WorldWideScience

Sample records for experiment h-mode plasmas

  1. H-mode plasmas at very low aspect ratio on the Pegasus Toroidal Experiment

    Science.gov (United States)

    Thome, K. E.; Bongard, M. W.; Barr, J. L.; Bodner, G. M.; Burke, M. G.; Fonck, R. J.; Kriete, D. M.; Perry, J. M.; Reusch, J. A.; Schlossberg, D. J.

    2017-02-01

    H-mode is obtained at A˜ 1.2 in the Pegasus Toroidal Experiment via Ohmic heating, high-field-side fueling, and low edge recycling in both limited and diverted magnetic topologies. These H-mode plasmas show the formation of edge current and pressure pedestals and a doubling of the energy confinement time to {{H}98y,2}˜ 1 . The L-H power threshold {{P}\\text{LH}} increases with density, and there is no {{P}\\text{LH}} minimum observed in the attainable density space. The power threshold is equivalent in limited and diverted plasmas, consistent with the FM3 model. However, the measured {{P}\\text{LH}} is ˜ 15 × higher than that predicted by conventional International Tokamak Physics Activity (ITPA) scalings, and {{P}\\text{LH}}/{{P}\\text{ITPA08}} increases as A\\to 1 . Small ELMs are present at low input power {{P}\\text{IN}}˜ {{P}\\text{LH}} , with toroidal mode number n≤slant 4 . At {{P}\\text{IN}}\\gg {{P}\\text{LH}} , they transition to large ELMs with intermediate 5. The dominant-n component of a large ELM grows exponentially, while other components evolve nonlinearly and can damp prior to the crash. Direct measurements of the current profile in the pedestal region show that both ELM types exhibit a generation of a current-hole, followed by a pedestal recovery. Large ELMs are shown to further expel a current-carrying filament. Small ELM suppression via injection of low levels of helical current into the edge plasma region is also indicated.

  2. Time-Dependent Simulations of Fast-Wave Heated High-Non-Inductive-Fraction H-Mode Plasmas in the National Spherical Torus Experiment Upgrade

    Science.gov (United States)

    Taylor, Gary; Bertelli, Nicola; Gerhardt, Stefan P.; Hosea, Joel C.; Mueller, Dennis; Perkins, Rory J.; Poli, Francesca M.; Wilson, James R.; Raman, Roger

    2017-10-01

    30 MHz fast-wave heating may be an effective tool for non-inductively ramping low-current plasmas to a level suitable for initiating up to 12 MW of neutral beam injection on the National Spherical Tokamak Experiment Upgrade (NSTX-U). Previously on NSTX 30 MHz fast wave heating was shown to efficiently and rapidly heat electrons; at the NSTX maximum axial toroidal magnetic field (BT(0)) of 0.55 T, 1.4 MW of 30 MHz heating increased the central electron temperature from 0.2 to 2 keV in 30 ms and generated an H-mode plasma with a non-inductive fraction (fNI) ˜ 0.7 at a plasma current (Ip) of 300 kA. NSTX-U will operate at BT(0) up to 1 T, with up to 4 MW of 30 MHz power (Prf). Predictive TRANSP free boundary transport simulations, using the TORIC full wave spectral code to calculate the fast-wave heating and current drive, have been run for NSTX-U Ip = 300 kA H-mode plasmas. Favorable scaling of fNI with 30 MHz heating power is predicted, with fNI ≥ 1 for Prf ≥ 2 MW.

  3. Dependence of various SOL widths on plasma current and density in NSTX H-mode plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, J; Maingi, R; Boedo, J; Soukhanovskii, V A

    2009-02-12

    The dependence of various SOL widths on the line-averaged density ({ovr n}{sub e}) and plasma current (l{sub p}) for the quiescent H-mode plasmas with Type-V ELMs in the National Spherical Torus Experiment (NSTX) was investigated. It is found that the heat flux SOL width ({lambda}{sub q}), measured by the IR camera, is virtually insensitive to {ovr n}{sub e} and has a strong negative dependence on l{sub p}. This insensitivity of {lambda}{sub q} to {ovr n}{sub e} is consistent with the scaling law from JET H-mode plasmas that shows a very weak dependence on the upstream density. The electron temperature, ion saturation current density, electron density, and electron pressure decay lengths ({lambda}{sub Te}, {lambda}{sub jsat}, {lambda}{sub ne}, and {lambda}{sub pe}, respectively) measured by the probe showed that {lambda}{sub Te} and {lambda}{sub jsat} have strong negative dependence on l{sub p}, whereas {lambda}{sub ne} and {lambda}{sub pe} revealed only a little or no dependence. The dependence of {lambda}{sub Te} on l{sub p} is consistent with the scaling law in the literature while {lambda}{sub ne} and {lambda}{sub pe} dependence shows a different trend.

  4. A study on the density shoulder formation in the SOL of H-mode plasmas

    Directory of Open Access Journals (Sweden)

    D. Carralero

    2017-08-01

    Full Text Available The term “shoulder formation” refers to an increase of the density decay length in the scrape-off layer (SOL observed in many tokamaks during L-mode operation when a density threshold is reached. Recent experiments in ASDEX Upgrade (AUG and JET have shown that the shoulder forms when the divertor collisionality in the divertor electrically disconnects filaments from the wall. This leads to a transition from the sheath limited to the inertial regime and to an enhancement of radial particle transport, in good agreement with analytical models. In the present work, the validity of such a mechanism is investigated in the more reactor-relevant H-mode regime. For this, a cold divertor H-mode scenario is developed in AUG using different levels of D puffing and N seeding, in which inter-ELM filaments and SOL density profiles are measured. The basic relation between filament size and divertor collisionality is still valid in H-mode plasmas, albeit an additional condition related to the gas fueling rate has been found for the formation of the shoulder.

  5. Plasma auto-biasing during Ohmic H-mode in the STOR-M tokamak

    Science.gov (United States)

    Zhang, W.; Xiao, C.; Hirose, A.

    1993-03-01

    Application of a short current pulse on a nominal Ohmic discharge in the STOR-M tokamak triggers the Ohmic H-mode characterized by reduced H sub alpha radiation, increased electron density, and reduced edge density/magnetic fluctuations. Measurements of plasma floating potential at the plasma edge and in the scrape-off layer indicate that the Ohmic H-mode is accompanied by negative plasma autobiasing which leads to a steeper radial electric field profile at the edge. Since the duration of the current pulse is shorter than the resistive skin time of about 1 ms, preferential edge heating is expected, which is believed to be responsible for changes in the edge discharge condition favorable for inducing the Ohmic H-mode. The electron density profile becomes steeper at the edge during the H-mode, and clear formation of a density pedestal has been seen. The evolution of the density profile suggests the presence of particle pinch. It is found that the electrostatic modes are dominant in the scrape-off layer while electromagnetic modes dominate in the main plasma. A similar H-mode is induced by external negative electrode biasing.

  6. Plasma autobiasing during Ohmic H-mode in the STOR-M tokamak

    Science.gov (United States)

    Zhang, W.; Xiao, C.; Hirose, A.

    1993-11-01

    Application of a short current pulse on a nominal Ohmic discharge in the STOR-M tokamak (Saskatchewan Torus-Modified) [Phys. Fluids B 4, 3277 (1992)] triggers the Ohmic H-mode characterized by reduced Hα radiation, increased electron density, and reduced edge density/magnetic fluctuations. Measurements of plasma floating potential at the plasma edge and in the scrape-off layer indicate that the Ohmic H-mode is accompanied by negative plasma autobiasing, which leads to a steeper radial electric field profile at the edge. Since the duration of the current pulse (≤20 kA, 100 μsec) is shorter than the resistive skin time (≂1 msec), preferential edge heating is expected, which is believed to be responsible for changes in the edge discharge condition favorable for inducing the Ohmic H-mode. The electron density profile becomes steeper at the edge during the H-mode, and clear formation of a density pedestal has been seen. The evolution of the density profile suggests the presence of particle pinch. An improved confinement phase (ICP) is induced by external negative electrode biasing. The ICP reveals some similarities as compared to the current pulse induced H-mode. It is found that the electrostatic modes are dominant in the scrape-off layer while electromagnetic modes dominate in the plasma edge during the normal Ohmic discharges.

  7. New Edge Coherent Mode Providing Continuous Transport in Long Pulse H-mode Plasmas

    DEFF Research Database (Denmark)

    Wang, H.Q.; Xu, G.S.; Wan, B.N.

    2014-01-01

    An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciproc......An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond......-coated reciprocating probes. The mode propagates in the electron diamagnetic direction in the plasma frame with poloidal wavelength of ∼8 cm. The mode drives a significant outflow of particles and heat as measured directly with the probes, thus greatly facilitating long pulse H-mode sustainment. This mode shows...

  8. Castellated tungsten plasma-facing components exposed to H-mode plasma in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.-H., E-mail: sukhhong@nfri.re.kr [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Department of Electrical Engineering, HanYang University, Seoul 133-791 (Korea, Republic of); Department of Accelerator and Nuclear Fusion Physics and Engineering, University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Lee, H.-H.; Kim, K.M.; Kim, H.T.; Bang, E.-N.; Son, S.H.; Kim, H.K. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)

    2016-11-01

    Highlights: • Heat load on the misaligned leading edges are studied by COMSOL analysis and infrared (IR) measurements in KSTAR. • 1–3 MW/m{sup 2} of heat flux has been deposited on the blocks during the inter-ELM (edge localized mode) phase in H-mode plasmas. • 1 mm leading edge under 3 MW/m{sup 2} reaches the recrystallization point within 2 s and will be melted within 30 s. • Shaped blocks show much better thermal response meaning that shaping of blocks enhances the heat load handling capability. • A simple COMSOL analysis describes qualitatively heat load patterns on the tungsten blocks of different shapes. - Abstract: Heat load on the misaligned leading edges of tungsten castellated blocks based on tungsten (W), oxygen-free high conductive copper (OFHC-Cu), and copper-chrome-zirconium (CuCrZr) alloy are studied by COMSOL analysis and infrared (IR) measurements in KSTAR. IR measurements show that 1–3 MW/m{sup 2} of heat flux has been deposited on the blocks during the inter-ELM (edge localized mode) phase in H-mode plasmas. COMSOL analysis indicates that the temperature of 1 mm leading edge in KSTAR under 3 MW/m{sup 2} would reach the recrystallization temperature within 2 s and will be melted within 30 s during a long pulse H-mode shot. Rounded and double chamfered blocks show much better thermal response meaning that shaping of divertor block enhances the heat load handling capability. It seems that a simple COMSOL analysis describes heat load patterns on the tungsten blocks of different shapes qualitatively well. Therefore, simple analysis would be useful to make a quick prediction on heat load patterns of blocks with arbitrary shapes.

  9. QUIESCENT DOUBLE BARRIER H-MODE PLASMAS IN THE DIII-D TOKAMAK

    Energy Technology Data Exchange (ETDEWEB)

    K.H. BURRELL; M.E. AUSTIN; D.P. BRENNAN; J.C. DeBOO; E.J. DOYLE; C. FENZI; C. FUCHS; P. GOHIL; R.J. GROEBNER; L.L. LAO; T.C. LUCE; M.A. MAKOWSKI; G.R. McKEE; R.A. MOYER; C.C. PETTY; M. PORKOLAB; C.L.RETTIG; T.L. RHODES; J.C. ROST; B.W. STALLARD; E.J. STRAIT; E.J. SYNAKOWSKI; M.R. WADE; J.G. WATKINS; W.P. WEST

    2000-11-01

    High confinement (H-mode) operation is the choice for next-step tokamak devices based either on conventional or advanced tokamak physics. This choice, however, comes at a significant cost for both the conventional and advanced tokamaks because of the effects of edge localized modes (ELMs). ELMs can produce significant erosion in the divertor and can affect the beta limit and reduced core transport regions needed for advanced tokamak operation. Experimental results from DIII-D [J.L. Luxon, et al., Plasma Phys. and Contr. Nucl. Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987) Vol. I, p. 159] this year have demonstrated a new operating regime, the quiescent H-mode regime, which solves these problems. We have achieved quiescent H-mode operation which is ELM-free and yet has good density and impurity control. In addition, we have demonstrated that an internal transport barrier can be produced and maintained inside the H-mode edge barrier for long periods of time (>3.5 seconds or >25 energy confinement times {tau}{sub E}), yielding a quiescent double barrier regime. By slowly ramping the input power, we have achieved {beta}{sub N} H{sub 89} = 7 for up to 5 times the {tau}{sub E} of 150 ms. The {beta}{sub N} H{sub 89} values of 7 substantially exceed the value of 4 routinely achieved in standard ELMing H-mode. The key factors in creating the quiescent H-mode operation are neutral beam injection in the direction opposite to the plasma current (counter injection) plus cryopumping to reduce the density. Density and impurity control in the quiescent H-mode is possible because of the presence of an edge magnetic hydrodynamic (MHD) oscillation, the edge harmonic oscillation, which enhances the edge particle transport while leaving the energy transport unaffected.

  10. Highly radiating type-III ELMy H-mode with low plasma core pollution

    NARCIS (Netherlands)

    Rapp, J.; M.R. de Baar,; Fundamenski, W.; Brix, M.; Felton, R.; Giroud, C.; Huber, A.; Jachmich, S.; Joffrin, E.; Nunes, I.; van Rooij, G. J.; Stamp, M.; Telesca, G.; Zagorski, R.

    2009-01-01

    The impurity seeded type-III ELMy H-mode is proposed as an integrated ITER scenario. At JET this scenario has been demonstrated up to plasma currents of 3 MA with nitrogen as seeding gas. Detached divertor operation is achieved with significantly reduced steady state and transient heat fluxes. By

  11. Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

    Science.gov (United States)

    Hong, Joohwan; Henderson, S. S.; Kim, Kimin; Seon, C. R.; Song, Inwoo; Lee, H. Y.; Jang, Juhyeok; Park, Jae Sun; Lee, S. G.; Lee, J. H.; Lee, Seung Hun; Hong, Suk-Ho; Choe, Wonho

    2017-03-01

    Experiments with a small amount of Ar gas injection as a trace impurity were conducted in the Korea Superconducting Tokamak Advanced Research (KSTAR) H-mode plasma ({{B}\\text{T}}   =  2.8 T, {{I}\\text{P}}   =  0.6 MA, and {{P}\\text{NBI}}   =  4.0 MW). 170 GHz electron cyclotron resonance heating (ECH) at 600 and 800 kW was focused along the mid-plane with a fixed major radial position of R   =  1.66 m. The emissivity of the Ar16+ (3.949 {\\mathring{\\text{A}}} ) and Ar15+ (353.860 {\\mathring{\\text{A}}} ) spectral lines were measured by x-ray imaging crystal spectroscopy (XICS) and a vacuum UV (VUV) spectrometer, respectively. ECH reduces the peak Ar15+ emission and increases the Ar16+ emission, an effect largest with 800 kW. The ADAS-SANCO impurity transport code was used to evaluate the Ar transport coefficients. It was found that the inward convective velocity found in the plasma core without ECH was decreased with ECH, while diffusion remained approximately constant resulting in a less-peaked Ar density profile. Theoretical results from the NEO code suggest that neoclassical transport is not responsible for the change in transport, while the microstability analysis using GKW predicts a dominant ITG mode during both ECH and non-ECH plasmas.

  12. Quiescent Double Barrier H-Mode Plasmas in the DIII-D Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Burrell, K H; Austin, M E; Brennan, D P; DeBoo, J C; Doyle, E J; Fenzi, C; Fuchs, C; Gohil, P; Greenfield, C M; Groebner, R J; Lao, L L; Luce, T C; Makowski, M A; McKee, G R; Moyer, R A; Petty, C C; Porkolab, M; Rettig, C L; Rhodes, T L; Rost, J C; Stallard, B W; Strait, E J; Synakowski, E J; Wade, M R; Watkins, J G; West, W P

    2000-11-01

    High confinement (H-mode) operation is the choice for next-step tokamak devices based either on conventional or advanced tokamak physics. This choice, however, comes at a significant cost for both the conventional and advanced tokamaks because of the effects of edge localized modes (ELMs). ELMs can produce significant erosion in the divertor and can affect the beta limit and reduced core transport regions needed for advanced tokamak operation. Experimental results from DIII-D this year have demonstrated a new operating regime, the quiescent H-mode regime, which solves these problems. We have achieved quiescent H-mode operation which is ELM-free and yet has good density and impurity control. In addition, we have demonstrated that an internal transport barrier can be produced and maintained inside the H-mode edge barrier for long periods of time (>3.5 seconds or >25 energy confinement times {tau}{sub E}), yielding a quiescent double barrier regime. By slowly ramping the input power, we have achieved {beta}{sub N} H89 = 7 for up to 5 times the {tau}{sub E} of 150 ms. The {beta}{sub N} H89 values of 7 substantially exceed the value of 4 routinely achieved in standard ELMing H-mode. The key factors in creating the quiescent H-mode operation are neutral beam injection in the direction opposite to the plasma current (counter injection) plus cryopumping to reduce the density. Density and impurity control in the quiescent H-mode is possible because of the presence of an edge magnetic hydrodynamic (MHD) oscillation, the edge harmonic oscillation, which enhances the edge particle transport while leaving the energy transport unaffected.

  13. Modelling of transitions between L- and H-mode in JET high plasma current plasmas and application to ITER scenarios including tungsten behaviour

    Science.gov (United States)

    Koechl, F.; Loarte, A.; Parail, V.; Belo, P.; Brix, M.; Corrigan, G.; Harting, D.; Koskela, T.; Kukushkin, A. S.; Polevoi, A. R.; Romanelli, M.; Saibene, G.; Sartori, R.; Eich, T.; Contributors, JET

    2017-08-01

    The dynamics for the transition from L-mode to a stationary high Q DT H-mode regime in ITER is expected to be qualitatively different to present experiments. Differences may be caused by a low fuelling efficiency of recycling neutrals, that influence the post transition plasma density evolution on the one hand. On the other hand, the effect of the plasma density evolution itself both on the alpha heating power and the edge power flow required to sustain the H-mode confinement itself needs to be considered. This paper presents results of modelling studies of the transition to stationary high Q DT H-mode regime in ITER with the JINTRAC suite of codes, which include optimisation of the plasma density evolution to ensure a robust achievement of high Q DT regimes in ITER on the one hand and the avoidance of tungsten accumulation in this transient phase on the other hand. As a first step, the JINTRAC integrated models have been validated in fully predictive simulations (excluding core momentum transport which is prescribed) against core, pedestal and divertor plasma measurements in JET C-wall experiments for the transition from L-mode to stationary H-mode in partially ITER relevant conditions (highest achievable current and power, H 98,y ~ 1.0, low collisionality, comparable evolution in P net/P L-H, but different ρ *, T i/T e, Mach number and plasma composition compared to ITER expectations). The selection of transport models (core: NCLASS  +  Bohm/gyroBohm in L-mode/GLF23 in H-mode) was determined by a trade-off between model complexity and efficiency. Good agreement between code predictions and measured plasma parameters is obtained if anomalous heat and particle transport in the edge transport barrier are assumed to be reduced at different rates with increasing edge power flow normalised to the H-mode threshold; in particular the increase in edge plasma density is dominated by this edge transport reduction as the calculated neutral influx across the

  14. Configuration and Heating Power Dependence of Edge Parameters and H-mode Dynamics in National Spherical Torus Experiment (NSTX)

    Energy Technology Data Exchange (ETDEWEB)

    C.E. Bush; M.G. Bell; R.E. Bell; J. Boedo; E.D. Fredrickson; S.M. Kaye; S. Kubota; B.P. LeBlanc; R. Maingi; R.J. Maqueda; S.A. Sabbagh; V.A. Soukhanovskii; D. Stutman; D.W. Swain; J.B. Wilgen; S.J. Zweben; W.M. Davis; D.A. Gates; D.W. Johnson; R. Kaita; H.W. Kugel; D. Mastrovito; S. Medley; J.E. Menard; D. Mueller; M. Ono; F. Paoletti; S.J. Paul; Y-K.M. Peng; R. Raman; P.G. Roney; A.L. Roquemore; C.H. Skinner; E.J. Synakowski; G. Taylor; the NSTX Team

    2003-01-09

    Edge parameters play a critical role in H-mode (high-confinement mode) access, which is a key component of plasma discharge optimization in present-day toroidal confinement experiments and the design of next-generation devices. Because the edge magnetic topology of a spherical torus (ST) differs from a conventional aspect ratio tokamak, H-modes in STs exhibit important differences compared with tokamaks. The dependence of the NSTX (National Spherical Torus Experiment) edge plasma on heating power, including the L-H transition requirements and the occurrence of edge-localized modes (ELMs), and on divertor configuration is quantified. Comparisons between good L-modes (low-confinement modes) and H-modes show greater differences in the ion channel than the electron channel. The threshold power for the H-mode transition in NSTX is generally above the predictions of a recent ITER (International Thermonuclear Experimental Reactor) scaling. Correlations of transition and ELM phenomena with turbulent fluctuations revealed by Gas Puff Imaging (GPI) and reflectometry are observed. In both single-null and double-null divertor discharges, the density peaks off-axis, sometimes developing prominent ''ears'' which can be sustained for many energy confinement times, tau subscript ''E'', in the absence of ELMs. A wide variety of ELM behavior is observed, and ELM characteristics depend on configuration and fueling.

  15. Access to a New Plasma Edge State with High Density and Pressures using Quiescent H-mode

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, Wayne M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Snyder, P. B. [General Atomics, San Diego, CA (United States); Burrell, K. H. [General Atomics, San Diego, CA (United States); Fenstermacher, M. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Garofalo, A. M. [General Atomics, San Diego, CA (United States); Grierson, B. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Loarte, A. [ITER Organization, St. Paul Lez Durance (France); McKee, G. R. [Univ. of Wisconsin, Madison, WI (United States); Nazikian, R [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Osborne, T. H. [General Atomics, San Diego, CA (United States)

    2014-07-01

    A path to a new high performance regime has been discovered in tokamaks that could improve the attractiveness of a fusion reactor. Experiments on DIII-D using a quiescent H-mode edge have navigated a valley of improved edge peeling-ballooning stability that opens up with strong plasma shaping at high density, leading to a doubling of the edge pressure over standard edge localized mode (ELM)ing H-mode at these parameters. The thermal energy confinement time increases both as a result of the increased pedestal height and improvements in the core transport and reduced low-k turbulence. Calculations of the pedestal height and width as a function of density using constraints imposed by peeling-ballooning and kinetic-ballooning theory are in quantitative agreement with the measurements.

  16. Power requirements for superior H-mode confinement on Alcator C-Mod: experiments in support of ITER

    Science.gov (United States)

    Hughes, J. W.; Loarte, A.; Reinke, M. L.; Terry, J. L.; Brunner, D.; Greenwald, M.; Hubbard, A. E.; LaBombard, B.; Lipschultz, B.; Ma, Y.; Wolfe, S.; Wukitch, S. J.

    2011-08-01

    Power requirements for maintaining sufficiently high confinement (i.e. normalized energy confinement time H98 >= 1) in H-mode and its relation to H-mode threshold power scaling, Pth, are of critical importance to ITER. In order to better characterize these power requirements, recent experiments on the Alcator C-Mod tokamak have investigated H-mode properties, including the edge pedestal and global confinement, over a range of input powers near and above Pth. In addition, we have examined the compatibility of impurity seeding with high performance operation, and the influence of plasma radiation and its spatial distribution on performance. Experiments were performed at 5.4 T at ITER relevant densities, utilizing bulk metal plasma facing surfaces and an ion cyclotron range of frequency waves for auxiliary heating. Input power was scanned both in stationary enhanced Dα (EDA) H-modes with no large edge localized modes (ELMs) and in ELMy H-modes in order to relate the resulting pedestal and confinement to the amount of power flowing into the scrape-off layer, Pnet, and also to the divertor targets. In both EDA and ELMy H-mode, energy confinement is generally good, with H98 near unity. As Pnet is reduced to levels approaching that in L-mode, pedestal temperature diminishes significantly and normalized confinement time drops. By seeding with low-Z impurities, such as Ne and N2, high total radiated power fractions are possible, along with substantial reductions in divertor heat flux (>4×), all while maintaining H98 ~ 1. When the power radiated from the confined versus unconfined plasma is examined, pedestal and confinement properties are clearly seen to be an increasing function of Pnet, helping to unify the results with those from unseeded H-modes. This provides increased confidence that the power flow across the separatrix is the correct physics basis for ITER extrapolation. The experiments show that Pnet/Pth of one or greater is likely to lead to H98 >= 1 operation

  17. Particle and power deposition on divertor targets in EAST H-mode plasmas

    DEFF Research Database (Denmark)

    Wang, L.; Xu, G.S.; Guo, H.Y.

    2012-01-01

    ELMs were chosen for analysis in order to reduce the uncertainty resulting from the influence of fast electrons on Langmuir triple-probe evaluation during ELMs. The power deposition obtained from Langmuir triple probes was consistent with that from the divertor infra-red camera during an ELM-free...... significantly broadening the SOL width and plasma-wetted area on the divertor target in both LHCD and LHCD + ICRH H-modes, thus posing a great challenge for the next-step high-power, long-pulse operation in EAST. Increasing the divertor-wetted area was also observed to reduce the peak heat flux and particle...

  18. Generation of Non-Inductive H-Mode Plasmas with 30 MHz Fast Wave Heating in NSTX-U

    Science.gov (United States)

    Taylor, G.; Bertelli, N.; Gerhardt, S. P.; Hosea, J. C.; Mueller, D.; Perkins, R. J.; Poli, F. M.; Wilson, J. R.; Raman, R.

    2016-10-01

    A Fusion Nuclear Science Facility based on a spherical tokamak must generate the plasma current (Ip) with little or no central solenoid field. The NSTX-U non-inductive (NI) plasma research program is addressing this goal by developing NI start-up, ramp-up and sustainment scenarios separately. 4 MW of 30 MHz fast wave power is predicted to ramp Ip to 400 kA, a level sufficient to avoid significant shine-through of 90 keV ions from neutral beam injection. In 2010, experiments in NSTX demonstrated that 1.4 MW of 30 MHz high-harmonic fast wave (HHFW) power could generate an Ip = 300 kA H-mode discharge with a NI Ip fraction, fNI, around 0.7 at the maximum axial toroidal field (BT(0)) in NSTX of 0.55 T. NSTX-U is a major upgrade of NSTX that will eventually allow the generation of plasmas with BT(0) up to 1 T. Full wave simulations of 30 MHz HHFW heating in NSTX-U predict reduced FW power loss in the plasma edge as BT(0) is increased. HHFW experiments this year aim to couple 3 - 4 MW of 30 MHz HHFW power into an Ip = 250 - 350 kA plasma with BT(0) up to 0.75 T to generate a fNI = 1 H-mode plasma. These experiments should benefit from the improved fast wave coupling predicted at higher BT(0) in NSTX-U. Work supported by USDOE Contract No. DE-AC02-09CH11466.

  19. Modeling of argon seeding in ASDEX Upgrade H-mode plasma with SOLPS5.0

    Directory of Open Access Journals (Sweden)

    L.Y. Xiang

    2017-08-01

    Full Text Available SOLPS modeling of Ar seeding in ASDEX Upgrade H-mode plasma shows that the divertor compression of Ar increases with the seeding rate when the inner divertor is detached and the outer divertor is attached. This results from the redistribution of the Ar density as the inner divertor detaches. During the detachment of the inner divertor, the parallel friction and thermal forces on Ar increase in the inner divertor and decrease in the outer divertor. The net force of the two directs Ar from the low field side to the high field side of the plasma along the field line. The net force is found to be stronger after the detachment of the inner divertor in the simulation. Although the divertor compression of Ar increases, the ratio of radiated power by Ar inside the divertor over that inside the separatrix does not increase after the detachment. This is because the radiation efficiency, i.e. the radiated per Ar particle on average decreases with the seeding rate in the divertor and increases inside the separatrix. The radiation efficiency in the simulation is determined by the characteristic cooling curve of Ar and the transport effects.

  20. Comparison of MHD simulation codes for understanding nonlinear ELMs dynamics in KSTAR H-mode plasma

    Science.gov (United States)

    Kim, M.; Lee, J.; Park, H. K.; Yun, G. S.; Xu, X.; Jardin, S. C.; Becoulet, M.

    2017-10-01

    KSTAR electron cyclotron emission imaging (ECEI) systems have contributed to understanding the fundamental physics of ELMs by high-quality 2D and quasi-3D images of ELMs. However, in the highly nonlinear phase of ELM dynamics, the interpretation of ECE signals becomes complicated intrinsically. Theoretical and numerical approaches are necessary to enhance the understanding of ELM physics. Well-established MHD codes (BOUT + + , JOREK, and M3D-C1) are introduced for comparative study with the observations. The nonlinear solutions are obtained using the same equilibrium of the KSTAR H-mode plasma. Each code shows the partial difference in mode evolution, probably, due to the difference in optimized operation window of initial conditions. The nonlinear simulation results show that low- n (n < 5) modes becomes dominant close to pedestal collapse. The mode evolution in the simulations qualitatively matches with the recent ECEI observation just before ELM-crash, or excitation of non-modal solitary perturbation (typically, n = 1) which is highly localized in poloidal and toroidal. Regardless of differences in details, qualitative similarity can provide inspiration to understand the triggering of ELM-crash. This work is supported by NRF of Korea under Contract No. NRF-2014M1A7A1A03029865.

  1. Dynamics and stability of divertor detachment in H-mode plasmas on JET

    Science.gov (United States)

    Field, A. R.; Balboa, I.; Drewelow, P.; Flanagan, J.; Guillemaut, C.; Harrison, J. R.; Huber, A.; Huber, V.; Lipschultz, B.; Matthews, G.; Meigs, A.; Schmitz, J.; Stamp, M.; Walkden, N.; contributors, JET

    2017-09-01

    The dynamics and stability of divertor detachment in {{{N}}}2 seeded, type-I, ELMy H-mode plasmas with dominant NBI heating in the JET ITER-like wall device is studied by means of an integrated analysis of diagnostic data from several systems, classifying data relative to the ELM times. It is thereby possible to study the response of the detachment evolution to the control parameters (SOL input power, upstream density and impurity fraction) prevailing during the inter-ELM periods and the effect of ELMs on the detached divertor. A relatively comprehensive overview is achieved, including the interaction with the targets at various stages of the ELM cycle, the role of ELMs in affecting the detachment process and the overall performance of the scenario. The results are consistent with previous studies in devices with an ITER-like, metal wall, with the important advance of distinguishing data from intra- and inter-ELM periods. Operation without significant degradation of the core confinement can be sustained in the presence of strong radiation from the x-point region (MARFE).

  2. ELM Size & ν⊥ e ~ 0 Location During RMP H-mode Plasmas in DIII-D

    Science.gov (United States)

    Fenstermacher, M. E.; Moyer, R. A.; Osborne, T. H.

    2011-10-01

    Previous studies, examined the correlation between vacuum island overlap region width and edge localized mode (ELM) size during n = 3 resonant magnetic perturbations (RMPs) in DIII-D. For rotating H-mode plasmas it was proposed, that the resonant perturbation components would be screened by plasma response except at locations with the sum of the electron diamagnetic and E × B velocities, ν⊥ e = 0 . One hypothesis for the mechanism of RMP ELM suppression is that the pedestal width is prevented from expanding to the peeling-ballooning instability boundary by plasma modes at a location where vacuum RMP fields penetrate. This would suggest that the ν⊥ e = 0 location would be closer to the plasma edge during ELM suppression than during ELM mitigation. This paper will examine the degree of correlation between ν⊥ e = 0 location and ELM size during RMP H-mode plasmas including those from the previous studies. Work supported by the US DOE under DE-AC52-07NA27344 and DE-FC02-04ER54698.

  3. High Power Fast Wave Coupling and Heating in H-mode Plasmas on DIII-D

    Science.gov (United States)

    Pinsker, R. I.; Buttery, R. J.; Luce, T. C.; Porkolab, M.; Diem, S.; Kaufman, M.; Ryan, P. M.; Hosea, J. C.; Nagy, A.; Perkins, R.; Solomon, W. M.; Maggiora, R.; Milanesio, D.

    2012-10-01

    Up to 2.5 MW of fast wave (FW) heating power has been coupled to the core of ELMing H-mode discharges with βN<=2.5 in conjunction with 3-7 MW of neutral beam injection and 2.6 MW of electron cyclotron heating. Core FW heating efficiency has been found experimentally to approach 100% in the Advanced Inductive regime, consistent with the excellent absorption predicted by ray-tracing models in this high βe regime. Low antenna loading (high rf voltages) characteristic of such regimes makes increasing the FW power challenging. A study of techniques to enhance FW antenna loading has been carried out in DIII-D, with emphasis on maintenance of good confinement. The loading is in absolute agreement with modeling when edge density profiles measured with reflectometry are used in the model. Recent work extending the range of H-mode regimes to which FW heating has been applied and on increasing the FW power coupled to those regimes is described.

  4. Study of density fluctuation in L-mode and H-mode plasmas on JFT-2M by microwave reflectometer

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, Kouji [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1997-08-01

    We propose the model which can explain the runaway phase. The model takes account of the scattered wave which is caused by the density fluctuation near the cut-off layer. We should take a new approach instead of the conventional phase measurement in order to derive the information of the density fluctuation from the data with the runaway phase. The complex spectrum and the rotary spectrum analyses are useful tools to analyze such data. The density fluctuation in L-mode and H-mode plasmas is discussed by using this new approach. We have observed that the reduction of the density fluctuation is localized in the edge region where the sheared electric field is produced. The fluctuations in the range of frequency lower than 100 kHz are mainly reduced. Two interesting features have been observed. One is the detection of the coherent mode around 100 kHz in H-mode. This mode appears about 10 ms after L to H transition. The timing corresponds to the formation of a steep density and temperature gradient in the edge region. The other is the enhancement of the fluctuations with the frequency higher than 300 kHz in H-mode in contrast to the reduction of the fluctuations with the frequency lower than 100 kHz. The Doppler shift is observed in the complex auto-power spectrum of the reflected wave when the plasma is actively moved. We have confirmed that the movement of the plasma is appropriately measured by using the low pass filter. The reflectometer can be used to measure the density profile by using a low pass filter even when the runaway phase phenomenon occurs. (author). 150 refs.

  5. Possible influence of near SOL plasma on the H-mode power threshold

    Directory of Open Access Journals (Sweden)

    A.V. Chankina

    2017-08-01

    Full Text Available A strong effect of divertor configuration on the threshold power for the L-H transition (PLH was observed in recent JET experiments in the new ITER-like Wall (ILW [1–3]. Following a series of EDGE2D-EIRENE code simulations with Be impurity and drifts a possible mechanism for the PLH variation with the divertor geometry is proposed. Both experiment and code simulations show that in the configuration with lower neutral recycling near the outer strike point (OSP, electron temperature (Te peaks near the OSP prior to the L-H transition, while in the configuration with higher OSP recycling Te peaks further out in the scrape-off layer (SOL and the plasma stays in the L-mode at the same input power. Code results show large positive radial electric field (Er in the near SOL under lower recycling conditions leading to a large E×B shear across the separatrix which may trigger earlier (at lower input power edge turbulence suppression and lower PLH. Suppressed Te‘s at OSP in configurations with strike points on vertical targets (VT were observed earlier and explained by a geometrical effect of neutral recycling near this particular position, whereas in configurations with strike points on horizontal targets (HT the OSP appears to be more open for neutrals (see e.g. review paper [4].

  6. Dynamical Evolution of Pedestal Parameters in ELMy H-mode in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, A; Kubota, S; Sontag, A; Osborne, T; Podesta, M; Bell, R E; LeBlanc, B P; Menard, J

    2011-07-27

    Characterizations of the pedestal parameter dynamics throughout the edge localized modes(ELM) cycles are performed on the National Spherical Torus Experiment (NSTX, [M. Ono et al., Nucl. Fusion 40, 557 (2000)]). A clear buildup of the pedestal height is observed between ELMs for three di erent plasma currents, which tends to saturate prior to the onset of ELM at low and medium plasma current. Similarly, the pedestal width increases with no clear evidence of saturation during an ELM cycle. The maximum pedestal gradient increases as a function of plasma current, reaches a nominal value after the ELM crash, and remains constant until the end of the ELM cycle. The pedestal height just prior to the onset of ELM is shown to increase quadratically with plasma current. The pedestal width Δ is proportional to the square-root of the poloidal Β at the top of the pedestal. Coherent density uctuations strongly increasing at the plasma edge are observed to be maximum after the ELM crash and to decay during the rest of the ELM cycle. Finally, the pedestal parameters evolution during the ELM cycle as well as the scaling with Ip of the pedestal pressure prior to the onset ELM are found to be qualitatively consistent with the peeling ballooning theory.

  7. Understanding ECH density pump-out in DIII-D H-mode plasmas

    Science.gov (United States)

    Wang, X.; Mordijck, S.; Doyle, E. J.; Rhodes, T. L.; Zeng, L.; McKee, G. R.; Austin, M. E.; Meneghini, O.; Staebler, G. M.; Smith, S. P.

    2017-11-01

    In this paper, we show that the often observed ‘density pump-out’ with electron cyclotron heating (ECH) (Angioni et al 2004 Nucl. Fusion 44 827, 2009 Plasma Phys. Control. Fusion 51 124017), at low density and/or collisionality is the result of an increase in turbulence drive at the plasma edge (Angioni et al 2004 Nucl. Fusion 44 827, 2005 Phys. Plasmas 12 040701, Mordijck et al 2015 Nucl. Fusion 43 113025). Prior results were limited to comparison of steady-state conditions, before and after the ECH was applied, and thus failed to capture the dynamics of the density pump-out. In this paper, we find, similar to prior results, that when the plasma reaches a new equilibrium after ECH is applied, gyro-kinetic simulations indicate that the plasma has transitioned from the ion temperature gradient (ITG) to a trapped electron mode (TEM) regime around mid-radius. However, this transition from ITG to TEM only occures in the core after 100 ms. The pump-out on the other hand, starts immediately and is strongest around ρ ∼ 0.8 . Linear gyrokinetic simulations with TGLF show that there is an increase in turbulence drive simultaneously with the density pump-out and the doppler backscattering (DBS) measures an instant increase in density fluctuations at the same radial location. On the other hand, around mid-radius the DBS measures no increase in density fluctuations. All these calculations along with experimental measurements show that the density pump-out is not the result of a change in turbulence type (i.e. not caused by a change from ITG to TEM), but the result of a change in turbulence drive (an increase in linear growth rates), which is later followed by the ITG to TEM transition. This highlights the need for studying not just the equilibrium conditions after a transition, but also the time-dependent changes.

  8. Multi-scale gyrokinetic simulations of an Alcator C-Mod, ELM-y H-mode plasma

    Science.gov (United States)

    Howard, N. T.; Holland, C.; White, A. E.; Greenwald, M.; Rodriguez-Fernandez, P.; Candy, J.; Creely, A. J.

    2018-01-01

    High fidelity, multi-scale gyrokinetic simulations capable of capturing both ion ({k}θ {ρ }s∼ { O }(1.0)) and electron-scale ({k}θ {ρ }e∼ { O }(1.0)) turbulence were performed in the core of an Alcator C-Mod ELM-y H-mode discharge which exhibits reactor-relevant characteristics. These simulations, performed with all experimental inputs and realistic ion to electron mass ratio ({({m}i/{m}e)}1/2=60.0) provide insight into the physics fidelity that may be needed for accurate simulation of the core of fusion reactor discharges. Three multi-scale simulations and series of separate ion and electron-scale simulations performed using the GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) are presented. As with earlier multi-scale results in L-mode conditions (Howard et al 2016 Nucl. Fusion 56 014004), both ion and multi-scale simulations results are compared with experimentally inferred ion and electron heat fluxes, as well as the measured values of electron incremental thermal diffusivities—indicative of the experimental electron temperature profile stiffness. Consistent with the L-mode results, cross-scale coupling is found to play an important role in the simulation of these H-mode conditions. Extremely stiff ion-scale transport is observed in these high-performance conditions which is shown to likely play and important role in the reproduction of measurements of perturbative transport. These results provide important insight into the role of multi-scale plasma turbulence in the core of reactor-relevant plasmas and establish important constraints on the the fidelity of models needed for predictive simulations.

  9. Turbulence at the transition to the high density H-mode in Wendelstein 7-AS plasmas

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Baumel, S.

    2003-01-01

    Recently a new improved confinement regime was found in the Wendelstein 7-AS (W7-AS) stellarator (Renner H. et al 1989 Plasma Phys. Control. Fusion 31 1579). The discovery of this high density high confinement mode (HDH-mode) was facilitated by the installation of divertor modules. In this paper......, measurements of short wavelength density fluctuations in the HDH-mode using collective scattering of infrared light are presented. These measurements will be contrasted to fluctuations during normal confinement operation (NC-mode). The autopower spectra of the measurements show a consistent increase...... of the fluctuation level associated with the transition from NC- to HDH-mode. Correlation calculations on a 20 mus timescale between magnetic and density fluctuations lead to the result that the fluctuations are correlated in NC- but not in HDH-mode. Finally, a comparative analysis between the enhanced D-alpha H...

  10. Discovery of Stationary Operation of Quiescent H-mode Plasmas with Net-Zero NBI Torque and High Energy Confinement on DIII-D

    Science.gov (United States)

    Burrell, Keith

    2015-11-01

    Experiments this summer in DIII-D have used edge turbulence control to achieve stationary, high confinement operation without Edge Localized Mode (ELM) instabilities and with no external torque input. Eliminating the ELM-induced heat bursts and controlling plasma stability at low rotation represent two of the great challenges for fusion energy. By exploiting edge turbulence in a novel manner, we achieved outstanding tokamak performance, well above the H98 international tokamak energy confinement scaling (H98 =1.25), thus meeting an additional confinement challenge that is usually difficult at low torque. The new regime is triggered in double null plasmas by ramping the injected torque to zero and then maintaining it there. This lowers ExB rotation shear in the plasma edge, allowing low-k, broadband, electromagnetic turbulence to increase. In the H-mode edge, a narrow transport barrier usually grows until MHD instability (a peeling ballooning mode) leads to the ELM heat burst. However, the increased turbulence reduces the pressure gradient, allowing the development of a broader and thus higher transport barrier. A 60% increase in pedestal pressure and 40% increase in energy confinement result. Strong double-null plasma shaping raises the threshold for the ELM instability, allowing the plasma to reach a transport-limited state near but below the explosive ELM stability boundary. The resulting plasmas have burning-plasma-relevant betan =1.6-1.8 and run without the need for extra torque from 3D magnetic fields. To date, stationary conditions have been produced for 2 s or 12 energy confinement times, limited only by external hardware constraints. Stationary operation with improved pedestal conditions is highly significant for future burning plasma devices, since operation without ELMs at low rotation and good confinement is key for fusion energy production. Supported by the US DOE under DE-FC02-04ER54698.

  11. Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection

    DEFF Research Database (Denmark)

    Valisa, M.; Carraro, L.; Predebon, I.

    2011-01-01

    The scan of ion cyclotron resonant heating (ICRH) power has been used to systematically study the pump out effect of central electron heating on impurities such as Ni and Mo in H-mode low collisionality discharges in JET. The transport parameters of Ni and Mo have been measured by introducing a t...

  12. Comparison of H-mode plasma simulations using toroidal velocity models depending on plasma current density and ion temperature in presence of an ITB

    Directory of Open Access Journals (Sweden)

    Boonyarit Chatthong

    2014-06-01

    Full Text Available Two different approaches for predicting plasma toroidal velocity (v are developed and used in self-consistent simulations of H-mode plasmas with the presence of ITB using BALDUR integrated predictive modelling code. In the first approach, the toroidal velocity depends on the plasma current density; while in the second approach the toroidal velocity is directly proportional to the ion temperature. The profile of v is used to calculate the ExB flow shear which is a main mechanism for plasma transport suppression, leading to the ITB formation. In all simulations, the core transport model is a combination of NCLASS neoclassical transport and semi-empirical Mixed Bohm/gyro-Bohm model that includes the ITB effects. The boundary condition is set at top of the pedestal and is estimated using a pedestal model based on a combination of magnetic and flow shear stabilization pedestal width scaling and an infinite-n ballooning pressure gradient. Two toroidal velocity models are used to simulate the time evolution of plasma temperature and density profiles of 10 JET discharges. The root mean square error (RMSE is used to compare simulation results of those 10 JET discharges with experimental data. It is found that RMSE of Ti , Te , ne are 28.1%, 31.8%, and 15.0% for the first toroidal velocity model and 25.5%, 30.2%, and 15.1% for the second toroidal velocity model, respectively. Furthermore, this suite of codes is used to predict the ITER performance under standard type I ELMy H-mode. It is found that the simulation yields formation of a narrow ITB near r/a = 0.7 in the simulation using the current density dependent model and a wide ITB from r/a = 0.5 to 0.8 in the simulation using the ion temperature dependent model. The average of central ion temperature, total fusion power output and alpha power are predicted to be 36 keV, 159 MW and 492 MW for the current density dependent model and 49 keV, 218 MW and 786 MW for the ion temperature dependent

  13. Deuterium charge exchange recombination spectroscopy from the top of the pedestal to the scrape off layer in H-mode plasmas

    Science.gov (United States)

    Haskey, S. R.; Grierson, B. A.; Stagner, L.; Burrell, K. H.; Chrystal, C.; Groebner, R. J.; Ashourvan, A.; Pablant, N. A.

    2017-10-01

    Recent completion of the thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on DIII-D [J.L. Luxon, Nucl. Fusion 42 (2002) 614] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the edge, providing high resolution measurements of the pedestal and steep gradient edge region of H-mode plasmas. The complexities of the Dα spectrum require fitting with a comprehensive model, as well as using iterative collisional radiative modeling to determine the underlying thermal deuterium ion properties. Large differences in the structure and magnitude of impurity (C6+) and main-ion (D+) toroidal rotation profiles are seen in the H-mode pedestal. Additionally the D+ temperature can be half the value of the C6+ temperature at the separatrix and shows more of a pedestal structure. Typically only the impurity properties are measured and the main-ion properties are either assumed to be the same, or inferred using neoclassical models, which require validation in the steep gradient region. These measured differences have implications for transport model validation, intrinsic rotation studies, pedestal stability, and the boundary conditions for scrape off layer and plasma material interactions studies.

  14. Two-Dimensional Visualization of Growth and Burst of the Edge-Localized Filaments in KSTAR H-Mode Plasmas

    NARCIS (Netherlands)

    Yun, G. S.; Lee, W.; Choi, M. J.; Lee, J.; Park, H. K.; Tobias, B.; Domier, C.W.; N C Luhmann Jr.,; Donne, A. J. H.; Lee, J. H.

    2011-01-01

    The filamentary nature and dynamics of edge-localized modes (ELMs) in the KSTAR high-confinement mode plasmas have been visualized in 2D via electron cyclotron emission imaging. The ELM filaments rotating with a net poloidal velocity are observed to evolve in three distinctive stages: initial linear

  15. UF-CHERS Measurements of Ion Temperature and Toroidal Rotation Fluctuations Associated with the Edge Harmonic Oscillation in Quiescent H-mode Plasmas

    Science.gov (United States)

    Truong, D. D.; Fonck, R. J.; McKee, G. R.; Yan, Z.; Grierson, B. A.

    2016-10-01

    The UF-CHERS (Ultra Fast CHarge Exchange Recombination Spectroscopy) diagnostic at DIII-D measures local, long-wavelength ion temperature and toroidal velocity fluctuations at turbulence-relevant spatiotemporal scales from emission of the CVI n=8 ->7 transition. During Quiescent H-mode (QH-mode) plasmas, which offer ELM-free improved confinement, UF-CHERS measurements observed coherent, low frequency (fo 10kHz) pedestal oscillations in Ti and vtor at the Edge Harmonic Oscillation (EHO) frequency while several modes between 35-75 kHz are suppressed when the EHO appears. Although broadband ion temperature and density fluctuations were reduced by the EHO, the toroidal rotation showed increased fluctuation amplitude. Investigating ion temperature and toroidal fluctuations associated with the EHO may provide insights into the saturated instability driving the EHO. Supported by DOE Grants DE-FG02-08ER54999, DE-FC02-04ER54698, and NSF GRFP Grant DGE-1256259.

  16. THE ROLE OF NEUTRALS IN H-MODE PEDESTAL FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    R.J. GROEBNER; M.A. MAHDAVI; A.W. LEONARD; T.H. OSBORNE; G.D. PORTER; R.J. COLCHIN; L.W.OWEN

    2001-11-01

    An analytic model, derived from coupled continuity equations for the electron and neutral deuterium densities, is consistent with many features of edge electron density profiles in the DIII-D tokamak. For an assumed constant particle diffusion coefficient, the model shows that particle transport and neutral fueling produce electron and neutral density profiles that have the same characteristic scale lengths at the plasma edge. For systematic variations of density in H-mode discharges, the model predicts that the width of the electron density transport barrier decreases and the maximum gradient increases, as observed in the experiments. The widths computed from the model agree quantitatively with the experimental widths for conditions in which the model is valid. These results support models of transport barrier formation in which the H-mode particle barrier is driven by the edge particle flux and the width of the barrier is approximately the neutral penetration length.

  17. The role of parallel heat transport in the relation between upstream scrape-off layer widths and target heat flux width in H-mode plasmas of NSTX.

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, J W; Boedo, J A; Maingi, R; Soukhanovskii, V A

    2009-01-05

    The physics of parallel heat transport was tested in the Scrape-off Layer (SOL) plasma of the National Spherical Torus Experiment (NSTX) [M. Ono, et al., Nucl. Fusion 40, 557 (2000) and S. M. Kaye, et al., Nucl. Fusion 45, S168 (2005)] tokamak by comparing the upstream electron temperature (T{sub e}) and density (n{sub e}) profiles measured by the mid-plane reciprocating probe to the heat flux (q{sub {perpendicular}}) profile at the divertor plate measured by an infrared (IR) camera. It is found that electron conduction explains the near SOL width data reasonably well while the far SOL, which is in the sheath limited regime, requires an ion heat flux profile broader than the electron one to be consistent with the experimental data. The measured plasma parameters indicate that the SOL energy transport should be in the conduction-limited regime for R-R{sub sep} (radial distance from the separatrix location) < 2-3 cm. The SOL energy transport should transition to the sheath-limited regime for R-R{sub sep} > 2-3cm. The T{sub e}, n{sub e}, and q{sub {perpendicular}} profiles are better described by an offset exponential function instead of a simple exponential. The conventional relation between mid plane electron temperature decay length ({lambda}{sub Te}) and target heat flux decay length ({lambda}{sub q}) is {lambda}{sub Te} = 7/2{lambda}{sub q}, whereas the newly-derived relation, assuming offset exponential functional forms, implies {lambda}{sub Te} = (2-2.5){lambda}{sub q}. The measured values of {lambda}{sub Te}/{lambda}{sub q} differ from the new prediction by 25-30%. The measured {lambda}{sub q} values in the far SOL (R-R{sub sep} > 2-3cm) are 9-10cm, while the expected values are 2.7 < {lambda}{sub q} < 4.9 cm (for sheath-limited regime). We propose that the ion heat flux profile is substantially broader than the electron heat flux profile as an explanation for this discrepancy in the far SOL.

  18. Comparison of hybrid and baseline ELMy H-mode confinement in JET with the carbon wall

    NARCIS (Netherlands)

    Beurskens, M. N. A.; Frassinetti, L.; Challis, C.; Osborne, T.; Snyder, P. B.; Alper, B.; Angioni, C.; Bourdelle, C.; Buratti, P.; Crisanti, F.; Giovannozzi, E.; Giroud, C.; Groebner, R.; Hobirk, J.; Jenkins, I.; Joffrin, E.; Leyland, M. J.; Lomas, P.; Mantica, P.; McDonald, D.; Nunes, I.; Rimini, F.; Saarelma, S.; Voitsekhovitch, I.; P. de Vries,; Zarzoso, D.

    2013-01-01

    The confinement in JET baseline type I ELMy H-mode plasmas is compared to that in so-called hybrid H-modes in a database study of 112 plasmas in JET with the carbon fibre composite (CFC) wall. The baseline plasmas typically have beta(Nu) similar to 1.5-2, H-98 similar to 1, whereas the hybrid

  19. Investigation Of A Transient Energetic Charge Exchange Fux Enhancement ('spike-on-tail') Observed In Neutral-beam-heated H-mode Discharges In The National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Medley et al, S S

    2011-08-04

    In the National Spherical Torus Experiment (NSTX), a large increase in the charge exchange neutral flux localized at the Neutral Beam (NB) injection full energy is measured by the E||B (superimposed parallel electric and magnetic fields) Neutral Particle Analyzer (NPA). Termed the High-Energy Feature (HEF), it appears on the NB-injected energetic ion spectrum only in discharges where tearing or kink-type modes (f < 50 kHz) are absent, Toroidal Alfvén Eigenmode (TAE) activity (f ~ 50 - 150 kHz) is weak and Global Alfvén Eigenmode (GAE) activity (f ~ 400 – 1000 kHz) is robust. Compressional Alfvén eigenmode (CAE) activity (f > 1000 kHz) is usually sporadic or absent during the HEF event. The HEF exhibits growth times of Δt ~ 20 - 80 ms, durations of ~ 100 – 600 ms and peak-to-base flux ratios up to H = Fmax /Fmin ~ 10. In infrequent cases, a slowing down distribution below the HEF energy can develop that continues to evolve over periods > 100 ms, a time scale long compared with the typical fast ion equilibration times. HEFs are Transient energetic charge exchange flux enhancement ('spike-on-tail') 2 observed only in H-mode (not L-mode) discharges with injected power Pb ≥ 4 MW and in the pitch range χ = vll /v ~ 0.7 – 0.9; i.e. only for passing particles. Increases of ~ 10 - 30 % in the measured neutron yield and total stored energy that are observed to coincide with the feature appear to be driven by concomitant broadening of measured Te(r), Ti(r) and ne(r) profiles and not the HEF itself. While the HEF has minimal impact on plasma performance, it nevertheless poses a challenging wave-particle interaction phenomenon to understand. Candidate mechanisms for HEF formation are developed based on quasilinear theory of wave-particle interaction. The only mechanism found to lead to the large NPA flux ratios, H = Fmax /Fmin , observed in NSTX is the quasilinear evolution of the energetic ion distribution, Fb(E,χ,r), in phase space and the concomitant

  20. ROLE OF NEUTRALS IN CORE FUELING AND PEDESTAL STRUCTURE IN H-MODE DIII-D DISCHARGES

    Energy Technology Data Exchange (ETDEWEB)

    WOLF, NS; PETRIE, TW; PORTER, GD; ROGNLIEN, TD; GROEBNER, RJ; MAKOWSKI, MA

    2002-10-01

    OAK A271 ROLE OF NEUTRALS IN CORE FUELING AND PEDESTAL STRUCTURE IN H-MODE DIII-D DISCHARGES. The 2-D fluid code UEDGE was used to analyze DIII-D experiments to determine the role of neutrals in core fueling, core impurities, and also the H-mode pedestal structure. The authors compared the effects of divertor closure on the fueling rate and impurity density of high-triangularity, H-mode plasmas. UEDGE simulations indicate that the decrease in both deuterium core fueling ({approx} 15%-20%) and core carbon density ({approx} 15%-30%) with the closed divertor compared to the open divertor configuration is due to greater divertor screening of neutrals. They also compared UEDGE results with a simple analytic model of the H-mode pedestal structure. The model predicts both the width and gradient of the transport barrier in n{sub e} as a function of the pedestal density. The more sophisticated UEDGE simulations of H-mode discharges corroborate the simple analytic model, which is consistent with the hypothesis that fueling processes play a role in H-mode transport barrier formation.

  1. Analysis of the H-mode density limit in the ASDEX upgrade tokamak using bolometry

    Energy Technology Data Exchange (ETDEWEB)

    Bernert, Matthias

    2013-10-23

    The high confinement mode (H-mode) is the operational scenario foreseen for ITER, DEMO and future fusion power plants. At high densities, which are favourable in order to maximize the fusion power, a back transition from the H-mode to the low confinement mode (L-mode) is observed. This H-mode density limit (HDL) occurs at densities on the order of, but below, the Greenwald density. In this thesis, the HDL is revisited in the fully tungsten walled ASDEX Upgrade tokamak (AUG). In AUG discharges, four distinct operational phases were identified in the approach towards the HDL. First, there is a stable H-mode, where the plasma density increases at steady confinement, followed by a degrading H-mode, where the core electron density is fixed and the confinement, expressed as the energy confinement time, reduces. In the third phase, the breakdown of the H-mode and transition to the L-mode, the overall electron density is fixed and the confinement decreases further, leading, finally, to an L-mode, where the density increases again at a steady confinement at typical L-mode values until the disruptive Greenwald limit is reached. These four phases are reproducible, quasi-stable plasma regimes and provide a framework in which the HDL can be further analysed. Radiation losses and several other mechanisms, that were proposed as explanations for the HDL, are ruled out for the current set of AUG experiments with tungsten walls. In addition, a threshold of the radial electric field or of the power flux into the divertor appears to be responsible for the final transition back to L-mode, however, it does not determine the onset of the HDL. The observation of the four phases is explained by the combination of two mechanisms: a fueling limit due to an outward shift of the ionization profile and an additional energy loss channel, which decreases the confinement. The latter is most likely created by an increased radial convective transport at the edge of the plasma. It is shown that the

  2. Plasma Response to Lithium-Coated Plasma-Facing Components in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    M.G. Bell, H.W. Kugel, R. Kaita, L.E. Zakharov, H. Schneider, B.P. LeBlanc, D. Mansfield, R.E. Bell, R. Maingi, S. Ding, S.M. Kaye, S.F. Paul, S.P. Gerhardt, J.M. Canik, J.C. Hosea, G. Taylor and the NSTX Research Team

    2009-08-20

    Experiments in the National Spherical Torus Experiment (NSTX) have shown beneficial effects on the performance of divertor plasmas as a result of applying lithium coatings on the graphite and carbonfiber- composite plasma-facing components. These coatings have mostly been applied by a pair of lithium evaporators mounted at the top of the vacuum vessel which inject collimated streams of lithium vapor towards the lower divertor. In NBI-heated, deuterium H-mode plasmas run immediately after the application of lithium, performance modifications included decreases in the plasma density, particularly in the edge, and inductive flux consumption, and increases in the electron and ion temperatures and the energy confinement time. Reductions in the number and amplitude of ELMs were observed, including complete ELM suppression for periods up to 1.2 s, apparently as a result of altering the stability of the edge. However, in the plasmas where ELMs were suppressed, there was a significant secular increase in the effective ion charge Zeff and the radiated power as a result of increases in the carbon and medium-Z metallic impurities, although not of lithium itself which remained at a very low level in the plasma core, <0.1%. The impurity buildup could be inhibited by repetitively triggering ELMs with the application of brief pulses of an n = 3 radial field perturbation. The reduction in the edge density by lithium also inhibited parasitic losses through the scrape-off layer of ICRF power coupled to the plasma, enabling the waves to heat electrons in the core of H-mode plasmas produced by NBI. Lithium has also been introduced by injecting a stream of chemically stabilized, fine lithium powder directly into the scrape-off layer of NBI-heated plasmas. The lithium was ionized in the SOL and appeared to flow along the magnetic field to the divertor plates. This method of coating produced similar effects to the evaporated lithium but at lower amounts.

  3. Characteristics of the First H-mode Discharges in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R.; Bell, M.G.; Bell, R.E.; Bush, C.E.; Fredrickson, E.D.; Gates, D.A.; Kaye, S.M.; Kugel, H.W.; LeBlanc, B.P.; Menard, J.E.; Mueller, D.; Sabbagh, S.A.; Stutman, D.; Taylor, G.; Johnson, D.W.; Kaita, R.; Maqueda, R.J.; Ono, M.; Paoletti, F.; Peng, Y-K.M.; Roquemore, A.L.; Skinner, C.H.; Soukhanovskii, V.A.; and Synakowski, E.J.

    2001-05-10

    We report observations of the first low-to-high (L-H) confinement mode transitions in the National Spherical Torus Experiment (NSTX). The H-mode energy confinement time increased over reference L-mode discharges transiently by 100-300%, as high as {approximately}150 ms. This confinement time is {approximately}1.8-2.3 times higher than predicted by a multi-machine ELM-free H-mode scaling. This achievement extends the H-mode window of fusion devices down to a record low aspect ratio (R/a) {approximately} 1.3, challenging both confinement and L-H power thresholds scalings based on conventional aspect ratio tokamaks.

  4. Impact of perturbative, non-axisymmetric impurity fueling on Alcator C-Mod H-modes

    Science.gov (United States)

    Reinke, M. L.; Lore, J. D.; Terry, J.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Hubbard, A.; Hughes, J. W.; Mumgaard, R.; Pitts, R. A.

    2017-12-01

    Experiments on Alcator C-Mod have been performed to investigate the impact of toroidally localized impurity injection on H-mode exhaust scenarios. Results help to inform sub-divertor gas injector designs, in particular that of the ITER machine, for which this work was primarily undertaken. In repeated EDA H-modes, the amount of N2 injected into the private flux region was scanned up to levels which strongly impacted normalized energy confinement, H98, and led to an H/L back-transition. Repeated scans increased the toroidal peaking of the gas injection, reducing from five equally spaced locations to a single toroidal and poloidal injector. Results show the impact on the pedestal and core plasma is similar between all cases as long as the total gas injection rate is held constant. An influence on toroidally localized impurity spectroscopy is shown, demonstrating a complication in using such data in interpreting experiments and supporting boundary modeling in cases where there are localized extrinsic or intrinsic impurity sources. These results, along with prior work in this area on Alcator C-Mod, form a comprehensive set of L-mode and H-mode data to be used for validation of 3D boundary physics codes.

  5. H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Moda)

    Science.gov (United States)

    Hubbard, A. E.; Hughes, J. W.; Bespamyatnov, I. O.; Biewer, T.; Cziegler, I.; LaBombard, B.; Lin, Y.; McDermott, R.; Rice, J. E.; Rowan, W. L.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S.

    2007-05-01

    This paper reports on studies of the edge transport barrier and transition threshold of the high confinement (H) mode of operation on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)], over a wide range of toroidal field (2.6-7.86T) and plasma current (0.4-1.7MA). The H-mode power threshold and edge temperature at the transition increase with field. Barrier widths, pressure limits, and confinement are nearly independent of field at constant current, but the operational space at high B shifts toward higher temperature and lower density and collisionality. Experiments with reversed field and current show that scrape-off-layer flows in the high-field side depend primarily on configuration. In configurations with the B ×∇B drift away from the active X-point, these flows lead to more countercurrent core rotation, which apparently contributes to higher H-mode thresholds. In the unfavorable case, edge temperature thresholds are higher, and slow evolution of profiles indicates a reduction in thermal transport prior to the transition in particle confinement. Pedestal temperatures in this case are also higher than in the favorable configuration. Both high-field and reversed-field results suggest that parameters at the L-H transition are influencing the evolution and parameters of the H-mode pedestal.

  6. Improved H mode with flat central q profile on EAST

    Science.gov (United States)

    Liu, Haiqing; Yang, Yao; Gao, Xiang; Zeng, Long; Qian, Jinping; Gong, Xianzu; Wan, Baonian; Ding, Weixing; Brower, David Lyn; EAST Team

    2017-10-01

    High betaN ( 1.8) plasma with good confinement (H98y2 1.1) on EAST tokamak has been reported recently. These ELMy H-mode plasmas with Bt = 1.6T, Ip = 400 kA and q95 4.5 were heated by lower hybrid wave and neutral beam injection. The internal transport barrier (ITB) and edge transport barrier (ETB) are both observed with m/n =1/1 fishbone, which were identified to clamp central q at values close to unity. Implying an improved H-mode with flat central q profile and absence of sawteeth, like other devices. Accurate q profile, key profile for developing scenarios aim at high performance H mode, were derived by Polarimeter-interferometer (POINT) measurement as constraint. Base on the optimized current profile, better confinement (H98y2 1.4) with an electron ITB was obtained also with flat central q profile and absence of sawteeth at high betaP ( 2) regime with Bt = 2.5T, Ip = 400 kA. Both high betaN regime and high betaP regime H mode, are characterized by a stationary flat central q profile q0 >=1, but typically close to 1, absence of sawteeth, H98(y,2) >1 and simultaneously, with ITB. This work is supported by the National Magnetic Confinement Fusion Program of China with Contract No. 2014GB106002 and partly supported by the US D.O.E. contract DESC0010469.

  7. H-mode achievement and edge features in RFX-mod tokamak operation

    Science.gov (United States)

    Spolaore, M.; Cavazzana, R.; Marrelli, L.; Carraro, L.; Franz, P.; Spagnolo, S.; Zaniol, B.; Zuin, M.; Cordaro, L.; Dal Bello, S.; De Masi, G.; Ferro, A.; Finotti, C.; Grando, L.; Grenfell, G.; Innocente, P.; Kudlacek, O.; Marchiori, G.; Martines, E.; Momo, B.; Paccagnella, R.; Piovesan, P.; Piron, C.; Puiatti, M. E.; Recchia, M.; Scarin, P.; Taliercio, C.; Vianello, N.; Zanotto, L.

    2017-11-01

    The RFX-mod experiment is a fusion device designed to operate as a reversed field pinch (RFP), with a major radius R = 2 m and a minor radius a = 0.459 m. Its high versatility recently allowed operating it also as an ohmic tokamak, allowing comparative studies between the two configurations in the same device. The device is equipped with a state of the art MHD mode feedback control system providing a magnetic boundary effective control, by applying resonant or non-resonant magnetic perturbations (MP), both in RFP and in tokamak configurations. In the fusion community the application of MPs is widely studied as a promising tool to limit the impact of plasma filaments and ELMs (edge localized modes) on plasma facing components. An important new research line is the exploitation of the RFX-mod active control system for ELM mitigation studies. As a first step in this direction, this paper presents the most recent achievements in term of RFX-mod tokamak explored scenarios, which allowed the first investigation of the ohmic and edge biasing induced H-mode. The production of D-shaped tokamak discharges and the design and deployment of an insertable polarized electrode were accomplished. Reproducible H-mode phases were obtained with insertable electrode negative biasing in single null discharges, representing an unexplored scenario with this technique. Important modifications of the edge plasma density and flow properties are observed. During the achieved H-mode ELM-like electromagnetic composite filamentary structures are observed. They are characterized by clear vorticity and parallel current density patterns.

  8. Experiments and Simulations of ITER-like Plasmas in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    .R. Wilson, C.E. Kessel, S. Wolfe, I.H. Hutchinson, P. Bonoli, C. Fiore, A.E. Hubbard, J. Hughes, Y. Lin, Y. Ma, D. Mikkelsen, M. Reinke, S. Scott, A.C.C. Sips, S. Wukitch and the C-Mod Team

    2010-09-24

    Alcator C-Mod is performing ITER-like experiments to benchmark and verify projections to 15 MA ELMy H-mode Inductive ITER discharges. The main focus has been on the transient ramp phases. The plasma current in C-Mod is 1.3 MA and toroidal field is 5.4 T. Both Ohmic and ion cyclotron (ICRF) heated discharges are examined. Plasma current rampup experiments have demonstrated that (ICRF and LH) heating in the rise phase can save voltseconds (V-s), as was predicted for ITER by simulations, but showed that the ICRF had no effect on the current profile versus Ohmic discharges. Rampdown experiments show an overcurrent in the Ohmic coil (OH) at the H to L transition, which can be mitigated by remaining in H-mode into the rampdown. Experiments have shown that when the EDA H-mode is preserved well into the rampdown phase, the density and temperature pedestal heights decrease during the plasma current rampdown. Simulations of the full C-Mod discharges have been done with the Tokamak Simulation Code (TSC) and the Coppi-Tang energy transport model is used with modified settings to provide the best fit to the experimental electron temperature profile. Other transport models have been examined also. __________________________________________________

  9. ELMs and the H-mode Pedestal in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    R. Maingi; S.A. Sabbagh; C.E. Bush; E.D. Fredrickson; J.E. Menard; D. Stutman; K. Tritz; M.G. Bell; R.E. Bell; J.A. Boedo; D.A. Gates; D.W. Johnson; R. Kaita; S.M. Kaye; H.W. Kugel; B.P. LeBlanc; D. Mueller; R. Raman; A.L. Roquemore; V.A. Soukhanovskii; T. Stevenson

    2004-07-16

    We report on the behavior of ELMs in NBI-heated H-mode plasmas in NSTX. It is observed that the size of Type I ELMs, characterized by the change in plasma energy, decreases with increasing density, as observed at conventional aspect ratio. It is also observed that the Type I ELM size decreases as the plasma equilibrium is shifted from a symmetric double-null toward a lower single-null configuration. Type III ELMs have also been observed in NSTX, as well as a high-performance regime with small ELMs which we designate Type V. These Type V ELMs are consistent with high bootstrap current operation and density approaching Greenwald scaling. The Type V ELMs are characterized by an intermittent n=1 MHD mode rotating counter to the plasma current. Without active pumping, the density rises continuously through the Type V phase. However, efficient in-vessel pumping should allow density control, based on particle containment time estimates.

  10. Physics Basis and Simulation of Burning Plasma Physics for the Fusion Ignition Research Experiment (FIRE)

    Energy Technology Data Exchange (ETDEWEB)

    C.E. Kessel; D. Meade; S.C. Jardin

    2002-01-18

    The FIRE [Fusion Ignition Research Experiment] design for a burning plasma experiment is described in terms of its physics basis and engineering features. Systems analysis indicates that the device has a wide operating space to accomplish its mission, both for the ELMing H-mode reference and the high bootstrap current/high beta advanced tokamak regimes. Simulations with 1.5D transport codes reported here both confirm and constrain the systems projections. Experimental and theoretical results are used to establish the basis for successful burning plasma experiments in FIRE.

  11. Overview of long pulse H-mode operation on EAST

    Science.gov (United States)

    Gong, X.; Garofalo, A. M.; Wan, B.; Li, J.; Qian, J.; Li, E.; Liu, F.; Zhao, Y.; Wang, M.; Xu, H.; EAST Team

    2017-10-01

    The EAST research program aims to demonstrate steady-state long-pulse high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. In the recent experimental campaign, a long pulse fully non-inductive H-mode discharge lasting over 100 seconds using the upper ITER-like tungsten divertor has been achieved in EAST. This scenario used only RF heating and current drive, but also benefitted from an integrated control of the wall conditioning, plasma configuration, divertor heat flux, particle exhaust, impurity management and superconducting coils safety. Maintaining effective coupling of multiple RF heating and current drive sources on EAST is a critical ingredient. This long pulse discharge had good energy confinement, H98,y2 1.1-1.2, and all of the plasma parameters reach a true steady-state. Power balance indicates that the confinement improvement is due partly to a significantly reduced core electron transport inside minor radius rho<0.4. This work was supported by the National Magnetic Confinement Fusion Program of China Contract No. 2015GB10200 and the US Department of Energy Contract No. DE-SC0010685.

