WorldWideScience

Sample records for plasma temperature density

  1. Charge, density and electron temperature in a molecular ultracold plasma

    CERN Document Server

    Rennick, C J; Ortega-Arroyo, J; Godin, P J; Grant, E R

    2009-01-01

    A Rydberg gas of NO entrained in a supersonic molecular beam releases electrons as it evolves to form an ultracold plasma. The size of this signal, compared with that extracted by the subsequent application of a pulsed electric field, determines the absolute magnitude of the plasma charge. This information, combined with the number density of ions, supports a simple thermochemical model that explains the evolution of the plasma to an ultracold electron temperature.

  2. High density and high temperature plasmas in Large Helical Device

    Science.gov (United States)

    Komori, Akio

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than ~ 1 × 1021 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  3. High density and high temperature plasmas in Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Komori, Akio, E-mail: komori@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2010-11-01

    Recently a new confinement regime called Super Dense Core (SDC) mode was discovered in Large Helical Device (LHD). An extremely high density core region with more than {approx} 1 x 10{sup 21} m{sup -3} is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB is very high and the particle confinement in the core region is {approx} 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature up to 5.6 keV with the formation of the internal transport barrier (ITB). In the electron heating experiments with 77 GHz gyrotrons, the highest electron temperature more than 15 keV was achieved, where plasmas are in the neoclassical regime.

  4. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  5. Feasibility of measuring density and temperature of laser produced plasmas using spectroscopic techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Edens, Aaron D.

    2008-09-01

    A wide variety of experiments on the Z-Beamlet laser involve the creation of laser produced plasmas. Having a direct measurement of the density and temperature of these plasma would an extremely useful tool, as understanding how these quantities evolve in space and time gives insight into the causes of changes in other physical processes, such as x-ray generation and opacity. We propose to investigate the possibility of diagnosing the density and temperature of laser-produced plasma using temporally and spatially resolved spectroscopic techniques that are similar to ones that have been successfully fielded on other systems. Various researchers have measured the density and temperature of laboratory plasmas by looking at the width and intensity ratio of various characteristic lines in gases such as nitrogen and hydrogen, as well as in plasmas produced off of solid targets such as zinc. The plasma conditions produce two major measurable effects on the characteristic spectral lines of that plasma. The 1st is the Stark broadening of an individual line, which depends on the electron density of the plasma, with higher densities leading to broader lines. The second effect is a change in the ratio of various lines in the plasma corresponding to different ionization states. By looking at the ratio of these lines, we can gain some understanding of the plasma ionization state and consequently its temperature (and ion density when coupled with the broadening measurement). The hotter a plasma is, the higher greater the intensity of lines corresponding to higher ionization states. We would like to investigate fielding a system on the Z-Beamlet laser chamber to spectroscopically study laser produced plasmas from different material targets.

  6. SOME COLLISION PROCESSES IN PLASMAS WITH HIGHER TEMPERATURE AND DENSITY

    Institute of Scientific and Technical Information of China (English)

    KazuoTakayanagi

    1990-01-01

    Some collision processes important in hot and dense plasmas are discussed.Recent calculation of secondary electron velocity distribution in ionizing collision between an electron and a multiply-charged ion is reported.

  7. Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade

    DEFF Research Database (Denmark)

    Horacek, J.; Adamek, J.; Müller, H.W.

    2010-01-01

    This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements of plasma density, potential and electron temperature in the edge plasma of tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate the credibility of the ball-pen probe. We demonstrate that floating poten...

  8. Modelling the influence of temperature anisotropies on poloidal asymmetries of density in the core of rotating plasmas

    Science.gov (United States)

    Bilato, R.; Maj, O.; Angioni, C.

    2014-07-01

    A consistent set of equations is derived to model poloidal density asymmetries induced by temperature anisotropies in tokamak rotating plasmas. The model can be applied to compute poloidal density asymmetry of highly charged impurities due to additional plasma heating.

  9. Simultaneous measurement of electron temperature and density by a line pair method in the RFP plasma

    Science.gov (United States)

    Watanabe, Masayuki; Shimizu, S.; Ogawa, H.; Shinohara, T.

    2009-11-01

    A line-pair-method has been applied for a simultaneous measurement of the electron temperature and density in ATRAS RFP plasma. Three helium spectrum lines (668nm, 706nm, 728nm) were measured during the discharge at the same time and the electron temperature and density is estimated by using a Collision-Radiation model. To get the signal of the helium impunity line from the RFP discharge, the RFP plasma in the hydrogen gas with a few mixed helium gas was formed. In the typical ATRAS RFP discharge of the plasma current of 60kA, the electron temperature was approximately 50-150 eV and the electron density is the order of 10^18 m-3. During the discharge, the change of the temperature and density are mutually related and this correlation was the almost reverse phase. The periodically change of the temperature and density were also observed. This change synchronizes with a periodically increase of the averaged toroidal magnetic field, which is caused by the toroidal rotation of the increase of the toroidal magnetic field. This rotation, which is deeply related with dynamo effect, makes the plasma energy lose and particles also diffuse toward the plasma edge. As a result, the recycling of the particle and energy are occurred at the same time.

  10. Chemical sputtering of graphite by low temperature nitrogen plasmas at various substrate temperatures and ion flux densities

    NARCIS (Netherlands)

    Bystrov, K.; Morgan, T. W.; Tanyeli, I.; De Temmerman, G.; M. C. M. van de Sanden,

    2013-01-01

    We report measurements of chemical sputtering yields of graphite exposed to low temperature nitrogen plasmas. The influence of surface temperature and incoming ion energy on the sputtering yields has been investigated in two distinct ion flux density regimes. Sputtering yields grow consistently with

  11. Temporal evolution of electron density and temperature in capillary discharge plasmas

    Science.gov (United States)

    Oh, Seong Y.; Uhm, Han S.; Kang, Hoonsoo; Lee, In W.; Suk, Hyyong

    2010-05-01

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 1018 cm-3 within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3×1018 cm-3 occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  12. CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

    NARCIS (Netherlands)

    Westerhout, J.; Cardozo, N. J. L.; Rapp, J.; van Rooij, G. J.

    2009-01-01

    The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature T-e=0.1-2.5 eV and electron density n(e)=(0.5-5) X 10(20) m(-3)] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to >10(6

  13. Electron number density and temperature measurements in laser produced brass plasma

    Science.gov (United States)

    Shaltout, A. A.; Mostafa, N. Y.; Abdel-Aal, M. S.; Shaban, H. A.

    2010-04-01

    Laser-induced breakdown spectroscopy (LIBS) has been used for brass plasma diagnostic using a Nd:YAG laser at 1064 nm. Optimal experimental conditions were evaluated, including repetition rate, number of laser shots on sample, and laser energy. The plasma temperatures and the electron number densities were determined from the emission spectra of LIBS. Cu and Zn spectral lines were used for excitation temperature calculation using Saha-Boltzmann distribution as well as line pair ratio. It was found that, the excitation temperature calculated by using Saha-Boltzmann distribution and line pair ratio methods are not the same. The electron number density has been evaluated from the Stark broadening of Hα transition at 656.27 nm and the calculated electron number density is agreement with literature.

  14. Electron density and temperature measurements in a magnetized expanding hydrogen plasma

    Science.gov (United States)

    Leyte-González, R.; Palomares, J. M.; Schram, D. C.; Engeln, R.

    2016-08-01

    We report measurements of electron densities, ne, and temperatures, Te, in a magnetized expanding hydrogen plasma performed using Thomson scattering. The effects of applying an axial magnetic field and changing the background pressure in the plasma vessel on ne and Te along the expansion axis are reported. Magnetic field strengths (B field) up to 170 mT were applied, which are one order of magnitude larger than previously reported. The main effect of the applied B field is the plasma confinement, which leads to higher ne. At B fields larger than 88 mT the electron density along the expansion axis does not depend strongly on the magnetic field strength. However, Te is susceptible to the B field and reaches at 170 mT a maximum of 2.5 eV at a distance of 1.5 cm from the exit of the cascaded arc. To determine also the effect of the arc current through the arc, measurements were performed with arc currents of 45, 60, and 75 A at background pressures of 9.7 and 88.3 Pa. At constant magnetic field ne decreases from the exit of the arc along the expansion axis when the arc current is decreased. At 88.3 Pa ne shows a higher value close to the exit of the arc, but a faster decay along the expansion axis with respect to the 9.7 Pa case. Te is overall higher at lower pressure reaching a maximum of 3.2 eV at the lower arc current of 45 A. The results of this study complement our understanding and the characterization of expanding hydrogen plasmas.

  15. Microwave diagnostic for the determination of the electron temperature of a low density shock-heated argon plasma

    Science.gov (United States)

    Schneider, C. P.; Exberger, R. J.

    1978-01-01

    The diffraction, defocusing and beam bending effects of microwaves transmitted through a bounded shock-heated argon plasma with low electron density are investigated with the purpose of developing an accurate method for electron temperature (Te) determination. This report describes the evaluation technique and presents results for an argon plasma with pressure between 3 and 10 torr, and T2 between 5500 and 9500 K. The electron temperature values obtained have a range of uncertainty between -20% and +10% only. The electron temperature is equal or lower by approximately 1000 K in comparison to the heavy particle temperature (T2).

  16. Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

    2009-07-01

    The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

  17. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas

    Science.gov (United States)

    Dutra, E. C.; Koch, J. A.; Presura, R.; Angermeier, W. A.; Darling, T.; Haque, S.; Mancini, R. C.; Covington, A. M.

    2016-11-01

    Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

  18. Factors affecting ion kinetic temperature, number density, and containment time in the NASA Lewis bumpy-torus plasma

    Science.gov (United States)

    Roth, J. R.

    1977-01-01

    The degree of toroidal symmetry of the plasma, the number of midplane electrode rings, the configuration of electrode rings, and the location of the diagnostic instruments with respect to the electrode rings used to generate the plasma are discussed. Impurities were deliberately introduced into the plasma, and the effects of the impurity fraction on ion kinetic temperature and electron number density were observed. It is concluded that, if necessary precautions are taken, the plasma communicates extremely well along the magnetic field lines and displays a high degree of symmetry from sector to sector for a wide range of electrode ring configurations and operating conditions. Finally, some characteristic data taken under nonoptimized conditions are presented, which include the highest electron number density and the longest particle containment time (1.9 msec) observed. Also, evidence from a paired comparison test is presented which shows that the electric field acting along the minor radius of the toroidal plasma improves the plasma density and the calculated containment time more than an order of magnitude if the electric field points inward, relative to the values observed when it points (and pushes ions) radially outward.

  19. Soft x-ray scattering using FEL radiation for probing near-solid density plasmas at few electronvolt temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Toleikis, S; Faustlin, R R; Cao, L; Doppner, T; Dusterer, S; Forster, E; Fortmann, C; Glenzer, S H; Gode, S; Gregori, G; Irsig, R; Laarmann, T; Lee, H J; Li, B; Meiwes-Broer, K; Przystawik, A; Radcliffe, P; Redmer, R; Tavella, F; Thiele, R; Tiggesbaumker, J; Truong, N X; Uschmann, I; Zastrau, U; Tschentscher, T

    2009-03-03

    We report on soft x-ray scattering experiments on cryogenic hydrogen and simple metal targets. As a source of intense and ultrashort soft x-ray pulses we have used free-electron laser radiation at 92 eV photon energy from FLASH at DESY, Hamburg. X-ray pulses with energies up to 100 {micro}J and durations below 50 fs provide interaction with the target leading simultaneously to plasma formation and scattering. Experiments exploiting both of these interactions have been carried out, using the same experimental setup. Firstly, recording of soft x-ray inelastic scattering from near-solid density hydrogen plasmas at few electronvolt temperatures confirms the feasibility of this diagnostics technique. Secondly, the soft x-ray excitation of few electronvolt solid-density plasmas in simple metals could be studied by recording soft x-ray line and continuum emission integrated over emission times from fs to ns.

  20. Structural materialization of stainless steel molds and dies by the low temperature high density plasma nitriding

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2015-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a mold substrate material for injection molding and as a die for mold-stamping and direct stamping processes. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical elements at present. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness of 1400 Hv within its thickness of 40 μm without any formation of nitrides after 14.4 ks plasma nitriding at 693 K. This nitrogen solid-solution treated stainless steel had thermal resistivity even at the mold-stamping conditions up to 900 K.

  1. Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

    Science.gov (United States)

    Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

    2008-01-01

    Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

  2. Excitation temperature and electron number density distributions experienced by analyte species in an inductively coupled argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kalnicky, D.J.

    1977-02-01

    Spatially resolved, radial excitation temperatures and radial electron number density distributions experienced by analyte species in the observation zone of 15 to 25 mm above the load coil of a toroidally shaped, inductively coupled argon plasma (ICP) are presented and related to the analytical performance of these plasmas. A comparison of radial temperatures measured with support gas (Ar I) lines and with a typical analyte thermometric species (Fe I) at 15 mm above the load coil is given. Radial (Fe I) excitation temperatures obtained at three observation heights (15, 20, and 25 mm) are compared for aerosol carrier gas flows of 1.0 l/min and 1.3 l/min. The addition of a large amount of an easily ionized element (6900 ..mu..g Na/ml) did not significantly change Fe I excitation temperature distributions at the respective aerosol carrier gas flows and observation heights. A comparison of radial electron number density distributions measured by the Saha-Eggert ionization and Stark broadening methods is given for an observation height of 15 mm above the load coil. The differences between the electron number density values obtained by these methods is discussed. The effect of addition of 6900 ..mu..g Na/ml on Saha-Eggert electron density distributions at these observation heights is also discussed. The computer programs employed in this investigation and discussions of the computational procedures incorporated in these programs are given.

  3. Low temperature high density plasma nitriding of stainless steel molds for stamping of oxide glasses

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2016-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a die for mold- and direct-stamping processes of optical oxide glasses. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical oxide-glass elements. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness over 1400 HV within its thickness of 50 μm without any formation of nitrides after plasma nitriding at 693 K for 14.4 ks. This plasma-nitrided mold was utilized for mold-stamping of two colored oxide glass plates at 833 K; these plates were successfully deformed and joined into a single glass plate by this stamping without adhesion or galling of oxide glasses onto the nitrided mold surface.

  4. Modified Korteweg-de Vries solitons at supercritical densities in two-electron temperature plasmas

    CERN Document Server

    Verheest, Frank; Hereman, Willy A

    2016-01-01

    The supercritical composition of a plasma model with cold positive ions in the presence of a two-temperature electron population is investigated, initially by a reductive perturbation approach, under the combined requirements that there be neither quadratic nor cubic nonlinearities in the evolution equation. This leads to a unique choice for the set of compositional parameters and a modified Korteweg-de Vries equation (mKdV) with a quartic nonlinear term. The conclusions about its one-soliton solution and integrability will also be valid for more complicated plasma compositions. Only three polynomial conservation laws can be obtained. The mKdV equation with quartic nonlinearity is not completely integrable, thus precluding the existence of multi-soliton solutions. Next, the full Sagdeev pseudopotential method has been applied and this allows for a detailed comparison with the reductive perturbation results. This comparison shows that the mKdV solitons have slightly larger amplitudes and widths than those obta...

  5. Characterization of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Phillips, L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Chan, L.-Y.; Serlin, V.

    2011-10-01

    Previous experiments with Nike KrF laser (λ = 248 nm , Δν ~ 1 THz) observed LPI signatures near quarter critical density (nc / 4) in CH plasmas, however, detailed measurement of the temperature (Te) and density (ne) profiles was missing. The current Nike LPI campaign will perform experimental determination of the plasma profiles. A side-on grid imaging refractometer (GIR) is the main diagnostic to resolve Te and ne in space taking 2D snapshots of probe laser (λ = 266 nm , Δt = 8 psec) beamlets (50 μm spacing) refracted by the plasma at laser peak time. Ray tracing of the beamlets through hydrodynamically simulated (FASTRAD3D) plasma profiles estimates the refractometer may access densities up to ~ 0 . 2nc . With the measured Te and ne profiles in the plasma corona, we will discuss analysis of light data radiated from the plasmas in spectral ranges relevant to two plasmon decay and convective Raman instabilities. Validity of the (Te ,ne) data will also be discussed for the thermal transport study. Work supported by DoE/NNSA and ONR and performed at NRL.

  6. Increase of the Density, Temperature and Velocity of Plasma Jets driven by a Ring of High Energy Laser Beams

    CERN Document Server

    Fu, Wen; Fatenejad, Milad; Lamb, Donald Q; Grosskopf, Michael; Park, Hye-Sook; Remington, Bruce; Spitkovsky, Anatoly

    2012-01-01

    Supersonic plasma outflows driven by multi-beam, high-energy lasers, such as Omega and NIF, have been and will be used as platforms for a variety of laboratory astrophysics experiments. Here we propose a new way of launching high density and high velocity, plasma jets using multiple intense laser beams in a hollow ring formation. We show that such jets provide a more flexible and versatile platform for future laboratory astrophysics experiments. Using high resolution hydrodynamic simulations, we demonstrate that the collimated jets can achieve much higher density, temperature and velocity when multiple laser beams are focused to form a hollow ring pattern at the target, instead of focused onto a single spot. We carried out simulations with different ring radii and studied their effects on the jet properties. Implications for laboratory collisionless shock experiments are discussed.

  7. Interaction between a high density-low temperature plasma and a frozen hydrogen pellet in a railgun injector

    Energy Technology Data Exchange (ETDEWEB)

    Grapperhaus, M.J. [Illinois Univ., Urbana, IL (United States)

    1993-10-01

    A model has been developed which describes the ablation process of frozen hydrogen pellets in an electromagnetic railgun. The model incorporates the neutral gas shielding model in which the pellet surface is heated by incident electrons from the plasma arc. The heated surface then ablates, forming a neutral cloud which attenuates the incoming electrons. The energy lost in the cloud by the electrons heats the ablatant material as it flows into the plasma arc. Under steady-state conditions, a scaling law for the ablation rate was derived as a function of plasma-arc temperature and density. In addition, flow conditions and the criteria for the existence of a steady-state solution were formulated and subsequently examined under simplifying assumptions. Comparison with experimentally observed ablation rates shows good qualitative agreement.

  8. Electron Density and Temperature Measurement by Stark Broadening in a Cold Argon Arc-Plasma Jet at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qiuping; CHENG Cheng; MENG Yuedong

    2009-01-01

    Determination of both the electron density and temperature simultaneously in a cold argon arc-plasma jet by analyzing the Stark broadening of two different emission lines is presented.This method is based on the fact that the Stark broadening of different lines has a different dependence on the electron density and temperature.Therefore,a comparison of two or more line broadenings allows us to diagnose the electron density and temperature simultaneously.In this study we used the first two Balmer series hydrogen lines H_α and H_β for their large broadening width.For this purpose,a small amount of hydrogen was introduced into the discharge gas.The results of the Gigosos-Cardenoso computational model,considering more relevant processes for the hydrogen Balmer lines,is used to process the experimental data.With this method,we obtained reliable electron density and temperature,1.88 ×10 ~(15) cm~(-3 )and 13000 K,respectively.Possible sources of error were also analyzed.

  9. Measurements of plasma temperature and electron density in laser-induced copper plasma by time-resolved spectroscopy of neutral atom and ion emissions

    Indian Academy of Sciences (India)

    V K Unnikrishnan; Kamlesh Alti; V B Kartha; C Santhosh; G P Gupta; B M Suri

    2010-06-01

    Plasma produced by a 355 nm pulsed Nd:YAG laser with a pulse duration of 6 ns focussed onto a copper solid sample in air at atmospheric pressure is studied spectroscopically. The temperature and electron density characterizing the plasma are measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time window of 300–2000 ns. An echelle spectrograph coupled with a gated intensified charge coupled detector is used to record the plasma emissions. The temperature is obtained using the Boltzmann plot method and the electron density is determined using the Saha– Boltzmann equation method. Both parameters are studied as a function of delay time with respect to the onset of the laser pulse. The results are discussed. The time window where the plasma is optically thin and is also in local thermodynamic equilibrium (LTE), necessary for the laser-induced breakdown spectroscopy (LIBS) analysis of samples, is deduced from the temporal evolution of the intensity ratio of two Cu I lines. It is found to be 700–1000 ns.

  10. Measurements of electron density and temperature profiles in plasma produced by Nike KrF laser for laser plasma instability research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Karasik, M.; Chan, L. Y.

    2015-08-01

    A grid image refractometer (GIR) has been implemented at the Nike krypton fluoride laser facility of the Naval Research Laboratory. This instrument simultaneously measures propagation angles and transmissions of UV probe rays (λ = 263 nm, Δt = 10 ps) refracted through plasma. We report results of the first Nike-GIR measurement on a CH plasma produced by the Nike laser pulse (˜1 ns FWHM) with the intensity of 1.1 × 1015 W/cm2. The measured angles and transmissions were processed to construct spatial profiles of electron density (ne) and temperature (Te) in the underdense coronal region of the plasma. Using an inversion algorithm developed for the strongly refracted rays, the deployed GIR system probed electron densities up to 4 × 1021 cm-3 with the density scale length of 120 μm along the plasma symmetry axis. The resulting ne and Te profiles are verified to be self-consistent with the measured quantities of the refracted probe light.

  11. 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

  12. Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: Off-resonant and resonant cases

    Energy Technology Data Exchange (ETDEWEB)

    Cortázar, O. D. [ESS Bilbao, Edificio Cosimet, Landabarri 2, 48940-Leioa, Vizcaya (Spain); Universidad de Castilla-La Mancha, ETSII, C.J. Cela s/n, 13170 Ciudad Real (Spain); Megía-Macías, A.; Vizcaíno-de-Julián, A. [ESS Bilbao, Edificio Cosimet, Landabarri 2, 48940-Leioa, Vizcaya (Spain)

    2013-09-15

    Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.

  13. N Vibrational Temperatures and OH Number Density Measurements in a NS Pulse Discharge Hydrogen-Air Plasmas

    Science.gov (United States)

    Hung, Yichen; Winters, Caroline; Jans, Elijah R.; Frederickson, Kraig; Adamovich, Igor V.

    2017-06-01

    This work presents time-resolved measurements of nitrogen vibrational temperature, translational-rotational temperature, and absolute OH number density in lean hydrogen-air mixtures excited in a diffuse filament nanosecond pulse discharge, at a pressure of 100 Torr and high specific energy loading. The main objective of these measurements is to study a possible effect of nitrogen vibrational excitation on low-temperature kinetics of HO2 and OH radicals. N2 vibrational temperature and gas temperature in the discharge and the afterglow are measured by ns broadband Coherent Anti-Stokes Scattering (CARS). Hydroxyl radical number density is measured by Laser Induced Fluorescence (LIF) calibrated by Rayleigh scattering. The results show that the discharge generates strong vibrational nonequilibrium in air and H2-air mixtures for delay times after the discharge pulse of up to 1 ms, with peak vibrational temperature of Tv ≈ 2000 K at T ≈ 500 K. Nitrogen vibrational temperature peaks ≈ 200 μs after the discharge pulse, before decreasing due to vibrational-translational relaxation by O atoms (on the time scale of a few hundred μs) and diffusion (on ms time scale). OH number density increases gradually after the discharge pulse, peaking at t 100-300 μs and decaying on a longer time scale, until t 1 ms. Both OH rise time and decay time decrease as H2 fraction in the mixture is increased from 1% to 5%. OH number density in a 1% H2-air mixture peaks at approximately the same time as vibrational temperature in air, suggesting that OH kinetics may be affected by N2 vibrational excitation. However, preliminary kinetic modeling calculations demonstrate that OH number density overshoot is controlled by known reactions of H and O radicals generated in the plasma, rather than by dissociation by HO2 radical in collisions with vibrationally excited N2 molecules, as has been suggested earlier. Additional measurements at higher specific energy loadings and kinetic modeling

  14. Measurements of Laser Plasma Instability (LPI) and Electron Density/Temperature Profiles in Plasmas Produced by the Nike KrF Laser

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Serlin, V.; Obenschain, S. P.

    2016-10-01

    We will present results of simultaneous measurements of LPI-driven light scattering and density/temperature profiles in CH plasmas produced by the Nike krypton fluoride laser (λ = 248 nm). The primary diagnostics for the LPI measurement are time-resolved spectrometers with absolute intensity calibration in spectral ranges relevant to the optical detection of stimulated Raman scattering or two plasmon decay. The spectrometers are capable of monitoring signal intensity relative to thermal background radiation from plasma providing a useful way to analyze LPI initiation. For further understanding of LPI processes, the recently implemented grid image refractometer (Nike-GIR)a is used to measure the coronal plasma profiles. In this experiment, Nike-GIR is equipped with a 5th harmonic probe laser (λ = 213 nm) in attempt to probe into a high density region over the previous peak density with λ = 263 nm probe light ( 4 ×1021 cm-3). The LPI behaviors will be discussed with the measured data sets. Work supported by DoE/NNSA.

  15. Electron density and temperature determination in a Tokamak plasma using light scattering; Determinacion de la densidad y temperatura electronicas en un Tokamak mediante difusion luminosa

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Navarro Gomerz, A.; Zurro Hernandez, B.

    1976-07-01

    A theoretical foundation review for light scattering by plasmas is presented. Furthermore, we have included a review of the experimental methods for electron density and temperature measurements, with spatial and time resolution, in a Tokamak plasma using spectral analysis of the scattered radiation. (Author) 13 refs.

  16. Measurements of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Karasik, M.; Chan, L.-Y.; Serlin, V.; Phillips, L.

    2012-10-01

    ExperimentsfootnotetextJ. Oh, et al, GO5.4, APS DPP (2010).^,footnotetextJ. L. Weaver, et al, GO5.3, APS DPP (2010). using Nike KrF laser observed LPI signatures from CH plasmas at the laser intensities above ˜1x10^15 W/cm^2. Knowing spatial profiles of temperature (Te) and density (ne) in the underdense coronal region (0 Nike LPI experiment, a side-on grid imaging refractometer (GIR)footnotetextR. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993). is being deployed for measuring the underdense plasma profiles. The GIR will resolve Te and ne in space taking a 2D snapshot of probe laser (λ= 263 nm, δt = 10 psec) beamlets (50μm spacing) refracted by the plasma at a selected time during the laser illumination. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera will simultaneously monitor light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay (TDP) instabilities. The experimental study of effects of the plasma profiles on the LPI initiation will be presented.

  17. Negative Plasma Densities Raise Questions

    Energy Technology Data Exchange (ETDEWEB)

    Hazi, A

    2006-01-26

    Nearly all the matter encountered on Earth is either a solid, liquid, or gas. Yet plasma-the fourth state of matter-comprises more than 99 percent of the visible universe. Understanding the physical characteristics of plasmas is important to many areas of scientific research, such as the development of fusion as a clean, renewable energy source. Lawrence Livermore scientists study the physics of plasmas in their pursuit to create fusion energy, because plasmas are an integral part of that process. When deuterium and tritium are heated to the extreme temperatures needed to achieve and sustain a fusion reaction (about 100 million degrees), the electrons in these light atoms become separated from the nuclei. This process of separation is called ionization, and the resulting collection of negatively charged free electrons and positively charged nuclei is known as a plasma. Although plasmas and gases have many similar properties, plasmas differ from gases in that they are good conductors of electricity and can generate magnetic fields. For the past decade, x-ray laser interferometry has been used in the laboratory for measuring a plasma's index of refraction to determine plasma density. (The index of refraction for a given material is defined as the wavelength of light in a vacuum divided by the wavelength of light traveling through the material.) Until now, plasma physicists expected to find an index of refraction less than one. Researchers from Livermore and Colorado State University recently conducted experiments on aluminum plasmas at the Laboratory's COMET laser facility and observed results in which the index of refraction was greater than one. This surprising result implied a negative electron density. Livermore physicist Joseph Nilsen and his colleagues from Livermore and the University of Notre Dame have performed sophisticated calculations to explain this phenomenon. Previously, researchers believed that only free electrons contributed to the index

  18. 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…

  19. 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…

  20. Combination of the ionic-to-atomic line intensity ratios from two test elements for the diagnostic of plasma temperature and electron number density in Inductively Coupled Plasma Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tognoni, E. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)], E-mail: tognoni@ipcf.cnr.it; Hidalgo, M.; Canals, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia. Universidad de Alicante. Apdo. 99, 03080, Alicante (Spain); Cristoforetti, G.; Legnaioli, S.; Salvetti, A.; Palleschi, V. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)

    2007-05-15

    In Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) spectrochemical analysis, the MgII(280.270 nm)/MgI(285.213 nm) ionic to atomic line intensity ratio is commonly used as a monitor of the robustness of operating conditions. This approach is based on the univocal relationship existing between intensity ratio and plasma temperature, for a pure argon atmospheric ICP in thermodynamic equilibrium. In a multi-elemental plasma in the lower temperature range, the measurement of the intensity ratio may not be sufficient to characterize temperature and electron density. In such a range, the correct relationship between intensity ratio and plasma temperature can be calculated only when the complete plasma composition is known. We propose the combination of the line intensity ratios of two test elements (double ratio) as an effective diagnostic tool for a multi-elemental low temperature LTE plasma of unknown composition. In particular, the variation of the double ratio allows us discriminating changes in the plasma temperature from changes in the electron density. Thus, the effects on plasma excitation and ionization possibly caused by introduction of different samples and matrices in non-robust conditions can be more accurately interpreted. The method is illustrated by the measurement of plasma temperature and electron density in a specific analytic case.

  1. Internal Magnetic Field, Temperature and Density Measurements on Magnetized HED plasmas using Pulsed Polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Roger J. [Univ. of Washington, Seattle, WA (United States)

    2016-10-20

    The goals were to collaborate with the MSX project and make the MSX platform reliable with a performance where pulsed polarimetry would be capable of adding a useful measurement and then to achieve a first measurement using pulsed polarimetry. The MSX platform (outside of laser blow off plasmas adjacent to magnetic fields which are low beta) is the only device that can generate high beta magnetized collisionless supercritical shocks, and with a large spatial size of ~10 cm. Creating shocks at high Mach numbers and investigating the dynamics of the shocks was the main goal of the project. The MSX shocks scale to astrophysical magnetized shocks and potentially throw light on the generation of highly energetic particles via a mechanism like the Fermi process.

  2. Extraction of the spatial distribution of electron temperature and density in Magnetized Liner Inertial Fusion implosion plasmas

    Science.gov (United States)

    Carpenter, Kyle; Mancini, Roberto

    2016-10-01

    We are testing polychromatic tomography to extract the spatial distribution of electron temperatures and densities in the cylindrical implosion plasmas created during MagLIF. Motivation for this technique stems from its successful application to spherical implosion core plasmas on Omega through the analysis of spatially resolved spectra (SRS) collected via pinhole imaging. In MagLIF, collections of SRS can be extracted from the images created by the slit imaging CRITR spectrometers. These spectra can be complemented with pinhole monochromatic images and spectra recorded with a spherical crystal spectrometer. One axially resolved and one radially resolved CRITR are field during MagLIF and information extracted from one of these SRS would be spatially integrated over a plane of finite thickness given by the spatial resolution of the instrument. In our method, we couple a model that creates synthetic sets of spectra, like those obtained from an experiment, with a Pareto genetic algorithm which searches in parameter space for the spatial distribution which best simultaneously and self-consistently fits the set of SRS/ Solutions obtained are used as the initial solution for a Levenberg-Marquadt minimization algorithm to provide a final ``fine-tuned'' solution. We are testing this method by creating synthetic ``experimental'' data and using the technique to search for the spatial distribution. The results of these feasibility studies will be discussed. The work is supported by a contract from Sandia National Laboratories.

  3. Increase of the Density, Temperature and Velocity of Plasma Jets driven by a Ring of High Energy Laser Beams

    OpenAIRE

    Fu, Wen; Liang, Edison P.; Fatenejad, Milad; Lamb, Donald Q.; Grosskopf, Michael; Park, Hye-Sook; Remington, Bruce; Spitkovsky, Anatoly

    2012-01-01

    Supersonic plasma outflows driven by multi-beam, high-energy lasers, such as Omega and NIF, have been and will be used as platforms for a variety of laboratory astrophysics experiments. Here we propose a new way of launching high density and high velocity, plasma jets using multiple intense laser beams in a hollow ring formation. We show that such jets provide a more flexible and versatile platform for future laboratory astrophysics experiments. Using high resolution hydrodynamic simulations,...

  4. Energy Density in Quark-Gluon Plasma

    Institute of Scientific and Technical Information of China (English)

    马忠彪; 苗洪; 高崇寿

    2003-01-01

    We study the energy density in quark-gluon plasma. At the very high temperature, the quark matter is a hot and dense matter in the colour deconfinement condition, and quarks can coalescent diquarks. Energy density of this system is worked out and compared with the energy density in the other two kinds of situations. Possible energy density is about eo ≈ 2.4 GeV/fm3 according to our estimation for quark matter including diquarks,

  5. On the E-H transition in inductively coupled radio frequency oxygen plasmas: I. Density and temperature of electrons, ground state and singlet metastable molecular oxygen

    Science.gov (United States)

    Wegner, Th; Küllig, C.; Meichsner, J.

    2017-02-01

    In this series of two papers, the E-H transition in a planar inductively coupled radio frequency discharge (13.56 MHz) in pure oxygen is studied using comprehensive plasma diagnostic methods. The electron density serves as the main plasma parameter to distinguish between the operation modes. The (effective) electron temperature, which is calculated from the electron energy distribution function and the difference between the floating and plasma potential, halves during the E-H transition. Furthermore, the pressure dependency of the RF sheath extension in the E-mode implies a collisional RF sheath for the considered total gas pressures. The gas temperature increases with the electron density during the E-H transition and doubles in the H-mode compared to the E-mode, whereas the molecular ground state density halves at the given total gas pressure. Moreover, the singlet molecular metastable density reaches 2% in the E-mode and 4% in the H-mode of the molecular ground state density. These measured plasma parameters can be used as input parameters for global rate equation calculations to analyze several elementary processes. Here, the ionization rate for the molecular oxygen ions is exemplarily determined and reveals, together with the optical excitation rate patterns, a change in electronegativity during the mode transition.

  6. Electron Density from Balmer Series Hydrogen Lines and Ionization Temperatures in Inductively Coupled Argon Plasma Supplied by Aerosol and Volatile Species

    Directory of Open Access Journals (Sweden)

    Jolanta Borkowska-Burnecka

    2016-01-01

    Full Text Available Electron density and ionization temperatures were measured for inductively coupled argon plasma at atmospheric pressure. Different sample introduction systems were investigated. Samples containing Sn, Hg, Mg, and Fe and acidified with hydrochloric or acetic acids were introduced into plasma in the form of aerosol, gaseous mixture produced in the reaction of these solutions with NaBH4 and the mixture of the aerosol and chemically generated gases. The electron densities measured from Hα, Hβ, Hγ, and Hδ lines on the base of Stark broadening were compared. The study of the H Balmer series line profiles showed that the ne values from Hγ and Hδ were well consistent with those obtained from Hβ which was considered as a common standard line for spectroscopic measurement of electron density. The ne values varied from 0.56·1015 to 1.32·1015 cm−3 and were the highest at loading mixture of chemically generated gases. The ionization temperatures of plasma, determined on the base of the Saha approach from ion-to-atom line intensity ratios, were lower for Sn and Hg (6500–7200 K than those from Fe and Mg lines (7000–7800 K. The Sn II/Sn I and Hg II/Hg I, Fe II/Fe I, and Mg II/Mg I intensity ratios and the electron densities (ne were dependent on experimental conditions of plasma generation. Experimental and theoretically calculated ionization degrees were compared.

  7. Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

    CERN Document Server

    Nagayama, T; Florido, R; Mayes, D; Tommasini, R; Koch, J A; Delettrez, J A; Regan, S P; Smalyuk, V A

    2014-01-01

    Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional space-resolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.

  8. Measurement of electron temperatures of Argon Plasmas in a High-Density Inductively-Coupled Remote Plasma System by Langmuir Probe and Optical-Emission Spectroscopy

    NARCIS (Netherlands)

    Boogaard, A.; Kovalgin, Alexeij Y.; Aarnink, Antonius A.I.; Wolters, Robertus A.M.; Holleman, J.; Brunets, I.; Schmitz, Jurriaan

    2006-01-01

    We measured electron density and electron energy distribution function (EEDF) in our reactor by a Langmuir probe. The EEDF of Ar plasma in the reactor could largely be described by the Maxwell-Boltzmann distribution function, but it also contained a fraction (~10-3) of electrons which were much

  9. Density threshold for plasma detachment in gas target

    Energy Technology Data Exchange (ETDEWEB)

    Ezumi, N. [Nagoya Univ. (Japan). Dept. of Energy Engineering and Science; Mori, S. [Department of Electrical Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-01 (Japan); Ohno, N. [Nagoya Univ. (Japan). Dept. of Energy Engineering and Science; Takagi, M. [Nagoya Univ. (Japan). Dept. of Energy Engineering and Science; Takamura, S. [Nagoya Univ. (Japan). Dept. of Energy Engineering and Science; Suzuki, H. [National Institute for Fusion Science, Nagoya 464-01 (Japan); Park, J. [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States)

    1997-02-01

    The simulated gas target divertor experiment has been performed to investigate the fundamental physics of plasma detachment in the linear plasma device, TPD-I, which has a high heat flux and high density plasma in steady state. The existence of a density threshold for plasma detachment was observed in our experiment. It is found that the electron-ion temperature relaxation process is a key to determine the density dependence of the plasma detachment. (orig.).

  10. Marshall N. Rosenbluth Outstanding Doctoral Thesis Award Talk: Simultaneous Measurement of Electron Temperature and Density Fluctuations in the Core of DIII-D Plasmas

    Science.gov (United States)

    White, A. E.

    2009-11-01

    Multi-field fluctuation measurements provide opportunities for rigorous comparison between experiment and nonlinear gyrokinetic turbulence simulations. A unique set of diagnostics on DIII-D allows for simultaneous study of local, long-wavelength (0 < kθρs< 0.5) electron temperature and density fluctuations in the core plasma (0.4 < ρ< 0.8). Previous experiments in L-mode indicate that normalized electron temperature fluctuation levels (40 < f < 400,kHz) increase with radius from ˜0.4% at ρ= 0.5 to ˜2% at ρ=0.8, similar to simultaneously measured density fluctuations. Electron cyclotron heating (ECH) is used to increase Te, which increases electron temperature fluctuation levels and electron heat transport in the experiments. In contrast, long wavelength density fluctuation levels change very little. The different responses are consistent with increased TEM drive relative to ITG-mode drive. A new capability at DIII-D is the measurement of phase angle between electron temperature and density fluctuations using coupled correlation electron cyclotron emission radiometer and reflectometer diagnostics. Linear and nonlinear GYRO runs have been used to design validation experiments that focus on measurements of the phase angle. GYRO shows that if Te and ∇Te increase 50% in a beam-heated L-mode plasma (ρ=0.5), then the phase angle between electron temperature and density fluctuations decreases 30%-50% and electron temperature fluctuation levels increase a factor of two more than density fluctuations. Comparisons between these predictions and experimental results will be presented.

  11. Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography

    Science.gov (United States)

    Sato, Yuta; Tomita, Kentaro; Tsukiyama, Syoichi; Eguchi, Toshiaki; Uchino, Kiichiro; Kouge, Kouichiro; Tomuro, Hiroaki; Yanagida, Tatsuya; Wada, Yasunori; Kunishima, Masahito; Kodama, Takeshi; Mizoguchi, Hakaru

    2017-03-01

    Spatial profiles of the electron density (n e), electron temperature (T e), and average ionic charge (Z) of laser-produced Sn plasmas for EUV lithography, whose conversion efficiency (CE) is sufficiently high for practical use, were measured using a collective Thomson scattering (TS) technique. For plasma production, Sn droplets of 26 µm diameter were used as a fuel. First, a picosecond-pulsed laser was used to expand a Sn target. Next, a CO2 laser was used to generate plasmas. By changing the injection timing of the picosecond and CO2 lasers, three different types of plasmas were generated. The CEs of the three types of plasmas differed, and ranged from 2.8 to 4.0%. Regarding the different plasma conditions, the spatial profiles of n e, T e, and Z clearly differed. However, under all plasma conditions, intense EUV was only observed at a sufficiently high T e (> 25 eV) and in an adequate n e range [1024–(2 × 1025) m‑3]. These plasma parameters lie in the efficient-EUV light source range, as predicted by simulations.

  12. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  13. Numerical studies of independent control of electron density and gas temperature via nonlinear coupling in dual-frequency atmospheric pressure dielectric barrier discharge plasmas

    Science.gov (United States)

    Zhang, Z. L.; Nie, Q. Y.; Wang, Z. B.; Gao, X. T.; Kong, F. R.; Sun, Y. F.; Jiang, B. H.

    2016-07-01

    Dielectric barrier discharges (DBDs) provide a promising technology of generating non-equilibrium cold plasmas in atmospheric pressure gases. For both application-focused and fundamental studies, it is important to explore the strategy and the mechanism for enabling effective independent tuning of key plasma parameters in a DBD system. In this paper, we report numerical studies of effects of dual-frequency excitation on atmospheric DBDs, and modulation as well as separate tuning mechanism, with emphasis on dual-frequency coupling to the key plasma parameters and discharge evolution. With an appropriately applied low frequency to the original high frequency, the numerical calculation demonstrates that a strong nonlinear coupling between two frequencies governs the process of ionization and energy deposition into plasma, and thus raises the electron density significantly (e.g., three times in this case) in comparisons with a single frequency driven DBD system. Nevertheless, the gas temperature, which is mainly determined by the high frequency discharge, barely changes. This method then enables a possible approach of controlling both averaged electron density and gas temperature independently.

  14. Construction of Larger Area Density-Uniform Plasma with Collisional Inductively Coupled Plasma Cells

    Institute of Scientific and Technical Information of China (English)

    OUYANG Liang; LIU Wandong; BAI Xiaoyan; CHEN Zhipeng; WANG Huihui; LI LUO Chen; JI Liangliang; HU Bei

    2007-01-01

    The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma (ICP) cells were measured by a double-probe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.

  15. A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

    Science.gov (United States)

    Iordanova, E.; Palomares, J. M.; Gamero, A.; Sola, A.; van der Mullen, J. J. A. M.

    2009-08-01

    An absolute intensity measurement (AIM) technique is presented that combines the absolute measurements of the line and the continuum emitted by strongly ionizing argon plasmas. AIM is an iterative combination of the absolute line intensity-collisional radiative model (ALI-CRM) and the absolute continuum intensity (ACI) method. The basis of ALI-CRM is that the excitation temperature T13 determined by the method of ALI is transformed into the electron temperature Te using a CRM. This gives Te as a weak function of electron density ne. The ACI method is based on the absolute value of the continuum radiation and determines the electron density in a way that depends on Te. The iterative combination gives ne and Te. As a case study the AIM method is applied to plasmas created by torche à injection axiale (TIA) at atmospheric pressure and fixed frequency at 2.45 GHz. The standard operating settings are a gas flow of 1 slm and a power of 800 W; the measurements have been performed at a position of 1 mm above the nozzle. With AIM we found an electron temperature of 1.2 eV and electron density values around 1021 m-3. There is not much dependence of these values on the plasma control parameters (power and gas flow). From the error analysis we can conclude that the determination of Te is within 7% and thus rather accurate but comparison with other studies shows strong deviations. The ne determination comes with an error of 40% but is in reasonable agreement with other experimental results.

  16. Determination of the Electron Density and Electron Temperature in A Magnetron Discharge Plasma Using Optical Spectroscopy and the Collisional-Radiative Model of Argon

    Science.gov (United States)

    Evdokimov, K. E.; Konishchev, M. E.; Pichugin, V. F.; Pustovalova, A. A.; Ivanova, N. M.; Sun', Ch.

    2017-09-01

    A method for determining the electron temperature and electron density in a plasma is proposed that is based on minimization of the difference between the experimental relative intensities of the spectral argon (Ar) lines and those same intensities calculated with the aid of the collisional-radiative model. The model describes the kinetics of the ground state and 40 excited states of the Ar atom and takes into account the following processes: excitation and deactivation of the states of the atom by electron impact, radiative decay of the excited states, self-absorption of radiation, ionization of excited states by electron impact, and quenching of metastable states as a consequence of collisions with the chamber walls. Using the given method, we have investigated the plasma of a magnetron discharge on a laboratory setup for intermediate-frequency magnetron sputtering for a few selected operating regimes.

  17. Relativistic correction of (v/c)2 to the collective Thomson scattering for high-temperature high-density plasma

    Institute of Scientific and Technical Information of China (English)

    Jiang Chen-Fan-Fu; Zheng Jian; Zhao Bin

    2011-01-01

    Collective Thomson scattering is theoretically investigated with the inclusion of the relativistic correction of (v/c)2.The correction is rather small for the plasma parameters inferred from the spectra of the thermal electron plasma waves in the plasma. Since the full formula of the corrected result is rather complicated,a simplified one is derived for practical use,which is shown to be in good agreement with the un-simplified one.

  18. Density of atoms in Ar*(3p54s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy

    Science.gov (United States)

    Hübner, S.; Sadeghi, N.; Carbone, E. A. D.; van der Mullen, J. J. A. M.

    2013-04-01

    This study presents the absolute argon 1 s (in Paschens's notation) densities and the gas temperature, Tg, obtained in a surfatron plasma in the pressure range 0.65recorded with two tunable diode lasers. Tg is deduced from the absorption line shapes when scanning the laser wavelengths. The line profile, which is a Doppler broadening dominated Gaussian at gas pressures of p 10 mbar, for which the pressure broadening can no more be neglected. Tg is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of Tg at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 1016-1018 m-3, increasing towards the end of the plasma column, decreasing with the pressure. In the low pressure side, a broad minimum is found around 10Radiative Model.

  19. Current drive at plasma densities required for thermonuclear reactors.

    Science.gov (United States)

    Cesario, R; Amicucci, L; Cardinali, A; Castaldo, C; Marinucci, M; Panaccione, L; Santini, F; Tudisco, O; Apicella, M L; Calabrò, G; Cianfarani, C; Frigione, D; Galli, A; Mazzitelli, G; Mazzotta, C; Pericoli, V; Schettini, G; Tuccillo, A A

    2010-08-10

    Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.

  20. Single-step, rapid low-temperature synthesis of Si quantum dots embedded in an amorphous SiC matrix in high-density reactive plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Qijin [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070 (Australia); Xu Shuyan [Plasma Sources and Applications Centre, NIE, Nanyang Technological University, 1 Nanyang Walk 637616 (Singapore); Ostrikov, Kostya, E-mail: Kostya.Ostrikov@csiro.au [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070 (Australia) and School of Physics, University of Sydney, Sydney NSW 2006 (Australia)

    2010-01-15

    A simple, effective and innovative approach based on low-pressure, thermally nonequilibrium, high-density inductively coupled plasmas is proposed to rapidly synthesize Si quantum dots (QDs) embedded in an amorphous SiC (a-SiC) matrix at a low substrate temperature and without any commonly used hydrogen dilution. The experimental results clearly demonstrate that uniform crystalline Si QDs with a size of 3-4 nm embedded in the silicon-rich (carbon content up to 10.7at.%) a-SiC matrix can be formed from the reactive mixture of silane and methane gases, with high growth rates of {approx}1.27-2.34 nm s{sup -1} and at a low substrate temperature of 200 deg. C. The achievement of the high-rate growth of Si QDs embedded in the a-SiC without any commonly used hydrogen dilution is discussed based on the unique properties of the inductively coupled plasma-based process. This work is particularly important for the development of the all-Si tandem cell-based third generation photovoltaic solar cells.

  1. 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.

  2. Modelling of density limit phenomena in toroidal helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K. [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, S.-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Giannone, L. [Max Planck Institut fuer Plasmaphysik, EURATOM-IPP Association, Garching (Germany)

    2000-03-01

    The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS stellarator. (author)

  3. Modelling of density limit phenomena in toroidal helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Giannone, Louis [EURATOM-IPP Association, Max Planck Institut fuer Plasmaphysik, Garching (Germany)

    2001-11-01

    The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the Wendelstein 7-AS (W7-AS) stellarator. (author)

  4. Spectroscopy of Low Temperature Plasma

    CERN Document Server

    Ochkin, Vladimir N

    2009-01-01

    Providing an up-to-date overview on spectroscopical diagnostics of low temperature plasma Spectroscopy of Low Temperature Plasma covers the latest developments and techniques. Written by a distinguished scientist and experienced book author this text is applicable to many fields in materials and surface science as well as nanotechnology and contains numerous appendices with indispensable reference data.

  5. 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.

  6. Plasma probe characteristics in low density hydrogen pulsed plasmas

    CERN Document Server

    Astakhov, D I; Lee, C J; Ivanov, V V; Krivtsun, V M; Zotovich, A I; Zyryanov, S M; Lopaev, D V; Bijkerk, F

    2014-01-01

    Probe theories are only applicable in the regime where the probe's perturbation of the plasma can be neglected. However, it is not always possible to know, a priori, that a particular probe theory can be successfully applied, especially in low density plasmas. This is especially difficult in the case of transient, low density plasmas. Here, we applied probe diagnostics in combination with a 2D particle-in-cell model, to an experiment with a pulsed low density hydrogen plasma. The calculations took into account the full chamber geometry, including the plasma probe as an electrode in the chamber. It was found that the simulations reproduce the time evolution of the probe IV characteristics with good accuracy. The disagreement between the simulated and probe measured plasma density is attributed to the limited applicability of probe theory to measurements of low density pulsed plasmas. Indeed, in the case studied here, probe measurements would lead to a large overestimate of the plasma density. In contrast, the ...

  7. 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.

  8. Thermodynamics of High Temperature Plasmas

    Directory of Open Access Journals (Sweden)

    Ettore Minardi

    2009-03-01

    Full Text Available In this work we discuss how and to what extent the thermodynamic concepts and the thermodynamic formalism can be extended to the description of high temperature states of the plasma not necessarily associated with a Boltzmann distribution and with thermal equilibrium.The discussion is based on the “magnetic or electrostatic entropy concept”, an interpretative and predictive tool based on probability and information, defined in a suitably coarse-grained possibility space of all current density or of all electric charge density distributions under testable constraints, and whose variation properties are proven to be related under certain conditions to the equilibrium and the stability of the system. In the case of magnetic equilibrium the potentiality of the magnetic entropy concept is illustrated by comparing the predictions of the current density and pressure profiles with the observations in different tokamak machines and different tokamak regimes, as well as by showing how the equilibrium and the stability in devices as different as the reversed field pinch or the magnetic well are described by the variation properties of the same entropy functional applied to the different situations. In fact it emerges that the maximum of the entropy can be seen in these different cases as an optimization constraint for the minimum of the magnetic energy. The application of the entropy concept to the electrostatic processes shows in particular that the so-called reactive instabilities (non-dissipative, non-resonant instabilities with a marginal point admit a neighboring state with higher entropy and are therefore of special relevance from the point of view of the physical evolution of the system. In this case the thermodynamic formalism allows the introduction of the concept of “thermodynamic fluctuations” of the macroscopic charge density and provides a method for the calculation of the “thermodynamic” fluctuation levels both on the stable as

  9. Characterization of near-LTE, high-temperature and high-density aluminum plasmas produced by ultra-high intensity lasers

    Science.gov (United States)

    Dervieux, V.; Loupias, B.; Baton, S.; Lecherbourg, L.; Glize, K.; Rousseaux, C.; Reverdin, C.; Gremillet, L.; Blancard, C.; Silvert, V.; Pain, J.-C.; Brown, C. R. D.; Allan, P.; Hill, M. P.; Hoarty, D. J.; Renaudin, P.

    2015-09-01

    Ultra-high-intensity lasers have opened up a new avenue for the creation and detailed spectral measurements of dense plasmas in extreme thermodynamic conditions. In this paper, we demonstrate the possibility of heating a dense plasma (ρ > 1 gcm-3) to a maximum temperature of 560 ± 40 eV using a few-Joule, relativistic-intensity laser pulse. Particle-in-cell, radiation-hydrodynamic and atomic physics simulation tools are used together for a full description of the plasma dynamics, from laser interaction to late-time expansion and x-ray emission, yielding overall good agreement with the spectral measurements. We discuss the sensitivity of our analysis to space-time gradients, non-equilibrium ionization processes and hot electron effects.

  10. Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique

    OpenAIRE

    Ensinger, Wolfgang

    1996-01-01

    Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique / B. Rauschenbach ... - In: Nuclear instruments and methods in physics research. B. 113. 1996. S. 266-269

  11. Temperature relaxation in dense plasma mixtures

    Science.gov (United States)

    Faussurier, Gérald; Blancard, Christophe

    2016-09-01

    We present a model to calculate temperature-relaxation rates in dense plasma mixtures. The electron-ion relaxation rates are calculated using an average-atom model and the ion-ion relaxation rates by the Landau-Spitzer approach. This method allows the study of the temperature relaxation in many-temperature electron-ion and ion-ion systems such as those encountered in inertial confinement fusion simulations. It is of interest for general nonequilibrium thermodynamics dealing with energy flows between various systems and should find broad use in present high energy density experiments.

  12. Mixing in plasma and low density jets

    Science.gov (United States)

    Russ, S.; Strykowski, P. J.; Pfender, E.

    1994-04-01

    This study was undertaken to examine the mechanisms which produce the large entrainment measured near the exit of thermal plasma torches. A research facility was constructed to examine low density jet behavior under similar dimensionless conditions as those produced by thermal plasma spray torches; the Reynolds number based on jet diameter and average properties was 1000, and the ratio of jet to ambient density was 0.07. This very low density jet produced organized vortex structures which were partially responsible for the rapid entrainment of external air. The formation of these organized structures could be disrupted by introducing turbulence, but the rapid entrainment process was not significantly affected. The structure of the jet produced by a commercial plasma torch was examined and compared to the low density research jet. At low gas flow rates the plasma jet also displayed the formation of coherent vortex structures, the passage frequency of which compared favorably with that measured in the low density research jet. At higher gas flow rates the shear layer of the plasma jet rapidly broke down producing relatively small scale turbulence. Visualizations of the hot plasma core were compared against measurements of the torch voltage fluctuations caused by arc instabilities. At low flow rates the arc voltage fluctuations were quite low and the plume was very steady. At higher flow rates the arc voltage fluctuations increased and produced “surging” and “whipping” in the hot potential core. It is believed that this low frequency unsteadiness is partially responsible for the rapid entrainment measured in plasma torches.

  13. Study of Volumetrically Heated Ultra-High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, Jorge J. [Colorado State Univ., Fort Collins, CO (United States)

    2016-10-27

    Heating dense matter to millions of degrees is important for applications, but requires complex and expensive methods. The major goal of the project was to demonstrate using a compact laser the creation of a new ultra-high energy density plasma regime characterized by simultaneous extremely high temperature and high density, and to study it combining experimental measurements and advanced simulations. We have demonstrated that trapping of intense femtosecond laser pulses deep within ordered nanowire arrays can heat near solid density matter into a new ultra hot plasma regime. Extreme electron densities, and temperatures of several tens of million degrees were achieved using laser pulses of only 0.5 J energy from a compact laser. Our x-ray spectra and simulations showed that extremely highly ionized plasma volumes several micrometers in depth are generated by irradiation of gold and Nickel nanowire arrays with femtosecond laser pulses of relativistic intensities. We obtained extraordinarily high degrees of ionization (e.g. we peeled 52 electrons from gold atoms, and up to 26 electrons from nickel atoms). In the process we generated Gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas.. The plasma created after the dissolved wires expand, collide, and thermalize, is computed to have a thermal energy density of 0.3 GJ cm-3 and a pressure of 1-2 Gigabar. These are pressures only exceeded in highly compressed thermonuclear fusion plasmas. Scaling these results to higher laser intensities promises to create plasmas with temperatures and pressures exceeding those in the center of the sun.

  14. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  15. Implementation of a multichannel soft x-ray diagnostic for electron temperature measurements in TJ-II high-density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Baiao, D.; Varandas, C. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, 1049-001 Lisboa (Portugal); Medina, F.; Ochando, M.; Pastor, I. [Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, 28040 Madrid (Spain); Molinero, A.; Chercoles, J. [Laboratorio General de Electronica y Automatica-CIEMAT, 28040 Madrid (Spain)

    2012-10-15

    Based on the multi-foil technique, a multichannel soft x-ray diagnostic for electron temperature measurements has been recently implemented in the TJ-II stellarator. The diagnostic system is composed by four photodiodes arrays with beryllium filters of different thickness. An in-vacuum amplifier board is coupled to each array, aiming at preventing induced noise currents. The Thomson scattering and the vacuum ultraviolet survey diagnostics are used for assessing plasma profiles and composition, being the analysis carried out with the radiation code IONEQ. The electron temperature is determined through the different signal-pair ratios with temporal and spatial resolution. The design and preliminary results from the diagnostic are presented.

