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Sample records for edge density profiles

  1. Measurements of edge density profile modifications during IBW on TFTR

    International Nuclear Information System (INIS)

    Hanson, G.R.; Bush, C.E.; Wilgen, J.B.

    1997-01-01

    Ion Bernstein wave (IBW) antennas are known to have substantial localized effects on the plasma edge. To allow better understanding and measurement of these effects, the TFTR edge reflectometer has been relocated to the new IBW antenna. This move was facilitated by the incorporation of a diagnostic access tube in the IBW antenna identical to the original diagnostic tube in the fast-wave (FW) antenna. This allowed the reflectometer launcher to simply be moved from the old FW antenna to the new IBW antenna. Only a moderate extension of the waveguide transmission line was required to reconnect the reflectometer to the launcher in its new location. Edge density profile modification during IBW experiments has been observed. Results from IBW experiments will be presented and contrasted to the edge density modifications previously observed during FW heating experiments

  2. Edge density profiles in high-performance JET plasmas

    International Nuclear Information System (INIS)

    Summers, D.D.R.; Viaccoz, B.; Vince, J.

    1997-01-01

    Detailed electron density profiles of the scrape-off layer in high-performance JET plasmas (plasma current, I p nbi ∝17 MW) have been measured by means of a lithium beam diagnostic system featuring high spatial resolution [Kadota (1978)[. Measurements were taken over a period of several seconds, allowing examination of the evolution of the edge profile at a location upstream from the divertor target. The data clearly show the effects of the H-mode transition - an increase in density near the plasma separatrix and a reduction in density scrape-off length. The profiles obtained under various plasma conditions are compared firstly with data from other diagnostics, located elsewhere in the vessel, and also with the predictions of an 'onion-skin' model (DIVIMP), which used, as initial parameters, data from an array of probes located in the divertor target. (orig.)

  3. Inter-ELM evolution of the edge current density profile on the ASDEX Upgrade tokamak

    International Nuclear Information System (INIS)

    Dunne, Michael G.

    2014-01-01

    The sudden decrease of plasma stored energy and subsequent power deposition on the first wall of a tokamak device due to edge localised modes (ELMs) is potentially detrimental to the success of a future fusion reactor. Understanding and control of ELMs is critical for the longevity of these devices and also to maximise their performance. The commonly accepted picture of ELMs posits a critical pressure gradient and current density in the plasma edge, above which coupled magnetohydrodynamic (MHD) peeling-ballooning modes are driven unstable. Much analysis has been presented in recent years on the spatial and temporal evolution of the edge pressure gradient. However, the edge current density has typically been overlooked due to the difficulties in measuring this quantity. In this thesis, a novel method of current density recovery is presented, using the equilibrium solver CLISTE to reconstruct a high resolution equilibrium utilising both external magnetic and internal edge kinetic data measured on the ASDEX Upgrade (AUG) tokamak. The evolution of the edge current density relative to an ELM crash is presented, showing that a resistive delay in the buildup of the current density is unlikely. An uncertainty analysis shows that the edge current density can be determined with an accuracy consistent with that of the kinetic data used. A comparison with neoclassical theory demonstrates excellent agreement between the current density determined by CLISTE and the calculated profiles. Three ELM mitigation regimes are investigated: Type-II ELMs, ELMs suppressed by external magnetic perturbations (MPs), and Nitrogen seeded ELMs. In the first two cases, the current density is found to decrease as mitigation onsets, indicating a more ballooning-like plasma behaviour. In the latter case, the flux surface averaged current density can decrease while the local current density increases, thus providing a mechanism to suppress both the peeling and ballooning modes.

  4. Inter-ELM evolution of the edge current density profile on the ASDEX Upgrade tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Dunne, Michael G.

    2014-02-15

    The sudden decrease of plasma stored energy and subsequent power deposition on the first wall of a tokamak device due to edge localised modes (ELMs) is potentially detrimental to the success of a future fusion reactor. Understanding and control of ELMs is critical for the longevity of these devices and also to maximise their performance. The commonly accepted picture of ELMs posits a critical pressure gradient and current density in the plasma edge, above which coupled magnetohydrodynamic (MHD) peeling-ballooning modes are driven unstable. Much analysis has been presented in recent years on the spatial and temporal evolution of the edge pressure gradient. However, the edge current density has typically been overlooked due to the difficulties in measuring this quantity. In this thesis, a novel method of current density recovery is presented, using the equilibrium solver CLISTE to reconstruct a high resolution equilibrium utilising both external magnetic and internal edge kinetic data measured on the ASDEX Upgrade (AUG) tokamak. The evolution of the edge current density relative to an ELM crash is presented, showing that a resistive delay in the buildup of the current density is unlikely. An uncertainty analysis shows that the edge current density can be determined with an accuracy consistent with that of the kinetic data used. A comparison with neoclassical theory demonstrates excellent agreement between the current density determined by CLISTE and the calculated profiles. Three ELM mitigation regimes are investigated: Type-II ELMs, ELMs suppressed by external magnetic perturbations (MPs), and Nitrogen seeded ELMs. In the first two cases, the current density is found to decrease as mitigation onsets, indicating a more ballooning-like plasma behaviour. In the latter case, the flux surface averaged current density can decrease while the local current density increases, thus providing a mechanism to suppress both the peeling and ballooning modes.

  5. Novel analysis technique for measuring edge density fluctuation profiles with reflectometry in the Large Helical Device

    Science.gov (United States)

    Creely, A. J.; Ida, K.; Yoshinuma, M.; Tokuzawa, T.; Tsujimura, T.; Akiyama, T.; Sakamoto, R.; Emoto, M.; Tanaka, K.; Michael, C. A.

    2017-07-01

    A new method for measuring density fluctuation profiles near the edge of plasmas in the Large Helical Device (LHD) has been developed utilizing reflectometry combined with pellet-induced fast density scans. Reflectometer cutoff location was calculated by proportionally scaling the cutoff location calculated with fast far infrared laser interferometer (FIR) density profiles to match the slower time resolution results of the ray-tracing code LHD-GAUSS. Plasma velocity profile peaks generated with this reflectometer mapping were checked against velocity measurements made with charge exchange spectroscopy (CXS) and were found to agree within experimental uncertainty once diagnostic differences were accounted for. Measured density fluctuation profiles were found to peak strongly near the edge of the plasma, as is the case in most tokamaks. These measurements can be used in the future to inform inversion methods of phase contrast imaging (PCI) measurements. This result was confirmed with both a fixed frequency reflectometer and calibrated data from a multi-frequency comb reflectometer, and this method was applied successfully to a series of discharges. The full width at half maximum of the turbulence layer near the edge of the plasma was found to be only 1.5-3 cm on a series of LHD discharges, less than 5% of the normalized minor radius.

  6. Bayesian modeling of JET Li-BES for edge electron density profiles using Gaussian processes

    Science.gov (United States)

    Kwak, Sehyun; Svensson, Jakob; Brix, Mathias; Ghim, Young-Chul; JET Contributors Collaboration

    2015-11-01

    A Bayesian model for the JET lithium beam emission spectroscopy (Li-BES) system has been developed to infer edge electron density profiles. The 26 spatial channels measure emission profiles with ~15 ms temporal resolution and ~1 cm spatial resolution. The lithium I (2p-2s) line radiation in an emission spectrum is calculated using a multi-state model, which expresses collisions between the neutral lithium beam atoms and the plasma particles as a set of differential equations. The emission spectrum is described in the model including photon and electronic noise, spectral line shapes, interference filter curves, and relative calibrations. This spectral modeling gets rid of the need of separate background measurements for calculating the intensity of the line radiation. Gaussian processes are applied to model both emission spectrum and edge electron density profile, and the electron temperature to calculate all the rate coefficients is obtained from the JET high resolution Thomson scattering (HRTS) system. The posterior distributions of the edge electron density profile are explored via the numerical technique and the Markov chain Monte Carlo (MCMC) samplings. See the Appendix of F. Romanelli et al., Proceedings of the 25th IAEA Fusion Energy Conference 2014, Saint Petersburg, Russia.

  7. Edge density profile measurements by X-mode reflectometry on Tore Supra

    International Nuclear Information System (INIS)

    Clairet, F.; Bottereau, C.; Chareau, J.M.; Paume, M.; Sabot, R.

    2000-10-01

    A broadband reflectometer operating in the frequency range 50-75 GHz has been developed on Tore Supra to measure electron density profiles at the edge. The system uses extraordinary mode polarization and performs routine measurements in 20 μs with a heterodyne detection to ensure a high dynamic range sensitivity. It allows separate phase and amplitude information of the signal. The density profiles are fully automatically calculated from the raw phase. The initialization is done with an automatic detection of the first cut-off from the amplitude of the reflected signal with accuracy up to ±0.5 cm. The profiles are now part of the public database of Tore Supra (TS) and can provide details of density structures better than the centimeter range. High reliability of the measurements for various plasma conditions make this diagnostic an ideal tool to study specific edge plasma physics with given examples on detached plasma behaviour and RF antenna-plasma coupling processes. It also is shown how the presence of suprathermal electrons may perturb the measurements. (authors)

  8. X mode reflectometry for edge density profile measurements on Tore Supra

    International Nuclear Information System (INIS)

    Clairet, F.; Bottereau, C.; Chareau, J.M.; Paume, M.; Sabot, R.

    1999-01-01

    X mode heterodyne reflectometry associated with fast sweep capabilities demonstrates very precise measurement on Tore Supra and a high sensitivity (∼10 17 m -3 ) to density variations. Very good agreement with Thomson scattering measurement is observed. Fluctuations of the radial positions of the profile are no more than ± 0.5 cm. However, edge magnetic field ripple can be a concern since it is not easy to stand precisely for the wave trajectory into the plasma and for the toroidal position of the cutoff layer; nevertheless if the error can be estimated to be less than than 3 cm in the position of the whole profile, addition work is needed combining 3-D ray tracing and different antenna systems. Additional LH heating generates an ECE noise in the same frequency range of the reflectometer and is detected. This emission throughout the plasma is fortunately stopped by the upper X mode cutoff and is also reabsorbed by the electron cyclotron resonance. But at the very edge, due to a misalignment of the antenna to the plasma magnetic field and the low optical thickness of the plasma, the first cutoff frequency, i.e. the profile initialization, may be determined less precisely. (authors)

  9. Impact of Te and ne on edge current density profiles in ELM mitigated regimes on ASDEX Upgrade

    Science.gov (United States)

    Dunne, M. G.; Rathgeber, S.; Burckhart, A.; Fischer, R.; Giannone, L.; McCarthy, P. J.; Schneider, P. A.; Wolfrum, E.; the ASDEX Upgrade Team

    2015-01-01

    ELM resolved edge current density profiles are reconstructed using the CLISTE equilibrium code. As input, highly spatially and temporally resolved edge electron temperature and density profiles are used in addition to data from the extensive set of external poloidal field measurements available at ASDEX Upgrade, flux loop difference measurements, and current measurements in the scrape-off layer. Both the local and flux surface averaged current density profiles are analysed for several ELM mitigation regimes. The focus throughout is on the impact of altered temperature and density profiles on the current density. In particular, many ELM mitigation regimes rely on operation at high density. Two reference plasmas with type-I ELMs are analysed, one with a deuterium gas puff and one without, in order to provide a reference for the behaviour in type-II ELMy regimes and high density ELM mitigation with external magnetic perturbations at ASDEX Upgrade. For type-II ELMs it is found that while a similar pedestal top pressure is sustained at the higher density, the temperature gradient decreases in the pedestal. This results in lower local and flux surface averaged current densities in these phases, which reduces the drive for the peeling mode. No significant differences between the current density measured in the type-I phase and ELM mitigated phase is seen when external perturbations are applied, though the pedestal top density was increased. Finally, ELMs during the nitrogen seeded phase of a high performance discharge are analysed and compared to ELMs in the reference phase. An increased pedestal pressure gradient, which is the source of confinement improvement in impurity seeded discharges, causes a local current density increase. However, the increased Zeff in the pedestal acts to reduce the flux surface averaged current density. This dichotomy, which is not observed in other mitigation regimes, could act to stabilize both the ballooning mode and the peeling mode at the

  10. Edge electron density profiles and fluctuations measured by two-dimensional beam emission spectroscopy in the KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Y. U., E-mail: yunam@nfri.re.kr; Wi, H. M. [National Fusion Research Institute, Daejeon (Korea, Republic of); Zoletnik, S.; Lampert, M. [Wigner RCP Institute for Particle and Nuclear Physics, Budapest (Hungary); Kovácsik, Ákos [Institute of Nuclear Techniques, Budapest Technical University, Budapest (Hungary)

    2014-11-15

    Beam emission spectroscopy (BES) system in Korea Superconducting Tokamak Advanced Research (KSTAR) has recently been upgraded. The background intensity was reduced from 30% to 2% by suppressing the stray lights. This allows acquisition of the relative electron density profiles on the plasma edge without background subtraction from the beam power modulation signals. The KSTAR BES system has its spatial resolution of 1 cm, the temporal resolution of 2 MHz, and a total 32 channel (8 radial × 4 poloidal) avalanche photo diode array. Most measurements were done on the plasma edge, r/a ∼ 0.9, with 8 cm radial measurement width that covers the pedestal range. High speed density profile measurements reveal temporal behaviors of fast transient events, such as the precursors of edge localized modes and the transitions between confinement modes. Low background level also allows analysis of the edge density fluctuation patterns with reduced background fluctuations. Propagation of the density structures can be investigated by comparing the phase delays between the spatially distributed channels.

  11. Comparison of collisional radiative models for edge electron density reconstruction from Li I (2s-2p) emission profiles

    Energy Technology Data Exchange (ETDEWEB)

    Stoschus, H.; Hudson, B.; Munoz Burgos, J. M. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831-0117 (United States); Thomas, D. M. [General Atomics, San Diego, California 92186-5608 (United States); Schweinzer, J. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, 85748 Garching (Germany)

    2012-10-15

    Four collisional radiative models (CRMs) for reconstruction of the edge electron density profile from the measured Li I (2s-2p) emission profile of an accelerated lithium beam are compared using experimental data from DIII-D. It is shown for both L- and H-mode plasmas that edge density profiles reconstructed with the CRMs DDD2, ABSOLUT, [Sasaki et al. Rev. Sci. Instrum. 64, 1699 (1993)] and a new model developed at DIII-D agree in a density scan from n{sub e}{sup ped}= (2.0-6.5) Multiplication-Sign 10{sup 19} m{sup -3} within 20%, 20%, <5%, and 40%, respectively, of the pedestal density measured with Thomson scattering. Profile shape and absolute density vary in a scan of the effective ion charge Z{sub eff}= 1-6 up to a factor of two but agree with Thomson data for Z{sub eff}= 1-2 within the error bars.

  12. Effect of ion orbit loss on the structure in the H-mode tokamak edge pedestal profiles of rotation velocity, radial electric field, density, and temperature

    International Nuclear Information System (INIS)

    Stacey, Weston M.

    2013-01-01

    An investigation of the effect of ion orbit loss of thermal ions and the compensating return ion current directly on the radial ion flux flowing in the plasma, and thereby indirectly on the toroidal and poloidal rotation velocity profiles, the radial electric field, density, and temperature profiles, and the interpretation of diffusive and non-diffusive transport coefficients in the plasma edge, is described. Illustrative calculations for a high-confinement H-mode DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] plasma are presented and compared with experimental results. Taking into account, ion orbit loss of thermal ions and the compensating return ion current is found to have a significant effect on the structure of the radial profiles of these quantities in the edge plasma, indicating the necessity of taking ion orbit loss effects into account in interpreting or predicting these quantities

  13. Evolution of Edge Pedestal Profiles Between ELMs

    Science.gov (United States)

    Floyd, J. P.; Stacey, W. M.; Groebner, R. J.

    2012-10-01

    The measured edge profile evolution in DIII-D discharges is analyzed in terms of the implied thermal diffusivities, ion diffusion coefficients and pinch velocities, using the momentum-balance methodology of Ref. [1], extended to take into account ion orbit loss and X-point loss. The evolution of the density, temperature, rotation and radial electric field profiles in the edge pedestal between edge localized modes (ELMs) provides information of these diffusive and non-diffusive transport processes in the pedestal of H-mode plasmas. This methodology is incorporated in the GTEDGE code developed for DIII-D data interpretation. Using a smaller integration time for the charge exchange recombination measurements than in Ref. [1] allows a more detailed examination of the time evolution of the ion temperature and rotation profiles. 6pt [1] W.M. Stacey and R.J. Groebner, Nucl. Fusion 51, 063024 (2011).

  14. Cutting Edge Localisation in an Edge Profile Milling Head

    NARCIS (Netherlands)

    Fernandez Robles, Laura; Azzopardi, George; Alegre, Enrique; Petkov, Nicolai

    2015-01-01

    Wear evaluation of cutting tools is a key issue for prolonging their lifetime and ensuring high quality of products. In this paper, we present a method for the effective localisation of cutting edges of inserts in digital images of an edge profile milling head. We introduce a new image data set of

  15. MODEL OF THE TOKAMAK EDGE DENSITY PEDESTAL INCLUDING DIFFUSIVE NEUTRALS

    International Nuclear Information System (INIS)

    BURRELL, K.H.

    2003-01-01

    OAK-B135 Several previous analytic models of the tokamak edge density pedestal have been based on diffusive transport of plasma plus free-streaming of neutrals. This latter neutral model includes only the effect of ionization and neglects charge exchange. The present work models the edge density pedestal using diffusive transport for both the plasma and the neutrals. In contrast to the free-streaming model, a diffusion model for the neutrals includes the effect of both charge exchange and ionization and is valid when charge exchange is the dominant interaction. Surprisingly, the functional forms for the electron and neutral density profiles from the present calculation are identical to the results of the previous analytic models. There are some differences in the detailed definition of various parameters in the solution. For experimentally relevant cases where ionization and charge exchange rate are comparable, both models predict approximately the same width for the edge density pedestal

  16. The text neutral lithium beam edge density diagnostic

    International Nuclear Information System (INIS)

    Howald, A.M.; McChesney, J.M.; West, W.P.

    1994-07-01

    A fast neutral lithium beam has been installed on the TEXT tokamak for Beam Emission Spectroscopy (BES) studies of the edge plasma electron density profile. The diagnostic was recently upgraded from ten to twenty spatial channels, each of which has two detectors, one to measure lithium beam signal and one to monitor plasma background light. The spatial resolution is 6 mm, and the temporal resolution is designed to be as high as 10 ms for studies of transient events including plasma density fluctuations. Initial results are presented from the ten-channel system: Edge electron densities unfolded from the LiI(2 s 2 S - 2 p 2 P) 670.8 nm emission profile have the same general time dependence as the line-averaged density measured by microwave interferometry

  17. Measurement of neoclassically predicted edge current density at ASDEX Upgrade

    Science.gov (United States)

    Dunne, M. G.; McCarthy, P. J.; Wolfrum, E.; Fischer, R.; Giannone, L.; Burckhart, A.; the ASDEX Upgrade Team

    2012-12-01

    Experimental confirmation of neoclassically predicted edge current density in an ELMy H-mode plasma is presented. Current density analysis using the CLISTE equilibrium code is outlined and the rationale for accuracy of the reconstructions is explained. Sample profiles and time traces from analysis of data at ASDEX Upgrade are presented. A high time resolution is possible due to the use of an ELM-synchronization technique. Additionally, the flux-surface-averaged current density is calculated using a neoclassical approach. Results from these two separate methods are then compared and are found to validate the theoretical formula. Finally, several discharges are compared as part of a fuelling study, showing that the size and width of the edge current density peak at the low-field side can be explained by the electron density and temperature drives and their respective collisionality modifications.

  18. Measurement of neoclassically predicted edge current density at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Dunne, M.G.; McCarthy, P.J.; Wolfrum, E.; Fischer, R.; Giannone, L.; Burckhart, A.

    2012-01-01

    Experimental confirmation of neoclassically predicted edge current density in an ELMy H-mode plasma is presented. Current density analysis using the CLISTE equilibrium code is outlined and the rationale for accuracy of the reconstructions is explained. Sample profiles and time traces from analysis of data at ASDEX Upgrade are presented. A high time resolution is possible due to the use of an ELM-synchronization technique. Additionally, the flux-surface-averaged current density is calculated using a neoclassical approach. Results from these two separate methods are then compared and are found to validate the theoretical formula. Finally, several discharges are compared as part of a fuelling study, showing that the size and width of the edge current density peak at the low-field side can be explained by the electron density and temperature drives and their respective collisionality modifications. (paper)

  19. Edge plasma density reconstruction for fast monoenergetic lithium beam probing

    International Nuclear Information System (INIS)

    Sasaki, S.; Takamura, S.; Ueda, M.; Iguchi, H.; Fujita, J.; Kadota, K.

    1993-01-01

    Two different electron density reconstruction methods for 8-keV neutral lithium beam probing have been developed for the Compact Helical System (CHS). Density dependences on emission and ionization processes are included by using effective rate coefficients obtained from the collisional radiative model. Since the two methods differ in the way the local beam density in the plasma is determined, the methods have different applicable electron densities. The beam attenuation is calculated by iteration from the electron density profile in method I. In method II, the beam remainder at the observation point z is determined by integrating the Li I emission intensity from z toward the position of emission tail-off. At the emission tail-off, the fast lithium beam is completely attenuated. Selecting an appropriate method enables us to obtain edge electron density profile well inside the last closed flux surface for various ranges of plasma densities (10 12 --5x10 13 cm -3 ). The electron density profiles reconstructed by these two different methods are in good agreement with each other and are consistent with results from ruby laser Thomson scattering

  20. Development of edge effects around experimental ecosystem hotspots is affected by edge density and matrix type

    Science.gov (United States)

    Ecological edge effects are sensitive to landscape context. In particular, edge effects can be altered by matrix type and by the presence of other nearby edges. We experimentally altered patch configurations in an African savanna to determine how edge density and matrix type influence edge effect de...

  1. Density limit in ASDEX discharges with peaked density profiles

    International Nuclear Information System (INIS)

    Staebler, A.; Niedermeyer, H.; Loch, R.; Mertens, V.; Mueller, E.R.; Soeldner, F.X.; Wagner, F.

    1989-01-01

    Results concerning the density limit in OH and NI-heated ASDEX discharges with the usually observed broad density profiles have been reported earlier: In ohmic discharges with high q a (q-cylindrical is used throughout this paper) the Murakami parameter (n e R/B t ) is a good scaling parameter. At the high densities edge cooling is observed causing the plasma to shrink until an m=2-instability terminates the discharge. When approaching q a =2 the density limit is no longer proportional to I p ; a minimum exists in n e,max (q a ) at q a ∼2.15. With NI-heating the density limit increases less than proportional to the heating power; the behaviour during the pre-disruptive phase is rather similar to the one of OH discharges. There are specific operating regimes on ASDEX leading to discharges with strongly peaked density profiles: the improved ohmic confinement regime, counter neutral injection, and multipellet injection. These regimes are characterized by enhanced energy and particle confinement. The operational limit in density for these discharges is, therefore, of great interest having furthermore in mind that high central densities are favourable in achieving high fusion yields. In addition, further insight into the mechanisms of the density limit observed in tokamaks may be obtained by comparing plasmas with rather different density profiles at their maximum attainable densities. 7 refs., 2 figs

  2. Spectroscopic measurements of the density and electronic temperature at the plasma edge in Tore Supra

    International Nuclear Information System (INIS)

    Lediankine, A.

    1996-01-01

    The profiles of temperature and electronic density at the plasma edge are important to study the wall-plasma interaction and the radiative layers in the Tokamak plasmas. The laser ablation technique of the lithium allows to measure the profile of electronic density. To measure the profile of temperature, it has been used for the first time, the injection of a fluorine neutral atoms beam. The experiments, the results are described in this work. (N.C.)

  3. Measurement of plasma edge profile on Wendelstein 7-X

    Energy Technology Data Exchange (ETDEWEB)

    Drews, Philipp; Liang, Yunfeng; Neubauer, Olaf; Denner, Peter; Rack, Michael; Liu, Shaocheng; Wang, Nunchao; Nicolai, Dirk; Hollfeld, Klaus; Satheeswaran, Guruparan [Forschungszentrum Juelich, IEK4, Juelich (Germany); Grulke, Olaf [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Collaboration: W7-X Team

    2016-07-01

    Wendelstein 7-X (W7-X), currently under commissioning at the IPP Greifswald, will be the world's largest stellarator with modular superconducting coils, which will enable steady-state-like plasma operation of up to thirty minutes in order to explore the reactor relevance of this concept. The first operation phase of W7-X will employ a limiter configuration. It will be used primarily for setting up the diagnostics and testing the magnetic configuration. In conjunction with the multipurpose manipulator, a fast reciprocating probe is installed. The combined probe head will be used to measure the radial distribution of the magnetic field using magnetic pick-up coils; the plasma temperature and density profiles and the radial electric field using Langmuir pins; and the plasma flows using a Mach setup. As a quasi-isodynamic stellarator, it has been predicted that not only neoclassical but also turbulent transport will be comparable to or possibly even lower than that of tokamaks. Edge plasma profile measurements, especially those of the electron temperature and density, will play a key role in validating this performance in comparison to the tokamak and hence the viability of a stellarator fusion reactor. The edge plasma profile measurements using the combined probe head are presented.

  4. Fueling with edge recycling to high-density in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, A.W., E-mail: leonard@fusion.gat.com [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Elder, J.D. [University of Toronto Institute of Aerospace Studies, Toronto, Canada M3H 5T6 (Canada); Canik, J.M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Groebner, R.J.; Osborne, T.H. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)

    2013-07-15

    Pedestal fueling through edge recycling is examined with the interpretive OEDGE code for high-density discharges in DIII-D. A high current, high-density discharge is found to have a similar radial ion flux profile through the pedestal to a lower current, lower density discharge. The higher density discharge, however, has a greater density gradient indicating a pedestal particle diffusion coefficient that scales near linear with 1/I{sub p}. The time dependence of density profile is taken into account in the analysis of a discharge with low frequency ELMs. The time-dependent analysis indicates that the inferred neutral ionization source is inadequate to account for the increase in the density profile between ELMs, implying an inward density convection, or density pinch, near the top of the pedestal.

  5. Presheath profiles in simulated tokamak edge plasmas

    International Nuclear Information System (INIS)

    LaBombard, B.; Conn, R.W.; Hirooka, Y.; Lehmer, R.; Leung, W.K.; Nygren, R.E.; Ra, Y.; Tynan, G.

    1988-04-01

    The PISCES plasma surface interaction facility at UCLA generates plasmas with characteristics similar to those found in the edge plasmas of tokamaks. Steady state magnetized plasmas produced by this device are used to study plasma-wall interaction phenomena which are relevant to tokamak devices. We report here progress on some detailed investigations of the presheath region that extends from a wall surface into these /open quotes/simulated tokamak/close quotes/ edge plasma discharges along magnetic field lines

  6. Edge plasma density convection during ICRH on Tore Supra

    International Nuclear Information System (INIS)

    Becoulet, M.; Colas, L.; Gunn, J.; Ghendrih, Ph.; Becoulet, A.; Pecoul, S.; Heuraux, S.

    2001-11-01

    The 2D edge plasma density distribution around ion cyclotron resonance heating (ICRH) antennae is studied experimentally and numerically in the tokamak Tore Supra (TS). A local density decrease in front of the loaded ICRH antenna ('pump-out' effect) is demonstrated by Langmuir probe measurements in a low recycling regime. An up-down asymmetry in the heat-flux and in the antenna erosion is also observed, and is associated with poloidal variations of the local density. These density redistributions are ascribed to an ExB convection process linked with RF-sheaths. To assess this interpretation, the 2D transport code CELLS was developed for modeling the density distribution near an antenna. The code takes into account perpendicular diffusion, parallel transport and convection in RF-sheath-driven potentials given by the 3D-antenna code ICANT. The strong density differences obtained in simulations reproduce up-down asymmetries of the heat fluxes. (authors)

  7. Edge plasma density convection during ICRH on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Becoulet, M.; Colas, L.; Gunn, J.; Ghendrih, Ph.; Becoulet, A. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Pecoul, S.; Heuraux, S. [Nancy-1 Univ., 54 (France). Lab. de Physique des Milieux Ionises

    2001-11-01

    The 2D edge plasma density distribution around ion cyclotron resonance heating (ICRH) antennae is studied experimentally and numerically in the tokamak Tore Supra (TS). A local density decrease in front of the loaded ICRH antenna ('pump-out' effect) is demonstrated by Langmuir probe measurements in a low recycling regime. An up-down asymmetry in the heat-flux and in the antenna erosion is also observed, and is associated with poloidal variations of the local density. These density redistributions are ascribed to an ExB convection process linked with RF-sheaths. To assess this interpretation, the 2D transport code CELLS was developed for modeling the density distribution near an antenna. The code takes into account perpendicular diffusion, parallel transport and convection in RF-sheath-driven potentials given by the 3D-antenna code ICANT. The strong density differences obtained in simulations reproduce up-down asymmetries of the heat fluxes. (authors)

  8. Scattering of ECRF waves by edge density fluctuations and blobs

    Directory of Open Access Journals (Sweden)

    Ram Abhay K.

    2015-01-01

    Full Text Available The scattering of electron cyclotron waves by density blobs embedded in the edge region of a fusion plasma is studied using a full-wave model. The full-wave theory is a generalization of the usual approach of geometric optics ray scattering by blobs. While the latter allows for only refraction of waves, the former, more general formulation, includes refraction, reflection, and diffraction of waves. Furthermore, the geometric optics, ray tracing, model is limited to blob densities that are slightly different from the background plasma density. Observations in tokamak experiments show that the fluctuating density differs from the background plasma density by 20% or more. Thus, the geometric optics model is not a physically realistic model of scattering of electron cyclotron waves by plasma blobs. The differences between the ray tracing approach and the full-wave approach to scattering are illustrated in this paper.

  9. Structure of density fluctuations in the edge plasma of ASDEX

    Energy Technology Data Exchange (ETDEWEB)

    Rudyj, A; Carlson, A; Endler, M; Giannone, L.; Niedermeyer, H; Theimer, G [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    1990-01-01

    It is now generally believed that the anomalous particle and energy transport in tokamaks is caused by turbulent fluctuations. The physical nature of these fluctuations (mode type, the driving mechanism) have still to be identified experimentally before a self consistent transport theory can be developed. In contrast to the confinement region the plasma edge can be well diagnosed. H{sub {alpha}}-light, which is emitted at the edge, reacts to density and to some extend to temperature fluctuations. It delivers information about radially integrated spectra and correlations. Langmuir probes measure density and potential fluctuations with good spatial resolution. The edge transport governs the physics in the scrape-off layer and in the divertor which is extremely important for a reactor and therefore deserves a major experimental effort. In this paper we report on an attempt to gain detailed information about the spatial and temporal structure of the edge turbulence hoping to reduce the degrees of freedom for theoretical models to a manageable number. (author) 3 refs., 3 figs.

  10. Structure of density fluctuations in the edge plasma of ASDEX

    International Nuclear Information System (INIS)

    Rudyj, A.; Carlson, A.; Endler, M.; Giannone, L.; Niedermeyer, H.; Theimer, G.

    1990-01-01

    It is now generally believed that the anomalous particle and energy transport in tokamaks is caused by turbulent fluctuations. The physical nature of these fluctuations (mode type, the driving mechanism) have still to be identified experimentally before a self consistent transport theory can be developed. In contrast to the confinement region the plasma edge can be well diagnosed. H α -light, which is emitted at the edge, reacts to density and to some extend to temperature fluctuations. It delivers information about radially integrated spectra and correlations. Langmuir probes measure density and potential fluctuations with good spatial resolution. The edge transport governs the physics in the scrape-off layer and in the divertor which is extremely important for a reactor and therefore deserves a major experimental effort. In this paper we report on an attempt to gain detailed information about the spatial and temporal structure of the edge turbulence hoping to reduce the degrees of freedom for theoretical models to a manageable number. (author) 3 refs., 3 figs

  11. Magnetic fluctuations associated with density fluctuations in the tokamak edge

    International Nuclear Information System (INIS)

    Kim, Y.J.; Gentle, K.W.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.

    1989-01-01

    Electrostatic density and potential fluctuations occurring with high amplitude near the edge of a tokamak are correlated with components of the fluctuating magnetic field measured outside the limiter radius. It has been established that this turbulence is associated with fluctuations in current as well as density and potential. The correlation extends for substantial toroidal distances, but only if the probes are displaced approximately along field lines, consistent with the short coherence lengths poloidally but long coherence lengths parallel to the field which are characteristic for this turbulence. Furthermore, the correlation can be found only with density fluctuations measured inside the limiter radius; density fluctuations behind the limiter have no detectable magnetic concomitant for the toroidally spaced probes used here. (author). Letter-to-the-editor. 12 refs, 3 figs

  12. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Chan, V.S.; Chen, L.

    1998-12-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n ∼ 2--9 and a fast growth time γ -1 = 20--150 micros are often observed prior to the first giant type 1 ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n > 1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region

  13. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Ferron, J.R.; Miller, R.L.

    2001-01-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n∼2-9 and a fast growth time γ -1 =20-150μs are often observed prior to the first giant type I ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n>1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region. (author)

  14. Spatiotemporal response of plasma edge density and temperature to non-axisymmetric magnetic perturbations at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Fischer, R; Fuchs, J C; McDermott, R; Rathgeber, S K; Suttrop, W; Wolfrum, E; Willensdorfer, M

    2012-01-01

    Non-axisymmetric magnetic perturbations (MPs) were successfully applied at ASDEX Upgrade to substantially reduce the plasma energy loss and peak divertor power load that occur concomitant with type-I edge localized modes (ELMs). The response of electron density edge profiles and temperature and pressure pedestal-top values to MPs are reported. ELM mitigation is observed above an edge density threshold and independent of the MPs being resonant or non-resonant with the edge safety factor. The edge electron collisionality appears not to be appropriate to separate mitigated from non-mitigated discharges for the present high-collisionality plasmas. No significant change in the position or gradient of the edge density profile could be observed for the transition into the ELM-mitigated phase, except from the effect of the three-dimensional MP field which leads to an apparent profile shift. An increase in the density and decrease in the temperature at the pedestal-top balance such that the pressure saturates at the value of the pre-mitigated phase. The plasma stored energy, the normalized plasma pressure, and the H-mode quality factor follow closely the evolution of the pedestal-top pressure and thus remain almost unaffected. The temporal evolution of the ion effective charge shows that the impurity content does not increase although flushing through type-I ELMs is missing. The type-I ELMs are replaced in the mitigated phase by small-scale and high-frequency edge perturbations. The effect of the small bursts on the density profile, which is correlated with a transient increase of the divertor thermoelectric current, is small compared with the effect of the type-I ELMs. The residual scatter of the profiles in the mitigated phase is small directly after the transition into the ELM-mitigated phase and increases again when the pressure saturates at the value of the pre-mitigated phase. (paper)

  15. Lower-hybrid counter current drive for edge current density modification in DIII-D

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Nevins, W.M.; Porkolab, M.; Bonoli, P.T.; Harvey, R.W.

    1994-01-01

    Each of the Advanced Tokamak operating modes in DIII-D is thought to have a distinctive current density profile. So far these modes have only been achieved transiently through experiments which ramp the plasma current and shape. Extension of these modes to steady state requires non-inductive current profile control, e.g., with lower hybrid current drive (LHCD). Calculations of LHCD have been done for DIII-D using the ACCOME and CQL3D codes, showing that counter driven current at the plasma edge can cancel some of the undesirable edge bootstrap current and potentially extend the VH-mode. Results will be presented for scenarios using 2.45 GHz LH waves launched from both the midplane and off-axis ports. The sensitivity of the results to injected power, n e and T e , and launched wave spectrum will also be shown

  16. Relaxation of potential, flows, and density in the edge plasma of Castor tokamak

    International Nuclear Information System (INIS)

    Hron, M.; Weinzettl, V.; Dufkova, E.; Duran, I.; Stoeckel, J.; Hidalgo, C.

    2004-01-01

    Decay times of plasma flows and plasma profiles have been measured after a sudden biasing switch-off in experiments on the Castor tokamak. A biased electrode has been used to polarize the edge plasma. The edge plasma potential and flows have been characterized by means of Langmuir and Mach probes, the radiation was measured using an array of bolometers. Potential profiles and poloidal flows can be well fitted by an exponential decay time in the range of 10 - 30 μs when the electrode biasing is turned off in the Castor tokamak. The radiation shows a slower time scale (about 1 ms), which is linked to the evolution in the plasma density and particle confinement. (authors)

  17. Effects of Density and Impurity on Edge Localized Modes in Tokamaks

    Science.gov (United States)

    Zhu, Ping

    2017-10-01

    Plasma density and impurity concentration are believed to be two of the key elements governing the edge tokamak plasma conditions. Optimal levels of plasma density and impurity concentration in the edge region have been searched for in order to achieve the desired fusion gain and divertor heat/particle load mitigation. However, how plasma density or impurity would affect the edge pedestal stability may have not been well known. Our recent MHD theory modeling and simulations using the NIMROD code have found novel effects of density and impurity on the dynamics of edge-localized modes (ELMs) in tokamaks. First, previous MHD analyses often predict merely a weak stabilizing effect of toroidal flow on ELMs in experimentally relevant regimes. We find that the stabilizing effects on the high- n ELMs from toroidal flow can be significantly enhanced with the increased edge plasma density. Here n denotes the toroidal mode number. Second, the stabilizing effects of the enhanced edge resistivity due to lithium-conditioning on the low- n ELMs in the high confinement (H-mode) discharges in NSTX have been identified. Linear stability analysis of the experimentally constrained equilibrium suggests that the change in the equilibrium plasma density and pressure profiles alone due to lithium-conditioning may not be sufficient for a complete suppression of the low- n ELMs. The enhanced resistivity due to the increased effective electric charge number Zeff after lithium-conditioning provides additional stabilization of the low- n ELMs. These new effects revealed in our theory analyses may help further understand recent ELM experiments and suggest new control schemes for ELM suppression and mitigation in future experiments. They may also pose additional constraints on the optimal levels of plasma density and impurity concentration in the edge region for H-mode tokamak operation. Supported by National Magnetic Confinement Fusion Science Program of China Grants 2014GB124002 and 2015GB

  18. Revisited neoclassical transport theory for steep, collisional plasma edge profiles

    International Nuclear Information System (INIS)

    Rogister, A.L.

    1994-01-01

    Published neoclassical results are misleading as concerns the plasma edge for they do not adequately take the peculiar local conditions into account, in particular the fact that the density and temperature variation length-scales are quite small. Coupled novel neoclassical equations obtain, not only for the evolution of the density and temperatures, but also for the radial electric field and the evolution of the parallel ion momentum: gyro-stresses and inertia indeed upset the otherwise de facto ambipolarity of particle transport and a radial electric field necessarily builds up. The increased nonlinear character of these revisited neoclassical equations widens the realm of possible plasma behaviors. (author)

  19. Current density profile evolution in JET

    International Nuclear Information System (INIS)

    Stubberfield, P.M.; Balet, B.; Campbell, D.; Challis, C.D.; Cordey, J.G.; O'Rourke, J.; Hammett, G.; Schmidt, G.L.

    1989-01-01

    Simulation studies have been made of the current density profile evolution in discharges where the bootstrap current is expected to be significant. The changes predicted in the total current profile have been confirmed by comparison with experimental results. (author) 8 refs., 6 figs

  20. Edge profiles and limiter tests in Extrap T2

    Science.gov (United States)

    Bergsåker, H.; Hedin, G.; Ilyinsky, L.; Larsson, D.; Möller, A.

    New edge profile measurements, including calorimetric measurements of the parallel heat flux, were made in Extrap T2. Test limiters of pure molybdenum and the TZM molybdenum alloy have been exposed in the edge plasma. The surface damage was studied, mainly by microscopy. Tungsten coated graphite probes were also exposed, and the surfaces were studied by microscopy, ion beam analysis and XPS. In this case cracking and mixing of carbon and tungsten at the interface was observed in the most heated areas, whereas carbide formation at the surface was seen in less heated areas. In these tests pure Mo generally fared better than TZM, and thin and cleaner coatings fared better than thicker and less clean.

  1. Profiles and fluctuations in edge and SOL turbulence

    DEFF Research Database (Denmark)

    Naulin, Volker; Xu, G.; Vianello, N.

    2012-01-01

    propagating structures and parallel transport sets up the observed profiles and how intermittency influences edge conditions. The filamentary blob structures also transport and generate currents in the SOL, which can be investigated by means of local magnetic diagnostics. Finally, the ratio of ion to electron...... temperature in the SOL is an important measure for the influence of finite larmor radius effects on the propagation properties of blobs. Numerical investigations indicate that these effects can lead to an increased self confinement and radial reach of these structures. © 2012 WILEY-VCH Verlag GmbH & Co. KGa...

  2. Density limit and cross-field edge transport scaling in Alcator C-Mod

    International Nuclear Information System (INIS)

    LaBombard, B.

    2002-01-01

    Experiments in Alcator C-Mod have uncovered a direct link between the character and scaling of edge transport and the empirical Greenwald density limit (n G ). In low to moderate density discharges, the scrape-off layer (SOL) exhibits a two-layer structure: a near SOL (∼5 mm zone) with steep density and temperature gradients and a far SOL with flatter profiles. In the far SOL, the transport fluxes exhibit large transport events ('bursts' which carry particles to main-chamber structures. In the near SOL, transport fluxes appear to be less 'bursty' particle diffusivities in this region is found to increase strongly with local plasma collisionality. As n/n G (or collisionality) is raised, cross-field heat convection begins to compete with parallel conduction to the divertor. At N/n G ∼0.5, T E at the separatrix is reduced. As n/n G approaches ∼1, regions inside the separatrix exhibit flatter profiles with 'bursty' transport behavior; cross-field heat convection to main-chamber structures becomes comparable to the radiated power. Thus as n/n G is increased, cross-field edge transport physics progressively changes, ultimately impacting the power balance of the discharge near N/n G ∼1. (author)

  3. The impact of edge gradients in the pressure, density, ion temperature, and electron temperature on edge-localized modes

    International Nuclear Information System (INIS)

    Kleva, Robert G.; Guzdar, Parvez N.

    2011-01-01

    The magnitude of the energy and particle fluxes in simulations of edge-localized modes (ELMs) is determined by the edge gradients in the pressure, density, ion temperature, and electron temperature. The total edge pressure gradient is the dominant influence on ELMs by far. An increase (decrease) of merely 2% in the pressure gradient results in an increase (decrease) of more than a factor of ten in the size of the ELM bursts. At a fixed pressure gradient, the size of the ELM bursts decreases as the density gradient increases, while the size of the bursts increases as the electron temperature gradient or, especially, the ion temperature gradient increases.

  4. Magnetic edge states in MoS2 characterized using density-functional theory

    DEFF Research Database (Denmark)

    Vojvodic, Aleksandra; Hinnemann, B.; Nørskov, Jens Kehlet

    2009-01-01

    It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional metallic edge states, the so-called "brim states." Here, we find from density-functional theory calculations that several edge structures, which are relevant for the hydrodesulfurization process......, are magnetic. The magnetism is an edge phenomenon associated with certain metallic edge states. Interestingly, we find that among the two low-index edges, only the S edge displays magnetism under hydrodesulfurization conditions. In addition, the implications of this on the catalytic activity are investigated...

  5. Influence of Wafer Edge Geometry on Removal Rate Profile in Chemical Mechanical Polishing: Wafer Edge Roll-Off and Notch

    Science.gov (United States)

    Fukuda, Akira; Fukuda, Tetsuo; Fukunaga, Akira; Tsujimura, Manabu

    2012-05-01

    In the chemical mechanical polishing (CMP) process, uniform polishing up to near the wafer edge is essential to reduce edge exclusion and improve yield. In this study, we examine the influences of inherent wafer edge geometries, i.e., wafer edge roll-off and notch, on the CMP removal rate profile. We clarify the areas in which the removal rate profile is affected by the wafer edge roll-off and the notch, as well as the intensity of their effects on the removal rate profile. In addition, we propose the use of a small notch to reduce the influence of the wafer notch and present the results of an examination by finite element method (FEM) analysis.

  6. A SURVEY OF CORONAL CAVITY DENSITY PROFILES

    International Nuclear Information System (INIS)

    Fuller, J.; Gibson, S. E.

    2009-01-01

    Coronal cavities are common features of the solar corona that appear as darkened regions at the base of coronal helmet streamers in coronagraph images. Their darkened appearance indicates that they are regions of lowered density embedded within the comparatively higher density helmet streamer. Despite interfering projection effects of the surrounding helmet streamer (which we refer to as the cavity rim), Fuller et al. have shown that under certain conditions it is possible to use a Van de Hulst inversion of white-light polarized brightness (pB) data to calculate the electron density of both the cavity and cavity rim plasma. In this article, we apply minor modifications to the methods of Fuller et al. in order to improve the accuracy and versatility of the inversion process, and use the new methods to calculate density profiles for both the cavity and cavity rim in 24 cavity systems. We also examine trends in cavity morphology and how departures from the model geometry affect our density calculations. The density calculations reveal that in all 24 cases the cavity plasma has a flatter density profile than the plasma of the cavity rim, meaning that the cavity has a larger density depletion at low altitudes than it does at high altitudes. We find that the mean cavity density is over four times greater than that of a coronal hole at an altitude of 1.2 R sun and that every cavity in the sample is over twice as dense as a coronal hole at this altitude. Furthermore, we find that different cavity systems near solar maximum span a greater range in density at 1.2 R sun than do cavity systems near solar minimum, with a slight trend toward higher densities for systems nearer to solar maximum. Finally, we found no significant correlation of cavity density properties with cavity height-indeed, cavities show remarkably similar density depletions-except for the two smallest cavities that show significantly greater depletion.

  7. Profiles of radiation power density in WEGA stellarator

    International Nuclear Information System (INIS)

    Zhang, D.; Otte, M.; Giannone, L.

    2005-01-01

    On the WEGA stellarator, a 12 channel bolometer camera has been used to measure the radiation power losses of the plasma, which is heated by ECR at 2.45 GHz with a maximum power of 26 kW. The typical electron temperatures achieved are around 10 eV. The bolometer is of the Au resistor type and is positioned on the mid-plane, viewing the plasma from the low-field side with a spatial resolution of about 6 cm. The viewing angle is opened to poloidally (±47 o ) and covers the whole cross-section. Angular profiles of radiation power density (emissivity) can be achieved using the measured fluxes to the channels, which are given by the integrals along the sight lines. Using Abel inversion with maximum entropy regularisation, radial profiles of emissivity could be obtained. It is found that the angular profile of emissivity depends on the magnetic configuration, the working gas (Ar, He) and the heating scenario. Peaked and hollow emissivity profiles have been obtained by using different types of heating antenna. By changing the magnetic configuration, strong edge radiation has been observed. The largest emissivity values are obtained in the upper SOL range of Ar-discharges. This edge radiation can be reduced by shifting the flux surfaces inwards or by changing their shape at the antenna. The reconstruction of the radial profile of the emissivity was carried out in the case of a peaked angular profile with minimum edge radiation. The total radiation power was estimated by linear extrapolation of the integrated radiation power in the viewing region to the torus volume. It is typically less than 30% of the ECRH input power, but depending on the ECRH input power, again the magnetic configuration, the working gas as well as the absolute field strength on the magnetic axis. Maximum radiation losses have been obtained around 0.6·B0, where B 0 =87.5 mT is the resonant field strength of the ECRH. No evidence for impurities was obtained from spectroscopic measurements, and thus the

  8. Density profile evolution during dynamic processes in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Nunes, I.; Santos, J.; Salzedas, F.; Manso, M.; Serra, F.; Conway, G.D.; Horton, L.D.; Neuhauser, J.; Suttrop, W.

    2005-01-01

    The current understanding of edge localized modes (ELMs) and the trigger of major disruptions is largely based on phenomenology. The need to better understand the processes underlying these phenomena requires high temporal and spatial resolution diagnostics. Fast diagnostics for the temperature measurements exist, such as the ECE radiometer but, for the plasma density, the existing diagnostics such as Lithium Beam and Thomson Scattering do not have the required high temporal resolution for a period long enough to characterize the entire ELM event. The microwave reflectometry system on ASDEX Upgrade has the capability to measure electron density profiles simultaneously at the low-field and high-field sides, in broadband swept ultrafast (35μs) operation with a spatial resolution of 5mm. In this paper we report on recent results on the effects of type I ELMs on density profiles and on the density pedestal width and ELM affected depth. During the ELM event, three phases are identified: precursor, collapse and recovery. The density pedestal width is found to be approximately constant for all the ELMy H-mode discharges analyzed here, except for high input power discharges, where an increase of the density pedestal width is observed. Major disruptions limit the range of parameters used in the operation of a tokamak, especially density limit disruptions, that limit the maximum usable density. Very abrupt increases of density are observed before the onset of the electron temperature profile erosion, supporting the hypothesis that this erosion is due to convection of the magnetic field. In ITER, during the long steady state flat-top phase of the discharges magnetic measurements may accumulate significant drifts. Plasma position and shape control using reflectometry is being assessed in ASDEX Upgrade for ITER like scenarios with successful results, where it is shown that position measurements from reflectometry compared to magnetic data satisfy the ITER requirements

  9. Comparison of neutral density profiles measured using Dα and C5+ in NSTX-U

    Science.gov (United States)

    Bell, R. E.; Scotti, F.; Diallo, A.; Leblanc, B. P.; Podesta, M.; Sabbagh, S. A.

    2017-10-01

    Edge neutral density profiles determined from two different measurements are compared on NSTX-U plasmas. Neutral density measurements were not typical on NSTX plasmas. An array of fibers dedicated to the measurement of passive emission of C5+, used to subtract background emission for charge exchange recombination spectroscopy (CHERS), can be used to infer deuterium neutral density near the plasma edge. The line emission from C5+ is dominated by charge exchange with neutral deuterium near the plasma edge. An edge neutral density diagnostic consisting of a camera with a Dα filter was installed on NSTX-U. The line-integrated measurements from both diagnostics are inverted to obtain local emissivity profiles. Neutral density is then inferred using atomics rates from ADAS and profile measurements from Thomson scattering and CHERS. Comparing neutral density profiles from the two diagnostic measurements helps determine the utility of using the more routinely available C5+ measurements for neutral density profiles. Initial comparisons show good agreement between the two measurements inside the separatrix. Supported by US DoE Contracts DE-AC02-09CH11466 and DE-AC52-07NA27344.

  10. Estimation and display of beam density profiles

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, S; Mukhopadhyay, T; Roy, A; Mallik, C

    1989-03-15

    A setup in which wire-scanner-type beam-profile monitor data are collected on-line in a nuclear data-acquisition system has been used and a simple algorithm for estimation and display of the current density distribution in a particle beam is described.

  11. Exact analytical density profiles and surface tension

    Indian Academy of Sciences (India)

    journal of. May 2005 physics pp. 785–801. Classical charged fluids at equilibrium near ... is provided by the excess surface tension for an air–water interface, which is determined ... the potential drop created by the electric layer which appears as soon as the fluid has ...... radii, by symmetry, the charge density profile is flat,.

  12. Midplane neutral density profiles in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Stotler, D. P., E-mail: dstotler@pppl.gov; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podestà, M.; Roquemore, A. L.; Ross, P. W. [Princeton Plasma Physics Laboratory, Princeton University, P. O. Box 451, Princeton, New Jersey 08543-0451 (United States); Scotti, F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-08-15

    Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-β light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-α emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 × 10{sup 17 }m{sup −3} and atomic densities ranging from 1 to 7 × 10{sup 16 }m{sup −3}; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. The uncertainties in the neutral densities associated with other model inputs and assumptions are ≤50%.

  13. Radiation profile measurements for edge transport barrier discharges in Compact Helical System using AXUV photodiode arrays

    International Nuclear Information System (INIS)

    Suzuki, C.; Okamura, S.; Minami, T.; Akiyama, T.; Fujisawa, A.; Ida, K.; Isobe, M.; Matsuoka, K.; Nagaoka, K.; Nishimura, S.; Peterson, B. J.; Shimizu, A.; Takahashi, C.; Toi, K.; Yoshimura, Y.

    2005-01-01

    The formation of edge transport barrier (ETB) has recently been found in Compact Helical System (CHS) plasmas heated by co-injected neutral beam injection (NBI) with strong gas puffing. This regime is characterized by the appearance of the steep gradient of the electron density near the edge following the abrupt drop of hydrogen Balmer alpha (H α ) line intensity. In addition to single channel pyroelectric detector as a conventional bolometer, we have employed unfiltered absolute extreme ultraviolet (AXUV) photodiode arrays as a simple and low-cost diagnostic to investigate spatial and temporal variations of radiation emissivity in the ETB discharges. A compact mounting module for a 20 channel AXUV photodiode array including an in-vacuum preamplifier for immediate current-voltage conversion has successfully been designed and fabricated. Two identical modules installed in the upper and lower viewports provide 40 lines of sight covering the inboard and outboard sides within the horizontally elongated cross section of the CHS plasma with wide viewing angle. Although spectral uniformity of the detector sensitivity of the AXUV photodiode is unsatisfied for photon energies lower than 200 eV, it has been confirmed that the signals of AXUV photodiode and pyroelectric detector in the ETB discharges show roughly the same behavior except for the very beginning and end of the discharges. The results of the measurements in typical ETB discharges show that the signals of all the channels of the AXUV photodiode arrays begin to increase more rapidly at the moment of the transition than before. The rate of the increase is larger for the edge viewing chords than for the center viewing ones, which indicates the flattening of the radiation profile following the change in the electron density profile after the formation of the ETB. However, the signals for the edge chords tend to saturate after several tens of milliseconds, while they still continue to increase for the central chords

  14. Ballooning mode stability for self-consistent pressure and current profiles at the H-mode edge

    International Nuclear Information System (INIS)

    Miller, R.L.; Lin-Liu, Y.R.; Osborne, T.H.; Taylor, T.S.