  12. Advancing the Physics Basis of Quiescent H-mode through Exploration of ITER Relevant Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, W. M. [PPPL; Burrell, K. H. [General Atomics; Fenstermacher, M. E. [LLNL; Garofalo, A. M. [General Atomics; Grierson, B. A. [PPPL; Loarte, A. [ITER; McKee, G. R. [U of Wisc, Madison; Nazikian, R. [PPPL; Snyder, B. P. [General Atomics

    2014-09-01

    Recent experiments on DIII-D have overcome a long-standing limitation in accessing quiescent H-mode (QH-mode), a high confinement state of the plasma that does not exhibit the explosive instabilities associated with edge localized modes (ELMs). In the past, QH-mode was associated with low density operation, but has now been extended to high normalized densities compatible with operation envisioned for ITER. Through the use of strong shaping, QH-mode plasmas have been maintained at high densities, both absolute (ηe ≈ 7 × 1019 m—3) and normalized Greenwald fraction (ηe/ηG > 0:7) . In these plasmas, the pedestal can evolve to very high pressures and current as the density is increased. Calculations of the pedestal height and width from the EPED model are quantitatively consistent with the experimental observed evolution with density. The comparison of the dependence of the maximum density threshold for QH-mode with plasma shape help validate the underlying theoretical peeling-ballooning models describing ELM stability. High density QH-mode operation with strong shaping has allowed stable access to a previously predicted regime of very high pedestal dubbed \\Super H-mode". In general, QH-mode is found to achieve ELM-stable operation while maintaining adequate impurity exhaust, due to the enhanced impurity transport from an edge harmonic oscillation, thought to be a saturated kink- peeling mode driven by rotation shear. In addition, the impurity confinement time is not affected by rotation, even though the energy confinement time and measured E Χ B shear is observed to increase at low toroidal rotation. Together with demonstrations of high beta, high confinement and low q95 for many energy confinement times, these results suggest QH-mode as a potentially attractive operating scenario for ITER's Q=10 mission.

  13. The 13th International Workshop on H-mode Physics and Transport Barriers (Oxford, UK, 2011) The 13th International Workshop on H-mode Physics and Transport Barriers (Oxford, UK, 2011)

    Science.gov (United States)

    Saibene, G.

    2012-11-01

    as to stimulate and lead the open discussion. Poster sessions were also organized to present specialist papers and provide a venue for continued discussion. The topics selected for this edition of the workshop were: 1. Integrated plasma scenarios for ITER and a reactor: experimental and theoretical studies, including the self-stabilizing transport approach. 2. Edge transport barrier control and plasma performance: physics of 3D stochastic magnetic fields for ELM suppression. 3. H-mode transition physics and H-mode pedestal structure: pedestal dynamics near transitions and requirements for high-confinement access and sustainment. 4. Energetic particle driven instabilities and related physics: H-mode and the transport barrier. 5. Role of and evidence for non-diffusive particle and toroidal momentum transport and impact of fuelling: experiments, theory and modelling. 6. Long-range correlation of plasma turbulence and interaction between edge and core transport. The choice of topics, and the amount of progress in the understanding of the complexity of transport barriers physics reflect the drive in the fusion community towards the preparation for the ITER tokamak operation. More than 100 scientists (including students) attended the three-day workshop, coming from all over the world to present their newest results, discuss with colleagues and enjoy the atmosphere of the beautiful Lady Margaret Hall. The preparation work of the International Advisory Committee (G. Saibene (EU - Chair), R. Groebner (US), T. S Hahm (KO), A. Hubbard (US), K. Ida (Japan), S. Lebedev (RF), N. Oyama (Japan), E Wolfrum (EU)) has been rewarded by the enthusiastic participation of scientists, experimentalist, modellers and theoreticians, and by the high level of the scientific discussion throughout the workshop, during lunch breaks and even at the conference dinner. The Committee is also grateful to EFDA for the support in the organization of the workshop and to the Local Organizing Committee (E

  14. Recent results of H-mode confinement study in JT-60U (April-September, 1995)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-01

    Improvement in the performance of energy confinement is one of the most important issues to realize thermonuclear fusion reactors. The H-mode is one of excellent improved confinement modes. From the view point of steady-state operation, the ELMy H-mode is considered to be a principal operation mode in ITER. For the engineering design of the ITER, there still remain issues to be clarified on the H-mode characteristics. These issues are required to be studied on the present tokamaks as ITER physics research needs. In order to satisfy the above request, experiments of the H-mode confinement have been carried out on JT-60U. Recent results of H-mode confinement study in JT-60U during April to September, 1995 are summarized in the present report. The scaling of high T{sub i} H-mode confinement is described in section 2. The time behaviour of transport properties are shown in sections 3 and 4. Result of the non-dimensional transport experiment is presented in section 5. The H-mode transition is investigated in sections 6, 7, 8 and 9; threshold power scaling, parametric study on edge local quantities, effect of edge neutrals, and H-L back transition. The onset condition of ELMs is studied in section 10. (author).

  15. Experiments on TFTR supershot plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Strachan, J.D.; Bell, M.; Janos, A.; Kaye, S.; Kilpatrick, S.; Manos, D.; Mansfield, D.; Mueller, D.; Owens, K; Timberlake, J. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Pitcher, C.S. (Canadian Fusion Fuels Technology Project, Toronto, ON (Canada)); Snipes, J. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)

    1992-05-01

    Improvements to the TFTR limiter have extended the threshold for carbon blooms (an uncontrolled massive influx of carbon) to greater than 32 MW for 1 sec so that blooms seldom occur in present TFTR Supershot experiments. As a result of the progression from strong blooms to modest blooms to no blooms, improvements in confinement could be correlated with the occurrence of a carbon bloom in the plasma which immediately preceded the supershot. It is speculated that the carbon influx during a carbon bloom results in a limiter surface which has a slightly reduced self=sputtering yield for subsequent discharge. The influence on the supershot plasma seems similar to phenomena obtained by conditioning with lithium pellets.

  16. Labotratory Simulation Experiments of Cometary Plasma

    OpenAIRE

    MINAMI, S.; Baum, P. J.; Kamin, G.; White, R. S.; 南, 繁行

    1986-01-01

    Laboratory simulation experiment to study the interaction between a cometary plasma and the solar wind has been performed using the UCR-T 1 space simulation facility at the Institute of Geophysics and Planetary Physics, the University of California, Riverside. Light emitting plasma composed of Sr, Ba and/or C simulating cometary coma plasma is produced by a plasma emitter which interacts with intense plasma flow produced by a co-axial plasma gun simulating the solar wind. The purpose of this ...

  17. Predictions of H-mode performance in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Budny, R. V.; Andre, R.; Bateman, G.; Halpern, F.; Kessel, C. E.; Kritz, A.; McCune, D.

    2008-03-03

    Time-dependent integrated predictive modeling is carried out using the PTRANSP code to predict fusion power and parameters such as alpha particle density and pressure in ITER H-mode plasmas. Auxiliary heating by negative ion neutral beam injection and ion cyclotron heating of He3 minority ions are modeled, and the GLF23 transport model is used in the prediction of the evolution of plasma temperature profiles. Effects of beam steering, beam torque, plasma rotation, beam current drive, pedestal temperatures, sawtooth oscillations, magnetic diffusion, and accumulation of He ash are treated self-consistently. Variations in assumptions associated with physics uncertainties for standard base-line DT H-mode plasmas (with Ip=15 MA, BTF=5.3 T, and Greenwald fraction=0.86) lead to a range of predictions for DT fusion power PDT and quasi-steady state fusion QDT (≡ PDT/Paux). Typical predictions assuming Paux = 50-53 MW yield PDT = 250- 720 MW and QDT = 5 - 14. In some cases where Paux is ramped down or shut off after initial flat-top conditions, quasi-steady QDT can be considerably higher, even infinite. Adverse physics assumptions such as existence of an inward pinch of the helium ash and an ash recycling coefficient approaching unity lead to very low values for PDT. Alternative scenarios with different heating and reduced performance regimes are also considered including plasmas with only H or D isotopes, DT plasmas with toroidal field reduced 10 or 20%, and discharges with reduced beam voltage. In full-performance D-only discharges, tritium burn-up is predicted to generate central tritium densities up to 1016/m3 and DT neutron rates up to 5×1016/s, compared with the DD neutron rates of 6×1017/s. Predictions with the toroidal field reduced 10 or 20% below the planned 5.3 T and keeping the same q98, Greenwald fraction, and Βη indicate that the fusion yield PDT and QDT will be lower by about a factor of two (scaling as B3.5).

  18. E- to H-mode Transition in Inductively Coupled Xenon Discharge Lamp

    Science.gov (United States)

    Nazri, Ahmad; Inui, Shuji; Motomura, Hideki; Jinno, Masafumi; Aono, Masaharu

    In this paper the phenomena of mode transition and hysteresis in xenon ICP (Inductively Coupled Plasma) discharge are studied. Xenon has been used as an alternative for mercury since there are environmental issues related to mercury. The transition from E-mode (electrostatic mode) discharge to H-mode (electromagnetic mode) discharge in a xenon cylindrical tube was investigated. RF energy at 13.56 MHz was induced to the tube through matching network. In this study, all the transitions occurred at a certain threshold input power which is a function of the xenon pressure. Hysteresis was observed as the input power was varied from 1 to 100 W. When the input power is increased the discharge starts in E-mode changes into H-mode, whereas when the input power is decreased the H-mode turns into the E-mode or there is a sudden switch-off as the function of the gas pressures. Mode transition is determined by sudden and huge change of luminance. H-mode is characterized by a much higher luminance and plasma density. Luminance and optical emission spectra were recorded. At high pressure more power is required to transform the discharge mode compared to low pressure. Continuum visible emission was obtained only in H-mode. At H-mode, many ionic and atomic spectrum are observed compared to E-mode. With high luminance and continuum visible emission that obtained from H-mode xenon ICP discharge, xenon is one of the most suitable alternatives in developing mercury-free light sources.

  19. Hybrid H-mode scenario with nitrogen seeding and type III ELMs in JET

    NARCIS (Netherlands)

    Corre, Y.; Joffrin, E.; Monier-Garbet, P.; Andrew, Y.; Arnoux, G.; Beurskens, M.; Brezinsek, S.; Brix, M.; Buttery, R.; Coffey, I.; Crombe, K.; de la Luna, E.; Felton, R.; Giroud, C.; Hacquin, S.; Hobirk, J.; Huber, A.; Imbeaux, F.; Jachmich, S.; Kempenaars, M.; Litaudon, X.; Leggate, H.; Loarer, T.; Maddison, G.; Rachlew, E.; Rapp, J.; Sauter, O.; Savchkov, A.; Telesca, G.; Widdowson, A.; Zastrow, K. D.; Zimmermann, O.

    2008-01-01

    The performance of the 'hybrid' H-mode regime (long pulse operation with high neutron fluency) has been extensively investigated in JET during the 2005-2007 experimental campaign up to normalized pressure beta(N) = 3, toroidal magnetic field B-t = 1.7T, with type I ELMs plasma edge

  20. Radiative type-III ELMy H-mode in all-tungsten ASDEX Upgrade

    NARCIS (Netherlands)

    Rapp, J.; Kallenbach, A.; Neu, R.; Eich, T.; Fischer, R.; Herrmann, A.; Potzel, S.; van Rooij, G. J.; Zielinski, J. J.; ASDEX Upgrade team,

    2012-01-01

    The type-III ELMy H-mode might be the solution for an integrated ITER operation scenario fulfilling the fusion power amplification factor (output fusion power to input heating power) of Q = 10 with simultaneous acceptable steady-state and transient power loads to the plasma-facing components. This

  1. Ubiquity of non-diffusive momentum transport in JET H-modes

    NARCIS (Netherlands)

    Weisen, H.; Camenen, Y.; Salmi, A.; Versloot, T. W.; de Vries, P. C.; Maslov, M.; Tala, T.; Beurskens, M.; Giroud, C.; JET-EFDA Contributors,

    2012-01-01

    A broad survey of the experimental database of neutral beam heated baseline H-modes and hybrid scenarios in the JET tokamak has established the ubiquity of non-diffusive momentum transport mechanisms in rotating plasmas. As a result of their presence, the normalized angular frequency gradient R

  2. BOUT++ Simulations of Edge Turbulence in Alcator C-Mod's EDA H-Mode

    Science.gov (United States)

    Davis, E. M.; Porkolab, M.; Hughes, J. W.; Labombard, B.; Snyder, P. B.; Xu, X. Q.

    2013-10-01

    Energy confinement in tokamaks is believed to be strongly controlled by plasma transport in the pedestal. The pedestal of Alcator C-Mod's Enhanced Dα (EDA) H-mode (ν* > 1) is regulated by a quasi-coherent mode (QCM), an edge fluctuation believed to reduce particle confinement and allow steady-state H-mode operation. ELITE calculations indicate that EDA H-modes sit well below the ideal peeling-ballooning instability threshold, in contrast with ELMy H-modes. Here, we use a 3-field reduced MHD model in BOUT++ to study the effects of nonideal and nonlinear physics on EDA H-modes. In particular, incorporation of realistic pedestal resistivity is found to drive resistive ballooning modes (RBMs) and increase linear growth rates above the corresponding ideal rates. These RBMs may ultimately be responsible for constraining the EDA pedestal gradient. However, recent high-fidelity mirror Langmuir probe measurements indicate that the QCM is an electron drift-Alfvén wave - not a RBM. Inclusion of the parallel pressure gradient term in the 3-field reduced MHD Ohm's law and various higher field fluid models are implemented in an effort to capture this drift wave-like response. This work was performed under the auspices of the USDoE under awards DE-FG02-94-ER54235, DE-AC52-07NA27344, DE-AC52-07NA27344, and NNSA SSGF.

  3. The H-mode power threshold in JET

    Energy Technology Data Exchange (ETDEWEB)

    Start, D.F.H.; Bhatnagar, V.P.; Campbell, D.J.; Cordey, J.G.; Esch, H.P.L. de; Gormezano, C.; Hawkes, N.; Horton, L.; Jones, T.T.C.; Lomas, P.J.; Lowry, C.; Righi, E.; Rimini, F.G.; Saibene, G.; Sartori, R.; Sips, G.; Stork, D.; Thomas, P.; Thomsen, K.; Tubbing, B.J.D.; Von Hellermann, M.; Ward, D.J. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    New H-mode threshold data over a range of toroidal field and density values have been obtained from the present campaign. The scaling with n{sub e} B{sub t} is almost identical with that of the 91/92 period for the same discharge conditions. The scaling with toroidal field alone gives somewhat higher thresholds than the older data. The 1991/2 database shows a scaling of P{sub th} (power threshold) with n{sub e} B{sub t} which is approximately linear and agrees well with that observed on other tokamaks. For NBI and carbon target tiles the threshold power is a factor of two higher with the ion {Nu}B drift away from the target compared with the value found with the drift towards the target. The combination of ICRH and beryllium tiles appears to be beneficial for reducing P{sub th}. The power threshold is largely insensitive to plasma current, X-point height and distance between the last closed flux surface and the limiter, at least for values greater than 2 cm. (authors). 3 refs., 6 figs.

  4. The role of MHD instabilities in the improved H-mode scenario

    Energy Technology Data Exchange (ETDEWEB)

    Flaws, Asher

    2009-02-16

    Recently a regime of tokamak operation has been discovered, dubbed the improved H-mode scenario, which simultaneously achieves increased energy confinement and stability with respect to standard H-mode discharges. It has been suggested that magnetohydrodynamic (MHD) instabilities play some role in establishing this regime. In this thesis MHD instabilities were identified, characterised, and catalogued into a database of improved H-mode discharges in order to statistically examine their behaviour. The onset conditions of MHD instabilities were compared to existing models based on previous H-mode studies. Slight differences were found, most notably a reduced {beta}{sub N} onset threshold for the frequently interrupted regime for neoclassical tearing modes (NTM). This reduced threshold is due to the relatively low magnetic shear of the improved H-mode regime. This study also provided a first-time estimate for the seed island size of spontaneous onset NTMs, a phenomenon characteristic of the improved H-mode scenario. Energy confinement investigations found that, although the NTM impact on confinement follows the same model applicable to other operating regimes, the improved H-mode regime acts to mitigate the impact of NTMs by limiting the saturated island sizes for NTMs with toroidal mode number n {>=} 2. Surprisingly, although a significant loss in energy confinement is observed during the sawtooth envelope, it has been found that discharges containing fishbones and low frequency sawteeth achieve higher energy confinement than those without. This suggests that fishbone and sawtooth reconnection may indeed play a role in establishing the high confinement regime. It was found that the time evolution of the central magnetic shear consistently locks in the presence of sawtooth and fishbone reconnection. Presumably this is due to the periodic redistribution of the central plasma current, an effect which is believed to help establish and maintain the characteristic current

  5. VH mode accessibility and global H-mode properties in previous and present JET configurations

    Energy Technology Data Exchange (ETDEWEB)

    Jones, T.T.C.; Ali-Arshad, S.; Bures, M.; Christiansen, J.P.; Esch, H.P.L. de; Fishpool, G.; Jarvis, O.N.; Koenig, R.; Lawson, K.D.; Lomas, P.J.; Marcus, F.B.; Sartori, R.; Schunke, B.; Smeulders, P.; Stork, D.; Taroni, A.; Thomas, P.R.; Thomsen, K. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    In JET VH modes, there is a distinct confinement transition following the cessation of ELMs, observed in a wide variety of tokamak operating conditions, using both NBI and ICRF heating methods. Important factors which influence VH mode accessibility such as magnetic configuration and vessel conditions have been identified. The new JET pumped divertor configuration has much improved plasma shaping control and power and particle exhaust capability and should permit exploitation of plasmas with VH confinement properties over an even wider range of operating regimes, particularly at high plasma current; first H-modes have been obtained in the 1994 JET operating period and initial results are reported. (authors). 7 refs., 6 figs.

  6. Plasma temperature measurements in disruption simulated experiment

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, N.I. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Bakhtin, V.P. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Safronov, V.M. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Toporkov, D.A. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Vasenin, S.G. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Wurz, H. [Kernforschungszentrum Karlsruhe, INR (Germany); Zhitlukhin, A.M. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation)

    1995-12-31

    Results are reported of experiments to measure the temporal and spatial distributions of a temperature and radiation of a near surface plasma cloud appearing in the disruption simulated experiments. These measurements are needed to verificate the different numerical models of vapor shielding layer which appears to arise near the divertor plates surface and prevents them from the bulk of the incoming energy. Experiments with graphite and tungsten samples were carried out at the 2MK-200 plasma facility. Long CUSP trap was used as a source of high temperature deuterium plasma with a power density W = 10 MW/cm{sup 2} and time duration t = 20 mcs. Laser scattering, space and time resolved soft x-ray spectroscopy was employed to measure the plasma cloud temperature and radiation. The different behaviour of shielding layer parameters was shown for a graphite and tungsten samples. For a tungsten the sharp boundary existed between the incoming deuterium plasma and the thin layer of ablated material plasma and the strong gradient of electron temperature took place in this zone. For a graphite this boundary was broadened at the distance and the main part of the screening layer consisted of the mixture of the incoming deuterium and ablated carbon plasma. (orig.).

  7. Effect of progressively increasing lithium conditioning on edge transport and stability in high triangularity NSTX H-modes

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R., E-mail: rmaingi@pppl.gov [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Canik, J.M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Bell, R.E. [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Boyle, D.P. [Princeton University, Princeton, NJ (United States); Diallo, A.; Kaita, R.; Kaye, S.M.; LeBlanc, B.P. [Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08543 (United States); Sabbagh, S.A. [Columbia University, New York, NY (United States); Scotti, F.; Soukhanovskii, V.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2017-04-15

    A sequence of H-mode discharges with increasing levels of pre-discharge lithium evaporation (‘dose’) was conducted in high triangularity and elongation boundary shape in NSTX. Energy confinement increased, and recycling decreased with increasing lithium dose, similar to a previous lithium dose scan in medium triangularity and elongation plasmas. Data-constrained SOLPS interpretive modeling quantified the edge transport change: the electron particle diffusivity decreased by 10–30x. The electron thermal diffusivity decreased by 4x just inside the top of the pedestal, but increased by up to 5x very near the separatrix. These results provide a baseline expectation for lithium benefits in NSTX-U, which is optimized for a boundary shape similar to the one in this experiment.

  8. PREFACE: 11th IAEA Technical Meeting on H-mode Physics and Transport Barriers

    Science.gov (United States)

    Takizuka, Tomonori

    2008-07-01

    This volume of Journal of Physics: Conference Series contains papers based on invited talks and contributed posters presented at the 11th IAEA Technical Meeting on H-mode Physics and Transport Barriers. This meeting was held at the Tsukuba International Congress Center in Tsukuba, Japan, on 26-28 September 2007, and was organized jointly by the Japan Atomic Energy Agency and the University of Tsukuba. The previous ten meetings in this series were held in San Diego (USA) 1987, Gut Ising (Germany) 1989, Abingdon (UK) 1991, Naka (Japan) 1993, Princeton (USA) 1995, Kloster Seeon (Germany) 1997, Oxford (UK) 1999, Toki (Japan) 2001, San Diego (USA) 2003, and St Petersburg (Russia) 2005. The purpose of the eleventh meeting was to present and discuss new results on H-mode (edge transport barrier, ETB) and internal transport barrier, ITB, experiments, theory and modeling in magnetic fusion research. It was expected that contributions give new and improved insights into the physics mechanisms behind high confinement modes of H-mode and ITBs. Ultimately, this research should lead to improved projections for ITER. As has been the tradition at the recent meetings of this series, the program was subdivided into six topics. The topics selected for the eleventh meeting were: H-mode transition and the pedestal-width Dynamics in ETB: ELM threshold, non-linear evolution and suppression, etc Transport relations of various quantities including turbulence in plasmas with ITB: rotation physics is especially highlighted Transport barriers in non-axisymmetric magnetic fields Theory and simulation on transport barriers Projections of transport barrier physics to ITER For each topic there was an invited talk presenting an overview of the topic, based on contributions to the meeting and on recently published external results. The six invited talks were: A Leonard (GA, USA): Progress in characterization of the H-mode pedestal and L-H transition N Oyama (JAEA, Japan): Progress and issues in

  9. Recent Results from the Plasma Couette Experiment

    Science.gov (United States)

    Katz, Noam; Collins, Cami; Cooper, Chris; Wallace, John; Clark, Mike; Reese, Ingrid; Wahl, Carl; Forest, Cary

    2012-10-01

    The Plasma Couette Experiment (PCX) has been designed to study the magnetorotational instability (MRI) in a laboratory plasma. As a first step towards this goal, we have achieved solid-body rotation of an unmagnetized plasma for the first time. We apply JxB torque at the magnetized edge region of a ``magnetic bucket,'' and the momentum couples into the unmagnetized bulk plasma through collisional viscosity. In order for momentum to couple inward from the edge, it is crucial that the ion viscosity dominate the drag due to ion-neutral charge exchange collisions. The next steps towards laboratory observation of the MRI involve driving sheared flow (since solid-body flow is stable to the MRI) and applying a weak vertical magnetic field to destabilize the plasma. We will describe our recent progress in these areas, as well as development of a laser-induced fluorescence diagnostic to better characterize the velocity profile and measure the ion temperature.

  10. Construction of the Plasma Liner Experiment (PLX)

    Science.gov (United States)

    Adams, C. S.; Awe, T. J.; Dunn, J. P.; Hsu, S. C.; Davis, J. S.; Hanna, D. S.; Schwartz, J. A.; Brockington, S.; van Doren, D.; Witherspoon, F. D.; Merritt, E. C.; Lynn, A. G.; Gilmore, M. A.

    2011-10-01

    The Plasma Liner Experiment (PLX) will investigate the behavior and interaction of spherically convergent plasma jets in forming imploding spherical plasma liners for HED and MIF-relevant studies. Numerous hardware systems have been assembled for the new PLX facility at Los Alamos National Laboratory to prepare for first plasma. A three meter diameter spherical vacuum tank is coupled to an oil-free vacuum pump system reaching sub-10-6 torr pressures on the first pump-down. A modular, distributed, and portable 60 kV pulsed-power system has been constructed for initial experiments on single jet propagation and two jet merging, with each plasma gun source having 70 kJ of stored energy. In addition, a capacitor test stand has been constructed in order to test each of the 180 required capacitors to the expected operational voltage. Finally, the experiment will be controlled via FPGA/LabView to interact with numerous custom-built pieces of electronics for interlock, control, triggering, and data acquisition. Supported by DOE Fusion Energy Sciences.

  11. Study on H-mode access at low density with lower hybrid current drive and lithium-wall coatings on the EAST superconducting tokamak

    DEFF Research Database (Denmark)

    Xu, G.S.; Wan, B.N.; Li, J.G.

    2011-01-01

    The first high-confinement mode (H-mode) with type-III edge localized modes at an H factor of HIPB98(y,2) ~ 1 has been obtained with about 1 MW lower hybrid wave power on the EAST superconducting tokamak. The first H-mode plasma appeared after wall conditioning by lithium (Li) evaporation before...... plasma breakdown and the real-time injection of fine Li powder into the plasma edge. The threshold power for H-mode access follows the international tokamak scaling even in the low density range and a threshold in density has been identified. With increasing accumulation of deposited Li the H......, which is considered the main mechanism for the H-mode power threshold reduction by the Li wall coatings....

  12. NSTX Plasma Response to Lithium Coated Divertor

    Energy Technology Data Exchange (ETDEWEB)

    H.W. Kugel, M.G. Bell, J.P. Allain, R.E. Bell, S. Ding, S.P. Gerhardt, M.A. Jaworski, R. Kaita, J. Kallman, S.M. Kaye, B.P. LeBlanc, R. Maingi, R. Majeski, R. Maqueda, D.K. Mansfield, D. Mueller, R. Nygren, S.F. Paul, R. Raman, A.L. Roquemore, S.A. Sabbagh, H. Schneider, C.H. Skinner, V.A. Soukhanovskii, C.N. Taylor, J.R. Timberlak, W.R. Wampler, L.E. Zakharov, S.J. Zweben, and the NSTX Research Team

    2011-01-21

    NSTX experiments have explored lithium evaporated on a graphite divertor and other plasma facing components in both L- and H- mode confinement regimes heated by high-power neutral beams. Improvements in plasma performance have followed these lithium depositions, including a reduction and eventual elimination of the HeGDC time between discharges, reduced edge neutral density, reduced plasma density, particularly in the edge and the SOL, increased pedestal electron and ion temperature, improved energy confinement and the suppression of ELMs in the H-mode. However, with improvements in confinement and suppression of ELMs, there was a significant secular increase in the effective ion charge Zeff and the radiated power in H-mode plasmas as a result of increases in the carbon and medium-Z metallic impurities. Lithium itself remained at a very low level in the plasma core, <0.1%. Initial results are reported from operation with a Liquid Lithium Divertor (LLD) recently installed.

  13. A stationary long-pulse ELM-absent H-mode regime in EAST

    Science.gov (United States)

    Ye, Y.; Xu, G. S.; Wan, B. N.; Chen, R.; Yan, N.; Guo, H. Y.; Shao, L. M.; Yang, Q. Q.; Wang, H. Q.; Zhang, W.; Xia, T. Y.; Zhang, T.; Li, Y. Y.; Wang, T. F.; Zang, Q.; Hu, Y. J.; Wu, G. J.; Zhang, L.; Hao, B. L.; Wang, L.; Li, Y. L.; Wu, X. Q.; Chen, L.; Lan, H.; Wang, Y. F.; Xu, J. C.; Hu, G. H.; Ding, S. Y.; Zhang, H.; Zhao, N.; Li, J.; The EAST Team

    2017-08-01

    A stationary edge-localized mode (ELM)-absent H-mode regime, with an electrostatic edge coherent mode (ECM) which resides in the pedestal region, has been achieved in the EAST tokamak recently. This regime allows the operation of a nearly fully noninductive long pulse (>15 s), exhibiting a relatively high pedestal and good global energy confinement with {{H}98,y2} near 1.2, and excellent impurity control. Furthermore, this regime is mostly obtained with a 4.6 GHz lower hybrid current drive (LHCD) or counter-current neutral beam injection (NBI), plus electron cyclotron resonance heating, and an extensive lithium wall coating. This stationary ELM-absent H-mode regime transits to a stationary small ELM H-mode regime, and upon additional heating power from the 2.45 GHz LHCD, an ion cyclotron resonant frequency or co-current NBI is applied (under 4.6 GHz LHCD heating background). A slight change of the plasma configuration also makes the small ELMs reappear. The experimental observations suggest that a long-pulse ELM-absent regime can be induced by the ECM, which exhibits strong electrostatic fluctuations and may provide a channel for continuous particle (especially impurities) and heat exhaust across the pedestal. The ECM exists in the collisionality of ν e*   =  2.5-4 and the pressure gradient |\

  14. Plasma wakefield acceleration experiments at FACET II

    Science.gov (United States)

    Joshi, C.; Adli, E.; An, W.; Clayton, C. E.; Corde, S.; Gessner, S.; Hogan, M. J.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; O’shea, B.; Xu, Xinlu; White, G.; Yakimenko, V.

    2018-03-01

    During the past two decades of research, the ultra-relativistic beam-driven plasma wakefield accelerator (PWFA) concept has achieved many significant milestones. These include the demonstration of ultra-high gradient acceleration of electrons over meter-scale plasma accelerator structures, efficient acceleration of a narrow energy spread electron bunch at high-gradients, positron acceleration using wakes in uniform plasmas and in hollow plasma channels, and demonstrating that highly nonlinear wakes in the ‘blow-out regime’ have the electric field structure necessary for preserving the emittance of the accelerating bunch. A new 10 GeV electron beam facility, Facilities for Accelerator Science and Experimental Test (FACET) II, is currently under construction at SLAC National Accelerator Laboratory for the next generation of PWFA research and development. The FACET II beams will enable the simultaneous demonstration of substantial energy gain of a small emittance electron bunch while demonstrating an efficient transfer of energy from the drive to the trailing bunch. In this paper we first describe the capabilities of the FACET II facility. We then describe a series of PWFA experiments supported by numerical and particle-in-cell simulations designed to demonstrate plasma wake generation where the drive beam is nearly depleted of its energy, high efficiency acceleration of the trailing bunch while doubling its energy and ultimately, quantifying the emittance growth in a single stage of a PWFA that has optimally designed matching sections. We then briefly discuss other FACET II plasma-based experiments including in situ positron generation and acceleration, and several schemes that are promising for generating sub-micron emittance bunches that will ultimately be needed for both an early application of a PWFA and for a plasma-based future linear collider.

  15. Reduced turbulence and H-mode confinement in L-mode negative triangularity discharges on DIII-D

    Science.gov (United States)

    Marinoni, A.; Austin, M. E.; Walker, M. L.; Hyatt, A. W.; Petty, C. C.; Thome, K. H.; Porkolab, M.; Rost, J. C.; Davis, E. M.; McKee, G. R.; Rhodes, T. L.; Sung, C.; Sauter, O.; DIII-D Team; MIT-PSFC Collaboration

    2017-10-01

    DIII-D has produced inner-wall limited plasmas with an L-mode edge at negative triangularity characterized by confinement and fluctuation levels comparable to those in H-mode plasmas at positive triangularity. On TCV, similar plasmas at low collisionality and with pure electron heating showedimproved energy confinement, as compared to matched discharges at positive triangularity, due to modifications to the toroidal precession drift of trapped electrons. The recent DIII-D experiment used both ECH and NBI heating, thus exploring a more reactor relevant regime where Te Ti. Compared to matched positive triangularity discharges, the intensity of density and temperaturefluctuations is reduced at negative triangularity both in ECH and in NBI dominated phases. Preliminary TGLF runs indicate the discharges are dominated by TEM modes. More detailed analysis will explore the role of the toroidal precession drift in this new regime. Work supported by US DOE under DE-FG02-94ER54235 and DE-FC02-04ER54698.

  16. MHD simulation of plasma compression experiments

    Science.gov (United States)

    Reynolds, Meritt; Barsky, Sandra; de Vietien, Peter

    2017-10-01

    General Fusion (GF) is working to build a magnetized target fusion (MTF) power plant based on compression of magnetically-confined plasma by liquid metal. GF is testing this compression concept by collapsing solid aluminum liners onto plasmas formed by coaxial helicity injection in a series of experiments called PCS (Plasma Compression, Small). We simulate the PCS experiments using the finite-volume MHD code VAC. The single-fluid plasma model includes temperature-dependent resistivity and anisotropic heat transport. The time-dependent curvilinear mesh for MHD simulation is derived from LS-DYNA simulations of actual field tests of liner implosion. We will discuss how 3D simulations reproduced instability observed in the PCS13 experiment and correctly predicted stabilization of PCS14 by ramping the shaft current during compression. We will also present a comparison of simulated Mirnov and x-ray diagnostics with experimental measurements indicating that PCS14 compressed well to a linear compression ratio of 2.5:1.

  17. Long Pulse High Performance Plasma Scenario Development for the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, C.E.; Bell, R.E.; Bell, M.G.; Gates, D.A.; Harvey, R.W.

    2006-01-01

    The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications and identify the requirements for (1) high elongation and triangularity, (2) density control to optimize the current drive, (3) plasma rotation and/or feedback stabilization to operate above the no-wall limit, and (4) electron Bernstein waves (EBW) for off-axis heating/current drive (H/CD). Integrated scenarios are constructed to provide the transport evolution and H/CD source modeling, supported by rf and stability analyses. Important factors include the energy confinement, Zeff, early heating/H mode, broadening of the NBI-driven current profile, and maintaining q(0) and qmin>1.0. Simulations show that noninductive sustained plasmas can be reached at IP=800 kA, BT=0.5 T, 2.5, N5, 15%, fNI=92%, and q(0)>1.0 with NBI H/CD, density control, and similar global energy confinement to experiments. The noninductive sustained high plasmas can be reached at IP=1.0 MA, BT=0.35 T, 2.5, N9, 43%, fNI=100%, and q(0)>1.5 with NBI H/CD and 3.0 MW of EBW H/CD, density control, and 25% higher global energy confinement than experiments. A scenario for nonsolenoidal plasma current rampup is developed using high harmonic fast wave H/CD in the early low IP and low Te phase, followed by NBI H/CD to continue the current ramp, reaching a maximum of 480 kA after 3.4 s.

  18. Characteristics of EGAMs in EAST tokamak under ICRF H-mode

    Science.gov (United States)

    di Liu, Ah; Zhou, Chu; Zhang, Xiao Hui; Hu, Jian Qiang; Li, Hong; Lan, Tao; Xie, Jing Lin; Yu, Chang Xuan; Liu, Wan Dong

    2012-10-01

    Doppler reflectometer is common plasma diagnostic used in magnetic confinement devices to measure density fluctuations and poloidal flow velocity. Two set of Doppler reflectometer (Q-band & V-band)were installed on EAST tokamak for the first time. A coherence mode with frequency of 20˜50kHz was observed both on Doppler reflectometer and magnetic coils during ICRF H-mode on EAST. It appeared as zero-symmetric peaks in the spectrum of Doppler backscattering phase signal, implying that the density fluctuation has a standing wave structure with frequency not changing with the plasma rotation. The toroidal mode number is zero according to the magnetic coils. This feather was not observed on ECE and soft-X signals and there isn't obvious relationship between the mode appearance and the neutrons and hard-X signals. Unlike the usual Geodesic Acoustic modes (GAM) in the edge plasma under L-mode, it was found that the mode only appeared in the core regime under H-mode through the ray-tracing code. The mode is suspected to be the energetic ion induced GAM.

  19. EDGE2D-EIRENE modelling of near SOL E r: possible impact on the H-mode power threshold

    Science.gov (United States)

    Chankin, A. V.; Delabie, E.; Corrigan, G.; Harting, D.; Maggi, C. F.; Meyer, H.; Contributors, JET

    2017-04-01

    Recent EDGE2D-EIRENE simulations of JET plasmas showed a significant difference between radial electric field (E r) profiles across the separatrix in two divertor configurations, with the outer strike point on the horizontal target (HT) and vertical target (VT) (Chankin et al 2016 Nucl. Mater. Energy, doi: 10.1016/j.nme.2016.10.004). Under conditions (input power, plasma density) where the HT plasma went into the H-mode, a large positive E r spike in the near scrape-off layer (SOL) was seen in the code output, leading to a very large E × B shear across the separatrix over a narrow region of a fraction of a cm width. No such E r feature was obtained in the code solution for the VT configuration, where the H-mode power threshold was found to be twice as high as in the HT configuration. It was hypothesised that the large E × B shear across the separatrix in the HT configuration could be responsible for the turbulence suppression leading to an earlier (at lower input power) L-H transition compared to the VT configuration. In the present work these ideas are extended to cover some other experimental observations on the H-mode power threshold variation with parameters which typically are not included in the multi-machine H-mode power threshold scalings, namely: ion mass dependence (isotope H-D-T exchange), dependence on the ion ∇B drift direction, and dependence on the wall material composition (ITER-like wall versus carbon wall in JET). In all these cases EDGE2D-EIRENE modelling shows larger positive E r spikes in the near SOL under conditions where the H-mode power threshold is lower, at least in the HT configuration.

  20. Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST

    DEFF Research Database (Denmark)

    Peng, Liu; Guosheng, Xu; Huiqian, Wang

    2013-01-01

    -H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (Vf) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots......As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave...... that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L...

  1. Fluctuations during JET discharges with H-mode

    Energy Technology Data Exchange (ETDEWEB)

    Malacarne, M.; Cripwell, P.; Duperrex, P.A.; Edwards, A.W.; Gill, R.D.; Granetz, R.S.; Simonet, F.; Snipes, J.; Weller, A.

    1987-12-01

    The appearance and disappearance of H-mode behaviour in JET Tokamak discharges is associated with characteristic instabilities detected by edge magnetic probes, arrays of soft X-ray diodes and reflectometry: edge disruptive-like modes are observed before L-H transitions whereas H-L transitions are accompanied by large bursts of broad-band activity. Other observed fluctuations, shown to be resonant in the central region of the discharge, are not affected by the transitions. The importance of edge fluctuations and induced transport of a magnetic separatrix configuration is thus emphasised.

  2. Laser fusion implosion and plasma interaction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstrom, H.G.

    1977-08-01

    Results related to the propagation, absorption and scattering of laser light by both spherical and planar targets are described. The absorption measurements indicate that for intensities of interest, inverse bremsstrahlung is not the dominant absorption mechanism. The laser light scattered by the plasma is polarization dependent and provides evidence that Brillouin scattering and resonance absorption are operative. Special diagnostics have been designed and experiments have been performed to elucidate the nature of these two processes. Implosion results on glass microshell targets filled with DT gas are also summarized. These experiments are for targets intentionally operated in the portion of parameter space characteristic of exploding pusher events. Experiments have been performed over a yield range from 0 to 10/sup 9/ neutrons per event. It is shown how this data can be normalized with a simple scaling law.

  3. One-dimensional modelling of limit-cycle oscillation and H-mode power scaling

    DEFF Research Database (Denmark)

    Wu, Xingquan; Xu, Guosheng; Wan, Baonian

    2015-01-01

    To understand the connection between the dynamics of microscopic turbulence and the macroscale power scaling in the L-I-H transition in magnetically confined plasmas, a new time-dependent, one-dimensional (in radius) model has been developed. The model investigates the radial force balance equation...... at the edge region of the plasma and applies the quenching effect of turbulence via the E x B flow shear rate exceeding the shear suppression threshold. By slightly ramping up the heating power, the spatio-temporal evolution of turbulence intensity, density and pressure profiles, poloidal flow and E x B flow...... and the turbulence intensity depending on which oscillation of the diamagnetic flow or poloidal flow is dominant. Specifically, by including the effects of boundary conditions of density and temperature, the model results in a linear dependence of the H-mode access power on the density and magnetic field...

  4. Electron density and plasma dynamics of a colliding plasma experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wiechula, J., E-mail: wiechula@physik.uni-frankfurt.de; Schönlein, A.; Iberler, M.; Hock, C.; Manegold, T.; Bohlender, B.; Jacoby, J. [Plasma Physics Group, Institute of Applied Physics, Goethe University, 60438 Frankfurt am Main (Germany)

    2016-07-15

    We present experimental results of two head-on colliding plasma sheaths accelerated by pulsed-power-driven coaxial plasma accelerators. The measurements have been performed in a small vacuum chamber with a neutral-gas prefill of ArH{sub 2} at gas pressures between 17 Pa and 400 Pa and load voltages between 4 kV and 9 kV. As the plasma sheaths collide, the electron density is significantly increased. The electron density reaches maximum values of ≈8 ⋅ 10{sup 15} cm{sup −3} for a single accelerated plasma and a maximum value of ≈2.6 ⋅ 10{sup 16} cm{sup −3} for the plasma collision. Overall a raise of the plasma density by a factor of 1.3 to 3.8 has been achieved. A scaling behavior has been derived from the values of the electron density which shows a disproportionately high increase of the electron density of the collisional case for higher applied voltages in comparison to a single accelerated plasma. Sequences of the plasma collision have been taken, using a fast framing camera to study the plasma dynamics. These sequences indicate a maximum collision velocity of 34 km/s.

  5. Divertor heat flux simulations in ELMy H-mode discharges of EAST

    Science.gov (United States)

    Xia, T. Y.; Xu, X. Q.; Wu, Y. B.; Huang, Y. Q.; Wang, L.; Zheng, Z.; Liu, J. B.; Zang, Q.; Li, Y. Y.; Zhao, D.; EAST Team

    2017-11-01

    This paper presents heat flux simulations for the ELMy H-mode on the Experimental Advanced Superconducting Tokamak (EAST) using a six-field two-fluid model in BOUT++. Three EAST ELMy H-mode discharges with different plasma currents I p and geometries are studied. The trend of the scrape-off layer width λq with I p is reproduced by the simulation. The simulated width is only half of that derived from the EAST scaling law, but agrees well with the international multi-machine scaling law. Note that there is no radio-frequency (RF) heating scheme in the simulations, and RF heating can change the boundary topology and increase the flux expansion. Anomalous electron transport is found to contribute to the divertor heat fluxes. A coherent mode is found in the edge region in simulations. The frequency and poloidal wave number kθ are in the range of the edge coherent mode in EAST. The magnetic fluctuations of the mode are smaller than the electric field fluctuations. Statistical analysis of the type of turbulence shows that the turbulence transport type (blobby or turbulent) does not influence the heat flux width scaling. The two-point model differs from the simulation results but the drift-based model shows good agreement with simulations.

  6. A Physics Exploratory Experiment on Plasma Liner Formation

    Science.gov (United States)

    Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ronald C.; Siemon, Richard E.; Turchi, Peter

    2002-01-01

    Momentum flux for imploding a target plasma in magnetized target fusion (MTF) may be delivered by an array of plasma guns launching plasma jets that would merge to form an imploding plasma shell (liner). In this paper, we examine what would be a worthwhile experiment to do in order to explore the dynamics of merging plasma jets to form a plasma liner as a first step in establishing an experimental database for plasma-jets driven magnetized target fusion (PJETS-MTF). Using past experience in fusion energy research as a model, we envisage a four-phase program to advance the art of PJETS-MTF to fusion breakeven Q is approximately 1). The experiment (PLX (Plasma Liner Physics Exploratory Experiment)) described in this paper serves as Phase I of this four-phase program. The logic underlying the selection of the experimental parameters is presented. The experiment consists of using twelve plasma guns arranged in a circle, launching plasma jets towards the center of a vacuum chamber. The velocity of the plasma jets chosen is 200 km/s, and each jet is to carry a mass of 0.2 mg - 0.4 mg. A candidate plasma accelerator for launching these jets consists of a coaxial plasma gun of the Marshall type.

  7. Plasma radiation in tokamak disruption simulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, N.; Bakhtin, V.; Safronov, V.; Toporkov, D.; Vasenin, S.; Zhitlukhin, A. [Troitsk Inst. for Innovation and Fusion Research (Russian Federation); Wuerz, H. [Forschungszentrum Karlsruhe (Germany)

    1995-12-31

    Plasma impact results in sudden evaporation of divertor plate material and produces a plasma cloud which acts as a protective shield. The incoming energy flux is absorbed in the plasma shield and is converted mainly into radiation. Thus the radiative characteristics of the target plasma determine the dissipation of the incoming energy and the heat load at the target. Radiation of target plasma is studied at the two plasma gun facility 2MK-200 at Troitsk. Space- and time-resolved spectroscopy and time-integrated space-resolved calorimetry are employed as diagnostics. Graphite and tungsten samples are exposed to deuterium plasma streams. It is found that the radiative characteristics depend strongly on the target material. Tungsten plasma arises within 1 {micro}s close to the surface and shows continuum radiation only. Expansion of tungsten plasma is restricted. For a graphite target the plasma shield is a mixture of carbon and deuterium. It expands along the magnetic field lines with a velocity of v = (3--4) 10{sub 6} cm/s. The plasma shield is a two zone plasma with a hot low dense corona and a cold dense layer close to the target. The plasma corona emits intense soft x-ray (SXR) line radiation in the frequency range from 300--380 eV mainly from CV ions. It acts as effective dissipation system and converts volumetrically the incoming energy flux into SXR radiation.

  8. Progress of plasma wakefield self-modulation experiments at FACET

    Energy Technology Data Exchange (ETDEWEB)

    Adli, E., E-mail: Erik.Adli@fys.uio.no [Department of Physics, University of Oslo, N-0316 Oslo (Norway); SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Berglyd Olsen, V.K.; Lindstrøm, C.A. [Department of Physics, University of Oslo, N-0316 Oslo (Norway); SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Muggli, P.; Reimann, O. [Max Planck Institute for Physics, Munich (Germany); Vieira, J.M.; Amorim, L.D. [GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Téchnico, Universidade de Lisboa, 1049-001 Lisbon (Portugal); Clarke, C.I.; Gessner, S.J.; Green, S.Z.; Hogan, M.J.; Litos, M.D.; O' Shea, B.D.; Yakimenko, V. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Clayton, C.; Marsh, K.A.; Mori, W.B.; Joshi, C.; Vafaei-Najafabadi, N.; Williams, O. [University of California Los Angeles, Los Angeles, CA 90095 (United States)

    2016-09-01

    Simulations and theory predict that long electron and positron beams may under favorable conditions self-modulate in plasmas. We report on the progress of experiments studying the self-modulation instability in plasma wakefield experiments at FACET. The experimental results obtained so far, while not being fully conclusive, appear to be consistent with the presence of the self-modulation instability.

  9. First observation of a new zonal-flow cycle state in the H-mode transport barrier of the experimental advanced superconducting Tokamak

    DEFF Research Database (Denmark)

    Xu, G.S.; Wang, H. Q.; Wan, B. N.

    2012-01-01

    A new turbulence-flow cycle state has been discovered after the formation of a transport barrier in the H-mode plasma edge during a quiescent phase on the EAST superconducting tokamak. Zonal-flow modulation of high-frequency-broadband (0.05-1MHz) turbulence was observed in the steep-gradient regi...

  10. An Heuristic Drift-Based Model of the Power Scrape-Off Width in H-Mode Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Robert J. Goldston

    2011-02-28

    An heuristic model for the plasma scrape-off width in H-mode plasmas is introduced. Grad B and curv B drifts into the SOL are balanced against sonic parallel flows out of the SOL, to the divertor plates. The overall mass flow pattern posited is a modification for open field lines of Pfirsch-Shlüter flows to include sinks to the divertors. These assumptions result in an estimated SOL width of 2aρp/R. They also result in a first-principles calculation of the particle confinement time of H-mode plasmas, qualitatively consistent with experimental observations. It is next assumed that anomalous perpendicular electron thermal diffusivity is the dominant source of heat flux across the separatrix, investing the SOL width, defined above, with heat from the main plasma. The separatrix temperature is calculated based on a two-point model balancing power input to the SOL with Spitzer-Härm parallel thermal conduction losses to the divertor. This results in an heuristic closed-form prediction for the power scrape-off width that is in remarkable quantitative agreement both in absolute magnitude and in scaling with recent experimental data. Further work should include full numerical calculations, including all magnetic and electric drifts, as well as more thorough comparison with experimental data.

  11. Experiments on the propagation of plasma filaments.

    Science.gov (United States)

    Katz, Noam; Egedal, Jan; Fox, Will; Le, Ari; Porkolab, Miklos

    2008-07-04

    We investigate experimentally the motion and structure of isolated plasma filaments propagating through neutral gas. Plasma filaments, or "blobs," arise from turbulent fluctuations in a range of plasmas. Our experimental geometry is toroidally symmetric, and the blobs expand to a larger major radius under the influence of a vertical electric field. The electric field, which is caused by nabla B and curvature drifts in a 1/R magnetic field, is limited by collisional damping on the neutral gas. The blob's electrostatic potential structure and the resulting E x B flow field give rise to a vortex pair and a mushroom shape, which are consistent with nonlinear plasma simulations. We observe experimentally this characteristic mushroom shape for the first time. We also find that the blob propagation velocity is inversely proportional to the neutral density and decreases with time as the blob cools.

  12. The quasi-coherent signature of enhanced D{sub {alpha}} H-mode in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Snipes, J.A.; LaBombard, B.; Greenwald, M.; Hutchinson, I.H.; Irby, J.; Lin, Y.; Mazurenko, A.; Porkolab, M. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States)

    2001-04-01

    The steady-state H-mode regime found at moderate to high density in Alcator C-Mod, known as enhanced D{sub {alpha}} (EDA) H-mode, appears to be maintained by a continuous quasi-coherent (QC) mode in the steep edge gradient region. Large amplitude density and magnetic fluctuations with typical frequencies of about 100 kHz are driven by the QC mode. These fluctuations are measured in the steep edge gradient region by inserting a fast-scanning probe containing two poloidally separated Langmuir probes and a poloidal field pick-up coil. As the probe approaches the plasma edge, clear magnetic fluctuations were measured within about 2 cm of the last-closed flux surface (LCFS). The mode amplitude falls off rapidly with distance from the plasma centre with an exponential decay length of k{sub r} approx. 1.5 cm{sup -1}, measured 10 cm above the outboard midplane. The root-mean-square amplitude of the fluctuation extrapolated to the LCFS was B-tilde{sub {theta}} approx. 5 G. The density fluctuations, on the other hand, were visible on the Langmuir probe only when it was within a few millimetres of the LCFS. The potential and density fluctuations were sufficiently in phase to enhance particle transport at the QC mode frequency. These results show that the QC signature of the EDA H-mode is an electromagnetic mode that appears to be responsible for the enhanced particle transport in the plasma edge. (author). Letter-to-the-editor.

  13. The INAF/IAPS Plasma Chamber for ionospheric simulation experiment

    Science.gov (United States)

    Diego, Piero

    2016-04-01

    The plasma chamber is particularly suitable to perform studies for the following applications: - plasma compatibility and functional tests on payloads envisioned to operate in the ionosphere (e.g. sensors onboard satellites, exposed to the external plasma environment); - calibration/testing of plasma diagnostic sensors; - characterization and compatibility tests on components for space applications (e.g. optical elements, harness, satellite paints, photo-voltaic cells, etc.); - experiments on satellite charging in a space plasma environment; - tests on active experiments which use ion, electron or plasma sources (ion thrusters, hollow cathodes, field effect emitters, plasma contactors, etc.); - possible studies relevant to fundamental space plasma physics. The facility consists of a large volume vacuum tank (a cylinder of length 4.5 m and diameter 1.7 m) equipped with a Kaufman type plasma source, operating with Argon gas, capable to generate a plasma beam with parameters (i.e. density and electron temperature) close to the values encountered in the ionosphere at F layer altitudes. The plasma beam (A+ ions and electrons) is accelerated into the chamber at a velocity that reproduces the relative motion between an orbiting satellite and the ionosphere (≈ 8 km/s). This feature, in particular, allows laboratory simulations of the actual compression and depletion phenomena which take place in the ram and wake regions around satellites moving through the ionosphere. The reproduced plasma environment is monitored using Langmuir Probes (LP) and Retarding Potential Analyzers (RPA). These sensors can be automatically moved within the experimental space using a sled mechanism. Such a feature allows the acquisition of the plasma parameters all around the space payload installed into the chamber for testing. The facility is currently in use to test the payloads of CSES satellite (Chinese Seismic Electromagnetic Satellite) devoted to plasma parameters and electric field

  14. Progress toward positron-electron pair plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Stenson, E. V.; Stanja, J.; Hergenhahn, U. [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Saitoh, H. [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa (Japan); Niemann, H.; Pedersen, T. Sunn [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Marx, G. H.; Schweikhard, L. [Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Danielson, J. R.; Surko, C. M. [University of California, San Diego, La Jolla, CA USA (United States); Hugenschmidt, C. [Technische Universität München, Garching (Germany)

    2015-06-29

    Electron-positron plasmas have been of theoretical interest for decades, due to the unique plasma physics that arises from all charged particles having precisely identical mass. It is only recently, though, that developments in non-neutral plasma physics (both in linear and toroidal geometries) and in the flux of sources for cold positrons have brought the goal of conducting electron-positron pair plasma experiments within reach. The APEX/PAX collaboration is working on a number of projects in parallel toward that goal; this paper provides an overview of recent, current, and upcoming activities.

  15. Advanced Tokamak Plasmas in the Fusion Ignition Research Experiment

    Energy Technology Data Exchange (ETDEWEB)

    C.E. Kessel; D. Meade; D.W. Swain; P. Titus; M.A. Ulrickson

    2003-10-13

    The Advanced Tokamak (AT) capability of the Fusion Ignition Research Experiment (FIRE) burning plasma experiment is examined with 0-D systems analysis, equilibrium and ideal-MHD stability, radio-frequency current-drive analysis, and full discharge dynamic simulations. These analyses have identified the required parameters for attractive burning AT plasmas, and indicate that these are feasible within the engineering constraints of the device.

  16. Advanced Tokamak Scenarios for the FIRE Burning Plasma Experiment

    Energy Technology Data Exchange (ETDEWEB)

    C.E. Kessel; D. Ignat; T.K. Mau

    2001-10-12

    The advanced tokamak (AT) capability of the Fusion Ignition Research Experiment (FIRE) burning plasma experiment is examined with 0-D systems analysis, equilibrium and ideal-MHD stability, radio-frequency current-drive analysis, and full discharge dynamic simulations. These analyses have identified the required parameters for attractive burning advanced tokamak plasmas, and indicate that these are feasible with the present progress on existing experimental tokamaks.

  17. Electron cyclotron plasma startup in the GDT experiment

    Science.gov (United States)

    Yakovlev, D. V.; Shalashov, A. G.; Gospodchikov, E. D.; Solomakhin, A. L.; Savkin, V. Ya.; Bagryansky, P. A.

    2017-01-01

    We report on a new plasma startup scenario in the gas dynamic trap (GDT) magnetic mirror device. The primary 5 MW neutral beam injection (NBI) plasma heating system fires into a sufficiently dense plasma target (‘seed plasma’), which is commonly supplied by an arc plasma generator. In the reported experiments, a different approach to seed plasma generation is explored. One of the channels of the electron cyclotron resonance (ECR) heating system is used to ionize the neutral gas and build up the density of plasma to a level suitable for NBI capture. After a short transition of approximately 1 ms the discharge becomes essentially similar to a standard one initiated by the plasma gun. This paper presents the discharge scenario and experimental data on the seed plasma evolution during ECRH, along with the dependencies on incident microwave power, magnetic configuration and pressure of a neutral gas. The characteristics of the consequent high-power NBI discharge are studied and differences from the conventional scenario are discussed. A theoretical model describing the ECR breakdown and the seed plasma accumulation in a large-scale mirror trap is developed on the basis of the GDT experiment.

  18. Contoured-gap coaxial guns for imploding plasma liner experiments

    Science.gov (United States)

    Witherspoon, F. D.; Case, A.; Brockington, S.; Cassibry, J. T.; Hsu, S. C.

    2014-10-01

    Arrays of supersonic, high momentum flux plasma jets can be used as standoff compression drivers for generating spherically imploding plasma liners for driving magneto-inertial fusion, hence the name plasma-jet-driven MIF (PJMIF). HyperV developed linear plasma jets for the Plasma Liner Experiment (PLX) at LANL where two guns were successfully tested. Further development at HyperV resulted in achieving the PLX goal of 8000 μg at 50 km/s. Prior work on contoured-gap coaxial guns demonstrated an approach to control the blowby instability and achieved substantial performance improvements. For future plasma liner experiments we propose to use contoured-gap coaxial guns with small Minirailgun injectors. We will describe such a gun for a 60-gun plasma liner experiment. Discussion topics will include impurity control, plasma jet symmetry and topology (esp. related to uniformity and compactness), velocity capability, and techniques planned for achieving gun efficiency of >50% using tailored impedance matched pulse forming networks. Mach2 and UAH SPH code simulations will be included. Work supported by US DOE DE-FG02-05ER54810.

  19. Plasma lens experiments at the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, B. [California Univ., Los Angeles, CA (United States)]|[Lawrence Berkeley Lab., CA (United States); Chattopadhyay, S. [Lawrence Berkeley Lab., CA (United States); Chen, P. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)] [and others

    1993-04-01

    We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 {times} 10{sup 10}, tunneling ionization of a gas target by an electron beam -- an effect which has never been observed before -- should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.

  20. Differences in the H-mode pedestal width of temperature and density

    Science.gov (United States)

    Schneider, P. A.; Wolfrum, E.; Groebner, R. J.; Osborne, T. H.; Beurskens, M. N. A.; Dunne, M. G.; Ferron, J. R.; Günter, S.; Kurzan, B.; Lackner, K.; Snyder, P. B.; Zohm, H.; the ASDEX Upgrade Team; the DIII-D Team; EFDA Contributors, JET

    2012-10-01

    A pedestal database was built using data from type-I ELMy H-modes of ASDEX Upgrade, DIII-D and JET. ELM synchronized pedestal data were analysed with the two-line method. The two-line method is a bilinear fit which shows better reproducibility of pedestal parameters than a modified hyperbolic tangent fit. This was tested with simulated and experimental data. The influence of the equilibrium reconstruction on pedestal parameters was investigated with sophisticated reconstructions from CLISTE and EFIT including edge kinetic profiles. No systematic deviation between the codes could be observed. The flux coordinate system is influenced by machine size, poloidal field and plasma shape. This will change the representation of the width in different coordinates, in particular, the two normalized coordinates ΨN and r/a show a very different dependence on the plasma shape. The scalings derived for the pedestal width, Δ, of all machines suggest a different scaling for the electron temperature and the electron density. Both cases show similar dependence with machine size, poloidal magnetic field and pedestal electron temperature and density. The influence of ion temperature and toroidal magnetic field is different on each of \\Delta_{T_\\rme} and \\Delta_{n_\\rme} . In dimensionless form the density pedestal width in ΨN scales with \\rho^{0.6}_{i\\star} , the temperature pedestal width with \\beta_p,ped^{0.5} . Both widths also show a strong correlation with the plasma shape. The shape dependence originates from the coordinate transformation and is not visible in real space. The presented scalings predict that in ITER the temperature pedestal will be appreciably wider than the density pedestal.

  1. An Experiment to Tame the Plasma Material Interface

    Energy Technology Data Exchange (ETDEWEB)

    Goldston, R J; Menard, J E; Allain, J P; Brooks, J N; Canik, J M; Doerner, R; Fu, G; Gates, D A; Gentile, C A; Harris, J H; Hassanein, A; Gorelenkov, N N; Kaita, R; Kaye, S M; Kotschenreuther, M; Kramer, G J; Kugel, H W; Maingi, R; Mahajan, S M; Majeski, R; Neumeyer, C L; Nygren, R E; Ono, M; Owen, L W; Ramakrishnan, S; Rognlien, T D; Ruzic, D N; Ryutov, D D; Sabbagh, S A; Skinner, C H; Soukhanovskii, V A; Stevenson, T N; Ulrickson, M A; Valanju, P M; Woolley, R D

    2009-01-08

    The plasma material interface in Demo will be more challenging than that in ITER, due to requirements for approximately four times higher heat flux from the plasma and approximately five times higher average duty factor. The scientific and technological solutions employed in ITER may not extrapolate to Demo. The key questions to be resolved for Demo and the resulting key requirements for an experiment to 'tame the plasma material interface' are analyzed. A possible design point for such an experiment is outlined.

  2. Application of the H-Mode, a Design and Interaction Concept for Highly Automated Vehicles, to Aircraft

    Science.gov (United States)

    Goodrich, Kenneth H.; Flemisch, Frank O.; Schutte, Paul C.; Williams, Ralph A.

    2006-01-01

    Driven by increased safety, efficiency, and airspace capacity, automation is playing an increasing role in aircraft operations. As aircraft become increasingly able to autonomously respond to a range of situations with performance surpassing human operators, we are compelled to look for new methods that help us understand their use and guide their design using new forms of automation and interaction. We propose a novel design metaphor to aid the conceptualization, design, and operation of highly-automated aircraft. Design metaphors transfer meaning from common experiences to less familiar applications or functions. A notable example is the "Desktop metaphor" for manipulating files on a computer. This paper describes a metaphor for highly automated vehicles known as the H-metaphor and a specific embodiment of the metaphor known as the H-mode as applied to aircraft. The fundamentals of the H-metaphor are reviewed followed by an overview of an exploratory usability study investigating human-automation interaction issues for a simple H-mode implementation. The envisioned application of the H-mode concept to aircraft is then described as are two planned evaluations.

  3. Phase Contrast Imaging Measurements of Edge Turbulence Across an H-mode Transition

    Science.gov (United States)

    Rost, J. C.; Marinoni, A.; Porkolab, M.; Burrell, K. H.

    2013-10-01

    The Phase Contrast Imaging (PCI) diagnostic on DIII-D provides a line-integrated measurement of density fluctuations. Analysis of previous PCI data taken during QH mode plasmas has revealed turbulence with short radial wavelengths and high frequencies which is generated by the well in the radial electric field Er. Application of these results allows us to study the rapid evolution in turbulence at an L-H transition. The dominant effect of the L-H transition on turbulence is a 70% drop in fluctuation amplitude. However high frequency fluctuations are seen to arise on the same time scale as the L-H transition (i.e. a few ms). Interpretation of the 2d spectrum S (k , f) of the PCI data of the line-integrated fluctuation, especially the Doppler shift and the ratio S (kpci / S (-kpci) , indicates that the high frequency fluctuations are located on the inner edge of the Er well. There is in addition a region of turbulence the PCI detects which is located outside the minimum of the Er well. This ongoing work will provide quantitative information on the evolution of the Er well at high time resolution across the L-H transition, important to understanding the interaction between turbulence and flow shear at the H-mode transition. Work supported by the US Department of Energy under DE-FG02-94ER54235 and DE-FC02-04ER54698.

  4. Edge simulations in ELMy H-mode discharges of EAST tokamak

    Science.gov (United States)

    Xia, T. Y.; Huang, Y. Q.; Xu, X. Q.; Wu, Y. B.; Wang, L.; Zheng, Z.; Liu, J. B.; Zang, Q.; Li, Y. Y.; Zhao, D.

    2017-10-01

    Simulations of ELM crash followed by a coherent mode, leading to transient divertor heat flux on EAST are achieved by the six-field two-fluid model in BOUT + + . Three EAST ELMy H-mode discharges with different pedestal structure, geometry and plasma current Ip are studied. The ELM-driven crash of the profiles in pedestal is reproduced, and the footprints of ELM filaments on targets are comparable with the measurements from divertor probes. A coherent mode is also found in the edge region in all the simulations after the ELM crash. The frequency and poloidal wave number are in the range of the edge coherent mode (ECM) on EAST. The magnetic fluctuations of the mode are smaller than the electric field fluctuations. The detailed comparisons between simulated mode structures with measurements will be reported. Statistical analysis on the simulated turbulent fluctuations shows that both the turbulent and blobby electron anomalous transport can pump the pedestal energy out into SOL, and then flow to divertors. The similar trend of the heat flux width with Ip is obtained in the simulations. The effects of the SOL current driven by LHW on ELMs will be discussed in this paper. This work was performed under the auspices of the US DOE by LLNL under contract DE-AC52-07NA27344. It was supported by the China NSF 11405215 and 11675217.

  5. Electron-cyclotron plasma startup in the GDT experiment

    CERN Document Server

    Yakovlev, D V; Gospodchikov, E D; Solomakhin, A L; Savkin, V Ya; Bagryansky, P A

    2016-01-01

    The paper reports on a new plasma startup scenario in the Gas Dynamic Trap (GDT) magnetic mirror device. The primary 5 MW neutral beam injection (NBI) plasma heating system fires into a sufficiently dense plasma target ("seed plasma"), which is commonly supplied by an arc plasma generator. In the reported experiments, a different approach to seed plasma generation is explored. One of the channels of the electron cyclotron resonance (ECR) heating system is used to ionize the neutral gas and build up the density of plasma to a level suitable for NBI capture. After a short transition (about 1 ms) the discharge becomes essentially similar to a standard one initiated by the plasma gun. The paper presents the discharge scenario and experimental data on the seed plasma evolution during ECR heating, along with the dependencies on incident microwave power, magnetic configuration and pressure of a neutral gas. The characteristics of consequent high-power NBI discharge are studied and differences to the conventional sce...

  6. A plasma wakefield acceleration experiment using CLARA beam

    Energy Technology Data Exchange (ETDEWEB)

    Xia, G., E-mail: guoxing.xia@cockcroft.ac.uk [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); The Cockcroft Institute, Sci-Tech Daresbury, Daresbury, Warrington (United Kingdom); Angal-Kalinin, D.; Clarke, J. [STFC/ASTeC, Daresbury, Warrington (United Kingdom); Smith, J. [Tech-X UK Corporation, Daresbury Innovation Centre, Warrington (United Kingdom); Cormier-Michel, E. [Tech-X Corporation, Boulder, CO (United States); Jones, J.; Williams, P.H.; Mckenzie, J.W.; Militsyn, B.L. [STFC/ASTeC, Daresbury, Warrington (United Kingdom); Hanahoe, K.; Mete, O. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); The Cockcroft Institute, Sci-Tech Daresbury, Daresbury, Warrington (United Kingdom); Aimidula, A.; Welsch, C.P. [The Cockcroft Institute, Sci-Tech Daresbury, Daresbury, Warrington (United Kingdom); The University of Liverpool, Liverpool (United Kingdom)

    2014-03-11

    We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility CLARA (Compact Linear Accelerator for Research and Applications) at Daresbury Laboratory. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in electron beam driven plasma wakefield acceleration, e.g. high gradient plasma wakefield excitation driven by a relativistic electron bunch, two bunch experiment for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and some other advanced beam dynamics issues. This paper presents the feasibility studies of electron beam transport to meet the requirements for beam driven wakefield acceleration and presents the plasma wakefield simulation results based on CLARA beam parameters. Other possible experiments which can be conducted at the PARS beam line are also discussed.

  7. Nonneutral plasma diagnostic commissioning for the ALPHA Antihydrogen experiment

    Science.gov (United States)

    Konewko, S.; Friesen, T.; Tharp, T. D.; Alpha Collaboration

    2017-10-01

    The ALPHA experiment at CERN creates antihydrogen by mixing antiproton and positron plasmas. Diagnostic measurements of the precursor plasmas are performed using a diagnostic suite, colloquially known as the ``stick.'' This stick has a variety of sensors and is able to move to various heights to align the desired diagnostic with the beamline. A cylindrical electrode, a faraday cup, an electron gun, and a microchannel-plate detector (MCP) are regularly used to control and diagnose plasmas in ALPHA. We have designed, built, and tested a new, upgraded stick which includes measurement capabilities in both beamline directions.

  8. Experiments on planar plasma flow switches at Los Alamos

    Energy Technology Data Exchange (ETDEWEB)

    Benage, J.F. Jr.; Wysocki, F.J.; Bowers, R.; Oona, H. [and others

    1997-12-01

    The authors have performed a series of experiments on the Colt facility at Los Alamos to study the performance of plasma flow switches and to understand the important physics issues which affect that performance. These experiments were done in planar geometry on a small machine to allow for better diagnostic access and a higher repetition rate. The Colt facility is a capacitor bank which stores 300 kJ at maximum charge and produced a peak current of 1.1 MA in 2.0 microseconds for these experiments. The diagnostics used for these experiments included an array of b-dot probes, visible framing pictures, visible spectroscopy, and laser interferometry. Characteristics of the switch are determined from spatial and temporal profiles of the magnetic field and the spatial profile and temperature of the switch plasma. Here the authors present results from experiments for a variety of switch conditions.

  9. Electron plasma for antiproton cooling in the ATHENA experiment

    CERN Document Server

    Amoretti, M; Lagomarsino, V; Manuzio, G; Testera, G; Variola, A

    2002-01-01

    The first phase of the ATHENA (Antihydrogen Apparatus) experiment is devoted to the study of cold antihydrogen production. The apparatus includes an antiproton capture trap designed to trap and to cool antiprotons coming from the CERN Antiproton Decelerator (AD). The antiproton cooling is achieved by means of the collisional interaction with a cold cloud of trapped electrons. The electron plasma is loaded in the trap before the antiproton capture by means of a small-size heated filament and cooled to sub-eV temperatures by cyclotron radiation. We report some measurements devoted to the characterization of the electron plasma. The ATHENA apparatus design does not allow the use of complex diagnostics; therefore the plasma properties are obtained using electrostatic wall probes, radio- frequency diagnostics, and dumping the electrons onto a charge collector. A simple experimental method to obtain an estimate of the electron plasma radius is discussed. (9 refs).

  10. Short wavelength turbulence generated by shear in the quiescent H-mode edge on DIII–D

    Energy Technology Data Exchange (ETDEWEB)

    Rost, J. C.; Porkolab, M.; Dorris, J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Burrell, K. H. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

    2014-06-15

    A region of turbulence with large radial wavenumber (k{sub r}ρ{sub s}>1) is found in the high-shear portion of the plasma edge in Quiescent H-mode (QH-mode) on DIII–D using the Phase Contrast Imaging (PCI) diagnostic. At its peak outside the minimum of the E{sub r} well, the turbulence exhibits large amplitude n{sup ~}/n∼40%, with large radial wavenumber |k{sup ¯}{sub r}/k{sup ¯}{sub θ}|∼11 and short radial correlation length L{sub r}/ρ{sub i}∼0.2. The turbulence inside the E{sub r} well minimum is characterized by the opposite sign in radial wavenumber from that of turbulence outside the minimum, consistent with the expected effects of velocity shear. The PCI diagnostic provides a line-integrated measurement of density fluctuations, so data are taken during a scan of plasma position at constant parameters to allow the PCI to sample a range in k{sub r}/k{sub θ}. Analysis of the Doppler shift and plasma geometry allows the turbulence to be localized to a narrow region 3 mm inside the last closed flux surface, outside the minimum of the E{sub r} well. The turbulence amplitude and radial wavenumber and correlation length are determined by fitting the PCI results with a simple non-isotropic turbulence model with two regions of turbulence. These PCI observations, made in QH-mode, are qualitatively similar to those made in standard edge localized modes (ELM)-free H-mode and between ELMs, suggesting a similar role for large k{sub r} turbulence there.

  11. Short wavelength turbulence generated by shear in the quiescent H-mode edge on DIII-D

    Science.gov (United States)

    Rost, J. C.; Porkolab, M.; Dorris, J.; Burrell, K. H.