  16. High Current, High Density Arc Plasma as a New Source for WiPAL

    Science.gov (United States)

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  17. Interaction of electromagnetic and plasma waves in warm motional plasma: Density and thermal effects

    Science.gov (United States)

    Rashed-Mohassel, P.; Hasanbeigi, A.; Hajisharifi, K.

    2017-08-01

    In this paper, the electromagnetic-electrostatic coupling instability excited in the two-dimensional planar-layered plasma medium with median temperature (warm motional plasma beam) is investigated by applying the initial fluctuation propagating along the planar surfaces. The dielectric tensor, obtained by the Maxwell-fluid model, is used to find the dispersion relation (DR) and different excited modes in the system. Interacting modes are investigated, in detail, by focusing on the effect of temperature on the plasma beam instability aroused by coupling the thermal excited modes (thermal-extraordinary and electron plasma modes) in the systems with various amounts of beam density. The numerical analysis of the obtained DR shows that even though the temperature effect of the plasma beam has an important role on the suppression of streaming instabilities, it does not have a considerable effect on the behavior of the coupling instability in the fluid limitation.

  18. Plasma-density evolution in compact polyacetal capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tomasel, F.G.; Rocca, J.J.; Cortazar, O.D.; Szapiro, B.T. (Electrical Engineering Department, Colorado State University, Fort Collins, Colorado 80523 (United States)); Lee, R.W. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

    1993-05-01

    We have measured the temporal evolution of the electron density of plasmas produced in polyacetal capillaries with diameters between 0.5 and 1.5 mm excited by 110-ns full-width-at-half-maximum discharge pulses with currents between 13 and 42 kA. The electron density was determined from Stark-broadened line profiles of the 4[ital f]-3[ital d] O VI transition taking into account opacity effects. The electron density was found to increase continuously during the rise of the current pulse, and to decrease near the end of the current pulse, when a drop in plasma temperature causes the degree of ionization of the plasma to decrease. The peak plasma density in a 1-mm capillary excited by a 24-kA pulse was measured to be 5[times]10[sup 19] cm[sup [minus]3]. The plasma density was observed to increase linearly with discharge energy from 7.5[times]10[sup 18] cm[sup [minus]3] for a 5-J discharge to 5[times]10[sup 19] cm[sup [minus]3] for a 30-J discharge in a 1.5-mm-diam. capillary.

  19. The Density of Coronal Plasma in Active Stellar Coronae

    CERN Document Server

    Testa, P; Peres, G; Testa, Paola; Drake, Jeremy J.; Peres, Giovanni

    2004-01-01

    We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer on {\\em Chandra} in order to investigate their coronal plasma density. Densities where investigated using the lines of the He-like ions O VII, Mg XI, and Si XIII. While Si XIII lines in all stars of the sample are compatible with the low-density limit, Mg XI lines betray the presence of high plasma densities ($> 10^{12}$ cm$^{-3}$) for most of the sources with higher X-ray luminosity ($> 10^{30}$ erg/s); stars with higher $L_X$ and $L_X/L_{bol}$ tend to have higher densities at high temperatures. Ratios of O VII lines yield much lower densities of a few $10^{10}$ cm$^{-3}$, indicating that the ``hot'' and ``cool'' plasma resides in physically different structures. Our findings imply remarkably compact coronal structures, especially for the hotter plasma emitting the Mg XI lines characterized by coronal surface filling factor, $f_{MgXI}$, ranging from $10^{-4}$ to $10^{-...

  20. Perturbing microwave beams by plasma density fluctuations

    Directory of Open Access Journals (Sweden)

    Köhn Alf

    2017-01-01

    Full Text Available The propagation of microwaves across a turbulent plasma density layer is investigated with full-wave simulations. To properly represent a fusion edge-plasma, drift-wave turbulence is considered based on the Hasegawa-Wakatani model. Scattering and broadening of a microwave beam whose amplitude distribution is of Gaussian shape is studied in detail as a function of certain turbulence properties. Parameters leading to the strongest deterioration of the microwave beam are identified and implications for existing experiments are given.

  1. A simple and straightforward expression for curling probe electron density diagnosis in reactive plasmas

    Science.gov (United States)

    Arshadi, Ali; Brinkmann, Ralf Peter; Hotta, Masaya; Nakamura, Keiji

    2017-04-01

    Active plasma resonance spectroscopy (APRS) refers to the family of plasma diagnostic methods which utilize the ability of plasmas to resonate at frequencies close to the plasma frequency. APRS operates by exciting the plasma with a weak RF signal by means of a small electric probe. The response of the plasma is recorded by a network analyzer (NA). A mathematical model is applied to derive characteristics like the electron density and the electron temperature. The curling probe is a promising realization of APRS. The curling probe is well-qualified for the local measurement of the electron density in reactive plasmas. This spiral probe resonates in plasma at a larger density dependent frequency than the plasma frequency. This manuscript represents a simple and straightforward expression relating this resonance frequency to the electron density of the plasma. A good agreement is observed between the proposed expression and the results obtained from previous studies and numerical simulations.

  2. Low temperature plasma technology methods and applications

    CERN Document Server

    Chu, Paul K

    2013-01-01

    Written by a team of pioneering scientists from around the world, Low Temperature Plasma Technology: Methods and Applications brings together recent technological advances and research in the rapidly growing field of low temperature plasmas. The book provides a comprehensive overview of related phenomena such as plasma bullets, plasma penetration into biofilms, discharge-mode transition of atmospheric pressure plasmas, and self-organization of microdischarges. It describes relevant technology and diagnostics, including nanosecond pulsed discharge, cavity ringdown spectroscopy, and laser-induce

  3. Density and Temperature Measurements in a Solar Active Region

    Science.gov (United States)

    Warren, Harry P.; Winebarger, Amy R.

    2003-10-01

    We present electron density and temperature measurements from an active region observed above the limb with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory. Density-sensitive line ratios from Si VIII and S X indicate densities greater than 108 cm-3 as high as 200" (or 145 Mm) above the limb. At these heights, static, uniformly heated loop models predict densities close to 107 cm-3. Differential emission measure analysis shows that the observed plasma is nearly isothermal with a mean temperature of about 1.5 MK and a dispersion of about 0.2 MK. Both the differential emission measure and the Si XI/Si VIII line ratios indicate only small variations in the temperature at the heights observed. These measurements confirm recent observations from the Transition Region and Coronal Explorer of ``overdense'' plasma at temperatures near 1 MK in solar active regions. Time-dependent hydrodynamic simulations suggest that impulsive heating models can account for the large densities, but they have a difficult time reproducing the narrow range of observed temperatures. The observations of overdense, nearly isothermal plasma in the solar corona provide a significant challenge to theories of coronal heating.

  4. Lattice QCD Results at Finite Temperature and Density

    CERN Document Server

    Fodor, Z

    2003-01-01

    Recent lattice results on QCD at finite temperatures and densities are reviewed. Two new and independent techniques give compatible results for physical quantities. The phase line separating the hadronic and quark-gluon plasma phases, the critical endpoint and the equation of state are discussed.

  5. Calculation of Ion Equilibrium Temperature in Ultracold Neutral Plasmas

    Institute of Scientific and Technical Information of China (English)

    李金星; 曹明涛; 韩亮; 齐越蓉; 张首刚; 高宏; 李福利; T.C.Killian

    2011-01-01

    We provide a fast iteration method to calculate the ion equilibrium temperature in an ultracold neutral plasma (UNP). The temperature as functions of electron initial temperature and ion density is obtained and compared with the recent UNP experimental data. The theoretical predictions agree with the experimental results very well. The calculated ion equilibrium temperature by this method can be applied to study the UNP expansion process more effectively.%We provide a fast iteration method to calculate the ion equilibrium temperature in an ultracold neutral plasma (UNP).The temperature as functions of electron initial temperature and ion density is obtained and compared with the recent UNP experimental data.The theoretical predictions agree with the experimental results very well.The calculated ion equilibrium temperature by this method can be applied to study the UNP expansion process more effectively.

  6. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    Science.gov (United States)

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic upd...

  7. Relativistic QED Plasma at Extremely High Temperature

    CERN Document Server

    Masood, Samina S

    2016-01-01

    Renormalization scheme of QED (Quantum Electrodynamics) at high temperatures is used to calculate the effective parameters of relativistic plasma in the early universe. Renormalization constants of QED play role of effective parameters of the theory and can be used to determine the collective behavior of the medium. We explicitly show that the dielectric constant, magnetic reluctivity, Debye length and the plasma frequency depend on temperature in the early universe. Propagation speed, refractive index, plasma frequency and Debye shielding length of a QED plasma are computed at extremely high temperatures in the early universe. We also found the favorable conditions for the relativistic plasma from this calculations.

  8. Residual gas entering high density hydrogen plasma: rarefaction due to rapid heating

    NARCIS (Netherlands)

    N. den Harder,; D.C. Schram,; W. J. Goedheer,; de Blank, H. J.; M. C. M. van de Sanden,; van Rooij, G. J.

    2015-01-01

    The interaction of background molecular hydrogen with magnetized (0.4 T) high density (1–5 × 10 20  m −3 ) low temperature (∼3 eV) hydrogen plasma was inferred from the Fulcher band emission in the linear plasma generator Pilot-PSI. In the plasma center,

  9. The expansion of a collisionless plasma into a plasma of lower density

    Energy Technology Data Exchange (ETDEWEB)

    Perego, M.; Gunzburger, M. D. [Department of Scientific Computing, Florida State University, Tallahassee, Florida 32306 (United States); Howell, P. D.; Ockendon, J. R.; Allen, J. E. [OCIAM, Mathematical Institute, Oxford University, 24-29 St Giles, OX1 3LB Oxford (United Kingdom)

    2013-05-15

    This paper considers the asymptotic and numerical solution of a simple model for the expansion of a collisionless plasma into a plasma of lower density. The dependence on the density ratio of qualitative and quantitative features of solutions of the well-known cold-ion model is explored. In the cold-ion limit, we find that a singularity develops in the ion density in finite time unless the density ratio is zero or close to unity. The classical cold-ion model may cease to be valid when such a singularity occurs and we then regularize the model by the finite ion-temperature Vlasov-Poisson system. Numerical evidence suggests the emergence of a multi-modal velocity distribution.

  10. Electron density and temperature study of plasmas using a millimeter-wave Fabry-Perot interferometer; Etude de la densite electronique et de la temperature de plasmas a l'aide d'un interferometre Fabry-Perot en ondes millimetriques

    Energy Technology Data Exchange (ETDEWEB)

    Bize, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The contents of this article, which have been used as a basis for a State doctorate thesis, deal with research into focussing systems of the Fabry-Perot, millimetre wave type. With the help of this equipment, measurements have been made of the electronic density using interferometry in the range from 10{sup 9} to 10{sup 14} electrons/cm{sup 3}, and of the electron temperature by Thomson diffusion, of plasmas formed by laser ionisation and by high frequency. (author) [French] Le contenu de cet article, qui a fait l'objet d'une these d'Etat, se rapporte a l'etude des systemes focalisant de type Fabry-Perot en ondes millimetriques. A l'aide de ces dispositifs, on mesure la densite electronique par interferometrie dans la gamme de densites de 10{sup 9} a 10{sup 14} e/cm{sup 3} et la temperature electronique par diffusion Thomson de plasmas crees par ionisation laser et par haute frequence. (auteur)

  11. Temperature measurements in thermal plasmas; Mesures de temperatures dans les plasmas thermiques

    Energy Technology Data Exchange (ETDEWEB)

    Fauchais, P.; Coudert, J.F. [Limoges Univ., 87 (France)

    1996-05-01

    Thermal plasmas are characterized by a high pressure (10{sup 4} to 10{sup 6} Pa) and a high density of particles. Plasmas considered in this paper are produced by electric discharges, arcs, injection torches with cold or hot cathodes, water vortex torches, RF devices and are characterized by temperatures ranging from 6000 to 40000 K and ionization energies ranging from 13.5 and 16 eV (in argon, argon-hydrogen, nitrogen, nitrogen-hydrogen, argon-helium, air, oxygen, CO{sub 2} or water). Temperature measurements in thermal plasmas are difficult due to their extreme luminosity, flow rate and thermal flux, and to their temperature and flow rate gradients. The most common measurement methods are the emission spectroscopy, the laser scattering (Rayleigh, Thomson and coherent anti-Stokes Raman scattering) and the enthalpy probes. The first two methods are non-intrusive, while the last method is intrusive. This paper gives first some general remarks about the principles of each technique and focusses on the problem of fluctuations due to the plasma jet instabilities. Then, it describes briefly each technique and gives some examples of results. Finally, it compares the spectroscopic measurements with other measurements. (J.S.) 80 refs.

  12. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    Science.gov (United States)

    Rawat, R. S.

    2015-03-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  13. Kinetics and spectroscopy of low temperature plasmas

    CERN Document Server

    Loureiro, Jorge

    2016-01-01

    This is a comprehensive textbook designed for graduate and advanced undergraduate students. Both authors rely on more than 20 years of teaching experience in renowned Physics Engineering courses to write this book addressing the students’ needs. Kinetics and Spectroscopy of Low Temperature Plasmas derives in a full self-consistent way the electron kinetic theory used to describe low temperature plasmas created in the laboratory with an electrical discharge, and presents the main optical spectroscopic diagnostics used to characterize such plasmas. The chapters with the theoretical contents make use of a deductive approach in which the electron kinetic theory applied to plasmas with basis on the electron Boltzmann equation is derived from the basic concepts of Statistical and Plasma Physics. On the other hand, the main optical spectroscopy diagnostics used to characterize experimentally such plasmas are presented and justified from the point of view of the Atomic and Molecular Physics. Low temperature plasmas...

  14. Interaction of bovine serum albumin and human blood plasma with PEO-tethered surfaces : influence of PEO chain length, grafting density and temperature

    NARCIS (Netherlands)

    Norde, W.; Gage, R.A.

    2004-01-01

    Solid surfaces are modified by grafting poly(ethylene oxide), PEO, to influence their interaction with indwelling particles, in particular molecules of bovine serum albumin and human plasma proteins. As a rule, the grafted PEO layers suppress protein adsorption. The suppression is most effective whe

  15. Energy density dependence of hydrogen combustion efficiency in atmospheric pressure microwave plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T.; Ezumi, N. [Nagano National College of Technology, Nagano-city, Nagano (Japan); Sawada, K. [Shinshu University, Nagano-city, Nagano (Japan); Tanaka, Y. [Kanazawa University, Kakuma-cho, Kanzawa-city, Ishikawa (Japan); Tanaka, M.; Nishimura, K. [National Insitute for Fusion Science, Toki-city, Gifu (Japan)

    2015-03-15

    The recovery of tritium in nuclear fusion plants is a key issue for safety. So far, the oxidation procedure using an atmospheric pressure plasma is expected to be part of the recovery method. In this study, in order to clarify the mechanism of hydrogen oxidation by plasma chemistry, we have investigated the dependence of hydrogen combustion efficiency on gas flow rate and input power in the atmospheric pressure microwave plasma. It has been found that the combustion efficiency depends on energy density of absorbed microwave power. Hence, the energy density is considered as a key parameter for combustion processes. Also neutral gas temperatures inside and outside the plasma were measured by an optical emission spectroscopy method and thermocouple. The result shows that the neutral gas temperature in the plasma is much higher than the outside temperature of plasma. The high neutral gas temperature may affect the combustion reaction. (authors)

  16. Self-sustained focusing of high-density streaming plasma

    Science.gov (United States)

    Bugaev, A.; Dobrovolskiy, A.; Goncharov, A.; Gushenets, V.; Litovko, I.; Naiko, I.; Oks, E.

    2017-01-01

    We describe our observations of the transport through an electrostatic plasma lens of a wide-aperture, high-current, low energy, metal-ion plasma flow produced by a cathodic arc discharge. The lens input aperture was 80 mm, the length of the lens was 140 mm, and there were three electrostatic ring electrodes located in a magnetic field formed by permanent magnets. The lens outer electrodes were grounded and the central electrode was biased up to -3 kV. The plasma was a copper plasma with directed (streaming) ion energy 20-40 eV, and the equivalent ion current was up to several amperes depending on the potential applied to the central lens electrode. We find that when the central lens electrode is electrically floating, the current density of the plasma flow at the lens focus increases by up to 40%-50%, a result that is in good agreement with a theoretical treatment based on plasma-optical principles of magnetic insulation of electrons and equipotentialization along magnetic field lines. When the central lens electrode is biased negatively, an on-axis stream of energetic electrons is formed, which can also provide a mechanism for focusing of the plasma flow. Optical emission spectra under these conditions show an increase in intensity of lines corresponding to both copper atoms and singly charged copper ions, indicating the presence of fast electrons within the lens volume. These energetic electrons, as well as accumulating on-axis and providing ion focusing, can also assist in reducing the microdroplet component in the dense, low-temperature, metal plasma.

  17. Investigation of the Electronic Structure of Solid Density Plasmas by X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gregori, G; Glenzer, S H; Forest, F J; Kuhlbrodt, S; Redmer, R; Faussurier, G; Blancard, C; Renaudin, P; Landen, O L

    2003-05-19

    We present an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. We use our theory to interpret x-ray scattering experiments from solid density carbon plasma and to extract accurate measurements of electron temperature, electron density and charge state. We use our experimental results to validate various equation-of-state models for carbon plasmas.

  18. Electronic Structure Measurement of Solid Density Plasmas using X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gregori, G; Glenzer, S H; Rogers, F J; Landen, O L; Blancard, C; Faussurier, G; Renaudin, P; Kuhlbrodt, S; Redmer, R

    2003-08-23

    We present an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. We use our theory to interpret x-ray scattering experiments from solid density carbon plasma and to extract accurate measurements of electron temperature, electron density and charge state. We use our experimental results to validate various equation-of-state models for carbon plasmas.

  19. Plasma Density Measurements on Refuelling by Solid Hydrogen Pellets in a Rotating Plasma

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, A. H.

    1978-01-01

    The authors used laser interferometry to directly measure the increase in plasma density caused by the ablation of a solid hydrogen pellet situated in a rotating plasma.......The authors used laser interferometry to directly measure the increase in plasma density caused by the ablation of a solid hydrogen pellet situated in a rotating plasma....

  20. Plasma density perturbation caused by probes at low gas pressure

    Science.gov (United States)

    Sternberg, Natalia; Godyak, Valery

    2017-09-01

    An analysis of plasma parameter perturbations caused by a spherical probe immersed into a spherical plasma is presented for arbitrary collisionality and arbitrary ratios of probe to plasma dimensions. The plasma was modeled by the fluid plasma equations with ion inertia and nonlinear ion friction force that dominate plasma transport at low gas pressures. Significant depletion of the plasma density around the probe surface has been found. The area of plasma depletion coincides with the sensing area of different kinds of magnetic and microwave probes and will therefore lead to errors in data inferred from measurements with such probes.

  1. On the intergalactic temperature-density relation

    Science.gov (United States)

    McQuinn, Matthew; Upton Sanderbeck, Phoebe R.

    2016-02-01

    Cosmological simulations of the low-density intergalactic medium exhibit a strikingly tight power-law relation between temperature and density that holds over two decades in density. It is found that this relation should roughly apply Δz ˜ 1-2 after a reionization event, and this limiting behaviour has motivated the power-law parameterizations used in most analyses of the Ly α forest. This relation has been explained by using equations linearized in the baryonic overdensity (which does not address why a tight power-law relation holds over two decades in density) or by equating the photoheating rate with the cooling rate from cosmological expansion (which we show is incorrect). Previous explanations also did not address why recombination cooling and Compton cooling off of the cosmic microwave background, which are never negligible, do not alter the character of this relation. We provide an understanding for why a tight power-law relation arises for unshocked gas at all densities for which collisional cooling is unimportant. We also use our results to comment on (1) how quickly fluctuations in temperature redshift away after reionization processes, (2) how much shock heating occurs in the low-density intergalactic medium, and (3) how the temperatures of collapsing gas parcels evolve.

  2. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y; Mazzucato, E; Guttenfelder, W; Bell, R E; Domier, C W; LeBlanc, B P; Lee, K C; Luhmann Jr, N C; Smith, D R

    2011-03-21

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k⊥ρs ≤10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  3. Temperature estimates for a railgun plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Kowalenko, Victor [School of Physics, University of Melbourne, VIC (Australia); Clark, Gregory A

    2000-02-07

    A free-flowing plasma in a railgun refers to a plasma which is not impeded by a projectile during a firing. One advantage in performing experiments with such plasmas is that spectroscopic measurements can be made when they are ejected. In this paper we analyse absorption and emission spectra of a free-flowing plasma for wavelengths between 300 and 625 nm in several firings. Calculations of the degree of ionization for the various species identified on the spectra are used to produce an estimate for the temperature of a free-flowing plasma in a RAPID railgun that lies between 11x10{sup 3} and 25x10{sup 3} K. This temperature range is reduced to 11x10{sup 3} K by using a special computer code that predicts the thermochemical functions and transport coefficients of partially- and fully-ionized plasmas. The code is then used to develop temperature estimates of the plasma armature in railgun firings with projectiles. For these plasmas, which are expected to be denser than free-flowing plasmas, a temperature estimate of 14x10{sup 3} K is obtained for a RAPID railgun firing at shot-out. (author)

  4. SOL plasma measurements during high density and long duration current drive on TRIAM-1M

    Energy Technology Data Exchange (ETDEWEB)

    Takemura, Takeharu; Kawasaki, Shoji; Jotaki, Eriko; Makino, Ken-ichi; Sakamoto, Mizuki; Nakamura, Kazuo; Nakamura, Yukio; Itoh, Sanae; Itoh, Satoshi [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics

    1997-02-01

    In the superconducting, strong magnetic field tokamak, TRIAM-1M, for the purpose of maintaining high density plasma for long time, the current drive experiment using 8.2 GHz lower hybrid wave has been carried out. For maintaining high density plasma for long time, it is indispensable to control gas puff and recycling from wall, as these are closely related to the structure and characteristics of boundary plasma including scrape-off layer (SOL). In this study, in the high density, long time current drive using 8.2 GHz lower hybrid wave, the electron density and electron temperature of SOL plasma were measured by using double probe, and the z-direction distribution and the toroidal magnetic field dependence of the electron density and electron temperature of SOL plasma were examined and compared with OH discharge. Also the dependence of the electron density of SOL plasma on the phase difference in a adjoining waveguide tubes was examined. The experimental setup and the double probe theory are explained. The experimental results of the change with time lapse, the z-direction distribution and the magnetic field dependence of the electron density and electron temperature of SOL plasma are reported. (K.I.)

  5. [Low temperature plasma technology for biomass refinery].

    Science.gov (United States)

    Fu, Xiaoguo; Chen, Hongzhang

    2014-05-01

    Biorefinery that utilizes renewable biomass for production of fuels, chemicals and bio-materials has become more and more important in chemical industry. Recently, steam explosion technology, acid and alkali treatment are the main biorefinery treatment technologies. Meanwhile, low temperature plasma technology has attracted extensive attention in biomass refining process due to its unique chemical activity and high energy. We systemically summarize the research progress of low temperature plasma technology for pretreatment, sugar platflow, selective modification, liquefaction and gasification in biomass refinery. Moreover, the mechanism of low temperature plasma in biorefinery and its further development were also discussed.

  6. Scalar perturbations in two-temperature cosmological plasmas

    NARCIS (Netherlands)

    Moortgat, J.B.; Marklund, M.

    2006-01-01

    We study the properties of density perturbations of a two-component plasma with a temperature difference on a homogeneous and isotropic background. For this purpose, we extend the general relativistic gauge-invariant and covariant (GIC) perturbation theory to include a multifluid with a particular e

  7. A control approach for plasma density in tokamak machines

    Energy Technology Data Exchange (ETDEWEB)

    Boncagni, Luca, E-mail: luca.boncagni@enea.it [EURATOM – ENEA Fusion Association, Frascati Research Center, Division of Fusion Physics, Rome, Frascati (Italy); Pucci, Daniele; Piesco, F.; Zarfati, Emanuele [Dipartimento di Ingegneria Informatica, Automatica e Gestionale ' ' Antonio Ruberti' ' , Sapienza Università di Roma (Italy); Mazzitelli, G. [EURATOM – ENEA Fusion Association, Frascati Research Center, Division of Fusion Physics, Rome, Frascati (Italy); Monaco, S. [Dipartimento di Ingegneria Informatica, Automatica e Gestionale ' ' Antonio Ruberti' ' , Sapienza Università di Roma (Italy)

    2013-10-15

    Highlights: •We show a control approach for line plasma density in tokamak. •We show a control approach for pressure in a tokamak chamber. •We show experimental results using one valve. -- Abstract: In tokamak machines, chamber pre-fill is crucial to attain plasma breakdown, while plasma density control is instrumental for several tasks such as machine protection and achievement of desired plasma performances. This paper sets the principles of a new control strategy for attaining both chamber pre-fill and plasma density regulation. Assuming that the actuation mean is a piezoelectric valve driven by a varying voltage, the proposed control laws ensure convergence to reference values of chamber pressure during pre-fill, and of plasma density during plasma discharge. Experimental results at FTU are presented to discuss weaknesses and strengths of the proposed control strategy. The whole system has been implemented by using the MARTe framework [1].

  8. Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers

    CERN Document Server

    Höll, A

    2006-01-01

    We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.

  9. Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Holl, A; Bornath, T; Cao, L; Doppner, T; Dusterer, S; Forster, E; Fortmann, C; Glenzer, S H; Gregori, G; Laarmann, T; Meiwes-Broer, K H; Przystawik, A; Radcliffe, P; Redmer, R; Reinholz, H; Ropke, G; Thiele, R; Tiggesbaumker, J; Toleikis, S; Truong, N X; Tschentscher, T; Uschmann, I; Zastrau, U

    2006-11-21

    We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.

  10. Industrial Applications of Low Temperature Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bardsley, J N

    2001-03-15

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed.

  11. High-Density Plasma Reactors: Simulations for Design

    Science.gov (United States)

    Hash, David B.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1998-01-01

    The development of improved and more efficient plasma reactors is a costly process for the semiconductor industry. Until five years ago, the Industry made most of its advancements through a trial and error approach. More recently, the role of computational modeling in the design process has increased. Both conventional computational fluid dynamics (CFD) techniques like Navier-Stokes solvers as well as particle simulation methods are used to model plasma reactor flowfields. However, since high-density plasma reactors generally operate at low gas pressures on the order of 1 to 10 mTorr, a particle simulation may be necessary because of the failure of CFD techniques to model rarefaction effects. The direct simulation Monte Carlo method is the most widely accepted and employed particle simulation tool and has previously been used to investigate plasma reactor flowfields. A plasma DSMC code is currently under development at NASA Ames Research Center with its foundation as the object-oriented parallel Cornell DSMC code, MONACO. The present investigation is a follow up of a neutral flow investigation of the effects of process parameters as well as reactor design on etch rate and etch rate uniformity. The previous work concentrated on silicon etch of a chlorine flow in a configuration typical of electron cyclotron resonance (ECR) or helical resonator type reactors. The effects of the plasma on the dissociation chemistry were modeled by making assumptions about the electron temperature and number density. The electrons or ions themselves were not simulated.The present work extends these results by simulating the charged species.The electromagnetic fields are calculated such that power deposition is modeled self-consistently. Electron impact reactions are modeled along with mechanisms for charge exchange. An bipolar diffusion assumption is made whereby electrons remain tied to the ions. However, the velocities of tile electrons are allowed to be modified during collisions

  12. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    Science.gov (United States)

    Adamovich, I.; Baalrud, S. D.; Bogaerts, A.; Bruggeman, P. J.; Cappelli, M.; Colombo, V.; Czarnetzki, U.; Ebert, U.; Eden, J. G.; Favia, P.; Graves, D. B.; Hamaguchi, S.; Hieftje, G.; Hori, M.; Kaganovich, I. D.; Kortshagen, U.; Kushner, M. J.; Mason, N. J.; Mazouffre, S.; Mededovic Thagard, S.; Metelmann, H.-R.; Mizuno, A.; Moreau, E.; Murphy, A. B.; Niemira, B. A.; Oehrlein, G. S.; Petrovic, Z. Lj; Pitchford, L. C.; Pu, Y.-K.; Rauf, S.; Sakai, O.; Samukawa, S.; Starikovskaia, S.; Tennyson, J.; Terashima, K.; Turner, M. M.; van de Sanden, M. C. M.; Vardelle, A.

    2017-08-01

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.

  13. Separation of finite electron temperature effect on plasma polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki (Japan)

    2012-12-15

    This study demonstrates the separation of the finite electron temperature on the plasma polarimetry in the magnetic confined fusion plasma for the first time. Approximate solutions of the transformed Stokes equation, including the relativistic effect, suggest that the orientation angle, {theta}, and ellipticity angle, {epsilon}, of polarization state have different dependency on the electron density, n{sub e}, and the electron temperature, T{sub e}, and that the separation of n{sub e} and T{sub e} from {theta} and {epsilon} is possible in principle. We carry out the equilibrium and kinetic reconstruction of tokamak plasma when the central electron density was 10{sup 20} m{sup -3}, and the central electron temperatures were 5, 10, 20, and 30 keV. For both cases when a total plasma current, I{sub p}, is known and when I{sub p} is unknown, the profiles of plasma current density, j{sub {phi}}, n{sub e}, and T{sub e} are successfully reconstructed. The reconstruction of j{sub {phi}} without the information of I{sub p} indicates the new method of I{sub p} measurement applicable to steady state operation of tokamak.

  14. Separation of finite electron temperature effect on plasma polarimetry.

    Science.gov (United States)

    Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

    2012-12-01

    This study demonstrates the separation of the finite electron temperature on the plasma polarimetry in the magnetic confined fusion plasma for the first time. Approximate solutions of the transformed Stokes equation, including the relativistic effect, suggest that the orientation angle, θ, and ellipticity angle, ε, of polarization state have different dependency on the electron density, n(e), and the electron temperature, T(e), and that the separation of n(e) and T(e) from θ and ε is possible in principle. We carry out the equilibrium and kinetic reconstruction of tokamak plasma when the central electron density was 10(20) m(-3), and the central electron temperatures were 5, 10, 20, and 30 keV. For both cases when a total plasma current, I(p), is known and when I(p) is unknown, the profiles of plasma current density, j(φ), n(e), and T(e) are successfully reconstructed. The reconstruction of j(φ) without the information of I(p) indicates the new method of I(p) measurement applicable to steady state operation of tokamak.

  15. Equatorial plasma bubbles with enhanced ion and electron temperatures

    Science.gov (United States)

    Park, Jaeheung; Min, Kyoung Wook; Kim, Vitaly P.; Kil, Hyosub; Su, Shin-Yi; Chao, Chi Kuang; Lee, Jae-Jin

    2008-09-01

    While the ion and electron temperatures inside equatorial plasma bubbles (EPBs) are normally lower than those in an ambient plasma, bubbles with enhanced temperatures (BETs) are found occasionally in the topside ionosphere. Here we report the characteristics of BETs identified from observations of the first Republic of China Satellite (ROCSAT-1), the first Korea Multi-purpose Satellite (KOMPSAT-1), and the Defense Meteorological Satellite Program (DMSP) F15 during the solar maximum period between 2000 and 2001. The oxygen ion fraction inside the BETs, which was no lower than that of the ambient ionosphere, was similar to the case of ordinary low-temperature EPBs. These observations indicate that the BETs and low-temperature EPBs detected on the topside were produced by the upward drift of low-density plasma from lower altitudes. The feature that distinguishes BETs from normal EPBs is the occurrence of an unusually fast poleward field-aligned plasma flow relative to the ambient plasma. The BETs occurred preferentially around geomagnetic latitudes of 10° in the summer hemisphere, where the ambient ion and electron temperatures are lower than those in the conjugate winter hemisphere. The occurrence of BETs did not show any notable dependence on geomagnetic activities. The characteristics of the BETs suggest that the BETs were produced by adiabatic plasma heating associated with a fast poleward oxygen ion transport along magnetic flux tubes.

  16. Waves in relativistic electron beam in low-density plasma

    Science.gov (United States)

    Sheinman, I.; Sheinman (Chernenco, J.

    2016-11-01

    Waves in electron beam in low-density plasma are analyzed. The analysis is based on complete electrodynamics consideration. Dependencies of dispersion laws from system parameters are investigated. It is shown that when relativistic electron beam is passed through low-density plasma surface waves of two types may exist. The first type is a high frequency wave on a boundary between the beam and neutralization area and the second type wave is on the boundary between neutralization area and stationary plasma.

  17. Workshop on extremely high energy density plasmas and their diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Shozo (ed.)

    2001-09-01

    Compiled are the papers presented at the workshop on 'Extremely High Energy Density Plasmas and Their Diagnostics' held at National Institute for Fusion Science. The papers cover physics and applications of extremely high-energy density plasmas such as dense z-pinch, plasma focus, and intense pulsed charged beams. Separate abstracts were presented for 7 of the papers in this report. The remaining 25 were considered outside the subject scope of INIS. (author)

  18. Radiation from High Temperature Plasmas.

    Science.gov (United States)

    1980-09-09

    PERFORMING ORGANIZATION NAME AND ADDRESS IO7PUOAM i. .’- "--"--o TASK AREA & WORK UNIT NUMIERS SI I. CONTROLLING OFFICE NAME AND ADDRESS .... D...8217’ -REPORT OATM September 19 14. MONITOING AGENCY NAME & AOORESS(I! dilfl ,rn lm Controlling Office) IS. SECURITY CLASS. (of tli repot) Unclassified 1S...together (specifically 25-50 X, in aluminum) id show comparable intensities is an indicatiou oE a rather substantial temperatura aradient in the plasma

  19. Droplet-free high-density metal ion source for plasma immersion ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Keiji [Department of Electrical Engineering, College of Engineering, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501 (Japan)]. E-mail: nakamura@solan.chubu.ac.jp; Yoshinaga, Hiroaki [Department of Electrical Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Yukimura, Ken [Department of Electrical Engineering, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0321 (Japan)

    2006-01-15

    This paper reports on plasma parameters and ion composition of droplet-free Zr ion source for plasma immersion ion implantation and deposition (PIII and D). Zirconium (Zr) ions were obtained by ionizing sputtered Zr atoms in inductively-coupled argon discharge. The characteristics of plasma density, plasma potential and electron temperature were typical ones of such a inductive discharge, and the plasma parameters were not significantly influenced by mixing the sputtered Zr atoms into the plasma. Actually, the main ionic component was still Ar{sup +} ions, and the ion density ratio of [Zr{sup +}]/[Ar{sup +}] was as low as {approx}8%. Increase in sputtering rate of the Zr source will be necessary to improve the ion density ratio.

  20. Density Dependence of Particle Transport in ECH Plasmas of the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, V. I.; Lopez-Bruna, D.; Guasp, J.; Herranz, J.; Estrada, T.; Medina, F.; Ochando, M.A.; Velasco, J.L.; Reynolds, J.M.; Ferreira, J.A.; Tafalla, D.; Castejon, F.; Salas, A.

    2009-05-21

    We present the experimental dependence of particle transport on average density in electron cyclotron heated (ECH) hydrogen plasmas of the TJ-II stellarator. The results are based on: (I) electron density and temperature data from Thomson Scattering and reflectometry diagnostics; (II) a transport model that reproduces the particle density profiles in steady state; and (III) Eirene, a code for neutrals transport that calculates the particle source in the plasma from the particle confinement time and the appropriate geometry of the machine/plasma. After estimating an effective particle diffusivity and the particle confinement time, a threshold density separating qualitatively and quantitatively different plasma transport regimes is found. The poor confinement times found below the threshold are coincident with the presence of ECH-induced fast electron losses and a positive radial electric field all over the plasma. (Author) 40 refs.

  1. Collimation of fast electrons in critical density plasma channel

    OpenAIRE

    2015-01-01

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is generated through the interaction of ultra-intense laser light with a uniform critical density plasma in experiments and 2D PIC simulations. In the experiment, the uniform critical density plasma is created by ionizing an ultra-low density foam target. The spacial distribution of the fast electron is observed by Imaging Plate. 2D PIC simulation and post process analysis reveal magnetic collimation of energetic e...

  2. Atomic processes in high-density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    More, R.M.

    1982-12-21

    This review covers dense atomic plasmas such as that produced in inertial confinement fusion. The target implosion physics along with the associated atomic physics, i.e., free electron collision phenomena, electron states I, electron states II, and nonequilibrium plasma states are described. (MOW)

  3. CO{sub 2} laser diagnostics for measurements of the plasma density profile and plasma density fluctuations on LHD

    Energy Technology Data Exchange (ETDEWEB)

    Vyacheslavov, L.N. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Tanaka, K.; Kawahata, K. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2001-04-01

    A CO{sub 2} laser based diagnostics complimentary to the existing FIR interferometer is proposed. It combines interferometry for plasma density profile measurement under conditions of large density gradients, and both imaging and scattering techniques for observation of plasma fluctuations. Two-colour interferometer with a slablike probe beam and a single multichannel linear detector array provide observation of plasma density profile and density fluctuations at two locations along the probe beam. Basic characteristics of the diagnostics are considered as well as some effects that include dispersion and are critical for two colour imaging technique. The results of the bench-top experiments with the prototype of the interferometer are presented. (author)

  4. On the intergalactic temperature-density relation

    CERN Document Server

    McQuinn, Matthew

    2015-01-01

    Cosmological simulations of the low-density intergalactic medium exhibit a strikingly tight power-law relation between temperature and density that holds over two decades in density. It is found that this relation should roughly apply Delta z ~ 1-2 after a reionization event, and this limiting behavior has motivated the power-law parameterizations used in most analyses of the Ly-alpha forest. This relation has been explained by using equations linearized in the baryonic overdensity (which does not address why a tight power-law relation holds over two decades in density) or by equating the photoheating rate with the cooling rate from cosmological expansion (which we show is incorrect). Previous explanations also did not address why recombination cooling and Compton cooling off of the cosmic microwave background, which are never negligible, do not alter the character of this relation. We provide an understanding for why a tight power-law relation arises for unshocked gas at all densities for which collisional c...

  5. A High Temperature Liquid Plasma Model of the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2007-01-01

    Full Text Available In this work, a liquid model of the Sun is presented wherein the entire solar mass is viewed as a high density/high energy plasma. This model challenges our current understanding of the densities associated with the internal layers of the Sun, advocating a relatively constant density, almost independent of radial position. The incompressible nature of liquids is advanced to prevent solar collapse from gravitational forces. The liquid plasma model of the Sun is a non-equilibrium approach, where nuclear reactions occur throughout the solar mass. The primary means of addressing internal heat transfer are convection and conduction. As a result of the convective processes on the solar surface, the liquid model brings into question the established temperature of the solar photosphere by highlighting a violation of Kirchhoff’s law of thermal emission. Along these lines, the model also emphasizes that radiative emission is a surface phenomenon. Evidence that the Sun is a high density/high energy plasma is based on our knowledge of Planckian thermal emission and condensed matter, including the existence of pressure ionization and liquid metallic hydrogen at high temperatures and pressures. Prior to introducing the liquid plasma model, the historic and scientific justifications for the gaseous model of the Sun are reviewed and the gaseous equations of state are also discussed.

  6. Temperature and Density Measurements in a Quiet Coronal Streamer

    Science.gov (United States)

    Warren, Harry P.; Warshall, Andrew D.

    2002-06-01

    Many previous studies have used emission line or broadband filter ratios to infer the presence of temperature gradients in the quiet solar corona. Recently it has been suggested that these temperature gradients are not real, but result from the superposition of isothermal loops with different temperatures and density scale heights along the line of sight. A model describing this hydrostatic weighting bias has been developed by Aschwanden & Acton. In this paper we present the application of the Aschwanden & Acton differential emission measure model to Solar and Heliospheric Observatory Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a quiet coronal streamer. Simultaneous Yohkoh soft X-ray telescope (SXT) observations show increases in the filter ratios with height above the limb, indicating an increase in temperature. The application of the Aschwanden & Acton model to these SUMER data, however, show that the temperature is constant with height and that the distribution of temperatures in the corona is much too narrow for the hydrostatic weighting bias to have any effect on the SXT filter ratios. We consider the possibility that there is a tenuous hot component (~3 MK) that accounts for the SXT observations. We find that a hot plasma with an emission measure sufficient to reproduce the observed SXT fluxes would also produce significant count rates in the high-temperature emission lines in the SUMER wavelength range. These lines are not observed, and we conclude that the SUMER spectra are not consistent with the SXT filter ratio temperatures. Calculations from a hydrodynamic loop model suggest that nonuniform footpoint heating may be consistent with the temperatures and densities observed at most heights, consistent with the recent analysis of relatively cool (~1 MK) active region loops. We also find, however, that at the lowest heights the observed densities are smaller than those predicted by uniform or footpoint heating.

  7. Profiling compact toroid plasma density on CTIX with laser deflection

    Science.gov (United States)

    Brockington, Samuel Joseph Erwin

    A laser deflectometer measures line-integrated plasma density gradient using laser diodes and amplified point detectors. A laser passing through an optically thin plasma is refracted by an amount proportional to the line-integrated electron density gradient. I have designed, installed, and operated a deflection diagnostic for the Compact Toroid Injection Experiment (CTIX), a plasma rail gun which can create compact toroid (CT) plasmas of controllable density and velocity. The diagnostic design and motivation are discussed, as well as three experiments performed with deflectometry. Thus, my thesis consists of the design of the deflectometer diagnostic, a comparison of its accuracy to interferometer density measurements, and finally a survey of compact toroid density profiles in two dimensions conducted with an array of detectors.

  8. Carrier Density and Plasma Frequency of Aluminum Nanofilms

    Institute of Scientific and Technical Information of China (English)

    Hao DU; Jun GONG; Chao SUN; Rongfang HUANG; Lishi WEN; W.Y.Cheung; S.P.Wong

    2003-01-01

    In this work, the prerequisite and mode of electromagnetic response of Al nanofilms to electromagnetic wave field was suggested.Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance,which provided plasma frequency-film thickness relation as well. Similarity of both plasma frequency-film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.

  9. Computational Simulation of High Energy Density Plasmas

    Science.gov (United States)

    2009-10-30

    the imploding liner. The PFS depends on a lithium barrier foil slowing the advance of deuterium up the coaxial gun to the corner. There the plasma ...the coaxial gun section, and Figure 4 shows the physical state of the plasma just prior to pinch. Figure 5 shows neutron yield reaching 1014 in this...details the channel geometry between the center cylinder and coaxial gas gun . The deuterium injection starts when the pressure of the deuterium gas in

  10. Anode Spot Formation in Low Pressure and Temperature He Plasma

    Science.gov (United States)

    Scheiner, Brett; Barnat, Edward; Hopkins, Matthew; Baalrud, Scott; Yee, Benjamin

    2016-10-01

    When a small electrode is biased sufficiently above the plasma potential in a low temperature plasma, the electron impact ionization of neutral species near the electrode becomes significant. At neutral gas pressures of 1-100mTorr, it has been previously observed that if this ionization rate is sufficiently high, a double layer may form near the electrode. In some cases the double layer will move outward, separating a high potential plasma attached to the electrode surface from the bulk plasma. This phenomenon is known as an anode spot. A model has been developed describing the formation of anode spots based on observations from 2D particle-in-cell simulations. In this model ionization leads to the buildup of an ion rich region adjacent to the electrode, which modifies the potential structure in a way that traps electrons near the electrode surface. This leads to the formation of a quasineutral plasma near the electrode surface. When the density of this plasma is large enough, the double layer expands due to a pressure imbalance. Observations from PIC simulations were found to be consistent with time resolved measurements of the electron density from laser collision induced fluorescence, and with plasma emission measurements. This research was supported by the Office of Fusion Energy Science at the U.S. Department of Energy under contract DE-AC04-94SL85000 and by the Office of Science Graduate Student Research (SCGSR) program under Contract Number DE-AC05-06OR23100.

  11. Plasma dynamics near critical density inferred from direct measurements of laser hole boring.

    Science.gov (United States)

    Gong, Chao; Tochitsky, Sergei Ya; Fiuza, Frederico; Pigeon, Jeremy J; Joshi, Chan

    2016-06-01

    We have used multiframe picosecond optical interferometry to make direct measurements of the hole boring velocity, v_{HB}, of the density cavity pushed forward by a train of CO_{2} laser pulses in a near critical density helium plasma. As the pulse train intensity rises, the increasing radiation pressure of each pulse pushes the density cavity forward and the plasma electrons are strongly heated. After the peak laser intensity, the plasma pressure exerted by the heated electrons strongly impedes the hole boring process and the v_{HB} falls rapidly as the laser pulse intensity falls at the back of the laser pulse train. A heuristic theory is presented that allows the estimation of the plasma electron temperature from the measurements of the hole boring velocity. The measured values of v_{HB}, and the estimated values of the heated electron temperature as a function of laser intensity are in reasonable agreement with those obtained from two-dimensional numerical simulations.

  12. 氩气低温等离子体处理HDPE薄膜表面的性能研究%Study on Surface Modification of High Density Polyethylene ( HDPE ) Film by Low Temperature Plasma Treatment of Argon

    Institute of Scientific and Technical Information of China (English)

    王建龙; 王正祥; 解林坤; 顾丽争

    2012-01-01

    The surface of high density polyethylene was modified using low temperature Ar plasma technology under the condition of vacuum pressure of 20 Pa and treatment power of 30 W. The results have been analyzed and characterized with water contact angle measurement, scanned electron microscopy(SEM), atomic force microscopy(AFM), XPS, etc. The results show that the weight loss rate of per unit area has reached maximum value at discharge time of 90 seconds during the treatment time of 0 -300 s; the water contact angle sharply decreased in the 0 - 160 s treatment time and their values did not cause significant changes during the 160 -300 s treatment time; the water contact angle gradually increased with the longer standing time; the surface of HDPE could form some polar species such as carbonyl, hydroxyl and carboxyl groups and the binding energy of the surface changed after treatment by low temperature Ar plasma.%利用低温等离子体,以氩气为工作气体,在工作压强为20Pa、处理功率为30w的条件下对HDPE薄膜进行了表面改性。用接触角、SEM、AFM、XPS等手段对改性结果进行了分析和表征。研究结果表明:在0~300s的处理时间内,失重率在处理时间为90s左右时达最大值;接触角在0~160s内随处理时间的增加显著减小,而在160~300s的处理时间内没有发生明显变化;改性后的接触角随着放置时间的推移出现微弱回复;HDPE薄膜经过氩气低温等离子体处理后,能在其表面形成各种极性基团,主要是羰基、羟基和羧基,且薄膜经处理后,其表面的结合能及平面光洁度发生了改变。

  13. Heat Transport Simulation for Atmospheric-Pressure High-Density Microgap Plasma

    Science.gov (United States)

    Kono, Akihiro; Shibata, Tomoyuki; Aramaki, Mitsutoshi

    2006-02-01

    Atmospheric-pressure cw high-density plasma can be produced in a microgap between two knife-edge electrodes by microwave excitation. A possible application of such a plasma is as an excimer light source and for this purpose the gas temperature in the plasma is a particularly important parameter. In this paper we report a fluid dynamic simulation of heat transport in the microgap plasma and compare the results with previously studied experimental gas temperature characteristics (e.g., dependence on the microwave power and the forced gas flow rate). The simulation explains reasonably well the experimental results when the effect of local gas density change on the gas heating process is taken into consideration. Discussion is given that the existence of thermally driven convection in the microgap plasma indicated in a preliminary report is incorrect.

  14. Proton Stopping Power of Different Density Profile Plasmas

    CERN Document Server

    Casas, David; Andreev, Alexander A; Schnürer, Matthias; Morales, Roberto

    2014-01-01

    In this work, the stopping power of a partially ionized plasma is analyzed by means of free electron stopping and bound electron stopping. For the first one, the RPA dielectric function is used, and for the latter one, an interpolation of high and low projectile velocity formulas is used. The dynamical energy loss of an ion beam inside a plasma is estimated by using an iterative scheme of calculation. The Abel inversion is also applied when we have a plasma with radial symmetry. Finally, we compare our methods with two kind of plasmas. In the first one, we estimate the energy loss in a plasma created by a laser prepulse, whose density is approximated by a piecewise function. For the latter one, a radial electron density is supposed and the stopping is obtained as function of radius from the calculated lateral points. In both cases, the dependence with the density profile is observed.

  15. PROTON STOPPING POWER OF DIFFERENT DENSITY PROFILE PLASMAS

    Directory of Open Access Journals (Sweden)

    David Casas

    2015-04-01

    Full Text Available In this work, the stopping power of a partially ionized plasma is analyzed by means of free electron stopping and bound electron stopping. For the first instance, the RPA dielectric function is used, and for the latter one, an interpolation of high and low projectile velocity formulas is used. The dynamical energy loss of a ion beam inside a plasma is estimated by using an iterative scheme of calculation. The Abel inversion is also applied when we have a plasma with radial symmetry. Finally, we compare our methods with two kind of plasmas. In the first one, we estimate the energy loss in a plasma created by a laser prepulse, whose density is approximated by a piecewise function. For the latter one, a radial electron density is supposed and the stopping is obtained as a function of radius from the calculated lateral points. In both cases, the dependence with the density profile is observed.

  16. Role of surface temperature in fluorocarbon plasma-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Caleb T.; Overzet, Lawrence J.; Goeckner, Matthew J. [Department of Electrical Engineering, University of Texas at Dallas, PO Box 830688, Richardson, TX 75083 (United States)

    2012-07-15

    This article examines plasma-surface reaction channels and the effect of surface temperature on the magnitude of those channels. Neutral species CF{sub 4}, C{sub 2}F{sub 6}, and C{sub 3}F{sub 8} are produced on surfaces. The magnitude of the production channel increases with surface temperature for all species, but favors higher mass species as the temperature is elevated. Additionally, the production rate of CF{sub 2} increases by a factor of 5 as the surface temperature is raised from 25 Degree-Sign C to 200 Degree-Sign C. Fluorine density, on the other hand, does not change as a function of either surface temperature or position outside of the plasma glow. This indicates that fluorine addition in the gas-phase is not a dominant reaction. Heating reactors can result in higher densities of depositing radical species, resulting in increased deposition rates on cooled substrates. Finally, the sticking probability of the depositing free radical species does not change as a function of surface temperature. Instead, the surface temperature acts together with an etchant species (possibly fluorine) to elevate desorption rates on that surface at temperatures lower than those required for unassisted thermal desorption.

  17. Quantum Phenomena in High Energy Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Murnane, Margaret [Univ. of Colorado, Boulder, CO (United States); Kapteyn, Henry [Univ. of Colorado, Boulder, CO (United States)

    2017-05-10

    The possibility of implementing efficient (phase matched) HHG upconversion of deep- UV lasers in multiply-ionized plasmas, with potentially unprecedented conversion efficiency is a fascinating prospect. HHG results from the extreme nonlinear response of matter to intense laser light:high harmonics are radiated as a result of a quantum coherent electron recollision process that occurs during laser field ionization of an atom. Under current support from this grant in work published in Science in 2015, we discovered a new regime of bright HHG in highly-ionized plasmas driven by intense UV lasers, that generates bright harmonics to photon energies >280eV

  18. Influence of microwave driver coupling design on plasma density at Testbench for Ion sources Plasma Studies, a 2.45 GHz Electron Cyclotron Resonance Plasma Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Megía-Macías, A.; Vizcaíno-de-Julián, A. [E.S.S. Bilbao, Edificio Cosimet, Landabarri 2, 48940-Leioa, Vizcaya (Spain); Cortázar, O. D., E-mail: dcortazar@essbilbao.org [E.S.S. Bilbao, Edificio Cosimet, Landabarri 2, 48940-Leioa, Vizcaya (Spain); Universidad de Castilla-La Mancha, ETSII, C.J. Cela s/n, 13170 Ciudad Real (Spain)

    2014-03-15

    A comparative study of two microwave driver systems (preliminary and optimized) for a 2.45 GHz hydrogen Electron Cyclotron Resonance plasma generator has been conducted. The influence on plasma behavior and parameters of stationary electric field distribution in vacuum, i.e., just before breakdown, along all the microwave excitation system is analyzed. 3D simulations of resonant stationary electric field distributions, 2D simulations of external magnetic field mapping, experimental measurements of incoming and reflected power, and electron temperature and density along the plasma chamber axis have been carried out. By using these tools, an optimized set of plasma chamber and microwave coupler has been designed paying special attention to the optimization of stationary electric field value in the center of the plasma chamber. This system shows a strong stability on plasma behavior allowing a wider range of operational parameters and even sustaining low density plasma formation without external magnetic field. In addition, the optimized system shows the capability to produce values of plasma density four times higher than the preliminary as a consequence of a deeper penetration of the magnetic resonance surface in relative high electric field zone by keeping plasma stability. The increment of the amount of resonance surface embedded in the plasma under high electric field is suggested as a key factor.

  19. Plasma actuator electron density measurement using microwave perturbation method

    Energy Technology Data Exchange (ETDEWEB)

    Mirhosseini, Farid; Colpitts, Bruce [Electrical and Computer Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3 (Canada)

    2014-07-21

    A cylindrical dielectric barrier discharge plasma under five different pressures is generated in an evacuated glass tube. This plasma volume is located at the center of a rectangular copper waveguide cavity, where the electric field is maximum for the first mode and the magnetic field is very close to zero. The microwave perturbation method is used to measure electron density and plasma frequency for these five pressures. Simulations by a commercial microwave simulator are comparable to the experimental results.

  20. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Phillips, Mark C.

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filamentation channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also partly explains the reason for the occurrence of atomic plume during fs LIBS in air compared to long-pulse ns LIBS.

  1. Charge density fluctuation of low frequency in a dusty plasma

    Institute of Scientific and Technical Information of China (English)

    李芳; 吕保维; O.Havnes

    1997-01-01

    The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ωc, which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma of P<<1, when the charging frequency Ωc is much smaller than the dusty plasma frequency wd, there is a strong charge density fluctuation which is of character of dust acoustic eigen wave. For a dusty plasma of P>>1, when the frequency Ωc, is much larger than wd there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.

  2. Physical properties of dense, low-temperature plasmas

    Science.gov (United States)

    Redmer, Ronald

    1997-04-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied within linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). This linear response method is applied to partially ionized systems such as dense, low-temperature plasmas. Here, the conductivity changes from nonmetallic values up to those typical for

  3. Practicality of magnetic compression for plasma density control

    CERN Document Server

    Gueroult, Renaud

    2016-01-01

    Plasma densification through magnetic compression has been suggested for time-resolved control of the wave properties in plasma-based accelerators. Using particle in cell simulations with real mass ratio, the practicality of large magnetic compression on timescales shorter than the ion gyro-period is investigated. For compression times shorter than the transit time of a compressional Alfven wave across the plasma slab, results show the formation of two counter-propagating shock waves, leading to a highly non-uniform plasma density profile. Furthermore, the plasma slab displays large hydromagnetic like oscillations after the driving field has reached steady state. Peak compression is obtained when the two shocks collide in the mid-plane. At this instant, very large plasma heating is observed, and plasma $\\beta$ is estimated to be about $1$. Although these results point out a densification mechanism quite different and more complex than initially envisioned, these features could possibly be advantageous in part...

  4. Time resolved measurements of the CF{sub 2} rotational temperature in pulsed fluorocarbon rf plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, O; Stepanov, S; Pfafferott, M; Meichsner, J [Institute of Physics, University of Greifswald, Domstrasse 10a, D-17498, Greifswald (Germany)

    2006-11-01

    Knowledge of the absolute densities of small radicals like CF, CF{sub 2} and CF{sub 3} in fluorocarbon plasmas is essential for a fundamental understanding of plasma chemical processes and plasma surface interaction. Infrared absorption spectroscopy by means of tunable diode lasers (IR-TDLAS) was established and widely used for density measurements in the last decade. The often unknown parameter in the calculation of absolute radical densities from a measured absorption of a single line is the rotational temperature. In particular, a strong dependence of the line strength on rotational temperature has a significant influence on density calculation. In this paper we report on measurements of the CF{sub 2} rotational temperature in capacitively coupled CF{sub 4}/H{sub 2} plasmas (CCP) with rf (13.56 MHz) powers up to 200 W. Rotational temperatures in continuous and pulsed modes of the discharge were found to be between 300 and 450 K. Furthermore, first measurements of the time dependence of the rotational temperature in pulsed rf plasma are presented. The rotational temperature rises in the plasma phase within 0.1 s and goes down again to the temperature of the background gas in the plasma pause within 0.5 s. It is also shown that accurate density measurements of the radicals by means of single line absorption need correct information about the rotational temperature and careful selection of a suitable absorption line.