    1997-11-01

    The edge pressure gradient (H-mode pedestal) for computed equilibria in which the current density profile is consistent with the bootstrap current may not be limited by the first regime ballooning limit. The transition to second stability is easier for: higher elongation, intermediate triangularity, larger ratio, pedestal at larger radius, narrower pedestal width, higher q 95 , and lower collisionality

  15. Matter Density Profile Shape Effects at DUNE

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Kevin J. [Northwestern U.; Parke, Stephen J. [Fermilab

    2018-02-19

    Quantum mechanical interactions between neutrinos and matter along the path of propagation, the Wolfenstein matter effect, are of particular importance for the upcoming long-baseline neutrino oscillation experiments, specifically the Deep Underground Neutrino Experiment (DUNE). Here, we explore specifically what about the matter density profile can be measured by DUNE, considering both the shape and normalization of the profile between the neutrinos' origin and detection. Additionally, we explore the capability of a perturbative method for calculating neutrino oscillation probabilities and whether this method is suitable for DUNE. We also briefly quantitatively explore the ability of DUNE to measure the Earth's matter density, and the impact of performing this measurement on measuring standard neutrino oscillation parameters.

  16. Electon density profiles of the topside ionosphere

    Directory of Open Access Journals (Sweden)

    D. Bilitza

    2002-06-01

    Full Text Available The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h m F 2 to ~ 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350 000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status. html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2 down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling ~ 70% of the ionograms. An «editing process» is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle.

  17. Measurement of the lunar neutron density profile

    International Nuclear Information System (INIS)

    Woolum, D.S.; Burnett, D.S.; Furst, M.; Weiss, J.R.

    1975-01-01

    An in situ measurement of the lunar neutron density from 20 to 400 g cm -2 depth below the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment (LNPE) using particle tracks produced by the 10 B (n,α) 7 Li reaction. Both the absolute magnitude and the depth profile of the neutron density are in good agreement with theoretical calculations by Lingenfelter, Canfield, and Hampel. However, relatively small deviations between experiment and theory in the effect of Cd absorption on the neutron density and in the relative 149 Sm to 157 Gd capture rates reported previously (Russ et al., 1972) imply that the true lunar 157 Gd capture rate is about one half of that calculated theoretically. (Auth.)

  18. Electron density profile in multilayer systems

    International Nuclear Information System (INIS)

    Toekesi, K.

    2004-01-01

    Complete text of publication follows. Electron energy loss spectroscopy (EELS) has been used extensively to study the multilayer systems, where the thickness of layers are in the nanometer range. These studies has received considerable attention because of its technological interest, for example in the nanotechnology. On the most fundamental level, its importance is derived from the basic physics that is involved. One key quantities of interest is the response of a many-body system to an external perturbation: How act and how modify the interface between the solid-solid or solid-vacuum the excitations in the solid and in the vicinity of the interfaces. In this work, as a starting point of such investigations we calculated the electron density profile for multilayer systems. Our approach employs the time-dependent density functional theory (TDDFT), that is, the solution of a time-dependent Schroedinger equation in which the potential and forces are determined selfconsistently from the dynamics governed by the Schroedinger equation. We treat the problem in TDDFT at the level of the local-density approximation (LDA). Later, the comparison of experimentally obtained loss functions and the theory, based on our TDDFT calculations can provide deeper understanding of surface physics. We performed the calculations for half-infinite samples characterized by r s =1.642 and r s =1.997. We also performed the calculations for double layer systems. The substrate was characterized by r s =1.997 and the coverage by r s =1.642. Fig. 1. shows the obtained electron density profile in LDA approximation. Because of the sharp cutoff of electronic wave vectors at the Fermi surface, the densities in the interior exhibit slowly decaying Friedel oscillations. To highlight the Friedel oscillation we enlarged the electron density profile in Fig. 1a. and Fig. 1b. The work was supported by the Hungarian Scientific Research Found: OTKA No. T038016, the grant 'Bolyai' from the Hungarian Academy of

  19. Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.

    Science.gov (United States)

    Leyland, M J; Beurskens, M N A; Flanagan, J C; Frassinetti, L; Gibson, K J; Kempenaars, M; Maslov, M; Scannell, R

    2016-01-01

    The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.

  20. The influence of the edge density fluctuations on electron cyclotron wave beam propagation in tokamaks

    DEFF Research Database (Denmark)

    Bertelli, N.; Balakin, A.A.; Westerhof, E.

    2010-01-01

    are estimated in a vacuum beam propagation between the edge density layer and the EC resonance absorption layer. Consequences on the EC beam propagation are investigated by using a simplified model in which the density fluctuations are described by a single harmonic oscillation. In addition, quasi......A numerical analysis of the electron cyclotron (EC) wave beam propagation in the presence of edge density fluctuations by means of a quasi-optical code [Balakin A. A. et al, Nucl. Fusion 48 (2008) 065003] is presented. The effects of the density fluctuations on the wave beam propagation...

  1. Estimation of edge electron temperature profiles via forward modelling of the electron cyclotron radiation transport at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Rathgeber, S K; Barrera, L; Eich, T; Fischer, R; Suttrop, W; Wolfrum, E; Nold, B; Willensdorfer, M

    2013-01-01

    We present a method to obtain reliable edge profiles of the electron temperature by forward modelling of the electron cyclotron radiation transport. While for the core of ASDEX Upgrade plasmas, straightforward analysis of electron cyclotron intensity measurements based on the optically thick plasma approximation is usually justified, reasonable analysis of the steep and optically thin plasma edge needs to consider broadened emission and absorption profiles and radiation transport processes. This is carried out in the framework of integrated data analysis which applies Bayesian probability theory for joint analysis of the electron density and temperature with data of different interdependent and complementary diagnostics. By this means, electron cyclotron radiation intensity delivers highly spatially resolved electron temperature data for the plasma edge. In H-mode, the edge gradient of the electron temperature can be several times higher than the one of the radiation temperature. Furthermore, we are able to reproduce the ‘shine-through’ peak—the observation of increased radiation temperatures at frequencies resonant in the optically thin scrape-off layer. This phenomenon is caused by strongly down-shifted radiation of Maxwellian tail electrons located in the H-mode edge region and, therefore, contains valuable information about the electron temperature edge gradient. (paper)

  2. Interferometric density measurements in the divertor and edge plasma regions for the additionally heated JT-60 plasmas

    International Nuclear Information System (INIS)

    Fukuda, T.; Yoshida, H.; Nagashima, A.; Ishida, S.; Kikuchi, M.; Yokomizo, H.

    1989-01-01

    The first divertor plasma density measurement and the interferometric edge plasma density measurement with boundary condition preserving millimeter waveguides were demonstrated to elucidate the mutual correlation among the divertor plasma, scrape-off layer plasma and the bulk plasma properties in the additionally heated JT-60 plasmas. The electron density in the divertor region exhibited a nonlinear dependence on the bulk plasma density for the joule-heated plasmas. When neutral beam heating is applied on the plasmas with the electron density above 2x10 19 /m 3 , however, the bulk plasma density is scraped off from the outer region to lead to density clamping, and the electron density in the divertor region rapidly increases over 1x10 20 /m 3 , from which we can deduce that the particle flow along the magnetic field is dominant, resulting in the apparent degradation of the particle confinement time. As for the case when neutral beam injection is applied to low-density plasmas, the bulk plasma electron density profile becomes flattened to yield a smaller density increase in the divertor region and no density clamping of the bulk plasma was observed. Simulation analysis which correlates the transport of the divertor plasma and the scrape-off layer plasma was also carried out to find the consistency with the experimental results. (orig.)

  3. A novel technique for real-time estimation of edge pedestal density gradients via reflectometer time delay data

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, L., E-mail: zeng@fusion.gat.com; Doyle, E. J.; Rhodes, T. L.; Wang, G.; Sung, C.; Peebles, W. A. [Physics and Astronomy Department, University of California, Los Angeles, California 90095 (United States); Bobrek, M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6006 (United States)

    2016-11-15

    A new model-based technique for fast estimation of the pedestal electron density gradient has been developed. The technique uses ordinary mode polarization profile reflectometer time delay data and does not require direct profile inversion. Because of its simple data processing, the technique can be readily implemented via a Field-Programmable Gate Array, so as to provide a real-time density gradient estimate, suitable for use in plasma control systems such as envisioned for ITER, and possibly for DIII-D and Experimental Advanced Superconducting Tokamak. The method is based on a simple edge plasma model with a linear pedestal density gradient and low scrape-off-layer density. By measuring reflectometer time delays for three adjacent frequencies, the pedestal density gradient can be estimated analytically via the new approach. Using existing DIII-D profile reflectometer data, the estimated density gradients obtained from the new technique are found to be in good agreement with the actual density gradients for a number of dynamic DIII-D plasma conditions.

  4. The influence of the edge density fluctuations on electron cyclotron wave beam propagation in tokamaks

    International Nuclear Information System (INIS)

    Bertelli, N; Balakin, A A; Westerhof, E; Garcia, O E; Nielsen, A H; Naulin, V

    2010-01-01

    A numerical analysis of the electron cyclotron (EC) wave beam propagation in the presence of edge density fluctuations by means of a quasi-optical code [Balakin A. A. et al, Nucl. Fusion 48 (2008) 065003] is presented. The effects of the density fluctuations on the wave beam propagation are estimated in a vacuum beam propagation between the edge density layer and the EC resonance absorption layer. Consequences on the EC beam propagation are investigated by using a simplified model in which the density fluctuations are described by a single harmonic oscillation. In addition, quasi-optical calculations are shown by using edge density fluctuations as calculated by two-dimensional interchange turbulence simulations and validated with the experimental data [O. E. Garcia et al, Nucl. Fusion 47 (2007) 667].

  5. Density profile analysis during an ELM event in ASDEX Upgrade H-modes

    International Nuclear Information System (INIS)

    Nunes, I.; Manso, M.; Serra, F.; Horton, L.D.; Conway, G.D.; Loarte, A.

    2005-01-01

    This paper reports results on measurements of the density profiles. Here we analyse the behaviour of the electron density for a set of experiments in type I ELMy H-mode discharges in ASDEX Upgrade where the plasma current, plasma density, triangularity and input power were varied. Detailed measurements of the radial extent of the perturbation on the density profiles caused by the edge localized mode (ELM) crash (ELM affected depth), the velocity of the radial propagation of the perturbation as well as the width and gradient of the density pedestal are determined. The effect of a type I ELM event on the density profiles affects the outermost 20-40% of the plasma minor radius. At the scrape-off layer (SOL) the density profile broadens while in the pedestal region the density decreases resulting in a smaller density gradient. This change in the density profile defines a pivot point around which the density profile changes. The average radial velocity at the SOL is in the range 125-150 ms -1 and approximately constant for all the density layers far from the pivot point. The width of the density pedestal is approximately constant for all the ELMy H-mode discharges analysed, with values between 2 and 3.5 cm. These results are then compared with an analytical model where the width of the density is predominantly set by ionization (neutral penetration model). The width of the density profiles for L-mode discharges is included, since L- and H-mode have different particle transport. No agreement between the experimental results and the model is found

  6. Probing neutral density at the plasma edge of Tore Supra with CX excited impurity ions

    International Nuclear Information System (INIS)

    Hess, W.R.; Mattioli, M.; Guirlet, R.

    1993-01-01

    In Tokamak plasma physics renewed interest in visible spectroscopy has grown for two reasons. The use of fiber optics allows observation of local sources of both impurities and of hydrogen by observing radiation of low ionization states. Moreover, charge exchange spectroscopy (CXS) with either auxiliary or heating neutral beams is a standard technique to determine the ion temperature and impurity density profiles. After a short description of the experimental setup and the ergodic divertor of Tore Supra (TS), two discharges in which space-resolved observations of the CVI (8-7) line clearly show the presence of CX-related effects. A well isolated spectral line at 5304.6 A is discussed. Tentative identification as CIII (1s 2 2s, 7-5) is suggested. The conclusion shows the usefulness of the reported results for probing neutral density at the plasma edge by detecting CX excited impurity ions and that highly ionized C 6+ ions exist in the MARFE regions. To the best of our knowledge, only very low ionization C and O ions (such as CIII or OIV) have been previously reported in these regions

  7. Radiation power profiles and density limit with a divertor in the W7-AS stellarator

    International Nuclear Information System (INIS)

    Giannone, L.; Burhenn, R.; McCormick, K.; Brakel, R.; Feng, Y.; Grigull, P.; Igitkhanov, Y.

    2002-01-01

    The addition of a divertor into the W7-AS stellarator has allowed access to a high density regime where the radiation profiles reach a steady state. In earlier limiter discharges, the plasma suffered a radiative collapse at high densities. In contrast to limiter experiments, where the impurity confinement time measured by Al laser blow-off increased with increasing line integrated density, in divertor discharges, above a density threshold, the impurity confinement time decreased with increasing line integrated density. The observation that the divertor plasma radiates mainly at the plasma edge rather than the plasma centre is a further indication that changes to the impurity transport coefficients at these high densities are the basis for the achievement of steady state discharges in the divertor configuration of W7-AS. The maximum line integrated density reached with a divertor is compared to that reached with a limiter. The previously derived scaling law for the density limit with a limiter shows that the achieved densities do not exceed those predicted when the higher deposited power is taken into account. In a divertor the radiated power is located at the plasma edge and increasing the density, cooling the plasma edge and radiating sufficient power to cause plasma detachment determines the density limit. (author)

  8. Density profiles of the exclusive queuing process

    Science.gov (United States)

    Arita, Chikashi; Schadschneider, Andreas

    2012-12-01

    The exclusive queuing process (EQP) incorporates the exclusion principle into classic queuing models. It is characterized by, in addition to the entrance probability α and exit probability β, a third parameter: the hopping probability p. The EQP can be interpreted as an exclusion process of variable system length. Its phase diagram in the parameter space (α,β) is divided into a convergent phase and a divergent phase by a critical line which consists of a curved part and a straight part. Here we extend previous studies of this phase diagram. We identify subphases in the divergent phase, which can be distinguished by means of the shape of the density profile, and determine the velocity of the system length growth. This is done for EQPs with different update rules (parallel, backward sequential and continuous time). We also investigate the dynamics of the system length and the number of customers on the critical line. They are diffusive or subdiffusive with non-universal exponents that also depend on the update rules.

  9. Kinetic theory of neutrals in a bounded plasma slab with inhomogeneous temperature and density profile

    International Nuclear Information System (INIS)

    Tendler, M.B.; Agren, O.

    1982-01-01

    The transport of neutral hydrogen atoms in a hydrogen plasma slab is considered. The influence of the inhomogeneous ion temperature profile on the neutral density and distribution is discussed as well as the influence of the neutral edge energy, charge exchange, and ionization rates. The analytical solutions for the neutral density and distribution function are obtained and compared with the numerical results. The effects due to the inhomogeneous temperature profile are discussed. The recommen-dations from the viewpoint of the effects mentioned previously for the purposes of the cold-gas mantle system have been given

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stefanikova, E. [Institute of Plasma Physics of the CAS, Za Slovankou 1782/3, 180 00 Prague (Czech Republic); Division of Fusion Plasma Physics, KTH Royal Institute of Technology, SE-10691 Stockholm (Sweden); Peterka, M. [Institute of Plasma Physics of the CAS, Za Slovankou 1782/3, 180 00 Prague (Czech Republic); MFF Charles University, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Bohm, P., E-mail: bohm@ipp.cas.cz; Bilkova, P.; Aftanas, M.; Urban, J.; Hron, M.; Panek, R. [Institute of Plasma Physics of the CAS, Za Slovankou 1782/3, 180 00 Prague (Czech Republic); Sos, M. [Institute of Plasma Physics of the CAS, Za Slovankou 1782/3, 180 00 Prague (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic)

    2016-11-15

    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.

  12. New approach to the suction force at the leading edge of a profile with zero thickness

    NARCIS (Netherlands)

    Sparenberg, JA; de Jager, EM

    2004-01-01

    This paper considers the suction force at the leading edge of a profile with zero thickness in an incompressible and inviscid fluid flow. The theory is linear, and the approach to the suction force is from the innerside of the profile. It is shown that the suction force can be considered as an

  13. Simultaneous realization of high density edge transport barrier and improved L-mode on CHS

    International Nuclear Information System (INIS)

    Minami, Takashi; Okamura, Shoichi; Suzuki, Chihiro

    2008-10-01

    An edge transport barrier (ETB) formation and an improved L-mode (IL mode) have been simultaneously realized in high density region (n-bar e - 1.2x10 20 m -3 ) on Compact Helical System (CHS). When the ETB is formed during the IL mode, the density reduction in the edge region is suppressed by the barrier formation. As a result of the continuous increasing of the temperature by the IL mode, the stored energy during the combined mode increased up to the maximum stored energy (W p - 9.4 kJ) recorded in CHS experiments. The plasma pressure in the peripheral region increases up to three times larger than that of the L-mode, and the large edge plasma pressure gradient is formed accompanying the pedestal structure. That is caused by the anomalous transport reduction that is confirmed from the sharp drop of the density fluctuation in the edge region. The neutral particle reduction in the peripheral region and the metallic impurity accumulation in the core plasma are simultaneously observed during the high density ETB formation. (author)

  14. Electron density profile determination by means of laser blow-off injected neutral beam

    International Nuclear Information System (INIS)

    Kocsis, G.; Bakos, J.S.; Ignacz, P.N.; Kardon, B.; Koltai, L.; Veres, G.

    1992-01-01

    This paper is devoted to the experimental and theoretical studies of the determination of the electron density profiles by means of laser blow-off neutrals. For the determination of the density profile the time and spatial distributions of the spectral line radiation intensity of the injected neutrals are used. The method is compared to other previously proposed methods and the advantages and disadvantages of the different methods are discussed. The result of the comparison is that our method gives the most reliable result with the highest temporal resolution for the density profile of the edge plasma. The only disadvantage is the need of careful calibration of the sensitivity of the spatial channels. The advantage is the ability of the method as a standard diagnostic. (orig.)

  15. The virialization density of peaks with general density profiles under spherical collapse

    OpenAIRE

    Rubin, Douglas; Loeb, Abraham

    2013-01-01

    We calculate the non-linear virialization density, $\\Delta_c$, of halos under spherical collapse from peaks with an arbitrary initial and final density profile. This is in contrast to the standard calculation of $\\Delta_c$ which assumes top-hat profiles. Given our formalism, the non-linear halo density can be calculated once the shape of the initial peak's density profile and the shape of the virialized halo's profile are provided. We solve for $\\Delta_c$ for halos in an Einstein de-Sitter an...

  16. Advances in the density profile evaluation from broadband reflectometry on ASDEX upgrade

    International Nuclear Information System (INIS)

    Varela, P.; Manso, M.; Conway, G.

    2001-01-01

    The high temporal and spatial resolutions provided by broadband microwave reflectometry make it an attractive diagnostic technique to measure the density profile in fusion plasmas. However, great problems have been encountered due to the plasma turbulence that difficult, and sometimes prevent, the routine evaluation of density profiles. Advanced broadband systems employ ultra-fast sweeping in an attempt to perform the profile measurement in a time window smaller than the temporal scale of the main plasma fluctuations but this is not sufficient. Indeed, abrupt plasma movements and/or spatial turbulence always affect the reflectometry signals, as shown by numerical studies (with both one- and two-dimensional codes), for the case of ultra-fast sweeping and pulse radar systems. For this reason not only the system performance is important but the software tools also play a crucial role for reflectometry to become a standard density profile diagnostic. Here we present the recent advances towards automatic evaluation of density profiles from broadband reflectometry on ASDEX Upgrade. For regimes with moderate levels of plasma turbulence, density profiles are obtained from single reflectometry samples (temporal resolution of 20 μs), and for higher turbulence levels average profiles are obtained from bursts of ultra-fast (20 μs), closely spaced (10 μs) sweeps. This method improved the accuracy and reliability of density profiles, which can now be obtained automatically from the edge to the bulk plasma - using reflectometry alone - in most plasma regimes of ASDEX Upgrade. New data processing capability has been implemented that allows the profiles to be available to the end-users 10-12 minutes after each discharge. These developments were possible due to the flexibility and high performance of the control and data acquisition systems and to the large number of measurements that can be performed with the diagnostic during each discharge (720 profiles both on the low- and

  17. NEW CONCEPTS AND TEST METHODS OF CURVE PROFILE AREA DENSITY IN SURFACE: ESTIMATION OF AREAL DENSITY ON CURVED SPATIAL SURFACE

    OpenAIRE

    Hong Shen

    2011-01-01

    The concepts of curve profile, curve intercept, curve intercept density, curve profile area density, intersection density in containing intersection (or intersection density relied on intersection reference), curve profile intersection density in surface (or curve intercept intersection density relied on intersection of containing curve), and curve profile area density in surface (AS) were defined. AS expressed the amount of curve profile area of Y phase in the unit containing surface area, S...

  18. Effect of readout direction in the edge profile on the modulation transfer function of computed radiographic systems by use of the edge method.

    Science.gov (United States)

    Tanaka, Nobukazu; Morishita, Junji; Tsuda, Norisato; Ohki, Masafumi

    2013-07-01

    We investigated the effect of the readout direction of the edge profile obtained by the edge method on the presampled modulation transfer function (MTF) in various computed radiographic (CR) systems. There were no differences in the MTFs derived from two edge profiles in the sub-scanning direction of four CR systems used in this study. On the other hand, the MTFs measured at a readout direction from the low (edge) to the high (direct exposure) exposure region were higher than those measured at a readout direction from the high to the low exposure region in the laser-beam scanning direction for three of the four CR systems. Although this phenomenon depends on the CR system, it is important to understand and indicate both MTFs at the two edge profiles in the laser-beam scanning direction for accurate assessment of the resolution property.

  19. In-vitro studies of change in edge detection with changes in bone density

    International Nuclear Information System (INIS)

    Pocock, N.; Noakes, K.; Griffiths, M.

    1999-01-01

    Full text: Dual energy X-ray absorptiometry (DXA) requires edge detection software to identify the skeletal regions for quantitation of bone mineral density (BMD) and bone mineral content (BMC). As bone mass decreases, the detection of bone edges becomes more difficult and this potentially could cause errors in DXA estimations of areal BMD or BMC. To address this issue, we have used an in-vitro model to study the effects of 'bone loss' on calculated bone area, BMD and BMC. Multiple vertebral phantoms, of equal cross-sectional area but incrementally decreased areal BMD, were constructed using calcium sulphate hemihydrate. The weight of each phantom vertebra, measured accurately using an electronic balance, was used as an index of its true 'bone mass equivalent' (BME). The phantoms were scanned and analysed in the lumbar spine mode using a Lunar DPX-L (L) and Hologic QDR-1000 (H). The changes in BME were compared to changes in measured area, BMC and areal BMD. The results demonstrate that, in an in-vitro model, as bone mass decreases, measured bone area and consequently BMC will decrease as the edge detection algorithms have greater difficulty in detecting the true edges. In conclusion, in an in-vitro model, the DXA edge detection algorithms will underestimate bone area as bone mass decreases. This has potential implications for monitoring changes in bone mass in vivo

  20. Core fueling to produce peaked density profiles in large tokamaks

    International Nuclear Information System (INIS)

    Mikkelsen, D.R.; McGuire, K.M.; Schmidt, G.L.; Zweben, S.J.

    1994-06-01

    Peaking the density profile increases the usable bootstrap current and the average fusion power density; this could reduce the current drive power and increase the net output of power producing tokamaks. The use of neutral beams and pellet injection to produce peaked density profiles is assessed. We show that with radially ''hollow'' diffusivity profiles (and no particle pinch) moderately peaked density profiles can be produced by particle source profiles which are peaked off-axis. The fueling penetration requirements can therefore be relaxed and this greatly improves the feasibility of generating peaked density profiles in large tokamaks. In particular, neutral beam fueling does not require MeV particle energy. Even with beam voltages of ∼200 keV, however, exceptionally good particle confinement, τ p much-gt τ E is required to achieve net electrical power generation. In system with no power production requirement (e.g., neutron sources) neutral beam fueling should be capable of producing peaked density profiles in devices as large as ITER. Fueling systems with low energy cost per particle (such as cryogenic pellet injection) must be used in power producing tokamaks when τ p ∼ τ E . Simulations with pellet injection speeds of 7 km/sec show the peaking factor, n eo /left-angle n e right-angle, approaching 2

  1. Core fuelling to produce peaked density profiles in large tokamaks

    International Nuclear Information System (INIS)

    Mikkelsen, D.R.; McGuire, K.M.; Schmidt, G.L.; Zweben, S.J.

    1995-01-01

    Peaking the density profile increases the usable bootstrap current and the average fusion power density; this could reduce the current drive power and increase the net output of power producing tokamaks. The use of neutral beams and pellet injection to produce peaked density profiles is assessed. It is shown that with radially 'hollow' diffusivity profiles (and no particle pinch) moderately peaked density profiles can be produced by particle source profiles that are peaked off-axis. The fuelling penetration requirements can therefore be relaxed and this greatly improves the feasibility of generating peaked density profiles in large tokamaks. In particular, neutral beam fuelling does not require Megavolt particle energies. Even with beam voltages of ∼ 200 keV, however, exceptionally good particle confinement is needed to achieve net electrical power generation. The required ratio of particle to thermal diffusivities is an order of magnitude outside the range reported for tokamaks. In a system with no power production requirement (e.g., neutron sources) neutral beam fuelling should be capable of producing peaked density profiles in devices as large as ITER. Fuelling systems with low energy cost per particle - such as cryogenic pellet injection - must be used in power producing tokamaks when τ P ∼ τ E . Simulations with pellet injection speeds of 7 km/s show that the peaking factor, n e0 / e >, approaches 2. (author). 65 refs, 8 figs

  2. Density limit and cross-field edge transport scaling in Alcator C-Mod

    International Nuclear Information System (INIS)

    LaBombard, B.; Greenwald, M.; Hughes, J.W.; Lipschultz, B.; Mossessian, D.; Terry, J.L.; Boivin, R.L.; Carreras, B.A.; Pitcher, C.S.; Zweben, S.J.

    2003-01-01

    Recent experiments in Alcator C-Mod have uncovered a direct link between the character and scaling of cross-field particle transport in the edge plasma and the density limit, n G . As n-bar e /n G is increased from low values to values approaching ∼1, an ordered progression in the cross-field edge transport physics occurs: first benign cross-field heat convection, then cross-field heat convection impacting the scrape-off layer (SOL) power loss channels and reducing the separatrix electron temperature, and finally 'bursty' transport (normally associated with the far SOL) invading into closed flux surface regions and carrying a convective power loss that impacts the power balance of the discharge. These observations suggest that SOL transport and its scaling with plasma conditions plays a key role in setting the empirically observed density limit scaling law. (author)

  3. Electron-cyclotron wave scattering by edge density fluctuations in ITER

    Science.gov (United States)

    Tsironis, Christos; Peeters, Arthur G.; Isliker, Heinz; Strintzi, Dafni; Chatziantonaki, Ioanna; Vlahos, Loukas

    2009-11-01

    The effect of edge turbulence on the electron-cyclotron wave propagation in ITER is investigated with emphasis on wave scattering, beam broadening, and its influence on localized heating and current drive. A wave used for electron-cyclotron current drive (ECCD) must cross the edge of the plasma, where density fluctuations can be large enough to bring on wave scattering. The scattering angle due to the density fluctuations is small, but the beam propagates over a distance of several meters up to the resonance layer and even small angle scattering leads to a deviation of several centimeters at the deposition location. Since the localization of ECCD is crucial for the control of neoclassical tearing modes, this issue is of great importance to the ITER design. The wave scattering process is described on the basis of a Fokker-Planck equation, where the diffusion coefficient is calculated analytically as well as computed numerically using a ray tracing code.

  4. Step Density Profiles in Localized Chains

    Science.gov (United States)

    De Roeck, Wojciech; Dhar, Abhishek; Huveneers, François; Schütz, Marius

    2017-06-01

    We consider two types of strongly disordered one-dimensional Hamiltonian systems coupled to baths (energy or particle reservoirs) at the boundaries: strongly disordered quantum spin chains and disordered classical harmonic oscillators. These systems are believed to exhibit localization, implying in particular that the conductivity decays exponentially in the chain length L. We ask however for the profile of the (very slowly) transported quantity in the steady state. We find that this profile is a step-function, jumping in the middle of the chain from the value set by the left bath to the value set by the right bath. This is confirmed by numerics on a disordered quantum spin chain of 9 spins and on much longer chains of harmonic oscillators. From theoretical arguments, we find that the width of the step grows not faster than √{L}, and we confirm this numerically for harmonic oscillators. In this case, we also observe a drastic breakdown of local equilibrium at the step, resulting in a heavily oscillating temperature profile.

  5. Current profile control and magnetohydrodynamic stability in Tore Supra discharges with edge-plasma control by the ergodic divertor

    International Nuclear Information System (INIS)

    Zabiego, M.; Friant, C.; Ghendrih, P.; Becoulet, M.; Bucalossi, J.; Saint-Laurent, F.

    1999-01-01

    Although ergodic divertors are primarily designed to control particle and heat fluxes at the plasma edge, they also happen to affect the MHD stability of tokamak discharges. On Tore Supra, the ergodic divertor has long been known to stabilize the m/n=2/1 tearing mode induced, for instance, by edge radiation and detachment processes, thus allowing safe high-current and high-density operations. More recently, though, in discharges where ergodic divertor operations were optimised relative to the control of the edge-plasma (i.e., with large divertor perturbation), a detrimental increase in the disruptiveness has been observed. The action that the ergodic divertor has on the MHD activity is interpreted in terms of a redistribution of the current profile. The latter results from a large increase in the edge resistivity, primarily induced by the degradation of the electron energy confinement in the ergodic layer. The possibility that a transport barrier develops in the vicinity of the separatrix strongly affects the considered modelling. (authors)

  6. Comparative study of the electron density profiles in the compact torus plasma merging experiments

    International Nuclear Information System (INIS)

    Hayashiya, Hitoshi; Asaka, Takeo; Katsurai, Makoto

    2003-01-01

    Following two previous papers on the comparative studies of the electron density distributions for a single compact torus (CT) and a spherical tokamak (ST), and for the a single ST and a merged ST, a comparative study on the dynamics of the electron density profile and after the CT and ST plasma merging process was performed. The sharpness of the peak in the electron density profile around the mid-plane just after the merging of CT with a low safety factor (q value) such as RFP or spheromak is found to be related to the speed of the magnetic axis during the plasma merging process. It is also found that the electron density gradient near the plasma edge in a high q ST is larger than that of a low q CT. High q ST is found to be provided with the magnetic structure which is able to sustain a large thermal pressure by a strong j x B force. Despite these differences in the electron density profile between CT and ST during merging, the confinement characteristics evaluated from the number of electrons confined within the magnetic separatrix after the completion of the merging is almost similar between in the merging CT and in the merging ST. For all configurations, the electron density profiles after the completion of the merging are analogous to those of the corresponding single configuration produced without the merging process. (author)

  7. Edge stability and pedestal profile sensitivity of snowflake diverted equilibria in the TCV Tokamak

    International Nuclear Information System (INIS)

    Medvedev, S.Yu.; Ivanov, A.A.; Martynov, A.A.; Poshekhonov, Yu.Yu.; Behn, R.; Martin, Y.R.; Moret, J.M.; Piras, F.; Pitzschke, A.; Pochelon, A.; Sauter, O.; Villard, L.

    2010-01-01

    A second order null divertor (snowflake) has been successfully created and controlled in the TCV tokamak[1] (F. Piras et al., Plasma Phys. Control. Fusion, 2009). The results of ideal MHD edge stability computations show an enhancement of the edge stability properties of the snowflake equilibria compared to standard x-point configurations[2] (S. Yu. Medvedev et al., 36th EPS Conference on Plasma Physics, 2009). However, a sensitivity study of the stability limits to variations of the pedestal profiles is essential for making conclusions about possibilities of ELM control in snowflake plasmas. Variations of the edge stability and beta limits for several types of snowflake equilibria, different values of triangularity and various pedestal profiles are investigated (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Thickness Evaluation of Pipeline Using Density Profile on a Radiograph

    International Nuclear Information System (INIS)

    Lee, Sung Sik; Jang, Byoung Gyu; Kim, Young H.

    2002-01-01

    The computer simulation has been done for non-insulated and insulated pipes which are vacant or half filled with liquid. The simulation results showed that the density profile on the radiography is continuous and symmetrical around the center of pipe in the case of vacant pipe. On the other hand the density profiles are not symmetrical and depend on geometrical setting for radiography in the case of half filled pipes. Finally, experimental testing on a non-insulated carbon steel pipe with artificial notches of different depth is carried out using Ir-192 and industrial film. Comparing the measured density profile on the radiograph to the calculated one, it has been shown that it is possible to evaluate thickness variation by measuring density profile on a radiograph

  9. Leading-Edge Noise Prediction of General Airfoil Profiles with Spanwise-Varying Inflow Conditions

    NARCIS (Netherlands)

    Miotto, Renato Fuzaro; Wolf, William Roberto; De Santana, Leandro Dantas

    2018-01-01

    This paper presents a study of the leading-edge noise radiated by an airfoil undergoing a turbulent inflow. The noise prediction of generic airfoil profiles subjected to spanwise-varying inflow conditions is performed with the support of Amiet’s theory and the inverse strip technique. In the

  10. Leading-Edge Noise Prediction of General Airfoil Profiles with Spanwise-Varying Inflow Conditions

    NARCIS (Netherlands)

    Miotto, Renato Fuzaro; Wolf, William Roberto; De Santana, Leandro Dantas

    This paper presents a study of the leading-edge noise radiated by an airfoil undergoing a turbulent inflow. The noise prediction of generic airfoil profiles subjected to spanwise-varying inflow conditions is performed with the support of Amiet’s theory and the inverse strip technique. In the

  11. Electron density profile measurements by microwave reflectometry on Tore Supra

    International Nuclear Information System (INIS)

    Clairet, F.; Paume, M.; Chareau, J.M.

    1995-01-01

    A proposal is presented developing reflectometry diagnostic for electron density profile measurements as routine diagnostic without manual intervention as achieved at JET. Since density fluctuations seriously perturb the reflected signal and the measurement of the group delay, a method is described to overcome the irrelevant results with the help of an adaptive filtering technique. Accurate profiles are estimated for about 70% of the shots. (author) 3 refs.; 6 figs

  12. External kink mode stability of tokamaks with finite edge current density in plasma outside separatrix

    International Nuclear Information System (INIS)

    Degtyarev, L.; Martynov, A.; Medvedev, S.; Troyon, F.; Villard, L.

    1996-01-01

    Large pressure gradients and current density at the plasma edge and accompanying edge-localized MHD instabilities are typical for H-mode discharges. Low-n external kink modes are a possible cause of the instabilities. The paper mostly deals with external kink modes driven by a finite current density at the plasma boundary (so called peeling modes). It was shown earlier that for a single axis plasma embedded into vacuum the peeling modes are stabilized when separatrix is approaching the plasma boundary. For doublet configurations a finite current density at the internal separatrix does not necessarily lead to external kink instability when the current density vanishes at the boundary. However, a finite current density at the plasma boundary outside the separatrix can drive outer peeling modes. The stability properties and structure of these modes depend on the plasma equilibrium outside the separatrix. The influence of plasma shear and pressure gradient at the boundary on the stability of the outer peeling modes in doublets is studied. The stability of kink modes in divertor configurations with plasma outside the separatrix is very sensitive to the boundary conditions set at open field lines. The choice of the boundary conditions and kink mode stability calculations for the divertor configurations are discussed. (author) 4 figs., 5 refs

  13. Electron Density Profile Data Contains Virtual Height/Frequency Pairs from a Profile or Profiles (Composite Months) of Ionograms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Electron Density Profile, N(h), data set contains both individual profiles and composite months. The data consist of virtual height/frequency pairs from a...

  14. Space potential, temperature, and density profile measurements on RENTOR

    International Nuclear Information System (INIS)

    Schoch, P.M.

    1983-05-01

    Radial profiles of the space potential, electron temperature, and density have been measured on RENTOR with a heavy-ion-beam probe. The potential profile has been compared to predictions from a stochastic magnetic field fluctuation theory, using the measured temperature and density profiles. The comparison shows strong qualitative agreement in that the potential is positive and the order of T/sub e//e. There is some quantitative disagreement in that the measured radial electric fields are somewhat smaller than the theoretical predictions. To facilitate this comparison, a detailed analysis of the possible errors has been completed

  15. Measurements of electron density profiles using an angular filter refractometer

    International Nuclear Information System (INIS)

    Haberberger, D.; Ivancic, S.; Hu, S. X.; Boni, R.; Barczys, M.; Craxton, R. S.; Froula, D. H.

    2014-01-01

    A novel diagnostic technique, angular filter refractometry (AFR), has been developed to characterize high-density, long-scale-length plasmas relevant to high-energy-density physics experiments. AFR measures plasma densities up to 10 21  cm −3 with a 263-nm probe laser and is used to study the plasma expansion from CH foil and spherical targets that are irradiated with ∼9 kJ of ultraviolet (351-nm) laser energy in a 2-ns pulse. The data elucidate the temporal evolution of the plasma profile for the CH planar targets and the dependence of the plasma profile on target radius for CH spheres

  16. Measurements of electron density profiles using an angular filter refractometer

    Energy Technology Data Exchange (ETDEWEB)

    Haberberger, D., E-mail: dhab@lle.rochester.edu; Ivancic, S.; Hu, S. X.; Boni, R.; Barczys, M.; Craxton, R. S.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14636 (United States)

    2014-05-15

    A novel diagnostic technique, angular filter refractometry (AFR), has been developed to characterize high-density, long-scale-length plasmas relevant to high-energy-density physics experiments. AFR measures plasma densities up to 10{sup 21} cm{sup −3} with a 263-nm probe laser and is used to study the plasma expansion from CH foil and spherical targets that are irradiated with ∼9 kJ of ultraviolet (351-nm) laser energy in a 2-ns pulse. The data elucidate the temporal evolution of the plasma profile for the CH planar targets and the dependence of the plasma profile on target radius for CH spheres.

  17. Edge profiles in K shell photoabsorption spectra of gaseous hydrides of 3p elements and homologues

    Science.gov (United States)

    Hauko, R.; Gomilšek, J. Padežnik; Kodre, A.; Arčon, I.; Aquilanti, G.

    2017-10-01

    Photoabsorption spectra of gaseous hydrides of 3p elements (PH3, H2S, HCl) are measured in the energy region of photoexcitations pertaining to K edge. The analysis of the edge profile is extended to hydrides of 4p series (GeH4, AsH3, H2Se, HBr) from an earlier experiment, and to published spectra of 2p hydrides (CH4, NH3, H2O, HF) and noble gases Ar, Kr and Ne and SiH4. The edge profiles are modelled with a linear combination of lorentzian components, describing excitations to individual bound states and to continuum. Transition energies and probabilities are also calculated in the non-relativistic molecular model of the ORCA code, in good agreement with the experiment. Edge profiles in the heavier homologues are closely similar, the symmetry of the molecule governs the transitions to the lowest unoccupied orbitals. In 2p series the effect of the strong nuclear potential prevails. Transitions to higher, atomic-like levels remain very much the same as in free atoms.

  18. Effect of low density H-mode operation on edge and divertor plasma parameters

    International Nuclear Information System (INIS)

    Maingi, R.; Mioduszewski, P.K.; Cuthbertson, J.W.

    1994-07-01

    We present a study of the impact of H-mode operation at low density on divertor plasma parameters on the DIII-D tokamak. The line-average density in H-mode was scanned by variation of the particle exhaust rate, using the recently installed divertor cryo-condensation pump. The maximum decrease (50%) in line-average electron density was accompanied by a factor of 2 increase in the edge electron temperature, and 10% and 20% reductions in the measured core and divertor radiated power, respectively. The measured total power to the inboard divertor target increased by a factor of 3, with the major contribution coming from a factor of 5 increase in the peak heat flux very close to the inner strike point. The measured increase in power at the inboard divertor target was approximately equal to the measured decrease in core and divertor radiation

  19. Edge density fluctuation diagnostic for DIII-D using lithium beams: 1992 annual report

    International Nuclear Information System (INIS)

    Thomas, D.M.

    1994-01-01

    During the past several months the Lithium beam diagnostic was commissioned of DIII-D and began yielding useful information. The author developed the remote control and monitoring of the ion source operation and beam formation and focussing, and integrated the control system and data acquisition into the DIII-D operating system. Several detector types were fabricated, and fluorescence data were collected using several differing detector arrangements. Beam-gas measurements were conducted to analyze the intrinsic beam fluctuations and stability. Fluorescence data was then obtained on a number of Tokamak discharges under varying discharge conditions. Analysis of this initial data is proceeding but has already yielded some interesting features. These include changes in the edge plasma density behavior during the l- to h-transition, disruptions, and edge localized modes (ELMs). Based on the quality of data obtained the author proceeded with the design and construction of the full 16-channel detection system which will be completed and tested shortly

  20. Edge-enriched, porous carbon-based, high energy density supercapacitors for hybrid electric vehicles.

    Science.gov (United States)

    Kim, Yong Jung; Yang, Cheol-Min; Park, Ki Chul; Kaneko, Katsumi; Kim, Yoong Ahm; Noguchi, Minoru; Fujino, Takeshi; Oyama, Shigeki; Endo, Morinobu

    2012-03-12

    Supercapacitors can store and deliver energy by a simple charge separation, and thus they could be an attractive option to meet transient high energy density in operating fuel cells and in electric and hybrid electric vehicles. To achieve such requirements, intensive studies have been carried out to improve the volumetric capacitance in supercapacitors using various types and forms of carbons including carbon nanotubes and graphenes. However, conventional porous carbons are not suitable for use as electrode material in supercapacitors for such high energy density applications. Here, we show that edge-enriched porous carbons are the best electrode material for high energy density supercapacitors to be used in vehicles as an auxiliary powertrain. Molten potassium hydroxide penetrates well-aligned graphene layers vertically and consequently generates both suitable pores that are easily accessible to the electrolyte and a large fraction of electrochemically active edge sites. We expect that our findings will motivate further research related to energy storage devices and also environmentally friendly electric vehicles. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Edge operational space for high density/high confinement ELMY H-modes in JET

    International Nuclear Information System (INIS)

    Sartori, R.; Saibene, G.; Loarte, A.

    2002-01-01

    This paper discusses how the proximity to the L-H threshold affects the confinement of ELMy H-modes at high density. The largest reduction in confinement at high density is observed at the transition from the Type I to the Type III ELMy regime. At medium plasma triangularity, δ≅0.3 (where δ is the average triangularity at the separatrix), JET experiments show that by increasing the margin above the L-H threshold power and maintaining the edge temperature above the critical temperature for the transition to Type III ELMs, it is possible to avoid the degradation of the pedestal pressure with density, normally observed at lower power. As a result, the range of achievable densities (both in the core and in the pedestal) is increased. At high power above the L-H threshold power the core density was equal to the Greenwald limit with H97≅0.9. There is evidence that a mixed regime of Type I and Type II ELMs has been obtained at this intermediate triangularity, possibly as a result of this increase in density. At higher triangularity, δ≅0.5, the power required to achieve similar results is lower. (author)

  2. Adjacent habitat influence on stink bug (Hemiptera: Pentatomidae) densities and the associated damage at field corn and soybean edges.

    Science.gov (United States)

    Venugopal, P Dilip; Coffey, Peter L; Dively, Galen P; Lamp, William O

    2014-01-01

    The local dispersal of polyphagous, mobile insects within agricultural systems impacts pest management. In the mid-Atlantic region of the United States, stink bugs, especially the invasive Halyomorpha halys (Stål 1855), contribute to economic losses across a range of cropping systems. Here, we characterized the density of stink bugs along the field edges of field corn and soybean at different study sites. Specifically, we examined the influence of adjacent managed and natural habitats on the density of stink bugs in corn and soybean fields at different distances along transects from the field edge. We also quantified damage to corn grain, and to soybean pods and seeds, and measured yield in relation to the observed stink bug densities at different distances from field edge. Highest density of stink bugs was limited to the edge of both corn and soybean fields. Fields adjacent to wooded, crop and building habitats harbored higher densities of stink bugs than those adjacent to open habitats. Damage to corn kernels and to soybean pods and seeds increased with stink bug density in plots and was highest at the field edges. Stink bug density was also negatively associated with yield per plant in soybean. The spatial pattern of stink bugs in both corn and soybeans, with significant edge effects, suggests the use of pest management strategies for crop placement in the landscape, as well as spatially targeted pest suppression within fields.

  3. Adjacent habitat influence on stink bug (Hemiptera: Pentatomidae densities and the associated damage at field corn and soybean edges.

    Directory of Open Access Journals (Sweden)

    P Dilip Venugopal

    Full Text Available The local dispersal of polyphagous, mobile insects within agricultural systems impacts pest management. In the mid-Atlantic region of the United States, stink bugs, especially the invasive Halyomorpha halys (Stål 1855, contribute to economic losses across a range of cropping systems. Here, we characterized the density of stink bugs along the field edges of field corn and soybean at different study sites. Specifically, we examined the influence of adjacent managed and natural habitats on the density of stink bugs in corn and soybean fields at different distances along transects from the field edge. We also quantified damage to corn grain, and to soybean pods and seeds, and measured yield in relation to the observed stink bug densities at different distances from field edge. Highest density of stink bugs was limited to the edge of both corn and soybean fields. Fields adjacent to wooded, crop and building habitats harbored higher densities of stink bugs than those adjacent to open habitats. Damage to corn kernels and to soybean pods and seeds increased with stink bug density in plots and was highest at the field edges. Stink bug density was also negatively associated with yield per plant in soybean. The spatial pattern of stink bugs in both corn and soybeans, with significant edge effects, suggests the use of pest management strategies for crop placement in the landscape, as well as spatially targeted pest suppression within fields.

  4. Prospects for Edge Current Density Determination Using LIBEAM on DIII-D

    International Nuclear Information System (INIS)

    D.M. Thomas; A.S. Bozek; T.N. Carlstrom; D.K. Finkenthal; R. Jayakumar; M.A. Makowski; D.G. Nilson; T.H. Osborne; B.W. Rice; R.T. Snider

    2000-01-01

    The specific size and structure of the edge current profile has important effects on the MHD stability and ultimate performance of many advanced tokamak (AT) operating modes. This is true for both bootstrap and externally driven currents that may be used to tailor the edge shear. Absent a direct local measurement of j(r), the best alternative is a determination of the poloidal field. Measurements of the precision (0.1-0.01 o in magnetic pitch angle and 1-10 ms) necessary to address issues of stability and control and provide constraints for EFIT are difficult to do in the region of interest (ρ = 0.9-1.1). Using Zeeman polarization spectroscopy of the 2S-2P lithium resonance line emission from the DIII-D LIBEAM, measurements of the various field components may be made to the necessary precision in exactly the region of interest to these studies. Because of the negligible Stark mixing of the relevant atomic levels, this method of determining j(r) is insensitive to the large local electric fields typically found in enhanced confinement (H-mode) edges, and thus avoids an ambiguity common to Motional Stark Effect (MSE) measurements of B. Key issues for utilizing this technique include good beam quality, an optimum viewing geometry, and a suitable optical pre-filter to isolate the polarized emission line. A prospective diagnostic system for the DIII-D AT program will be described

  5. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    Science.gov (United States)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C., Jr.; the ASDEX Upgrade Team; the EUROfusion MST1 Team

    2018-04-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T e ) and its fluctuations (δT e ). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects, the scrape-off layer region is not accessible to the ECEI measurements in steady state conditions and that the signal is dominated by the shine-through emission. Transient effects, such as filaments, can change the radiation transport locally, but cannot be distinguished from the shine-through. Local density measurements are essential for the correct interpretation of the electron cyclotron emission, since the density fluctuations influence the temperature measurements at the plasma edge. As an example, a low frequency 8 kHz mode, which causes 10%-15% fluctuations in the signal level of the ECEI, is analysed. The same mode has been measured with the lithium beam emission spectroscopy density diagnostic, and is very well correlated in time with high frequency magnetic fluctuations. With radiation transport modelling of the electron cyclotron radiation in the ECEI geometry, it is shown that the density contributes significantly to the radiation temperature (T rad) and the experimental observations have shown the amplitude modulation in both density and temperature measurements. The poloidal velocity of the low frequency mode measured by the ECEI is 3 km s-1. The calculated velocity of the high frequency mode measured with the magnetic pick-up coils is about 25 km s-1. Velocities are compared with the E × B background flow velocity and possible explanations for the origin of the low frequency mode are discussed.

  6. Impact of rotating resonant magnetic perturbation fields on plasma edge electron density and temperature

    International Nuclear Information System (INIS)

    Stoschus, H.; Schmitz, O.; Frerichs, H.; Reiser, D.; Unterberg, B.; Lehnen, M.; Reiter, D.; Samm, U.; Jakubowski, M.W.

    2012-01-01

    Rotating resonant magnetic perturbation (RMP) fields impose a characteristic modulation to the edge electron density n e (r, t) and temperature T e (r, t) fields, which depends on the relative rotation f rel between external RMP field and plasma fluid. The n e (r, t) and T e (r, t) fields measured in the edge (r/a = 0.9–1.05) of TEXTOR L-mode plasmas are in close correlation with the local magnetic vacuum topology for low relative rotation f rel = −0.2 kHz. In comparison with the 3D neutral and plasma transport code EMC3-Eirene, this provides substantial experimental evidence that for low relative rotation level and high resonant field amplitudes (normalized radial field strength B r 4/1 /B t =2×10 -3 ), a stochastic edge with a remnant island chain dominated by diffusive transport exists. Radially outside a helical scrape-off layer, the so-called laminar zone embedded into a stochastic domain is found to exist. In contrast for high relative rotation of f rel = 1.8 kHz, the measured modulation of n e is shifted by π/2 toroidally with respect to the modelled vacuum topology. A pronounced flattening in T e (r) and a reduction in n e (r) is measured at the resonant flux surface and represents a clear signature for a magnetic island, which is phase shifted with respect to the vacuum island position. A correlated shift of the laminar zone radially outwards at the very plasma edge is observed suggesting that the actual near-field structure at the perturbation source is determined by the plasma response as well. (paper)

  7. Edge density X-mode reflectometry of RF-heated plasmas on ASDEX

    International Nuclear Information System (INIS)

    Schubert, R.

    1991-09-01

    In the present work microwave reflectometry is extended to the outermost part of tokamak plasmas (n e ≅ 10 11 to 1.5x10 13 cm -3 ), which is subject to strong electron density fluctuations. The perturbations of electron density profile measurements by these fluctuations, which lead to strong modulations in intensity and phase of the reflected signal is analysed in detail. By increasing the frequency of the interference fringes to values between 800 kHz and 2.4 MHz it is possible to make reliable profile measurements even in the region of very strong fluctuations. Measurements in the low density region are only possible with reasonable errors in the X-mode (Eperpendicular toB), as only the cut-off frequency of this mode, in contrast to that of the O-mode (EparallelB), takes a finite value (f ce ) for n e ->O. Taking advantage of this property, a method is presented to calibrate the measurements on the first reflection, which occurs directly in front of the microwave antennas (1-4 mm from the opening) thus giving a high precision even in the outermost part of the plasma close to the microwave antennas. For the calculation of the electron density profile a new and numerically stable algorithm has been developed. Measurements in connection with Lower Hybrid have been made with a set of 2 reflectometer antennas installed in ASDEX. (orig./AH)

  8. Lower hybrid current drive for edge current density modification in DIII-D: Final status report

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Porkolab, M.