    2014-06-01

    A region of turbulence with large radial wavenumber (krρs>1) is found in the high-shear portion of the plasma edge in Quiescent H-mode (QH-mode) on DIII-D using the Phase Contrast Imaging (PCI) diagnostic. At its peak outside the minimum of the Er well, the turbulence exhibits large amplitude n ˜/n˜40%, with large radial wavenumber |k¯r/k¯θ|˜11 and short radial correlation length Lr/ρi˜0.2. The turbulence inside the Er well minimum is characterized by the opposite sign in radial wavenumber from that of turbulence outside the minimum, consistent with the expected effects of velocity shear. The PCI diagnostic provides a line-integrated measurement of density fluctuations, so data are taken during a scan of plasma position at constant parameters to allow the PCI to sample a range in kr/kθ. Analysis of the Doppler shift and plasma geometry allows the turbulence to be localized to a narrow region 3 mm inside the last closed flux surface, outside the minimum of the Er well. The turbulence amplitude and radial wavenumber and correlation length are determined by fitting the PCI results with a simple non-isotropic turbulence model with two regions of turbulence. These PCI observations, made in QH-mode, are qualitatively similar to those made in standard edge localized modes (ELM)-free H-mode and between ELMs, suggesting a similar role for large kr turbulence there.

  12. Tritium Plasma Experiment (TPE) - parameters and potentials for fusion plasma-wall interaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Masashi Shimada; Robert D. Kolasinski; J. Phillip Sharpe; Rion A. Causey

    2011-08-01

    The Tritium plasma experiment (TPE) is a unique facility devoted to experiments on the behavior of deuterium/tritium in toxic (e.g. beryllium) and radioactive materials for fusion plasma-wall interaction (PWI) studies. A Langmuir probe was added to the system to characterize the plasma conditions in TPE. With this new diagnostic, we found the achievable electron temperature ranged from 5.0 to 10.0 eV, the electron density varied from 5.0 x 10{sup 16} to 2.5 x 10{sup 18} m{sup -3}, and the ion flux density varied between 5.0 x 10{sup 20} to 2.5 x 10{sup 22} m{sup -2}s{sup -1} along the centerline of the plasma. A comparison of these plasma parameters with the conditions expected for the plasma facing components (PFCs) in ITER shows that TPE is capable of achieving most (approximately 800 m{sup 2} of 850 m{sup 2} total PFCs area) of the expected ion flux density and electron density conditions.

  13. Solar array experiments on the SPHINX satellite. [Space Plasma High voltage INteraction eXperiment satellite

    Science.gov (United States)

    Stevens, N. J.

    1974-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

  14. An Intensified Photodiode Array for Characterizing Argon Plasma Jets on the Plasma Liner Experiment

    Science.gov (United States)

    Davis, J. S.; Awe, T. J.; Hsu, S. C.; Case, A.

    2011-10-01

    The Plasma Liner Experiment (PLX) will merge 30 high Mach number plasma jets to form an imploding spherical plasma liner for high energy density physics and magneto-inertial fusion studies. The peak stagnation pressures achieved will be highly dependent on the implosion velocity of the liner, which is in turn dependent on the velocities of the merging plasma jets. For initial experiments characterizing single jet propagation, an array of three intensified photodiode (gain of roughly 25 dB and a spectral range of 350-1100 nm) will be used to measure the jet's velocity (up to 50 km/s) and acceleration (if any) as it travels from the chamber wall toward the center of a 9 ft. diameter spherical vacuum chamber. By adding filters to the photodiodes, it will be possible to correlate stages of jet evolution to specific argon emission lines, thus providing information on the state of the argon plasma as it propagates. Alignment and light collection are achieved via an aperture, lens, and fiber optic chain with the photodiodes themselves situated in an electromagnetically shielded ``screen cage.'' This poster will discuss the detailed design, setup, alignment, and initial experimental data of the photodiode array. Supported by DOE Fusion Energy Sciences.

  15. Virus-inactivated plasma - Plasmasafe: a one-year experience

    Science.gov (United States)

    De Silvestro, Giustina; Bagatella, Paola; Tison, Tiziana; Quaino, Vania; Carraro, Paolo; Tenderini, Maria Luisa; Lazzaro, Annarosa; Marotti, Alberto

    2007-01-01

    Background Fresh-frozen plasma (FFP) is a widely used blood transfusion product. The transfusion safety of this product is ensured by legally obligatory tests, but can be further improved by using some technical procedures, such as methylene blue (MB) and solvent-detergent (SD) viral inactivation methods. Mainly organisational criteria led us to introduce the SD viral inactivation technique as a service activity. In this report we describe our first year of experience, following the introduction of the SD technique, and thus the use of SD-virally inactivated plasma (PlasmaSafe). Materials and methods In order to evaluate the appropriate use and the therapeutic efficacy of PlasmaSafe in our Blood Transfusion Unit, the following programme was planned: quality control [prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen] of the FFP units (N=312); evaluation of the clinical effectiveness on 490 patients (879 transfusion events); pre- and post-treatment monitoring of indicators of coagulation (PT, aPTT, fibrinogen, proteins S and C, factor VIII) on 15 patients; treatment of three patients with thrombotic thrombocytopenic purpura (TTP) undergoing plasma-exchange; haemovigilance of adverse reactions provoked by SD-plasma. Results The indicators of coagulation in the FFP units varied greatly: the PT ranged from 50–120%, the aPTT from 24–41 seconds and the fibrinogen concentration from 1.42–6.84 g/L. Seventy-six percent of the patients responded to the plasma administration; moreover, two of 15 patients in whom protein S was assayed, showed no increase of this haemostatic protein. The TTP patients responded to plasma exchange treatment following four sessions of apheresis. During the observation period 8,422 PlasmaSafe units were transfused and no adverse reactions were recorded. Conclusion PlasmaSafe, a pharmaceutical-like product with a standardised content of coagulation factors, was found to be effective at correcting coagulation

  16. A Proton-Driven Plasma Wakefield Acceleration experiment at CERN

    CERN Multimedia

    The AWAKE Collaboration has been formed in order to demonstrate protondriven plasma wakefield acceleration for the first time. This technology could lead to future colliders of high energy but of a much reduced length compared to proposed linear accelerators. The SPS proton beam in the CNGS facility will be injected into a 10m plasma cell where the long proton bunches will be modulated into significantly shorter micro-bunches. These micro-bunches will then initiate a strong wakefield in the plasma with peak fields above 1 GV/m that will be harnessed to accelerate a bunch of electrons from about 20MeV to the GeV scale within a few meters. The experimental program is based on detailed numerical simulations of beam and plasma interactions. The main accelerator components, the experimental area and infrastructure required as well as the plasma cell and the diagnostic equipment are discussed in detail. First protons to the experiment are expected at the end of 2016 and this will be followed by an initial 3–4 yea...

  17. Planetary Ring Simulation Experiment in Fine Particle Plasmas

    Science.gov (United States)

    Yokota, Toshiaki

    We are experimenting on the planetary ring formation by using two component fine particle plasmas generated by a boat method. Two component plasmas which were composed of positively charged particles and negatively charged particles were generated by UV irradiation of fine aluminum particles. A small insulator sphere in which a small permanent magnet was inserted was put into the fine particle plasmas, and was connected using insulator rods and rotated by a small motor. We were able to create a ring form of fine particle plasmas just like the Saturn ring by unipolar induction. The ring formation process was recorded on VTR and its motion was analyzed by using a computer. The experimental parameters for ring formation coincides almost with the estimated values. The particles had charges of ±25 electrons from analysis of the particle beam splitting after passage through a static electric and a static magnetic field. It is estimated that the fine particle plasmas were in strongly coupled state (Γ>1) in these experimental conditions. The charges of particles increased and Γ also increased when the power of the halogen lamp was increased. The relations between the rotating frequency and the motion of ring and charge dependency were investigated mainly by using an optical method

  18. Heat flux pattern in detached L-modes and ELM mitigated H-modes with rotating magnetic perturbations in ASDEX Upgrade

    Science.gov (United States)

    Brida, D.; Lunt, T.; Wischmeier, M.; Bernert, M.; Carralero, D.; Faitsch, M.; Feng, Y.; Sehmer, T.; Sieglin, B.; Suttrop, W.; Wolfrum, E.; The ASDEX Upgrade Team; The MST1 Team

    2017-11-01

    For the first time divertor heat and particle fluxes in high-recycling and detached deuterium L- and H-mode plasmas with rotating magnetic perturbations (MPs) have been measured systematically in the ASDEX Upgrade (AUG) tokamak. The capability to rotate the MP field in AUG enabled us to obtain full two-dimensional profiles of the fluxes from measurements with the divertor triple Langmuir probes. As the divertor detached it was found that the initially non-axisymmetric heat flux became increasingly axisymmetric. In particular no ‘burn-through’ of the lobes was observed in the detached divertor in H-mode. Furthermore, the measurements were compared with simulations of the transport code EMC3-EIRENE as well as a simplified model based on field line tracing.

  19. Taylor-Dean flow on the Plasma Couette Experiment (PCX)

    Science.gov (United States)

    Flanagan, K.; Clark, M.; Collins, C.; Cooper, C.; Khalzov, I.; Wallace, J.; Forest, C.

    2014-10-01

    A Taylor-Dean flow profile is implemented on the upgraded Plasma Couette Experiment (PCX) aimed at exciting the magnetorotational instability (MRI). Taylor-Dean flow profiles are set up by injecting torque via a radial current crossing an axial magnetic field. A ``virtual cathode'' is set up in the center of PCX by applying a bias from a cathode located at the top center of the vessel to an anode at the bottom. This circuit is biased with respect to anodes at the outer wall to drive a radial current. A small vertical magnetic field is then applied via external Helmholtz coils in order to induce a J × B torque. Theoretical investigations have shown that the ion-neutral drag in PCX plasmas with low ionization fractions negatively affect the MRI threshold and growth rate. In order to increase the ionization fraction in PCX, upgrades to the multicusp magnet system and microwave power are underway. New SmCo magnets, like those used on the Madison Plasma Dynamo Experiment (MPDX), will provide better confinement and tolerate higher plasma temperatures than the previous ceramic ones. A MRI stability analysis of Taylor-Dean flows under relevant PCX parameters as well as early flow data will be presented.

  20. Atomic kinetics of a neon photoionized plasma experiment at Z

    Science.gov (United States)

    Mayes, D. C.; Mancini, R. C.; Schoenfeld, R. P.; Bailey, J. E.; Loisel, G. P.; Rochau, G. A.; ZAPP Collaboration

    2017-10-01

    We discuss an experimental effort to study the atomic kinetics in neon photoionized plasmas via K-shell line absorption spectroscopy. The experiment employs the intense x-ray flux emitted at the collapse of a Z-pinch to heat and backlight a photoionized plasma contained within a cm-scale gas cell placed at various distances from the Z-pinch and filled with neon gas pressures in the range from 3.5 to 120 Torr. The experimental platform affords an order of magnitude range in the ionization parameter characterizing the photoionized plasma from about 5 to 80 erg*cm/s. Thus, the experiment allows for the study of trends in ionization distribution as a function of the ionization parameter. An x-ray crystal spectrometer capable of collecting both time-integrated and time-gated data is used to collect absorption spectra. The spectra show line absorption by several ionization stages of neon, including Be-, Li-, He-, and H-like ions. Analysis of these spectra yields ion areal-densities and charge state distributions, which can be compared with results from atomic kinetics codes. In addition, the electron temperature is extracted from level population ratios of nearby energy levels in Li- and Be-like ions, which can be used to test heating models of photoionized plasmas. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451, and the Z Facility Fundamental Science Program of SNL.

  1. Agglomeration processes in carbonaceous dusty plasmas, experiments and numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dap, S; Hugon, R; De Poucques, L; Bougdira, J [Nancy Universite-Institut Jean Lamour, Dpt CP2S UMR 7198 CNRS, Faculte des Sciences et Technologies, BP 70239, 54506 Vandoeuvre-les-Nancy cedex (France); Lacroix, D [Nancy Universite-LEMTA, UMR 7563 CNRS, Faculte des Sciences et Technologies, BP 70239, 54506 Vandoeuvre-les-Nancy cedex (France); Patisson, F, E-mail: david.lacroix@lemta.uhp-nancy.f [Nancy Universite-Institut Jean Lamour, Dpt SI2M UMR 7198 CNRS, Ecole des Mines de Nancy, Parc de Saurupt-CS 14234, 54042 Nancy cedex (France)

    2010-09-15

    This paper deals with carbon dust agglomeration in radio frequency acetylene/argon plasma. Two studies, an experimental and a numerical one, were carried out to model dust formation mechanisms. Firstly, in situ transmission spectroscopy of dust clouds in the visible range was performed in order to observe the main features of the agglomeration process of the produced carbonaceous dust. Secondly, numerical simulation tools dedicated to understanding the achieved experiments were developed. A first model was used for the discretization of the continuous population balance equations that characterize the dust agglomeration process. The second model is based on a Monte Carlo ray-tracing code coupled to a Mie theory calculation of dust absorption and scattering parameters. These two simulation tools were used together in order to numerically predict the light transmissivity through a dusty plasma and make comparisons with experiments.

  2. Bifurcation of quiescent H-mode to a wide pedestal regime in DIII-D and advances in the understanding of edge harmonic oscillations

    Science.gov (United States)

    Chen, Xi; Burrell, K. H.; Osborne, T. H.; Barada, K.; Ferraro, N. M.; Garofalo, A. M.; Groebner, R. J.; McKee, G. R.; Petty, C. C.; Porkolab, M.; Rhodes, T. L.; Rost, J. C.; Snyder, P. B.; Solomon, W. M.; Yan, Z.; The DIII-D Team

    2017-08-01

    New experimental studies and modelling of the coherent edge harmonic oscillation (EHO), which regulates the conventional Quiescent H-mode (QH-mode) edge, validate the proposed hypothesis of edge rotational shear in destabilizing the low-n kink-peeling mode as the additional drive mechanism for the EHO. The observed minimum edge E  ×  B shear required for the EHO decreases linearly with pedestal collisionality ν \\text{e}\\ast , which is favorable for operating QH-mode in machines with low collisionality and low rotation such as ITER. In addition, the QH-mode regime in DIII-D has recently been found to bifurcate into a new ‘wide-pedestal’ state at low torque in double-null shaped plasmas, characterized by increased pedestal height, width and thermal energy confinement (Burrell 2016 Phys. Plasmas 23 056103, Chen 2017 Nucl. Fusion 57 022007). This potentially provides an alternate path for achieving high performance ELM-stable operation at low torque, in addition to the low-torque QH-mode sustained with applied 3D fields. Multi-branch low-k and intermediate-k turbulences are observed in the ‘wide-pedestal’. New experiments support the hypothesis that the decreased edge E  ×  B shear enables destabilization of broadband turbulence, which relaxes edge pressure gradients, improves peeling-ballooning stability and allows a wider and thus higher pedestal. The ability to accurately predict the critical E  ×  B shear for EHO and maintain high performance QH-mode at low torque is an essential requirement for projecting QH-mode operation to ITER and future machines.

  3. Compatibility of separatrix density scaling for divertor detachment with H-mode pedestal operation in DIII-D

    Science.gov (United States)

    Leonard, A. W.; McLean, A. G.; Makowski, M. A.; Stangeby, P. C.

    2017-08-01

    The midplane separatrix density is characterized in response to variations in upstream parallel heat flux density and central density through deuterium gas injection. The midplane density is determined from a high spatial resolution Thomson scattering diagnostic at the midplane with power balance analysis to determine the separatrix location. The heat flux density is varied by scans of three parameters, auxiliary heating, toroidal field with fixed plasma current, and plasma current with fixed safety factor, q 95. The separatrix density just before divertor detachment onset is found to scale consistent with the two-point model when radiative dissipation is taken into account. The ratio of separatrix to pedestal density, n e,sep/n e,ped varies from  ⩽30% to  ⩾60% over the dataset, helping to resolve the conflicting scaling of core plasma density limit and divertor detachment onset. The scaling of the separatrix density at detachment onset is combined with H-mode power threshold scaling to obtain a scaling ratio of minimum n e,sep/n e,ped expected in future devices.

  4. Momentum transport studies in JET H-mode discharges with an enhanced toroidal field ripple

    NARCIS (Netherlands)

    de Vries, P. C.; Versloot, T. W.; Salmi, A.; Hua, M. D.; Howell, D. H.; Giroud, C.; Parail, V.; Saibene, G.; Tala, T.

    2010-01-01

    In this study, enhancement of the toroidal field (TF) ripple has been used as a tool in order to reveal the impact of the momentum pinch on the rotation profiles in H-mode JET discharges. The analysis showed that flatter rotation profiles were obtained in discharges with a high TF ripple, attributed

  5. Plasma density observations from the Dynamic Ionosphere Cubesat Experiment (DICE)

    Science.gov (United States)

    Barjatya, A.; Swenson, C.; Fish, C. S.; Crowley, G.; Pilinski, M.; Azeem, S. I.; Neilsen, T. L.

    2012-12-01

    The Dynamic Ionosphere Cubesat Experiment (DICE) was launched into an eccentric low Earth orbit on October 28, 2011 on a NASA rocket from Vandenburg Air Force Base. DICE consists of two identical 1.5U CubeSats with a mission objective to study and characterize geomagnetic Storm Enhanced Density (SED) bulge and plume by multipoint measurements. Each identical spacecraft carries two Langmuir probes to measure in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a magnetometer to measure in-situ DC and AC magnetic fields. This work presents Langmuir probe data from both the CubeSats as they follow each other. The two Langmuir probes are deployed 180 degrees apart on 10cm long scissor booms from the top and bottom of the CubeSats. The probes are primarily operated in the ion saturation region as fixed bias probes to give relative plasma densities, but periodically swept (every 100 seconds) to give absolute plasma density and temperature. The derived densities will be compared to International Reference Ionosphere as well as other models.; Comparison of relative plasma density derived from two fixed bias Langmuir probes (DCP+ and DCP-) on DICE with IRI model.

  6. QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

    Energy Technology Data Exchange (ETDEWEB)

    WEST,WP; BURRELL,KH; deGRASSIE,JS; DOYLE,EJ; GREENFIELD,CM; LASNIER,CJ; SNYDER,PB; ZENG,L

    2003-08-01

    OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.

  7. Initial Thomson Scattering Survey of Local Helicity Injection and Ohmic Plasmas at the Pegasus Toroidal Experiment

    Science.gov (United States)

    Schlossberg, D. J.; Bodner, G. M.; Bongard, M. W.; Fonck, R. J.; Winz, G. R.

    2014-10-01

    A multipoint Thomson scattering diagnostic has recently been installed on the Pegasus ST. The system utilizes a frequency-doubled Nd:YAG laser (λ0 ~ 532 nm), spectrometers with volume phase holographic gratings, and a gated, intensified CCD camera. It provides measurements of Te and ne at 8 spatial locations for each spectrometer once per discharge. A new multiple aperture and beam dump system has been implemented to mitigate interference from stray light. This system has provided initial measurements in the core region of plasmas initiated by local helicity injection (LHI), as well as conventional Ohmic L- and H-mode discharges. Multi-shot averages of low-density (ne ~ 3 ×1018 m-3) , Ip ~ 0 . 1 MA LHI discharges show central Te ~ 75 eV at the end of the helicity injection phase. Ip ~ 0 . 13 MA Ohmic plasmas at moderate densities (ne ~ 2 ×1019 m-3) have core Te ~ 150 eV in L-mode. Generally, these plasmas do not reach transport equilibrium in the short 25 ms pulse length available. After an L-H transition, strong spectral broadening indicates increasing Te, to values above the range of the present spectrometer system with a high-dispersion VPH grating. Near-term system upgrades will focus on deploying a second spectrometer, with a lower-dispersion grating capable of measuring the 0.1-1.0 keV range. The second spectrometer system will also increase the available number of spatial channels, enabling study of H-mode pedestal structure. Work supported by US DOE Grant DE-FG02-96ER54375.

  8. Laser-Plasma experiments at ELI-NP

    Science.gov (United States)

    Ghenuche, Petru; Negoita, Florin; Diaconescu, Bogdan; Stutman, Dan

    2017-10-01

    Recent advances in ultra-high power lasers architecture brings unprecedented intensity and pressure regimes within our reach. Extreme Light Infrastructure - Nuclear Physics (ELI-NP) is a new large laser facility, part of the ELI European research infrastructure that will benefit from these upgrades in the next years. It has the ambitious goal to use extreme electromagnetic fields generated by two 10 PW laser beams for a broad range of research topics in fundamental physics at the frontier of plasma physics, nuclear physics and astrophysics, together with applied research in materials and life sciences. Here we describe the facility implementation status and challenges and the commissioning experiments related with laser-plasma interaction.

  9. The Skylab barium plasma injection experiments. I - Convection observations

    Science.gov (United States)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Peek, H. M.

    1976-01-01

    Two barium-plasma injection experiments were carried out during magnetically active periods in conjunction with the Skylab 3 mission. The high-explosive shaped charges were launched near dawn on November 27 and December 4, 1973, UT. In both cases, the AE index was near 400 gammas, and extensive pulsating auroras covered the sky. The first experiment, Skylab Alpha, occurred in the waning phase of a 1000-gamma substorm, and the second, Skylab Beta, occurred in the expansive phase of an 800-gamma substorm. In both, the convection was generally magnetically eastward, with 100-km-level electric fields near 40 mV/m. However, in the Alpha experiment the observed orientation of the barium flux tube fit theoretical field lines having no parallel current, but the Beta flux-tube orientation indicated a substantial upward parallel sheet current.

  10. Study on divertor particle and heat fluxes from electric probe measurements during ELMy H-modes in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Bak, Jun-Gyo, E-mail: jgbak@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, Heung-Su [National Fusion Research Institute, Daejeon (Korea, Republic of); Bae, Min-Keun; Chung, Kyu-Sun [Hanyang University, Seoul (Korea, Republic of); Hong, Suk-Ho [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • The characteristics of the particle and heat fluxes were investigated during ELMs in H-modes under the LSN configuration in the KSTAR tokamak.. • There was relation between the ELM amplitude and the ELM frequency as ΔW{sub ELM}/W{sub TOT} ∝ 1/f{sub ELM} in the range of f{sub ELM} ≤ 200 Hz. • The trends of the peak amplitude of the divertor flux near the OSP during ELMs due to the ELM mitigation and the plasma shaping were investigated. • The ELMs were mitigated by MP field, SMBI and ECH. The ELM mitigations due to the MP field and the SMBI were stronger than one due to the ECH. • Finally, the particle flux, evaluated at the far scrape-off layer (SOL) region, was estimated to less than 1% of the divertor particle flux. - Abstract: The characteristics of the divertor particle and heat fluxes are investigated during ELM bursts in ELMy H-mode plasmas with the lower single null (LSN) configuration in Korea Superconducting Tokamak Advanced Research (KSTAR). The particle and heat fluxes are evaluated from the electric probe measurements at the divertor region. It is found that the peak amplitude of the divertor flux during an ELM burst obtained near the outer strike point (OSP) decreases up to about 20% as the ELM frequency increases by a factor of ∼6.5 due to the ELM mitigation and the plasma shaping, which is similar to the trend of the amplitude versus the frequency of the ELM observed in other tokamaks. The ELMs are mitigated by using several methods as magnetic perturbation (MP) field, supersonic molecular beam injection (SMBI) and electron cyclotron heating (ECH) at the edge region. In addition, the particle flux, evaluated at the far scrape-off layer (SOL) region, is less than 1% of the divertor particle flux. In this work, results from the experimental investigations of particle and heat fluxes during ELM bursts from the electric probe measurements at the divertor and far SOL regions are presented.

  11. Scaling Study of Reconnection Heating in Torus Plasma Merging Experiments

    Science.gov (United States)

    Ono, Yasushi; Akimitsu, Moe; Sawada, Asuka; Cao, Qinghong; Koike, Hideya; Hatano, Hironori; Kaneda, Taishi; Tanabe, Hiroshi

    2017-10-01

    We have been investigating toroidal plasma merging and reconnection for high-power heating of spherical tokamak (ST) and field-reversed configuration (FRC), using TS-3 (ST, FRC: R =0.2m, 1985-), TS-4 (ST, FRC: R =0.5m, 2000-), UTST (ST: R =0.45m, 2008-) and MAST (ST: R =0.9m, 2000-) devices. The series of merging experiments made clear the promising scaling and characteristics of reconnection heating: (i) its ion heating energy that scales with square of the reconnecting magnetic field Brec, (ii) its energy loss lower than 10%, (iii) its ion heating energy (in the downstream) 10 time larger than its electron heating energy (at around X-point) and (iv) low dependence of ion heating on the guide (toroidal) field Bg. The Brec2-scalingwas obtained when the current sheet was compressed to the order of ion gyrodadius. When the sheet was insufficiently compressed, the measured ion temperature was lower than the scaling prediction. Based on this scaling, we realized significant ion heating up to 1.2keV in MAST after 2D elucidation of ion heating up to 250eV in TS-3 [3,4]. This promising scaling leads us to new high Brec reconnection heating experiments for future direct access to burning plasma: TS-U (2017-) in Univ. Tokyo and ST-40 in Tokamak Energy Inc. (2017-). This presentation reviews major progresses in those toroidal plasma merging experiments for physics and fusion applications of magnetic reconnection.

  12. Initial Characterization of L-mode and H-mode Edge Turbulence in NSTX-U using Beam Emission Spectroscopy

    Science.gov (United States)

    Kriete, David; Fonck, Raymond; McKee, George; Smith, David

    2016-10-01

    Turbulence in L-mode and H-mode plasmas in NSTX-U has been measured using the upgraded 2D BES system. Plasma discharges exhibit a broadband turbulence spectrum up to 150 kHz. In addition, a broadband feature centered at 100 kHz is observed in the early, low density L-mode phase of a discharge with high neutral beam heating, but not in the late, high density L-mode phase of a discharge with low neutral beam heating. Normalized density fluctuation power reduces after the L-H transition by a factor of 10 in the outer edge region, and 5 in the inner edge region. More detailed characterization results, including correlation lengths, decorrelation times, and flow dynamics across the L-H transition, will be presented. Due to discontinuation of the photodiode currently used in BES detectors, the capacitances of several modern, PIN photodiodes have been measured to assess their suitability for BES measurements. The BES preamplifier board layout has been redesigned to test each of the potential replacement diodes. The redesign also enables automated fabrication and assembly of the preamplifiers, simplifying future expansions to the BES system. Finally, the design specifications of a survey spectrometer for impurity measurements with BES detectors will be discussed. This work is supported by US DOE Award Numbers DE-SC0001288 and DE-AC02-09CH11466.

  13. Alternating-code experiment for plasma-line studies

    Directory of Open Access Journals (Sweden)

    P. Guio

    Full Text Available We present results of the first plasma-line measurement of the incoherent spectrum using the alternating-code technique with the EISCAT VHF radar. This technique, which has earlier mostly been used to measure high-resolution E-region ion-line spectra, turned out to be a very good alternative to other techniques for plasma-line measurements. The experiment provides simultaneous measurement of the ion line and downshifted and upshifted plasma-line spectra with an altitude resolution of 3 km and a temporal resolution of 10 s. The measurements are taken around the peak of the F region, but not necessarily at the peak itself, as is the case with the long-pulse technique. The condition for success is that the scale height should be large enough such that the backscattered signal from the range extent of one gate falls inside the receiver filter. The data are analysed and the results are combined with the results of the ion-line data analysis to estimate electron mean drift velocity and thereafter electric currents along the line of sight of the radar using both the standard dispersion relation assuming a Maxwellian electron velocity distribution and the more recent model including a heat-flow correction term.

  14. TCV experiments towards the development of a plasma exhaust solution

    Science.gov (United States)

    Reimerdes, H.; Duval, B. P.; Harrison, J. R.; Labit, B.; Lipschultz, B.; Lunt, T.; Theiler, C.; Tsui, C. K.; Verhaegh, K.; Vijvers, W. A. J.; Boedo, J. A.; Calabro, G.; Crisanti, F.; Innocente, P.; Maurizio, R.; Pericoli, V.; Sheikh, U.; Spolare, M.; Vianello, N.; the TCV Team; the EUROfusion MST1 Team

    2017-12-01

    Research towards a plasma exhaust solution for a fusion power plant aims at validating edge physics models, strengthening predictive capabilities and improving the divertor configuration. The TCV tokamak is extensively used to investigate the extent that geometric configuration modifications can affect plasma exhaust performance. Recent TCV experiments continue previous detachment studies of Ohmically heated L-mode plasmas in standard single-null configurations, benefitting from a range of improved diagnostic capabilities. Studies were extended to nitrogen seeding and an entire suite of alternative magnetic configurations, including flux flaring towards the target (X divertor), increasing the outer target radius (Super-X) and movement of a secondary x-point inside the vessel (X-point target) as well as the entire range of snowflake configurations. Nitrogen seeding into a snowflake minus configuration demonstrated a regime with strong radiation in the large region between the two x-points, confirming EMC3-Eirene simulations, and opening a promising path towards highly radiating regimes with limited adverse effects on core performance.

  15. Non-equilibrium plasma experiments at The Pennsylvania State University

    Science.gov (United States)

    Knecht, Sean; Bilen, Sven; Micci, Michael

    2013-10-01

    The authors have recently established the capability at The Pennsylvania State University to generate non-equilibrium plasma in atmospheric-pressure air and liquids such as water and saline. The plasma is generated using a high-voltage pulser (Pacific-Electronics PT-55), which is capable of voltage pulses of 75-ns width, peak voltage >50 kV, with rise-times on the order of nanoseconds. The electrodes are tungsten wires of various diameters (50 μm, 175 μm, 254 μm) insulated with nylon tubing. The spacing of the electrodes is controlled with translating mounts with resolution of tens of microns. Spectroscopy (Ocean Optics Model HR2000) is presently used for line identification only. Current and voltage vs. time will be measured with a 500-MHz bandwidth oscilloscope, a high-voltage probe and a shunt resistor connected to the ground side of the circuit. Research directions presently being pursued include the effects of solution electrical conductivity on plasma production and propellant ignition studies. Data from several types of experiments will be presented.

  16. Structure and motion of edge turbulence in the National Spherical Torus Experiment and Alcator C-Moda)

    Science.gov (United States)

    Zweben, S. J.; Maqueda, R. J.; Terry, J. L.; Munsat, T.; Myra, J. R.; D'Ippolito, D.; Russell, D. A.; Krommes, J. A.; LeBlanc, B.; Stoltzfus-Dueck, T.; Stotler, D. P.; Williams, K. M.; Bush, C. E.; Maingi, R.; Grulke, O.; Sabbagh, S. A.; White, A. E.

    2006-05-01

    In this paper we compare the structure and motion of edge turbulence observed in L-mode vs. H-mode plasmas in the National Spherical Torus Experiment (NSTX) [M. Ono, M. G. Bell, R. E. Bell et al., Plasma Phys. Controlled Fusion 45, A335 (2003)]. The radial and poloidal correlation lengths are not significantly different between the L-mode and the H-mode in the cases examined. The poloidal velocity fluctuations are lower and the radial profiles of the poloidal turbulence velocity are somewhat flatter in the H-mode compared with the L-mode plasmas. These results are compared with similar measurements Alcator C-Mod [E. Marmar, B. Bai, R. L. Boivin et al., Nucl. Fusion 43, 1610 (2003)], and with theoretical models.

  17. Diagnostic Systems for the Compact Burning Plasma Experiment Ignitor

    Science.gov (United States)

    Bombarda, F.; Ignitor Diagnostics Group

    2002-11-01

    For any of the proposed burning plasma experiments one challenge will be that of selecting and fielding diagnostics systems able to operate under reactor-relevant neutron fluxes, but at low fluence. The Ignitor approach to diagnostics has been that of preferring conventional and well proven techniques over innovative concept. A basic set needed for machine operation and experimental documentation has been assessed. Diagnostics considered essential to the mission of the experiment and not already available, such as neutron spectrometry, have been proposed, built and implemented on existing devices. The physics requirement and justifications for the basic set of diagnostics systems are presented, with their tentative lay-out on the machine. Radiological issues are identified and possible solutions are presented. The viability of promising new techniques is discussed. Work supported in part by ENEA of Italy and by the US DOE.

  18. Parallel collisionless-shock experiments at the Large Plasma Device

    Science.gov (United States)

    Weidl, Martin; Heuer, Peter; Bondarenko, Anton; Schaeffer, Derek; Winske, Dan; Constantin, Carmen; Jenko, Frank; Niemann, Christoph

    2017-04-01

    Previous research on parallel collisionless shocks, which constitute an important part of the Earth's bow shock region, has been limited to satellite measurements and simulations. However, whether and how these collisionless shocks form depends on a wide range of parameters and scales, some of which can be established and measured more easily in a laboratory experiment. Using a kJ-class laser, an ongoing experimental campaign at the Large Plasma Device (LAPD) at UCLA in Los Angeles is expected to produce the first laboratory measurements of the formation of a parallel collisionless shock. We present hybrid kinetic/MHD simulations which show how ion-beam instabilities in the background plasma can be driven by ablating carbon ions from a polyethylene target, causing non-linear density oscillations which eventually develop into a propagating shock front. The free-streaming carbon ions can excite both the resonant right-hand instability and the non-resonant firehose mode, the latter of which has also received a lot of attention among astrophysicists as Bell's instability. We present measurements from a first trial experiment at LAPD, in which we have identified these instabilities, and discuss their respective roles for future shock formation and the basic microphysical processes which drive them.

  19. Electric Field Double Probe Measurements for Ionospheric Space Plasma Experiments

    Science.gov (United States)

    Pfaff, R.

    1999-01-01

    Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements in a variety of space plasma regimes including the magnetosphere, ionosphere, and mesosphere. Such experiments have been successfully flown on a variety of spacecraft including sounding rockets and satellites. Typical instrument designs involve a series of trades, depending on the science objectives, type of platform (e.g., spinning or 3-axis stabilized), expected plasma regime where the measurements will be made, available telemetry, budget, etc. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place spherical sensors at large distances (10m or more) from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "interferometer" technique. Accurate attitude knowledge enables B times V contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. We review the measurement technique for both DC and wave electric field measurements in the ionosphere discussing recent advances involving high resolution burst memories, multiple baseline double probes, new sensor surface materials, biasing techniques, and other considerations.

  20. Effect of Electron Energy Distribution on the Hysteresis of Plasma Discharge: Theory, Experiment, and Modeling

    Science.gov (United States)

    Lee, Hyo-Chang; Chung, Chin-Wook

    2016-09-01

    Hysteresis, which is the history dependence of physical systems, indicates that there are more-than-two stable points in a given condition, and it has been considered to one of the most important topics in fundamental physics. Recently, the hysteresis of plasma has become a focus of research because stable plasma operation is very important for fusion reactors, bio-medical plasmas, and industrial plasmas for nano-device fabrication process. Interestingly, the bi-stability characteristics of plasma with a huge hysteresis loop have been observed in inductive discharge plasmas Because hysteresis study in such plasmas can provide a universal understanding of plasma physics, many researchers have attempted experimental and theoretical studies. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. This research was partially supported by Korea Research Institute of Standard and Science.

  1. Comparing MHD simulations of RFP plasmas to RELAX experiments

    Science.gov (United States)

    McCollam, K. J.; den Hartog, D. J.; Jacobson, C. M.; Sauppe, J. P.; Masamune, S.; Sanpei, A.

    2015-11-01

    Standard reversed-field pinch (RFP) plasmas provide a nonlinear dynamical system as a validation domain for numerical MHD simulation codes, which can be applied to general toroidal confinement scenarios including tokamaks. Using the NIMROD code, we calculate linear stability and simulate the nonlinear evolution of plasmas similar to those in the RELAX RFP experiment, whose relatively modest Lundquist numbers of order 104 make the simulations tractable given present computing resources. The chosen RELAX cases cover a broad range of RFP reversal parameters and have also been previously simulated with the MIPS code (N. Mizuguchi et al., TH/P3-26, IAEA FEC, 2012). Experimental diagnostics that can be used for validation purposes include Thomson scattering for electron temperature, interferometry for electron density, SXR imaging, and external and internal magnetic probes. RELAX's small aspect ratio (~ 2) motivates a comparison study using toroidal and cylindrical geometries in NIMROD. This work is supported by the U.S. DOE and NSF and by the Japan Society for the Promotion of Science.

  2. Flowing dusty plasma experiments: Generation of flow and measurement techniques

    CERN Document Server

    Jaiswal, S; Sen, A

    2016-01-01

    A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a $\\Pi-$shaped Dusty Plasma Experimental (DPEx) device with micron size kaolin/Melamine Formaldehyde (MF) particles embedded in a background of Argon plasma created by a direct current (DC) glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super Particle Identification (sPIT) code, Particle Image Velocimetry (PIV) analysis and the excitation of Dust Acoustic Waves (DAWs). The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral dr...

  3. Interrelationship between Plasma Experiments in the Laboratory and in Space

    Energy Technology Data Exchange (ETDEWEB)

    Koepke, Mark E. [West Virginia Univ., Morgantown, WV (United States)

    2017-05-25

    Funds were expended to offset the travel costs of three students and three postdoctoral research associates to participate in and present work at the 2015 International Workshop on the Interrelationship between Plasma Experiments in the Laboratory and in Space (IPELS2015), 23-28 August 2015, Pitlochry, Scotland, UK. Selection was priority-ranked by lab-space engagement, first, and topic relevance, second. Supplementary selection preference was applied to under-represented populations, applicants lacking available travel-resources in their home research group, applicants unusually distant from the conference venue, and the impact of the applicant’s attendance in increasing the diversity of conference participation. One support letter per student was required. The letters described the specific benefit of IPELS2015 to the student dissertation or the postdoc career development, and document the evidence for the ordering criteria.

  4. Computer experiments on the relaxation of collisionless plasmas

    Science.gov (United States)

    Lapenta, Giovanni; Markidis, Stefano; Kaniadakis, Giorgio

    2009-02-01

    The relaxation of a collisionless plasma is not regulated by the usual collisional Boltzmann equation and its related H-theorem. The interactions are long range and the collisions are not instantaneous. A direct simulation approach is presented for measuring by computer experiment what the relaxed distribution is. The conclusion of the analysis is that the relaxed distribution includes both a low energy component that is well described using the usual Boltzmann distribution and a high energy tail described using a power law. The results of the simulation study are compared directly with the model recently proposed by Kaniadakis (2002 Phys. Rev. E 66 056125). The observed cumulative distribution function is well reproduced by the theory.

  5. Detection of inverse Compton scattering in plasma wakefield experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Simon

    2016-12-15

    Inverse Compton scattering (ICS) is the process of scattering of photons and electrons, where the photons gain a part of the electrons energy. In combination with plasma wakefield acceleration (PWA), ICS offers a compact MeV γ-ray source. A numerical study of ICS radiation produced in PWA experiments at FLASHForward was performed, using an ICS simulation code and the results from particle-in-cell modelling. The possibility of determining electron beam properties from measurements of the γ-ray source was explored for a wide range of experimental conditions. It was found that information about the electron divergence, the electron spectrum and longitudinal information can be obtained from measurements of the ICS beams for some cases. For the measurement of the ICS profile at FLASHForward, a CsI(Tl) scintillator array was chosen, similar to scintillators used in other ICS experiments. To find a suitable detector for spectrum measurements, an experimental test of a Compton spectrometer at the RAL was conducted. This test showed that a similar spectrometer could also be used at FLASHForward. However, changes to the spectrometer could be needed in order to use the pair production effect. In addition, further studies using Geant4 could lead to a better reconstruction of the obtained data. The studies presented here show that ICS is a promising method to analyse electron parameters from PWA experiments in further detail.

  6. Understanding Solar Coronal Heating through Atomic and Plasma Physics Experiments

    Science.gov (United States)

    Savin, Daniel Wolf; Arthanayaka, Thusitha; Bose, Sayak; Hahn, Michael; Beiersdorfer, Peter; Brown, Gregory V.; Gekelman, Walter; Vincena, Steve

    2017-08-01

    Recent solar observations suggest that the Sun's corona is heated by Alfven waves that dissipate at unexpectedly low heights in the corona. These observations raise a number of questions. Among them are the problems of accurately quantifying the energy flux of the waves and that of describing the physical mechanism that leads to the wave damping. We are performing laboratory experiments to address both of these issues.The energy flux depends on the electron density, which can be measured spectroscopically. However, spectroscopic density diagnostics have large uncertainties, because they depend sensitively on atomic collisional excitation, de-excitation, and radiative transition rates for multiple atomic levels. Essentially all of these data come from theory and have not been experimentally validated. We are conducting laboratory experiments using the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory that will provide accurate empirical calibrations for spectroscopic density diagnostics and which will also help to guide theoretical calculations.The observed rapid wave dissipation is likely due to inhomogeneities in the plasma that drive flows and currents at small length scales where energy can be more efficiently dissipated. This may take place through gradients in the Alfvén speed along the magnetic field, which causes wave reflection and generates turbulence. Alternatively, gradients in the Alfvén speed across the field can lead to dissipation through phase-mixing. Using the Large Plasma Device (LAPD) at the University of California Los Angeles, we are studying both of these dissipation mechanisms in the laboratory in order to understand their potential roles in coronal heating.

  7. Electron heat transport in EAST steady-state H-mode discharges with a weak electron internal transport barrier

    Science.gov (United States)

    Du, H.; Ding, S.; Chen, J.; Wang, Y.; Lian, H.; Liu, H.; Zang, Q.; Lyu, B.; Duan, Y.; Xu, G.; Qian, J.; Gong, X.

    2017-10-01

    The global confinement (H98) increases with the internal inductance (1.0 1.2) in the recent steady-state H-mode discharges, which exhibit a weak electron ITB started at ρ = 0.4 in EAST. After turning off ECRH, the stored energy decreases by 30% in 2.5 s. Calculations suggest that both the lower hybrid electron heating and driven current move from the core to large radii after turning off ECRH. Power balance analysis show that the LH deposition profile shift from just inside the ITB to outside the ITB after ECRH termination appears to be responsible for the marked drop in stored energy. The slow stored energy decrease is believed to be connected to the long plasma current profile relaxation time. Linear gyrokinetic simulations indicate increasing low-k instability growth rate from small to large radii, which is consistent with the reduced diffusivity within the ITB. The calculations also show that the CTEM dominate within the ITB, ETG modes grow rapidly outside this region, and that ITG modes dominate near the pedestal top. Work supported by the NNSF of China #11575248.

  8. Observations of highly sheared turbulence in the H-mode pedestal using Phase Contrast Imaging on DIII-D

    Science.gov (United States)

    Rost, J. C.; Marinoni, A.; Davis, E. M.; Porkolab, M.; Burrell, K. H.

    2017-10-01

    Highly sheared turbulence with short radial correlation lengths has been measured near the top of the H-mode pedestal, in addition to the previously measured highly-sheared turbulence measured in the Er well. Turbulence in regions of large velocity shear is characterized by radial correlation lengths shorter than the poloidal wavelength (L 200 kHz). The phase contrast imaging (PCI) diagnostic on DIII-D is ideally suited to measuring this density turbulence due to the measurement geometry and high frequency bandwidth. Radial localization is achieved by optical filtering, varying the ExB profile, and shifting the plasma position. Reconfiguration of the Er well, such as at the L-H transition or the transition to wide pedestal QH-mode, shows a near-instantaneous change (t < 1 ms) to the sheared turbulence in the Er well ( 1 cm inside the separatrix). In contrast, the sheared turbulence near the top of the pedestal ( 2 cm inside the separatrix) varies over times scales of tens of ms, consistent with pedestal evolution. Work supported by the US Department of Energy under DE-FG02-94ER54235 and DE-FC02-04ER54698.

  9. Outward particle transport by coherent mode in the H-mode pedestal in the Experimental Advanced Superconducting Tokamak (EAST)

    Science.gov (United States)

    Zhang, T.; Han, X.; Gao, X.; Liu, H. Q.; Shi, T. H.; Liu, J. B.; Liu, Y.; Kong, D. F.; Liu, Z. X.; Qu, H.; Xiang, H. M.; Geng, K. N.; Wang, Y. M.; Wen, F.; Zhang, S. B.; Ling, B. L.; the EAST Team

    2017-06-01

    A coherent mode (CM) in the edge pedestal region has been observed on different fluctuation quantities, including density fluctuation, electron temperature fluctuation and magnetic fluctuation in H mode plasma on the Experimental Advanced Superconducting Tokamak (EAST) tokamak. Measurements at different poloidal positions show that the local poloidal wavenumber is smallest at the outboard midplane and will increase with poloidal angle. This poloidal asymmetry is consistent with the flute-like assumption (i.e. k// ˜ 0) from which the toroidal mode number of the mode has been estimated as between 12 and 17. It was further found that the density fluctuation amplitude of the CM also demonstrated poloidal asymmetry. The appearance of a CM can clearly decrease or even stop the increase in the edge density, while the disappearance of a CM will lead to an increase in the pedestal density and density gradient. Statistical analysis showed there was a trend that as the CM mode amplitude increased, the rate of increase of the edge density decreased and the particle flux (Γdiv) onto the divertor plate increased. The CM sometimes showed burst behavior, and these bursts led bursts on Γdiv with a time of about 230 μs, which is close to the time for particle flow from the outer midplane to the divertor targets along the scrape-off layer magnetic field line. This evidence showed that the CM had an effect on the outward transport of particles.

  10. Pedestal properties of H-modes with negative triangularity using the EPED-CH model

    Science.gov (United States)

    Merle, A.; Sauter, O.; Medvedev, S. Yu

    2017-10-01

    The EPED model has been designed to predict the pedestal height and width from a minimal set of parameters and using the stability of the pedestal region for global MHD peeling-ballooning (P-B) modes as well as local kinetic ballooning modes (KBMs). This approach has been validated for type-I ELMy H-modes and quiescent H-modes (QH) but can also be used for other types of H-modes where it usually sets an upper limit on the achievable pedestal height. Using the recently developed EPED-like model called EPED-CH and based on the equilibrium codes CHEASE and CAXE and the MHD stability code KINX, we investigate in this work the effect of negative triangularity on the pedestal structure. Our simulation results confirm the experimental results from TCV where a reduction of the pedestal height was observed when going from positive to negative top triangularity. This was interpreted as a degradation of the peeling-ballooning stability due to the closed access to the second stability region for ballooning modes in the case of negative triangularity. This effect is further enhanced by the coupling to the KBM stability criterion in EPED simulations. The novel concept of the negative triangularity tokamak (a DEMO-sized machine) is also investigated. Again a strong reduction of the pedestal height and width is observed going from positive to negative triangularity for up-down symmetric equilibria. The pedestal height is also reduced going to more up-down asymmetric cases. The beneficial effect of the global β value on the pedestal height, which is linked to the second stability access, is strongly reduced for negative triangularity.

  11. Novel Feature of H-Mode Induced by CT Injection on STOR-M Tokamak

    Science.gov (United States)

    Sen, S.; Xiao, C.; Hirose, A.

    2000-10-01

    A novel feature of the H-mode induced by compact torus injection on STOR-M tokamak is observed. There is almost no change in the radial electric-field profiles during and after the L-H transition. The usual hypothesis of the E X B shear stabilization mechanism is therefore unlikely to play a role in this transition. A new mechanism of the stabilization of microinstabilities by parallel flow is suggested as the plausible cause for the transition to this improved regime.

  12. Crossbar H-mode drift-tube linac design with alternative phase focusing for muon linac

    Science.gov (United States)

    Otani, M.; Futatsukawa, K.; Hasegawa, K.; Kitamura, R.; Kondo, Y.; Kurennoy, S.

    2017-07-01

    We have developed a Crossbar H-mode (CH) drift-tube linac (DTL) design with an alternative phase focusing (APF) scheme for a muon linac, in order to measure the anomalous magnetic moment and electric dipole moment (EDM) of muons at the Japan Proton Accelerator Research Complex (J-PARC). The CH-DTL accelerates muons from β = v/c = 0.08 to 0.28 at an operational frequency of 324 MHz. The design and results are described in this paper.

  13. Plasma science and technology for emerging economies an AAAPT experience

    CERN Document Server

    2017-01-01

    This book highlights plasma science and technology-related research and development work at institutes and universities networked through Asian African Association for Plasma Training (AAAPT) which was established in 1988. The AAAPT, with 52 member institutes in 24 countries, promotes the initiation and intensification of plasma research and development through cooperation and technology sharing.   With 13 chapters on fusion-relevant, laboratory and industrial plasmas for wide range of applications and basic research and a chapter on AAAPT network, it demonstrates how, with collaborations, high-quality, industrially relevant academic and scientific research on fusion, industrial and laboratory plasmas and plasma diagnostics can be successfully pursued in small research labs.   These plasma sciences and technologies include pioneering breakthroughs and applications in (i) fusion relevant research in the quest for long-term, clean energy source development using high-temperature, high- density plasmas and (ii...

  14. Parametric dependencies of the experimental tungsten transport coefficients in ICRH and ECRH assisted ASDEX Upgrade H-modes

    Science.gov (United States)

    Sertoli, M.; Angioni, C.; Odstrcil, T.; ASDEX Upgrade Team; Eurofusion MST1 Team

    2017-11-01

    The profiles of the W transport coefficients have been experimentally calculated for a large database of identical ASDEX Upgrade H-mode discharges where only the radio-frequency (RF) power characteristics have been varied [Angioni et al., Nucl. Fusion 57, 056015 (2017)]. Central ion cyclotron resonance heating (ICRH) in the minority heating scheme has been compared with central and off-axis electron cyclotron resonance heating (ECRH), using both localized and broad heat deposition profiles. The transport coefficients have been calculated applying the gradient-flux relation to the evolution of the intrinsic W density in-between sawtooth cycles as measured using the soft X-ray diagnostic. For both ICRH and ECRH, the major player in reducing the central W density peaking is found to be the reduction of inward pinch and, in the case of ECRH, the rise of an outward convection. The impurity convection increases, from negative to positive, almost linearly with RF-power, while no appreciable changes are observed in the diffusion coefficient, which remains roughly at neoclassical levels independent of RF power or background plasma conditions. The ratio vW/DW is consistent with the equilibrium ∇ n W / n W prior to the sawtooth crash, corroborating the separate estimates of diffusion and convection. These experimental findings are slightly different from previous results obtained analysing the evolution of impurity injections over many sawtooth cycles. Modelling performed using the drift-kinetic code NEO and the gyro-kinetic code GKW (assuming axisymmetry) overestimates the diffusion coefficient and underestimates the experimental positive convection. This is a further indication that magneto-hydrodynamic/neoclassical models accounting for 3D effects may be needed to characterize impurity transport in sawtoothing tokamak plasmas.

  15. Advanced plasma flow simulations of cathodic-arc and ferroelectric plasma sources for neutralized drift compression experiments

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2008-07-01

    Full Text Available Large-space-scale and long-time-scale plasma flow simulations are executed in order to study the spatial and temporal evolution of plasma parameters for two types of plasma sources used in the neutralized drift compression experiment (NDCX. The results help assess the charge neutralization conditions for ion beam compression experiments and can be employed in more sophisticated simulations, which previously neglected the dynamical evolution of the plasma. Three-dimensional simulations of a filtered cathodic-arc plasma source show the coupling efficiency of the plasma flow from the source to the drift region depends on geometrical factors. The nonuniform magnetic topology complicates the well-known general analytical considerations for evaluating guiding-center drifts, and particle-in-cell simulations provide a self-consistent evaluation of the physics in an otherwise challenging scenario. Plasma flow profiles of a ferroelectric plasma source demonstrate that the densities required for longitudinal compression experiments involving ion beams are provided over the drift length, and are in good agreement with measurements. Simulations involving azimuthally asymmetric plasma creation conditions show that symmetric profiles are nevertheless achieved at the time of peak on-axis plasma density. Also, the ferroelectric plasma expands upstream on the thermal expansion time scale, and therefore avoids the possibility of penetration into the acceleration gap and transport sections, where partial neutralization would increase the beam emittance. Future experiments on NDCX will investigate the transverse focusing of an axially compressing intense charge bunch to a sub-mm spot size with coincident focal planes using a strong final-focus solenoid. In order to fill a multi-tesla solenoid with the necessary high-density plasma for beam charge neutralization, the simulations predict that supersonically injected plasma from the low-field region will penetrate and

  16. Experiments on helical modes in magnetized thin foil-plasmas

    Science.gov (United States)

    Yager-Elorriaga, David

    2017-10-01

    This paper gives an in-depth experimental study of helical features on magnetized, ultrathin foil-plasmas driven by the 1-MA linear transformer driver at University of Michigan. Three types of cylindrical liner loads were designed to produce: (a) pure magneto-hydrodynamic (MHD) modes (defined as being void of the acceleration-driven magneto-Rayleigh-Taylor instability, MRT) using a non-imploding geometry, (b) pure kink modes using a non-imploding, kink-seeded geometry, and (c) MRT-MHD coupled modes in an unseeded, imploding geometry. For each configuration, we applied relatively small axial magnetic fields of Bz = 0.2-2.0 T (compared to peak azimuthal fields of 30-40 T). The resulting liner-plasmas and instabilities were imaged using 12-frame laser shadowgraphy and visible self-emission on a fast framing camera. The azimuthal mode number was carefully identified with a tracking algorithm of self-emission minima. Our experiments show that the helical structures are a manifestation of discrete eigenmodes. The pitch angle of the helix is simply m / kR , from implosion to explosion, where m, k, and R are the azimuthal mode number, axial wavenumber, and radius of the helical instability. Thus, the pitch angle increases (decreases) during implosion (explosion) as R becomes smaller (larger). We found that there are one, or at most two, discrete helical modes that arise for magnetized liners, with no apparent threshold on the applied Bz for the appearance of helical modes; increasing the axial magnetic field from zero to 0.5 T changes the relative weight between the m = 0 and m = 1 modes. Further increasing the applied axial magnetic fields yield higher m modes. Finally, the seeded kink instability overwhelms the intrinsic instability modes of the plasma. These results are corroborated with our analytic theory on the effects of radial acceleration on the classical sausage, kink, and higher m modes. Work supported by US DOE award DE-SC0012328, Sandia National Laboratories

  17. Laboratory experiments on plasma jets in a magnetic field using high-power lasers

    Directory of Open Access Journals (Sweden)

    Nishio K.

    2013-11-01

    Full Text Available The experiments to simulate astrophysical jet generation are performed using Gekko XII (GXII HIPER laser system at the Institute of Laser Engineering. In the experiments a fast plasma flow generated by shooting a CH plane (10 μm thickness is observed at the rear side of the plane. By separating the focal spot of the main beams, a non-uniform plasma is generated. The non-uniform plasma flow in an external magnetic field (0.2∼0.3 T perpendicular to the plasma is more collimated than that without the external magnetic field. The plasma β, the ratio between the plasma and magnetic pressure, is ≫ 1, and the magnetic Reynolds number is ∼150 in the collimated plasma. It is considered that the magnetic field is distorted by the plasma flow and enhances the jet collimation.

  18. A Laboratory Plasma Experiment for Studying Magnetic Dynamics of Accretion Discs and Jets

    OpenAIRE

    Hsu, S. C.; Bellan, P. M.

    2002-01-01

    This work describes a laboratory plasma experiment and initial results which should give insight into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also plasma detachment associated with spheromak formation, which may have relevance to disc winds and flares. The plasmas are produced by a planar magnetized coaxial gun. The resulting...

  19. The Double Star Plasma Electron and Current Experiment

    Directory of Open Access Journals (Sweden)

    A. N. Fazakerley

    2005-11-01

    Full Text Available The Double Star Project is a collaboration between Chinese and European space agencies, in which two Chinese magnetospheric research spacecraft, carrying Chinese and European instruments, have been launched into equatorial (on 29 December 2003 and polar (on 25 July 2004 orbits designed to enable complementary studies with the Cluster spacecraft. The two Double Star spacecraft TC-1 and TC-2 each carry a Double Star Plasma Electron and Current Experiment (PEACE instrument. These two instruments were based on Cluster Flight Spare equipment, but differ from Cluster instruments in two important respects. Firstly, a Double Star PEACE instrument has only a single sensor, which must be operated in a manner not originally envisaged in the Cluster context in order to sample the full range of energies. Secondly, the DPU hardware was modified and major changes of onboard software were implemented, most notably a completely different approach to data compression has been adopted for Double Star, which allows high resolution 3-dimensional distributions to be transmitted almost every spin, a significant improvement over Cluster. This paper describes these instruments, and includes examples of data collected in various magnetospheric regions encountered by the spacecraft which have been chosen to illustrate the power of combined Double Star and Cluster measurements.

  20. Convex Crystal X-ray Spectrometer for Laser Plasma Experiments

    Energy Technology Data Exchange (ETDEWEB)

    May, M; Heeter, R; Emig, J

    2004-04-15

    Measuring time and space-resolved spectra is important for understanding Hohlraum and Halfraum plasmas. Experiments at the OMEGA laser have used the Nova TSPEC which was not optimized for the OMEGA diagnostic space envelope or for the needed spectroscopic coverage and resolution. An improved multipurpose spectrometer snout, the MSPEC, has been constructed and fielded on OMEGA. The MSPEC provides the maximal internal volume for mounting crystals without any beam interferences at either 2x or 3x magnification. The RAP crystal is in a convex mounting geometry bent to a 20 cm radius of curvature. The spectral resolution, E/dE, is about 200 at 2.5 keV. The spectral coverage is 2 to 4.5 keV. The MSPEC can record four separate spectra on the framing camera at time intervals of up to several ns. The spectrometer design and initial field-test performance will be presented and compared to that of the TSPEC. Work supported by U. S. DoE/UC LLNL contract W-7405-ENG-48

  1. Formation of counterstreaming plasmas for collisionless shock experiment

    Science.gov (United States)

    Ide, T.; Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Tanji, H.; Nishio, K.; Kuwada, M.; Ide, H.; Tsubouchi, K.; Shimazaki, S.; Taguchi, T.; Gregory, C.; Diziere, A.; Nakatsutsumi, M.; Koenig, M.; Ohnishi, N.; Takabe, H.

    2013-11-01

    Process of counterstreaming plasma generation for laser irradiation of the innner-surface of the first plane of a double-plane target is investigated. The image taken by streaked self-emission optical pyrometer and radiation hydrodynamic simulation show the plasma from the second plane is ablated by radiation almost at the laser timing. After ˜5ns, increase in brightness and the generation of a plasma on the second plane are observed. According to the contemporary measurement of streaked interferometry, this is caused by the ablation of the second plane by the first plane plasma.

  2. Formation of counterstreaming plasmas for collisionless shock experiment

    Directory of Open Access Journals (Sweden)

    Ide T.

    2013-11-01

    Full Text Available Process of counterstreaming plasma generation for laser irradiation of the innner-surface of the first plane of a double-plane target is investigated. The image taken by streaked self-emission optical pyrometer and radiation hydrodynamic simulation show the plasma from the second plane is ablated by radiation almost at the laser timing. After ∼5ns, increase in brightness and the generation of a plasma on the second plane are observed. According to the contemporary measurement of streaked interferometry, this is caused by the ablation of the second plane by the first plane plasma.

  3. Development of high energy pulsed plasma simulator for plasma-lithium trench experiment

    Science.gov (United States)

    Jung, Soonwook

    To simulate detrimental events in a tokamak and provide a test-stand for a liquid lithium infused trench (LiMIT) device, a pulsed plasma source utilizing a theta pinch in conjunction with a coaxial plasma accelerator has been developed. An overall objective of the project is to develop a compact device that can produce 100 MW/m2 to 1 GW/m2 of plasma heat flux (a typical heat flux level in a major fusion device) in ~ 100 mus (≤ 0.1 MJ/m2) for a liquid lithium plasma facing component research. The existing theta pinch device, DEVeX, was built and operated for study on lithium vapor shielding effect. However, a typical plasma energy of 3 - 4 kJ/m2 is too low to study an interaction of plasma and plasma facing components in fusion devices. No or little preionized plasma, ringing of magnetic field, collisions of high energy particles with background gas have been reported as the main issues. Therefore, DEVeX is reconfigured to mitigate these issues. The new device is mainly composed of a plasma gun for a preionization source, a theta pinch for heating, and guiding magnets for a better plasma transportation. Each component will be driven by capacitor banks and controlled by high voltage / current switches. Several diagnostics including triple Langmuir probe, calorimeter, optical emission measurement, Rogowski coil, flux loop, and fast ionization gauge are used to characterize the new device. A coaxial plasma gun is manufactured and installed in the previous theta pinch chamber. The plasma gun is equipped with 500 uF capacitor and a gas puff valve. The increase of the plasma velocity with the plasma gun capacitor voltage is consistent with the theoretical predictions and the velocity is located between the snowplow model and the weak - coupling limit. Plasma energies measured with the calorimeter ranges from 0.02 - 0.065 MJ/m2 and increases with the voltage at the capacitor bank. A cross-check between the plasma energy measured with the calorimeter and the triple probe

  4. Experiments on phase transitions in three-dimensional dusty plasma under microgravity conditions

    Science.gov (United States)

    Molotkov, V. I.; Naumkin, V. N.; Lipaev, A. M.; Zhukhovitskii, D. I.; Usachev, A. D.; Fortov, V. E.; Thomas, H. M.

    2017-11-01

    Complex (dusty) plasmas are composed of weakly ionized gas and charged microparticles and represent the plasma state of soft matter. Due to the “heavy” component, microparticles, and the low density of the surrounding medium, the rarefied gas and plasma, it is necessary to perform experiments under microgravity conditions to cover a broad range of experimental parameters which are not available on ground. The investigations have been performed onboard the International Space Station (ISS) with the help of the PK-3 Plus laboratory. This laboratory was mainly built to investigate the crystalline state of complex plasma, the so-called plasma crystal, its phase transitions and processes in multi-particle mixtures. The crystal–liquid phase transition was obtained in large three-dimensional isotropic dusty plasma system. Observations of a transition of the dusty plasma system state due to the particle charge reduction and due to variations of the plasma component density are presented.

  5. AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

    CERN Document Server

    Gschwendtner, E.; Amorim, L.; Apsimon, R.; Assmann, R.; Bachmann, A.M.; Batsch, F.; Bauche, J.; Berglyd Olsen, V.K.; Bernardini, M.; Bingham, R.; Biskup, B.; Bohl, T.; Bracco, C.; Burrows, P.N.; Burt, G.; Buttenschon, B.; Butterworth, A.; Caldwell, A.; Cascella, M.; Chevallay, E.; Cipiccia, S.; Damerau, H.; Deacon, L.; Dirksen, P.; Doebert, S.; Dorda, U.; Farmer, J.; Fedosseev, V.; Feldbaumer, E.; Fiorito, R.; Fonseca, R.; Friebel, F.; Gorn, A.A.; Grulke, O.; Hansen, J.; Hessler, C.; Hofle, W.; Holloway, J.; Huther, M.; Jaroszynski, D.; Jensen, L.; Jolly, S.; Joulaei, A.; Kasim, M.; Keeble, F.; Li, Y.; Liu, S.; Lopes, N.; Lotov, K.V.; Mandry, S.; Martorelli, R.; Martyanov, M.; Mazzoni, S.; Mete, O.; Minakov, V.A.; Mitchell, J.; Moody, J.; Muggli, P.; Najmudin, Z.; Norreys, P.; Oz, E.; Pardons, A.; Pepitone, K.; Petrenko, A.; Plyushchev, G.; Pukhov, A.; Rieger, K.; Ruhl, H.; Salveter, F.; Savard, N.; Schmidt, J.; Seryi, A.; Shaposhnikova, E.; Sheng, Z.M.; Sherwood, P.; Silva, L.; Soby, L.; Sosedkin, A.P.; Spitsyn, R.I.; Trines, R.; Tuev, P.V.; Turner, M.; Verzilov, V.; Vieira, J.; Vincke, H.; Wei, Y.; Welsch, C.P.; Wing, M.; Xia, G.; Zhang, H.

    2016-01-01

    The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment at CERN and the world's first proton driven plasma wakefield acceleration experiment. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV/c proton beam bunches from the SPS. The first experiments will focus on the self-modulation instability of the long (rms ~12 cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy (~15 MeV) electrons will be externally injected to sample the wakefields and be accelerated beyond 1 GeV. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented.

  6. AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

    Energy Technology Data Exchange (ETDEWEB)

    Gschwendtner, E. [CERN, Geneva (Switzerland); Adli, E. [University of Oslo, Oslo 0316 (Norway); Amorim, L. [GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisbon (Portugal); Apsimon, R. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Lancaster University, Lancaster LA1 4YR (United Kingdom); Assmann, R. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Bachmann, A.-M.; Batsch, F. [Max Planck Institute for Physics, Föhringer Ring 6, München 80805 (Germany); Bauche, J. [CERN, Geneva (Switzerland); Berglyd Olsen, V.K. [University of Oslo, Oslo 0316 (Norway); Bernardini, M. [CERN, Geneva (Switzerland); Bingham, R. [STFC Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Biskup, B. [CERN, Geneva (Switzerland); Czech Technical University, Zikova 1903/4, 166 36 Praha 6 (Czech Republic); Bohl, T.; Bracco, C. [CERN, Geneva (Switzerland); Burrows, P.N. [John Adams Institute for Accelerator Science, Oxford (United Kingdom); University of Oxford, Oxford OX1 2JD (United Kingdom); Burt, G. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Buttenschön, B. [Max Planck Institute for Plasma Physics, Wendelsteinstr. 1, Greifswald 17491 (Germany); Butterworth, A. [CERN, Geneva (Switzerland); Caldwell, A. [Max Planck Institute for Physics, Föhringer Ring 6, München 80805 (Germany); Cascella, M. [UCL, Gower Street, London WC1E 6BT (United Kingdom); and others

    2016-09-01

    The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment at CERN and the world's first proton driven plasma wakefield acceleration experiment. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV/c proton beam bunches from the SPS. The first experiments will focus on the self-modulation instability of the long (rms ~12 cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy (~15 MeV) electrons will be externally injected into the sample wakefields and be accelerated beyond 1 GeV. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented.

  7. Numerical optimization of a plasma wakefield acceleration experiment

    Directory of Open Access Journals (Sweden)

    K. V. Lotov

    2007-05-01

    Full Text Available One possible way to demonstrate both the efficiency and beam quality in a plasma wakefield accelerator is to prepare matched drive and accelerated beams by removing a central slice from a single high-quality electron bunch (parent beam. For parameters of the parent beam given, the question arises how to maximize the number and energy of accelerated particles and minimize their energy spread and emittance. This question is addressed by numerical simulations. The optimum shape of the beams, required plasma length, achievable energy gain, and energy spread are found as functions of the plasma density and parent beam characteristics. The required control accuracy of adjustable beam and plasma parameters is determined.

  8. Waves In Space Plasmas (WISP): A space plasma lab active experiment

    Science.gov (United States)

    Fredricks, R. W.

    1983-01-01

    The Waves in Space Plasmas (WISP) series of Spacelab Space Plasma Labs devoted to active experimentation, are introduced. Space Plasma Lab-1 is keyed to active probing of the ionosphere and magnetosphere using controlled wave injections by the WISP VLF and HF transmitters, supported by a free-flying plasma diagnostics package instrumented with wave receivers and particle probe diagnostics, designed to measure radiation and propagation of plasma waves, precipitated particle fluxes due to wave/particle interactions, and similar phenomena resulting from wave injectons. The VLF transmitter delivers up to 1 kW of RF power into the antenna terminals over the range from 0.3 to 30 kHz. The HF transmitter delivers up to 500 W to the antenna over the range from 1 to 30 MHz. A dipole antenna commandable to any extension up to 300 m tip-to-tip is available.

  9. Plasma action on helium flow in cold atmospheric pressure plasma jet experiments

    Science.gov (United States)

    Darny, T.; Pouvesle, J.-M.; Fontane, J.; Joly, L.; Dozias, S.; Robert, E.

    2017-10-01

    In this work, helium flow modifications, visualized by schlieren imaging, induced by the plasma generated in a plasma jet have been studied in conditions used for biomedical treatments (jet being directed downwards with a low helium flow rate). It has been shown that the plasma action can shift up to few centimeters downstream the effects of buoyancy, which allows to the helium flow to reach a target below in conditions for which it is not the case when the plasma is off. This study reveals the critical role of large and long lifetime negative ions during repetitive operations in the kHz regime, inducing strong modifications in the gas propagation. The cumulative added streamwise momentum transferred to ambient air surrounding molecules resulting from a series of applied voltage pulses induces a gradual built up of a helium channel on tens of millisecond timescale. In some conditions, a remarkable stable cylindrical helium channel can be generated to the target with plasma supplied by negative polarity voltage pulses whereas a disturbed flow results from positive polarity operation. This has a direct effect on air penetration in the helium channel and then on the reactive species production over the target which is of great importance for biomedical applications. It has also been shown that with an appropriate combination of negative and positive polarity pulses, it is possible to benefit from both polarity features in order to optimize the plasma plume propagation and plasma delivery to a target.

  10. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Green, David L [ORNL; Jaeger, E. F. [XCEL; Berry, Lee A [ORNL; Chen, Guangye [ORNL; Ryan, Philip Michael [ORNL; Canik, John [ORNL

    2011-01-01

    Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.

  11. Commercialization of Plasma-Assisted Technologies: The Indian Experience

    Science.gov (United States)

    John, P. I.

    The paper describes an initiative by the Institute for Plasma Research (IPR), India in establishing links with the Indian industry for developing and commercialising advanced plasma-based industrial technologies. This has culminated in the creation of a self-financing technology development, incubation, demonstration and delivery facility. A business plan for converting the knowledge base to commercially viable technologies conceived technology as a product and the industry as the market and addressed issues like resistance to new technologies, the key role of entrepreneur, thrust areas and the necessity of technology incubation and delivery. Success of this strategy is discussed in a few case studies. We conclude by identifying the cost, environmental, strategic and techno-economic aspects, which would be the prime drivers for plasma-assisted manufacturing technology in India.

  12. Dusty Plasma Experimental (DPEx) device for complex plasma experiments with flow

    CERN Document Server

    Jaiswal, S; Sen, A

    2015-01-01

    A versatile table-top dusty plasma experimental device (DPEx) to study flow induced excitations of linear and nonlinear waves/structures in a complex plasma is presented. In this $\\Pi$-shaped apparatus a DC glow discharge plasma is produced between a disc shaped anode and a grounded long cathode tray by applying a high voltage DC in the background of a neutral gas and subsequently a dusty plasma is created by introducing micron sized dust particles that get charged and levitated in the sheath region. A flow of the dust particles is induced in a controlled manner by adjusting the pumping speed and the gas flow rate into the device. A full characterisation of the plasma, using Langmuir and emissive probe data, and that of the dusty plasma using particle tracking data with the help of an idl based (super) Particle Identification and Tracking (sPIT) code is reported. Experimental results on the variation of the dust flow velocity as a function of the neutral pressure and the gas flow rate are given. The potential...

  13. A pinhole camera for ultrahigh-intensity laser plasma experiments

    Science.gov (United States)

    Wang, C.; An, H. H.; Xiong, J.; Fang, Z. H.; Wang, Y. W.; Zhang, Z.; Hua, N.; Sun, J. R.; Wang, W.