  5. Improving the uniformity of RF-plasma density by a humped variable-gap spiral antenna

    Institute of Scientific and Technical Information of China (English)

    Xu Xu; Li Lin-Sen; Liu Feng; Zhou Qian-Hong; Liang Rong-Qing

    2008-01-01

    This paper develops a humped spiral antenna of top inductively coupled plasma with variable gap.Comparing with planar spiral antennas,it investigates the performance of humped spiral antennae in the calculated electromagnetic configurations and experimental results.It finds that the humped antenna has the improved uniformity of plasma density in the radial direction and the decreased electron temperature in the top inductively coupled plasma.By experimental and theoretical analyses,the plasma performance in the case of humped antennae is considered to be the combined results of the uniform electromagnetic configurations and the depressed capacitively coupling effect.

  6. High density plasma production in a multicusp plasma generator with RF antenna

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yasuo; Hanada, Masaya; Okumura, Yoshikazu; Tanaka, Masanobu [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1992-10-01

    A high density plasma was produced by radio-frequency in a multicusp plasma generator. The generator is a cylindrical chamber of 200 mm in inner diameter and 270 mm in length with 1-3 turn copper tube antenna. By injecting a 2 MHz, 20 kW RF into the multicusp plasma generator, hydrogen plasma of an ion saturation current density of 120 mA/cm{sup 2} and a hydrogen plasma of a density of 6.0 x 10{sup 11} cm{sup -3} was produced at a pressure of 0.6 Pa in the generator. The ion saturation current density was uniform over the central area of 100 mm in diameter. Coating the antenna with an insulator, we proved that the efficiency of the plasma production was improved. (author).

  7. High density plasma production in a multicusp plasma generator with RF antenna

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yasuo; Hanada, Masaya; Okumura, Yoshikazu; Tanaka, Masanobu (Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment)

    1992-10-01

    A high density plasma was produced by radio-frequency in a multicusp plasma generator. The generator is a cylindrical chamber of 200 mm in inner diameter and 270 mm in length with 1-3 turn copper tube antenna. By injecting a 2 MHz, 20 kW RF into the multicusp plasma generator, hydrogen plasma of an ion saturation current density of 120 mA/cm[sup 2] and a hydrogen plasma of a density of 6.0 x 10[sup 11] cm[sup -3] was produced at a pressure of 0.6 Pa in the generator. The ion saturation current density was uniform over the central area of 100 mm in diameter. Coating the antenna with an insulator, we proved that the efficiency of the plasma production was improved. (author).

  8. A unified model of density limit in fusion plasmas

    Science.gov (United States)

    Zanca, P.; Sattin, F.; Escande, D. F.; Pucella, G.; Tudisco, O.

    2017-05-01

    In this work we identify by analytical and numerical means the conditions for the existence of a magnetic and thermal equilibrium of a cylindrical plasma, in the presence of Ohmic and/or additional power sources, heat conduction and radiation losses by light impurities. The boundary defining the solutions’ space having realistic temperature profile with small edge value takes mathematically the form of a density limit (DL). Compared to previous similar analyses the present work benefits from dealing with a more accurate set of equations. This refinement is elementary, but decisive, since it discloses a tenuous dependence of the DL on the thermal transport for configurations with an applied electric field. Thanks to this property, the DL scaling law is recovered almost identical for two largely different devices such as the ohmic tokamak and the reversed field pinch. In particular, they have in common a Greenwald scaling, linearly depending on the plasma current, quantitatively consistent with experimental results. In the tokamak case the DL dependence on any additional heating approximately follows a 0.5 power law, which is compatible with L-mode experiments. For a purely externally heated configuration, taken as a cylindrical approximation of the stellarator, the DL dependence on transport is found stronger. By adopting suitable transport models, DL takes on a Sudo-like form, in fair agreement with LHD experiments. Overall, the model provides a good zeroth-order quantitative description of the DL, applicable to widely different configurations.

  9. Simulation of density measurements in plasma wakefields using photo acceleration

    CERN Document Server

    Kasim, Muhammad Firmansyah; Ceurvorst, Luke; Sadler, James; Burrows, Philip N; Trines, Raoul; Holloway, James; Wing, Matthew; Bingham, Robert; Norreys, Peter

    2015-01-01

    One obstacle in plasma accelerator development is the limitation of techniques to diagnose and measure plasma wakefield parameters. In this paper, we present a novel concept for the density measurement of a plasma wakefield using photon acceleration, supported by extensive particle in cell simulations of a laser pulse that copropagates with a wakefield. The technique can provide the perturbed electron density profile in the laser’s reference frame, averaged over the propagation length, to be accurate within 10%. We discuss the limitations that affect the measurement: small frequency changes, photon trapping, laser displacement, stimulated Raman scattering, and laser beam divergence. By considering these processes, one can determine the optimal parameters of the laser pulse and its propagation length. This new technique allows a characterization of the density perturbation within a plasma wakefield accelerator.

  10. A microwave interferometer for small and tenuous plasma density measurements.

    Science.gov (United States)

    Tudisco, O; Lucca Fabris, A; Falcetta, C; Accatino, L; De Angelis, R; Manente, M; Ferri, F; Florean, M; Neri, C; Mazzotta, C; Pavarin, D; Pollastrone, F; Rocchi, G; Selmo, A; Tasinato, L; Trezzolani, F; Tuccillo, A A

    2013-03-01

    The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10(16) m(-3) and 10(19) m(-3)) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small (λ = 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02° has been used, corresponding to a density of 0.5 × 10(16) m(-3).

  11. A microwave interferometer for small and tenuous plasma density measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tudisco, O.; Falcetta, C.; De Angelis, R.; Florean, M.; Neri, C.; Mazzotta, C.; Pollastrone, F.; Rocchi, G.; Tuccillo, A. A. [ENEA CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Lucca Fabris, A.; Manente, M.; Ferri, F.; Tasinato, L.; Trezzolani, F. [CISAS ' G.Colombo,' Universita degli studi di Padova, Via Venezia 15, 35131 Padova (Italy); Accatino, L. [ACC Antenna and MW tech, Via Trieste 16/B, 10098 Rivoli (Italy); Pavarin, D. [Dip. di Ingegneria Industriale (DII), Universita degli Studi di Padova, Via Venezia 1, 35131 Padova (Italy); Selmo, A. [RESIA, Studio Progettazione e Realizzazione di Apparati Elettronici, via Roma 17, 37041 Albaredo d' Adige (Italy)

    2013-03-15

    The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10{sup 16} m{sup -3} and 10{sup 19} m{sup -3}) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small ({lambda}= 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02 Degree-Sign has been used, corresponding to a density of 0.5 Multiplication-Sign 10{sup 16} m{sup -3}.

  12. Development of density measurement method of negative ion in plasmas using laser Thomson scattering

    Science.gov (United States)

    Yamagata, Yukihiko; Saiho, Hiroatsu; Uchino, Kiichiro; Muraoka, Katsunori

    2004-09-01

    Measurements of negative ion density in plasmas have been an important subject for many years. We have proposed a new method to measure the negative ion density in plasmas using laser Thomson scattering (LTS), and successfully measured O^- ion density in an radio frequency inductively coupled plasma [1]. In order to ensure the reliability of this technique and to estimate the accuracy, we have measured O^- ion density in the same experimental conditions using the second (SHG) and third harmonics (THG) of a Nd:YAG laser as different laser sources. The LTS spectra measured at pure argon plasma (500 W, 20 mTorr) fitted in a straight line well in both SHG and THG cases. As for the plasma at 500 W in 20 mTorr with Ar/O_2=95%/5%, a clear bump in LTS spectra, which is caused by photo-detached electrons, was observed below 0.9 eV for the SHG case and 2 eV for the case, as predicted by a difference between the electron affinity of O^- ion and the laser photon energy. The electron temperatures, the electron densities and the O^- ion densities, which were obtained from the spectral shape and intensity of both LTS spectra, were in agreement each other within an experimental error. [1] M. Noguchi, K. Ariga, T. Hirao, P. Suanpoot, Y. Yamagata, K. Uchino, K. Muraoka, Plasma Sources Sci. Technol., 11 (2002) 57.

  13. A study of increasing radical density and etch rate using remote plasma generator system

    Science.gov (United States)

    Lee, Jaewon; Kim, Kyunghyun; Cho, Sung-Won; Chung, Chin-Wook

    2013-09-01

    To improve radical density without changing electron temperature, remote plasma generator (RPG) is applied. Multistep dissociation of the polyatomic molecule was performed using RPG system. RPG is installed to inductively coupled type processing reactor; electrons, positive ions, radicals and polyatomic molecule generated in RPG and they diffused to processing reactor. The processing reactor dissociates the polyatomic molecules with inductively coupled power. The polyatomic molecules are dissociated by the processing reactor that is operated by inductively coupled power. Therefore, the multistep dissociation system generates more radicals than single-step system. The RPG was composed with two cylinder type inductively coupled plasma (ICP) using 400 kHz RF power and nitrogen gas. The processing reactor composed with two turn antenna with 13.56 MHz RF power. Plasma density, electron temperature and radical density were measured with electrical probe and optical methods.

  14. Evolution of the SOL plasma background at density shoulder formation

    Energy Technology Data Exchange (ETDEWEB)

    D' Isa, Federico Antonio; Carralero, Daniel; Lunt, Tilmann; Collaboration: ASDEX Upgrade Team

    2016-12-15

    observed that filaments, namely coherent structures that enhance the transport in the outer region of Tokamaks, undergo a regime transition that enhances their transport at the outboard midplane. It is believed that inhomogeneous perpendicular transport related to the filaments is responsible for the density shoulder formation. The regime transition occurs because of the increase of the global collisionality. Since the plasma parameters (n{sub e},T{sub e}) change significantly along a field line it is needed a full description of the plasma in the SOL in order to study where such increase of the collisionaly takes place. The first part of this work is focused on use EMC3-EIRENE simulations, in continuation of previous work, to provide a detailed 3D plasma background of the SOL condition in two different L-mode discharges carried out in the ASDEX Upgrade Tokamak, featuring different different degrees of shoulder formation: case A (simulation of discharge 29231) in which no shoulder is observed and case B (simulation of discharge 29887) after the transition. In the simulation, cross field transport is described by the perpendicular particle and energy diffusive time independent transport coefficients: D {sub perpendicular} {sub to}, χ {sup e,i} {sub perpendicular} {sub to}. The simulations are compared with the experimental measurements at the midplane, the X-point and the divertor targets. The comparison shows that previous simulations of case B strongly underestimate the electron and ion temperatures. In order to improve the simulation results and provide a realistic description of the SOL plasma background several simulations are performed. As a result, the final agreement between experimental measurement and numerical results has been improved with respect to the original work. The simulations show that: - It is possible to simulate the density shoulder formation by increasing transport a factor of 3 only at the outer midplane, in good agreement with the experimental

  15. The LC resonance probe for determining local plasma density

    Energy Technology Data Exchange (ETDEWEB)

    Boris, D R; Fernsler, R F; Walton, S G, E-mail: david.boris.ctr@nrl.navy.mi [Naval Research Laboratory, Charge Particle Physics Branch-Code 6752, Plasma Physics Division, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)

    2011-04-15

    We present a novel plasma diagnostic for measuring local plasma density in reactive-gas plasmas, and depositing plasmas. The diagnostic uses a network analyzer to measure the LC resonance (LCR) frequency of a parallel plate capacitor with inductive leads. The location of the LCR ({omega}{sub R}) in frequency space is then used as a measure of the plasma dielectric constant bold varepsilon{sub p} between the plates. By properly constructing the LCR probe, {omega}{sub R} can be tuned such that {omega}{sub R} >> {omega}{sub ce}, where {omega}{sub ce} is the electron-cyclotron frequency. Thus, the probe can be used in plasmas with varying degrees of magnetization while avoiding complications introduced to bold varepsilon{sub p} when {omega} is comparable to {omega}{sub ce}. Density measurements from the LCR probe are compared with Langmuir probe measurements in an electron-beam generated plasma in which density varied from 10{sup 9} to 10{sup 11} cm{sup -3}. An axial magnetic field, typically used to confine the electron beam, was varied between 0 to 300 G. The LCR probe showed good agreement with a Langmuir probe across the entire range of magnetic fields.

  16. Laser Plasma Coupling for High Temperature Hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  17. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B. [Particle Beam Physics Laboratory, UCLA, Los Angeles, CA 90095 (United States); Bruhwiler, David L. [RadiaSoft LLC, Boulder, CO 80304 (United States); RadiaBeam Technologies LLC (United States); Smith, Jonathan [Tech-X UK Ltd, Daresbury, Cheshire WA4 4FS (United Kingdom); Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G. [Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Hidding, Bernhard [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical “plasma torch” distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  18. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    Science.gov (United States)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B.; Bruhwiler, David L.; Smith, Jonathan; Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G.; Hidding, Bernhard

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical "plasma torch" distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  19. High-density operation of the Proto-MPEX High Intensity Plasma Source

    Science.gov (United States)

    Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Campbell, I. H.; Caneses, J.; Diem, S. J.; Martin, E. H.; Parish, C. M.; Rapp, J.; Ray, H. B.; Shaw, G. C.; Showers, M. A.; Donovan, D.; Piotrowicz, P. A.; Martin, D. C.

    2016-10-01

    The Prototype Materials Plasma Experiment (Proto-MPEX) is a linear high-intensity RF plasma source that combines a high-density helicon plasma generator with ion and electron heating sections. It is being used to study the physics of heating over-dense plasmas in a linear configuration with the goal of delivering a plasma heat flux of 10 MW/m2 at a target. The helicon plasma is produced by coupling 13.56 MHz RF power at levels of >100 kW. A 30 kW ion cyclotron antenna has recently been installed, and microwaves at 28 GHz ( 150 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW). High plasma densities near the target have been produced in D ( 5 x1019/m3) , and electron temperatures range from 3 to >10 eV, depending on the source parameters. IR camera images of the target plate indicate plasma heat depositions >10 MW/m2 for some operating conditions. Details of the experimental results of the operational domain with respect to Te and ne as well as results from initial plasma material interaction tests will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  20. Second Topical Conference on High-Temperature Plasma Diagnostics

    Science.gov (United States)

    1978-02-01

    1 and is employed to make routine measurements of the evolution of plasma density in the high density ( n > 5 x 1011* cm-3) Alcator A tokamak...plasmas. To exemplify the use of these techniques in fusion plasmas, studies of density fluc- tuations in the ATC and ALCATOR tokamaks will be...character- istics for the excessive incidence of plasma light. Video signals are recorded with a video tape recorder, which starts and stops recording

  1. Radio Scintillation due to Discontinuities in the Interstellar Plasma Density

    CERN Document Server

    Lambert, H; Lambert, Hendrik; Rickett, Barney

    1999-01-01

    We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral exponent of 4 corresponding to a medium with abrupt changes in its density. An ``outer scale'' is included in the model representing the typical scale over which the density of the medium remains uniform. Such a spectrum could be used to model plasma shock fronts in supernova remnants or other plasma discontinuities. We investigate and develop equations for the decorrelation bandwidth of diffractive scintillations and the refractive scintillation index and compare our results with pulsar measurements. We consider both a medium concentrated in a thin layer and an extended irregular medium. We conclude that the discontinuity model gives satisfactory agreement for many diffractive measurements, in particular the VLBI meaurements of the structure function exponent between 5/3 and 2. However, it gives less satisfactory agreement for the refractive scintillation index than...

  2. High temperature UF6 RF plasma experiments applicable to uranium plasma core reactors

    Science.gov (United States)

    Roman, W. C.

    1979-01-01

    An investigation was conducted using a 1.2 MW RF induction heater facility to aid in developing the technology necessary for designing a self critical fissioning uranium plasma core reactor. Pure, high temperature uranium hexafluoride (UF6) was injected into an argon fluid mechanically confined, steady state, RF heated plasma while employing different exhaust systems and diagnostic techniques to simulate and investigate some potential characteristics of uranium plasma core nuclear reactors. The development of techniques and equipment for fluid mechanical confinement of RF heated uranium plasmas with a high density of uranium vapor within the plasma, while simultaneously minimizing deposition of uranium and uranium compounds on the test chamber peripheral wall, endwall surfaces, and primary exhaust ducts, is discussed. The material tests and handling techniques suitable for use with high temperature, high pressure, gaseous UF6 are described and the development of complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma, effluent exhaust gases, and residue deposited on the test chamber and exhaust system components is reported.

  3. Plasma Shock Wave Modification Experiments in a Temperature Compensated Shock Tube

    Science.gov (United States)

    Vine, Frances J.; Mankowski, John J.; Saeks, Richard E.; Chow, Alan S.

    2003-01-01

    A number of researchers have observed that the intensity of a shock wave is reduced when it passes through a weakly ionized plasma. While there is little doubt that the intensity of a shock is reduced when it propagates through a weakly ionized plasma, the major question associated with the research is whether the reduction in shock wave intensity is due to the plasma or the concomitant heating of the flow by the plasma generator. The goal of this paper is to describe a temperature compensated experiment in a "large" diameter shock tube with an external heating source, used to control the temperature in the shock tube independently of the plasma density.

  4. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    Energy Technology Data Exchange (ETDEWEB)

    Catapano, F., E-mail: menacata3@gmail.com; Zimbardo, G. [Dipartimento di Fisica, Università della Calabria, Rende, Cosenza (Italy); Artemyev, A. V., E-mail: ante0226@gmail.com; Vasko, I. Y. [Space Research Institute, RAS, Moscow (Russian Federation)

    2015-09-15

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed.

  5. Schlieren technique applied to the arc temperature measurement in a high energy density cutting torch

    Science.gov (United States)

    Prevosto, L.; Artana, G.; Mancinelli, B.; Kelly, H.

    2010-01-01

    Plasma temperature and radial density profiles of the plasma species in a high energy density cutting arc have been obtained by using a quantitative schlieren technique. A Z-type two-mirror schlieren system was used in this research. Due to its great sensibility such technique allows measuring plasma composition and temperature from the arc axis to the surrounding medium by processing the gray-level contrast values of digital schlieren images recorded at the observation plane for a given position of a transverse knife located at the exit focal plane of the system. The technique has provided a good visualization of the plasma flow emerging from the nozzle and its interactions with the surrounding medium and the anode. The obtained temperature values are in good agreement with those values previously obtained by the authors on the same torch using Langmuir probes.

  6. Density Distributions of H and H2 in Pulsed Microwave hydrogen Plasmas

    Institute of Scientific and Technical Information of China (English)

    DUAN Xu-Ru(段旭如); H.Lange; QIAN shang-Jie(钱尚介); N.Lang

    2003-01-01

    Temporal distribution of the H atom and Hz densities in a pulsed microwave hydrogen plasmas has been measured simultaneously by two-photon absorption laser-induced fluorescence (TALIF). The measurement of the H-atom absolute density obtained by NO2 titration in a flow tube reactor shows that the density of H2 could be determined by the measured effective lifetime of the TALIF signal via the quenching equation. The H-atom density of about 1.5×1015cm-3 in both pulsed and stationary phases does not obviously change. It is found that the gas temperature volume effect plays an important role in governing the distributions of the H-atom density and it is mole fraction. The calculated gas temperature is in good consistent with the rotational temperature of H2measured by optical emission spectroscopy in pulsed phase.

  7. [Two-temperature diagnostic studies by emission spectra for nonequilibrium Ti-H plasma].

    Science.gov (United States)

    Deng, Chun-feng; Lu, Biao; Wu, Chun-lei; Wang, Yi-fu; Wen, Zhong-wei

    2014-12-01

    Using the T-H solid solution made by titanium absorbed hydrogen as the cathode, the Ti-H plasma produced by the pulsed vacuum are ion source was nonequilibrium: it contained both the component of titanium and hydrogen; there existed gradient in the radiaL, the horizontal and the time. As a result, it could not be described by a single temperature. The present paper assumed that the subsystem consisting of electrons and the subsystem consisting of other heavy particles reached equilibrium respectively, meaning that the Ti-H plasma was described by the two temperatures as electron temperature and heavy ion temperature, it was non-equilibrium two-temperature plasma Using Culdberg-Waage dissociation equation to describe the molecular dissociation process in the system, using Saha ionization equation to describe the atomic ionization process, combining plasma's charge quasi-neutral condition and introducing atomic emission spectroscopy as a plasma diagnostic method which would not interfere the plasma at the same time; the temperature and the particle number density of the Ti-H plasma were diagnosed. Using MATLAB as a tool, both the titanium atoms and monovalent titanium ions' ionization were considered, and the calculated results showed that with the electtron density determined by the Stark broadening of spectral lines in advance, except the heavy particle temperature and the hydrogen number density, the Ti-H plasma's parameters could be diagnosed fairly accurately; the accuracy of the electron density values had a great effect on the calculation results; if the heavy particle temperature could be determined in advance, the temperature and the particle number density of the Ti-H plasma could be accurately analyzed quantitatively.

  8. Understanding the core density profile in TCV H-mode plasmas

    CERN Document Server

    Wágner, Dávid; Pitzschke, Andreas; Sauter, Olivier; Weisen, Henri

    2012-01-01

    Results from a database analysis of H-mode electron density profiles on the Tokamak \\`a Configuration Variable (TCV) in stationary conditions show that the logarithmic electron density gradient increases with collisionality. By contrast, usual observations of H-modes showed that the electron density profiles tend to flatten with increasing collisionality. In this work it is reinforced that the role of collisionality alone, depending on the parameter regime, can be rather weak and in these, dominantly electron heated TCV cases, the electron density gradient is tailored by the underlying turbulence regime, which is mostly determined by the ratio of the electron to ion temperature and that of their gradients. Additionally, mostly in ohmic plasmas, the Ware-pinch can significantly contribute to the density peaking. Qualitative agreement between the predicted density peaking by quasi-linear gyrokinetic simulations and the experimental results is found. Quantitative comparison would necessitate ion temperature meas...

  9. Low temperature plasma biomedicine: A tutorial reviewa)

    Science.gov (United States)

    Graves, David B.

    2014-08-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  10. Low temperature plasma biomedicine: A tutorial review

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David B., E-mail: graves@berkeley.edu [University of California at Berkeley, Berkeley, California 94720 (United States)

    2014-08-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  11. Extended Opacity Tables with Higher Temperature-Density-Frequency Resolution

    Science.gov (United States)

    Schillaci, Mark; Orban, Chris; Delahaye, Franck; Pinsonneault, Marc; Nahar, Sultana; Pradhan, Anil

    2015-05-01

    Theoretical models for plasma opacities underpin our understanding of radiation transport in many different astrophysical objects. These opacity models are also relevant to HEDP experiments such as ignition scale experiments on NIF. We present a significantly expanded set of opacity data from the widely utilized Opacity Project, and make these higher resolution data publicly available through OSU's portal with dropbox.com. This expanded data set is used to assess how accurate the interpolation of opacity data in temperature-density-frequency dimensions must be in order to adequately model the properties of most stellar types. These efforts are the beginning of a larger project to improve the theoretical opacity models in light of experimental results at the Sandia Z-pinch showing that the measured opacity of Iron disagrees strongly with all current models.

  12. Interacting Eigenmodes of a plasma diode with a density gradient

    Energy Technology Data Exchange (ETDEWEB)

    Loefgren, T.; Gunell, H.

    1997-08-01

    The formation of narrow high frequency electric field spikes in plasma density gradients is investigated using one-dimensional particle in cell simulations. It is found that the shape of the plasma density gradient is very important for the spike formation. The spike appears also in simulations with immobile ions showing that a coupling to the ion motion, as for example in wave interactions, is not necessary for the formation of HF spikes. However, the HF spike influences the ion motion, and ion waves are seen in the simulations. It has been found, in experiments and simulations, that the electron velocity distribution function deviates from the Maxwellian distribution. Dispersion relations are calculated using realistic distribution functions. The spike can be seen as a coupled system of two Eigenmodes of a plasma diode fed by the beam-plasma interaction. Based on a simplified fluid description of such Eigenmodes, explanations for the localization of the spike, spatially and in frequency, are given. The density amplitude is comparable with the DC density level close to the cathode. Space charge limits of waves in this region seem to determine the amplitude of the spike through the Poisson`s equation. 12 refs, 19 figs.

  13. Hydrodynamic theory of diffusion in two-temperature multicomponent plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ramshaw, J.D.; Chang, C.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-12-31

    Detailed numerical simulations of multicomponent plasmas require tractable expressions for species diffusion fluxes, which must be consistent with the given plasma current density J{sub q} to preserve local charge neutrality. The common situation in which J{sub q} = 0 is referred to as ambipolar diffusion. The use of formal kinetic theory in this context leads to results of formidable complexity. We derive simple tractable approximations for the diffusion fluxes in two-temperature multicomponent plasmas by means of a generalization of the hydrodynamical approach used by Maxwell, Stefan, Furry, and Williams. The resulting diffusion fluxes obey generalized Stefan-Maxwell equations that contain driving forces corresponding to ordinary, forced, pressure, and thermal diffusion. The ordinary diffusion fluxes are driven by gradients in pressure fractions rather than mole fractions. Simplifications due to the small electron mass are systematically exploited and lead to a general expression for the ambipolar electric field in the limit of infinite electrical conductivity. We present a self-consistent effective binary diffusion approximation for the diffusion fluxes. This approximation is well suited to numerical implementation and is currently in use in our LAVA computer code for simulating multicomponent thermal plasmas. Applications to date include a successful simulation of demixing effects in an argon-helium plasma jet, for which selected computational results are presented. Generalizations of the diffusion theory to finite electrical conductivity and nonzero magnetic field are currently in progress.

  14. Plasma density fluctuations observed during Space Shuttle Orbiter water releases

    Science.gov (United States)

    Pickett, J. S.; D'Angelo, N.; Kurth, W. S.

    1989-01-01

    Observations by the Langmuir probe on the Plasma Diagnostics Package flown as part of the Spacelab 2 mission in the summer of 1985 show a strong increase in the level of turbulence near the Shuttle Orbiter during operations in which liquid water is released. The spectrum of the plasma density fluctuations peaks at the lowest frequencies measured (a few Hz) and extends up to a few kHz, near the lower hybrid frequency. Two potential mechanisms for generating the plasma turbulence are suggested which are both based on the production of water ions as a result of charge exchange with the ambient oxygen ions in the ionosphere. The first mechanism proposed is the ion-plasma instability which arises from the drift of the contaminant with respect to the ambient oxygen ions. The other mechanism proposed is the Ott-Farley instability, which is a result of the ring distribution formed by the 'pick-up' water ions.

  15. Low temperature spark plasma sintering of YIG powders

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Garcia, L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Suarez, M., E-mail: m.suarez@cinn.e [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Fundacion ITMA, Parque Tecnologico de Asturias, 33428, Llanera (Spain); Menendez, J.L. [Department of Nanostructured Materials, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2010-07-16

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 {sup o}C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 {sup o}C leads to dense samples with minimal formation of YFeO{sub 3}, opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  16. Unstable density distribution associated with equatorial plasma bubble

    Science.gov (United States)

    Kherani, E. A.; Bharuthram, R.; Singh, S.; Lakhina, G. S.; de Meneses, F. Carlos

    2016-04-01

    In this work, we present a simulation study of equatorial plasma bubble (EPB) in the evening time ionosphere. The fluid simulation is performed with a high grid resolution, enabling us to probe the steepened updrafting density structures inside EPB. Inside the density depletion that eventually evolves as EPB, both density and updraft are functions of space from which the density as implicit function of updraft velocity or the density distribution function is constructed. In the present study, this distribution function and the corresponding probability distribution function are found to evolve from Maxwellian to non-Maxwellian as the initial small depletion grows to EPB. This non-Maxwellian distribution is of a gentle-bump type, in confirmation with the recently reported distribution within EPB from space-borne measurements that offer favorable condition for small scale kinetic instabilities.

  17. Practicality of magnetic compression for plasma density control

    Science.gov (United States)

    Gueroult, Renaud; Fisch, Nathaniel J.

    2016-03-01

    Plasma densification through magnetic compression has been suggested for time-resolved control of the wave properties in plasma-based accelerators [P. F. Schmit and N. J. Fisch, Phys. Rev. Lett. 109, 255003 (2012)]. Using particle in cell simulations with real mass ratio, the practicality of large magnetic compression on timescales shorter than the ion gyro-period is investigated. For compression times shorter than the transit time of a compressional Alfven wave across the plasma slab, results show the formation of two counter-propagating shock waves, leading to a highly non-uniform plasma density profile. Furthermore, the plasma slab displays large hydromagnetic like oscillations after the driving field has reached steady state. Peak compression is obtained when the two shocks collide in the mid-plane. At this instant, very large plasma heating is observed, and the plasma β is estimated to be about 1. Although these results point out a densification mechanism quite different and more complex than initially envisioned, these features still might be advantageous in particle accelerators.

  18. Estimation of Plasma Density by Surface Plasmons for Surface-Wave Plasmas

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhao-Quan; LIU Ming-Hai; LAN Chao-Hui; CHEN Wei; LUO Zhi-Qing; HU Xi-Wei

    2008-01-01

    @@ An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 1017 m-3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 1017 m-3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.

  19. Electron density and electron temperature measurements in nanosecond pulse discharges over liquid water surface

    Science.gov (United States)

    Simeni Simeni, M.; Roettgen, A.; Petrishchev, V.; Frederickson, K.; Adamovich, I. V.

    2016-12-01

    Time-resolved electron density, electron temperature, and gas temperature in nanosecond pulse discharges in helium and O2-He mixtures near liquid water surface are measured using Thomson/pure rotational Raman scattering, in two different geometries, (a) ‘diffuse filament’ discharge between a spherical high-voltage electrode and a grounded pin electrode placed in a reservoir filled with distilled water, with the tip exposed, and (b) dielectric barrier discharge between the high-voltage electrode and the liquid water surface. A diffuse plasma filament generated between the electrodes in helium during the primary discharge pulse exhibits noticeable constriction during the secondary discharge pulse several hundred ns later. Adding oxygen to the mixture reduces the plasma filament diameter and enhances constriction during the secondary pulse. In the dielectric barrier discharge, diffuse volumetric plasma occupies nearly the entire space between the high voltage electrode and the liquid surface, and extends radially along the surface. In the filament discharge in helium, adding water to the container results in considerable reduction of plasma lifetime compared to the discharge in dry helium, by about an order of magnitude, indicating rapid electron recombination with water cluster ions. Peak electron density during the pulse is also reduced, by about a factor of two, likely due to dissociative attachment to water vapor during the discharge pulse. These trends become more pronounced as oxygen is added to the mixture, which increases net rate of dissociative attachment. Gas temperature during the primary discharge pulse remains near room temperature, after which it increases up to T ~ 500 K over 5 µs and decays back to near room temperature before the next discharge pulse several tens of ms later. As expected, electron density and electron temperature in diffuse DBD plasmas are considerably lower compared to peak values in the filament discharge. Use of Thomson

  20. Influence of temperature fluctuations on plasma turbulence investigations with Langmuir probes

    CERN Document Server

    Nold, B; Ramisch, M; Huang, Z; Müller, H W; Scott, B D; Stroth, U

    2011-01-01

    The reliability of Langmuir probe measurements for plasma-turbulence investigations is studied on GEMR gyro-fluid simulations and compared with results from conditionally sampled I-V characteristics as well as self-emitting probe measurements in the near scrape-off layer of the tokamak ASDEX Upgrade. In this region, simulation and experiment consistently show coherent in-phase fluctuations in density, plasma potential and also in electron temperature. Ion-saturation current measurements turn out to reproduce density fluctuations quite well. Fluctuations in the floating potential, however, are strongly influenced by temperature fluctuations and, hence, are strongly distorted compared to the actual plasma potential. These results suggest that interpreting floating as plasma-potential fluctuations while disregarding temperature effects is not justified near the separatrix of hot fusion plasmas. Here, floating potential measurements lead to corrupted results on the ExB dynamics of turbulent structures in the cont...

  1. Reflectometry techniques for density profile measurements on fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Laviron, C. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Donne, A.J.H. [Associatie Euratom-FOM, Nieuwegein (Netherlands). FOM-Instituut voor Plasmafysica; Manso, M.E. [Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Quimica Organica; Sanchez, J. [EURATOM-CIEMAT for Fusion Association, Madrid (Spain)

    1996-03-01

    Reflectometry applied to the measurement of density profiles on fusion plasmas has been subject to many recent developments. After a brief reminder of the principles of reflectometry, the theoretical accuracy of reflectometry measurements is discussed. The main difficulties limiting the performance, namely the plasma fluctuations and the quality of the transmission lines, are analysed. The different techniques used for reflectometry are then presented. The present status and achievements of actual implementations of these techniques are shown, with an analysis of their respective limitations and merits, as well as foreseen developments. (author). 70 refs.

  2. Dependence of Arc Plasma Dispersion Capability on its Temperature

    Institute of Scientific and Technical Information of China (English)

    CHEN Yun-Yun; SONG Yang; HE An-Zhi; LI Zhen-Hua

    2008-01-01

    @@ The relationship between the dispersion capability and the temperature of argon arc plasma at Iatm is deduced in view of the plasma's refractive index equation.The results indicate that argon arc plasma has a normal dispersion and its dispersion capability is nonlinear to the plasma's temperature in a wide range of temperature and wavelength region.According to the results of numerical calculation, the preferred optical methods are believed to be suitable for the diagnosis of argon arc plasma in different temperature regions.

  3. Surface hardening utilizing high-density plasma nitriding on stainless steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lleonart-Davila, G; Gaudier, J; Rivera, R; Leal, D; Gonzalez-Lizardo, A; Leal-Quiros, E [Plasma Engineering Laboratory, Polytechnic University of Puerto Rico, San Juan, PR 00918 (Puerto Rico)

    2008-10-15

    By using a plasma nitriding procedure at the PUPR Mirror Cusp Plasma machine, surface hardness is increased in 302/304-type stainless steel samples by exposing them to high-ion-density plasma at high vacuum. This method successfully dopes the surface of the material with strengthening nitrogen ions, without the use of chemical procedures that sacrifice the resistance to corrosion of the given material. A 500 V negative bias is placed on the sample exposed to the nitrogen plasma, where high-energy ions are therefore attracted and immersed into the metallic matrix microns into the surface of the stainless steel. This potential maintains a constant surface temperature at approximately 800 deg. C. The plasma parameters including ion density and plasma temperature were diagnosed using single Langmuir probes. The stainless steel samples were then tested using scanning electron microscopy (SEM), and Vickers micro-hardness testing to determine the increment in the surface harness of the material. The SEM showed a significant presence of nitrogen imbedded in the grains of the stainless steel surface.

  4. Temperature and Density Structure of a Recurring Active Region Jet

    CERN Document Server

    Mulay, Sargam M; Mason, Helen

    2016-01-01

    We present a study of a recurring jet observed on October 31, 2011 by SDO/AIA, Hinode/XRT and Hinode/EIS. We discuss the physical parameters of the jet such as density, differential emission measure, peak temperature, velocity and filling factor obtained using imaging and spectroscopic observations. A differential emission measure (DEM) analysis was performed at the region of the jet-spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The plasma along the line-of-sight in the jet-spire and jet-footpoint was found to be peak at 2.0 MK. We calculated electron densities using the Fe XII ($\\lambda$186/$\\lambda$195) line ratio in the region of the spire (Ne = 7.6x$10^{10}$ $cm^{-3}$) and the footpoint (1.1x$10^{11}$ $cm^{-3}$). The plane-of-sky velocity of the jet is found to be 524 km/s. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. There is no in...

  5. DC Thermal Plasma Design and Utilization for the Low Density Polyethylene to Diesel Oil Pyrolysis Reaction

    Directory of Open Access Journals (Sweden)

    Hossam A. Gabbar

    2017-06-01

    Full Text Available The exponential increase of plastic production produces 100 million tonnes of waste plastics annually which could be converted into hydrocarbon fuels in a thermal cracking process called pyrolysis. In this research work, a direct current (DC thermal plasma circuit is designed and used for conversion of low density polyethylene (LDPE into diesel oil in a laboratory scale pyrolysis reactor. The experimental setup uses a 270 W DC thermal plasma at operating temperatures in the range of 625 °C to 860 °C for a low density polyethylene (LDPE pyrolysis reaction at pressure = −0.95, temperature = 550 °C with τ = 30 min at a constant heating rate of 7.8 °C/min. The experimental setup consists of a vacuum pump, closed system vessel, direct current (DC plasma circuit, and a k-type thermocouple placed a few millimeters from the reactant sample. The hydrocarbon products are condensed to diesel oil and analyzed using flame ionization detector (FID gas chromatography. The analysis shows 87.5% diesel oil, 1,4-dichlorobenzene (Surr, benzene, ethylbenzene and traces of toluene and xylene. The direct current (DC thermal plasma achieves 56.9 wt. % of diesel range oil (DRO, 37.8 wt. % gaseous products and minimal tar production. The direct current (DC thermal plasma shows reliability, better temperature control, and high thermal performance as well as the ability to work for long operation periods.

  6. Control of ion density distribution by magnetic traps for plasma electrons

    Energy Technology Data Exchange (ETDEWEB)

    Baranov, Oleg; Romanov, Maxim [Plasma Laboratory, National Aerospace University ' KhAI,' Kharkov 61070 (Ukraine); Fang Jinghua [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, New South Wales 2070 (Australia); School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Cvelbar, Uros [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Ostrikov, Kostya [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, New South Wales 2070 (Australia); University of Sydney, Sydney, NSW 2006 (Australia)

    2012-10-01

    The effect of a magnetic field of two magnetic coils on the ion current density distribution in the setup for low-temperature plasma deposition is investigated. The substrate of 400 mm diameter is placed at a distance of 325 mm from the plasma duct exit, with the two magnetic coils mounted symmetrically under the substrate at a distance of 140 mm relative to the substrate centre. A planar probe is used to measure the ion current density distribution along the plasma flux cross-sections at distances of 150, 230, and 325 mm from the plasma duct exit. It is shown that the magnetic field strongly affects the ion current density distribution. Transparent plastic films are used to investigate qualitatively the ion density distribution profiles and the effect of the magnetic field. A theoretical model is developed to describe the interaction of the ion fluxes with the negative space charge regions associated with the magnetic trapping of the plasma electrons. Theoretical results are compared with the experimental measurements, and a reasonable agreement is demonstrated.

  7. Effects of the current boundary conditions at the plasma-gun gap on density in SSPX

    Science.gov (United States)

    Kolesnikov, Roman; Lodestro, L. L.; Meyer, W. H.

    2012-10-01

    The Sustained Spheromak Physics Experiment (SSPX) was a toroidal magnetic-confinement device without toroidal magnetic-field coils or a central transformer but which generated core-plasma currents by dynamo processes driven by coaxial plasma-gun injection into a flux-conserving vessel. Record electron temperatures in a spheromak (Te˜500eV) were achieved, and final results of the SSPX program were reported in [1]. Plasma density, which depended strongly on wall conditions, was an important parameter in SSPX. It was observed that density rises with Igun and that confinement improved as the density was lowered. Shortly after the last experiments, a new feature was added to the Corsica code's solver used to reconstruct SSPX equilibria. Motivated by n=0 fields observed in NIMROD simulations of SSPX, an insulating boundary condition was implemented at the plasma-gun gap. Using this option we will perform new reconstructions of SSPX equilibria and look for correlations between the location of the separatrix (which moves up the gun wall and onto the insulating gap as Igun increases) and plasma density and magnetic-flux amplification [2].[4pt] [1] H. S. McLean, APS, DPP, Dallas, TX, 2008.[0pt] [2] E. B. Hooper et al., Nucl. Fusion 47, 1064 (2007).

  8. Magnetohydrodynamically stable plasma with supercritical current density at the axis

    Energy Technology Data Exchange (ETDEWEB)

    Burdakov, A. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Avenue, 630092 Novosibirsk (Russian Federation); Postupaev, V. V., E-mail: V.V.Postupaev@inp.nsk.su; Sudnikov, A. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation)

    2014-05-15

    In this work, an analysis of magnetic perturbations in the GOL-3 experiment is given. In GOL-3, plasma is collectively heated in a multiple-mirror trap by a high-power electron beam. During the beam injection, the beam-plasma interaction maintains a high-level microturbulence. This provides an unusual radial profile of the net current (that consists of the beam current, current of the preliminary discharge, and the return current). The plasma core carries supercritical current density with the safety factor well below unity, but as a whole, the plasma is stable with q(a) ≈ 4. The net plasma current is counter-directed to the beam current; helicities of the magnetic field in the core and at the edge are of different signs. This forms a system with a strong magnetic shear that stabilizes the plasma core in good confinement regimes. We have found that the most pronounced magnetic perturbation is the well-known n = 1, m = 1 mode for both stable and disruptive regimes.

  9. Development of plasma bolometers using fiber-optic temperature sensors

    Science.gov (United States)

    Reinke, M. L.; Han, M.; Liu, G.; van Eden, G. G.; Evenblij, R.; Haverdings, M.; Stratton, B. C.

    2016-11-01

    Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry-Pérot cavity when broadband light, λo ˜ 1550 nm, is transmitted along the fiber. Changes in temperature alter the optical path length of the cavity primarily through the thermo-optic effect, resulting in a shift of fringes reflected from the pillar detected using an I-MON 512 OEM spectrometer. While initially designed for use in liquids, this sensor has ideal properties for use as a plasma bolometer: a time constant, in air, of ˜150 ms, strong absorption in the spectral range of plasma emission, immunity to local EMI, and the ability to measure changes in temperature remotely. Its compact design offers unique opportunities for integration into the vacuum environment in places unsuitable for a resistive bolometer. Using a variable focus 5 mW, 405 nm, modulating laser, the signal to noise ratio versus power density of various bolometer technologies are directly compared, estimating the noise equivalent power density (NEPD). Present tests show the fiber-optic bolometer to have NEPD of 5-10 W/m2 when compared to those of the resistive bolometer which can achieve coatings, along with improving the spectral resolution of the interrogator.

  10. ZaP-HD: High Energy Density Z-Pinch Plasmas using Sheared Flow Stabilization

    Science.gov (United States)

    Golingo, R. P.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Hughes, M. C.; Kim, B.; Ross, M. P.; Weed, J. R.

    2015-11-01

    The ZaP-HD flow Z-pinch project investigates scaling the flow Z-pinch to High Energy Density Plasma, HEDP, conditions by using sheared flow stabilization. ZaP used a single power supply to produce 100 cm long Z-pinches that were quiescent for many radial Alfven times and axial flow-through times. The flow Z-pinch concept provides an approach to achieve HED plasmas, which are dimensionally large and persist for extended durations. The ZaP-HD device replaces the single power supply from ZaP with two separate power supplies to independently control the plasma flow and current in the Z-pinch. Equilibrium is determined by diagnostic measurements of the density with interferometry and digital holography, the plasma flow and temperature with passive spectroscopy, the magnetic field with surface magnetic probes, and plasma emission with optical imaging. The diagnostics fully characterize the plasma from its initiation in the coaxial accelerator, through the pinch, and exhaust from the assembly region. The plasma evolution is modeled with high resolution codes: Mach2, WARPX, and NIMROD. Experimental results and scaling analyses are presented. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

  11. Comet plasma densities deduced from refraction of occulted radio sources

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.S. (Commonwealth Department of Science, Ionospheric Prediction Service, Narrabri, New South Wales, Australia); Nelson, G.J. (Commonwealth Scientific and Industrial Research Organization, Div. of Radiophysics, Narrabri, New South Wales, Australia)

    1979-04-01

    Observations of the occultation of radio sources by comet plasma tails are used to derive the electron density and density gradients in the tails. Occultations of source Culgoora-1 0300+16 by Comet Kohoutek and of Culgoora-1 2313-14 by Comet West were measured by radioheliograph at 80 MHz. After corrections for ionospheric refraction, a 2 arcmin anomaly was observed in the declination of 0300+16, attributed to refraction by the tail of Comet Kohoutek, while none was observed for Comet West. The maximum electron density in the tail of Comet Kohoutek is calculated to be 2 x 10 to the 4th/cu cm, while that of Comet West is 5 x 10 to the 4th/cu cm, with density gradients of about 0.05 per cu cm per km. The direction of refraction observed suggests that the tail of Kohoutek is either highly asymmetric about its axis or has the form of a hollow, cylindrical plasma sheath. The high electron densities observed in Kohoutek may indicate the presence of undetected ion species or a low ionization loss rate.

  12. Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

    NARCIS (Netherlands)

    Buzi, L.; De Temmerman, G.; Unterberg, B.; M. Reinhart,; Litnovsky, A.; Philipps, V.; Van Oost, G.; Möller, S.

    2014-01-01

    Systematic study of deuterium irradiation effects on tungsten was done under ITER - relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER - like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux

  13. Electron density and temperature in NIO1 RF source operated in oxygen and argon

    Science.gov (United States)

    Barbisan, M.; Zaniol, B.; Cavenago, M.; Pasqualotto, R.; Serianni, G.; Zanini, M.

    2017-08-01

    The NIO1 experiment, built and operated at Consorzio RFX, hosts an RF negative ion source, from which it is possible to produce a beam of maximum 130 mA in H- ions, accelerated up to 60 kV. For the preliminary tests of the extraction system the source has been operated in oxygen, whose high electronegativity allows to reach useful levels of extracted beam current. The efficiency of negative ions extraction is strongly influenced by the electron density and temperature close to the Plasma Grid, i.e. the grid of the acceleration system which faces the source. To support the tests, these parameters have been measured by means of the Optical Emission Spectroscopy diagnostic. This technique has involved the use of an oxygen-argon mixture to produce the plasma in the source. The intensities of specific Ar I and Ar II lines have been measured along lines of sight close to the Plasma Grid, and have been interpreted with the ADAS package to get the desired information. This work will describe the diagnostic hardware, the analysis method and the measured values of electron density and temperature, as function of the main source parameters (RF power, pressure, bias voltage and magnetic filter field). The main results show that not only electron density but also electron temperature increase with RF power; both decrease with increasing magnetic filter field. Variations of source pressure and plasma grid bias voltage appear to affect only electron temperature and electron density, respectively.

  14. Pulse compression radar reflectometry for density measurements on fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Costley, A.; Prentice, R. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Laviron, C. [Compagnie Generale des Matieres Nucleaires (COGEMA), 78 - Velizy-Villacoublay (France); Prentice, R. [Toulouse-3 Univ., 31 (France). Centre d`Etude Spatiale des Rayonnements

    1994-07-01

    On tokamaks and other toroidal machines, reflectometry is a very rapidly developing technique for density profile measurements, particularly near the edge. Its principle relies on the total reflection of an electromagnetic wave at a cutoff layer, where the critical density is reached and the local refractive index goes to zero. With the new fast frequency synthesizers now available, a method based on pulse compression radar is proposed for plasma reflectometry, overcoming the limitations of the previous reflectometry methods. The measurement can be made on a time-scale which is effectively very short relatively to the plasma fluctuations, and the very high reproducibility and stability of the source allows an absolute calibration of the waveguides to be made, which corrects for the effects of the parasitic reflections. 2 refs., 5 figs.

  15. Density bunching effects in a laser-driven, near-critical density plasma for ion acceleration

    Science.gov (United States)

    Ettlinger, Oliver; Sahai, Aakash; Hicks, George; Ditter, Emma-Jane; Dover, Nicholas; Chen, Yu-Hsin; Helle, Michael; Gordon, Daniel; Ting, Antonio; Polyanskiy, Mikhail; Pogorelsky, Igor; Babzien, Marcus; Najmudin, Zulfikar

    2016-10-01

    We present work investigating the interaction of relativistic laser pulses with near-critical density gas targets exhibiting pre-plasma scale lengths of several laser wavelengths. Analytical and computational modelling suggest that the interaction dynamics in a low-Z plasma is a direct result of induced density bunching up to the critical surface. In fact, these bunches can themselves become overcritical and experience significant radiation pressure, accelerating ions to higher energies compared to an ``idealised'' plasma slab target. This work will be used to help explain the observation of ion energies exceeding those predicted by radiation pressure driven hole-boring in recent experiments using the TW CO2 laser at the Accelerator Test Facility at Brookhaven National Laboratory.

  16. Fly ash particles spheroidization using low temperature plasma energy

    Science.gov (United States)

    Shekhovtsov, V. V.; Volokitin, O. G.; Kondratyuk, A. A.; Vitske, R. E.

    2016-11-01

    The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO2; 20.61 wt.% Al2O3 and 17.55 wt.% Fe2O3 phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O2Si, phase, increase of O22Al20 and Fe2O3 phases and change in Al, O density of O22Al20 chemical unit cell.

  17. Simulations of Stimulated Raman Scattering in Low-Density Plasmas

    Institute of Scientific and Technical Information of China (English)

    CAO Lihua; CHANG Tieqiang; LIU Zhanjun; ZHENG Chunyang

    2007-01-01

    Stimulated Raman scattering(SRS)in a low-density plasma slab is investigated by particle-in-cell(PIC)simulations.The backward stimulated Raman scattering(B-SRS)dominates initially and erodes the head of the pump wave,while the forward stimulated Raman scattering (F-SRS)subsequently develops and is located at the rear part of the slab.Two-stage electron acceleration may be more efficient due to the coexistence of these two instabilities.The B-SRS plasma wave with low phase velocities can accelerate the background electrons which may be further boosted to higher energies by the F-SRS plasma wave with high phase velocities.The simulations show that the peaks of the main components in both the frequency and wave number spectra occur at the positions estimated from the phase-matching conditions.

  18. Holographic quark-gluon plasmas at finite quark density

    Energy Technology Data Exchange (ETDEWEB)

    Bigazzi, F. [Dipartimento di Fisica e Astronomia, Universita di Firenze, Sesto Fiorentino (Firenze), Pisa (Italy); INFN, Sezione di Torino (Italy); Cotrone, A. [Dipartimento di Fisica, Universita di Torino (Italy); Mas, J. [Departamento de Fisica de Particulas, Universidade de Santiago de Compostela (Spain); Instituto Galego de Fisica de Altas Enerxias (IGFAE), Santiago de Compostela (Spain); Tarrio, J. [Institute for Theoretical Physics and Spinoza Institute, Universiteit Utrecht, 3584 CE, Utrecht (Netherlands); Mayerson, D. [Institute for Theoretical Physics, University of Amsterdam (Netherlands)

    2012-07-15

    Gravity solutions holographically dual to strongly coupled quark-gluon plasmas with non-zero quark density are reviewed. They are motivated by the urgency of finding novel tools to explore the phase diagram of QCD-like theories at finite chemical potential. After presenting the solutions and their regime of validity, some of their physical properties are discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Modifications of plasma density profile and thrust by neutral injection in a helicon plasma thruster

    Science.gov (United States)

    Takahashi, Kazunori; Takao, Yoshinori; Ando, Akira

    2016-11-01

    Argon propellant is introduced from the upstream and downstream sides of a high power helicon plasma thruster. The plasma density profile and the imparted thrust are measured for various upstream and downstream argon flow rates, where the total gas flow rate of 70 sccm and the resultant vacuum chamber pressure of 0.2 mTorr are maintained. It is observed that the imparted thrust increases with an increase in the downstream gas flow rate; simultaneously an upstream-peaking profile of the plasma density observed for the upstream gas injection becomes uniform for the downstream gas injection. The difference in the thrust between the upstream and downstream gas injections is enhanced by increasing the rf power. The observed density profiles are qualitatively consistent with theoretical predictions taking a neutral depletion effect into account.

  20. Altitude dependence of plasma density in the auroral zone

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    Full Text Available We study the altitude dependence of plasma depletions above the auroral region in the 5000–30 000 km altitude range using five years of Polar spacecraft potential data. We find that besides a general decrease of plasma density with altitude, there frequently exist additional density depletions at 2–4 RE radial distance, where RE is the Earth radius. The position of the depletions tends to move to higher altitude when the ionospheric footpoint is sunlit as compared to darkness. Apart from these cavities at 2–4 RE radial distance, separate cavities above 4 RE occur in the midnight sector for all Kp and also in the morning sector for high Kp. In the evening sector our data remain inconclusive in this respect. This holds for the ILAT range 68–74. These additional depletions may be substorm-related. Our study shows that auroral phenomena modify the plasma density in the auroral region in such a way that a nontrivial and interesting altitude variation results, which reflects the nature of the auroral acceleration processes.

    Key words. Magnetospheric physics (auroral phenomena; magnetosphere–ionosphere interactions

  1. Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L. [Department of Applied Physics, E.T.S.I. Aeronáutica y del Espacio. Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-01-15

    The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.

  2. High Energy-Density Plasma Dynamics in Plasma-Filled Rod-Pinch Diodes

    Science.gov (United States)

    2013-06-01

    at about 30 eV at the time of maximum energy density, and that the time-averaged ionization is about +17, similar to MHD model predictions [2... MHD model predictions [2]. The plasma mass distribution is inferred from x-ray distribution measurements. The time-dependent mass distribution is used...Previous modeling [2] assumed the tungsten plasma had a time-dependent Gaussian radial profile and a fixed length of 3.5 mm, consistent with time

  3. Meson properties at finite temperature and baryon density

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M.; Klimt, S.; Weise, W. (Inst. of Theoretical Physics, Univ. Regensburg (Germany))

    1992-06-22

    We use the generalized SU(3) version of the Nambu and Jona-Lasinio model to discuss properties of mesons, constituent quarks and vacuum structure as a function of density and temperature in compressed matter. Systematic low-density expansions are derived. In particular, we show that effects due to finite quasi-particle size are important in stabilizing the density and temperature dependence of the pion mass. (orig.).

  4. Relative contributions of temperature and salinity to seasonal mixed layer density changes and horizontal density gradients

    OpenAIRE

    Johnson, Gregory C.; Schmidtko, Sunke; Lyman, John M.

    2012-01-01

    Temperature and salinity both contribute to ocean density, including its seasonal cycle and spatial patterns in the mixed layer. Temperature and salinity profiles from the Argo Program allow construction and analysis of a global, monthly, mixed layer climatology. Temperature changes dominate the seasonal cycle of mixed layer density in most regions, but salinity changes are dominant in the tropical warm pools, Arctic, and Antarctic. Under the Intertropical Convergence Zone, temperature and sa...

  5. Plasma density control with ergodic divertor on Tore Supra; Controle de la densite du plasma en presence du divertor ergodique dans le tokamak Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Meslin, B

    1998-04-30

    Plasma density control on the tokamak Tore Supra is important for the optimization of every experimental scenario dealing with the improvement of plasma performances. Specific conditions are required both in the plasma bulk and at the edge. Within the framework of the present study, a magnetic configuration is used in the e plasma edge of Tore Supra: the ergodic divertor configuration. A magnetic perturbation which is resonant with the permanent field destroys the plasma confinement locally, opening the field lines onto the material components. They aim of the study is the characterization of the edge density in every relevant scenario for Tore Supra. The first part of this work is dedicated to density and temperature measurements by a series of fixed Langmuir probes located at the very edge of the plasma. Thanks to them, density regimes have been put in evidence during experiments where the volume averaged density , an usual control parameter of the plasma, was varied. The analysis of heat and particle transport through the plasma edge region explains the mechanisms leading to those regimes. The essential factor in our analysis is the dependence of the electron conductivity and ionization depth on temperature. While heat conduction governs the heat transport, the edge density varies linearly according to . Below a critical temperature, reached when the ion flux amplification at constant power density is large enough, a parallel temperature gradient appears leading to a density gradient in the opposite direction in order to maintain the pressure constant along the field lines. A high recycling regime is obtained and the edge density varies like {sup 3}. The pressure conservation is no more satisfied during the detachment of the plasma, which is characterized by a high neutral density at low temperatures leading to a ion momentum loss by friction against the neutrals. The edge density drops in those conditions. These regimes are similar

  6. Measurements of Rotational Temperatures in Atmospheric-Pressure Capillary Plasma Electrode (CPE) Discharge

    Science.gov (United States)

    Figus, Margaret; Abramzon, Nina; Becker, Kurt

    2003-10-01

    We report the results of rotational temperature measurements in atmospheric-pressure capillary plasma electrode (CPE) discharges in ambient air using the unresolved N2 second positive band. Assuming that the emitting N2 molecules can be described by a Maxwell-Boltzmann distribution characterized by a single rotational temperature, this temperature is determined from a fit of the measured emission spectrum to a calculated spectrum. If the emitting species are in equilibrium with the bulk gas in the plasma, then this temperature can be interpreted as the gas kinetic temperature in the plasma. We determined rotational temperatures for three different plasma regions: inside the capillary by analyzing radiation emitted along the axis of the capillary, between the capillaries, and perpendicular to the axis of the capillary. Each region has a different plasma density and, therefore, a different gas temperature with the plasma inside the capillary being the hottest. We also measured the rotational temperatures in each region as a function of the plasma power. As expected, the rotational temperatures increase with increasing discharge power. Work supported by the NSF and by ARO through a DURIP award.