    1993-01-01

    Application of Lower Hybrid (LH) Current Drive (CD) in the DIII-D tokamak has been studied at LLNL, off and on, for several years. The latest effort began in February 1992 in response to a letter from ASDEX indicating that the 2.45 GHz, 3 MW system there was available to be used on another device. An initial assessment of the possible uses for such a system on DIII-D was made and documented in September 1992. Multiple meetings with GA personnel and members of the LH community nationwide have occurred since that time. The work continued through the submission of the 1995 Field Work Proposals in March 1993 and was then put on hold due to budget limitations. The purpose of this document is to record the status of the work in such a way that it could fairly easily be restarted at a future date. This document will take the form of a collection of Appendices giving both background and the latest results from the FY 1993 work, connected by brief descriptive text. Section 2 will describe the final workshop on LHCD in DIII-D held at GA in February 1993. This was an open meeting with attendees from GA, LLNL, MIT and PPPL. Summary documents from the meeting and subsequent papers describing the results will be included in Appendices. Section 3 will describe the status of work on the use of low frequency (2.45 GHZ) LH power and Parametric Decay Instabilities (PDI) for the special case of high dielectric in the edge regions of the DIII-D plasma. This was one of the critical issues identified at the workshop. Other potential issues for LHCD in the DIII-D scenarios are: (1) damping of the waves on fast ions from neutral beam injection, (2) runaway electrons in the low density edge plasma, (3) the validity of the WKB approximation used in the ray-tracing models in the steep edge density gradients

  9. Edge reconstruction in armchair phosphorene nanoribbons revealed by discontinuous Galerkin density functional theory.

    Science.gov (United States)

    Hu, Wei; Lin, Lin; Yang, Chao

    2015-12-21

    With the help of our recently developed massively parallel DGDFT (Discontinuous Galerkin Density Functional Theory) methodology, we perform large-scale Kohn-Sham density functional theory calculations on phosphorene nanoribbons with armchair edges (ACPNRs) containing a few thousands to ten thousand atoms. The use of DGDFT allows us to systematically achieve a conventional plane wave basis set type of accuracy, but with a much smaller number (about 15) of adaptive local basis (ALB) functions per atom for this system. The relatively small number of degrees of freedom required to represent the Kohn-Sham Hamiltonian, together with the use of the pole expansion the selected inversion (PEXSI) technique that circumvents the need to diagonalize the Hamiltonian, results in a highly efficient and scalable computational scheme for analyzing the electronic structures of ACPNRs as well as their dynamics. The total wall clock time for calculating the electronic structures of large-scale ACPNRs containing 1080-10,800 atoms is only 10-25 s per self-consistent field (SCF) iteration, with accuracy fully comparable to that obtained from conventional planewave DFT calculations. For the ACPNR system, we observe that the DGDFT methodology can scale to 5000-50,000 processors. We use DGDFT based ab initio molecular dynamics (AIMD) calculations to study the thermodynamic stability of ACPNRs. Our calculations reveal that a 2 × 1 edge reconstruction appears in ACPNRs at room temperature.

  10. Transfer characteristics of optical profilers with respect to rectangular edge and step height measurement

    Science.gov (United States)

    Xie, Weichang; Hagemeier, Sebastian; Bischoff, Jörg; Mastylo, Rostyslav; Manske, Eberhard; Lehmann, Peter

    2017-06-01

    Optical profilers are mature instruments used in research and industry to study surface topography features. Although the corresponding standards are based on simple step height measurements, in practical applications these instruments are often used to study the fidelity of surface topography. In this context it is well-known that in certain situations a surface profile obtained by an optical profiler will differ from the real profile. With respect to practical applications such deviations often occur in the vicinity of steep walls and in cases of high aspect ratio. In this contribution we compare the transfer characteristics of different 3D optical profiler principles, namely white-light interferometry, focus sensing, and confocal microscopy. Experimental results demonstrate that the transfer characteristics do not only depend on the parameters of the optical measurement system (e. g. wavelength and coherence of light, numerical aperture, evaluated signal feature, polarization) but also on the properties of the measuring object such as step height, aspect ratio, material properties and homogeneity, rounding and steepness of the edges, surface roughness. As a result, typical artefacts such as batwings occur for certain parameter combinations, particularly at certain height-to-wavelength ratio (HWR) values. Understanding of the mechanisms behind these phenomena enables to reduce them by an appropriate parameter adaption. However, it is not only the edge artefacts, but also the position of an edge that may be changed due to the properties of the measuring object. In order to investigate the relevant effects theoretically, several models are introduced. These are based on either an extension of Richards-Wolf modeling or rigorous coupled wave analysis (RCWA). Although these models explain the experimental effects quite well they suffer from different limitations, so that a quantitative correspondence of theoretical modeling and experimental results is hard to achieve

  11. Behavior of the bottomside electron density profile over Pruhonice

    Czech Academy of Sciences Publication Activity Database

    Mosert, M.; Burešová, Dalia; Ezquer, R.; Mansilla, G.

    2004-01-01

    Roč. 34, č. 9 (2004), s. 1982-1989 ISSN 0273-1177 R&D Projects: GA AV ČR IAA3042102 Institutional research plan: CEZ:AV0Z3042911 Keywords : Electron density profiles * Variability Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.548, year: 2004

  12. Density fluctuation measurement at edge and internal transport barriers in JT-60U

    International Nuclear Information System (INIS)

    Oyama, N; Bruskin, L G; Takenaga, H; Shinohara, K; Isayama, A; Ide, S; Sakamoto, Y; Suzuki, T; Fujita, T; Kamada, Y; Miura, Y

    2004-01-01

    A new analytical method using a combination of the O-mode reflectometer and a time-dependent two-dimensional full-wave simulation code has been developed for the quantitative evaluation of density fluctuations in JT-60U. Two statistical parameters of the reflectometer signals, fluctuation index (F) and elongation factor (χ), are introduced as measures of the fluctuation amplitude (γ) and the width of the poloidal wave number spectrum (k θ0 ). This method is applied to the edge transport barrier (ETB) and internal transport barrier (ITB). At the transition to the ELM free H-mode phase, analysis suggests that the density fluctuation level reduced from 1.9-3.2% to 0.29-0.44%, while the value of k θ0 changed from 1.6-2.0 to 0.77-0.81 cm -1 in the ETB region. On the other hand, the amplitude of the density fluctuation was evaluated as 1.0-2.0% at the ITB region, even after the formation of the box type ITB. Instead, when a pellet was injected into the plasma with a box type ITB as an external perturbation, a remarkable change in the frequency spectrum was observed. Analysis suggests a reduction in the density fluctuation level to 0.4-0.6% after the pellet injection

  13. Current density profile inside q=1 on Tore Supra

    International Nuclear Information System (INIS)

    Joffrin, E.; Desgranges, C.; Sabot, R.; Dubois, M.A.

    1995-01-01

    The Tore Supra polarimeter used to measure the poloidal field distribution is described. The current density profiles are computed in two different ways using the interferometric and polarimetric data in conjunction with the magnetic data and the location of the inversion radius determined by the soft X-ray camera. The current density inside the q=1 surface is investigated for normal and monster sawteeth. Its variation are also measured by the polarimeter and compared with that predicted by the current diffusion equation assuming complete reconnection. Finally, the safety factor profile is compared with that obtained with the striation data of the pellet ablation. The results of the evolution of the q profile during sawteeth are in good agreement with those obtained in other devices. (author) 9 refs.; 4 figs

  14. Stationary density profiles in the Alcator C-mod tokamak

    International Nuclear Information System (INIS)

    Kesner, J.; Ernst, D.; Hughes, J.; Mumgaard, R.; Shiraiwa, S.; Whyte, D.; Scott, S.

    2012-01-01

    In the absence of an internal particle source, plasma turbulence will impose an intrinsic relationship between an inwards pinch and an outwards diffusion resulting in a stationary density profile. The Alcator C-mod tokamak utilizes RF heating and current drive so that fueling only occurs in the vicinity of the separatrix. Discharges that transition from L-mode to I-mode are seen to maintain a self-similar stationary density profile as measured by Thomson scattering. For discharges with negative magnetic shear, an observed rise of the safety factor in the vicinity of the magnetic axis appears to be accompanied by a decrease of electron density, qualitatively consistent with the theoretical expectations.

  15. Investigation of mechanisms for He-I emission radial profile broadening in a weakly ionized cylindrical helium plasma with recombining edge

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, E. M.; Brandt, C.; Hudson, B.; Nishijima, D.; Pigarov, A. Yu. [University of California–San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Kumar, D. [Johns Hopkins University, 3400 N Charles St., Baltimore, Maryland 21218 (United States)

    2013-09-15

    Spatially resolved spectroscopic measurements of He-I line emission are used to study the causes of emission profile broadening radially across the cylinder of a weakly ionized helium plasma. The plasma consists of an ionizing core (r < 2 cm) surrounded by a recombining edge (r > 2 cm) plasma. The brightness profiles of low-n EUV He-I resonance lines are shown to be strongly radially broadened due to opacity. The brightness profiles of high-n visible lines are also found to be strongly radially broadened, but dominantly due to edge recombination. Visible low-n lines are less strongly radially broadened, apparently by a combination of both recombination and EUV opacity. The low-n visible He-I line ratio method with central opacity correction is found to calculate central electron density and temperature well, with poor agreement at the edge, as expected for recombining plasma. In the recombining edge, high-n Boltzmann analysis is found to accurately measure the cold (T{sub e} < 0.2 eV) edge temperature. Near the core, however, high-n Boltzmann analysis can be complicated by electron-impact excitation, giving incorrect (T{sub e}≈ 0.1 eV) apparent temperatures. Probe measurements were not able to capture the cold edge temperature accurately, probably due to large potential fluctuations, even when using fast triple probe measurements. Fast spectroscopic measurements show that this discrepancy is not explained by recombining plasma alternating with ionizing plasma in the edge region.

  16. EMC3-Eirene simulations of gas puff effects on edge density and ICRF coupling in ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Noterdaeme, Jean-Marie [Max Planck Institute for Plasma Physics, Garching (Germany); University of Ghent, Ghent (Belgium); Coster, David; Lunt, Tilmann; Bobkov, Volodymyr; Feng, Yuehe [Max Planck Institute for Plasma Physics, Garching (Germany); Collaboration: ASDEX Upgrade team

    2015-05-01

    Ion cyclotron range of frequency (ICRF) heating relies on the Fast Wave (FW) to transport the power from the edge (the antenna) to the plasma center. Since the FW is evanescent below a critical density (typically in the 10{sup 18} m{sup -3} range), the wave does not propagate in the region where the density is below this value in the very edge of the plasma. The coupling depends strongly on the width of this region. The distance between the ICRF antenna and the FW cut-off layer can be made smaller by increasing the edge density in front of the ICRF antenna. Previous experiments in many tokamaks and preliminary simulation results for AUG and JET with EDGE2D-EIRENE show that the edge density could indeed be increased with gas puffing at the top of the vessel or in the midplane. But the 2D code cannot quantitatively reproduce the experimental results, mainly due to the assumptions of toroidal axisymmetry. EMC3-EIRENE is a 3D Edge Monte Carlo plasma fluid transport code. By including the toroidal nonaxisymmetric plasma facing components and 3D positions of gas valves in the code, the simulations can be made more realistic. We will show first simulation results of the code and a comparison to experiments.

  17. Density profiles of supernova matter and determination of neutrino parameters

    Science.gov (United States)

    Chiu, Shao-Hsuan

    2007-08-01

    The flavor conversion of supernova neutrinos can lead to observable signatures related to the unknown neutrino parameters. As one of the determinants in dictating the efficiency of resonant flavor conversion, the local density profile near the Mikheyev-Smirnov-Wolfenstein (MSW) resonance in a supernova environment is, however, not so well understood. In this analysis, variable power-law functions are adopted to represent the independent local density profiles near the locations of resonance. It is shown that the uncertain matter density profile in a supernova, the possible neutrino mass hierarchies, and the undetermined 1-3 mixing angle would result in six distinct scenarios in terms of the survival probabilities of νe and ν¯e. The feasibility of probing the undetermined neutrino mass hierarchy and the 1-3 mixing angle with the supernova neutrinos is then examined using several proposed experimental observables. Given the incomplete knowledge of the supernova matter profile, the analysis is further expanded to incorporate the Earth matter effect. The possible impact due to the choice of models, which differ in the average energy and in the luminosity of neutrinos, is also addressed in the analysis.

  18. Vacuum heating evaluation for plasmas of exponentially decreasing density profile

    International Nuclear Information System (INIS)

    Pestehe, S.J.; Mohammadnejad, M.

    2008-01-01

    Ultra-short pulse lasers have opened a regime of laser-plasma interaction where plasmas have scale lengths shorter than the laser wavelength and allow the possibility of generating near-solid density plasmas. The interaction of high-intensity laser beams with sharply bounded high-density and small scale length plasmas is considered. Absorption of the laser energy associated with the mechanism of dragging electrons out of the plasma into the vacuum and sending them back into the plasma with the electric field component along the density gradient, so called vacuum heating, is studied. An exponentially decreasing electron density profile is assumed. The vector potential of the electromagnetic field propagating through the plasma is calculated and the behaviour of the electric and magnetic components of the electromagnetic field is studied. The fraction of laser power absorbed in this process is calculated and plotted versus the laser beam incidence angle, illumination energy, and the plasma scale length

  19. Finding evidence for density fluctuation effects on electron cyclotron heating deposition profiles on DIII-D

    International Nuclear Information System (INIS)

    Brookman, M. W.; Austin, M. E.; Petty, C. C.

    2015-01-01

    Theoretical work, computation, and results from TCV [J. Decker “Effect of density fluctuations on ECCD in ITER and TCV,” EPJ Web of Conf. 32, 01016 (2012)] suggest that density fluctuations in the edge region of a tokamak plasma can cause broadening of the ECH deposition profile. In this paper, a GUI tool is presented which is used for analysis of ECH deposition as a first step towards looking for this broadening, which could explain effects seen in previous DIII-D ECH transport studies [K.W. Gentle “Electron energy transport inferences from modulated electron cyclotron heating in DIII-D,” Phys. Plasmas 13, 012311 (2006)]. By applying an FFT to the T e measurements from the University of Texas’s 40-channel ECE Radiometer, and using a simplified thermal transport equation, the flux surface extent of ECH deposition is determined. The Fourier method analysis is compared with a Break-In-Slope (BIS) analysis and predictions from the ray-tracing code TORAY. Examination of multiple Fourier harmonics and BIS fitting methods allow an estimation of modulated transport coefficients and thereby the true ECH deposition profile. Correlations between edge fluctuations and ECH deposition in legacy data are also explored as a step towards establishing a link between fluctuations and deposition broadening in DIII-D

  20. Finding evidence for density fluctuation effects on electron cyclotron heating deposition profiles on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Brookman, M. W., E-mail: brookmanmw@fusion.gat.com; Austin, M. E. [Institute for Fusion Studies, University of Texas at Austin, MS 13-505, 3483 Dunhill St, San Diego, CA 92121-1200 (United States); Petty, C. C. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States)

    2015-12-10

    Theoretical work, computation, and results from TCV [J. Decker “Effect of density fluctuations on ECCD in ITER and TCV,” EPJ Web of Conf. 32, 01016 (2012)] suggest that density fluctuations in the edge region of a tokamak plasma can cause broadening of the ECH deposition profile. In this paper, a GUI tool is presented which is used for analysis of ECH deposition as a first step towards looking for this broadening, which could explain effects seen in previous DIII-D ECH transport studies [K.W. Gentle “Electron energy transport inferences from modulated electron cyclotron heating in DIII-D,” Phys. Plasmas 13, 012311 (2006)]. By applying an FFT to the T{sub e} measurements from the University of Texas’s 40-channel ECE Radiometer, and using a simplified thermal transport equation, the flux surface extent of ECH deposition is determined. The Fourier method analysis is compared with a Break-In-Slope (BIS) analysis and predictions from the ray-tracing code TORAY. Examination of multiple Fourier harmonics and BIS fitting methods allow an estimation of modulated transport coefficients and thereby the true ECH deposition profile. Correlations between edge fluctuations and ECH deposition in legacy data are also explored as a step towards establishing a link between fluctuations and deposition broadening in DIII-D.

  1. THE DARK MATTER DENSITY PROFILE OF THE FORNAX DWARF

    International Nuclear Information System (INIS)

    Jardel, John R.; Gebhardt, Karl

    2012-01-01

    We construct axisymmetric Schwarzschild models to measure the mass profile of the Local Group dwarf galaxy Fornax. These models require no assumptions to be made about the orbital anisotropy of the stars, as is the case for commonly used Jeans models. We test a variety of parameterizations of dark matter density profiles and find cored models with uniform density ρ c = (1.6 ± 0.1) × 10 –2 M ☉ pc –3 fit significantly better than the cuspy halos predicted by cold dark matter simulations. We also construct models with an intermediate-mass black hole, but are unable to make a detection. We place a 1σ upper limit on the mass of a potential intermediate-mass black hole at M . ≤ 3.2 × 10 4 M ☉ .

  2. Diagnostic development for current density profile control at KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Ko, J., E-mail: jinseok@nfri.re.kr [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); University of Science and Technology, Daejeon 34113 (Korea, Republic of); Chung, J. [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Messmer, M.C.C. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven (Netherlands)

    2016-11-01

    Highlights: • The motional Stark effect (MSE) diagnostic installed at KSTAR. • Engineering challenges and solutions on the design and fabrication of the front optics housing and filter modules. • Characterization of the bandpass filters and the responses to polarized light. - Abstract: The current density profile diagnostics are critical for the control of the steady-state burning plasma operations. A multi-channel motional Stark effect (MSE) diagnostic system has been implemented for the measurements of the internal magnetic field structures that constrain the magnetic equilibrium reconstruction to accurately produce the tokamak safety factor and current density profiles for the Korea Superconducting Tokamak Advanced Research (KSTAR). This work presents the design and fabrication of the front optics and the filter modules and the calibration activities for the MSE diagnostic at KSTAR.

  3. Ion transition heights from topside electron density profiles

    International Nuclear Information System (INIS)

    Titheridge, J.E.

    1976-01-01

    Theoretical electron density profiles are calculated for the topside ionosphere to determine the major factors controlling the profile shape. Only the mean temperature, the vertical temperature gradient and the O + /H + ion transition height are important. Vertical proton fluxes alter the ion transition height but have no other effect on the profile shape. Diffusive equilibrium profiles including only these three effects fit observed profiles, at all latitudes, to within experimental accuracy. Values of plasma temperature, temperature gradient and ion transition height hsub(T) were determined by fitting theoretical models to 60,000 experimental profiles obtained from Alouette 1 ionograms, at latitudes of 75 0 S to 85 0 N near solar minimum. Inside the plasmasphere hsub(T) varies from about 500 km on winter nights to 850 km on summer days. Diurnal variations are caused primarily by the production and loss of O + in the ionosphere. The approximately constant winter night value of hsub(T) is close to the level for chemical equilibrium. In summer hsub(T) is always above the equilibrium level, giving a continual production of protons which travel along lines of force to aid in maintaining the conjugate winter night ionosphere. Outside the plasmasphere hsub(T) is 300 to 600 km above the equilibrium level at all times. This implies a continual near-limiting upwards flux of protons which persists down to latitudes of about 60 0 at night and 50 0 during the day. (author)

  4. Atmospheric turbulence profiling with unknown power spectral density

    Science.gov (United States)

    Helin, Tapio; Kindermann, Stefan; Lehtonen, Jonatan; Ramlau, Ronny

    2018-04-01

    Adaptive optics (AO) is a technology in modern ground-based optical telescopes to compensate for the wavefront distortions caused by atmospheric turbulence. One method that allows to retrieve information about the atmosphere from telescope data is so-called SLODAR, where the atmospheric turbulence profile is estimated based on correlation data of Shack-Hartmann wavefront measurements. This approach relies on a layered Kolmogorov turbulence model. In this article, we propose a novel extension of the SLODAR concept by including a general non-Kolmogorov turbulence layer close to the ground with an unknown power spectral density. We prove that the joint estimation problem of the turbulence profile above ground simultaneously with the unknown power spectral density at the ground is ill-posed and propose three numerical reconstruction methods. We demonstrate by numerical simulations that our methods lead to substantial improvements in the turbulence profile reconstruction compared to the standard SLODAR-type approach. Also, our methods can accurately locate local perturbations in non-Kolmogorov power spectral densities.

  5. LPWA using supersonic gas jet with tailored density profile

    Science.gov (United States)

    Kononenko, O.; Bohlen, S.; Dale, J.; D'Arcy, R.; Dinter, M.; Erbe, J. H.; Indorf, G.; di Lucchio, L.; Goldberg, L.; Gruse, J. N.; Karstensen, S.; Libov, V.; Ludwig, K.; Martinez de La Ossa, A.; Marutzky, F.; Niroula, A.; Osterhoff, J.; Quast, M.; Schaper, L.; Schwinkendorf, J.-P.; Streeter, M.; Tauscher, G.; Weichert, S.; Palmer, C.; Horbatiuk, Taras

    2016-10-01

    Laser driven plasma wakefield accelerators have been explored as a potential compact, reproducible source of relativistic electron bunches, utilising an electric field of many GV/m. Control over injection of electrons into the wakefield is of crucial importance in producing stable, mono-energetic electron bunches. Density tailoring of the target, to control the acceleration process, can also be used to improve the quality of the bunch. By using gas jets to provide tailored targets it is possible to provide good access for plasma diagnostics while also producing sharp density gradients for density down-ramp injection. OpenFOAM hydrodynamic simulations were used to investigate the possibility of producing tailored density targets in a supersonic gas jet. Particle-in-cell simulations of the resulting density profiles modelled the effect of the tailored density on the properties of the accelerated electron bunch. Here, we present the simulation results together with preliminary experimental measurements of electron and x-ray properties from LPWA experiments using gas jet targets and a 25 TW, 25 fs Ti:Sa laser system at DESY.

  6. Plasma density profiles and finite bandwidth effects on electron heating

    International Nuclear Information System (INIS)

    Spielman, R.B.; Mizuno, K.; DeGroot, J.S.; Bollen, W.M.; Woo, W.

    1980-01-01

    Intense, p-polarized microwaves are incident on an inhomogeneous plasma in a cylindrical waveguide. Microwaves are mainly absorbed by resonant absorption near the critical surface (where the plasma frequency, ω/sub pe/, equals the microwave frequency, ω/sub o/). The localized plasma waves strongly modify the plasma density. Step-plateau density profiles or a cavity are created depending on the plasma flow speed. Hot electron production is strongly affected by the microwave bandwidth. The hot electron temperature varies as T/sub H/ is proportional to (Δ ω/ω) -0 25 . As the hot electron temperature decreases with increasing driver bandwidth, the hot electron density increases. This increase is such that the heat flux into the overdense region (Q is proportional to eta/sub H/T/sub H/ 3 2 ) is nearly constant

  7. Estimation of Neutral Density in Edge Plasma with Double Null Configuration in EAST

    International Nuclear Information System (INIS)

    Zhang Ling; Xu Guosheng; Ding Siye; Gao Wei; Wu Zhenwei; Chen Yingjie; Huang Juan; Liu Xiaoju; Zang Qing; Chang Jiafeng; Zhang Wei; Li Yingying; Qian Jinping

    2011-01-01

    In this work, population coefficients of hydrogen's n = 3 excited state from the hydrogen collisional-radiative (CR) model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients (PECs) of hydrogen Balmer-α (n = 3 → n = 2) (H α ). The results are compared with the PECs from Atomic Data and Analysis Structure (ADAS) database, and a good agreement is found. A magnetic surface-averaged neutral density profile of typical double-null (DN) plasma in EAST is obtained by using FRANTIC, the 1.5-D fluid transport code. It is found that the sum of integral D α and H α emission intensity calculated via the neutral density agrees with the measured results obtained by using the absolutely calibrated multi-channel poloidal photodiode array systems viewing the lower divertor at the last closed flux surface (LCFS). It is revealed that the typical magnetic surface-averaged neutral density at LCFS is about 3.5 x 10 16 m -3 . (magnetically confined plasma)

  8. Automated Processing of ISIS Topside Ionograms into Electron Density Profiles

    Science.gov (United States)

    Reinisch, bodo W.; Huang, Xueqin; Bilitza, Dieter; Hills, H. Kent

    2004-01-01

    Modeling of the topside ionosphere has for the most part relied on just a few years of data from topside sounder satellites. The widely used Bent et al. (1972) model, for example, is based on only 50,000 Alouette 1 profiles. The International Reference Ionosphere (IRI) (Bilitza, 1990, 2001) uses an analytical description of the graphs and tables provided by Bent et al. (1972). The Alouette 1, 2 and ISIS 1, 2 topside sounder satellites of the sixties and seventies were ahead of their times in terms of the sheer volume of data obtained and in terms of the computer and software requirements for data analysis. As a result, only a small percentage of the collected topside ionograms was converted into electron density profiles. Recently, a NASA-funded data restoration project has undertaken and is continuing the process of digitizing the Alouette/ISIS ionograms from the analog 7-track tapes. Our project involves the automated processing of these digital ionograms into electron density profiles. The project accomplished a set of important goals that will have a major impact on understanding and modeling of the topside ionosphere: (1) The TOPside Ionogram Scaling and True height inversion (TOPIST) software was developed for the automated scaling and inversion of topside ionograms. (2) The TOPIST software was applied to the over 300,000 ISIS-2 topside ionograms that had been digitized in the fkamework of a separate AISRP project (PI: R.F. Benson). (3) The new TOPIST-produced database of global electron density profiles for the topside ionosphere were made publicly available through NASA s National Space Science Data Center (NSSDC) ftp archive at . (4) Earlier Alouette 1,2 and ISIS 1, 2 data sets of electron density profiles from manual scaling of selected sets of ionograms were converted fiom a highly-compressed binary format into a user-friendly ASCII format and made publicly available through nssdcftp.gsfc.nasa.gov. The new database for the topside ionosphere established

  9. Element-specific density profiles in interacting biomembrane models

    International Nuclear Information System (INIS)

    Schneck, Emanuel; Rodriguez-Loureiro, Ignacio; Bertinetti, Luca; Gochev, Georgi; Marin, Egor; Novikov, Dmitri; Konovalov, Oleg

    2017-01-01

    Surface interactions involving biomembranes, such as cell–cell interactions or membrane contacts inside cells play important roles in numerous biological processes. Structural insight into the interacting surfaces is a prerequisite to understand the interaction characteristics as well as the underlying physical mechanisms. Here, we work with simplified planar experimental models of membrane surfaces, composed of lipids and lipopolymers. Their interaction is quantified in terms of pressure–distance curves using ellipsometry at controlled dehydrating (interaction) pressures. For selected pressures, their internal structure is investigated by standing-wave x-ray fluorescence (SWXF). This technique yields specific density profiles of the chemical elements P and S belonging to lipid headgroups and polymer chains, as well as counter-ion profiles for charged surfaces. (paper)

  10. Flare plasma density determination using observed temperature profiles

    International Nuclear Information System (INIS)

    Garcia, H.A.

    1986-01-01

    Observed electron temperature variations derived from flux intensity ratios of whole-disk continuum soft X-ray spectra recorded by GOES satellites are presently subjected to an analysis that is based on the nonequilibrium energy balance equation in order to obtain the physical properties of a large solar flare from onset through the gradual phase. A self-similar formalism which reduces the nonlinear, second-order PDE in length and time to a more tractable, nonlinear, first-order Ricatti equation is invoked. Plasma density is the principal unknown variable contained in the Ricatti equation, which also contains first-order time derivatives and first- and second-order spatial derivatives of temperature. This methodology is presently applied to the moderate size flare of January 28, 1982, for which a density profile is deduced under various parametric conditions. 37 references

  11. High Confinement and High Density with Stationary Plasma Energy and Strong Edge Radiation Cooling in Textor-94

    Science.gov (United States)

    Messiaen, A. M.

    1996-11-01

    A new discharge regime has been observed on the pumped limiter tokamak TEXTOR-94 in the presence of strong radiation cooling and for different scenarii of additional hearing. The radiated power fraction (up to 90%) is feedback controlled by the amount of Ne seeded in the edge. This regime meets many of the necessary conditions for a future fusion reactor. Energy confinement increases with increasing densities (reminiscent of the Z-mode obtained at ISX-B) and as good as ELM-free H-mode confinement (enhancement factor verus ITERH93-P up to 1.2) is obtained at high densities (up to 1.2 times the Greenwald limit) with peaked density profiles showing a peaking factor of about 2 and central density values around 10^14cm-3. In experiments where the energy content of the discharges is kept constant with an energy feedback loop acting on the amount of ICRH power, stable and stationary discharges are obtained for intervals of more than 5s, i.e. 100 times the energy confinement time or about equal to the skin resistive time, even with the cylindrical q_α as low as 2.8 β-values up to the β-limits of TEXTOR-94 are achieved (i.e. β n ≈ 2 of and β p ≈ 1.5) and the figure of merit for ignition margin f_Hqa in these discharges can be as high as 0.7. No detrimental effects of the seeded impurity on the reactivity of the plasma are observed. He removal in these discharges has also been investigated. [1] Laboratoire de Physique des Plasmas-Laboratorium voor Plasmafysica, Association "EURATOM-Belgian State", Ecole Royale Militaire-Koninklijke Militaire School, Brussels, Belgium [2] Institut für Plasmaphysik, Forschungszentrum Jülich, GmbH, Association "EURATOM-KFA", Jülich, Germany [3] Fusion Energy Research Program, Mechanical Engineering Division, University of California at San Diego, La Jolla, USA [4] FOM Institüt voor Plasmafysica Rijnhuizen, Associatie "FOM-EURATOM", Nieuwegein, The Netherlands [*] Researcher at NFSR, Belgium itemize

  12. On the density of nearly regular graphs with a good edge-labelling

    OpenAIRE

    Mehrabian, Abbas

    2011-01-01

    A good edge-labelling of a simple graph is a labelling of its edges with real numbers such that, for any ordered pair of vertices (u,v), there is at most one nondecreasing path from u to v. Say a graph is good if it admits a good edge-labelling, and is bad otherwise. Our main result is that any good n-vertex graph whose maximum degree is within a constant factor of its average degree (in particular, any good regular graph) has at most n^{1+o(1)} edges. As a corollary, we show that there are b...

  13. Interpretation of the U L3-edge EXAFS in uranium dioxide using molecular dynamics and density functional theory simulations

    International Nuclear Information System (INIS)

    Bocharov, Dmitry; Chollet, Melanie; Krack, Matthias; Bertsch, Johannes; Grolimund, Daniel; Martin, Matthias; Kuzmin, Alexei; Purans, Juris; Kotomin, Eugene

    2016-01-01

    X-ray absorption spectroscopy is employed to study the local structure of pure and Cr-doped UO 2 at 300 K. The U L 3 -edge EXAFS spectrum is interpreted within the multiplescattering (MS) theory using the results of the classical and ab initio molecular dynamics simulations, allowing us to validate the accuracy of theoretical models. The Cr K-edge XANES is simulated within the full-multiple-scattering formalism considering a substitutional model (Cr at U site). It is shown that both unrelaxed and relaxed structures, produced by ab initio density functional theory (DFT) calculations, fail to describe the experiment. (paper)

  14. 1 μs broadband frequency sweeping reflectometry for plasma density and fluctuation profile measurements

    Science.gov (United States)

    Clairet, F.; Bottereau, C.; Medvedeva, A.; Molina, D.; Conway, G. D.; Silva, A.; Stroth, U.; ASDEX Upgrade Team; Tore Supra Team; Eurofusion Mst1 Team

    2017-11-01

    Frequency swept reflectometry has reached the symbolic value of 1 μs sweeping time; this performance has been made possible, thanks to an improved control of the ramp voltage driving the frequency source. In parallel, the memory depth of the acquisition system has been upgraded and can provide up to 200 000 signals during a plasma discharge. Additional improvements regarding the trigger delay determination of the acquisition and the voltage ramp linearity required by this ultra-fast technique have been set. While this diagnostic is traditionally dedicated to the plasma electron density profile measurement, such a fast sweeping rate can provide the study of fast plasma events and turbulence with unprecedented time and radial resolution from the edge to the core. Experimental results obtained on ASDEX Upgrade plasmas are presented to demonstrate the performances of the diagnostic.

  15. An edge density fluctuation diagnostic for DIII-D using lithium beams

    International Nuclear Information System (INIS)

    Thomas, D.M.

    1991-12-01

    This report covers the research conducted under DOE grant FG03- 90ER54081 during the period August 15, 1990 through November 15, 1991. Progress during the period March 15, 1990 through August 15, 1990 was covered in a previous report. Highlights during this period include the development of a compact neutral lithium accelerator capable of producing several mA at up to 30 kV, measurements of intrinsic beam fluctuation levels, and the design and partial completion of the diagnostic installation on the D3-D tokamak. We also had one journal article describing the system published in Reviews of Scientific Instruments, presented a poster on our recent progress at the APS Plasma Physics conference, and submitted an abstract to the 9th Topical Conference on Plasma Diagnostics. The overall objective of this project is to provide detailed information about the behavior of the electron density in the edge region of D3-D, and in particular to examine the local character of the associated degradation in confinement properties. Measurements should provide important data for testing theories of the L-H transition in tokamaks and should help in assessing the role of various instabilities in anomalous transport. The work on this project may be naturally organized according to the following six subareas: Ion source/beam system, neutralizer system, optical system, data acquisition, data analysis, and machine (D3-D) interface. Progress in each of these areas will be discussed briefly. We also briefly discuss our plans for future work on this program

  16. First density profile measurements using frequency modulation of the continuous wave reflectometry on JETa)

    Science.gov (United States)

    Meneses, L.; Cupido, L.; Sirinelli, A.; Manso, M. E.; Jet-Efds Contributors

    2008-10-01

    We present the main design options and implementation of an X-mode reflectometer developed and successfully installed at JET using an innovative approach. It aims to prove the viability of measuring density profiles with high spatial and temporal resolution using broadband reflectometry operating in long and complex transmission lines. It probes the plasma with magnetic fields between 2.4 and 3.0 T using the V band [~(0-1.4)×1019 m-3]. The first experimental results show the high sensitivity of the diagnostic when measuring changes in the plasma density profile occurring ITER relevant regimes, such as ELMy H-modes. The successful demonstration of this concept motivated the upgrade of the JET frequency modulation of the continuous wave (FMCW) reflectometry diagnostic, to probe both the edge and core. This new system is essential to prove the viability of using the FMCW reflectometry technique to probe the plasma in next step devices, such as ITER, since they share the same waveguide complexity.

  17. Control-oriented modeling of the plasma particle density in tokamaks and application to real-time density profile reconstruction

    NARCIS (Netherlands)

    Blanken, T.C.; Felici, F.; Rapson, C.J.; de Baar, M.R.; Heemels, W.P.M.H.

    2018-01-01

    A model-based approach to real-time reconstruction of the particle density profile in tokamak plasmas is presented, based on a dynamic state estimator. Traditionally, the density profile is reconstructed in real-time by solving an ill-conditioned inversion problem using a measurement at a single

  18. Real-time feedback control of the plasma density profile on ASDEX Upgrade

    International Nuclear Information System (INIS)

    Mlynek, A.; Reich, M.; Giannone, L.; Treutterer, W.; Behler, K.; Blank, H.; Buhler, A.; Cole, R.; Eixenberger, H.; Fischer, R.; Lohs, A.; Lueddecke, K.; Merkel, R.; Neu, G.; Ryter, F.; Zasche, D.

    2011-01-01

    The spatial distribution of density in a fusion experiment is of significant importance as it enters in numerous analyses and contributes to the fusion performance. The reconstruction of the density profile is therefore commonly done in offline data analysis. In this paper, we present an algorithm which allows for density profile reconstruction from the data of the submillimetre interferometer and the magnetic equilibrium in real-time. We compare the obtained results to the profiles yielded by a numerically more complex offline algorithm. Furthermore, we present recent ASDEX Upgrade experiments in which we used the real-time density profile for active feedback control of the shape of the density profile.

  19. The emergence densities of annual cicadas (Hemiptera: Cicadidae) increase with sapling density and are greater near edges in a bottomland hardwood forest.

    Science.gov (United States)

    Chiavacci, Scott J; Bednarz, James C; McKay, Tanja

    2014-08-01

    The emergence densities of cicadas tend to be patchy at multiple spatial scales. While studies have identified habitat conditions related to these patchy distributions, their interpretation has been based primarily on periodical cicada species; habitat factors associated with densities of nonperiodical (i.e., annual) cicadas have remained under studied. This is despite their widespread distribution, diversity, and role as an important trophic resource for many other organisms, particularly within riparian areas. We studied habitat factors associated with the emergence densities of Tibicen spp. in a bottomland hardwood forest in east-central Arkansas. We found emergence densities were greatest in areas of high sapling densities and increased toward forest edges, although sapling density was a much stronger predictor of emergence density. Emergence densities also differed among sample areas within our study system. The habitat features predicting nymph densities were likely driven by a combination of factors affecting female selection of oviposition sites and the effects of habitat conditions on nymph survival. The differences in nymph densities between areas of our system were likely a result of the differential effects of flooding in these areas. Interestingly, our findings were similar to observations of periodical species, suggesting that both types of cicadas select similar habitat characteristics for ovipositing or are under comparable selective pressures during development. Our findings also imply that changes in habitat characteristics because of anthropogenically altered disturbance regimes (e.g., flooding) have the potential to negatively impact both periodical and annual species, which could have dramatic consequences for organisms at numerous trophic levels.

  20. Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

    International Nuclear Information System (INIS)

    Priegnitz, M; Helmbrecht, S; Fiedler, F; Janssens, G; Smeets, J; Vander Stappen, F; Perali, I; Sterpin, E

    2015-01-01

    Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation. (paper)

  1. Density profile of nitrogen in cylindrical pores of MCM-41

    Science.gov (United States)

    Soper, Alan K.; Bowron, Daniel T.

    2017-09-01

    A straightforward approach using radiation scattering (X-ray or neutron) combined with atomistic modelling is used to accurately assess the pore dimensions in the porous silica, MCM-41. The method is used to calculate the density profile of nitrogen absorbed in this material at a variety of fractional pressures, p/p0, where p0 is the saturated vapour pressure, up to p/p0 = 0.36 at T = 87 K in the present instance. At this pressure two distinct layers of liquid nitrogen occur on the silica surface, with a relatively sharp gas-liquid interface. It is suggested surface tension effects at this interface strongly influence the growth of further layers.

  2. Nekton density patterns and hurricane recovery in submerged aquatic vegetation, and along non-vegetated natural and created edge habitats

    Science.gov (United States)

    La Peyre, M.K.; Gordon, J.

    2012-01-01

    We compared nekton habitat value of submerged aquatic vegetation, flooded non-vegetated natural and man-made edge habitats in mesohaline interior marsh areas in southwest Louisiana using a 1-m 2 throw trap and 3-mm bag seine. When present, SAV habitats supported close to 4 times greater densities and higher species richness of nekton as compared to either natural or man-made edge habitats, which supported similar densities to one another. Three species of concern (bayou killifish, diamond killifish, chain pipefish) were targeted in the analysis, and two of the three were collected almost entirely in SAV habitat. During the course of the study, Hurricanes Ike and Gustav passed directly over the study sites in September 2008. Subsequent analyses indicated significant reductions in resident nekton density 1-mo post hurricanes, and only limited recovery 13-mo post-hurricane. Possible alteration of environmental characteristics such as scouring of SAV habitat, deposition of sediment over SAV, edge erosion and marsh loss, and extended high salinities may explain these lasting impacts. ?? 2011.

  3. Surface density profile and surface tension of the one-component classical plasma

    International Nuclear Information System (INIS)

    Ballone, P.; Senatore, G.; Trieste Univ.; Tosi, M.P.; Oxford Univ.

    1982-08-01

    The density profile and the interfacial tension of two classical plasmas in equilibrium at different densities are evaluated in the square-density-gradient approximation. For equilibrium in the absence of applied external voltage, the profile is oscillatory in the higher-density plasma and the interfacial tension is positive. The amplitude and phase of these oscillations and the magnitude of the interfacial tension are related to the width of the background profile. Approximate representations of the equilibrium profile by matching of its asymptotic forms are analyzed. A comparison with computer simulation data and a critical discussion of a local-density theory are also presented. (author)

  4. Effects of density gradients and fluctuations at the plasma edge on ECEI measurements at ASDEX Upgrade

    NARCIS (Netherlands)

    Vanovac, B.; Wolfrum, E.; Denk, S. S.; Mink, F.; Laggner, F. M.; Birkenmeier, G.; Willensdorfer, M.; Viezzer, E.; Hoelzl, M.; Freethy, S. J.; Dunne, M. G.; Lessig, A.; Luhmann, N. C.; ASDEX Upgrade team,; EUROfusion MST1 Team,

    2018-01-01

    Electron cyclotron emission imaging (ECEI) provides measurements of electron temperature (T-e) and its fluctuations (delta T-e). However, when measuring at the plasma edge, in the steep gradient region, radiation transport effects must be taken into account. It is shown that due to these effects,

  5. A temporally and spatially resolved electron density diagnostic method for the edge plasma based on Stark broadening

    Energy Technology Data Exchange (ETDEWEB)

    Zafar, A., E-mail: zafara@ornl.gov [Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Martin, E. H.; Isler, R. C.; Caughman, J. B. O. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Shannon, S. C. [Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2016-11-15

    An electron density diagnostic (≥10{sup 10} cm{sup −3}) capable of high temporal (ms) and spatial (mm) resolution is currently under development at Oak Ridge National Laboratory. The diagnostic is based on measuring the Stark broadened, Doppler-free spectral line profile of the n = 6–2 hydrogen Balmer series transition. The profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The quasi-static approach used to calculate the Doppler-free spectral line profile is outlined here and the results from the model are presented for H-δ spectra for electron densities of 10{sup 10}–10{sup 13} cm{sup −3}. The profile shows complex behavior due to the interaction between the magnetic substates of the atom.

  6. Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

    Science.gov (United States)

    Réfy, D. I.; Brix, M.; Gomes, R.; Tál, B.; Zoletnik, S.; Dunai, D.; Kocsis, G.; Kálvin, S.; Szabolics, T.; JET Contributors

    2018-04-01

    Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ˜10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge. The APD system is capable of measuring light intensities on the microsecond time scale. However ˜100 μs integration is needed to have an acceptable signal to noise ratio due to moderate light levels. Fast modulation of the beam up to 30 kHz is implemented which allows background subtraction on the 100 μs time scale. The measurement covers the 0.9 background subtraction, the relative calibration, and the comprehensive error calculation, runs a Bayesian density reconstruction code, and loads results to the JET database. The paper demonstrates the capability of the APD system by analyzing fast phenomena like pellet injection and edge localized modes.

  7. 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)

  8. CO2 laser diagnostics for measurements of the plasma density profile and plasma density fluctuations on LHD

    International Nuclear Information System (INIS)

    Vyacheslavov, L.N.; Tanaka, K.; Kawahata, K.

    2001-04-01

    A CO 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)

  9. Evolution of Edge Pedestal Profiles Over the L-H Transition

    Science.gov (United States)

    Sayer, M. S.; Stacey, W. M.; Floyd, J. P.; Groebner, R. J.

    2012-10-01

    The detailed time evolution of thermal diffusivities, electromagnetic forces, pressure gradients, particle pinch and momentum transport frequencies (which determine the diffusion coefficient) have been analyzed during the L-H transition in a DIII-D discharge. Density, temperature, rotation velocity and electric field profiles at times just before and after the L-H transition are analyzed in terms of these quantities. The analysis is based on the fluid particle balance, energy balance, force balance and heat conduction equations, as in Ref. [1], but with much greater time resolution and with account for thermal ion orbit loss. The variation of diffusive and non-diffusive transport over the L-H transition is determined from the variation in the radial force balance (radial electric field, VxB force, and pressure gradient) and the variation in the interpreted diffusive transport coefficients. 6pt [1] W.M. Stacey and R.J. Groebner, Phys. Plasmas 17, 112512 (2010).

  10. Do prey densities determine preferences of mammalian predators for habitat edges in an agricultural landscape?

    Czech Academy of Sciences Publication Activity Database

    Šálek, Martin; Kreisinger, Jakub; Sedláček, František; Albrecht, Tomáš

    2010-01-01

    Roč. 98, č. 2 (2010), s. 86-91 ISSN 0169-2046 R&D Projects: GA MŠk LC06073; GA MŠk 1P05OC078 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z60930519 Keywords : mammalian predators * fragmentation * small mammals * edge effect * predator–prey * distribution * Mustelids Subject RIV: EH - Ecology, Behaviour Impact factor: 2.004, year: 2010

  11. Impact of the pedestal plasma density on dynamics of edge localized mode crashes and energy loss scaling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. Q., E-mail: xxu@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States); Li, G. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2014-12-15

    The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1 < n < 5), therefore the width of the growth rate spectrum γ(n) becomes narrower and the peak growth shifts to lower n. Nonlinear BOUT++ simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.

  12. MEASURING PROTOPLANETARY DISK GAS SURFACE DENSITY PROFILES WITH ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Jonathan P.; McPartland, Conor, E-mail: jpw@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2016-10-10

    The gas and dust are spatially segregated in protoplanetary disks due to the vertical settling and radial drift of large grains. A fuller accounting of the mass content and distribution in disks therefore requires spectral line observations. We extend the modeling approach presented in Williams and Best to show that gas surface density profiles can be measured from high fidelity {sup 13}CO integrated intensity images. We demonstrate the methodology by fitting ALMA observations of the HD 163296 disk to determine a gas mass, M {sub gas} = 0.048 M {sub ⊙}, and accretion disk characteristic size R {sub c} = 213 au and gradient γ = 0.39. The same parameters match the C{sup 18}O 2–1 image and indicate an abundance ratio [{sup 12}CO]/[C{sup 18}O] of 700 independent of radius. To test how well this methodology can be applied to future line surveys of smaller, lower mass T Tauri disks, we create a large {sup 13}CO 2–1 image library and fit simulated data. For disks with gas masses 3–10 M {sub Jup} at 150 pc, ALMA observations with a resolution of 0.″2–0.″3 and integration times of ∼20 minutes allow reliable estimates of R {sub c} to within about 10 au and γ to within about 0.2. Economic gas imaging surveys are therefore feasible and offer the opportunity to open up a new dimension for studying disk structure and its evolution toward planet formation.

  13. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory.

    Science.gov (United States)

    Lima, Frederico A; Bjornsson, Ragnar; Weyhermüller, Thomas; Chandrasekaran, Perumalreddy; Glatzel, Pieter; Neese, Frank; DeBeer, Serena

    2013-12-28

    X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.

  14. Density effects on tokamak edge turbulence and transport with magnetic X-points

    International Nuclear Information System (INIS)

    Xu, X.Q.; Cohen, R.H.; Nevins, W.M.; Rognlien, T.D.; Ryutov, D.D.; Umansky, M.V.; Pearlstein, L.D.; Bulmer, R.H.; Russell, D.A.; Myra, J.R.; D'Ippolito, D.A.; Greenwald, M.; Snyder, P.B.; Mahdavi, M.A.

    2005-01-01

    Results are presented from the 3D electromagnetic turbulence code BOUT, the 2D transport code UEDGE, and theoretical analysis of boundary turbulence and transport in a real divertor-plasma geometry and its relationship to the density limit. Key results include: (1) a transition of the boundary turbulence from resistive X-point to resistive-ballooning as a critical plasma density is exceeded; (2) formation of an X-point MARFE in 2D UEDGE transport simulations for increasing outboard radial transport as found by BOUT for increasing density; (3) identification of convective transport by localized plasma 'blobs' in the SOL at high density during neutral fueling, and decorrelation of turbulence between the midplane and the divertor leg due to strong X-point magnetic shear; (4) a new divertor-leg instability driven at high plasma beta by a radial tilt of the divertor plate. (author)

  15. Modified knife-edge method for current density distribution measurements in e-beam writers

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Kolařík, Vladimír; Horáček, Miroslav; Matějka, Milan; Matějka, František

    2013-01-01

    Roč. 31, č. 3 (2013), 031603:1-6 ISSN 1071-1023 R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : electron-beam * intensity distribution * aperture * detector * profile * size Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.358, year: 2013

  16. Density and temperature profile modifications with electron cyclotron power injection in quiescent double barrier discharges on DIII-D

    International Nuclear Information System (INIS)

    Casper, T A; Burrell, K H; Doyle, E J; Gohil, P; Lasnier, C J; Leonard, A W; Moller, J M; Osborne, T H; Snyder, P B; Thomas, D M; Weiland, J; West, W P

    2006-01-01

    Quiescent double barrier (QDB) conditions often form when an internal transport barrier is created with high-power neutral-beam injection into a quiescent H-mode (QH) plasma. These QH-modes offer an attractive, high-performance operating scenario for burning plasma experiments due to their quasi-stationarity and lack of edge localized modes. Our initial experiments and modelling using ECH/ECCD in QDB shots were designed to control the current profile and, indeed, we have observed a strong dependence on the q-profile when EC-power is used inside the core transport barrier region. While strong electron heating is observed with EC power injection, we also observe a drop in the other core parameters, namely ion temperature and rotation, electron density and impurity concentration. At onset and termination of the EC pulse, dynamically changing conditions are induced that provide a rapid evolution of T e /T i profiles accessible with 0.3 e /T i ) axis e /T i ratio as the ion temperature and density profiles flatten with this change in transport. The change in transport is consistent with a destabilization of ITG turbulence as inferred from the reduction of the stability threshold due to the change in T e /T i

  17. Determination of Jupiter's electron density profile from plasma wave observations

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Scarf, F.L.; Kurth, W.S.; Shaw, R.R.; Poynter, R.L.

    1981-01-01

    This paper summarizes the electron density measurements obtained in the Jovian magnetosphere from the plasma wave instruments on the Voyager 1 and 2 spacecraft. Three basic techniques are discussed for determining the electron density: (1) local measurements from the low-frequency cutoff of continuum radiation, (2) local measurements from the frequency of upper hybrid resonance emissions, and (3) integral measurements from the dispersion of whistlers. The limitations and advantages of each technique are critically reviewed. In all cases the electron densities are unaffected by spacecraft charging or sheath effects, which makes these measurements of particular importance for verifying in situ plasma and low-energy charged particle measurments. In the outer regions of the dayside magnetosphere, beyond about 40 R/sub J/, the electron densities range from about 3 x 10 -3 to 3 x 10 -2 cm -3 . On Voyager 2, several brief excursions apparently occurred into the low-density region north of the plasma sheet with densities less than 10 -3 cm -3 . Approaching the planet the electron density gradually increases, with the plasma frequency extending above the frequency range of the plasma wave instrument (56 kHz, or about 38 electrons cm -3 ) inside of about 8 R/sub J/. Within the high-density region of the Io plasma torus, whistlers provide measurements of the north-south scale height of the plasma torus, with scale heights ranging from about 0.9 to 2.5 R/sub J/

  18. Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates.

    Science.gov (United States)

    Donahue, Courtney M; Pacheco, Juan S Lezama; Keith, Jason M; Daly, Scott R

    2014-06-28

    S K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT) calculations were performed on a series of As[S2CNR2]3 complexes, where R2 = Et2, (CH2)5 and Ph2, to determine how dithiocarbamate substituents attached to N affect As[S2CNR2]3 electronic structure. Complimentary [PPh4][S2CNR2] salts were also studied to compare dithiocarbamate bonding in the absence of As. The XAS results indicate that changing the orientation of the alkyl substituents from trans to cis (R2 = Et2vs. (CH2)5) yields subtle variations whereas differences associated with a change from alkyl to aryl are much more pronounced. For example, despite the differences in As 4p mixing, the first features in the S K-edge XAS spectra of [PPh4][S2CNPh2] and As[S2CNPh2]3 were both shifted by 0.3 eV compared to their alkyl-substituted derivatives. DFT calculations revealed that the unique shift observed for [PPh4][S2CNPh2] is due to phenyl-induced splitting of the π* orbitals delocalized over N, C and S. A similar phenomenon accounts for the shift observed for As[S2CNPh2]3, but the presence of two unique S environments (As-S and As···S) prevented reliable analysis of As-S covalency from the XAS data. In the absence of experimental values, DFT calculations revealed a decrease in As-S orbital mixing in As[S2CNPh2]3 that stems from a redistribution of electron density to S atoms participating in weaker As···S interactions. Simulated spectra obtained from TDDFT calculations reproduce the experimental differences in the S K-edge XAS data, which suggests that the theory is accurately modeling the experimental differences in As-S orbital mixing. The results highlight how S K-edge XAS and DFT can be used cooperatively to understand the electronic structure of low symmetry coordination complexes containing S atoms in different chemical environments.

  19. Response of temperature and density profiles to heat deposition profile and its impact on global scaling in LHD

    International Nuclear Information System (INIS)

    Yamada, H.; Murakami, S.; Yamazaki, K.

    2002-01-01

    Energy confinement and heat transport of net current-free NBI-heated plasmas in the Large Helical Device (LHD) are discussed with an emphasis on density dependence. Although the apparent density dependence of the energy confinement time has been demonstrated in a wide parameter range in LHD, the loss of this dependence has been observed in the high density regime under the specific condition. Broad heat deposition due to off-axis alignment and shallow penetration of neutral beams degrades the global energy confinement while the local heat transport maintains a clear temperature dependence lying between Bohm and gyro-Bohm characteristics. The central heat deposition inclines towards an intrinsic density dependence like τ E ∝(n-bar e /P) 0.6 from the saturated state. The broadening of the temperature profile due to the broad heat deposition profile contrasts with the invariant property which has observed widely as profile consistency and stiffness in tokamak experiments. (author)

  20. Response of temperature and density profiles to heat deposition profile and its impact on global scaling in LHD

    International Nuclear Information System (INIS)

    Yamada, H.; Murakami, S.; Yamazaki, K.