    2017-11-01

    A pinhole camera is an important instrument for the detection of radiation in laser plasmas. It can monitor the laser focus directly and assist in the analysis of the experimental data. However, conventional pinhole cameras are difficult to use when the target is irradiated by an ultrahigh-power laser because of the high background of hard X-ray emission generated in the laser/target region. Therefore, an improved pinhole camera has been developed that uses a grazing-incidence mirror that enables soft X-ray imaging while avoiding the effect of hard X-ray from hot dense plasmas.

  14. Influence of proton bunch and plasma parameters on the AWAKE experiment

    Science.gov (United States)

    Moreira, Mariana; Vieira, Jorge; Muggli, Patric

    2017-10-01

    The Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN will test the concept underlying plasma wakefield acceleration using long proton beams that undergo the self-modulation instability. The effectiveness of the experiment hinges on the successful and predictable development of this instability, which fragments the initial proton bunch into smaller beamlets with lengths of the order of the plasma wavelength. Since the initial parameters of the experiment inevitably vary from event to event, this work will aim to understand the correlation between these variations and the resulting wakefield. Using both theoretical models and numerical particle-in-cell simulations, the influence of variations in initial bunch charge, bunch dimensions, bunch energy and plasma density profile on the excited accelerating gradients and on the final energies reached by the witness particles will be investigated. In addition, further options in the experiment setup will be explored with the aim of optimizing the results.

  15. Early results of microwave transmission experiments through an overly dense rectangular plasma sheet with microparticle injection

    Science.gov (United States)

    Gillman, Eric D.; Amatucci, W. E.

    2014-06-01

    These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.

  16. Experiment on the formation of boron nitride in the jet of low-temperature plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pollo, I. (Politechnika Lubelska (Poland)); Aniol, S. (Politechnika Slaska, Gliwice (Poland). Katedra Chemii i Technologii Nieorganicznej)

    1981-01-01

    The paper deals with the experiments on the formation of boron nitride in the jet of nitric-argon plasma into which solid boron trioxide as well as gaseous ammonia were introduced. It was found out that the conversion process of B/sub 2/O/sub 3/ into nitride in the jet of low-temperature plasma affected by gaseous NH/sub 3/ is possible and in the conditions of our experiment did not exceed 20 per cent.

  17. Ion beam experiments for the study of plasma-surface interactions

    Science.gov (United States)

    Karahashi, Kazuhiro; Hamaguchi, Satoshi

    2014-06-01

    Experimental studies based on mass-selected ion beams are reviewed as a means to examine plasma-surface interactions for industrial plasma processing. Plasma etching and deposition processes widely used in the microelectronics industry exploit surface chemical reactions induced by plasmas. Such reactions typically result from a conglomeration of complex interactions of the surface material with incident free radicals and ions. While it is in general difficult to analyse individual surface reactions separately in a plasma system, ion and/or charge-neutral beam experiments allow one to analyse specific surface reactions involving only selected gaseous species. In this review, experiments on beam-surface interactions are discussed in detail and beam reaction data for silicon surfaces are presented as sample data.

  18. Power Balance Analysis of the Prototype-Material Plasma Exposure eXperiment

    Science.gov (United States)

    Showers, M. A.; Biewer, T. M.; Caneses, J. F.; Caughman, J. B. O.; Lumsdaine, A.; Owen, L.; Rapp, J.; Youchison, D.; Beers, C. J.; Donovan, D. C.; Kafle, N.; Ray, H. B.

    2017-10-01

    The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) is a test bed for the plasma source concept for the planned Material Plasma Exposure eXperiment (MPEX), a steady-state linear device studying plasma material interactions for fusion reactors. A power balance of Proto-MPEX attempts to identify machine operating parameters that will improve Proto-MPEX's performance, potentially impacting the MPEX design concept. A power balance has been performed utilizing an extensive diagnostic suite to identify mechanisms and locations of power loss from the main plasma. The diagnostic package includes infrared cameras, double Langmuir probes, fluoroptic probes, Mach probes, a Thomson scattering diagnostic, a McPherson spectrometer and in-vessel thermocouples. Radiation losses are estimated with absolute calibrated spectroscopic signals. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

  19. Plasma edge cross-field transport: experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Benjamin A. [Oak Ridge National Laboratory, P.O. Box 2008, MS-6169, Oak Ridge, TN 37831-6169 (United States)]. E-mail: carrerasba@ornl.gov

    2005-03-01

    In recent years, the basic physics picture of plasma transport in the scrape-off layers of tokamaks and stellarators has changed. This basic picture was based on slow diffusive cross-field transport competing with fast parallel transport. However, the idea of a local diffusive cross-field transport picture is not compatible with some of the experimental findings. Cross-field particle fluxes have an intermittent character. Large transport events can be responsible for a large portion of the total integrated flux. Those measurements also show the existence of long-range correlations in time and space. These correlations break down a possible separation of scales that was the base in deriving the macroscopic transport models. Structures are not limited to density fluctuations; they also appear on edge flows. The interaction between fluctuations and flows becomes one of the most important issues in the plasma edge dynamics.

  20. Particle transport in tokamak plasmas, theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Angioni, C [Max-Planck Institut fuer Plasmaphysik, IPP-EURATOM Association, D-85748 Garching (Germany); Fable, E; Maslov, M; Weisen, H [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Greenwald, M [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA (United States); Peeters, A G [Centre for Fusion, Space and Astrophysics, University of Warwick, CV4 7AL, Coventry (United Kingdom); Takenaga, H [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka, Ibaraki 311-0193 (Japan)

    2009-12-15

    The physical processes producing electron particle transport in the core of tokamak plasmas are described. Starting from the gyrokinetic equation, a simple analytical derivation is used as guidance to illustrate the main mechanisms driving turbulent particle convection. A review of the experimental observations on particle transport in tokamaks is presented and the consistency with the theoretical predictions is discussed. An overall qualitative agreement, and in some cases even a specific quantitative agreement, emerges between complex theoretical predictions and equally complex experimental observations, exhibiting different dependences on plasma parameters under different regimes. By these results, the direct connection between macroscopic transport properties and the character of microscopic turbulence is pointed out, and an important confirmation of the paradigm of microinstabilities and turbulence as the main cause of transport in the core of tokamaks is obtained. Finally, the impact of these results on the prediction of the peaking of the electron density profile in a fusion reactor is illustrated.

  1. Characterizing Hypervelocity Impact Plasma Through Experiments and Simulations

    Science.gov (United States)

    Close, Sigrid; Lee, Nicolas; Fletcher, Alex; Nuttall, Andrew; Hew, Monica; Tarantino, Paul

    2017-10-01

    Hypervelocity micro particles, including meteoroids and space debris with masses computational fluid dynamics (CFD) simulations that allow us to extend to regimes not currently possible with ground-based technology. We show that significant impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (>20 km/s) impacts that produced a fully ionized plasma.

  2. CO2 Laser Beat-Wave Experiment in an Unmagnetized Plasma

    Science.gov (United States)

    Liu, Fei; Hwang, David; Horton, Robert; Hong, Sean; Evans, Russell

    2012-10-01

    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics and fusion energy research. It is even more advantageous if the wave penetration is independent of the electron acceleration process. Plasma current can be generated through beat-wave mixing process by launching two intense electromagnetic waves (φ>>φpe) into plasma. The beat wave formation process can be efficient if the difference frequency of the two pump waves is matched to a local resonant frequency of the medium, i.e. in this case the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in a low-density plasma using microwaves.footnotetextRogers, J. H. and Hwang, D. Q., Phys. Rev. Lett. v68 p3877 (1992). The CO2 lasers provide the high tunability for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. Two sections of Lumonics TEA CO2 lasers have been modified to serve as the two pump wave sources with peak power over 100MW. The development of the tunable CO2 lasers, a high-density plasma target source and diagnostics system will be presented. The initial results of unbalanced beat-wave experiment using one high-power pulsed and one low-power CW CO2 lasers will be presented and discussed using the independent plasma source to control the φpe of the interaction region. This work is supported by U.S. DOE under Contract No. DE-FG02-10ER55083.

  3. Pre-conceptual design activities for the materials plasma exposure experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lumsdaine, Arnold, E-mail: lumsdainea@ornl.gov; Rapp, Juergen; Varma, Venugopal; Bjorholm, Thomas; Bradley, Craig; Caughman, John; Duckworth, Robert; Goulding, Richard; Graves, Van; Giuliano, Dominic; Lessard, Timothy; McGinnis, Dean; Meitner, Steven

    2016-11-01

    Highlights: • The development of long-pulse nuclear fusion devices requires testing plasma facing components at reactor relevant conditions. • The pre-conceptual design of a proposed linear plasma facility is presented. • Engineering considerations for multiple systems—plasma source and heating, magnet, vacuum, water cooling, and target, are presented. - Abstract: The development of next step fusion facilities such as DEMO or a Fusion Nuclear Science Facility (FNSF) requires first closing technology gaps in some critical areas. Understanding the material-plasma interface is necessary to enable the development of divertors for long-pulse plasma facilities. A pre-conceptual design for a proposed steady-state linear plasma device, the Materials Plasma Exposure Experiment (MPEX), is underway. A helicon plasma source along with ion cyclotron and electron Bernstein wave heating systems will produce ITER divertor relevant plasma conditions with steady-state parallel heat fluxes of up to 40 MW/m{sup 2} with ion fluxes up to 10{sup 24}/m{sup 2} s on target. Current plans are for the device to use superconducting magnets to produce 1–2 T fields. As a steady-state device, active cooling will be required for components that interact with the plasma (targets, limiters, etc.), as well as for other plasma facing components (transport regions, vacuum tanks, diagnostic ports). Design concepts for the vacuum system, the cooling system, and the plasma heating systems have been completed. The device will include the capability for handling samples that have been neutron irradiated in order to consider the multivariate effects of neutrons, plasma, and high heat-flux on the microstructure of divertor candidate materials. A vacuum cask, which can be disconnected from the high field environment in order to perform in-vacuo diagnosis of the surface evolution is also planned for the facility.

  4. Effect of ELMs on rotation and momentum confinement in H-mode discharges in JET

    DEFF Research Database (Denmark)

    Versloot, T.W.; de Vries, P.C.; Giroud, C.

    2010-01-01

    The loss of plasma toroidal angular momentum and thermal energy by edge localized modes (ELMs) has been studied in JET. The analysis shows a consistently larger drop in momentum in comparison with the energy loss associated with the ELMs. This difference originates from the large reduction...... in angular frequency at the plasma edge, observed to penetrate into the plasma up to r/a ~ 0.65 during large type-I ELMs. As a result, the time averaged angular frequency is lowered near the top of the pedestal with increasing ELM frequency, resulting in a significant drop in thermal Mach number at the edge....... An increase in profile peaking of ion temperature and angular frequency is observed. At the same time the plasma confinement is reduced while the ratio of confinement times (Rτ = τE/τ) increases noticeably with ELM frequency. This change could be explained by the relatively larger ELM induced losses...

  5. Excitation of slow waves in front of an ICRF antenna in a basic plasma experiment

    Science.gov (United States)

    Soni, Kunal; van Compernolle, Bart; Crombe, Kristel; van Eester, Dirk

    2017-10-01

    Recent results of ICRF experiments at the Large Plasma Device (LAPD) indicate parasitic coupling to the slow wave by the fast wave antenna. Plasma parameters in LAPD are similar to the scrape-off layer of current fusion devices. The machine has a 17 m long, 60 cm diameter magnetized plasma column with typical plasma parameters ne 1012 -1013 cm-3, Te 1 - 10 eV and B0 1000 G. It was found that coupling to the slow mode occurs when the plasma density in front of the antenna is low enough such that the lower hybrid resonance is present in the plasma. The radial density profile is tailored to allow for fast mode propagation in the high density core and slow mode propagation in the low density edge region. Measurements of the wave fields clearly show two distinct modes, one long wavelength m=1 fast wave mode in the core and a short wavelength backward propagating mode in the edge. Perpendicular wave numbers compare favorably to the predicted values. The experiment was done for varying frequencies, ω /Ωi = 25 , 6 and 1.5. Future experiments will investigate the dependence on antenna tilt angle with respect to the magnetic field, with and without Faraday screen. This work is performed at the Basic Plasma Science Facility, sponsored jointly by DOE and NSF.

  6. PKE-Nefedov: plasma crystal experiments on the International Space Station

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, Anatoli P [Institute for High Energy Densities, Russian Academy of Sciences, 127412 Moscow (Russian Federation); Morfill, Gregor E [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Fortov, Vladimir E [Institute for High Energy Densities, Russian Academy of Sciences, 127412 Moscow (Russian Federation); Thomas, Hubertus M [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Rothermel, Hermann [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Hagl, Tanja [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Ivlev, Alexei V [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Zuzic, Milenko [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Klumov, Boris A [Centre for Interdisciplinary Plasma Science, Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany); Lipaev, Andrey M [Institute for High Energy Densities, Russian Academy of Sciences, 127412 Moscow (Russian Federation); Molotkov, Vladimir I [Institute for High Energy Densities, Russian Academy of Sciences, 127412 Moscow (Russian Federation); Petrov, Oleg F [Institute for High Energy Densities, Russian Academy of Sciences, 127412 Moscow (Russian Federation); Gidzenko, Yuri P [Y Gagarin Cosmonauts Training Centre, 141160 Star City, Moscow Region (Russian Federation); Krikalev, Sergey K [SP Korolev RSC Energia, Korolev 141070, Moscow Region (Russian Federation); Shepherd, William [Expedition 1 Crew, International Space Station (ISS) (Country Unknown)] [and others

    2003-04-01

    The plasma crystal experiment PKE-Nefedov, the first basic science experiment on the International Space Station (ISS), was installed in February 2001 by the first permanent crew. It is designed for long-term investigations of complex plasmas under microgravity conditions. 'Complex plasmas' contain ions, electrons, neutrals and small solid particles - normally in the micrometre range. These microparticles obtain thousands of elementary charges and interact with each other via a 'screened' Coulomb potential. Complex plasmas are of special interest, because they can form liquid and crystalline states (Thomas et al 1994 Phys. Rev. Lett. 73 652-5, Chu and I 1994 Phys. Rev. Lett. 72 4009-12) and are observable at the kinetic level. In experiments on Earth the microparticles are usually suspended against gravity in strong electric fields. This creates asymmetries, stresses and pseudo-equilibrium states with sufficient free energy to readily become unstable. Under microgravity conditions the microparticles move into the bulk of the plasma (Morfill et al 1999 Phys. Rev. Lett. 83 1598), experiencing much weaker volume forces than on Earth. This allows investigations of the thermodynamics of strongly coupled plasma states under substantially stress-free conditions. In this first paper we report our results on plasma crystals, in particular the first experimental observations of bcc lattice structures.

  7. Laboratory Experiments on Propagating Plasma Bubbles into Vacuum, Vacuum Magnetic Field, and Background Plasmas

    Science.gov (United States)

    Lynn, Alan G.; Zhang, Yue; Gilmore, Mark; Hsu, Scott

    2014-10-01

    We discuss the dynamics of plasma ``bubbles'' as they propagate through a variety of background media. These bubbles are formed by a pulsed coaxial gun with an externally applied magnetic field. Bubble parameters are typically ne ~1020 m-3, Te ~ 5 - 10 eV, and Ti ~ 10 - 15 eV. The structure of the bubbles can range from unmagnetized jet-like structures to spheromak-like structures with complex magnetic flux surfaces. Some of the background media the bubbles interact with are vacuum, vacuum with magnetic field, and other magnetized plasmas. These bubbles exhibit different qualitative behavior depending on coaxial gun parameters such as gas species, gun current, and gun bias magnetic field. Their behavior also depends on the parameters of the background they propagate through. Multi-frame fast camera imaging and magnetic probe data are used to characterize the bubble evolution under various conditions.

  8. Instantaneous charge state of Uranium projectiles in fully ionized plasmas from energy loss experiments

    CERN Document Server

    Morales, Roberto; Casas, David

    2016-01-01

    The instantaneous charge state of uranium ions traveling through a fully ionized hydrogen plasma has been theoretically studied and compared with one of the first energy loss experiments in plasmas, carried out at GSI-Darmstadt by Hoffmann \\textit{et al.} in the 90's. For this purpose, two different methods to estimate the instantaneous charge state of the projectile have been employed: (1) rate equations using ionization and recombination cross sections, and (2) equilibrium charge state formulas for plasmas. Also, the equilibrium charge state has been obtained using these ionization and recombination cross sections, and compared with the former equilibrium formulas. The equilibrium charge state of projectiles in plasmas is not always reached, it depends mainly on the projectile velocity and the plasma density. Therefore, a non-equilibrium or an instantaneous description of the projectile charge is necessary. The charge state of projectile ions cannot be measured, except after exiting the target, and experime...

  9. Plasma-Jet-Driven Magneto-Inertial Fusion (PJMIF): Physics and Design for a Plasma Liner Formation Experiment

    Science.gov (United States)

    Hsu, Scott; Cassibry, Jason; Witherspoon, F. Douglas

    2014-10-01

    Spherically imploding plasma liners are a potential standoff compression driver for magneto-inertial fusion, which is a hybrid of and operates in an intermediate density between those of magnetic and inertial fusion. We propose to use an array of merging supersonic plasma jets to form a spherically imploding plasma liner. The jets are to be formed by pulsed coaxial guns with contoured electrodes that are placed sufficiently far from the location of target compression such that no hardware is repetitively destroyed. As such, the repetition rate can be higher (e.g., 1 Hz) and ultimately the power-plant economics can be more attractive than most other MIF approaches. During the R&D phase, a high experimental shot rate at reasonably low cost (e.g., gun plasma-liner-formation experiment, which will provide experimental data on: (i) scaling of peak liner ram pressure versus initial jet parameters, (ii) liner non-uniformity characterization and control, and (iii) control of liner profiles for eventual gain optimization.

  10. Recent Progress on the magnetic turbulence experiment at the Bryn Mawr Plasma Laboratory

    Science.gov (United States)

    Schaffner, D. A.; Cartagena-Sanchez, C. A.; Johnson, H. K.; Fahim, L. E.; Fiedler-Kawaguchi, C.; Douglas-Mann, E.

    2017-10-01

    Recent progress is reported on the construction, implementation and testing of the magnetic turbulence experiment at the Bryn Mawr Plasma Laboratory (BMPL). The experiment at the BMPL consists of an ( 300 μs) long coaxial plasma gun discharge that injects magnetic helicity into a flux-conserving chamber in a process akin to sustained slow-formation of spheromaks. A 24cm by 2m cylindrical chamber has been constructed with a high density axial port array to enable detailed simultaneous spatial measurements of magnetic and plasma fluctuations. Careful positioning of the magnetic structure produced by the three separately pulsed coils (one internal, two external) are preformed to optimize for continuous injection of turbulent magnetized plasma. High frequency calibration of magnetic probes is also underway using a power amplifier.

  11. Interaction of Fast Ions with Global Plasma Modes in the C-2 Field Reversed Configuration Experiment

    Science.gov (United States)

    Smirnov, Artem; Dettrick, Sean; Clary, Ryan; Korepanov, Sergey; Thompson, Matthew; Trask, Erik; Tuszewski, Michel

    2012-10-01

    A high-confinement operating regime [1] with plasma lifetimes significantly exceeding past empirical scaling laws was recently obtained by combining plasma gun edge biasing and tangential Neutral Beam Injection (NBI) in the C-2 field-reversed configuration (FRC) experiment [2, 3]. We present experimental and computational results on the interaction of fast ions with the n=2 rotational and n=1 wobble modes in the C-2 FRC. It is found that the n=2 mode is similar to quadrupole magnetic fields in its detrimental effect on the fast ion transport due to symmetry breaking. The plasma gun generates an inward radial electric field, thus stabilizing the n=2 rotational instability without applying the quadrupole magnetic fields. The resultant FRCs are nearly axisymmetric, which enables fast ion confinement. The NBI further suppresses the n=2 mode, improves the plasma confinement characteristics, and increases the plasma configuration lifetime [4]. The n=1 wobble mode has relatively little effect on the fast ion transport, likely due to the approximate axisymmetry about the displaced plasma column. [4pt] [1] M. Tuszewski et al., Phys. Rev. Lett. 108, 255008 (2012).[0pt] [2] M. Binderbauer et al., Phys. Rev. Lett. 105, 045003 (2010).[0pt] [3] H.Y. Guo et al., Phys. Plasmas 18, 056110 (2011).[0pt] [4] M. Tuszewski et al., Phys. Plasmas 19, 056108 (2012)

  12. Electrically driving large magnetic Reynolds number flows on the Madison plasma dynamo experiment

    Science.gov (United States)

    Weisberg, David; Wallace, John; Peterson, Ethan; Endrezzi, Douglass; Forest, Cary B.; Desangles, Victor

    2015-11-01

    Electrically-driven plasma flows, predicted to excite a large-scale dynamo instability, have been generated in the Madison plasma dynamo experiment (MPDX), at the Wisconsin Plasma Astrophysics Laboratory. Numerical simulations show that certain topologies of these simply-connected flows may be optimal for creating a plasma dynamo and predict critical thresholds as low as Rmcrit =μ0 σLV = 250 . MPDX plasmas are shown to exceed this critical Rm , generating large (L = 1 . 4 m), warm (Te > 10 eV), unmagnetized (MA > 1) plasmas where Rm torque in Helium plasmas. Detailed Mach probe measurements of plasma velocity for two flow topologies will be presented: edge-localized drive using the multi-cusp boundary field, and volumetric drive using an axial Helmholtz field. Radial velocity profiles show that edge-driven flow is established via ion viscosity but is limited by a volumetric neutral drag force (χ ~ 1 / (ντin)), and measurements of velocity shear compare favorably to Braginskii transport theory. Volumetric flow drive is shown to produce stronger velocity shear, and is characterized by the radial potential gradient as determined by global charge balance.

  13. Experiments on penetration of a plasma with magnetized electrons across a magnetic field

    Science.gov (United States)

    Cid, R. E.; Cohen, R. H.; Hooper, E. B.; Molvik, A. W.; Porter, G. D.; Ryutov, D. D.

    1998-11-01

    In a number of situations of practical interest, one has to deal with plasma flow past bodies whose size is much greater than the electron gyroradius but much smaller than the ion gyroradius (examples from two very different environments are: spaceraft in the geomagnetic field, and irregularities on the surface of divertor plates). The ions are then repelled from the region inaccessible for electrons by the ambipolar potential, and a shadow with a size much less than the ion gyro-radius is formed. We present a systematic experimental study of plasma penetration into such shadows across the magnetic field lines. The experiments are performed on the Bluebell device situated at LLNL. The flow of an Argon plasma with density up to 10^12 cm-3 and electron temperature 2-3 eV is collimated by holes with diameters from 0.5 to 2 cm made in a thin aluminum disk that intersepts the rest of the plasma. The magnetic field strength is in the range of a few tens of gauss. The plasma density distribution in the gradually expanding plasma jets behind the holes is measured by electrostatic probes. In order to eliminate direct electric contact with the upstream plasma (which is sometimes quite "noisy"), some of the holes are covered with fine metal meshes. We report on the measurements of the cross-field expansion rate of the jets vs. the plasma density, the density of the background gas, and the magnetic field intensity.

  14. Properties of the Circumsolar Plasma Turbulence and Plasma Waves According to the Coronal Sounding Experiments Using Spacecraft Signals

    Science.gov (United States)

    Yakovlev, O. I.

    2017-10-01

    We report on the results of studying the circumsolar plasma turbulence according to the coronal sounding experiments using spacecraft signals. Statistical characteristics of the temporal fluctuation spectra of the amplitude, phase, frequency, and Faraday rotation angle of the radio-wave polarization plane are described for the solar offset distances of the ray path in the range between 3 and 40 solar radii. Information on the turbulence spectra is given and the spectral index, as well as the outer and inner turbulence scales, as functions of the heliocentric distance are presented. The effect on the measured parameters of the plasma waves is discussed and typical values of the wave periods for different distances from the Sun are given.

  15. On L to H-mode transitions of the tokamak and entropy reduction

    Directory of Open Access Journals (Sweden)

    Rastović Danilo

    2006-01-01

    Full Text Available In an ideal case, it is assumed that the models for tokamak and stellarator plasma behaviour lead to the theory of invariant manifolds by Rastović [Chaos, Solitons & Fractals, 2007]. But, at the present state of knowledge a more realistic concept for describing L to H transitions and edge localized modes is the reduction of entropy and appropriate methods.

  16. Clinical experiences with extracorporeal immunoperfusion of plasma from cancer patients.

    Science.gov (United States)

    Korec, S; Smith, F P; Schein, P S; Phillips, T M

    1984-01-01

    We have treated 11 patients having a variety of tumor types and three patients having mitomycin-C-associated thrombotic thrombocytopenic purpura (TTP) with extracorporeal plasma perfusion through filters containing immobilized protein A from Staphylococcus aureus. In performing more than 140 procedures we observed only minimal toxicity, of which fever, chills, nausea, and vomiting were the most common symptoms, occurring in 25% of the patients. Significant decrease in blood pressure and bronchospasm were rare complications. However, none of these side effects were severe enough to require therapeutic intervention. The antitumor effect of immunoperfusion was modest. In 10 adequately treated patients there was one measurable tumor reduction (40% decrease of original tumor mass). Two patients had correction of total small bowel obstruction, with return to normal food intake and restoration of normal bowel habits, lasting for 6 and 3 months; and two of the two adequately treated TTP patients had dramatic hematological improvement after four and five immunoperfusion treatments and are well at present. We found direct correlation between extent of complement activation and clinical toxicity. By temperature manipulation of the perfusion procedure we were able to control the above-mentioned side effects caused by complement activation.

  17. Comparisons of small ELM H-Mode regimes on the Alcator C-Mod and JFT-2M tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, A E [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Kamiya, K [Japan Atomic Energy Agency, Naka-city, Ibaraki 311-0193 (Japan); Oyama, N [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Basse, N [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Biewer, T [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Edlund, E [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Hughes, J W [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Lin, L [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Porkolab, M [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Rowan, W [Fusion Research Center, University of Texas at Austin, TX (United States); Snipes, J [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Terry, J [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States); Wolfe, S M [MIT Plasma Science and Fusion Center, Cambridge MA, 02139 (United States)

    2006-05-15

    Comparisons of H-mode regimes were carried out on the Alcator C-Mod and JFT-2M tokamaks. Shapes were matched apart from aspect ratio, which is lower on C-Mod. The high recycling steady H-mode on JFT-2M and enhanced D-alpha (EDA) regime on C-Mod, both of which feature very small or no ELMs, are found to have similar access conditions in q{sub 95} - {nu}* space, occurring for pedestal collisionality {nu}* > 1. Differences in edge fluctuations were found, with lower frequencies but higher mode numbers on C-Mod. In both tokamaks an attractive regime with small ELMs on top of an enhanced D{sub {alpha}} baseline was obtained at moderate {nu}* and higher pressure. The JFT-2M shape favoured the appearance of ELMs on C-Mod and also resulted in the appearance of a lower frequency component of the quasicoherent mode during EDA.

  18. The AMY experiment: Microwave emission from air shower plasmas

    Directory of Open Access Journals (Sweden)

    Alvarez-Muñiz J.

    2016-01-01

    Full Text Available You The Air Microwave Yield (AMY experiment investigate the molecular bremsstrahlung radiation emitted in the GHz frequency range from an electron beam induced air-shower. The measurements have been performed at the Beam Test Facility (BTF of Frascati INFN National Laboratories with a 510 MeV electron beam in a wide frequency range between 1 and 20 GHz. We present the apparatus and the results of the tests performed.

  19. Vacuum UV spectroscopy of armor erosion from plasma gun disruption simulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Rockett, P.D. [Sandia Nat. Labs., Albuquerque, NM (United States). Fusion Tech. Dept.; Hunter, J.A. [Sandia Nat. Labs., Albuquerque, NM (United States). Fusion Tech. Dept.; Bradley, J.T. III [Electrical Engineering and Computer Engineering Department, University of New Mexico, Albuquerque, NM 87131 (United States); Gahl, J.M. [Electrical Engineering and Computer Engineering Department, University of New Mexico, Albuquerque, NM 87131 (United States); Zhitlukhin, A. [Troitsk Institute for Innovation and Technology (TRINITI), Troitsk, Moscow Region (Russian Federation); Arkhipov, K. [Troitsk Institute for Innovation and Technology (TRINITI), Troitsk, Moscow Region (Russian Federation); Bakhtin, V. [Troitsk Institute for Innovation and Technology (TRINITI), Troitsk, Moscow Region (Russian Federation); Toporkov, D. [Troitsk Institute for Innovation and Technology (TRINITI), Troitsk, Moscow Region (Russian Federation); Ovchinnokov, I. [Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation); Kuznetsov, V.E. [Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation); Titov, V.A. [Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation)

    1995-03-01

    Extensive simulations of tokamak disruptions have provided a picture of material erosion that is limited by the transfer of energy from the incident plasma to the armor solid surface through a dense vapor shield. Two transmission grating vacuum ultraviolet (VUV) spectrographs were designed and utilized to study the plasma-material interface in plasma gun simulation experiments. Target materials included POCO graphite, ATJ graphite, boron nitride and plasma-sprayed tungsten. Detailed spectra were recorded with a spatial resolution of ca. 0.7mm resolution on VIKA at Efremov and on 2MK-200 at Troitsk. Time-resolved data with 40-200ns resolution were then recorded along with the same spatial resolution on 2MK-200. The VIKA plasma gun directly illuminated a target with a high-intensity plasma pulse of 2-100MJm{sup -2} with low-energy ions of ca. 100eV. The 2MK-200 plasma gun illuminated the target via a magnetic cusp that permitted only deuterium to pass with energies of ca. 1keV, but which produced a fairly low intensity of 2MJm{sup -2}. Power densities on target ranged from 10{sup 7} to 10{sup 8}Wcm{sup -2}. Emitted spectra were recorded from 15 to 450A over a distance from 0 to 7cm above the armor target surface. The data from both plasma gun facilities demonstrated that the hottest plasma region was sitting several millimeters above the armor tile surface. This apparently constituted the absorption region, which confirmed past computer simulations. Spectra indicated both the species and ionization level that were being ablated from the target, demonstrating impurity content, and showing plasma ablation velocity. Graphite samples clearly showed CV lines as well as impurity lines from O V and O VI. The BN tiles produced textbook examples of BIV and BV, and extensive NIV, V and VI lines. These are being compared with radiation-hydrodynamic calculations. (orig.).

  20. Modulating toroidal flow stabilization of edge localized modes with plasma density

    CERN Document Server

    Cheng, Shikui; Banerjee, Debabrata

    2016-01-01

    Recent EAST experiments have demonstrated mitigation and suppression of edge localized modes (ELMs) with toroidal rotation flow in higher collisionality regime, suggesting potential roles of plasma density. In this work, the effects of plasma density on the toroidal flow stabilization of the high-$n$ edge localized modes have been extensively studied in linear calculations for a circular-shaped limiter H-mode tokamak, using the extended MHD code NIMROD. In the single MHD model, toroidal flow has a weak stabilizing effects on the high-$n$ modes. Such a stabilization, however, can be significantly enhanced with the increase in plasma density. Furthermore, our calculations show that the enhanced stabilization of high-$n$ modes from toroidal flow with higher edge plasma density persists in the 2-fluid MHD model. These findings may explain the ELM mitigation and suppression by toroidal rotation in higher collisionality regime due to the enhancement of plasma density obtained in recent EAST experiments.

  1. Design of a laboratory platform for atmospheric pressure biomedical plasma experiments

    Science.gov (United States)

    Lee, Sarah; Rutz, Sara; Hicks, Nathaniel; Briggs, Brandon

    2017-10-01

    The design of a laboratory set up for atmospheric pressure plasma (APP) experiments with biomedical applications is described. A comparison between various types of cold APP discharges (DC, RF, microwave) is presented, as well as various configurations of electrodes, dielectric materials, and gas feed conditions. Particular attention is paid to designs comprising floating electrode dielectric barrier discharges (FE-DBD) (for example as described in), but atmospheric pressure plasma jets are considered as well. A plan is discussed for initial experiments on the response of bacterial populations of E. coli and Deinococcus radiodurans to APP treatment as well as to media activated by APP. Supported by 2017 University of Alaska Anchorage Innovate Award.

  2. Simulations of Boundary Turbulence in Tokamak Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Nevins, W M; Xu, X Q; Carlstrom, T N; Cohen, R H; Groebner, R; Jennings, T; LaBombard, B; Maqueda, R A; Mazurenko, A; McKee, G R; Moyer, R; Mossessian, D; Porkolab, M; Porter, G D; Rensink, M E; Rhodes, T L; Rognlien, T D; Rost, C; Snipes, J; Stotler, D P; Terry, J; Zweben, S

    2002-10-11

    Comparisons between the boundary plasma turbulence observed in the BOUT code and experiments on C-Mod, NSTX, and DIII-D are presented. BOUT is a 3D non-local electromagnetic turbulence simulation code which models boundary-plasma turbulence in a realistic divertor geometry using the modified Braginskii equations for plasma vorticity, density, the electron and ion temperatures and parallel momenta. Many features of the Quasi-Coherent (QC) mode, observed at high densities during enhanced D-alpha (EDA) H-Mode in Alcator C-Mod, are reproduced in BOUT simulations. The spatial structure of boundary plasma turbulence as observed by gas puff imaging (GPI) from discharges on NSTX and C-Mod are in general (NSTX) to good (CMod) agreement with BOUT simulations. Finally, BOUT simulations of DIII-D L-mode experiments near the Hmode transition threshold are in broad agreement with the experimental results.

  3. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas.

    Science.gov (United States)

    Green, D L; Berry, L A; Chen, G; Ryan, P M; Canik, J M; Jaeger, E F

    2011-09-30

    Observations of improved radio frequency (rf) heating efficiency in ITER relevant high-confinement (H-)mode plasmas on the National Spherical Tokamak Experiment are investigated by whole-device linear simulation. The steady-state rf electric field is calculated for various antenna spectra and the results examined for characteristics that correlate with observations of improved or reduced rf heating efficiency. We find that launching toroidal wave numbers that give fast-wave propagation in the scrape-off plasma excites large amplitude (∼kV m(-1)) coaxial standing modes between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggests that these modes are a probable cause of degraded heating efficiency.

  4. Results from an 8 Joule RMF-FRC Plasma Translation Experiment for Space Propulsion

    Science.gov (United States)

    Hill, Carrie; Uchizono, Nolan; Holmes, Michael

    2017-10-01

    Field-Reversed Configuration (FRC) thrusters are attractive for advanced in-space propulsion technology as their projected performance, low specific mass, and propellant flexibility offer significant benefits over state-of-the art thrusters. A benchtop experiment to evaluate FRC thruster behavior using a Rotating Magnetic Field (RMF) formation method was constructed at the Air Force Research Laboratory. This experiment generated an RMF-FRC in a conical geometry and accelerated the plasma into a field-free drift region, using 8 J of input energy. Downstream plasma probes in a time-of-flight array measured the exhaust contents of the plasma plume. Results from this diagnostic demonstrated that the ejected mass and ion exit velocities fell short of the desired specific impulse and momentum. Two high-speed cameras were installed to diagnose the gross plasma behavior from two perspectives. Results from these images are presented here. These images show that the plasma generated in the formation region for several different operating conditions was highly non-uniform and did not form a stable closed-field topology that is expected from RMF-FRC plasmas.

  5. High power plasma heating experiments on the Proto-MPEX facility

    Science.gov (United States)

    Bigelow, T. S.; Beers, C. J.; Biewer, T. M.; Caneses, J. F.; Caughman, J. B. O.; Diem, S. J.; Goulding, R. H.; Green, D. L.; Kafle, N.; Rapp, J.; Showers, M. A.

    2017-10-01

    Work is underway to maximize the power delivered to the plasma that is available from heating sources installed on the Prototype Materials Plasma Exposure eXperiment (Proto-MPEX) at ORNL. Proto-MPEX is a linear device that has a >100 kW, 13.56 MHz helicon plasma generator available and is intended for material sample exposure to plasmas. Additional plasma heating systems include a 10 kW 18 GHz electron cyclotron heating (ECH) system, a 25 kW 8 MHz ion cyclotron heating ICH system, and a 200 kW 28 GHz electron Bernstein wave (EBW) and ECH system. Most of the heating systems have relatively good power transmission efficiency, however, the 28 GHz EBW system has a lower efficiency owing to stringent requirements on the microwave launch characteristics for EBW coupling combined with the lower output mode purity of the early-model gyrotron in use and its compact mode converter system. A goal for the Proto-MPEX is to have a combined heating power of 200 kW injected into the plasma. Infrared emission diagnostics of the target plate combined with Thomson Scattering, Langmuir probe, and energy analyzer measurements near the target are utilized to characterize the plasmas and coupling efficiency of the heating systems. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  6. Radio frequency heating induced edge plasma convection: self-consistent simulations and experiments on ASDEX Upgrade

    Science.gov (United States)

    Zhang, W.; Tierens, W.; Noterdaeme, J.-M.; Bobkov, V.; Aguiam, D.; Coster, D.; Fuenfgelder, H.; Jacquot, J.; Ochoukov, R.; Silva, A.; Colas, L.; Křivská, A.; the ASDEX Upgrade Team; the MST1 Team

    2017-11-01

    Plasma heating with waves in the ion cyclotron range of frequency (ICRF) affects the edge plasma and the edge plasma affects the ICRF heating. In simulations, these nonlinear ICRF—edge plasma interactions have been self-consistently simulated by running the EMC3-EIRENE, RAPLICASOL and SSWICH codes in an iterative way on ASDEX Upgrade for the first time. In experiments, the edge plasma convection induced by powered 3-strap antennas is measured with the antenna embedded reflectometers for the first time. Both the simulation and experimental results indicate that the ICRF induced convective cells are most significant on the top and bottom of the antennas; the edge plasma convection induced by 3-strap antennas in optimized antenna feeding configuration (dipole phasing, power ratio between the center and outer straps ~1.5) is smallest among the studied cases. The simulation results also suggest that compared to the 2-strap antennas, the 3-strap antennas can significantly reduce the plasma convection associated with the radio-frequency sheaths, even with unfavorable power balance between the straps in dipole phasing.

  7. Integrated Modeling of Short-Pulse Laser-Plasma Experiments

    Science.gov (United States)

    Town, R. P. J.; Welch, D. R.

    2005-10-01

    Modeling high energy density physics applications driven by short-pulse lasers requires the integration of many areas of physics that operate on disparate spatial and temporal scales. To perform such modeling in one integrated code would be computationally prohibitive, therefore we use the python scripting language to couple together independent hydrodynamics, explicit particle-in-cell (PIC) (Z3), implicit hybrid PIC (LSP), and atomic physics codes (FLYCHK) into one virtual code. This paper will briefly review the integration methodology and outline the new physics packages that have recently been added to LSP. We will contrast our simulation approach with those pursued by other researchers. We will present integrated simulation results of recent Petawatt Kα radiography, electron transport, and isochoric heating experiments and show predictions of a proof-of-principle NIF fast ignition experiment. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  8. Phenolic Acids from Wheat Show Different Absorption Profiles in Plasma: A Model Experiment with Catheterized Pigs

    DEFF Research Database (Denmark)

    Nørskov, Natalja; Hedemann, Mette Skou; Theil, Peter Kappel

    2013-01-01

    , their concentrations in the plasma and the absorption profiles differed between cinnamic and benzoic acid derivatives. Cinnamic acids derivatives such as ferulic acid and caffeic acid had maximum plasma concentration of 82 ± 20 and 200 ± 7 nM, respectively, and their absorption profiles differed depending on the diet...... consumed. Benzoic acid derivatives showed low concentration in the plasma (acid, with a plasma concentration (4 ± 0.4 μM), much higher than the other plant phenolic acids, likely because it is an intermediate in the phenolic acid metabolism......The concentration and absorption of the nine phenolic acids of wheat were measured in a model experiment with catheterized pigs fed whole grain wheat and wheat aleurone diets. Six pigs in a repeated crossover design were fitted with catheters in the portal vein and mesenteric artery to study...

  9. Research progress and status of the Magnetized Dusty Plasma Experiment (MDPX)

    Science.gov (United States)

    Thomas, Edward; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene; MDPX Team

    2017-10-01

    The addition of a magnetic field has a profound influence on the properties of a complex/dusty plasma. The Magnetized Dusty Plasma Experiment (MDPX) device at Auburn University is a flexible, high magnetic field research instrument with a mission to serve as an open access, multi-user facility for the dusty plasma and basic plasma research communities. In the last year, the MDPX device has performed a broad range of experimental studies at magnetic fields B >= 3 T; these are conditions where the electron gyro-radius is comparable to the diameter of the microparticles and the ion gyro-radius is comparable to the spacing between the microparticles. A variety of emergent phenomena are observed including a new type of imposed spatial ordering, significantly modified particle charging, coupling between ion and microparticle/nanoparticle transport, and new regimes of nanoparticle behavior. This work is supported by the US Dept. of Energy (DE-SC0016330) and the NSF (PHY-1613087).

  10. Achievement of Sustained Net Plasma Heating in a Fusion Experiment with the Optometrist Algorithm.

    Science.gov (United States)

    Baltz, E A; Trask, E; Binderbauer, M; Dikovsky, M; Gota, H; Mendoza, R; Platt, J C; Riley, P F

    2017-07-25

    Many fields of basic and applied science require efficiently exploring complex systems with high dimensionality. An example of such a challenge is optimising the performance of plasma fusion experiments. The highly-nonlinear and temporally-varying interaction between the plasma, its environment and external controls presents a considerable complexity in these experiments. A further difficulty arises from the fact that there is no single objective metric that fully captures both plasma quality and equipment constraints. To efficiently optimise the system, we develop the Optometrist Algorithm, a stochastic perturbation method combined with human choice. Analogous to getting an eyeglass prescription, the Optometrist Algorithm confronts a human operator with two alternative experimental settings and associated outcomes. A human operator then chooses which experiment produces subjectively better results. This innovative technique led to the discovery of an unexpected record confinement regime with positive net heating power in a field-reversed configuration plasma, characterised by a >50% reduction in the energy loss rate and concomitant increase in ion temperature and total plasma energy.

  11. Active experiments in geospace plasmas with gigawatts of RF power at HAARP

    Science.gov (United States)

    Sheerin, James

    2016-07-01

    The ionosphere provides a relatively quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 - 10 MHz to the ionosphere with millisecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP's unique features have enabled the conduct of a number of nonlinear plasma experiments in the inter¬action region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and optics for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. Applications are made to the controlled study of fundamental nonlinear plasma processes of relevance to laboratory plasmas, ionospheric irregularities affecting spacecraft communication and navigation systems, artificial ionization mirrors, wave-particle interactions in the magnetosphere, active global magnetospheric experiments, and many more.

  12. Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

    Science.gov (United States)

    Najarian, Maya L.; Chinni, Rosemarie C.

    2013-01-01

    This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

  13. Using a plasma physics experiment to expand student understanding of the index of refraction

    Science.gov (United States)

    Wise, Joe; Gekelman, Walter; Baker, Robert; Pribyl, Patrick

    2010-02-01

    The Los Angeles Physics Alliance Group (LAPTAG) Plasma Lab has met regularly at UCLA for the past 9 years. High school students have been involved in the construction of probes, amplifiers, antennae, machine shop use, printed circuit construction, experimental design, and scientific programming for the analysis of data. We describe a unique opportunity for high school students to participate in the process of science. Using plasma physics as an educational ``hook,'' students are engaged through a series of experiments, lectures, presentations, and group discussions. The outcome is that students gain a deeper understanding of the scientific method and in this case, the concepts of index of refraction and its effects on wave propagation. For example, students comprehend such advanced topics as dispersion, k-space, plasma properties, and wave group and phase velocities. This engagement supports efforts to improve STEM career choices by exposing high school students to challenging and interesting experiences in preparation for advanced study. )

  14. Comparative Analysis of Experiment Treating Benzene and CEES by Pulse Corona Plasma

    Science.gov (United States)

    Yan, Xuefeng; Hu, Zhen

    2005-08-01

    Based on an experiment treating benzene and 2-chloroethyl ethyl sulfide (CEES) by pulse corona induced-plasma, the similarities and differences found in the experimental data and analytical results are analyzed in a comparative manner in this paper. The theory applied is also discussed.

  15. Empirical modeling of plasma clouds produced by the Metal Oxide Space Clouds experiment

    Science.gov (United States)

    Pedersen, Todd R.; Caton, Ronald G.; Miller, Daniel; Holmes, Jeffrey M.; Groves, Keith M.; Sutton, Eric

    2017-05-01

    The Advanced Research Project Agency (ARPA) Long-Range Tracking And Instrumentation Radar (ALTAIR) radar at Kwajalein Atoll was used in incoherent scatter mode to measure plasma densities within two artificial clouds created by the Air Force Research Laboratory (AFRL) Metal Oxide Space Clouds (MOSC) experiment in May 2013. Optical imager, ionosonde, and ALTAIR measurements were combined to create 3-D empirical descriptions of the plasma clouds as a function of time, which match the radar measurements to within 15%. The plasma clouds closely track the location of the optical clouds, and the best fit plasma cloud widths are generally consistent with isotropic neutral diffusion. Cloud plasma densities decreased as a power of time, with exponents between -0.5 and -1.0, or much more slowly than the -1.5 predicted by diffusion. These exponents and estimates of total ion number from integration through the model volume are consistent with a scenario of slow ionization and a gradually increasing total number of ions with time, reaching a net ionization fraction of 20% after approximately half an hour. These robust representations of the plasma density are being used to study impacts of the artificial clouds on the dynamics of the background ionosphere and on RF propagation.

  16. Analysis of data from z-pinch MTF target plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wysocki, F.J.; Taccetti, J.M.; Benage, J.F.; Idzorek, G.; Oona, H.; Kirkpatrick, R.C.; Lindemuth, I.R.; Sheehey, P.T.

    1999-07-01

    Magnetized Target Fusion (MTF) target plasma experiments have been performed at the Los Alamos National Laboratory Colt facility for roughly three years. The capacitor bank has a maximum output voltage of 120 kV, maximum energy store of 0.25 mJ, and can deliver at least 2 MA of current to a load in 2.5 microseconds. The approach for MTF target plasma generation has been to drive a z-directed current through a plasma which is contained by a 2 cm radius by 2 cm high cylindrical metal wall. The initial mass for the target plasma comes from either a static uniform fill of hydrogen or deuterium gas, or from a polyethylene fiber mounted among the central axis. Polyethylene fibers were used as a substitute for the cryogenically frozen deuterium fibers that were originally planned for. The diagnostic set includes an array of 12 B-dot probes, optical framing camera, gated OMA visible spectrometer, time-resolved monochrometer, filtered silicon photodiodes, neutron yield, and a laser interferometer. The data obtained allows an assessment of the plasma temperature, density, magnetization, and decay time. With this, the suitability of these plasmas for an MTF application will be addressed.

  17. Study of dual radio frequency capacitively coupled plasma: an analytical treatment matched to an experiment

    Science.gov (United States)

    Saikia, P.; Bhuyan, H.; Escalona, M.; Favre, M.; Wyndham, E.; Maze, J.; Schulze, J.

    2018-01-01

    The behavior of a dual frequency capacitively coupled plasma (2f CCP) driven by 2.26 and 13.56 MHz radio frequency (rf) source is investigated using an approach that integrates a theoretical model and experimental data. The basis of the theoretical analysis is a time dependent dual frequency analytical sheath model that casts the relation between the instantaneous sheath potential and plasma parameters. The parameters used in the model are obtained by operating the 2f CCP experiment (2.26 MHz + 13.56 MHz) in argon at a working pressure of 50 mTorr. Experimentally measured plasma parameters such as the electron density, electron temperature, as well as the rf current density ratios are the inputs of the theoretical model. Subsequently, a convenient analytical solution for the output sheath potential and sheath thickness was derived. A comparison of the present numerical results is done with the results obtained in another 2f CCP experiment conducted by Semmler et al (2007 Plasma Sources Sci. Technol. 16 839). A good quantitative correspondence is obtained. The numerical solution shows the variation of sheath potential with the low and high frequency (HF) rf powers. In the low pressure plasma, the sheath potential is a qualitative measure of DC self-bias which in turn determines the ion energy. Thus, using this analytical model, the measured values of the DC self-bias as a function of low and HF rf powers are explained in detail.

  18. Beta limits in H-modes and VH-modes in JET

    Energy Technology Data Exchange (ETDEWEB)

    Smeulders, P.; Hender, T.C.; Huysmans, G.; Marcus, F.; Ali-Arshad, S.; Alper, B.; Balet, B.; Bures, M.; Deliyanakis, N.; Esch, H. de; Fshpool, G.; Jarvis, O.N.; Jones, T.T.C.; Ketner, W.; Koenig, R.; Lawson, K.; Lomas, P.; O`Brien, D.; Sadler, G.; Stok, D.; Stubberfield, P.; Thomas, P.; Thomen, K.; Wesson, J. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Nave, M.F. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior Tecnico

    1994-07-01

    In Hot-ion H- and VH-modes, the highest achieved beta was about 10% below the Troyon value in the best case of discharge 26087. The operational space of the high beta discharges obtained before March 1992 has been explored as function of the parameters H{sub ITER89P}, {beta}{sub n}, q{sub 95}, I{sub p}. Also, a limiting envelope on the fusion reactivity as a function of the average plasma pressure and beta has been observed with R{sub DD} related to {beta}{sub {phi}}{sup 2}.B{sub {phi}}{sup 4}. MHD stability analysis shows that the JET VH modes at the edge are in the second region for ballooning mode stability. The dependence of ballooning stability and the n=1 external kink on the edge current density is analyzed. (authors). 6 figs., 6 refs.

  19. Determination of plasma displacement based on eddy current diagnostics for the Keda Torus eXperiment

    Science.gov (United States)

    Tu, Cui; Li, Hong; Liu, Adi; Li, Zichao; Zhang, Yuan; You, Wei; Tan, Mingsheng; Luo, Bing; Adil, Yolbarsop; Hu, Jintong; Wu, Yanqi; Yan, Wentan; Xie, Jinlin; Lan, Tao; Mao, Wenzhe; Ding, Weixing; Xiao, Chijin; Zhuang, Ge; Liu, Wandong

    2017-10-01

    The measurement of plasma displacement is one of the most basic diagnostic tools in the study of plasma equilibrium and control in a toroidal magnetic confinement configuration. During pulse discharge, the eddy current induced in the vacuum vessel and shell will produce an additional magnetic field at the plasma boundary, which will have a significant impact on the measurement of plasma displacement using magnetic probes. In the newly built Keda Torus eXperiment (KTX) reversed field pinch device, the eddy current in the composite shell can be obtained at a high spatial resolution. This device offers a new way to determine the plasma displacement for KTX through the multipole moment expansion of the eddy current, which can be obtained by unique probe arrays installed on the inner and outer surfaces of the composite shell. In an ideal conductor shell approximation, the method of multipole moment expansion of the poloidal eddy current for measuring the plasma displacement in toroidal coordinates, is more accurate than the previous method based on symmetrical magnetic probes, which yielded results in cylindrical coordinates. Through an analytical analysis of many current filaments and numerical simulations of the current distribution in toroidal coordinates, the scaling relation between the first moment of the eddy current and the center of gravity of the plasma current is obtained. In addition, the origin of the multipole moment expansion of the eddy current in KTX is retrieved simultaneously. Preliminary data on the plasma displacement have been collected using these two methods during short pulse discharges in the KTX device, and the results of the two methods are in reasonable agreement.

  20. Gyrokinetic Studies of Resonant Magnetic Perturbation Effect on Microturbulence in DIII-D H-Mode Pedestal

    Science.gov (United States)

    Holod, Ihor; Lin, Zhihong; Taimourzadeh, Sam; Nazikian, Raffi; Spong, Donald; Wingen, Andreas

    2016-10-01

    Vacuum Resonant Magnetic Perturbation (RMP) applied to otherwise axisymmetric plasmas for the purpose of ELM mitigation produce in general a combination of non resonant effects preserving closed flux surfaces (kink response) and resonant effects that introduce magnetic islands. The effect of the plasma kink response on the stability and transport of edge turbulence is studied using the gyrokinetic code GTC for a DIII-D discharge with applied n=2 vacuum RMP. Three reference equilibria were modeled using VMEC code, based on DIII-D shot 158103: axisymmetric (no RMP) equilibrium, n=2 RMP, and artificially amplified RMPx10 equilibria. Gyrokinetic simulations reveal no increase of growth rates for electrostatic driftwave instability and electromagnetic kinetic-ballooning mode in the presence of the RMP. The effect of RMP on zonal flow damping is found to be insufficient to modify turbulent transport. Therefore, the plasma kink response to the RMP cannot account for the change in the turbulence level seen in experiments with suppressed ELMs. These results demonstrate that other physics must be controlling the transition in confinement responsible for ELM suppression. Work is supported by General Atomics subcontract 4500055243, U.S. DOE Grant DE-SC0010416 and DE-SC0013804, and by General Atomics collaboration agreement under DOE Grant DE-FG03-94ER54271.

  1. Intrinsic momentum generation by a combined neoclassical and turbulence mechanism in diverted DIII-D plasma edge

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Janghoon; Choe, W. [Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Chang, C. S.; Ku, S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Kwon, J. M. [National Fusion Research institute, Daejeon 305-806 (Korea, Republic of); Müller, Stefan H. [Max Planck Institute for Plasma Physics, Garching 85748 (Germany); Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)

    2014-09-15

    Fluid Reynolds stress from turbulence has usually been considered to be responsible for the anomalous toroidal momentum transport in tokamak plasma. Experiment by Müller et al. [Phys. Rev. Lett. 106, 115001 (2011)], however, reported that neither the observed edge rotation profile nor the inward momentum transport phenomenon at the edge region of an H-mode plasma could be explained by the fluid Reynolds stress measured with reciprocating Langmuir-probe. The full-function gyrokinetic code XGC1 is used to explain, for the first time, Müller et al.'s experimental observations. It is discovered that, unlike in the plasma core, the fluid Reynolds stress from turbulence is not sufficient for momentum transport physics in plasma edge. The “turbulent neoclassical” physics arising from the interaction between kinetic neoclassical orbit dynamics and plasma turbulence is key in the tokamak edge region across the plasma pedestal into core.

  2. Radiofrequency antenna for suppression of parasitic discharges in a helicon plasma thruster experiment

    Science.gov (United States)

    Takahashi, Kazunori

    2012-08-01

    A radiofrequency (rf) antenna for helicon plasma thruster experiments is developed and tested using a permanent magnets helicon plasma source immersed in a vacuum chamber. A magnetic nozzle is provided by permanent magnets arrays and an argon plasma is produced by a 13.56 MHz radiofrequency helicon-wave or inductively-coupled discharge. A parasitic discharge outside the source tube is successfully suppressed by covering the rf antenna with a ceramic ring and a grounded shield; a decrease in the ion saturation current of a Langmuir probe located outside the source tube is observed and the ion saturation current on axis increases simultaneously, compared with the case of a standard uncovered rf antenna. It is also demonstrated that the covered antenna can yield stable operation of the source.

  3. Measurements of Plasma Power Losses in the C-2 Field-Reversed Configuration Experiment

    Science.gov (United States)

    Korepanov, Sergey; Smirnov, Artem; Garate, Eusebio; Donin, Alexandr; Kondakov, Alexey; Singatulin, Shavkat

    2013-10-01

    A high-confinement operating regime with plasma lifetimes significantly exceeding past empirical scaling laws was recently obtained by combining plasma gun edge biasing and tangential Neutral Beam Injection in the C-2 field-reversed configuration (FRC) experiment. To analyze the power balance in C-2, two new diagnostic instruments - the pyroelectric (PE) and infrared (IR) bolometers - were developed. The PE bolometer, designed to operate in the incident power density range from 0.1-100 W/cm2, is used to measure the radial power loss, which is dominated by charge-exchange neutrals and radiation. The IR bolometer, which measures power irradiated onto a thin metal foil inserted in the plasma, is designed for the power density range from 0.5-5 kW/cm2. The IR bolometer is used to measure the axial power loss from the plasma near the end divertors. The maximum measurable pulse duration of ~ 10 ms is limited by the heat capacitance of the IR detector. Both detectors have time resolution of about 10-100 μs and were calibrated in absolute units using a high power neutral beam. We present the results of first direct measurements of axial and radial plasma power losses in C-2.

  4. AWAKE Design Report: A Proton-Driven Plasma Wakefield Acceleration Experiment at CERN

    CERN Document Server

    Caldwell, A; Lotov, K; Muggli, P; Wing, M

    2013-01-01

    The AWAKE Collaboration has been formed in order to demonstrate proton driven plasma wakefield acceleration for the first time. This technology could lead to future colliders of high energy but of a much reduced length compared to proposed linear accelerators. The SPS proton beam in the CNGS facility will be injected into a 10m plasma cell where the long proton bunches will be modulated into significantly shorter micro-bunches. These micro-bunches will then initiate a strong wakefield in the plasma with peak fields above 1 GV/m that will be harnessed to accelerate a bunch of electrons from about 20MeV to the GeV scale within a few meters. The experimental program is based on detailed numerical simulations of beam and plasma interactions. The main accelerator components, the experimental area and infrastructure required as well as the plasma cell and the diagnostic equipment are discussed in detail. First protons to the experiment are expected at the end of 2015 and this will be followed by an initial 3–4 ye...

  5. Ring-averaged ion velocity distribution function probe for laboratory magnetized plasma experiment

    Science.gov (United States)

    Kawamori, Eiichirou; Chen, Jinting; Lin, Chiahsuan; Lee, Zongmau

    2017-10-01

    Ring-averaged velocity distribution function of ions at a fixed guiding center position is a fundamental quantity in the gyrokinetic plasma physics. We have developed a diagnostic tool for the ring averaged velocity distribution function of ions for laboratory plasma experiments, which is named as the ring-averaged ion distribution function probe (RIDFP). The RIDFP is a set of ion collectors for different velocities. It is designed to be immersed in magnetized plasmas and achieves momentum selection of incoming ions by the selection of the ion Larmor radii. To nullify the influence of the sheath potential surrounding the RIDFP on the orbits of the incoming ions, the electrostatic potential of the RIDFP body is automatically adjusted to coincide with the space potential of the target plasma with the use of an emissive probe and a voltage follower. The developed RIDFP successfully measured the equilibrium ring-averaged velocity distribution function of a laboratory magnetized plasma, which was in accordance with the Maxwellian distribution having an ion temperature of 0.2 eV.

  6. Ring-averaged ion velocity distribution function probe for laboratory magnetized plasma experiment.

    Science.gov (United States)

    Kawamori, Eiichirou; Chen, Jinting; Lin, Chiahsuan; Lee, Zongmau

    2017-10-01

    Ring-averaged velocity distribution function of ions at a fixed guiding center position is a fundamental quantity in the gyrokinetic plasma physics. We have developed a diagnostic tool for the ring averaged velocity distribution function of ions for laboratory plasma experiments, which is named as the ring-averaged ion distribution function probe (RIDFP). The RIDFP is a set of ion collectors for different velocities. It is designed to be immersed in magnetized plasmas and achieves momentum selection of incoming ions by the selection of the ion Larmor radii. To nullify the influence of the sheath potential surrounding the RIDFP on the orbits of the incoming ions, the electrostatic potential of the RIDFP body is automatically adjusted to coincide with the space potential of the target plasma with the use of an emissive probe and a voltage follower. The developed RIDFP successfully measured the equilibrium ring-averaged velocity distribution function of a laboratory magnetized plasma, which was in accordance with the Maxwellian distribution having an ion temperature of 0.2 eV.

  7. Pressure and energy balance of stagnating plasmas in z-pinch experiments: implications to current flow at stagnation.

    Science.gov (United States)

    Maron, Y; Starobinets, A; Fisher, V I; Kroupp, E; Osin, D; Fisher, A; Deeney, C; Coverdale, C A; Lepell, P D; Yu, E P; Jennings, C; Cuneo, M E; Herrmann, M C; Porter, J L; Mehlhorn, T A; Apruzese, J P

    2013-07-19

    Detailed spectroscopic diagnostics of the stagnating plasma in two disparate z pinches allow, for the first time, the examination of the plasma properties within a 1D shock wave picture, demonstrating a good agreement with this picture. The conclusion is that for a wide range of imploding-plasma masses and current amplitudes, in experiments optimizing non-Planckian hard radiation yields, contrary to previous descriptions the stagnating plasma pressure is balanced by the implosion pressure, and the radiation energy is provided by the imploding-plasma kinetic energy, rather than by the magnetic-field pressure and magnetic-field-energy dissipation, respectively.

  8. Lower hybrid current drive experiments in support of high confinement long pulse operation in EAST

    Science.gov (United States)

    Ekedahl, Annika; Ding, Bojiang; Gong, Xianzu; Goniche, Marc; Li, Miaohui; Peysson, Yves; Qian, Jinping; Hillairet, Julien; Hoang, Tuong; Liu, Fukun; Qin, Chengming; Song, Yuantao; Wang, Xiaojie; Zhang, Xinjun; Zhao, Yanping; Zou, Xiao-Lan

    2017-10-01

    The lower hybrid current drive (LHCD) system plays a crucial role in the mission of the Experimental Advanced Superconducting Tokamak (EAST) and is a prerequisite for reaching long pulse, high confinement plasmas on EAST [1, 2]. LHCD experiments and modelling [3] have been carried out on EAST in 2015-2016, with the aim to optimising EAST long pulse scenarios, and at the same time gain experience for the exploitation of WEST [4]. Experiments have been carried out to study the LH current drive efficiency in different plasma configurations (Upper Single Null and Lower Single Null). The effect of the gas feed location on the LH wave coupling was investigated by comparing gas fuelling from high field side, low field side and upper divertor. In view of long pulse H-mode scenarios, a series of H-mode experiments were conducted where all the heating power was provided by RF heating methods only, i.e. LHCD, ECRH and ICRH. H-modes were sustained in both Upper Single Null (W divertor) and Lower Single Null (carbon divertor) configurations, with loop voltage maintained as low as 50 mV.

  9. Tungsten impurity transport experiments in Alcator C-Mod to address high priority research and development for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Loarte, A.; Polevoi, A. R.; Hosokawa, M. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Reinke, M. L. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Chilenski, M.; Howard, N.; Hubbard, A.; Hughes, J. W.; Rice, J. E.; Walk, J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Köchl, F. [Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Vienna (Austria); Pütterich, T.; Dux, R. [Max-Planck-Institut für Plasmaphysik, Boltzmanstraße 2, D-85748 Garching (Germany); Zhogolev, V. E. [NRC “Kurchatov Institute,” Kurchatov Square 1, 123098 Moscow (Russian Federation)

    2015-05-15

    Experiments in Alcator C-Mod tokamak plasmas in the Enhanced D-alpha H-mode regime with ITER-like mid-radius plasma density peaking and Ion Cyclotron Resonant heating, in which tungsten is introduced by the laser blow-off technique, have demonstrated that accumulation of tungsten in the central region of the plasma does not take place in these conditions. The measurements obtained are consistent with anomalous transport dominating tungsten transport except in the central region of the plasma where tungsten transport is neoclassical, as previously observed in other devices with dominant neutral beam injection heating, such as JET and ASDEX Upgrade. In contrast to such results, however, the measured scale lengths for plasma temperature and density in the central region of these Alcator C-Mod plasmas, with density profiles relatively flat in the core region due to the lack of core fuelling, are favourable to prevent inter and intra sawtooth tungsten accumulation in this region under dominance of neoclassical transport. Simulations of ITER H-mode plasmas, including both anomalous (modelled by the Gyro-Landau-Fluid code GLF23) and neoclassical transport for main ions and tungsten and with density profiles of similar peaking to those obtained in Alcator C-Mod show that accumulation of tungsten in the central plasma region is also unlikely to occur in stationary ITER H-mode plasmas due to the low fuelling source by the neutral beam injection (injection energy ∼ 1 MeV), which is in good agreement with findings in the Alcator C-Mod experiments.

  10. Optical pyrometer system for collisionless shock experiments in high-power laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Morita, T.; Sakawa, Y.; Kuramitsu, Y.; Sano, T.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Dono, S.; Ide, T.; Tanji, H.; Shiroshita, A. [Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Shibata, S.; Aoki, H. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Waugh, J. N.; Woolsey, N. C. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Gregory, C. D. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Route de Saclay, 91128 Palaiseau (France)

    2012-10-15

    A temporally and spatially resolved optical pyrometer system has been fielded on Gekko XII experiments. The system is based on the self-emission measurements with a gated optical imager (GOI) and a streaked optical pyrometer (SOP). Both detectors measure the intensity of the self-emission from laser-produced plasmas at the wavelength of 450 nm with a bandpass filter with a width of {approx}10 nm in FWHM. The measurements were calibrated with different methods, and both results agreed with each other within 30% as previously reported [T. Morita et al., Astrophys. Space Sci. 336, 283 (2011)]. As a tool for measuring the properties of low-density plasmas, the system is applicable for the measurements of the electron temperature and density in collisionless shock experiments [Y. Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)].

  11. The development of a distributed computing environment for the design and modeling of plasma spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Nash, J.K.; Eme, W.G.; Lee, R.W. [Lawrence Livermore National Lab., CA (United States); Salter, J.M. [South Gosforth Computer Systems, Ltd., South Gosforth, Newcastle Upon Tyne, (United Kingdom)

    1994-10-01

    The design and analysis of plasma spectroscopy experiments can be significantly complicated by relatively routine computational tasks arising from the massive amount of data encountered in the experimental design and analysis stages of the work. Difficulties in obtaining, computing, manipulating and visualizing the information represent not simply an issue of convenience -- they have a very real limiting effect on the final quality of the data and on the potential for arriving at meaningful conclusions regarding an experiment. We describe ongoing work in developing a portable UNIX environment shell with the goal of simplifying and enabling these activities for the plasma-modeling community. Applications to the construction of atomic kinetics models and to the analysis of x-ray transmission spectroscopy will be shown.

  12. The Project PLASMONX for Plasma Acceleration Experiments and a Thomson X-Ray Source at SPARC

    CERN Document Server

    Serafini, Luca; Alessandria, Franco; Bacci, Alberto; Baldeschi, Walter; Barbini, Alessandro; Bellaveglia, Marco; Bertolucci, Sergio; Biagini, Maria; Boni, Roberto; Bonifacio, Rodolfo; Boscolo, Ilario; Boscolo, Manuela; Bottigli, Ubaldo; Broggi, Francesco; Castellano, Michele; Cecchetti, Carlo A; Cialdi, Simone; Clozza, Alberto; De Martinis, Carlo; Di Pirro, Giampiero; Drago, Alessandro; Esposito, Adolfo; Ferrario, Massimo; Ficcadenti, L; Filippetto, Daniele; Fusco, Valeria; Galimberti, Marco; Gallo, Alessandro; Gatti, Giancarlo; Ghigo, Andrea; Giove, Dario; Giulietti, Antonio; Giulietti, Danilo; Gizzi, Leonida A; Golosio, Bruno; Guiducci, Susanna; Incurvati, Maurizio; Köster, Petra; Labate, Luca; Ligi, Carlo; Marcellini, Fabio; Maroli, Cesare; Mauri, Marco; Migliorati, Mauro; Mostacci, Andrea; Oliva, Pier N; Palumbo, Luigi; Pellegrino, Luigi; Petrillo, Vittoria; Piovella, Nicola; Poggiu, Angela; Pozzoli, Roberto; Preger, Miro; Ricci, Ruggero; Rome, Massimiliano; Rossi, Antonella; Sanelli, Claudio; Serio, Mario; Sgamma, Francesco; Spataro, Bruno; Stecchi, Alessandro; Stella, Angelo; Stumbo, Simone; Tazzioli, Franco; Tommasini, Paolo; Vaccarezza, Cristina; Vescovi, Mario; Vicario, Carlo

    2005-01-01

    We present the status of the activity on the project PLASMONX, which foresees the installation of a multi-TW Ti:Sa laser system at the CNR-ILIL laboratory to conduct plasma acceleration experiments and the construction of an additional beam line at SPARC to develop a Thomson X-ray source at INFN-LNF. After pursuing self-injection experiments at ILIL, when the electron beam at SPARC will be available the SPARC laser system will be upgraded to TW power level in order to conduct either external injection plasma acceleration experiments and ultra-bright X-ray pulse generation with the Thomson source. Results of numerical simulations modeling the interaction of the SPARC electron beam and the counter-propagating laser beam are presented with detailed discussion of the monochromatic X-ray beam spectra generated by Compton backscattering: X-ray energies are tunable in the range 20 to 1000 keV, with pulse duration from 30 fs to 20 ps. Preliminary simulations of plasma acceleration with self-injection are illustrated,...

  13. Simulations of Super Alfvenic Laser Ablation Experiments in the Large Plasma Device

    Science.gov (United States)

    Clark, Stephen Eric

    Hybrid plasma simulations, consisting of kinetic ions treated using standard Particle- In-Cell (PIC) techniques and an inertialess charge-neutralizing electron fluid, have been used to investigate the properties of collisionless shocks for a number of years. They agree well with sparse data obtained by flying through Earth's bow shock and have been used to model high energy explosions in the ionosphere. In this doctoral dissertation hybrid plasma simulation is used on much smaller scales to model collisionless shocks in a controlled laboratory setting. Initially a two-dimensional hybrid code from Los Alamos National Laboratory was used to find the best experimental parameters for shock formation, and interpret experimental data. It was demonstrated using the hybrid code that the experimental parameters needed to generate a shock in the laboratory are relaxed compared to previous work that was done. It was also shown that stronger shocks can be generated when running into a density gradient. Laboratory experiments at the University of California at Los Angeles using the high energy kJ-class Nd:Glass 1053 nm Raptor laser, and later the low energy yet high repetition rate 25 J Nd:Glass 1053 nm Peening laser have been performed in the Large Plasma Device (LAPD), which have provided some much needed data to benchmark the hybrid simulation method. The LAPD provides a repeatable, quiescent, ambient magnetized plasma to surround the exploding laser produced plasma that is ablated from a High Density Polyethylene (HDPE) target. The plasma density peaks in the machine at ni O(1013 cm-3 ), which is sufficiently dense to strongly couple energy and momentum from a laser ablated carbon plasma ejected from the HDPE target into the magnetized ambient plasma. It has been demonstrated that a sub-critical shock is formed in the LAPD using the high energy Raptor laser, though the data from this experiment is scant. Hybrid simulation was used as an analysis tool for the shock

  14. Application of imaging plates to x-ray imaging and spectroscopy in laser plasma experiments (invited)

    Science.gov (United States)

    Izumi, N.; Snavely, R.; Gregori, G.; Koch, J. A.; Park, H.-S.; Remington, B. A.