  7. SPECTROSCOPIC DIAGNOSIS IN ELECTRONIC TEMPERATURE OF PHOTOIONISE PLASMAS

    Directory of Open Access Journals (Sweden)

    A. K. Ferouani

    2015-08-01

    Full Text Available In this work, we are interested in the diagnostics in electronic temperature of a plasma purely photoionized, based on the intensity ration of lines emitted by ions helium-like, which have an atomic number Z relatively small. We considered the three lines corresponding to the transitions starting from the excited levels 1s2l towards the fundamental level 1s2 1S0, like appropriate lines. More precisely, the line of resonance w due to the transition 1s2p 1P1 --- 1s2 1 S0, the line of intercombinaison (x,y 1s2p 3 P2,1 --- 1s2 1 S0  as well as prohibited line z due to the transition 1s2 3 S1 --- 1s2 1 S0. These lines appear clearly in the spectra of astrophysical plasmas. As helium-like ion, we chose two, the oxygen O6+ (Z=8 and neon Ne8+ (Z=10. We carried out calculations of the ration of lines intensity G=(z+x+y/w of O6+ and Ne8+  according to the electronic temperature in the range going from 105 to 107 K. We will see that, like it was shown by Gabriel and Jordan in 1969 [1], this intensity ration can be very sensitive to the temperature electronic and practically independent of the electronic density. Consequently, the ration G can be used to determine in a reliable way the electronic temperature of plasma observed [2].

  8. DIAGNOSTIC SPECTROSCOPIQUE EN TEMPERATURE ELECTRONIQUE DES PLASMAS PHOTOIONISES

    Directory of Open Access Journals (Sweden)

    A. K Ferouani

    2009-12-01

    Full Text Available In this work, we are interested in the diagnostics in electronic temperature of a plasma purely photoionized, based on the intensity ration of lines emitted by ions helium-like, witch have an atomic number Z relatively small. We considered the three lines corresponding to the transitions starting from the excited levels 1s2l towards the fundamental level 1s2 1S0, like appropriate lines. More precisely, the line of resonance w due to the transition 1s2p 1P1 1s2 1 S0, the line of intercombinaison (x,y 1s2p 3 P2,1 1s2 1 S0 as well as prohibited line z due to the transition 1s2 3 S1 1s2 1 S0. These lines appear clearly in the spectra of astrophysical plasmas. As helium-like ion, we chose two, the oxygen O6+ (Z=8 and neon Ne8+ (Z=10. We carried out calculations of the ration of lines intensity G=(zxy/w of O6+ and Ne8+ according to the electronic temperature in the range going from 105 to 107 K. We will see that, like it was shown by Gabriel and Jordan in 1969, this intensity ration can be very sensitive to the temperature electronic and practically independent of the electronic density. Consequently, the ration G can be used to determine in a reliable way the electronic temperature of plasma observed.

  9. Do plasma proteins distinguish between liposomes of varying charge density?

    KAUST Repository

    Capriotti, Anna Laura

    2012-03-01

    Cationic liposomes (CLs) are one of the most employed nonviral nanovector systems in gene therapy. However, their transfection efficiency is strongly affected by interactions with plasma components, that lead to the formation of a "protein corona" onto CL surface. The interactions between nanoparticles entering the body and biomolecules have an essential role for their biodistribution. Because the knowledge of proteins adsorbed onto vector surface could be useful in the screening of new, more efficient and more biocompatible liposomal formulations, the behavior of three CLs with different membrane charge densities was investigated. The proteins of the three coronas were identified by nano-liquid chromatography-tandem mass spectrometry, and quantified with label-free spectral counting strategy. Fibrinogen displayed higher association with CLs with high membrane charge density, while apolipoproteins and C4b-binding protein with CLs with low membrane charge density. These results are discussed in terms of the different lipid compositions of CLs and may have a deep biological impact for in vivo applications. Surface charge of nanoparticles is emerging as a relevant factor determining the corona composition after interaction with plasma proteins. Remarkably, it is also shown that the charge of the protein corona formed around CLs is strongly related to their membrane charge density. © 2012 Elsevier B.V.

  10. Evaporation of carbon using electrons of a high density plasma; Evaporacion de carbono usando los electrones de un plasma de alta densidad

    Energy Technology Data Exchange (ETDEWEB)

    Muhl, S.; Camps, E.; Escobar A, L.; Garcia E, J.L.; Olea, O. [Instituto de Investigaciones en Materiales, UNAM, C.P. 04510 Mexico D.F. (Mexico)

    2000-07-01

    The high density plasmas are used frequently in the preparation of thin films or surface modification, for example to nitridation. In these processes, are used mainly the ions and the neutrals which compose the plasma. However, the electrons present in the plasma are not used, except in the case of chemical reactions induced by collisions, although the electron bombardment usually get hot the work piece. Through the adequate polarization of a conductor material, it is possible to extract electrons from a high density plasma at low pressure, that could be gotten the evaporation of this material. As result of the interaction between the plasma and the electron flux with the vapor produced, this last will be ionized. In this work, it is reported the use of this novelty arrangement to prepare carbon thin films using a high density argon plasma and a high purity graphite bar as material to evaporate. It has been used substrates outside plasma and immersed in the plasma. Also it has been reported the plasma characteristics (temperature and electron density, energy and ions flux), parameters of the deposit process (deposit rate and ion/neutral rate) as well as the properties of the films obtained (IR absorption spectra and UV/Vis, elemental analysis, hardness and refractive index). (Author)

  11. Density profile in shock wave fronts of partially ionized xenon plasmas

    CERN Document Server

    Reinholz, H; Morozov, I; Mintsev, V; Zaparoghets, Y; Fortov, V; Wierling, A

    2003-01-01

    Results for the reflection coefficient of shock-compressed dense xenon plasmas at pressures of 1.6-20 GPa and temperatures around 30 000 K are interpreted. In addition to former experiments using laser beams with lambda = 1.06 mu m, measurements at lambda = 0.694 mu m have been performed recently. Reflectivities typical for metallic systems are found at high densities. Besides free carriers, the theoretical description also takes into account the influence of the neutral component of the plasma on the reflectivity. A consistent description of the measured reflectivities is achieved only if a finite width of the shock wave front is considered.

  12. Upstream Density for Plasma Detachment with Conventional and Lithium Vapor-Box Divertors

    Science.gov (United States)

    Goldston, Rj; Schwartz, Ja

    2016-10-01

    Fusion power plants are likely to require detachment of the divertor plasma from material targets. The lithium vapor box divertor is designed to achieve this, while limiting the flux of lithium vapor to the main plasma. We develop a simple model of near-detachment to evaluate the required upstream plasma density, for both conventional and lithium vapor-box divertors, based on particle and dynamic pressure balance between up- and down-stream, at near-detachment conditions. A remarkable general result is found, not just for lithium-induced detachment, that the upstream density divided by the Greenwald-limit density scales as (P 5 / 8 /B 3 / 8) Tdet1 / 2 / (ɛcool + γTdet) , with no explicit size scaling. Tdet is the temperature just before strong pressure loss, 1/2 of the ionization potential of the dominant recycling species, ɛcool is the average plasma energy lost per injected hydrogenic and impurity atom, and γ is the sheath heat transmission factor. A recent 1-D calculation agrees well with this scaling. The implication is that the plasma exhaust problem cannot be solved by increasing R. Instead significant innovation, such as the lithium vapor box divertor, will be required. This work supported by DOE Contract No. DE-AC02-09CH11466.

  13. Force-free collisionless current sheet models with non-uniform temperature and density profiles

    Science.gov (United States)

    Wilson, F.; Neukirch, T.; Allanson, O.

    2017-09-01

    We present a class of one-dimensional, strictly neutral, Vlasov-Maxwell equilibrium distribution functions for force-free current sheets, with magnetic fields defined in terms of Jacobian elliptic functions, extending the results of Abraham-Shrauner [Phys. Plasmas 20, 102117 (2013)] to allow for non-uniform density and temperature profiles. To achieve this, we use an approach previously applied to the force-free Harris sheet by Kolotkov et al. [Phys. Plasmas 22, 112902 (2015)]. In one limit of the parameters, we recover the model of Kolotkov et al. [Phys. Plasmas 22, 112902 (2015)], while another limit gives a linear force-free field. We discuss conditions on the parameters such that the distribution functions are always positive and give expressions for the pressure, density, temperature, and bulk-flow velocities of the equilibrium, discussing the differences from previous models. We also present some illustrative plots of the distribution function in velocity space.

  14. Investigation of relationship between plasma gas temperature and reactive species

    Science.gov (United States)

    Doyama, Hideyuki; Kawano, Hiroaki; Takamatsu, Toshihiro; Matsumura, Yuriko; Miyahara, Hidekazu; Iwasawa, Atsuo; Azuma, Takeshi; Okino, Akitoshi

    2016-09-01

    In recent years, atmospheric non-thermal plasmas have attracted attention as a new sterilization device. In conventional plasma source, since the plasma gas temperature depends on the discharge power, influence of the plasma gas temperature on bactericidal ability by constant power has not been investigated. Therefore, we developed a new plasma source that can control the plasma gas temperature independently of the power, and it was shown that the bactericidal ability is increased with the plasma gas temperature. However, this factor has not been revealed. In this study, we investigated relationship between the bactericidal ability and the concentration of reactive species at each plasma gas temperature. Because reactive species generated by plasma are thought to affect sterilization. So, to investigate lifetime of the sterilizing factor bactericidal ability of Plasma Treated Water made by each gas temperature plasma was investigated. In both experiments, the correlation (R2 = 0.999) was observed between the concentration of singlet oxygen (1O2) and the bactericidal ability. These results show long-lifetime reactive species generated by 1O2 affects the bactericidal ability.

  15. A Multiple Z-Pinch Configuration for the Generation of High-Density, Magnetized Plasmas

    Science.gov (United States)

    Tarditi, Alfonso G.

    2015-11-01

    The z-pinch is arguably the most straightforward and economical approach for the generation and confinement of hot plasmas, with a long history of theoretical investigations and experimental developments. While most of the past studies were focused on countering the natural tendency of z-pinches to develop instabilities, this study attempts to take advantage of those unstable regimes to form a quasi-stable plasma, with higher density and temperature, possibly of interest for a fusion reactor concept. For this purpose, a configuration with four z-pinch discharges, with axis parallel to each other and symmetrically positioned, is considered. Electrodes for the generation of the discharges and magnetic coils are arranged to favor the formation of concave discharge patterns. The mutual attraction from the co-streaming discharge currents enhances this pattern, leading to bent plasma streams, all nearing towards the axis. This configuration is intended to excite and sustain a ``kink'' unstable mode for each z-pinch, eventually producing either plasmoid structures, detached from each discharge, or sustained kink patterns: both these cases appear to lead to plasmas merging in the central region. The feasibility of this approach in creating a higher density, hotter, meta-stable plasma regime is investigated computationally, addressing both the kink excitation phase and the dynamics of the converging plasma columns.

  16. Theory of density fluctuations in strongly radiative plasmas

    Science.gov (United States)

    Cross, J. E.; Mabey, P.; Gericke, D. O.; Gregori, G.

    2016-03-01

    Derivation of the dynamic structure factor, an important parameter linking experimental and theoretical work in dense plasmas, is possible starting from hydrodynamic equations. Here we obtain, by modifying the governing hydrodynamic equations, a new form of the dynamic structure factor which includes radiative terms. The inclusion of such terms has an effect on the structure factor at high temperatures, which suggests that its effect must be taken into consideration in such regimes.

  17. Multispecies density peaking in gyrokinetic turbulence simulations of low collisionality Alcator C-Mod plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, D. R., E-mail: dmikkelsen@pppl.gov; Bitter, M.; Delgado-Aparicio, L.; Hill, K. W. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Greenwald, M.; Howard, N. T.; Hughes, J. W.; Rice, J. E. [MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139 (United States); Reinke, M. L. [MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139 (United States); York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Podpaly, Y. [MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139 (United States); AAAS S and T Fellow placed in the Directorate for Engineering, NSF, 4201 Wilson Blvd., Arlington, Virginia 22230 (United States); Ma, Y. [MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139 (United States); ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Candy, J.; Waltz, R. E. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

    2015-06-15

    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.

  18. Determination of coronal temperatures from electron density profiles

    CERN Document Server

    Lemaire, J F

    2011-01-01

    The most popular method for determining coronal temperatures is the scale-height-method (shm). It is based on electron density profiles inferred from White Light (WL) brightness measurements of the corona during solar eclipses. This method has been applied to several published coronal electron density models. The calculated temperature distributions reach a maximum at r > 1.3 RS, and therefore do not satisfy one of the conditions for applying the shm method. Another method is the hydrostatic equilibrium method (hst), which enables coronal temperature distributions to be determined, providing solutions to the hydrostatic equilibrium equation. The temperature maximas using the hst method are almost equal to those obtained using the shm method, but the temperature peak is always at significantly lower altitude when the hst-method is used than when the shm-method is used. A third and more recently developed method, dyn, can be used for the same published electron density profiles. The temperature distributions ob...

  19. Modelling of a Multi-Temperature Plasma Composition

    Institute of Scientific and Technical Information of China (English)

    B. Liani; R.Benallal; Z.Bentalha

    2005-01-01

    @@ Knowledge of plasma composition is very important for various plasma applications and prediction of plasma properties. We use the Saha equation and Debye length equation to calculate the non-local thermodynamicequilibrium plasma composition. It has been shown that the model to 2T with T representing the temperature (electron temperature and heavy-particle temperature) described by Chen and Han [J. Phys. D 32 (1999)1711]can be applied for a mixture of gases, where each atomic species has its own temperature, but the model to 4T is more general because it can be applicable to temperatures distant enough of the heavy particles. This can occur in a plasma composed of big- or macro-molecules. The electron temperature Te varies in the range 8000*20000 K at atmospheric pressure.

  20. Whittaker functions in beam driven plasma wakefield acceleration for a plasma with a parabolic density profile

    Energy Technology Data Exchange (ETDEWEB)

    Golian, Y.; Dorranian, D., E-mail: d.dorranian@gmail.com [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Aslaninejad, M., E-mail: m.aslaninejad@ipm.ir [Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)

    2016-01-15

    A model for the interaction of charged particle beams and plasma for a linear wakefield generation in a parabolic plasma channel is presented. The density profile has the maximum on the axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. We have built a thorough analytical model and solved the governing equations for the wakefield acceleration of a charged particle beam. The longitudinal and radial wakefields are expressed by Whittaker functions, and for certain parameters of plasma and the beam, their behaviours in longitudinal and radial directions are investigated. It is observed that the radial electric field generated by the bunch increases with the distance behind the bunch.

  1. Whittaker functions in beam driven plasma wakefield acceleration for a plasma with a parabolic density profile

    Science.gov (United States)

    Golian, Y.; Aslaninejad, M.; Dorranian, D.

    2016-01-01

    A model for the interaction of charged particle beams and plasma for a linear wakefield generation in a parabolic plasma channel is presented. The density profile has the maximum on the axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. We have built a thorough analytical model and solved the governing equations for the wakefield acceleration of a charged particle beam. The longitudinal and radial wakefields are expressed by Whittaker functions, and for certain parameters of plasma and the beam, their behaviours in longitudinal and radial directions are investigated. It is observed that the radial electric field generated by the bunch increases with the distance behind the bunch.

  2. Real-time control of the plasma density profile on ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Mlynek, Alexander

    2010-07-20

    been chosen, which permits a very localized power deposition in the plasma center. As a coupling mechanism between temperature profile and density profile exists, central heating effects a central flattening or peaking of the density profile, depending on the type of discharge. This effect was successfully exploited for feedback control of the shape of the density profile. The last part of this thesis work investigates this coupling mechanism between temperature and density in more detail, especially with respect to the temporal behavior in response to sudden changes in the central heating power. Here, a hysteresis loop in the local density-temperature diagram is observed. With the help of a simple numerical model, it is finally shown that, based on the transport equations for heat and particles, the occurrence of such a hysteresis loop is expected. In particular, the results indicate a temperature dependence of the particle inwards drift. (orig.)

  3. Transport analysis of high radiation and high density plasmas in the ASDEX Upgrade tokamak

    Directory of Open Access Journals (Sweden)

    Casali L.

    2014-01-01

    Full Text Available Future fusion reactors, foreseen in the “European road map” such as DEMO, will operate under more demanding conditions compared to present devices. They will require high divertor and core radiation by impurity seeding to reduce heat loads on divertor target plates. In addition, DEMO will have to work at high core densities to reach adequate fusion performance. The performance of fusion reactors depends on three essential parameters: temperature, density and energy confinement time. The latter characterizes the loss rate due to both radiation and transport processes. The DEMO foreseen scenarios described above were not investigated so far, but are now addressed at the ASDEX Upgrade tokamak. In this work we present the transport analysis of such scenarios. Plasma with high radiation by impurity seeding: transport analysis taking into account the radiation distribution shows no change in transport during impurity seeding. The observed confinement improvement is an effect of higher pedestal temperatures which extend to the core via stiffness. A non coronal radiation model was developed and compared to the bolometric measurements in order to provide a reliable radiation profile for transport calculations. High density plasmas with pellets: the analysis of kinetic profiles reveals a transient phase at the start of the pellet fuelling due to a slower density build up compared to the temperature decrease. The low particle diffusion can explain the confinement behaviour.

  4. Wave Localization and Density Bunching in Pair Ion Plasmas

    CERN Document Server

    Mahajan, Swadesh M

    2008-01-01

    By investigating the nonlinear propagation of high intensity electromagnetic (EM) waves in a pair ion plasma, whose symmetry is broken via contamination by a small fraction of high mass immobile ions, it is shown that this new and interesting state of (laboratory created) matter is capable of supporting structures that strongly localize and bunch the EM radiation with density excess in the region of localization. Testing of this prediction in controlled laboratory experiments can lend credence, inter alia, to conjectures on structure formation (via the same mechanism) in the MEV era of the early universe.

  5. A unified model of density limit in fusion plasmas

    CERN Document Server

    Zanca, P; Escande, D F; Pucella, G; Tudisco, O

    2016-01-01

    A limit for the edge density, ruled by radiation losses from light impurities, is established by a minimal cylindrical magneto-thermal equilibrium model. For ohmic tokamak and reversed field pinch the limit scales linearly with the plasma current, as the empirical Greenwald limit. The auxiliary heating adds a further dependence, scaling with the 0.4 power, in agreement with L-mode tokamak experiments. For a purely externally heated configuration the limit takes on a Sudo-like form, depending mainly on the input power, and is compatible with recent Stellarator scalings.

  6. Temperature Dependence Viscosity and Density of Different Biodiesel Blends

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2015-01-01

    Full Text Available The main goal of this paper is to assess the effect of rapeseed oil methyl ester (RME concentration in diesel fuel on its viscosity and density behaviour. The density and dynamic viscosity were observed at various mixing ratios of RME and diesel fuel. All measurements were performed at constant temperature of 40 °C. Increasing ratio of RME in diesel fuel was reflected in increased density value and dynamic viscosity of the blend. In case of pure RME, pure diesel fuel, and a blend of both (B30, temperature dependence of dynamic viscosity and density was examined. Temperature range in the experiment was −10 °C to 80 °C. Considerable temperature dependence of dynamic viscosity and density was found and demonstrated for all three samples. This finding is in accordance with theoretical assumptions and reference data. Mathematical models were developed and tested. Temperature dependence of dynamic viscosity was modeled using a polynomial 3rd polynomial degree. Correlation coefficients R −0.796, −0.948, and −0.974 between measured and calculated values were found. Temperature dependence of density was modeled using a 2nd polynomial degree. Correlation coefficients R −0.994, −0.979, and −0.976 between measured and calculated values were acquired. The proposed models can be used for flow behaviour prediction of RME, diesel fuel, and their blends.

  7. Computational lipidology: predicting lipoprotein density profiles in human blood plasma.

    Directory of Open Access Journals (Sweden)

    Katrin Hübner

    2008-05-01

    Full Text Available Monitoring cholesterol levels is strongly recommended to identify patients at risk for myocardial infarction. However, clinical markers beyond "bad" and "good" cholesterol are needed to precisely predict individual lipid disorders. Our work contributes to this aim by bringing together experiment and theory. We developed a novel computer-based model of the human plasma lipoprotein metabolism in order to simulate the blood lipid levels in high resolution. Instead of focusing on a few conventionally used predefined lipoprotein density classes (LDL, HDL, we consider the entire protein and lipid composition spectrum of individual lipoprotein complexes. Subsequently, their distribution over density (which equals the lipoprotein profile is calculated. As our main results, we (i successfully reproduced clinically measured lipoprotein profiles of healthy subjects; (ii assigned lipoproteins to narrow density classes, named high-resolution density sub-fractions (hrDS, revealing heterogeneous lipoprotein distributions within the major lipoprotein classes; and (iii present model-based predictions of changes in the lipoprotein distribution elicited by disorders in underlying molecular processes. In its present state, the model offers a platform for many future applications aimed at understanding the reasons for inter-individual variability, identifying new sub-fractions of potential clinical relevance and a patient-oriented diagnosis of the potential molecular causes for individual dyslipidemia.

  8. Probing near-solid density plasmas using soft x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Toleikis, S; Duesterer, S; Faeustlin, R R; Laarmann, T; Redlin, H [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg (Germany); Bornath, T; Goede, S; Irsig, R; Meiwes-Broer, K-H; Przystawik, A [Institut fuer Physik, Universitaet Rostock, Universitaetsplatz 3, 18051 Rostock (Germany); Doeppner, T; Glenzer, S H [Lawrence Livermore National Laboratory, 7000 East Av., Livermore, CA 94550 (United States); Foerster, E [Institut fuer Optik und Quantenelektronik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Fortmann, C [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Gregori, G; Mithen, J [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU (United Kingdom); Lee, H J; Nagler, B [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Li, B [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX (United Kingdom); Radcliffe, P, E-mail: sven.toleikis@desy.d [European XFEL GmbH, Albert-Einstein-Ring 19, 22671 Hamburg (Germany)

    2010-10-14

    X-ray scattering using highly brilliant x-ray free-electron laser (FEL) radiation provides new access to probe free-electron density, temperature and ionization in near-solid density plasmas. First experiments at the soft x-ray FEL FLASH at DESY, Hamburg, show the capabilities of this technique. The ultrashort FEL pulses in particular can probe equilibration phenomena occurring after excitation of the plasma using ultrashort optical laser pumping. We have investigated liquid hydrogen and find that the interaction of very intense soft x-ray FEL radiation alone heats the sample volume. As the plasma establishes, photons from the same pulse undergo scattering, thus probing the transient, warm dense matter state. We find a free-electron density of (2.6 {+-} 0.2) x 10{sup 20} cm{sup -3} and an electron temperature of 14 {+-} 3.5 eV. In pump-probe experiments, using intense optical laser pulses to generate more extreme states of matter, this interaction of the probe pulse has to be considered in the interpretation of scattering data. In this paper, we present details of the experimental setup at FLASH and the diagnostic methods used to quantitatively analyse the data.

  9. Plasmaspheric H+, He+, O+, He++, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, D. L.; Craven, P. D.; Comfort H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  10. Plasmaspheric H+, He+, He++, O+, and O++ Densities and Temperatures

    Science.gov (United States)

    Gallagher, G. L.; Craven, P. D.; Comfort, R. H.

    2013-01-01

    Thermal plasmaspheric densities and temperatures for five ion species have recently become available, even though these quantities were derived some time ago from the Retarding Ion Mass Spectrometer onboard the Dynamics Explorer 1 satellite over the years 1981-1984. The quantitative properties will be presented. Densities are found to have one behavior with lessor statistical variation below about L=2 and another with much greater variability above that Lshell. Temperatures also have a behavior difference between low and higher L-values. The density ratio He++/H+ is the best behaved with values of about 0.2% that slightly increase with increasing L. Unlike the He+/H+ density ratio that on average decreases with increasing Lvalue, the O+/H+ and O++/H+ density ratios have decreasing values below about L=2 and increasing average ratios at higher L-values. Hydrogen ion temperatures range from about 0.2 eV to several 10s of eV for a few measurements, although the bulk of the observations are of temperatures below 3 eV, again increasing with L-value. The temperature ratios of He+/H+ are tightly ordered around 1.0 except for the middle plasmasphere between L=3.5 and 4.5 where He+ temperatures can be significantly higher. The temperatures of He++, O+, and O++ are consistently higher than H+.

  11. Exchange corrections in a low-temperature plasma.

    Science.gov (United States)

    Ekman, Robin; Zamanian, Jens; Brodin, Gert

    2015-07-01

    We have studied the exchange corrections to linear electrostatic wave propagation in a plasma using a quantum kinetic formalism. Specifically, we have considered the zero-temperature limit. In order to simplify the calculations we have focused on the long-wavelength limit, i.e., wavelengths much longer than the de Broglie wavelength. For the case of ion-acoustic waves we have calculated the exchange correction both to the damping rate and the real part of the frequency. For Langmuir waves the frequency shift due to exchange effects is found. Our results are compared with the frequency shifts deduced from commonly used exchange potentials which are computed from density-functional theory.

  12. Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

    Energy Technology Data Exchange (ETDEWEB)

    Buzi, Luxherta, E-mail: l.buzi@fz-juelich.de [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Université de Lorraine, Institut Jean Lamour, CNRS UMR 7198, Bvd. des Aiguillettes, F-54506 Vandoeuvre (France); Temmerman, Greg De [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Unterberg, Bernhard; Reinhart, Michael; Litnovsky, Andrey; Philipps, Volker [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Oost, Guido Van [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Möller, Sören [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany)

    2014-12-15

    Systematic study of deuterium irradiation effects on tungsten was done under ITER – relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER – like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux densities (high: 3.5–7 · 10{sup 23} D{sup +}/m{sup 2} s and low: 9 · 10{sup 21} D{sup +}/m{sup 2} s). Particle fluence and ion energy, respectively 10{sup 26} D{sup +}/m{sup 2} and ∼38 eV were kept constant in all cases. The experiments were performed at three different surface temperatures 530 K, 630 K and 870 K. Experimental results concerning the deuterium retention and surface modifications of low flux exposure confirmed previous investigations. At temperatures 530 K and 630 K, deuterium retention was higher at lower flux density due to the longer exposure time (steady state plasma operation) and a consequently deeper diffusion range. At 870 K, deuterium retention was found to be higher at high flux density according to the thermal desorption spectroscopy (TDS) measurements. While blisters were completely absent at low flux density, small blisters of about 40–50 nm were formed at high flux density exposure. At the given conditions, a relation between deuterium retention and blister formation has been found which has to be considered in addition to deuterium trapping in defects populated by diffusion.

  13. Temperature and density structure of a recurring active region jet

    Science.gov (United States)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-01-01

    Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, such as density, differential emission measure, peak temperature, velocity, and filling factor. Methods: A differential emission measure (DEM) analysis was performed at the region of the jet spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The resulting EIS DEM curves were compared to those obtained with AIA-XRT. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The predicted total count rates for each AIA channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the DEM inversion were investigated. Spectroscopic diagnostics were used to obtain an electron number density distribution for the jet spire and the jet footpoint. Results: The plasma along the line of sight in the jet spire and jet footpoint was found to be peak at 2.0 MK (log T [K] = 6.3). We calculated electron densities using the Fe XII (λ186/λ195) line ratio in the region of the spire (Ne = 7.6 × 1010 cm-3) and the footpoint (1.1 × 1011 cm-3). The plane-of-sky velocity of the jet is found to be 524 km s-1. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. The synthetic spectra contributing to each AIA channel confirms the multi-thermal nature of the AIA channels in both regions. There is no indication of high temperatures, such as emission from Fe XVII (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of the jet footpoint, synthetic spectra predict weak contributions from Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation, we confirmed

  14. Neutral gas density depletion due to neutral gas heating and pressure balance in an inductively coupled plasma

    Science.gov (United States)

    Shimada, Masashi; Tynan, George R.; Cattolica, Robert

    2007-02-01

    The spatial distribution of neutral gas temperature and total pressure have been measured for pure N2, He/5%N2 and Ar/5%N2 in an inductively coupled plasma (ICP) reactor, and a significant rise in the neutral gas temperature has been observed. When thermal transpiration is used to correct total pressure measurements, the total pressure remains constant regardless of the plasma condition. Neutral pressure is depleted due to the pressure balance when the plasma pressure (mainly electron pressure) becomes comparable to the neutral pressure in high density plasma. Since the neutral gas follows the ideal gas law, the neutral gas density profile was obtained from the neutral gas temperature and the corrected neutral pressure measurements. The results show that the neutral gas density at the centre of the plasma chamber (factor of 2-4 ×) decreases significantly in the presence of a plasma discharge. Significant spatial variation in neutral gas uniformity occurs in such plasmas due to neutral gas heating and pressure balance.

  15. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    Bin Luo; Shuang-Nan Zhang

    2004-01-01

    In normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma.We calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions.Our results show that the total radiation power is always lower if the motion of ions is considered.We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow(ADAF)model:we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.

  16. Low temperature synthesis of silicon quantum dots with plasma chemistry control in dual frequency non-thermal plasmas.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Han, Jeon Geon; Shiratani, Masaharu

    2016-06-21

    The advanced materials process by non-thermal plasmas with a high plasma density allows the synthesis of small-to-big sized Si quantum dots by combining low-temperature deposition with superior crystalline quality in the background of an amorphous hydrogenated silicon nitride matrix. Here, we make quantum dot thin films in a reactive mixture of ammonia/silane/hydrogen utilizing dual-frequency capacitively coupled plasmas with high atomic hydrogen and nitrogen radical densities. Systematic data analysis using different film and plasma characterization tools reveals that the quantum dots with different sizes exhibit size dependent film properties, which are sensitively dependent on plasma characteristics. These films exhibit intense photoluminescence in the visible range with violet to orange colors and with narrow to broad widths (∼0.3-0.9 eV). The observed luminescence behavior can come from the quantum confinement effect, quasi-direct band-to-band recombination, and variation of atomic hydrogen and nitrogen radicals in the film growth network. The high luminescence yields in the visible range of the spectrum and size-tunable low-temperature synthesis with plasma and radical control make these quantum dot films good candidates for light emitting applications.

  17. Doppler Spectrometry for Ultrafast Temporal Mapping of Density Dynamics in Laser-Induced Plasmas

    Science.gov (United States)

    Mondal, S.; Lad, Amit D.; Ahmed, Saima; Narayanan, V.; Pasley, J.; Rajeev, P. P.; Robinson, A. P. L.; Kumar, G. Ravindra

    2010-09-01

    We present high resolution measurements of the ultrafast temporal dynamics of the critical surface in moderately overdense, hot plasma by using two-color, pump-probe Doppler spectrometry. Our measurements clearly capture the initial inward motion of the plasma inside the critical surface of the pump laser which is followed by outward expansion. The measured instantaneous velocity and acceleration profiles are very well reproduced by a hybrid simulation that uses a 1D electromagnetic particle-in-cell simulation for the initial evolution and a hydrodynamics simulation for the later times. The combination of high temporal resolution and dynamic range in our measurements clearly provides quantitative unraveling of the dynamics in this important region, enabling this as a powerful technique to obtain ultrafast snapshots of plasma density and temperature profiles for providing benchmarks for simulations.

  18. Electron temperature dynamics of TEXTOR plasmas

    NARCIS (Netherlands)

    Udintsev, Victor Sergeevich

    2003-01-01

    To study plasma properties in the presence of large and small MHD modes, new high-resolution ECE diagnostics have been installed at TEXTOR tokamak, and some of the already existing systems have been upgraded. Two models for the plasma transport properties inside large m/n = 2/1 MHD islands have been

  19. Temperature dependence of densities of Sb and Bi melts

    Institute of Scientific and Technical Information of China (English)

    GENG HaoRan; SUN ChunJing; WANG Rui; QI XiaoGang; ZHANG Ning

    2007-01-01

    The densities of Sb and Bi melts were investigated by an improved Archimedean method. The results show that the density of the Sb melt decreases linearly with increasing temperature, but the density of the Bi melt firstly increases and then decreases as the temperature increases. There is a maximum density value of 10.002 g/cm3 at 310℃, about 39℃ above the melting point. The temperature dependence of the Sb melt is well fitted with the expression ρ= 6.8590-5.8105×10-4T, and that of the Bi melt is fitted with ρ=10.3312-1.18×10-3T. The results were discussed from a microstructure viewpoint.

  20. Density of biogas digestate depending on temperature and composition.

    Science.gov (United States)

    Gerber, Mandy; Schneider, Nico

    2015-09-01

    Density is one of the most important physical properties of biogas digestate to ensure an optimal dimensioning and a precise design of biogas plant components like stirring devices, pumps and heat exchangers. In this study the density of biogas digestates with different compositions was measured using pycnometers at ambient pressure in a temperature range from 293.15 to 313.15K. The biogas digestates were taken from semi-continuous experiments, in which the marine microalga Nannochloropsis salina, corn silage and a mixture of both were used as feedstocks. The results show an increase of density with increasing total solid content and a decrease with increasing temperature. Three equations to calculate the density of biogas digestate were set up depending on temperature as well as on the total solid content, organic composition and elemental composition, respectively. All correlations show a relative deviation below 1% compared to experimental data.

  1. Baryon number fluctuations at finite temperature and density

    CERN Document Server

    Fu, Wei-jie; Rennecke, Fabian; Schaefer, Bernd-Jochen

    2016-01-01

    We investigate baryon number fluctuations for finite temperature and density in two-flavor QCD. This is done within a QCD-improved low-energy effective theory in an extension of the approach put forward in [1,2]. In the present work we aim at improving the predictive power of this approach for large temperatures and density, that is, for small collision energies. This is achieved by taking into account the full frequency dependence of the quark dispersion. This ensures the necessary Silver Blaze property of finite density QCD for the first time, which so far was only implemented approximately. Moreover, we show that Polyakov loop fluctuations have a sizeable impact at large temperatures and density. The results for the kurtosis of baryon number fluctuations are compared to previous effective theory results, lattice results and recent experimental data from STAR.

  2. Development of plasma bolometers using fiber-optic temperature sensors

    Energy Technology Data Exchange (ETDEWEB)

    Reinke, M. L., E-mail: reinkeml@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Han, M.; Liu, G. [University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States); Eden, G. G. van [Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612 AJ Eindhoven (Netherlands); Evenblij, R.; Haverdings, M. [Technobis, Pyrietstraat 2, 1812 SC Alkmaar (Netherlands); Stratton, B. C. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

    2016-11-15

    Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry–Pérot cavity when broadband light, λ{sub o} ∼ 1550 nm, is transmitted along the fiber. Changes in temperature alter the optical path length of the cavity primarily through the thermo-optic effect, resulting in a shift of fringes reflected from the pillar detected using an I-MON 512 OEM spectrometer. While initially designed for use in liquids, this sensor has ideal properties for use as a plasma bolometer: a time constant, in air, of ∼150 ms, strong absorption in the spectral range of plasma emission, immunity to local EMI, and the ability to measure changes in temperature remotely. Its compact design offers unique opportunities for integration into the vacuum environment in places unsuitable for a resistive bolometer. Using a variable focus 5 mW, 405 nm, modulating laser, the signal to noise ratio versus power density of various bolometer technologies are directly compared, estimating the noise equivalent power density (NEPD). Present tests show the fiber-optic bolometer to have NEPD of 5-10 W/m{sup 2} when compared to those of the resistive bolometer which can achieve <0.5 W/m{sup 2} in the laboratory, but this can degrade to 1-2 W/m{sup 2} or worse when installed on a tokamak. Concepts are discussed to improve the signal to noise ratio of this new fiber-optic bolometer by reducing the pillar height and adding thin metallic coatings, along with improving the spectral resolution of the interrogator.

  3. Electron Temperature and Plasma Flow Measurements of NIF Hohlraum Plasmas

    Science.gov (United States)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brow, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Eder, D.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; LLNL Collaboration; LLE Collaboration; GA Collaboration; SNL Collaboration

    2016-10-01

    Characterizing the plasma conditions inside NIF hohlraums, in particular mapping the plasma Te, is critical to gaining insight into mechanisms that affect energy coupling and transport in the hohlraum. The dot spectroscopy platform provides a temporal history of the localized Te and plasma flow inside a NIF hohlraum, by introducing a Mn-Co tracer dot, at strategic locations inside the hohlraum, that comes to equilibrium with the local plasma. K-shell X-ray spectroscopy of the tracer dot is recorded onto an absolutely calibrated X-ray streak spectrometer. Isoelectronic and interstage line ratios are used to infer localized Te through comparison with atomic physics calculations using SCRAM. Time resolved X-ray images are simultaneously taken of the expanding dot, providing plasma (ion) flow information. We present recent results provided by this platform and compare with simulations using HYDRA. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  4. Temperature and relative density of atomic hydrogen in a multicusp H sup minus volume source

    Energy Technology Data Exchange (ETDEWEB)

    Bruneteau, A.M.; Hollos, G.; Bacal, M. (Laboratoire de Physique des Milieux Ionises, Laboratoire du Centre National de la Recherche Scientifique, Ecole Polytechnique, 91128 Palaiseau Cedex, (France)); Bretagne, J. (Laboratoire de Physique des Gaz et des Plasmas, LA73 du Centre National de la Recherche Scientifique, Universite de Paris-Sud, 91405 Orsay (France))

    1990-06-15

    The Balmer {beta} and {gamma} line shapes have been analyzed to determine the relative density and the temperature of hydrogen atoms in magnetic multicusp plasma generators. Results for a 90-V, 4--40-mTorr, 1--18-A conventional multicusp plasma generator and a 50-V, 4-mTorr, 1--15-A hybrid multicusp plasma generator are presented. The relative number density of hydrogen atoms increased smoothly with pressure and discharge current but never exceeded 10%. The absolute atomic number density in a 90-V 10-A discharge varied in proportion with pressure. The atomic temperature (in the 0.1--0.4-eV range) decreased with pressure and slowly increased with the discharge current. The role of atoms in the processes determining the H{sup {minus}} temperature and the H{sub 2} vibrational and rotational temperatures is discussed. The results confirm that in multicusp negative-ion sources collisional excitation of ground state atoms and molecules by energetic electrons is the dominant process in Balmer-{beta} and -{gamma} light emission.

  5. Atomic temperature and density in multicusp H sup minus volume sources

    Energy Technology Data Exchange (ETDEWEB)

    Bruneteau, A.M.; Hollos, G.; Leroy, R.; Berlemont, P.; Bacal, M. (Laboratoire du C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Bertagne, J. (Laboratoire de Physique des Gaz et des Plasmas, LA73 du CNRS, Universite de Paris-Sud, 91405 Orsay (France))

    1990-08-05

    The Balmer {beta} and {gamma} line shapes have been analyzed to determine the relative density and the temperature of hydrogen atoms in magnetic multicusp plasma generators. Results for a 90 V, 4--40 mTorr, 1--18 A conventional multicusp plasma generator and a 50 V, 4 mTorr, 1--15 A hybrid multicusp plasma generator are presented. The relative number density of hydrogen atoms increases smoothly with pressure and discharge current but never exceeds 10%. The absolute atomic number density in a 90 V--10 A discharge varies in proportion with pressure. The atomic temperature (in the 0.1--0.4 eV range) decreases with pressure and slowly increases with the discharge current. The role of atoms in the processes determining the H{sup {minus}} temperature and the H{sub 2} vibrational and rotational temperatures is discussed. The results confirm that in multicusp negative ion sources collisional excitation of ground-state atoms and molecules by energetic electrons is the dominant process in Balmer {beta} and {gamma} light emission.

  6. Measurements of Ionospheric Density, Temperature, and Spacecraft Charging in a Space Weather Constellation

    Science.gov (United States)

    Balthazor, R. L.; McHarg, M. G.; Wilson, G.

    2016-12-01

    The Integrated Miniaturized Electrostatic Analyzer (IMESA) is a space weather sensor developed by the United States Air Force Academy and integrated and flown by the DoD's Space Test Program. IMESA records plasma spectrograms from which can be derived plasma density, temperature, and spacecraft frame charging. Results from IMESA currently orbiting on STPSat-3 are presented, showing frame charging effects dependent on a complex function of the number of solar panel cell strings switched in, solar panel current, and plasma density. IMESA will fly on four more satellites launching in the next two calendar years, enabling an undergraduate DoD space weather constellation in Low Earth Orbit that has the ability to significantly improve space weather forecasting capabilities using assimilative forecast models.

  7. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Science.gov (United States)

    Pu, Lumei; Gao, Jinzhang; Hu, Yusen; Liang, Huiguang; Xiao, Wen; Wang, Xingmin

    2008-06-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  8. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    PU Lumei; GAO Jinzhang; HU Yusen; LIANG Huiguang; XIAO Wen; WANG Xingmin

    2008-01-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  9. Ideal laser-beam propagation through high-temperature ignition Hohlraum plasmas.

    Science.gov (United States)

    Froula, D H; Divol, L; Meezan, N B; Dixit, S; Moody, J D; Neumayer, P; Pollock, B B; Ross, J S; Glenzer, S H

    2007-02-23

    We demonstrate that a blue (3omega, 351 nm) laser beam with an intensity of 2 x 10(15) W cm(-2) propagates nearly within the original beam cone through a millimeter scale, T(e)=3.5 keV high density (n(e)=5 x 10(20) cm(-3)) plasma. The beam produced less than 1% total backscatter at these high temperatures and densities; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  10. Laser Plasmas : Density oscillations in laser produced plasma decelerated by external magnetic field

    Indian Academy of Sciences (India)

    V N Rai; M Shukla; H C Pant

    2000-11-01

    This paper presents the dynamics as well as the stability of laser produced plasma expanding across the magnetic field. Observation of some high frequency fluctuations superimposed on ion saturation current along with structuring in the pin hole images of x-ray emitting plasma plume indicate the presence of instability in the plasma. Two type of slope in the variation of x-ray emission with laser intensity in the absence and presence of magnetic field shows appearance of different threshold intensity of laser corresponding to each magnetic field at which this instability or density fluctuation sets on. This instability has been identified as a large Larmor radius instability instead of classical Rayleigh-Taylor (R-T) instability.

  11. Determining the Concentrations and Temperatures of Products in a CF_4/CHF_3/N_2 Plasma via Submillimeter Absorption Spectroscopy

    Science.gov (United States)

    Helal, Yaser H.; Neese, Christopher F.; De Lucia, Frank C.; Ewing, Paul R.; Agarwal, Ankur; Craver, Barry; Stout, Phillip J.; Armacost, Michael D.

    2017-06-01

    Plasmas used for the manufacturing of semiconductor devices are similar in pressure and temperature to those used in the laboratory for the study of astrophysical species in the submillimeter (SMM) spectral region. The methods and technology developed in the SMM for these laboratory studies are directly applicable for diagnostic measurements in the semiconductor manufacturing industry. Many of the molecular neutrals, radicals, and ions present in processing plasmas have been studied and their spectra have been cataloged or are in the literature. In this work, a continuous wave, intensity calibrated SMM absorption spectrometer was developed as a remote sensor of gas and plasma species. A major advantage of intensity calibrated rotational absorption spectroscopy is its ability to determine absolute concentrations and temperatures of plasma species from first principles without altering the plasma environment. An important part of this work was the design of the optical components which couple 500-750 GHz radiation through a commercial inductively coupled plasma chamber. The measurement of transmission spectra was simultaneously fit for background and absorption signal. The measured absorption was used to calculate absolute densities and temperatures of polar species. Measurements for CHF_3, CF_2, FCN, HCN, and CN made in a CF_4/CHF_3/N_2 plasma will be presented. Temperature equilibrium among species will be shown and the common temperature is leveraged to obtain accurate density measurements for simultaneously observed species. The densities and temperatures of plasma species are studied as a function of plasma parameters, including flow rate, pressure, and discharge power.

  12. Patterned Platinum Etching Studies in an Argon High Density Plasma

    Science.gov (United States)

    Delprat, Sébastien; Chaker, Mohamed; Margot, Joëlle; Pépin, Henri; Tan, Liang; Smy, Tom

    1998-10-01

    A high-density surface-wave Ar plasma operated in the low pressure regime is used to study pure physical etching characteristics of platinum thin films. The platinum samples are RF biased so as to obtain a maximum DC self-bias voltage of 150 V. The sputter-etching characteristics are investigated as a function of the magnetic field intensity, the self-bias voltage and the gas pressure. At 1 mtorr, the etch rate is found to be a unique linear function of both the self-bias voltage and the ion density, independently of the magnetic field intensity value. However, even though the ion density increases, the etch rate is found to decrease with increasing pressure. In the low pressure regime, etch rates as high as 2000 A/min are obtained with a good selectivity over resist. Without any optimization of the etching process, we were able to etch 0.5 micron Pt trenches, 0.6 micron thick yielding fence-free profiles and sidewall angles (75º) that already meets the present industrial requirements of NVRAM technology.

  13. Discharge dynamics and plasma density recovery by on/off switches of additional gas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyo-Chang, E-mail: lhc@kriss.re.kr [Center for Vacuum Technology, Korea Research Institute of Standard and Science, Daejeon 305-340 (Korea, Republic of); Department of Electrical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763 (Korea, Republic of); Kwon, Deuk-Chul [Plasma Technology Research Center, Nation Fusion Research Institute, Gunsan 573-540 (Korea, Republic of); Oh, SeungJu; Kang, Hyun-Ju; Kim, Yu-Sin; Chung, Chin-Wook, E-mail: joykang@hanyang.ac.kr [Department of Electrical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763 (Korea, Republic of)

    2016-06-15

    Measurement of the plasma density is investigated to study plasma dynamics by adding reactive gas (O{sub 2}) or rare gas (He) in Ar plasmas. When the O{sub 2} or He gas is added, plasma density is suddenly decreased, while the plasma density recovers slowly with gas off. It is found that the recovery time is strongly dependent on the gas flow rate, and it can be explained by effect of gas residence time. When the He gas is off in the Ar plasma, the plasma density is overshot compared to the case of the O{sub 2} gas pulsing due to enhanced ionizations by metastable atoms. Analysis and calculation for correlation between the plasma density dynamics and the gas pulsing are also presented in detail.

  14. Modeling of neutral gas dynamics in high-density plasmas

    Science.gov (United States)

    Canupp, Patrick Wellington

    This thesis describes a physical model of chemically reactive neutral gas flow and discusses numerical solutions of this model for the flow in an inductively coupled plasma etch reactor. To obtain these solutions, this research develops an efficient, implicit numerical method. As a result of the enhanced numerical stability of the scheme, large time steps advance the solution from initial conditions to a final steady state in fewer iterations and with less computational expense than simpler explicit methods. This method would incorporate suitably as a module in currently existing large scale plasma simulation tools. In order to demonstrate the accuracy of the numerical technique, this thesis presents results from two simulations of flows that possess theoretical solutions. The first case is the inviscid flow of a gas through a converging nozzle. A comparison of the numerical solution to isentropic flow theory shows that the numerical technique capably captures the essential flow features of this environment. The second case is the Couette flow of a gas between two parallel plates. The simulation results compare well with the exact solution for this flow. After establishing the accuracy of the numerical technique, this thesis discusses results for the flow of chemically reactive gases in a chlorine plasma etch reactor. This research examines the influence of the plasma on the neutral gas and the dynamics exhibited by the neutral gas in the reactor. This research finds that the neutral gas temperature strongly depends on the rate at which inelastic, electron-impact dissociation reactions occur and on atomic chlorine wall recombination rates. Additionally, the neutral gas Aow in the reactor includes a significant mass flux of etch product from the wafer surface. Resolution of these effects is useful for neutral gas simulation. Finally, this thesis demonstrates that continuum fluid models provide reasonable accuracy for these low pressure reactor flows due to the fact

  15. Wavefront-sensor-based electron density measurements for laser-plasma accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; van Mourik, Reinier; Leemans, Wim

    2010-02-20

    Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength, hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, have greater phase sensitivity, straightforward analysis, improving shot-to-shot plasma-density diagnostics.

  16. Application of Atmospheric-Pressure Microwave Line Plasma for Low Temperature Process

    Science.gov (United States)

    Suzuki, Haruka; Nakano, Suguru; Itoh, Hitoshi; Sekine, Makoto; Hori, Masaru; Toyoda, Hirotaka

    2015-09-01

    Atmospheric pressure (AP) plasmas have been given much attention because of its high cost benefit and a variety of possibilities for industrial applications. In various kinds of plasma production technique, pulsed-microwave discharge plasma using slot antenna is attractive due to its ability of high-density and stable plasma production. In this plasma source, however, size of the plasma has been limited up to a few cm in length due to standing wave inside a waveguide. To solve this, we have proposed a newly-developed AP microwave plasma source that utilizes not standing wave but travelling wave. By using this plasma source, spatially-uniform AP line plasma with 40 cm in length was realized by pure helium discharge in 60 cm slot and with nitrogen gas additive of 1%. Furthermore, gas temperature as low as 400 K was realized in this device. In this study, as an example of low temperature processes, hydrophilic treatment of PET films was performed. Processing speed increased with pulse frequency and a water contact angle of ~20° was easily obtained within 5 s with no thermal damage to the substrate. To evaluate treatment-uniformity of long line length, PET films were treated by 90 cm slot-antenna plasma and uniform treatment performance was confirmed.

  17. Measurement of Plasma Density Produced in Dielectric Barrier Discharge for Active Aerodynamic Control with Interferometer

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHANG Yi; XU Yan-Ji; LIN Bin; LI Yu-Tong; ZHU Jun-Qiang

    2009-01-01

    We utilize an interferometer to investigate the changes of the refractive index caused by dielectric barrier discharge plasma.The electronic density of the plasma produced is measured and analyzed tentatively.The results show that density of the plasma increases linearly with exciting voltages.

  18. Self-injection by trapping of plasma electrons oscillating in rising density gradient at the vacuum-plasma interface

    CERN Document Server

    Sahai, Aakash A; Muggli, Patric

    2014-01-01

    We model the trapping of plasma $e^-$ within the density structures excited by a propagating energy source ($\\beta_{S}\\simeq1$) in a rising plasma density gradient. Rising density gradient leads to spatially contiguous coupled up-chirped plasmons ($d{\\omega^2_{pe}(x)}/{dx}>0$). Therefore phase mixing between plasmons can lead to trapping until the plasmon field is high enough such that $e^-$ trajectories returning towards a longer wavelength see a trapping potential. Rising plasma density gradients are ubiquitous for confining the plasma within sources at the vacuum-plasma interfaces. Therefore trapping of plasma-$e^-$ in a rising ramp is important for acceleration diagnostics and to understand the energy dissipation from the excited plasmon train \\cite{LTE-2013}. Down-ramp in density \\cite{density-transition-2001} has been used for plasma-$e^-$ trapping within the first bucket behind the driver. Here, in rising density gradient the trapping does not occur in the first plasmon bucket but in subsequent plasmon...

  19. Generation of attosecond electron bunches in a laser-plasma accelerator using a plasma density upramp

    Energy Technology Data Exchange (ETDEWEB)

    Weikum, M.K., E-mail: maria.weikum@desy.de [Deutsches Elektronensynchrotron (DESY), Bdg. 30b, Notkestr. 85, 22607 Hamburg (Germany); Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Li, F.Y. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Assmann, R.W. [Deutsches Elektronensynchrotron (DESY), Bdg. 30b, Notkestr. 85, 22607 Hamburg (Germany); Sheng, Z.M. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Laboratory for Laser Plasmas and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Jaroszynski, D. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom)

    2016-09-01

    Attosecond electron bunches and attosecond radiation pulses enable the study of ultrafast dynamics of matter in an unprecedented regime. In this paper, the suitability for the experimental realization of a novel scheme producing sub-femtosecond duration electron bunches from laser-wakefield acceleration in plasma with self-injection in a plasma upramp profile has been investigated. While it has previously been predicted that this requires laser power above a few hundred terawatts typically, here we show that the scheme can be extended with reduced driving laser powers down to tens of terawatts, generating accelerated electron pulses with minimum length of around 166 attoseconds and picocoulombs charge. Using particle-in-cell simulations and theoretical models, the evolution of the accelerated electron bunch within the plasma as well as simple scalings of the bunch properties with initial laser and plasma parameters are presented. - Highlights: • LWFA with an upramp density profile can trap and accelerate sub-fs electron beams. • A reduction of the necessary threshold laser intensity by a factor 4 is presented. • Electron properties are tuned by varying initial laser and plasma parameters. • Simulations predict electron bunch lengths below 200 attoseconds with pC charge. • Strong bunch evolution effects and a large energy spread still need to be improved.

  20. CENTER FOR PULSED POWER DRIVEN HIGH ENERGY DENSITY PLASMA STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Professor Bruce R. Kusse; Professor David A. Hammer

    2007-04-18

    This annual report summarizes the activities of the Cornell Center for Pulsed-Power-Driven High-Energy-Density Plasma Studies, for the 12-month period October 1, 2005-September 30, 2006. This period corresponds to the first year of the two-year extension (awarded in October, 2005) to the original 3-year NNSA/DOE Cooperative Agreement with Cornell, DE-FC03-02NA00057. As such, the period covered in this report also corresponds to the fourth year of the (now) 5-year term of the Cooperative Agreement. The participants, in addition to Cornell University, include Imperial College, London (IC), the University of Nevada, Reno (UNR), the University of Rochester (UR), the Weizmann Institute of Science (WSI), and the P.N. Lebedev Physical Institute (LPI), Moscow. A listing of all faculty, technical staff and students, both graduate and undergraduate, who participated in Center research activities during the year in question is given in Appendix A.

  1. Effect of density changes on tokamak plasma confinement

    CERN Document Server

    Spineanu, F

    2015-01-01

    A change of the particle density (by gas puff, pellets or impurity seeding) during the plasma discharge in tokamak produces a radial current and implicitly a torque and rotation that can modify the state of confinement. After ionization the newly born ions will evolve toward the periodic neoclassical orbits (trapped or circulating) but the first part of their excursion, which precedes the periodicity, is an effective radial current. It is short, spatially finite and unique for each new ion, but multiplied by the rate of ionization and it can produce a substantial total radial current. The associated torque induces rotation which modify the transport processes. We derive the magnitude of the radial current induced by ionization by three methods: the analysis of a simple physical picture, a numerical model and the neoclassical drift-kinetic treatment. The results of the three approaches are in agreement and show that the current can indeed be substantial. Many well known experimental observations can be reconsi...

  2. Counter-facing plasma focus system as a repetitive and/or long-pulse high energy density plasma source

    Science.gov (United States)

    Aoyama, Yutaka; Nakajima, Mitsuo; Horioka, Kazuhiko

    2009-11-01

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and/or repetitive high energy density plasma source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrodes. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time durations in at least ten microseconds.

  3. Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applications

    CERN Document Server

    Hsu, S C; Moser, A L; Awe, T J; Brockington, S J E; Davis, J S; Adams, C S; Case, A; Cassibry, J T; Dunn, J P; Gilmore, M A; Lynn, A G; Messer, S J; Witherspoon, F D

    2012-01-01

    We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed are density \\approx 2 x 10^(16) cm^(-3), electron temperature \\approx 1.4 eV, velocity \\approx 30 km/s, M \\approx 14, ionization fraction \\approx 0.96, diameter \\approx 5 cm, and length \\approx 20 cm. These values approach the range needed by the Plasma Liner Experiment (PLX), which is designed to use merging plasma jets to form imploding spherical plasma liners that can reach peak pressures of 0.1-1 Mbar at stagnation. As these jets propagate a distance of approximately 40 cm, the average density drops by one order of magnitude, which is up to an order of magnitude less than the drop predicted by the ideal hydrodynamic theory of a constant-M jet.