    2003-01-01

    Energy confinement and heat transport of net current-free NBI-heated plasmas in the Large Helical Device (LHD) are discussed with an emphasis on density dependence. Although the apparent density dependence of the energy confinement time has been demonstrated in a wide parameter range in LHD, the loss of this dependence has been observed in the high density regime under the specific condition. Broad heat deposition due to off-axis alignment and shallow penetration of neutral beams degrades the global energy confinement while the local heat transport maintains a clear temperature dependence lying between Bohm and gyro-Bohm characteristics. The central heat deposition inclines towards an intrinsic density dependence like τ E ∝(n-bars e /P) 0.6 from the saturated state. The broadening of the temperature profile due to the broad heat deposition profile contrasts with the invariant property which has observed widely as profile consistency and stiffness in tokamak experiments. (author)

  1. Ion temperature profiles from the plasma center to the edge of ASDEX combining high and low energy CX-diagnostics

    International Nuclear Information System (INIS)

    Verbeek, H.; Heinrich, O.; Schneider, R.; Fahrbach, H.U.; Herrmann, W.; Neuhauser, J.; Stroth, U.; Reiter, D.

    1992-01-01

    The charge exchange (CX) neutral energy distribution from ASDEX measured with the conventional neutral particle analyzers (NPA) at energies >500 eV are combined with the low energy CX spectra from the low energy neutral analyzer (LENA). In the region of overlap their shapes fit each other very well. With the 3D EIRENE code the neutral gas was simulated and ion temperature (T i ) profiles from the center to the edge are obtained. The T i values at the separatrix and the edge based on the LENA data are considerably lower than those suggested earlier from the NPA data. This is attributed to the different energy ranges - high energies for the NPA, low energies for LENA - that are used for the T i evaluation. (orig.)

  2. An analytical calculation of the axial density profile for 1-d slab expansion

    International Nuclear Information System (INIS)

    Ho, D

    1999-01-01

    Obtaining an analytical expression for the axial density profile can provide us with a quick and convenient way to evaluate the density evolution for targets with different densities and dimensions. In this note, we show that such an analytical expression can be obtained based on the self-similar solutions and the method of characteristics for 1-D slab expansion

  3. Machine-vision-based identification of broken inserts in edge profile milling heads

    NARCIS (Netherlands)

    Fernandez Robles, Laura; Azzopardi, George; Alegre, Enrique; Petkov, Nicolai

    This paper presents a reliable machine vision system to automatically detect inserts and determine if they are broken. Unlike the machining operations studied in the literature, we are dealing with edge milling head tools for aggressive machining of thick plates (up to 12 centimetres) in a single

  4. Confinement bifurcation by current density profile perturbation in TUMAN-3M tokamak

    International Nuclear Information System (INIS)

    Lebedev, S.V.; Andreiko, M.V.; Askinazi, L.G.

    2001-01-01

    In the recent experiments performed on TUMAN-3M the possibility to switch on/off the H-mode by current density profile perturbations has been shown. The j(r) perturbations were created by fast Current Ramp Up/Down or by Magnetic Compression produced by a fast increase of the toroidal magnetic field. It was found that the Current Ramp Up (CRU) and Magnetic Compression (MC) are useful means for H-mode triggering. The Current Ramp Down (CRD) triggers H-L transition. The difference in the j(r) behavior in these experiments suggests the peripheral current density may not be the critical parameter controlling L-H and H-L transitions. Confinement bifurcation in the above experiments could be explained by the unified mechanism: variation of a turbulent transport resulting from radial electric field emerging near the edge in the conditions of alternating toroidal electric field Ej and different electron and ion collisionalities. According to the suggested model the toroidal field E φ arising in the periphery during the CRU and MC processes amplifies Ware drift, which mainly influences electron component. As a result the favorable for the transition negative (inward directed) E r emerges. In the CRD scenario, when E φ is opposite to the total plasma current direction, the mechanism should generate positive E r , which is thought to be unfavorable for the H-mode. The experimental data on L-H and H-L transitions in various scenarios and the results of the modeling of E r emerging in the CRU experiment are presented in the paper. (author)

  5. Measurement of electron density profiles by soft X-ray tomography on the RTP tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, D.F. da; Donne, A.J.H.; Lyadina, E.S.; Rutteman, R.H.; Tanzi, C.P. [FOM-Instituut voor Plasmafysica, Rijnhuizen (Netherlands)

    1993-12-31

    Tomographic diagnosis of the soft x-ray emissivity profile is a powerful method for studying several plasma parameters. The x-ray emissivity is a complicated function of plasma quantities like the electron density and temperature, and the impurity content in the plasma. These quantities can be studied separately provided that information is available on the remaining parameters. Soft x-ray emissivity profiles have already been used successfully in other machines to determine local values of impurity densities and the effective charge Z{sub eff}. In the RTP tokamak the electron density profile has been inferred from a modelling of the x-ray emissivity in situations where information is available on the electron temperature profile, the value of Z{sub eff}, and the relative proportion of the impurities. The method can be useful for the study of hollow density profiles that cannot be properly reconstructed by Abel inversion of interferometer or reflectometer data. (author) 7 refs., 2 figs.

  6. Measurement of electron density profiles by soft X-ray tomography on the RTP tokamak

    International Nuclear Information System (INIS)

    Cruz, D.F. da; Donne, A.J.H.; Lyadina, E.S.; Rutteman, R.H.; Tanzi, C.P.

    1993-01-01

    Tomographic diagnosis of the soft x-ray emissivity profile is a powerful method for studying several plasma parameters. The x-ray emissivity is a complicated function of plasma quantities like the electron density and temperature, and the impurity content in the plasma. These quantities can be studied separately provided that information is available on the remaining parameters. Soft x-ray emissivity profiles have already been used successfully in other machines to determine local values of impurity densities and the effective charge Z eff . In the RTP tokamak the electron density profile has been inferred from a modelling of the x-ray emissivity in situations where information is available on the electron temperature profile, the value of Z eff , and the relative proportion of the impurities. The method can be useful for the study of hollow density profiles that cannot be properly reconstructed by Abel inversion of interferometer or reflectometer data. (author) 7 refs., 2 figs

  7. Data description and quality assessment of ionospheric electron density profiles for ARPA modeling project. Technical report

    International Nuclear Information System (INIS)

    Conkright, R.O.

    1977-03-01

    This report presents a description of the automated method used to produce electron density (N(h)) profiles from ionograms recorded on 35mm film and an assessment of the resulting data base. A large data base of about 30,000 profiles was required for an ionospheric modeling project. This motivated a search for an automated method of producing profiles. The automated method used is fully described, the resulting data are given a quality grade, and the noon and midnight profiles are presented. Selected portions of this data base are compared with profiles produced by the standard profiling method in use by the Environmental Data Service at Boulder, Colorado

  8. Temporal evolutions of electron temperature and density with edge localized mode in the JT-60U divertor plasma

    International Nuclear Information System (INIS)

    Nakano, T; Kubo, H; Asakura, N

    2010-01-01

    From the intensity ratios of the three He I lines measured at 20 kHz, the temporal evolutions of the electron temperature and density during and after the power and the particle flow into the divertor plasma caused by edge localized modes are determined. The electron temperature increases from 70 eV to 80 eV with increasing D α intensity. Then, at the peak of D α intensity, the electron temperature starts decreasing down to 60 eV. The electron density increases from 0.1 x 10 19 m -3 to 0.3 x 10 19 m -3 with increasing D α intensity, and then starts to decrease more gradually compared with the electron temperature after the peak of D α intensity. It is interpreted that the increase of the electron temperature is ascribed to the power and the particle flow into the divertor plasma, and that the decrease of the electron temperature and the increase of the electron density are ascribed to the ionization of the recycled neutrals, which consumes the electron energy and produces electrons.

  9. Effect of magnetic boundary on edge plasma profiles studied using probe measurements in EXTRAP T2R

    OpenAIRE

    Moustaphawi, Hawra

    2012-01-01

    In this Master’s thesis project, several experiments are conducted under three different conditions in order to study their effect on the edge plasma profiles. In the first case, the standard case, there is no external interference and the plasma is studied under normal lab environments. In the second case, the plasma position inside the EXTRAP T2R device is changed by a few millimeters and in the third case a magnetic boundary is inserted into the experiment. For each set of the experiment, ...

  10. CONTROL SYSTEM FOR THE LITHIUM BEAM EDGE PLASMA CURRENT DENSITY DIAGNOSTIC ON THE DIII-D TOKAMAK

    International Nuclear Information System (INIS)

    PEAVY, J.J.; CARY, W.P; THOMAS, D.M; KELLMAN, D.H.; HOYT, D.M; DELAWARE, S.W.; PRONKO, S.G.E.; HARRIS, T.E.

    2004-03-01

    OAK-B135 An edge plasma current density diagnostic employing a neutralized lithium ion beam system has been installed on the DIII-D tokamak. The lithium beam control system is designed around a GE Fanuc 90-30 series PLC and Cimplicity(reg s ign) HMI (Human Machine Interface) software. The control system operates and supervises a collection of commercial and in-house designed high voltage power supplies for beam acceleration and focusing, filament and bias power supplies for ion creation, neutralization, vacuum, triggering, and safety interlocks. This paper provides an overview of the control system, while highlighting innovative aspects including its remote operation, pulsed source heating and pulsed neutralizer heating, optimizing beam regulation, and beam ramping, ending with a discussion of its performance

  11. Improvement of mobility edge model by using new density of states with exponential tail for organic diode

    International Nuclear Information System (INIS)

    Muhammad Ammar Khan; Sun Jiu-Xun

    2015-01-01

    The mobility edge (ME) model with single Gaussian density of states (DOS) is simplified based on the recent experimental results about the Einstein relationship. The free holes are treated as being non-degenerate, and the trapped holes are dealt with as being degenerate. This enables the integral for the trapped holes to be easily realized in a program. The J–V curves are obtained through solving drift-diffusion equations. When this model is applied to four organic diodes, an obvious deviation between theoretical curves and experimental data is observed. In order to solve this problem, a new DOS with exponential tail is proposed. The results show that the consistence between J–V curves and experimental data based on a new DOS is far better than that based on the Gaussian DOS. The variation of extracted mobility with temperature can be well described by the Arrhenius relationship. (paper)

  12. Electron temperature and density profiles measurement in the TJ-1 tokamak by Thomson scattering

    International Nuclear Information System (INIS)

    Pardo, C.; Zurro, B.

    1986-01-01

    Electron temperature and density profiles of ohmically heated hydrogen plasmas in the TJ-1 tokamak have been measured by Thomson scattering. The temperature profile peaks sharply in the central region while the density profile is very flat. Temperature values between 100 and 390 eV have been measured for densities in the range of 5.10 12 to 2.6.10 13 cm -3 . Parameters characterizing TJ-1 plasma, such as confinement times Z eff , have been deduced from experimental data. Energy confinement times are compared with experimental scaling laws. (author)

  13. Electron number density profiles derived from radio occultation on the CASSIOPE spacecraft

    DEFF Research Database (Denmark)

    Shume, E. B.; Vergados, P.; Komjathy, A.

    2017-01-01

    This paper presents electron number density profiles derived from high resolution Global Positioning System (GPS) radio occultation (RO) observations performed using the Enhanced Polar Outflow Probe (e-POP) payload on the high inclination CAScade, Smallsat and IOnospheric Polar Explorer (CASSIOPE...... good agreement with density profiles estimated from ionosonde data, measured over nearby stations to the latitude and longitude of the RO tangent points, (2) in good agreement with density profiles inferred from GPS RO measured by the Constellation Observing System for Meteorology, Ionosphere...

  14. Response of temperature and density profiles to heat deposition profile and its impact on global scaling in LHD

    International Nuclear Information System (INIS)

    Yamada, H.

    2002-01-01

    Significant density dependence of the energy confinement time as described in the ISS95 scaling has been demonstrated in the extended parameter regimes in LHD. However, recent experiments have indicated that this density dependence is lost at a certain density under specific conditions. This paper discusses the cause of this saturation and related characteristics of anomalous transport. The saturation of the energy confinement time is observed in the density ramp-up phase of NBI heated plasmas. In contrast to the global energy confinement time, the local heat conduction coefficient still indicates the temperature dependence which is a companion to the density dependence of the energy confinement time. The apparent contradiction between the global confinement and the local transport can be attributed to the change of the heat deposition profile. Through this study, the response of temperature and density profiles to the heat deposition profile is highlighted, which is contrasted to the concept of stiffness or profile consistency observed in tokamaks. The major anomalous transport models based on ITG/TEM and interchange/ballooning modes are assessed. (author)

  15. Electron density and temperature profile diagnostics for C-2 field reversed configuration plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Deng, B. H.; Kinley, J. S.; Schroeder, J. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2012-10-15

    The 9-point Thomson scattering diagnostic system for the C-2 field reversed configuration plasmas is improved and the measured electron temperature profiles are consistent with theoretical expectations. Rayleigh scattering revealed a finite line width of the ruby laser emission, which complicates density calibration. Taking advantage of the plasma wobble motion, density profile reconstruction accuracy from the 6-chord two-color CO{sub 2}/HeNe interferometer data is improved.

  16. Characterization of the intrinsic density profiles for liquid surfaces

    International Nuclear Information System (INIS)

    Chacon, Enrique; Tarazona, Pedro

    2005-01-01

    This paper presents recent advances in the characterization of the intrinsic structures in computer simulations of liquid surfaces. The use of operational definitions for the intrinsic surface, associated with each molecular configuration of a liquid slab, gives direct access to the intrinsic profile and to the wavevector dependent surface tension. However, the characteristics of these functions depend on the definition used for the intrinsic surface. We discuss the pathologies associated with a local Gibbs dividing surface definition, and consider the alternative definition of a minimal area surface, going though a set of surface pivots, self-consistently chosen to represent the first liquid layer

  17. Experimental investigation of edge localised modes in JET

    International Nuclear Information System (INIS)

    Lindholm Colton, A.

    1993-08-01

    Edge Localised Modes (ELMs) in the JET tokamak have been studied experimentally, using density profile and fluctuation data from a multichannel reflectometer and temperature profile data from an ECE heterodyne radiometer. The following topics have been investigated: The radial extent and localisation of the density and temperature profile perturbations caused by the ELMs. Fluctuations in the density and magnetic field in connection with the ELMs. The correlation between the repetition frequency of the L-H transition ELMs, and the plasma edge temperature and density. Trajectories in n-T space prior to ELMs later in the H-mode. (au) (39 refs.)

  18. Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D.

    Science.gov (United States)

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

    2016-11-01

    Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.

  19. Variations of the ionospheric parameters and vertical electron density distribution at the northern edge of the EIA from 2010 to 2015 along 95°E and comparison with the IRI-2012

    Science.gov (United States)

    Kalita, Bitap Raj; Bhuyan, Pradip Kumar

    2017-07-01

    The vertical electron density profiles over Dibrugarh (27.5°N, 95°E, 43° dip) a low mid latitude station normally located at the northern edge of the EIA for the period of July 2010 till October 2015 are constructed from the measured bottom side profiles and ionosonde-GPS TEC assisted Topside Sounder Model (TSM) topside profiles. The bottom side density profiles are obtained by using POLAN on the manually scaled ionograms. The topside is constructed by the modified ionosonde assisted TSM model (TaP-TSM assisted by POLAN) which is integrated with POLAN for the first time. The reconstructed vertical profile is compared with the IRI predicted density profile and the electron density profile obtained from the COSMIC/FORMOSAT radio occultation measurements over Dibrugarh. The bottom side density profiles are fitted to the IRI bottom side function to obtain best-fit bottom side thickness parameter B0 and shape parameter B1. The temporal and solar activity variation of the B-parameters over Dibrugarh are investigated and compared to those predicted by IRI-2012 model with ABT-2009 option. The bottom side thickness parameter B0 predicted by the IRI model is found to be similar to the B0 measured over Dibrugarh in the night time and the forenoon hours. Differences are observed in the early morning and the afternoon period. The IRI doesn't reproduce the morning collapse of B0 and overestimates the B0 over Dibrugarh in the afternoon period, particularly in summer and equinox. The IRI model predictions are closest to the measured B0 in the winter of low solar activity. The B0 over Dibrugarh is found to increase by about 15% with solar activity during the period of study encompassing almost the first half of solar cycle 24 but solar activity effect was not observed in the B1 parameter. The topside profile obtained from TaP profiler is thicker than the IRI topside in equinox from afternoon to sunrise period but is similar to the IRI in summer daytime. The differences in the

  20. 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

  1. Role of substituents on the reactivity and electron density profile of ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 5. Role of substituents on the reactivity and electron density profile of diimine ligands: A density functional theory based study. Bhakti S Kulkarni Deepti Mishra Sourav Pal. Volume 125 Issue 5 September 2013 pp 1247-1258 ...

  2. ICRF power-deposition profiles and heating in monster sawtooth and peaked-density profile discharges in JET

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Taroni, A.; Ellis, J.J.; Jacquinot, J.; Stuart, D.F.

    1989-01-01

    In this paper, we compare experimental results of electron and ion-heating in discharges that feature monster sawtooth with those in pellet-produced peaked-density profile discharges which were heated with ICRF. Also we carry out a comprehensive analysis of ICRF-heated peaked-density profile discharges by a transport code to simulate the evolution of JET discharges and to provide an insight into the improved heating and confinement found in these discharges. In this analysis, the ICRF power-deposition profile in the minority-heating scenario is computed by the ray-tracing code BRAYCO that self-consistently takes the finite antenna geometry, its radiation spectrum and the hot-plasma damping into account. The power delivered to ions and electrons is calculated based on Stix model. (author) 10 refs., 5 figs

  3. Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

    International Nuclear Information System (INIS)

    Walkden, N. R.; Adamek, J.; Komm, M.; Allan, S.; Elmore, S.; Fishpool, G.; Harrison, J.; Kirk, A.; Dudson, B. D.

    2015-01-01

    The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ∼1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the E R measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak

  4. Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

    Science.gov (United States)

    Walkden, N. R.; Adamek, J.; Allan, S.; Dudson, B. D.; Elmore, S.; Fishpool, G.; Harrison, J.; Kirk, A.; Komm, M.

    2015-02-01

    The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ˜1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the ER measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.

  5. Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

    Energy Technology Data Exchange (ETDEWEB)

    Walkden, N. R., E-mail: nrw504@york.ac.uk [CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB (United Kingdom); Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD (United Kingdom); Adamek, J.; Komm, M. [Institute of Plasma Physics of AS CR, v. v. i., Za Slovankou 3, 182 00 Praha 8 (Czech Republic); Allan, S.; Elmore, S.; Fishpool, G.; Harrison, J.; Kirk, A. [CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB (United Kingdom); Dudson, B. D. [Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD (United Kingdom)

    2015-02-15

    The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ∼1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the E{sub R} measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.

  6. Transport simulations of a density limit in radiation-dominated tokamak discharges: profile effects

    International Nuclear Information System (INIS)

    Stotler, D.P.

    1988-01-01

    The density limit observed in tokamak experiments is thought to be due to a radiative collapse of the current channel. A transport code coupled with a magnetohydrodynamic (MHD) equilibrium routine is used to determine the detailed, self-consistent evolution of the plasma profiles in tokamak discharges with radiated power close to or equaling the input power. The present work is confined to Ohmic discharges in steady state. It is found that the shape of the density profile can have a significant impact on the variation of the maximum electron density with plasma current. Analytic calculations confirm this result

  7. Transport simulations of a density limit in radiation-dominated tokamak discharges: Profile effects

    International Nuclear Information System (INIS)

    Stotler, D.P.

    1988-06-01

    The density limit observed in tokamak experiments is thought to be due to a radiative collapse of the current channel. A transport code coupled with an MHD equilibrium routine is used to determine the detailed, self-consistent evolution of the plasma profiles in tokamak discharges with radiated power close to or equalling the input power. The present work is confined to ohmic discharges in steady state. It is found that the shape of the density profile can have a significant impact on the variation of the maximum electron density with plasma current. Analytic calculations confirm this result. 41 refs., 9 figs

  8. Experimental electron density profiles of the mid-latitude lower ionosphere and winter anomaly

    International Nuclear Information System (INIS)

    Rapoport, Z.Ts.; Sinel'nikov, V.M.

    1996-01-01

    Summarized measurements of high-latitude electron density profiles of N e lower ionosphere, obtained at M100B meteorological rockets by precision method of coherent frequencies during 1979-1990 at the Volgograd test site (φ = 48 deg 41' N; λ = 44 deg 21 E), are presented. The profiles obtained represent average values of electron density at various altitudes of lower ionosphere (h = 70-100 km) during night and day time hours in winter and non winter periods. Increased electron density values during daytime hours in winter are related to winter anomaly phenomenon. 36 refs.; 1 fig

  9. 2D electron density profile measurement in tokamak by laser-accelerated ion-beam probe.

    Science.gov (United States)

    Chen, Y H; Yang, X Y; Lin, C; Wang, L; Xu, M; Wang, X G; Xiao, C J

    2014-11-01

    A new concept of Heavy Ion Beam Probe (HIBP) diagnostic has been proposed, of which the key is to replace the electrostatic accelerator of traditional HIBP by a laser-driven ion accelerator. Due to the large energy spread of ions, the laser-accelerated HIBP can measure the two-dimensional (2D) electron density profile of tokamak plasma. In a preliminary simulation, a 2D density profile was reconstructed with a spatial resolution of about 2 cm, and with the error below 15% in the core region. Diagnostics of 2D density fluctuation is also discussed.

  10. Electron density profiles in the background of LF absorption during Forbush-decrease and PSE

    International Nuclear Information System (INIS)

    Satori, G.

    1989-01-01

    Based on the simulation of different Forbush decrease and particle precipitation effects in the D region, electron density profiles in the mid-latitudes the ionospheric absorption of low frequency (LF) radio waves was determined. The absorption variations at different frequenceis are strongly affected by the shape of the electron density profile. A structure appears which sometimes resembles the letter S (in a sloping form). Both the height (around 70 to 72 km) and the depth of the local minimum in the electron density contribute to the computed absorption changes of various degree at different frequencies. In this way several observed special absorption events can be interpreted

  11. Polar observations of electron density distribution in the Earth’s magnetosphere. 2. Density profiles

    Directory of Open Access Journals (Sweden)

    H. Laakso

    2002-11-01

    Full Text Available Using spacecraft potential measurements of the Polar electric field experiment, we investigate electron density variations of key plasma regions within the magnetosphere, including the polar cap, cusp, trough, plasmapause, and auroral zone. The statistical results were presented in the first part of this study, and the present paper reports detailed structures revealed by individual satellite passes. The high-altitude (> 3 RE polar cap is generally one of the most tenuous regions in the magnetosphere, but surprisingly, the polar cap boundary does not appear as a steep density decline. At low altitudes (1 RE in summer, the polar densities are very high, several 100 cm-3 , and interestingly, the density peaks at the central polar cap. On the noonside of the polar cap, the cusp appears as a dense, 1–3° wide region. A typical cusp density above 4 RE distance is between several 10 cm-3 and a few 100 cm-3 . On some occasions the cusp is crossed multiple times in a single pass, simultaneously with the occurrence of IMF excursions, as the cusp can instantly shift its position under varying solar wind conditions, similar to the magnetopause. On the nightside, the auroral zone is not always detected as a simple density cavity. Cavities are observed but their locations, strengths, and sizes vary. Also, the electric field perturbations do not necessarily overlap with the cavities: there are cavities with no field disturbances, as well as electric field disturbances observed with no clear cavitation. In the inner magnetosphere, the density distributions clearly show that the plasmapause and trough densities are well correlated with geomagnetic activity. Data from individual orbits near noon and midnight demonstrate that at the beginning of geomagnetic disturbances, the retreat speed of the plasmapause can be one L-shell per hour, while during quiet intervals the plasmapause can expand anti-earthward at the same speed. For the trough region, it is found

  12. Semi-analytical model of laser resonance absorption in plasmas with a parabolic density profile

    International Nuclear Information System (INIS)

    Pestehe, S J; Mohammadnejad, M

    2010-01-01

    Analytical expressions for mode conversion and resonance absorption of electromagnetic waves in inhomogeneous, unmagnetized plasmas are required for laboratory and simulation studies. Although most of the analyses of this problem have concentrated on the linear plasma density profile, there are a few research works that deal with different plasma density profiles including the parabolic profile. Almost none of them could give clear analytical formulae for the electric and magnetic components of the electromagnetic field propagating through inhomogeneous plasmas. In this paper, we have considered the resonant absorption of laser light near the critical density of plasmas with parabolic electron density profiles followed by a uniform over-dense region and have obtained expressions for the electric and magnetic vectors of laser light propagating through the plasma. An estimation of the fractional absorption of laser energy has also been carried out. It has been shown that, in contrast to the linear density profile, the energy absorption depends explicitly on the value of collision frequency as well as on a new parameter, N, called the over-dense density order.

  13. Density and impurity profile behaviours in HL-2A tokamak with different gas fuelling methods

    International Nuclear Information System (INIS)

    Zheng-Ying, Cui; Yan, Zhou; Wei, Li; Bei-Bin, Feng; Ping, Sun; Chun-Feng, Dong; Yi, Liu; Wen-Yu, Hong; Qing-Wei, Yang; Xuan-Tong, Ding; Xu-Ru, Duan

    2009-01-01

    The electron density profile peaking and the impurity accumulation in the HL-2A tokamak plasma are observed when three kinds of fuelling methods are separately used at different fuelling particle locations. The density profile becomes more peaked when the line-averaged electron density approaches the Greenwald density limit n G and, consequently, impurity accumulation is often observed. A linear increase regime in the density range n e G and a saturation regime in n e > 0.6n G are obtained. There is no significant difference in achieved density peaking factor f ne between the supersonic molecular beam injection (SMBI) and gas puffing into the plasma main chamber. However, the achieved f ne is relatively low, in particular, in the case of density below 0.7n G , when the working gas is puffed into the divertor chamber. A discharge with a density as high as 1.2n G , i.e. n e = 1.2n G , can be achieved by SMBI just after siliconization as a wall conditioning. The metallic impurities, such as iron and chromium, also increase remarkably when the impurity accumulation happens. The mechanism behind the density peaking and impurity accumulation is studied by investigating both the density peaking factor versus the effective collisionality and the radiation peaking versus density peaking. (fluids, plasmas and electric discharges)

  14. Quasi-quadrature interferometer for plasma density radial profile measurements

    International Nuclear Information System (INIS)

    Lowenthal, D.D.; Hoffman, A.L.

    1979-01-01

    A cw Mach Zehnder multichannel interferometer has been developed to measure time-dependent fractional fringe shifts with an accuracy of one-fortieth fringe. The design is quasi-quadrature in that known phase shifts, introduced in the reference beam, are time multiplexed with the normal reference beam. This technique requires only one detector per interferometer channel as compared to two detectors for most quadrature designs. The quadrature information makes the sense of density changes unambiguous, it automatically calibrates the instrument during the plasma event, and it makes fringe shift measurements virtually independent of fringe contrast fluctuations caused by plasma refractive and/or absorptive effects. The interferometer optical design is novel in that the electro-optic crystal used to introduce the 90 0 phase shifts is located in the common 2-mm-diam HeNe entrance beam to the interferometer, by exploiting polarization techniques, rather than in the expanded 1--2-cm reference beam itself. This arrangement greatly reduces the size, cost, and high-voltage requirements for the phase modulating crystal

  15. Earth-mass haloes and the emergence of NFW density profiles

    Science.gov (United States)

    Angulo, Raul E.; Hahn, Oliver; Ludlow, Aaron D.; Bonoli, Silvia

    2017-11-01

    We simulate neutralino dark matter (χDM) haloes from their initial collapse, at ˜ earth mass, up to a few percent solar. Our results confirm that the density profiles of the first haloes are described by a ˜r-1.5 power law. As haloes grow in mass, their density profiles evolve significantly. In the central regions, they become shallower and reach on average ˜r-1, the asymptotic form of an NFW profile. Using non-cosmological controlled simulations, we observe that temporal variations in the gravitational potential caused by major mergers lead to a shallowing of the inner profile. This transformation is more significant for shallower initial profiles and for a higher number of merging systems. Depending on the merger details, the resulting profiles can be shallower or steeper than NFW in their inner regions. Interestingly, mergers have a much weaker effect when the profile is given by a broken power law with an inner slope of -1 (such as NFW or Hernquist profiles). This offers an explanation for the emergence of NFW-like profiles: after their initial collapse, r-1.5 χDM haloes suffer copious major mergers, which progressively shallows the profile. Once an NFW-like profile is established, subsequent merging does not change the profile anymore. This suggests that halo profiles are not universal but rather a combination of (1) the physics of the formation of the microhaloes and (2) their early merger history - both set by the properties of the dark matter particle - as well as (3) the resilience of NFW-like profiles to perturbations.

  16. Equatorial bottom and topside electron density profiles and comparison with IRI

    International Nuclear Information System (INIS)

    Reinisch, B.W.; Huang, X.; Conway, J.; Komjathy, A.

    2001-01-01

    A new technique of estimating the ionospheric topside profile from the information contained in the groundbased ionograms is described. The electron density profile above the F2 layer peak is approximated by an α-Chapman function with a constant scale height that is derived from the bottomside profile shape near the F2 peak. The scale height is obtained from the bottomside profile by representing the latter in terms of α-Chapman functions with scale heights H(h) that vary as a function of height. The scale height at the layer peak is then used for the topside profile. The bottomside and topside electron contents is obtained by integrating the electron density from h=0 to hmF2 and from hmF2 to ∞. The ionogram derived electron content values for Jicamarca in 1998 are compared with the respective IRI values. (author)

  17. Dependence of recycling and edge profiles on lithium evaporation in high triangularity, high performance NSTX H-mode discharges

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R., E-mail: rmaingi@pppl.gov [Princeton Plasma Physics Laboratory, Receiving 3, Route 1 North, Princeton, NJ 08543 (United States); Osborne, T.H. [General Atomics, 3550 General Atomics Ct., San Diego, CA 92121 (United States); Bell, M.G.; Bell, R.E.; Boyle, D.P. [Princeton Plasma Physics Laboratory, Receiving 3, Route 1 North, Princeton, NJ 08543 (United States); Canik, J.M. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 (United States); Diallo, A.; Kaita, R.; Kaye, S.M.; Kugel, H.W.; LeBlanc, B.P. [Princeton Plasma Physics Laboratory, Receiving 3, Route 1 North, Princeton, NJ 08543 (United States); Sabbagh, S.A. [Applied Physics and Applied Math Dept., Columbia University, New York, NY 10027 (United States); Skinner, C.H. [Princeton Plasma Physics Laboratory, Receiving 3, Route 1 North, Princeton, NJ 08543 (United States); Soukhanovskii, V.A. [Lawrence Livermore National Laboratory, 7000 East Ave, PO Box 808, Livermore, CA 94551 (United States)

    2015-08-15

    In this paper, the effects of a pre-discharge lithium evaporation variation on highly shaped discharges in the National Spherical Torus Experiment (NSTX) are documented. Lithium wall conditioning (‘dose’) was routinely applied onto graphite plasma facing components between discharges in NSTX, partly to reduce recycling. Reduced D{sub α} emission from the lower and upper divertor and center stack was observed, as well as reduced midplane neutral pressure; the magnitude of reduction increased with the pre-discharge lithium dose. Improved energy confinement, both raw τ{sub E} and H-factor normalized to scalings, with increasing lithium dose was also observed. At the highest doses, we also observed elimination of edge-localized modes. The midplane edge plasma profiles were dramatically altered, comparable to lithium dose scans at lower shaping, where the strike point was farther from the lithium deposition centroid. This indicates that the benefits of lithium conditioning should apply to the highly shaped plasmas planned in NSTX-U.

  18. Linear calculations of edge current driven kink modes with BOUT++ code

    Energy Technology Data Exchange (ETDEWEB)

    Li, G. Q., E-mail: ligq@ipp.ac.cn; Xia, T. Y. [Institute of Plasma Physics, CAS, Hefei, Anhui 230031 (China); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Xu, X. Q. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Snyder, P. B.; Turnbull, A. D. [General Atomics, San Diego, California 92186 (United States); Ma, C. H.; Xi, P. W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); FSC, School of Physics, Peking University, Beijing 100871 (China)

    2014-10-15

    This work extends previous BOUT++ work to systematically study the impact of edge current density on edge localized modes, and to benchmark with the GATO and ELITE codes. Using the CORSICA code, a set of equilibria was generated with different edge current densities by keeping total current and pressure profile fixed. Based on these equilibria, the effects of the edge current density on the MHD instabilities were studied with the 3-field BOUT++ code. For the linear calculations, with increasing edge current density, the dominant modes are changed from intermediate-n and high-n ballooning modes to low-n kink modes, and the linear growth rate becomes smaller. The edge current provides stabilizing effects on ballooning modes due to the increase of local shear at the outer mid-plane with the edge current. For edge kink modes, however, the edge current does not always provide a destabilizing effect; with increasing edge current, the linear growth rate first increases, and then decreases. In benchmark calculations for BOUT++ against the linear results with the GATO and ELITE codes, the vacuum model has important effects on the edge kink mode calculations. By setting a realistic density profile and Spitzer resistivity profile in the vacuum region, the resistivity was found to have a destabilizing effect on both the kink mode and on the ballooning mode. With diamagnetic effects included, the intermediate-n and high-n ballooning modes can be totally stabilized for finite edge current density.

  19. Linear calculations of edge current driven kink modes with BOUT++ code

    International Nuclear Information System (INIS)

    Li, G. Q.; Xia, T. Y.; Xu, X. Q.; Snyder, P. B.; Turnbull, A. D.; Ma, C. H.; Xi, P. W.

    2014-01-01

    This work extends previous BOUT++ work to systematically study the impact of edge current density on edge localized modes, and to benchmark with the GATO and ELITE codes. Using the CORSICA code, a set of equilibria was generated with different edge current densities by keeping total current and pressure profile fixed. Based on these equilibria, the effects of the edge current density on the MHD instabilities were studied with the 3-field BOUT++ code. For the linear calculations, with increasing edge current density, the dominant modes are changed from intermediate-n and high-n ballooning modes to low-n kink modes, and the linear growth rate becomes smaller. The edge current provides stabilizing effects on ballooning modes due to the increase of local shear at the outer mid-plane with the edge current. For edge kink modes, however, the edge current does not always provide a destabilizing effect; with increasing edge current, the linear growth rate first increases, and then decreases. In benchmark calculations for BOUT++ against the linear results with the GATO and ELITE codes, the vacuum model has important effects on the edge kink mode calculations. By setting a realistic density profile and Spitzer resistivity profile in the vacuum region, the resistivity was found to have a destabilizing effect on both the kink mode and on the ballooning mode. With diamagnetic effects included, the intermediate-n and high-n ballooning modes can be totally stabilized for finite edge current density

  20. Confinement properties of JET plasmas with different temperature and density profiles

    International Nuclear Information System (INIS)

    Watkins, M.L.; Balet, B.; Bhatnagar, V.P.

    1989-01-01

    The confinement properties of plasmas with substantially different temperature and density profiles have been analysed. The effects of fast particles and energy pedestals on the overall confinement of plasma energy in limiter (L-mode) and X-point (L- and H-modes) discharges heated by NBI or ICRF or both are determined. The importance of the bootstrap current when such energy pedestals are formed is noted. Using sets of consistent experimental data, including ion temperature profile measurements, the local transport properties are compared in the L- and H-phases of a single null X-point medium density NBI heated discharge, the ''enhanced'' confinement phase of a limiter high density pellet-fuelled and ICRF heated discharge, the hot-ion phase of a double null X-point low density NBI heated discharge and the hot-ion and H-phases of a double null X-point low density high temperature NBI heated discharge. (author)

  1. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Congsen [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Department of Physics, National University of Defense Technology, Changsha 410073 (China); Janssen, Maurice H. M. [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

    2015-02-15

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the density profile of the molecular beam, and the measured absolute density is compared with theoretical calculations of the centre line beam density. Subsequently, we discuss reasons accounting for the differences between measurements and calculations and propose that strong skimmer interference is the most probable cause for the differences. Furthermore, we report on experiments measuring the centre line density of seeded supersonic beams. The femtosecond ion images show that seeding the heavy Xe atom at low relative seed fractions (1%-10%) in a light carrier gas like Ne results in strong relative enhancements of up to two orders of magnitude.

  2. Non-power law behavior of the radial profile of phase-space density of halos

    International Nuclear Information System (INIS)

    Popolo, A. Del

    2011-01-01

    We study the pseudo phase-space density, ρ(r)/σ 3 (r), of ΛCDM dark matter halos with and without baryons (baryons+DM, and pure DM), by using the model introduced in Del Popolo (2009), which takes into account the effect of dynamical friction, ordered and random angular momentum, baryons adiabatic contraction and dark matter baryons interplay. We examine the radial dependence of ρ(r)/σ 3 (r) over 9 orders of magnitude in radius for structures on galactic and cluster of galaxies scales. We find that ρ(r)/σ 3 (r) is approximately a power-law only in the range of halo radius resolved by current simulations (down to 0.1% of the virial radius) while it has a non-power law behavior below the quoted scale, with inner profiles changing with mass. The non-power-law behavior is more evident for halos constituted both of dark matter and baryons while halos constituted just of dark matter and with angular momentum chosen to reproduce a Navarro-Frenk-White (NFW) density profile, are characterized by an approximately power-law behavior. The results of the present paper lead to conclude that density profiles of the NFW type are compatible with a power-law behavior of ρ(r)/σ 3 (r), while those flattening to the halo center, like those found in Del Popolo (2009) or the Einasto profile, or the Burkert profile, cannot produce radial profile of the pseudo-phase-space density that are power-laws at all radii. The results argue against universality of the pseudo phase-space density and as a consequence argue against universality of density profiles constituted by dark matter and baryons as also discussed in Del Popolo (2009)

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

    International Nuclear Information System (INIS)

    Mlynek, Alexander

    2010-01-01

    The tokamak concept currently is the most promising approach to future power generation by controlled thermonuclear fusion. The spatial distribution of the particle density in the toroidally confined fusion plasma is of particular importance. This thesis work therefore focuses on the question as to what extent the shape of the density profile can be actively controlled by a feedback loop in the fusion experiment ASDEX Upgrade. There are basically two essential requirements for such feedback control of the density profile, which has been experimentally demonstrated within the scope of this thesis work: On the one hand, for this purpose the density profile must be continuously calculated under real-time constraints during a plasma discharge. The calculation of the density profile is based on the measurements of a sub-millimeter interferometer, which provides the line-integrated electron density along 5 chords through the plasma. Interferometric density measurements can suffer from counting errors by integer multiples of 2π when detecting the phase difference between a probing and a reference beam. As such measurement errors have severe impact on the reconstructed density profile, one major part of this work consists in the development of new readout electronics for the interferometer, which allows for detection of such measurement errors in real-time with high reliability. A further part of this work is the design of a computer algorithm which reconstructs the spatial distribution of the plasma density from the line-integrated measurements. This algorithm has to be implemented on a computer which communicates the measured data to other computers in real-time, especially to the tokamak control system. On the other hand, a second fundamental requirement for the successful implementation of a feedback controller is the identification of at least one actuator which enables a modification of the density profile. Here, electron cyclotron resonance heating (ECRH) has been

  4. Characterization of laser-produced plasma density profiles using grid image refractometry

    International Nuclear Information System (INIS)

    Craxton, R.S.; Turner, F.S.; Hoefen, R.; Darrow, C.; Gabl, E.F.; Busch, G.E.

    1993-01-01

    Grid image refractometry (GIR) is proposed as a technique for determining the two-dimensional density profiles of long scale-length laser-produced plasmas. Its distinctive feature is that an optical probe beam is broken up into ''rays'' by being passed through a grid before traversing the plasma. The refraction angles of the rays are measured by imaging the plasma at two or more object planes and are integrated to yield the phase front. For cylindrically symmetric plasmas the density profile is then determined using Abel inversion. The feasibility of GIR is illustrated by an experiment in which a thick CH target was irradiated with ∼100 J of 527 nm radiation and diagnosed with a 20 ps, 263 nm probe. The resulting density profile is substantially larger than any that have previously been reported using interferometry and compares quite closely with hydrodynamic simulations

  5. Density profile effects on confinement and MHD stability of currentless NBI plasmas in Heliotron E

    International Nuclear Information System (INIS)

    Sudo, Shigeru; Zushi, Hideki; Kondo, Katsumi

    1993-01-01

    Density profile effects on confinement and MHD stability of currentless NBI plasmas in Heliotron E are studied. The peaked density profile produced by pellet injection increases the stored energy by 20-30% compared to the gas puffed plasmas which obey the empirical stellarator/heliotron scaling in a moderate density range. In contrast to confinement, the peaked pressure profile tends to destabilize the plasma. By limiter insertion, MHD instability occurs (seems to locate near ι/2π=1) even in case of low β (β 0 ≤1%, where β 0 is the central β value) plasmas. On the other hand, the mode of m/n=3/2 at ι/2π=2/3, seems to be a key parameter to the major MHD instability in case of high β (β 0 ≥2%) plasmas. (author)

  6. ICRF power-deposition profiles, heating and confinement of monster sawtooth and peaked-density profile discharges in JET

    International Nuclear Information System (INIS)

    Bhatnagar, V.P.; Taroni, A.; Ellis, J.J.; Jacquinot, J.; Start, D.F.H.

    1989-01-01

    The ion cyclotron resonance heating of monster sawtooth (period greater than the energy confinement time) and pellet-fueled peaked-density profiles in limiter discharges of JET Tokamak are studied. The monster sawtooth is a characteristic JET regime which is related to fast ions generated during the minority ion heating. In the ICRF heating of peaked-density profile discharges, we find typically the T i0 is higher roughly by a factor of 2 and T e0 roughly by 35% at a fixed P TOT /n e0 when compared to non-peaked profile cases. Here, T e0 and T i0 are central electron and ion temperatures, respectively, n e0 is the central electron density and P TOT is the total input power. The ion heating is improved in the pellet case, in part, due to a higher collisionality between the background ions and the energetic minority, but more significantly by a reduction of local ion energy transport in the central region. The transport-code simulation of these discharges reveals that there is a reduction of both χ e and χ i in the central region of the plasma in the ICRF heated peaked-profile discharges where χ e and χ i are the electron and ion heat conductivities, respectively. The improvement of confinement is not explained quantitatively by any of the existing η i -driven turbulence theories as the n i parameter (η i = d ln T i /d ln n i where T i is the ion temperature and n i is the ion density), instead of dropping below the critical value, remains above it for most of the duration of the improved confinement phase. The physical mechanism(s) that plays a role in this improvement is not yet clear. (author)

  7. Avalanche consumption and the stationary regions of the density profile around the droplets in the theory of condensation

    OpenAIRE

    Kurasov, V.

    1998-01-01

    The contradiction between the stationary aproach to the density profile and the avalanche character of the metastable phase consumption is investigated. The exact solution for the metastable phase profile is obtained. The reconsidered value for the special parameter responsible for the hierarchy in the structure of the density profile around the droplet is presented.

  8. Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications of surface step edges

    Energy Technology Data Exchange (ETDEWEB)

    Killat, N., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk; Montes Bajo, M.; Kuball, M., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk [Center for Device Thermography and Reliability (CDTR), H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paskova, T. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Evans, K. R. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Leach, J. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Li, X.; Özgür, Ü.; Morkoç, H. [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Chabak, K. D.; Crespo, A.; Gillespie, J. K.; Fitch, R.; Kossler, M.; Walker, D. E.; Trejo, M.; Via, G. D.; Blevins, J. D. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

    2013-11-04

    To enable gaining insight into degradation mechanisms of AlGaN/GaN high electron mobility transistors, devices grown on a low-dislocation-density bulk-GaN substrate were studied. Gate leakage current and electroluminescence (EL) monitoring revealed a progressive appearance of EL spots during off-state stress which signify the generation of gate current leakage paths. Atomic force microscopy evidenced the formation of semiconductor surface pits at the failure location, which corresponds to the interaction region of the gate contact edge and the edges of surface steps.

  9. Simulating Ru L3-edge X-ray absorption spectroscopy with time-dependent density functional theory: model complexes and electron localization in mixed-valence metal dimers.

    Science.gov (United States)

    Van Kuiken, Benjamin E; Valiev, Marat; Daifuku, Stephanie L; Bannan, Caitlin; Strader, Matthew L; Cho, Hana; Huse, Nils; Schoenlein, Robert W; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of Ru(II) and Ru(III) complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6](4-) and Ru(II) polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5M(II)-CN-Ru(III)(NH3)5](-) (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  10. The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryons

    Science.gov (United States)

    Robertson, Andrew; Massey, Richard; Eke, Vincent; Tulin, Sean; Yu, Hai-Bo; Bahé, Yannick; Barnes, David J.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop

    2018-05-01

    We present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in terms of their different final baryon distributions.

  11. A Numerical Fit of Analytical to Simulated Density Profiles in Dark Matter Haloes

    Science.gov (United States)

    Caimmi, R.; Marmo, C.; Valentinuzzi, T.

    2005-06-01

    Analytical and geometrical properties of generalized power-law (GPL) density profiles are investigated in detail. In particular, a one-to-one correspondence is found between mathematical parameters (a scaling radius, r_0, a scaling density, rho_0, and three exponents, alpha, beta, gamma), and geometrical parameters (the coordinates of the intersection of the asymptotes, x_C, y_C, and three vertical intercepts, b, b_beta, b_gamma, related to the curve and the asymptotes, respectively): (r_0,rho_0,alpha,beta,gamma) (x_C,y_C,b,b_beta,b_gamma). Then GPL density profiles are compared with simulated dark haloes (SDH) density profiles, and nonlinear least-absolute values and least-squares fits involving the above mentioned five parameters (RFSM5 method) are prescribed. More specifically, the sum of absolute values or squares of absolute logarithmic residuals, R_i= log rhoSDH(r_i)-log rhoGPL(r_i), is evaluated on 10^5 points making a 5- dimension hypergrid, through a few iterations. The size is progressively reduced around a fiducial minimum, and superpositions on nodes of earlier hypergrids are avoided. An application is made to a sample of 17 SDHs on the scale of cluster of galaxies, within a flat LambdaCDM cosmological model (Rasia et al. 2004). In dealing with the mean SDH density profile, a virial radius, rvir, averaged over the whole sample, is assigned, which allows the calculation of the remaining parameters. Using a RFSM5 method provides a better fit with respect to other methods. The geometrical parameters, averaged over the whole sample of best fitting GPL density profiles, yield (alpha,beta,gamma) approx(0.6,3.1,1.0), to be compared with (alpha,beta,gamma)=(1,3,1), i.e. the NFW density profile (Navarro et al. 1995, 1996, 1997), (alpha,beta,gamma)=(1.5,3,1.5) (Moore et al. 1998, 1999), (alpha,beta,gamma)=(1,2.5,1) (Rasia et al. 2004); and, in addition, gamma approx 1.5 (Hiotelis 2003), deduced from the application of a RFSM5 method, but using a different

  12. Influence of an axial magnetic field on the density profile of capillary plasma channels

    CERN Document Server

    Ivanov, V V; Toma, E S; Bijkerk, F

    2003-01-01

    A narrow capillary plasma channel, with a sizeable depletion of the electron density on the channel axis, has been proposed to guide a laser pulse over a length of several to several tens of centimetres. We discuss the possibility to significantly improve the wave-guiding properties of such a channel by applying an axial magnetic field. Our analytical and numerical studies show that a pulsed axial magnetic field of 10 T in a hydrogen capillary plasma at a pressure of 50 Torr will reduce the on-axis plasma density by a factor of three, and the full width at half maximum of the density profile by a factor of two. The resulting parabolic plasma density profile is expected to be more efficient in guiding laser pulses.

  13. Properties of ion temperature gradient and trapped electron modes in tokamak plasmas with inverted density profiles

    Science.gov (United States)

    Du, Huarong; Jhang, Hogun; Hahm, T. S.; Dong, J. Q.; Wang, Z. X.

    2017-12-01

    We perform a numerical study of linear stability of the ion temperature gradient (ITG) mode and the trapped electron mode (TEM) in tokamak plasmas with inverted density profiles. A local gyrokinetic integral equation is applied for this study. From comprehensive parametric scans, we obtain stability diagrams for ITG modes and TEMs in terms of density and temperature gradient scale lengths. The results show that, for the inverted density profile, there exists a normalized threshold temperature gradient above which the ITG mode and the TEM are either separately or simultaneously unstable. The instability threshold of the TEM for the inverted density profile is substantially different from that for normal and flat density profiles. In addition, deviations are found on the ITG threshold from an early analytic theory in sheared slab geometry with the adiabatic electron response [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. A possible implication of this work on particle transport in pellet fueled tokamak plasmas is discussed.

  14. Real-time evaluation of electron and current density profile parameters on TEXTOR

    International Nuclear Information System (INIS)

    Bruessau, W.D.; Soltwisch, H.

    1985-08-01

    The shapes of electron and current density profiles are monitored in real-time mode in order to get rapid qualitative information on the development of a TEXTOR tokamak plasma. The profiles are described by form parameters which relate to the signals of a 9-channel FIR-polari/interferometer in simple mathematical formulae. These profile parameters are obtained by real-time conversion of measured quantities for display on a storage oscilloscope or on a chart recorder. The application of the parameters is demonstrated in some examples. (orig.)

  15. Fast electron current density profile and diffusion studies during LHCD in PBX-M

    International Nuclear Information System (INIS)

    Jones, S.E.; Kesner, J.; Luckhardt, S.; Paoletti, F.

    1993-08-01

    Successful current profile control experiments using lower hybrid current drive (LCHD) clearly require knowledge of (1) the location of the driven fast electrons and (2) the ability to maintain that location from spreading due to radial diffusion. These issues can be addressed by examining the data from the hard x-ray camera on PBX-M, a unique diagnostic producing two-dimensional, time resolved tangential images of fast electron bremsstrahlung. Using modeling, these line-of-sight images are inverted to extract a radial fast electron current density profile. We note that ''hollow'' profiles have been observed, indicative of off-axis current drive. These profiles can then be used to calculate an upper bound for an effective fast electron diffusion constant: assuming an extremely radially narrow lower hybrid absorption profile and a transport model based on Rax and Moreau, a model fast electron current density profile is calculated and compared to the experimentally derived profile. The model diffusion constant is adjusted until a good match is found. Applied to steady-state quiescent modes on PBX-M, we obtain an upper limit for an effective diffusion constant of about D*=1.1 m 2 /sec

  16. Probing ultrafast changes of spin and charge density profiles with resonant XUV magnetic reflectivity at the free-electron laser FERMI.

    Science.gov (United States)

    Gutt, C; Sant, T; Ksenzov, D; Capotondi, F; Pedersoli, E; Raimondi, L; Nikolov, I P; Kiskinova, M; Jaiswal, S; Jakob, G; Kläui, M; Zabel, H; Pietsch, U

    2017-09-01

    We report the results of resonant magnetic XUV reflectivity experiments performed at the XUV free-electron laser FERMI. Circularly polarized XUV light with the photon energy tuned to the Fe M 2,3 edge is used to measure resonant magnetic reflectivities and the corresponding Q -resolved asymmetry of a Permalloy/Ta/Permalloy trilayer film. The asymmetry exhibits ultrafast changes on 240 fs time scales upon pumping with ultrashort IR laser pulses. Depending on the value of the wavevector transfer Q z , we observe both decreasing and increasing values of the asymmetry parameter, which is attributed to ultrafast changes in the vertical spin and charge density profiles of the trilayer film.

  17. Modification of strain and 2DEG density induced by wafer bending of AlGaN/GaN heterostructure: Influence of edges caused by processing

    Directory of Open Access Journals (Sweden)

    Ashu Wang

    2018-03-01

    Full Text Available Due to the piezoelectricity, the density of 2DEG (NS formed in the AlGaN/GaN heterostructure can be altered when it is deformed externally, which may be exploited to develop pressure sensors and to enhance the performance of power devices by stress engineering based on the heterostructure. In this paper, a 3D electro-mechanical simulation is presented to study how the induced strains and NS for the AlGaN/GaN wafer under bending exerted uniaxial stress are influenced by the edges caused by processing: the fabrication of the mesa used for isolation, the ohmic contact metal, the gate metal, and the passivation. Results show that the influences are dependent on distance between the edges, depth of the edges, and direction of the exerted uniaxial stress.

  18. On the contact values of the density profiles in an electric double layer using density functional theory

    Directory of Open Access Journals (Sweden)

    L.B. Bhuiyan

    2012-06-01

    Full Text Available A recently proposed, local second contact value theorem [Henderson D., Boda D., J. Electroanal. Chem., 2005, Vol. 582, 16] for the charge profile of an electric double layer is used in conjunction with existing Monte Carlo data from the literature to assess the contact behavior of the electrode-ion distributions predicted by the density functional theory. The results for the contact values of the co- and counterion distributions and their product are obtained for the symmetric valency, restricted primitive model planar double layer for a range of electrolyte concentrations and temperatures. Overall the theoretical results satisfy the second contact value theorem reasonably well the agreement with the simulations being semi-quantitative or better. The product of the co- and counterion contact values as a function of the electrode surface charge density is qualitative with the simulations with increasing deviations at higher concentrations.

  19. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    NARCIS (Netherlands)

    Meng, C.; Janssen, M.H.M.

    2015-01-01

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the

  20. Experimental profile evolution of a high-density field-reversed configuration

    International Nuclear Information System (INIS)

    Ruden, E. L.; Zhang, Shouyin; Intrator, T. P.; Wurden, G. A.