    2006-10-01

    We report recent progress in x-ray diagnosis of laser-plasma experiments using imaging plates. Imaging plates are photostimulable phosphor screens [BaF(Br0.85,I0.15):Eu2+] deposited on flexible metal or plastic substrates. We applied imaging plates to x-ray microscopy of inertial confinement fusion experiments. Self-emission x-ray images of imploded cores were obtained successfully with high-magnification, target-mounted pinholes using imaging plates as detectors. Imaging plates were also used in ultraintense laser experiments at the Rutherford Appleton Laboratory, where small samarium foils were irradiated by high intensity laser pulses from the Vulcan laser system. K-shell x rays from the foil (˜40keV) were used as a line x-ray source for one-dimensional microscopic radiography, and the performance of imaging plates on high-energy x-ray backlit radiography experiments was demonstrated by imaging sinusoidal grooves of 6μm amplitude on a Au foil. Detailed K-shell spectra from Cu targets were also obtained by coupling an imaging plate with a highly ordered pyrolytic graphite crystal spectrometer. The performance of the imaging plates as evaluated in actual laser plasma experiments is presented.

  15. Laser-induced fluorescence measurements on plasma science experiments at PPPL

    Energy Technology Data Exchange (ETDEWEB)

    Koepke, Mark

    2011-12-20

    Collaborative research between WVU and PPPL was carried out at WVU for the purpose of incorporating the sophisticated diagnostic technique known as laser-induced fluorescence (LIF) in the Paul-Trap Simulation Experiment (PTSX) at PPPL. WVU assembled a LIF system at WVU, transported it to PPPL, helped make LIF experiments on the PTSX device, participated in PTSX science, and trained PPPL staff in LIF techniques. In summary, WVU refurbished a non-operational LIF system being loaned from University of Maryland to PPPL and, by doing so, provided PPPL with additional diagnostic capability for its PTSX device and other General Plasma Science experiments. WVU students, staff, and faculty will visit PPPL to collaborate on PTSX experiments in the future.

  16. Shock-like pulse experiment in a strongly coupled dusty plasma

    Science.gov (United States)

    Kananovich, Anton; Goree, J.

    2017-10-01

    Compressional pulses are excited in a dusty plasma using a wire moved at a supersonic speed. The dusty plasma consists of a 2D monolayer of polymer microspheres electrically levitated in a low-temperature argon RF plasma. The microspheres gained a large negative charge so that they interacted with each other as a strongly coupled component, partly shielded by the electrons and ions. The wire, which had a negative potential that repelled microspheres, was moved at a constant speed, causing a compressional pulse to propagate. This pulse had shock-like properties because the wire was moved faster than the longitudinal sound speed in the microspheres. The experiment was repeated for the dusty plasma both in liquid and solid states, all of the controlled parameters except for the dust kinetic temperature being equal. The laser rastering method was used to change the kinetic temperature. Several experimental runs were done with different wire speeds for the both cases. An increase in the wire propagation speed increased the propagation speed of the compressional pulse. High pulse propagation speeds were obtained with Mach numbers up to 5. For high pulse propagation speeds crystal buckling was observed. Video microscopy was the main diagnostic. Supported by U.S. Dept. of Energy.

  17. Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP

    Energy Technology Data Exchange (ETDEWEB)

    Sheerin, J. P., E-mail: jsheerin@emich.edu [Physics and Astronomy, Eastern Michigan Univ., Ypsilanti, MI 48197 (United States); Cohen, Morris B., E-mail: mcohen@gatech.edu [Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250 (United States)

    2015-12-10

    The ionosphere is the ionized uppermost layer of our atmosphere (from 70 – 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 – 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 – 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP’s unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 – 3000 Hz) and VLF (3 – 30 kHz) radio waves which are guided to global distances in the Earth

  18. Full-f Neoclassical Simulations toward a Predictive Model for H-mode Pedestal Ion Energy, Particle and Momentum Transport

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, D. J. [PPPL; Boedo, J. A. [University of California San Diego; Burrell, K. H. [General Atomics; Chang, C. S. [PPPL; Canik, J. M. [ORNL; deGrassie, J. S. [General Atomics; Gerhardt, S. P. [PPPL; Grierson, B. A. [General Atomics; Groebner, R. J. [General Atomics; Maingi, Rajesh [PPPL; Smith, S. P. [General Atomics

    2014-09-01

    Energy and particle transport rates are decoupled in the H-mode edge since the ion thermal transport rate is primarily set by the neoclassical transport of the deuterium ions in the tail of the thermal energy distribution, while the net particle transport rate is set by anomalous transport of the colder bulk ions. Ion orbit loss drives the energy distributions away from Maxwellian, and describes the anisotropy, poloidal asymmetry and local minimum near the separatrix observed in the Ti profile. Non-Maxwellian distributions also drive large intrinsic edge flows, and the interaction of turbulence at the top of the pedestal with the intrinsic edge flow can generate an intrinsic core torque. The primary driver of the radial electric field (Er) in the pedestal and scrapeoff layer (SOL) are kinetic neoclassical effects, such as ion orbit loss of tail ions and parallel electron loss to the divertor. This paper describes the first multi-species kinetic neoclassical transport calculations for ELM-free H-mode pedestal and scrape-off layer on DIII-D using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. This interpretative technique quantifies the role of neoclassical, anomalous and neutral transport to the overall pedestal structure, and consequently illustrates the importance of including kinetic effects self-consistently in transport calculations around transport barriers.

  19. Results from colliding magnetized plasma jet experiments executed at the Trident laser facility

    Science.gov (United States)

    Manuel, M. J.-E.; Rasmus, A. M.; Kurnaz, C. C.; Klein, S. R.; Davis, J. S.; Drake, R. P.; Montgomery, D. S.; Hsu, S. C.; Adams, C. S.; Pollock, B. B.

    2015-11-01

    The interaction of high-velocity plasma flows in a background magnetic field has applications in pulsed-power and fusion schemes, as well as astrophysical environments, such as accretion systems and stellar mass ejections into the magnetosphere. Experiments recently executed at the Trident Laser Facility at the Los Alamos National Laboratory investigated the effects of an expanding aluminum plasma flow into a uniform 4.5-Tesla magnetic field created using a solenoid designed and manufactured at the University of Michigan. Opposing-target experiments demonstrate interesting collisional behavior between the two magnetized flows. Preliminary interferometry and Faraday rotation measurements will be presented and discussed. This work is funded by the U.S Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840. Support for this work was provided by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Astrophysical Observatory for NASA under contract NAS8-03060.

  20. Megagauss field generation for high-energy-density plasma science experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Rovang, Dean Curtis; Struve, Kenneth William; Porter, John Larry Jr.

    2008-10-01

    There is a need to generate magnetic fields both above and below 1 megagauss (100 T) with compact generators for laser-plasma experiments in the Beamlet and Petawatt test chambers for focused research on fundamental properties of high energy density magnetic plasmas. Some of the important topics that could be addressed with such a capability are magnetic field diffusion, particle confinement, plasma instabilities, spectroscopic diagnostic development, material properties, flux compression, and alternate confinement schemes, all of which could directly support experiments on Z. This report summarizes a two-month study to develop preliminary designs of magnetic field generators for three design regimes. These are, (1) a design for a relatively low-field (10 to 50 T), compact generator for modest volumes (1 to 10 cm3), (2) a high-field (50 to 200 T) design for smaller volumes (10 to 100 mm3), and (3) an extreme field (greater than 600 T) design that uses flux compression. These designs rely on existing Sandia pulsed-power expertise and equipment, and address issues of magnetic field scaling with capacitor bank design and field inductance, vacuum interface, and trade-offs between inductance and coil designs.

  1. First on-line positron experiments en route to pair-plasma creation

    Energy Technology Data Exchange (ETDEWEB)

    Stanja, Juliane; Hergenhahn, Uwe; Stenson, Eve V. [Max-Planck-Institut fuer Plasmaphysik (Germany); Niemann, Holger; Sunn Pedersen, Thomas [Max-Planck-Institut fuer Plasmaphysik (Germany); Ernst-Moritz-Arndt Universitaet Greifswald (Germany); Saitoh, Haruhiko [Max-Planck-Institut fuer Plasmaphysik (Germany); The University of Tokyo (Japan); Stoneking, Matthew R. [Lawrence University (United States); Hugenschmidt, Christoph; Piochacz, Christian [Technische Universitaet Muenchen (Germany); Schweikhard, Lutz [Ernst-Moritz-Arndt Universitaet Greifswald (Germany)

    2016-07-01

    Electron-positron plasmas are predicted to show a fundamentally different behavior from traditional ion-electron plasmas, because of the equal masses of the two species. Using up to 10{sup 9} positrons per second provided by the NEPOMUC (Neutron-Induced Positron Source Munich) facility, the APEX/PAX team aims to create the first such plasma confined in a toroidal magnetic trap. Positron beam parameters as well as efficient injection and confinement schemes for both species in toroidal geometries are fundamental to the project. In this contribution we present results from first on-line positron experiments. Besides characterizing the NEPOMUC beam we conducted positron injection experiments into a dipole magnetic field configuration. Using static electric fields, a 5-eV positron beam was transported across magnetic field lines into the confinement region. With this method, up to 38% of the incoming particles reach the confinement region and make at least a 180 revolution around the magnet. Under dedicated experimental conditions confinement on the order of 1 ms was realized.

  2. Boundary plasma heat flux width measurements for poloidal magnetic fields above 1 Tesla in the Alcator C-Mod tokamak

    Science.gov (United States)

    Brunner, Dan; Labombard, Brian; Kuang, Adam; Terry, Jim; Alcator C-Mod Team

    2017-10-01

    The boundary heat flux width, along with the total power flowing into the boundary, sets the power exhaust challenge for tokamaks. A multi-machine boundary heat flux width database found that the heat flux width in H-modes scaled inversely with poloidal magnetic field (Bp) and was independent of machine size. The maximum Bp in the database was 0.8 T, whereas the ITER 15 MA, Q =10 scenario will be 1.2 T. New measurements of the boundary heat flux width in Alcator C-Mod extend the international database to plasmas with Bp up to 1.3 T. C-Mod was the only experiment able to operate at ITER-level Bp. These new measurements are from over 300 plasma shots in L-, I-, and EDA H-modes spanning essentially the whole operating space in C-Mod. We find that the inverse-Bp dependence of the heat flux width in H-modes continues to ITER-level Bp, further reinforcing the empirical projection of 500 μm heat flux width for ITER. We find 50% scatter around the inverse-Bp scaling and are searching for the `hidden variables' causing this scatter. Supported by USDoE award DE-FC02-99ER54512.

  3. Experiments with Plasmas Produced by Potassium-Seeded Cyanogen Oxygen Flames for Study of Radio Transmission at Simulated Reentry Vehicle Plasma Conditions

    Science.gov (United States)

    Huber, Paul W.; Gooderum, Paul B.

    1961-01-01

    A method for the chemical production of an ionized gas stream for application to radio transmission studies is described. Involved is the combustion of gaseous cyanogen and oxygen with the addition of vaporized potassium in some cases to further increase the ionization. Experiments are described in which a 3-inch-diameter subsonic free jet at atmospheric pressure is used, and the results are presented. The plasma obtained by using this method is sufficient to simulate plasma conditions expected for reentering hypersonic vehicles. The unseeded plasma stream temperature is indicated to be about 4,200 K, with the degree of ionization indicated to be that expected from thermal equilibrium considerations. Measurements of radio-signal loss due to the unseeded flame plasma are presented for microwaves of 8 to 20 kmc transmitted through the stream and for a dipole transmitting model of 219.5 mc immersed in the stream. Favorable comparison of these results with the simple plane-wave signal-attenuation theory was obtained. In the case of a 9.4-kmc microwave signal of 30-kw peak power, the preliminary indication is that the plasma characteristics were not changed due to this strong signal. Comparison of a simplified concept of radio-signal attenuation due to plasmas is made with some hypersonic reentry vehicle signal-loss data. Other areas of plasma research using this method for the transmission problem are indicated.

  4. Plasma experiments with 1. 06-. mu. m lasers at the Lawrence Livermore Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstrom, H.G.; Holzrichter, J.F.; Manes, K.R.; Storm, E.K.; Boyle, M.J.; Brooks, K.M.; Haas, R.A.; Phillion, D.W.; Rupert, V.C.

    1976-12-20

    Recent laser fusion experiments at the Lawrence Livermore Laboratory have provided basic data concerning: laser beam propagation and absorption in high temperature plasmas, electron energy transport processes that transfer the absorbed laser energy to the high-density ablation region, the general fluid dynamic expansion and compression of the heated plasma, and the processes responsible for the production of 14-MeV neutrons during implosion experiments. Irradiation experiments were performed with Nd:YAG glass laser systems: the two-beam Janus (less than or equal to40 J/100 ps, approx.0.4 TW) and Argus (less than or equal to140 J, 35 ps, approx.4 TW), and the single beam Cyclops (less than or equal to70 J/100 ps, approx.0.7 TW). Two classes of targets have been used: glass microshells (approx.40 to 120 ..mu..m in diameter with approx.0.75-..mu..m-thick walls) filled with an equimolar deuterium-tritium mixture, and disks (approx.160 to 600 ..mu..m in diameter and approx. 10 ..mu..m thick) of several compositions. The targets were supported in vacuum (pressure less than or equal to10/sup -5/ Torr) by thin glass stalks. This paper reports on results related to the propagation, absorption, and scattering of laser light by both spherical and planar targets.

  5. Observation of a new turbulence-driven limit-cycle state in H-modes with lower hybrid current drive and lithium-wall conditioning in the EAST superconducting tokamak

    DEFF Research Database (Denmark)

    Wang, H.Q.; Xu, G.S.; Guo, H.Y.

    2012-01-01

    The first high confinement H-mode plasma has been obtained in the Experimental Advanced Superconducting Tokamak (EAST) with about 1 MW lower hybrid current drive after wall conditioning by lithium evaporation and real-time injection of Li powder. Following the L–H transition, a small-amplitude, low...... correlated with each other, with nearly no phase differences poloidally and toroidally, and finite phase difference radially, thus providing strong evidence for zonal flows. The growth, saturation and disappearance of the zonal flows are strongly correlated with those of the high-frequency turbulence....... And the measurements demonstrate that the energy gain of zonal flows is of the same order as the energy loss of turbulence. This strongly suggests the interactions between zonal flows and high-frequency turbulences at the pedestal during the limit-cycle state....

  6. Recent progress of RF-dominated experiments on EAST

    Science.gov (United States)

    Liu, F. K.; Zhao, Y. P.; Shan, J. F.; Zhang, X. J.; Ding, B. J.; Wang, X. J.; Wang, M.; Xu, H. D.; Qin, C. M.; Li, M. H.; Gong, X. Z.; Hu, L. Q.; Wan, B. N.; Song, Y. T.; Li, J. G.

    2017-10-01

    The research of EAST program is mostly focused on the development of high performance steady state scenario with ITER-like poloidal configuration and RF-dominated heating schemes. With the enhanced ITER-relevant auxiliary heating and current drive systems, the plasma profile control by coupling/integration of various combinations has been investigated, including lower hybrid current drive (LHCD), electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH). The 12 MW ICRH system has been installed on EAST. Heating and confinement studies using the Hydrogen Minority Heating scheme have been investigated. One of the importance challenges for EAST is coupling higher power into the core plasma, experiments including changing plasma position, electron density, local gas puffing and antenna phasing scanning were performed to improve ICRF coupling efficiency on EAST. Results show that local gas injection and reducing the k|| can improve the coupling efficiency directly. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and sustained at relatively high density, even up to ne ˜ 4.5 × 1019 m-3, where a current drive effect is still observed. Meanwhile, effect of source frequency (2.45GHz and 4.6GHz) on LHCD characteristic has been studied on EAST, showing that higher frequency improves penetration of the coupled LH (lower hybrid) power into the plasma core and leads to a better effect on plasma characteristics. Studies demonstrate the role of parasitic effects of edge plasma in LHCD and the mitigation by increasing source frequency. Experiments of effect of LH spectrum and plasma density on plasma characteristics are performed, suggesting the possibility of plasma control for high performance. The development of a 4MW ECRH system is in progress for the purpose of plasma heating and MHD control. The built ECRH system with 1MW source power has been successfully put into use on EAST in 2015. H-mode discharges with L

  7. Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, C.I.; Adli, E.; Corde, S.; Decker, F.J.; England, R.J.; Erickson, R.; Fisher, A.; Gessner, S.; Hast, C.; Hogan, M.J.; Li, S.Z.; Lipkowitz, N.; Litos, M.; Nosochkov, Y.; Seeman, J.; Sheppard, J.C.; Tudosa, I.; White, G.; Wienands, U.; Woodley, M.; Wu, Z.; /SLAC /UCLA

    2012-09-14

    FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV, 3 nC electron beams, short (20 {micro}m) bunches and small (20 {micro}m wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. FACET is also a source of THz radiation for material studies. We present the FACET design, initial operating experience and first science from the facility.

  8. Laser pulse propagation in a meter scale rubidium vapor/plasma cell in AWAKE experiment

    CERN Document Server

    Joulaei, Atefeh; Berti, Nicolas; Kasparian, Jerome; Mirzanejhad, Saeed; Muggli, Patric

    2016-01-01

    We present the results of numerical studies of laser pulse propagating in a 3.5 cm Rb vapor cell in the linear dispersion regime by using a 1D model and a 2D code that has been modified for our special case. The 2D simulation finally aimed at finding laser beam parameters suitable to make the Rb vapor fully ionized to obtain a uniform, 10 m-long, at least 1 mm in radius plasma in the next step for the AWAKE experiment.

  9. Electron beam injection experiments - Replication of flight observations in a laboratory beam plasma discharge

    Science.gov (United States)

    Bernstein, W.; Mcgarity, J. O.; Konradi, A.

    1983-01-01

    Recent electron beam injection experiments in the lower ionosphere have produced two perplexing results: (1) At altitudes from 140 km to 220 km, the beam associated 391.4 nm intensity is relatively independent of altitude despite the decreasing N2 abundance. (2) The radial extent of the perturbed region populated by beam associated energetic electrons significantly exceeds the nominal gyrodiameter for 90 deg injection. A series of laboratory measurements is described in which both of these flight results appear to have been closely reproduced. The laboratory results are reasonably consistent with the transition from a collision dominated to collisionless beam-plasma discharge configuration.

  10. Characterization of scintillators for lost alpha diagnostics on burning plasma experiments

    OpenAIRE

    M., "Nishiura; N., Kubo; T., Hirouchi; T., Ido; T., Nagasaka; T.", Mutoh; S., Matsuyama; M., Isobe; A., Okamoto; K., Shinto; S., Kitajima; M., Sasao; M., Nakatsuka; K.", Fujioka

    2006-01-01

    The characteristics of light output by ion beam irradiations under high ion fluxes have been measured for three kinds of scintillators: ZnS:Ag deposited on the glass plate, Y_3Al_5O_12:Ce powder stiffened with a binder, and Y_3Al_5O_12:Ce ceramics sintered at high temperature. The ion beam flux in the range from 10^12 to 10^13 ions/(cm^2 s) is irradiated to simulate the burning plasma experiments. The decrease of light output has been observed by long time ion irradiation. The deteriorati...

  11. JET experiments with tritium and deuterium–tritium mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Horton, Lorne, E-mail: Lorne.Horton@jet.uk [JET Exploitation Unit, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); European Commission, B-1049 Brussels (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Batistoni, P. [Unità Tecnica Fusione - ENEA C. R. Frascati - via E. Fermi 45, Frascati (Roma), 00044, Frascati (Italy); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Boyer, H.; Challis, C.; Ćirić, D. [CCFE, Culham Science Centre, Abingdon OX14 3DB, Oxon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Donné, A.J.H. [EUROfusion Programme Management Unit, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); FOM Institute DIFFER, PO Box 1207, NL-3430 BE Nieuwegein (Netherlands); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Eriksson, L.-G. [European Commission, B-1049 Brussels (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Garcia, J. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Garzotti, L.; Gee, S. [CCFE, Culham Science Centre, Abingdon OX14 3DB, Oxon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Hobirk, J. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Joffrin, E. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); and others

    2016-11-01

    Highlights: • JET is preparing for a series of experiments with tritium and deuterium–tritium mixtures. • Physics objectives include integrated demonstration of ITER operating scenarios, isotope and alpha physics. • Technology objectives include neutronics code validation, material studies and safety investigations. • Strong emphasis on gaining experience in operation of a nuclear tokamak and training scientists and engineers for ITER. - Abstract: Extensive preparations are now underway for an experiment in the Joint European Torus (JET) using tritium and deuterium–tritium mixtures. The goals of this experiment are described as well as the progress that has been made in developing plasma operational scenarios and physics reference pulses for use in deuterium–tritium and full tritium plasmas. At present, the high performance plasmas to be tested with tritium are based on either a conventional ELMy H-mode at high plasma current and magnetic field (operation at up to 4 MA and 4 T is being prepared) or the so-called improved H-mode or hybrid regime of operation in which high normalised plasma pressure at somewhat reduced plasma current results in enhanced energy confinement. Both of these regimes are being re-developed in conjunction with JET's ITER-like Wall (ILW) of beryllium and tungsten. The influence of the ILW on plasma operation and performance has been substantial. Considerable progress has been made on optimising performance with the all-metal wall. Indeed, operation at the (normalised) ITER reference confinement and pressure has been re-established in JET albeit not yet at high current. In parallel with the physics development, extensive technical preparations are being made to operate JET with tritium. The state and scope of these preparations is reviewed, including the work being done on the safety case for DT operation and on upgrading machine infrastructure and diagnostics. A specific example of the latter is the planned calibration at

  12. ANALYSIS OF DATA FROM Z-PINCH MTF TARGET PLASMA EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    F. WYSOCKI; J. TACCETTI; ET AL

    1999-04-01

    The Los Alamos National Laboratory Colt facility has been used to create target plasma for Magnetized Target Fusion (MTF). The primary results regarding magnetic field, plasma density, plasma temperature, and hot plasma lifetime are summarized and the suitability of these plasma targets for MTF is assessed.

  13. Characterization of the plasma current quench during disruptions in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gerhardt, S.P., Menard, J.E., and the NSTX Research Team

    2008-12-17

    A detailed analysis of the plasma current quench in the National Spherical Torus Experiment [M.Ono, et al Nuclear Fusion 40, 557 (2000)] is presented. The fastest current quenches are fit better by a linear waveform than an exponential one. Area-normalized current quench times down to .4 msec/m2 have been observed, compared to the minimum of 1.7 msec/m2 recommendation based on conventional aspect ratio tokamaks; as noted in previous ITPA studies, the difference can be explained by the reduced self-inductance at low aspect ratio and high-elongation. The maximum instantaneous dIp/dt is often many times larger than the mean quench rate, and the plasma current before the disruption is often substantially less than the flat-top value. The poloidal field time-derivative during the disruption, which is directly responsible for driving eddy currents, has been recorded at various locations around the vessel. The Ip quench rate, plasma motion, and magnetic geometry all play important roles in determining the rate of poloidal field change.

  14. Plasma and antenna coupling characterization in ICRF-wall conditioning experiments

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Manash Kumar, E-mail: manashkr@gmail.com [National Institute of Technology Agartala, Jirania, Tripura 799 055 (India); Institut fuer Energieforschung-Plasmaphysik FZ Juelich, Euratom Association, 52425 Juelich (Germany); Lyssoivan, A.; Koch, R.; Wauters, T. [LPP-ERM/KMS, Association Euratom-Belgian State, 1000 Brussels (Belgium); Douai, D. [CEA, IRFM, Association Euratom-CEA, 13108 St Paul lez Durance (France); Bobkov, V. [Max Planck Institute fur Plasma Physik, Euratom Association, 85748 Garching (Germany); Van Eester, D.; Lerche, E.; Ongena, J. [LPP-ERM/KMS, Association Euratom-Belgian State, 1000 Brussels (Belgium); Rohde, V. [Max Planck Institute fur Plasma Physik, Euratom Association, 85748 Garching (Germany); Noterdaeme, J.-M. [Max Planck Institute fur Plasma Physik, Euratom Association, 85748 Garching (Germany); Gent University, EESA Department, B-9000 Gent (Belgium); Graham, M.; Mayoral, M.-L.; Monakhov, I.; Nightingale, M. [CCFE/Euratom Fusion Association, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Plyusnin, V.V. [Instituto de Plasmas e Fusao Nuclear, Associacao EURATOM-IST, Av. Rovisco Pais, Lisbon (Portugal)

    2012-02-15

    Ion Cyclotron Wall Conditioning (ICWC) discharges, in pulsed-mode operation, were carried out in the divertor tokamaks ASDEX Upgrade (AUG) and JET to simulate the scenario of ITER wall conditioning at half-field (AUG) and full-field (JET). ICWC-plasma and antenna coupling characterization results obtained during the Ion Cyclotron Resonance Frequency (ICRF)-Wall Conditioning experiments performed in helium-hydrogen mixture in AUG and helium-deuterium mixtures in JET are presented here. Safe operational regimes for optimum ICWC in ITER could be explored for different magnetic fields. Satisfactory antenna coupling in the Mode Conversion scenario along with reproducible generation of ICRF plasmas and reliable wall conditioning were achieved by coupling RF power from one or two ICRF antennas at two (AUG, JET) different resonant frequencies. These results are in qualitative agreement with the predictions of 1-D TOMCAT code. Present study of ICWC indicates towards the beneficial effect of application of an additional (along with toroidal magnetic field) stationary vertical (B{sub V} Much-Less-Than B{sub T}) magnetic field on antenna coupling and plasma parameters. The results obtained from JET and AUG tokamaks, presented in this paper, emphasizes the proposed phenomenological schemes for further development of ICWC in superconducting tokamaks.

  15. Schlieren, Phase-Contrast, and Spectroscopy Diagnostics for the LBNL HIF Plasma Channel Experiment

    Science.gov (United States)

    Ponce, D. M.; Niemann, C.; Fessenden, T. J.; Leemans, W.; Vandersloot, K.; Dahlbacka, G.; Yu, S. S.; Sharp, W. M.; Tauschwitz, A.

    1999-11-01

    The LBNL Plasma Channel experiment has demonstrated stable 42-cm Z-pinch discharge plasma channels with peak currents in excess of 50 kA for a 7 torr nitrogen, 30 kV discharge. These channels offer the possibility of transporting heavy-ion beams for inertial fusion. We postulate that the stability of these channels resides in the existance of a neutral-gas density depresion created by a pre-pulse discharge before the main capacitor bank discharge is created. Here, we present the results and experimental diagnostics setup used for the study of the pre-pulse and main bank channels. Observation of both the plasma and neutral gas dynamics is achieved. Schlieren, Zernike's phase-contrast, and spectroscopic techniques are used. Preliminary Schlieren results show a gas shockwave moving radially at a rate of ≈ 10^6 mm/sec as a result of the fast and localized deposited energy during the evolution of the pre-pulse channel. This data will be used to validate simulation codes (BUCKY and CYCLOPS).

  16. Electron beam injection experiments - The beam-plasma discharge at low pressures and magnetic field strengths

    Science.gov (United States)

    Bernstein, W.; Leinbach, H.; Kellogg, P.; Monson, S.; Hallinan, T.; Garriott, O. K.; Konradi, A.; Mccoy, J.; Daly, P.; Baker, B.

    1978-01-01

    The paper describes electron beam injection experiments which clarify observational results obtained in rocket flights. A column of enhanced density plasma, exceeding the density expected from ionization by primary beam electrons, was observed in a large vacuum system at low magnetic fields (1 to 1.5 G) and low ambient pressures (10 to the minus 6 to 10 to the minus 5 torr). The peak luminosity of the discharge was about 10 times that of the beam alone, and the radius increased by a factor of three. In the absence of the discharge, RF emission is observed at 1.1 to 1.2 times the cyclotron frequency, and a strong band of RF noise with upper frequency cutoff at about the cyclotron frequency is observed in the discharge mode, along with higher frequency noise at or near the plasma frequency. The onset of the plasma discharge is critically dependent on beam current. The described results agree with observations obtained at much higher densities and magnetic fields in fusion research studies.

  17. Global electrostatic potential structures of merging flux tubes in TS-U torus plasma merging experiment

    Science.gov (United States)

    Sawada, Asuka; Hatano, Hironori; Akimitsu, Moe; Cao, Qinghong; Yamasaki, Kotaro; Tanabe, Hiroshi; Ono, Yasushi; TS-Group Team

    2017-10-01

    We have been investigating 2D potential profile of global merging tokamaks to solve high-power heating of magnetic reconnection in TS-3 and TS-3U (ST, FRC:R =0.2m, 1985-, 2017-) and TS-4 (ST, FRC:R =0.5m, 2000-), UTST (ST:R =0.45m, 2008-) and MAST (ST:R = 0.9m, 2000-) devices. These experiments made clear that the electrostatic potential well is formed not only in the downstream area of magnetic reconnection but also in the whole common (reconnected) flux area of two merging flux tubes: tokamak plasmas. This fact suggests that the ion acceleration/heating occurs in much wider region than the reconnection downstream. We studied how the potential structure depends on key reconnection parameters:guide toroidal field and plasma collisionality. We found the polarity of the guide toroidal field determines those of potential hills and wells, indicating their formation is affected by the Hall effect. The peak value of the electrostatic potential well decreased with gas pressure increasing, suggesting plasma collisionality suppresses the Hall effect. The relationship between the electrostatic potential structure and anomalous ion heating is being studied as a possible cause for the high-power heating of fast magnetic reconnection. This work was supported by JSPS KAKENHI Grant Numbers 15H05750, 15K14279 and 17H04863.

  18. Role of E  ×  B on in-out divertor asymmetry in high recycling/partial detachment regimes under L-mode and H-mode conditions

    Science.gov (United States)

    Du, Hailong; Sang, Chaofeng; Wang, Liang; Bonnin, Xavier; Wang, Huiqian; Sun, Jizhong; Wang, Dezhen

    2017-11-01

    The role of the E  ×  B electric drift on background plasma and carbon impurity in-out divertor asymmetry was estimated under L-mode and H-mode conditions in the high recycling regime and partial detachment regime by using the edge plasma code SOLPS5.1. It was found that the poloidal electric drift E r  ×  B also may play a dominant role during H-mode discharge in high recycling regime, instead of the radial electric drift E θ   ×  B. Moreover, it also was found that during H-mode with partial detachment both components can play simultaneously a crucial role in inducing the in-out asymmetry. Their synergistic effect can make the asymmetry much more obvious than that with either of them separately. However, E θ   ×  B in partial detachment during L-mode can play a main role in inducing in-out asymmetry, rather than E r  ×  B. Besides, the role of E  ×  B components on carbon (C) impurity in-out asymmetry was also addressed. Simulation results reveal that E r  ×  B or E θ   ×  B individually have a very small effect on C impurity ions in-out asymmetry, especially E θ   ×  B, while their synergistic effect makes the impurity ions exhibit a much more remarkable in-out asymmetry. Moreover, it was found that the E r  ×  B and E θ   ×  B drift flows in the private flux region could play a crucial role in inducing C impurity in-out asymmetry, rather than the parallel flow or electric drift flow in the upstream SOL region when only considering E  ×  B.

  19. Overview and first results of experiments on magnetic reconnection between colliding magnetized plasmas at the National Ignition Facility

    Science.gov (United States)

    Fox, W.; Rosenberg, M.; Schaeffer, D.; Fiksel, G.; Park, H. S.; Kalantar, D.; Bhattacharjee, A.; Huang, Y.-M.; Ji, H.; Matteucci, J.; Gao, L.; Uzdensky, D.; Birkel, A.; Li, C. K.; Hu, S. X.; Shvydky, A.

    2017-10-01

    Expanding laser-produced plasmas naturally self-generate magnetic fields by the Biermann battery effect, and the collision of two plumes can drive magnetic reconnection. The National Ignition Facility at LLNL occupies a unique position for laser-driven magnetic reconnection experiments by simultaneously allowing very large plasma temperature, low plasma resistivity, and large system size, which allows observation of secondary instabilities driven during magnetic reconnection and particle acceleration relevant to astrophysical plasmas. Magnetic reconnection experiments have been conducted on the NIF through the NIF Discovery Science program with the first experimental shots conducted in May 2017. We will present the design of the experimental platform and results from the first experimental day. Magnetic reconnection data is obtained from proton radiography based on a DHe3 backlighter, x-ray self-emission, and a new low-energy particle spectrometer (NIF EPPS-300G) developed by the NIF Facility and Engineering and fielded for the first time on these experiments.

  20. Analysis of higher harmonics on bidirectional heat pulse propagation experiment in helical and tokamak plasmas

    Science.gov (United States)

    Kobayashi, T.; Ida, K.; Inagaki, S.; Tsuchiya, H.; Tamura, N.; Choe, G. H.; Yun, G. S.; Park, H. K.; Ko, W. H.; Evans, T. E.; Austin, M. E.; Shafer, M. W.; Ono, M.; López-bruna, D.; Ochando, M. A.; Estrada, T.; Hidalgo, C.; Moon, C.; Igami, H.; Yoshimura, Y.; Tsujimura, T. Ii.; Itoh, S.-I.; Itoh, K.

    2017-07-01

    In this contribution we analyze modulation electron cyclotron resonance heating (MECH) experiment and discuss higher harmonic frequency dependence of transport coefficients. We use the bidirectional heat pulse propagation method, in which both inward propagating heat pulse and outward propagating heat pulse are analyzed at a radial range, in order to distinguish frequency dependence of transport coefficients due to hysteresis from that due to other reasons, such as radially dependent transport coefficients, a finite damping term, or boundary effects. The method is applied to MECH experiments performed in various helical and tokamak devices, i.e. Large Helical Device (LHD), TJ-II, Korea Superconducting Tokamak Advanced Research (KSTAR), and Doublet III-D (DIII-D) with different plasma conditions. The frequency dependence of transport coefficients are clearly observed, showing a possibility of existence of transport hysteresis in flux-gradient relation.

  1. Rossby vortices, spiral structures, solitons astrophysics and plasma physics in shallow water experiments

    CERN Document Server

    Nezlin, Mikhail V

    1993-01-01

    This book can be looked upon in more ways than one. On the one hand, it describes strikingly interesting and lucid hydrodynamic experiments done in the style of the "good old days" when the physicist needed little more than a piece of string and some sealing wax. On the other hand, it demonstrates how a profound physical analogy can help to get a synoptic view on a broad range of nonlinear phenomena involving self-organization of vortical structures in planetary atmo­ spheres and oceans, in galaxies and in plasmas. In particular, this approach has elucidated the nature and the mechanism of such grand phenomena as the Great of galaxies. A number of our Red Spot vortex on Jupiter and the spiral arms predictions concerning the dynamics of spiral galaxies are now being confirmed by astronomical observations stimulated by our experiments. This book is based on the material most of which was accumulated during 1981-88 in close cooperation with our colleagues, experimenters from the Plasma Physics Department of the...

  2. Development of modular scalable pulsed power systems for high power magnetized plasma experiments

    Science.gov (United States)

    Bean, I. A.; Weber, T. E.; Adams, C. S.; Henderson, B. R.; Klim, A. J.

    2017-10-01

    New pulsed power switches and trigger drivers are being developed in order to explore higher energy regimes in the Magnetic Shock Experiment (MSX) at Los Alamos National Laboratory. To achieve the required plasma velocities, high-power (approx. 100 kV, 100s of kA), high charge transfer (approx. 1 C), low-jitter (few ns) gas switches are needed. A study has been conducted on the effects of various electrode geometries and materials, dielectric media, and triggering strategies; resulting in the design of a low-inductance annular field-distortion switch, optimized for use with dry air at 90 psig, and triggered by a low-jitter, rapid rise-time solid-state Linear Transformer Driver. The switch geometry and electrical characteristics are designed to be compatible with Syllac style capacitors, and are intended to be deployed in modular configurations. The scalable nature of this approach will enable the rapid design and implementation of a wide variety of high-power magnetized plasma experiments. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. Approved for unlimited release, LA-UR-17-2578.

  3. Neutron Emission Experiment on the Megajoule Plasma-Focus Facility Operated at the IPPLM

    National Research Council Canada - National Science Library

    Scholz, Marek

    2000-01-01

    .... He will also determine neutron emission characteristics and investigate the relation between the neutron yield and plasma sheath dynamics and plasma sheath structure, particular attention will...

  4. Survey of ELF-VLF plasma waves in outer radiation belt observed by Cluster STAFF-SA experiment

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2008-10-01

    Full Text Available Various types of plasma waves have profound effects on acceleration and scattering of radiation belt particles. For the purposes of radiation belt modeling it is necessary to know statistical distributions of plasma wave parameters. This paper analyzes four years of plasma wave observations in the Earth's outer radiation belt obtained by the STAFF-SA experiment on board Cluster spacecraft. Statistical distributions of spectral density of different plasma waves observed in ELF-VLF range (chorus, plasmaspheric hiss, magnetosonic waves are presented as a function of magnetospheric coordinates and geomagnetic activity indices. Comparison with other spacecraft studies supports some earlier conclusions about the distribution of chorus and hiss waves and helps to remove the long-term controversy regarding the distribution of equatorial magnetosonic waves. This study represents a step towards the development of multi-spacecraft database of plasma wave activity in radiation belts.

  5. Analysis of induced stress on materials exposed to laser-plasma radiation during high-intensity laser experiments

    Science.gov (United States)

    Scisciò, M.; Barberio, M.; Liberatore, C.; Veltri, S.; Laramée, A.; Palumbo, L.; Legaré, F.; Antici, P.

    2017-11-01

    In this work, we investigate the damage produced in materials when exposed to a laser-generated plasma. The plasma was generated by interaction of a high-intensity laser with Oxygen. We demonstrate that the stress induced on the target surface of a Tantalum target (typical materials used as Plasma Facing Material) after 10 h of plasma exposure is equivalent to the stress induced during 1 h of conventional laser ablation using a pulsed 0.5 J laser. In both cases we obtain a surface erosion in the tens of μm, and a change in the surface roughness in the tens of nm for the stressed materials. The erosion rate of 1 nm/s, explained in terms of surface fragmentation at thermodynamic equilibrium, generates a slow damage to the materials exposed to the plasma. Our method allows indicating safety parameters for the maintenance of materials used in high-intensity laser experiments.

  6. Diagnostic suite of the C-2U advanced beam-driven field-reversed configuration plasma experiment

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, M. C., E-mail: mthompson@trialphaenergy.com; Gota, H.; Putvinski, S.; Tuszewski, M.; Binderbauer, M. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2016-11-15

    The C-2U experiment at Tri Alpha Energy studies the evolution of field-reversed configuration (FRC) plasmas sustained by neutral beam injection. Data on the FRC plasma performance are provided by a comprehensive suite of diagnostics that includes magnetic sensors, interferometry, Thomson scattering, spectroscopy, bolometry, reflectometry, neutral particle analyzers, and fusion product detectors. While many of these diagnostic systems were inherited from the preceding experiment C-2, C-2U has a variety of new and upgraded diagnostic systems: multi-chord far-infrared polarimetry, multiple fast imaging cameras with selectable atomic line filters, proton detector arrays, and 100 channel bolometer units capable of observing multiple regions of the spectrum simultaneously. In addition, extensive ongoing work focuses on advanced methods of measuring separatrix shape and plasma current profile that will facilitate equilibrium reconstruction and active control of the FRC plasma.

  7. Diagnostic suite of the C-2U advanced beam-driven field-reversed configuration plasma experiment.

    Science.gov (United States)

    Thompson, M C; Gota, H; Putvinski, S; Tuszewski, M; Binderbauer, M

    2016-11-01

    The C-2U experiment at Tri Alpha Energy studies the evolution of field-reversed configuration (FRC) plasmas sustained by neutral beam injection. Data on the FRC plasma performance are provided by a comprehensive suite of diagnostics that includes magnetic sensors, interferometry, Thomson scattering, spectroscopy, bolometry, reflectometry, neutral particle analyzers, and fusion product detectors. While many of these diagnostic systems were inherited from the preceding experiment C-2, C-2U has a variety of new and upgraded diagnostic systems: multi-chord far-infrared polarimetry, multiple fast imaging cameras with selectable atomic line filters, proton detector arrays, and 100 channel bolometer units capable of observing multiple regions of the spectrum simultaneously. In addition, extensive ongoing work focuses on advanced methods of measuring separatrix shape and plasma current profile that will facilitate equilibrium reconstruction and active control of the FRC plasma.

  8. Integrated core–SOL–divertor modelling for ITER including impurity: effect of tungsten on fusion performance in H-mode and hybrid scenario

    NARCIS (Netherlands)

    Zagorski, R.; Voitsekhovitch, I.; Ivanova-Stanik, I.; Kochl, F.; Belo, da Silva Ares; Fable, E.; Garcia, J.; Garzotti, L.; Hobirk, J.; Hogeweij, G. M. D.; Joffrin, E.; Litaudon, X.; Polevoi, A. R.; Telesca, G.; JET Contributors,

    2015-01-01

    The compatibility of two operational constraints—operation above the L–H power threshold and at low power to divertor—is examined for ITER long pulse H-mode and hybrid scenarios in integrated core–scrape off layer (SOL)–divertor modelling including impurities (intrinsic Be, He, W and seeded Ne). The

  9. Tritium Plasma Experiment Upgrade and Improvement of Surface Diagnostic Capabilities at STAR Facility for Enhancing Tritium and Nuclear PMI Sciences

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, M.; Taylor, C. N.; Pawelko, R. J.; Cadwallader, L. C.; Merrill, B. J.

    2016-04-01

    The Tritium Plasma Experiment (TPE) is a unique high-flux linear plasma device that can handle beryllium, tritium, and neutron-irradiated plasma facing materials, and is the only existing device dedicated to directly study tritium retention and permeation in neutron-irradiated materials with tritium [M. Shimada et.al., Rev. Sci. Instru. 82 (2011) 083503 and and M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008]. The plasma-material-interaction (PMI) determines a boundary condition for diffusing tritium into bulk PFCs, and the tritium PMI is crucial for enhancing fundamental sciences that dictate tritium fuel cycles and safety and are high importance to an FNSF and DEMO. Recently the TPE has undergone major upgrades in its electrical and control systems. New DC power supplies and a new control center enable remote plasma operations from outside of the contamination area for tritium, minimizing the possible exposure risk with tritium and beryllium. We discuss the electrical upgrade, enhanced operational safety, improved plasma performance, and development of optical spectrometer system. This upgrade not only improves operational safety of the worker, but also enhances plasma performance to better simulate extreme plasma-material conditions expected in ITER, Fusion Nuclear Science Facility (FNSF), and Demonstration reactor (DEMO). This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.

  10. Towards cooperative guidance and control of highly automated vehicles: H-Mode and Conduct-by-Wire.

    Science.gov (United States)

    Flemisch, Frank Ole; Bengler, Klaus; Bubb, Heiner; Winner, Hermann; Bruder, Ralph

    2014-01-01

    This article provides a general ergonomic framework of cooperative guidance and control for vehicles with an emphasis on the cooperation between a human and a highly automated vehicle. In the twenty-first century, mobility and automation technologies are increasingly fused. In the sky, highly automated aircraft are flying with a high safety record. On the ground, a variety of driver assistance systems are being developed, and highly automated vehicles with increasingly autonomous capabilities are becoming possible. Human-centred automation has paved the way for a better cooperation between automation and humans. How can these highly automated systems be structured so that they can be easily understood, how will they cooperate with the human? The presented research was conducted using the methods of iterative build-up and refinement of framework by triangulation, i.e. by instantiating and testing the framework with at least two derived concepts and prototypes. This article sketches a general, conceptual ergonomic framework of cooperative guidance and control of highly automated vehicles, two concepts derived from the framework, prototypes and pilot data. Cooperation is exemplified in a list of aspects and related to levels of the driving task. With the concept 'Conduct-by-Wire', cooperation happens mainly on the guidance level, where the driver can delegate manoeuvres to the automation with a specialised manoeuvre interface. With H-Mode, a haptic-multimodal interaction with highly automated vehicles based on the H(orse)-Metaphor, cooperation is mainly done on guidance and control with a haptically active interface. Cooperativeness should be a key aspect for future human-automation systems. Especially for highly automated vehicles, cooperative guidance and control is a research direction with already promising concepts and prototypes that should be further explored. The application of the presented approach is every human-machine system that moves and includes high

  11. Modeling Laser-Plasma Interaction over a Suite of NIF Experiments

    Science.gov (United States)

    Strozzi, D. J.; Berger, R. L.; Jones, O. S.; Chapman, T.; Woods, D. T.; MacLaren, S. A.; Michel, P.; Divol, L.

    2017-10-01

    We systematically study laser-plasma interaction (LPI) on NIF indirect-drive experiments, namely backscatter and cross-beam energy transfer. LLNL's best practice radiation-hydrodynamic simulation methodology in the Lasnex simulation code is employed without ad-hoc tuning to match experimental data. This entails converged numerical resolution, an improved DCA model for coronal (ne 1 keV) gold opacity, electron heat flux strongly limited to 0.03neTe3 / 2 me- 1 / 2 , and the inline CBET model. The rad-hydro plasma conditions are used for LPI analysis, namely linear instability gains, and the paraxial-envelope code pF3D. Simulated scattered-light spectra are also compared to measurements. We initially focus on shots with low backscatter, so its self-consistent treatment should not be important. These shots have low hohlraum fill density and short laser pulses, and the only significant backscatter is outer-beams Brillouin. Our long-term goals are to understand reflectivity trends to guide target design and develop LPI mitigation strategies. Work performed under auspices of US DoE by LLNL under Contract DE-AC52-07NA27344.

  12. Water cooling system leak proofing strategy for the Plasma Couette Experiment Upgrade (PCX-U)

    Science.gov (United States)

    Clark, Mike; Flanagan, Ken; Hernandez, Wilson; Jaeger, Austin; Laufman-Wollitzer, Lauren; Nikolau, Ethan; Tabbutt, Megan; Waleffe, Roger; Wallace, John; Xu, Yufan; Forest, Cary

    2016-10-01

    An improved system for water cooling several experimental components has been installed for the Plasma Couette Experiment Upgrade (PCX-U). The most important aspect of the upgrade was to cool the new SmCo permanent magnet cage array. Many methods of connecting water cooling pipes, tubes, and fittings were employed balancing several factors. These factors included ease of assembly/disassembly, reliability, operating pressure, operating temperature, chemical reactivity, and cost. The actions taken to develop the water cooling system will be discussed and illustrated. A focus will be made on sealing cooling water leaks from the inside out on small diameter metal passages (including extrusions, tubing, and fittings). These passages were located inside a vacuum environment, and only the ends of each passage were accessible to do the work. The vacuum vessel of PCX-U is a 1 meter diameter, 1 meter tall cylinder comprised of 0.25'' thick stainless steel. PCX-U has one removable end. Rings of SmCo magnets attached to a removable frame create a cusp field to contain the plasma and provide a resonance surface for the RF. This work is supported by the NSF.

  13. Global Simulations of Dynamo and Magnetorotational Instability in Madison Plasma Experiments and Astrophysical Disks

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Fatima [Univ. of New Hampshire, Durham, NH (United States)

    2014-07-31

    Large-scale magnetic fields have been observed in widely different types of astrophysical objects. These magnetic fields are believed to be caused by the so-called dynamo effect. Could a large-scale magnetic field grow out of turbulence (i.e. the alpha dynamo effect)? How could the topological properties and the complexity of magnetic field as a global quantity, the so called magnetic helicity, be important in the dynamo effect? In addition to understanding the dynamo mechanism in astrophysical accretion disks, anomalous angular momentum transport has also been a longstanding problem in accretion disks and laboratory plasmas. To investigate both dynamo and momentum transport, we have performed both numerical modeling of laboratory experiments that are intended to simulate nature and modeling of configurations with direct relevance to astrophysical disks. Our simulations use fluid approximations (Magnetohydrodynamics - MHD model), where plasma is treated as a single fluid, or two fluids, in the presence of electromagnetic forces. Our major physics objective is to study the possibility of magnetic field generation (so called MRI small-scale and large-scale dynamos) and its role in Magneto-rotational Instability (MRI) saturation through nonlinear simulations in both MHD and Hall regimes.

  14. The Titan Haze Simulation Experiment: Latest Laboratory Results and Dedicated Plasma Chemistry Model

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Raymond, Alexander; Mazur, Eric; Salama, Farid

    2017-10-01

    Here, we present the latest results on the gas- and solid phase analyses in the Titan Haze Simulation (THS) experiment, developed at the NASA Ames COSmIC simulation chamber. The THS is a unique experimental platform that allows us to simulate Titan’s complex atmospheric chemistry at Titan-like temperature (200 K) by cooling down N2-CH4-based mixtures in a supersonic expansion before inducing the chemistry by plasma. Because of the accelerated gas flow in the expansion, the residence time of the gas in the active plasma region is less than 3 µs. This results in a truncated chemistry that enables us to control how far in the chain of chemical reactions chemistry processes[1], by adding, in the initial gas mixture, heavier molecules that have been detected as trace elements on Titan.We discuss the results of recent Mid-infrared (MIR) spectroscopy[2] and X-ray Absorption Near Edge Structure spectroscopy studies of THS Titan tholins produced in different gas mixtures (with and without acetylene and benzene). Both studies have shown the presence of nitrogen chemistry, and differences in the level and nature of the nitrogen incorporation depending on the initial gas mixture. A comparison of THS MIR spectra to VIMS data has shown that the THS aerosols produced in simpler mixtures, i.e., that contain more nitrogen and where the N-incorporation is in isocyanide-type molecules instead of nitriles, are more representative of Titan’s aerosols.In addition, a new model has been developed to simulate the plasma chemistry in the THS. Electron impact and chemical kinetics equations for more than 120 species are followed. The calculated mass spectra[3] are in good agreement with the experimental THS mass spectra[1], confirming that the short residence time in the plasma cavity limits the growth of larger species and results in a truncated chemistry, a main feature of the THS.References:[1] Sciamma-O'Brien E. et al., Icarus, 243, 325 (2014)[2] Sciamma-O'Brien E. et al., Icarus

  15. Experiments on Interactions of Electrons with Molecular Ions in Fusion and Astrophysical Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bannister, Mark E [ORNL; Aliabadi, Habib [ORNL; Bahati, Eric [ORNL; Fogle, Mark R. [Oak Ridge National Laboratory (ORNL); Krstic, Predrag S [ORNL; Vane, C Randy [ORNL; Ehlerding, A. [Stockholm University, Sweden; Geppert, W. [Stockholm University, Sweden; Hellberg, F. [Stockholm University, Sweden; Zhaunerchyk, Vitali [Stockholm University, Sweden; Larsson, Mats [Stockholm University, Sweden; Thomas, Richard D [ORNL

    2007-01-01

    Through beam-beam experiments at the Multicharged Ion Research Facility (MIRF) at Oak Ridge National Laboratory (ORNL) and at the CRYRING heavy ion storage ring at Stockholm University, we are seeking to formulate a more complete picture of electron-impact dissociation of molecular ions. These inelastic collisions play important roles in many low temperature plasmas such as in divertors of fusion devices and in astrophysical environments. An electron-ion crossed beams experiment at ORNL investigates the dissociative excitation and dissociative ionization of molecular ions from a few eV up to 100 eV. Measurements on dissociative recombination (DR) experiments are made at CRYRING, where chemical branching fractions and fragmentation dynamics are studied. Taking advantage of a 250-kV acceleration platform at the MIRF, a merged electron-ion beams energy loss apparatus is employed to study DR down to zero energy. Recent results on the dissociation of molecular ions of importance in fusion and astrophysics are presented.

  16. Energetic Particle Physics In Fusion Research In Preparation For Burning Plasma Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gorelenkov, Nikolai N [PPPL

    2013-06-01

    The area of energetic particle (EP) physics of fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by W.W. Heidbrink and G.J. Sadler [1]. That review coincided with the start of deuterium-tritium (DT) experiments on Tokamak Fusion Test reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the "sea" of Alfven eigenmodes (AE) in particular by the toroidicityinduced AEs (TAE) modes and reversed shear Alfven (RSAE). In present paper we attempt a broad review of EP physics progress in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus) including helical/stellarator devices. Introductory discussions on basic ingredients of EP physics, i.e. particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others are given to help understanding the advanced topics of EP physics. At the end we cover important and interesting physics issues toward the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

  17. Measurement of Plasma Rotation Velocities in the STOR-M Tokamak

    Science.gov (United States)

    Morelli, Jordan; Xiao, Chijin; McColl, David; Hirose, Akira; Mitarai, Osamu

    2000-10-01

    Measurements of the plasma rotation velocities in the edge region of the Saskatchewan Torus-Modified (STOR-M) tokamak during one full cycle of alternating current operation and CT injection will be presented. In these experiments, a four sided Mach probe is used to measure the radial profile of the plasma poloidal and toroidal rotation velocities in the edge region. It has long been suspected that changes in the plasma edge region of both the velocity structure, and the radial electric field and its gradient are responsible for the transition to the ohmic high-confinement mode (H-mode). Furthermore, the results will help to check a recent theoretical model in which the confinement improvement is based on the toroidal velocity CURVATURE, consistent with the expectation that the tangential CT injection speeds up the toroidal flow.

  18. Four-color laser irradiation system for laser-plasma interaction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pennington, D.M.; Henesian, M.A.; Wilcox, R.B. [and others

    1996-06-01

    Since 1986, optical smoothing of the laser irradiance on targets for Inertial Confinement Fusion (ICF) has gained increasing attention. Optical smoothing can significantly reduce wavefront aberrations that produce nonuniformities in the energy distribution of the focal spot. Hot spots in the laser irradiance can induce local self focusing of the light, producing filamentation of the plasma. Filamentation can have detrimental consequences on the hydrodynamics of an ICF plasma, and can affect the growth of parametric instabilities, as well as add to the complexity of the study of such instabilities as stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). As experiments approach and exceed breakeven (i.e., where driver energy = fusion yield), the likelihood of significant excitation of these processes increases. As a result, the authors are including a scheme for implementing optical-beam smoothing for target experiments in the baseline design for the proposed next-generation ICF facility--the National Ignition Facility (NIF). To verify the efficacy of this design for the suppression of parametric instabilites in NIF-like indirect-drive targets, the authors successfully modified a Nova beamline to simulate the proposed NIF conditions. In this article, they discuss the laser science associated with a four-color target campaign on Nova to test the effect of f-number (ratio of focal length to beam diameter) and temporal smoothing on the scaling of SBS with a four-segment interaction beam using NIF-like parameters. The results of the target series associated with the four-color configuration are discussed elsewhere.

  19. Influence of atomic kinetics in the simulation of plasma microscopic properties and thermal instabilities for radiative bow shock experiments.

    Science.gov (United States)

    Espinosa, G; Rodríguez, R; Gil, J M; Suzuki-Vidal, F; Lebedev, S V; Ciardi, A; Rubiano, J G; Martel, P

    2017-03-01

    Numerical simulations of laboratory astrophysics experiments on plasma flows require plasma microscopic properties that are obtained by means of an atomic kinetic model. This fact implies a careful choice of the most suitable model for the experiment under analysis. Otherwise, the calculations could lead to inaccurate results and inappropriate conclusions. First, a study of the validity of the local thermodynamic equilibrium in the calculation of the average ionization, mean radiative properties, and cooling times of argon plasmas in a range of plasma conditions of interest in laboratory astrophysics experiments on radiative shocks is performed in this work. In the second part, we have made an analysis of the influence of the atomic kinetic model used to calculate plasma microscopic properties of experiments carried out on magpie on radiative bow shocks propagating in argon. The models considered were developed assuming both local and nonlocal thermodynamic equilibrium and, for the latter situation, we have considered in the kinetic model different effects such as external radiation field and plasma mixture. The microscopic properties studied were the average ionization, the charge state distributions, the monochromatic opacities and emissivities, the Planck mean opacity, and the radiative power loss. The microscopic study was made as a postprocess of a radiative-hydrodynamic simulation of the experiment. We have also performed a theoretical analysis of the influence of these atomic kinetic models in the criteria for the onset possibility of thermal instabilities due to radiative cooling in those experiments in which small structures were experimentally observed in the bow shock that could be due to this kind of instability.

  20. High-voltage interactions in plasma wakes: Results from the charging hazards and wake studies (CHAWS) flight experiments

    Science.gov (United States)

    Enloe, C. L.; Cooke, D. L.; Pakula, W. A.; Violet, M. D.; Hardy, D. A.; Chaplin, C. B.; Kirkwood, R. K.; Tautz, M. F.; Bonito, N.; Roth, C.; Courtney, G.; Davis, V. A.; Mandell, M. J.; Hastings, D. E.; Shaw, G. B.; Giffin, G.; Sega, R. M.

    1997-01-01

    Data from the charging hazards and wake studies (CHAWS) flight experiments on board space shuttle missions STS-60 and STS-69, during which a negatively biased, high-voltage (0-5 kV) probe was placed in a plasma wake in low Earth orbit, are presented. For these experiments the source of the wake was the 4-m-diameter Wake Shield Facility (WSF), which was operated both as a free-flying spacecraft and attached to the shuttle orbiter's robot arm. Current collection by the biased probe is investigated as a function of the density and temperature of the ambient plasma and the probe's location in the plasma wake. Current collection behavior is determined by the expansion of the high-voltage sheath into the ambient plasma stream. Consistent with preflight predictions, current collection on the probe is highly nonuniform, varying by more than 5 orders of magnitude across the surface of the probe. The onset of current collection, however, begins at voltages that are an order of magnitude lower than anticipated. This is likely due to the low-energy, turbulent plasma (typically 2-5% of the ambient density and up to 40% on occasion) observed in the ambient environment. This important minority constituent of the plasma was observed in the vicinity of the shuttle Orbiter and observed while the WSF was free-flying.

  1. Measurements of plasma profiles using a fast swept Langmuir probe in the VINETA-II magnetic reconnection experiment

    Science.gov (United States)

    Shesterikov, I.; Von Stechow, A.; Grulke, O.; Stenzel, R.; Klinger, T.

    2017-07-01

    A fast-swept Langmuir probe capable to be biased at a high voltages has been constructed and successfully operated at the VINETA-II magnetic reconnection experiment. The presented circuit has two main features beneficial for fast transient parameter changes in laboratory experiments as, e.g., plasma guns or magnetic reconnection: the implementation simplicity and the high voltage sweep range. This work presents its design and performance for time-dependent measurements of VINETA-II plasmas. The probe is biased with a sinusoidal voltage at a fixed frequency. Current - voltage characteristics are measured along the falling and rising slopes of the probe bias. The sweep frequency is fsweep= 150 kHz. The spatiotemporal evolution of radial plasma profiles is obtained by evaluation of the probe characteristics. The plasma density measurements agree with those derived from a microwave interferometer, demonstrating the reliability of the measurements. As a model plasma system, a plasma gun discharge with typical pulse times of 60 μ s is chosen.

  2. (Sub)nanosecond transient plasma for atmospheric plasma processing experiments: application to ozone generation and NO removal

    Science.gov (United States)

    Huiskamp, T.; Hoeben, W. F. L. M.; Beckers, F. J. C. M.; van Heesch, E. J. M.; Pemen, A. J. M.

    2017-10-01

    In this paper we use a (sub)nanosecond high-voltage pulse source (2-9 ns pulses with 0.4 ns rise time) to generate streamer plasma in a wire-cylinder reactor and apply it to two atmospheric plasma processing applications: ozone generation and NO removal. We will investigate what pulse parameters result in the highest plasma processing yields. The results show that for ozone generation, secondary-streamer effects appear to have a slight influence on the ozone yield: if the pulse duration increases and/or the voltage increases in such a way that streamers can start to cross the gap in the reactor, the ozone yields decrease. Furthermore, for NO removal, we see a similar effect of pulse duration and applied voltage as for the ozone generation, but the effect of the pulse duration is slightly different: long pulses result in the highest NO-removal yield. However, the NO-removal process is fundamentally different: besides removing NO, the plasma also produces NO and this production is more pronounced in the primary-streamer phase, which is why the pulse polarity has almost no influence on the NO-removal yield (only on the by-product formation). Moreover, the rise time of the pulses has a much more significant effect on ozone generation and NO removal than the pulse duration: a long rise time results in a lower enhanced electric field at the streamer heads, which consequently reduces the production of radicals required for ozone generation and NO removal, and decreases the streamer volume. Consequently, the resulting ozone yields and NO-removal yields are lower. Finally, the main conclusion is that the plasma generated with our nanosecond pulses is very efficient for ozone generation and NO removal, achieving yields as high as 175 g · kWh-1 for ozone generation and 2.5 mol · kWh-1 (or 14.9 eV per NO molecule) for NO removal.

  3. The target for the new plasma/wall experiment Magnum-PSI

    NARCIS (Netherlands)

    van den Berg, M. A.; Brons, S.; Kruijt, O. G.; Scholten, J.; Pasquet, R.; Smeets, P. H. M.; Schweer, B.; De Temmerman, G.

    2011-01-01

    The construction of Magnum-PSI is in its final stage. The aim is to provide a controlled and highly accessible linear plasma device to perform the basic plasma-surface interaction research needed for the design of the plasma facing components of future fusion devices. This contribution will focus on

  4. Laser cooled ion beams and strongly coupled plasmas for precision experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bussmann, Michael

    2008-03-17

    This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C{sup 3+} ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged {sup 24}Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)

  5. Development of a Multi-GeV spectrometer for laser-plasma experiment at FLAME

    Science.gov (United States)

    Valente, P.; Anelli, F.; Bacci, A.; Batani, D.; Bellaveglia, M.; Benocci, R.; Benedetti, C.; Cacciotti, L.; Cecchetti, C. A.; Clozza, A.; Cultrera, L.; Di Pirro, G.; Drenska, N.; Faccini, R.; Ferrario, M.; Filippetto, D.; Fioravanti, S.; Gallo, A.; Gamucci, A.; Gatti, G.; Ghigo, A.; Giulietti, A.; Giulietti, D.; Gizzi, L. A.; Koester, P.; Labate, L.; Levato, T.; Lollo, V.; Londrillo, P.; Martellotti, S.; Pace, E.; Pathak, N.; Rossi, A.; Tani, F.; Serafini, L.; Turchetti, G.; Vaccarezza, C.

    2011-10-01

    The advance in laser-plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular, the upcoming experiments with the 250 TW laser at the FLAME facility of the INFN Laboratori Nazionali di Frascati, will enter the GeV regime with more than 100 pC of electrons. At the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need for developing a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV), with still unknown angular divergences. Within the PlasmonX experiment at FLAME, a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence, present challenges in the design and construction of such a device. We present the design considerations for this spectrometer that lead to the use of scintillating fibers, multichannel photo-multipliers and a multiplexing electronics, a combination which is innovative in the field. We also present the experimental results obtained with a high intensity electron beam performed on a prototype at the LNF beam test facility.

  6. A new attempt using LabVIEW into a computational experiment of plasma focus device

    Science.gov (United States)

    Kim, Myungkyu

    2017-03-01

    The simulation program of plasma focus device based on S. Lee's model has been first developed since 30 years ago and it is widely used to date. Originally the program made by GWbasic language, and then modified by visual basic which was included in the Microsoft Excel. Using Excel well-known to researchers is a key advantage of this program. But it has disadvantages in displaying data in same graph, in slow calculation speed, and in displaying data and calculation of smaller time step. To overcome all these points, the LabVIEW that made by national instrument and based on graphical environment is used for simulation. Furthermore it is correlated with data acquisition of experiment, once experiment being the data is directly transferred to the simulation program and then analyzes and predicts for the next shot. The mass swept factor (fm) and current factor (fc) can be easily find out using this program. This paper describes the detail function and usage of the program and compares the results with the existing one.

  7. Transport experiments in Alcator-C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Greenwald, M.; Boivin, R.L.; Bonoli, P.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.; Golovato, S.; Graf, M.; Granetz, R.; Horne, S.; Hsu, T.; Hubbard, A.; Hutchinson, I.; Irby, J.; Kurz, C.; LaBombard, B.; Lipschultz, B.; Luke, T.; Marmar, E.; McCracken, G.; Niemczewski, A.; O`Shea, P.; Porkolab, M.; Rice, J.; Reardon, J.; Schachter, J.; Snipes, J.; Stek, P.; Takase, Y.; Terry, J.; Umansky, M.; Watterson, R.; Wolfe, S. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bombarda, F. [ENEA-Frascati, Frascati (Italy); May, M. [Johns Hopkins University, Baltimore, Maryland 21218 (United States); Welch, B. [University of Maryland, College Park, Maryland 20742 (United States)

    1995-06-01

    A series of transport experiments has been carried out in Alcator-C-Mod. [Phys Plasmas {bold 1}, 1511 (1994)]. Data from both Ohmic and ICRF (ion cyclotron range of frequencies) heated plasmas can be fitted with an L-mode (low mode) scaling law. The Ohmic {tau}{sub {ital E}}`s show no scaling with density in any regime and can reach values of 2--3 times neo-Alcator. Impurity confinement has been studied with the laser blow-off technique with {tau}{sub {ital I}} showing nearly linear scaling with plasma current. Ohmic and ICRF H modes are obtained over a wide range of discharge parameters, extending the range in the international database for {ital nB}, by almost a factor of 10. The power threshold for ELM-free (edge localized mode) discharges is in rough agreement with the scaling {ital P}/{ital S}=0.044{ital nB}. Energy diffusivities of Ohmic and ICRF heated plasmas have been measured from local analysis of plasma profiles and power fluxes. The same analysis produces a value for plasma resistivity which lies between the Spitzer and neoclassical calculations. Analysis of plasma transients have yielded values for particle diffusivity and convection velocity.

  8. Minority heating scenarios in and SST-1 plasmas

    Indian Academy of Sciences (India)

    Asim Kumar Chattopadhyay

    2017-12-19

    Dec 19, 2017 ... Abstract. A numerical analysis of ion cyclotron resonance heating scenarios in two species of low ion temperature plasma has been done to elucidate the physics and possibility to achieve H-mode in tokamak plasma. The analysis is done in the steady-state superconducting tokamak, SST-1, using phase-I ...

  9. Measurements of fast electron beams and soft X-ray emission from plasma-focus experiments

    Directory of Open Access Journals (Sweden)

    Surała Władysław

    2016-06-01

    Full Text Available The paper reports results of the recent experimental studies of pulsed electron beams and soft X-rays in plasma-focus (PF experiments carried out within a modified PF-360U facility at the NCBJ, Poland. Particular attention was focused on time-resolved measurements of the fast electron beams by means of two different magnetic analyzers, which could record electrons of energy ranging from about 41 keV to about 715 keV in several (6 or 8 measuring channels. For discharges performed with the pure deuterium filling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the first hard X-ray pulse detected by an external scintillation neutron-counter. In some of the analyzer channels, electron spikes (lasting about dozens of nanoseconds and appearing in different instants after the current peculiarity (so-called current dip were also recorded. For several discharges, fast ion beams, which were emitted along the z-axis and recorded with nuclear track detectors, were also investigated. Those measurements confirmed a multibeam character of the ion emission. The time-integrated soft X-ray images, which were taken side-on by means of a pinhole camera and sensitive X-ray films, showed the appearance of some filamentary structures and so-called hot spots. The application of small amounts of admixtures of different heavy noble gases, i.e. of argon (4.8% volumetric, krypton (1.6% volumetric, or xenon (0.8% volumetric, decreased intensity of the recorded electron beams, but increased intensity of the soft X-ray emission and showed more distinct and numerous hot spots. The recorded electron spikes have been explained as signals produced by quasi-mono-energetic microbeams emitted from tiny sources (probably plasma diodes, which can be formed near the observed hot spots.

  10. Motivational differences between whole blood and plasma donors already exist before their first donation experience.

    Science.gov (United States)

    Veldhuizen, Ingrid; van Dongen, Anne

    2013-08-01

    The demand for plasma products has increased rapidly. It is therefore important to understand donating behavior by plasma donors. This study investigates whether motivational differences between whole blood and plasma donors already exist at the beginning of a donor career. New donors (n = 4861) were invited to fill out a questionnaire before their first donation (response, 61%). The questionnaire assessed variables from the Theory of Planned Behavior (intention, self-efficacy, attitude, and norms), conscientiousness, and donation anxiety. Three years later it was determined who became whole blood or plasma donor. Multivariable linear regression analyses for intention were fitted separately for whole blood and plasma donors. A logistic regression analysis was executed to estimate the effect of intention at the beginning of a donor career on becoming a plasma donor. Plasma donors had a higher intention, self-efficacy, attitude, and conscientiousness and a lower anxiety than whole blood donors. In plasma and whole blood donors, both self-efficacy and cognitive attitude were positively related to intention but with different strength (plasma, β = 0.47 and β = 0.30; whole blood, β = 0.57 and β = 0.17). Having a high level of intention increased the odds of becoming a plasma donor (odds ratio, 1.33; 95% confidence interval, 1.12-1.59). Motivational differences already exist between future whole blood and plasma donors before their first donation. Although a feeling of self-efficacy is necessary for all new donors, more favorable cognitions are important for future plasma donors. Recruitment strategies for plasma donors should focus on attracting the more self-confident donors by highlighting the usefulness of plasma donation. © 2012 American Association of Blood Banks.

  11. Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

    NARCIS (Netherlands)

    de Bock, M. F. M.; Citrin, J.; Saarelma, S.; Temple, D.; Conway, N. J.; Kirk, A.; Meyer, H.; Michael, C. A.

    2012-01-01

    Edge localized modes (ELMs), that are present in most tokamak H-(high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is

  12. Mid-latitude ionospheric perturbation associated with the Spacelab-2 plasma depletion experiment at Millstone Hill

    Directory of Open Access Journals (Sweden)

    J. C. Foster

    Full Text Available Elevation scans across geomagnetic mid latitudes by the incoherent scatter radar at Millstone Hill captured the ionospheric response to the firing of the Space Shuttle Challenger OMS thrusters near the peak of the F layer on July 30, 1985. Details of the excitation of airglow and the formation of an ionospheric hole during this event have been reported in an earlier paper by Mendillo et al.. The depletion (factor ~2 near the 320 km Shuttle orbital altitude persisted for ~35 min and then recovered to near normal levels, while at 265 km the density was reduced by a factor of ~6; this significant reduction in the bottomside F-region density persisted for more than 3 hours. Total electron content in the vicinity of the hole was reduced by more than a factor of 2, and an oscillation of the F-region densities with 40-min period ensued and persisted for several hours. Plasma vertical Doppler velocity varied quasi-periodically with a ~80-min period, while magnetic field variations observed on the field line through the Shuttle-burn position exhibited a similar ~80-min periodicity. An interval of magnetic field variations at hydromagnetic frequencies (~95 s period accompanied the ionospheric perturbations on this field line. Radar observations revealed a downward phase progression of the 40-min period density enhancements of -1.12° km-1, corresponding to a 320-km vertical wavelength. An auroral-latitude geomagnetic disturbance began near the time of the Spacelab-2 experiment and was associated with the imposition of a strong southward IMF Bz across the magnetosphere. This created an additional complication in the interpretation of the active ionospheric experiment. It cannot be determined uniquely whether the ionospheric oscillations, which followed the Spacelab-2 experiment, were related to the active experiment or were the result of a propagating ionospheric disturbance (TID launched by the enhanced auroral

  13. Mid-latitude ionospheric perturbation associated with the Spacelab-2 plasma depletion experiment at Millstone Hill

    Directory of Open Access Journals (Sweden)

    J. C. Foster

    2000-01-01

    Full Text Available Elevation scans across geomagnetic mid latitudes by the incoherent scatter radar at Millstone Hill captured the ionospheric response to the firing of the Space Shuttle Challenger OMS thrusters near the peak of the F layer on July 30, 1985. Details of the excitation of airglow and the formation of an ionospheric hole during this event have been reported in an earlier paper by Mendillo et al.. The depletion (factor ~2 near the 320 km Shuttle orbital altitude persisted for ~35 min and then recovered to near normal levels, while at 265 km the density was reduced by a factor of ~6; this significant reduction in the bottomside F-region density persisted for more than 3 hours. Total electron content in the vicinity of the hole was reduced by more than a factor of 2, and an oscillation of the F-region densities with 40-min period ensued and persisted for several hours. Plasma vertical Doppler velocity varied quasi-periodically with a ~80-min period, while magnetic field variations observed on the field line through the Shuttle-burn position exhibited a similar ~80-min periodicity. An interval of magnetic field variations at hydromagnetic frequencies (~95 s period accompanied the ionospheric perturbations on this field line. Radar observations revealed a downward phase progression of the 40-min period density enhancements of -1.12° km-1, corresponding to a 320-km vertical wavelength. An auroral-latitude geomagnetic disturbance began near the time of the Spacelab-2 experiment and was associated with the imposition of a strong southward IMF Bz across the magnetosphere. This created an additional complication in the interpretation of the active ionospheric experiment. It cannot be determined uniquely whether the ionospheric oscillations, which followed the Spacelab-2 experiment, were related to the active experiment or were the result of a propagating ionospheric disturbance (TID launched by the enhanced auroral activity. The most reasonable conclusion is

  14. Haemovigilance data on the use of methylene blue virally inactivated fresh frozen plasma with the Theraflex MB-Plasma System in comparison to quarantine plasma: 11 years' experience.