  4. Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applications

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, S. C.; Moser, A. L.; Awe, T. J.; Davis, J. S.; Dunn, J. P. [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Merritt, E. C.; Adams, C. S. [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); University of New Mexico, Albuquerque, New Mexico 87131 (United States); Brockington, S. J. E.; Case, A.; Messer, S. J.; Witherspoon, F. D. [HyperV Technologies Corp., Chantilly, Virginia 20151 (United States); Cassibry, J. T. [Propulsion Research Center, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Gilmore, M. A.; Lynn, A. G. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2012-12-15

    We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed are density Almost-Equal-To 2 Multiplication-Sign 10{sup 16} cm{sup -3}, electron temperature Almost-Equal-To 1.4 eV, velocity Almost-Equal-To 30 km/s, M Almost-Equal-To 14, ionization fraction Almost-Equal-To 0.96, diameter Almost-Equal-To 5 cm, and length Almost-Equal-To 20 cm. These values approach the range needed by the Plasma Liner Experiment, which is designed to use merging plasma jets to form imploding spherical plasma liners that can reach peak pressures of 0.1-1 Mbar at stagnation. As these jets propagate a distance of approximately 40 cm, the average density drops by one order of magnitude, which is at the very low end of the 8-160 times drop predicted by ideal hydrodynamic theory of a constant-M jet.

  5. High density plasmas and new diagnostics: An overview (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Celona, L., E-mail: celona@lns.infn.it; Gammino, S.; Mascali, D. [Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy)

    2016-02-15

    One of the limiting factors for the full understanding of Electron Cyclotron Resonance Ion Sources (ECRISs) fundamental mechanisms consists of few types of diagnostic tools so far available for such compact machines. Microwave-to-plasma coupling optimisation, new methods of density overboost provided by plasma wave generation, and magnetostatic field tailoring for generating a proper electron energy distribution function, suitable for optimal ion beams formation, require diagnostic tools spanning across the entire electromagnetic spectrum from microwave interferometry to X-ray spectroscopy; these methods are going to be implemented including high resolution and spatially resolved X-ray spectroscopy made by quasi-optical methods (pin-hole cameras). The ion confinement optimisation also requires a complete control of cold electrons displacement, which can be performed by optical emission spectroscopy. Several diagnostic tools have been recently developed at INFN-LNS, including “volume-integrated” X-ray spectroscopy in low energy domain (2-30 keV, by using silicon drift detectors) or high energy regime (>30 keV, by using high purity germanium detectors). For the direct detection of the spatially resolved spectral distribution of X-rays produced by the electronic motion, a “pin-hole camera” has been developed also taking profit from previous experiences in the ECRIS field. The paper will give an overview of INFN-LNS strategy in terms of new microwave-to-plasma coupling schemes and advanced diagnostics supporting the design of new ion sources and for optimizing the performances of the existing ones, with the goal of a microwave-absorption oriented design of future machines.

  6. High density plasmas and new diagnostics: An overview (invited).

    Science.gov (United States)

    Celona, L; Gammino, S; Mascali, D

    2016-02-01

    One of the limiting factors for the full understanding of Electron Cyclotron Resonance Ion Sources (ECRISs) fundamental mechanisms consists of few types of diagnostic tools so far available for such compact machines. Microwave-to-plasma coupling optimisation, new methods of density overboost provided by plasma wave generation, and magnetostatic field tailoring for generating a proper electron energy distribution function, suitable for optimal ion beams formation, require diagnostic tools spanning across the entire electromagnetic spectrum from microwave interferometry to X-ray spectroscopy; these methods are going to be implemented including high resolution and spatially resolved X-ray spectroscopy made by quasi-optical methods (pin-hole cameras). The ion confinement optimisation also requires a complete control of cold electrons displacement, which can be performed by optical emission spectroscopy. Several diagnostic tools have been recently developed at INFN-LNS, including "volume-integrated" X-ray spectroscopy in low energy domain (2-30 keV, by using silicon drift detectors) or high energy regime (>30 keV, by using high purity germanium detectors). For the direct detection of the spatially resolved spectral distribution of X-rays produced by the electronic motion, a "pin-hole camera" has been developed also taking profit from previous experiences in the ECRIS field. The paper will give an overview of INFN-LNS strategy in terms of new microwave-to-plasma coupling schemes and advanced diagnostics supporting the design of new ion sources and for optimizing the performances of the existing ones, with the goal of a microwave-absorption oriented design of future machines.

  7. Characteristics of temporal evolution of particle density and electron temperature in helicon discharge

    Science.gov (United States)

    Yang, Xiong; Cheng, Mousen; Guo, Dawei; Wang, Moge; Li, Xiaokang

    2017-10-01

    On the basis of considering electrochemical reactions and collision relations in detail, a direct numerical simulation model of a helicon plasma discharge with three-dimensional two-fluid equations was employed to study the characteristics of the temporal evolution of particle density and electron temperature. With the assumption of weak ionization, the Maxwell equations coupled with the plasma parameters were directly solved in the whole computational domain. All of the partial differential equations were solved by the finite element solver in COMSOL MultiphysicsTM with a fully coupled method. In this work, the numerical cases were calculated with an Ar working medium and a Shoji-type antenna. The numerical results indicate that there exist two distinct modes of temporal evolution of the electron and ground atom density, which can be explained by the ion pumping effect. The evolution of the electron temperature is controlled by two schemes: electromagnetic wave heating and particle collision cooling. The high RF power results in a high peak electron temperature while the high gas pressure leads to a low steady temperature. In addition, an OES experiment using nine Ar I lines was conducted using a modified CR model to verify the validity of the results by simulation, showing that the trends of temporal evolution of electron density and temperature are well consistent with the numerically simulated ones.

  8. Radial Density Profile in the SSX Plasma Wind Tunnel using a Double Langmuir Probe

    Science.gov (United States)

    Weinhold, D. L.; Flanagan, K.; Gray, T.; Brown, M. R.

    2011-10-01

    We present preliminary results from a moveable double Langmuir probe in the present plasma wind tunnel configuration of SSX. The probe is designed to measure radial profiles of electron density (ne) and electron temperature (Te) across the midplane with a 1 cm resolution. Line-averaged densities from He-Ne interferometry show densities of 1 - 5 ×1015 cm-3 . In addition to mean values, we will also present electrostatic fluctuations and correlations with magnetic field measurements. The double Langmuir probe also measures local Te. Line-averaged measurements from VUV spectroscopy indicate Te ~ 10 eV . The Langmuir probe stalk diameter measures 6 . 5 mm and tip spacing is 1 . 1 mm . The SSX plasma wind tunnel has dimensions L ≅ 1 m and R = 0 . 08 m . Plasma flow speeds are v >= 50 km / s . The cylindrical copper boundary and probe surfaces are baked and cleaned in a He glow discharge to maintain excellent vacuum and surface conditions. Electrostatic measurements during merging will be presented if available. Work supported by US DOE and CMSO.

  9. Ion Temperature-Measurements in Tokamak Plasmas by Rutherford Scattering

    NARCIS (Netherlands)

    Vanblokland, A. A. E.; Barbian, E. P.; Donne, A. J. H.; van der Grift, A. F.; Grimbergen, T. W. M.; Oyevaar, T.; Schüller, F. C.; Tammen, H. F.; Vanderven, H. W.; Vijverberg, T. F.; Dewinter, F. D. A.; Bertschinger, G.; Cosler, A.; Korten, M.

    1992-01-01

    A Rutherford scattering diagnostic has been applied at the TEXTOR tokamak to obtain spatially and temporally resolved information on the temperature of the bulk ions in the plasma. In the experimental setup, a helium atomic beam (30-keV, 12-mA equivalent current) passes vertically through the plasma

  10. Exact conditions on the temperature dependence of density functionals

    CERN Document Server

    Burke, Kieron; Grabowski, Paul E; Pribram-Jones, Aurora

    2015-01-01

    Universal exact conditions guided the construction of most ground-state density functional approximations in use today. We derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

  11. Exact conditions on the temperature dependence of density functionals

    Science.gov (United States)

    Burke, K.; Smith, J. C.; Grabowski, P. E.; Pribram-Jones, A.

    2016-05-01

    Universal exact conditions guided the construction of most ground-state density functional approximations in use today. We derive the relation between the entropy and Mermin free energy density functionals for thermal density functional theory. Both the entropy and sum of kinetic and electron-electron repulsion functionals are shown to be monotonically increasing with temperature, while the Mermin functional is concave downwards. Analogous relations are found for both exchange and correlation. The importance of these conditions is illustrated in two extremes: the Hubbard dimer and the uniform gas.

  12. Second topical conference on high-temperature plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Jahoda, F.C.; Freese, K.B. (comps.)

    1978-02-01

    This report contains the program and abstracts of papers presented at the Second American Physical Society Topical Conference on High Temperature Plasma Diagnostics, March 1-3, 1978, Santa Fe, New Mexico.

  13. Surface morphology and deuterium retention in tungsten exposed to high flux D plasma at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Y.Z. [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); De Temmerman, G. [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN Nieuwegein (Netherlands); ITER Organization, Route de Vinon-sur-Verdon-CS90046, 13067 St Paul Lez Durance Cedex (France); Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Xu, H.Y. [Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621907 (China); Li, C.; Fu, B.Q. [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, W., E-mail: liuw@mail.tsinghua.edu.cn [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-02-15

    Surface modifications and deuterium retention induced in tungsten by high fluxes (10{sup 24} m{sup −2} s{sup −1}) low energy (38 eV) deuterium ions were studied as a function of surface temperature. Blister formation was studied by scanning electron microscopy and electron backscatter diffraction, while deuterium retention was measured by thermal desorption spectroscopy. Blisters are observed on the surface exposed at different temperatures, ranging from 493 K to 1273 K. The blister density and D retention decrease with the increasing exposure temperature. The formation of blisters at high temperatures is attributed to the high flux of D plasma. At 943 K, with the increasing fluence, there is trend to the saturation of D retention and blister density. The defects caused by plasma exposure have an important effect on the D trapping and blistering behavior. The formation of blisters has a strong relationship with slipping system of tungsten.

  14. On the interaction between two fireballs in low-temperature plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dimitriu, D. G., E-mail: dimitriu@uaic.ro; Irimiciuc, S. A.; Popescu, S. [Faculty of Physics, “Alexandru Ioan Cuza” University, 11 Carol I Blvd., 700506 Iasi (Romania); Agop, M. [Department of Physics, “Gh. Asachi” Technical University, 59A Mangeron Blvd., 700050 Iasi (Romania); Ionita, C.; Schrittwieser, R. W. [Institute for Ion Physics and Applied Physics, University of Innsbruck, 25 Technikerstr., A-6020 Innsbruck (Austria)

    2015-11-15

    We report experimental results and theoretical modeling showing the interaction between two fireballs excited on two positively biased electrodes immersed in a low-temperature plasma. This interaction leads to a synchronized dynamics of the two fireballs, its frequency depending on the plasma density, the voltages applied on the electrodes, and the distance between the two electrodes. By considering that the plasma particles (electrons, ions, neutrals) move on fractal curves, a theoretical model describing the interaction between the two fireballs is developed. The results of the theoretical model were found to be in good agreement with the experimental results.

  15. Low Temperature Plasmas Generated and Sustained Indefinitely Using a Focused Microwave Beam

    Science.gov (United States)

    Reid, Remington; Hoff, Brad; Lepell, Paul; AFRL Team

    2016-10-01

    The Air Force Research Laboratory has constructed a device that can initiate a plasma discharge in a focused microwave beam and sustain it indefinitely. A 10 kW, 4.5 GHz beam is passed through a vacuum chamber outfitted with pressure windows that are transparent to 4.5 GHz radiation. The pressure windows are large enough in diameter to prevent any interactions between the beam and the metallic chamber. The entire experiment is housed inside an anechoic chamber to minimize reflections. This novel plasma source generates low temperature, low density plasmas that have no contact with the walls which minimizes contamination and sheath formation.

  16. Measurement of neutral gas temperature in a 13.56 MHz inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jayapalan, Kanesh K.; Chin, Oi Hoong [Plasma Technology Research Centre, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Measuring the temperature of neutrals in inductively coupled plasmas (ICP) is important as heating of neutral particles will influence plasma characteristics such as the spatial distributions of plasma density and electron temperature. Neutral gas temperatures were deduced using a non-invasive technique that combines gas actinometry, optical emission spectroscopy and simulation which is described here. Argon gas temperature in a 13.56 MHz ICP were found to fall within the range of 500 − 800 K for input power of 140 − 200 W and pressure of 0.05 − 0.2 mbar. Comparing spectrometers with 0.2 nm and 0.5 nm resolution, improved fitting sensitivity was observed for the 0.2 nm resolution.

  17. Photon Temperatures of Hard X-Ray Emission of LHCD Plasmas in HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    Jawad YOUNIS; WAN Baonian; CHEN Zhongyong; LIN Shiyao; SHI Yuejiang; SHAN Jiafang; LIU Fukun

    2008-01-01

    A detailed study of photon temperatures (Tph) of hard X-ray emission in lower hybrid current drive (LHCD) plasmas is presented.The photon temperature increases with the increase in plasma current and decreases with the increase in plasma density.In lower hybrid power and phase scanning experiments;there is no appreciable change in the photon temperature.The numerical results based on ray-tracing calculation and Fokker-Planck solver gives reasonable explanation for the experimental observation.Both experimental and numerical results reveal that the photon temperature depends mainly on global effects of the fast electron population,synergy between the fast electron and the loop voltage and the Coulomb slowing down.

  18. Charge-exchange recombination spectroscopy of the plasma ion temperature at the T-10 tokamak

    Science.gov (United States)

    Krupin, V. A.; Tugarinov, S. N.; Barsukov, A. G.; Dnestrovskij, A. Yu.; Klyuchnikov, L. A.; Korobov, K. V.; Krasnyanskii, S. A.; Naumenko, N. N.; Nemets, A. R.; Sushkov, A. V.; Tilinin, G. N.

    2013-08-01

    Charge-exchange recombination spectroscopy (CXRS) based on a diagnostic neutral beam has been developed at the T-10 tokamak. The diagnostics allows one to measure the ion temperature profile in the cross section of the plasma column. In T-10 experiments, the measurement technique was adjusted and the elements of the CXRS diagnostics for ITER were tested. The used spectroscopic equipment makes it possible to reliably determine the ion temperature from the Doppler broadening of impurity lines (helium, carbon), as well as of the spectral lines of the working gas. The profiles of the plasma ion temperature in deuterium and helium discharges were measured at different plasma currents and densities, including with the use of active Doppler measurements of lines of different elements. The validity and reliability of ion temperature measurements performed by means of the developed CXRS diagnostics are analyzed.

  19. Etching with atomic precision by using low electron temperature plasma

    Science.gov (United States)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Monroy, G. A.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2017-07-01

    There has been a steady increase in sub-nm precision requirement for many critical plasma etching processes in the semiconductor industry. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in conventional radio-frequency (RF) plasma processing systems, even during layer-by-layer or ‘atomic layer’ etch. To meet these increasingly stringent requirements, it is necessary to have an accurate control over ion energy and ion/radical composition during plasma processing. In this work, a new plasma etch system designed to facilitate atomic precision plasma processing is presented. An electron sheet beam parallel to the substrate surface is used to produce a plasma in this system. This plasma has a significantly lower electron temperature T e ~ 0.3 eV and ion energy E i  plasmas. Electron beam plasmas also have a higher ion-to-radical ratio compared to RF plasmas, so this plasma etch system employs an independent radical source for accurate control over relative ion and radical concentrations. A low frequency RF bias capability that allows control of ion energy in the 2-50 eV range is another important component of this plasma etch system. The results of etching of a variety of materials and structures in this low-electron temperature plasma system are presented in this study: (1) layer-by-layer etching of p-Si at E i ~ 25-50 eV using electrical and gas cycling is demonstrated; (2) continuous etching of epi-grown µ-Si in Cl2-based plasmas is performed, showing that surface damage can be minimized by keeping E i  etching at low E i.

  20. Physics of High Temperature, Dense Plasmas.

    Science.gov (United States)

    1984-01-01

    34Investigation of the High-Energy Acceleration Mode in the Coaxial Gun," Phys. Fluids, Suppl., S28, (1964). I. 9. Dattner, A. and Eninger J...34Studies of a Coaxial Plasma Gun," Phys. Fluids, Suppl., S41, (1964). II. 10. Wilcox, J. M., Pugh, E., Dattner, A. and Eninger , J., "Experimental Study of

  1. Simulating strongly coupled plasmas at low temperatures

    Science.gov (United States)

    Bussmann, M.; Schramm, U.; Habs, D.

    2006-10-01

    Realistic molecular dynamics (MD) simulations of the particle dynamics in strongly coupled plasmas require the computation of the mutual Coulomb-force for each pair of charged particles if a correct treatment of long range correlations is required. For plasmas with N > 104 particles this requires a tremendous number of computational steps which can only be addressed using efficient parallel algorithms adopted to modern super-computers. We present a new versatile MD simulation code which can simulate the non-relativistic mutual Coulomb-interaction of a large number of charged particles in arbitrary external field configurations. A demanding application is the simulation of the complete dynamics of in-trap stopping of highly charged ions in a laser cooled plasma of N = 105 24Mg+ ions. We demonstrate that the simulation is capable of delivering results on stopping times and plasma dynamics under realistic conditions. The results suggest that this stopping scheme can compete with in-trap electron cooling and might be an alternative approach for delivering ultra cold highly charged ions for future trap-based experiments aiming for precision mass measurements of stable and radioactive nuclei.

  2. Exploration of Plasma Jets Approach to High Energy Density Physics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chiping [Massachusetts Institute of Technology

    2013-08-26

    High-energy-density laboratory plasma (HEDLP) physics is an emerging, important area of research in plasma physics, nuclear physics, astrophysics, and particle acceleration. While the HEDLP regime occurs at extreme conditions which are often found naturally in space but not on the earth, it may be accessible by colliding high intensity plasmas such as high-energy-density plasma jets, plasmoids or compact toroids from plasma guns. The physics of plasma jets is investigated in the context of high energy density laboratory plasma research. This report summarizes results of theoretical and computational investigation of a plasma jet undergoing adiabatic compression and adiabatic expansion. A root-mean-squared (rms) envelope theory of plasma jets is developed. Comparison between theory and experiment is made. Good agreement between theory and experiment is found.

  3. Monte Carlo Sampling of Negative-temperature Plasma States

    Energy Technology Data Exchange (ETDEWEB)

    John A. Krommes; Sharadini Rath

    2002-07-19

    A Monte Carlo procedure is used to generate N-particle configurations compatible with two-temperature canonical equilibria in two dimensions, with particular attention to nonlinear plasma gyrokinetics. An unusual feature of the problem is the importance of a nontrivial probability density function R0(PHI), the probability of realizing a set {Phi} of Fourier amplitudes associated with an ensemble of uniformly distributed, independent particles. This quantity arises because the equilibrium distribution is specified in terms of {Phi}, whereas the sampling procedure naturally produces particles states gamma; {Phi} and gamma are related via a gyrokinetic Poisson equation, highly nonlinear in its dependence on gamma. Expansion and asymptotic methods are used to calculate R0(PHI) analytically; excellent agreement is found between the large-N asymptotic result and a direct numerical calculation. The algorithm is tested by successfully generating a variety of states of both positive and negative temperature, including ones in which either the longest- or shortest-wavelength modes are excited to relatively very large amplitudes.

  4. Friedberg-Lee model at finite temperature and density

    Science.gov (United States)

    Mao, Hong; Yao, Minjie; Zhao, Wei-Qin

    2008-06-01

    The Friedberg-Lee model is studied at finite temperature and density. By using the finite temperature field theory, the effective potential of the Friedberg-Lee model and the bag constant B(T) and B(T,μ) have been calculated at different temperatures and densities. It is shown that there is a critical temperature TC≃106.6 MeV when μ=0 MeV and a critical chemical potential μ≃223.1 MeV for fixing the temperature at T=50 MeV. We also calculate the soliton solutions of the Friedberg-Lee model at finite temperature and density. It turns out that when T⩽TC (or μ⩽μC), there is a bag constant B(T) [or B(T,μ)] and the soliton solutions are stable. However, when T>TC (or μ>μC) the bag constant B(T)=0 MeV [or B(T,μ)=0 MeV] and there is no soliton solution anymore, therefore, the confinement of quarks disappears quickly.

  5. The Friedberg-Lee model at finite temperature and density

    CERN Document Server

    Mao, Hong; Zhao, Wei-Qin

    2007-01-01

    The Friedberg-Lee model is studied at finite temperature and density. By using the finite temperature field theory, the effective potential of the Friedberg-Lee model and the bag constant $B(T)$ and $B(T,\\mu)$ have been calculated at different temperatures and densities. It is shown that there is a critical temperature $T_{C}\\simeq 106.6 \\mathrm{MeV}$ when $\\mu=0 \\mathrm{MeV}$ and a critical chemical potential $\\mu \\simeq 223.1 \\mathrm{MeV}$ for fixing the temperature at $T=50 \\mathrm{MeV}$. We also calculate the soliton solutions of the Friedberg-Lee model at finite temperature and density. It turns out that when $T\\leq T_{C}$ (or $\\mu \\leq \\mu_C$), there is a bag constant $B(T)$ (or $B(T,\\mu)$) and the soliton solutions are stable. However, when $T>T_{C}$ (or $\\mu>\\mu_C$) the bag constant $B(T)=0 \\mathrm{MeV}$ (or $B(T,\\mu)=0 \\mathrm{MeV}$) and there is no soliton solution anymore, therefore, the confinement of quarks disappears quickly.

  6. Molecular hydrogen emission as a density and temperature indicator

    Science.gov (United States)

    Wang, Xiang; Ferland, Gary J.; Baldwin, Jack A.; Loh, Edwin D.; Fabian, Andy C.; Williams, Robin

    2016-01-01

    Infrared observations have discovered a variety of objects, including filaments in the Crab Nebula and cool-core clusters of galaxies, where the 1-0 S(1) line is stronger than the infrared H I lines. A variety of processes could be responsible for this emission. Although many complete shock or PDR calculations of emission have been published, we know of no previous simple calculation that shows the emission spectrum and level populations of thermally excited low-density . We present a range of purely thermal collisional simulations, corresponding to constant gas kinetic temperature at different densities. We consider the cases where the collisions affecting H2 are predominantly with atomic or molecular hydrogen. The resulting level population (often called "excitation") diagrams show that excitation temperatures are sometimes lower than the gas kinetic temperature when the density is too low for the level populations to go to LTE. The atomic case goes to LTE at much lower densities than the molecular case due to larger collision rates. At low densities for the v=1 and 2 vibrational manifolds level populations are quasi-thermal, which could be misinterpreted as showing the gas is in LTE at high density. At low densities for the molecular case the level population diagrams are discontinuous between v=0 and 1 vibrational manifolds and between v=2, J=0, 1 and other higher J levels within the same vibrational manifold. These jumps could be used as density diagnostics. We show how much the H2 mass would be underestimated using the 1-0 S(1) line strength if the density is below that required for LTE. We give diagnostic diagrams showing level populations over a range of density and temperature. The density where the level populations are given by a Boltzmann distribution relative to the total molecular abundance (required to get the correct H2 mass), is shown for various cases. We discuss the implications of these results for the interpretation of H2 observations of the

  7. Density Fluctuations in the Yukawa One Component Plasma: An accurate model for the dynamical structure factor

    CERN Document Server

    Mithen, James P; Crowley, Basil J B; Gregori, Gianluca

    2011-01-01

    Using numerical simulations, we investigate the equilibrium dynamics of a single component fluid with Yukawa interaction potential. We show that, for a wide range of densities and temperatures, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. Since the Yukawa potential can describe the ion-ion interactions in a plasma, the model has significant applicability for both analyzing and interpreting the results of x-ray scattering data from high power lasers and fourth generation light sources.

  8. Dust-ion-acoustic Gardner double layers in a dusty plasma with two-temperature electrons

    Indian Academy of Sciences (India)

    M M Masud; I Tasnim; A A Mamun

    2015-01-01

    The properties of dust-ion-acoustic Gardner double layers (DIA GDLs) in an unmagnetized dusty plasma, whose constituents are negatively-charged stationary dust, inertial ions, and Boltzmann electrons of two distinct temperatures, are rigorously investigated by employing the reductive perturbation method: Gardner approach. The standard Gardner equation is derived, and its double layer (DL) solution is obtained. It has been shown that the properties of the DIA GDLs are significantly modified by some plasma parameters (viz. = e1/e2, e1 = e10/i0, and e2 = e20/i0, where e1 (e2) is the cold (hot) electron temperature, e10 (e20) is the cold (hot) electron number density at equilibrium, and i0 is the ion number density at equilibrium). The implications of our investigation in understanding the basic features of nonlinear electrostatic perturbations observed in many space plasma systems and laboratory devices are briefly discussed.

  9. Exploring the temporally resolved electron density evolution in EUV induced plasmas

    CERN Document Server

    van der Horst, R M; Beckers, J; Kroesen, G M W

    2014-01-01

    We measured for the first time the electron density in an Extreme Ultra-Violet induced plasma. This is achieved in a low-pressure argon plasma by using a method called microwave cavity resonance spectroscopy. Good agreement is found between the measured electron density at the end of the EUV pulse and a theoretical prediction. The plasma (i.e. electron density) decays in tens of microseconds.

  10. Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel

    OpenAIRE

    Sonu Sen; Meenu Asthana Varshney; Dinesh Varshney

    2014-01-01

    In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have num...

  11. Tokamak Plasmas : Electron temperature $(T_{e})$ measurements by Thomson scattering system

    Indian Academy of Sciences (India)

    R Rajesh; B Ramesh Kumar; S K Varshney; Manoj Kumar; Chhaya Chavda; Aruna Thakkar; N C Patel; Ajai Kumar; Aditya Team

    2000-11-01

    Thomson scattering technique based on high power laser has already proved its superoirity in measuring the electron temperature (e) and density (e) in fusion plasma devices like tokamaks. The method is a direct and unambiguous one, widely used for the localised and simultaneous measurements of the above parameters. In Thomson scattering experiment, the light scattered by the plasma electrons is used for the measurements. The plasma electron temperature is measured from the Doppler shifted scattered spectrum and density from the total scattered intensity. A single point Thomson scattering system involving a -switched ruby laser and PMTs as the detector is deployed in ADITYA tokamak to give the plasma electron parameters. The system is capable of providing the parameters e from 30 eV to 1 keV and e from 5 × 1012 cm-3-5× 1013 cm-3. The system is also able to give the parameter profile from the plasma center ( = 0 cm) to a vertical position of = +22 cm to = -14 cm, with a spatial resolution of 1 cm on shot to shot basis. This paper discusses the initial measurements of the plasma temperature from ADITYA.

  12. Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures.

    Science.gov (United States)

    Shen, Chen; Julius, Ethan F; Tyree, Timothy J; Dan, Ritwik; Moreau, David W; Thorne, Robert

    2017-06-28

    We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid cooling, to prepare the desired cryogenic temperature phase. Microliter to picoliter size drops are cooled by projection into a liquid nitrogen-argon (N2-Ar) mixture. The cryogenic temperature phase of the drop is evaluated using a visual assay that correlates with X-ray diffraction measurements. The density of the liquid N2-Ar mixture is adjusted by adding N2 or Ar until the drop becomes neutrally buoyant. The density of this mixture and thus of the drop is determined using a test mass and Archimedes principle. With appropriate care in drop preparation, management of gas above the liquid cryogen mixture to minimize icing, and regular mixing of the cryogenic mixture to prevent density stratification and phase separation, densities accurate to <0.5% of drops as small as 50 pL can readily be determined. Measurements on aqueous cryoprotectant mixtures provide insight into cryoprotectant action, and provide quantitative data to facilitate thermal contraction matching in biological cryopreservation.

  13. Interaction of Low Temperature Plasmas with Prokaryotic and Eukaryotic Cells

    Science.gov (United States)

    Laroussi, Mounir

    2008-10-01

    Due to promising possibilities for their use in medical applications such as wound healing, surface modification of biocompatible materials, and the sterilization of reusable heat-sensitive medical instruments, low temperature plasmas and plasma jets are making big strides as a technology that can potentially be used in medicine^1-2. At this stage of research, fundamental questions about the effects of plasma on prokaryotic and eukaryotic cells are still not completely answered. An in-depth understanding of the pathway whereby cold plasma interact with biological cells is necessary before real applications can emerge. In this paper, first an overview of non-equilibrium plasma sources (both low and high pressures) will be presented. Secondly, the effects of plasma on bacterial cells will be discussed. Here, the roles of the various plasma agents in the inactivation process will be outlined. In particular, the effects of UV and that of various reactive species (O3, O, OH) are highlighted. Thirdly, preliminary findings on the effects of plasma on few types of eukaryotic cells will be presented. How plasma affects eukaryotic cells, such as mammalian cells, is very important in applications where the viability/preservation of the cells could be an issue (such as in wound treatment). Another interesting aspect is the triggering of apoptosis (programmed cell death). Some investigators have claimed that plasma is able to induce apoptosis in some types of cancer cells. If successfully replicated, this can open up a novel method of cancer treatment. In this talk however, I will briefly focus more on the wound healing potential of cold plasmas. ^1E. A. Blakely, K. A. Bjornstad, J. E. Galvin, O. R. Monteiro, and I. G. Brown, ``Selective Neuron Growth on Ion Implanted and Plasma Deposited Surfaces'', In Proc. IEEE Int. Conf. Plasma Sci., (2002), p. 253. ^2M. Laroussi, ``Non-thermal Decontamination of Biological Media by Atmospheric Pressure Plasmas: Review, Analysis, and

  14. Understanding the dramatic role of anomalous dispersion on the measurement of electron densities in plasmas using interferometers

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J; Johnson, W R; Iglesias, C A; Scofield, J H

    2005-07-20

    For decades the electron density of plasmas has been measured using optical interferometers. With the availability of good X-ray laser sources in the last decade interferometers have been extended into the wavelength range 14-47 nm, which has enabled researchers to probe even higher density plasmas. The data analysis assumes the index of refraction is due only to the free electrons, which makes the index less than one. Recent interferometer experiments in Al plasmas observed plasmas with index of refraction greater than one at 14 nm and brought into question the validity of the usual formula for calculating the index. In this paper we show how the anomalous dispersion from bound electrons can dominate the free electron contribution to the index of refraction in many plasmas and make the index greater than one or enhance the contribution to the index such that one would greatly overestimate the density of the plasma using interferometers. Using a new average-atom code we calculate the index of refraction in many plasmas at different temperatures for photon energies from 0 to 100 eV and compare against calculations done with OPAL. We also present examples of other plasmas that may have index of refraction greater than one at X-ray laser energies. During the next decade X-ray free electron lasers and other X-ray sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.

  15. Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

    Science.gov (United States)

    Mattoo, S K; Singh, S K; Awasthi, L M; Singh, R; Kaw, P K

    2012-06-22

    We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius.

  16. Ion temperature evolution in an ultracold neutral plasma

    Energy Technology Data Exchange (ETDEWEB)

    McQuillen, P., E-mail: patrickmcquillen@rice.edu; Strickler, T.; Langin, T.; Killian, T. C. [Department of Physics and Astronomy, Rice University, Houston, Texas 77005 (United States)

    2015-03-15

    We study the long-time evolution of the ion temperature in an expanding ultracold neutral plasma using spatially resolved, laser-induced-fluorescence spectroscopy. Adiabatic cooling reduces the ion temperature by an order of magnitude during the plasma expansion, to temperatures as low as 0.2 K. Cooling is limited by heat exchange between ions and the much hotter electrons. We also present evidence for an additional heating mechanism and discuss possible sources. Data are described by a model of the plasma evolution, including the effects of ion-electron heat exchange. We show that for appropriate initial conditions, the degree of Coulomb coupling of ions in the plasma increases during expansion.

  17. Ion Temperature Evolution in an Ultracold Neutral Plasma

    CERN Document Server

    McQuillen, P; Langin, T; Killian, T C

    2015-01-01

    We study the long-time evolution of the ion temperature in an expanding ultracold neutral plasma using spatially resolved, laser-induced-fluorescence spectroscopy. Adiabatic cooling reduces the ion temperature by an order of magnitude during the plasma expansion, to temperatures as low as 0.2 K. Cooling is limited by heat exchange between ions and the much hotter electrons. We also present evidence for an additional heating mechanism and discuss possible sources. Data are described by a model of the plasma evolution, including the effects of ion-electron heat exchange. We show that for appropriate initial conditions, the degree of Coulomb coupling of ions in the plasma increases during expansion.

  18. An exospheric temperature model from CHAMP thermospheric density

    Science.gov (United States)

    Weng, Libin; Lei, Jiuhou; Sutton, Eric; Dou, Xiankang; Fang, Hanxian

    2017-02-01

    In this study, the effective exospheric temperature, named as T∞, derived from thermospheric densities measured by the CHAMP satellite during 2002-2010 was utilized to develop an exospheric temperature model (ETM) with the aid of the NRLMSISE-00 model. In the ETM, the temperature variations are characterized as a function of latitude, local time, season, and solar and geomagnetic activities. The ETM is validated by the independent GRACE measurements, and it is found that T∞ and thermospheric densities from the ETM are in better agreement with the GRACE data than those from the NRLMSISE-00 model. In addition, the ETM captures well the thermospheric equatorial anomaly feature, seasonal variation, and the hemispheric asymmetry in the thermosphere.

  19. The dust-acoustic mode in two-temperature electron plasmas with charging effects

    Indian Academy of Sciences (India)

    Zhong Xijuan; Chen Hui; Liu Nianhua; Liu Sanqiu

    2016-04-01

    Dust charging in an unmagnetized collisionless dusty plasma with two-temperature electrons was investigated based on the orbital motion limited theory, where the two-temperature electrons and ions are modelled by the Maxwellian distributions. Then by taking into account the effects of two-temperature electron and the associated charging fluctuations, the dispersion peculiarities of dust-acoustic waves are studied based on dust fluid dynamics. The present results show that the effect will introduce a dissipation on the mode, and the dispersion and the dissipation depend on the temperature ratio and number density ratio of hot and cold electrons.

  20. Plasma density characterization at SPARC-LAB through Stark broadening of Hydrogen spectral lines

    Energy Technology Data Exchange (ETDEWEB)

    Filippi, F., E-mail: francesco.filippi@roma1.infn.it [Dipartimento di Scienze di Base e Applicate per l' Ingegneria (SBAI), ‘Sapienza’ Università di Roma, Via A. Scarpa 14-16, 00161 Roma (Italy); INFN-Roma1, Piazzale Aldo Moro, 2 00161 Roma (Italy); Anania, M.P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Cianchi, A. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Di Giovenale, D.; Di Pirro, G.; Ferrario, M. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Mostacci, A.; Palumbo, L. [Dipartimento di Scienze di Base e Applicate per l' Ingegneria (SBAI), ‘Sapienza’ Università di Roma, Via A. Scarpa 14-16, 00161 Roma (Italy); INFN-Roma1, Piazzale Aldo Moro, 2 00161 Roma (Italy); Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Zigler, A. [Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2016-09-01

    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC-LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC-LAB is presented. - Highlights: • Stark broadening of Hydrogen lines has been measured to determine plasma density. • Plasma density diagnostic tool for plasma-based experiments at SPARC-LAB is presented. • Plasma density in tapered laser triggered ablative capillary discharge was measured. • Results of plasma density measurements in ablative capillaries are shown.

  1. Electron density measurement in gas discharge plasmas by optical and acoustic methods

    Science.gov (United States)

    Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-08-01

    Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

  2. Dyeing Performance of Soybean Fiber Treated with Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    WANG Li-ming; SHEN Yong; DING Ying; ZHANG Hui-fang

    2006-01-01

    The soybean fiber was treated with low temperature plasma and the dyeing performance of the treated soybean fiber was also researched. The results show that the speed of dyeing and the percentages of balance dyeing have a sharp increase after being treated. So the dyeing temperature and the dosage of acid can be reduced without damaging the bulk fiber structure.

  3. A laser-induced fluorescence measurement technique for obtaining neutral hydrogen densities in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Yao, X.Z.; Yang, T.F.; Chang-Diaz, F.R. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1995-09-01

    The resonance fluorescence of neutral hydrogen illuminated by {ital H}{sub {alpha}} radiation has been used as a technique for the spatially and temporally resolved density measurements of neutral hydrogen in high temperature plasmas, such as in the tokamak and magnetic mirror plasma fusion devices. The fluorescence signal, usually very weak and buried in the background of stray laser light and {ital H}{sub {alpha}} emission, is very difficult to extract and its measurements are inaccurate. This paper discusses the improvement of the signal extraction using two optical path laser-induced fluorescence (LIF) methods. One optical path carries the fluorescence signal and the background (the stray laser light and {ital H}{sub {alpha}} emission), whereas the other path carries only the background signal. By combining these two signals, a clean fluorescence signal can be isolated by subtracting out the background using a differential amplifier. The measurement is obtained instantaneously from these two signals which are taken simultaneously in one pulse rather than being extracted from two separate spectra taken in two sequential pulses (double pulses). This method, therefore, makes a significant improvement on the double pulse technique in terms of the accuracy of the measurement and the time resolution. Using this LIF technique the measurement of the neutral density profile in the exhaust of a tandem mirror plasma propulsion device is obtained and presented. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  4. Modelling of the plasma-MIG welding temperature field

    Institute of Scientific and Technical Information of China (English)

    Bai Yan; Gao Hongming; Wu Lin; Shi Lei

    2006-01-01

    A three-dimensional simulation model for the plasma-MIG welding process, which takes the interaction between the plasma arc and MIG arc into account, is presented and the quasi-steady temperature fields on the workpiece are calculated with the model. The 10 mm-5A06 aluminum alloy is welded and the temperature fields are measured with the thermoelectric couple. The simulation results and measured results show that the biggest deviation of peak temperature between them is below 20 ℃ , which indicates good coincidence between the simulation and measurement.

  5. Impact of plasma parameter on self-organization of electron temperature gradient driven turbulence

    Science.gov (United States)

    Kawai, C.; Idomura, Y.; Maeyama, S.; Ogawa, Y.

    2017-04-01

    Self-organization in the slab electron temperature gradient driven (ETG) turbulence is investigated based on gyrokinetic simulations and the Hasegawa-Mima (HM) equation. The scale and the anisotropy of self-organized turbulent structures vary depending on the Rhines scale and the characteristic scale given by the adiabatic response term in the HM equation. The former is determined by competition between the linear wave dispersion and the nonlinear turbulent cascade, while the latter is given as the scale, at which the turbulent cascade is impeded. These scales are controlled by plasma parameters such as the density and temperature gradient, and the temperature ratio of ion to electron. It is found that depending on the plasma parameters, the ETG turbulence shows either isotropic turbulence or zonal flows, which give significantly different transport levels. Although the modulational instability excites zonal modes regardless of the plasma parameters, the final turbulent structure is determined by the self-organization process.

  6. Detonability of white dwarf plasma: turbulence models at low densities

    Science.gov (United States)

    Fenn, D.; Plewa, T.

    2017-06-01

    We study the conditions required to produce self-sustained detonations in turbulent, carbon-oxygen degenerate plasma at low densities. We perform a series of three-dimensional hydrodynamic simulations of turbulence driven with various degrees of compressibility. The average conditions in the simulations are representative of models of merging binary white dwarfs. We find that material with very short ignition times is abundant in case turbulence is driven compressively. This material forms contiguous structures that persist over many ignition times, and that we identify as prospective detonation kernels. Detailed analysis of prospective kernels reveals that these objects are centrally condensed and their shape is characterized by low curvature, supportive of self-sustained detonations. The key characteristic of the newly proposed detonation mechanism is thus high degree of compressibility of turbulent drive. The simulated detonation kernels have sizes notably smaller than the spatial resolution of any white dwarf merger simulation performed to date. The resolution required to resolve kernels is 0.1 km. Our results indicate a high probability of detonations in such well-resolved simulations of carbon-oxygen white dwarf mergers. These simulations will likely produce detonations in systems of lower total mass, thus broadening the population of white dwarf binaries capable of producing Type Ia supernovae. Consequently, we expect a downward revision of the lower limit of the total merger mass that is capable of producing a prompt detonation. We review application of the new detonation mechanism to various explosion scenarios of single, Chandrasekhar-mass white dwarfs.

  7. Electronic ground state OH(X) radical in a low-temperature atmospheric pressure plasma jet

    Science.gov (United States)

    Fuh, Che A.; Clark, Shane M.; Wu, Wei; Wang, Chuji

    2016-10-01

    The wide applicability of atmospheric pressure plasma jets in biomedicine stems from the presence of reactive nitrogen and oxygen species generated in these plasma jets. Knowing the absolute concentration of these reactive species is of utmost importance as it is critical, along with the particle flux obtained from the plasma feed gas flow rate to ensure that the correct dosage is applied during applications. In this study, we investigate and report the ground state OH(X) number density acquired using cavity ringdown spectroscopy, along the propagation axis (z-axis) of a cold atmospheric pressure helium plasma plume. The jet was generated by a repetitively pulsed mono-polar square wave of duration 1 μs running at a frequency of 9.9 kHz. The voltage supplied was 6.5 kV with the helium flow rate fixed at 3.6 standard liters per minute. The rotational and vibrational temperatures are simulated from the second positive system of nitrogen, N 2(C3πu-B3πg) , with the rotational temperature being spatially constant at 300 K along the propagation axis of the atmospheric pressure plasma jet while the vibrational temperature is 3620 K at the beginning of the plume and is observed to decrease downstream. The OH(A) emission intensity obtained via optical emission spectroscopy was observed to decrease downstream of the plasma jet. The OH(X) number density along the propagation axis was initially 2.2 × 1013 molecules cm-3 before increasing to a peak value of 2.4 × 1013 molecules cm-3, from which the number density was observed to decrease to 2.2 × 1013 molecules cm-3 downstream of the plasma jet. The total OH(A, X) in the plasma jet remained relatively constant along the propagation axis of the plasma jet before falling off at the tip of the jet. The increase in vibrational temperature downstream and the simultaneous measurements of both the excited state OH(A) and the ground state OH(X) reported in this study provide insights into the formation and consumption of this

  8. Low-temperature plasma simulations with the LSP PIC code

    Science.gov (United States)

    Carlsson, Johan; Khrabrov, Alex; Kaganovich, Igor; Keating, David; Selezneva, Svetlana; Sommerer, Timothy

    2014-10-01

    The LSP (Large-Scale Plasma) PIC-MCC code has been used to simulate several low-temperature plasma configurations, including a gas switch for high-power AC/DC conversion, a glow discharge and a Hall thruster. Simulation results will be presented with an emphasis on code comparison and validation against experiment. High-voltage, direct-current (HVDC) power transmission is becoming more common as it can reduce construction costs and power losses. Solid-state power-electronics devices are presently used, but it has been proposed that gas switches could become a compact, less costly, alternative. A gas-switch conversion device would be based on a glow discharge, with a magnetically insulated cold cathode. Its operation is similar to that of a sputtering magnetron, but with much higher pressure (0.1 to 0.3 Torr) in order to achieve high current density. We have performed 1D (axial) and 2D (axial/radial) simulations of such a gas switch using LSP. The 1D results were compared with results from the EDIPIC code. To test and compare the collision models used by the LSP and EDIPIC codes in more detail, a validation exercise was performed for the cathode fall of a glow discharge. We will also present some 2D (radial/azimuthal) LSP simulations of a Hall thruster. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

  9. Diagnosis of Unmagnetized Plasma Electron Number Density and Electron-neutral Collision Frequency by Using Microwave

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhongcai; Shi Jiaming; Xu Bo

    2005-01-01

    The plasma diagnostic method using the transmission attenuation of microwaves at double frequencies (PDMUTAMDF) indicates that the frequency and the electron-neutral collision frequency of the plasma can be deduced by utilizing the transmission attenuation of microwaves at two neighboring frequencies in a non-magnetized plasma. Then the electron density can be obtained from the plasma frequency. The PDMUTAMDF is a simple method to diagnose the plasma indirectly. In this paper, the interaction of electromagnetic waves and the plasma is analyzed. Then, based on the attenuation and the phase shift of a microwave in the plasma, the principle of the PDMUTAMDF is presented. With the diagnostic method, the spatially mean electron density and electron collision frequency of the plasma can be obtained. This method is suitable for the elementary diagnosis of the atmospheric-pressure plasma.

  10. 4{omega} Thomson scattering probe for high-density plasma characterization at Titan

    Energy Technology Data Exchange (ETDEWEB)

    Ross, J. S.; Pollock, B. B. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Department of Mechanical and Aerospace Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0411 (United States); Kline, J. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Yang, S.; Henesian, M.; Weiland, T.; Price, D.; Glenzer, S. H. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

    2010-10-15

    In preparation for the upcoming experiments on the Titan laser at the Jupiter Laser Facility, a new Thomson scattering system has been designed and implemented. This system allows electron temperature and density measurements in a high-density regime (n{sub e}>10{sup 21} cm{sup -3}). A 263 nm probe has been demonstrated to produce a total energy of 15 J at 4{omega}(263 nm) in a 1 ns square pulse with a focal spot size of 100 {mu}m. This probe has been used for imaging Thomson scattering of the ion feature. The goal of this study is to investigate the heating of a preformed plasma by a short-pulse heater beam.

  11. Heat Transfer to a Particle Exposed to a Rarefied Plasma with a Great Temperature Gradient

    Institute of Scientific and Technical Information of China (English)

    XiChen; XinTao

    1993-01-01

    A kinetic-theory analysis is presented concerning the heat transfer from a rarefiled plasma to a spherical particle for the extreme case of free-molecule regime and thin phasma sheath.A great temperature gradient is assumed to exist in the plasma,and thus a non-Maxwellian velocity distribution function is employed for each of the gas species.Analytical results show that the existence of a temperature in employed for each of the gas species,Analytical results show that the existence of a temperature gradient in the plasma causes a nonuniform distribution of the local heat flux density on the sphere surface,while the total heat flux to the whole particle is independent of the temperature gradient.The nonuniformity of the local heat flux distributioln is small even for the case with a temperature gradient as great as 106 K/m,but it may significantly enhance the thermophoretic force on an evaporating particle,Heat transfer is mainly caused by atome at low gas temperatures with negligible ionization degree,while it can be attributed to ions and electrons at high plasma temperatures.

  12. Laser-induced plasma electron number density: Stark broadening method versus the Saha-Boltzmann equation

    Science.gov (United States)

    Arnab, Sarkar; Manjeet, Singh

    2017-02-01

    We report spectroscopic studies on plasma electron number density of laser-induced plasma produced by ns-Nd:YAG laser light pulses on an aluminum sample in air at atmospheric pressure. The effect of different laser energy and the effect of different laser wavelengths were compared. The experimentally observed line profiles of neutral aluminum have been used to extract the excitation temperature using the Boltzmann plot method, whereas the electron number density has been determined from the Stark broadened as well as using the Saha-Boltzmann equation (SBE). Each approach was also carried out by using the Al emission line and Mg emission lines. It was observed that the SBE method generated a little higher electron number density value than the Stark broadening method, but within the experimental uncertainty range. Comparisons of N e determined by the two methods show the presence of a linear relation which is independent of laser energy or laser wavelength. These results show the applicability of the SBE method for N e determination, especially when the system does not have any pure emission lines whose electron impact factor is known. Also use of Mg lines gives superior results than Al lines.

  13. Temperature and temporal dependence of neutral density transmittance standards

    Science.gov (United States)

    Koo, A.; Hamlin, J. D.

    2012-04-01

    The Schott series of NG glasses are frequently used to manufacture neutral density transmittance standards for validation of spectrophotometer systems as well as for comparisons of regular spectral transmittance scales. A study has been made of the temperature and temporal dependence of transmittance in these types of filters. The temperature dependence of transmittance is found to scale as -ln(T). The filter transmittance was found to vary significantly with time shortly after manufacture but appears to be stabilizing nine months after beginning measurements.

  14. High precision measurement of fuel density profiles in nuclear fusion plasmas

    NARCIS (Netherlands)

    Svensson, J.; von Hellermann, M.; Konig, R.

    2002-01-01

    This paper presents a method for deducing fuel density profiles of nuclear fusion plasmas in realtime during an experiment. A Multi Layer Perceptron (MLP) neural network is used to create a mapping between plasma radiation spectra and indirectly deduced hydrogen isotope densities. By combining diffe

  15. An enhancement of plasma density by neutral gas injection observed in SEPAC Spacelab-1 experiment

    Science.gov (United States)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Kubota, S.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.; Williamson, P. R.

    1985-01-01

    An enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented. When a plume of nitrogen gas was injected from the orbiter into space, a large amount of plasma was detected by an onboard plasma probe. The observed density often increased beyond the background plasma density and was strongly dependent on the attitude of the orbiter with respect to the velocity vector. This effect has been explained by a collisional interaction between the injected gas molecules and the ionospheric ions relatively drifting at the orbital speed.

  16. Neoclassical flows in deuterium-helium plasma density pedestals

    CERN Document Server

    Buller, Stefan; Newton, Sarah; Omotani, John

    2016-01-01

    In tokamak transport barriers, the radial scale of profile variations can be comparable to a typical ion orbit width, which makes the coupling of the distribution function across flux surfaces important in the collisional dynamics. We use the radially global steady-state neoclassical {\\delta}f code Perfect to calculate poloidal and toroidal flows, and radial fluxes, in the pedestal. In particular, we have studied the changes in these quantities as the plasma composition is changed from a deuterium bulk species with a helium impurity to a helium bulk with a deuterium impurity, under specific profile similarity assumptions. The poloidally resolved radial fluxes are not divergence-free in isolation in the presence of sharp radial profile variations, which leads to the appearance of poloidal return-flows. These flows exhibit a complex radial-poloidal structure that extends several orbit widths into the core and is sensitive to abrupt radial changes in the ion temperature gradient. We find that a sizable neoclassi...

  17. Generator of chemically active low-temperature plasma

    Science.gov (United States)

    Tyuftyaev, A. S.; Gadzhiev, M. Kh; Sargsyan, M. A.; Demirov, N. A.; Spector, N. O.

    2016-11-01

    A new generator of high enthalpy (H 0 > 40 kJ/g), chemically active nitrogen and air plasmas was designed and constructed. Main feature of the generator is an expanding channel of an output electrode; the generator belongs to the class of DC plasma torches with thermionic cathode with an efficiency of 80%. The generator ensures the formation of a slightly divergent plasma jet (2α = 12°) with a diameter of D = 10-12 mm, an electric arc maximum power of 20-50 kW, plasma forming gas flow rate 1.0-2.0 g/s, and the average plasma temperature at an outlet of 8000-11000 K.

  18. Temperature and density effects on the nucleon mass splitting

    CERN Document Server

    Christiansen, H R; Fanchiotti, H; Garc, C A

    1996-01-01

    The finite temperature and finite density dependence of the neu\\-tron-proton mass difference is analysed in a purely hadronic framework where the \\rho-\\omega mixing is crucial for this isospin symmetry breakdown. The problem is handled within Thermo Field Dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei.

  19. Temperature and density effects on the nucleon mass splitting

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, H.R.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A. [Departamento de Fisica, Universidad Nacional de La Plata C.C. 67, (1900) La Plata (Argentina)

    1996-04-01

    The finite temperature and finite density dependence of the neutron-proton mass difference is analyzed in a purely hadronic framework where the {rho}-{omega} mixing is crucial for this isospin symmetry breakdown. The problem is handled within thermofield dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei. {copyright} {ital 1996 The American Physical Society.}

  20. Reduced density matrix functional theory at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Baldsiefen, Tim

    2012-10-15

    Density functional theory (DFT) is highly successful in many fields of research. There are, however, areas in which its performance is rather limited. An important example is the description of thermodynamical variables of a quantum system in thermodynamical equilibrium. Although the finite-temperature version of DFT (FT-DFT) rests on a firm theoretical basis and is only one year younger than its brother, groundstate DFT, it has been successfully applied to only a few problems. Because FT-DFT, like DFT, is in principle exact, these shortcomings can be attributed to the difficulties of deriving valuable functionals for FT-DFT. In this thesis, we are going to present an alternative theoretical description of quantum systems in thermal equilibrium. It is based on the 1-reduced density matrix (1RDM) of the system, rather than on its density and will rather cumbersomly be called finite-temperature reduced density matrix functional theory (FT-RDMFT). Its zero-temperature counterpart (RDMFT) proved to be successful in several fields, formerly difficult to address via DFT. These fields include, for example, the calculation of dissociation energies or the calculation of the fundamental gap, also for Mott insulators. This success is mainly due to the fact that the 1RDM carries more directly accessible ''manybody'' information than the density alone, leading for example to an exact description of the kinetic energy functional. This sparks the hope that a description of thermodynamical systems employing the 1RDM via FT-RDMFT can yield an improvement over FT-DFT. Giving a short review of RDMFT and pointing out difficulties when describing spin-polarized systems initiates our work. We then lay the theoretical framework for FT-RDMFT by proving the required Hohenberg-Kohn-like theorems, investigating and determining the domain of FT-RDMFT functionals and by deriving several properties of the exact functional. Subsequently, we present a perturbative method to

  1. High Temperature Plasmas Theory and Mathematical Tools for Laser and Fusion Plasmas

    CERN Document Server

    Spatschek, Karl-Heinz

    2012-01-01

    Filling the gap for a treatment of the subject as an advanced course in theoretical physics with a huge potential for future applications, this monograph discusses aspects of these applications and provides theoretical methods and tools for their investigation. Throughout this coherent and up-to-date work the main emphasis is on classical plasmas at high-temperatures, drawing on the experienced author's specialist background. As such, it covers the key areas of magnetic fusion plasma, laser-plasma-interaction and astrophysical plasmas, while also including nonlinear waves and phenomena.

  2. Statistical mechanics of 'negative temperature' states. [for plasma

    Science.gov (United States)

    Montgomery, D.; Joyce, G.

    1974-01-01

    Consideration of the dynamics of a two-dimensional guiding center plasma, recently shown by Taylor and McNamara (1971) to be identical to the dynamics of the discrete vortex model of Onsager (1949). A semirigorous application of the methods of equilibrium statistical mechanics to the guiding center plasma (or equivalently, the line vortex system) is presented. An adaptation of the apparatus of the theory of probability is attempted, in the form given by Khinchin (1949) to obtain ensemble-average predictions for the states of the guiding center plasma. Interest focuses primarily on the regime in which the interaction energy is high enough to be above the Onsager 'negative temperature' threshold.

  3. Atmospheric Pressure Low Temperature Plasma System for Additive Manufacturing

    Science.gov (United States)

    Burnette, Matthew; Staack, David

    2016-09-01

    There is growing interest in using plasmas for additive manufacturing, however these methods use high temperature plasmas to melt the material. We have developed a novel technique of additive manufacturing using a low temperature dielectric barrier discharge (DBD) jet. The jet is attached to the head of a 3D printer to allow for precise control of the plasma's location. Various methods are employed to deposit the material, including using a vaporized precursor or depositing a liquid precursor directly onto the substrate or into the plasma via a nebulizer. Various materials can be deposited including metals (copper using copper (II) acetylacetonate), polymers (PMMA using the liquid monomer), and various hydrocarbon compounds (using alcohols or a 100% methane DBD jet). The rastering pattern for the 3D printer was modified for plasma deposition, since it was originally designed for thermoplastic extrusion. The design constraints for fill pattern selection for the plasma printer are influenced by substrate heating, deposition area, and precursor consumption. Depositions onto pressure and/or temperature sensitive substrates can be easily achieved. Deposition rates range up to 0.08 cm3/hr using tris(2-methoxyethoxy)(vinyl)silane, however optimization can still be done on the system to improve the deposition rate. For example higher concentration of precursor can be combined with faster motion and higher discharge powers to increase the deposition rate without overheating the substrate.

  4. 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.

  5. Combustion and Plasma Synthesis of High-Temperature Materials

    Science.gov (United States)

    Munir, Z. A.; Holt, J. B.