    2006-01-01

    A field-reversed configuration (FRC) gains angular momentum over time, eventually resulting in an n=2 rotational instability (invariant under rotation by π) terminating confinement. To study this, a laser interferometer probes the time history of line integrated plasma density along eight chords of the high-density (∼10 17 cm -3 ) field-reversed configuration experiment with a liner. Abel and tomographic inversions provide density profiles during the FRC's azimuthally symmetric phase, and over a period when the rotational mode has saturated and rotates with a roughly fixed profile, respectively. During the latter part of the symmetric phase, the FRC approximates a magnetohydrodynamic (MHD) equilibrium, allowing the axial magnetic-field profile to be calculated from pressure balance. Basic FRC properties such as temperature and poloidal flux are then inferred. The subsequent two-dimensional n=2 density profiles provide angular momentum information needed to set bounds on prior values of the stability relevant parameter α (rotational to ion diamagnetic drift frequency ratio), in addition to a view of plasma kinematics useful for benchmarking plasma models of higher order than MHD

  1. Magnetically filtered Faraday probe for measuring the ion current density profile of a Hall thruster

    International Nuclear Information System (INIS)

    Rovey, Joshua L.; Walker, Mitchell L.R.; Gallimore, Alec D.; Peterson, Peter Y.

    2006-01-01

    The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magnetic field as an ion filter. In this study, a MFFP, Faraday probe with a reduced acceptance angle (BFP), and nude Faraday probe are used to measure the ion current density profile of a 5 kW Hall thruster operating over the range of 300-500 V and 5-10 mg/s. The probes are evaluated on a xenon propellant Hall thruster in the University of Michigan Large Vacuum Test Facility at operating pressures within the range of 4.4x10 -4 Pa Xe (3.3x10 -6 Torr Xe) to 1.1x10 -3 Pa Xe (8.4x10 -6 Torr Xe) in order to study the ability of the Faraday probe designs to filter out CEX ions. Detailed examination of the results shows that the nude probe measures a greater ion current density profile than both the MFFP and BFP over the range of angular positions investigated for each operating condition. The differences between the current density profiles obtained by each probe are attributed to the ion filtering systems employed. Analysis of the results shows that the MFFP, operating at a +5 A solenoid current, provides the best agreement with flight-test data and across operating pressures

  2. Affinity proteomic profiling of plasma for proteins associated to area-based mammographic breast density.

    Science.gov (United States)

    Byström, Sanna; Eklund, Martin; Hong, Mun-Gwan; Fredolini, Claudia; Eriksson, Mikael; Czene, Kamila; Hall, Per; Schwenk, Jochen M; Gabrielson, Marike

    2018-02-14

    Mammographic breast density is one of the strongest risk factors for breast cancer, but molecular understanding of how breast density relates to cancer risk is less complete. Studies of proteins in blood plasma, possibly associated with mammographic density, are well-suited as these allow large-scale analyses and might shed light on the association between breast cancer and breast density. Plasma samples from 1329 women in the Swedish KARMA project, without prior history of breast cancer, were profiled with antibody suspension bead array (SBA) assays. Two sample sets comprising 729 and 600 women were screened by two different SBAs targeting a total number of 357 proteins. Protein targets were selected through searching the literature, for either being related to breast cancer or for being linked to the extracellular matrix. Association between proteins and absolute area-based breast density (AD) was assessed by quantile regression, adjusting for age and body mass index (BMI). Plasma profiling revealed linear association between 20 proteins and AD, concordant in the two sets of samples (p density and processes of tissue homeostasis, DNA repair, cancer development and/or progression in breast cancer. Further validation and follow-up studies of the shortlisted protein candidates in independent cohorts will be needed to infer their role in breast density and its progression in premenopausal and postmenopausal women.

  3. Mars Global Surveyor Radio Science Electron Density Profiles: Interannual Variability and Implications for the Neutral Atmosphere

    Science.gov (United States)

    Bougher, S. W.; Engel, S.; Hinson, D. P.; Murphy, J. R.

    2003-01-01

    The Mars Global Surveyor (MGS) Radio Science (RS) experiment employs an ultrastable oscillator aboard the spacecraft. The signal from the oscillator to Earth is refracted by the Martian ionosphere, allowing retrieval of electron density profiles versus radius and geopotential. The present analysis is carried out on five sets of occultation measurements: (1) four obtained near northern summer solstice (Ls = 74-116, near aphelion) at high northern latitudes (64.7-77.6N), and (2) one set of profiles approaching equinox conditions (Ls = 135- 146) at high southern latitudes (64.7-69.1S). Electron density profiles (95 to 200 km) are examined over a narrow range of solar zenith angles (76.5-86.9 degrees) for local true solar times of (1) 3-4 hours and (2) 12.1 hours. Variations spanning 1-Martian year are specifically examined in the Northern hemisphere.

  4. Comparison of the observed results of the electron density profiles with the IRI90

    International Nuclear Information System (INIS)

    Zhang Manlian; Radicella, S.M.; Dai Kailiang

    1996-01-01

    The daily and composite profiles and the thickness parameter of the electron density profiles are compared with the results of IRI90 for the stations of Ramey (15.8 deg. N, 292.9 deg. E), Wuchang (30.6 deg. N, 114.3 deg. E), Chongqing (29.5 deg. N, 106.4 deg. E) and Wrumchi (43.8 deg. N, 87.6 deg. E). It is found that the electron density profiles produced by IRI90, both with the old Standard B0 and the new Gulyaeva-B0 thickness parameter, are too thick below F2-peak compared with the observed results. It is also shown that the IRI90 results show a very poor agreement with the observed results for the intermediate (F1) layer of the ionosphere. (author). 1 ref., 4 figs,

  5. Electron density profile measurements from hydrogen line intensity ratio method in Versatile Experimental Spherical Torus

    Energy Technology Data Exchange (ETDEWEB)

    Kim, YooSung; Shi, Yue-Jiang, E-mail: yjshi@snu.ac.kr; Yang, Jeong-hun; Kim, SeongCheol; Kim, Young-Gi; Dang, Jeong-Jeung; Yang, Seongmoo; Jo, Jungmin; Chung, Kyoung-Jae [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Oh, Soo-Ghee [Division of Energy Systems Research, Ajou University, Suwon 442-749 (Korea, Republic of); Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Center for Advanced Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2016-11-15

    Electron density profiles of versatile experiment spherical torus plasmas are measured by using a hydrogen line intensity ratio method. A fast-frame visible camera with appropriate bandpass filters is used to detect images of Balmer line intensities. The unique optical system makes it possible to take images of H{sub α} and H{sub β} radiation simultaneously, with only one camera. The frame rate is 1000 fps and the spatial resolution of the system is about 0.5 cm. One-dimensional local emissivity profiles have been obtained from the toroidal line of sight with viewing dumps. An initial result for the electron density profile is presented and is in reasonable agreement with values measured by a triple Langmuir probe.

  6. Measurements of density profile evolution during the stably-stratified filling of an open enclosure

    International Nuclear Information System (INIS)

    Tarawneh, Constantine M.; Homan, K.O.

    2008-01-01

    The stably-stratified filling of an open enclosure produces an interfacial gradient layer which is transported through the enclosure with the bulk flow. The evolution of this interfacial layer is strongly time-dependent and is driven by the nature of the interaction between the internal gravity waves and the inlet-driven interfacial shear. Measurements of density profile evolution have been completed for a rectangular enclosure with a single corner inlet and density variation produced by saline concentration. This system serves as a mass transfer analog to large-scale, thermally-stratified energy storage devices, preserving dynamic similitude in a laboratory-scale system. The experiments covered jet Reynolds numbers of 200-2200 and Froude numbers of 0.06-0.6 in an enclosure with a width 23 times the jet inlet height. The density profiles are seen to be strongly asymmetric and exhibit growth rates significantly different than due to simple one-dimensional molecular diffusion. In addition, shadowgraph and hydrogen bubble visualizations of the density and velocity fields in the gradient layer show the persistence of complex multi-dimensional flow structure even at relatively late stages of the filling process when the gradient layer has been transported well away from the enclosure inlet. The evolution of the vertical density profile has been compared quantitatively to a quasi one-dimensional model based upon empirical diffusivity coefficients

  7. A thermodynamic perturbation theory for the surface tension and ion density profile of a liquid metal

    International Nuclear Information System (INIS)

    Evans, R.; Kumaravadivel, R.

    1976-01-01

    A simple scheme for determining the ion density profile and the surface tension of a liquid metal is described. Assuming that the interaction between metallic pseudo-ions is of the form introduced by Evans, an approximate expression for the excess free energy of the system is derived using the thermodynamic perturbation theory of Weeks, Chandler and Anderson. This excess free energy is then minimized with respect to a parameter which specifies the ion density profile, and the surface tension is given directly. From a consideration of the dependence of the interionic forces on the electron density it is predicted that the ions should take up a very steep density profile at the liquid metal surface. This behaviour is contrasted with that to be expected for rare-gas fluids in which the interatomic forces are density-independent. The values of the surface tension calculated for liquid Na, K and Al from a simplified version of the theory are in reasonable agreement with experiment. (author)

  8. Analysis of Total Electron Content and Electron Density Profile during Different Geomagnetic Storms

    Science.gov (United States)

    Chapagain, N. P.; Rana, B.; Adhikari, B.

    2017-12-01

    Total Electron content (TEC) and electron density are the key parameters in the mitigation of ionospheric effects on radio communication system. Detail study of the TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (13˚N -17˚N, 88˚E -98˚E), (30˚N-50˚N, 120˚W -95˚W), (29˚S-26˚S, 167˚W-163˚W,) and (60˚S-45˚S, 120˚W-105˚W) using the Gravity Recovery and Climate Experiment (GRACE) satellite observations. In order to find the geomagnetic activity, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma drift velocity (Vsw), flow pressure (nPa), AE, Dst and Kp indices were obtained from Operating Mission as Nodes on the Internet (OMNI) web system. The data for geomagnetic indices have been correlated with the TEC and electron density for four different events of geomagnetic storms on 6 April 2008, 27 March 2008, 4 September 2008, and 11 October 2008. The result illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar activities. The peak values of electron density and TEC increase as the geomagnetic storms become stronger. Similarly, the electron density profile varies with altitudes, which peaks around the altitude range of about 250- 350 km, depending on the strength of geomagnetic storms. The results clearly show that the peak electron density shifted to higher altitude (from about 250 km to 350 km) as the geomagnetic disturbances becomes stronger.

  9. Interaction of the modulated electron beam with inhomogeneous plasma: plasma density profile deformation and langmuir waves excitation

    International Nuclear Information System (INIS)

    Anisimov, I.O.; Kelnyk, O.I.; Soroka, S.V.; Siversky, T.V.

    2005-01-01

    Nonlinear deformation of the initially linear plasma density profile due to the modulated electron beam is studied via computer simulation. In the initial time period the field slaves to the instantaneous profile of the plasma density. Langmuir waves excitation is suppressed by the density profile deformation. The character of the plasma density profile deformation for the late time period depends significantly on the plasma properties. Particularly, for plasma with hot electrons quasi-periodic generation of ion-acoustic pulses takes place in the vicinity of the initial point of plasma resonance

  10. Ion acceleration in electrostatic collisionless shock: on the optimal density profile for quasi-monoenergetic beams

    Science.gov (United States)

    Boella, E.; Fiúza, F.; Stockem Novo, A.; Fonseca, R.; Silva, L. O.

    2018-03-01

    A numerical study on ion acceleration in electrostatic shock waves is presented, with the aim of determining the best plasma configuration to achieve quasi-monoenergetic ion beams in laser-driven systems. It was recently shown that tailored near-critical density plasmas characterized by a long-scale decreasing rear density profile lead to beams with low energy spread (Fiúza et al 2012 Phys. Rev. Lett. 109 215001). In this work, a detailed parameter scan investigating different plasma scale lengths is carried out. As result, the optimal plasma spatial scale length that allows for minimizing the energy spread while ensuring a significant reflection of ions by the shock is identified. Furthermore, a new configuration where the required profile has been obtained by coupling micro layers of different densities is proposed. Results show that this new engineered approach is a valid alternative, guaranteeing a low energy spread with a higher level of controllability.

  11. Astigmatism-free high-brightness 1060 nm edge-emitting lasers with narrow circular beam profile.

    Science.gov (United States)

    Miah, Md Jarez; Kalosha, Vladimir P; Bimberg, Dieter; Pohl, Johannes; Weyers, Markus

    2016-12-26

    1060 nm high-brightness vertical broad-area edge-emitting lasers providing anastigmatic high optical power into a narrow circular beam profile are demonstrated. Ridge-waveguide (RW) lasers yield record 2.2 W single-transverse mode power in the 1060-nm wavelength range under continuous-wave (cw) operation at room temperature with excellent beam quality factor M2 ≤ 2. Independent of operating current the astigmatism is only 2.5 µm. 3 mm long broad-area (BA) lasers produce a θvert as narrow as 9° full width at half maximum, which agrees well with our simulation results, being insensitive to drive current. 5 mm long BA lasers deliver highest ever reported cw 12 W multimode output power among lasers showing θvert <10° in the 1060-nm wavelength range. The emitted laser beams from both RW and BA lasers show a perfect circular shape with ≤10° divergence angle at record 2.1 W and 4.2 W cw-mode output power, respectively.

  12. Topside electron density: comparison of experimental and IRI model profiles during low solar activity period

    International Nuclear Information System (INIS)

    Alazo, K.; Coisson, P.; Radicella, S.M.

    2003-01-01

    The pattern of the topside electron density profiles is not yet very well represented by the IRI model. In this work the topside profiles obtained by the ISIS-2 satellite during low solar activity conditions are compared to those modeled by IRI. We take the quantitative parameter ε to measure the deviation of the model from the observed profiles. The results showed that the IRI overestimation of the topside profile is higher for low dip latitudes. The dispersion of the epsilon values is from 40 to 140%, more in equinoctial months and some lower for Winter. The best modeling is about 20% to 40% in middle and high latitudes of the North Hemisphere. (author)

  13. The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks

    International Nuclear Information System (INIS)

    Kleva, Robert G.; Guzdar, Parvez N.

    2009-01-01

    Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.

  14. Dark matter and gas density profiles - a consequence of entropy bifurcation

    International Nuclear Information System (INIS)

    Leubner, M. P.

    2006-01-01

    The radial profiles of dark matter and hot plasma density distributions of relaxed galaxies and clusters were hitherto commonly fitted by empirical functions. On the other hand, the fundamental concept of non-extensive statistics accounts for long-range interactions and correlations present in gravitationally coupled ensembles and plasmas. We provide a theoretical link of non-extensive statistics to large scale astrophysical structures and show that the underlying tandem character of the entropy results in a bifurcation of the density distribution. A kinetic dark matter and thermodynamic gas branch turn out as natural consequence within the theory and is controlled by one single parameter, measuring physically the degree of correlations in the system. The theoretically derived density profiles are shown to represent accurately the characteristics of both, DM and hot plasma distributions, as observed or generated in N-body and hydro-simulations. The significant advantage over empirical fitting functions is provided by the physical content of the non-extensive approach wherefore it is proposed to model observed density profiles of astrophysical structures within the fundamental context of entropy generalization, accounting for nonlocality and long-range interactions in gravitationally coupled systems

  15. A two-dimensional regularization algorithm for density profile evaluation from broadband reflectometry

    International Nuclear Information System (INIS)

    Nunes, F.; Varela, P.; Silva, A.; Manso, M.; Santos, J.; Nunes, I.; Serra, F.; Kurzan, B.; Suttrop, W.

    1997-01-01

    Broadband reflectometry is a current technique that uses the round-trip group delays of reflected frequency-swept waves to measure density profiles of fusion plasmas. The main factor that may limit the accuracy of the reconstructed profiles is the interference of the probing waves with the plasma density fluctuations: plasma turbulence leads to random phase variations and magneto hydrodynamic activity produces mainly strong amplitude and phase modulations. Both effects cause the decrease, and eventually loss, of signal at some frequencies. Several data processing techniques can be applied to filter and/or interpolate noisy group delay data obtained from turbulent plasmas with a single frequency sweep. Here, we propose a more powerful algorithm performing two-dimensional regularization (in space and time) of data provided by multiple consecutive frequency sweeps, which leads to density profiles with improved accuracy. The new method is described and its application to simulated data corrupted by noise and missing data is considered. It is shown that the algorithm improves the identification of slowly varying plasma density perturbations by attenuating the effect of fast fluctuations and noise contained in experimental data. First results obtained with this method in ASDEX Upgrade tokamak are presented. copyright 1997 American Institute of Physics

  16. Quantum Hall states of atomic Bose gases: Density profiles in single-layer and multilayer geometries

    International Nuclear Information System (INIS)

    Cooper, N. R.; Lankvelt, F. J. M. van; Reijnders, J. W.; Schoutens, K.

    2005-01-01

    We describe the density profiles of confined atomic Bose gases in the high-rotation limit, in single-layer and multilayer geometries. We show that, in a local-density approximation, the density in a single layer shows a landscape of quantized steps due to the formation of incompressible liquids, which are analogous to fractional quantum Hall liquids for a two-dimensional electron gas in a strong magnetic field. In a multilayered setup we find different phases, depending on the strength of the interlayer tunneling t. We discuss the situation where a vortex lattice in the three-dimensional condensate (at large tunneling) undergoes quantum melting at a critical tunneling t c 1 . For tunneling well below t c 1 one expects weakly coupled or isolated layers, each exhibiting a landscape of quantum Hall liquids. After expansion, this gives a radial density distribution with characteristic features (cusps) that provide experimental signatures of the quantum Hall liquids

  17. Dwarf galaxy dark matter density profiles inferred from stellar and gas kinematics

    International Nuclear Information System (INIS)

    Adams, Joshua J.; Simon, Joshua D.; Fabricius, Maximilian H.; Bender, Ralf; Thomas, Jens; Van den Bosch, Remco C. E.; Van de Ven, Glenn; Barentine, John C.; Gebhardt, Karl; Hill, Gary J.; Murphy, Jeremy D.; Swaters, R. A.

    2014-01-01

    We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low-mass galaxies frequently suggest that they contain constant density DM cores, while N-body simulations instead predict a cuspy profile. We present a data set of high-resolution integral-field spectroscopy on seven galaxies and measure the stellar and gas kinematics simultaneously. Using Jeans modeling on our full sample, we examine whether gas kinematics in general produce shallower density profiles than are derived from the stars. Although two of the seven galaxies show some localized differences in their rotation curves between the two tracers, estimates of the central logarithmic slope of the DM density profile, γ, are generally robust. The mean and standard deviation of the logarithmic slope for the population are γ = 0.67 ± 0.10 when measured in the stars and γ = 0.58 ± 0.24 when measured in the gas. We also find that the halos are not under-concentrated at the radii of half their maximum velocities. Finally, we search for correlations of the DM density profile with stellar velocity anisotropy and other baryonic properties. Two popular mechanisms to explain cored DM halos are an exotic DM component or feedback models that strongly couple the energy of supernovae into repeatedly driving out gas and dynamically heating the DM halos. While such models do not yet have falsifiable predictions that we can measure, we investigate correlations that may eventually be used to test models. We do not find a secondary parameter that strongly correlates with the central DM density slope, but we do find some weak correlations. The central DM density slope weakly correlates with the abundance of α elements in the stellar population, anti-correlates with H I fraction, and anti-correlates with vertical orbital anisotropy. We expect, if anything, the opposite of these

  18. Direct imaging of band profile in single layer MoS2 on graphite: quasiparticle energy gap, metallic edge states, and edge band bending.

    Science.gov (United States)

    Zhang, Chendong; Johnson, Amber; Hsu, Chang-Lung; Li, Lain-Jong; Shih, Chih-Kang

    2014-05-14

    Using scanning tunneling microscopy and spectroscopy, we probe the electronic structures of single layer MoS2 on graphite. The apparent quasiparticle energy gap of single layer MoS2 is measured to be 2.15 ± 0.06 eV at 77 K, albeit a higher second conduction band threshold at 0.2 eV above the apparent conduction band minimum is also observed. Combining it with photoluminescence studies, we deduce an exciton binding energy of 0.22 ± 0.1 eV (or 0.42 eV if the second threshold is use), a value that is lower than current theoretical predictions. Consistent with theoretical predictions, we directly observe metallic edge states of single layer MoS2. In the bulk region of MoS2, the Fermi level is located at 1.8 eV above the valence band maximum, possibly due to the formation of a graphite/MoS2 heterojunction. At the edge, however, we observe an upward band bending of 0.6 eV within a short depletion length of about 5 nm, analogous to the phenomena of Fermi level pinning of a 3D semiconductor by metallic surface states.

  19. Density limits in Tokamaks

    International Nuclear Information System (INIS)

    Tendler, M.

    1984-06-01

    The energy loss from a tokamak plasma due to neutral hydrogen radiation and recycling is of great importance for the energy balance at the periphery. It is shown that the requirement for thermal equilibrium implies a constraint on the maximum attainable edge density. The relation to other density limits is discussed. The average plasma density is shown to be a strong function of the refuelling deposition profile. (author)

  20. Measuring Density Profiles of Electrons and Heavy Particles in a Stable Axially Blown Arc

    Science.gov (United States)

    Carstensen, J.; Stoller, P.; Galletti, B.; Doiron, C. B.; Sokolov, A.

    2017-08-01

    Two-color spatial carrier wave interferometry employing pulsed 532- and 671-nm lasers is used to measure the electron-density and heavy-particle-density profiles in the stagnation point of a stable, axially blown arc in argon for currents of 50 to 200 A and stagnation point pressures of 0.2 to 16 bar. This technique takes advantage of the fact that the free-electron contribution to the refractive index depends strongly on the wavelength, while that of the heavy particles does not. The high spatial resolution achieved allows the hot core of the arc to be readily distinguished from the surrounding boundary layer. A custom-built test device is used to ensure flow conditions that lead to a stable, axisymmetric arc; this permits the reconstruction of the density and temperature profiles using a single projection (interferometric image) of the refractive-index distribution through the arc (at two wavelengths). The arc radius determined from the heavy-particle density decreases with increasing stagnation pressure and increases with the current. These measurements are in good agreement with a simple axially blown arc model taking into account Ohmic heating, radiation losses, and enthalpy flow for core temperatures of approximately 16 500 K. The measured electron density at the center of the arc agrees well with a prediction based on local thermodynamic equilibrium.

  1. Comments on ''theory of dissipative density-gradient-driven turbulence in the tokamak edge'' [Phys. Fluids 28, 1419 (1985)

    International Nuclear Information System (INIS)

    Krommes, J.A.

    1985-11-01

    The author critiques the model of tokamak edge turbulence by P.W. Terry and P.H. Diamond (Phys. Fluids 28, 1419, 1985). The critique includes a discussion of the physical basis, consistency and quantitative accuracy of the Terry-Diamond model. 19 refs

  2. Analytical solution for the mode conversion equations with steep exponential density profiles

    International Nuclear Information System (INIS)

    Alava, M.J.; Heikkinen, J.A.

    1992-01-01

    A general analytical solution for the converted power from the fast magnetosonic wave to an ion Bernstein wave in a magnetized plasma with an exponential steeply increasing density profile is given in the closed form. The solution covers both the conversion at the lower-hybrid resonance and the conversion through the density gradient for small parallel wave numbers. As an application, the conversion coefficients at the scrape-off layer plasma are estimated in the context of ion cyclotron heating of a tokamak plasma

  3. Electron density profile reconstruction by maximum entropy method with multichannel HCN laser interferometer system on SPAC VII

    International Nuclear Information System (INIS)

    Kubo, S.; Narihara, K.; Tomita, Y.; Hasegawa, M.; Tsuzuki, T.; Mohri, A.

    1988-01-01

    A multichannel HCN laser interferometer system has been developed to investigate the plasma electron confinement properties in SPAC VII device. Maximum entropy method is applied to reconstruct the electron density profile from measured line integrated data. Particle diffusion coefficient in the peripheral region of the REB ring core spherator was obtained from the evolution of the density profile. (author)

  4. Modeling L2,3-Edge X-ray Absorption Spectroscopy with Real-Time Exact Two-Component Relativistic Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Kasper, Joseph M; Lestrange, Patrick J; Stetina, Torin F; Li, Xiaosong

    2018-04-10

    X-ray absorption spectroscopy is a powerful technique to probe local electronic and nuclear structure. There has been extensive theoretical work modeling K-edge spectra from first principles. However, modeling L-edge spectra directly with density functional theory poses a unique challenge requiring further study. Spin-orbit coupling must be included in the model, and a noncollinear density functional theory is required. Using the real-time exact two-component method, we are able to variationally include one-electron spin-orbit coupling terms when calculating the absorption spectrum. The abilities of different basis sets and density functionals to model spectra for both closed- and open-shell systems are investigated using SiCl 4 and three transition metal complexes, TiCl 4 , CrO 2 Cl 2 , and [FeCl 6 ] 3- . Although we are working in the real-time framework, individual molecular orbital transitions can still be recovered by projecting the density onto the ground state molecular orbital space and separating contributions to the time evolving dipole moment.

  5. Reconstruction and analysis of temperature and density spatial profiles inertial confinement fusion implosion cores

    International Nuclear Information System (INIS)

    Mancini, R. C.

    2007-01-01

    We discuss several methods for the extraction of temperature and density spatial profiles in inertial confinement fusion implosion cores based on the analysis of the x-ray emission from spectroscopic tracers added to the deuterium fuel. The ideas rely on (1) detailed spectral models that take into account collisional-radiative atomic kinetics, Stark broadened line shapes, and radiation transport calculations, (2) the availability of narrow-band, gated pinhole and slit x-ray images, and space-resolved line spectra of the core, and (3) several data analysis and reconstruction methods that include a multi-objective search and optimization technique based on a novel application of Pareto genetic algorithms to plasma spectroscopy. The spectroscopic analysis yields the spatial profiles of temperature and density in the core at the collapse of the implosion, and also the extent of shell material mixing into the core. Results are illustrated with data recorded in implosion experiments driven by the OMEGA and Z facilities

  6. Electron momentum density and Compton profile by a semi-empirical approach

    Science.gov (United States)

    Aguiar, Julio C.; Mitnik, Darío; Di Rocco, Héctor O.

    2015-08-01

    Here we propose a semi-empirical approach to describe with good accuracy the electron momentum densities and Compton profiles for a wide range of pure crystalline metals. In the present approach, we use an experimental Compton profile to fit an analytical expression for the momentum densities of the valence electrons. This expression is similar to a Fermi-Dirac distribution function with two parameters, one of which coincides with the ground state kinetic energy of the free-electron gas and the other resembles the electron-electron interaction energy. In the proposed scheme conduction electrons are neither completely free nor completely bound to the atomic nucleus. This procedure allows us to include correlation effects. We tested the approach for all metals with Z=3-50 and showed the results for three representative elements: Li, Be and Al from high-resolution experiments.

  7. Method of measuring a profile of the density of charged particles in a particle beam

    International Nuclear Information System (INIS)

    Hyman, L.G.; Jankowski, D.J.

    1975-01-01

    A profile of the relative density of charged particles in a beam is obtained by disposing a number of rods parallel to each other in a plane perpendicular to the beam and shadowing the beam. A second number of rods is disposed perpendicular to the first rods in a plane perpendicular to the beam and also shadowing the beam. Irradiation of the rods by the beam of charged particles creates radioactive isotopes in a quantity proportional to the number of charged particles incident upon the rods. Measurement of the radioactivity of each of the rods provides a measure of the quantity of radioactive material generated thereby and, together with the location of the rods, provides information sufficient to identify a profile of the density of charged particles in the beam

  8. The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chihway; et al.

    2017-10-18

    Splashback refers to the process of matter that is accreting onto a dark matter halo reaching its first orbital apocenter and turning around in its orbit. The cluster-centric radius at which this process occurs, r_sp, defines a halo boundary that is connected to the dynamics of the cluster, in contrast with other common halo boundary definitions such as R_200. A rapid decline in the matter density profile of the halo is expected near r_sp. We measure the galaxy number density and weak lensing mass profiles around RedMapper galaxy clusters in the first year Dark Energy Survey (DES) data. For a cluster sample with mean mass ~2.5 x 10^14 solar masses, we find strong evidence of a splashback-like steepening of the galaxy density profile and measure r_sp=1.16 +/- 0.08 Mpc/h, consistent with earlier SDSS measurements of More et al. (2016) and Baxter et al. (2017). Moreover, our weak lensing measurement demonstrates for the first time the existence of a splashback-like steepening of the matter profile of galaxy clusters. We measure r_sp=1.28 +/- 0.18 Mpc/h from the weak lensing data, in good agreement with our galaxy density measurements. Applying our analysis to different cluster and galaxy samples, we find that consistent with LambdaCDM simulations, r_sp scales with R_200m and does not evolve with redshift over the redshift range of 0.3--0.6. We also find that potential systematic effects associated with the RedMapper algorithm may impact the location of r_sp, in particular the choice of scale used to estimate cluster richness. We discuss progress needed to understand the systematic uncertainties and fully exploit forthcoming data from DES and future surveys, emphasizing the importance of more realistic mock catalogs and independent cluster samples.

  9. Density Profiles, Energy, and Oscillation Strength of a Quantum Dot in Two Dimensions with a Harmonic Oscillator External Potential using an Orbital-free Energy Functional Based on Thomas–Fermi Theory

    Directory of Open Access Journals (Sweden)

    Suhufa Alfarisa

    2016-03-01

    Full Text Available This research aims i to determine the density profile and calculate the ground state energy of a quantum dot in two dimensions (2D with a harmonic oscillator potential using orbital-free density functional theory, and ii to understand the effect of the harmonic oscillator potential strength on the electron density profiles in the quantum dot. This study determines the total energy functional of the quantum dot that is a functional of the density that depends only on spatial variables. The total energy functional consists of three terms. The first term is the kinetic energy functional, which is the Thomas–Fermi approximation in this case. The second term is the external potential. The harmonic oscillator potential is used in this study. The last term is the electron–electron interactions described by the Coulomb interaction. The functional is formally solved to obtain the electron density as a function of spatial variables. This equation cannot be solved analytically, and thus a numerical method is used to determine the profile of the electron density. Using the electron density profiles, the ground state energy of the quantum dot in 2D can be calculated. The ground state energies obtained are 2.464, 22.26, 90.1957, 252.437, and 496.658 au for 2, 6, 12, 20, and 56 electrons, respectively. The highest electron density is localized close to the middle of the quantum dot. The density profiles decrease with the increasing distance, and the lowest density is at the edge of the quantum dot. Generally, increasing the harmonic oscillator potential strength reduces the density profiles around the center of the quantum dot.

  10. Semi-analytical study of the tokamak pedestal density profile in a single-null diverted plasma with puffing-recycling gas sources

    Science.gov (United States)

    Shi, Bingren

    2010-10-01

    The tokamak pedestal density structure is generally studied using a diffusion-dominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion-convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position.

  11. Semi-analytical study of the tokamak pedestal density profile in a single-null diverted plasma with puffing-recycling gas sources

    Energy Technology Data Exchange (ETDEWEB)

    Shi Bingren, E-mail: shibr@swip.ac.c [Southwestern Institute of Physics, PO Box 432, Chengdu, Sichuan 610041 (China)

    2010-10-15

    The tokamak pedestal density structure is generally studied using a diffusion-dominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion-convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position.

  12. Modification of K-line emission profiles in laser-created solid-density plasmas

    International Nuclear Information System (INIS)

    Sengebusch, A.; Reinholz, H.; Roepke, G.

    2010-01-01

    Complete text of publication follows. X-ray emissions in the keV energy range have shown to be suitable radiation to investigate the properties of laser-created solid-density plasmas. We use the modifications of inner shell transitions due to the environment to characterize these plasmas. A theoretical treatment of spectral line profiles based on a self-consistent ion sphere model is applied on moderately ionized mid-Z materials, such as titanium, silicon and chlorine. We observe large contributions of satellite transitions due to M-shell ionization and excitation. To determine the composition a mixture of various excited and ionized ionic states embedded in a plasma has to be considered. Plasma polarization effects that cause shifts of the emission and ionization energies are taken into account. K-line profiles are calculated for bulk temperatures up to 100 eV and free electron densities up to 10 24 cm -3 in order to analyze recent measurements with respect to the plasma parameters of electron heated target regions. Moreover, in high-intensity laser-matter interactions, inevitable prepulses are likely to create preplasma and shocks within the target before the main pulse arrives. We investigate the influence of density gradients due to prepulses on the spectral profiles. Further, radial bulk temperature distributions as well the composition of the created warm dense matter are inferred.

  13. Real-time control of the current density and pressure profiles in Jet

    International Nuclear Information System (INIS)

    Mazon, D.; Moreau, D.; Litaudon, X.; Joffrin, E.; Laborde, L.; Zabeo, L.; Crisanti, F.; Riva, M.; Felton, R.; Murari, A.; Tala, T.

    2003-01-01

    In order to ultimately control internal transport barriers during advanced operation scenarios, new algorithms using a truncated singular value decomposition of a linearized model operator have been implemented in the JET real-time controller, with the potentiality of retaining the distributed nature of plasma parameter profiles. First experiments using the simplest, lumped-parameter, version of this technique have been dedicated to the feedback control of the current density profile in a negative shear plasma using three heating and current drive actuators, namely neutral beam injection (NBI), ion cyclotron resonant frequency heating (ICRH) and lower hybrid current drive (LHCD). Successful control of the safety factor profile has been achieved on the time scale of the current redistribution time, first during an extended preheat phase with only LHCD as actuator and, then, in quasi steady-state conditions during the main heating phase of a discharge, using the three heating and current drive actuators

  14. Line profiles of hydrogenic ions from high-temperature and high-density plasmas

    International Nuclear Information System (INIS)

    Hou Qing; Li Jianming

    1991-01-01

    Applying the Hooper's first-order theory, the authors calculate the static micro-electric field distributions in plasmas containing various multiply-charged ions. The influences of the impurity concentrations on the micro electric field distributions and on the Lyman profiles (n→1) from hydrogenic ions are analysed. Based on the optical-thin line profiles, the radiation transfer equation in sphere plasmas with various optical depths is solved. The results confirm that the opacity-broadening of the line profiles has almost no effect on the separation of Lyman β splitted peaks. Such separation is determined by electric field at which the static micro-electric field distribution has a maximum. The separation can be utilized for spatially resolved and temporally resolved density diagnostic of fusion plasmas

  15. Advanced density profile reflectometry; the state-of-the-art and measurement prospects for ITER

    Science.gov (United States)

    Doyle, E. J.

    2006-10-01

    Dramatic progress in millimeter-wave technology has allowed the realization of a key goal for ITER diagnostics, the routine measurement of the plasma density profile from millimeter-wave radar (reflectometry) measurements. In reflectometry, the measured round-trip group delay of a probe beam reflected from a plasma cutoff is used to infer the density distribution in the plasma. Reflectometer systems implemented by UCLA on a number of devices employ frequency-modulated continuous-wave (FM-CW), ultrawide-bandwidth, high-resolution radar systems. One such system on DIII-D has routinely demonstrated measurements of the density profile over a range of electron density of 0-6.4x10^19,m-3, with ˜25 μs time and ˜4 mm radial resolution, meeting key ITER requirements. This progress in performance was made possible by multiple advances in the areas of millimeter-wave technology, novel measurement techniques, and improved understanding, including: (i) fast sweep, solid-state, wide bandwidth sources and power amplifiers, (ii) dual polarization measurements to expand the density range, (iii) adaptive radar-based data analysis with parallel processing on a Unix cluster, (iv) high memory depth data acquisition, and (v) advances in full wave code modeling. The benefits of advanced system performance will be illustrated using measurements from a wide range of phenomena, including ELM and fast-ion driven mode dynamics, L-H transition studies and plasma-wall interaction. The measurement capabilities demonstrated by these systems provide a design basis for the development of the main ITER profile reflectometer system. This talk will explore the extent to which these reflectometer system designs, results and experience can be translated to ITER, and will identify what new studies and experimental tests are essential.

  16. Analytic expressions for mode conversion in a plasma with a parabolic density profile: Generalized results

    International Nuclear Information System (INIS)

    Hinkel-Lipsker, D.E.; Fried, B.D.; Morales, G.J.

    1993-01-01

    This study provides an analytic solution to the general problem of mode conversion in an unmagnetized plasma. Specifically, an electromagnetic wave of frequency ω propagating through a plasma with a parabolic density profile of scale length L p is examined. The mode conversion points are located a distance Δ 0 from the peak of the profile, where the electron plasma frequency ω p (z) matches the wave frequency ω. The corresponding reflection, transmission, and mode conversion coefficients are expressed analytically in terms of parabolic cylinder functions for all values of Δ 0 . The method of solution is based on a source approximation technique that is valid when the electromagnetic and electrostatic scale lengths are well separated. For large Δ 0 , i.e., (cL p /ω) 1/2 much-lt Δ 0 p , the appropriately scaled result [D. E. Hinkel-Lipsker et al., Phys. Fluids B 4, 559 (1992)] for a linear density profile is recovered as the parabolic cylinder functions asymptotically become Airy functions. When Δ 0 →0, the special case of conversion at the peak of the profile [D. E. Hinkel-Lipsker et al., Phys. Fluids B 4, 1772 (1992)] is obtained

  17. Measurement of impurity ion densities and energies in the divertor and edge regions of Alcator C-Mod tokamak

    International Nuclear Information System (INIS)

    Griem, H.R.; Moreno, J.; Welch, B.L.

    1992-01-01

    A study to investigate impurity production and transport in the divertor and edge regions of the Alcator C-Mod tokamak through spectroscopic techniques is described. A 0.75-meter Czerny-Turner spectrometer with a 1200-g/mm grating and a 35-meter quartz optic bundle transmission line were tested. A high-resolution 2-meter spectrometer will be ordered. Data acquisition considerations are being addressed

  18. TIDAL STIRRING OF SATELLITES WITH SHALLOW DENSITY PROFILES PREVENTS THEM FROM BEING TOO BIG TO FAIL

    Energy Technology Data Exchange (ETDEWEB)

    Tomozeiu, Mihai; Mayer, Lucio [Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Quinn, Thomas, E-mail: mihai@physik.uzh.ch [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States)

    2016-08-10

    The “too big to fail” problem is revisited by studying the tidal evolution of populations of dwarf satellites with different density profiles. The high-resolution cosmological ΛCDM “ErisMod” set of simulations is used. These simulations can model both the stellar and dark matter components of the satellites, and their evolution under the action of the tides of a Milky Way (MW)-sized host halo at a force resolution better than 10 pc. The stronger tidal mass loss and re-shaping of the mass distribution induced in satellites with γ = 0.6 dark matter density distributions, as those resulting from the effect of feedback in hydrodynamical simulations of dwarf galaxy formation, are sufficient to bring the circular velocity profiles in agreement with the kinematics of MW’s dSphs. In contrast, in simulations in which the satellites retain cusps at z = 0 there are several “massive failures” with circular velocities in excess of the observational constraints. Various sources of deviations in the conventionally adopted relation between the circular velocity at the half-light radius and the one-dimensional line of sight velocity dispersions are found. Such deviations are caused by the response of circular velocity profiles to tidal effects, which also varies depending on the initially assumed inner density profile and by the complexity of the stellar kinematics, which include residual rotation and anisotropy. In addition, tidal effects naturally induce large deviations in the stellar mass–halo mass relation for halo masses below 10{sup 9} M {sub ⊙}, preventing any reliable application of the abundance matching technique to dwarf galaxy satellites.

  19. Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, A. Meredith; Lieman-Sifry, Jesse; Flaherty, Kevin M.; Daley, Cail M. [Department of Astronomy, Van Vleck Observatory, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Roberge, Aki [Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States); Kóspál, Ágnes; Moór, Attila; Ábrahám, Peter [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Kamp, Inga [Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen (Netherlands); Wilner, David J.; Andrews, Sean M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States); Kastner, Joel H., E-mail: amhughes@astro.wesleyan.edu [Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

    2017-04-20

    We present ∼0.″4 resolution images of CO(3–2) and associated continuum emission from the gas-bearing debris disk around the nearby A star 49 Ceti, observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). We analyze the ALMA visibilities in tandem with the broadband spectral energy distribution to measure the radial surface density profiles of dust and gas emission from the system. The dust surface density decreases with radius between ∼100 and 310 au, with a marginally significant enhancement of surface density at a radius of ∼110 au. The SED requires an inner disk of small grains in addition to the outer disk of larger grains resolved by ALMA. The gas disk exhibits a surface density profile that increases with radius, contrary to most previous spatially resolved observations of circumstellar gas disks. While ∼80% of the CO flux is well described by an axisymmetric power-law disk in Keplerian rotation about the central star, residuals at ∼20% of the peak flux exhibit a departure from axisymmetry suggestive of spiral arms or a warp in the gas disk. The radial extent of the gas disk (∼220 au) is smaller than that of the dust disk (∼300 au), consistent with recent observations of other gas-bearing debris disks. While there are so far only three broad debris disks with well characterized radial dust profiles at millimeter wavelengths, 49 Ceti’s disk shows a markedly different structure from two radially resolved gas-poor debris disks, implying that the physical processes generating and sculpting the gas and dust are fundamentally different.

  20. Investigation of Electron Density Profile in the ionospheric D and E region by Kagoshima rocket experiment

    Science.gov (United States)

    Ashihara, Y.; Ishisaka, K.; Miyake, T.; Okada, T.; Nagano, I.; Abe, T.; Ono, T.

    2007-12-01

    The radio wave propagation characteristic in the lower ionosphere is important because of its effect on commercial radio communication, navigation, and broadcast services. The electron density is of primary interest in this region because the high ion-neutral collision frequencies result in radio wave absorption. In order to investigate the ionization structure in the ionospheric D and E region by using the propagation characteristics of MF-band and LF-band radio waves, S-310-37 and S-520-23 sounding rocket experiments have been carried out at Uchinoura Space Center (USC). S-310-37 sounding rocket was launched at 11:20 LT on January 16, 2007. The apex of rocket trajectory was about 138 km. Then S-520-23 sounding rocket was launched at 19:20 LT on September 2, 2007. The apex was about 279 km. As a common measurement, these sounding rockets measure the fields intensities and the waveform of radio waves from NHK Kumamoto broadcasting station (873kHz, 500kW) and JJY signals from Haganeyama LF radio station (60kHz, 50kW). The approximate electron density profile can be determined from the comparison between these experimental results and propagation characteristics calculated by the full wave method. We will get the most probable electron density profile in the ionosphere. In presentation, we will show the propagation characteristic of LF/MF radio waves measured by two sounding rocket experiments. Then we will discuss the analysis method and the estimated electron density profile in the ionosphere.

  1. Preliminary results of structural profiling of the Kras edge and Istria (Kozina – Srmin Motorway, Sečovlje

    Directory of Open Access Journals (Sweden)

    2002-06-01

    Full Text Available On the section Kozina-Srmin the new motorway Ljubljana-Koper is crossing the Kras edge, which in geologic terminology is refered to as the Kras thrust edge. In the widest sense it comprises the area between the edge of the Trieste-Komen plateau and the Savudrija ridge, creating the boundary between the Adriatic foreland and the External Dinarides. Detailed geologic mapping of the motorway section Kozina-Srmin slowed that the Kras thrust edge is not a monophase tectonic structure, but has been formed through several different deformation phases from the Eocene until today. Besides smaller onesthese phases include responses of three significant events; the Dinaric nappe thrusting, displacements along the strice-slipe faults with NW-SE trending and underthrusting of the Istria toward the NE. The latter event destroyed the primary of the SW boundary ofthe External Dinarides between Southern Alps and the Velebit arc.

  2. Impact of measurement approach on the quality of gamma scanning density profile in a tray type lab-scale column

    International Nuclear Information System (INIS)

    Shahabinejad, H.; Feghhi, S.A.H.; Khorsandi, M.

    2014-01-01

    This article presents a study for investigating impact of the measurement approach on the quality of gamma scanning density profile in tray type columns using experimental and computational evaluations. Experimental density profiles from the total and the photopeak count measurements, as two approaches in gamma ray column scanning technique, has been compared with the computational density profile from Monte Carlo simulation results. We used a laboratory distillation column of 51 cm diameter as an illustrative example for this investigation. 137 Cs was used as a gamma ray source with the activity of 296 MBq (8 mCi), with a NaI(Tl) detector. MCNP4C Monte Carlo code has been used for simulations. The quality of the density profile in the photopeak count approach is relatively within 155–204% better than that of the total count approach for experimental results. The same comparison for simulation results leads to a relative difference within 100–135% for the density profile. - Highlights: • The quality of density profile in gamma scanning technique has been studied. • Quality of density profile depends on the measurement approach. • A laboratory distillation column has been used as an illustrative example. • MCNP4C Monte Carlo code has been used for simulations

  3. Majorana zero modes and long range edge correlation in interacting Kitaev chains: analytic solutions and density-matrix-renormalization-group study.

    Science.gov (United States)

    Miao, Jian-Jian; Jin, Hui-Ke; Zhang, Fu-Chun; Zhou, Yi

    2018-01-11

    We study Kitaev model in one-dimension with open boundary condition by using exact analytic methods for non-interacting system at zero chemical potential as well as in the symmetric case of Δ = t, and by using density-matrix-renormalization-group method for interacting system with nearest neighbor repulsion interaction. We suggest and examine an edge correlation function of Majorana fermions to characterize the long range order in the topological superconducting states and study the phase diagram of the interating Kitaev chain.

  4. Nekton densities along Spartina alterniflora marsh-edge and adjacent shallow non-vegetated bottom in Carancahua Cove, Texas from 1982-03-03 to 1993-06-24 (NCEI Accession 0161172)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains nekton counts used to quantify and compare densities along Spartina alterniflora marsh-edge and adjacent shallow non-vegetated bottom in...

  5. Recent measurements of electron density profiles of plasmas in PLADIS I, a plasma disruption simulator

    International Nuclear Information System (INIS)

    Bradley, J. III; Sharp, G.; Gahl, J.M. Kuznetsov, V.; Rockett, P.; Hunter, J.

    1995-01-01

    Tokamak disruption simulation experiments are being conducted at the University of New Mexico (UNM) using the PLADIS I plasma gun system. PLADIS I is a high power, high energy coaxial plasma gun configured to produce an intense plasma beam. First wall candidate materials are placed in the beam path to determine their response under disruption relevant energy densities. An optically thick vapor shield plasma has been observed to form above the target surface in PLADIS I. Various diagnostics have been used to determine the characteristics of the incident plasma and the vapor shielding plasma. The cross sectional area of the incident plasma beam is a critical characteristic, as it is used in the calculation of the incident plasma energy density. Recently, a HeNe interferometer in the Mach-Zehnder configuration has been constructed and used to probe the electron density of the incident plasma beam and vapor shield plasma. The object beam of the interferometer is scanned across the plasma beam on successive shots, yielding line integrals of beam density on different chords through the plasma. Data from the interferometer is used to determine the electron density profile of the incident plasma beam as a function of beam radius. This data is then used to calculate the effective beam area. Estimates. of beam area, obtained from other diagnostics such as damage targets, calorimeter arrays and off-axis measurements of surface pressure, will be compared with data from the interferometer to obtain a better estimate of the beam cross sectional area

  6. Topside ionospheric vertical electron density profile reconstruction using GPS and ionosonde data: possibilities for South Africa

    Directory of Open Access Journals (Sweden)

    P. Sibanda

    2011-02-01

    Full Text Available Successful empirical modeling of the topside ionosphere relies on the availability of good quality measured data. The Alouette, ISIS and Intercosmos-19 satellite missions provided large amounts of topside sounder data, but with limited coverage of relevant geophysical conditions (e.g., geographic location, diurnal, seasonal and solar activity by each individual mission. Recently, methods for inferring the electron density distribution in the topside ionosphere from Global Positioning System (GPS-based total electron content (TEC measurements have been developed. This study is focused on the modeling efforts in South Africa and presents the implementation of a technique for reconstructing the topside ionospheric electron density (Ne using a combination of GPS-TEC and ionosonde measurements and empirically obtained Upper Transition Height (UTH. The technique produces reasonable profiles as determined by the global models already in operation. With the added advantage that the constructed profiles are tied to reliable measured GPS-TEC and the empirically determined upper transition height, the technique offers a higher level of confidence in the resulting Ne profiles.

  7. Segment density profiles of polyelectrolyte brushes determined by Fourier transform ellipsometry

    Science.gov (United States)

    Biesalski, Markus; Rühe, Jürgen; Johannsmann, Diethelm

    1999-10-01

    We describe a method for the explicit determination of the segment density profile φ(z) of surface-attached polymer brushes with multiple angle of incidence null-ellipsometry. Because the refractive index contrast between the brush layer and the solvent is weak, multiple reflections are of minor influence and the ellipsometric spectrum is closely related to the Fourier transform of the refractive index profile, thereby allowing for explicit inversion of the ellipsometric data. We chose surface-attached monolayers of polymethacrylic acid (PMAA), a weak polyelectrolyte, as a model system and determined the segment density profile of this system as a function of the pH value of the surrounding medium by the Fourier method. Complementary to the Fourier analysis, fits with error functions are given as well. The brushes were prepared on the bases of high refractive index prisms with the "grafting-from" technique. In water, the brushes swell by more than a factor of 30. The swelling increases with increasing pH because of a growing fraction of dissociated acidic groups leading to a larger electrostatic repulsion.

  8. Generalized saddle point condition for ignition in a tokamak reactor with temperature and density profiles

    International Nuclear Information System (INIS)

    Mitari, O.; Hirose, A.; Skarsgard, H.M.

    1989-01-01

    In this paper, the concept of a generalized ignition contour map, is extended to the realistic case of a plasma with temperature and density profiles in order to study access to ignition in a tokamak reactor. The generalized saddle point is found to lie between the Lawson and ignition conditions. If the height of the operation path with Goldston L-mode scaling is higher than the generalized saddle point, a reactor can reach ignition with this scaling for the case with no confinement degradation effect due to alpha-particle heating. In this sense, the saddle point given in a general form is a new criterion for reaching ignition. Peaking the profiles for the plasma temperature and density can lower the height of the generalized saddle point and help a reactor to reach ignition. With this in mind, the authors can judge whether next-generation tokamaks, such as Compact Ignition Tokamak, Tokamak Ignition/Burn Experimental Reactor, Next European Torus, Fusion Experimental Reactor, International Tokamak Reactor, and AC Tokamak Reactor, can reach ignition with realistic profile parameters and an L-mode scaling law

  9. Constraining the Milky Way dark matter density profile with gamma-rays with Fermi-LAT

    International Nuclear Information System (INIS)

    Bernal, Nicolás; Palomares-Ruiz, Sergio

    2012-01-01

    We study the abilities of the Fermi-LAT instrument on board of the Fermi mission to simultaneously constrain the Milky Way dark matter density profile and some dark matter particle properties, as annihilation cross section, mass and branching ratio into dominant annihilation channels. A single dark matter density profile is commonly assumed to determine the capabilities of gamma-ray experiments to extract dark matter properties or to set limits on them. However, our knowledge of the Milky Way halo is far from perfect, and thus in general, the obtained results are too optimistic. Here, we study the effect these astrophysical uncertainties would have on the determination of dark matter particle properties and conversely, we show how gamma-ray searches could also be used to learn about the structure of the Milky Way halo, as a complementary tool to other type of observational data that study the gravitational effect caused by the presence of dark matter. In addition, we also show how these results would improve if external information on the annihilation cross section and on the local dark matter density were included and compare our results with the predictions from numerical simulations

  10. Density profile measurements from a two-gun plasma focus device

    International Nuclear Information System (INIS)

    Tzeng, C.C.; Yen, C.K.; Yeh, T.R.; Kuo, Y.Y.; Shang, D.J.; Yu, Y.Z.; Hou, W.S.