    Science.gov (United States)

    Politis, C; Kavallierou, L; Hantziara, S; Parara, M; Zervou, E; Katsarou, O; Hatzitaki, M; Fountouli, P; Gioka, A; Tzioura, K; Koumarianos, S; Asariotou, M; Richardson, C

    2014-10-01

    Haemovigilance is an effective tool for identifying adverse effects of blood components. We analyse cumulative haemovigilance data in order to compare the two secured therapeutic plasmas that have been in use for more than 11 years in Greece - methylene blue-treated fresh frozen plasma (MB-FFP) and quarantine fresh frozen plasma (Q-FFP) - regarding safety and adverse events. Data from the centralised active haemovigilance system of Greece for the period 2001-2011 were used to examine the association between FFP types and adverse events. Post-transfusion information on infectious and non-infectious adverse events was analysed. Events were examined by reaction type, severity and imputability to transfusion. The incidence of adverse events was higher with Q-FFP (1:3620) than MB-FFP (1 : 24 593) by a factor of 6·79 [95% confidence interval (CI) 2·52-27·8]. Allergic adverse events were also commoner with Q-FFP (1 : 7489) than with MB-FFP (1:24 593), by a factor of 3·28 (95% CI 1·17-13·7). All adverse reactions experienced by the MB plasma recipients were considered to be mild. Haemovigilance over 11 years has demonstrated the long-term safety of MB-FFP in comparison to untreated quarantine FFP. In addition to lowering the adverse event rate, implementing the system on a national scale in at-risk countries would presumably reduce the transmission of severe viral infections including emerging infectious diseases by transfusion. © 2014 British Blood Transfusion Society.

  15. Resonant Character of Edge Plasma Parameters in Stochastic Boundary Experiments at DIII-D and TEXTOR

    Science.gov (United States)

    Schmitz, O.; Bray, B. D.; Brooks, N. H.; Evans, T. E.; Leonard, A. W.; Osborne, T. H.; West, W. P.; Fenstermacher, M. E.; Groth, M.; Lasnier, C. J.; Frerichs, H.; Lehnen, M.; Unterberg, B.; Jakubowski, M. W.; Moyer, R. A.; Watkins, J. G.

    2008-11-01

    Dependence of electron pressure pe profiles on the edge safety factor during resonant magnetic perturbations (RMPs) is analyzed and compared to heat and particle fluxes. For TEXTOR, a strong reduction of pe and an increase of target fluxes is measured when the inward penetration of the vacuum stochastic layer is maximized. For DIII-D, target heat and particle fluxes follow the 3-D perturbed separatrix due to a stochastic layer of open, perturbed field lines with a minimum penetration to ψN=0.95 in normalized poloidal flux. Experimental measurements show the toroidally spiraling structure of perturbed target plate separatrix lobes depend on q95 and that there is a clear q95 dependent reduction of ne(ψN), Te(ψN) and pe(ψN) which follows the toroidal phase of the RMP field. The measurements provide evidence for pitch resonant edge stochastisation as a mechanism leading to peeling-ballooning stabilized RMP H-modes at DIII-D.

  16. Identification of Accretion as Grain Growth Mechanism in Astrophysically Relevant Water–Ice Dusty Plasma Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Ryan S.; Chai, Kil-Byoung; Bellan, Paul M. [Applied Physics and Materials Science, Caltech, Pasadena, CA 91125 (United States)

    2017-03-01

    The grain growth process in the Caltech water–ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (i) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μ m, (ii) the major axis length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (i.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ∼0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.

  17. Observation of quasi-coherent edge fluctuations in Ohmic plasmas on National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Santanu [Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat (India); Diallo, A.; Zweben, S. J. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)

    2016-04-15

    A quasi-coherent edge density mode with frequency f{sub mode} ∼ 40 kHz is observed in Ohmic plasmas in National Spherical Torus Experiment using the gas puff imaging diagnostic. This mode is located predominantly just inside the separatrix, with a maximum fluctuation amplitude significantly higher than that of the broadband turbulence in the same frequency range. The quasi-coherent mode has a poloidal wavelength λ{sub pol} ∼ 16 cm and a poloidal phase velocity of V{sub pol} ∼ 4.9 ± 0.3 km s{sup −1} in the electron diamagnetic direction, which are similar to the characteristics expected from a linear drift-wave-like mode in the edge. This is the first observation of a quasi-coherent edge mode in an Ohmic diverted tokamak, and so may be useful for validating tokamak edge turbulence codes.

  18. Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

    Science.gov (United States)

    Gupta, Mohit; Kumara, Chamara; Nylén, Per

    2017-08-01

    Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

  19. Rayleigh-Taylor-instability evolution in colliding-plasma-jet experiments with magnetic and viscous stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Colin Stuart [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Univ. of Washington, Seattle, WA (United States)

    2015-01-15

    The Rayleigh-Taylor instability causes mixing in plasmas throughout the universe, from micron-scale plasmas in inertial confinement fusion implosions to parsec-scale supernova remnants. The evolution of this interchange instability in a plasma is influenced by the presence of viscosity and magnetic fields, both of which have the potential to stabilize short-wavelength modes. Very few experimental observations of Rayleigh-Taylor growth in plasmas with stabilizing mechanisms are reported in the literature, and those that are reported are in sub-millimeter scale plasmas that are difficult to diagnose. Experimental observations in well-characterized plasmas are important for validation of computational models used to make design predictions for inertial confinement fusion efforts. This dissertation presents observations of instability growth during the interaction between a high Mach-number, initially un-magnetized plasma jet and a stagnated, magnetized plasma. A multi-frame fast camera captures Rayleigh-Taylor-instability growth while interferometry, spectroscopy, photodiode, and magnetic probe diagnostics are employed to estimate plasma parameters in the vicinity of the collision. As the instability grows, an evolution to longer mode wavelength is observed. Comparisons of experimental data with idealized magnetohydrodynamic simulations including a physical viscosity model suggest that the observed instability evolution is consistent with both magnetic and viscous stabilization. These data provide the opportunity to benchmark computational models used in astrophysics and fusion research.

  20. Battery-powered pulsed high density inductively coupled plasma source for pre-ionization in laboratory astrophysics experiments.

    Science.gov (United States)

    Chaplin, Vernon H; Bellan, Paul M

    2015-07-01

    An electrically floating radiofrequency (RF) pre-ionization plasma source has been developed to enable neutral gas breakdown at lower pressures and to access new experimental regimes in the Caltech laboratory astrophysics experiments. The source uses a customized 13.56 MHz class D RF power amplifier that is powered by AA batteries, allowing it to safely float at 3-6 kV with the electrodes of the high voltage pulsed power experiments. The amplifier, which is capable of 3 kW output power in pulsed (<1 ms) operation, couples electrical energy to the plasma through an antenna external to the 1.1 cm radius discharge tube. By comparing the predictions of a global equilibrium discharge model with the measured scalings of plasma density with RF power input and axial magnetic field strength, we demonstrate that inductive coupling (rather than capacitive coupling or wave damping) is the dominant energy transfer mechanism. Peak ion densities exceeding 5 × 10(19) m(-3) in argon gas at 30 mTorr have been achieved with and without a background field. Installation of the pre-ionization source on a magnetohydrodynamically driven jet experiment reduced the breakdown time and jitter and allowed for the creation of hotter, faster argon plasma jets than was previously possible.

  1. Shock tube experiments on nitromethane and Promotion of chemical reactions by non-thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Seljeskog, Morten

    2002-06-01

    This dissertation was undertaken to study two different subjects both related to molecular decomposition by applying a shock tube and non-thermal plasma to decompose selected hydrocarbons. The first approach to molecular decomposition concerned thermal decomposition and oxidation of highly diluted nitromethane (NM) in a shock tube. Reflected shock tube experiments on NM decomposition, using mixtures of 0.2 to 1.5 vol% NM in nitrogen or argon were performed over the temperature range 850-1550 K and pressure range 190-900 kPa, with 46 experiments diluted in nitrogen and 44 diluted in argon. By residual error analysis of the measured decomposition profiles it was found that NM decomposition (CH{sub 3}NO{sub 2} + M {yields} CH{sub 3} + NO{sub 2} + M, where M = N{sub 2} /Ar) corresponds well to a law of first order. Arrhenius expressions corresponding to NM diluted either in N{sub 2} or in Ar were found as k{sub N2} = 10{sup 17.011} * exp(- 182.6 kJ/mole / R*T) and k{sub Ar} = 10{sup 17.574}*exp(-207 kJ/mole / R*T ) , respectively. A new reaction mechanism was then proposed, based on new experimental data for NM decomposition both in Ar and N{sub 2} and on three previously developed mechanisms. The new mechanism predicts well the decomposition of NM diluted in both N{sub 2} and Ar within the pressure and temperature range covered by the experiments. In parallel to, and following the decomposition experiments, oxidative experiments on the ignition delay times of NM/O{sub 2}/Ar mixtures were investigated over high temperature and low to high pressure ranges. These experiments were carried out with eight different mixtures of gaseous NM and oxygen diluted in argon, with pressures ranging between 44.3-600 kPa, and temperatures ranging between 842-1378 K. The oxidation experiments were divided into different categories according to the type of decomposition signals achieved. For signals with and without emission, the apparent quasi

  2. The Impact Of Lithium Wall Coatings On NSTX Discharges And The Engineering Of The Lithium Tokamak eXperiment (LTX)

    Energy Technology Data Exchange (ETDEWEB)

    R. Majeski, H. Kugel and R. Kaita

    2010-03-18

    Recent experiments on the National Spherical Torus eXperiment (NSTX) have shown the benefits of solid lithium coatings on carbon PFC's to diverted plasma performance, in both Land H- mode confinement regimes. Better particle control, with decreased inductive flux consumption, and increased electron temperature, ion temperature, energy confinement time, and DD neutron rate were observed. Successive increases in lithium coverage resulted in the complete suppression of ELM activity in H-mode discharges. A liquid lithium divertor (LLD), which will employ the porous molybdenum surface developed for the LTX shell, is being installed on NSTX for the 2010 run period, and will provide comparisons between liquid walls in the Lithium Tokamak eXperiment (LTX) and liquid divertor targets in NSTX. LTX, which recently began operations at the Princeton Plasma Physics Laboratory, is the world's first confinement experiment with full liquid metal plasma-facing components (PFCs). All materials and construction techniques in LTX are compatible with liquid lithium. LTX employs an inner, heated, stainless steel-faced liner or shell, which will be lithium-coated. In order to ensure that lithium adheres to the shell, it is designed to operate at up to 500 - 600 oC to promote wetting of the stainless by the lithium, providing the first hot wall in a tokamak to operate at reactor-relevant temperatures. The engineering of LTX will be discussed.

  3. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    van Eck, H. J. N.; Koppers, W. R.; van Rooij, G. J.; W. J. Goedheer,; Engeln, R.; D.C. Schram,; Cardozo, N. J. L.; Kleyn, A. W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial

  4. Comparison of 2D simulations of detached divertor plasmas with divertor Thomson measurements in the DIII-D tokamak

    Directory of Open Access Journals (Sweden)

    T.D. Rognlien

    2017-08-01

    Full Text Available A modeling study is reported using new 2D data from DIII-D tokamak divertor plasmas and improved 2D transport model that includes large cross-field drifts for the numerically difficult low anomalous transport regime associated with the H-mode. The data set, which spans a range of plasma densities for both forward and reverse toroidal magnetic field (Bt, is provided by divertor Thomson scattering (DTS. Measurements utilizing X-point sweeping give corresponding 2D profiles of electron temperature (Te and density (ne across both divertor legs for individual discharges. The simulations focus on the open magnetic field-line regions, though they also include a small region of closed field lines. The calculations show the same features of in/out divertor plasma asymmetries as measured in the experiment, with the normal Bt direction (ion ∇B drift toward the X-point having higher ne and lower Te in the inner divertor leg than outer. Corresponding emission data for total radiated power shows a strong inner-divertor/outer-divertor asymmetry that is reproduced by the simulations. These 2D UEDGE transport simulations are enabled for steep-gradient H-mode conditions by newly implemented algorithms to control isolated grid-scale irregularities.

  5. Fast measurements of the electron temperature and parallel heat flux in ELMy H-mode on the COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Adámek, Jiří; Seidl, Jakub; Komm, Michael; Weinzettl, Vladimír; Pánek, Radomír; Stöckel, Jan; Hron, Martin; Háček, Pavel; Imríšek, Martin; Vondráček, Petr; Horáček, Jan; Devitre, A.

    2017-01-01

    Roč. 57, č. 2 (2017), č. článku 022010. ISSN 0029-5515 R&D Projects: GA ČR(CZ) GA15-10723S; GA MŠk(CZ) LM2015045; GA MŠk(CZ) 8D15001 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : COMPASS * divertor * ELM * scrape-off layer * ball-pen probe * power decay length Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.307, year: 2016 http://iopscience.iop.org/ article /10.1088/0029-5515/57/2/022010

  6. Low- and high-mode separation of short wavelength turbulence in dithering Wendelstein 7-AS plasmas

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Saffman, M.

    2002-01-01

    measurements can be fitted with the same exponents in L- and H-mode. Correlations between the density fluctuations, the H-alpha-signal and magnetic fluctuations as measured by Mirnov coils were analyzed. Correlation calculations using 50 ms time windows (several dithering periods) with time lag steps of 100......) stellarator [H. Renner , Plasma Phys. Control. Fusion 31, 1579 (1989)]. The experimental setup and discharge properties are described. H-alpha-light observing an inner limiter was used to separate low confinement (L)- and H-mode phases of the plasma; the separated density fluctuations are characterized....... It was found that L- (H-) mode fluctuations dominate at high (low) frequencies, respectively, and that they possess well-defined and distinguishable scaling properties. Wavenumber spectra for L- and H-mode measurements are calculated and fitted by power-laws and exponential functions. The separated...

  7. An accurate Rb density measurement method for a plasma wakefield accelerator experiment using a novel Rb reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Öz, E.; Batsch, F.; Muggli, P.

    2016-09-01

    A method to accurately measure the density of Rb vapor is described. We plan on using this method for the Advanced Wakefield (AWAKE) (Assmann et al., 2014 [1]) project at CERN , which will be the world's first proton driven plasma wakefield experiment. The method is similar to the hook (Marlow, 1967 [2]) method and has been described in great detail in the work by Hill et al. (1986) [3]. In this method a cosine fit is applied to the interferogram to obtain a relative accuracy on the order of 1% for the vapor density–length product. A single-mode, fiber-based, Mach–Zenhder interferometer will be built and used near the ends of the 10 meter-long AWAKE plasma source to be able to make accurate relative density measurement between these two locations. This can then be used to infer the vapor density gradient along the AWAKE plasma source and also change it to the value desired for the plasma wakefield experiment. Here we describe the plan in detail and show preliminary results obtained using a prototype 8 cm long novel Rb vapor cell.

  8. Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

    Science.gov (United States)

    Adjei, Daniel; Ayele, Mesfin Getachew; Wachulak, Przemyslaw; Bartnik, Andrzej; Wegrzynski, Łukasz; Fiedorowicz, Henryk; Vyšín, Luděk; Wiechec, Anna; Lekki, Janusz; Kwiatek, Wojciech M.; Pina, Ladislav; Davídková, Marie; Juha, Libor

    2015-12-01

    A desk-top laser-produced plasma (LPP) source of soft X-rays (SXR) has been developed for radiobiology research. The source is based on a double-stream gas puff target, irradiated with the focused beam of a commercial Nd:YAG laser. The source has been optimized to get a maximum photon emission from LPP in the X-ray "water window" spectral wavelength range from 2.3 nm (i.e., an absorption edge of oxygen) to 4.4 nm (i.e., an absorption edge of carbon) (280-540 eV in photon energy units) by using argon gas-puff target and spectral filtering by free-standing thin foils. The present source delivers nanosecond pulses of soft X-rays at a fluence of about 4.2 × 103 photons/μm2/pulse on a sample placed inside the vacuum chamber. In this paper, the source design, radiation output characterization measurements and initial irradiation experiments are described. The source can be useful in addressing observations related to biomolecular, cellular and organisms' sensitivity to pulsed radiation in the "water window", where carbon atoms absorb X-rays more strongly than the oxygen, mostly present in water. The combination of the SXR source and the radiobiology irradiation layout, reported in this article, make possible a systematic investigation of relationships between direct and indirect action of ionizing radiation, an increase of a local dose in carbon-rich compartments of the cell (e.g., lipid membranes), an experimental estimation of a particular role of the Auger effect (in particular in carbon atoms) in the damage to biological systems, and the study of ionization/excitation-density (LET - Linear Energy Transfer) and dose-rate effects in radiobiology.

  9. Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

    Energy Technology Data Exchange (ETDEWEB)

    Adjei, Daniel, E-mail: nana.adjeidan@gmail.com [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra (Ghana); Ayele, Mesfin Getachew; Wachulak, Przemyslaw; Bartnik, Andrzej; Wegrzynski, Łukasz; Fiedorowicz, Henryk [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Vyšín, Luděk [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Wiechec, Anna; Lekki, Janusz; Kwiatek, Wojciech M. [Institute of Nuclear Physics, Polish Academy of Sciences, 152, Radzikowskiego Str., 31-342 Cracow (Poland); Pina, Ladislav [Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Davídková, Marie [Institute of Nuclear Physics, Czech Academy of Sciences, Řež (Czech Republic); Juha, Libor [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2015-12-01

    A desk-top laser-produced plasma (LPP) source of soft X-rays (SXR) has been developed for radiobiology research. The source is based on a double-stream gas puff target, irradiated with the focused beam of a commercial Nd:YAG laser. The source has been optimized to get a maximum photon emission from LPP in the X-ray “water window” spectral wavelength range from 2.3 nm (i.e., an absorption edge of oxygen) to 4.4 nm (i.e., an absorption edge of carbon) (280–540 eV in photon energy units) by using argon gas-puff target and spectral filtering by free-standing thin foils. The present source delivers nanosecond pulses of soft X-rays at a fluence of about 4.2 × 10{sup 3} photons/μm{sup 2}/pulse on a sample placed inside the vacuum chamber. In this paper, the source design, radiation output characterization measurements and initial irradiation experiments are described. The source can be useful in addressing observations related to biomolecular, cellular and organisms’ sensitivity to pulsed radiation in the “water window”, where carbon atoms absorb X-rays more strongly than the oxygen, mostly present in water. The combination of the SXR source and the radiobiology irradiation layout, reported in this article, make possible a systematic investigation of relationships between direct and indirect action of ionizing radiation, an increase of a local dose in carbon-rich compartments of the cell (e.g., lipid membranes), an experimental estimation of a particular role of the Auger effect (in particular in carbon atoms) in the damage to biological systems, and the study of ionization/excitation-density (LET – Linear Energy Transfer) and dose-rate effects in radiobiology.

  10. Isotope effects on L-H threshold and confinement in tokamak plasmas

    Science.gov (United States)

    Maggi, C. F.; Weisen, H.; Hillesheim, J. C.; Chankin, A.; Delabie, E.; Horvath, L.; Auriemma, F.; Carvalho, I. S.; Corrigan, G.; Flanagan, J.; Garzotti, L.; Keeling, D.; King, D.; Lerche, E.; Lorenzini, R.; Maslov, M.; Menmuir, S.; Saarelma, S.; Sips, A. C. C.; Solano, E. R.; Belonohy, E.; Casson, F. J.; Challis, C.; Giroud, C.; Parail, V.; Silva, C.; Valisa, M.; Contributors, JET

    2018-01-01

    The dependence of plasma transport and confinement on the main hydrogenic ion isotope mass is of fundamental importance for understanding turbulent transport and, therefore, for accurate extrapolations of confinement from present tokamak experiments, which typically use a single hydrogen isotope, to burning plasmas such as ITER, which will operate in deuterium–tritium mixtures. Knowledge of the dependence of plasma properties and edge transport barrier formation on main ion species is critical in view of the initial, low-activation phase of ITER operations in hydrogen or helium and of its implications on the subsequent operation in deuterium–tritium. The favourable scaling of global energy confinement time with isotope mass, which has been observed in many tokamak experiments, remains largely unexplained theoretically. Moreover, the mass scaling observed in experiments varies depending on the plasma edge conditions. In preparation for upcoming deuterium–tritium experiments in the JET tokamak with the ITER-like Be/W Wall (JET-ILW), a thorough experimental investigation of isotope effects in hydrogen, deuterium and tritium plasmas is being carried out, in order to provide stringent tests of plasma energy, particle and momentum transport models. Recent hydrogen and deuterium isotope experiments in JET-ILW on L-H power threshold, L-mode and H-mode confinement are reviewed and discussed in the context of past and more recent isotope experiments in tokamak plasmas, highlighting common elements as well as contrasting observations that have been reported. The experimental findings are discussed in the context of fundamental aspects of plasma transport models.

  11. Nonlinear optical polarization response and plasma generation in noble gases: Comparison of metastable-electronic-state-approach models to experiments

    Science.gov (United States)

    Bahl, Anand; Wahlstrand, Jared K.; Zahedpour, Sina; Milchberg, Howard M.; Kolesik, Miroslav

    2017-10-01

    The nonlinear polarization response and plasma generation produced by intense optical pulses, modeled by the metastable-electronic-state approach, are verified against space-and-time resolved measurements with single-shot supercontinuum spectral interferometry. This first of a kind theory-experiment comparison is done in the intensity regime typical for optical filamentation, where self-focusing and plasma generation play competing roles. Excellent agreement between the theory and experiment shows that the self-focusing nonlinearity can be approximated by a single resonant state. Moreover, we demonstrate that inclusion of the post-adiabatic corrections, previously tested only in theoretic models, provides a viable description of the ionization rate in real gases.

  12. Modeling-challenge paradigm using design of experiments for spacecraft immersed in nonstationary, between-regimes, flowing plasma

    Science.gov (United States)

    Koepke, Me; Marchand, R.

    2017-10-01

    A conducting sphere and cylinder under the conditions of nonstationary, between-regimes, flowing plasma is adopted as a test case for a modeling-challenge paradigm based on design of experiments (DOE) methodology that merges numerical simulation and testing. This model/simulation development platform facilitates a red-team/blue-team style challenge aimed at a tailored set of standard experimental conditions and measurements addressing specific questions in spacecraft-environment interactions and assessing the capability of models to describe those conditions. The goal is streamlining the Model/Simulation development process. A byproduct is an enhancement of the interrelationship between experiments in the laboratory and in space. Here, we conceptualize the advantage of the model-challenge over conventional validation in advancing whole-device modeling objectives in basic and applied plasma science.

  13. Waves in Plasma Sheaths and at Boundaries: Theory and Computer Experiments

    National Research Council Canada - National Science Library

    Birdsall, Charles

    1997-01-01

    .... There is no applied magnetic field; the plasma and waves are unmagnetized. First, a linear theory and simulation are made, to include the sheath and the pre-sheath from first principles and self-consistently...

  14. Plasma Cell Mastitis in Men: A Single-center Experience and Review of the Literature.

    Science.gov (United States)

    Palmieri, Andrea; D'Orazi, Valerio; Martino, Giovanni; Frusone, Federico; Crocetti, Daniele; Amabile, Maria Ida; Monti, Marco

    Plasma cell mastitis is an inflammatory disease of the breast parenchyma, rare in males. In the last 40 years, few cases have been described in literature. Our recent treatment of male patients affected by plasma cell mastitis raised a series of issues which led us to carry out a critical review of the literature. Plasma cell mastitis is often not well defined and is difficult to assess by clinical examination and radiological investigation alone. An understanding of the pathogenesis and the mechanisms behind plasma cell mastitis may help improve the diagnostic and therapeutic course of the disease, leading to a more targeted and less invasive treatment. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  15. Developing the science and technology for the Material Plasma Exposure eXperiment

    Science.gov (United States)

    Rapp, J.; Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Caughman, J. B. O.; Diem, S. J.; Goulding, R. H.; Isler, R. C.; Lumsdaine, A.; Beers, C. J.; Bjorholm, T.; Bradley, C.; Canik, J. M.; Donovan, D.; Duckworth, R. C.; Ellis, R. J.; Graves, V.; Giuliano, D.; Green, D. L.; Hillis, D. L.; Howard, R. H.; Kafle, N.; Katoh, Y.; Lasa, A.; Lessard, T.; Martin, E. H.; Meitner, S. J.; Luo, G.-N.; McGinnis, W. D.; Owen, L. W.; Ray, H. B.; Shaw, G. C.; Showers, M.; Varma, V.; the MPEX Team

    2017-11-01

    Linear plasma generators are cost effective facilities to simulate divertor plasma conditions of present and future fusion reactors. They are used to address important R&D gaps in the science of plasma material interactions and towards viable plasma facing components for fusion reactors. Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The steady-state linear plasma device MPEX will address this regime with electron temperatures of 1-10 eV and electron densities of 1021{\\text{}}-1020 m-3 . The resulting heat fluxes are about 10 MW m-2 . MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with electron Bernstein wave (EBW) heating and ion cyclotron resonance heating with a total installed power of 800 kW. The linear device Proto-MPEX, forerunner of MPEX consisting of 12 water-cooled copper coils, has been operational since May 2014. Its helicon antenna (100 kW, 13.56 MHz) and EC heating systems (200 kW, 28 GHz) have been commissioned and 14 MW m-2 was delivered on target. Furthermore, electron temperatures of about 20 eV have been achieved in combined helicon and ECH heating schemes at low electron densities. Overdense heating with EBW was achieved at low heating powers. The operational space of the density production by the helicon antenna was pushed up to 1.1 × 1020 m-3 at high magnetic fields of 1.0 T at the target. The experimental results from Proto-MPEX will be used for code validation to enable predictions of the source and heating performance for MPEX. MPEX, in its last phase, will be capable to expose neutron-irradiated samples. In this concept, targets will be irradiated in ORNL’s High Flux Isotope Reactor and then subsequently exposed to fusion reactor relevant plasmas in MPEX.

  16. Simulations of collisionless counter-propagating plasma flows in support of two-wire implosion experiments

    Science.gov (United States)

    Caplinger, James; Sotnikov, Vladimir; Hamilton, Andrew; Plasma Physics Sensors Laboratory Team

    2017-10-01

    One of the simplest configurations leading to colliding plasma flows is created by driving strong currents through a pair of parallel wires. The azimuthal magnetic fields generated around each wire, and the Ohmic current dissipation and heating occurring upon wire evaporation, launches powerful radial outflows of magnetized plasmas. Upon colliding they form a flow pattern suggestive of magnetic field reconnection, and the development of various plasma instabilities. In the current effort, we analyzed collision of two high-temperature precursor light ion plasma flows via PIC (Particle-In-Cell) simulations using LSP. The aim is to demonstrate the appearance of an electric field parallel to the direction of a plasma flow. This field appears in colliding plasma flows due to the charge separation and is associated with the Buneman instability. It is responsible for the creation of ExB drift of electrons. Next, an interaction between drifting electrons and unmagnetized ions, moving parallel to them, lead to excitation of a modified Buneman instability in the frequency range close to the Lower-Hybrid frequency. Simulation results will allow us to identify the characteristics of nonlinear density fluctuations that appear in the process of such an interaction. This work was supported by the Air Force Office of Scientific Research.

  17. Shuttle-era experiments in the area of plasma flow interactions with bodies in space

    Science.gov (United States)

    Samir, U.; Stone, N. H.

    1980-01-01

    A new experimental approach is discussed that can be adopted for studies in the area of plasma flow interactions with bodies in space. The potential use of the Space Shuttle/Orbiter as a near-earth plasma laboratory for studies in space plasma physics and particularly in solar system plasmas is discussed. This new experimental approach holds great promise for studies in the supersonic and sub-Alfvenic flow regime which has applications to the motion of natural satellites around their mother planets in the solar-system (e.g., the satellite Io around the planet Jupiter). A well conceived experimental and theoretical program can lead to a better physical understanding regarding the validity and range of applicability of using gasdynamic, kinetic, and fluid approaches in describing collisionless plasma flow interactions with bodies in a variety of flow regimes. In addition to the above scientific aspects of the program, significant technological advances can be achieved regarding the interaction of space probes in planetary atmospheres/ionospheres and the reliability of using various plasma diagnostic devices on board spacecraft and large space platforms.

  18. ICRF heating experiments on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Y.; Bonoli, P.T.; Hubbard, A.; Mazurenko, A.; OShea, P.J.; Porkolab, M.; Reardon, J.; Wukitch, S.; Boivin, R. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Bombarda, F. [Associazione EURATOM-ENEA sulla Fusione, Frascati 00044 (Italy); Fiore, C.; Garnier, D.; Goetz, J.A.; Granetz, R.; Greenwald, M. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Hartmann, D. [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Hutchinson, I.H.; Irby, J.; LaBombard, B.; Lipschultz, B.; Marmar, E. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); May, M. [Department of Physics, The John Hopkins University, Baltimore, Maryland 21218 (United States); Rice, J.; Rost, J.C.; Schachter, J.; Snipes, J.A.; Stek, P.; Terry, J. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Welch, B. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States); Wolfe, S. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

    1997-04-01

    Routine high power operation of the ICRF heating system (up to 3.5 MW at 80 MHz) has enabled studies of enhanced confinement modes as well as high heat flux divertor experiments in the Alcator C-Mod tokamak with toroidal magnetic fields of up to 8 T. H-mode was routinely observed when the edge temperature exceeded a threshold value. Boronization has reduced the radiated power to approximately 30{percent} of the input power, which had little effect on confinement of L-mode plasmas, but had a large impact on the performance of H-mode plasmas. It has become possible to achieve quasi-steady-state H-modes with H{approx_equal}2 and {beta}{sub N}{approx_equal}1.5 simultaneously with P{sub rad}/P{sub in}{approx_equal}0.3 and Z{sub eff}{approx_equal}1.5. PEP mode can be obtained with central ICRF heating combined with core fuelling by pellet injection. Because of the high central density, ion heating becomes the dominant heating channel during PEP mode. For direct electron heating schemes, such as heating by the mode converted ion Bernstein wave, the electron heating profile can be measured using the break-in-slope analysis of the electron temperature at rf power transitions. Mode conversion heating produced highly localized electron heating profiles, both on-axis and off-axis. Recent developments in full-wave codes have improved the agreement between the observed experimental results and the theoretically calculated power absorption profiles and power partition between ions and electrons. {copyright} {ital 1997 American Institute of Physics.}

  19. A Benchmark Experiment for Photoionized Plasma Emission from Accretion-Powered X-ray Sources

    Science.gov (United States)

    Loisel, G.; Bailey, J.; Nagayama, T.; Hansen, S.; Rochau, G.; Liedahl, D.; Fontes, C.; Kallman, T.; Mancini, R.

    2017-10-01

    Accretion-powered emission from X-ray binaries or black-hole accretion in Active Galactic Nuclei is a powerful diagnostic for their behavior and structure. Interpretation of x-ray emission from these objects requires a spectral synthesis model for photoionized plasma. Models must predict the photoionized charge state distribution, the photon emission processes, and the radiation transport influence on the observed emission. At the Z facility, we have measured simultaneously emission and absorption from a photoionized silicon plasma suitable to benchmark photoionization and spectrum formation models with +/-5% reproducibility and E/dE >2500 spectral resolution. Plasma density, temperature, and charge state distribution are determined with absorption spectroscopy. Self-emission measured at adjustable column densities tests radiation transport effects. Observation of 14 transitions in He-like silicon will help understand population mechanisms in a photoionized plasma. First observation of radiative recombination continuum in a photoionized plasma will be presented. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.

  20. Plans and Progress of Electrode Biased Plasmas in the Magnetic Reconnection Experiment

    Science.gov (United States)

    Martin, E. H.; Gerhardt, S. P.; Yamada, M.; Ji, H.; Ren, Y.; Dorfman, S.; Torreblanca, H.

    2006-10-01

    Compact Toroid (CT) plasmas such as Spheromaks are known to exhibit a global instability known as the tilt mode, where the magnetic moment of the CT tilts to align itself with the external magnetic field, as well as other non-rigid body instabilities. Possible tilt stabilizing mechanisms for these instabilities include external field shaping, nearby passive stabilizers, and plasma rotation. The proposed research focuses on reducing the growth of the tilt instability by introducing toroidal rotation in spheromaks formed in MRX. Rotation is introduced by the use of interior and exterior electrodes; the result is a Jbias x Binternal torque on the CT plasma which in turn leads to toroidal rotation of the CT plasma. In order to power the bias electrode a 450 V 8800 μF capacitor bank capable of delivering up to 450 amperes was constructed along with the required control and triggering circuitry. Solid state switches allow for fast turn on and turn off times of Jbias. The bias current and the voltage drop across the electrodes are measured using a current shunt and voltage divider respectively, and the resulting flow is measured with a Mach probe. Internal arrays of magnetic probes and optical diagnostics will be used to parameterize the performance of the CT plasma during bias. Construction and testing of all necessary components and diagnostics is complete; preliminary results will be presented.

  1. Progress On The Thomson Scattering Diagnostic For The Helicon Plasma Experiment (HPX)

    Science.gov (United States)

    Green, A.; Emami, T.; Davies, R.; Frank, J.; Hopson, J.; Karama, J.; James, R. W.; Hopson, J.; Paolino, R. N.; Sandri, E.; Turk, J.; Wicke, M.; Cgapl Team

    2017-10-01

    A high-performance spectrometer utilizing volume-phase-holographic (VPH) grating and a charge coupled device (CCD) camera with a range of 380-1090 nm and resolution of 1024x1024 has been assembled on HPX at the Coast Guard Academy Plasma Laboratory (CGAPL). This spectrometer will collect doppler shifted photons, emitted from the plasma by the first harmonic (1064 nm) of a 2.5 J Nd:YAG laser. Direct measurements of the plasma's temperature and density will be determined using HPX's Thomson Scattering (TS) single spatial point diagnostic system. A zero order half wave plate rotates the polarization of the second harmonic TS laser beam when operating at a wavelength of 532 nm. A linear actuated periscope has been constructed to remotely redirect the beam so that 532 and 1064 nm wavelengths can both be used. TS has the capability of determining plasma properties on short time scales and will be used to create a robust picture of the internal plasma parameters. Operating at both 532 and 1064 nm results in a self-consistent measurement and better use our existing spectrometer and soon to be constructed polychrometer. A prototype spectrometer has been constructed to explore the Andor CCD camera's resolution and sensitivity. The current status of the diagnostic development, spectrometer, and collection optics system will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY17.

  2. Microscopic properties of xenon plasmas for density and temperature regimes of laboratory astrophysics experiments on radiative shocks.

    Science.gov (United States)

    Rodríguez, R; Espinosa, G; Gil, J M; Stehlé, C; Suzuki-Vidal, F; Rubiano, J G; Martel, P; Mínguez, E

    2015-05-01

    This work is divided into two parts. In the first one, a study of radiative properties (such as monochromatic and the Rosseland and Planck mean opacities, monochromatic emissivities, and radiative power loss) and of the average ionization and charge state distribution of xenon plasmas in a range of plasma conditions of interest in laboratory astrophysics and extreme ultraviolet lithography is performed. We have made a particular emphasis in the analysis of the validity of the assumption of local thermodynamic equilibrium and the influence of the atomic description in the calculation of the radiative properties. Using the results obtained in this study, in the second part of the work we have analyzed a radiative shock that propagated in xenon generated in an experiment carried out at the Prague Asterix Laser System. In particular, we have addressed the effect of plasma self-absorption in the radiative precursor, the influence of the radiation emitted from the shocked shell and the plasma self-emission in the radiative precursor, the cooling time in the cooling layer, and the possibility of thermal instabilities in the postshock region.

  3. Overview of C-2 field-reversed configuration experiment plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Gota, H., E-mail: hgota@trialphaenergy.com; Thompson, M. C.; Tuszewski, M.; Binderbauer, M. W. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2014-11-15

    A comprehensive diagnostic suite for field-reversed configuration (FRC) plasmas has been developed and installed on the C-2 device at Tri Alpha Energy to investigate the dynamics of FRC formation as well as to understand key FRC physics properties, e.g., confinement and stability, throughout a discharge. C-2 is a unique, large compact-toroid merging device that produces FRC plasmas partially sustained for up to ∼5 ms by neutral-beam (NB) injection and end-on plasma-guns for stability control. Fundamental C-2 FRC properties are diagnosed by magnetics, interferometry, Thomson scattering, spectroscopy, bolometry, reflectometry, and NB-related fast-ion/neutral diagnostics. These diagnostics (totaling >50 systems) are essential to support the primary goal of developing a deep understanding of NB-driven FRCs.

  4. Overview of C-2 field-reversed configuration experiment plasma diagnostics.

    Science.gov (United States)

    Gota, H; Thompson, M C; Tuszewski, M; Binderbauer, M W

    2014-11-01

    A comprehensive diagnostic suite for field-reversed configuration (FRC) plasmas has been developed and installed on the C-2 device at Tri Alpha Energy to investigate the dynamics of FRC formation as well as to understand key FRC physics properties, e.g., confinement and stability, throughout a discharge. C-2 is a unique, large compact-toroid merging device that produces FRC plasmas partially sustained for up to ∼5 ms by neutral-beam (NB) injection and end-on plasma-guns for stability control. Fundamental C-2 FRC properties are diagnosed by magnetics, interferometry, Thomson scattering, spectroscopy, bolometry, reflectometry, and NB-related fast-ion/neutral diagnostics. These diagnostics (totaling >50 systems) are essential to support the primary goal of developing a deep understanding of NB-driven FRCs.

  5. Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

    Czech Academy of Sciences Publication Activity Database

    Adjei, D.; Ayele, M. G.; Wachulak, P.; Bartnik, A.; Wegrzynski, L.; Fiedorowicz, H.; Vyšín, Luděk; Wiechec, A.; Lekki, J.; Kwiatek, W. M.; Pina, L.; Davídková, Marie; Juha, Libor

    2015-01-01

    Roč. 364, Dec (2015), s. 27-32 ISSN 0168-583X R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GA13-28721S EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Institutional support: RVO:68378271 ; RVO:61389005 Keywords : laser-produced plasma * soft X-rays * radiobiology * gas puff target * water window Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.389, year: 2015

  6. The Skylab barium plasma injection experiments. II - Evidence for a double layer

    Science.gov (United States)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Davis, T. N.; Peek, H. M.

    1976-01-01

    Television observations of a barium-plasma flux tube extending from near 4500 km to near 10,000 km during a magnetic substorm and dawn-sector auroral display indicated several interesting anomalous events. Beyond 5500 km, there was a rapid increase in brightness accompanied by flux-tube splitting and diffusion, leaving behind a truncated single flux tube. From the orientation of the flux tube compared with theoretical field models, the presence of a substantial field-aligned current sheet is deduced. A suggested explanation of these phenomena is given in terms of a plasma potential double layer.

  7. Enhanced understanding of the MHD dynamics and ELM control experiments in KSTAR

    Science.gov (United States)

    Park, Hyeon K.

    2013-10-01

    In KSTAR, H-mode discharges have been achieved reliably at toroidal fields from 1.4 to 3.5 T with a heating power of ~ 5 MW. Using real-time plasma shape control the flattop time in H-mode has been extended to over ~ 16 s at 600 kA in the 2012 campaign and the extended plasma operation boundary has surpassed the n = 1 no-wall limit with βN /li up to 4.1. In order to achieve a high beta steady state operation in KSTAR, establishment of predictive MHD simulation and first-principle-based control of the harmful MHD are the first steps. Visualization of MHD dynamics via a 2-D Electron Cyclotron Emission Imaging (ECEI) has significantly enhanced the level of understanding of the MHD dynamics. Following the first 2-D ELM measurements in H-mode plasmas in KSTAR the measured 2-D ELM images were compared with synthetic images from the BOUT + + code. The physics of ELMs is characterized based on a wide range of measured mode numbers (n, m) local magnetic shear and pressure gradients. The observed ELM dynamics during control experiments have been enlightening and consistent with the stability models. Near the q ~ 2 surface, the island width and Δ' of the m = 2 tearing mode have been verified through the modified Rutherford model based on the 2-D images. With the aid of a second (toroidally separated) ECEI system installed in the 2012 KSTAR campaign, a 3-D reconstruction of the MHD instabilities has allowed further validation of the computed magnetic field pitch angles, rotation speeds, and toroidal asymmetries of the MHDs Work supported by NRF of Korea under contract No. 20120005920 and the U.S. DoE under contract No. DE-FG-02-99ER54531.

  8. Fabrication and testing of gas-filled targets for large-scale plasma experiments on nova

    Energy Technology Data Exchange (ETDEWEB)

    Stone, G.F.; Rivers, C.J.; Spragge, M.R.; Wallace, R.J.

    1996-06-01

    The proposed next-generation ICF facility, the National Ignition Facility (NIF) is designed to produce energy gain from x-ray heated {open_quotes}indirect-drive{close_quotes} fuel capsules. For indirect-drive targets, laser light heats the inside of the Au hohlraum wall and produces x rays which in turn heat and implode the capsule to produce fusion conditions in the fuel. Unlike Nova targets, in NIF-scale targets laser light will propagate through several millimeters of gas, producing a plasma, before impinging upon the Au hohlraum wall. The purpose of the gas-produced plasma is to provide sufficient pressure to keep the radiating Au surface from expanding excessively into the hohlraum cavity. Excessive expansion of the Au wall interacts with the laser pulse and degrades the drive symmetry of the capsule implosion. The authors have begun an experimental campaign on the Nova laser to study the effect of hohlraum gas on both laser-plasma interaction and implosion symmetry. In their current NIF target design, the calculated plasma electron temperature is T{sub e} {approx} 3 keV and the electron density is N{sub e} {approx} 10{sup 21}cm{sup {minus}3}.

  9. Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sørensen, O. H.; Mygind, Jesper

    1978-01-01

    as the temperature is decreased from Tc. We used three different schemes for observation of the plasma oscillations: (a) second-harmonic generation (excitation at ∼ 4.5 GHz, fp∼4.5 GHz); (b) mixing (excitations at ∼ 9 and ∼ 18 GHz, fp∼9 GHz); (c) parametric half-harmonic oscillation (excitation at ∼ 18 GHz, fp∼9 GHz...

  10. Pilot Experience with an External Quality Assurance Scheme for Acylcarnitines in Plasma/Serum

    NARCIS (Netherlands)

    Sala, P Ruiz; Ruijter, G; Acquaviva, C; Chabli, A; de Sain-van der Velden, M G M; Garcia-Villoria, J; Heiner-Fokkema, M R; Jeannesson-Thivisol, E; Leckstrom, K; Franzson, L; Lynes, G; Olesen, J; Onkenhout, W; Petrou, P; Drousiotou, A; Ribes, A; Vianey-Saban, C; Merinero, B

    2016-01-01

    The analysis of acylcarnitines (AC) in plasma/serum is established as a useful test for the biochemical diagnosis and the monitoring of treatment of organic acidurias and fatty acid oxidation defects. External quality assurance (EQA) for qualitative and quantitative AC is offered by ERNDIM and CDC

  11. Large-Scale Mini-Magnetosphere Plasma Propulsion (M2P2) Experiments

    Science.gov (United States)

    Winglee, R. M.; Slough, J.; Ziemba, T.; Euripides, P.; Adrian, M. L.; Gallagher, D.; Craven, P.; Tomlinson, W.; Cravens, J.; Burch, J.; hide

    2001-01-01

    Mini-Magnetosphere Plasma Propulsion (M2P2) is an innovative plasma propulsion system that has the potential to propel spacecraft at unprecedented speeds of 50 to 80 km per second with a low-power requirement of approx. 1 kW per 100 kg of payload and approx. 1 kg of neutral gas [fuel] consumption per day of acceleration. Acceleration periods from several days to a few months are envisioned. High specific impulse and efficiency are achieved through coupling of the spacecraft to the 400 km per second solar wind through an artificial magnetosphere. The mini-magnetosphere or inflated magnetic bubble is produced by the injection of cold dense plasma into a spacecraft-generated magnetic field envelope. Magnetic bubble inflation is driven by electromagnetic processes thereby avoiding the material and deployment problems faced by mechanical solar sail designs, Here, we present the theoretical design of M2P2 as well as initial results from experimental testing of an M2P2 prototype demonstrating: 1) inflation of the dipole magnetic field geometry through the internal injection of cold plasma; and 2) deflection of and artificial solar wind by the prototype M2P2 system. In addition, we present plans for direct laboratory measurement of thrust imparted to a prototype M2P2 by an artificial solar wind during the summer of 2001.

  12. Laser-Plasma Interaction Experiments in Gas-Filled Hohlraums at the LIL Facility

    Science.gov (United States)

    Masson-Laborde, Paul-Edouard; Loiseau, Pascal; Casanova, Michel; Rousseaux, Christophe; Teychenne, Denis; Laffite, Stephane; Huser, Gael

    2009-11-01

    The first laser-plasma interaction campaign conducted at the LIL facility, using gas-filled hohlraums, ended in spring 09. Two different gas-filled hohlraums have been designed in order to mimic plasma conditions expected along two particular beam paths in ignition hohlraums. The targets consist of 3- or 4-millimeters long, 1 atm neo-pentane gas-filled gold hohlraums. The LIL quadruplet is aligned with the hohlraum's axis and delivers a 6-ns long pulse with 15 kJ at 3φ. Optical smoothing is achieved by longitudinal dispersion and a phase plate giving a near 10^15 W/cm^2 mean intensity on the focal spot at maximum power. Plasma conditions from hydrodynamic calculations allow to calcule SBS and SRS linear gain with the PIRANAH code. The calculated spectra are compared to experimental results. We use the paraxial code HERA to investigate the propagation of the LIL quad. Finally, 1D and 2D PIC simulations based on the plasma conditions of the cavity will be discussed in order to understand experimental SRS spectrum.

  13. Universality in scrape-off layer plasma fluctuations: Comparison of experiment to numerical simulations

    Science.gov (United States)

    Kube, Ralph; Garcia, Odd Erik; Theodorsen, Audun; Brunner, Dan; Labombard, Brian; Terry, James; Wiesenberger, Matthias

    2017-10-01

    Particle density time series, sampled in the outboard mid-plane scrape-off layer, are interspersed by large amplitude bursts due to radial propagation of plasma blobs. GPI and Langmuir probe time series measured in the Alcator C-Mod tokamak suggest that conditionally averaged wave forms of large amplitude bursts are well described by a double exponential function. Furthermore remains the ratio of the rise and fall e-folding time of the conditionally averaged wave form constant over a range of line-averaged plasma densities. In this contribution we compare this finding to results from numerical simulations. A two-dimensional drift-fluid model has been used to simulate the propagation of seeded plasma blobs in scrape-off layer plasmas for various initial amplitudes and cross-field sizes. Time traces of the particle density, sampled at a single point, are compared to the conditionally averaged waveform of the experimental data time series. The results are interpreted in the framework of a stochastic model which relates the statistical properties of the SOL fluctuations to the profile scale length.

  14. Analysis of conductive target influence in plasma jet experiments through helium metastable and electric field measurements

    Science.gov (United States)

    Darny, T.; Pouvesle, J.-M.; Puech, V.; Douat, C.; Dozias, S.; Robert, Eric

    2017-04-01

    The use of cold atmospheric pressure plasma jets for in vivo treatments implies most of the time plasma interaction with conductive targets. The effect of conductive target contact on the discharge behavior is studied here for a grounded metallic target and compared to the free jet configuration. In this work, realized with a plasma gun, we measured helium metastable HeM (23S1) concentration (by laser absorption spectroscopy) and electric field (EF) longitudinal and radial components (by electro-optic probe). Both diagnostics were temporally and spatially resolved. Mechanisms after ionization front impact on the target surface have been identified. The remnant conductive ionized channel behind the ionization front electrically transiently connects the inner high voltage electrode to the target. Due to impedance mismatching between the ionized channel and the target, a secondary ionization front is initiated and rapidly propagates from the target surface to the inner electrode through this ionized channel. This leads to a greatly enhanced HeM production inside the plasma plume and the capillary. Forward and reverse dynamics occur with further multi reflections of more or less damped ionization fronts between the inner electrode and the target as long as the ionized channel is persisting. This phenomenon is very sensitive to parameters such as target distance and ionized channel conductivity affecting electrical coupling between these two and evidenced using positive or negative voltage polarity and nitrogen admixture. In typical operating conditions for the plasma gun used in this work, it has been found that after the secondary ionization front propagation, when the ionized channel is conductive enough, a glow like discharge occurs with strong conduction current. HeM production and all species excitation, especially reactive ones, are then driven by high voltage pulse evolution. The control of forward and reverse dynamics, impacting on the production of the glow

  15. Determination of Total Arsenic and Speciation in Apple Juice by Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry: An Experiment for the Analytical Chemistry Laboratory

    Science.gov (United States)

    He, Ping; Colon, Luis A.; Aga, Diana S.

    2016-01-01

    A two-part laboratory experiment was designed for upper-level analytical chemistry students to provide hands-on experience in the use of high performance liquid chromatography (HPLC) for separation and inductively coupled plasma mass spectrometry (ICP-MS) for detection. In the first part of the experiment, the students analyze total arsenic in…

  16. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1976-01-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

  17. Observations at the planet Mercury by the plasma electron experiment - Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1977-01-01

    Two nightside encounters with Mercury's magnetosphere by Mariner 10 revealed bow shock and magnetosheath signatures in the plasma electron data that are entirely consistent with the geometry expected for an interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance between the planet's center and the solar wind stagnation point is 1.4 plus or minus 0.1 R sub M. Both diffuse and sharp shock crossings were observed on the two magnetosphere encounters.

  18. Computational modeling of magentically driven liner-on-plasma fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Sheehey, P.T.; Faehl, R.J.; Kirkpatrick, R.C.; Lindemuth, I.R.

    1996-12-31

    Magnetized Target Fusion (MTF) is an approach to controlled fusion which potentially avoids the difficulties of the traditional magnetic and inertial confinement approaches. It appears possible to investigate the critical issues for MTF at low cost, relative to traditional fusion programs, utilizing pulsed power drivers much less expensive than ICF drivers, and plasma configurations much less expensive than those needed for full magnetic confinement. Computational and experimental research into MTF is proceeding at Los Alamos, VNIIEF, and other laboratories.

  19. Long conduction time plasma opening switch experiments at Sandia National Labs

    Science.gov (United States)

    Savage, M. E.; Simpson, W. W.; Cooper, G. W.; Usher, M. A.

    1992-01-01

    Sandia National Labs has undertaken an ambitious program to reduce the size and cost of large pulsed power drivers. The program basis is inductive energy storage and Plasma Opening Switches (POS). Inductive energy storage has well known advantages, including increased efficiency and reduced stress on the vacuum interface. The Sandia approach is to retain the reliable and efficient Marx generator and the temporal pulse compression of the water dielectric capacitor. A triggered closing switch, developed at Sandia, transfers the capacitor charge into the energy storage inductor. This approach has several advantages, including relaxed requirements on Marx jitter and inductance, and must faster current risetime in the energy storage inductor. The POS itself is the key to the Sandia program. The switch design uses an auxiliary magnetic field to inject the plasma and hold it in place during conduction. After opening begins, the self magnetic field of the power pulse pushes on the plasma to increase the opened gap. We use magnetic pressure because we desire POS gaps of several cm. Erosion POS devices typically open much less than that. Improved opening allows more efficient energy transfer to loads.

  20. Enhancement of the life of refractories through the operational experience of plasma torch melter

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Young Pyo [Technology Institute, Korea Radioactive waste Agency (KORAD), Daejeon (Korea, Republic of); Choi, Jaang Young [Chungnam National University, Daejeon (Korea, Republic of)

    2016-06-15

    The properties of wastes for melting need to be considered to minimize the maintenance of refractory and to discharge the molten slags smoothly from a plasma torch melter. When the nonflammable wastes from nuclear facilities such as concrete debris, glass, sand, etc., are melted, they become acid slags with low basicity since the chemical composition has much more acid oxides than basic oxides. A molten slag does not have good characteristics of discharge and is mainly responsible for the refractory erosion due to its low liquidity. In case of a stationary plasma torch melter with a slant tapping port on the wall, a fixed amount of molten slags remains inside of tapping hole as well as the melter inside after tapping out. Nonmetallic slags keep the temperature higher than melting point of metal because metallic slags located on the bottom of melter by specific gravity difference are simultaneously melted when dual mode plasma torch operates in transferred mode. In order to minimize the refractory erosion, the compatible refractories are selected considering the temperature inside the melter and the melting behavior of slags whether to contact or noncontact with molten slags. An acidic refractory shall not be installed in adjacent to a basic refractory for the resistibility against corrosion.

  1. Properties of the edge plasma in the rebuilt Extrap-T2R reversed field pinch experiment

    Science.gov (United States)

    Vianello, N.; Spolaore, M.; Serianni, G.; Bergsåker, H.; Antoni, V.; Drake, J. R.

    2002-12-01

    The edge region of the rebuilt Extrap-T2R reversed field pinch experiment has been investigated using Langmuir probes. Radial profiles of main plasma parameters are obtained and compared with those of the previous device Extrap-T2. The spontaneous setting up of a double shear layer of E×B toroidal velocity is confirmed. The particle flux induced by electrostatic fluctuations is calculated and the resulting effective diffusion coefficient is consistent with the Bohm estimate. A close relationship between electrostatic fluctuations at the edge and non-linear coupling of MHD modes in the core is found.

  2. Width of turbulent SOL in circular plasmas: A theoretical model validated on experiments in Tore Supra tokamak

    Directory of Open Access Journals (Sweden)

    N. Fedorczak

    2017-08-01

    Full Text Available The relation between turbulent transport and scrape off layer width is investigated in circular plasmas toroidally limited on the inner wall. A broad set of experimental observations collected in the Tore Supra scrape off layer is detailed and compared to turbulent interchange models. Blob E × B drift velocities measured in experiments agree reasonably well with an analytical model derived for isolated blobs. Based on a time averaged particle flux balance, it is also shown that the SOL width depends on both the blob drift velocity and a blob intermittency parameter, which is so far not predicted by isolated blob models. A set of 2D isothermal turbulence simulations are used to derive a power law regression of the density width function of global control parameters. Quantitative agreement is found between this regression and experimental density widths measured in Tore Supra, over a large set of plasma conditions. The sensitivity to control parameters (major radius, safety factor and normalized Larmor radius is roughly explained by the sensitivity of the blob velocity model. The predictions are also extended to power decay length in limited plasma configurations. For ITER start-up phases, the predicted power decay length fall in the range of extrapolations based on multi-machine regressions.

  3. Involvement of activated leukocytes in the regulation of plasma levels of acute phase proteins in microgravity simulation experiments

    Science.gov (United States)

    Larina, Olga; Bekker, Anna; Turin-Kuzmin, Alexey

    2016-07-01

    Earth-based studies of microgravity effects showed the induction of the mechanisms of acute phase reaction (APR). APR comprises the transition of stress-sensitive protein kinases of macrophages and other responsive cells into the active state and the phosphorylation of transcription factors which in turn stimulate the production of acute-phase reaction cytokines. Leukocyte activation is accompanied by the acceleration of the formation of oxygen radicals which can serve a functional indice of leukocyte cell state. The series of events at acute phase response result in selective changes in the synthesis of a number of secretory blood proteins (acute phase proteins, APPs) in liver cells thus contributing the recovery of homeostasis state in the organism. Earlier experiment with head-down tilt showed the increase in plasma concentrations of two cytokine mediators of acute phase response, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) being the outcome of the activation of producer cells, foremost, leukocytes. In experiment with 4-day dry immersion chemiluminescent (ChL) reply of the whole blood samples to a test stimulus were studied along with the measurements of plasma levels of APPs, namely, alpha1-antitrypsin (alpha1-AT), alpha1-acid glycoprotein (alpha1-AGP), alpha2-macroglobulin (alpha2-M), ceruloplasmin (Cer), haptoglobin (Hp), C3-complement component (C3), C-reactive protein (CRP). Eight individuals aged 21.2 ± 3.2 years were the test subjects in the investigation. Protein studies showed a noticeable increase in the mean plasma levels of all APPs measured in experiment thus producing the evidence of the activation of acute phase response mechanisms while individual patterns revealed variability during the immersion period. The overall trends were similar to these in the previous immersion series. The augment in the strength of signal in stimulated light emission tests was higher after 1- and 2-day of immersion exposure than before the

  4. Argon/UF6 plasma experiments: UF6 regeneration and product analysis

    Science.gov (United States)

    Roman, W. C.

    1980-01-01

    An experimental and analytical investigation was conducted to aid in developing some of the technology necessary for designing a self-critical fissioning uranium plasma core reactors (PCR). This technology is applicable to gaseous uranium hexafluoride nuclear-pumped laser systems. The principal equipment used included 1.2 MW RF induction heater, a d.c. plasma torch, a uranium tetrafluoride feeder system, and batch-type fluorine/UF6 regeneration systems. Overall objectives were to continue to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure, gaseous UF6; and to continue development of complementary diagnostic instrumentation and measurement techniques to characterize the effluent exhaust gases and residue deposited on the test chamber and exhaust system components. Specific objectives include: a development of a batch-type UF6 regeneration system employing pure high-temperature fluorine; development of a ruggedized time-of-flight mass spectrometer and associated data acquisition system capable of making on-line concentration measurements of the volatile effluent exhaust gas species in a high RF environment and corrosive environment of UF6 and related halide compounds.

  5. Determination of plasma sheath current distributions by comparison of Zeeman spectroscopy with B-dot measurements in laser ablation Z-pinch experiments

    Science.gov (United States)

    Dutra, Eric; Presura, Radu; Angermeier, William; Mancini, Roberto; Covington, Aaron

    2017-10-01

    In plasma pinch experiments, measurements of current distributions and losses across the anode-cathode (A-K) gap are needed to ensure uniform and repeatable implosions. Traditional B-dots measure current a considerable distance away from the plasma source and provide little detailed information on the current distribution across the plasma sheath near the pinch. In the experiments presented here, visible spectroscopic techniques were used to measure magnetically induced Zeeman splitting. Ionic plasma species were chosen such that the Zeeman splitting of different fine structure doublets split non-uniformly with increasing magnetic field strength in the plasma. This differential splitting enables measurements of non-directional B-field strengths in the plasma across a wide range of conditions. More specifically, the optical emission of Al III, C IV, and O VI doublets, 2P3/2 to 2S1/2 and 2P1/2 to 2S1/2 transitions were measured and used to determine the Zeeman broadening. We have applied this technique to diagnose time- and space-resolved B-field strengths in laser ablation Z-pinch experiments (LAZE). Experiments were conducted at the Nevada Terawatt Facility (NTF) using the TW-class Leopard laser and the 1 MA Zebra Z-pinch. The currents inferred from Zeeman spectroscopy measurements were compared to those determined from the B-dot diagnostics. DOE/NV/25946 ''3272.

  6. Core Fueling and Edge Particle Flux Analysis in Ohmically and Auxiliary Heated NSTX Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    V.A. Soukhanovskii; R. Maingi; R. Raman; H.W. Kugel; B.P. LeBlanc; L. Roquemore; C.H. Skinner; NSTX Research Team

    2002-06-12

    The Boundary Physics program of the National Spherical Torus Experiment (NSTX) is focusing on optimization of the edge power and particle flows in b * 25% L- and H-mode plasmas of t {approx} 0.8 s duration heated by up to 6 MW of high harmonic fast wave and up to 5 MW of neutral beam injection. Particle balance and core fueling efficiencies of low and high field side gas fueling of L-mode homic and NBI heated plasmas have been compared using an analytical zero dimensional particle balance model and measured ion and neutral fluxes. Gas fueling efficiencies are in the range of 0.05-0.20 and do not depend on discharge magnetic configuration, density or poloidal location of the injector. The particle balance modeling indicates that the addition of HFS fueling results in a reversal of the wall loading rate and higher wall inventories. Initial particle source estimates obtained from neutral pressure and spectroscopic measurements indicate that ion flux into the divertor greatly exceeds midplane ion flux from the main plasma, suggesting that the scrape-off cross-field transport plays a minor role in diverted plasmas. Present analysis provides the basis for detailed fluid modeling of core and edge particle flows and particle confinement properties of NSTX plasmas. This research was supported by the U.S. Department of Energy under contracts No. DE-AC02-76CH03073, DE-AC05-00OR22725, and W-7405-ENG-36.

  7. An imaging proton spectrometer for short-pulse laser plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H; Hazi, A; van Maren, R; Chen, S; Fuchs, J; Gauthier, M; Pape, S L; Rygg, J R; Shepherd, R

    2010-05-11

    Ultra intense short pulse laser pulses incident on solid targets can generate energetic protons. In additions to their potentially important applications such as in cancer treatments and proton fast ignition, these protons are essential to understand the complex physics of intense laser plasma interaction. To better characterize these laser-produced protons, we designed and constructed a novel, spatially imaging proton spectrometer that will not only measure proton energy distribution with high resolution, but also provide its angular characteristics. The information obtained from this spectrometer compliments those from commonly used diagnostics including radiochromic film packs, CR39 nuclear track detectors, and non-imaging magnetic spectrometers. The basic characterizations and sample data from this instrument are presented.

  8. Tendinopathies and platelet-rich plasma (PRP): from pre-clinical experiments to therapeutic use

    Science.gov (United States)

    Kaux, Jean-François; Drion, Pierre; Croisier, Jean-Louis; Crielaard, Jean-Michel

    2015-01-01

    Objectives: The restorative properties of platelets, through the local release of growth factors, are used in various medical areas. This article reviews fundamental and clinical research relating to platelet-rich plasma applied to tendinous lesions. Materials and method: Articles in French and English, published between 1 January 2012 and 31 December 2014. dealing with PRP and tendons were searched for using the Medline and Scopus data bases. Results: Forty-seven articles were identified which addressed pre-clinical and clinical studies: 27 relating to in vitro and in vivo animal studies and 20 relating to human studies. Of these, five addressed lateral epicondylitis, two addressed rotator cuff tendinopathies, ten dealt with patellar tendinopathies and three looked at Achilles tendinopathies. Conclusions: The majority of pre-clinical studies show that PRP stimulates the tendon’s healing process. However, clinical series remain more controversial and level 1, controlled, randomised studies are still needed. PMID:26195890

  9. Tendinopathies and platelet-rich plasma (PRP: from pre-clinical experiments to therapeutic use

    Directory of Open Access Journals (Sweden)

    Kaux JF

    2015-05-01

    Full Text Available Objectives: The restorative properties of platelets, through the local release of growth factors, are used in various medical areas. This article reviews fundamental and clinical research relating to platelet-rich plasma applied to tendinous lesions. Materials and method: Articles in French and English, published between 1 January 2012 and 31 December 2014. dealing with PRP and tendons were searched for using the Medline and Scopus data bases. Results: Forty-seven articles were identified which addressed pre-clinical and clinical studies: 27 relating to in vitro and in vivo animal studies and 20 relating to human studies. Of these, five addressed lateral epicondylitis, two addressed rotator cuff tendinopathies, ten dealt with patellar tendinopathies and three looked at Achilles tendinopathies. Conclusions: The majority of pre-clinical studies show that PRP stimulates the tendon's healing process. However, clinical series remain more controversial and level 1, controlled, randomised studies are still needed.

  10. Analysis of pre-flight modulator voltage calibration data for the Voyager plasma science experiment

    Science.gov (United States)

    Nastov, Ognen

    1988-01-01

    The Voyager Plasma Science (PLS) modulator calibration (MVM) data analysis was undertaken in order to check the correctness of the fast A/D converter formulas that connect low voltage monitor signals (MV) with digital outputs (DN), to determine the proportionality constants between the actual modulator grid potential (V) and the monitor voltage (MV), and to establish an algorithm to link the digitized readouts (DN) with the actual grid potential (V). The analysis results are surprising in that the derived conversion constants deviate by fairly significant amounts from their nominal values. However, it must be kept in mind that the test results which were used for analysis may be very imprecise. Even if it is assumed that the test result errors are very large, they do no appear to be capable to account for all discrepancies between the theoretical expectations and the results of the analysis. Measurements with the flight spare instrument appear to be the only means of investigating these effects further.

  11. Plasma-exchange in the treatment of systemic rheumatic diseases: past and present experience

    Directory of Open Access Journals (Sweden)

    P. Marson

    2011-06-01

    Full Text Available La terapia con plasma-exchange (PEx è stata utilizzata sin dagli anni Settanta per la cura di molteplici malattie, nella cui patogenesi fattori umorali si riteneva potessero giocare un ruolo di rilievo. Questa modalità di trattamento comporta la rimozione di autoanticorpi, immunocomplessi circolanti, molecole di adesione, citochine, chemochine ed altri mediatori solubili implicati nello sviluppo del danno tissutale (1. Nel 1993 l’American Society of Apheresis (ASFA ha per la prima volta pubblicato un elenco di applicazioni cliniche delle diverse tecniche di aferesi terapeutica, fra le quali di gran lunga la più utilizzata era, allora come oggi, il PEx (2. Questo elenco comprendeva malattie autoimmuni, malattie ematologiche ed oncologiche, disordini metabolici, malattie neurologiche e malattie renali. Fra le malattie autoimmuni figuravano molte forme morbose di pertinenza reumatologica...

  12. High Bandwidth Data Recording Systems for Pulsed Power and Laser Produced Plasma Experiments.

    Energy Technology Data Exchange (ETDEWEB)

    May, M J; Clancy, T; Fittinghoff, D; Halvorson, C; MIlls, T; Nikitin, A; Perry, T; Roberson, P; Smith, D; Teruya, A; Miller, K; Trainham, C

    2006-05-02

    We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5 GHz. The other system is based upon a fiber-optic Mach-Zehnder modulator and has a bandwidth of 12 GHz, and is limited by the photo receiver. The signals are recorded on commercial digitizing oscilloscopes that have approximately 6 effective bits. The transmission systems use many off-the-shelf components from the telecommunications industry and thus have a high reliability and a moderate cost. Results from recent measurements will be presented. Investigation of the reduction in optical transmission by the fibers during exposure to high dose radiation will also be discussed.

  13. Small volume plasma exchange in Guillain-Barre syndrome: experience in 25 patients.

    Science.gov (United States)

    Tharakan, J; Jayaprakash, P A; Iyer, V P

    1990-08-01

    The impact of small volume plasma exchange (PE) on the treatment of Guillain-Barre syndrome (GBS) was studied by comparing 25 patients treated with PE since 1982 with 25 historic controls treated without PE prior to 1982. Small volume PE was done by removing 10-15 ml plasma/kg body weight daily till the progression of the disease was arrested or recovery started. The PE group started recovering earlier (median 3 days, compared to 17.5 days in controls, 2P = 0.01), attained better clinical grades at the end of the 1st and 3rd months (2P = 0.001), and took much shorter time to recover by one clinical grade (median 15 days, compared to 53 days in controls, 2P = 0.01). The median duration of ventilation among the surviving patients was shorter in the PE group (8 days compared to 24.5 days, 2P = 0.10) and total number of complications was less in the PE group (15 events compared to 22 in the controls, 2P = 0.05). Three months after the onset of neuropathy, 13/25 controls were still bed bound, whereas only 4/25 in the PE group remained in that grade (2P = 0.02). There was no significant difference in the mortality rate in two groups (2P = 0.09), but the difference was significant in the subgroup of patients who were ventilated (2P = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Advanced study of ICF-energy direct conversion for laser fusion rocket with quasi-dipole field in the laser-plasma experiments and pic-simulations*

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Y P; Vchivkov, K V; Boyarintsev, E L; Melekhov, A V; Posukh, V G; Shaikhislamov, I F [Institute of Laser Physics (ILP), Russian Academy of Sciences (RAS), Novosibirsk, 630090 (Russian Federation); Nakashima, H; Kajimura, Y [Department of Advanced Energy Engineering Science, Kyushu University (KU), 816-8580 (Japan)], E-mail: zakharov@plasma.nsk.ru

    2008-05-01

    We had studied by the methods of numerical and laboratory simulations an important problem of direct inductive conversion of the ICF-plasma' energy into electric one, under conditions of promising space propulsions with magnetic nozzle. For such kind of Laser Fusion Rocket, like a VISTA, with the strong and dipole-like magnetic field, a minimal 5%-level of conversion efficiency is required to supply a need power for laser system etc. As a result of calculations by 3D/PIC-code of KU a real opportunity to achieve this value was confirmed for the first time with taking into account a data of simulative experiments at KI-1 facility of ILP. A schemes and results of 'VISTA-KI' experiments with Laser-Plasma clouds is discussed to verify this opportunity under real conditions of flute-like plasma instability and the geometry of plasma expansion (versus the main and pick-up coils) close to VISTA.

  15. MHD limits and plasma response in high-beta hybrid operations in ASDEX Upgrade

    Science.gov (United States)

    Igochine, V.; Piovesan, P.; Classen, I. G. J.; Dunne, M.; Gude, A.; Lauber, P.; Liu, Y.; Maraschek, M.; Marrelli, L.; McDermott, R.; Reich, M.; Ryan, D.; Schneller, M.; Strumberger, E.; Suttrop, W.; Tardini, G.; Zohm, H.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

    2017-11-01

    The improved H-mode scenario (or high β hybrid operations) is one of the main candidates for high-fusion performance tokamak operation that offers a potential steady-state scenario. In this case, the normalized pressure {{β }N} must be maximized and pressure-driven instabilities will limit the plasma performance. These instabilities could have either resistive ((m  =  2, n  =  1) and (3,2) neoclassical tearing modes (NTMs)) or ideal character (n  =  1 ideal kink mode). In ASDEX Upgrade (AUG), the first limit for maximum achievable {{β }N} is set by the NTMs. The application of pre-emptive electron cyclotron current drive at the q  =  2 and q  =  1.5 resonant surfaces reduces this problem, so that higher values of {{β }N} can be reached. AUG experiments have shown that, in spite of the fact that hybrids are mainly limited by NTMs, the proximity to the no-wall limit leads to amplification of the external fields that strongly influence the plasma profiles. For example, rotation braking is observed throughout the plasma and peaks in the core. In this situation, even small external fields are amplified and their effect becomes visible. To quantify these effects, the plasma response to the magnetic fields produced by B-coils is measured as {{β }N} approaches the no-wall limit. These experiments and corresponding modeling allow the identification of the main limiting factors, which depend on the stabilizing influence of the conducting components facing the plasma surface, the existence of external actuators, and the kinetic interaction between the plasma and the marginally stable ideal modes. Analysis of the plasma reaction to external perturbations allowed us to identify optimal correction currents for compensating the intrinsic error field in the device. Such correction, together with the analysis of kinetic effects, will help to increase {{β }N} further in future experiments.