    1997-04-01

    KEYNOTE ADDRESS. Self-Propagating High-Temperature Synthesis: Twenty Years of Search and Findings (A. Merzhanov). SOLID-STATE COMBUSTION SYNTHESIS. Recent Progress in Combustion Synthesis of High-Performance Materials in Japan (M. Koizumi & Y. Miyamoto). Modeling and Numerical Computation of a Nonsteady SHS Process (A. Bayliss & B. Matkowsky). New Models of Quasiperiodic Burning in Combustion Synthesis (S. Margolis, et al.). Modeling of SHS Operations (V. Hlavacek, et al.). Combustion Theory for Sandwiches of Alloyable Materials (R. Armstrong & M. Koszykowski). Observations on the Combustion Reaction Between Thin Foils of Ni and Al (U. Anselmi-Tamburini & Z. Munir). Combustion Synthesis of Intermetallic Compounds (Y. Kaieda, et al.). Combustion Synthesis of Nickel Aluminides (B. Rabin, et al.). Self-Propagating High-Temperature Synthesis of NiTi Intermetallics (H. Yi & J. Moore). Shock-Induced Chemical Synthesis of Intermetallic Compounds (S. Work, et al.). Advanced Ceramics Via SHS (T. DeAngelis & D. Weiss). In-Situ Formation of SiC and SiC-C Blocked Solids by Self-Combustion Synthesis (S. Ikeda, et al.). Powder Purity and Morphology Effects in Combustion-Synthesis Reactions (L. Kecskes, et al.). Simultaneous Synthesis and Densification of Ceramic Components Under Gas Pressure by SHS (Y. Miyamoto & M. Koizumi). The Use of Self-Propagating High-Temperature Synthesis of High-Density Titanium Diboride (P. Zavitsanos, et al.). Metal--Ceramic Composite Pipes Produced by a Centrifugal-Thermit Process (O. Odawara). Simultaneous Combustion Synthesis and Densification of AIN (S. Dunmead, et al.). Fabrication of a Functionally Gradient Material by Using a Self-Propagating Reaction Process (N. Sata, et al.). Combustion Synthesis of Oxide-Carbide Composites (L. Wang, et al.). Heterogeneous Reaction Mechanisms in the Si-C System Under Conditions of Solid Combustion (R. Pampuch, et al.). Experimental Modeling of Particle-Particle Interactions During SHS of TiB2 -Al2O3 (K. Logan

  6. Plasma-Wall Interaction and Electron Temperature Saturation in Hall Thrusters

    Science.gov (United States)

    Smirnov, Artem

    2005-10-01

    Existing Hall thruster models predict that secondary electron emission from the channel walls is significant and that the near-wall sheaths are space charge saturated. The plasma-wall interaction and its dependence on the discharge voltage and channel width were studied through the measurements of the electron temperature, plasma potential, and plasma density in a 2 kW Hall thruster [1,2]. The experimental electron-wall collision frequency is computed using the measured plasma parameters. For high discharge voltages, the deduced electron-wall collision frequency is much lower than the theoretical value obtained for the space charge saturated sheath regime, but larger than the wall recombination frequency. The observed electron temperature saturation appears to be directly associated with a decrease of the Joule heating, rather than with the enhancement of the electron energy loss at the walls due to a strong secondary electron emission. The channel width is shown to have a more significant effect on the axial distribution of the plasma potential than the discharge voltage. 1. Y. Raitses, D. Staack, M. Keidar, and N.J. Fisch, Phys. Plasmas 12, 057104 (2005). 2. Y. Raitses, D. Staack, A. Smirnov, and N.J. Fisch, Phys. Plasmas 12, 073507 (2005).

  7. Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

    Science.gov (United States)

    Olsen, Jeppe; Madsen, Jens; Nielsen, Anders Henry; Rasmussen, Jens Juul; Naulin, Volker

    2016-04-01

    The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocity scaling, which is proportional to the ion acoustic speed times the square root of the filament particle density times the sum of the electron and ion temperature perturbations. Only for small blobs the cross field convection does not follow this scaling. The influence of finite Larmor radius effects on the cross-field blob convection is shown not to depend strongly on the dynamical ion temperature field. The blob dynamics of constant finite and dynamical ion temperature blobs is similar. When the blob size is on the order of 10 times the ion Larmor radius the blobs stay coherent and decelerate slowly compared to larger blobs which dissipate faster due to fragmentation and turbulent mixing.

  8. Electrical properties of bilayer graphene synthesized using surface wave microwave plasma techniques at low temperature

    Science.gov (United States)

    Yamada, Takatoshi; Kato, Hiromitsu; Okigawa, Yuki; Ishihara, Masatou; Hasegawa, Masataka

    2017-01-01

    Bilayer graphene was synthesized at low temperature using surface wave microwave plasma techniques where poly(methyl metacrylate) (PMMA) and methane (CH4) were used as carbon sources. Temperature-dependent Hall effect measurements were carried out in a helium atmosphere. Sheet resistance, sheet carrier density and mobility showed weak temperature dependence for graphene from PMMA, and the highest carrier mobility is 740 cm2 V-1 s-1. For graphene from CH4, tunneling of the domain boundary limited carrier transport. The difference in average domain size was determined by Raman signal maps. In addition, residuals of PMMA were detected on graphene from PMMA. The low sheet resistances of graphene synthesized at a temperature of 280 °C using plasma techniques were explained by the PMMA related residuals rather than the domain sizes.

  9. Nonperturbative Yukawa theory at finite density and temperature

    CERN Document Server

    Fraga, Eduardo S; Pinto, Marcus Benghi

    2009-01-01

    In-medium Yukawa theory is part of the thermodynamics of the Standard Model of particle physics and is one of the main building blocks of most effective field theories of fermionic systems. By computing its pressure we investigate the nonperturbative thermodynamics at finite temperature and density using the optimized perturbation theory (OPT) framework. Our calculations are valid for arbitrary fermion and scalar masses, temperature, chemical potential, and not restricted to weak coupling. The model is considered in the presence as well as in the absence of condensates. Comparison with nonperturbative results shows that second order perturbation theory (PT) fails in the first case but performs rather well when condensates are absent, even at high-temperature regimes.

  10. 13th TOPICAL CONFERENCE ON HIGH TEMPERATURE PLASMA DIAGNOSTICS SCIENTIFIC PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    C. BARNES

    2000-07-01

    Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. {omega}{sub pe} >> {Omega}{sub ce} in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition ({tau} > 2). Electron Bernstein waves (EBWs) are electrostatic waves which can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large K{sub i}. This talk reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub 0} {approx} 2 kG, {approx} 10{sup 13} cm{sup -3} and T{sub e} {approx} 10 - 200 eV. Results will be presented for both direct detection of EBWs and for mode-converted EBW emission. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode-converted EBW radiation temperature was found to be {le} T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe was employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance where the mode conversion of the EBWs is expected to occur. Changes in the mode conversion efficiency may explain the observation of mode-converted EBW radiation temperatures below T{sub e}. Initial results suggest EBW emission and EBW heating are viable concepts for plasmas where {omega}{sub pe} >> {Omega}{sub ce}.

  11. Correlation between density fluctuations and plasma gradients at the edge of the TORE SUPRA tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Devynck, P.; Garbet, X.; Laviron, C.; Payan, J.; Haas, J. de; Clairet, F.; Talvard, M. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Gervais, F.; Gresillon, D.; Hennequin, P.; Quemeneur, A.; Truc, A. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1993-12-31

    The ALTAIR diagnostic uses scattering on the plasma electrons with the help of an IR laser beam to obtain information on the density fluctuations. This diagnostic can simultaneously record fluctuations from two independent wave numbers. Two experiments are carried out: study of the density fluctuations during strong plasma heating that combined both low hybrid waves and ion cyclotron heating; density fluctuations associated to the tokamak gas-feed modulation. 6 figs., 5 refs.

  12. Thermodynamic properties and transport coefficients of two-temperature helium thermal plasmas

    Science.gov (United States)

    Guo, Xiaoxue; Murphy, Anthony B.; Li, Xingwen

    2017-03-01

    Helium thermal plasmas are in widespread use in arc welding and many other industrial applications. Simulation of these processes relies on accurate plasma property data, such as plasma composition, thermodynamic properties and transport coefficients. Departures from LTE (local thermodynamic equilibrium) generally occur in some regions of helium plasmas. In this paper, properties are calculated allowing for different values of the electron temperature, T e, and heavy-species temperature, T h, at atmospheric pressure from 300 K to 30 000 K. The plasma composition is first calculated using the mass action law, and the two-temperature thermodynamic properties are then derived. The viscosity, diffusion coefficients, electrical conductivity and thermal conductivity of the two-temperature helium thermal plasma are obtained using a recently-developed method that retains coupling between electrons and heavy species by including the electron–heavy-species collision term in the heavy-species Boltzmann equation. It is shown that the viscosity and the diffusion coefficients strongly depend on non-equilibrium ratio θ (θ ={{T}\\text{e}}/{{T}\\text{h}} ), through the plasma composition and the collision integrals. The electrical conductivity, which depends on the electron number density and ordinary diffusion coefficients, and the thermal conductivity have similar dependencies. The choice of definition of the Debye length is shown to affect the electrical conductivity significantly for θ  >  1. By comparing with literature data, it is shown that the coupling between electrons and heavy species has a significant influence on the electrical conductivity, but not on the viscosity. Plasma properties are tabulated in the supplementary data.

  13. Electron Cyclotron Resonance Heating of a High-Density Plasma

    DEFF Research Database (Denmark)

    Hansen, F. Ramskov

    1986-01-01

    Various schemes for electron cyclotron resonance heating of tokamak plasmas with the ratio of electron plasma frequency to electron cyclotron frequency, "»pe/^ce* larger than 1 on axis, are investigated. In particular, a mode conversion scheme is investigated using ordinary waves at the fundamental...

  14. Research of partition function on optical properties and temperature diagnosis of air plasma

    Science.gov (United States)

    Qiu, Dechuan; Gao, Guoqiang; Wei, Wenfu; Hu, Haixing; Li, Chunmao; Wu, Guangning

    2017-08-01

    The relationship between partition function, particle density, refractive index, and temperature for atmospheric plasma is calculated based on thermodynamics and chemical equilibrium. Taking into account the contribution of hydrogen-like levels to the atomic partition function, a compact method to calculate the atomic partition function is first used with the Eindhoven model to deduce the plasma's refractive index. Results calculated by the new approach and two other traditional simplified methods are compared and analyzed. For a better understanding on the temperature measurement accuracy deduced by different partition function disposal approaches, moiré deflectometry is employed as the experimental scheme to acquire the refractive index-position curve. Finally, applicability of different partition function disposal approaches are discussed, and results indicate that the optical properties deduced in this paper are well suited for the refractive index-based plasma diagnosis.

  15. PT Symmetry and QCD: Finite Temperature and Density

    Directory of Open Access Journals (Sweden)

    Michael C. Ogilvie

    2009-04-01

    Full Text Available The relevance of PT symmetry to quantum chromodynamics (QCD, the gauge theory of the strong interactions, is explored in the context of finite temperature and density. Two significant problems in QCD are studied: the sign problem of finite-density QCD, and the problem of confinement. It is proven that the effective action for heavy quarks at finite density is PT-symmetric. For the case of 1+1 dimensions, the PT-symmetric Hamiltonian, although not Hermitian, has real eigenvalues for a range of values of the chemical potential μ, solving the sign problem for this model. The effective action for heavy quarks is part of a potentially large class of generalized sine-Gordon models which are non-Hermitian but are PT-symmetric. Generalized sine-Gordon models also occur naturally in gauge theories in which magnetic monopoles lead to confinement. We explore gauge theories where monopoles cause confinement at arbitrarily high temperatures. Several different classes of monopole gases exist, with each class leading to different string tension scaling laws. For one class of monopole gas models, the PT-symmetric affine Toda field theory emerges naturally as the effective theory. This in turn leads to sine-law scaling for string tensions, a behavior consistent with lattice simulations.

  16. Time-resolved electron density and electron temperature measurements in nanosecond pulse discharges in helium

    Science.gov (United States)

    Roettgen, A.; Shkurenkov, I.; Simeni Simeni, M.; Petrishchev, V.; Adamovich, I. V.; Lempert, W. R.

    2016-10-01

    Thomson scattering is used to study temporal evolution of electron density and electron temperature in nanosecond pulse discharges in helium sustained in two different configurations, (i) diffuse filament discharge between two spherical electrodes, and (ii) surface discharge over plane quartz surface. In the diffuse filament discharge, the experimental results are compared with the predictions of a 2D plasma fluid model. Electron densities are put on an absolute scale using pure rotational Raman spectra in nitrogen, taken without the plasma, for calibration. In the diffuse filament discharge, electron density and electron temperature increase rapidly after breakdown, peaking at n e  ≈  3.5 · 1015 cm-3 and T e  ≈  4.0 eV. After the primary discharge pulse, both electron density and electron temperature decrease (to n e ~ 1014 cm-3 over ~1 µs and to T e ~ 0.5 eV over ~200 ns), with a brief transient rise produced by the secondary discharge pulse. At the present conditions, the dominant recombination mechanism is dissociative recombination of electrons with molecular ions, \\text{He}2+ . In the afterglow, the electron temperature does not relax to gas temperature, due to superelastic collisions. Electron energy distribution functions (EEDFs) inferred from the Thomson scattering spectra are nearly Maxwellian, which is expected at high ionization fractions, when the shape of EEDF is controlled primarily by electron-electron collisions. The kinetic model predictions agree well with the temporal trends detected in the experiment, although peak electron temperature and electron density are overpredicted. Heavy species temperature predicted during the discharge and the early afterglow remains low and does not exceed T  =  400 K, due to relatively slow quenching of metastable He* atoms in two-body and three-body processes. In the surface discharge, peak electron density and electron temperature are n e  ≈  3 · 1014 cm3 and T e

  17. Spatial and Temporal Investigations of Laser Ablation Plasma Plume Density and Composition

    Science.gov (United States)

    Iratcabal, Jeremy; Bach, Bernhard; Beatty, Cuyler; Dutra, Eric; Darling, Timothy; Wiewior, Piotr; Covington, Aaron

    2016-10-01

    Laser ablation of solid targets with laser intensities of the order of 108-1011 W/cm2 provides a rich platform for investigating the density and composition of coexisting molecular, atomic, and ion species in the resulting plasma plume. Experiments measuring the spatial- and temporal-evolution of laser ablation plumes have been performed to simultaneously characterize the multiple parameters related to the energy and momentum partitioning of the incident laser energy as the ablation process occurs. The temperature, density, and relative populations of different molecular, atomic, and ion species can be determined by the simultaneous measurement of optical and charged particle spectroscopy, fast imaging cameras, and optical interferometric diagnostics. Additionally, background gas pressure, density, and species were carefully varied. A comparison of density measurements obtained with multiple interferometric, spectroscopic, and fast imaging diagnostics for a carbon ablation plume expanding into vacuum and into background gases with different Reynolds numbers will be presented. Atomic, molecular, and ion species population evolution will be presented as measured with optical and charged particle spectroscopy. This work was supported by the U.S. DOE NNSA Cooperative Agreement No. DE-NA0002075 and National Securities Technologies, LLC under Contract No. DE-AC52-06NA25946/subcontract No. 165819.

  18. Multifield measurement of magnetic fluctuation-induced particle flux in a high-temperature toroidal plasma

    Science.gov (United States)

    Lin, L.; Ding, W. X.; Brower, D. L.

    2016-12-01

    Magnetic fluctuation-induced particle transport is explored in the high-temperature, high-beta interior of the Madison symmetric torus (MST) reversed-field pinch by performing a multifield measurement of the correlated product of magnetic and density fluctuations associated with global resistive tearing modes. Local density fluctuations are obtained by inverting the line-integrated interferometry data after resolving the mode helicity through correlation techniques. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of Faraday-effect polarimetry measurements. Reconstructed 2D images of density and current density perturbations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved. The convective magnetic fluctuation-induced particle flux profile is measured for both standard and high-performance plasmas in MST with tokamak-like confinement, showing large reduction in the flux during improved confinement.

  19. Effect of sintering on the relative density of Cr-coated diamond/Cu composites prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    Wei Cui; Hui Xu; Jian-hao Chen; Shu-bin Ren; Xin-bo He; Xuan-hui Qu

    2016-01-01

    Cr-coated diamond/Cu composites were prepared by spark plasma sintering. The effects of sintering pressure, sintering tempera-ture, sintering duration, and Cu powder particle size on the relative density and thermal conductivity of the composites were investigated in this paper. The influence of these parameters on the properties and microstructures of the composites was also discussed. The results show that the relative density of Cr-coated diamond/Cu reaches ~100% when the composite is gradually compressed to 30 MPa during the heating process. The densification temperature increases from 880 to 915°C when the diamond content is increased from 45vol% to 60vol%. The densification temperature does not increase further when the content reaches 65vol%. Cu powder particles in larger size are beneficial for in-creasing the relative density of the composite.

  20. Fitting of the Thomson scattering density and temperature profiles on the COMPASS tokamak

    Science.gov (United States)

    Stefanikova, E.; Peterka, M.; Bohm, P.; Bilkova, P.; Aftanas, M.; Sos, M.; Urban, J.; Hron, M.; Panek, R.

    2016-11-01

    A new technique for fitting the full radial profiles of electron density and temperature obtained by the Thomson scattering diagnostic in H-mode discharges on the COMPASS tokamak is described. The technique combines the conventionally used modified hyperbolic tangent function for the edge transport barrier (pedestal) fitting and a modification of a Gaussian function for fitting the core plasma. Low number of parameters of this combined function and their straightforward interpretability and controllability provide a robust method for obtaining physically reasonable profile fits. Deconvolution with the diagnostic instrument function is applied on the profile fit, taking into account the dependence on the actual magnetic configuration.

  1. Low density lipoproteins as circulating fast temperature sensors.

    Directory of Open Access Journals (Sweden)

    Ruth Prassl

    Full Text Available BACKGROUND: The potential physiological significance of the nanophase transition of neutral lipids in the core of low density lipoprotein (LDL particles is dependent on whether the rate is fast enough to integrate small (+/-2 degrees C temperature changes in the blood circulation. METHODOLOGY/PRINCIPAL FINDINGS: Using sub-second, time-resolved small-angle X-ray scattering technology with synchrotron radiation, we have monitored the dynamics of structural changes within LDL, which were triggered by temperature-jumps and -drops, respectively. Our findings reveal that the melting transition is complete within less than 10 milliseconds. The freezing transition proceeds slowly with a half-time of approximately two seconds. Thus, the time period over which LDL particles reside in cooler regions of the body readily facilitates structural reorientation of the apolar core lipids. CONCLUSIONS/SIGNIFICANCE: Low density lipoproteins, the biological nanoparticles responsible for the transport of cholesterol in blood, are shown to act as intrinsic nano-thermometers, which can follow the periodic temperature changes during blood circulation. Our results demonstrate that the lipid core in LDL changes from a liquid crystalline to an oily state within fractions of seconds. This may, through the coupling to the protein structure of LDL, have important repercussions on current theories of the role of LDL in the pathogenesis of atherosclerosis.

  2. Neutrino Dispersion Relations at Finite Temperature and Density in the Left-Right Symmetric Model

    CERN Document Server

    Villalba-Pardo, F D

    2010-01-01

    In the framework of the Left-Right Symmetric Model, where left-handed neutrinos are massive via the see-saw mechanism, we determine the effects of temperature and density in the dispersion relations for neutrinos, considering that there exists an excess of leptons over antileptons in the plasma. To achieve this we first calculate the dispersion relations at finite temperature and density, computing the neutrino self-energy at one loop order in perturbation theory, obtaining a fully analytic expression for this self-energy even in the fully broken symmetry case by using the Mellin summation technique. From the dispersion relation found from the self energy we obtain the thermal effective mass for neutrinos at high temperature limit. This result allow us to establish the effect of finite temperature and density for neutrino oscillations in thermal and dense media for this framework. We can do it if we take into account that the oscillation patterns depend explicitly on neutrino masses. As a result, a generaliza...

  3. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  4. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Science.gov (United States)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  5. Study on low temperature plasma driven permeation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs.

  6. Plasma-nitriding of tantalum at relatively low temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Deyuan; LIN Qin; ZHAO Haomin; FEI Qinyong; GENG Man

    2004-01-01

    The combined quadratic orthogonal regression method of experiment design was employed to explore the effects of process parameters of plasma nitriding of tantalum such as total pressure, temperature and original hydrogen molar fraction on the hardness, roughness and structure of nitriding surfaces. The regression equations of hardness, roughness and structure were given according to the results of regression and statistic analysis. And the diffusion activation energy of nitrogen in tantalum on plasma nitriding conditions was calculated according to the experimental data of hardness of plasma-nitriding of tantalum vs time and temperature. The diffusion activation energy calculated belongs to (155.49 + 10.51)kJ/mol (783-983 K).

  7. Comparison of surface vacuum ultraviolet emissions with resonance level number densities. I. Argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Boffard, John B., E-mail: jboffard@wisc.edu; Lin, Chun C. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Culver, Cody [Materials Science Program, University of Wisconsin, Madison, WI 53706 (United States); Wang, Shicong; Wendt, Amy E. [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI 53706 (United States); Radovanov, Svetlana; Persing, Harold [Varian Semiconductor Equipment, Applied Materials Inc., Gloucester, MA 01939 (United States)

    2014-03-15

    Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. The highly energetic photons can induce surface damage by driving surface reactions, disordering surface regions, and affecting bonds in the bulk material. In argon plasmas, the VUV emissions are due to the decay of the 1s{sub 4} and 1s{sub 2} principal resonance levels with emission wavelengths of 104.8 and 106.7 nm, respectively. The authors have measured the number densities of atoms in the two resonance levels using both white light optical absorption spectroscopy and radiation-trapping induced changes in the 3p{sup 5}4p→3p{sup 5}4s branching fractions measured via visible/near-infrared optical emission spectroscopy in an argon inductively coupled plasma as a function of both pressure and power. An emission model that takes into account radiation trapping was used to calculate the VUV emission rate. The model results were compared to experimental measurements made with a National Institute of Standards and Technology-calibrated VUV photodiode. The photodiode and model results are in generally good accord and reveal a strong dependence on the neutral gas temperature.

  8. Production of CW High-Density Non-Equilibrium Plasma in the Atmosphere Using Microgap Discharge Excited by Microwave

    Science.gov (United States)

    Kono, Akihiro; Sugiyama, Tomohiko; Goto, Toshio; Furuhashi, Hideo; Uchida, Yoshiyuki

    2001-03-01

    A new technique for cw production of high-pressure, high-density, non-equilibrium plasma is presented. Using microwave excitation at 2.45 GHz, a stable atmospheric glow discharge was sustained between two knife-edge electrodes, having a length of 10 mm and facing each other across a ˜100 μm microgap. Laser Thomson scattering diagnostics indicates that the plasma density in the microgap is as high as 1.6× 1015 cm-3 at a microwave power of 100 W. The optical emission of the N2 second positive band indicates that the gas temperature in the microgap is 1800 K, much lower than the electron temperature.

  9. The influence of plasma density decreasement by pre-pulse on the laser wakefield acceleration

    Directory of Open Access Journals (Sweden)

    Ke-Gong Dong

    2011-12-01

    Full Text Available In the laser wakefield acceleration, the generation of electron beam is very sensitive to the plasma density. Not only the laser-wakefield interaction, but also the electron trapping and acceleration would be effected by the plasma density. However, the plasma density could be changed in the experiment by different reasons, which will result in the mismatch of parameters arranged initially. Forward Raman scattering spectrum demonstrated that the interaction density was decreased obviously in the experiment, which was verified by the pre-pulse conditions and two-dimensional particle-in-cell simulations. It was demonstrated that the plasma density was very important on the self-evolutions and energy coupling of laser pulse and wakefield, and eventually the energy spectrum of electron beam.

  10. Manipulation of laser-generated energetic proton spectra in near critical density plasma

    Science.gov (United States)

    Palmer, Charlotte A. J.; Dover, Nicholas P.; Pogorelsky, Igor; Streeter, Matthew J. V.; Najmudin, Zulfikar

    2015-01-01

    We present simulations that demonstrate the production of quasi-monoenergetic proton bunches from the interaction of a CO2 laser pulse train with a near-critical density hydrogen plasma. The multi-pulse structure of the laser leads to a steepening of the plasma density gradient, which the simulations show is necessary for the formation of narrow-energy spread proton bunches. Laser interactions with a long, front surface, scale-length (>> c/ωp ) plasma, with linear density gradient, were observed to generate proton beams with a higher maximum energy, but a much broader spectrum compared to step-like density profiles. In the step-like cases, a peak in the proton energy spectra was formed and seen to scale linearly with the ratio of laser intensity to plasma density.

  11. Electron temperature and density probe for small aeronomy satellites

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, K.-I. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan (China); International Center for Space Weather Study and education, Kyushu University, Fukuoka (Japan); Hsu, Y. W.; Jiang, G. S.; Chen, W. H.; Liu, W. T. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Cheng, C. Z.; Fang, H. K. [Plasma and Space Science Center, National Cheng Kung University, Tainan, Taiwan (China); Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan, Taiwan (China)

    2015-08-15

    A compact and low power consumption instrument for measuring the electron density and temperature in the ionosphere has been developed by modifying the previously developed Electron Temperature Probe (ETP). A circuit block which controls frequency of the sinusoidal signal is added to the ETP so that the instrument can measure both T{sub e} in low frequency mode and N{sub e} in high frequency mode from the floating potential shift of the electrode. The floating potential shift shows a minimum at the upper hybrid resonance frequency (f{sub UHR}). The instrument which is named “TeNeP” can be used for tiny satellites which do not have enough conductive surface area for conventional DC Langmuir probe measurements. The instrument also eliminates the serious problems associated with the contamination of satellite surface as well as the sensor electrode.

  12. Electron temperature and density probe for small aeronomy satellites

    Science.gov (United States)

    Oyama, K.-I.; Hsu, Y. W.; Jiang, G. S.; Chen, W. H.; Cheng, C. Z.; Fang, H. K.; Liu, W. T.

    2015-08-01

    A compact and low power consumption instrument for measuring the electron density and temperature in the ionosphere has been developed by modifying the previously developed Electron Temperature Probe (ETP). A circuit block which controls frequency of the sinusoidal signal is added to the ETP so that the instrument can measure both Te in low frequency mode and Ne in high frequency mode from the floating potential shift of the electrode. The floating potential shift shows a minimum at the upper hybrid resonance frequency (fUHR). The instrument which is named "TeNeP" can be used for tiny satellites which do not have enough conductive surface area for conventional DC Langmuir probe measurements. The instrument also eliminates the serious problems associated with the contamination of satellite surface as well as the sensor electrode.

  13. Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    H. Park; E. Mazzucato; T. Munsat; C.W. Domier; M. Johnson; N.C. Luhmann, Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

    2004-05-07

    Diagnostic systems for fluctuation measurements in plasmas have, of necessity, evolved from simple 1-D systems to multi-dimensional systems due to the complexity of the MHD and turbulence physics of plasmas illustrated by advanced numerical simulations. Using the recent significant advancements in millimeter wave imaging technology, Microwave Imaging Reflectometry (MIR) and Electron Cyclotron Emission Imaging (ECEI), simultaneously measuring density and temperature fluctuations, are developed for TEXTOR. The MIR system was installed on TEXTOR and the first experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The new 2-D ECE Imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured a true 2-D images of Te fluctuations of m=1 oscillation (''sawteeth'') near the q {approx} 1 surface for the first time.

  14. Dyson-Schwinger Equation Density, Temperature and Continuum Strong QCD

    CERN Document Server

    Roberts, C D

    2000-01-01

    Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions; and the transition to, and properties of, a quark gluon plasma. We provide a contemporary perspective, couched primarily in terms of the Dyson-Schwinger equations but also making comparisons with other approaches and models. Our discourse provides a practitioners' guide to features of the Dyson-Schwinger equations [such as confinement and dynamical chiral symmetry breaking] and canvasses phenomenological applications to light meson and baryon properties in cold, sparse QCD. These provide the foundation for an extension to hot, dense QCD, which is probed via the introduction of the intensive thermodynamic variables: chemical potential and temperature. We describe order parameters whose evolution signals deconfinement and chiral symmetry restoration, and chronicle their use in demarcating the quark gluon...

  15. High power densities from high-temperature material interactions

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs) offer important and unique advantages in terrestrial and space energy processing. And they are well suited to serve together synergistically. TEC and MFHPs operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: high-temperature material effects determine the level and lifetime of performance. Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs - and point to significant improvements with anticipated technological gains.

  16. Survival of charged rho condensation at high temperature and density

    CERN Document Server

    Liu, Hao; Huang, Mei

    2015-01-01

    The charged vector $\\rho$ mesons in the presence of external magnetic fields at finite temperature $T$ and chemical potential $\\mu$ have been investigated in the framework of the Nambu--Jona-Lasinio model. We compute the masses of charged $\\rho$ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential. The self-energy of the $\\rho$ meson contains the quark-loop contribution, i.e. the leading order contribution in $1/N_c$ expansion. The charged $\\rho$ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field $eB_c$, which means that the charged vector meson condensation, i.e. the electromagnetic superconductor can be induced above the critical magnetic field. Surprisingly, it is found that the charged $\\rho$ condensation can even survive at high temperature and density. At zero temperature, the critical magnetic field just increases slightly with the chemical potential, which indicates that the charged $\\rho$ condensatio...

  17. Numerical simulation of temperature and velocity fields in plasma spray

    Institute of Scientific and Technical Information of China (English)

    FAN Qun-bo; WANG Lu; WANG Fu-chi

    2007-01-01

    Based on the turbulence jet model, with respect to Ar-He mixture plasma gas injecting to ambient atmosphere, the temperature filed and velocity field under typical working conditions were investigated. Given the conditions of I=900 A, FAr=1.98 m3/h, FHe=0.85 m3/h, it is found that both the temperature and the velocity undergo a plateau region near the nozzle exit (0-10 mm) at the very first stage, then decrease abruptly from initial 13 543 K and 778.2 m/s to 4 000 K and 260.0 m/s, and finally decrease slowly again. Meanwhile, the radial temperature and radial velocity change relatively slow. The inner mechanism for such phenomena is due to the complex violent interaction between the high-temperature and high-velocity turbulent plasma jet and the ambient atmosphere. Compared with traditional methods, the initial working conditions can be directly related to the temperature and velocity fields of the plasma jet by deriving basic boundary conditions.

  18. Three temperature plasma shock solutions with gray radiation diffusion

    CERN Document Server

    Johnson, Bryan M

    2016-01-01

    The effects of radiation on the structure of shocks in a fully-ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray-diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron-ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and co...

  19. Ion Density Distribution in an Inductively Coupled Plasma Chamber

    Institute of Scientific and Technical Information of China (English)

    陈俊芳; 赵文锋; 吴先球; 樊双莉; 符斯列

    2004-01-01

    The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa,27 Pa and 53 Pa in the reaction chamber, different radio-frequency powers and different positions.The result indicates that the ion density decreases as the pressure increases, and increases as the power decreases. The ion density of axial position z = 0 achieves 5.8×10 10 on the center of coil under the power of 200 w and pressure of 9 Pa in the reaction chamber.

  20. Binary Collision Density in a Non-Ideal Gas as a Function of Particle Density, Collision Diameter, and Temperature

    Science.gov (United States)

    Mohazzabi, Pirooz

    2017-09-01

    Using molecular dynamics simulations, binary collision density in a dense non-ideal gas with Lennard-Jones interactions is investigated. It is shown that the functional form of the dependence of collision density on particle density and collision diameter remains the same as that for an ideal gas. The temperature dependence of the collision density, however, has a very different form at low temperatures, where it decreases as temperature increases. But at higher temperatures the functional form becomes the same as that for an ideal gas.

  1. Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency

    Science.gov (United States)

    Hazeltine, R. D.; Stark, David J.; Bhattacharjee, Chinmoy; Arefiev, Alexey V.; Toncian, Toma; Mahajan, S. M.

    2015-11-01

    3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. We consider here the simplest problem: the propagation of a low amplitude pulse through a preformed relativistically hot anisotropic electron plasma to explore its intrinsic dielectric properties. We find that: 1) the critical density for propagation depends strongly on the pulse polarization, 2) two plasmas with the same density and average energy per electron can exhibit profoundly different responses to electromagnetic pulses, 3) the anisotropy-driven Weibel instability develops as expected; the timescales of the growth and back reaction (on anisotropy), however, are long enough that sufficient anisotropy persists for the entire duration of the simulation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization. This work was supported by the U.S. DOE Contract Nos. DE-FG02-04ER54742 and DE-AC05-06OR23100 (D. J. S.) and NNSA Contract No. DE-FC52-08NA28512.

  2. Pair correlation functions of strongly coupled two-temperature plasma

    Science.gov (United States)

    Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.

    2017-09-01

    Using molecular dynamics simulations, we perform the first direct tests of three proposed models for the pair correlation functions of strongly coupled plasmas with species of unequal temperature. The models are all extensions of the Ornstein-Zernike/hypernetted-chain theory used to good success for equilibrium plasmas. Each theory is evaluated at several coupling strengths, temperature ratios, and mass ratios for a model plasma in which the electrons are positively charged. We show that the model proposed by Seuferling et al. [Phys. Rev. A 40, 323 (1989)] agrees well with molecular dynamics over a wide range of mass and temperature ratios, as well as over a range of coupling strength similar to that of the equilibrium hypernetted-chain (HNC) theory. The SVT model also correctly predicts the strength of interspecies correlations and exhibits physically reasonable long-wavelength limits of the static structure factors. Comparisons of the SVT model with the Yukawa one-component plasma (YOCP) model are used to show that ion-ion pair correlations are well described by the YOCP model up to Γe≈1 , beyond which it rapidly breaks down.

  3. The density and velocity of plasma bullets propagating along one dielectric tube

    Directory of Open Access Journals (Sweden)

    Longfei Ji

    2015-08-01

    Full Text Available This study shows that the propagation of plasma bullets along one dielectric tube is strongly affected by many discharge parameters, such as the waveform of applied voltage (AC or pulsed DC, peak voltage, He flow rate, and the frequency of AC voltage. Analysis indicates that the density and velocity of plasma bullets are mainly determined by the electric field at the front of plasma bullets. These discharge parameters may significantly influence the distribution of plasma potential along the tube, thus control the electric field at the front of plasma bullets and their propagation. An increase in the pulsed DC voltage with its rise time of <40-50 ns can lead to an obvious improvement in the electric field at the front of plasma bullets, resulting in generation of a plasma in the high density gas and a fast propagation of plasma bullets. He flowing through the tube can contribute to the surface diffusion of charged species, and greatly increase the electric field at the front of plasma bullets. During the propagation of plasma bullets, their density is decreased due to the surface recombination of charged species, such as electrons and ions.

  4. Electromagnetic radiation generated by arcing in low density plasma

    Science.gov (United States)

    Vayner, Boris V.; Ferguson, Dale C.; Snyder, David B.; Doreswamy, C. V.

    1996-01-01

    An unavoidable step in the process of space exploration is to use high-power, very large spacecraft launched into Earth orbit. Obviously, the spacecraft will need powerful energy sources. Previous experience has shown that electrical discharges occur on the surfaces of a high-voltage array, and these discharges (arcs) are undesirable in many respects. Moreover, any high voltage conductor will interact with the surrounding plasma, and that interaction may result in electrical discharges between the conductor and plasma (or between two conductors with different potentials, for example, during docking and extravehicular activity). One very important aspect is the generation of electromagnetic radiation by arcing. To prevent the negative influence of electromagnetic noise on the operation of spacecraft systems, it seems necessary to determine the spectra and absolute levels of the radiation, and to determine limitations on the solar array bias voltage that depend on the parameters of LEO plasma and the technical requirements of the spacecraft equipment. This report describes the results of an experimental study and computer simulation of the electromagnetic radiation generated by arcing on spacecraft surfaces. A large set of high quality data was obtained during the Solar Array Module Plasma Interaction Experiment (SAMPIE, flight STS-62) and ground test. These data include the amplitudes of current, pulse forms, duration of each arc, and spectra of plasma waves. A theoretical explanation of the observed features is presented in this report too. The elaborated model allows us to determine the parameters of the electromagnetic noise for different frequency ranges, distances from the arcing site, and distinct kinds of plasma waves.

  5. Large density amplification measured on jets ejected from a magnetized plasma gun

    OpenAIRE

    Yun, Gunsu S.; You, Setthivoine; Bellan, Paul M.

    2007-01-01

    Observation of a large density amplification in the collimating plasma jet ejected from a coplanar coaxial plasma gun is reported. The jet velocity is ~30 km s^-1 and the electron density increases from ~10^20 to 10^(22–23) m^-3. In previous spheromak experiments, electron density of the order 10^(19–21) m^-3 had been measured in the flux conserver region, but no density measurement had been reported for the source gun region. The coplanar geometry of our electrodes permits direct observation...

  6. In depth fusion flame spreading with a deuterium-tritium plane fuel density profile for plasma block ignition

    Institute of Scientific and Technical Information of China (English)

    B.Malekynia; S.S.Razavipour

    2012-01-01

    Solid-state fuel ignition was given by Chu and Bobin according to the hydrodynamic theory at x =0 qualitatively.A high threshold energy flux density,i.e.,E* =4.3 x 1012 J/m2,has been reached.Recently,fast ignition by employing clean petawatt-picosecond laser pulses was performed.The anomalous phenomena were observed to be based on suppression of prepulses.The accelerated plasma block was used to ignite deuterium-tritium fuel at solid-state density.The detailed analysis of the thermonuclear wave propagation was investigated.Also the fusion conditions at x ≠ 0 layers were clarified by exactly solving hydrodynamic equations for plasma block ignition.In this paper,the applied physical mechanisms are determined for nonlinear force laser driven plasma blocks,thermonuclear reaction,heat transfer,electron-ion equilibration,stopping power of alpha particles,bremsstrahlung,expansion,density dependence,and fluid dynamics.New ignition conditions may be obtained by using temperature equations,including thc dcnsity profile that is obtained by the continuity equation and expansion velocity.The density is only a function of x and independent of time.The ignition energy flux density,E*t,for the x ≠ 0 layers is 1.95 × 1012 J/m2.Thus threshold ignition energy in comparison with that at x =0 layers would be reduced to less than 50 percent.

  7. Effect of O2 plasma treatment on density-of-states in a-IGZO thin film transistors

    Science.gov (United States)

    Ding, Xingwei; Huang, Fei; Li, Sheng; Zhang, Jianhua; Jiang, Xueyin; Zhang, Zhilin

    2017-01-01

    This work reports an efficient route for enhancing the performance of amorphous InGaZnO (a-IGZO) thin film transistors (TFT). The mobility was greatly improved by about 38% by means of O2 plasma treatment. Temperature-stress was carried out to investigate the stability and extract the parameters related to activation energy ( E a) and density-of-states (DOS). The DOS was calculated on the basis of the experimentally obtained E a, which can explain the experimental observation. A lower activation energy ( E a, 0.72 eV) and a smaller DOS were obtained in the O2 plasma treatment TFT based on the temperature-dependent transfer curves. The results showed that temperature stability and electrical properties enhancements in a-IGZO thin film transistors were attributed to the smaller DOS. [Figure not available: see fulltext.

  8. Effects of beam velocity and density on an ion-beam pulse moving in magnetized plasmas

    CERN Document Server

    Zhao, Xiao-ying; Zhao, Yong-tao; Qi, Xin; Yang, Lei

    2016-01-01

    The wakefield and stopping power of an ion-beam pulse moving in magnetized plasmas are investigated by particle-in-cell (PIC) simulations. The effects of beam velocity and density on the wake and stopping power are discussed. In the presence of magnetic field, it is found that beside the longitudinal conversed V-shaped wakes, the strong whistler wave are observed when low-density and low-velocity pulses moving in plasmas. The corresponding stopping powers are enhanced due to the drag of these whistler waves. As beam velocities increase, the whistler waves disappear, and only are conversed V-shape wakes observed. The corresponding stopping powers are reduced compared with these in isotropic plasmas. When high-density pulses transport in the magnetized plasmas, the whistler waves are greatly inhibited for low-velocity pulses and disappear for high-velocity pulses. Additionally, the magnetic field reduces the stopping powers for all high-density cases.

  9. Collisionless electrostatic shock formation and ion acceleration in intense laser interactions with near critical density plasmas

    CERN Document Server

    Liu, M; Li, Y T; Yuan, D W; Chen, M; Mulser, P; Sheng, Z M; Murakami, M; Yu, L L; Zheng, X L; Zhang, J

    2016-01-01

    Laser-driven collisonless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas. Particle-in-cell simulations show that both the speed of laser-driven collisionless electrostatic shock and the energies of shock-accelerated ions can be greatly enhanced due to fast laser propagation in near critical density plasmas. However, a response time longer than tens of laser wave cycles is required before the shock formation in a near critical density plasma, in contrast to the quick shock formation in a highly overdense target. More important, we find that some ions can be reflected by the collisionless shock even if the electrostatic potential jump across the shock is smaller than the ion kinetic energy in the shock frame, which seems against the conventional ion-reflection condition. These anomalous ion reflections are attributed to the strongly time-oscillating electric field accompanying laser-driven collisionless shock in a near critical density plasma...

  10. Upgrade of plasma density feedback control system in HT-7 tokamak

    Institute of Scientific and Technical Information of China (English)

    ZHAO Da-Zheng; LUO Jia-Rong; LI Gang; JI Zhen-Shan; WANG Feng

    2004-01-01

    The HT-7 is a superconducting tokamak in China used to make researches on the controlled nuclear fusion as a national project for the fusion research. The plasma density feedback control subsystem is the one of the subsystems of the distributed control system in HT-7 tokamak (HT7DCS). The main function of the subsystem is to control the plasma density on real-time. For this reason, the real-time capability and good stability are the most significant factors, which will influence the control results. Since the former plasma density feedback control system (FPDFCS) based on Windows operation system could not fulfill such requirements well, a new subsystem has to be developed. The paper describes the upgrade of the plasma density feedback control system (UPDFCS), based on the dual operation system (Windows and Linux), in detail.

  11. Tomographic reconstruction of high energy density plasmas with picosecond temporal resolution

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K L

    2005-09-20

    Three-dimensional reconstruction of the electron density in a plasma can be obtained by passing multiple beams at different field angles simultaneously through a plasma and performing a tomographic reconstruction of the measured field-dependent phase profiles. In this letter, a relatively simple experimental setup is proposed and simulations are carried out to verify the technique. The plasma distribution is modeled as a discreet number of phase screens and a Zernike polynomial representation of the phase screens is used to reconstruct the plasma profile. Using a subpicosecond laser, the complete three-dimensional electron density of the plasma can be obtained with a time resolution limited only by the transit time of the probe through the plasma.

  12. Plasma Density Measurements in Cable Gun Experiments with a Sensitive He-Ne Interferometer

    Institute of Scientific and Technical Information of China (English)

    CHEN Lin; HE An; JIANG Wei; XU Min; WU Shoudong; LI Ye

    2007-01-01

    A time-resolved sensitive He-Ne laser interferometer without complicated active stabilization was built up and applied to low-density plasma measurements. A precision of about 0.2° in phase measurements was achieved with a minimum line-integrated plasma density as low as 8.3×l013 cm-2. With this interferometer, the characteristics of the plasma generated by a cable plasma gun was investigated systematically. The reproducibility, spatial and temporal distributions and the averaged injection velocity of the plasma are presented. In addition, the interaction of the plasma flow with a conductor was studied by placing a metal plate in the downstream of the cable gun.

  13. Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

    Science.gov (United States)

    Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-09-01

    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

  14. Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Quevedo, H. J., E-mail: hjquevedo@utexas.edu; McCormick, M.; Wisher, M.; Bengtson, Roger D.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

    2016-01-15

    A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas. Demonstration of this double probe system was done by measuring rapidly evolving plasmas on time scales less than 1 ns produced by the interaction of femtosecond, high intensity, laser pulses with argon gas clusters. Experiments aimed at studying homogeneous plasmas from high intensity laser-gas or laser-cluster interaction could benefit from the use of this probing scheme.

  15. Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas

    Science.gov (United States)

    Quevedo, H. J.; McCormick, M.; Wisher, M.; Bengtson, Roger D.; Ditmire, T.

    2016-01-01

    A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas. Demonstration of this double probe system was done by measuring rapidly evolving plasmas on time scales less than 1 ns produced by the interaction of femtosecond, high intensity, laser pulses with argon gas clusters. Experiments aimed at studying homogeneous plasmas from high intensity laser-gas or laser-cluster interaction could benefit from the use of this probing scheme.

  16. Influence of sample temperature on the expansion dynamics and the optical emission of laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Eschlböck-Fuchs, S.; Haslinger, M.J.; Hinterreiter, A.; Kolmhofer, P.; Huber, N. [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Rössler, R. [voestalpine Stahl GmbH, A-4031 Linz (Austria); Heitz, J. [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2013-09-01

    We investigate the influence of sample temperature on the dynamics and optical emission of laser induced plasma for various solid materials. Bulk aluminum alloy, silicon wafer, and metallurgical slag samples are heated to temperature T{sub S} ≤ 500 °C and ablated in air by Nd:YAG laser pulses (wavelength 1064 nm, pulse duration approx. 7 ns). The plasma dynamics is investigated by fast time-resolved photography. For laser-induced breakdown spectroscopy (LIBS) the optical emission of plasma is measured by Echelle spectrometers in combination with intensified CCD cameras. For all sample materials the temporal evolution of plume size and broadband plasma emission vary systematically with T{sub S}. The size and brightness of expanding plumes increase at higher T{sub S} while the mean intensity remains independent of temperature. The intensity of emission lines increases with temperature for all samples. Plasma temperature and electron number density do not vary with T{sub S}. We apply the calibration-free LIBS method to determine the concentration of major oxides in slag and find good agreement to reference data up to T{sub S} = 450 °C. The LIBS analysis of multi-component materials at high temperature is of interest for technical applications, e.g. in industrial production processes. - Highlights: • Size and emission of laser-induced plasma increase with sample temperature Ts. • Mean optical intensity of plasma is independent of Ts. • Plasma temperature and electron number density do not vary with Ts. • Major oxides in steel slag are quantified up to Ts = 450 °C. • Industrial steel slags are analyzed by calibration-free LIBS method.

  17. Analysis of plasma equilibrium based on orbit-driven current density profile in steady-state plasma on QUEST

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K., E-mail: nakamura@triam.kyushu-u.ac.jp [RIAM, Kyushu University, Kasuga 816-8580 (Japan); Alam, M.M. [IGSES, Kyushu University, Kasuga 816-8580 (Japan); Jiang, Y.Z. [Tsinghua University, Beijing 100084 (China); Mitarai, O. [Tokai University, Kumamoto 862-8652 (Japan); Kurihara, K.; Kawamata, Y.; Sueoka, M.; Takechi, M. [Japan Atomic Energy Agency, Naka 311-0193 (Japan); Hasegawa, M.; Tokunaga, K.; Araki, K.; Zushi, H.; Hanada, K.; Fujisawa, A.; Idei, H.; Nagashima, Y.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Nagata, T. [RIAM, Kyushu University, Kasuga 816-8580 (Japan); and others

    2016-11-01

    Highlights: • High energy particle guiding center orbit is calculated as a contour plot of conserved variable. • Current density profile is analyzed based on the orbit-driven current. • Plasma equilibrium is reconstructed by considering the hollow current profile. - Abstract: In the present RF-driven (ECCD) steady-state plasma on QUEST (B{sub t} = 0.25 T, R = 0.68 m, a = 0.40 m), plasma current seems to flow in the open magnetic surface outside of the closed magnetic surface in the low-field region according to plasma current fitting (PCF) method. We consider that the current in the open magnetic surface is due to orbit-driven current by high-energy particles in RF-driven plasma. So based on the analysis of current density profile based on the orbit-driven current, plasma equilibrium is to be calculated. We calculated high energy particles guiding center orbits as a contour plot of conserved variable in Hamiltonian formulation and considered particles initial position with different levels of energy and pitch angles that satisfy resonance condition. Then the profile of orbit-driven current is estimated by multiplying the particle density on the resonance surface and the velocity on the orbits. This analysis shows negative current near the magnetic axis and hollow current profile is expected even if pressure driven current is considered. Considering the hollow current profile shifted toward the low-field region, the equilibrium is fitted by J-EFIT coded by MATLAB.

  18. Two-dimensional Hybrid Simulations of Kinetic Plasma Turbulence: Current and Vorticity vs Proton Temperature

    CERN Document Server

    Franci, Luca; Matteini, Lorenzo; Verdini, Andrea; Landi, Simone

    2016-01-01

    Proton temperature anisotropies between the directions parallel and perpendicular to the mean magnetic field are usually observed in the solar wind plasma. Here, we employ a high-resolution hybrid particle-in-cell simulation in order to investigate the relation between spatial properties of the proton temperature and the peaks in the current density and in the flow vorticity. Our results indicate that, although regions where the proton temperature is enhanced and temperature anisotropies are larger correspond approximately to regions where many thin current sheets form, no firm quantitative evidence supports the idea of a direct causality between the two phenomena. On the other hand, quite a clear correlation between the behavior of the proton temperature and the out-of-plane vorticity is obtained.

  19. A fibre based triature interferometer for measuring rapidly evolving, ablatively driven plasma densities

    Science.gov (United States)

    Macdonald, J.; Bland, S. N.; Threadgold, J.

    2015-08-01

    We report on the first use of a fibre interferometer incorporating triature analysis for measuring rapidly evolving plasma densities of ne ˜ 1013/cm3 and above, such as those produced by simple coaxial plasma guns. The resultant system is extremely portable, easy to field in experiments, relatively cheap to produce, and—with the exception of a small open area in which the plasma is sampled—safe in operation as all laser light is enclosed.

  20. The energy density of a Landau damped plasma wave

    NARCIS (Netherlands)

    Best, R. W. B.

    1999-01-01

    In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite

  1. Thermographic determination of the sheath heat transmission coefficient in a high density plasma

    NARCIS (Netherlands)

    van den Berg, M. A.; Bystrov, K.; Pasquet, R.; Zielinski, J. J.; De Temmerman, G.

    2013-01-01

    Experiments were performed in the Pilot-PSI linear plasma device, to determine the sheath heat transmission coefficients in a high recycling regime under various conditions of density (1–20 × 1020 m−3) and plasma composition (H2, Ar, N2) relevant for the

  2. Thermographic determination of the sheath heat transmission coefficient in a high density plasma

    NARCIS (Netherlands)

    van den Berg, M. A.; Bystrov, K.; Pasquet, R.; Zielinski, J. J.; De Temmerman, G.

    2013-01-01

    Experiments were performed in the Pilot-PSI linear plasma device, to determine the sheath heat transmission coefficients in a high recycling regime under various conditions of density (1–20 × 1020 m−3) and plasma composition (H2, Ar, N2) relevant for the

  3. Generation of low-temperature air plasma for food processing

    Science.gov (United States)

    Stepanova, Olga; Demidova, Maria; Astafiev, Alexander; Pinchuk, Mikhail; Balkir, Pinar; Turantas, Fulya

    2015-11-01

    The project is aimed at developing a physical and technical foundation of generating plasma with low gas temperature at atmospheric pressure for food industry needs. As known, plasma has an antimicrobial effect on the numerous types of microorganisms, including those that cause food spoilage. In this work an original experimental setup has been developed for the treatment of different foods. It is based on initiating corona or dielectric-barrier discharge in a chamber filled with ambient air in combination with a certain helium admixture. The experimental setup provides various conditions of discharge generation (including discharge gap geometry, supply voltage, velocity of gas flow, content of helium admixture in air and working pressure) and allows for the measurement of the electrical discharge parameters. Some recommendations on choosing optimal conditions of discharge generation for experiments on plasma food processing are developed.

  4. Active measurement of the thermal electron density and temperature on the Mercury Magnetospheric Orbiter of the BepiColombo mission

    Science.gov (United States)

    Trotignon, J. G.; Béghin, C.; Lagoutte, D.; Michau, J. L.; Matsumoto, H.; Kojima, H.; Hashimoto, K.; Kasaba, Y.; Blomberg, L. G.; Lebreton, J. P.; Masson, A.; Hamelin, M.; Pottelette, R.

    2006-01-01

    The thermal component of Mercury's electron population has never been measured. One scientific objective of the Plasma Wave Investigation consortium, PWI, is to determine the influence of the thermal plasma upon the formation and dynamics of the planetary magnetosphere, as a function of solar activity. The Active Measurement of Mercury's Plasma experiment, AM 2P, has been proposed as part of PWI, to monitor the density and temperature of the thermal electron population, during the whole mission of the Mercury Magnetospheric Orbiter of BepiColombo. These two physical parameters will be deduced from the measurements of the self- and mutual-impedances of the MEFISTO (Mercury Electric Field In Situ TOol) double-sphere antenna, in a frequency range comprising the expected plasma frequency. The in situ measurement of the antenna impedance is also essential for calibrating the electric antenna which measures the natural waves; it will allow, in particular, the effective length of the antenna to be calculated as a function of frequency and plasma conditions. The purpose of this paper is to define the scientific objectives of AM 2P, to explain the principle of the measurement, to describe the electronic device, and to show the ability of AM 2P to make reliable and accurate measurements of the thermal plasma density and temperature in the Hermean magnetosphere, as well as in the solar wind at heliocentric distances of 0.31-0.47 AU. The potential performance of this instrument has been evaluated using both an analytical approach and numerical simulations.

  5. High density plasma gun generates plasmas at 190 kilometers per second

    Science.gov (United States)

    Espy, P. N.

    1971-01-01

    Gun has thin metal foil disc which positions or localizes gas to be ionized during electrical discharge cycle, overcoming major limiting factor in obtaining such plasmas. Expanding plasma front travels at 190 km/sec, compared to plasmas of 50 to 60 km/sec previously achieved.

  6. Lack of correlation of glucose levels in filtered blood plasma to density and conductivity measurements.

    Science.gov (United States)

    Gordon, David M; Ash, Stephen R

    2009-01-01

    The purpose of this research project was to determine whether the glucose level of a blood plasma sample from a diabetic patient could be predicted by measuring the density and conductivity of ultrafiltrate of plasma created by a 30,000 m.w. cutoff membrane. Conductivity of the plasma filtrate measures electrolyte concentration and should correct density measurements for changes in electrolytes and water concentration. In vitro studies were performed measuring conductivity and density of solutions of varying glucose and sodium chloride concentrations. Plasma from seven hospitalized patients with diabetes was filtered across a 30,000 m.w. cutoff membrane. The filtrate density and conductivity were measured and correlated to glucose levels. In vitro studies confirmed the ability to predict glucose from density and conductivity measurements, in varying concentrations of glucose and saline. In plasma filtrate, the conductivity and density measurements of ultrafiltrate allowed estimation of glucose in some patients with diabetes but not others. The correlation coefficient for the combined patient data was 0.45 which was significant but only explained 20% of the variability in the glucose levels. Individually, the correlation was significant in only two of the seven patients with correlation coefficients of 0.79 and 0.88. The reasons for lack of correlation are not clear, and cannot be explained by generation of idiogenic osmoles, effects of alcohol dehydrogenase, water intake, etc. This combination of physical methods for glucose measurement is not a feasible approach to measuring glucose in plasma filtrate.

  7. Low energy plasma treatment of a proton exchange membrane used for low temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Charles, C [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Ramdutt, D [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Brault, P [GREMI-CNRS Laboratory, University of Orleans, BP 6744, F-45067, Orleans (France); Caillard, A [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Bulla, D [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Boswell, R [Space Plasma, Power, and Propulsion group, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Rabat, H [GREMI-CNRS Laboratory, University of Orleans, BP 6744, F-45067, Orleans (France); Dicks, A [School of Engineering, University of Queensland, Brisbane, QLD 4072 (Australia)

    2007-05-15

    A low energy ({approx}30 V) plasma treatment of Nafion, a commercial proton exchange membrane used for low temperature fuel cells, is performed in a helicon radiofrequency (13.56 MHz) plasma system. For argon densities in the 10{sup 9}-10{sup 10} cm{sup -3} range, the water contact angle (hydrophobicity) of the membrane surface linearly decreases with an increase in the plasma energy dose, which is maintained below 5.1 J cm{sup -2}, and which results from the combination of an ion energy dose (up to 3.8 J cm{sup -2}) and a photon (mostly UV) energy dose (up to 1.3 J cm{sup -2}). The decrease in water contact angle is essentially a result of the energy brought to the surface by ion bombardment. The measured effect of the energy brought to the surface by UV light is found to be negligible.

  8. Low energy plasma treatment of a proton exchange membrane used for low temperature fuel cells

    Science.gov (United States)

    Charles, C.; Ramdutt, D.; Brault, P.; Caillard, A.; Bulla, D.; Boswell, R.; Rabat, H.; Dicks, A.