    1990-01-01

    The dynamics of the plasma evolution in a two-gun plasma focus device has been studied using the laser shadowgraphy as well as the laser interferometry. The experiments were carried out from a 700 kJ two-gun plasma focus device reported earlier, which consisted of a pair of Mather type coaxial electrodes connected muzzle to muzzle. Previous results indicated that the simultaneous formation of the two deuterium plasma foci occurred earlier and then after ∼ 100 ns a disk-shaped plasma of ∼ 1.5 cm in diameter appeared in the middle region between the anodes. It is, therefore, the authors' goal to study the density profiles in the plasma foci and the middle region in order to understand further the formation of the plasma foci and their time evolution. The laser shadowgraphy was done with a XeCl excimer pumped dye laser system which operated at 550 nm with pulse width of ∼ 10 ns. The laser interferometry, on the other hand, was carried out using a TEA-TEA oscillator-amplifier N 2 -laser system with 337.1 nm and subnano-second pulse width. Both results show that the maximum electron density is ≥2 x 10 19 cm -3 and, in addition, the growth of the hydrodynamic instabilities are observed. These results together with the detailed density profiles are presented and discussed

  11. Effect of plasma density profile of tokamak on Kelvin-Helmholtz instability

    International Nuclear Information System (INIS)

    Tang Fulin

    1984-01-01

    The purpose of this paper is to study the effect of radial distribution of plasma density profile of tokamak on Kelvin-Helmholtz instability caused by toroidal rotation. The effect of radial distribution of plasma rotational velocity on stability is also examine for comparison. It is found that within the range of tokamak parameters the only radial distribution of plasma rotational velocity cannot induce Kelvin-Helmholtz instability. On the contrary, when there is a radial distribution of plasma density, i.e. P 01 =P 0 e -tx and V 0 1 = const, plasma becomes unstable, and instability will increase proportionally to the value of t. Meanwhile when the value of t remains constant, the instability growth rate will decrease if P 0 grows or the distance between plasma and wall of container decreases too. It shows that the Kelvin-Helmoltz instability is not only influenced by the steepness of density profile but also by the inertia of plasma in central region, which is helpful for depressing the instability. (author). 5 refs, 4 figs, 2 tabs

  12. Fluid and gyrokinetic modelling of particle transport in plasmas with hollow density profiles

    International Nuclear Information System (INIS)

    Tegnered, D; Oberparleiter, M; Nordman, H; Strand, P

    2016-01-01

    Hollow density profiles occur in connection with pellet fuelling and L to H transitions. A positive density gradient could potentially stabilize the turbulence or change the relation between convective and diffusive fluxes, thereby reducing the turbulent transport of particles towards the center, making the fuelling scheme inefficient. In the present work, the particle transport driven by ITG/TE mode turbulence in regions of hollow density profiles is studied by fluid as well as gyrokinetic simulations. The fluid model used, an extended version of the Weiland transport model, Extended Drift Wave Model (EDWM), incorporates an arbitrary number of ion species in a multi-fluid description, and an extended wavelength spectrum. The fluid model, which is fast and hence suitable for use in predictive simulations, is compared to gyrokinetic simulations using the code GENE. Typical tokamak parameters are used based on the Cyclone Base Case. Parameter scans in key plasma parameters like plasma β, R/L T , and magnetic shear are investigated. It is found that β in particular has a stabilizing effect in the negative R/L n region, both nonlinear GENE and EDWM show a decrease in inward flux for negative R/L n and a change of direction from inward to outward for positive R/L n . This might have serious consequences for pellet fuelling of high β plasmas. (paper)

  13. Relativistic self-focusing of intense laser beam in thermal collisionless quantum plasma with ramped density profile

    Directory of Open Access Journals (Sweden)

    S. Zare

    2015-04-01

    Full Text Available 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.

  14. High-Latitude Topside Ionospheric Vertical Electron Density Profile Changes in Response to Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

    2016-01-01

    Large magnetic-storm-induced changes were detected in high-latitude topside vertical electron density profiles Ne(h) in a database of profiles and digital topside ionograms, from the International Satellites for Ionospheric Studies (ISIS) program, that enabled Ne(h) profiles to be obtained in nearly the same region of space before, during, and after a major magnetic storm (Dst -100nT). Storms where Ne(h) profiles were available in the high-latitude Northern Hemisphere had better coverage of solar wind parameters than storms with available Ne(h) profiles in the high-latitude Southern Hemisphere. Large Ne(h) changes were observed during all storms, with enhancements and depletions sometimes near a factor of 10 and 0.1, respectively, but with substantial differences in the responses in the two hemispheres. Large spatial andor temporal Ne(h) changes were often observed during Dst minimum and during the storm recovery phase. The storm-induced Ne(h) changes were the most pronounced and consistent in the Northern Hemisphere in that large enhancements were observed during winter nighttime and large depletions during winter and spring daytime. The limited available cases suggested that these Northern Hemisphere enhancements increased with increases of the time-shifted solar wind velocity v, magnetic field B, and with more negative values of the B components except for the highest common altitude (1100km) of the profiles. There was also some evidence suggesting that the Northern Hemisphere depletions were related to changes in the solar wind parameters. Southern Hemisphere storm-induced enhancements and depletions were typically considerably less with depletions observed during summer nighttime conditions and enhancements during summer daytime and fall nighttime conditions.

  15. Iterative noise removal from temperature and density profiles in the TJ-II Thomson scattering

    International Nuclear Information System (INIS)

    Farias, G.; Dormido-Canto, S.; Vega, J.; Santos, M.; Pastor, I.; Fingerhuth, S.; Ascencio, J.

    2014-01-01

    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

  16. 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.

  17. Density profiles of granular gases studied by molecular dynamics and Brownian bridges

    Science.gov (United States)

    Peñuñuri, F.; Montoya, J. A.; Carvente, O.

    2018-02-01

    Despite the inherent frictional forces and dissipative collisions, confined granular matter can be regarded as a system in a stationary state if we inject energy continuously. Under these conditions, both the density and the granular temperature are, in general, non-monotonic variables along the height of the container. In consequence, an analytical description of a granular system is hard to conceive. Here, by using molecular dynamics simulations, we measure the packing fraction profiles for a vertically vibrating three-dimensional granular system in several gaseous-like stationary states. We show that by using the Brownian bridge concept, the determined packing fraction profiles can be reproduced accurately and give a complete description of the distribution of the particles inside the simulation box.

  18. Modelling of the electron density height profiles in the mid-latitude ionospheric D-region

    Directory of Open Access Journals (Sweden)

    P. Y. Mukhtarov

    1996-06-01

    Full Text Available A new mid-latitude D-region (50-105 km model of the electron density is presented obtained on the basis of a full wave theory and by a trial-and-error inversion method. Daytime (at different solar zenith angles absorption measurements by A3-technique made in Bulgaria yielded data with the aid of which the seasonal and diurnal courses of the Ne(h-profiles were derived. Special attention is drawn to the event diurnal asymmetry, or uneven formation of the ionosphere as a function of insulation. The latter is probably connected with the influence of the diurnal fluctuations in the local temperature on the chemistry involved in the electron loss rate, as well as the diurnal variations of the main ionizing agent (NO in the D-region. That is why the Ne(h-profiles in the midlatitude D-region are modelled separately for morning and afternoon hours.

  19. Task-Related Edge Density (TED)-A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain.

    Science.gov (United States)

    Lohmann, Gabriele; Stelzer, Johannes; Zuber, Verena; Buschmann, Tilo; Margulies, Daniel; Bartels, Andreas; Scheffler, Klaus

    2016-01-01

    The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach "Task-related Edge Density" (TED). TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function.

  20. Task-Related Edge Density (TED-A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain.

    Directory of Open Access Journals (Sweden)

    Gabriele Lohmann

    Full Text Available The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach "Task-related Edge Density" (TED. TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function.

  1. On the choice of lens density profile in time delay cosmography

    Science.gov (United States)

    Sonnenfeld, Alessandro

    2018-03-01

    Time delay lensing is a mature and competitive cosmological probe. However, it is limited in accuracy by the well-known problem of the mass-sheet degeneracy: too rigid assumptions on the density profile of the lens can potentially bias the inference on cosmological parameters. I investigate the degeneracy between the choice of the lens density profile and the inference on the Hubble constant, focusing on double image systems. By expanding lensing observables in terms of the local derivatives of the lens potential around the Einstein radius, and assuming circular symmetry, I show that 3 degrees of freedom in the radial direction are necessary to achieve a few per cent accuracy in the time-delay distance. Additionally, while the time delay is strongly dependent on the second derivative of the potential, observables typically used to constrain lens models in time-delay studies, such as image position and radial magnification information, are mostly sensitive to the first and third derivatives, making it very challenging to accurately determine time-delay distances with lensing data alone. Tests on mock observations show that the assumption of a power-law density profile results in a 5 per cent average bias on H0, with a 6 per cent scatter. Using a more flexible model and adding unbiased velocity dispersion constraints allows me to obtain an inference with 1 per cent accuracy. A power-law model can still provide 3 per cent accuracy if velocity dispersion measurements are used to constrain its slope. Although this study is based on the assumption of axisymmetry, its main findings can be generalized to cases with moderate ellipticity.

  2. Exploration of one-dimensional plasma current density profile for K-DEMO steady-state operation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, J.S. [Seoul National University, Seoul 151-742 (Korea, Republic of); Jung, L. [National Fusion Research Institute, Daejeon (Korea, Republic of); Byun, C.-S.; Na, D.H.; Na, Y.-S. [Seoul National University, Seoul 151-742 (Korea, Republic of); Hwang, Y.S., E-mail: yhwang@snu.ac.kr [Seoul National University, Seoul 151-742 (Korea, Republic of)

    2016-11-01

    Highlights: • One-dimensional current density and its optimization for the K-DEMO are explored. • Plasma current density profile is calculated with an integrated simulation code. • The impact of self and external heating profiles is considered self-consistently. • Current density is identified as a reference profile by minimizing heating power. - Abstract: Concept study for Korean demonstration fusion reactor (K-DEMO) is in progress, and basic design parameters are proposed by targeting high magnetic field operation with ITER-sized machine. High magnetic field operation is a favorable approach to enlarge relative plasma performance without increasing normalized beta or plasma current. Exploration of one-dimensional current density profile and its optimization process for the K-DEMO steady-state operation are reported in this paper. Numerical analysis is conducted with an integrated plasma simulation code package incorporating a transport code with equilibrium and current drive modules. Operation regimes are addressed with zero-dimensional system analysis. One-dimensional plasma current density profile is calculated based on equilibrium, bootstrap current analysis, and thermal transport analysis. The impact of self and external heating profiles on those parameters is considered self-consistently, where thermal power balance and 100% non-inductive current drive are the main constraints during the whole exploration procedure. Current and pressure profiles are identified as a reference steady-state profile by minimizing the external heating power with desired fusion power.

  3. Hollow density profile on electron cyclotron resonance heating JFT-2M plasma

    International Nuclear Information System (INIS)

    Yamauchi, Toshihiko; Hoshino, Katsumichi; Kawashima, Hisato; Ogawa, Toshihide; Kawakami, Tomohide; Shiina, Tomio; Ishige, Youichi

    1998-01-01

    The first hollow electron density profile in the central region on the JAERI Fusion Torus-2M (JFT-2M) is measured during electron cyclotron resonance heating (ECRH) with a TV Thomson scattering system (TVTS). The peripheral region is not hollow but is accumulated due to pump-out from the central region. The hollowness increases with time but is saturated at ∼40 ms and maintains a constant hollow ratio. The hollowness is strongly related to the steep temperature gradient of the heated zone. (author)

  4. Measurements of electron density and temperature profiles in a gas blanket experiment

    International Nuclear Information System (INIS)

    Kuthy, A.

    1979-02-01

    Radial profiles of electron density, temperature and H sub(β) intensity are presented for the rotating plasma device F-1. The hydrogen filling pressure, the average magnetic field strength at the midplane, and the power input to the discharge have been varied in the ranges 10-100 mTorr, 0.25-0.5 Tesla, and 0.1 to 1.5 MW, respectively. These experiments have been performed with the main purpose of studying the gas blanket (cold-mantle) state of the plasma. It is shown, that a simple spectroscopic method can be used to derive the radial distribution of the electron temperature in such plasmas. The observed peak temperatures and densities are in agreement with earlier theoretical estimates. (author)

  5. Fast-scan monitor examines neutral-beam ion-density profile

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    All of the magnetic mirror confinement fusion experiments at LLL and at other laboratories depend on pulsed, energetic neutral-beam injection for fueling and imparting energy to the trapped plasma for density build-up and stability studies. It is vital to be able to monitor how well the injected ion beam is aimed and focused. To do this, we have designed an ion-beam current-density profile monitor that uses a commercial minimodular data acquisition system. Our prototype model monitors a single 20-kV, 50-A, 10-ms beam. However, the method is applicable to any number of beams with similar sampling target arrays. Also, the electronics can be switched to monitor any one of several target collectors

  6. Specific Modulus and Density Profile as Characterization Criteria of Prefabricated Wood Composite Materials

    Directory of Open Access Journals (Sweden)

    Pavel Král

    2015-01-01

    Full Text Available Wood based product industry has developed and modified a wide range of products to cater changing demands of construction industry. Development of a product necessitates characterization to ensure compliance to established standards. Traditionally a product was characterized by properties like bending properties, density and swelling factor etc. Whereas, advances in technology has introduced more sophisticated parameters which represent a combination of various classical factors and provide more practical and detailed information. In this study, we procured four different types of commercial products, viz. Gypsum board, cement board, oriented strand board and gypsum fiber board and tried to characterized them using density profile ratio and stiffness ratio. We observed some interesting empirical relations between various parameters as represented in various plots.

  7. Density profiles and collective excitations of a trapped two-component Fermi vapour

    International Nuclear Information System (INIS)

    Amoruso, M.; Meccoli, I.; Minguzzi, A.; Tosi, M.P.

    1999-08-01

    We discuss the ground state and the small-amplitude excitations of a degenerate vapour of fermionic atoms placed in two hyperfine states inside a spherical harmonic trap. An equations-of-motion approach is set up to discuss the hydrodynamic dissipation processes from the interactions between the two components of the fluid beyond mean-field theory and to emphasize analogies with spin dynamics and spin diffusion in a homogeneous Fermi liquid. The conditions for the establishment of a collisional regime via scattering against cold-atom impurities are analyzed. The equilibrium density profiles are then calculated for a two-component vapour of 40 K atoms: they are little modified by the interactions for presently relevant values of the system parameters, but spatial separation of the two components will spontaneously arise as the number of atoms in the trap is increased. The eigenmodes of collective oscillation in both the total particle number density and the concentration density are evaluated analytically in the special case of a symmetric two-component vapour in the collisional regime. The dispersion relation of the surface modes for the total particle density reduces in this case to that of a one-component Fermi vapour, whereas the frequencies of all other modes are shifted by the interactions. (author)

  8. Density profiles in the Scrape-Off Layer interpreted through filament dynamics

    Science.gov (United States)

    Militello, Fulvio

    2017-10-01

    We developed a new theoretical framework to clarify the relation between radial Scrape-Off Layer density profiles and the fluctuations that generate them. The framework provides an interpretation of the experimental features of the profiles and of the turbulence statistics on the basis of simple properties of the filaments, such as their radial motion and their draining towards the divertor. L-mode and inter-ELM filaments are described as a Poisson process in which each event is independent and modelled with a wave function of amplitude and width statistically distributed according to experimental observations and evolving according to fluid equations. We will rigorously show that radially accelerating filaments, less efficient parallel exhaust and also a statistical distribution of their radial velocity can contribute to induce flatter profiles in the far SOL and therefore enhance plasma-wall interactions. A quite general result of our analysis is the resiliency of this non-exponential nature of the profiles and the increase of the relative fluctuation amplitude towards the wall, as experimentally observed. According to the framework, profile broadening at high fueling rates can be caused by interactions with neutrals (e.g. charge exchange) in the divertor or by a significant radial acceleration of the filaments. The framework assumptions were tested with 3D numerical simulations of seeded SOL filaments based on a two fluid model. In particular, filaments interact through the electrostatic field they generate only when they are in close proximity (separation comparable to their width in the drift plane), thus justifying our independence hypothesis. In addition, we will discuss how isolated filament motion responds to variations in the plasma conditions, and specifically divertor conditions. Finally, using the theoretical framework we will reproduce and interpret experimental results obtained on JET, MAST and HL-2A.

  9. Control of the current density profile with lower hybrid current drive on PBX-M

    International Nuclear Information System (INIS)

    Bell, R.E.; Bernabei, S.; Chu, T.K.; Gettelfinger, G.; Greenough, N.; Hatcher, R.; Ignat, D.; Jardin, S.; Kaita, R.; Kaye, S.; Kozub, T.; Kugel, H.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Sauthoff, N.; Sesnic, S.; Sun, Y.; Takahashi, H.; Tighe, W.; Valeo, E.; von Goeler, S.; Jones, S.; Kesner, J.; Luckhardt, S.; Paoletti, F.; Levinton, F.; Timini, F.

    1993-07-01

    Lower hybrid current drive (LHCD) is being explored as a means to control the current density profile on PBX-M with the goal of raising the central safety factor q(O) to values of 1.5-2 to facilitate access to a full-volume second stable regime. Initial experiments have been conducted with up to 400 kW of 4.6 GHz LH power in circular and indented plasmas with modest parameters. A tangential-viewing two-dimensional hard x-ray imaging diagnostic has been used to observe the bremsstrahlung emission from the suprathermal electrons generated during LHCD. Hollow hard x-ray images have indicated off-axis localization of the driven current. A serious obstacle to the control of the current density profile with LHCD is the concomitant generation of MHD activity, which can seriously degrade the confinement of suprathermal electrons. By combining neutral beam injection with LHCD, an MHD-free condition has been obtained where q(O) is raised above 1

  10. Universal analytical scattering form factor for shell-, core-shell, or homogeneous particles with continuously variable density profile shape.

    Science.gov (United States)

    Foster, Tobias

    2011-09-01

    A novel analytical and continuous density distribution function with a widely variable shape is reported and used to derive an analytical scattering form factor that allows us to universally describe the scattering from particles with the radial density profile of homogeneous spheres, shells, or core-shell particles. Composed by the sum of two Fermi-Dirac distribution functions, the shape of the density profile can be altered continuously from step-like via Gaussian-like or parabolic to asymptotically hyperbolic by varying a single "shape parameter", d. Using this density profile, the scattering form factor can be calculated numerically. An analytical form factor can be derived using an approximate expression for the original Fermi-Dirac distribution function. This approximation is accurate for sufficiently small rescaled shape parameters, d/R (R being the particle radius), up to values of d/R ≈ 0.1, and thus captures step-like, Gaussian-like, and parabolic as well as asymptotically hyperbolic profile shapes. It is expected that this form factor is particularly useful in a model-dependent analysis of small-angle scattering data since the applied continuous and analytical function for the particle density profile can be compared directly with the density profile extracted from the data by model-free approaches like the generalized inverse Fourier transform method. © 2011 American Chemical Society

  11. A Simultaneous Density-Integral System for Estimating Stem Profile and Biomass: Slash Pine and Willow Oak

    Science.gov (United States)

    Bernard R. Parresol; Charles E. Thomas

    1996-01-01

    In the wood utilization industry, both stem profile and biomass are important quantities. The two have traditionally been estimated separately. The introduction of a density-integral method allows for coincident estimation of stem profile and biomass, based on the calculus of mass theory, and provides an alternative to weight-ratio methodology. In the initial...

  12. Probing ultrafast changes of spin and charge density profiles with resonant XUV magnetic reflectivity at the free-electron laser FERMI

    Directory of Open Access Journals (Sweden)

    C. Gutt

    2017-09-01

    Full Text Available We report the results of resonant magnetic XUV reflectivity experiments performed at the XUV free-electron laser FERMI. Circularly polarized XUV light with the photon energy tuned to the Fe M2,3 edge is used to measure resonant magnetic reflectivities and the corresponding Q-resolved asymmetry of a Permalloy/Ta/Permalloy trilayer film. The asymmetry exhibits ultrafast changes on 240 fs time scales upon pumping with ultrashort IR laser pulses. Depending on the value of the wavevector transfer Qz, we observe both decreasing and increasing values of the asymmetry parameter, which is attributed to ultrafast changes in the vertical spin and charge density profiles of the trilayer film.

  13. MGS Radio Science Electron Density Profiles: Interannual Variability and Implications for the Martian Neutral Atmosphere

    Science.gov (United States)

    Bougher, S. W.; Engel, S.; Hinson, D. P.; Murphy, J. R.

    2004-01-01

    Martian electron density profiles provided by the Mars Global Surveyor (MGS) Radio Science (RS) experiment over the 95-200 km altitude range indicate what the height of the electron peak and the longitudinal structure of the peak height are sensitive indicators of the physical state of the Mars lower and upper atmospheres. The present analysis is carried out on five sets of occultation profiles, all at high solar zenith angles (SZA). Variations spanning 2 Martian years are investigated near aphelion conditions at high northern latitudes (64.7 - 77.6 N) making use of four of these data sets. A mean ionospheric peak height of 133.5 - 135 km is obtained near SZA = 78 - 82 deg.; a corresponding mean peak density of 7.3 - 8.5 x l0(exp 4)/ qu cm is also measured during solar moderate conditions at Mars. Strong wave number 2 - 3 oscillations in peak heights are consistently observed as a function of longitude over the 2 Martian years. These observed ionospheric features are remarkably similar during aphelion conditions 1 Martian year apart. This year-to-year repeatability in the thermosphere-ionosphere structure is consistent with that observed in multiyear aphelion temperature data of the Mars lower atmosphere. Coupled Mars general circulation model (MGCM) and Mars thermospheric general circulation model (MTGCM) codes are run for Mars aphelion conditions, yielding mean and longitude variable ionospheric peak heights that reasonably match RS observations. A tidal decomposition of MTGCM thermospheric densities shows that observed ionospheric wave number 3 features are linked to a non-migrating tidal mode with semidiurnal period (sigma = 2) and zonal wave number 1 (s = -1) characteristics. The height of this photochemically determined ionospheric peak should be monitored regularly.

  14. Constraining Saturn's interior density profile from precision gravity field measurement obtained during Grand Finale

    Science.gov (United States)

    Movshovitz, N.; Fortney, J. J.; Helled, R.; Hubbard, W. B.; Mankovich, C.; Thorngren, D.; Wahl, S. M.; Militzer, B.; Durante, D.

    2017-12-01

    The external gravity field of a planetary body is determined by the distribution of mass in its interior. Therefore, a measurement of the external field, properlyinterpreted, tells us about the interior density profile, ρ(r), which in turn can be used to constrain the composition in the interior and thereby learn about theformation mechanism of the planet. Recently, very high precision measurements of the gravity coefficients for Saturn have been made by the radio science instrument on the Cassini spacecraft during its Grand Finale orbits. The resulting coefficients come with an associated uncertainty. The task of matching a given density profile to a given set of gravity coefficients is relatively straightforward, but the question of how to best account for the uncertainty is not. In essentially all prior work on matching models to gravity field data inferences about planetary structure have rested on assumptions regarding the imperfectly known H/He equation of state and the assumption of an adiabatic interior. Here we wish to vastly expand the phase space of such calculations. We present a framework for describing all the possible interior density structures of a Jovian planet constrained by a given set of gravity coefficients and their associated uncertainties. Our approach is statistical. We produce a random sample of ρ(a) curves drawn from the underlying (and unknown) probability distribution of all curves, where ρ is the density on an interior level surface with equatorial radius a. Since the resulting set of density curves is a random sample, that is, curves appear with frequency proportional to the likelihood of their being consistent with the measured gravity, we can compute probability distributions for any quantity that is a function of ρ, such as central pressure, oblateness, core mass and radius, etc. Our approach is also Bayesian, in that it can utilize any prior assumptions about the planet's interior, as necessary, without being overly

  15. Constraining the interior density profile of a Jovian planet from precision gravity field data

    Science.gov (United States)

    Movshovitz, Naor; Fortney, Jonathan J.; Helled, Ravit; Hubbard, William B.; Thorngren, Daniel; Mankovich, Chris; Wahl, Sean; Militzer, Burkhard; Durante, Daniele

    2017-10-01

    The external gravity field of a planetary body is determined by the distribution of mass in its interior. Therefore, a measurement of the external field, properly interpreted, tells us about the interior density profile, ρ(r), which in turn can be used to constrain the composition in the interior and thereby learn about the formation mechanism of the planet. Planetary gravity fields are usually described by the coefficients in an expansion of the gravitational potential. Recently, high precision measurements of these coefficients for Jupiter and Saturn have been made by the radio science instruments on the Juno and Cassini spacecraft, respectively.The resulting coefficients come with an associated uncertainty. And while the task of matching a given density profile with a given set of gravity coefficients is relatively straightforward, the question of how best to account for the uncertainty is not. In essentially all prior work on matching models to gravity field data, inferences about planetary structure have rested on imperfect knowledge of the H/He equation of state and on the assumption of an adiabatic interior. Here we wish to vastly expand the phase space of such calculations. We present a framework for describing all the possible interior density structures of a Jovian planet, constrained only by a given set of gravity coefficients and their associated uncertainties. Our approach is statistical. We produce a random sample of ρ(a) curves drawn from the underlying (and unknown) probability distribution of all curves, where ρ is the density on an interior level surface with equatorial radius a. Since the resulting set of density curves is a random sample, that is, curves appear with frequency proportional to the likelihood of their being consistent with the measured gravity, we can compute probability distributions for any quantity that is a function of ρ, such as central pressure, oblateness, core mass and radius, etc. Our approach is also bayesian, in that

  16. Two-dimensional imaging of edge plasma electron density and temperature by the passive helium emission ratio technique in TJ-II

    International Nuclear Information System (INIS)

    De la Cal, E; Guasp, J

    2011-01-01

    An intensified visible camera looks tangentially at a poloidal limiter where helium recycles, acting as a wide neutral source, and the atomic line emission due to plasma excitation becomes strongly localized there. It includes a bifurcated coherent bundle, each end with a different interference filter to select helium atomic lines, so that two simultaneous filtered images are captured in one single frame. The object of the proposed technique is to apply the well-known helium-beam line-ratio technique to obtain from selected filtered images the two-dimensional (2D) edge plasma n e and T e . The code EIRENE was used to demonstrate that the helium emission from recycling neutrals dominates the emission for the lines of view passing close above the limiter. Since these chords are nearly parallel to magnetic field lines in the emission region, the images can be approximated to poloidal cuts of the plasma emission within the tolerances discussed in the paper. The absolute radial profiles of T e and n e obtained with the method presented here were checked in the TJ-II stellarator to be in relatively good agreement with other diagnostics within a wide range of plasma parameters for both ECRH and NBI plasmas. The method is finally used to get 2D images of edge plasma T e and n e .

  17. Retrieval of Electron Density Profile for KOMPSAT-5 GPS Radio Occultation

    Directory of Open Access Journals (Sweden)

    Woo-Kyoung Lee

    2007-12-01

    Full Text Available The AOPOD (Atmosphere Occultation and Precision Orbit Determination system, the secondary payload of KOMPSAT (KOrea Multi-Purpose SATellite-5 scheduled to be launched in 2010, shall provide GPS radio occultation data. In this paper, we simulated the GPS radio occultation characteristic of KOMPSAT-5 and retrieved electron density profiles using KROPS (KASI Radio Occultation Processing Software. The electron density retrieved from CHAMP (CHAllenging Minisatellite Payload GPS radio occultation data on June 20, 2004 was compared with IRI (International Reference Ionosphere - 2001, PLP (Planar Langmuir Probe, and ionosonde measurements. When the result was compared with ionosonde measurements, the discrepancies were 5 km on the F_2 peak height (hmF_2 and 3×10^{10} el/m^3 on the electron density of the F_2 peak height (NmF_2. By comparing with the Langmuir Probe measurements of CHAMP satellite (PLP, both agrees with 1.6×10^{11} el/m^3 at the height of 365.6 km.

  18. Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors

    Science.gov (United States)

    Mazzola, F.; Wells, J. W.; Pakpour-Tabrizi, A. C.; Jackman, R. B.; Thiagarajan, B.; Hofmann, Ph.; Miwa, J. A.

    2018-01-01

    We demonstrate simultaneous quantization of conduction band (CB) and valence band (VB) states in silicon using ultrashallow, high-density, phosphorus doping profiles (so-called Si:P δ layers). We show that, in addition to the well-known quantization of CB states within the dopant plane, the confinement of VB-derived states between the subsurface P dopant layer and the Si surface gives rise to a simultaneous quantization of VB states in this narrow region. We also show that the VB quantization can be explained using a simple particle-in-a-box model, and that the number and energy separation of the quantized VB states depend on the depth of the P dopant layer beneath the Si surface. Since the quantized CB states do not show a strong dependence on the dopant depth (but rather on the dopant density), it is straightforward to exhibit control over the properties of the quantized CB and VB states independently of each other by choosing the dopant density and depth accordingly, thus offering new possibilities for engineering quantum matter.

  19. Emission spectra from super-critical rippled plasma density profiles illuminated by intense laser pulses

    International Nuclear Information System (INIS)

    Ondarza R, R.; Boyd, T.J.M.

    2000-01-01

    High-order harmonic emission from the interaction of intense femtosecond laser pulses with super-critical plasmas characterized by a rippled density profile at the vacuum-plasma interface has been observed from particle-in-cell (PIC) simulations. A plasma simulation box several laser wavelengths in extent was prepared with a rippled density of a fraction of a laser wavelength. Emission spectra at the very initial stage of the interaction were recorded with spectral characteristics dissimilar to those previously reported in the literature. The reflected light spectra were characterized by a strong emission at the plasma line and by a series of harmonics at multiples of the ripple frequency. Harmonic spectra were obtained for different values of the plasma ripple frequency. In all cases the harmonics were emitted at the precise multiple harmonic number of the ripple frequency. Another important feature apparent from the simulations was that the emission peaks appeared to havea complex structure as compared with those for unrippled plasmas. For the cases when the plasma was rippled the peaks that corresponded to the multiples of the rippled density typically showed a double peak for the first few harmonics. The reflected emission plots for the main laser pulse showed strong emission at the plasma frequency and at multiples of that frequency as reported by the authors in the literature. (Author)

  20. Effects of low central fuelling on density and ion temperature profiles in reversed shear plasmas on JT-60U

    Energy Technology Data Exchange (ETDEWEB)

    Takenaga, H; Ide, S; Sakamoto, Y; Fujita, T [Japan Atomic Energy Agency, Naka Ibaraki 311-0193 (Japan)], E-mail: takenaga.hidenobu@jaea.go.jp

    2008-07-15

    Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.

  1. Effects of low central fuelling on density and ion temperature profiles in reversed shear plasmas on JT-60U

    Science.gov (United States)

    Takenaga, H.; Ide, S.; Sakamoto, Y.; Fujita, T.; JT-60 Team

    2008-07-01

    Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.

  2. Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator.

    Science.gov (United States)

    Hiratsuka, Junichi; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Miyamoto, Kenji; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; Tobari, Hiroyuki

    2016-02-01

    To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

  3. Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Hiratsuka, Junichi, E-mail: hiratsuka.junichi@jaea.go.jp; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; Tobari, Hiroyuki [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka 311-0193 (Japan); Miyamoto, Kenji [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan)

    2016-02-15

    To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

  4. Predicting Near Edge X-ray Absorption Spectra with the Spin-Free Exact-Two-Component Hamiltonian and Orthogonality Constrained Density Functional Theory.

    Science.gov (United States)

    Verma, Prakash; Derricotte, Wallace D; Evangelista, Francesco A

    2016-01-12

    Orthogonality constrained density functional theory (OCDFT) provides near-edge X-ray absorption (NEXAS) spectra of first-row elements within one electronvolt from experimental values. However, with increasing atomic number, scalar relativistic effects become the dominant source of error in a nonrelativistic OCDFT treatment of core-valence excitations. In this work we report a novel implementation of the spin-free exact-two-component (X2C) one-electron treatment of scalar relativistic effects and its combination with a recently developed OCDFT approach to compute a manifold of core-valence excited states. The inclusion of scalar relativistic effects in OCDFT reduces the mean absolute error of second-row elements core-valence excitations from 10.3 to 2.3 eV. For all the excitations considered, the results from X2C calculations are also found to be in excellent agreement with those from low-order spin-free Douglas-Kroll-Hess relativistic Hamiltonians. The X2C-OCDFT NEXAS spectra of three organotitanium complexes (TiCl4, TiCpCl3, TiCp2Cl2) are in very good agreement with unshifted experimental results and show a maximum absolute error of 5-6 eV. In addition, a decomposition of the total transition dipole moment into partial atomic contributions is proposed and applied to analyze the nature of the Ti pre-edge transitions in the three organotitanium complexes.

  5. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    International Nuclear Information System (INIS)

    Yusof, Mohd Fahmi Mohd; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz; Bauk, Sabar; Hashim, Rokiah

    2015-01-01

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ 2 value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ 2 value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies

  6. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Mohd Fahmi Mohd, E-mail: mfahmi@usm.my; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Bauk, Sabar [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Hashim, Rokiah [School of Industrial Technologies, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-29

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ{sup 2} value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ{sup 2} value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies.

  7. Correlation study of actual temperature profile and in-line metrology measurements for within-wafer uniformity improvement and wafer edge yield enhancement (Conference Presentation)

    Science.gov (United States)

    Fang, Fang; Vaid, Alok; Vinslava, Alina; Casselberry, Richard; Mishra, Shailendra; Dixit, Dhairya; Timoney, Padraig; Chu, Dinh; Porter, Candice; Song, Da; Ren, Zhou

    2018-03-01

    It is getting more important to monitor all aspects of influencing parameters in critical etch steps and utilize them as tuning knobs for within-wafer uniformity improvement and wafer edge yield enhancement. Meanwhile, we took a dive in pursuing "measuring what matters" and challenged ourselves for more aspects of signals acquired in actual process conditions. Among these factors which are considered subtle previously, we identified Temperature, especially electrostatic chuck (ESC) Temperature measurement in real etch process conditions have direct correlation to in-line measurements. In this work, we used SensArray technique (EtchTemp-SE wafer) to measure ESC temperature profile on a 300mm wafer with plasma turning on to reproduce actual temperature pattern on wafers in real production process conditions. In field applications, we observed substantial correlation between ESC temperature and in-line optical metrology measurements and since temperature is a process factor that can be tuning through set-temperature modulations, we have identified process knobs with known impact on physical profile variations. Furthermore, ESC temperature profile on a 300mm wafer is configured as multiple zones upon radius and SensArray measurements mechanism could catch such zonal distribution as well, which enables detailed temperature modulations targeting edge ring only where most of chips can be harvested and critical zone for yield enhancement. Last but not least, compared with control reference (ESC Temperature in static plasma-off status), we also get additional factors to investigate in chamber-to-chamber matching study and make process tool fleet match on the basis really matters in production. KLA-Tencor EtchTemp-SE wafer enables Plasma On wafer temperature monitoring of silicon etch process. This wafer is wireless and has 65 sensors with measurement range from 20 to 140°C. the wafer is designed to run in real production recipe plasma on condition with maximum RF power up

  8. Asymmetric Velocity Distributions from Halo Density Profiles in the Eddington Approach

    International Nuclear Information System (INIS)

    Vergados, J. D.

    2015-01-01

    We show how to obtain the energy distribution f(E) in our vicinity starting from WIMP density profiles in a self-consistent way by employing the Eddington approach and adding reasonable angular momentum dependent terms in the expression of the energy. We then show how we can obtain the velocity dispersions and the asymmetry parameter β in terms of the parameters describing the angular momentum dependence. From this expression, for f(E), we proceed to construct an axially symmetric WIMP a velocity distribution, which, for a gravitationally bound system, automatically has a velocity upper bound and is characterized by the same asymmetriy β. This approach is tested and clarified by constructing analytic expressions in a simple model, with adequate structure. We then show how such velocity distributions can be used in determining the event rates, including modulation, in both the standard and the directional WIMP searches.

  9. Density profiles and particle fluxes of heavy impurities in the limiter shadow region of a tokamak

    International Nuclear Information System (INIS)

    Claassen, H.A.; Repp, H.

    1980-01-01

    For the case of low impurity concentration, transport calculations have been performed for heavy impurities, in the scrape-off layer plasma of a tokamak with a poloidal ring limiter. The theory is based on the drift-kinetic equations for the various ionization states of the impurity ions taking due consideration of the convection and collision processes. The background plasma and the impurity sources from the torus wall and the limiter surface enter the theory as input parameters. The theory is developed for the first two orders of the drift approximation. Numerical results are given to zero order drift approximation for the radial profiles of density and particle fluxes parallel to the magnetic field. (orig.)

  10. The control of plasma density profile in Tore Supra. Comparison of different fueling techniques

    International Nuclear Information System (INIS)

    Commaux, N.

    2007-09-01

    The behaviour of a reactor-class plasma when fuelled using the existing techniques (gas puffing, supersonic molecular beam injection and pellet injection) is still very difficult to foresee. The present work has been initiated on Tore Supra in order to extrapolate the consequences of the different fuelling systems on ITER. Two main topics have been studied: the comparison of the plasma behaviour when fuelled using the different techniques at high Greenwald density fractions and the study of the homogenization following a pellet injection (main fuelling technique for ITER burning plasmas). The experiments at high Greenwald density fractions performed on Tore Supra showed that the plasma behaviour is very dependent on the fuelling method. The plasma energy confinement is following the scaling laws determined at low density when fuelled using pellet injection. which is better than for gas puffing and SMBI. both inducing a significant confinement loss. This behaviour is nor related to a transport modification: the ratio between effective diffusion and convection is similar to the pellet case. The difference between these shots is related only to the position of the matter source (at the edge for gas and close to the center for pellets). The study concerning the homogenization phenomena following a pellet injection aims mainly to study the ∇B-drift effect that expels the mater deposited by a pellet toward the low field side. A new phenomenon. which appears to be particularly important for the ∇B-drift during low field side injections. was then discovered: the influence of magnetic surfaces with an integer-valued safety factor (q). When the mater drifting toward low field side crosses an integer q surface. it experiences an important braking effect which stops the drift motion. It implies that the pellet material is mainly deposited on the last integer q surface crossed by the pellet during its injection. This study allows also to determine that the

  11. Anomalous plasma heating induced by modulation of the current-density profile

    International Nuclear Information System (INIS)

    Lopes Cardozo, N.J.

    1985-05-01

    The usual plasma heating in a tokamak needs additional heating to reach ignition temperature (approx. 10 8 K). The method used in the TORTUR III experiment is to induce anomalous plasma resistivity by applying a short (10 microseconds) high-voltage pulse. A sharp rise of the plasma temperature is found almost simultaneously, but this effect, though considerable, is too short-lived to be of interest for a thermonuclear chain reaction. A second pulse gives a second rise of temperature, but this time a slow one, extending over several milliseconds. The mechanism of this delayed heating and the reservoir within the plasma supplying the energy are subjects of investigation in the TORTUR III experiments. Some conclusions concerning the plasma heating mechanism are presented. The conclusion is reached that the application of the high-voltage pulse results in a modulation of the current-density profile: the (normally already peaked) profile sharpens, the current concentrates in the centre of the plasma column. This is a non-equilibrium situation. It relaxes to the noraml current distribution within approximately 2 milliseconds. As long as this relaxation process is not finished, the dissipation is on an enhanced level and anomalous plasma heating is observed. Many plasma parameters are surveyed and evaluated: temperature (both of the ions and the electrons), density, emission spectrum (from microwaves to hard X-rays) and the fluctuation spectrum. Main subject of this report is the measurement and interpretation of the X-rays of the emission spectrum. Experimental results are presented and discussed

  12. Strong orientation dependence of surface mass density profiles of dark haloes at large scales

    Science.gov (United States)

    Osato, Ken; Nishimichi, Takahiro; Oguri, Masamune; Takada, Masahiro; Okumura, Teppei

    2018-06-01

    We study the dependence of surface mass density profiles, which can be directly measured by weak gravitational lensing, on the orientation of haloes with respect to the line-of-sight direction, using a suite of N-body simulations. We find that, when major axes of haloes are aligned with the line-of-sight direction, surface mass density profiles have higher amplitudes than those averaged over all halo orientations, over all scales from 0.1 to 100 Mpc h-1 we studied. While the orientation dependence at small scales is ascribed to the halo triaxiality, our results indicate even stronger orientation dependence in the so-called two-halo regime, up to 100 Mpc h-1. The orientation dependence for the two-halo term is well approximated by a multiplicative shift of the amplitude and therefore a shift in the halo bias parameter value. The halo bias from the two-halo term can be overestimated or underestimated by up to {˜ } 30 per cent depending on the viewing angle, which translates into the bias in estimated halo masses by up to a factor of 2 from halo bias measurements. The orientation dependence at large scales originates from the anisotropic halo-matter correlation function, which has an elliptical shape with the axis ratio of ˜0.55 up to 100 Mpc h-1. We discuss potential impacts of halo orientation bias on other observables such as optically selected cluster samples and a clustering analysis of large-scale structure tracers such as quasars.

  13. Fatty acid profile in patients with phenylketonuria and its relationship with bone mineral density.

    Science.gov (United States)

    Lage, Sergio; Bueno, María; Andrade, Fernando; Prieto, José Angel; Delgado, Carmen; Legarda, María; Sanjurjo, Pablo; Aldámiz-Echevarría, Luis Jose

    2010-12-01

    Patients with phenylketonuria (PKU) undergo a restrictive vegan-like diet, with almost total absence of n-3 fatty acids, which have been proposed as potential contributors to bone formation in the healthy population. The PKU diet might lead these patients to bone mass loss and, consequently, to the development of osteopenia/osteoporosis. Therefore, we proposed to analyze their plasma fatty acid profile status and its relationship with bone health. We recruited 47 PKU patients for this cross-sectional study and divided the cohort into three age groups (6-10 years, 11-18 years, 19-42 years). We measured their plasma fatty acid profile and bone mineral density (BMD) (both at the femoral neck and the lumbar spine). Seventy-seven healthy controls also participated as reference values of plasma fatty acids. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and total n-3 fatty acids were significantly diminished in PKU patients compared with healthy controls. DHA, EPA, and total n-3 fatty acids were also positively associated with bone mineral density (r = 0.83, p = 0.010; r = 0.57, p = 0.006; r = 0.73, p = 0.040, respectively). There was no association between phenylalanine (Phe), Index of Dietary Control (IDC), calcium, 25-hydroxivitamin D concentrations, daily calcium intake, and BMD. Our results suggest a possible influence of essential fatty acids over BMD in PKU patients. The lack of essential n-3 fatty acids intake in the PKU diet might affect bone mineralization. Further clinical trials are needed to confirm the effect of the n-3 essential fatty acids on bone accrual in a cohort of PKU patients.

  14. Edge transport and its interconnection with main chamber recycling in ASDEX upgrade

    International Nuclear Information System (INIS)

    Kallenbach, A.; Dux, R.; Gafert, J.

    2003-01-01

    Edge profiles of electron temperature and density are measured in ASDEX Upgrade with high spatial resolution of 2-3 mm with Thomson scattering. In the region of the edge transport barrier in ELMy H-mode, the gradient lengths of T e and n e are found closely coupled, with the temperature profile twice as steep as the density profile corresponding to η e ∼ 2. The edge density in the region of the barrier foot is closely coupled to the main chamber recycling, with no strong dependence on other parameters. In contrast the density rise from the outer barrier foot to the pedestal exhibits pronounced dependence on plasma current and shaping, indicating quite different mechanisms determining the absolute density and its gradient. (author)

  15. Tidal Disruption of Milky Way Satellites with Shallow Dark Matter Density Profiles

    Directory of Open Access Journals (Sweden)

    Ewa L. Łokas

    2016-11-01

    Full Text Available Dwarf galaxies of the Local Group provide unique possibilities to test current theories of structure formation. Their number and properties have put the broadly accepted cold dark matter model into question, posing a few problems. These problems now seem close to resolution due to the improved treatment of baryonic processes in dwarf galaxy simulations which now predict cored rather than cuspy dark matter profiles in isolated dwarfs with important consequences for their subsequent environmental evolution. Using N-body simulations, we study the evolution of a disky dwarf galaxy with such a shallow dark matter profile on a typical orbit around the Milky Way. The dwarf survives the first pericenter passage but is disrupted after the second due to tidal forces from the host. We discuss the evolution of the dwarf’s properties in time prior to and at the time of disruption. We demonstrate that the dissolution occurs on a rather short timescale as the dwarf expands from a spheroid into a stream with non-zero mean radial velocity. We point out that the properties of the dwarf at the time of disruption may be difficult to distinguish from bound configurations, such as tidally induced bars, both in terms of surface density and line-of-sight kinematics.

  16. Relationship between nutritional profile, measures of adiposity, and bone mineral density in postmenopausal Saudi women.

    Science.gov (United States)

    Alissa, Eman M; Alnahdi, Wafa A; Alama, Nabeel; Ferns, Gordon A

    2014-01-01

    Osteoporosis remains a major health problem in all developed countries and is a condition in which several dietary factors have been implicated. To assess the nutritional status and levels of adiposity of postmenopausal women in relation to bone mineral density. A cross-sectional study in which dietary intake was estimated by a food frequency questionnaire in 300 Saudi postmenopausal women aged 46-88 years. Bone profile biochemistry (serum calcium, phosphate, parathyroid hormone [PTH], vitamin D) and bone mineral density (BMD) in 3 skeletal sites were determined for all participants. Overweight and obesity were highly prevalent among the study population. No significant correlation was found between dietary calcium and vitamin D and bone mass at any site. Dietary intake of calcium and vitamin D was significantly less than the recommended levels for a large proportion of the cohort. Energy-adjusted intakes of carbohydrates, fat, protein, and unsaturated fatty acids were associated with BMD in the postmenopausal women. Age, body weight, and residency type were predictors of BMD at all sites. Serum-intact PTH was a predictor of BMD at lumbar spine and femoral neck. Waist : hip ratio (WHR) was a predictor for BMD at femoral neck. These results suggest that BMD is influenced by dietary factors other than calcium and vitamin D. However, nondietary factors such as age, WHR, PTH, and body weight may be important determinants of BMD in postmenopausal women.

  17. The Surface Density Profile of the Galactic Disk from the Terminal Velocity Curve

    Science.gov (United States)

    McGaugh, Stacy S.

    2016-01-01

    The mass distribution of the Galactic disk is constructed from the terminal velocity curve and the mass discrepancy-acceleration relation. Mass models numerically quantifying the detailed surface density profiles are tabulated. For R0 = 8 kpc, the models have stellar mass 5 spiral galaxy that obeys scaling relations like the Tully-Fisher relation, the size-mass relation, and the disk maximality-surface brightness relation. The stellar disk is maximal, and the spiral arms are massive. The bumps and wiggles in the terminal velocity curve correspond to known spiral features (e.g., the Centaurus arm is a ˜50% overdensity). The rotation curve switches between positive and negative over scales of hundreds of parsecs. The rms amplitude { }1/2≈ 14 {km} {{{s}}}-1 {{kpc}}-1, implying that commonly neglected terms in the Jeans equations may be nonnegligible. The spherically averaged local dark matter density is ρ0,DM ≈ 0.009 {M}⊙ {{pc}}-3 (0.34 {GeV} {{cm}}-3). Adiabatic compression of the dark matter halo may help reconcile the Milky Way with the c-V200 relation expected in ΛCDM while also helping to mitigate the too-big-to-fail problem, but it remains difficult to reconcile the inner bulge/bar-dominated region with a cuspy halo. We note that NGC 3521 is a near twin to the Milky Way, having a similar luminosity, scale length, and rotation curve.

  18. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    International Nuclear Information System (INIS)

    Loi, Shyeh Tjing; Cairns, Iver H.; Li, Bo

    2014-01-01

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency f p to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both f p and 2 f p radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in f p than 2 f p emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 f p radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 f p radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  19. Effects of triangularity on confinement, density limit and profile stiffness of H-modes on ASDEX upgrade

    International Nuclear Information System (INIS)

    Stober, J.; Gruber, O.; Kallenbach, A.; Mertens, V.; Ryter, F.; Staebler, A.; Suttrop, W.; Treutterer, W.

    2000-01-01

    At ASDEX Upgrade the influence of triangularity on the H-mode performance has been studied intensively. It has been found that confinement increases with δ for a fixed line-averaged density. Though confinement decreases with increasing density for all analysed values of δ, H-factors (ITERH-98P) at the Greenwald density could be raised to 1 for the highest δ values achieved so far. The H-mode density limit could be increased by approx. 20%. There is a scatter of about 30% on the confinement data, which is anti-correlated to the average density in the scrape-off layer or the neutral fluxes outside the plasma. For nearly all discharges analysed so far, the temperature profiles are self-similar. This indication of profile stiffness could be verified by changing the heat-flux profile by changing the beam-voltage of the neutral-beam injection (NBI) at high density. At low density, first results indicate a deviation from this stiff behaviour. (author)

  20. Relationship between habitat, densities and metabolic profile in brown hares (Lepus europaeus Pallas

    Directory of Open Access Journals (Sweden)

    Marco Bagliacca

    2010-01-01

    Full Text Available Some habitat traits and haematic parameters were studied to understand the relationships between the hare densities, habitat characteristics and physiological and nutritional condition of the animals. A total of 33 protected areas, reserved for wild game reproduction, located in the Province of Florence (Central Italy, were monitored during a 2-year period. In each protected area the hares were submitted to census. The habitat features of the protected areas were studied and the following parameters were categorised: altitude; cleared-land/total-land ratio; main exposure; main ground composition; water availability; main slope; anthropogenic presence; predator presence; wooded borders; presence of trees and shrubs; surveillance against hunting; demographic predator control; kind of cultivation; unharvested crops for game. After the census the hares were captured for translocation outside in “free” hunting areas. During capture the hares were put in darkened, wooden capture-boxes and remained inside for a variable period of time (10min to 3h. A sample of 3 to 7 hares, captured per year and per each protected area, were removed from the boxes (physically restrained, with covered eyes for blood sample collection, sex, age and live weight determination. The following analyses were performed on frozen plasma samples: ALanine aminoTransferase (ALT, ASpartate aminoTransferase (AST, glucose, cholesterol, Blood Urea Nitrogen (BUN, Ca, P, Mg, Na, K, and Cl concentrations. The relationship between hare density and habitat characteristics was analysed by single regressions analysis. Then the habitat characteristics were subjected to multivariate analysis in relationship to hare body condition. The haematic parameters were analysed by least square means considering habitat traits, animal density, age and sex, as main categorical factors, interaction sex*age, and “pregnant and non-reproducing” nested within sex. Results showed that the highest density

  1. Physics of increased edge electron temperature and density turbulence during ELM-free QH-mode operation on DIII-D

    Science.gov (United States)

    Sung, C.; Rhodes, T. L.; Staebler, G. M.; Yan, Z.; McKee, G. R.; Smith, S. P.; Osborne, T. H.; Peebles, W. A.

    2018-05-01

    For the first time, we report increased edge electron temperature and density turbulence levels ( T˜ e and n˜ e) in Edge Localized Mode free Quiescent H-mode (ELM-free QH-mode) plasmas as compared to the ELMing time period. ELMs can severely damage plasma facing components in fusion plasma devices due to their large transient energy transport, making ELM-free operation a highly sought after goal. The QH-mode is a candidate for this goal as it is ELM-free for times limited only by hardware constraints. It is found that the driving gradients decrease during the QH-mode compared to the ELMing phase, however, a significant decrease in the ExB shearing rate is also observed that taken together is consistent with the increased turbulence. These results are significant as the prediction and control of ELM-free H-mode regimes are crucial for the operation of future fusion devices such as ITER. The changes in the linear growth rates calculated by CGYRO [Candy et al., J. Comput. Phys. 324, 73 (2016)] and the measured ExB shearing rate between ELMing and QH-mode phases are qualitatively consistent with these turbulence changes. Comparison with ELMing and 3D fields ELM suppressed H-mode finds a similar increase in T˜ e and n˜ e, however, with distinctly different origins, the increased driving gradients rather than the changes in the ExB shearing rate in 3D fields ELM suppressed the H-mode. However, linear gyrokinetic calculation results are generally consistent with the increased turbulence in both ELM-controlled discharges.

  2. Note: Interpolation for evaluation of a two-dimensional spatial profile of plasma densities at low gas pressures

    International Nuclear Information System (INIS)

    Oh, Se-Jin; Kim, Young-Chul; Chung, Chin-Wook

    2011-01-01

    An interpolation algorithm for the evaluation of the spatial profile of plasma densities in a cylindrical reactor was developed for low gas pressures. The algorithm is based on a collisionless two-dimensional fluid model. Contrary to the collisional case, i.e., diffusion fluid model, the fitting algorithm depends on the aspect ratio of the cylindrical reactor. The spatial density profile of the collisionless fitting algorithm is presented in two-dimensional images and compared with the results of the diffusion fluid model.

  3. High triglycerides and low high-density lipoprotein cholesterol lipid profile in rheumatoid arthritis: A potential link among inflammation, oxidative status, and dysfunctional high-density lipoprotein.

    Science.gov (United States)

    Rodríguez-Carrio, Javier; Alperi-López, Mercedes; López, Patricia; López-Mejías, Raquel; Alonso-Castro, Sara; Abal, Francisco; Ballina-García, Francisco J; González-Gay, Miguel Á; Suárez, Ana

    The interactions between inflammation and lipid profile in rheumatoid arthritis (RA) are poorly understood. The lipid profile study in RA has been biased toward lipoprotein levels, whereas those of triglycerides (TGs) and lipoprotein functionality have been underestimated. Since recent findings suggest a role for TG and TG-rich lipoproteins (TRL) on inflammation, we aimed to evaluate a combined lipid profile characterized by high TG and low high-density lipoprotein cholesterol levels (TG high HDL low ) in RA. Lipid profiles were analyzed in 113 RA patients, 113 healthy controls, and 27 dyslipemic subjects. Levels of inflammatory mediators, paraoxonase-1 (PON1) activity, and total antioxidant capacity were quantified in serum. PON1-rs662 status was evaluated by real-time polymerase chain reaction. The TG high HDL low profile was detected in 29/113 RA patients. Although no differences in prevalence compared with healthy controls or dyslipemic subjects were observed, this profile was associated with increased tumor necrosis factor α (P = .004), monocyte chemotactic protein (P = .004), interferon-gamma-inducible protein-10 (P = .018), and leptin (P < .001) serum levels in RA, where decreased PON1 activity and total antioxidant capacity were found. TG high HDL low prevalence was lower among anti-TNFα-treated patients (P = .004). When RA patients were stratified by PON1-rs662 status, these associations remained in the low-activity genotype (QQ). Finally, a poor clinical response on TNFα blockade was related to an increasing prevalence of the TG high HDL low profile over treatment (P = .021) and higher TRL levels at baseline (P = .042). The TG high HDL low profile is associated with systemic inflammation, decreased PON1 activity, and poor clinical outcome on TNFα blockade in RA, suggesting a role of TRL and HDL dysfunction as the missing link between inflammation and lipid profile. Copyright © 2017 National Lipid Association. Published by Elsevier Inc

  4. First observation of density profile in directly laser-driven polystyrene targets for ablative Rayleigh-Taylor instability research

    International Nuclear Information System (INIS)

    Fujioka, Shinsuke; Shiraga, Hiroyuki; Nishikino, Masaharu; Shigemori, Keisuke; Sunahara, Atsushi; Nakai, Mitsuo; Azechi, Hiroshi; Nishihara, Katsunobu; Yamanaka, Tatsuhiko

    2003-01-01

    The temporal evolution of the density profile of a directly laser-driven polystyrene target was observed for the first time using an x-ray penumbral imaging technique coupled with side-on x-ray backlighting at the GEKKO XII [C. Yamanaka et al., IEEE J. Quantum Electron. QE-17, 1639 (1981)]-High Intensity Plasma Experimental Research laser facility (I L =0.7x10 14 W/cm 2 , λ L =0.35 μm). This density measurement makes it possible to experimentally confirm all physical parameters [γ(k),k,g,m,ρ a ,L m ] appearing in the modified Takabe formula for the growth rate of the ablative Rayleigh-Taylor instability. The measured density profiles were well reproduced by a one-dimensional hydrodynamic simulation code. The density measurement contributes toward fully understanding the ablative Rayleigh-Taylor instability

  5. 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.