  16. Application of a design of experiment approach in the development of a sensitive bioanalytical assay in human plasma.

    Science.gov (United States)

    Dawes, Michelle L; Bergum, James S; Schuster, Alan E; Aubry, Anne-Françoise

    2012-11-01

    To support a first-in-human (FIH) clinical study in healthy volunteers, a human plasma assay, a 20-fold more sensitive method than the validated non-clinical LC-MS/MS assays, was requested. For the clinical assay, a LLOQ of 0.050 ng/mL for Compound A and 0.100 ng/mL for Compound B was desired to accurately determine the analyte concentrations in human plasma samples across all treatment groups. A design of experiment (DOE) investigation was performed in an effort to optimize the extraction procedure of the bioanalytical assay used to support the first in human study and future clinical studies. Three factors, extraction buffer pH (two pHs), volume ratio of organic solvent to plasma (two ratios), and extraction shake time (three times), were selected for the DOE. Both analytes were analyzed at a low concentration, 0.150 ng/mL, and a stable isotope label internal standard was used for each analyte. To estimate the recovery of each analyte from the extraction, the response ratio of each analyte over the respective internal standard was used, and to estimate matrix effects, the absolute response (peak area) of each analyte was used. The results of the DOE indicated that the three factors tested had a more significant effect on the extraction of the metabolite, Compound B, compared to that of the parent, Compound A. The extraction buffer pH had the greatest influence on Compound B and the volume of extraction solvent had an influence on both analytes. Unexpectedly, a longer extraction time caused an apparent decrease in the overall recovery for both analytes. This was presumably due to an increased extraction of interfering matrix components. Optimal conditions were achieved for the combined analysis of both compounds using the DOE approach. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx

    Directory of Open Access Journals (Sweden)

    P.-D. Pautet

    2009-06-01

    Full Text Available From September to November 2005, the NASA Living with a Star program supported the Spread-F Experiment campaign (SpreadFEx in Brazil to study the effects of convectively generated gravity waves on the ionosphere and their role in seeding Rayleigh-Taylor instabilities, and associated equatorial plasma bubbles. Several US and Brazilian institutes deployed a broad range of instruments (all-sky imagers, digisondes, photometers, meteor/VHF radars, GPS receivers covering a large area of Brazil. The campaign was divided in two observational phases centered on the September and October new moon periods. During these periods, an Utah State University (USU all-sky CCD imager operated at São João d'Aliança (14.8° S, 47.6° W, near Brasilia, and a Brazilian all-sky CCD imager located at Cariri (7.4° S, 36° W, observed simultaneously the evolution of the ionospheric bubbles in the OI (630 nm emission and the mesospheric gravity wave field. The two sites had approximately the same magnetic latitude (9–10° S but were separated in longitude by ~1500 km.

    Plasma bubbles were observed on every clear night (17 from Brasilia and 19 from Cariri, with 8 coincident nights. These joint datasets provided important information for characterizing the ionospheric depletions during the campaign and to perform a novel longitudinal investigation of their variability. Measurements of the drift velocities at both sites are in good agreement with previous studies, however, the overlapping fields of view revealed significant differences in the occurrence and structure of the plasma bubbles, providing new evidence for localized generation. This paper summarizes the observed bubble characteristics important for related investigations of their seeding mechanisms associated with gravity wave activity.

  18. Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx

    Directory of Open Access Journals (Sweden)

    P.-D. Pautet

    2009-06-01

    Full Text Available From September to November 2005, the NASA Living with a Star program supported the Spread-F Experiment campaign (SpreadFEx in Brazil to study the effects of convectively generated gravity waves on the ionosphere and their role in seeding Rayleigh-Taylor instabilities, and associated equatorial plasma bubbles. Several US and Brazilian institutes deployed a broad range of instruments (all-sky imagers, digisondes, photometers, meteor/VHF radars, GPS receivers covering a large area of Brazil. The campaign was divided in two observational phases centered on the September and October new moon periods. During these periods, an Utah State University (USU all-sky CCD imager operated at São João d'Aliança (14.8° S, 47.6° W, near Brasilia, and a Brazilian all-sky CCD imager located at Cariri (7.4° S, 36° W, observed simultaneously the evolution of the ionospheric bubbles in the OI (630 nm emission and the mesospheric gravity wave field. The two sites had approximately the same magnetic latitude (9–10° S but were separated in longitude by ~1500 km. Plasma bubbles were observed on every clear night (17 from Brasilia and 19 from Cariri, with 8 coincident nights. These joint datasets provided important information for characterizing the ionospheric depletions during the campaign and to perform a novel longitudinal investigation of their variability. Measurements of the drift velocities at both sites are in good agreement with previous studies, however, the overlapping fields of view revealed significant differences in the occurrence and structure of the plasma bubbles, providing new evidence for localized generation. This paper summarizes the observed bubble characteristics important for related investigations of their seeding mechanisms associated with gravity wave activity.

  19. Plasma Shape and Current Density Profile Control in Advanced Tokamak Operating Scenarios

    Science.gov (United States)

    Shi, Wenyu

    -point position. Setting up a suitable toroidal current profile is related to both the stability and performance of the plasma. The requirements of ITER motivate the research on plasma current profile control. Currently, physics-based control-oriented modeling techniques of the current profile evolution can be separated into two major classes: data-driven and first-principles-driven. In this dissertation, a two-timescale linear dynamic data-driven model of the rotational transform profile and betaN is identified based on experimental data from the DIII-D tokamak. A mixed-sensitivity Hinfinity controller is developed and tested during DIII-D high-confinement (H-mode) experiments by using the heating and current drive (H&CD) systems to regulate the plasma rotational transform profile and betaN around particular target values close to the reference state used for system identification. The preliminary experimental results show good progress towards routine current profile control in DIII-D. As an alternative, a nonlinear dynamic first-principles-driven model is obtained by converting the physics-based model that describes the current profile evolution in H-mode DIII-D discharges into a form suitable for control design. The obtained control-oriented model is validated by comparing the model prediction to experimental data. An Hinfinity control design problem is formulated to synthesize a stabilizing feedback controller, with the goal of developing a closed-loop controller to drive the current profile in DIII-D to a desirable target evolution. Simulations show that the controller is capable of regulating the system around the target rotational transform profile in the presence of disturbances. When compared to a previously designed data-driven model-based controller, the proposed first-principles-driven model-based controller shows potential for improving the control performance.

  20. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

    Science.gov (United States)

    Mikkelsen, D. R.; Bitter, M.; Delgado-Aparicio, L.; Hill, K. W.; Greenwald, M.; Howard, N. T.; Hughes, J. W.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Ma, Y.; Candy, J.; Waltz, R. E.

    2015-06-01

    Peaked density profiles in low-collisionality AUG and JET H-mode plasmas are probably caused by a turbulently driven particle pinch, and Alcator C-Mod experiments confirmed that collisionality is a critical parameter. Density peaking in reactors could produce a number of important effects, some beneficial, such as enhanced fusion power and transport of fuel ions from the edge to the core, while others are undesirable, such as lower beta limits, reduced radiation from the plasma edge, and consequently higher divertor heat loads. Fundamental understanding of the pinch will enable planning to optimize these impacts. We show that density peaking is predicted by nonlinear gyrokinetic turbulence simulations based on measured profile data from low collisionality H-mode plasma in Alcator C-Mod. Multiple ion species are included to determine whether hydrogenic density peaking has an isotope dependence or is influenced by typical levels of low-Z impurities, and whether impurity density peaking depends on the species. We find that the deuterium density profile is slightly more peaked than that of hydrogen, and that experimentally relevant levels of boron have no appreciable effect on hydrogenic density peaking. The ratio of density at r/a = 0.44 to that at r/a = 0.74 is 1.2 for the majority D and minority H ions (and for electrons), and increases with impurity Z: 1.1 for helium, 1.15 for boron, 1.3 for neon, 1.4 for argon, and 1.5 for molybdenum. The ion temperature profile is varied to match better the predicted heat flux with the experimental transport analysis, but the resulting factor of two change in heat transport has only a weak effect on the predicted density peaking.

  1. Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling

    Science.gov (United States)

    Hassanein, A.; Sizyuk, T.; Sizyuk, V.; Harilal, S. S.

    2011-04-01

    Laser produced plasmas (LPP) is currently a promising source of an efficient extreme ultraviolet (EUV) photon source production for advanced lithography. Optimum laser pulse parameters with adjusted wavelength, energy, and duration for simple planar or spherical tin target can provide 2-3% conversion efficiency (CE) in laboratory experiments. These values are also in good agreement with modeling results. Additional effects such as targets with complex geometry and tin-doped targets using pre-pulsing of laser beams can significantly increase CE. Recent studies showed that such improvements in LPP system are due to reduction in laser energy losses by decreasing photons transmission (higher harmonic of Nd:YAG laser) or photons reflection (for CO2 laser). Optimization of target heating using pre-pulses or ablating low-density and nanoporous tin oxide can further improve LLP sources by creating more efficient plasma plumes and as a result increasing CE, the most important parameter for EUV sources. The second important challenge in developing LPP devices is to decrease fast ions and target debris to protect the optical collection system and increase its lifetime. We investigated the combined effects of pre-pulsing with various parameters and different target geometries on EUV conversion efficiency and on energetic ions production. The much higher reflectivity of CO2 laser from a tin target leads to two possible ways for system improvement using pre-pulses with shorter laser wavelengths or using more complex targets geometries with special grooves as developed previously by the authors.

  2. A Radiation-Hydrodynamics Code Comparison for Laser-Produced Plasmas: FLASH versus HYDRA and the Results of Validation Experiments

    CERN Document Server

    Orban, Chris; Chawla, Sugreev; Wilks, Scott C; Lamb, Donald Q

    2013-01-01

    The potential for laser-produced plasmas to yield fundamental insights into high energy density physics (HEDP) and deliver other useful applications can sometimes be frustrated by uncertainties in modeling the properties and expansion of these plasmas using radiation-hydrodynamics codes. In an effort to overcome this and to corroborate the accuracy of the HEDP capabilities recently added to the publicly available FLASH radiation-hydrodynamics code, we present detailed comparisons of FLASH results to new and previously published results from the HYDRA code used extensively at Lawrence Livermore National Laboratory. We focus on two very different problems of interest: (1) an Aluminum slab irradiated by 15.3 and 76.7 mJ of "pre-pulse" laser energy and (2) a mm-long triangular groove cut in an Aluminum target irradiated by a rectangular laser beam. Because this latter problem bears a resemblance to astrophysical jets, Grava et al., Phys. Rev. E, 78, (2008) performed this experiment and compared detailed x-ray int...

  3. Optical properties of Al mirrors under impact of deuterium plasma ions in experiments simulating ITER conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bardamid, A.F. [Taras Shevchenko National University, 01033 Kiev (Ukraine); Belyaeva, A.I. [National Technical University ' KhPI' , 61002 Kharkov (Ukraine); Davis, J.W., E-mail: jwdavis@starfire.utias.utoronto.c [University of Toronto Institute for Aerospace Studies, 4925 Dufferin St., Toronto, ON, Canada M3H5T6 (Canada); Dobrotvorskaya, M.V. [NSC Single Crystal Institute, Kharkov (Ukraine); Galuza, A.A. [National Technical University ' KhPI' , 61002 Kharkov (Ukraine); Kapitonchuk, L.M. [E.O.Paton Electric Welding Institute, Kiev (Ukraine); Konovalov, V.G.; Ryzhkov, I.V.; Shtan' , A.F. [IPP NSC KIPT, 61108 Kharkov (Ukraine); Slatin, K.A. [National Technical University ' KhPI' , 61002 Kharkov (Ukraine); Solodovchenko, S.I.; Voitsenya, V.S. [IPP NSC KIPT, 61108 Kharkov (Ukraine)

    2009-09-15

    The ion-induced modification of aluminum alloy mirrors, under bombardment by deuterium plasma ions has been investigated as a simulation of the environment effects on in-vessel mirrors in ITER. Ellipsometry and reflectrometry have been used to characterize the mirror surface, along with several surface diagnostic techniques (XPS, Auger, SIMS). The results of multiangular- and spectro-ellipsometry were analyzed using both a bare surface model, and effective medium model; the medium was composed of Al, Al{sub 2}O{sub 3} (Al(OD){sub 3} or AlOOD), and voids. It was found that the reflectance decreases following exposure to keV-range ions, but can be restored by subsequent exposing the mirror to low-energy ions (approx60 eV). Chemical processes related to an increased oxide layer are thought to be responsible for the decrease in reflectance, while the reduction of the oxide layer following low-energy D{sup +} exposure may lead to the return of high reflectance. By comparing the measurements with the results of modeling, a mechanism is suggested to explain the experimental data. The mechanism is based on: (1) chemical processes in a surface layer and (2) changes in the thickness and roughness of the surface layer.

  4. Role of platelet-rich plasma in chronic alopecia areata: Our centre experience

    Directory of Open Access Journals (Sweden)

    Sukhbir Singh

    2015-01-01

    Full Text Available Aim: The aim of the study was to evaluate the efficacy of platelet-rich plasma (PRP in the treatment of chronic alopecia areata (AA. Material and Methods: This is a prospective study that was conducted at Kamal Hospital, Kaushambi in which 20 patients who attended the outpatient department were enrolled for the study. All the patients had h/o patches and taken various line of treatments for a duration of 2 years. All the patients were biopsy-proven positive for AA disease. There was no randomisation done since all of them were healthy young adults. The patients′age ranged from 25 to 35 years, and none of them had any co-morbidities. Results: Of 20 patients, only one patient had a relapse. None of the patients had any side effects, and all of them tolerated the procedure well. Conclusion: We wish to conclude that PRP has a definite role in treating AA infections. However, still more long-term follow-up, studies are required for further validation of results and labelling it as a 100% cure for people suffering from AA with recurrences which are so common.

  5. Investigation of the influence of divertor recycling on global plasma confinement in JET ITER-like wall

    NARCIS (Netherlands)

    Tamain, P.; Joffrin, E.; Bufferand, H.; Jarvinen, A.; Brezinsek, S.; Ciraolo, G.; Delabie, E.; Frassinetti, L.; Giroud, C.; Groth, M.; Lipschultz, B.; Lomas, P.; Marsen, S.; Menmuir, S.; Oberkofler, M.; Stamp, M.; Wiesen, S.; JET-EFDA Contributors,

    2015-01-01

    Abstract The impact of the divertor geometry on global plasma confinement in type I ELMy H-mode has been investigated in the JET tokamak equipped with ITER-Like Wall. Discharges have been performed in which the position of the strike-points was changed while keeping the bulk plasma equilibrium

  6. Field-aligned currents and magnetospheric generator in experiments on a laser-produced plasma flowing around a magnetic dipole

    Science.gov (United States)

    Shaikhislamov, I. F.; Antonov, V. M.; Zakharov, Yu. P.; Boyarintsev, E. L.; Melekhov, A. V.; Posukh, V. G.; Ponomarenko, A. G.

    2014-07-01

    A laboratory experiment on modeling the magnetospheric generator of the field-aligned currents and the Earth's transpolar potential in the absence of IMF is illustrated. The measurements of the total field-aligned current in the generator shorted mode and the transpolar potential in the circuit disconnection mode made it possible to determine the generator internal resistance. A model that explains the saturation current and internal resistance by the feedback between the field-aligned current and plasma flank motions has been proposed. This feedback is described through the effective resistance, which is proportional to the flow rate and the ratio of the boundary layer to the dimension of the magnetosphere. For the experimental conditions, the calculated generator resistance was in good agreement with the measured value. The estimates for the Earth's magnetosphere indicate that the MHD generator internal resistance in the boundary layer is usually much lower than the reverse integral conductivity of the ionosphere.

  7. Development of room temperature crossbar-H-mode cavities for proton and ion acceleration in the low to medium beta range

    Directory of Open Access Journals (Sweden)

    G. Clemente

    2011-11-01

    Full Text Available The crossbar H-mode (CH cavity is an accelerating structure operated in the H_{21(0} mode. The robustness of the crossbar geometry allows one to realize room temperature as well as superconducting linac cavities. The shunt impedance characteristics of this structure are attractive to develop proton and heavy ion linacs in the low and medium beta range. A first room temperature eight-cell prototype has proven the feasibility of the crossbar design in terms of mechanical construction, copper plating, and cooling. An innovative rf coupling concept has been developed where two CH cavities are connected by a two gap E_{010}-mode resonator which, at the same time, provides transverse focusing by a quadrupole triplet. The concept has been applied in the design of the new FAIR proton linac and a scaled model of the second cavity of this injector has been built and tested too. The full scale prototype is now under construction at the University of Frankfurt. In this paper, the room temperature CH cavity development as well as the general layout of the FAIR proton injector (70 MeV, 325 MHz, 70 mA is presented and discussed.

  8. A scheme to produce a dense positronium plasma for an antihydrogen experiment

    Energy Technology Data Exchange (ETDEWEB)

    Perez, P. [CEA Saclay, DSM/IRFU, 91191 Gif-sur-Yvette Cedex (France)], E-mail: patrice.perez@cea.fr; Liszkay, L.; Rey, J.-M.; Delferrierre, O.; Blideanu, V.; Carty, M.; Curtoni, A.; Ruiz, N.; Sauce, Y. [CEA Saclay, DSM/IRFU, 91191 Gif-sur-Yvette Cedex (France)

    2008-10-31

    A 6 MeV industrial electron linac with 0.2 mA average current will be installed in December 2007 in CEA-Saclay. Equipped with a tungsten target and moderator, it is aimed at producing rates of order 10{sup 8} s{sup -1} slow positrons. This setup is part of a project to demonstrate the feasibility of an experiment to produce the H-bar{sup +} ion for a free fall measurement of H-bar. The energy is below the neutron activation threshold. Its small size and cost could be of interest for a university laboratory or industry, and could be envisaged as a replacement source for the antihydrogen experiments at CERN.

  9. Attachment of polymer chains on plasma-treated surfaces: experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Riccardi, C [Dipartimento di Fisica, Universita di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Roman, H E [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden (Germany); Ziano, R, E-mail: roman@pks.mpg.d [Dipartimento di Medicina Sperimentale, Universita di Milano-Bicocca, Via Cadore 48, 20052 Monza (Italy)

    2010-07-15

    Deposition of linear polymers, such as polyethylene glycol (PEG), on a plasma-treated surface has been studied experimentally and theoretically by means of Monte Carlo (MC) simulations. Acrylic acid is deposited on a silicon wafer in the presence of argon at a pressure of 10 Pa by applying 30 W external power. Active carboxyl sites are obtained having a surface number density of {approx}2 sites nm{sup -2}. A homogeneous PEG solution is brought into contact with the treated surface (over 24 h) and a thin film of attached PEG chains is formed. Two different PEGs having molecular weights of 3000 and 5000 g mol{sup -1}, respectively, are considered. The corresponding thin film widths, W, are measured, yielding W(3000)=4.3{+-}3.1 nm and W(5000)=8.8{+-}1.8 nm. For the MC simulations, the linear polymers are modeled as an ensemble of self-avoiding walks of length N (number of monomers) on a simple cubic lattice, executing worm-like or reptation dynamics, which can become attached at an active carboxyl site on the surface. The numerical results for the film widths are in good agreement with the experimental findings. We find that less than 20% of active sites are effectively occupied by attached chains, corresponding to less than 5% of the total available surface sites. Scaling arguments predict universal power-law dependences of the film density, {rho}(N), as a function of polymer length, i.e. {rho}(N){approx}c/N{sup {nu}}, with c{approx_equal}5 g cm{sup -3} and {nu}{approx_equal}0.6. The model also predicts a dependence of the prefactor c on the density of carboxyl active sites.

  10. On uniform plasma generation for the large area plasma processing in intermediate pressures

    Science.gov (United States)

    Kim, Hyun Jun; Hwang, Hye-Ju; Kim, Dong Hwan; Cho, Jeong Hee; Chae, Hee Sun; Chung, Chin-Wook

    2015-04-01

    Radial plasma discharge characteristics in the range of 450 mm were studied in a dual inductively coupled plasma (ICP) source, which consisted of a helical ICP and the side type ferrite ICPs. Since the energy relaxation length is shorter than the distance between each of the ferrite ICPs in an intermediate pressure (600 mTorr), local difference in the plasma ignition along the antenna position were observed. In addition, large voltage drop in the discharge of the ferrite ICPs causes an increase in the displacement current to the plasma, and separate discharge mode (E and H mode) according to the antenna position was observed. This results in non-uniform plasma distribution. For the improvement in the discharge of the ferrite ICPs, a capacitor which is placed between the ends of antenna and the ground is adjusted to minimize the displacement current to the plasma. As a result, coincident transitions from E to H mode were observed along the antenna position, and radially concave density profile (edge focused) was measured. For the uniform density distribution, a helical ICP, which located at the center of the discharge chamber, was simultaneously discharged with the ferrite ICPs. Due to the plasma potential variation through the simultaneous discharge of helical ICP and ferrite ICPs, uniform radial distribution in both plasma density and electron temperature are achieved.

  11. Turbulent Dynamo Amplification of Magnetic Fields in Laser-Produced Plasmas: Simulations and Experiments

    Science.gov (United States)

    Tzeferacos, P.; Rigby, A.; Bott, A.; Bell, A.; Bingham, R.; Casner, A.; Cattaneo, F.; Churazov, E.; Forest, C.; Katz, J.; Koenig, M.; Li, C.-K.; Meinecke, J.; Petrasso, R.; Park, H.-S.; Remington, B.; Ross, J.; Ryutov, D.; Ryu, D.; Reville, B.; Miniati, F.; Schekochihin, A.; Froula, D.; Lamb, D.; Gregori, G.

    2017-10-01

    The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between the filaments of galaxy clusters to several teragauss in black holes and neutron stars. The standard model for cosmological magnetic fields is the nonlinear amplification of seed fields via turbulent dynamo. We have conceived experiments to demonstrate and study the turbulent dynamo mechanism in the laboratory. Here, we describe the design of these experiments through large-scale 3D FLASH simulations on the Mira supercomputer at ANL, and the laser-driven experiments we conducted with the OMEGA laser at LLE. Our results indicate that turbulence is capable of rapidly amplifying seed fields to near equipartition with the turbulent fluid motions. This work was supported in part from the ERC (FP7/2007-2013, No. 256973 and 247039), and the U.S. DOE, Contract No. B591485 to LLNL, FWP 57789 to ANL, Grant No. DE-NA0002724 and DE-SC0016566 to the University of Chicago, and DE-AC02-06CH11357 to ANL.

  12. Validation of Kinetic-Turbulent-Neoclassical Theory for Edge Intrinsic Rotation in DIII-D Plasmas

    Science.gov (United States)

    Ashourvan, Arash

    2017-10-01

    Recent experiments on DIII-D with low-torque neutral beam injection (NBI) have provided a validation of a new model of momentum generation in a wide range of conditions spanning L- and H-mode with direct ion and electron heating. A challenge in predicting the bulk rotation profile for ITER has been to capture the physics of momentum transport near the separatrix and steep gradient region. A recent theory has presented a model for edge momentum transport which predicts the value and direction of the main-ion intrinsic velocity at the pedestal-top, generated by the passing orbits in the inhomogeneous turbulent field. In this study, this model-predicted velocity is tested on DIII-D for a database of 44 low-torque NBI discharges comprised of bothL- and H-mode plasmas. For moderate NBI powers (PNBInet injected torque through the edge can exceed 1 N.m in the counter-current direction. The theory model has been extended to compute the rotation degradation from this counter-current NBI torque by solving a reduced momentum evolution equation for the edge and found the revised velocity prediction to be in agreement with experiment. Projecting to the ITER baseline scenario, this model predicts a value for the pedestal-top rotation (ρ 0.9) comparable to 4 kRad/s. Using the theory modeled - and now tested - velocity to predict the bulk plasma rotation opens up a path to more confidently projecting the confinement and stability in ITER. Supported by the US DOE under DE-AC02-09CH11466 and DE-FC02-04ER54698.

  13. Two-slope soft X-ray spectra observed in experiments on electron cyclotron resonance plasma heating in the L-2M stellarator

    Science.gov (United States)

    Meshcheryakov, A. I.; Vafin, I. Yu.; Grishina, I. A.; Letunov, A. A.; Tereshchenko, M. A.

    2017-06-01

    In experiments on the generation and electron cyclotron resonance heating (ECRH) of plasma in the L-2M stellarator, non-Maxwellian two-slope soft X-ray (SXR) spectra were observed. The temperatures of the thermal and epithermal components of the spectra were measured as functions of the heating power and plasma density. A hypothesis based on the experimental results is suggested to explain the formation mechanism of two-slope SXR spectra in the ECRH experiments at the L-2M stellarator. The measured SXR spectra are compared with the results of numerical simulations.

  14. Frontiers of the Physics of Dense Plasmas and Planetary Interiors: Experiment, Theory, Applications

    Energy Technology Data Exchange (ETDEWEB)

    Fortney, J J; Glenzer, S H; Koenig, M; Brambrink, E; Militzer, B; Saumon, D; Valencia, D

    2008-09-12

    We review recent developments of dynamic x-ray characterization experiments of dense matter, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. We examine several applications of this work. These include the structure of massive 'Super Earth' terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as our benchmark for giant planets. We are now in an era of dramatic improvement in our knowledge of the physics of materials at high density. For light elements, this theoretical and experimental work has many applications, including internal confinement fusion as well as the interiors of gas giant planets. For heavy elements, experiments on silicates and iron at high pressure are helping to better understand the Earth, as well as terrestrial planets as a class of objects. In particular, the discovery of rocky and gaseous planets in other planetary systems has opened our imaginations to planets not found in our own solar system. While the fields of experiments of matter at high densities, first principles calculations of equations of state (EOS), planetary science, and astronomy do progress independently of each other, it is important for there to be communication between fields. For instance, in the realm of planets, physicists can learn of key problems that exist in the area of planetary structure, and how advances in our understanding of input physics could shed new light in this area. Astronomers and planetary scientists can learn where breakthroughs in physics of materials under extreme conditions are occurring, and be ready to apply these findings within their fields.

  15. Frontier of the physics of dense plasmas and planetary interiors: experiments, theory, applications

    Energy Technology Data Exchange (ETDEWEB)

    Saumon, Didier [Los Alamos National Laboratory; Fortney, Jonathan J [UC SANTA CRUZ; Glenzer, Siegfried H [LLNL; Koenig, Michel [LULI (FRANCE); Brambrink, E [LULI(FRANCE); Militzer, Burkhard [UC BERKELEY; Valencia, Diana [HARVARD U

    2008-01-01

    Recent developments of dynamic x-ray characterization experiments of dense matter are reviewed, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. Several applications of this work are examined. These include the structure of massive 'super-Earth' terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as the benchmark for giant planets.

  16. Experiments and Computational Theory for Electrical Breakdown in Critical Components: THz Imaging of Electronic Plasmas.

    Energy Technology Data Exchange (ETDEWEB)

    Zutavern, Fred J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hjalmarson, Harold P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bigman, Verle Howard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallegos, Richard Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    This report describes the development of ultra-short pulse laser (USPL) induced terahertz (THz) radiation to image electronic plasmas during electrical breakdown. The technique uses three pulses from two USPLs to (1) trigger the breakdown, (2) create a 2 picosecond (ps, 10 -12 s), THz pulse to illuminate the breakdown, and (3) record the THz image of the breakdown. During this three year internal research program, sub-picosecond jitter timing for the lasers, THz generation, high bandwidth (BW) diagnostics, and THz image acquisition was demonstrated. High intensity THz radiation was optically-induced in a pulse-charged gallium arsenide photoconductive switch. The radiation was collected, transported, concentrated, and co-propagated through an electro-optic crystal with an 800 nm USPL pulse whose polarization was rotated due to the spatially varying electric field of the THz image. The polarization modulated USPL pulse was then passed through a polarizer and the resulting spatially varying intensity was detected in a high resolution digital camera. Single shot images had a signal to noise of %7E3:1. Signal to noise was improved to %7E30:1 with several experimental techniques and by averaging the THz images from %7E4000 laser pulses internally and externally with the camera and the acquisition system (40 pulses per readout). THz shadows of metallic films and objects were also recorded with this system to demonstrate free-carrier absorption of the THz radiation and improve image contrast and resolution. These 2 ps THz pulses were created and resolved with 100 femtosecond (fs, 10 -15 s) long USPL pulses. Thus this technology has the capability to time-resolve extremely fast repetitive or single shot phenomena, such as those that occur during the initiation of electrical breakdown. The goal of imaging electrical breakdown was not reached during this three year project. However, plans to achieve this goal as part of a follow-on project are described in this document

  17. Hosing Instability of the Drive Electron Beam in the E157 Plasma-Wakefield Acceleration Experiment at the Stanford Linear Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Brent Edward; /SLAC /UCLA

    2005-10-10

    In the plasma-wakefield experiment at SLAC, known as E157, an ultra-relativistic electron beam is used to both excite and witness a plasma wave for advanced accelerator applications. If the beam is tilted, then it will undergo transverse oscillations inside of the plasma. These oscillations can grow exponentially via an instability know as the electron hose instability. The linear theory of electron-hose instability in a uniform ion column predicts that for the parameters of the E157 experiment (beam charge, bunch length, and plasma density) a growth of the centroid offset should occur. Analysis of the E157 data has provided four critical results. The first was that the incoming beam did have a tilt. The tilt was much smaller than the radius and was measured to be 5.3 {micro}m/{delta}{sub z} at the entrance of the plasma (IP1.) The second was the beam centroid oscillates in the ion channel at half the frequency of the beam radius (betatron beam oscillations), and these oscillations can be predicted by the envelope equation. Third, up to the maximum operating plasma density of E157 ({approx}2 x 10{sup 14} cm{sup -3}), no growth of the centroid offset was measured. Finally, time-resolved data of the beam shows that up to this density, no significant growth of the tail of the beam (up to 8ps from the centroid) occurred even though the beam had an initial tilt.

  18. Neutron emission in neutral beam heated KSTAR plasmas and its application to neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Jong-Gu, E-mail: jgkwak@nfri.re.kr; Kim, H.S.; Cheon, M.S.; Oh, S.T.; Lee, Y.S.; Terzolo, L.

    2016-11-01

    Highlights: • We measured the neutron emission from KSTAR plasmas quantitatively. • We confirmed that neutron emission is coming from neutral beam-plasma interactions. • The feasibility study shows that the fast neutron from KSTAR could be used for fast neutron radiography. - Abstract: The main mission of Korea Superconducting Tokamak Advanced Research (KSTAR) program is exploring the physics and technologies of high performance steady state Tokamak operation that are essential for ITER and fusion reactor. Since the successful first operation in 2008, the plasma performance is enhanced and duration of H-mode is extended to around 50 s which corresponds to a few times of current diffusion time and surpassing the current conventional Tokamak operation. In addition to long-pulse operation, the operational boundary of the H-mode discharge is further extended over MHD no-wall limit(β{sub N} ∼ 4) transiently and higher stored energy region is obtained by increased total heating power (∼6 MW) and plasma current (I{sub p} up to 1 MA for ∼10 s). Heating system consists of various mixtures (NB, ECH, LHCD, ICRF) but the major horse heating resource is the neutral beam(NB) of 100 keV with 4.5 MW and most of experiments are conducted with NB. So there is a lot of production of fast neutrons coming from via D(d,n){sup 3}He reaction and it is found that most of neutrons are coming from deuterium beam plasma interaction. Nominal neutron yield and the area of beam port is about 10{sup 13}–10{sup 14}/s and 1 m{sup 2} at the closest access position of the sample respectively and neutron emission could be modulated for application to the neutron radiography by varying NB power. This work reports on the results of quantitative analysis of neutron emission measurements and results are discussed in terms of beam-plasma interaction and plasma confinement. It also includes the feasibility study of neutron radiography using KSTAR.

  19. Numerical investigation on lithium transport in the edge plasma of EAST real-time- Li-injection experiments in the frame of BOUT + +

    Science.gov (United States)

    Li, N. M.; Sun, J. Z.; Wang, Z. H.; Xu, X. Q.; Sun, Z.; Wang, L.; Hu, J. S.; Wang, D. Z.

    2016-10-01

    Experimental observations on applications of Lithium (Li) have indicated that Li could benefit plasma performance. But all these call for further investigation on lithium transport. A simple model has been developed by reducing Braginskii's equations with assumed quasi-neutral condition for transport of Li species in the edge plasma in the EAST experiments of real-time Li aerosol injection and implemented in the frame of BOUT + + . The simulation results show that Li atoms propagate inwards continuously during the Li injection, and the propagating depth of Li atoms depends on both the local plasma conditions along its path and the Li injection velocity. It is also found that Li ions accumulate rapidly in the edge, and only a small fraction of Li species can transport cross the magnetic field into the core. In the poloidal direction, Li ions drift swiftly downwards along the field lines, and transport much faster at the high field side than at the low field side. The strong interaction between background plasma and Li ions plays a critical role in determining the edge plasma profile. It is found that real-time Li injection raises the plasma density in the pedestal region and reduces the plasma temperature, just as has been observed experimentally National Magnetic Confinement Fusion Science Program of China No. 2013GB107003, National Natural Science Foundation of China No. 11575039.

  20. EFFECT OF APPLE CIDER VINEGAR ON PLASMA LIPIDS (MODEL EXPERIMENT IN MICE

    Directory of Open Access Journals (Sweden)

    Balázs Bender

    2012-02-01

    Full Text Available Normal 0 21 false false false HU X-NONE X-NONE Model experiment was carried out to investigate the effect of apple cider vinegar (ACV on the blood and liver cholesterol (Ch, triglycerides (TG and one of a marker of antioxidant status of blood (FRAP in laboratory mice. Animals consumed a basal mice diet (Control served as the control group. The same diet was supplemented either 1% cholesterol (Ch or 1% edible sunflower oil (SFO. All groups were duplicated and their animals were supplied drinking water containing ACV (50 mg l-1(groups: Control+ACV, Chol+ACV, SFO+ACV.The feeding and drinking was ad libitum for 21 days. At the end of experiment the animals were exterminated. Blood and liver samples were analyzed for total cholesterol (tCh, triglycerides (TG and ferric reducing antioxidant power (FRAP. The results show that the Ch supplemented group stored higher concentration of tCh in the liver (Pdoi:10.5219/156  

  1. Plasma physics for controlled fusion

    CERN Document Server

    Miyamoto, Kenro

    2016-01-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator includi...

  2. Experiments of Discharge Guiding using Strongly and Weakly Ionized Plasma Channel produced by KrF Laser

    Science.gov (United States)

    Shimada, Yoshinori; Uchida, Shigeaki; Kawasaki, Zen-Ichiro; Yamanaka, Tatsuhiko; Takagi, Yasuhiro; Furuoka, Yoshihiro; Yamanaka, Chiyoe

    We have studied the feasibility of a hybrid discharge method (to guide the discharge with strongly and weakly ionized plasma channels) of a long guiding laser plasma channel. Charged particle densities in a weakly ionized plasma channel were measured as a function of the laser intensity. Critical condition of the weakly ionized plasma to guide an electrical streamer was determined. The electrical resistibility of plasma channel to generate the self-propagating streamer is smaller than 3.5 Ωm. The self-propagating streamer could heat the channel and leads to a main discharge.

  3. A successful experience of the Iranian blood transfusion organization in improving accessibility and affordability of plasma derived medicine.

    Science.gov (United States)

    Chegini, Azita; Torab, Seyed Ardeshir; Pourfatollah, Ali Akbar

    2017-02-01

    Plasma is the liquid part of blood. It is estimated 21.6 million liters of plasma collect from Whole blood annually. From these plasma, 4.2 million liters transfuse, 8.1 million liters fractionate, 9.3 million liters waste. Nowadays, blood products and PDM (plasma derived medicine) consider as essential medicine in modern health care and transfusion medicine. Iranian blood transfusion organization as a non-profit organization was established in 1974 in order to centralize all blood transfusion activities from donor recruitment to distribution of blood components to hospitals. Iran is the only country in EMR region with the rate of 20-29.9 blood donations per 1000 population and reached 100% voluntary non-remunerated blood donation in 2007. RBCs and platelets demand are much more than FFPs so the IBTO was faced the surplus plasma that could cause surplus plasma wastage. Simultaneously, hospitals need more plasma derived medicine especially albumin, IVIG, factor VIII, factor IX. IBTO was faced the challenges such as Fractionators selection, Plasma volume shipment, Contract duration, Product profile, Multiple External audits, Cold chain maintenance, Transporting plasma across international borders, NAT test. To overcome plasma wastage and storage of PDM. IBTO involved toll manufacturing in 2005 and not only prevents plasma wastage but also save MOH (ministry of health) budget. Copyright © 2016. Published by Elsevier Ltd.

  4. Discriminant analysis of plasma fusion data

    Science.gov (United States)

    Kardaun, O. J. W. F.; Kardaun, J. W. P. F.; Itoh, Sanae-I.; Itoh, Kimitaka

    1992-06-01

    Discriminant analysis is a branch of statistics with applications in many fields. One of these (a relatively new one) is nuclear fusion research, where one is interested in various types of plasma discharges produced in toroidal devices. In many instances, one has a small number, say 2 or 3, of different types of discharges under investigation. For instance, L-mode and H-mode discharges (L stands for Low confinement, and H for High confinement), or: H-mode discharges without ELM's, with 'small' ELM's, and with 'large' (giant) ELM's. The abbreviation ELM's stands for Edge Localized Modes, which are detected by light recording instruments. They enhance the outward transport of the plasma, including the plasma impurities, but if they are large, they produce a heavy heat load on material contacts of the plasma with the wall. There are typically 4 or 5 continuous variables, for instance plasma current Ip, magnetic field B(sub t), plasma electron density n(sub e), input heating power P(inj), that influence the type of discharge ('shot') that will occur. In addition, there may be a few (2 or 3) discrete variables that are physically expected to be important. Finally, there are a number of wall conditioning aspects, which influence the type of shots that will be produced. In the framework of the ITER project, a collaborative effort between Europe, GUS, Japan and the USA, an international fusion reactor device is being designed which is due to operate at the beginning of the next century. In this context, a database (ITERH.DB1) has been assembled containing plasma confinement data of about 1000 H-mode discharges from 6 different tokamaks. These data have been released for general use by plasma physicists and other interested scientists. We will use part of these data to illustrate various discriminant analysis techniques. Several discriminant analysis methods have been applied and compared to predict the type of ELM's in H-mode discharges: (1) quadratic discriminant

  5. Analysis of Waves in Space Plasma (WISP) near field simulation and experiment

    Science.gov (United States)

    Richie, James E.

    1992-01-01

    The WISP payload scheduler for a 1995 space transportation system (shuttle flight) will include a large power transmitter on board at a wide range of frequencies. The levels of electromagnetic interference/electromagnetic compatibility (EMI/EMC) must be addressed to insure the safety of the shuttle crew. This report is concerned with the simulation and experimental verification of EMI/EMC for the WISP payload in the shuttle cargo bay. The simulations have been carried out using the method of moments for both thin wires and patches to stimulate closed solids. Data obtained from simulation is compared with experimental results. An investigation of the accuracy of the modeling approach is also included. The report begins with a description of the WISP experiment. A description of the model used to simulate the cargo bay follows. The results of the simulation are compared to experimental data on the input impedance of the WISP antenna with the cargo bay present. A discussion of the methods used to verify the accuracy of the model is shown to illustrate appropriate methods for obtaining this information. Finally, suggestions for future work are provided.

  6. Electron kinetics dependence on gas pressure in laser-induced oxygen plasma experiment: Theoretical analysis

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Abdellatif, Galila

    2017-08-01

    A study is performed to investigate the dependency of threshold intensity on gas pressure observed in the measurements of the breakdown of molecular oxygen that carried out by Phuoc (2000) [1]. In this experiment, the breakdown was induced by 532 nm laser radiation of pulse width 5.5 ns and spot size of 8.5 μm, in oxygen over a wide pressure range (190-3000 Torr). The analysis aimed to explore the electron kinetic reliance on gas pressure for the separate contribution of each of the gain and loss processes encountered in this study. The investigation is based on an electron cascade model applied previously in Gamal and Omar (2001) [2] and Gaabour et al. (2013) [3]. This model solves numerically a differential equation designates the time evolution of the electron energy distribution, and a set of rate equations that describe the change of excited states population. The numerical examination of the electron energy distribution function and its parameters revealed that photo-ionization of the excited molecules plays a significant role in enhancing the electron density growth rate over the whole tested gas pressure range. This process is off set by diffusion of electrons out of the focal volume in the low-pressure regime. At atmospheric pressure electron, collisional processes dominate and act mainly to populate the excited states. Hence photo-ionization becomes efficient and compete with the encountered loss processes (electron diffusion, vibrational excitation of the ground state molecules as well as two body attachments). At high pressures ( 3000 Torr) three body attachments are found to be the primary cause of losses which deplete the electron density and hence results in the slow decrease of the threshold intensity.

  7. ELM suppression in helium plasmas with 3D magnetic fields

    Science.gov (United States)

    Evans, T. E.; Loarte, A.; Orlov, D. M.; Grierson, B. A.; Knölker, M. M.; Lyons, B. C.; Cui, L.; Gohil, P.; Groebner, R. J.; Moyer, R. A.; Nazikian, R.; Osborne, T. H.; Unterberg, E. A.

    2017-08-01

    Experiments in DIII-D, using non-axisymmetric magnetic perturbation fields in high-purity low toroidal rotation, 4He plasmas have resulted in Type-I edge localized mode (ELM) suppression and mitigation. Suppression is obtained in plasmas with zero net input torque near the L-H power threshold using either electron cyclotron resonant heating (ECRH) or balanced co- and counter-I p neutral beam injection (NBI) resulting in conditions equivalent to those expected in ITER’s non-active operating phase. In low-power ECRH H-modes, periods with uncontrolled density and impurity radiation excursions are prevented by applying n  =  3 non-axisymmetric magnetic perturbation fields. ELM suppression results from a reduction and an outward shift of the electron pressure gradient peak compared to that in the high-power ELMing phase. The change in the electron pressure gradient peak is primarily due to a drop in the pedestal temperature rather than the pedestal density.

  8. Muon probe and connected instrumentation for the study of quark-gluon plasma in ALICE experiment; Sonde muonique et instrumentation associee pour l'etude du plasma de quarks et de gluons dans l'experience ALICE

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, Fabien [Ecole Doctorale des Sciences Fondamentales, Universite Blaise Pascal, U.F.R de Recherches Scientifiques et Techniques, 34, avenue Carnot - BP 185, 63006 Clermont-Ferrand Cedex (France)

    2006-11-15

    ALICE (A Large Ion Collider Experiment) is the LHC detector dedicated to the study of ultra-relativistic heavy ion collisions. The main goal of ALICE is the study of a new phase of the nuclear matter predicted by the Quantum Chromodynamics theory (QCD): the Quark-Gluon Plasma (QGP). One of the possible signatures is a suppression of quarkonia yields by color screening in the heavy ion collisions, in which the formation of the QGP is expected. The muon spectrometer will allow measuring of the quarkonia yields (J/{psi}, {upsilon}) in heavy ion collisions via their dimuon decay. A fast trigger, associated to muon spectrometer, has to select events with at least one muon or one dimuon by using a track search algorithm. The study of muon trigger performance will be presented with emphasis on the trigger efficiency and rates in Ar-Ar and Pb-Pb collisions. We will also present the reconstruction of unlike-sign dimuon mass spectrum with the ALICE muon spectrometer. The expected yields of Upsilon states will be extracted from a simulation based on a fit of this spectrum for one month running for Pb-Pb collisions and for different collision centralities. (author)

  9. Experimental and analytical studies of merging plasma loops on the Caltech solar loop experiment

    Science.gov (United States)

    Pitigoi-Aron, Gabriela

    and personal factors and perceptions with emphasis on mentors' influence; (5) Negative influence of salary difference with respect to private practitioners. The findings of this study were similar to the available studies on foreign-trained dentists and to most of the studies already done on domestically trained dentists. The major factors found were comparable with the up-to-date literature. The elevated research drive, the intellectual challenges, the work environment, the desire to teach, and the mentors' influence were among those which mirrored almost perfectly the other studies. Some fine differences were found for foreign-trained dentists, such as a lighter financial burden caused by smaller student debt and the irrelevance of military practice experience. The study provides a number of suggestions for enhancing the recruiting and retaining process for dental academia: (1) Support and enhance the research capacity of dental schools; (2) Create structures to develop mentors; (3) Invest to build prestige; (4) Find creative ways to offset lower salaries; (5) Foster a pleasant academic working environment; (6) Use international activities to recruit international dentists. The study revealed factors that have been influential in participants' decisions to choose an academic career, in general and at Pacific. It is hoped that this study will be a useful reference in the increasingly difficult endeavor of adding and retaining world-class dental educators.

  10. Production of Terahertz Seed Radiation for FEL/IFEL Microbunchers for Second Generation Plasma Beatwave Experiments at Neptune

    CERN Document Server

    Ralph, Joseph; Rosenzweig, James E; Sung, Chieh; Tochitsky, Sergei Ya

    2005-01-01

    To achieve phase locked injection of short electron bunches in a plasma beatwave accelerator, the Neptune Laboratory will utilize microbunching in an FEL or IFEL system. These systems require terahertz (THz) seed radiation on the order of 10 kW for the FEL and 10 MW for the IFEL bunchers. We report results of experiments on THz generation using nonlinear frequency mixing of CO2 laser lines in GaAs. A two-wavelength laser beam was split and sent onto a 2.5 cm long GaAs crystal cut for noncollinear phase matching. Low power measurements achieved ~1 W of 340 ?m radiation using 200 ns CO2 pump pulses with wavelengths 10.3?m and 10.6?m. We also demonstrated tunability of difference frequency radiation, producing 240?m by mixing two different CO2 laser lines. By going to shorter laser pulses and higher intensities, we were able to increase the conversion efficiency while decreasing the surface damage threshold. Using 200ps pulses we produced ~2 MW of 340 ?m radiation. Future studies in this area will focus on devel...

  11. The Effect of Plasma Beta on High-n Ballooning Stability at Low Magnetic Shear

    CERN Document Server

    Connor, J W; Hastie, R J

    2016-01-01

    An explanation of the observed improvement in H-mode pedestal characteristics with increasing core plasma pressure or poloidal beta, as observed in MAST and JET, is sought in terms of the impact of the Shafranov shift, d', on ideal ballooning MHD stability.

  12. On the influence of atomic physics mechanisms on edge plasma turbulence in the TJ-I and Princeton Beta Experiment-Modified tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Pedrosa, M.A.; Garcia-Cortes, I.; Branas, B.; Balbin, R.; Hidalgo, C. [Asociacion EURATOM/CIEMAT, 28040-Madrid (Spain); Schmitz, L.; Tynan, G. [University of California at Los Angeles, Los Angeles, California 90024 (United States); Post-Zwicker, A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 3783, The PBX-M Team (United States)]|[Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    1995-07-01

    The role of neutrals as a driving force of plasma turbulence was investigated in the TJ-I tokamak [Phys. Fluids B {bold 5}, 4051 (1993)]. No influence of the local neutral source strength on fluctuation levels was found, neither in the plasma bulk side nor in the scrape-off layer side of the velocity shear layer location. Helium puffing was used to study the influence of impurity radiation on turbulence in the Princeton Beta Experiment-Modified (PBX-M) [{ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Nuclear} {ital Fusion} {ital Research} 1988 (International Atomic Physics Agency, Nice, 1989), Vol. 1, p. 97]. Evidence of fluctuation levels modified increasing He-impurity radiation was obtained. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  13. Two-fluid (plasma-neutral) Extended-MHD simulations of spheromak configurations in the HIT-SI experiment with PSI-Tet

    Science.gov (United States)

    Sutherland, D. A.; Hansen, C. J.; Jarboe, T. R.

    2017-10-01

    A self-consistent, two-fluid (plasma-neutral) dynamic neutral model has been implemented into the 3-D, Extended-MHD code PSI-Tet. A monatomic, hydrogenic neutral fluid reacts with a plasma fluid through elastic scattering collisions and three inelastic collision reactions: electron-impact ionization, radiative recombination, and resonant charge-exchange. Density, momentum, and energy are evolved for both the plasma and neutral species. The implemented plasma-neutral model in PSI-Tet is being used to simulate decaying spheromak configurations in the HIT-SI experimental geometry, which is being compare to two-photon absorption laser induced fluorescence measurements (TALIF) made on the HIT-SI3 experiment. TALIF is used to measure the absolute density and temperature of monatomic deuterium atoms. Neutral densities on the order of 1015 m-3 and neutral temperatures between 0.6-1.7 eV were measured towards the end of decay of spheromak configurations with initial toroidal currents between 10-12 kA. Validation results between TALIF measurements and PSI-Tet simulations with the implemented dynamic neutral model will be presented. Additionally, preliminary dynamic neutral simulations of the HIT-SI/HIT-SI3 spheromak plasmas sustained with inductive helicity injection will be presented. Lastly, potential benefits of an expansion of the two-fluid model into a multi-fluid model that includes multiple neutral species and tracking of charge states will be discussed.

  14. DIII-D Edge Plasma, Disruptions, and Radiative Processes. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Boedo, J. A.; Luckhardt, S.C.; Moyer, R. A.

    2001-01-01

    The scientific goal of the UCSD-DIII-D Collaboration during this period was to understand the coupling of the core plasma to the plasma-facing components through the plasma boundary (edge and scrape-off layer). To achieve this goal, UCSD scientists studied the transport of particles, momentum, energy, and radiation from the plasma core to the plasma-facing components under normal (e.g., L-mode, H-mode, and ELMs), and off-normal (e.g., disruptions) operating conditions.

  15. Plasma flow measurements in improved modes on STOR-M and CASTOR tokamaks

    Science.gov (United States)

    Germaine, G. S.; Xiao, C.; Hirose, A.

    2010-02-01

    A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r=82 mm and biased to+500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrape-off layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both ohmic discharges and discharges with electrode biasing.

  16. TURis plasma vaporization in non-muscle invasive bladder cancer--the first Romanian experience with a new technique

    National Research Council Canada - National Science Library

    Geavlete, B; Jecu, M; Mulţescu, R; Georgescu, D; Drăguţescu, M; Geavlete, P

    2010-01-01

    .... The aim of our study was to evaluate the efficacy and safety of a newly introduced endoscopic technique, the bipolar transurethral resection in saline-plasma vaporization of bladder tumors (TURis-PVBT...

  17. Influence of plasma pressure gradient on melt layer macroscopic erosion of metal targets in disruption simulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tereshin, V.I.; Garkusha, I.E. E-mail: garkusha@ipp.kharkov.ua; Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Makhlaj, V.A.; Solyakov, D.G.; Wuerz, H

    2003-03-01

    Melt layer erosion of metal targets under pulsed high heat loads is discussed. Tungsten, copper, aluminum, and titanium targets were exposed to perpendicular and inclined plasma impact in the quasi-steady-state plasma accelerator QSPA Kh-50. Melt layer motion results in erosion crater formation with rather large mountains of the resolidified material at the crater edge. It is shown that macroscopic motion of the melt layer and surface cracking are the main factors responsible for tungsten erosion.

  18. Numerical modeling of lower hybrid current drive in fully non-inductive plasma start-up experiments on TST-2

    Science.gov (United States)

    Tsujii, N.; Takase, Y.; Ejiri, A.; Shinya, T.; Togashi, H.; Yajima, S.; Yamazaki, H.; Moeller, C. P.; Roidl, B.; Sonehara, M.; Takahashi, W.; Toida, K.; Yoshida, Y.

    2017-12-01

    Non-inductive plasma start-up is a critical issue for spherical tokamaks since there is not enough room to provide neutron shielding for the center solenoid. Start-up using lower hybrid (LH) waves has been studied on the TST-2 spherical tokamak. Because of the low magnetic field of a spherical tokamak, the plasma density needs to be kept at a very low value during the plasma current ramp-up so that the plasma core remains accessible to the LH waves. However, we have found that higher density was required to sustain larger plasma current. The achievable plasma current was limited by the maximum operational toroidal field of TST-2. The existence of an optimum density for LH current drive and its toroidal field dependence is explained through a numerical simulation based on a ray tracing code and a Fokker-Planck solver. In order to access higher density at the same magnetic field, a top-launch antenna was recently installed in addition to the existing outboard-launch antenna. Increase in the density limit was observed when the power was launched from the top antenna, consistently with the numerical predictions.

  19. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    Directory of Open Access Journals (Sweden)

    T. R. Robinson

    Full Text Available A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.

    Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

  20. Hysteresis and mode transitions in inductively coupled Ar Hg plasma in the electrodeless induction lamp

    Science.gov (United States)

    Qi, Long; Yuming, Chen; Dahua, Chen

    2006-08-01

    Hysteresis and mode transitions in inductively coupled Ar-Hg plasma in the electrodeless induction lamp are studied at different discharge frequencies and under different matching conditions. It is observed that transition currents change at different frequencies and hysteresis exists not only between the starting and minimum maintaining currents of the electromagnetic mode (H mode) discharge but also between the starting and minimum maintaining currents of the electrostatic mode (E mode) discharge. The illuminance and global electrical parameters in the mode transitions are recorded. It is shown that the E to H mode transition is accompanied by increased plasma resistance and decreased plasma reactance, which results in a higher efficiency in the H mode. Under the same output voltage of the radio frequency source, mode transition can also be triggered by changing the matching condition. The emission spectra recorded before and after the E to H mode transition provide experimental evidence for the theory that the change of the electron energy distribution function plays an important role in the hysteresis effect.

  1. Plasma current start-up experiments without a central solenoid in the iron core STOR-M tokamak

    Science.gov (United States)

    Mitarai, O.; Tomney, G.; Rohollohi, A.; Lewis, E.; McColl, D.; Xiao, C.; Hirose, A.

    2015-06-01

    Reproducible plasma current start-up without a central solenoid (CS) has been demonstrated using the outer ohmic heating (OH) coils in the iron core STOR-M tokamak (Mitarai et al 2014 Fusion Eng. Des. 89 2467-71). Although the outer OH coil current saturates the iron core eventually, it has been demonstrated that the plasma current can be maintained during the iron core saturation phase. In this work, further studies have been conducted to investigate the effects of the turn number of the outer OH coils (N = 4 or N = 6) in the CS-less discharges and to evaluate the plasma stability with respect to the n-decay index of the vertical magnetic field. For the loose coupling of the iron core with N = 4 turns, the plasma current can be sustained after the additional third capacitor bank is applied near the iron core saturation phase, showing the slow transition from the unsaturated to the partially saturated phase. For the case of stronger coupling of N = 6 turns, the plasma current is increased at the same fast bank voltage, but the main discharge is shortened from 35 to 20 ms. As the magnetizing current is smaller due to stronger coupling between the OH coils and the plasma current, the transition from the unsaturated to the saturated phase is slightly difficult at present. The present experimental results suggest a feasible operation scenario in a future spherical tokamak (ST) at least using loose iron core coupling for smoother transition from the unsaturated to the saturated iron core phase. Thus, a reliable plasma current start-up by the outer OH coils and the current ramp-up to a steady state by additional heating power and vertical field coils could be considered as an operation scenario for future ST reactors with an iron core transformer.

  2. Electron transport in the plasma edge with rotating resonant magnetic perturbations at the TEXTOR tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Stoschus, Henning

    2011-10-13

    Small three-dimensional (3D) magnetic perturbations can be used as a tool to control the edge plasma parameters in magnetically confined plasmas in high confinement mode (''H-mode'') to suppress edge instabilities inherent to this regime, the Edge Localized Modes (ELMs). In this work, the impact of rotating 3D resonant magnetic perturbation (RMP) fields on the edge plasma structure characterized by electron density and temperature fields is investigated. We study a low confinement (L-mode) edge plasma (r/a>0.9) with high resistivity (edge electron collisionality {nu}{sup *}{sub e}>4) at the TEXTOR tokamak. The plasma structure in the plasma edge is measured by a set of high resolution diagnostics: a fast CCD camera ({delta}t=20 {mu}s) is set up in order to visualize the plasma structure in terms of electron density variations. A supersonic helium beam diagnostic is established as standard diagnostic at TEXTOR to measure electron density n{sub e} and temperature T{sub e} with high spatial ({delta}r=2 mm) and temporal resolution ({delta}t=20 {mu}s). The measured plasma structure is compared to modeling results from the fluid plasma and kinetic neutral transport code EMC3-EIRENE. A sequence of five new observations is discussed: (1) Imaging of electron density variations in the plasma edge shows that a fast rotating RMP field imposes an edge plasma structure, which rotates with the external RMP rotation frequency of vertical stroke {nu}{sub RMP} vertical stroke =1 kHz. (2) Measurements of the electron density and temperature provide strong experimental evidence that in the far edge a rotating 3D scrape-off layer (SOL) exists with helical exhaust channels to the plasma wall components. (3) Radially inward, the plasma structure at the next rational flux surface is found to depend on the relative rotation between external RMP field and intrinsic plasma rotation. For low relative rotation the plasma structure is dominated by a particle and energy loss

  3. Experiment-Model Comparisons of Turbulence, Transport, and Flows in a Magnetized Linear Plasma Using a Global Two-Fluid Braginskii Solver

    Science.gov (United States)

    Gilmore, M.; Fisher, D. M.; Kelly, R. F.; Hatch, M. W.; Rogers, B. N.

    2017-10-01

    Ongoing experiments and numerical modeling of the dynamics of electrostatic turbulence and transport in the presence of flow shear are being conducted in helicon plasmas in the linear HelCat (Helicon-Cathode) device. Modeling is being done using GBS, a 3D, global two-fluid Braginskii code that solves self-consistently for plasma equilibrium as well as fluctuations. Past experimental measurements of flows have been difficult to reconcile with simple expectations, such as azimuthal flows being dominated by Er x Bz rotation. Therefore, recent measurements have focused on understanding plasma flows, and the role of neutral dynamics. In the model, a set of two-fluid drift-reduced Braginskii equations are evolved using the Global Braginskii Solver Code (GBS). For low-field helicon-sourced Ar plasmas a non-negligible cross-field thermal collisional term must be added to shift the electric potential in the ion momentum and vorticity equations as the ions are unmagnetized. Significant radially and axially dependent neutral profiles are also included in the simulations to try and match those observed in HelCat. Ongoing simulations show a mode dependence on the axial magnetic field along with strong axial variations that suggest drift waves may be important in the low-field case. Supported by U.S. National Science Foundation Award 1500423.

  4. Radial transport in the far scrape-off layer of ASDEX upgrade during L-mode and ELMy H-mode

    DEFF Research Database (Denmark)

    Ionita, C.; Naulin, Volker; Mehlmann, F.

    2013-01-01

    potentials of two probes on the same poloidal meridian. In both cases, equal electron temperatures on all probe pins had to be assumed. Of the other pins one was biased to ion saturation (-70 V), whereas one was swept to record the current-voltage characteristic. A detailed statistical analysis of the plasma...... probes. One of the probe pins was protruding radially above the other pins. The radial electric field component was derived from the difference of the floating potentials of the protruding pin and another pin nearby. The poloidal electric field component was derived from the difference of the floating...

  5. Prevalence of RhD status and clinical application of non-invasive prenatal determination of fetal RHD in maternal plasma: a 5 year experience in Cyprus.

    Science.gov (United States)

    Papasavva, Thessalia; Martin, Pete; Legler, Tobias J; Liasides, Marios; Anastasiou, George; Christofides, Agathoklis; Christodoulou, Tasos; Demetriou, Sotos; Kerimis, Prokopis; Kontos, Charis; Leontiades, George; Papapetrou, Demetris; Patroclos, Telis; Phylaktou, Marios; Zottis, Nikos; Karitzie, Eleni; Pavlou, Eleni; Kountouris, Petros; Veldhuisen, Barbera; van der Schoot, Ellen; Kleanthous, Marina

    2016-04-01

    After the discovery that cell-free fetal DNA (cffDNA) is circulating in the maternal plasma of pregnant women, non-invasive prenatal diagnosis for fetal RhD in maternal plasma in RhD negative women at risk for haemolytic disease of the newborn (HDN) was clinically established and used by many laboratories. The objectives of this study are: (a) to assess the feasibility and report our experiences of the routine implementation of fetal RHD genotyping by analysis of cffDNA extracted from maternal plasma of RhD negative women at risk of HDN, and (b) to estimate the RhD phenotype frequencies, the RHD genotype frequencies and the RhD zygosity in the Cypriot population. cffDNA was extracted from maternal plasma of 73 RhD negative pregnant women. Real-Time Multiplex-PCR was used to amplify regions of RHD gene in exons 4, 5 and 10. RhD phenotypes were determined on 445 random samples using conventional agglutination slide test. The fetus was predicted to be positive in 53 cases and negative in 18 cases. Two of cases were identified as D-variants, weak D type-1 and 11. The frequency of RhD negative homozygosity in the Cypriot population was estimated to be 7.2%, while the frequencies of RHD hemizygosity and RhD positive homozygosity was calculated to be 39.2 and 53.6%, respectively. Fetal RHD genotyping can be accurately determined using cffDNA from maternal plasma. The implementation of the test has eliminated all use of unnecessary anti-D and reduced the total use of anti-D by 25.3% while achieving appropriate management of the RhD negative pregnancies.

  6. Electronic cigarette user plasma nicotine concentration, puff topography, heart rate, and subjective effects: Influence of liquid nicotine concentration and user experience.

    Science.gov (United States)

    Hiler, Marzena; Breland, Alison; Spindle, Tory; Maloney, Sarah; Lipato, Thokozeni; Karaoghlanian, Nareg; Shihadeh, Alan; Lopez, Alexa; Ramôa, Carolina; Eissenberg, Thomas

    2017-10-01

    Electronic cigarette (ECIG) nicotine delivery and other effects may depend on liquid nicotine concentration and user experience. This study is the first to systematically examine the influence of ECIG liquid nicotine concentration and user experience on nicotine delivery, heart rate, puff topography, and subjective effects. Thirty-three ECIG-experienced individuals and 31 ECIG-naïve cigarette smokers completed 4 laboratory conditions consisting of 2, 10-puff bouts (30-sec interpuff interval) with a 3.3-V ECIG battery attached to a 1.5-Ω "cartomizer" (7.3 W) filled with 1 ml ECIG liquid. Conditions differed by liquid nicotine concentration: 0, 8, 18, or 36 mg/ml. Participants' plasma nicotine concentration was directly related to liquid nicotine concentration and dependent on user experience, with significantly higher mean plasma nicotine increases observed in ECIG-experienced individuals relative to ECIG-naïve smokers in each active nicotine condition. When using 36 mg/ml, mean plasma nicotine increase for ECIG-experienced individuals was 17.9 ng/ml (SD = 17.2) and 6.9 (SD = 7.1; p users: collapsed across condition, mean puff duration was 5.6 sec (SD = 3.0) for ECIG-experienced and 2.9 (SD = 1.5) for ECIG-naïve individuals. ECIG use also suppressed nicotine/tobacco abstinence symptoms in both groups; the magnitude of abstinence symptom suppression depended on liquid nicotine concentration and user experience. These and other recent results suggest that policies intended to limit ECIG nicotine delivery will need to account for factors in addition to liquid nicotine concentration (e.g., device power and user behavior). (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  7. Comparison of measured and computed plasma loading resistance in the tandem mirror experiment-upgrade (TMX-U) central cell

    Energy Technology Data Exchange (ETDEWEB)

    Mett, R.R.

    1984-08-01

    The plasma loading resistance vs density plots computed with McVey's Code XANTENA1, agree well with experimental measurements in the TMX-U central cell. The agreement is much better for frequencies where ..omega../..omega../sub ci/ <1 than for ..omega../..omega../sub ci/ greater than or equal to 1.

  8. Plasma YKL-40 and CHI3L1 in systemic inflammation and sepsis—Experience from two prospective cohorts

    DEFF Research Database (Denmark)

    Kornblit, Brian; Hellemann, Dorthe; Munthe-Fog, Lea

    2013-01-01

    YKL-40, derived from the CHI3L1 gene, has been associated with outcome of infectious and inflammatory diseases. We hypothesized that plasma YKL-40 concentrations and CHI3L1 genotype could be used as prognostic biomarkers in the assessment of systemic inflammatory response syndrome (SIRS) and sepsis...

  9. Non-Inductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta in the Pegasus Toroidal Experiment

    Science.gov (United States)

    Reusch, Joshua

    2017-10-01

    A major goal of the spherical tokamak research program is accessing a state of low internal inductance li, high elongation κ, high toroidal and normalized beta (βt and βN) , and low collisionality without solenoidal current drive. A new local helicity injection (LHI) system in the lower divertor region of the ultra-low aspect ratio Pegasus ST provides non-solenoidally driven plasmas that exhibit most of these characteristics. LHI utilizes compact, edge-localized current sources (Ainj 4 cm2, Iinj 8 kA, Vinj 1.5 kV) for plasma startup and sustainment, and can sustain more than 200 kA of plasma current. Plasma growth via LHI is enhanced by a transition from a regime of high kink-like MHD activity to one of reduced MHD activity at higher frequencies and presumably shorter wavelengths. The strong edge current drive provided by LHI results in a hollow current density profile with low li. The low aspect ratio (R0 / a 1.2) of Pegasus allows ready access to high κ and MHD stable operation at very high normalized plasma currents (IN =Ip /aBT> 15). Thomson scattering measurements indicate Te 100 eV and ne 1 ×19 m-3. The impurity Ti evolution is correlated in time with high frequency magnetic fluctuations, implying substantial reconnection ion heating is driven by the applied helicity injection. Doppler spectroscopy indicates Ti >=Te and that the anomalous ion heating scales consistently with two fluid reconnection theory. Taken together, these features provide access to very high βt plasmas. Equilibrium analyses indicate βt up to 100% and βN 6.5 is achieved. At increasingly low BT, the discharge disrupts at the no-wall ideal stability limit. In these high βt discharges, a minimum |B| well forms over 50% of the plasma volume. This unique magnetic configuration may be of interest for testing predictions of stabilizing drift wave turbulence and/or improving energetic particle confinement. This work supported by US DOE Grants DE-FG02-96ER54375 and DE-SC0006928.

  10. Plasma contactor research, 1989

    Science.gov (United States)

    Williams, John D.

    1990-01-01

    The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

  11. From the conceptual design to the first simulation of the new WEST plasma control system

    Energy Technology Data Exchange (ETDEWEB)

    Nouailletas, R., E-mail: remy.nouailletas@cea.fr [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Ravenel, N.; Signoret, J. [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Treutterer, W. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Spring, A.; Lewerentz, M. [Max Planck Institute for Plasma Physics, Wendeksteinstr. 1, 17491 Greifswald (Germany); Rapson, C.J. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Masand, H.; Dhongde, J. [Institute for Plasma Research (IPR), Near Indira Bridge, Bhat, Gandhinagar 382 428, Gujarat (India); Moreau, P.; Guillerminet, B.; Brémond, S.; Allegretti, L. [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Raupp, G. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Werner, A. [Max Planck Institute for Plasma Physics, Wendeksteinstr. 1, 17491 Greifswald (Germany); Saint Laurent, F.; Nardon, E. [IRFM, CEA, F-13108 Saint Paul lez Durance (France); Bhandarkar, M. [Institute for Plasma Research (IPR), Near Indira Bridge, Bhat, Gandhinagar 382 428, Gujarat (India)

    2015-10-15

    Highlights: • We propose an overview of the future control system of the Tore Supra in WEST configuration. • The control system will be based on DCS (Discharge Control System) of ASDEX Upgrade. • The Pulse Schedule Editor will be based on the experiment program editor of the future W7X facility. • The operation of this new system is illustrated by an example based on a simple plasma current/loop voltage control. - Abstract: The configuration of the Tore Supra WEST project leads to control challenges and event handling close to those of ITER from a plasma scenario point of view (X-point configuration, H mode, long duration pulse) and from a machine protection point of view (metallic environment). Based on previous conceptual studies and to meet the WEST requirements, a sub-project will implement a new plasma control system (PCS) and a new pulse schedule editor (PSE). The main idea is to use a segment approach to describe the pulse scheduling with a full integration of event handling both on the PCS and on the PSE. After detailed specification work, it has been shown that the real-time framework called DCS (Discharge Control System) which is currently used on ASDEX upgrade fulfills the requirements and could be integrated into the WEST global control infrastructure. For the PSE, the Xedit tool, developed for the future W7X facility, has been chosen. This contribution will begin by a short explanation of the concepts proposed for the control of the plasma and the handling of events during the plasma discharge. Then it will focus on the new centralized architecture of the new Tore Supra PCS and an operating principle example showing the efficiency of the approach to handle normal and off-normal events. This later point will illustrate the required modifications of DCS and Xedit to fit with the Tore Supra Control infrastructure.

  12. Scientific Fellow of Max Planck Institute of Plasma Physics (IPP) and European Physical Society President Elect F. Wagner at ATLAS experiment with Collaboration Spokesperson P. Jenni on 22 September 2006.

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Scientific Fellow of Max Planck Institute of Plasma Physics (IPP) and European Physical Society President Elect F. Wagner at ATLAS experiment with Collaboration Spokesperson P. Jenni on 22 September 2006.

  13. A new quasi-stationary, very high density plasma regime on the W7-AS stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Jaenicke, R; Baeumel, S; Baldzuhn, J; Brakel, R; Burhenn, R; Ehmler, H; Endler, M; Erckmann, V; Feng, Y; Gadelmeier, F; Geiger, J; Giannone, L; Grigull, P; Hartfuss, H J; Hartmann, D; Hildebrandt, D; Hirsch, M; Holzhauer, E; Kick, M; Kisslinger, J; Klinger, T; Klose, S; Knauer, J; Koenig, R; Kuehner, G; Laqua, H; Maassberg, H; McCormick, K; Narayanan, R; Niedermeyer, H; Pasch, E; Ruhs, N; Rust, N; Saffert, J; Sardei, F; Schneider, F; Schubert, M; Speth, E; Wagner, F; Weller, A; Wenzel, U; Werner, A; Wuersching, E [Max-Planck Institut fuer Plasmaphysik, EURATOM-Association, D-85748 Garching (Germany)

    2002-12-01

    Stellarators have the intrinsic property of steady state operation. However, on present-day stellarators the pulse length is usually not only limited due to technical reasons, but also by physical problems. Lack of density control and a subsequent radiation collapse terminate the discharges quite often at high densities. To improve the control of the plasma-wall interaction, the island divertor concept was developed for optimized stellarators. To test this divertor concept on W7-AS, all limiters were removed and replaced by ten divertor modules. In subsequent divertor experiments a promising new plasma operational regime has been discovered which is termed 'high density H-mode' (HDH-mode). During the transition into that regime a clear reduction of ELM-like events and turbulent fluctuations is observed. The HDH-mode combines good energy confinement with very low impurity confinement resulting in low core radiation, but high edge-localized radiation. Consequently, stationary discharges at densities of typically 2x10{sup 20} m{sup -3} can be performed within the accessible pulse length of about 1 s. At densities above 3x10{sup 20} m{sup -3} a controlled transition from attached to partially detached plasmas is observed. The still edge-localized radiation reaches 90% of the heating power so that the power load onto the divertor target plates is further reduced. At a lower toroidal field of 0.9 T average {beta}-values could be raised from earlier 2% to more than 3% in magnetic field configurations with rather smooth flux surfaces at the plasma boundary. The recently obtained results render excellent prospects for W7-X, the larger superconducting successor experiment of W7-AS.