    2007-05-01

    A low energy (~30 V) plasma treatment of Nafion, a commercial proton exchange membrane used for low temperature fuel cells, is performed in a helicon radiofrequency (13.56 MHz) plasma system. For argon densities in the 109-1010 cm-3 range, the water contact angle (hydrophobicity) of the membrane surface linearly decreases with an increase in the plasma energy dose, which is maintained below 5.1 J cm-2, and which results from the combination of an ion energy dose (up to 3.8 J cm-2) and a photon (mostly UV) energy dose (up to 1.3 J cm-2). The decrease in water contact angle is essentially a result of the energy brought to the surface by ion bombardment. The measured effect of the energy brought to the surface by UV light is found to be negligible.

  9. Thermodynamic Properties of Gaseous Plasmas in the Limit of Extremely Low Temperature

    CERN Document Server

    Iosilevskiy, Igor

    2010-01-01

    Limiting structure of thermodynamic functions of gaseous plasmas is under consideration in the limit of zero temperature and density. Remarkable tendency, which was claimed previously (Iosilevskiy and Gryaznov, 1985) is carried to extreme. Both equations of state, thermal and caloric ones obtain in this limit identical stepped structure ("ionization stairs") for plasma of any single element when this limit (T -> 0, n -> 0) is carried out at fixed value of chemical potential for electrons (or atoms). The same stepped structure is valid for plasma of mixtures or compounds. This structure appears within a fixed (negative) range of chemical potential of electrons bounded below by value of major ionization potential of element and above by the value depending on sublimation energy of substance. Binding energies of all possible bound complexes (atomic, molecular, ionic and clusters) in its ground state are the only quantities that manifest itself in meaningful details of this limiting picture as location and value ...

  10. Laser diagnostics on atmospheric pressure discharge plasmas, including cryoplasmas, in environments around room and cryogenic temperature

    Science.gov (United States)

    Sakakibara, Noritaka; Muneoka, Hitoshi; Urabe, Keiichiro; Yasui, Ryoma; Sakai, Osamu; Terashima, Kazuo

    2017-04-01

    Cryoplasmas, the plasma gas temperature (T g) of which can be controlled continuously below room temperature, show various unique and advantageous properties depending on T g. Recently, the T g dependence of plasma chemistry related to metastable helium (Hem) has been revealed in helium cryoplasmas. However, T g was only estimated by thermal calculation from the temperature outside the plasmas. In this study, for better evaluation of T g, near-infrared laser heterodyne interferometry (NIR-LHI) measurements were conducted in atmospheric pressure helium pulsed discharge plasmas at around room and cryogenic ambient temperatures (T a). The maximum difference between T g and T a was evaluated as 47 K at T a  =  300 K with 282 mW power consumption. To further investigate the T g dependence of plasma chemical reactions related to Hem, laser absorption spectroscopy (LAS) was performed on the same discharge plasmas to measure the Hem density and lifetime. The Hem lifetime was longer at lower T g, i.e. the lifetime at T g  =  145 K (9.6 µs) was seven times longer than that at T g  =  386 K (1.4 µs). By comparing the results with the numerically simulated rates of Hem quenching reactions taking T g into account, the mechanism of the Hem quenching reaction was revealed to vary with T g even though the main quenching reaction was a three-body collision at all T g. In this manner, the combination of NIR-LHI with LAS led directly to the T g dependence of Hem quenching reactions.

  11. Dissociative recombination coefficient for low temperature equilibrium cesium plasma

    Science.gov (United States)

    Momozaki, Yoichi; El-Genk, Mohamed S.

    2002-07-01

    The dissociative recombination (DR) coefficient in decaying low temperature Cs plasma is calculated based on the experimentally measured relaxation time of decaying Cs plasma by L. P. Harris [J. Appl. Phys. 36, 1543 (1965)]. Results showed that DR is the dominant recombination process over three-body recombination at T<1650 K and PCs of 0.5-20 Torr (67-2666 Pa). The estimated DR coefficient for Cs is between 10-12 and 10-13 m3/s at T<1750 K and PCs of 0.5-20 Torr. Although theory predicts that DR coefficient solely depends on temperature, the present results show pressure dependency. For typical operating conditions in thermionic converters (T<1650 K and PCsless-than-or-equal400 Pa), DR is constant and approx5.26 x10-13 m3/s.

  12. Lattice QCD at finite temperature and density from Taylor expansion

    Science.gov (United States)

    Steinbrecher, Patrick

    2017-01-01

    In the first part, I present an overview of recent Lattice QCD simulations at finite temperature and density. In particular, we discuss fluctuations of conserved charges: baryon number, electric charge and strangeness. These can be obtained from Taylor expanding the QCD pressure as a function of corresponding chemical potentials. Our simulations were performed using quark masses corresponding to physical pion mass of about 140 MeV and allow a direct comparison to experimental data from ultra-relativistic heavy ion beams at hadron colliders such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. In the second part, we discuss computational challenges for current and future exascale Lattice simulations with a focus on new silicon developments from Intel and NVIDIA.

  13. The Effect of Temperature on the Spectral Emission of Plasma Induced in Water

    Directory of Open Access Journals (Sweden)

    B. Charfi

    2013-01-01

    Full Text Available A numerical modeling investigation of the spectral emission of laser-induced plasma in MgCl2-NaCl aqueous solution has been presented. A model based on equilibrium equations has been developed for the computation of the plasma composition and excited levels population. Physical interpretation is presented to comment on firstly the evolution of atomic species number densities, and secondly on the population of the excited species emitting MgII and NaI resonant lines for temperatures ranging from 3000 K to 20 000 K. It is shown that MgII line reach a maximum of population on the issuing level, at norm temperature of 13800 K. Whereas, NaI line presents two norm temperatures, evaluated at 3300 K and 11700 K. This splitting of the NaI norm temperature is explained by the low-ionization potential and weak concentration of the sodium atom in this aqueous solution. Thus, the proposed model can be useful to predict the optimal plasma temperature for the detection of given chemical element, which is not easy to reveal experimentally.

  14. Experimental charge density of hematite in its magnetic low temperature and high temperature phases.

    Science.gov (United States)

    Theissmann, R; Fuess, H; Tsuda, K

    2012-09-01

    Structural parameters of hematite (α-Fe(2)O(3)), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Determination of self generated magnetic field and the plasma density using Cotton Mouton polarimetry with two color probes

    Directory of Open Access Journals (Sweden)

    Joshi A.S.

    2013-11-01

    Full Text Available Self generated magnetic fields (SGMF in laser produced plasmas are conventionally determined by measuring the Faraday rotation angle of a linearly polarized laser probe beam passing through the plasma along with the interferogram for obtaining plasma density. In this paper, we propose a new method to obtain the plasma density and the SGMF distribution from two simultaneous measurements of Cotton Mouton polarimetry of two linearly polarized probe beams of different colors that pass through plasma in a direction normal to the planar target. It is shown that this technique allows us to determine the distribution of SGMF and the plasma density without doing interferometry of laser produced plasmas.

  16. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    Science.gov (United States)

    Reames, Donald V.

    2016-11-01

    Thirty years ago Breneman and Stone [1] observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or “impulsive” show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ∼1000 for (76magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated “gradual” SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T seed population containing residual impulsive suprathermal ions. Most of the large event-to-event abundance variations and their time variation are largely explained by variations in T magnified by A/Q-dependent fractionation during transport. However, the non-thermal variance of impulsive SEP events (∼30%) exceeds that of the ∼3 MK gradual events (∼10%) so that several small impulsive events must be averaged together with the ambient plasma to form the seed population for shock acceleration in these events.

  17. Improved confinement in high-density H-modes via modification of the plasma boundary with lower hybrid wavesa)

    Science.gov (United States)

    Terry, J. L.; Reinke, M. L.; Hughes, J. W.; LaBombard, B.; Theiler, C.; Wallace, G. M.; Baek, S. G.; Brunner, D.; Churchill, R. M.; Edlund, E.; Ennever, P.; Faust, I.; Golfinopoulos, T.; Greenwald, M.; Hubbard, A. E.; Irby, J.; Lin, Y.; Parker, R. R.; Rice, J. E.; Shiraiwa, S.; Walk, J. R.; Wukitch, S. J.; Xu, P.

    2015-05-01

    Injecting Lower Hybrid Range of Frequency (LHRF) waves into Alcator C-Mod's high-density H-mode plasmas has led to enhanced global energy confinement by increasing pedestal temperature and pressure gradients, decreasing the separatrix density, modifying the pedestal radial electric field and rotation, and decreasing edge turbulence. These experiments indicate that edge LHRF can be used as an actuator to increase energy confinement via modification of boundary quantities. H98-factor increases of up to ˜35% (e.g., H98 from 0.75 to 1.0) are seen when moderate amounts of LH power (PLH/Ptot ˜ 0.15) are applied to H-modes of densities n ¯ e ˜ 3 × 1020 m-3, corresponding to values ˜0.5 of the Greenwald density. However, the magnitude of the improvement is reduced if the confinement quality of the target H-mode plasma is already good (i.e., H98target ˜ 1). Ray-tracing modeling and accessibility calculations for the LH waves indicate that they do not penetrate to the core. The LHRF power appears to be deposited in plasma boundary region, with a large fraction of the injected power increment appearing promptly on the outer divertor target. There is no evidence that the LH waves are driving current in these plasmas. The LHRF-actuated improvements are well correlated with suppressed pedestal density fluctuations in the 100-300 kHz range. There is also a correlation between the improved confinement and a drop in separatrix density, a correlation that is consistent with previous H-mode results with no LHRF.

  18. Simulating x-ray Thomson scattering signals from high-density, millimetre-scale plasmas at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, D. A., E-mail: david.chapman@awe.co.uk [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR (United Kingdom); Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Kraus, D.; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Gaffney, J. A.; Hawreliak, J. A.; Landen, O. L.; Le Pape, S.; Ma, T.; Nilsen, J.; Pak, A.; Swift, D. C.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Gericke, D. O. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States); Guymer, T. M. [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR (United Kingdom); Neumayer, P. [Gesellschaft für Schwerionenforschung, 64291 Darmstadt (Germany); Redmer, R. [Institut für Physik, Universität Rostock, 18051 Rostock (Germany); and others

    2014-08-15

    We have developed a model for analysing x-ray Thomson scattering data from high-density, millimetre-scale inhomogeneous plasmas created during ultra-high pressure implosions at the National Ignition Facility in a spherically convergent geometry. The density weighting of the scattered signal and attenuation of the incident and scattered x-rays throughout the target are included using radial profiles of the density, opacity, ionization state, and temperature provided by radiation-hydrodynamics simulations. These simulations show that the scattered signal is strongly weighted toward the bulk of the shocked plasma and the Fermi degenerate material near the ablation front. We show that the scattered signal provides a good representation of the temperature of this highly nonuniform bulk plasma and can be determined to an accuracy of ca. 15% using typical data analysis techniques with simple 0D calculations. On the other hand, the mean ionization of the carbon in the bulk is underestimated. We suggest that this discrepancy is due to the convolution of scattering profiles from different regions of the target. Subsequently, we discuss modifications to the current platform to minimise the impact of inhomogeneities, as well as opacity, and also to enable probing of conditions more strongly weighted toward the compressed core.

  19. Temperature Control in Spark Plasma Sintering: An FEM Approach

    Directory of Open Access Journals (Sweden)

    G. Molénat

    2010-01-01

    Full Text Available Powder consolidation assisted by pulsed current and uniaxial pressure, namely, Spark Plasma Sintering (SPS, is increasingly popular. One limitation however lies in the difficulty of controlling the sample temperature during compaction. The aim of this work is to present a computational method for the assembly temperature based on the finite elements method (FEM. Computed temperatures have been compared with experimental data for three different dies filled with three materials with different electrical conductivities (TiAl, SiC, Al2O3. The results obtained are encouraging: the difference between computed and experimental values is less than 5%. This allows thinking about this FEM approach as a predictive tool for selecting the right control temperatures in the SPS machine.

  20. Experimental charge density of hematite in its magnetic low temperature and high temperature phases

    Energy Technology Data Exchange (ETDEWEB)

    Theissmann, R., E-mail: ralf.theissmann@kronosww.com [Faculty of Engineering and CeNIDE (Center for NanoIntegration Duisburg-Essen), University of Duisburg-Essen, Bismarckstr. 81, 47057 Duisburg (Germany); Fuess, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Tsuda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, 980-8577 Sendai (Japan)

    2012-09-15

    Structural parameters of hematite ({alpha}-Fe{sub 2}O{sub 3}), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90 K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. -- Highlights: Black-Right-Pointing-Pointer Quantitative CBED was used to study hematite ({alpha}-Fe2O3). Black-Right-Pointing-Pointer Structure and charge density of both antiferromagnetic phases were investigated. Black-Right-Pointing-Pointer Topological charge density analysis was combined with a Bader analysis. Black-Right-Pointing-Pointer A transition from a Mott-Hubbard to a charge transfer insulator is proposed. Black-Right-Pointing-Pointer A frustrated triangular magnetic coupling in the oxygen planes is proposed.

  1. Physics and applications of high energy density plasmas. Extreme state driven by pulsed electromagnetic energy

    Energy Technology Data Exchange (ETDEWEB)

    Horioka, Kazuhiko (ed.)

    2002-06-01

    The papers presented at the symposium on ''Physics and application of high energy density plasmas, held December 20-21, 2001 at NIFS'' are collected in this proceedings. The topics covered in the meeting include dense z-pinches, plasma focus, intense charged particle beams, intense radiation sources, discharge pumped X-ray lasers, their diagnostics, and applications of them. The papers reflect the present status and trends in the research field of high energy density plasmas. (author)

  2. Demonstration of resonant backward Raman amplification in high-density gas-jet plasma

    Science.gov (United States)

    Wu, Z. H.; Zhou, K. N.; Zheng, X. M.; Wei, X. F.; Zhu, Q. H.; Su, J. Q.; Xie, N.; Jiao, Z. H.; Peng, H.; Wang, X. D.; Sun, L.; Li, Q.; Huang, Z.; Zuo, Y. L.

    2016-10-01

    Backward Raman amplification was observed in a 0.7 mm-long high-density gas jet plasma. The 800 nm 30 fs seed pulse was amplified by a factor  ∼28, with an output energy of 2.8 mJ. The output spectra showed that the waveband around 800 nm was significantly amplified. The experimental result demonstrated that the resonant Raman amplification can be realized in high-density plasma against strong plasma instability.

  3. Spaced-Resolved Electron Density of Aluminum Plasma Produced by Frequency-Tripled Laser

    Institute of Scientific and Technical Information of China (English)

    Yang Boqian; Han Shensheng; Zhang Jiyan; Zheng Zhijian; Yang Guohong; Yang Jiaming; Li Jun; Wang Yan

    2005-01-01

    By using the space-resolved spectrograph, the K-shell emission from laser-produced plasma was investigated. Electron density profiles along the normal direction of the target surface in aluminum laser-plasmas were obtained by two different diagnostic methods and compared with the profiles from the theoretical simulation of hydrodynamics code MULTI1D. The results corroborate the feasibility to obtain the electron density above the critical surface by the diagnostic method based on the Stark-broadened wings in the intermediately coupled plasmas.

  4. Diagnosing the high density FRX-L Field Reversed Configuration plasma

    Science.gov (United States)

    Wurden, G. A.; Intrator, T. P.; Renneke, R. M.; Dorf, L. A.; Farrell, M. W.; Gray, T. K.; Hsu, S. C.; Lynn, A. G.; Ruden, E. L.

    2006-10-01

    The FRX-L plasma is a high pressure, high density, field reversed configuration (FRC), at n ˜1x10^16-1x10^17 cm-3, and hundreds of eV electron temperature. In order to study formation, equilibrium, transport, flow, and confinement issues, we have a suite of diagnostics. Standard plasma diagnostics include B-dot probes, magnetic flux loops, single and multi-channel visible spectroscopy, optical light tomography arrays, up to 8 filtered visible fibers (546 nm or 486 nm) and an 8-chord side-on HeNe interferometer. Recent diagnostic additions include AXUV bolometers, VUV spectroscopy using a methly salicylate fluorescer converter and optical multichannel analyzer (OMA), eight simultaneous axial views of visible spectra with a 0.3 meter spectrometer and Princeton Instruments PI-Max camera, two-foil end-on surface barrier diode soft x-ray measurements, a hard x-ray/neutron plastic scintillator/ PMT, and indium activation foils to detect time-integrated absolute DD neutron emission. We also discuss plans for a soft x-ray framing camera, using end-on optical access and consisting of a pinhole/fluorescer geometry coupled to a high resolution DiCam camera.

  5. Measuring the electron density in plasmas from the difference of Lorentzian part of the widths of two Balmer series hydrogen lines

    Energy Technology Data Exchange (ETDEWEB)

    Yubero, C. [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain); García, M.C., E-mail: fa1gamam@uco.es [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain); Dimitrijevic, M.S. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Sola, A.; Gamero, A. [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain)

    2015-05-01

    We present an alternative optical emission spectroscopy method to measure the plasma electron density from the difference of widths of two Balmer series hydrogen lines (H{sub α} and H{sub β}), especially convenient for non-thermal plasmas since with this method, there is no need to know either the gas temperature or the van der Waals contribution to the Lorentzian part of the line. In this paper it has been assumed that the part of full width at half maximum due to Stark broadening can be determined with the approximation of Lorentzian line shape. The method has been applied to the determination of the electron density in an argon microwave-induced plasma maintained at atmospheric pressure, and comparison with the results obtained using other diagnostic methods has been done. - Highlights: • An alternative method to measure the electron density in plasmas from two Balmer series hydrogen lines (H{sub α} and H{sub β}) is presented. • The method is very convenient for plasmas with electron densities of the order of 10{sup 14} cm{sup −3} and above, at low gas temperatures. • It has been applied to the determination of the electron density of an argon microwave plasma at atmospheric pressure. • Results from it are in good agreement with previous ones obtained using other diagnostic methods.

  6. Ion density and temperature profiles along (XGSM) and across (ZGSM) the magnetotail as observed by THEMIS, Geotail, and ARTEMIS

    Science.gov (United States)

    Artemyev, A. V.; Angelopoulos, V.; Hietala, H.; Runov, A.; Shinohara, I.

    2017-02-01

    Characteristics of the two-dimensional configuration of the magnetotail current sheet are important for modeling magnetotail motion/evolution and charged particle energization. Because of the magnetotail current sheet's dynamical nature, however, simultaneous plasma and magnetic field measurements at different radial distances are required to reveal this configuration. Simultaneous observations of the magnetotail current sheet from Time History of Events and Macroscale Interactions during Substorms (THEMIS) D (around 10RE downtail), Geotail (around 30RE downtail), and Acceleration, Reconnection, Turbulence and Electrodynamics of the Moons Interaction with the Sun (ARTEMIS) P1 (around 55RE downtail) are used to study distributions of plasma (ion) density and temperature along (Earth-Sun direction) and across (north-south direction) the magnetotail. Fourteen events (each including several current sheet crossings at different downtail distances) are studied. We demonstrate that the plasma temperature along and across the magnetotail varies more significantly than plasma density does. The temperature decrease from equatorial plane to current sheet boundaries is a major contributor to the cross-tail pressure balance. The Alfven velocity VA,B calculated at the current sheet boundaries increases significantly toward the Earth from 700 km/s at lunar orbit ˜55RE to 2200 km/s around ˜10RE downtail. The corresponding energy EA=mpVA,B2 (mp is the proton mass) is 4 times larger than the plasma temperature T0 in the magnetotail's equatorial plane, whereas the ratio EA/T0 is constant along the magnetotail. The plasma temperature T0 measured around lunar orbit in the magnetotail agrees well with the simultaneously measured energy of solar wind protons mpVSW2/2 (VSW is the solar wind speed).

  7. Compatibility of lithium plasma-facing surfaces with high edge temperatures in the Lithium Tokamak Experiment (LTX)

    Science.gov (United States)

    Majeski, Dick

    2016-10-01

    High edge electron temperatures (200 eV or greater) have been measured at the wall-limited plasma boundary in the Lithium Tokamak eXperiment (LTX). High edge temperatures, with flat electron temperature profiles, are a long-predicted consequence of low recycling boundary conditions. The temperature profile in LTX, measured by Thomson scattering, varies by as little as 10% from the plasma axis to the boundary, determined by the lithium-coated high field-side wall. The hydrogen plasma density in the outer scrape-off layer is very low, 2-3 x 1017 m-3 , consistent with a low recycling metallic lithium boundary. The plasma surface interaction in LTX is characterized by a low flux of high energy protons to the lithium PFC, with an estimated Debye sheath potential approaching 1 kV. Plasma-material interactions in LTX are consequently in a novel regime, where the impacting proton energy exceeds the peak in the sputtering yield for the lithium wall. In this regime, further increases in the edge temperature will decrease, rather than increase, the sputtering yield. Despite the high edge temperature, the core impurity content is low. Zeff is 1.2 - 1.5, with a very modest contribution (Gas puffing is used to increase the plasma density. After gas injection stops, the discharge density is allowed to drop, and the edge is pumped by the low recycling lithium wall. An upgrade to LTX which includes a 35A, 20 kV neutral beam injector to provide core fueling to maintain constant density, as well as auxiliary heating, is underway. Two beam systems have been loaned to LTX by Tri Alpha Energy. Additional results from LTX, as well as progress on the upgrade - LTX- β - will be discussed. Work supported by US DOE contracts DE-AC02-09CH11466 and DE-AC05-00OR22725.

  8. Strongly Driven Magnetic Reconnection in a Magnetized High-Energy-Density Plasma

    Science.gov (United States)

    Fiksel, G.; Barnak, D. H.; Chang, P.-Y.; Haberberger, D.; Hu, S. X.; Ivancic, S.; Nilson, P. M.; Fox, W.; Deng, W.; Bhattacharjee, A.; Germaschewski, K.

    2014-10-01

    Magnetic reconnection in a magnetized high-energy-density plasma is characterized by measuring the dynamics of the plasma density and magnetic field between two counter-propagating and colliding plasma flows. The density and magnetic field were profiled using the 4 ω angular filter refractometry and fast proton deflectometry diagnostics, respectively. The plasma flows are created by irradiating oppositely placed plastic targets with 1.8-kJ, 2-ns laser beams on the OMEGA EP Laser System. The two plumes are magnetized by an externally controlled magnetic field with an x-type null point geometry with B = 0 at the midplane and B = 8 T at the targets. The interaction region is pre-filled with a low-density background plasma. The counterflowing super-Alfvénic plasma plumes sweep up and compress the magnetic field and the background plasma into a pair of magnetized ribbons, which collide, stagnate, and reconnect at the midplane, allowing for the first detailed observation of a stretched current sheet in laser-driven reconnection experiments. The measurements are in good agreement with first-principles particle-in-cell simulations. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and NLUF Grant DE-SC0008655.

  9. Derivation of the Fano profile from time-dependent density-functional theory for local thermodynamic equilibrium plasmas

    Science.gov (United States)

    Kiyokawa, Shuji

    2007-04-01

    We give the derivation of the Fano profile (the resonance energy position, the resonance width Γ , and q value) from the time-dependent nonrelativistic density-functional theory (DFT) and propose a scheme for calculating the photoabsorption cross section of hot dense plasmas. As a consequence of this derivation, we show the line profile is obtained as a superposition of Fano and Lorentz profiles when the competition of two optically allowed bound-bound and bound-free transitions occurs. We also show the results of the photoabsorption cross section by applying our scheme to an Fe plasma (density is 7.85g/cm3 , temperature is 100eV ), where the calculation is carried out without numerical divergence for any photon energy. The calculated results are in good agreement with those of Grimaldi.

  10. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    Science.gov (United States)

    Ting, A.; Gordon, D.; Helle, M.; Kaganovich, D.; Sprangle, P.; Hafizi, B.

    2010-11-01

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, ˜1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called "bucket jumping" where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  11. Plasma density evolution in plasma opening switch obtained by a time-resolved sensitive He-Ne interferometer

    Science.gov (United States)

    Chen, Lin; Ren, Jing; Guo, Fan; Zhou, LiangJi; Li, Ye; He, An; Jiang, Wei

    2014-03-01

    To understand the formation process of vacuum gap in coaxial microsecond conduction time plasma opening switch (POS), we have made measurements of the line-integrated plasma density during switch operation using a time-resolved sensitive He-Ne interferometer. The conduction current and conduction time in experiments are about 120 kA and 1 μs, respectively. As a result, more than 85% of conduction current has been transferred to an inductive load with rise time of 130 ns. The radial dependence of the density is measured by changing the radial location of the line-of-sight for shots with the same nominal POS parameters. During the conduction phase, the line-integrated plasma density in POS increases at all radial locations over the gun-only case by further ionization of material injected from the guns. The current conduction is observed to cause a radial redistribution of the switch plasma. A vacuum gap forms rapidly in the plasma at 5.5 mm from the center conductor, which is consistent with the location where magnetic pressure is the largest, allowing current to be transferred from the POS to the load.

  12. A Catalytic Sensor for Measurement of Radical Density in CO2 Plasmas

    Directory of Open Access Journals (Sweden)

    Alenka Vesel

    2012-11-01

    Full Text Available A catalytic sensor for the measurement of radical density in weakly ionized CO2 plasmas, created in a low-pressure electrodeless discharge, is presented. The CO2 plasma was created in a 4 cm wide borosilicate glass tube inside a copper coil connected to a radio frequency generator operating at 27.12 MHz with a nominal power of 250 W. The dissociation fraction of the CO2 molecules was measured in the early afterglow at pressures ranging from 10 Pa to 100 Pa, and at distances of up to 35 cm along the gas stream from the glowing plasma. The radical density peaked (2 × 1020 m–3 at 80 Pa. The density quickly decreased with increasing distance from the glowing plasma despite a rather large drift velocity. The dissociation fraction showed similar behavior, except that the maximum was obtained at somewhat lower pressure. The results were explained by rather intense surface recombination of radicals.

  13. Enhanced toroidal flow stabilization of edge localized modes with increased plasma density

    Science.gov (United States)

    Cheng, Shikui; Zhu, Ping; Banerjee, Debabrata

    2017-09-01

    Toroidal flow alone is generally thought to have an important influence on tokamak edge pedestal stability, even though theoretical analysis often predicts merely a weak stabilizing effect of toroidal flow on the edge localized modes (ELMs) in experimental parameter regimes. For the first time, we find from two-fluid MHD calculations that such a stabilization, however, can be significantly enhanced by increasing the edge plasma density. Our finding resolves a long-standing mystery whether or how toroidal rotation can indeed have an effective influence on ELMs, and explains why the ELM mitigation and suppression by toroidal rotation are more favorably achieved in higher collisionality regime in recent experiments. The finding suggests a new control scheme on modulating toroidal flow stabilization of ELMs with plasma density, along with a new additional constraint on the optimal level of plasma density for the desired edge plasma conditions.

  14. Modeling of plasma density in the earth's dayside inner magnetosphere

    NARCIS (Netherlands)

    Domrachev, VV; Chugunin, DV

    2002-01-01

    The results of comparison of the model profiles of density, obtained by means of the CDPDM model, with the experimental data of the ISEE-1 satellite for the years 1977-1983 are presented. The hypothesis on the validity of the mirror mapping of the convection boundary relative to the dawn-dusk

  15. Influence of metallic vapours on thermodynamic and transport properties of two-temperature air plasma

    Science.gov (United States)

    Zhong, Linlin; Wang, Xiaohua; Cressault, Yann; Teulet, Philippe; Rong, Mingzhe

    2016-09-01

    The metallic vapours (i.e., copper, iron, and silver in this paper) resulting from walls and/or electrode surfaces can significantly affect the characteristics of air plasma. Different from the previous works assuming local thermodynamic equilibrium, this paper investigates the influence of metallic vapours on two-temperature (2 T) air plasma. The 2 T compositions of air contaminated by Cu, Fe, and Ag are first determined based on Saha's and Guldberg-Waage's laws. The thermodynamic properties (including mass density, specific enthalpy, and specific heat) are then calculated according to their definitions. After determining the collision integrals for each pair of species in air-metal mixtures using the newly published methods and source data, the transport coefficients (including electrical conductivity, viscosity, and thermal conductivity) are calculated for air-Cu, air-Fe, and air-Ag plasmas with different non-equilibrium degree θ (Te/Th). The influences of metallic contamination as well as non-equilibrium degree are discussed. It is found that copper, iron, and silver exist mainly in the form of Cu2, FeO, and AgO at low temperatures. Generally, the metallic vapours increase mass density at most temperatures, reduce the specific enthalpy and specific heat in the whole temperature range, and affect the transport properties remarkably from 5000 K to 20 000 K. The effect arising from the type of metals is little except for silver at certain temperatures. Besides, the departure from thermal equilibrium results in the delay of dissociation and ionization reactions, leading to the shift of thermodynamic and transport properties towards a higher temperature.

  16. Improved-confinement plasmas at high temperature and high beta in the MST RFP

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, B. E. [University of Wisconsin, Madison; Ahn, J. W. [University of Wisconsin, Madison; Almagri, A. F. [University of Wisconsin, Madison; Anderson, J. [University of Wisconsin, Madison; Combs, Stephen Kirk [ORNL; Foust, Charles R [ORNL; Kaufman, M. [University of Wisconsin, Madison

    2009-01-01

    We have increased substantially the electron and ion temperatures, the electron density, and the total beta in plasmas with improved energy confinement in the Madison Symmetric Torus (MST). The improved confinement is achieved with a well-established current profile control technique for reduction of magnetic tearing and reconnection. A sustained ion temperature > 1 keV is achieved with intensified reconnection-based ion heating followed immediately by current profile control. In the same plasmas, the electron temperature reaches 2 keV, and the electron thermal diffusivity drops to about 2 m(2) s(-1). The global energy confinement time is 12 ms. This and the reported temperatures are the largest values yet achieved in the reversed-field pinch (RFP). These results were attained at a density similar to 10(19) m(-3). By combining pellet injection with current profile control, the density has been quadrupled, and total beta has nearly doubled to a record value of about 26%. The Mercier criterion is exceeded in the plasma core, and both pressure-driven interchange and pressure-driven tearing modes are calculated to be linearly unstable, yet energy confinement is still improved. Transient momentum injection with biased probes reveals that global momentum transport is reduced with current profile control. Magnetic reconnection events drive rapid momentum transport related to large Maxwell and Reynolds stresses. Ion heating during reconnection events occurs globally, locally, or not at all, depending on which tearing modes are involved in the reconnection. To potentially augment inductive current profile control, we are conducting initial tests of current drive with lower-hybrid and electron-Bernstein waves.

  17. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    CERN Document Server

    Reames, Donald V

    2016-01-01

    Thirty years ago Breneman and Stone observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or "impulsive" show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ~1000 for (76<=Z<=82)/O and temperature in the range 2-4 MK. This acceleration is believed to occur in islands of magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated "gradual" SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T < 1.6 MK, while 24% have T ~ 3 MK, the latter suggesting a seed population containing residual impulsive suprathermal ions. Mos...

  18. One-dimensional time-dependent fluid model of a very high density low-pressure inductively coupled plasma

    Science.gov (United States)

    Chaplin, Vernon H.; Bellan, Paul M.

    2015-12-01

    A time-dependent two-fluid model has been developed to understand axial variations in the plasma parameters in a very high density (peak ne≳ 5 ×1019 m-3 ) argon inductively coupled discharge in a long 1.1 cm radius tube. The model equations are written in 1D with radial losses to the tube walls accounted for by the inclusion of effective particle and energy sink terms. The ambipolar diffusion equation and electron energy equation are solved to find the electron density ne(z ,t ) and temperature Te(z ,t ) , and the populations of the neutral argon 4s metastable, 4s resonant, and 4p excited state manifolds are calculated to determine the stepwise ionization rate and calculate radiative energy losses. The model has been validated through comparisons with Langmuir probe ion saturation current measurements; close agreement between the simulated and measured axial plasma density profiles and the initial density rise rate at each location was obtained at pA r=30 -60 mTorr . We present detailed results from calculations at 60 mTorr, including the time-dependent electron temperature, excited state populations, and energy budget within and downstream of the radiofrequency antenna.

  19. The influence of Exciting Frequency on N2 and N+2 Vibrational Temperature of Nitrogen Capacitively Coupled Plasma

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-Jiang; XIN Yu; ZHANG Jie; NING Zhao-Yuan

    2009-01-01

    By using optical emission spectroscopy (OES), N2 and N+2 vibrational temperatures in capacitively coupled plasma discharges with different exciting frequencies are investigated. The vibrational temperatures are acquired by comparing the measured and calculated spectra of selected transitions with a least-square procedure. It is found that 512 and N+2 vibrational temperatures almost increase linearly with increasing exciting frequency up to 23 MHz, then increase slowly or even decrease. The pressure corresponding to the maximum point of N2 vibrational temperature decreases with the increasing exciting frequency. These experimental phenomena are attributed to the increasing electron density, whereas the electron temperature decreases with exciting frequency rising.

  20. Performance of water and hybrid stabilized electric arcs: the impact of dependence of radiation losses and plasma density on pressure

    Science.gov (United States)

    Jeništa, J.; Bartlová, M.; Aubrecht, V.

    2006-10-01

    Processes in the worldwide unique type of thermal plasma generator with water vortex stabilization and combined stabilization of arc by argon flow and water vortex have been numerically studied. Two-dimensional axisymmetric numerical model assumes laminar and compressible plasma flow in the state of local thermodynamic equilibrium. The calculation domain includes the arc discharge area between the near-cathode region and the outlet nozzle of the plasma torch. Radiation losses from the arc are calculated by the partial characteristics method for atmospheric pressure water and argon-water discharges. Thermal, electrical and fluid-dynamic characteristics of such arcs have been studied for the range of currents 150÷600 A under the assumption that radiation losses and plasma density depend linearly on pressure. It was proved that, taking this dependence into account, plasma velocity decrease while power losses from the arc by radiation and radial conduction increase with current. Outlet plasma temperature as well as electric potential drop remain practically unchanged.

  1. Plasma Density and Radio Echoes in the Magnetosphere

    Science.gov (United States)

    Calvert, W.

    1995-01-01

    This project provided a opportunity to study a variety of interesting topics related to radio sounding in the magnetosphere. The results of this study are reported in two papers which have been submitted for publication in the Journal of Geophysical Research and Radio Science, and various aspects of this study were also reported at meetings of the American Geophysical Union (AGU) at Baltimore, Maryland and the International Scientific Radio Union (URSI) at Boulder, Colorado. The major results of this study were also summarized during a one-day symposium on this topic sponsored by Marshall Space Flight Center in December 1994. The purpose of the study was to examine the density structure of the plasmasphere and determine the relevant mechanisms for producing radio echoes which can be detected by a radio sounder in the magnetosphere. Under this study we have examined density irregularities, biteouts, and outliers of the plasmasphere, studied focusing, specular reflection, ducting, and scattering by the density structures expected to occur in the magnetosphere, and predicted the echoes which can be detected by a magnetospheric radio sounder.

  2. Material for electrodes of low temperature plasma generators

    Science.gov (United States)

    Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich

    2008-12-09

    Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron: 3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, and municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

  3. Molecular Nitrogen Vibrational Temperature in an Inductively Coupled Plasma

    Institute of Scientific and Technical Information of China (English)

    康正德; 蒲以康

    2002-01-01

    Using a technique applied previously to vibrationally excited molecular nitrogen (N*2) in the region of daytime and nighttime aurora, the emission intensity of the N2 second positive band system in an inductively coupled plasma (ICP) has been analysed and the vibrational temperature of nitrogen molecules in the ICP is thus determined. The result shows that the vibrational temperature increases with the increase of the neutral gas pressure from 0.04Pa to 10Pa, then decreases with the further increase of the pressure from 10Pa to 100Pa. Also,this is explained by using the Boltzmann relation between the vibrational temperature and the concentration of the vibrationally excited N*2(X1∑+g ) molecules.

  4. On bias of kinetic temperature measurements in complex plasmas

    DEFF Research Database (Denmark)

    Kantor, M.; Moseev, D.; Salewski, Mirko

    2014-01-01

    The kinetic temperature in complex plasmas is often measured using particle tracking velocimetry. Here, we introduce a criterion which minimizes the probability of faulty tracking of particles with normally distributed random displacements in consecutive frames. Faulty particle tracking results...... in a measurement bias of the deduced velocity distribution function and hence the deduced kinetic temperature. For particles with a normal velocity distribution function, mistracking biases the obtained velocity distribution function towards small velocities at the expense of large velocities, i.e., the inferred...... velocity distribution is more peaked and its tail is less pronounced. The kinetic temperature is therefore systematically underestimated in measurements. We give a prescription to mitigate this type of error....

  5. Low-Temperature Nitriding of Pure Titanium by using Hollow Cathode RF-DC Plasma

    Science.gov (United States)

    Windajanti, J. M.; S, D. J. Djoko H.; Abdurrouf

    2017-05-01

    Pure titanium is widely used for the structures and mechanical parts due to its high strength, low density, and high corrosion resistance. Unfortunately, titanium products suffer from low hardness and low wear resistance. Titanium’s surface can be modified by nitriding process to overcome such problems, which is commonly conducted at high temperature. Here, we report the low-temperature plasma nitriding process, where pure titanium was utilized by high-density RF-DC plasma combined with hollow cathode device. To this end, a pure titanium plate was set inside a hollow tube placed on the cathode plate. After heating to 450 °C, a pre-sputtering process was conducted for 1 hour to remove the oxide layer and activate the surface for nitriding. Plasma nitriding using N2/H2 gasses was performed in 4 and 8 hours with the RF voltage of 250 V, DC bias of -500 to -600 V, and gas pressure of 75 to 30 Pa. To study the nitriding mechanism as well as the role of hollow cathode, the nitrided specimen was characterized by SEM, EDX, XRD, and micro-hardness equipment. The TiN compound was obtained with the diffusion zone of nitrogen until 5 μm thickness for 4 hours nitriding process, and 8 μm for 8 hours process. The average hardness also increased from 300 HV in the untreated specimen to 624 HV and 792 HV for 4 and 8 hours nitriding, respectively.

  6. Simultaneous measurement of electron and heavy particle temperatures in He laser-induced plasma by Thomson and Rayleigh scattering

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K.; Mendys, A.; Zawadzki, W. [Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pokrzywka, B. [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)

    2013-04-01

    Thomson and Rayleigh scattering methods were applied to quantify the electron and heavy particle temperatures, as well as electron number density, in a laser spark in helium at atmospheric pressure. Plasma was created using 4.5 ns, 25 mJ pulses from Nd:YAG laser at 532 nm. Measurements, performed for the time interval between 20 ns and 800 ns after breakdown, show electron density and temperature to decrease from 7.8 Multiplication-Sign 10{sup 23} m{sup -3} to 2.6 Multiplication-Sign 10{sup 22} m{sup -3} and from 95 900 K to 10 350 K, respectively. At the same time, the heavy particle temperature drops from only 47 000 K down to 4100 K which indicates a two temperature plasma out of local isothermal equilibrium.

  7. Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

    Science.gov (United States)

    Zare, S.; Yazdani, E.; Rezaee, S.; Anvari, A.; Sadighi-Bonabi, R.

    2015-04-01

    Propagation of a Gaussian x-ray laser beam has been analyzed in collisionless thermal quantum plasma with considering a ramped density profile. In this density profile due to the increase in the plasma density, an earlier and stronger self-focusing effect is noticed where the beam width oscillates with higher frequency and less amplitude. Moreover, the effect of the density profile slope and the initial plasma density on the laser propagation has been studied. It is found that, by increasing the initial density and the ramp slope, the laser beam focuses faster with less oscillation amplitude, smaller laser spot size and more oscillations. Furthermore, a comparison is made among the laser self-focusing in thermal quantum plasma, cold quantum plasma and classical plasma. It is realized that the laser self-focusing in the quantum plasma becomes stronger in comparison with the classical regime.

  8. Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel

    Directory of Open Access Journals (Sweden)

    Sonu Sen

    2014-01-01

    Full Text Available In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have numerical appreciation of the results the propagation equation for plasma is solved using the fourth order Runge-Kutta method for the initial plane wave front of the beam, using boundary conditions. The spot size of the laser beam decreases as the beam penetrates into the plasma and significantly adds self-focusing in plasma. This causes the laser beam to become more focused by reduction of diffraction effect, which is an important phenomenon in inertial confinement fusion and also for the understanding of self-focusing of laser pulses. Numerical computations are presented and discussed in the form of graphs for typical parameters of laser-plasma interaction.

  9. Non-equilibrium in low-temperature plasmas

    Science.gov (United States)

    Taccogna, Francesco; Dilecce, Giorgio

    2016-11-01

    The wide range of applications of cold plasmas originates from their special characteristic of being a physical system out of thermodynamic equilibrium. This property enhances its reactivity at low gas temperature and allows to obtain macroscopic effects with a moderate energy consumption. In this review, the basic concepts of non-equilibrium in ionized gases are treated by showing why and how non-equilibrium functions of the degrees of freedom are formed in a variety of natural and man-made plasmas with particular emphasis on the progress made in the last decade. The modern point of view of a molecular basis of non-equilibrium and of a state-to-state kinetic approach is adopted. Computational and diagnostic techniques used to investigate the non-equilibrium conditions are also surveyed.

  10. Hole boring velocity measurements in near critical density plasmas by a CO2 laser pulse

    Science.gov (United States)

    Gong, Chao; Tochitsky, Sergei; Pigeon, Jeremy; Joshi, Chan

    2014-10-01

    Measurements of plasma dynamics during the interaction of a high-power laser pulse with an above critical density plasma is important for understanding absorption, transport and particle acceleration mechanisms. An important process that affects these mechanisms is hole boring occurring at the critical density because of the radiation pressure of the laser pulse. Yet, no systematic measurements of the hole boring velocity's (vhb) dependence on laser intensity (I) have been made. In this talk, we present experimental results of vhb in near critical density plasmas produced by CO2 laser as a function of I in the range of 1*1015 to 1.6*1016 W/cm2. A novel four frame Mach-Zehnder interferometer using a 1 ps, 532 nm probe laser pulse was developed to record the evolution of the plasma density profile and the motion of the near critical density layer. Using this diagnostic, we observed the motion of the steepened plasma profile due to the incident, time-structured CO2 laser pulse. Experimental results show the hole boring velocity increases from 0.004c to 0.007c as the laser intensity is increased from 1*1015 to 1.6*1016 W/cm2. This work is supported by DOE grant DE-FG02-92-ER40727, NSF grant PHY-0936266 at UCLA.

  11. Validation of improved Multi-Mode model for density, temperature and toroidal rotation profiles using PTRANSP simulations

    Science.gov (United States)

    Luo, L.; Bateman, G.; Kritz, A. H.; Pankin, A. Y.; Rafiq, T.; McCune, D. C.; Budny, R. V.

    2010-11-01

    Advances in the Multi-Mode model include an improved Weiland model for the ITG and TEM modes [1] and a new model for the drift resistive inertial ballooning modes (DRIBM) [2]. Advances in the PTRANSP code include an improved algorithm for the particle density evolution. Validation studies are carried out for the improved Multi-Mode model using PTRANSP simulations. In order to allow tight coupling with stiff transport models, all of the transport equations for main ion and impurity density profiles as well as electron temperature, ion temperature and toroidal angular rotation profiles are advanced simultaneously by the PTRANSP solver. The Plasma State connects the new solver to the rest of PTRANSP. The solver uses several techniques to control numerical stability. Simulation results for density, temperature and rotation frequency profiles are compared with experimental data for L-mode and H-mode discharges. [4pt] [1] J.Weiland et al., Nucl. Fusion 49 (2009) 965933; F.D. Halpern et al., Phys. Plasmas 15 (2008) 065033 [2] T. Rafiq et al., to appear in Phys. Plasmas (2010)

  12. Optimum temperature on corrosion resistance for plasma ion nitrided 316L stainless steel in sea water solution

    Science.gov (United States)

    Chong, Sang-Ok; Kim, Seong-Jong

    2017-01-01

    The aim of this research is to investigate the optimum plasma ion nitriding temperature on corrosion resistance in natural sea water for plasma ion nitrided 316L stainless steel. Plasma ion nitriding was conducted at different temperatures of 350, 400, 450, and 500 °C with a mixture of 75% of nitrogen and 25% of hydrogen during 10 h. In conclusion of anodic polarization test, a wide passive potential region and a high corrosion potential were observed at a plasma ion nitriding temperature of 450 °C. Moreover, relatively less damage depth and clean surface micrographs were observed at 450 °C as results of observation of three-dimensional (3D) microscope and scanning electron microscope (SEM) after polarization experiments. In addition, higher corrosion potential and lower corrosion current density were indicated at plasma ion nitrided samples than the value of untreated substrate after Tafel analysis. Hence, plasma ion nitrided at 450 °C in sea water solution represented optimum corrosion resistance among the all the plasma ion nitriding temperature parameters.

  13. Ionic Wind Phenomenon and Charge Carrier Mobility in Very High Density Argon Corona Discharge Plasma

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.

    2014-04-01

    Wind ions phenomenon has been observed in the high density argon corona discharge plasma. Corona discharge plasma was produced by point to plane electrodes and high voltage DC. Light emission from the recombination process was observed visually. The light emission proper follow the electric field lines that occur between point and plane electrodes. By using saturation current, the mobilities of non-thermal electrons and ions have been obtained in argon gas and liquid with variation of density from 2,5 1021 to 2 1022 cm-3. In the case of ions, we found that the behaviour of the apparent mobility inversely proportional to the density or follow the Langevin variation law. For non-thermal electron, mobility decreases and approximately follows a variation of Langevin type until the density <= 0,25 the critical density of argon.

  14. Development of a High Energy Density Capacitor for Plasma Thrusters.

    Science.gov (United States)

    1980-10-01

    sparcity of data results in wide confidence bands around the plotted reliability versus discharge life curve. Within the 90% confidence limits, lines...point a 4 mm, *C 161 flossing point, IC -70 (viscous liquid) Pour point. *C -69 Flash point (open cup), IF 330 (t66C) File point. IF 353 (112?C...temperature. confidence bands around the plotted relia- bility vs. discharge-life curve. Within The rear lid is welded to the can once the 90% confidence limits

  15. Three-temperature plasma shock solutions with gray radiation diffusion

    Science.gov (United States)

    Johnson, B. M.; Klein, R. I.

    2017-03-01

    The effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron-ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  16. Modelling of the reactive sputtering process with non-uniform discharge current density and different temperature conditions

    Science.gov (United States)

    Vašina, P; Hytková, T; Eliáš, M

    2009-05-01

    The majority of current models of the reactive magnetron sputtering assume a uniform shape of the discharge current density and the same temperature near the target and the substrate. However, in the real experimental set-up, the presence of the magnetic field causes high density plasma to form in front of the cathode in the shape of a toroid. Consequently, the discharge current density is laterally non-uniform. In addition to this, the heating of the background gas by sputtered particles, which is usually referred to as the gas rarefaction, plays an important role. This paper presents an extended model of the reactive magnetron sputtering that assumes the non-uniform discharge current density and which accommodates the gas rarefaction effect. It is devoted mainly to the study of the behaviour of the reactive sputtering rather that to the prediction of the coating properties. Outputs of this model are compared with those that assume uniform discharge current density and uniform temperature profile in the deposition chamber. Particular attention is paid to the modelling of the radial variation of the target composition near transitions from the metallic to the compound mode and vice versa. A study of the target utilization in the metallic and compound mode is performed for two different discharge current density profiles corresponding to typical two pole and multipole magnetics available on the market now. Different shapes of the discharge current density were tested. Finally, hysteresis curves are plotted for various temperature conditions in the reactor.

  17. Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources

    Science.gov (United States)

    Odorici, F.; Malferrari, L.; Montanari, A.; Rizzoli, R.; Mascali, D.; Castro, G.; Celona, L.; Gammino, S.; Neri, L.

    2016-02-01

    Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to "screen" the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

  18. Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Odorici, F., E-mail: fabrizio.odorici@bo.infn.it; Malferrari, L.; Montanari, A. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); Rizzoli, R. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); CNR–Istituto per la Microelettronica ed i Microsistemi, Via Gobetti 101, 40129 Bologna (Italy); Mascali, D.; Castro, G.; Celona, L.; Gammino, S.; Neri, L. [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy)

    2016-02-15

    Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to “screen” the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

  19. Plasma behaviour at high beta and high density in the Madison Symmetric Torus RFP

    Energy Technology Data Exchange (ETDEWEB)

    Wyman, M. [University of Wisconsin, Madison; Chapman, B. E. [University of Wisconsin, Madison; Ahn, J. W. [University of Wisconsin, Madison; Almagri, A. F. [University of Wisconsin, Madison; Anderson, J. [University of Wisconsin, Madison; Bonomo, F. [Consorzio RFX, Italy; Bower, D L [University of California, Los Angeles; Combs, Stephen Kirk [ORNL; Craig, D. [University of Wisconsin, Madison; Foust, Charles R [ORNL

    2009-01-01

    Pellet fuelling of improved confinement Madison Symmetric Torus (MST) plasmas has resulted in high density and high plasma beta. The density in improved confinement discharges has been increased fourfold, and a record plasma beta (beta(tot) = 26%) for the improved confinement reversed-field pinch (RFP) has been achieved. At higher beta, a new regime for instabilities is accessed in which local interchange and global tearing instabilities are calculated to be linearly unstable, but experimentally, no severe effect, e. g., a disruption, is observed. The tearing instability, normally driven by the current gradient, is driven by the pressure gradient in this case, and there are indications of increased energy transport ( as compared with low-density improved confinement). Pellet fuelling is also compared with enhanced edge fuelling of standard confinement RFP discharges for the purpose of searching for a density limit in MST. In standard-confinement discharges, pellet fuelling peaks the density profile where edge fuelling cannot, but transport appears unchanged. For a limited range of plasma current, MST discharges with edge fuelling are constrained to a maximum density corresponding to the Greenwald limit. This limit is surpassed in pellet-fuelled improved confinement discharges.

  20. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature

    Science.gov (United States)

    Balasubramanian, C.; Joseph, B.; Orpe, PB; Saini, NL; Mukherjee, S.; Dziedzic-Kocurek, K.; Stanek, J.; Di Gioacchino, D.; Marcelli, A.

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  1. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, G. T. Road, Phagwara, Punjab 144411 (India)

    2014-07-15

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect.

  2. Metastable argon atom density in complex argon/acetylene plasmas determined by means of optical absorption and emission spectroscopy

    Science.gov (United States)

    Sushkov, Vladimir; Herrendorf, Ann-Pierra; Hippler, Rainer

    2016-10-01

    Optical emission and absorption spectroscopy has been utilized to investigate the instability of acetylene-containing dusty plasmas induced by growing nano-particles. The density of Ar(1s5) metastable atoms was derived by two methods: tunable diode laser absorption spectroscopy and with the help of the branching ratio method of emitted spectral lines. Results of the two techniques agree well with each other. The density of Ar(1s3) metastable atoms was also measured by means of optical emission spectroscopy. The observed growth instability leads to pronounced temporal variations of the metastable and other excited state densities. An analysis of optical line ratios provides evidence for a depletion of free electrons during the growth cycle but no indication for electron temperature variations.

  3. Observations of plasma density structures in association with the passage of traveling convection vortices and the occurrence of large plasma jets

    Directory of Open Access Journals (Sweden)

    C. E. Valladares

    Full Text Available We report important results of the first campaign specially designed to observe the formation and the initial convection of polar cap patches. The principal instrumentation used in the experiments comprised the EISCAT, the Sondrestrom, and the Super DARN network of radars. The experiment was conducted on February 18, 1996 and was complemented with additional sensors such as the Greenland chain of magnetometers and the WIND and IMP-8 satellites. Two different types of events were seen on this day, and in both events the Sondrestrom radar registered the formation and evolution of large-scale density structures. The first event consisted of the passage of traveling convection vortices (TCV. The other event occurred in association with the development of large plasma jets (LPJ embedded in the sunward convection part of the dusk cell. TCVs were measured, principally, with the magnetometers located in Greenland, but were also confirmed by the line-of-sight velocities from the Sondrestrom and SuperDARN radars. We found that when the magnetic perturbations associated with the TCVs were larger than 100 nT, then a section of the high-latitude plasma density was eroded by a factor of 2. We suggest that the number density reduction was caused by an enhancement in the O+ recombination due to an elevated Ti, which was produced by the much higher frictional heating inside the vortex. The large plasma jets had a considerable (>1000 km longitudinal extension and were 200-300 km in width. They were seen principally with the Sondrestrom, and SuperDARN radars. Enhanced ion temperature (Ti was also observed by the Sondrestrom and EISCAT radars. These channels of high Ti were exactly collocated with the LPJs and some of them with regions of eroded plasma number density. We suggest that the LPJs bring less dense plasma from later local times. However, the recent time history of the plasma flow is important to define the

  4. Density of Liquid Steel over Temperature Range of 1 803-1 873 K

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang

    2004-01-01

    The density of three kinds of liquid steel was measured by a modified sessile drop method over the temperature range of 1 803-1 873 K. It is found that the density of liquid steels decreases with increasing temperature and carbon content in steel. Both of the density and its absolute temperature coefficient of studied steels are smaller than the literature values of pure iron. The molar volume of the steels increases with increasing temperature.

  5. Radial convection of finite ion temperature, high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Wiesenberger, M.; Madsen, Jens; Kendl, Alexander

    2014-01-01

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line...... with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very...

  6. Ion temperature gradient turbulence in helical and axisymmetric RFP plasmas

    CERN Document Server

    Predebon, I

    2015-01-01

    Turbulence induced by the ion temperature gradient (ITG) is investigated in the helical and axisymmetric plasma states of a reversed field pinch device by means of gyrokinetic calculations. The two magnetic configurations are systematically compared, both linearly and nonlinearly, in order to evaluate the impact of the geometry on the instability and its ensuing transport, as well as on the production of zonal flows. Despite its enhanced confinement, the high-current helical state demonstrates a lower ITG stability threshold compared to the axisymmetric state, and ITG turbulence is expected to become an important contributor to the total heat transport.

  7. Microwave frequency sweep interferometer for plasma density measurements in ECR ion sources: Design and preliminary results

    Science.gov (United States)

    Torrisi, Giuseppe; Mascali, David; Neri, Lorenzo; Leonardi, Ornella; Sorbello, Gino; Celona, Luigi; Castro, Giuseppe; Agnello, Riccardo; Caruso, Antonio; Passarello, Santi; Longhitano, Alberto; Isernia, Tommaso; Gammino, Santo

    2016-02-01

    The Electron Cyclotron Resonance Ion Sources (ECRISs) development is strictly related to the availability of new diagnostic tools, as the existing ones are not adequate to such compact machines and to their plasma characteristics. Microwave interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for plasma density measurement in hostile environment. Interferometry in ECRISs is a challenging task mainly due to their compact size. The typical density of ECR plasmas is in the range 1011-1013 cm-3 and it needs a probing beam wavelength of the order of few centimetres, comparable to the chamber radius. The paper describes the design of a microwave interferometer developed at the LNS-INFN laboratories based on the so-called "frequency sweep" method to filter out the multipath contribution in the detected signals. The measurement technique and the preliminary results (calibration) obtained during the experimental tests will be presented.

  8. Bright gamma-rays from betatron resonance acceleration in near critical density plasma

    CERN Document Server

    Liu, B; Wu, D; Liu, J; Chen, C E; Yan, X Q; He, X T

    2013-01-01

    We show that electron betatron resonance acceleration by an ultra-intense ultra-short laser pulse in a near critical density plasma works as a high-brightness gamma-ray source. Compared with laser plasma X-ray sources in under-dense plasma, near critical density plasma provides three benefits for electron radiation: more radiation electrons, larger transverse amplitude, and higher betatron oscillation frequency. Three-dimensional particle-in-cell simulations show that, by using a 7.4J laser pulse, 8.3mJ radiation with critical photon energy 1MeV is emitted. The critical photon energy $E_c$ increases with the incident laser energy %faster than a linear relation. $W_I$ as $E_c \\propto W_I^{1.5}$, and the corresponding photon number is proportional to $W_I$. A simple analytical synchrotron-like radiation model is built, which can explain the simulation results.