  6. Edge transport barrier formation in compact helical system

    International Nuclear Information System (INIS)

    Okamura, S; Minami, T; Oishi, T; Suzuki, C; Ida, K; Isobe, M; Yoshimura, Y; Nagaoka, K; Toi, K; Fujisawa, A; Akiyama, T; Iguchi, H; Ikeda, R; Kado, S; Matsuoka, K; Matsushita, H; Nakamura, K; Nakano, H; Nishimura, S; Nishiura, M; Ohshima, S; Shimizu, A; Takagi, S; Takahashi, C; Takeuchi, M; Yoshinuma, M

    2004-01-01

    The edge transport barrier (ETB) for particle transport is formed in the neutral beam (NB) heated hydrogen discharges in compact helical system (CHS). The transition to the ETB formation and the back transition are controlled by the heating power. The existence of the heating power threshold is confirmed and it is roughly proportional to the density. The Hα emission signal shows a clear drop at the transition (the timescale of signal decrease is ∼1 ms for the high heating power case). The ETB formation continues for the full duration of NB injection (100 ms) with a moderate level of radiation power loss. Local density profile measurement shows increase of the edge density and the movement of the density gradient region towards the edge

  7. Axisymmetric instability of a self-pinched beam with rounded radial density profile

    International Nuclear Information System (INIS)

    Chen, H.C.; Uhm, H.S.

    1983-01-01

    The axisymmetric perturbations (sausage and hollowing modes) of an intense relativistic self-pinched electron beam propagating in a resistive plasma background are studied, especially for a beam with rounded radial density profile. The Bennett profiles are assumed for both the equilibrium beam current J/sub b/(r) = J/sub b/(0) (1+r 2 /R 2 /sub b/) -2 and plasma return current J/sub p/(r) = -fJ/sub b/(0) (1+r 2 /R 2 /sub p/) -2 , where R/sub b/ and R/sub p/ are the characteristic radii of the beam and plasma return currents, respectively. It is further assumed that the electric conductivity sigma(r) of the plasma channel is proportional to the return current. For a paraxial electron beam with complete space-charge neutralization by the ambient plasma, the axisymmetric modes can be destabilized by the phase lag between the magnetic field and beam current, even without the plasma return current. The plasma return current significantly modifies the growth rate of the instability such that the ratio of plasma current to beam current (-I/sub p//I/sub b/ = fR 2 /sub p// iR 2 /sub b/) largely determines the stability character of the beam. Furthermore, for the same fractional current neutralization f, the modes are highly unstable for a smaller ratio of plasma to beam radius R/sub p//R/sub b/. As compared to the resistive hose instability, the growth rates for the hollowing mode can be larger than those of the hose mode, while the sausage mode is much stabler than the hose mode. Stability properties are illustrated in detail for various system parameters

  8. Formulation of detector response function to calculate the power density profiles using in-core neutron detectors

    International Nuclear Information System (INIS)

    Ahmed, S. A.; Peter, J. K.; Semmler, W.; Shultis, J. K.

    2007-01-01

    By measuring neutron fluxes at different locations throughout a core, it's possible to derive the power-density profile P k (W cm - 3), at an axial depth z of fuel rod k. Micro-pocket fission detectors (MPFD) have been fabricated to perform such in-core neutron flux measurements. The purpose of this study is to develop a mathematical model to obtain axial power density distributions in the fuel rods from the in-core responses of the MPFDs

  9. Modeling and control of the current density profile in Tokamaks and its relation to electron transport

    International Nuclear Information System (INIS)

    Zucca, C.

    2009-04-01

    The current density in tokamak plasmas strongly affects transport phenomena, therefore its understanding and control represent a crucial challenge for controlled thermonuclear fusion. Within the vast framework of tokamak studies, three topics have been tackled in the course of the present thesis: first, the modelling of the current density evolution in electron Internal Transport Barrier (eITB) discharges in the Tokamak à Configuration Variable (TCV); second, the study of current diffusion and inversion of electron transport properties observed during Swing Electron Cyclotron Current Drive (Swing ECCD) discharges in TCV; third, the analysis of the current density tailoring obtained by local ECCD driven by the improved EC system for sawtooth control and reverse shear scenarios in the International Thermonuclear Experimental Reactor (ITER). The work dedicated to the study of eITBs in TCV has been undertaken to identify which of the main parameters, directly related to the current density, played a relevant role in the confinement improvement created during these advanced scenarios. In this context, the current density has to be modeled, there being no measurement currently available on TCV. Since the Rebut-Lallia-Watkins (RLW) model has been validated on TCV ohmic heated plasmas, the corresponding scaling factor has often been used as a measure of improved confinement on TCV. The many interpretative simulations carried on different TCV discharges have shown that the thermal confinement improvement factor, H RLW , linearly increases with the absolute value of the minimum shear outside ρ > 0.3, ρ indicating a normalized radial coordinate. These investigations, performed with the transport code ASTRA, therefore confirmed a general observation, formulated through previous studies, that the formation of the transport barrier is correlated with the magnetic shear reversal. This was, indeed, found to be true in all cases studied, regardless of the different heating and

  10. Novel lipoprotein density profiling in healthy dogs of various breeds, healthy miniature schnauzers, and miniature schnauzers with hyperlipidemia

    Science.gov (United States)

    2013-01-01

    Background Despite the importance of abnormalities in lipoprotein metabolism in clinical canine medicine, the fact that most previously used methods for lipoprotein profiling are rather laborious and time-consuming has been a major obstacle to the wide clinical application and use of lipoprotein profiling in this species. The aim of the present study was to assess the feasibility of a continuous lipoprotein density profile (CLPDP) generated within a bismuth sodium ethylenediaminetetraacetic acid (NaBiEDTA) density gradient to characterize and compare the lipoprotein profiles of healthy dogs of various breeds, healthy Miniature Schnauzers, and Miniature Schnauzers with primary hypertriacylglycerolemia. A total of 35 healthy dogs of various breeds with serum triacylglycerol (TAG) and cholesterol concentrations within their respective reference intervals were selected for use as a reference population. Thirty-one Miniature Schnauzers with serum TAG and cholesterol concentrations within their respective reference intervals and 31 Miniature Schnauzers with hypertriacylglyceridemia were also included in the study. Results The results suggest that CLPDP using NaBiEDTA provides unique diagnostic information in addition to measurements of serum TAG and cholesterol concentrations and that it is a useful screening method for dogs with suspected lipoprotein metabolism disorders. Using the detailed and continuous density distribution information provided by the CLPDP, important differences in lipoprotein profiles can be detected even among dogs that have serum TAG and cholesterol concentrations within the reference interval. Miniature Schnauzers with serum TAG and cholesterol concentrations within the reference interval had significantly different lipoprotein profiles than dogs of various other breeds. In addition, it was further established that specific lipoprotein fractions are associated with hypertriacylglyceridemia in Miniature Schnauzers. Conclusions The results of the

  11. Density profile of dark matter haloes and galaxies in the HORIZON-AGN simulation: the impact of AGN feedback

    Science.gov (United States)

    Peirani, Sébastien; Dubois, Yohan; Volonteri, Marta; Devriendt, Julien; Bundy, Kevin; Silk, Joe; Pichon, Christophe; Kaviraj, Sugata; Gavazzi, Raphaël; Habouzit, Mélanie

    2017-12-01

    Using a suite of three large cosmological hydrodynamical simulations, HORIZON-AGN, HORIZON–NOAGN (no AGN feedback) and HORIZON-DM (no baryons), we investigate how a typical sub-grid model for AGN feedback affects the evolution of the inner density profiles of massive dark matter haloes and galaxies. Based on direct object-to-object comparisons, we find that the integrated inner mass and density slope differences between objects formed in these three simulations (hereafter, HAGN, HnoAGN and HDM) significantly evolve with time. More specifically, at high redshift (z ∼ 5), the mean central density profiles of HAGN and HnoAGN dark matter haloes tend to be much steeper than their HDM counterparts owing to the rapidly growing baryonic component and ensuing adiabatic contraction. By z ∼ 1.5, these mean halo density profiles in HAGN have flattened, pummelled by powerful AGN activity ('quasar mode'): the integrated inner mass difference gaps with HnoAGN haloes have widened, and those with HDM haloes have narrowed. Fast forward 9.5 billion years, down to z = 0, and the trend reverses: HAGN halo mean density profiles drift back to a more cusped shape as AGN feedback efficiency dwindles ('radio mode'), and the gaps in integrated central mass difference with HnoAGN and HDM close and broaden, respectively. On the galaxy side, the story differs noticeably. Averaged stellar profile central densities and inner slopes are monotonically reduced by AGN activity as a function of cosmic time, resulting in better agreement with local observations.

  12. An edge pedestal model

    International Nuclear Information System (INIS)

    Stacev, W.M.

    2001-01-01

    A new model for calculation of the gradient scale lengths in the edge pedestal region and of the edge transport barrier width in H-mode tokamak plasmas will be described. Model problem calculations which demonstrate the promise of this model for predicting experimental pedestal properties will be discussed. The density and Prague gradient scale lengths (L) in the edge are calculated from the particle and ion and electron energy radial transport equations, making use of (presumed) known particle and energy fluxes flowing across the edge transport barrier from the core into the SOL and of edge transport coefficients. The average values of the particle and heat fluxes in the edge transport barrier are calculated in terms of the fluxes crossing into the SOL and the atomic physics reaction rates (ionisation, charge-exchange, elastic scattering, impurity radiation) in the edge by integrating the respective transport equations from the pedestal to the separatrix. An important implication of this model is that the pedestal gradient scale lengths depend not just on local pedestal platers properties but also on particle and energy fluxes from the core plasma and on recycling neutral fluxes that penetrate into the plasma edge, both of which in turn depend on the pedestal properties. The MHD edge pressure gradient constraint α≤ α C is used to determine the pressure width of the edge transport barrier, Δ TB = Δ TB (α c ). Three different models for the MHD edge pressure gradient constraint have been investigated: (1) nominal ideal ballooning mode theory, (2) ballooning mode theory taking into account the edge geometry and shear to access He second stability region; and pedestal β-limit theory when the ballooning modes are stabilised by diamagnetic effects. A series of calculations have been made for a DIII-D model problem. The calculated gradient scale lengths and edge transport barrier widths are of the magnitude of values observed experimentally, and certain trends

  13. Role of ion magnetization in formation of radial density profile in magnetically expanding plasma produced by helicon antenna

    Science.gov (United States)

    Yadav, Sonu; Ghosh, Soumen; Bose, Sayak; Barada, Kshitish K.; Pal, Rabindranath; Chattopadhyay, Prabal K.

    2018-04-01

    Experimentally, the density profile in the magnetic nozzle of a helicon antenna based plasma device is seen to be modified from being centrally peaked to that of hollow nature as the external magnetic field is increased. It occurs above a characteristic field value when the ions become magnetized in the expansion chamber. The density profile in the source chamber behind the nozzle, however, remains peaked on-axis irrespective of the magnetic field. The electron temperature there is observed to be hollow and this nature is carried to the expansion chamber along the field line. In the electron energy distribution near the off axis peak location, a high energy tail exists. Rotation of these tail electrons in the azimuthal direction due to the gradient-B drift in the expansion chamber leads to an additional off-axis ionization and forms the hollow density profile. It seems that if the ions are not magnetized, then the off-axially produced additional plasma is not confined and the density profile retains the on-axis peak nature. The present experiment successfully demonstrates how the knowledge of the ion magnetization together with tail electrons significantly contributes to the design of an efficient helicon plasma based thruster.

  14. Density profile and cholesterol concentration of serum lipoproteins in experimental animals and human subjects on hypercholesterolaemic diets

    NARCIS (Netherlands)

    Beynen, A.C.; Terpstra, A.H.M.

    1984-01-01

    1. 1. The density profile of Sudan black stained serum lipoproteins was studied in human subjects and various animal species on diets supplemented with cholesterol. 2. 2. In the animals studied (rabbits, calves, mice, chickens, rats and guinea-pigs), the feeding of cholesterol resulted in an

  15. Expression profiling on high-density DNA grids to detect novel targets in dendritic cells

    International Nuclear Information System (INIS)

    Weissmann, M.

    2000-10-01

    Gene expression analyzes on a large scale using DNA microarrays is a novel approach to study transcription of thousands of genes in parallel. By comparing gene expression profiles of different cell-types and of cells in different activation, novel regulatory networks will be identified that are unique to a cell-type and hence, important in its biological function. Among the differentially expressed genes many novel drug targets will be found. The Genetic department of the Novartis Research Institute was following this approach to identify novel genes, which are critical in the antigen presenting function of DCs and could become promising drug targets. Drugs that modulate effector functions of DCs towards induction of energy or tolerance in T-cells could be useful in the treatment of chronic inflammatory or autoimmune diseases. By using specific robotics equipment high-density cDNA grids on nylon membranes have been produced for hybridizations with various radioactive labeled DNA probes. By our format, based on 384 well plates and limited by the resolution power of our current image analysis software, 27.648 cDNA clones, bacterial colonies or pure DNA, were spotted on one filter. For RNA profiling, we generated filters containing a collection of genes expressed in peripheral blood DCs or monocytes and characterized by oligonucleotide fingerprinting (ONF) as being differentially expressed. The gene collection contained many unknown genes. Sequence analysis of to date 18.000 cDNA clones led to an estimate of 5.000 non-redundant genes being represented in the collection. 10 % of them are either completely unknown or homologous to rare ESTs (expressed sequence tags) in the public EST database. These clones occurred predominantly in small fingerprint clusters and were therefore assumed to be rarely expressed in DCs or monocytes. Some of those genes may become novel drug targets if their expression is DC specific or induced by external stimuli driving DCs into

  16. Direct detection of albedo neutron decay electrons at the inner edge of the radiation belt and experimental determination of neutron density in near-Earth space

    Science.gov (United States)

    Li, X.; Selesnick, R.; Schiller, Q. A.; Zhang, K.; Zhao, H.; Baker, D. N.; Temerin, M. A.

    2017-12-01

    The galaxy is filled with cosmic ray particles, mostly protons with kinetic energy above hundreds of mega-electron volts (MeV). Soon after the discovery of Earth's Van Allen radiation belts almost six decades ago, it was recognized that the main source of inner belt protons, with kinetic energies of tens to hundreds of MeV, is Cosmic Ray Albedo Neutron Decay (CRAND). In this process, cosmic rays reaching the upper atmosphere from throughout the galaxy interact with neutral atoms to produce albedo neutrons which, being unstable to 𝛽 decay, are a potential source of geomagnetically trapped protons and electrons. Protons retain most of the neutrons' kinetic energy while the electrons have lower energies, mostly below 1 MeV. The viability of the electron source was, however, uncertain because measurements showed that electron intensity can vary greatly while the neutron decay rate should be almost constant. Recent measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard the Colorado Student Space Weather Experiment (CSSWE) CubeSat now show that CRAND is the main electron source for the radiation belt near its inner edge, and also contributes to the inner belt elsewhere. Furthermore, measurement of the CRAND electron intensity provides the first experimental determination of the neutron density in near-Earth space, 2x10-9/cm3, confirming earlier theoretical estimates.

  17. Assignment of near-edge x-ray absorption fine structure spectra of metalloporphyrins by means of time-dependent density-functional calculations

    International Nuclear Information System (INIS)

    Schmidt, Norman; Fink, Rainer; Hieringer, Wolfgang

    2010-01-01

    The C 1s and N 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of three prototype tetraphenyl porphyrin (TPP) molecules are discussed in the framework of a combined experimental and theoretical study. We employ time-dependent density-functional theory (TDDFT) to compute the NEXAFS spectra of the open- and closed-shell metalloporphyrins CoTPP and ZnTPP as well as the free-base 2HTPP in realistic nonplanar conformations. Using Becke's well-known half-and-half hybrid functional, the computed core excitation spectra are mostly in good agreement with the experimental data in the low-energy region below the appropriate ionization threshold. To make these calculations feasible, we apply a new, simple scheme based on TDDFT using a modified single-particle input spectrum. This scheme is very easy to implement in standard codes and allows one to compute core excitation spectra at a similar cost as ordinary UV/vis spectra even for larger molecules. We employ these calculations for a detailed assignment of the NEXAFS spectra including subtle shifts in certain peaks of the N 1s spectra, which depend on the central coordination of the TPP ligand. We furthermore assign the observed NEXAFS resonances to the individual molecular subunits of the investigated TPP molecules.

  18. Angular filter refractometry analysis using simulated annealing [An improved method for characterizing plasma density profiles using angular filter refractometry

    International Nuclear Information System (INIS)

    Angland, P.; Haberberger, D.; Ivancic, S. T.; Froula, D. H.

    2017-01-01

    Here, a new method of analysis for angular filter refractometry images was developed to characterize laser-produced, long-scale-length plasmas using an annealing algorithm to iterative converge upon a solution. Angular filter refractometry (AFR) is a novel technique used to characterize the density pro files of laser-produced, long-scale-length plasmas. A synthetic AFR image is constructed by a user-defined density profile described by eight parameters, and the algorithm systematically alters the parameters until the comparison is optimized. The optimization and statistical uncertainty calculation is based on a minimization of the χ2 test statistic. The algorithm was successfully applied to experimental data of plasma expanding from a flat, laser-irradiated target, resulting in average uncertainty in the density profile of 5-10% in the region of interest.

  19. Improved density profile measurements in the C-2U advanced beam-driven Field-Reversed Configuration (FRC) plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Beall, M., E-mail: mbeall@trialphaenergy.com; Deng, B. H.; Gota, H. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

    2016-11-15

    In the prior C-2 experiment, electron density was measured using a two-color 6-chord CO{sub 2}/HeNe interferometer. Analysis shows that high-frequency common mode phase noise can be reduced by a factor of 3 by constructing a reference chord. In the system upgrade from C-2 to C-2U a 4-chord far-infrared laser interferometer was developed, which demonstrated superior sensitivity (1 × 10{sup 16} m{sup −2} at >1 MHz bandwidth) and solved the under spatial sampling issue of the C-2 interferometer system. Improved density-profile measurement results are presented in this paper, including evidence of fast-ion modified density profile and stabilization of the n = 1 plasma wobble mode.

  20. THE INITIAL MASS FUNCTION AND THE SURFACE DENSITY PROFILE OF NGC 6231

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Hwankyung [Department of Astronomy and Space Science, Sejong University, 98, Kunja-dong, Kwangjin-gu, Seoul 143-747 (Korea, Republic of); Sana, Hugues [Astronomical Institute ' Anton Pannekeok' , Amsterdam University, Science Park 904, 1098-XH Amsterdam (Netherlands); Bessell, Michael S., E-mail: sungh@sejong.ac.kr, E-mail: H.Sana@uva.nl, E-mail: bessell@mso.anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University, MSO, Cotter Road, Weston, ACT 2611 (Australia)

    2013-02-01

    We have performed new wide-field photometry of the young open cluster NGC 6231 to study the shape of the initial mass function (IMF) and mass segregation. We also investigated the reddening law toward NGC 6231 from optical to mid-infrared color excess ratios, and found that the total-to-selective extinction ratio is R{sub V} = 3.2, which is very close to the normal value. But many early-type stars in the cluster center show large color excess ratios. We derived the surface density profiles of four member groups, and found that they reach the surface density of field stars at about 10', regardless of stellar mass. The IMF of NGC 6231 is derived for the mass range 0.8-45 M{sub Sun }. The slope of the IMF of NGC 6231 ({Gamma} = -1.1 {+-} 0.1) is slightly shallower than the canonical value, but the difference is marginal. In addition, the mass function varies systematically, and is a strong function of radius-it is very shallow at the center, and very steep at the outer ring suggesting the cluster is mass segregated. We confirm the mass segregation for the massive stars (m {approx}> 8 M{sub Sun }) by a minimum spanning tree analysis. Using a Monte Carlo method, we estimate the total mass of NGC 6231 to be about 2.6 ({+-} 0.6) Multiplication-Sign 10{sup 3} M{sub Sun }. We constrain the age of NGC 6231 by comparison with evolutionary isochrones. The age of the low-mass stars ranges from 1 to 7 Myr with a slight peak at 3 Myr. However, the age of the high-mass stars depends on the adopted models and is 3.5 {+-} 0.5 Myr from the non-rotating or moderately rotating models of Brott et al. as well as the non-rotating models of Ekstroem et al. But the age is 4.0-7.0 Myr if the rotating models of Ekstroem et al. are adopted. This latter age is in excellent agreement with the timescale of ejection of the high-mass runaway star HD 153919 from NGC 6231, albeit the younger age cannot be entirely excluded.

  1. Reconstruction of intra-bundle fission density profile during a postulated LOCA in a CANDU reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ilas, D. [Oak Ridge National Laboratory (United States); Rahnema, F. [Georgia Inst. of Technology (United States); Nuclear and Radiological Engineering/Medical Physics Programs, George W. Woodruff School, Georgia Inst. of Technology, Atlanta, GA 30332-0405 (United States); Serghiuta, D. [Canadian Nuclear Safety Commission (Canada); Sarsour, H.; Turinsky, P. J. [North Carolina State Univ. (United States); Stamm' ler, R. [Studsvik Scandpower AS (Norway)

    2006-07-01

    In this paper, results related to the reconstruction of intra-bundle fission density profile for a 37-pin CANDU-6 bundle with the highest enthalpy deposition during a postulated large LOCA stagnation break in a Bruce B core are presented. Bruce B is a nuclear power plant in Kincardine, Ontario (Canada)), on the shores of Lake Huron with 4 CANDU reactors that are rated at about 750 MWe. The reconstruction of the fuel pin fission densities is based on steady-state, three-dimensional simulations with the Monte Carlo code MCNP for a subset of 27 out of 69 time steps during the first two seconds of the power pulse predicted for the fuel bundle at core location V13/8. Two-group cross section data libraries are generated for MCNP at each time step by the lattice depletion neutron transport code HELIOS-1.7. To include the effect of the surrounding core environment, the calculations are performed with time-dependent albedo boundary conditions inferred from a full core simulation of the transient by the nodal diffusion code NESTLE with HELIOS homogenized cross-sections. It is found that the local peaking factor (LPF) in the outer ring varies during the transient, but never exceeds its value before the transient. Inclusion of the core environment increases the LPF in the outer ring. For the analyzed case, the increase is 0.72% with a relative error of 0.01% for the LPF before the transient and 0.55% (with a relative error of 0.01%) for the maximum average LPF during the transient. The latter is based on only four selected transient time points. Note that the immediate environment of the 'hot bundle' does not contain any reactivity devices or other perturbing factors. As a result, the increases observed in the LPF in the outer ring may not be representative of the situations in which 'other' core environment perturbing factors are present. To determine the effect of these factors on the LPF, further analyses of a bundle in the proximity of control devices

  2. Stellar Populations in the Central 0.5 pc of the Galaxy. I. A New Method for Constructing Luminosity Functions and Surface-density Profiles

    Science.gov (United States)

    Do, T.; Lu, J. R.; Ghez, A. M.; Morris, M. R.; Yelda, S.; Martinez, G. D.; Wright, S. A.; Matthews, K.

    2013-02-01

    We present new high angular resolution near-infrared spectroscopic observations of the nuclear star cluster surrounding the Milky Way's central supermassive black hole. Using the integral-field spectrograph OSIRIS on Keck II behind the laser-guide-star adaptive optics system, this spectroscopic survey enables us to separate early-type (young, 4-6 Myr) and late-type (old, >1 Gyr) stars with a completeness of 50% down to K' = 15.5 mag, which corresponds to ~10 M ⊙ for the early-type stars. This work increases the radial extent of reported OSIRIS/Keck measurements by more than a factor of three from 4'' to 14'' (0.16 to 0.56 pc), along the projected disk of young stars. For our analysis, we implement a new method of completeness correction using a combination of star-planting simulations and Bayesian inference. We assign probabilities for the spectral type of every source detected in deep imaging down to K' = 15.5 mag using information from spectra, simulations, number counts, and the distribution of stars. The inferred radial surface-density profiles, Σ(R)vpropR -Γ, for the young stars and late-type giants are consistent with earlier results (Γearly = 0.93 ± 0.09, Γlate = 0.16 ± 0.07). The late-type surface-density profile is approximately flat out to the edge of the survey. While the late-type stellar luminosity function is consistent with the Galactic bulge, the completeness-corrected luminosity function of the early-type stars has significantly more young stars at faint magnitudes compared with previous surveys with similar depth. This luminosity function indicates that the corresponding mass function of the young stars is likely less top-heavy than that inferred from previous surveys.

  3. Carbon K-edge X-ray absorption spectroscopy and time-dependent density functional theory examination of metal-carbon bonding in metallocene dichlorides.

    Science.gov (United States)

    Minasian, Stefan G; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Kozimor, Stosh A; Martin, Richard L; Shuh, David K; Tyliszczak, Tolek; Vernon, Louis J

    2013-10-02

    Metal-carbon covalence in (C5H5)2MCl2 (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a1* and 1b2* orbitals. The peak intensities, which are directly related to the M-(C5H5) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (C5H5)2TiCl2 to 0.31(3) and 0.75(8) for (C5H5)2ZrCl2, and finally to 0.54(5) and 0.83(8) for (C5H5)2HfCl2. The experimental trend toward increased peak intensity for transitions associated with 1a1* and 1b2* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (C5H5)2TiCl2; 0.21 and 0.73, (C5H5)2ZrCl2; 0.35 and 0.69, (C5H5)2HfCl2] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a1* and 1b2* orbitals [8.2 and 23.4%, (C5H5)2TiCl2; 15.3 and 39.7%, (C5H5)2ZrCl2; 20.1 and 50.9%, (C5H5)2HfCl2]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M-Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands.

  4. Restricted primitive model for electrical double layers: modified HNC theory of density profiles and Monte Carlo study of differential capacitance

    International Nuclear Information System (INIS)

    Ballone, P.; Pastore, G.; Tosi, M.P.

    1986-02-01

    Interfacial properties of an ionic fluid next to a uniformly charged planar wall are studied in the restricted primitive model by both theoretical and Monte Carlo methods. The system is a 1:1 fluid of equisized charged hard spheres in a state appropriate to 1M aqueous electrolyte solutions. The interfacial density profiles of counterions and coions are evaluated by extending the hypernetted chain approximation (HNC) to include the leading bridge diagrams for the wall-ion correlations. The theoretical results compare well with those of grand canonical Monte Carlo computations of Torrie and Valleau over the whole range of surface charge density considered by these authors, thus resolving the earlier disagreement between statistical mechanical theories and simulation data at large charge densities. In view of the importance of the model as a testing ground for theories of the diffuse layer, the Monte Carlo calculations are tested by considering alternative choices for the basic simulation cell and are extended so as to allow an evaluation of the differential capacitance of the model interface by two independent methods. These involve numerical differentiation of the mean potential drop as a function of the surface charge density or alternatively an appropriate use of a fluctuation theory formula for the capacitance. The results of these two Monte Carlo approaches consistently indicate an initially smooth increase of the diffuse layer capacitance followed by structure at large charge densities, this behaviour being connected with layering of counterions as already revealed in the density profiles reported by Torrie and Valleau. (author)

  5. Implementation of reflectometry as a standard density profile diagnostic on DIII-D

    International Nuclear Information System (INIS)

    Zeng, L.; Doyle, E. J.; Luce, T. C.; Peebles, W. A.

    2001-01-01

    The profile reflectometer system on the DIII-D tokamak has been significantly upgraded in order to improve time coverage, data quality, and profile availability. The performance of the reflectometer system, which utilizes continuous frequency modulated (FMCW) radar techniques, has been improved as follows: First, a new PC-based data acquisition system has been installed, providing higher data sampling rates and larger memory depth. The higher sampling rate enables use of faster frequency sweeps of the FMCW microwave source, improving time resolution, and increasing profile accuracy. The larger memory depth enables longer data records, so that profiles can now be obtained throughout 5 s discharges at 100 Hz profile measurement rates, while continuous sampling at 10 MHz is available for 1 s for high time resolution physics studies. Second, an initial automated between-shots profile analysis capability is now available. Third, availability of the profiles to end users has been significantly improved

  6. Design of an O-mode frequency modulated reflectometry system for the measurement of Alborz Tokamak plasma density profile

    Energy Technology Data Exchange (ETDEWEB)

    Koohestani, Saeideh [Department of Energy Engineering and physics, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of); Amrollahi, Reza, E-mail: amrollahi@aut.ac.ir [Department of Energy Engineering and physics, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of); Moradi, Gholamreza [Department of Electrical Engineering, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of)

    2016-12-15

    Reflectometry is a common method for plasma diagnostic, in which microwaves are launched into the plasma and reflected at the critical surfaces. Comparing the reflected microwave signals with the launched waves would give rise to the plasma density profiles. In the present study, an ordinary mode (O-mode) frequency modulation (FM) reflectometry system has been designed for the electron density profile measurement of the Alborz Tokamak plasma. This system has been considered to operate at K-band (18–26.5 GHz) frequency range and scan the frequency band between 18 to 26 GHz in 40 μS. The density profile from major radius r = 47.9–51.55 cm can be measured in Alborz Tokamak plasma. Based on the Alborz Tokamak operational conditions, the characteristic frequencies, and some dimensional limitations, all parts of reflectometer have been designed so that an appropriate efficiency with minimum attenuation, especially in transmitting/receiving system would be achieved. A dual antenna and an oversized waveguide of X-band (8–12 GHz) for transmitting and receiving purposes and a balanced detector for absolute phase determination have been utilized. The details of the Alborz Tokamak FM reflectometry components focusing on the antenna and waveguide design and mounting are described in this paper. Additionally, the procedure of plasma profile reconstruction using the system output signal is discussed. This system uses signal phase shift to determine the position of the cutoff layer.

  7. Changes in density fluctuations associated with confinement transitions close to a rational edge rotational transform in the W7-AS stellarator

    DEFF Research Database (Denmark)

    Zoletnik, S,; Basse, Nils Plesner; Saffman, Mark

    2002-01-01

    At certain values of the edge rotational transform t(a), the confinement quality of plasmas in the Wendelstein 7-AS (W7-AS) stellarator is found to react very sensitively to small modifications of the edge rotational transform t(a). As t(a) can be reproducibly changed, either by external fields o...

  8. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  9. Prospects for steady-state tokamak reactor operation through feedback control of the current density profile

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, D

    1994-12-31

    A brief overview of the most relevant experiments on current profile modifications, strong improvements with respect to the usual L-mode scaling laws and Troyon beta limit is presented, as relevant issues for most tokamaks. Practical means and scenarios for producing and maintaining the optimum current profiles in the various phases of the thermonuclear discharge (profile formation, current ramp-up, burn phase) are proposed. (author). 34 refs., 3 figs.

  10. Measurements of Pfirsch-Schlueter current and pressure profile for the high density ECH plasmas in Heliotron DR

    International Nuclear Information System (INIS)

    Morimoto, S.; Yanagi, N.; Nakasuga, M.; Obiki, T.; Iiyoshi, A.; Uo, K.

    1988-01-01

    The Pfirsch-Schlueter current and pressure profiles are estimated from magnetic measurements for high density electron cyclotron heating (ECH) plasmas (n-bar e =(2-3)x10 13 cm -3 , T e0 =200-400 eV, (β) 0 (1-(r/a) 2 ) s , is about two in macroscopically stable plasmas. A fast loss of plasma energy from the centre to the periphery is observed during the onset of the MHD instability. This method of measuring the pressure profile shape is simple and useful for heliotron type devices. (author). 20 refs, 8 figs, 1 tab

  11. Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources

    International Nuclear Information System (INIS)

    Christ-Koch, Sina

    2007-01-01

    This work shows the application of the Laserdetachment method for spatially resolved measurements of negative Hydrogen/Deuterium ion density. It was applied on a high power low pressure RF-driven ion source. The Laser detachment method is based on the measurement of electron currents on a positively biased Langmuir probe before and during/after a laser pulse. The density ratio of negative ions to electrons can be derived from the ratio of currents to the probe. The absolute density of negative ions can be obtained when the electron density is measured with the standard Langmuir probe setup. Measurements with the Langmuir probe additionally yield information about the floating and plasma potential, the electron temperature and the density of positive ions. The Laser detachment setup had to be adapted to the special conditions of the RF-driven source. In particular the existence of RF fields (1 MHz), high source potential (-20 kV), magnetic fields (∝ 7 mT) and caesium inside the source had to be considered. The density of negative ions could be identified in the range of n(H - )=1.10 17 1/m 3 , which is in the same order of magnitude as the electron density. Only the application of the Laser detachment method with the Langmuir probe measurements will yield spatially resolved plasma parameters and H- density profiles. The influence of diverse external parameters, such as pressure, RF-power, magnetic fields on the plasma parameters and their profiles were studied and explained. Hence, the measurements lead to a detailed understanding of the processes inside the source. (orig.)

  12. Density limit experiments on FTU

    International Nuclear Information System (INIS)

    Pucella, G.; Tudisco, O.; Apicella, M.L.; Apruzzese, G.; Artaserse, G.; Belli, F.; Boncagni, L.; Botrugno, A.; Buratti, P.; Calabrò, G.; Castaldo, C.; Cianfarani, C.; Cocilovo, V.; Dimatteo, L.; Esposito, B.; Frigione, D.; Gabellieri, L.; Giovannozzi, E.; Bin, W.; Granucci, G.

    2013-01-01

    One of the main problems in tokamak fusion devices concerns the capability to operate at a high plasma density, which is observed to be limited by the appearance of catastrophic events causing loss of plasma confinement. The commonly used empirical scaling law for the density limit is the Greenwald limit, predicting that the maximum achievable line-averaged density along a central chord depends only on the average plasma current density. However, the Greenwald density limit has been exceeded in tokamak experiments in the case of peaked density profiles, indicating that the edge density is the real parameter responsible for the density limit. Recently, it has been shown on the Frascati Tokamak Upgrade (FTU) that the Greenwald density limit is exceeded in gas-fuelled discharges with a high value of the edge safety factor. In order to understand this behaviour, dedicated density limit experiments were performed on FTU, in which the high density domain was explored in a wide range of values of plasma current (I p = 500–900 kA) and toroidal magnetic field (B T = 4–8 T). These experiments confirm the edge nature of the density limit, as a Greenwald-like scaling holds for the maximum achievable line-averaged density along a peripheral chord passing at r/a ≃ 4/5. On the other hand, the maximum achievable line-averaged density along a central chord does not depend on the average plasma current density and essentially depends on the toroidal magnetic field only. This behaviour is explained in terms of density profile peaking in the high density domain, with a peaking factor at the disruption depending on the edge safety factor. The possibility that the MARFE (multifaced asymmetric radiation from the edge) phenomenon is the cause of the peaking has been considered, with the MARFE believed to form a channel for the penetration of the neutral particles into deeper layers of the plasma. Finally, the magnetohydrodynamic (MHD) analysis has shown that also the central line

  13. Determination of electron temperature and density at plasma edge in the Large Helical Device with opacity-incorporated helium collisional-radiative model

    International Nuclear Information System (INIS)

    Goto, M.; Sawada, K.

    2014-01-01

    Spectra of neutral helium in the visible wavelength range are measured for a discharge in the Large Helical Device (LHD). The electron temperature (T e ) and density (n e ) are derived from the intensity distribution of helium emission lines. For that purpose, a collisional-radiative model developed by Sawada et al. [Plasma and Fusion Res. 2010;5:001] which takes the reabsorption effect into account is used. It is found that incorporation of the reabsorption effect is necessary to obtain a set of T e and n e giving consistent line intensity distribution with the measurement, and that those parameters obtained vary as the line-averaged n e changes in the course of time. The position where the helium line emission dominantly takes place is located with the help of T e and n e profiles measured by the Thomson scattering system. The result indicates that the emission position is almost fixed at the place where the connection length of the magnetic field lines to the divertor plate leaps beyond 10 m. Because intense neutral atom line emission suggests the vigorous ionization of neutral atoms, the helium line emission location determined here can be regarded as the effective boundary of the plasma. - Highlights: • The reabsorption effect is included in the helium collisional-radiative model. • Electron temperature and density are derived for the Large Helical Device (LHD). • Line emission location is found to be little changed during the discharge. • This measurement method can be used to determine the position of effective plasma boundary

  14. High-Latitude Topside Ionospheric Vertical Electron-Density-Profile Changes in Response to Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

    2015-01-01

    Large magnetic-storm induced changes have been detected in high-latitude topside vertical electron-density profiles Ne(h). The investigation was based on the large database of topside Ne(h) profiles and digital topside ionograms from the International Satellites for Ionospheric Studies (ISIS) program available from the NASA Space Physics Data Facility (SPDF) at http://spdf.gsfc.nasa.gov/isis/isis-status.html. This large database enabled Ne(h) profiles to be obtained when an ISIS satellite passed through nearly the same region of space before, during, and after a major magnetic storm. A major goal was to relate the magnetic-storm induced high-latitude Ne(h) profile changes to solar-wind parameters. Thus an additional data constraint was to consider only storms where solar-wind data were available from the NASA/SPDF OMNIWeb database. Ten large magnetic storms (with Dst less than -100 nT) were identified that satisfied both the Ne(h) profile and the solar-wind data constraints. During five of these storms topside ionospheric Ne(h) profiles were available in the high-latitude northern hemisphere and during the other five storms similar ionospheric data were available in the southern hemisphere. Large Ne(h) changes were observed during each one of these storms. Our concentration in this paper is on the northern hemisphere. The data coverage was best for the northern-hemisphere winter. Here Ne(h) profile enhancements were always observed when the magnetic local time (MLT) was between 00 and 03 and Ne(h) profile depletions were always observed between 08 and 10 MLT. The observed Ne(h) deviations were compared with solar-wind parameters, with appropriate time shifts, for four storms.

  15. Space charge profiles in low density polyethylene samples containing a permittivity/conductivity gradient

    DEFF Research Database (Denmark)

    Bambery, K.R.; Fleming, R.J.; Holbøll, Joachim

    2001-01-01

    .5×107 V m-1. Current density was also measured as a function of temperature and field. Space charge due exclusively to the temperature gradient was detected, with density of order 0.01 C m-3. The activation energy associated with the transport of electrons through the bulk was calculated as 0.09 e...

  16. Density functional theory calculations of energy-loss carbon near-edge spectra of small diameter armchair and zigzag nanotubes: Core-hole, curvature, and momentum-transfer orientation effects

    International Nuclear Information System (INIS)

    Titantah, J.T.; Lamoen, D.; Jorissen, K.

    2004-01-01

    We perform density functional theory calculations on a series of armchair and zigzag nanotubes of diameters less than 1 nm using the all-electron full-potential(-linearized)-augmented-plane-wave method. Emphasis is laid on the effects of curvature, the electron-beam orientation, and the inclusion of the core hole on the carbon electron-energy-loss K edge. The electron-energy-loss near-edge spectra of all the studied tubes show strong curvature effects compared to that of flat graphene. The curvature-induced π-σ hybridization is shown to have a more drastic effect on the electronic properties of zigzag tubes than on those of armchair tubes. We show that the core-hole effect must be accounted for in order to correctly reproduce electron-energy-loss measurements. We also find that the energy-loss near-edge spectra of these carbon systems are dominantly dipole selected and that they can be expressed simply as a proportionality with the local momentum projected density of states, thus portraying the weak energy dependence of the transition matrix elements. Compared to graphite, we report a reduction in the anisotropy as seen on the energy-loss near-edge spectra of carbon nanotubes

  17. In depth fusion flame spreading with a deuterium—tritium plane fuel density profile for plasma block ignition

    International Nuclear Information System (INIS)

    Malekynia, B.; Razavipour, S. S.

    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 × 10 12 J/m 2 , 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 the density 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 × 10 12 J/m 2 . Thus threshold ignition energy in comparison with that at x = 0 layers would be reduced to less than 50 percent. (physics of gases, plasmas, and electric discharges)

  18. Determination of dislocation density by electron backscatter diffraction and X-ray line profile analysis in ferrous lath martensite

    International Nuclear Information System (INIS)

    Berecz, Tibor; Jenei, Péter; Csóré, András; Lábár, János; Gubicza, Jenő

    2016-01-01

    The microstructure and the dislocation density in as-quenched ferrous lath martensite were studied by different methods. The blocks, packets and variants formed due to martensitic transformation were identified and their sizes were determined by electron backscatter diffraction (EBSD). Concomitant transmission electron microscopy (TEM) investigation revealed that the laths contain subgrains with the size between 50 and 100 nm. A novel evaluation procedure of EBSD images was elaborated for the determination of the density and the space distribution of geometrically necessary dislocations from the misorientation distribution. The total dislocation density obtained by X-ray diffraction line profile analysis was in good agreement with the value determined by EBSD, indicating that the majority of dislocations formed due to martensitic transformation during quenching are geometrically necessary dislocations.

  19. Model-based Optimization and Feedback Control of the Current Density Profile Evolution in NSTX-U

    Science.gov (United States)

    Ilhan, Zeki Okan

    Nuclear fusion research is a highly challenging, multidisciplinary field seeking contributions from both plasma physics and multiple engineering areas. As an application of plasma control engineering, this dissertation mainly explores methods to control the current density profile evolution within the National Spherical Torus eXperiment-Upgrade (NSTX-U), which is a substantial upgrade based on the NSTX device, which is located in Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ. Active control of the toroidal current density profile is among those plasma control milestones that the NSTX-U program must achieve to realize its next-step operational goals, which are characterized by high-performance, long-pulse, MHD-stable plasma operation with neutral beam heating. Therefore, the aim of this work is to develop model-based, feedforward and feedback controllers that can enable time regulation of the current density profile in NSTX-U by actuating the total plasma current, electron density, and the powers of the individual neutral beam injectors. Motivated by the coupled, nonlinear, multivariable, distributed-parameter plasma dynamics, the first step towards control design is the development of a physics-based, control-oriented model for the current profile evolution in NSTX-U in response to non-inductive current drives and heating systems. Numerical simulations of the proposed control-oriented model show qualitative agreement with the high-fidelity physics code TRANSP. The next step is to utilize the proposed control-oriented model to design an open-loop actuator trajectory optimizer. Given a desired operating state, the optimizer produces the actuator trajectories that can steer the plasma to such state. The objective of the feedforward control design is to provide a more systematic approach to advanced scenario planning in NSTX-U since the development of such scenarios is conventionally carried out experimentally by modifying the tokamak's actuator

  20. Modelling of the energy density deposition profiles of ultrashort laser pulses focused in optical media

    International Nuclear Information System (INIS)

    Vidal, F; Lavertu, P-L; Bigaouette, N; Moore, F; Brunette, I; Giguere, D; Kieffer, J-C; Olivie, G; Ozaki, T

    2007-01-01

    The propagation of ultrashort laser pulses in dense optical media is investigated theoretically by solving numerically the nonlinear Schroedinger equation. It is shown that the maximum energy density deposition as a function of the pulse energy presents a well-defined threshold that increases with the pulse duration. As a consequence of plasma defocusing, the maximum energy density deposition is generally smaller and the size of the energy deposition zone is generally larger for shorter pulses. Nevertheless, significant values of the energy density deposition can be obtained near threshold, i.e., at lower energy than for longer pulses

  1. Simulated X-ray galaxy clusters at the virial radius: Slopes of the gas density, temperature and surface brightness profiles

    Science.gov (United States)

    Roncarelli, M.; Ettori, S.; Dolag, K.; Moscardini, L.; Borgani, S.; Murante, G.

    2006-12-01

    Using a set of hydrodynamical simulations of nine galaxy clusters with masses in the range 1.5 × 1014 matter of tension between simulated and observed properties, and up to the virial radius and beyond, where present observations are unable to provide any constraints. We have modelled the radial profiles between 0.3R200 and 3R200 with power laws with one index, two indexes and a rolling index. The simulated temperature and [0.5-2] keV surface brightness profiles well reproduce the observed behaviours outside the core. The shape of all these profiles in the radial range considered depends mainly on the activity of the gravitational collapse, with no significant difference among models including extraphysics. The profiles steepen in the outskirts, with the slope of the power-law fit that changes from -2.5 to -3.4 in the gas density, from -0.5 to -1.8 in the gas temperature and from -3.5 to -5.0 in the X-ray soft surface brightness. We predict that the gas density, temperature and [0.5-2] keV surface brightness values at R200 are, on average, 0.05, 0.60, 0.008 times the measured values at 0.3R200. At 2R200, these values decrease by an order of magnitude in the gas density and surface brightness, by a factor of 2 in the temperature, putting stringent limits on the detectable properties of the intracluster-medium (ICM) in the virial regions.

  2. Experimental study of a swept reflectometer with a single antenna for plasma density profile measurement

    International Nuclear Information System (INIS)

    Calderon, M.A.G.; Simonet, F.

    1984-12-01

    The feasibility of a swept microwave reflectometer, with one antenna only, for plasma electron density measurement is studied. Experimental results obtained in the laboratory by simulating the plasma with a metallic mirror are presented

  3. RELATIONSHIPS BETWEEN ANATOMICAL FEATURES AND INTRA-RING WOOD DENSITY PROFILES IN Gmelina arborea APPLYING X-RAY DENSITOMETRY

    Directory of Open Access Journals (Sweden)

    Mario Tomazelo-Filho

    2007-12-01

    Full Text Available Four annual tree-rings (2 of juvenile wood and 2 of mature wood were sampled from fast-growth plantations ofGmelina arborea in two climatic conditions (dry and wet tropical in Costa Rica. Each annual tree-ring was divided in equal parts ina radial direction. For each part, X-ray density as well as vessel percentage, length and width fiber, cell wall thickness and lumendiameter were measured. Wood density and profile patterns of cell dimension demonstrated inconsistency between juvenile andmature wood and climatic conditions. The Pearson correlation matrix showed that intra-ring wood density was positively correlatedwith the cell wall thickness and negatively correlated with vessel percentage, fiber length, lumen diameter and width. The forwardstepwise regressions determined that: (i intra-ring wood density variation could be predicted from 76 to 96% for anatomicalvariation; (ii cell wall thickness was the most important anatomical feature to produce intra-ring wood density variation and (iii thevessel percentage, fiber length, lumen diameter and width were the second most statically significant characteristics to intra-ring wooddensity, however, with low participation of the determination coefficient of stepwise regressions.

  4. Edge and internal transport barrier formations in CHS

    International Nuclear Information System (INIS)

    Okamura, S.; Minami, T.; Akiyama, T.; Fujisawa, A.; Ida, K.; Iguchi, H.; Isobe, M.; Nagaoka, K.; Nakamura, K.; Nishimura, S.; Matsuoka, K.; Matsushita, H.; Nakano, H.; Nishiura, M.; Ohshima, S.; Shimizu, A.; Suzuki, C.; Takahashi, C.; Toi, K.; Yoshimura, Y.; Yoshinuma, M.; Oishi, T.; Kado, S.

    2005-01-01

    Edge transport barrier (ETB) formation was observed in CHS. Sharp decrease of Hα emission indicates the quick transition of edge particle transport. Increase of the density gradient at the edge was measured by various profile diagnostics and the improvement of the global energy confinement was confirmed based on the stellarator confinement scaling. The heating power threshold exists. The transition and back transition is controlled by the heating power. The local density measurement by the beam emission spectroscopy shows intermittent burst of the low frequency fluctuations during the ETB formation phase. The ETB formation together with the electron temperature increase (electron ITB) in the core region were observed for the NBI discharges without ECH. (author)

  5. Investigation of non thermal effects from the Dα line wings in edge plasmas

    International Nuclear Information System (INIS)

    Marandet, Y.; Godbert-Mouret, L.; Koubiti, M.; Stamm, R.; Capes, H.; Guirlet, R.

    2002-01-01

    The far wings of intense Dα lines measured at the edge of the Tore Supra Tokamak are found to exhibit a power-law behavior. The characteristic exponent is not far from two. Since the low density rules out thermal Stark broadening, we discuss non thermal effects which may arise from the edge plasma drift-wave turbulence. We suggest that both the Stark and the Doppler profile could be affected by the turbulence

  6. Characterization and interpretation of the Edge Snake in between type-I edge localized modes at ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, F; Guenter, S; Kallenbach, A; Maraschek, M; Boom, J; Fischer, R; Hicks, N; Reiter, B; Wolfrum, E [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching, EURATOM Association (Germany); Luhmann, N C Jr [University of California at Davis, Davis, CA 95616 (United States); Park, H K [POSTECH, Pahang, Gyeongbuk 790-784 (Korea, Republic of); Wenninger, R, E-mail: fabian.sommer@ipp.mpg.de [Universitaetssternwarte der Ludwig-Maximilians-Universitaet, D-81679 Muenchen (Germany)

    2011-08-15

    A new magnetohydrodynamic instability called the 'Edge Snake', which was found in 2006 at the tokamak ASDEX Upgrade during type-I ELMy H-modes, is investigated. It is located within the separatrix in the region of high temperature and density gradients and has a toroidal mode number of n = 1. The Edge Snake consists of a radially and poloidally strongly localized current wire, in which the temperature and density profiles flatten. This significant reduction in pressure gradient leads to a reduction in the neoclassical Bootstrap current and can plausibly explain the drive of the instability. The experimental observations point towards a magnetic island with a defect current inside the O-point of the island. The Edge Snake is compared with similar instabilities at JET, DIII-D and ASDEX Upgrade.

  7. Edge Matters

    DEFF Research Database (Denmark)

    Earon, Ofri

    2013-01-01

    of this container is to separate inside from outside and to protect and provide privacy, psychological as well as physical (Venturi, 1966). But, if dwelling phenomenon takes place both inside and outside the private house – why is the urban house an enclosed box? What is the differentiation between inside...... and outside the contemporary urban house? And what is the interplay between them? The research argues for re-thinking the edge zone between inside and outside the urban house. Therefore, although, residential buildings in the city are the objects of study, the focal point here is the edge zone along...... the building. The research explores and develops the architectural characteristics of correlations between the resident, the singular unit, the building and the given location at the edge zone. It approaches the edge zone of the urban house as a platform for dynamic interactions between these behaviours...

  8. Tractable flux-driven temperature, density, and rotation profile evolution with the quasilinear gyrokinetic transport model QuaLiKiz

    Science.gov (United States)

    Citrin, J.; Bourdelle, C.; Casson, F. J.; Angioni, C.; Bonanomi, N.; Camenen, Y.; Garbet, X.; Garzotti, L.; Görler, T.; Gürcan, O.; Koechl, F.; Imbeaux, F.; Linder, O.; van de Plassche, K.; Strand, P.; Szepesi, G.; Contributors, JET

    2017-12-01

    Quasilinear turbulent transport models are a successful tool for prediction of core tokamak plasma profiles in many regimes. Their success hinges on the reproduction of local nonlinear gyrokinetic fluxes. We focus on significant progress in the quasilinear gyrokinetic transport model QuaLiKiz (Bourdelle et al 2016 Plasma Phys. Control. Fusion 58 014036), which employs an approximated solution of the mode structures to significantly speed up computation time compared to full linear gyrokinetic solvers. Optimisation of the dispersion relation solution algorithm within integrated modelling applications leads to flux calculations × {10}6-7 faster than local nonlinear simulations. This allows tractable simulation of flux-driven dynamic profile evolution including all transport channels: ion and electron heat, main particles, impurities, and momentum. Furthermore, QuaLiKiz now includes the impact of rotation and temperature anisotropy induced poloidal asymmetry on heavy impurity transport, important for W-transport applications. Application within the JETTO integrated modelling code results in 1 s of JET plasma simulation within 10 h using 10 CPUs. Simultaneous predictions of core density, temperature, and toroidal rotation profiles for both JET hybrid and baseline experiments are presented, covering both ion and electron turbulence scales. The simulations are successfully compared to measured profiles, with agreement mostly in the 5%-25% range according to standard figures of merit. QuaLiKiz is now open source and available at www.qualikiz.com.