  14. Nonlinear electromagnetic fields in 0.5 MHz inductively coupled plasmas

    DEFF Research Database (Denmark)

    Ostrikov, K.N.; Tsakadze, E.L.; Xu, S.

    2003-01-01

    Radial profiles of magnetic fields in the electrostatic (E) and electromagnetic (H) modes of low-frequency (similar to500 kHz) inductively coupled plasmas have been measured using miniature magnetic probes. In the low-power (similar to170 W) E-mode, the magnetic field pattern is purely linear......, with the fundamental frequency harmonics only. After transition to higher-power (similar to1130 W) H-mode, the second-harmonic nonlinear azimuthal magnetic field B-phi(2omega) that is in 4-6 times larger than the fundamental frequency component B-phi(omega), has been observed. A simplified plasma fluid model...... explaining the generation of the second harmonics of the azimuthal magnetic field in the plasma source is proposed. The nonlinear second harmonic poloidal (r-z) rf current generating the azimuthal magnetic field B-phi(2omega) is attributed to nonlinear interactions between the fundamental frequency radial...

  15. Princeton Plasma Physics Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

  16. Comparing Theory and Experiment for Analyte Transport in the First Vacuum Stage of the Inductively Coupled Plasma Mass Spectrometer

    Science.gov (United States)

    Zachreson, Matthew R.

    The inductively coupled plasma mass spectrometer (ICP-MS) has been used in laboratories for many years. The majority of the improvements to the instrument have been done empirically through trial and error. A few fluid models have been made, which have given a general description of the flow through the mass spectrometer interface. However, due to long mean free path effects and other factors, it is very difficult to simulate the flow details well enough to predict how changing the interface design will change the formation of the ion beam. Towards this end, Spencer et al. developed FENIX, a direct simulation Monte Carlo algorithm capable of modeling this transitional flow through the mass spectrometer interface, the transitional flow from disorganized plasma to focused ion beam. Their previous work describes how FENIX simulates the neutral ion flow. While understanding the argon flow is essential to understanding the ICP-MS, the true goal is to improve its analyte detection capabilities. In this work, we develop a model for adding analyte to FENIX and compare it to previously collected experimental data. We also calculate how much ambipolar fields, plasma sheaths, and electron-ion recombination affect the ion beam formation. We find that behind the sampling interface there is no evidence of turbulent mixing. The behavior of the analyte seems to be described simply by convection and diffusion. Also, ambipolar field effects are small and do not significantly affect ion beam formation between the sampler and skimmer cones. We also find that the plasma sheath that forms around the sampling cone does not significantly affect the analyte flow downstream from the skimmer. However, it does thermally insulate the electrons from the sampling cone, which reduces ion-electron recombination. We also develop a model for electron-ion recombination. By comparing it to experimental data, we find that significant amounts of electron-ion recombination occurs just downstream from the

  17. Recent Results on Soft Probes of the Quark-Gluon Plasma from the ATLAS Experiment at the LHC

    CERN Document Server

    Przybycien, M; The ATLAS collaboration

    2014-01-01

    Measurements of low-pT (< 5 GeV) particle production have provided valuable insight on the production and evolution of the quark-gluon plasma in Pb+Pb collisions at the LHC. In particular, measurements of elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-pT particles directly probe the strongly-coupled dynamics of the quark-gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS has made it possible to measure flow event-by-event and to determine the correlations between different harmonics. Recent measurements of low-pT particle production and multi-particle correlations in proton-lead collisions have shown features similar to the collective flow observed in Pb+Pb collisions. Results will be presented from a variety of single and multi-particle measurements in Pb+Pb and proton-Pb collisions that probe the collective dynamics of the quark-gluon plasma and possibly provide evidence for collectivity in ...

  18. An observing system simulation experiment for FORMOSAT-5/AIP probing topside ionospheric plasma irregularities by using DEMETER/IAP

    Directory of Open Access Journals (Sweden)

    Jann-Yenq Liu

    2017-01-01

    Full Text Available The ion density probed by IAP (Instrument d’Analyse du Plasma on board the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions satellite is used to find whether the science payload of Advanced Ionospheric Probe (AIP on board FORMOSAT-5 can be employed to observe space weather of ionospheric plasma irregularities. The low-latitude irregularities within ±15° dip latitudes of the DEMETER/IAP ion density are nighttime phenomena, and become prominent in the South America-Central Africa sector almost all year round, especially during May to August. The high-latitude irregularities of the DEMETER/IAP ion density appear around ±65° dip latitude worldwide in both daytime and nighttime, and become very intense in the winter and the equinox month/hemisphere. DEMETER/IAP results show that FORMOSAT-5/AIP can be used to monitor space weather of ionospheric daytime/nighttime plasma irregularities in not only the low- but also high-latitude ionosphere.

  19. Experiments of synchrotron injection using the direct fast chopped H{sup -} beam extracted from surface-plasma-type negative hydrogen ion source

    Energy Technology Data Exchange (ETDEWEB)

    Shinto, Katsuhiro; Takagi, Akira; Machida, Shinji; Mori, Yoshiharu; Yoshii, Masahito; Shirakata, Masashi; Koba, Kiyomi [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    1997-12-31

    An experiment of synchrotron injection using the direct fast chopped H{sup -} beam extracted from a surface-plasma-type H{sup -} ion source has been successfully achieved. The injection phase of the fast chopped beam from linac into the booster synchrotron is adjustable against the center of rf bucket by using this beam. It was obtained that the longitudinal emittance was controlled at the extraction of the booster synchrotron, and that the beam loss during the injection into main ring of the KEK-PS was reduced by this fast chopped beam. (author)

  20. Evaluating a Contribution of the Knock-on Deuterons to the Neutron Yield in the Experiments with Weakly Collisional Plasma Jets (Part 1)

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-12-01

    Laser-generated interpenetrating plasma jets are widely used in the studies of collisionless interaction of counter-streaming plasmas in conjunction with possible formation of collisionless shocks. In a number of experiments of this type the plasma is formed on plastic targets made of CH or CD. The study of the DD neutron production from the interaction between two CD jets on the one hand and between a CD jet and a CH jet could serve as a qualitative indicator of the collisionless shock formation. The purpose of this memo is a discussion of the effect of collisions on the neutron generation in the interpenetrating CH and CD jets. First, the kinematics of the large-deflection collisions of the deuterons and carbon are discussed. Then the scattering angles are related with the corresponding Rutherford cross-section. After that expression for the number of the backscattered deuterons is provided, and their contribution to the neutron yield is evaluated. The results may be of some significance to the kinetic codes benchmarking and developing the neutron diagnostic.

  1. Experiencia clínica en el empleo de factores de crecimiento autólogos obtenidos de plasma rico en plaquetas Clinical experience related to the use of autologous platelet rich plasma

    Directory of Open Access Journals (Sweden)

    J. Montón Echeverría

    2007-09-01

    Full Text Available El presente artículo pretende exponer el estado actual del conocimiento en relación con el empleo del plasma rico en plaquetas autólogo en diversas indicaciones encuadradas en el marco de la Cirugía Plástica, Estética y Reparadora así como la experiencia clínica acumulada en nuestro Servicio en relación con el uso de este tratamiento durante el periodo comprendido entre el 1 de Enero de 2005 y el 30 de Junio de 2007 (30 meses. Las evidencias clínicas acumuladas hasta el momento indican que el empleo de esta terapia en la promoción de los fenómenos reparativos asociados a distintos procedimientos quirúrgicos plásticos, estéticos y reparadores induce los siguientes efectos: incremento de los procesos de reparación tisular de tejidos blandos y óseos, disminución de las tasas de infección postoperatoria, del dolor y de las pérdidas hemáticas. Basándonos en dicha información exponemos nuestra experiencia sobre un total de 151 casos que comprenden casos de úlceras vasculares, pies diabéticos, radiopatías, pérdidas de sustancia postraumáticas, casos complejos y reconstrucción mamaria. La evidencia clínica, no cuantificada, nos muestra una evolución claramente satisfactoria, comprobando desde una perspectiva clínica una clara mejoría de los fenómenos reparativos.This article intends to expose the state of the art related to the clinical use of autologous rich platelet plasma in different procedures which belong to the field of Plastic and Reconstructive Surgery. It is also referred our clinical experience related to this practice during a 30 month period (January 2005 - June 2007. Clinical evidence shows that this therapy has been able to promote both soft and bone tissue regeneration with a decrease in postoperative infection rates, pain and bleeding. Based upon this knowledge, our experience is related to 151 cases of vascular ulcers, diabetic feet, radiopathy, posttraumatic loss of substance, complex situations and

  2. Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation

    Science.gov (United States)

    Kang, Chen; Hua, Liang

    2016-02-01

    Plasma flow control (PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle (UAV) by nanosecond discharge plasma aerodynamic actuation (NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge (30 A) is much bigger than that for millisecond discharge (0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation (MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503302, 51207169, and 51276197), the China Postdoctoral Science Foundation (Grant No. 2014M562446), and the Natural Science Foundation of Shaanxi Province, China (Grant No. 2015JM1001).

  3. A miniature high voltage plasma interaction flight experiment - Project MINX. [for measuring solar cell array parasitic current drain

    Science.gov (United States)

    Riley, T. J.; Triner, J. E.; Sater, B. L.; Cohen, D.; Somberg, H.

    1974-01-01

    A miniature high-voltage array was fabricated, incorporating the multi-junction edge illuminated (MJC) cell technique. The array consists of 32 2x2.2 cm MJCs, series connected, capable of 1600 V open circuit at 1 AMO and 1.2 mA short circuit. A solid state, high-voltage relay is connected across each 4-cell subgroup of the array. It was built to test plasma current drain on space systems using high voltage as might occur when a high-voltage solar array is operated from low to synchronous orbit.

  4. Edge Minority Heating Experiment in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    S.J. Zweben; J.L. Terry; P. Bonoli; R. Budny; C.S. Chang; C. Fiore; G. Schilling; S. Wukitch; J. Hughes; Y. Lin; R. Perkins; M. Porkolab; the Alcator C-Mod Team

    2005-03-25

    An attempt was made to control global plasma confinement in the Alcator C-Mod tokamak by applying ion cyclotron resonance heating (ICRH) power to the plasma edge in order to deliberately create a minority ion tail loss. In theory, an edge fast ion loss could modify the edge electric field and so stabilize the edge turbulence, which might then reduce the H-mode power threshold or improve the H-mode barrier. However, the experimental result was that edge minority heating resulted in no improvement in the edge plasma parameters or global stored energy, at least at power levels of radio-frequency power is less than or equal to 5.5 MW. A preliminary analysis of these results is presented and some ideas for improvement are discussed.

  5. Non-Invasive Prenatal RHD Genotyping Using Cell-Free Fetal DNA from Maternal Plasma: An Italian Experience.

    Science.gov (United States)

    Picchiassi, Elena; Di Renzo, Gian Carlo; Tarquini, Federica; Bini, Vittorio; Centra, Michela; Pennacchi, Luana; Galeone, Fabiana; Micanti, Mara; Coata, Giuliana

    2015-01-01

    This study assessed the diagnostic accuracy of a non-invasive approach to fetal RHD genotyping using cell-free fetal DNA in maternal plasma and a combination of methodological strategies. Real-time PCR (qPCR) was performed on 216 RhD-negative women between weeks 10+0 and 14+6 of gestation (1st qPCR). qPCR was repeated (2nd qPCR) to increase the amount of each sample for analysis, on 95 plasma aliquots that were available from first trimester blood collection (group 1) and on 13 samples that were collected between weeks 18+0 and 25+6 of gestation (group 2). qPCR was specific for exons 5 and 7 of the RHD gene (RHD5 and RHD7). The results were interpreted according to the number of positive replicates of both exons. 1st qPCR: diagnostic accuracy was of 93.3%. Diagnostic accuracy increased from 90.5% (1st qPCR) to 93.7% (2nd qPCR) in group 1 and from 84.6% (1st qPCR) to 92.3% (2nd qPCR) in group 2. These increments were not statistically significant. Our approach to RHD genotyping in early pregnancy yielded high diagnostic accuracy. Increasing the amount of DNA analyzed in each sample did not improve significantly the diagnostic accuracy of the test.

  6. Plasma detachment study of high density helium plasmas in the Pilot-PSI device

    NARCIS (Netherlands)

    Hayashi, Y.; Jesko, K.; van der Meiden, H. J.; Vernimmen, J. W. M.; Morgan, T. W.; Ohno, N.; Kajita, S.; Yoshikawa, M.; Masuzaki, S.

    2016-01-01

    We have investigated plasma detachment phenomena of high-density helium plasmas in the linear plasma device Pilot-PSI, which can realize a relevant ITER SOL/Divertor plasma condition. The experiment clearly indicated plasma detachment features such as drops in the plasma pressure and particle flux

  7. A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Loebner, Keith T. K., E-mail: kloebner@stanford.edu; Underwood, Thomas C.; Cappelli, Mark A. [Stanford Plasma Physics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-06-15

    A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.

  8. Controlling marginally detached divertor plasmas

    Science.gov (United States)

    Eldon, D.; Kolemen, E.; Barton, J. L.; Briesemeister, A. R.; Humphreys, D. A.; Leonard, A. W.; Maingi, R.; Makowski, M. A.; McLean, A. G.; Moser, A. L.; Stangeby, P. C.

    2017-06-01

    A new control system at DIII-D has stabilized the inter-ELM detached divertor plasma state for H-mode in close proximity to the threshold for reattachment, thus demonstrating the ability to maintain detachment with minimal gas puffing. When the same control system was instead ordered to hold the plasma at the threshold (here defined as T e  =  5 eV near the divertor target plate), the resulting T e profiles separated into two groups with one group consistent with marginal detachment, and the other with marginal attachment. The plasma dithers between the attached and detached states when the control system attempts to hold at the threshold. The control system is upgraded from the one described in Kolemen et al (2015 J. Nucl. Mater. 463 1186) and it handles ELMing plasmas by using real time D α measurements to remove during-ELM slices from real time T e measurements derived from divertor Thomson scattering. The difference between measured and requested inter-ELM T e is passed to a PID (proportional-integral-derivative) controller to determine gas puff commands. While some degree of detachment is essential for the health of ITER’s divertor, more deeply detached plasmas have greater radiative losses and, at the extreme, confinement degradation, making it desirable to limit detachment to the minimum level needed to protect the target plate (Kolemen et al 2015 J. Nucl. Mater. 463 1186). However, the observed bifurcation in plasma conditions at the outer strike point with the ion B   ×  \

  9. Alpha-spectrometry and fractal analysis of surface micro-images for characterisation of porous materials used in manufacture of targets for laser plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Aushev, A A; Barinov, S P; Vasin, M G; Drozdov, Yu M; Ignat' ev, Yu V; Izgorodin, V M; Kovshov, D K; Lakhtikov, A E; Lukovkina, D D; Markelov, V V; Morovov, A P; Shishlov, V V [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2015-06-30

    We present the results of employing the alpha-spectrometry method to determine the characteristics of porous materials used in targets for laser plasma experiments. It is shown that the energy spectrum of alpha-particles, after their passage through porous samples, allows one to determine the distribution of their path length in the foam skeleton. We describe the procedure of deriving such a distribution, excluding both the distribution broadening due to statistical nature of the alpha-particle interaction with an atomic structure (straggling) and hardware effects. The fractal analysis of micro-images is applied to the same porous surface samples that have been studied by alpha-spectrometry. The fractal dimension and size distribution of the number of the foam skeleton grains are obtained. Using the data obtained, a distribution of the total foam skeleton thickness along a chosen direction is constructed. It roughly coincides with the path length distribution of alpha-particles within a range of larger path lengths. It is concluded that the combined use of the alpha-spectrometry method and fractal analysis of images will make it possible to determine the size distribution of foam skeleton grains (or pores). The results can be used as initial data in theoretical studies on propagation of the laser and X-ray radiation in specific porous samples. (laser plasma)

  10. Increase in the neutron yield from a dense plasma-focus experiment performed with a conical tip placed in the centre of the anode end

    Science.gov (United States)

    Kubes, P.; Paduch, M.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Rezac, K.; Zielinska, E.; Sadowski, M. J.; Szymaszek, A.; Tomaszewski, K.; Zaloga, D.

    2017-09-01

    The paper describes the evolution of self-organized structures inside a pinched plasma column during the phase of the effective production of fusion neutrons, as observed in the mega-ampere plasma focus experiment performed with a conical tip placed in the centre of the anode face. In a comparison with the plane anode face configuration, the described anode shape facilitated transformations in the pinch column during the neutron production and increased the neutron yield several times. Simultaneously, it decreased the minimal diameter and the length of the pinched column, and it depressed the first neutron pulse. It also induced shorter pulses of X-rays and neutrons, which enabled the determination of a temporal difference between the emission of electron and deuteron beams. The fast electrons were produced mainly during a disruption of the pinch constriction, while the fast deuterons - during the formation and explosion of plasmoids. The paper also presents the temporal evolution of a current distribution in the plasmoid during the neutron production, as well as the appearance and stable positions of current filaments traces upon the surface of the conical anode tip.

  11. Overview of the data-acquisition system (including shielding, isolation and grounding) on the Beta II field-reversed plasma-gun experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bell, H.H. Jr.

    1981-07-01

    Computer-supported acquisition, analysis, and storage of mirror fusion experimental data requires the solution of several problems. The data must be gathered with a minimum amount of noise, and transients must be excluded from the computer so that it can function properly. On Beta II (which was an experiment to produce field-reversed plasma rings from a coaxial plasma gun) the diagnostic system was planned to provide the shielding and isolation necessary to solve these two problems. The Beta II system has been in operation for about two years and provides 300-channel capacity, CAMAC interfaced, to a Hewlett Packard 21MX computer. The system routinely handles signals ranging from 1 mV to 50 kV, with bandwidths from .05 Hz to 10 MHz. The data are captured by transient recorders during a shot, then transferred to the computer. The computer stores the data on disc for immediate processing and on tape for long-term storage. Processed data from any number of channels (usually 20 to 30) is plotted between shots for immediate review. The rest of the data is processed and plotted during off hours.

  12. Adverse pregnancy outcome in patients with low pregnancy-associated plasma protein-A: The Indian Experience.

    Science.gov (United States)

    Gupta, Sangeeta; Goyal, Manisha; Verma, Deepti; Sharma, Anjana; Bharadwaj, Namita; Kabra, Madhulika; Kapoor, Seema

    2015-07-01

    The aim of our study was to examine the association of low pregnancy-associated plasma protein-A (PAPP-A) with adverse pregnancy outcome. A total of 1640 consecutive pregnant women between 9(+5) and 13(+6) weeks of pregnancy were recruited. One hundred and thirty women with PAPP-A levels PAPP-A and were considered as cases and 200 women with normal PAPP-A were controls. Intrauterine growth restriction was observed in 28 (21.54%) cases as compared to 10 (5%) controls. Pre-eclampsia presented in 24 (18.46%) cases and in 18 (9%) controls. Twenty (15.38%) cases had preterm delivery compared to 12 (6%) controls. Fifty-six (43.08%) cases delivered low-birthweight babies compared to 22 (11%) controls. Thus, the incidence of intrauterine growth restriction, preterm birth and low birthweight was significantly more in the cases as compared to the control group. PAPP-A is a valuable analyte for predicting risk of adverse pregnancy outcome and women with low serum PAPP-A levels would benefit from closer surveillance. © 2015 The Authors. Journal of Obstetrics and Gynaecology Research © 2015 Japan Society of Obstetrics and Gynecology.

  13. Experience of Treatments of Amanita phalloides-Induced Fulminant Liver Failure with Molecular Adsorbent Recirculating System and Therapeutic Plasma Exchange.

    Science.gov (United States)

    Zhang, Jicheng; Zhang, Ying; Peng, Zhiyong; Maberry, Donald; Feng, Xueqiang; Bian, Pengfei; Ma, Wenjuan; Wang, Chunting; Qin, Chengyong

    2014-01-01

    Ingestion of the mushroom containing Amanita phalloides can induce fulminant liver failure and death. There are no specific antidotes. Blood purifications, such as molecular adsorbent recirculating system (MARS) and therapeutic plasma exchange (TPE), are potential therapies. However, the extent to which these technologies avert the deleterious effects of amatoxins remains controversial; the optimal intensity, duration, and initiation criteria have not been determined yet. This study aimed to retrospectively observe the effects of MARS and TPE on nine patients with A. phalloides-induced fulminant liver failure. The survival rate for the nine patients was 66.7%. Both TPE and MARS might remove toxins and improve liver functions. However, a single session of TPE produced immediately greater improvements in alanine aminotransferase (-60% vs. -16.3%), aspartate aminotransferase (-47.6% vs. -15.4%), and total bilirubin (-37.3% vs. -17.1%) (compared with the values of pretreatment, all p < 0.05) than MARS compared with MARS. Early intervention may be more effective than delayed therapy. Additionally, the presence of severe liver failure and renal failure indicated worse outcome. Although these findings are promising, additional case-controlled, randomized studies are required to confirm our results.

  14. Clinical features and outcomes of plasma cell leukemia: a single-institution experience in the era of novel agents

    Directory of Open Access Journals (Sweden)

    Giampaolo Talamo

    2012-06-01

    Full Text Available Plasma cell leukemia (PCL is a rare hematologic malignancy with aggressive clinical and biologic features. Data regarding its prognosis with the use of the novel agents, i.e., the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib, are limited. We retrospectively reviewed clinical outcomes, response to therapy, and survival of 17 patients seen at the Penn State Hershey Cancer Institute since the availability of novel agents (2006-2011. Twelve patients had primary PCL (pPCL, and 5 second- ary PCL (sPCL. PCL was associated with aggressive clinicobiological features, such as high-risk cytogenetics, elevated serum beta-2-microglobulin and lactate dehydrogenase, International Staging System stage III, and rapid relapse after therapy. With the use of thalidomide, lenalidomide, and bortezomib in 53%, 53%, and 88% patients, respectively, median overall survival (OS was 18 months in the whole group (95% confidence interval, 11-21 months, and 21 and 4 months in pPCL and sPCL, respectively (P=0.015. OS was inferior to that of 313 consecutive patients with multiple myeloma (MM treated in the same period, even when compared with a subset of 47 MM with high-risk cytogenetics. Although our data are limited by the small sample size, we conclude that novel agents may modestly improve survival in patients with PCL, when compared to historical controls. Novel therapies do not seem to overcome the negative prognosis of PCL as compared with MM.

  15. Successful experiments on an external MHD Accelerator: wall confinement of the plasma, annihilation of the electrothermal instability by magnetic gradient inversion, creation of a stable spiral current pattern

    Science.gov (United States)

    Petit, Jean-Pierre; Dore, Jean-Christophe

    2013-09-01

    MHD propulsion has been extensively studied since the fifties. To shift from propulsion to an MHD Aerodyne, one only needs to accelerate the air externally, along its outer skin, using Lorentz forces. We present a set of successful experiments, obtained around a model, placed in low density air. We successfully dealt with various problems: wall confinement of two-temperature plasma obtained by inversion of the magnetic pressure gradient, annihilation of the Velikhov electrothermal instability by magnetic confinement of the streamers, establishment of a stable spiral distribution of the current, obtained by an original method. Another direction of research is devoted to the study of an MHD-controlled inlet which, coupled with a turbofan engine and implying an MHD-bypass system, would extend the flight domain to hypersonic conditions. Research manager

  16. Wire Probe Antenna (WPT) and Electric Field Detector (EFD) of Plasma Wave Experiment (PWE) aboard the Arase satellite: specifications and initial evaluation results

    Science.gov (United States)

    Kasaba, Yasumasa; Ishisaka, Keigo; Kasahara, Yoshiya; Imachi, Tomohiko; Yagitani, Satoshi; Kojima, Hirotsugu; Matsuda, Shoya; Shoji, Masafumi; Kurita, Satoshi; Hori, Tomoaki; Shinbori, Atsuki; Teramoto, Mariko; Miyoshi, Yoshizumi; Nakagawa, Tomoko; Takahashi, Naoko; Nishimura, Yukitoshi; Matsuoka, Ayako; Kumamoto, Atsushi; Tsuchiya, Fuminori; Nomura, Reiko

    2017-12-01

    This paper summarizes the specifications and initial evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), the key components for the electric field measurement of the Plasma Wave Experiment (PWE) aboard the Arase (ERG) satellite. WPT consists of two pairs of dipole antennas with 31-m tip-to-tip length. Each antenna element has a spherical probe (60 mm diameter) at each end of the wire (15 m length). They are extended orthogonally in the spin plane of the spacecraft, which is roughly perpendicular to the Sun and enables to measure the electric field in the frequency range of DC to 10 MHz. This system is almost identical to the WPT of Plasma Wave Investigation aboard the BepiColombo Mercury Magnetospheric Orbiter, except for the material of the spherical probe (ERG: Al alloy, MMO: Ti alloy). EFD is a part of the EWO (EFD/WFC/OFA) receiver and measures the 2-ch electric field at a sampling rate of 512 Hz (dynamic range: ± 200 mV/m) and the 4-ch spacecraft potential at a sampling rate of 128 Hz (dynamic range: ± 100 V and ± 3 V/m), with the bias control capability of WPT. The electric field waveform provides (1) fundamental information about the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves in various magnetospheric statuses with the magnetic field measured by MGF and PWE-MSC. The spacecraft potential provides information on thermal electron plasma variations and structure combined with the electron density obtained from the upper hybrid resonance frequency provided by PWE-HFA. EFD has two data modes. The continuous (medium-mode) data are provided as (1) 2-ch waveforms at 64 Hz (in apoapsis mode, L > 4) or 256 Hz (in periapsis mode, L < 4), (2) 1-ch spectrum within 1-232 Hz with 1-s resolution, and (3) 4-ch spacecraft potential at 8 Hz. The burst (high-mode) data are intermittently obtained as (4) 2-ch waveforms at 512 Hz and (5) 4-ch spacecraft potential at 128 Hz and downloaded with the WFC

  17. Texas Experimental Tokamak, a plasma research facility: Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, A.J.

    1995-08-01

    In the year just past, the authors made major progress in understanding turbulence and transport in both core and edge. Development of the capability for turbulence measurements throughout the poloidal cross section and intelligent consideration of the observed asymmetries, played a critical role in this work. In their confinement studies, a limited plasma with strong, H-mode-like characteristics serendipitously appeared and received extensive study though a diverted H-mode remains elusive. In the plasma edge, they appear to be close to isolating a turbulence drive mechanism. These are major advances of benefit to the community at large, and they followed from incremental improvements in diagnostics, in the interpretation of the diagnostics, and in TEXT itself. Their general philosophy is that the understanding of plasma physics must be part of any intelligent fusion program, and that basic experimental research is the most important part of any such program. The work here demonstrates a continuing dedication to the problems of plasma transport which continue to plague the community and are an impediment to the design of future devices. They expect to show here that they approach this problem consistently, systematically, and effectively.

  18. Cell bricks-enriched platelet-rich plasma gel for injectable cartilage engineering - an in vivo experiment in nude mice.

    Science.gov (United States)

    Zhu, Jun; Cai, Bolei; Ma, Qin; Chen, Fulin; Wu, Wei

    2013-10-01

    Clinical application of platelet-rich plasma (PRP)-based injectable tissue engineering is limited by weak mechanical properties and a rapid fibrinolytic rate. We proposed a new strategy, a cell bricks-stabilized PRP injectable system, to engineer and regenerate cartilage with stable morphology and structure in vivo. Chondrocytes from the auricular cartilage of rabbits were isolated and cultured to form cell bricks (fragmented cell sheet) or cell expansions. Fifteen nude mice were divided evenly (n = 5) into cells-PRP (C-P), cell bricks-PRP (CB-P) and cell bricks-cells-PRP (CB-C-P) groups. Cells, cell bricks or a cell bricks/cells mixture were suspended in PRP and were injected subcutaneously in animals. After 8 weeks, all the constructs were replaced by white resilient tissue; however, specimens from the CB-P and CB-C-P groups were well maintained in shape, while the C-P group appeared distorted, with a compressed outline. Histologically, all groups presented lacuna-like structures, glycosaminoglycan-enriched matrices and positive immunostaining of collagen type II. Different from the uniform structure presented in CB-C-P samples, CB-P presented interrupted, island-like chondrogenesis and contracted structure; fibrous interruption was shown in the C-P group. The highest percentage of matrix was presented in CB-C-P samples. Collagen and sGAG quantification confirmed that the CB-C-P constructs had statistically higher amounts than the C-P and CB-P groups; statistical differences were also found among the groups in terms of biomechanical properties and gene expression. We concluded that cell bricks-enriched PRP gel sufficiently enhanced the morphological stability of the constructs, maintained chondrocyte phenotypes and favoured chondrogenesis in vivo, which suggests that such an injectable, completely biological system is a suitable cell carrier for cell-based cartilage repair. Copyright © 2012 John Wiley & Sons, Ltd.

  19. The Center for Momentum Transport and Flow Organization in Plasmas - Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Munsat, Tobin [Univ. of Colorado, Boulder, CO (United States)

    2015-12-14

    fields, all of the instabilities co-exist, leading to rich plasma dynamics and fully developed broadband turbulence. Edge-Turbulence and Flow Experiments in NSTX: A series of Gas Puff Imaging (GPI) observations on NSTX revealed a quasi-periodic oscillation in the plasma edge preceding the L-H transition in a limited set of neutral beam heated plasmas. These ~3 kHz flow oscillations exhibit both long wavelength and long correlation lengths, suggesting they are zonal-flow-like. The flow oscillations are strongly correlated with modulations of the level of edge turbulence, thus the system appears to undergo a predator--prey-type limit-cycle preceding the L-H transition. However, a clear trigger for the L-H transition was not observed. Reynolds stress profiles were obtained directly from image velocimetry for L-mode periods ELM-Precursor Studies in NSTX: A separate study based on NSTX-GPI data captured the two-dimensional evolution of edge-localized mode (ELM) precursors. Precursor events were observed preceding ELMs and ELM-induced H–L back-transitions in radio-frequency heated H-mode plasmas, and the growth of the precursor mode through the ELM filamentation was imaged in the plane perpendicular to the local B-field. Strong edge intensity modulations appeared to propagate in the electron diamagnetic direction while steadily drifting radially outwards. Intensity fluctuations were observed at frequencies around 20 kHz and wavenumbers of 0.05-0.2 cm-1. Upon growing to a trigger point, precursor fluctuations were seen to form filamentary structures and move into the scrape-off layer (SOL) explosively with radial velocities peaking at 8 km/s. Once in the SOL, filaments reverse their propagation direction and travel in the ion diamagnetic direction. Edge intensity fluctuations were strongly correlated with magnetic signals from Mirnov coils, and toroidally distributed coils estimated toroidal mode numbers of n=5-10. Quantitatively similar precursors have been

  20. Transport simulation of ELM pacing by pellet injection in tokamak plasmas

    Science.gov (United States)

    Kim, Ki Min; Na, Yong-Su; Hong, Sang Hee; Lang, P. T.; Alper, B.; contributors, JET-EFDA

    2010-05-01

    This paper deals mainly with the numerical simulation on edge localized mode (ELM) pacing by pellet injection that is useful for fuelling and control of plasma profiles to achieve enhanced tokamak operations. The fuelling and pellet-induced ELMs are simulated with a 1.5-dimensional core transport code, which includes a neutral gas shielding model and a grad-B drift model for pellet deposition in H-mode tokamak plasmas. Fuelling and ELM pacing experiments by pellet injections at JET are introduced as a current experimental approach. For the description of ELM triggering by pellet injection based on ideal ballooning mode criteria, three possible models are suggested and discussed on their ELM characteristics, respectively: (i) the density enhanced ELMs in the post-pellet phase, (ii) the modification of the surface averaged pressure profiles in a transport time scale and (iii) the local increase in the pressure (density and/or temperature) gradients perturbed by pellets. Among them, the pellet-induced density perturbation model is adopted, in practice, to carry out an ELM pacing simulation in preparation for future experiments in KSTAR. The numerical simulation shows that the artificially induced ELM by pellets releases the reduced energy bursts, compared with spontaneous ELMs. The energy loss per burst by the pellet-induced ELM turns out to be much smaller than that by the spontaneous ELM as the pellet injection frequency becomes higher in ELM pacing. Based on the simulation results showing good agreement with the general ELM characteristics observed in pellet pacing experiments, the ELM pacing by pellet injection is very promising for mitigating the ELM energy bursts to the divertor by controlling the injection frequency.

  1. Plasma Redistribution in the M-I-T System during Magnetic Storms: Evidence from Experiments and Modeling

    Science.gov (United States)

    Basu, S.; Valladares, C. E.; Basu, S.; MacKenzie, E. M.; Scherliess, L.; Gardner, L. C.; Coster, A. J.; Schunk, R. W.

    2013-05-01

    Thermal plasma redistribution in the coupled magnetosphere-ionosphere-thermosphere system during magnetic storms is a topic of great current interest. We present both experimental and modeling evidence for such redistribution in the main phase of two moderate storms, in the rising part of the current solar cycle, to provide a better understanding of the electrodynamics involved. The first of these storms on Aug 3-4, 2010 (when solar flux was 80 units) combined the mid and low-latitude TEC obtained from the dense network of GPS stations within North America including Mexico with an array of GPS receivers forming part of the Low Latitude Ionospheric Sensor Network (LISN) in South America together with the COCONET in the Caribbean (Su. Basu et al., presented at AGU Fall Meeting, 2012). Similar TEC observations are shown for the magnetic storm of September 26-27, 2011 when the solar flux was 50 per cent larger and DMSP-measured in-situ velocities were high. At mid latitudes the prompt penetration for both storms occurred during photo-production in the afternoon hours in the American sector, was associated with storm enhanced density (SED) and TEC plumes that traveled from the SE to NW across North America. At equatorial to low latitudes, a second TEC enhancement was observed which seemed to be unrelated to the SED. The USU Global Assimilation of Ionospheric Measurements Full-Physics model (GAIM-FP) was used to model the stormtime evolution of the equatorial and low and mid-latitude ionosphere during the Aug 3-4, 2010 and Sept 26-27, 2011 storm events. The model is based on an Ensemble Kalman filter technique and a physics-based model of the ionosphere/plasmasphere (IPM), which covers the altitude range from 90 to 20,000 km. In the current study the model assimilated a multitude of ground- and space-based ionospheric observations including the ground-based GPS observations from the South American LISN network and the North American CORS network to specify the morphology

  2. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Mark Allen [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-02-05

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB’s)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB’s] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  3. Plasma harmonics

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    Preface; Why plasma harmonics? A very brief introduction Early stage of plasma harmonic studies - hopes and frustrations New developments in plasma harmonics studies: first successes Improvements of plasma harmonics; Theoretical basics of plasma harmonics; Basics of HHG Harmonic generation in fullerenes using few-cycle pulsesVarious approaches for description of observed peculiarities of resonant enhancement of a single harmonic in laser plasmaTwo-colour pump resonance-induced enhancement of odd and even harmonics from a tin plasmaCalculations of single harmonic generation from Mn plasma;Low-o

  4. Introduction to Complex Plasmas

    CERN Document Server

    Bonitz, Michael; Ludwig, Patrick

    2010-01-01

    Complex plasmas differ from traditional plasmas in many ways: these are low-temperature high pressure systems containing nanometer to micrometer size particles which may be highly charged and strongly interacting. The particles may be chemically reacting or be in contact with solid surfaces, and the electrons may show quantum behaviour. These interesting properties have led to many applications of complex plasmas in technology, medicine and science. Yet complex plasmas are extremely complicated, both experimentally and theoretically, and require a variety of new approaches which go beyond standard plasma physics courses. This book fills this gap presenting an introduction to theory, experiment and computer simulation in this field. Based on tutorial lectures at a very successful recent Summer Institute, the presentation is ideally suited for graduate students, plasma physicists and experienced undergraduates.

  5. Therapeutic plasma exchange plus corticosteroid for the treatment of the thrombotic thrombocytopenic purpura: a single institutional experience in the southern Marmara region of Turkey.

    Science.gov (United States)

    Ozkalemkas, Fahir; Ali, Ridvan; Ozkocaman, Vildan; Ozcelik, Tulay; Ozkan, Atilla; Tunali, Ahmet

    2007-02-01

    Thrombotic thrombocytopenic purpura (TTP) is a classic, but not a common disorder of hematology. Plasma exchange (PE) was shown to nearly reverse its 90% mortality rate. However, there are still some fatal outcomes in this dramatic disease. We present our experience of plasma exchange plus corticosteroids for the treatment of TTP in our hospital. Patients with TTP diagnosed between January 1996 and January 2005 were identified by a retrospective review of records of the Uludag University Hospital, Bursa (the largest referral center for adults with this disorder in this region with an estimated 2.2 million residents), which performs all therapeutic PE in the southern Marmara region in Turkey. A total of 11 (6 male, 5 female) patients were treated for TTP during this period. The median age was 39 years (range 18-49). One plasma volume exchange daily plus steroid was the principle treatment in all patients. A total of 295 PE sessions were performed. We have obtained six complete responses (CR) and three partial responses (PR) with daily PE and steroid (response rate 9/11). One of our primary refractory patients was saved with pulse steroid+cyclosporine+vincristine. Now, he is disease free for over one year. The other refractory patient did not develop any response to salvage therapy and expired on day 15 with status epilepticus and ventilator related pneumonia (mortality rate 1/11). A CR was obtained with adjuvant treatments in all three PR patients. Only one CR patient developed an early relapse (early relapse rate in CR patients 1/6). She was treated successfully with daily PE plus vincristine. Our median follow up period was 25 months (range 9-108). Considering our local population, our annual incidence is only about 0.63 new cases per one million people. This figure is considerably less than the data from US, which indicated an incidence of 3.7 cases per 1,000,000. To our knowledge, there is no high variability in the incidence of TTP in the different geographical

  6. The density limit in JET diverted plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, D.J.; Clement, S.; Gottardi, N.; Gowers, C.; Harbour, P.; Loarte, A.; Horton, L.; Lingertat, J.; Lowry, C.G.; Saibene, G.; Stamp, M.; Stork, D. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Monk, R. [Royal Holloway Coll., London (United Kingdom). Dept. of Physics

    1994-07-01

    In JET limiter plasmas the density limit is associated with radiated power fractions of 100% and, in plasmas with carbon limiters, it is invariably disruptive. However, in discharges with solid beryllium limiters the limit is identified with the formation of a MARFE and disruptions are less frequent. In addition, the improved conditioning of the vessel arising from the use of beryllium has significantly improved the density limit scaling, so that the maximum density rises with the square root of the input power. In diverted plasmas several confinement regimes exist, making the characterization of the density limit more complex. While the density limit in L-mode plasmas is generally disruptive, the limit in ELMy and ELM-free H-modes generally prompts a return to the L-mode and a disruption is not inevitable. The density limit does rise with the increasing power, but the L-to-H transition complicates the analysis. Nevertheless, at low plasma currents (<2 MA), densities significantly above the Greenwald limit can be achieved, while at higher currents power handling limitations have constrained the range of density which can be achieved. (authors). 7 refs., 4 figs.

  7. Measurements of hard probes of the quark-gluon plasma with the ATLAS experiment at the LHC

    CERN Document Server

    Wosiek, B; The ATLAS collaboration

    2016-01-01

    ATLAS results on the production of high-transverse momentum probes in Pb+Pb and p+Pb collisions at the LHC are presented. The focus is on the jet measurements, which provide a useful tool to study the hot, dense and coloured matter created in ultra-relativistic heavy ion collisions. The ATLAS experiment has measured inclusive jet yields in pp and Pb+Pb collisions at sqrt(s_NN) = 2.76 TeV and in p+Pb collisions at sqrt(s_NN) = 5.02 TeV. The jet nuclear modification factor, RAA, is shown as a function of jet pT, rapidity and collision centrality. The RAA weakly increases with pT, shows no dependence on rapidity and smoothly decreases with the collision centrality. In 10% of the most central collisions, jet production is suppressed by a factor of two relative to pp yields scaled by the number of binary nucleonnucleon collisions. Charged-particle fragmentation functions of jets are also measured and ratios of fragmentation functions between di erent centrality intervals show a centrality-dependent modification. T...

  8. Overview of Results from the National Spherical Torus Experiment (NSTX)

    Energy Technology Data Exchange (ETDEWEB)

    Gates, D; Ahn, J; Allain, J; Andre, R; Bastasz, R; Bell, M; Bell, R; Belova, E; Berkery, J; Betti, R; Bialek, J; Biewer, T; Bigelow, T; Bitter, M; Boedo, J; Bonoli, P; Bozzer, A; Brennan, D; Breslau, J; Brower, D; Bush, C; Canik, J; Caravelli, G; Carter, M; Caughman, J; Chang, C; Choe, W; Crocker, N; Darrow, D; Delgado-Aparicio, L; Diem, S; D' Ippolito, D; Domier, C; Dorland, W; Efthimion, P; Ejiri, A; Ershov, N; Evans, T; Feibush, E; Fenstermacher, M; Ferron, J; Finkenthal, M; Foley, J; Frazin, R; Fredrickson, E; Fu, G; Funaba, H; Gerhardt, S; Glasser, A; Gorelenkov, N; Grisham, L; Hahm, T; Harvey, R; Hassanein, A; Heidbrink, W; Hill, K; Hillesheim, J; Hillis, D; Hirooka, Y; Hosea, J; Hu, B; Humphreys, D; Idehara, T; Indireshkumar, K; Ishida, A; Jaeger, F; Jarboe, T; Jardin, S; Jaworski, M; Ji, H; Jung, H; Kaita, R; Kallman, J; Katsuro-Hopkins, O; Kawahata, K; Kawamori, E; Kaye, S; Kessel, C; Kim, J; Kimura, H; Kolemen, E; Krasheninnikov, S; Krstic, P; Ku, S; Kubota, S; Kugel, H; La Haye, R; Lao, L; LeBlanc, B; Lee, W; Lee, K; Leuer, J; Levinton, F; Liang, Y; Liu, D; Luhmann, N; Maingi, R; Majeski, R; Manickam, J; Mansfield, D; Maqueda, R; Mazzucato, E; McCune, D; McGeehan, B; McKee, G; Medley, S; Menard, J; Menon, M; Meyer, H; Mikkelsen, D; Miloshevsky, G; Mitarai, O; Mueller, D; Mueller, S; Munsat, T; Myra, J; Nagayama, Y; Nelson, B; Nguyen, X; Nishino, N; Nishiura, M; Nygren, R; Ono, M; Osborne, T; Pacella, D; Park, H; Park, J; Paul, S; Peebles, W; Penaflor, B; Peng, M; Phillips, C; Pigarov, A; Podesta, M; Preinhaelter, J; Ram, A; Raman, R; Rasmussen, D; Redd, A; Reimerdes, H; Rewoldt, G; Ross, P; Rowley, C; Ruskov, E; Russell, D; Ruzic, D; Ryan, P; Sabbagh, S; Schaffer, M; Schuster, E; Scott, S; Shaing, K; Sharpe, P; Shevchenko, V; Shinohara, K; Sizyuk, V; Skinner, C; Smirnov, A; Smith, D; Smith, S; Snyder, P; Soloman, W; Sontag, A; Soukhanovskii, V; Stoltzfus-Dueck, T; Stotler, D; Strait, T; Stratton, B; Stutman, D; Takahashi, R; Takase, Y; Tamura, N; Tang, X; Taylor, G; Taylor, C; Ticos, C; Tritz, K; Tsarouhas, D; Turrnbull, A; Tynan, G; Ulrickson, M; Umansky, M; Urban, J; Utergberg, E; Walker, M; Wampler, W; Wang, J; Wang, W; Weland, A

    2009-01-05

    The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high {beta} operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies confirm the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l{sub i} {approx} 0.4 with strong shaping ({kappa} {approx} 2.7, {delta} {approx} 0.8) with {beta}{sub N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f{sub NI} {approx} 71%. Instabilities driven by super-Alfvenic ions are an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvenic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. RWM/RFA feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with {beta} above the no-wall limit. The impact of n > 1 error fields on stability is a important result for ITER. Other highlights are

  9. Overview of Results from the National Spherical Torus Experiment (NSTX)

    Energy Technology Data Exchange (ETDEWEB)

    Gates, D. A.; Ahn, J.; Allain, J.; Andre, R.; Bastasz, R.; Bell, M.; Bell, R.; Belova, E.; Berkery, J.; Betti, R.; Bialek, J.; Biewer, T.; Bigelow, T.; Bitter, M.; Choe, W.; Crocker, N.; Darrow, D.; Delgado-Aparicio, L.; Diem, S.; D’Ippolito, D.; Domier, C.; Dorland, W.; Efthimion, P.; Ejiri, A.; Ershov, N.; Evans, T.; Feibush, E.; Fenstermacher, M.; Ferron, J.; Finkenthal, M.; Foley, J.; Frazin, R.; Fredrickson, E.; Fu, G.; Funaba, H.; Gerhardt, S.; Glasser, A.; Gorelenkov, N.; Grisham, L.; Hahm, T.; Harvey, R.; Hassanein, A.; Heidbrink, W.; Hill, K.; Hillesheim, J.; Hillis, D.; Hirooka, Y.; Hu, B.; Humphreys, D.; Idehara, T.; Indireshkumar, K.; Ishida, A.; Jaeger, F.; Jarboe, T.; Jardin, S.; Jaworski, M.; Ji, H.; Jung, H.; Kaita, R.; Kallman, J.; Katsuro-Hopkins, O.; Kawahata, K.; Kawamori, E.; Kaye, S.; Kessel, C.; Kim, J.; Kimura, H.; Kolemen, E.; Krasheninnikov, S.; Krstic, P.; Ku, S.; Kubota, S.; Kugel, H.; La Haye, R.; Lao, L.; LeBlanc, B.; Lee, W.; Lee, K.; Leuer, J.; Levinton, F.; Liang, Y.; Liu, D.; Luhmann, Jr., N.; Maingi, R.; Majeski, R.; Manickam, J.; Mansfield, D.; Maqueda, R.; Mazzucato, E.; McCune, D.; McGeehan, B.; McKee, G.; Medley, S.; Menard, J.; Menon, M.; Meyer, H.; Mikkelsen, D.; Miloshevsky, G.; Mitarai, O.; Mueller, D.; Mueller, S.; Munsat, T.; Myra, J.; Nagayama, Y.; Nelson, B.; Nguyen, X.; Nishino, N.; Nishiura, M.; Nygren, R.; Ono, M.; Osborne, T.; Pacella, D.; Park, H.; Park, J.; Paul, S.; Peebles, W.; Penaflor, B.; Peng, M.; Phillips, C.; Pigarov, A.; Podesta, M.; Preinhaelter, J.; Ram, A.; Raman, R.; Rasmussen, D.; Redd, A.; Reimerdes, H.; Rewo, G.; Ross, P.; Rowley, C.; Ruskov, E.; Russell, D.; Ruzic, D.; Ryan, P.; Sabbagh, S.; Schaffer, M.; Schuster, E.; Scott, S.; Shaing, K.; Sharpe, P.; Shevchenko, V.; Shinohara, K.; Sizyuk, V.; Skinner, C.; Smirnov, A.; Smith, D.; Smith, S.; Snyder, P.; Solomon, W.; Sontag, A.; Soukhanovskii, V.; Stoltzfus-Dueck, T.; Stotler, D.; Strait, T.; Stratton, B.; Stutman, D.; Takahashi, R.; Takase, Y.; Tamura, N.; Tang, X.; Taylor, G.; Taylor, C.; Ticos, C.; Tritz, K.; Tsarouhas, D.; Turrnbull, A.; Tynan, G.; Ulrickson, M.; Umansky, M.; Urban, J.; Utergberg, E.; Walker, M.; Wampler, W.; Wang, J.; Wang, W.; Welander, A.; Whaley, J.; White, R.; Wilgen, J.; Wilson, R.; Wong, K.; Wright, J.; Xia, Z.; Xu, X.; Youchison, D.; Yu, G.; Yuh, H.; Zakharov, L.; Zemlyanov, D.; Zweben, S.

    2009-03-24

    The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ~0.4 with strong shaping (κ ~ 2.7, δ ~ 0.8) with βN approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ~71%. Instabilities driven by super-Alfv´enic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfv´enic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. The impact of n > 1 error fields on stability is a important result for ITER. RWM/RFA feedback combined with n=3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are: results

  10. Simulations of plasma response to RMP with BOUT + + code

    Science.gov (United States)

    Gui, Bin; Xu, Xueqiao

    2013-10-01

    BOUT + + code is a framework which developed to simulate 3-dimenisonal fluid equations in curvilinear coordinates (Dudson, et al., Computer Physics Communications, 2009). Here we developed an ideal two-field model (vorticity and Ampere's law) to simulate the influence of resonant magnetic perturbation (RMP) on the pedestal plasmas. The vacuum RMP field is self-consistently calculated and included in the two-field model. The current sheets at resonant surface are found, and the radial magnetic field distribution of vacuum RMP and total magnetic field strength are compared. The influence of resistivity on the current sheets is also studied in this model. Based on this work, the radial magnetic field perturbation includes the vacuum RMP component and plasma response in the pedestal region is obtained. By applying the magnetic field perturbation in the peeling-ballooning mode simulation, the influence of RMP on the pedestal plasma could be studied in L-mode, H-mode and ELM discharges.

  11. Simulation of triton burn-up in JET plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Loughlin, M.J.; Balet, B.; Jarvis, O.N.; Stubberfield, P.M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    This paper presents the first triton burn-up calculations for JET plasmas using the transport code TRANSP. Four hot ion H-mode deuterium plasmas are studied. For these discharges, the 2.5 MeV emission rises rapidly and then collapses abruptly. This phenomenon is not fully understood but in each case the collapse phase is associated with a large impurity influx known as the ``carbon bloom``. The peak 14 MeV emission occurs at this time, somewhat later than that of the 2.5 MeV neutron peak. The present results give a clear indication that there are no significant departures from classical slowing down and spatial diffusion for tritons in JET plasmas. (authors). 7 refs., 3 figs., 1 tab.

  12. Nonlinear phenomena, turbulence and anomalous transport in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo, C.; Estrada, T.; Sanchez, E.; Branas, B.; Garcia-Cortes, I.; Van Milligen, B.P.; Balbin, R.; Pedrosa, M.A.; Sanchez, J. [Asociancion Euratom-Ciemat, Madrid (Spain); Carreras, B.A. [Oak Ridge National Lab., TN (United States)] [and others

    1995-02-01

    The nonlinear nature of the plasma turbulence, as measured by bicoherence analysis, has been studied in stellarator (ATF and W7AS) and tokamak (PBXM) devices. In ATF, little nonlinear interaction is found in the scrape-off layer region whereas the strength of the coupling is enhanced in the edge plasma region where the level of fluctuations is consistent with the theoretical expectations from resistive interchange modes. In W7AS the level of bicoherence is significantly smaller than in ATF. The comparison ATF/W7AS/PBXM suggest the important role of the magnetic shear to determine nonlinear behavior of the turbulence. The level of bicoherence also depends on the plasma conditions: in particular, it increases at the H-mode transition. The comparison between the nonlinear behavior of the turbulence in tokamaks and stellarators allows experimental verification of theoretical turbulence models.

  13. Leak tightness tests on actively cooled plasma facing components: Lessons learned from Tore Supra experience and perspectives for the new fusion machines

    Energy Technology Data Exchange (ETDEWEB)

    Chantant, M., E-mail: michel.chantant@cea.fr; Lambert, R.; Gargiulo, L.; Hatchressian, J.-C.; Guilhem, D.; Samaille, F.; Soler, B.

    2015-10-15

    Highlights: • Test procedures for the qualification of the tightness of actively cooled plasma facing components were defined. • The test is performed after the component manufacturing and before its set-up in the vacuum vessel. • It allows improving the fusion machine availability. • The lessons of tests over 20 years at Tore Supra are presented. - Abstract: The fusion machines under development or construction (ITER, W7X) use several hundreds of actively cooled plasma facing components (ACPFC). They are submitted to leak tightness requirements in order to get an appropriate vacuum level in the vessel to create the plasma. During the ACPFC manufacturing and before their installation in the machine, their leak tightness performance must be measured to check that they fulfill the vacuum requirements. A relevant procedure is needed which allows to segregate potential defects. It must also be optimized in terms of test duration and costs. Tore Supra, as an actively cooled Tokamak, experienced several leaks on ACPFCs during the commissioning and during the operation of the machine. A test procedure was then defined and several test facilities were set-up. Since 1990 the tightness of all the new ACPFCs is systematically tested before their installation in Tore Supra. During the qualification test, the component is set up in a vacuum test tank, and its cooling circuits are pressurized with helium. It is submitted to 3 temperature cycles from room temperature up to the baking temperature level in Tore Supra (200 °C) and two pressurization tests are performed (6 MPa at room temperature and 4 MPa at 200 °C) at each stage. At the end of the last cycle when the ACPFC is at room temperature and pressurized with helium at 6 MPa, the measured leak rate must be lower than 5 × 10{sup −11} Pa m{sup 3} s{sup −1}, the pressure in the test tank being <5 × 10{sup −5} Pa. A large experience has been gained on ACPFCs with carbon parts on stainless steel and Cu

  14. Princeton Plasma Physics Laboratory:

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, C.A. (ed.)

    1986-01-01

    This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

  15. Leo space plasma interactions

    Science.gov (United States)

    Ferguson, Dale C.

    1991-01-01

    Photovoltaic arrays interact with the low earth orbit (LEO) space plasma in two fundamentally different ways. One way is the steady collection of current from the plasma onto exposed conductors and semiconductors. The relative currents collected by different parts of the array will then determine the floating potential of the spacecraft. In addition, these steady state collected currents may lead to sputtering or heating of the array by the ions or electrons collected, respectively. The second kind of interaction is the short time scale arc into the space plasma, which may deplete the array and/or spacecraft of stored charge, damage solar cells, and produce EMI. Such arcs only occur at high negative potentials relative to the space plasma potential, and depend on the steady state ion currents being collected. New high voltage solar arrays being incorporated into advanced spacecraft and space platforms may be endangered by these plasma interactions. Recent advances in laboratory testing and current collection modeling promise the capability of controlling, and perhaps even using, these space plasma interactions to enable design of reliable high voltage space power systems. Some of the new results may have an impact on solar cell spacing and/or coverslide design. Planned space flight experiments are necessary to confirm the models of high voltage solar array plasma interactions. Finally, computerized, integrated plasma interactions design tools are being constructed to place plasma interactions models into the hands of the spacecraft designer.

  16. Overview of EAST experiments on the development of high-performance steady-state scenario

    Science.gov (United States)

    Wan, B. N.; Liang, Y. F.; Gong, X. Z.; Li, J. G.; Xiang, N.; Xu, G. S.; Sun, Y. W.; Wang, L.; Qian, J. P.; Liu, H. Q.; Zhang, X. D.; Hu, L. Q.; Hu, J. S.; Liu, F. K.; Hu, C. D.; Zhao, Y. P.; Zeng, L.; Wang, M.; Xu, H. D.; Luo, G. N.; Garofalo, A. M.; Ekedahl, A.; Zhang, L.; Zhang, X. J.; Huang, J.; Ding, B. J.; Zang, Q.; Li, M. H.; Ding, F.; Ding, S. Y.; Lyu, B.; Yu, Y. W.; Zhang, T.; Zhang, Y.; Li, G. Q.; Xia, T. Y.; the EAST Team; Collaborators

    2017-10-01

    The EAST research program aims to demonstrate steady-state long-pulse advanced high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. Since the 2014 IAEA FEC, EAST has been upgraded with all ITER-relevant auxiliary heating and current drive systems, enabling the investigation of plasma profile control by the coupling/integration of various auxiliary heating combinations. Fully non-inductive steady-state H-mode plasma (H 98,y2  >  1.1) was extended over 60 s for the first time with sole RF heating plus good power coupling and impurity and particle control. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and maintained at relatively high density, even up to n e ~ 4.5  ×  1019 m-3, where a current drive effect is still observed. Significant progress has been achieved on EAST, including: (i) demonstration of a steady-state scenario (fully non-inductive with V loop ~ 0.0 V at high β P ~ 1.8 and high-performance in upper single-null (ɛ ~ 1.6) configuration with the tungsten divertor; (ii) discovery of a stationary H-mode regime with no/small ELM using 4.6 GHz LHCD, and; (iii) achievement of ELM suppression in slowly rotating H-mode plasma with n  =  1 and 2 RMP compatible with long-pulse operations. The new advances in scenario development provide an integrated solution in achieving long-pulse steady-state operations on EAST.

  17. Minority heating scenarios in ^4He(H) and ^3He(H) SST-1 plasmas

    Science.gov (United States)

    Chattopadhyay, Asim Kumar

    2018-01-01

    A numerical analysis of ion cyclotron resonance heating scenarios in two species of low ion temperature plasma has been done to elucidate the physics and possibility to achieve H-mode in tokamak plasma. The analysis is done in the steady-state superconducting tokamak, SST-1, using phase-I plasma parameters which is basically L-mode plasma parameters having low ion temperature and magnetic field with the help of the ion cyclotron heating code TORIC combined with `steady state Fokker-Planck quasilinear' (SSFPQL) solver. As a minority species hydrogen has been used in ^3He and ^4He plasmas to make two species ^3He(H) and ^4He(H) plasmas to study the ion cyclotron wave absorption scenarios. The minority heating is predominant in ^3He(H) and ^4He(H) plasmas as minority resonance layers are not shielded by ion-ion resonance and cut-off layers in both cases, and it is better in ^4He(H) plasma due to the smooth penetration of wave through plasma-vacuum surface. In minority concentration up to 15%, it has been observed that minority ion heating is the principal heating mechanism compared to electron heating and heating due to mode conversion phenomena. Numerical analysis with the help of SSFPQL solver shows that the tail of the distribution function of the minority ion is more energetic than that of the majority ion and therefore, more anisotropic. Due to good coupling of the wave and predominance of the minority heating regime, producing energetic ions in the tail region of the distribution function, the ^4He(H) and ^3He(H) plasmas could be studied in-depth to achieve H-mode in two species of low-temperature plasma.

  18. Plasma astrophysics

    CERN Document Server

    Kaplan, S A; ter Haar, D

    2013-01-01

    Plasma Astrophysics is a translation from the Russian language; the topics discussed are based on lectures given by V.N. Tsytovich at several universities. The book describes the physics of the various phenomena and their mathematical formulation connected with plasma astrophysics. This book also explains the theory of the interaction of fast particles plasma, their radiation activities, as well as the plasma behavior when exposed to a very strong magnetic field. The text describes the nature of collective plasma processes and of plasma turbulence. One author explains the method of elementary

  19. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  20. Basic plasma physics

    CERN Document Server

    Ghosh, Basudev

    2014-01-01

    Basic Plasma Physics is designed to serve as an introductory compact textbook for advanced undergraduate, postgraduate and research students taking plasma physics as one of their subject of study for the first time. It covers the current syllabus of plasma physics offered by the most universities and technical institutions. The book requires no background in plasma physics but only elementary knowledge of basic physics and mathematics. Emphasis has been given on the analytical approach. Topics are developed from first principle so that the students can learn through self-study. One chapter has been devoted to describe some practical aspects of plasma physics. Each chapter contains a good number of solved and unsolved problems and a variety of review questions, mostly taken from recent examination papers. Some classroom experiments described in the book will surely help students as well as instructors.

  1. Project and analysis of the toroidal magnetic field production circuits and the plasma formation of the ETE (Spherical Tokamak Experiment) tokamak; Projeto e analise dos circuitos de producao de campo magnetico toroidal e de formacao do plasma do Tokamak ETE (Experimento Tokamak Esferico)

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Luis Filipe F.P.W.; Bosco, Edson del

    1994-12-31

    This report presents the project and analysis of the circuit for production of the toroidal magnetic field in the Tokamak ETE (Spherical Tokamak Experiment). The ETE is a Tokamak with a small-aspect-ratio parameter to be used for studying the plasma physics for the research on thermonuclear fusion. This machine is being constructed at the Laboratorio Associado de Plasma (LAP) of the Instituto Nacional de Pesquisas Espaciais (INPE) in Sao Jose dos Campos, SP, Brazil. (author). 20 refs., 39 figs., 4 tabs.

  2. Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

    Energy Technology Data Exchange (ETDEWEB)

    Brombin, M., E-mail: matteo.brombin@igi.cnr.it; Spolaore, M.; Serianni, G.; Pomaro, N.; Taliercio, C.; Palma, M. Dalla; Pasqualotto, R. [Consorzio RFX, Corso Stati Uniti 4, I-35127 Padova (Italy); Schiesko, L. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

    2014-11-15

    A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors’ holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.

  3. Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

    Science.gov (United States)

    Brombin, M.; Spolaore, M.; Serianni, G.; Pomaro, N.; Taliercio, C.; Palma, M. Dalla; Pasqualotto, R.; Schiesko, L.

    2014-11-01

    A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors' holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.

  4. Stability and transport in magnetic confined plasmas; estabilidad y transporte en plasmas confinados magneticamente

    Energy Technology Data Exchange (ETDEWEB)

    Martinell, J.J.; Herrera, J.J.E.; Morozov, D.K.; Soboleva, T.K.; Vitela, E. [Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, A.P. 70-543, 04510 Mexico D.F. (Mexico)

    2000-07-01

    A tokamak is a device with a toroidal geometry that uses magnetic fields to confine a plasma inside a vacuum chamber, in order to produce thermonuclear fusion reactions, releasing large amounts of energy, larger than that employed in operating the device. There are two fundamental problems that have prevented us from achieving this goal: (1) the appearance of different instabilities that are capable of destroying confinement, and (2) the great energy losses resulting from transport to the plasma edge. For several years there has been an enormous effort to study the complex physics behind these two phenomena in order to understand the way they affect the plasma so it is possible to control the unwanted effects. In this Project, different aspects of the Tokamak plasma physics are studied, namely: (a) the transition phenomenon to an improved confinement mode (H mode), (b) the effect impurities have on plasma dynamics in the cooler edge region, (c) the processes leading to a detached divertor regime, which makes energy extraction more efficient, and (d) the burn control of a future nuclear fusion reactor using neural networks. All these are important problems and have to be well understood before the design and construction of a tokamak-based thermonuclear reactor can be undertaken. (Author)

  5. Nonequilibrium Phenomena in Plasmas

    CERN Document Server

    Sharma, A Surjalal

    2005-01-01

    The complexity of plasmas arises mainly from their inherent nonlinearity and far from equilibrium nature. The nonequilibrium behavior of plasmas is evident in the natural settings, for example, in the Earth's magnetosphere. Similarly, laboratory plasmas such as fusion bottles also have their fair share of complex behavior. Nonequilibrium phenomena are intimately connected with statistical dynamics and form one of the growing research areas in modern nonlinear physics. These studies encompass the ideas of self-organization, phase transition, critical phenomena, self-organized criticality and turbulence. This book presents studies of complexity in the context of nonequilibrium phenomena using theory, modeling, simulations, and experiments, both in the laboratory and in nature.

  6. Ultracold neutral plasmas

    Science.gov (United States)

    Lyon, M.; Rolston, S. L.

    2017-01-01

    By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

  7. Ultracold neutral plasmas.

    Science.gov (United States)

    Lyon, M; Rolston, S L

    2017-01-01

    By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

  8. The Tokamak Fusion Test Reactor decontamination and decommissioning project and the Tokamak Physics Experiment at the Princeton Plasma Physics Laboratory. Environmental Assessment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-05-27

    If the US is to meet the energy needs of the future, it is essential that new technologies emerge to compensate for dwindling supplies of fossil fuels and the eventual depletion of fissionable uranium used in present-day nuclear reactors. Fusion energy has the potential to become a major source of energy for the future. Power from fusion energy would provide a substantially reduced environmental impact as compared with other forms of energy generation. Since fusion utilizes no fossil fuels, there would be no release of chemical combustion products to the atmosphere. Additionally, there are no fission products formed to present handling and disposal problems, and runaway fuel reactions are impossible due to the small amounts of deuterium and tritium present. The purpose of the TPX Project is to support the development of the physics and technology to extend tokamak operation into the continuously operating (steady-state) regime, and to demonstrate advances in fundamental tokamak performance. The purpose of TFTR D&D is to ensure compliance with DOE Order 5820.2A ``Radioactive Waste Management`` and to remove environmental and health hazards posed by the TFTR in a non-operational mode. There are two proposed actions evaluated in this environmental assessment (EA). The actions are related because one must take place before the other can proceed. The proposed actions assessed in this EA are: the decontamination and decommissioning (D&D) of the Tokamak Fusion Test Reactor (TFTR); to be followed by the construction and operation of the Tokamak Physics Experiment (TPX). Both of these proposed actions would take place primarily within the TFTR Test Cell Complex at the Princeton Plasma Physics Laboratory (PPPL). The TFTR is located on ``D-site`` at the James Forrestal Campus of Princeton University in Plainsboro Township, Middlesex County, New Jersey, and is operated by PPPL under contract with the United States Department of Energy (DOE).

  9. On the design of experiments for the study of extreme field limits in the ultra-relativistic interaction of electromagnetic waves with plasmas

    Science.gov (United States)

    Bulanov, Sergei V.; Esirkepov, Timur Z.; Hayashi, Yukio; Kando, Masaki; Kiriyama, Hiromitsu; Koga, James K.; Kondo, Kiminori; Kotaki, Hideyuki; Pirozhkov, Alexander S.; Bulanov, Stepan S.; Zhidkov, Alexei G.; Chen, Pisin; Neely, David; Kato, Yoshiaki; Narozhny, Nikolay B.; Korn, Georg

    2011-06-01

    The critical electric field of quantum electrodynamics, called also the Schwinger field, is so strong that it produces electron-positron pairs from vacuum, converting the energy of light into matter. Since the dawn of quantum electrodynamics, there has been a dream on how to reach it on Earth. With the rise of laser technology this field has become feasible through the construction of extremely high power lasers or/and with the sophisticated use of nonlinear processes in relativistic plasmas. This is one of the most attractive motivations for extremely high power laser development, i.e. producing matter from vacuum by pure light in fundamental process of quantum electrodynamics in the nonperturbative regime. Recently it has been realized that a laser with intensity well below the Schwinger limit can create an avalanche of electron-positron pairs similar to a discharge before attaining the Schwinger field. It has also been realized that the Schwinger limit can be reached using an appropriate configuration of laser beams. In experiments on the collision of laser light and high intensity electromagnetic pulses generated by relativistic flying mirrors, with electron bunches produced by a conventional accelerator and with laser wake field accelerated electrons the studying of extreme field limits in the nonlinear interaction of electromagnetic waves is proposed. The regimes of dominant radiation reaction, which completely changes the electromagnetic wave-matter interaction, will be revealed. This will result in a new powerful source of high brightness gamma-rays. A possibility of the demonstration of the electronpositron pair creation in vacuum via multi-photon processes can be realized. This will allow modeling under terrestrial laboratory conditions neutron star magnetospheres, cosmological gamma ray bursts and the Leptonic Era of the Universe.

  10. Modeling of linear divertor plasma simulator experiments with three-dimensional target structure by using EMC3-eIRENE code

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, T. [Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya (Japan); Tanaka, H.; Kobayashi, M. [National Institute for Fusion Science, Toki (Japan); SOKENDAI (The Graduate University For Advanced Studies), Toki (Japan); Kawamura, G. [National Institute for Fusion Science, Toki (Japan); Ohno, N.; Nishikata, H. [Graduate School of Engineering, Nagoya University, Nagoya (Japan); Feng, Y. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Garching/Greifswald (Germany)

    2016-08-15

    We have adapted the EMC3-EIRENE code for modeling of a linear divertor plasma simulator in order to demonstrate plasma-wall interactions with three-dimensional (3D) effects. 3D distributions of hydrogen plasma and neutrals can be successfully calculated for four different types of target plates: a V-shaped target, inclined targets with open and closed structures, and a planer target. Hydrogen atoms and molecules are accumulated more effectively in the V-shaped target plate, leading to a higher electron density with lower electron temperature than the planar target plate. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sheftman, D., E-mail: dsheftman@trialphaenergy.com; Gupta, D.; Roche, T.; Thompson, M. C. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688-7010 (United States); Giammanco, F.; Conti, F.; Marsili, P.; Moreno, C. D. [Department of Physics, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa (Italy)

    2016-11-15

    Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

  12. Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment.

    Science.gov (United States)

    Sheftman, D; Gupta, D; Roche, T; Thompson, M C; Giammanco, F; Conti, F; Marsili, P; Moreno, C D

    2016-11-01

    Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

  13. Heavy quark resonances as a probe of quark-gluon plasma: optimization of the muon spectrometer of ALICE experiment and study of the J/{psi} production in the NA60 experiment; Les resonances de quarks lourds comme sonde du plasma de quarks et de gluons: optimisation du spectrometre a muons de l'experience ALICE et etude de la production du J/{psi} dans l'experience NA60

    Energy Technology Data Exchange (ETDEWEB)

    Pillot, Ph

    2005-05-15

    The study of heavy quark production such as J/{psi} (cc-bar resonance) and {upsilon} (bb-bar resonance) in heavy ion collisions at high incident energies has been proposed as a tool to investigate the formation of a Quark Gluon Plasma. Experimentally, these resonances can be detected through their decay channel into a muon pair, using a muon spectrometer. The optimal resolution of a muon spectrometer cannot be reached unless the position of the different tracking detectors are accurately known. In the first part of the work reported in this thesis are presented the design and performances of the Geometry Monitoring System of the ALICE experiment's muon spectrometer at LHC. This system, which is composed of several hundreds of RASNIK derived optical devices, allows to measure displacements and deformations of the chambers with a precision better than a hundred of microns. Thanks to its muon spectrometer associated with a vertex telescope, the NA60 experiment studies the dimuon production in nucleus-nucleus collisions at CERN SPS. The second part of the work reported in this thesis is related to the analysis of the data collected in indium-indium collisions at 158 GeV/c/nucleon. More specifically, the J/{psi} production together with its transverse momentum and transverse mass distributions are studied as a function of the centrality of the collision. The different results arising from our analysis are then compared to those obtained previously by NA38 and NA50, allowing a better understanding