  9. Microwave frequency sweep interferometer for plasma density measurements in ECR ion sources: Design and preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, Giuseppe [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University Mediterranea of Reggio Calabria, Reggio Calabria (Italy); Mascali, David; Neri, Lorenzo; Leonardi, Ornella; Celona, Luigi; Castro, Giuseppe; Agnello, Riccardo; Caruso, Antonio; Passarello, Santi; Longhitano, Alberto; Gammino, Santo [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Sorbello, Gino [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University of Catania, Catania, Italy and INFN-LNS, Catania (Italy); Isernia, Tommaso [University Mediterranea of Reggio Calabria, Reggio Calabria (Italy)

    2016-02-15

    The Electron Cyclotron Resonance Ion Sources (ECRISs) development is strictly related to the availability of new diagnostic tools, as the existing ones are not adequate to such compact machines and to their plasma characteristics. Microwave interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for plasma density measurement in hostile environment. Interferometry in ECRISs is a challenging task mainly due to their compact size. The typical density of ECR plasmas is in the range 10{sup 11}–10{sup 13} cm{sup −3} and it needs a probing beam wavelength of the order of few centimetres, comparable to the chamber radius. The paper describes the design of a microwave interferometer developed at the LNS-INFN laboratories based on the so-called “frequency sweep” method to filter out the multipath contribution in the detected signals. The measurement technique and the preliminary results (calibration) obtained during the experimental tests will be presented.

  10. Investigation of physical processes limiting plasma density in H-mode on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R.; Mahdavi, M.A. [General Atomics, San Diego, CA (United States); Jernigan, T.C. [Oak Ridge National Lab., TN (United States)] [and others

    1996-12-01

    A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmas was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks.

  11. GROWTH PROCESS OF LOW-TEMPERATURE PLASMA-NITRIDING LAYER ON AUSTENITIC STAINLESS STEEL

    Institute of Scientific and Technical Information of China (English)

    Z.W.Yu; L.Wang; X.L.Xu; J.B.Qiang

    2004-01-01

    The growth process of low-temperature plasma-nitriding layer was investigated by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The layer is composed of expanded fcc phase(γN),whose lattice parameter of the layer increases with process time resulting from increasing the nitrogen content.The layer hardness increases gradually with nitrogen content.The high slip band density on the layer surface observed in situ by SEM shows that the surface yield occurs when supersaturated nitrogen content in the layer attains to some value,which is also responsible for the increase in layer hardness.

  12. Iterative noise removal from temperature and density profiles in the TJ-II Thomson scattering

    Energy Technology Data Exchange (ETDEWEB)

    Farias, G., E-mail: gonzalo.farias@ucv.cl [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile); Dormido-Canto, S., E-mail: sebas@dia.uned.es [Departamento de Informática y Automática, UNED, 28040 Madrid (Spain); Vega, J., E-mail: jesus.vega@ciemat.es [Asociación EURATOM/CIEMAT para Fusión, Avd. Complutense 22, 28040 Madrid (Spain); Santos, M., E-mail: msantos@ucm.es [Departamento de Arquitectura de Computadores y Automática, Universidad Complutense de Madrid, 28040 Madrid (Spain); Pastor, I., E-mail: ignacio.pastor@ciemat.es [Asociación EURATOM/CIEMAT para Fusión, Avd. Complutense 22, 28040 Madrid (Spain); Fingerhuth, S., E-mail: sebastian.fingerhuth@ucv.cl [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile); Ascencio, J., E-mail: j_ascencio21@hotmail.com [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile)

    2014-05-15

    TJ-II Thomson Scattering diagnostic provides temperature and density profiles of plasma. The CCD camera acquires images that are corrupted with some kind of noise called stray-light. This noise degrades both image contrast and measurement accuracy, which could produce unreliable profiles of the diagnostic. So far, several approaches have been applied in order to decrease the noise in the TJ-II Thomson scattering images. Since the presence of the noise is not global but located in some particular regions of the image, advanced processing techniques are needed. However such methods require of manual fine-tuning of parameters to reach a good performance. In this contribution, an iterative image processing approach is applied in order to reduce the stray light effects in the images of the TJ-II Thomson scattering diagnostic. The proposed solution describes how the noise can be iteratively reduced in the images when a key parameter is automatically adjusted during the iterative process.

  13. Cleaning of SiC surfaces by low temperature ECR microwave hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Huang Lingqin; Zhu Qiaozhi; Gao Mingchao [School of Electronic Science and Technology, Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, 116024 (China); Qin Fuwen [State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), Dalian University of Technology, 116024 (China); Wang Dejun, E-mail: dwang121@dlut.edu.cn [School of Electronic Science and Technology, Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, 116024 (China)

    2011-09-15

    N-type 4H-SiC (0 0 0 1) surfaces were cleaned by low temperature hydrogen plasma in electronic cyclotron resonance (ECR) microware plasma system. The effects of the hydrogen plasma treatment (HPT) on the structure, chemical and electronic properties of surfaces were characterized by in situ reflection high energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). The RHEED results indicate that the structures of the films are strongly dependent on the treatment temperature and time. Significant improvements in quality of 4H-SiC films can be obtained with the temperature ranging from 200 deg. C to 700 deg. C for an appropriate treatment period. The XPS results show that the surface oxygen is greatly reduced and the carbon contamination is completely removed from the 4H-SiC surfaces. The hydrogenated SiC surfaces exhibit an unprecedented stability against oxidation in the air. The surface Fermi level moves toward the conduction band in 4H-SiC after the treatment indicating an unpinning Fermi level with the density of surfaces states as low as 8.09 x 10{sup 10} cm{sup -2} eV{sup -1}.

  14. [Plasma temperature of white-eye hexagonal pattern in dielectric barrier discharge].

    Science.gov (United States)

    Zhao, Yang; Dong, Li-fang; Fu, Hong-yan

    2015-01-01

    By using the water-electrode discharge experimental setup, the white-eye hexagonal pattern is firstly observed and investigated in the dielectric barrier discharge with the mixture of argon and air whose content can be varied whenever necessary, and the study shows that the white-eye cell is an interleaving of three different hexagonal sub-structures: the spot, the ring, and the halo. The white-eye hexagonal pattern has the excellent discharge stability and sustainability during the experiment. Pictures recorded by ordinary camera with long exposure time in the same argon content condition show that the spot, the ring, and the halo of the white-eye hexagonal pattern have different brightness, which may prove that their plasma states are different. And, it is worth noting that there are obvious differences not only on the brightness but also on the color of the white-eye cell in conditions of different argon content, which shows that its plasma state also changed with the variation of the argon content. The white-eye hexagonal pattern is observed at a lower applied voltage so that the temperature of the water electrodes almost keeps unchanged during the whole experiment, which is advantageous for the long term stable measurement. The plasma state will not be affected by the temperature of the electrodes during the continuous discharge. Based on the above phenomena, plasma temperatures of the spot, the ring, and the halo in white-eye hexagonal pattern including molecule vibrational temperature and variations of electron density at different argon content are investigated by means of optical emission spectroscopy (OES). The emission spectra of the N2 second positive band(C3Πu-->B3Πg)are measured, and the molecule vibrational temperature of the spot, the ring, and the halo of the white-eye hexagonal pattern are calculated by the emission intensities. Furthermore, emission spectra of Ar I (2P2-->1S5)is collected and the changes of its width with different argon

  15. Density-Gradient-Driven trapped-electron-modes in improved-confinement RFP plasmas

    Science.gov (United States)

    Duff, James

    2016-10-01

    Short wavelength density fluctuations in improved-confinement MST plasmas exhibit multiple features characteristic of the trapped-electron-mode (TEM), strong evidence that drift wave turbulence emerges in RFP plasmas when transport associated with MHD tearing is reduced. Core transport in the RFP is normally governed by magnetic stochasticity stemming from long wavelength tearing modes that arise from current profile peaking. Using inductive control, the tearing modes are reduced and global confinement is increased to values expected for a comparable tokamak plasma. The improved confinement is associated with a large increase in the pressure gradient that can destabilize drift waves. The measured density fluctuations have frequencies >50 kHz, wavenumbers k_phi*rho_sglobal tearing modes. Their amplitude increases with the local density gradient, and they exhibit a density-gradient threshold at R/L_n 15, higher than in tokamak plasmas by R/a. the GENE code, modified for RFP equilibria, predicts the onset of microinstability for these strong-gradient plasma conditions. The density-gradient-driven TEM is the dominant instability in the region where the measured density fluctuations are largest, and the experimental threshold-gradient is close to the predicted critical gradient for linear stability. While nonlinear analysis shows a large Dimits shift associated with predicted strong zonal flows, the inclusion of residual magnetic fluctuations causes a collapse of the zonal flows and an increase in the predicted transport to a level close to the experimentally measured heat flux. Similar circumstances could occur in the edge region of tokamak plasmas when resonant magnetic perturbations are applied for the control of ELMs. Work supported by US DOE.

  16. Quasi-optical design for systems to diagnose the electron temperature and density fluctuations on EAST

    Science.gov (United States)

    Cao, Qifo; Liu, Yong; Zhao, Hailin; Zhou, Tianfu; Ti, Ang; Hu, Liqun

    2016-11-01

    A system to simultaneously diagnose the electron temperature and density fluctuations is proposed for Experimental Advanced Superconducting Tokamak device. This system includes a common quasi-optical antenna, a correlation electron cyclotron emission (CECE) system that is used to measure the electron temperature fluctuations and a Doppler backscattering (DBS) system that is used to measure the electron density fluctuations. The frequency range of the proposed CECE system is 108-120 GHz, and this corresponds to a radial coverage of normalized radius ((R - R0)/a, R0 = 1850 mm, a = 450 mm) from 0.2 to 0.67 for the plasma operation with a toroidal magnetic field of 2.26 T. This paper focuses on the design of the quasi-optical antenna and aims at optimizing the poloidal resolution for different frequency bands. An optimum result gives the beam radius for the CECE system of 13-15 mm and this corresponds to a wave number range of kθ < 2.4 cm-1. The beam radius is 20-30 mm for V band (50-75 GHz) and 15-20 mm for W band (75-110 GHz).

  17. Plasma diagnostic approach for the low-temperature deposition of silicon quantum dots using dual frequency PECVD

    Science.gov (United States)

    Sahu, B. B.; Yin, Y.; Lee, J. S.; Han, Jeon G.; Shiratani, M.

    2016-10-01

    Although studies of silicon (Si) quantum dots (QDs) were started just a few years ago, progress is noteworthy concerning unique film properties and their potential application for devices. In particular, relating to the Si QD process optimization, it is essential to control the deposition environment by studying the role of plasma parameters and atomic and molecular species in the process plasmas. In this work, we report on advanced material processes for the low-temperature deposition of Si QDs by utilizing radio frequency and ultrahigh frequency dual frequency (DF) plasma enhanced chemical vapor deposition (PECVD) method. DF PECVD can generate a very high plasma density in the range ~9  ×  1010 cm-3 to 3.2  ×  1011 cm-3 at a very low electron temperature (T e) ~ 1.5 to 2.4 eV. The PECVD processes, using a reactive mixture of H2/SiH4/NH3 gases, are carefully studied to investigate the operating regime and to optimize the deposition parameters by utilizing different plasma diagnostic tools. The analysis reveals that a higher ion flux at a higher plasma density on the substrate is conducive to enhancing the overall crystallinity of the deposited film. Along with high-density plasmas, a high concentration of atomic H and N is simultaneously essential for the high growth rate deposition of Si QDs. Numerous plasma diagnostics methods and film analysis tools are used to correlate the effect of plasma- and atomic-radical parameters on the structural and chemical properties of the deposited Si QD films prepared in the reactive mixtures of H2/SiH4/NH3 at various pressures.

  18. Multi-dimensional collective effects in high-current relativistic beams relevant to High Density Laboratory Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Shvets, Gennady

    2014-05-09

    In summary, an analytical model describing the self-pinching of a relativistic charge-neutralized electron beam undergoing the collisionless Weibel instability in an overdense plasma has been developed. The model accurately predicts the final temperature and size of the self-focused filament. It is found that the final temperature is primarily defined by the total beam’s current, while the filament’s radius is shown to be smaller than the collisionless skin depth in the plasma and primarily determined by the beam’s initial size. The model also accurately predicts the repartitioning ratio of the initial energy of the beam’s forward motion into the magnetic field energy and the kinetic energy of the surrounding plasma. The density profile of the final filament is shown to be a superposition of the standard Bennett pinch profile and a wide halo surrounding the pinch, which contains a significant fraction of the beam’s electrons. PIC simulations confirm the key assumption of the analytic theory: the collisionless merger of multiple current filaments in the course of the Weibel Instability provides the mechanism for Maxwellization of the beam’s distribution function. Deviations from the Maxwell-Boltzmann distribution are explained by incomplete thermalization of the deeply trapped and halo electrons. It is conjectured that the simple expression derived here can be used for understanding collsionless shock acceleration and magnetic field amplification in astrophysical plasmas.

  19. Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density

    Science.gov (United States)

    Gong, Chao

    The interaction of a high-power laser beam with plasma has been explored extensively in the context of laser-driven fusion, plasma-based acceleration of ions and electrons and high energy-density physics. One of the fundamental processes common to all these studies is the penetration of intense light into a dense matter through the hole boring effect and self-induced transparency. Light with a given wavelength lambda will be reflected once the electron density equals the critical electron plasma density nc = 1.1x 1021cm -3 /[lambda(mum)]2. The radiation pressure exerted on the critical density layer is characterized by the ponderomotive force of a focused laser pulse which scales with a laser intensity, I as Ilambda2 Wmum2/cm 2. At Ilambda2 ˜1017 Wmum2/cm2 and above, it becomes possible for the laser pulse not only to steepen the plasma profile but to push the overcritical plasma with ne > nc creating a cavity or a hole in the target. The phenomenon of hole boring, whereby a laser pulse propagates through a reduced density cavity to reach and push the critical density layer, is of importance in fast-ignition fusion because it may allow the laser pulse to deliver its energy closer to the compressed fuel where it can be converted into fast electrons that are needed to ignite a small portion of the fuel. The layer of plasma pushed by the radiation pressure can reflect and accelerate ions via the so called Hole Boring Radiation Pressure Acceleration mechanism. Also the density pile- up in combination with the strong electron heating at the critical density layer can facilitate the formation of a collisionless shock. This shock wave acceleration can produce high energy ion beams with a narrow energy spread. Numerous experiments have been carried out to study dynamics of laser plasma interaction indirectly using solid state targets that are opaque for 1?m laser. However, by using a longer wavelength CO2 laser, lambda = 10.6mum, the critical plasma density is decreased

  20. Comparison of apoprotein B of low density lipoproteins of human interstitial fluid and plasma.

    Science.gov (United States)

    Hong, J L; Pflug, J; Reichl, D

    1984-08-15

    Virtually all apoprotein B (apoB)-containing lipoproteins of the peripheral interstitial fluid of subjects with primary lymphoedema float in the ultracentrifugal field in the density interval 1.019-1.063 g/ml; in this respect they are similar to plasma low-density lipoproteins (LDL). 2. Virtually all apo-B-containing lipoproteins of interstitial fluid migrate in the electrophoretic field with pre-beta mobility; in this respect they are similar to plasma very-low-density lipoproteins. 3. The apoB of lipoproteins of interstitial fluid does not differ in terms of Mr from apoB-100 of human plasma [Kane, Hardman & Paulus (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 2465-2469] as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 4. Both apoB of interstitial fluid and plasma are heterogenous in terms of their charge as determined by isoelectric focusing of their complexes with the nonionic detergent Nonidet P40. ApoB of plasma LDL focuses between pH5.9 and 6.65, and that of interstitial fluid LDL between pH 5.9 and 6.1. Thus the overall charge of apoB of interstitial fluid is more negative than that of its plasma LDL counterpart.

  1. Microwave techniques for electron density measurements in low pressure RF plasmas

    Science.gov (United States)

    Zheltukhin, Viktor; Gafarov, Ildar; Shemakhin, Alexander

    2016-09-01

    Results of the experimental studying of RF plasma jet at low pressure in the range of 10 - 300 Pa is presented. The electron density distribution both in inductive and in capacitive coupled RF discharges was measured at 1.76 MHz and 13.56 MHz consequently. We used three independent microwave diagnostic techniques such as free space (the ``two-frequency'' and ``on the cut-off signal'') and a resonator. It is found that the electron density in the RF plasma jets is by 1-2 orders of magnitude greater than in the decaying plasma jet, and by 1-2 orders of magnitude less than in the RF plasma torch. Thus the RF plasma jet is similar to the additional discharge between the electrodes or the coil and the vacuum chamber walls. As a consequence, the formation of the positive charge sheath near the specimen placed in plasma stream is observed. It is found that the maximum of ionization degree as well as more uniform electron density distribution across the stream is observed in the range of the gas flow rate Gg = 0 . 06 - 0 . 12 g/s and the discharge power Pd = 0 . 5 - 2 . 5 kW. The work was funded by RFBR, according to the research projects No. 16-31-60081 mol_a_dk.

  2. Temperature and Population Density Effects on Locomotor Activity of Musca domestica (Diptera: Muscidae)

    DEFF Research Database (Denmark)

    Schou, T. M.; Faurby, S.; Kjærsgaard, A.

    2013-01-01

    activity was measured for both sexes and at four densities (with mixed sexes) during a full light and dark (L:D) cycle at temperatures ranging from 10 to 40°C. Locomotor activity during daytime increased with temperature at all densities until reaching 30°C and then decreased. High-density treatments...

  3. Low temperature spark plasma sintering of TC4/HA composites

    Institute of Scientific and Technical Information of China (English)

    Huiliang Shao; Lei Cao; Daqian Sun; Zhankui Zhao

    2016-01-01

    Ti6Al4V/hydroxyapatite composites (TC4/HA) have been prepared by high energy ball milling and low temperature spark plasma sintering at 600 °C, 550 °C, 500 °C and 450 °C, respectively. The sintering temperature of the composites was sharply decreased as the result of the activation and surficial modification effects induced from high energy ball milling. The decomposition and reaction of hydro-xyapatite was successfully avoided, which offers the composites superior biocompatibility. The hydro-xyapatite in the composites was distributed in gap uniformly, and formed an ideal network structure. The lowest hardness, compressive strength and Young's modulus of the composites satisfy the requirements of human bone.

  4. High temperature superconductors for fusion at the Swiss Plasma Center

    Science.gov (United States)

    Bruzzone, P.; Wesche, R.; Uglietti, D.; Bykovsky, N.

    2017-08-01

    High temperature superconductors (HTS) may become in future an option for the superconducting magnets of commercial fusion plants. At the Swiss Plasma Center (SPC) the R&D activity toward HTS high current, high field cables suitable for fusion magnets started in 2012 and led in 2015 to the assembly of the first 60 kA, 12 T prototype conductor. The cable concept developed at the SPC is based on the principle of ‘soldered, twisted stacks’ of REBCO tapes. The required number of stacks is assembled in a cored flat cable, cooled by forced flow of supercritical helium. The sample environment of the test facility at SPC has been upgraded with a HTS adapter and a counter-flow heat exchanger to allow testing the HTS sample in a broader range of temperature (4.5 K-50 K) using the existing, NbTi based superconducting transformer and the closed loop refrigerator.

  5. Effect of Radial Density Configuration on Wave Field and Energy Flow in Axially Uniform Helicon Plasma

    Science.gov (United States)

    Chang, Lei; Li, Qingchong; Zhang, Huijie; Li, Yinghong; Wu, Yun; Zhang, Bailing; Zhuang, Zhong

    2016-08-01

    The effect of the radial density configuration in terms of width, edge gradient and volume gradient on the wave field and energy flow in an axially uniform helicon plasma is studied in detail. A three-parameter function is employed to describe the density, covering uniform, parabolic, linear and Gaussian profiles. It finds that the fraction of power deposition near the plasma edge increases with density width and edge gradient, and decays in exponential and “bump-on-tail” profiles, respectively, away from the surface. The existence of a positive second-order derivative in the volume density configuration promotes the power deposition near the plasma core, which to our best knowledge has not been pointed out before. The transverse structures of wave field and current density remain almost the same during the variation of density width and gradient, confirming the robustness of the m=1 mode observed previously. However, the structure of the electric wave field changes significantly from a uniform density configuration, for which the coupling between the Trivelpiece-Gould (TG) mode and the helicon mode is very strong, to non-uniform ones. The energy flow in the cross section of helicon plasma is presented for the first time, and behaves sensitive to the density width and edge gradient but insensitive to the volume gradient. Interestingly, the radial distribution of power deposition resembles the radial profile of the axial component of current density, suggesting the control of the power deposition profile in the experiment by particularly designing the antenna geometry to excite a required axial current distribution. supported by National Natural Science Foundation of China (No. 11405271)

  6. Plasma Efficiency and Losses for pulsed Xe Excimer DBDs at high Power Densities

    Science.gov (United States)

    Paravia, Mark; Meisser, Michael; Heering, Wolfgang

    2009-10-01

    The UV water disinfection for example needs efficient lamps with high power densities. Xe2^* dielectric barrier discharges (DBDs) with phosphor coating can be used due to plasma efficiencies up to 60 % at pulsed electrical power densities of 0.04 W/cm^2 [1]. The power density can be increased by pressure or (operation) frequency. However, the plasma efficiency declines with frequency. We present measurements of the radiant flux for pulsed DBDs made of fused silica as function of pressure and frequency. By calculation of optical losses the plasma efficiency is estimated to be 52 % at 0.07 W/cm^2 but decreases to 34 % at 0.8 W/cm^2. The maximum frequency is pressure dependent and limited due to change-over from homogeneous into filamented mode. In comparison we measured the gas gap voltage and internal plasma current of a pulsed planar DBD for general lighting [2]. This comparison makes it possible to explain the frequency dependence of plasma efficiency and radiant flux. Due to the high frequency the remaining charge density is increased and the discharge becomes a glow discharge. For that reason the typical peak current during ignition drops and explains the declined efficiency by glow phase losses. [4pt] [1] Beleznai, S., et al., JPhysD, 41 (2008) [0pt] [2] Paravia, M., et al., GEC, Dallas, 2008

  7. Dynamics of the spatial electron density distribution of EUV-induced plasmas

    Science.gov (United States)

    van der Horst, R. M.; Beckers, J.; Osorio, E. A.; Banine, V. Y.

    2015-11-01

    We studied the temporal evolution of the electron density distribution in a low pressure pulsed plasma induced by high energy extreme ultraviolet (EUV) photons using microwave cavity resonance spectroscopy (MCRS). In principle, MCRS only provides space averaged information about the electron density. However, we demonstrate here the possibility to obtain spatial information by combining multiple resonant modes. It is shown that EUV-induced plasmas, albeit being a rather exotic plasma, can be explained by known plasma physical laws and processes. Two stages of plasma behaviour are observed: first the electron density distribution contracts, after which it expands. It is shown that the contraction is due to cooling of the electrons. The moment when the density distribution starts to expand is related to the inertia of the ions. After tens of microseconds, the electrons reached the wall of the cavity. The speed of this expansion is dependent on the gas pressure and can be divided into two regimes. It is shown that the acoustic dominated regime the expansion speed is independent of the gas pressure and that in the diffusion dominated regime the expansion depends reciprocal on the gas pressure.

  8. Experiment to measure oxygen opacity at high density and temperature

    Science.gov (United States)

    Keiter, Paul; Mussack, Katie; Orban, Chris; Colgan, James; Ducret, Jean-Eric; Fontes, Christopher J.; Guzik, Joyce Ann; Heeter, Robert F.; Kilcrease, Dave; Le Pennec, Maelle; Mancini, Roberto; Perry, Ted; Turck-Chièze, Sylvaine; Trantham, Matt

    2017-06-01

    In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. This discrepancy has led to an investigation of opacities through laboratory experiments and improved opacity models for many of the larger contributors to the sun’s opacity, including iron and oxygen. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al, 2015]. Although these results are still controversial, repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for C, O and Fe to address the solar abundance issue [Colgan, 2013]. Armstrong et al [2014] have also implemented changes in the ATOMIC code for low-Z elements. However, no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions.This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, grant No. DE-NA0001840, and the NLUF Program, grant No. DE-NA0000850, and through LLE, University of Rochester by the NNSA/OICF under Agreement No. DE-FC52-08NA28302.

  9. Effect of q-nonextensive parameter and saturation time on electron density steepening in electron-positron-ion plasmas

    Science.gov (United States)

    Hashemzadeh, M.

    2015-11-01

    The effect of q-nonextensive parameter and saturation time on the electron density steepening in electron-positron-ion plasmas is studied by particle in cell method. Phase space diagrams show that the size of the holes, and consequently, the number of trapped particles strongly depends on the q-parameter and saturation time. Furthermore, the mechanism of the instability and exchange of energy between electron-positron and electric field is explained by the profiles of the energy density. Moreover, it is found that the q-parameter, saturation time, and electron and positron velocities affect the nonlinear evolution of the electron density which leads to the steepening of its structure. The q-nonextensive parameter or degree of nonextensivity is the relation between temperature gradient and potential energy of the system. Therefore, the deviation of q-parameter from unity indicates the degree of inhomogeneity of temperature or deviation from equilibrium. Finally, using the kinetic theory, a generalized q-dispersion relation is presented for electron-positron-ion plasma systems. It is found that the simulation results in the linear regime are in good agreement with the growth rate results obtained by the kinetic theory.

  10. Scattering of diffracting beams of electron cyclotron waves by random density fluctuations in inhomogeneous plasmas

    Science.gov (United States)

    Weber, Hannes; Maj, Omar; Poli, Emanuele

    2015-03-01

    The physics and first results of the new WKBeam code for electron cyclotron beams in tokamak plasmas are presented. This code is developed on the basis of a kinetic radiative transfer model which is general enough to account for the effects of diffraction and density fluctuations on the beam. Our preliminary numerical results show a significant broadening of the power deposition profile in ITER due to scattering from random density fluctuations at the plasma edge, while such scattering effects are found to be negligible in medium-size tokamaks like ASDEX upgrade.

  11. Extension of the coherence function to quadratic models. [applied to plasma density and potential fluctuations

    Science.gov (United States)

    Kim, Y. C.; Wong, W. F.; Powers, E. J.; Roth, J. R.

    1979-01-01

    It is shown how the use of higher coherence functions can recover some of the lost coherence due to nonlinear relationship between two fluctuating quantities whose degree of mutual coherence is being measured. The relationship between the two processes is modeled with the aid of a linear term and a quadratic term. As a specific example, the relationship between plasma density and potential fluctuations in a plasma is considered. The fraction of power in the auto-power spectrum of the potential fluctuations due to a linear relationship and to a quadratic relationship between the density and potential fluctuations is estimated.

  12. Generation of neutral and high-density electron–positron pair plasmas in the laboratory

    Science.gov (United States)

    Sarri, G.; Poder, K.; Cole, J. M.; Schumaker, W.; Di Piazza, A.; Reville, B.; Dzelzainis, T.; Doria, D.; Gizzi, L. A.; Grittani, G.; Kar, S.; Keitel, C. H.; Krushelnick, K.; Kuschel, S.; Mangles, S. P. D.; Najmudin, Z.; Shukla, N.; Silva, L. O.; Symes, D.; Thomas, A. G. R.; Vargas, M.; Vieira, J.; Zepf, M.

    2015-01-01

    Electron–positron pair plasmas represent a unique state of matter, whereby there exists an intrinsic and complete symmetry between negatively charged (matter) and positively charged (antimatter) particles. These plasmas play a fundamental role in the dynamics of ultra-massive astrophysical objects and are believed to be associated with the emission of ultra-bright gamma-ray bursts. Despite extensive theoretical modelling, our knowledge of this state of matter is still speculative, owing to the extreme difficulty in recreating neutral matter–antimatter plasmas in the laboratory. Here we show that, by using a compact laser-driven setup, ion-free electron–positron plasmas with unique characteristics can be produced. Their charge neutrality (same amount of matter and antimatter), high-density and small divergence finally open up the possibility of studying electron–positron plasmas in controlled laboratory experiments. PMID:25903920

  13. The rapid nitriding of Al alloys with the controlling of plasma power density and pretreatments

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Jun; Moon, Kyoung Il [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Lee, Jae Seung; Choi, Yoon [A-Tech System, Seoul (Korea, Republic of)

    2010-05-15

    The properties of AlN make this material very attractive for optical, electronic, and tribological application. Also, if the AlN could be formed on the Al surface to enhance its surface properties, Al could be applied for the lightening of machine parts. However, a dense oxide film exists on the surface of Al, which prevents the formation of the Al nitride even during plasma nitriding and plasma coating process. In this study, plasma nitriding has been tried to form an AlN layer on Al after the surface activation processes. During the plasma nitriding, the density of the nitrogen ions was amplified by means of controlling the power of the Al substrates. The film thickness, microstructural features and the mechanical properties such as hardness and wear properties of the AlN layer were examined as a function of the process parameters of pretreatment and plasma nitriding

  14. Density bump formation in a collisionless electrostatic shock wave in a laser-ablated plasma

    CERN Document Server

    Garasev, M A; Kocharovsky, V V; Malkov, Yu A; Murzanev, A A; Nechaev, A A; Stepanov, A N

    2016-01-01

    The emergence of a density bump at the front of a collisionless electrostatic shock wave have been observed experimentally during the ablation of an aluminium foil by a femtosecond laser pulse. We have performed numerical simulations of the dynamics of this phenomena developing alongside the generation of a package of ion-acoustic waves, exposed to a continual flow of energetic electrons, in a collisionless plasma. We present the physical interpretation of the observed effects and show that the bump consists of transit particles, namely, the accelerated ions from the dense plasma layer, and the ions from the diluted background plasma, formed by a nanosecond laser prepulse during the ablation.

  15. Electronically swept millimeter-wave interferometer for spatially resolved measurement of plasma electron density.

    Science.gov (United States)

    Howard, John; Oliver, David

    2006-12-01

    We report the development and initial implementation of what we believe to be a new rapid- spatial-scan millimeter-wave interferometer for plasma density measurements. The fast scan is effected by electronic frequency sweeping of a wideband (180-280 GHz) backward-wave oscillator whose output is focused onto a fixed blazed diffraction grating. The system, which augments the rotating-grating scanned multiview H-1 heliac interferometer, can sweep the plasma cross section in a period of less than 1 ms with a beam diameter in the plasma of 20 mm and phase noise of the order of 0.01 rad.

  16. Generation of a neutral, high-density electron-positron plasma in the laboratory

    CERN Document Server

    Sarri, G; Cole, J; Schumaker, W; Di Piazza, A; Reville, B; Doria, D; Dromey, B; Gizzi, L; Green, A; Grittani, G; Kar, S; Keitel, C H; Krushelnick, K; Kushel, S; Mangles, S; Najmudin, Z; Thomas, A G R; Vargas, M; Zepf, M

    2013-01-01

    We report on the laser-driven generation of purely neutral, relativistic electron-positron pair plasmas. The overall charge neutrality, high average Lorentz factor ($\\gamma_{e/p} \\approx 15$), small divergence ($\\theta_{e/p} \\approx 10 - 20$ mrad), and high density ($n_{e/p}\\simeq 10^{15}$cm$^{-3}$) of these plasmas open the pathway for the experimental study of the dynamics of this exotic state of matter, in regimes that are of relevance to electron-positron astrophysical plasmas.

  17. Spectral evolution of soft x-ray emission from optically thin, high electron temperature platinum plasmas

    Directory of Open Access Journals (Sweden)

    Hiroyuki Hara

    2017-08-01

    Full Text Available The soft x-ray spectra of heavy element plasmas are frequently dominated by unresolved transition array (UTA emission. We describe the spectral evolution of an intense UTA under optically thin conditions in platinum plasmas. The UTA was observed to have a peak wavelength around 4.6 nm at line-of-sight averaged electron temperatures less than 1.4 keV at electron densities of (2.5–7.5 × 1013 cm−3. The UTA spectral structure was due to emission from 4d–4f transitions in highly charged ions with average charge states of q = 20–40. A numerical simulation successfully reproduced the observed spectral behavior.

  18. Spectral evolution of soft x-ray emission from optically thin, high electron temperature platinum plasmas

    Science.gov (United States)

    Hara, Hiroyuki; Ohashi, Hayato; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Sasaki, Akira; Suzuki, Chihiro; Tamura, Naoki; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Higashiguchi, Takeshi; LHD Experiment Group

    2017-08-01

    The soft x-ray spectra of heavy element plasmas are frequently dominated by unresolved transition array (UTA) emission. We describe the spectral evolution of an intense UTA under optically thin conditions in platinum plasmas. The UTA was observed to have a peak wavelength around 4.6 nm at line-of-sight averaged electron temperatures less than 1.4 keV at electron densities of (2.5-7.5) × 1013 cm-3. The UTA spectral structure was due to emission from 4d-4f transitions in highly charged ions with average charge states of q = 20-40. A numerical simulation successfully reproduced the observed spectral behavior.

  19. The Construction of Plasma Density Feedback Control System on J-TEXT Tokamak

    Science.gov (United States)

    Ke, Xin; Chen, Zhipeng; Ba, Weigang; Shu, Shuangbao; Gao, Li; Zhang, Ming; Zhuang, Ge

    2016-02-01

    The plasma density feedback control system (PDFCS) has been established on the Joint Texas Experimental Tokamak (J-TEXT) for meeting the need for an accurate plasma density in physical experiments. It consists of a density measurement subsystem, a feedback control subsystem and a gas puffing subsystem. According to the characteristic of the gas puffing system, a voltage amplitude control mode has been applied in the feedback control strategy, which is accomplished by the proportion, integral and differential (PID) controller. In this system, the quantity calibration of gas injection, adjusted responding to the change of the density signal, has been carried out. Some experimental results are shown and discussed. supported by the National Magnetic Confinement Fusion Science Program (Nos. 2014GB103001 and 2013GB106001) and National Natural Science Foundation of China (Nos. 11305070 and 11105028)

  20. Investigations on the time evolution of the plasma density in argon electron-beam plasma at intermediate pressure

    Science.gov (United States)

    Xiaoyan, BAI; Chen, CHEN; Hong, LI; Wandong, LIU

    2017-03-01

    The time evolution of the argon electron-beam plasma at intermediate pressure and low electron beam intensity was presented. By applying the amplitude modulation with the frequency of 20 Hz on the stable beam current, the plasma evolution was studied. A Faraday cup was used for the measurement of the electron beam current and a single electrostatic probe was used for the measurement of the ion current. Experimental results indicated that the ion current was in phase with the electron beam current in the pressure range from 200 Pa to 3000 Pa and in the beam current range lower than 20 mA, the residual density increased approximately linearly with the maximum density in the log-log plot and the fitting coefficient was irrelative to the pressure. And then three kinds of kinetic models were developed and the simulated results given by the kinetic model, without the consideration of the excited atoms, mostly approached to the experimental results. This indicated that the effect of the excited atoms on the plasma density can be ignored at intermediate pressure and low electron beam current intensity, which can greatly simplify the kinetic model. In the end, the decrease of the plasma density when the beam current was suddenly off was studied based on the simplified model and it was found that the decease characteristic at intermediate pressure was approximate to the one at high pressure at low electron beam intensity, which was in good accordance with the experimental results. Supported by National Natural Science Foundations of China (No. 11375187) and the Foundation of State key Laboratory of China (No. SKLIPR1510).

  1. NO density and gas temperature measurements in atmospheric pressure nanosecond repetitively pulsed (NRP) discharges by Mid-IR QCLAS

    Science.gov (United States)

    Simeni Simeni, Marien; Stancu, Gabi-Daniel; Laux, Christophe

    2014-10-01

    Nitric oxide is a key species for many processes: in combustion, in human skin physiology... Recently, NO-ground state absolute density measurements produced by atmospheric pressure NRP discharges were carried out in air as a function of the discharge parameters, using Quantum Cascade Laser Absorption Spectroscopy. These measurements were space averaged and performed in the post-discharge region in a large gas volume. Here we present radial profiles of NO density and temperature measured directly in the discharge for different configurations. Small plasma volume and species densities, high temperature and EM noise environment make the absorption diagnostic challenging. For this purpose the QCLAS sensitivity was improved using a two-detector system. We conducted lateral absorbance measurements with a spatial resolution of 300 μm for two absorption features at 1900.076 and 1900.517 cm-1. The radial temperature and NO density distributions were obtained from the Abel inverted lateral measurements. Time averaged NO densities of about 1.E16 cm-3 and gas temperature of about 1000K were obtained in the center of the discharge. PLASMAFLAME Project (Grant No ANR-11-BS09-0025).

  2. Beam Matching to a Plasma Wake Field Accelerator Using a Ramped Density Profile at the Plasma Boundary

    CERN Document Server

    Marsh, Kenneth; Clayton, Chris; Decker, Franz Josef; Deng, Suzhi; Hogan, Mark; Huang Cheng Kun; Iverson, Richard; Johnson, Devon K; Joshi, Chandrashekhar; Katsouleas, Thomas C; Krejcik, Patrick; Lu, Wei; Mori, Warren; Muggli, Patric; Oz, Erdem; Siemann, Robert; Walz, Dieter; Zhou, Miaomiao

    2005-01-01

    An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense regime, the drive beam creates an ion channel which acts on the beam as a strong thick focusing lens. The ion channel causes the beam to undergo multiple betatron oscillations along the length of the plasma. There are several advantages if the beam size can be matched to a constant radius. First, simulations have shown that instabilities such as hosing are reduced when the beam is matched. Second, synchrotron radiation losses are minimized when the beam is matched. Third, an initially matched beam will propagate with no significant change in beam size in spite of large energy loss or gain. Coupling to the plasma with a matched radius can be difficult in some cases. This paper shows how an appropriate density ramp at the plasma entrance can be useful for achieving a matched beam. Additionally, the density ramp is helpful in bringing a misaligned trailing beam onto the drive beam axis. A plas...

  3. Broadening of the Spectral Atomic Lines Analysis in High Density Argon Corona Plasma by Using Voigt Profile

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.; Atrazhev, V. M.

    2015-06-01

    Studies of spectrum emission from high density argon plasma corona has been done. The analysis of the boardening of spectral atomic lines of Ar-I profile has been curried out by using an empirical approximation based on a Voigt profile. Full-width at half-maximum (FWHM) of the spectral-lines of 763.5 nm has been determined from atmospheric pressure until liquid state. The study liquid argon was curried out in a variation of temperature from K to 151.2 K and hydrostatics pressure from 2.1 MPa to 6.4 MPa. These pressure gives the densities N∞ (i.e. density very far from ionization zone) a variation from 1.08 1022 to 2.11 1022 cm-3. FWHM of Voigt approximation (Wv) of the line 763,5 nm of 'Ar I for: the emission lamp very low pressure (Wv = 0,160 nm) and our corona discharge at a pressure of MPa (Wv = 0,67 nm) and at a pressure of 9,5 MPa (Wv = 1,16 nm). In gas, corona plasma has been generated from 0.1 MPa to 9.5 MPa. We found that the broadening spectral line increase by increasing densities both for. the spectral-lines of 763.5 nm and 696.5 nm. We concluded that broadening of spectrum cause of Van der Waals force.

  4. Active measurements of the thermal electron density and temperature from the Mercury Magnetospheric Orbiter of the BepiColombo mission

    Science.gov (United States)

    Trotignon, J. G.; Beghin, C.; Matsumoto, H.; Kojima, H.; Hashimoto, K.; Blomberg, L.; Lebreton, J. P.; Masson, A.; Hamelin, M.; Pottelette, R.

    The thermal component of the Mercury's electron population remains to be investigated. It is one of the scientific objectives of the Plasma Wave Investigation, PWI, consortium to determine its influence on the formation and dynamics of the planetary magnetosphere as a function of the solar activity. The Active Measurement of Mercury's Plasma, AM2P, experiment has therefore been proposed as part of the PWI to measure the density and temperature of the thermal electron population all along the Mercury Magnetospheric Orbiter of the BepiColombo mission. These two aeronomical parameters shall be deduced from the measurements of the self- and mutual-impedances of the MEFISTO (Mercury Electric Field In Situ TOol) double-sphere antenna in a frequency range comprising the expected plasma frequency. The purpose of the current presentation is: 1) to set the AM2P scientific objectives, 2) to give the principle of measurements, 3) to describe the electronics device, and 4) to show the ability of the AM2P to make reliable and accurate measurements of the thermal plasma density and temperature in the Hermean magnetosphere, as well as in the solar wind at 0.31-0.47 AU from the Sun. The latter point has been established from analytical and numerical simulations.

  5. Chirp mitigation of plasma-accelerated beams using a modulated plasma density

    CERN Document Server

    Brinkmann, R; Dornmair, I; Assmann, R; Behrens, C; Floettmann, K; Grebenyuk, J; Gross, M; Jalas, S; Kirchen, M; Mehrling, T; de la Ossa, A Martinez; Osterhoff, J; Schmidt, B; Wacker, V; Maier, A R

    2016-01-01

    Plasma-based accelerators offer the possibility to drive future compact light sources and high-energy physics applications. Achieving good beam quality, especially a small beam energy spread, is still one of the major challenges. For stable transport, the beam is located in the focusing region of the wakefield which covers only the slope of the accelerating field. This, however, imprints a longitudinal energy correlation (chirp) along the bunch. Here, we propose an alternating focusing scheme in the plasma to mitigate the development of this chirp and thus maintain a small energy spread.

  6. Experimental studies and modelling of high radiation and high density plasmas in the ASDEX upgrade tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Casali, Livia

    2015-11-24

    Fusion plasmas contain impurities, either intrinsic originating from the wall, or injected willfully with the aim of reducing power loads on machine components by converting heat flux into radiation. The understanding and the prediction of the effects of these impurities and their radiation on plasma performances is crucial in order to retain good confinement. In addition, it is important to understand the impact of pellet injection on plasma performance since this technique allows higher core densities which are required to maximise the fusion power. This thesis contributes to these efforts through both experimental investigations and modelling. Experiments were conducted at ASDEX Upgrade which has a full-W wall. Impurity seeding was applied to H-modes by injecting nitrogen and also medium-Z impurities such as Kr and Ar to assess the impact of both edge and central radiation on confinement. A database of about 25 discharges has been collected and analysed. A wide range of plasma parameters was achieved up to ITER relevant values such as high Greenwald and high radiation fractions. Transport analyses taking into account the radiation distribution reveal that edge localised radiation losses do not significantly impact confinement as long as the H-mode pedestal is sustained. N seeding induces higher pedestal pressure which is propagated to the core via profile stiffness. Central radiation must be limited and controlled to avoid confinement degradation. This requires reliable control of the impurity concentration but also possibilities to act on the ELM frequency which must be kept high enough to avoid an irreversible impurity accumulation in the centre and the consequent radiation collapse. The key role of the f{sub ELM} is confirmed also by the analysis of N+He discharges. Non-coronal effects affect the radiation of low-Z impurities at the plasma edge. Due to the radial transport, the steep temperature gradients and the ELM flush out, a local equilibrium cannot be

  7. Experimental studies and modelling of high radiation and high density plasmas in the ASDEX upgrade tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Casali, Livia

    2015-11-24

    Fusion plasmas contain impurities, either intrinsic originating from the wall, or injected willfully with the aim of reducing power loads on machine components by converting heat flux into radiation. The understanding and the prediction of the effects of these impurities and their radiation on plasma performances is crucial in order to retain good confinement. In addition, it is important to understand the impact of pellet injection on plasma performance since this technique allows higher core densities which are required to maximise the fusion power. This thesis contributes to these efforts through both experimental investigations and modelling. Experiments were conducted at ASDEX Upgrade which has a full-W wall. Impurity seeding was applied to H-modes by injecting nitrogen and also medium-Z impurities such as Kr and Ar to assess the impact of both edge and central radiation on confinement. A database of about 25 discharges has been collected and analysed. A wide range of plasma parameters was achieved up to ITER relevant values such as high Greenwald and high radiation fractions. Transport analyses taking into account the radiation distribution reveal that edge localised radiation losses do not significantly impact confinement as long as the H-mode pedestal is sustained. N seeding induces higher pedestal pressure which is propagated to the core via profile stiffness. Central radiation must be limited and controlled to avoid confinement degradation. This requires reliable control of the impurity concentration but also possibilities to act on the ELM frequency which must be kept high enough to avoid an irreversible impurity accumulation in the centre and the consequent radiation collapse. The key role of the f{sub ELM} is confirmed also by the analysis of N+He discharges. Non-coronal effects affect the radiation of low-Z impurities at the plasma edge. Due to the radial transport, the steep temperature gradients and the ELM flush out, a local equilibrium cannot be

  8. Effect of dust charge variation on dust—acoustic solitary waves in a magnetized two—ion—temperature dusty plasma

    Institute of Scientific and Technical Information of China (English)

    XueJu-Kui; LangHe

    2003-01-01

    The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may exite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).

  9. Effect of dust charge variation on dust-acoustic solitary waves in a magnetized two-ion-temperature dusty plasma

    Institute of Scientific and Technical Information of China (English)

    薛具奎; 郎和

    2003-01-01

    The effect of dust charge variation on the dust-acoustic solitary structures is investigated in a warm magnetized two-ion-temperature dusty plasma consisting of a negatively and variably charged extremely massive dust fluid and ions of two different temperatures. It is shown that the dust charge variation as well as the presence of a second component of ions would modify the properties of the dust-acoustic solitary structures and may excite both dust-acoustic solitary holes (soliton waves with a density dip) and positive solitons (soliton waves with a density hump).

  10. Ultrafine grained high density manganese zinc ferrite produced using polyol process assisted by Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Gaudisson, T.; Beji, Z.; Herbst, F.; Nowak, S. [ITODYS, Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75205 Paris (France); Ammar, S., E-mail: ammarmer@univ-paris-diderot.fr [ITODYS, Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, 75205 Paris (France); Valenzuela, R. [D2MC, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, 04510 Ciudad de Mexico (Mexico)

    2015-08-01

    We report the synthesis of Mn–Zn ferrite (MZFO) nanoparticles (NPs) by the polyol process and their consolidation by Spark Plasma Sintering (SPS) technique at relatively low temperature and short time, namely 500 °C for 10 min. NPs were obtained as perfectly epitaxied aggregated nanoclusters forming a kind of spherical pseudo-single-crystals of about 40 nm in size. The results on NPs consolidation by SPS underlined the importance of this clustering on the grain growth mechanism. Grain growth proceeds by coalescing nanocrystalline aggregates into single grain of almost the same average size, thus leading to a high density ceramic. Due to magnetic exchange interactions between grains, the produced ceramic does not exhibit thermal relaxation whereas their precursor polyol-made NPs are superparamagnetic. - Highlights: • Textured Mn–Zn ferrite nano-aggregates were produced in polyol. • Dense ceramic was obtained by SPS starting from these particles at 500 °C for 10 min. • The grain growth was driven by coalescence leading to nanometer-sized grains. • The 300 K-magnetic properties of the ceramic are typical of a soft magnet. • Its magnetization is very close to that of bulk despite its ultrafine grain size.

  11. Particle Densities of the Atmospheric-Pressure Argon Plasmas Generated by the Pulsed Dielectric Barrier Discharges

    Science.gov (United States)

    Pan, Jie; Li, Li; Wang, Yunuan; Xiu, Xianwu; Wang, Chao; Song, Yuzhi

    2016-11-01

    Atmospheric-pressure argon plasmas have received increasing attention due to their high potential in many industrial and biomedical applications. In this paper, a 1-D fluid model is used for studying the particle density characteristics of the argon plasmas generated by the pulsed dielectric barrier discharges. The temporal evolutions of the axial particle density distributions are illustrated, and the influences of changing the main discharge conditions on the averaged particle densities are researched by independently varying the various discharge conditions. The calculation results show that the electron density and the ion density reach two peaks near the momentary cathodes during the rising and the falling edges of the pulsed voltage. Compared with the charged particle densities, the densities of the resonance state atom Arr and the metastable state atom Arm have more uniform axial distributions, reach higher maximums and decay more slowly. During the platform of the pulsed voltage and the time interval between the pulses, the densities of the excited state atom Ar* are far lower than those of the Arr or the Arm. The averaged particle densities of the different considered particles increase with the increases of the amplitude and the frequency of the pulsed voltage. Narrowing the discharge gap and increasing the relative dielectric constant of the dielectric also contribute to the increase of the averaged particle densities. The effects of reducing the discharge gap distance on the neutral particle densities are more significant than the influences on the charged particle densities. supported by Natural Science Foundation of Shandong Province, China (No. ZR2015AQ008), and Project of Shandong Province Higher Educational Science and Technology Program of China (No. J15LJ04)

  12. Effects of the fluorine plasma treatment on low-density drain AlGaN/GaN HEMT

    Science.gov (United States)

    Chong, Wang; Xiaoxiao, Wei; Yunlong, He; Xuefeng, Zheng; Xiaohua, Ma; Jincheng, Zhang; Yue, Hao

    2016-06-01

    Low-density drain high-electron mobility transistors (LDD-HEMTs) with different F- plasma treatment were investigated by simulations and experiments. The LDD region was performed by introducing negatively charged fluorine ions, which modified the surface field distribution on the drain side of the HEMT, and the enhancement of breakdown voltage were achieved. With the increased fluorine plasma treatment power and LDD region length, the breakdown voltage can be maximumly improved by 70%, and no severe reductions on output current and transconductance were observed. To confirm the temperature stability of the devices, annealing experiments were carried out at 400 °C for 2 min in ambient N2. Moreover, the gate leakage current and breakdown voltage before and after annealing were compared and analyzed, respectively. Project supported by the National Natural Science Foundation of China (Nos. 61334002, 61106106, 61474091) and the Fundamental Research Funds for the Central Universities (Nos. K5051325004, K5051325002).

  13. Effect of plasma torus density variations on the morphology and brightness of the Io footprint

    Science.gov (United States)

    Payan, A. P.; Rajendar, A.; Paty, C. S.; Crary, F.

    2014-05-01

    We develop a 2-D-layered model of the Io plasma torus to study the apparent "shutoff" of the Io footprint in 2007, when it disappeared beneath a region of diffuse emissions, roughly coincident with a massive eruption of Tvashtar Paterae. First, we investigate the effects of Io's location in the plasma torus and validate our model results against Hubble UV observations of the Io footprint. We are able to qualitatively reproduce variations in the morphology of the footprint due to Io's changing latitudinal location with respect to the center of the plasma torus, capturing the bright leading spot and the dimmer tail. Then, we consider the effects of an increase in the local plasma density on the brightness and morphology of the Io footprint. Our results show a correlation between a local density increase in the plasma torus and the dimming of the Io footprint as observed in 2007. In particular, we find that a local density enhancement at Io of fivefold compared to the nominal value is sufficient to produce the observed shutoff of the footprint.

  14. Simulation of cold atmospheric plasma component composition and particle densities in air

    Science.gov (United States)

    Kirsanov, Gennady; Chirtsov, Alexander; Kudryavtsev, Anatoliy

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was divided into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

  15. Ionized sputter deposition using an extremely high plasma density pulsed magnetron discharge

    Energy Technology Data Exchange (ETDEWEB)

    Macak, Karol [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Kouznetsov, Vladimir [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Schneider, Jochen [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Helmersson, Ulf [Department of Physics, Linkoeping University, SE-581 83 Linkoeping, (Sweden); Petrov, Ivan [Materials Science Department and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

    2000-07-01

    Time resolved plasma probe measurements of a novel high power density pulsed plasma discharge are presented. Extreme peak power densities in the pulse (on the order of several kW cm{sup -2}) result in a very dense plasma with substrate ionic flux densities of up to 1 A cm{sup -2} at source-to-substrate distances of several cm and at a pressure of 0.13 Pa (1 mTorr). The pulse duration was {approx}100 {mu}s with a pulse repetition frequency of 50 Hz. The plasma consists of metallic and inert gas ions, as determined from time resolved Langmuir probe measurements and in situ optical emission spectroscopy data. It was found that the plasma composition at the beginning of the pulse was dominated by Ar ions. As time elapsed metal ions were detected and finally dominated the ion composition. The effect of the process parameters on the temporal development of the ionic fluxes is discussed. The ionized portion of the sputtered metal flux was found to have an average velocity of 2500 m s{sup -1} at 6 cm distance from the source, which conforms to the collisional cascade sputtering theory. The degree of ionization of the sputtered metal flux at a pressure of 0.13 Pa was found to be 40%{+-}20% by comparing the total flux of deposited atoms with the charge measured for the metal ions in the pulse. (c) 2000 American Vacuum Society.

  16. Fundamental Study of Interactions Between Pulsed High-Density Plasmas and Materials for Space Propulsion

    Science.gov (United States)

    2016-05-23

    thermal shock and allows for optical plasma diagnostics. The new capillary uses a flash lamp approach for triggering to eliminate the need for a...add silicon oxide to alumina processing to form relatively low- melting aluminosilicate phases to enhance densification/ sintering at temperatures well...pressure on the microstructure of spark plasma sintered silicon carbide,” Journal of Chemical Processing Research 16, 303 (2007). 5. O. Sharia

  17. JT-60U Thomson scattering system with multiple ruby laser and high spatial resolution for high electron temperature plasma measurement

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Hidetoshi; Naito, Osamu; Yamashita, Osamu; Kitamura, Shigeru; Hatae, Takaki; Nagashima, Akira [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1996-11-01

    This article describes the design and operation of a 60 spatial channel Thomson scattering system as of 1996 with multiple ruby lasers to measure the electron temperature T{sub e} and density n{sub e} profiles of the JT-60U plasmas. The wide spectral range (403-683 nm) of the spectrometer and newly developed two-dimensional detector (high repetition photodiode array) has enabled this system to measure the high electron temperature plasma (5 keV or more) formed at the plasma core during negative magnetic shear discharge with high precision and reliability. The high spatial resolution (8 mm) have provided the precise measurement of steep electron temperature and density gradients formed at the plasma edge and in the scrape-off layer during H-mode discharge. The multilaser operation with the minimum time interval of 2 ms has provided an essential tool for the transient phenomenon measurement like the formation process of edge transport barrier during L- to H-mode transition and internal transport barrier during discharge with negative magnetic shear, the relaxation process of pellet injected plasma and so on. Measurement examples of recent JT-60U T{sub e} and n{sub e} profiles are also presented. (author)

  18. Investigation of the 2p_{32}-3d_{52} line emission of Au;{53+}-Au;{69+} for diagnosing high energy density plasmas.

    Science.gov (United States)

    Brown, G V; Hansen, S B; Träbert, E; Beiersdorfer, P; Widmann, K; Chen, H; Chung, H K; Clementson, J H T; Gu, M F; Thorn, D B

    2008-06-01

    Measurements of the L -shell emission of highly charged gold ions were made under controlled laboratory conditions using the SuperEBIT electron beam ion trap, allowing detailed spectral observations of lines from Fe-like Au53+ through Ne-like Au69+ . Using atomic data from the Flexible Atomic Code, we have identified strong 3d_{52}-->2p_{32} emission features that can be used to diagnose the charge state distribution in high energy density plasmas, such as those found in the laser entrance hole of hot hohlraum radiation sources. We provide collisional-radiative calculations of the average ion charge Z as a function of temperature and density, which can be used to relate charge state distributions inferred from 3d_{52}-->2p_{32} emission features to plasma conditions, and investigate the effects of plasma density on calculated L -shell Au emission spectra.

  19. On the diurnal variability in F2-region plasma density above the EISCAT Svalbard radar

    Directory of Open Access Journals (Sweden)

    J. Moen

    2008-08-01

    Full Text Available Two long runs of EISCAT Svalbard Radar (ESR, in February 2001 and October 2002, have been analysed with respect to variability in the F2 region peak density and altitude. The diurnal variation in the F2 peak density exhibits one maximum around 12:00 MLT and another around 23:00 MLT, consistent with solar wind controlled transport of EUV ionized plasma across the polar cap from day to night. High density plasma patch material is drawn in through the cusp inflow region independent of IMF BY. There is no apparent IMF BY asymmetry on the intake of high density plasma, but the trajectory of its motion is strongly BY dependent. Comparison with the international reference ionosphere model (IRI2001 clearly demonstrates that the model does not take account of the cross-polar transport of F2-region plasma, and hence has limited applicability in polar cap regions.

  20. Preferential association of apolipoprotein E Leiden with very low density lipoproteins of human plasma

    NARCIS (Netherlands)

    Fazio, S.; Horie, Y.; Weisgraber, K.H.; Havekes, L.M.; Rall Jr., S.C.

    1993-01-01

    Apolipoprotein (apo) E Leiden is a rare variant of human apoE characterized by defective receptor binding and associated with dominant transmission of type III hyperlipoproteinemia. In heterozygotes, apoE Leiden is present in higher concentrations in both total plasma and very low density