  9. Visualization and analysis of pulsed ion beam energy density profile with infrared imaging

    Science.gov (United States)

    Isakova, Y. I.; Pushkarev, A. I.

    2018-03-01

    Infrared imaging technique was used as a surface temperature-mapping tool to characterize the energy density distribution of intense pulsed ion beams on a thin metal target. The technique enables the measuring of the total ion beam energy and the energy density distribution along the cross section and allows one to optimize the operation of an ion diode and control target irradiation mode. The diagnostics was tested on the TEMP-4M accelerator at TPU, Tomsk, Russia and on the TEMP-6 accelerator at DUT, Dalian, China. The diagnostics was applied in studies of the dynamics of the target cooling in vacuum after irradiation and in the experiments with target ablation. Errors caused by the target ablation and target cooling during measurements have been analyzed. For Fluke Ti10 and Fluke Ti400 infrared cameras, the technique can achieve surface energy density sensitivity of 0.05 J/cm2 and spatial resolution of 1-2 mm. The thermal imaging diagnostics does not require expensive consumed materials. The measurement time does not exceed 0.1 s; therefore, this diagnostics can be used for the prompt evaluation of the energy density distribution of a pulsed ion beam and during automation of the irradiation process.

  10. The improved DGR analytical model of electron density height profile and total electron content in the ionosphere

    OpenAIRE

    Radicella, S. M.; Zhang, M. L.

    1995-01-01

    Tests of the analytical model of the electron density profile originally proposed by G, Di Giovanni and S.M. Radicella (DGR model) have shown the need to introduce improvements in order to obtain a model able to reproduce the ionosphere in a larger spectrum of geophysical and time conditions. The present paper reviews the steps toward such progress and presents the final formulation of the model. It gives also a brief re- view of tests of the improved model done by different authors.

  11. Optimization of E r-density profile for efficient pumping and high signal gain in Erbium-doped fiber amplifiers

    International Nuclear Information System (INIS)

    Arzi, E.; Hassani, A.; Esmaili Seraji, F.

    2000-01-01

    Recently, the Erbium-Doped Fiber Amplifier has been shown to have a great potentiality in Fiber-Optics Communication. A model is suggested for calculating the E r-density profile, using the propagation and rate equations of a homogeneous two-level laser medium in Erbium-Doped Fiber Amplifier, such that efficient pumping and high signal gain is achieved for different fiber waveguide structure. The result of this numerical calculation shows that the gain, compared with the gain of the existing Erbium-Doped Fiber Amplifier, is higher by a factor of 3.5. This model is applicable in all active waveguides and any other dopant as well

  12. The utilization of electronic computers for bone density measurements with iodine 125 profile scanner

    International Nuclear Information System (INIS)

    Reiners, C.

    1974-01-01

    The utilization of electronic computers in the determination of the mineral content in bone with the 125 I profile scanner offers many advantages. The computer considerably lessens intensive work of routine evaluation. It enables the direct calculation of the attenuation coefficients. This means a greater accuracy and correctness of the results compared to the former 'graphical' method, as the approximations are eliminated and reference errors are avoided. (orig./LH) [de

  13. A distribution-free multi-factorial profiler for harvesting information from high-density screenings.

    Science.gov (United States)

    Besseris, George J

    2013-01-01

    Data screening is an indispensable phase in initiating the scientific discovery process. Fractional factorial designs offer quick and economical options for engineering highly-dense structured datasets. Maximum information content is harvested when a selected fractional factorial scheme is driven to saturation while data gathering is suppressed to no replication. A novel multi-factorial profiler is presented that allows screening of saturated-unreplicated designs by decomposing the examined response to its constituent contributions. Partial effects are sliced off systematically from the investigated response to form individual contrasts using simple robust measures. By isolating each time the disturbance attributed solely to a single controlling factor, the Wilcoxon-Mann-Whitney rank stochastics are employed to assign significance. We demonstrate that the proposed profiler possesses its own self-checking mechanism for detecting a potential influence due to fluctuations attributed to the remaining unexplainable error. Main benefits of the method are: 1) easy to grasp, 2) well-explained test-power properties, 3) distribution-free, 4) sparsity-free, 5) calibration-free, 6) simulation-free, 7) easy to implement, and 8) expanded usability to any type and size of multi-factorial screening designs. The method is elucidated with a benchmarked profiling effort for a water filtration process.

  14. A distribution-free multi-factorial profiler for harvesting information from high-density screenings.

    Directory of Open Access Journals (Sweden)

    George J Besseris

    Full Text Available Data screening is an indispensable phase in initiating the scientific discovery process. Fractional factorial designs offer quick and economical options for engineering highly-dense structured datasets. Maximum information content is harvested when a selected fractional factorial scheme is driven to saturation while data gathering is suppressed to no replication. A novel multi-factorial profiler is presented that allows screening of saturated-unreplicated designs by decomposing the examined response to its constituent contributions. Partial effects are sliced off systematically from the investigated response to form individual contrasts using simple robust measures. By isolating each time the disturbance attributed solely to a single controlling factor, the Wilcoxon-Mann-Whitney rank stochastics are employed to assign significance. We demonstrate that the proposed profiler possesses its own self-checking mechanism for detecting a potential influence due to fluctuations attributed to the remaining unexplainable error. Main benefits of the method are: 1 easy to grasp, 2 well-explained test-power properties, 3 distribution-free, 4 sparsity-free, 5 calibration-free, 6 simulation-free, 7 easy to implement, and 8 expanded usability to any type and size of multi-factorial screening designs. The method is elucidated with a benchmarked profiling effort for a water filtration process.

  15. Modifications of plasma edge electric field and confinement properties by limiter biasing on the KT-5C tokamak

    International Nuclear Information System (INIS)

    Hui Gao; Kan Zhai; Yizhi Wen; Shude Wan; Guiding Wang; Changxun Yu

    1995-01-01

    Experiments using a biased multiblock limiter in the KT-5C tokamak show that positive biasing is more effective than negative biasing in modifying the edge electric field, suppressing fluctuations and improving plasma confinement. The biasing effect varies with the limiter area, the toroidal magnetic field and the biasing voltage. By positive biasing, the edge profiles of the plasma potential, the electron temperature and the density become steeper, resulting in a reduced edge particle flux, an increased global particle confinement time and lower fluctuation levels of the edge plasma. (author)

  16. Improvement of Lipid Profile Is Accompanied by Atheroprotective Alterations in High-Density Lipoprotein Composition Upon Tumor Necrosis Factor Blockade A Prospective Cohort Study in Ankylosing Spondylitis

    NARCIS (Netherlands)

    Eijk, van I.C.; Vries, de M.K.; Levels, J.H.M.; Peters, M.J.L.; Huizer, E.E.; Dijkmans, B.A.C.; Horst - Bruinsma, van der I.E.; Hazenberg, B.P.C.; Stadt, van de R.J.; Wolbink, G.; Nurmohamed, M.T.

    2009-01-01

    Objective. Cardiovascular mortality is increased in ankylosing spondylitis (AS), and inflammation plays an important role. Inflammation deteriorates the lipid profile and alters high-density lipoprotein cholesterol (HDL-c) composition, reflected by increased concentrations of serum amyloid A (SAA)

  17. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    International Nuclear Information System (INIS)

    Castracane, J.

    2001-01-01

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies

  18. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Castracane, J.

    2001-01-04

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies.

  19. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M. W. [DESY (Deutsches Elektronen-Synchrotron), FS-PEX, Notkestrasse 85, 22607 Hamburg (Germany); Yiu, Y. M., E-mail: yyiu@uwo.ca; Sham, T. K. [Department of Chemistry, University of Western Ontario, London, ON N6A5B7 (Canada); Ward, M. J. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Liu, L. [Institute of Functional Nano and Soft Materials (FUNSOM) and Soochow University-Western University Center for Synchrotron Radiation Research, Soochow University, Suzhou, Jiangsu, 215123 (China); Hu, Y. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N2V3 (Canada); Zapien, J. A. [Center Of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Liu, Yingkai [Institute of Physics and Electronic Information, Yunnan Normal University, Kunming, Yunnan, 650500 (China)

    2014-11-21

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  20. Edge harmonic oscillations at the density pedestal in the H-mode discharges in CHS Heliotron measured using beam emission spectroscopy and magnetic probe

    Energy Technology Data Exchange (ETDEWEB)

    Kado, S. [High Temperature Plasma Center, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8568 (Japan)]. E-mail: kado@q.t.u-tokyo.ac.jp; Oishi, T. [School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yoshinuma, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Ida, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Takeuchi, M. [Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603 (Japan); Toi, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Akiyama, T. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Minami, T. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Nagaoka, K. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Shimizu, A. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Okamura, S. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Tanaka, S. [School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2007-06-15

    Edge harmonic oscillations (EHO) offer the potential to relax the H-mode pedestal in a tokamak, thus avoiding edge localised modes (ELM). The mode structure of the EHO in CHS was investigated using a poloidal array of beam emission spectroscopy (BES) and a magnetic probe array. The EHO exhibited a peculiar characteristic in which the first, second and third harmonics show the same wavenumber, suggesting that the propagation velocities are different. Change in the phase of higher harmonics at the time when that of the first harmonic is zero can be described as a variation along the (m, n) = (-2, 1) mode structure, though the EHO lies on the {iota} = 1 surface. This behavior leads to an oscillation that exhibits periodic dependence of shape on spatial position.

  1. ON THE AVERAGE DENSITY PROFILE OF DARK-MATTER HALOS IN THE INNER REGIONS OF MASSIVE EARLY-TYPE GALAXIES

    International Nuclear Information System (INIS)

    Grillo, C.

    2012-01-01

    We study a sample of 39 massive early-type lens galaxies at redshift z ∼< 0.3 to determine the slope of the average dark-matter density profile in the innermost regions. We keep the strong-lensing and stellar population synthesis modeling as simple as possible to measure the galaxy total and luminous masses. By rescaling the values of the Einstein radius and dark-matter projected mass with the values of the luminous effective radius and mass, we combine all the data of the galaxies in the sample. We find that between 0.3 and 0.9 times the value of the effective radius the average logarithmic slope of the dark-matter projected density profile is –1.0 ± 0.2 (i.e., approximately isothermal) or –0.7 ± 0.5 (i.e., shallower than isothermal), if, respectively, a constant Chabrier or heavier, Salpeter-like stellar initial mass function is adopted. These results provide positive evidence of the influence of the baryonic component on the contraction of the galaxy dark-matter halos, compared to the predictions of dark-matter-only cosmological simulations, and open a new way to test models of structure formation and evolution within the standard ΛCDM cosmological scenario.

  2. ICRF/edge physics research on TEXTOR

    International Nuclear Information System (INIS)

    Oost, G. van; Nieuwenhove, R. van; Koch, R.; Messiaen, A.M.; Vandenplas, P.E.; Weynants, R.R.; Dippel, K.H.; Finken, K.H.; Lie, Y.T.; Pospieszczyk, A.; Samm, U.; Schweer, B.; Conn, R.W.; Corbett, W.J.; Goebel, D.M.; Moyer, R.A.; California Univ., Los Angeles

    1990-01-01

    Extensive investigations of ICRF-induced effects on the edge plasma and on plasma-wall interaction were conducted on TEXTOR under different wall- and limiter as well as plasma- and heating conditions. Several strong effects of ICRF on the edge parameters were observed on TEXTOR, such as density rise, instantaneous electron heating, modification of SOL profiles, influx of ligth and/or heavy impurities, increased heat flux to the limiters, and production of energetic ions in the SOL. The fast response time of some of the changes and the observation of a maximum in the SOL profile of electron temperature, heat flux and metal sputtering clearly demonstrated that RF power is directly absorbed in the SOL. Estimates of this power amount to several percent of the total RF power launched into the plasma. Plasma-wall interaction during ICRF was substantially reduced by an appropriate choice of the wall conditioning procedures (wall carbonization with liner at 400degC or, above all, boronization). As a result record low values of the radiated power fraction were achieved during ICRF and long pulse, high power, low impurity operation was possible. Further improvement was obtained by ICRF antenna phasing. When ICRF power is coupled to the plasma, several effects on the core and edge plasma influence the operation of the toroidal pump limiter ALT-II. Experimental and theoretical studies were performed to elucidate the mechanisms responsible for the ICRF-induced effects, including the propagation of plasma waves in the edge plasma and nonlinear phenomena such as parametric decay, important changes in the DC current between the antenna structure and the liner due to the sheath effect at the antennas, and the generation of waves at harmonics of the RF generator frequency. Radial profiles of the DC radial and poloidal electric fields as well as a localized RF electric field structure were measured in the SOL using a fast scanning probe. (orig.)

  3. Task-Related Edge Density (TED)—A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain

    Science.gov (United States)

    Lohmann, Gabriele; Stelzer, Johannes; Zuber, Verena; Buschmann, Tilo; Margulies, Daniel; Bartels, Andreas; Scheffler, Klaus

    2016-01-01

    The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach “Task-related Edge Density” (TED). TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function. PMID:27341204

  4. A New Inversion Routine to Produce Vertical Electron-Density Profiles from Ionospheric Topside-Sounder Data

    Science.gov (United States)

    Wang, Yongli; Benson, Robert F.

    2011-01-01

    Two software applications have been produced specifically for the analysis of some million digital topside ionograms produced by a recent analog-to-digital conversion effort of selected analog telemetry tapes from the Alouette-2, ISIS-1 and ISIS-2 satellites. One, TOPIST (TOPside Ionogram Scalar with True-height algorithm) from the University of Massachusetts Lowell, is designed for the automatic identification of the topside-ionogram ionospheric-reflection traces and their inversion into vertical electron-density profiles Ne(h). TOPIST also has the capability of manual intervention. The other application, from the Goddard Space Flight Center based on the FORTRAN code of John E. Jackson from the 1960s, is designed as an IDL-based interactive program for the scaling of selected digital topside-sounder ionograms. The Jackson code has also been modified, with some effort, so as to run on modern computers. This modification was motivated by the need to scale selected ionograms from the millions of Alouette/ISIS topside-sounder ionograms that only exist on 35-mm film. During this modification, it became evident that it would be more efficient to design a new code, based on the capabilities of present-day computers, than to continue to modify the old code. Such a new code has been produced and here we will describe its capabilities and compare Ne(h) profiles produced from it with those produced by the Jackson code. The concept of the new code is to assume an initial Ne(h) and derive a final Ne(h) through an iteration process that makes the resulting apparent-height profile fir the scaled values within a certain error range. The new code can be used on the X-, O-, and Z-mode traces. It does not assume any predefined profile shape between two contiguous points, like the exponential rule used in Jackson s program. Instead, Monotone Piecewise Cubic Interpolation is applied in the global profile to keep the monotone nature of the profile, which also ensures better smoothness

  5. Density profile evolution and nonequilibrium effects in partial and full spreading measurements of surface diffusion

    DEFF Research Database (Denmark)

    Nikunen, P.; Vattulainen, Ilpo Tapio; Ala-Nissila, T.

    2001-01-01

    in D-C(theta) depend on the initial density gradient and the initial state from which the spreading starts. To this end, we carry out extensive Monte Carlo simulations for a lattice-gas model of the O/W(110) system. Studies of submonolayer spreading from an initially ordered p(2x1) phase at theta = 1....../2 reveal that the spreading and diffusion rates in directions parallel and perpendicular to rows of oxygen atoms are significantly different within the ordered phase. Aside from this effect, we find that the degree of ordering in the initial phase has a relatively small impact on the overall behavior of D...

  6. Spectroscopic observation of the middle ultraviolet earth albedo by S-520-4 rocket and mesospheric ozone density profile

    International Nuclear Information System (INIS)

    Suzuki, Katsuhisa; Ogawa, Toshihiro.

    1982-01-01

    The ozone Hartey absorption band in the middle ultraviolet range is commonly adopted for the ozone measurement by rocket and satellite observations. In Japan, since 1965 the ozone absorption in the solar ultraviolet radiation has been observed by rocket-borne uv photometers. On the other hand the spectroscopic measurements of the scattered solar ultraviolet radiation from the terrestrial atmosphere will be performed by the EXOS-C satellite which will be launched in 1984. We tested the spectrometer for this satellite experiment by S-520-4 rocket launched on 5 September 1981. This instrument observed the scattered radiation of 2500 A -- 3300 A and the visible earth albedo of 4030 A. The spectrometer is consisted of a concave grating and has about 10 A wavelength resolution. A photomultiplier having a Cs-Te photocathode is used as a uv detector. The visible albedo is measured by a photometer consisting of an interference filter and a phototube. We estimated the atmospheric ozone profile, comparing the uv spectrum obtained by this experiment with the model calculations. The estimated ozone density profile higher than 30 km altitude has good agreement with the profile obtained by the previous uv photometer experiments at Uchinoura. There are differences between the observed spectrum and the calculated one in = 3100 A. We can explain them by the effect of Mie scattering and the uv stray light. In the present experiment we could successfully test the functions of the instrument in the space. rocket, spectrometer, solar ultraviolet radiation, earth albedo, ozone (author)

  7. Measurements of Electron 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.

    2013-10-01

    Knowing spatial profiles of electron density (ne) in the underdense coronal region (n Nike LPI experiment, a side-on grid imaging refractometer (GIR) was deployed for measuring the underdense plasma profiles. Plasmas were produced from flat CH targets illuminated by Nike KrF laser with total energies up to 1 kJ of 0.5 ~ 1 nsec FWHM pulses. The GIR resolved ne up to 3 ×1021 /cm3 in space taking 2D snapshot images of probe laser (λ = 263 nm, Δt = 10 ps) beamlets (50 μm spacing) refracted by the plasma at a selected time during the laser illumination. The individual beamlet transmittances were also measured for Te estimation. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera simultaneously detected light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay instabilities. The measured spatial profiles are compared with simulation results from the FAST3D radiation hydrocode and their effects on the LPI observations are investigated. Work supported by DoE/NNSA and performed at Naval Research Laboratory.

  8. Theory for the asymmetry in the auroral ionization density profile for the generation of auroral infrasonic waves

    International Nuclear Information System (INIS)

    Goodwin, P.A.

    1979-01-01

    Traveling pressure waves with periods from 10 to 100 seconds are generated in the lower ionosphere by auroral electrojet current filaments as they move supersonically in an equatorward direction. The infrasonic waves produced by the auroral motions propagate to the ground as highly directional bow waves that can be detected by infrasonic microphones on the surface. There is an asymmetry in the reception of auroral infrasonic waves (AIW) with respect to whether the auroral arcs are moving equatorward to poleward. In the literature it is suggested that the asymmetry may be due to anisotropic propagation conditions along the acoustic ray path from the E-region, where AIW are produced, to the surface. Some intrinsic property of the AIW generation mechanism itself has also been suggested as a possible explanation. In this thesis anisotropic propagation is eliminated as the cause of the AIW reception asymmetry. Theoretical calculations, beginning with a model of an auroral precipitation region, are presented to show that there can be a significant difference in the transverse ionization density profiles between an auroral arc that is moving equatorward and an arc that is moving poleward, for a given equatorward-directed E-region ambient electric field. The calculation has been accomplished by solving the equations of motion and continuity for the cross-sectional ionization density profile associated with the transverse motion of a filamentary auroral electrojet. Thus, it is shown that there is an asymmetry in the ionization profiles associated with moving arcs, and in their coupling, that is related to the relative direction of motion of the arc with respect to the ambient electric field, and that it is this asymmetry that is probably the cause of the observed AIW reception asymmetry

  9. Innovative User Defined Density Profile Approach To FSW Of Aluminium Foam

    International Nuclear Information System (INIS)

    Contorno, Dorotea; Fratini, Livan; Filice, Luigino; Gagliardi, Francesco; Umbrello, Domenico; Shivpuri, Rajiv

    2007-01-01

    Metallic foams are one of the most exciting materials in the world of mechanical industry due to their reduced mass and the good mechanical, thermal and acoustic characteristics. Consequently, their application, is increasing day by day even with the important drawbacks that reduce their suitability and diffusion such as high manufacturing cost and difficulty in processing. An innovative approach is outlined in this paper that enables the production of complex shapes taking advantage of deformation processing and friction stir welding (FSW). The aim is to create customized tailored manufactured parts. The cellular construction of foams makes this approach rather challenging as the cell walls are extremely thin and deform unpredictably especially in the presence of rotating and moving hard tool. In this paper, an integrated approach to overcome some of the above challenges is proposed. The initial density is modified by using simple deformation processes, in order to obtained the desired 'crushed density', customized for the intended application. Then, the panels are joined to specially designed solid blocks by using FSW process with a proper set-up. Finally, the obtained specimens are evaluated for mechanical performance and the quality of the joint.

  10. Spatial profiles of electron and metastable atom densities in positive polarity fast ionization waves sustained in helium

    International Nuclear Information System (INIS)

    Weatherford, Brandon R.; Barnat, E. V.; Xiong, Zhongmin; Kushner, Mark J.

    2014-01-01

    Fast ionization waves (FIWs), often generated with high voltage pulses over nanosecond timescales, are able to produce large volumes of ions and excited states at moderate pressures. The mechanisms of FIW propagation were experimentally and computationally investigated to provide insights into the manner in which these large volumes are excited. The two-dimensional structure of electron and metastable densities produced by short-pulse FIWs sustained in helium were measured using laser-induced fluorescence and laser collision-induced fluorescence diagnostics for times of 100–120 ns after the pulse, as the pressure was varied from 1 to 20 Torr. A trend of center-peaked to volume-filling to wall-peaked electron density profiles was observed as the pressure was increased. Instantaneous FIW velocities, obtained from plasma-induced emission, ranged from 0.1 to 3 × 10 9  cm s −1 , depending on distance from the high voltage electrode and pressure. Predictions from two-dimensional modeling of the propagation of a single FIW correlated well with the experimental trends in electron density profiles and wave velocity. Results from the model show that the maximum ionization rate occurs in the wavefront, and the discharge continues to propagate forward after the removal of high voltage from the powered electrode due to the potential energy stored in the space charge. As the pressure is varied, the radial distribution of the ionization rate is shaped by changes in the electron mean free path, and subsequent localized electric field enhancement at the walls or on the centerline of the discharge.

  11. DIII-D edge physics database

    International Nuclear Information System (INIS)

    Jong, R.A.; Porter, G.D.; Hill, D.N.; Buchenauer, D.A.; Bramson, G.

    1992-03-01

    We have developed an edge-physics database containing data for the plasma in the divertor region and the scrape-off layer (SOL) for the DIII-D tokamak. The database provides many of the parameters necessary to model the power flow to the divertor and other plasma processes in the plasma edge. It will also facilitate the analysis of DIII-D data for comparison with other divertor tokamaks. In addition to the core plasma parameters, edge-specific data are included in this database. Initial results using the database show good agreement between the pressure profiles measured by the Langmuir probes and those determined from the Thomson data for the inner strike point, but not for the outer strike point region. We also find that the ratio of separatrix density to average core density, as well as the in/out asymmetry in the SOL power at the divertor in DIII-D do not agree with values currently assumed in modeling the International Thermonuclear Experimental Reactor (ITER)

  12. Edge instabilities of topological superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Johannes S. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany); Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Assaad, Fakher F. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany); Schnyder, Andreas P. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2016-07-01

    Nodal topological superconductors display zero-energy Majorana flat bands at generic edges. The flatness of these edge bands, which is protected by time-reversal and translation symmetry, gives rise to an extensive ground state degeneracy and a diverging density of states. Therefore, even arbitrarily weak interactions lead to an instability of the flat-band edge states towards time-reversal and translation-symmetry broken phases, which lift the ground-state degeneracy. Here, we employ Monte Carlo simulations combined with mean-field considerations to examine the instabilities of the flat-band edge states of d{sub xy}-wave superconductors. We find that attractive interactions induce a complex s-wave pairing instability together with a density wave instability. Repulsive interactions, on the other hand, lead to ferromagnetism mixed with spin-triplet pairing at the edge. We discuss the implications of our findings for experiments on cuprate high-temperature superconductors.

  13. Profile of cortisol, glycaemia, and blood parameters of American Bullfrog tadpoles Lithobates catesbeianus exposed to density and hypoxia stressors

    Directory of Open Access Journals (Sweden)

    Patricia C. Teixeira

    2012-12-01

    Full Text Available The aim of this study was to evaluate alterations to the physiological profile (cortisol, glycaemia, and blood parameters of Lithobates catesbeianus caused by the stressors density and hypoxia. The organisms were in the prometamorphosis stage and exposed to different tadpole densities: 1 tadpole/L (T1, 5 tadpoles/L (T2, and 10 tadpoles/L (T3 for 12 days. The blood was collected through the rupture of the caudal blood vessel and collected under normoxia (immediate collection and hypoxia (after 15 minutes of air exposure conditions. Cortisol levels rose on the fourth and eighth days of treatment and returned to basal levels by the end of the experiment. The stressor mechanisms tested did not affect glycaemia. White blood cells (total number of lymphocytes, neutrophils, and eosinophils showed a significant difference at the twelfth day of the experiment when compared with the start of the experiment. We concluded that, under controlled conditions, a density of up to 10 tadpoles/L and air exposure for 15 minutes did not cause harmful physiological alterations during the experimental period. The answer to these stressors maybe was in another hormonal level (corticosterone.

  14. Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

    International Nuclear Information System (INIS)

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

    2010-01-01

    The axial profiles of the electron density n e and electron temperature T e of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10 18 e 19 m -3 and 1.1 e e and T e down to 8% and 3%, respectively. It is found that n e decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T e does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

  15. K- and L-edge X-ray absorption spectrum calculations of closed-shell carbon, silicon, germanium, and sulfur compounds using damped four-component density functional response theory.

    Science.gov (United States)

    Fransson, Thomas; Burdakova, Daria; Norman, Patrick

    2016-05-21

    X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems.

  16. Observation of the skin-like profiles of electron temperature and density of turbulently heated plasmas in the TRIAM-1 tokamak

    International Nuclear Information System (INIS)

    Hiraki, Naoji; Nakamura, Kazuo; Toi, Kazuo; Itoh, Satoshi

    1980-01-01

    The time evolution of electron temperature and density profiles are measured on the turbulent heating experiment in the TRIAM-1 tokamak. The skin-like profiles of electron temperature and density are observed just after the application of the pulsed electric field for turbulent heating. The width of the skin layer of the electron temperature profile is about 1 cm, and agrees well with the theoretical value. The above mentioned skin heating of electrons just after the heating pulse is also spectroscopically confirmed by the remarkable decrease of the volume emission of visible lines which is localized at the outer plasma region. (author)

  17. Observation of the skin-like profiles of electron temperature and density of turbulently heated plasmas in the TRIAM-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, N; Nakamura, K; Toi, K; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-07-01

    The time evolution of electron temperature and density profiles are measured on the turbulent heating experiment in the TRIAM-1 tokamak. The skin-like profiles of electron temperature and density are observed just after the application of the pulsed electric field for turbulent heating. The width of the skin layer of the electron temperature profile is about 1 cm, and agrees well with the theoretical value. The above mentioned skin heating of electrons just after the heating pulse is also spectroscopically confirmed by the remarkable decrease of the volume emission of visible lines which is localized at the outer plasma region.

  18. Improving the Automatic Inversion of Digital Alouette/ISIS Ionogram Reflection Traces into Topside Electron Density Profiles

    Science.gov (United States)

    Benson, Robert F.; Truhlik, Vladimir; Huang, Xueqin; Wang, Yongli; Bilitza, Dieter

    2012-01-01

    The topside sounders of the International Satellites for Ionospheric Studies (ISIS) program were designed as analog systems. The resulting ionograms were displayed on 35 mm film for analysis by visual inspection. Each of these satellites, launched between 1962 and 1971, produced data for 10 to 20 years. A number of the original telemetry tapes from this large data set have been converted directly into digital records. Software, known as the Topside Ionogram Scalar With True-Height (TOPIST) algorithm, has been produced and used for the automatic inversion of the ionogram reflection traces on more than 100,000 ISIS-2 digital topside ionograms into topside vertical electron density profiles Ne(h). Here we present some topside ionospheric solar cycle variations deduced from the TOPIST database to illustrate the scientific benefit of improving and expanding the topside ionospheric Ne(h) database. The profile improvements will be based on improvements in the TOPIST software motivated by direct comparisons between TOPIST profiles and profiles produced by manual scaling in the early days of the ISIS program. The database expansion will be based on new software designed to overcome limitations in the original digital topside ionogram database caused by difficulties encountered during the analog-to-digital conversion process in the detection of the ionogram frame sync pulse and/or the frequency markers. This improved and expanded TOPIST topside Ne(h) database will greatly enhance investigations into both short- and long-term ionospheric changes, e.g., the observed topside ionospheric responses to magnetic storms, induced by interplanetary magnetic clouds, and solar cycle variations, respectively.

  19. Profiles

    International Nuclear Information System (INIS)

    2004-01-01

    Profiles is a synthetic overview of more than 100 national energy markets in the world, providing insightful facts and key energy statistics. A Profile is structured around 6 main items and completed by key statistics: Ministries, public agencies, energy policy are concerned; main companies in the oil, gas, electricity and coal sectors, status, shareholders; reserve, production, imports and exports, electricity and refining capacities; deregulation of prices, subsidies, taxes; consumption trends by sector, energy market shares; main energy projects, production and consumption prospects. Statistical Profiles are present in about 3 pages the main data and indicators on oil, gas, coal and electricity. (A.L.B.)

  20. Determination of density profiles of unevenly compressed wood of Po­pu­lus tremula using the X – RAY DENSE – LAB laboratory device

    Directory of Open Access Journals (Sweden)

    Aleš Dejmal

    2009-01-01

    Full Text Available The paper deals with the measuring of the density profile of unevenly pressed wood of European aspen (Populus tremula L.. The main aim of the work is to examine in an experimental way the possibilities of using the X – RAY DENSE – LAB laboratory equipment designed for the determination of density profiles of agglomerated and plied large-area materials. The work uses the X – RAY DENSE – LAB equipment to determine the density profile of the cross-section of unevenly pressed aspen wood, plasticized hydrothermically, without the presence of chemical substances. The work also presents calculations of the level of compression/densification in dependence on the density and it describes the factors that can influence the density profile of compressed/densified wood; at the same time, it presents the possible ways to determine the density profile in the cross-section. Further, it includes the creation of the methodology for sample preparation so that the results do not get distorted during measuring. It describes the preparation of sample pieces, the orientation of the anatomic structure, the methodology of pressing, air conditioning, sample preparation, their measuring and analysis. The paper also describes the theory and the principles of measuring with use of X – RAY DENSE – LAB and its calibration. The paper analyses the obtained results of density profiles and searches for and describes the causes of the uneven distribution of the density in the cross-section. It concludes by summarizing the results and recommending the procedure for future measuring.

  1. Using solution- and solid-state S K-edge X-ray absorption spectroscopy with density functional theory to evaluate M-S bonding for MS4(2-) (M = Cr, Mo, W) dianions.

    Science.gov (United States)

    Olson, Angela C; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Daly, Scott R; Kozimor, Stosh A; MacInnes, Molly M; Martin, Richard L; Scott, Brian L

    2014-12-14

    Herein, we have evaluated relative changes in M-S electronic structure and orbital mixing in Group 6 MS4(2-) dianions using solid- and solution-phase S K-edge X-ray absorption spectroscopy (XAS; M = Mo, W), as well as density functional theory (DFT; M = Cr, Mo, W) and time-dependent density functional theory (TDDFT) calculations. To facilitate comparison with solution measurements (conducted in acetonitrile), theoretical models included gas-phase calculations as well as those that incorporated an acetonitrile dielectric, the latter of which provided better agreement with experiment. Two pre-edge features arising from S 1s → e* and t electron excitations were observed in the S K-edge XAS spectra and were reasonably assigned as (1)A1 → (1)T2 transitions. For MoS4(2-), both solution-phase pre-edge peak intensities were consistent with results from the solid-state spectra. For WS4(2-), solution- and solid-state pre-edge peak intensities for transitions involving e* were equivalent, while transitions involving the t orbitals were less intense in solution. Experimental and computational results have been presented in comparison to recent analyses of MO4(2-) dianions, which allowed M-S and M-O orbital mixing to be evaluated as the principle quantum number (n) for the metal valence d orbitals increased (3d, 4d, 5d). Overall, the M-E (E = O, S) analyses revealed distinct trends in orbital mixing. For example, as the Group 6 triad was descended, e* (π*) orbital mixing remained constant in the M-S bonds, but increased appreciably for M-O interactions. For the t orbitals (σ* + π*), mixing decreased slightly for M-S bonding and increased only slightly for the M-O interactions. These results suggested that the metal and ligand valence orbital energies and radial extensions delicately influenced the orbital compositions for isoelectronic ME4(2-) (E = O, S) dianions.

  2. Recent experimental studies of edge and internal transport barriers in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Gohil, P; Baylor, L R; Burrell, K H; Casper, T A; Doyle, E J; Greenfield, C M; Jernigan, T C; Kinsey, J E; Lasnier, C J; Moyer, R A; Murakami, M; Rhodes, T L; Rudakov, D L; Staebler, G M; Wang, G; Watkins, J G; West, W P; Zeng, L

    2003-01-01

    Results from recent experiments on the DIII-D tokamak have revealed many important details on transport barriers at the plasma edge and in the plasma core. These experiments include: (a) the formation of the H-mode edge barrier directly by pellet injection; (b) the formation of a quiescent H-mode edge barrier (QH-mode) which is free from edge localized modes, but which still exhibits good density and radiative power control; (c) the formation of multiple transport barriers, such as the quiescent double barrier (QDB) which combines an internal transport barrier with the quiescent H-mode edge barrier. Results from the pellet-induced H-mode experiments indicate that: (a) the edge temperature (electron or ion) does not need to attain a critical value for the formation of the H-mode barrier, (b) pellet injection leads to an increased gradient in the radial electric field, E r , at the plasma edge; (c) the experimentally determined edge parameters at barrier transition are well below the predictions of several theories on the formation of the H-mode barrier, (d) pellet injection can lower the threshold power required to form the H-mode barrier. The quiescent H-mode barrier exhibits good density control as the result of continuous magnetohydrodynamic activity at the plasma edge called the edge harmonic oscillation (EHO). The EHO enhances the edge particle transport whilst maintaining a good energy transport barrier. The ability to produce multiple barriers in the QDB regime has led to long duration, high-performance plasmas with β N H 89 values of 7 for up to 10 times the confinement time. Density profile control in the plasma core of QDB plasmas has been demonstrated using on-axis electron cyclotron heating

  3. Measurements and 2-D Modeling of Recycling and Edge Transport in Discharges with Lithium-coated PFCs in NSTX

    International Nuclear Information System (INIS)

    Canik, John; Maingi, R.; Soukhanovskii, V.A.; Bell, R.E.; Kugel, H.; LeBlanc, B.; Osborne, T.H.

    2011-01-01

    The application of lithium coatings on plasma facing components has been shown to profoundly affect plasma performance in the National Spherical Torus Experiment, improving energy confinement and eliminating edge-localized modes. The edge particle balance during these ELM-free discharges has been studied through 2-D plasma-neutrals modeling, constrained by measurements of the upstream plasma density and temperature profiles and the divertor heat flux and D-alpha emission. The calculations indicate that the reduction in divertor D-alpha emission with lithium coatings applied is consistent with a drop in recycling coefficient from R similar to 0.98 to R similar to 0.9. The change in recycling is not sufficient to account for the change in edge density profiles: interpretive modeling indicates similar transport coefficients within the edge transport barrier (D/chi(e) similar to 0.2/1.0 m(2)/s), but a widening of the barrier with lithium.

  4. Measurements and 2-D modeling of recycling and edge transport in discharges with lithium-coated PFCs in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Canik, J.M., E-mail: canikjm@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Maingi, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Soukhanovskii, V.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Bell, R.E.; Kugel, H.W.; LeBlanc, B.P. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Osborne, T.H. [General Atomics, San Diego, CA (United States)

    2011-08-01

    The application of lithium coatings on plasma facing components has been shown to profoundly affect plasma performance in the National Spherical Torus Experiment, improving energy confinement and eliminating edge-localized modes. The edge particle balance during these ELM-free discharges has been studied through 2-D plasma-neutrals modeling, constrained by measurements of the upstream plasma density and temperature profiles and the divertor heat flux and D{sub {alpha}} emission. The calculations indicate that the reduction in divertor D{sub {alpha}} emission with lithium coatings applied is consistent with a drop in recycling coefficient from R {approx} 0.98 to R {approx} 0.9. The change in recycling is not sufficient to account for the change in edge density profiles: interpretive modeling indicates similar transport coefficients within the edge transport barrier (D/{chi}{sub e} {approx} 0.2/1.0 m{sup 2}/s), but a widening of the barrier with lithium.

  5. Control of quasi-monoenergetic electron beams from laser-plasma accelerators with adjustable shock density profile

    Science.gov (United States)

    Tsai, Hai-En; Swanson, Kelly K.; Barber, Sam K.; Lehe, Remi; Mao, Hann-Shin; Mittelberger, Daniel E.; Steinke, Sven; Nakamura, Kei; van Tilborg, Jeroen; Schroeder, Carl; Esarey, Eric; Geddes, Cameron G. R.; Leemans, Wim

    2018-04-01

    The injection physics in a shock-induced density down-ramp injector was characterized, demonstrating precise control of a laser-plasma accelerator (LPA). Using a jet-blade assembly, experiments systematically varied the shock injector profile, including shock angle, shock position, up-ramp width, and acceleration length. Our work demonstrates that beam energy, energy spread, and pointing can be controlled by adjusting these parameters. As a result, an electron beam that was highly tunable from 25 to 300 MeV with 8% energy spread (ΔEFWHM/E), 1.5 mrad divergence, and 0.35 mrad pointing fluctuation was produced. Particle-in-cell simulation characterized how variation in the shock angle and up-ramp width impacted the injection process. This highly controllable LPA represents a suitable, compact electron beam source for LPA applications such as Thomson sources and free-electron lasers.

  6. The effect of plasma density profile on the backscatter of microwaves from a plasma-covered plane conductor

    International Nuclear Information System (INIS)

    Destler, W.W.; Singh, A.; Rodgers, J.

    1993-01-01

    In order to gain further insight into the mechanism of anomalous absorption of microwaves in a pulsed plasma column, the latter was studied using single and double Langmuir probes. Graphs of plasma potential recorded by floating Langmuir probes as a function of time were obtained for a range of pressure of the background gas and at different distances from the plasma-covered plane-conducting plate. From this data, two main components of the plasma have been identified. The first appears earlier, exhibits greater fluctuations and is shorter in duration than the second component. The presence of these two plasma components is consistent with earlier observations obtained from transverse transmission measurements of microwaves through the plasma. Variations in the envelopes of these two components as experimental conditions are changed will be presented. Microwave backscatter measurements under varying conditions of plasma-density profile and ambient gas pressure will also be presented

  7. Collisional drift waves in the H-mode edge

    International Nuclear Information System (INIS)

    Sen, S.

    1994-01-01

    The stability of the collisional drift wave in a sheared slab geometry is found to be severely restricted at the H-mode edge plasma due to the very steep density gradient. However, a radially varying transverse velocity field is found to play the key role in stability. Velocity profiles usually found in the H-mode plasma stabilize drift waves. On the other hand, velocity profiles corresponding to the L-mode render collisional drift waves unstable even though the magnetic shear continues to play its stabilizing role. (author). 24 refs

  8. Defining the bone morphometry, micro-architecture and volumetric density profile in osteopenic vs non-osteopenic adolescent idiopathic scoliosis.

    Science.gov (United States)

    Wang, Zhi-Wei; Lee, Wayne Yuk-Wai; Lam, Tsz-Ping; Yip, Benjamin Hon-Kei; Yu, Fiona Wai-Ping; Yu, Wing-Sze; Zhu, Feng; Ng, Bobby Kin-Wah; Qiu, Yong; Cheng, Jack Chun-Yiu

    2017-06-01

    Osteopenia has been widely reported in about 30 % of girls with adolescent idiopathic scoliosis (AIS). However, the bone quality profile of the 70 % non-osteopenic AIS defined by areal bone mineral density (BMD) with conventional dual-energy X-ray absorptiometry (DXA) has not been adequately studied. Our purpose was to verify whether abnormal volumetric BMD (vBMD) and bone structure (morphometry and micro-architecture) also existed in the non-osteopenic AIS when compared with matched controls using both DXA and high-resolution peripheral computed tomography (HR-pQCT). This was a case-control cross-sectional study. 257 AIS girls with a mean age of 12.7 (SD = 0.8) years old and 187 age- and gender-matched normal controls with an average age of 12.9 (SD = 0.5) years old were included. Areal BMD (aBMD) and bone quality were measured with standard DXA and HR-pQCT, respectively. The parameters of HR-pQCT could be categorized as bone morphometry, vBMD and bone micro-architecture. The results were compared between the osteopenic AIS and osteopenic control, and between the non-osteopenic AIS and non-osteopenic control. In addition to the lower aBMD and vBMD, osteopenic AIS showed significantly greater cortical perimeter and trabecular area than the osteopenic control even after adjustments of age (P architecture and volumetric density profile compared with their normal matched controls. The observed abnormalities were suggestive of decreased endocortical bone apposition or active endocortical resorption that could affect the mechanical bone strength in AIS. The underlying pathomechanism might be attributed to abnormal bone modeling/remodeling that could be associated with the etiopathogenesis of AIS.

  9. Hollow density profile and particle transport of ECH plasmas in the low-aspect-ratio heliotron/torsatron CHS

    International Nuclear Information System (INIS)

    Iguchi, H.; Kubo, S.; Idei, H.

    1993-01-01

    Transport enhancement due to helical ripples is the main problem for a low-aspect-ratio helical system to survive as a magnetic fusion device. Optimization of the magnetic configuration has been experimentally studied for neutral beam heated plasmas in the Compact Helical System (CHS). A confinement regime compatible with the LHD scaling has been obtained by shifting the magnetic axis inward with respect to the minor axis of the helical windings. However a power balance analysis suggests that the improvement of plasma parameters has mainly been achieved by the improvement of power deposition. On the other hand, electron density profiles become peaked with the inward shifted magnetic axis in contrast to flattened profiles with the outward shifted one. A question arises: Does the magnetic structure really affect transport processes? In order to answer this question, it is most suitable to examine ECH plasmas in a low collisionality regime. In this paper we report some characteristics of the ECH plasmas in the low-aspect-ratio device CHS and discuss the effect of magnetic field ripples on transport processes. (author) 10 refs., 4 figs

  10. Improving the Automatic Inversion of Digital ISIS-2 Ionogram Reflection Traces into Topside Vertical Electron-Density Profiles

    Science.gov (United States)

    Benson, R. F.; Truhlik, V.; Huang, X.; Wang, Y.; Bilitza, D.

    2011-01-01

    The topside-sounders on the four satellites of the International Satellites for Ionospheric Studies (ISIS) program were designed as analog systems. The resulting ionograms were displayed on 35-mm film for analysis by visual inspection. Each of these satellites, launched between 1962 and 1971, produced data for 10 to 20 years. A number of the original telemetry tapes from this large data set have been converted directly into digital records. Software, known as the TOPside Ionogram Scalar with True-height (TOPIST) algorithm has been produced that enables the automatic inversion of ISIS-2 ionogram reflection traces into topside vertical electron-density profiles Ne(h). More than million digital Alouette/ISIS topside ionograms have been produced and over 300,000 are from ISIS 2. Many of these ISIS-2 ionograms correspond to a passive mode of operation for the detection of natural radio emissions and thus do not contain ionospheric reflection traces. TOPIST, however, is not able to produce Ne(h) profiles from all of the ISIS-2 ionograms with reflection traces because some of them did not contain frequency information. This information was missing due to difficulties encountered during the analog-to-digital conversion process in the detection of the ionogram frame-sync pulse and/or the frequency markers. Of the many digital topside ionograms that TOPIST was able to process, over 200 were found where direct comparisons could be made with Ne(h) profiles that were produced by manual scaling in the early days of the ISIS program. While many of these comparisons indicated excellent agreement (inversion process: (1) improve the quality of the digital ionogram database by remedying the missing frequency-information problem when possible, and (2) using the above-mentioned comparisons as teaching examples of how to improve the original TOPIST software.

  11. Study of edge turbulence in tokamak plasmas

    International Nuclear Information System (INIS)

    Sarazin, Y.

    1997-01-01

    The aim of this work is to propose a new frame to study turbulent transport in plasmas. In order to avoid the restraint of scale separability the forcing by flux is used. A critical one-dimension self-organized cellular model is developed. In keeping with experience the average transport can be described by means of diffusion and convection terms whereas the local transport could not. The instability due to interchanging process is thoroughly studied and some simplified equations are derived. The proposed model agrees with the following experimental results: the relative fluctuations of density are maximized on the edge, the profile shows an exponential behaviour and the amplitude of density fluctuations depends on ionization source strongly. (A.C.)

  12. CO2 laser imaging heterodyne and phase contrast interferometer for density profile and fluctuation measurements in LHD

    International Nuclear Information System (INIS)

    Tanaka, K.; Michael, C.; Akiyama, T.; Kawahata, K.; Ito, Y.; Vyacheslavov, L.N.; Sanin, A.L.; Okajima, S.

    2007-01-01

    A CO 2 laser heterodyne imaging interferometer (CO 2 HI) and a CO 2 laser phase contrast imaging interferometer (CO 2 PCI) were installed in LHD. The purpose of CO 2 HI is to measure electron density profile at high density (>1x10 20 m -3 ), where the existing far infrared laser (wavelength 118.9 μm) interferometer suffers from fringe jump due to the reduction of signal intensity caused by refraction. In the beginning of 10th LHD experimental campaign (2006-2007), sixty three three of CO 2 HI with 10 channels of YAG HI for vibration compensation, and in the later of 10th LHD experimental campaign. Eighty one channels CO 2 HI and 15 channels YAG HI became available. The purpose of CO 2 PCI is to measure turbulent fluctuation, which can contribute to the energy and particle transport. In order to get local fluctuation information, magnetic shear technique was applied with use of 48 (6 by 8) channel two dimensional detector. (author)

  13. em>d-wave superfluid with gapless edges in a cold-atom trap

    DEFF Research Database (Denmark)

    Larsen, Anne-Louise Gadsbølle; Francis Song, H.; Le Hur, Karyn

    2012-01-01

    and competing phases. In particular, at low temperatures, this allows the realization of a d-wave superfluid region surrounded by purely (gapless) normal edges. Solving the Bogoliubov–de Gennes equations and comparing them with the local density approximation, we show that the proximity to the Mott insulator...... is revealed by a downturn of the Fermi liquid order parameter at the center of the trap where the d-wave gap has a maximum. The density profile evolves linearly with distance....

  14. Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

    Energy Technology Data Exchange (ETDEWEB)

    Palomares, J.M., E-mail: f02palij@gmail.co [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Iordanova, E.; Veldhuizen, E.M. van; Baede, L. [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Gamero, A.; Sola, A. [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Mullen, J.J.A.M. van der, E-mail: j.j.a.m.v.d.Mullen@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)

    2010-03-15

    The axial profiles of the electron density n{sub e} and electron temperature T{sub e} of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10{sup 18} < n{sub e} < 8 x 10{sup 19} m{sup -3} and 1.1 < T{sub e} < 2.0 eV. Due to several improvements of the setup we could reduce the errors of n{sub e} and T{sub e} down to 8% and 3%, respectively. It is found that n{sub e} decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T{sub e} does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

  15. H-mode edge rotation in W7-AS

    International Nuclear Information System (INIS)

    Hirsch, M.; Baldzuhn, J.; Ehmler, H.; Grigull, P.; Maassberg, H.; McCormick, K.; Wagner, F.; Wobig, H.

    2005-01-01

    In W7-AS three regimes of improved confinement exist which base on negative radial electric fields at the plasma edge resulting there from ion-root conditions of the ambipolar radial fluxes. Experimental control besides the magnetic configuration is given via the edge density profile i.e. the recycling and fuelling conditions. However, the ordering element seems to be the radial electric field profile (respectively its shear) and its interplay with the gradients of ion temperature and density. At low to medium densities the so called optimum confinement regime occurs with maximum density gradients located well inside the plasma boundary and large negative values of E r extending deep in the bulk plasma. For a large inner fraction of the bulk the ion temperature can be sufficiently high that ion transport conditions already can be explained by neoclassics. This regime delivers maximum values of T i , τ e and n τ e T i . Density gradients located right inside the plasma boundary result in the classical H-mode phenomena reminiscent to other toroidal devices with the capability of an edge layer with nearly complete suppression of turbulence either quasi stationary (in a quiescent H-mode) or intermittently (in between ELMs). At even higher densities and highly collisional plasmas with the maximum of ∇n shifted to or even out of the plasma boundary the High Density H-mode (HDH) opens access to steady state conditions with no measurable impurity accumulation. These improved confinement regimes are accessed and left via significant transitions of the transport properties albeit these transitions occur on rather different timescales. A comprehensive picture of improved edge confinement regimes in W7-AS is drawn based on the assumption that a weak edge bounded transport barrier resulting from the ion root conditions (thus E r <0) is the ground state of the (turbulent) edge plasma and already behaves as a barrier for anomalous transport. On top of that the classical H

  16. Improving the AGR fuel testing power density profile versus irradiation-time in the advanced test reactor

    International Nuclear Information System (INIS)

    Chang, Gray S.; Lillo, Misti A.; Maki, John T.; Petti, David A.

    2009-01-01

    The Very High Temperature gas-cooled Reactor (VHTR), which is currently being developed, achieves simplification of safety through reliance on ceramic-coated fuel particles. Each TRISO-coated fuel particle has its own containment which serves as the principal barrier against radionuclide release under normal operating and accident conditions. These fuel particles, in the form of graphite fuel compacts, are currently undergoing a series of irradiation tests in the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL) to support the Advanced Gas-Cooled Reactor (AGR) fuel qualification program. A representive coated fuel particle with an 235 U enrichment of 19.8 wt% was used in this analysis. The fuel burnup analysis tool used to perform the neutronics study reported herein, couples the Monte Carlo transport code MCNP, with the radioactive decay and burnup code ORIGEN2. The fuel burnup methodology known as Monte-Carlo with ORIGEN2 (MCWO) was used to evaluate the AGR experiment assembly and demonstrate compliance with ATR safety requirements. For the AGR graphite fuel compacts, the MCWO-calculated fission power density (FPD) due to neutron fission in 235 U is an important design parameter. One of the more important AGR fuel testing requirements is to maintain the peak fuel compact temperature close to 1250degC throughout the proposed irradiation campaign of 550 effective full power days (EFPDs). Based on the MCWO-calculated FPD, a fixed gas gap size was designed to allow regulation of the fuel compact temperatures throughout the entire fuel irradiation campaign by filling the gap with a mixture of helium and neon gases. The chosen fixed gas gap can only regulate the peak fuel compact temperature in the desired range during the irradiation test if the ratio of the peak power density to the time-dependent low power density (P/T) at 550 EFPDs is less than 2.5. However, given the near constant neutron flux within the ATR driver core and the depletion of 235 U

  17. Magnetohydrodynamic simulations of density-limit disruptions in tokamaks

    International Nuclear Information System (INIS)

    Kleva, R.G.; Drake, J.F.; Denton, R.E.

    1990-01-01

    Magnetohydrodynamic simulations are presented which demonstrate that density limit disruptions can be triggered by edge radiation which destabilizes a q = 1 kink followed by a q = 2 tearing mode. A bubble of cold plasma is injected from the edge into the center by the q = 1 kink. The q = 2 mode then broadens the current profile and throws the hot plasma to the wall. The MHD simulations presented are the first to successfully reproduce several key features of density limit disruptions including (1) the rapid drop in the central temperature, (2) the rapid expansion of the current profile, (3) the m = 1 cold bubble which is seen to be injected from the edge into the center during density limit disruptions on JET, and (4) disruptions in sawtoothing discharges. (author)

  18. Joint refinement model for the spin resolved one-electron reduced density matrix of YTiO3 using magnetic structure factors and magnetic Compton profiles data.

    Science.gov (United States)

    Gueddida, Saber; Yan, Zeyin; Kibalin, Iurii; Voufack, Ariste Bolivard; Claiser, Nicolas; Souhassou, Mohamed; Lecomte, Claude; Gillon, Béatrice; Gillet, Jean-Michel

    2018-04-28

    In this paper, we propose a simple cluster model with limited basis sets to reproduce the unpaired electron distributions in a YTiO 3 ferromagnetic crystal. The spin-resolved one-electron-reduced density matrix is reconstructed simultaneously from theoretical magnetic structure factors and directional magnetic Compton profiles using our joint refinement algorithm. This algorithm is guided by the rescaling of basis functions and the adjustment of the spin population matrix. The resulting spin electron density in both position and momentum spaces from the joint refinement model is in agreement with theoretical and experimental results. Benefits brought from magnetic Compton profiles to the entire spin density matrix are illustrated. We studied the magnetic properties of the YTiO 3 crystal along the Ti-O 1 -Ti bonding. We found that the basis functions are mostly rescaled by means of magnetic Compton profiles, while the molecular occupation numbers are mainly modified by the magnetic structure factors.

  19. Edge Detection,

    Science.gov (United States)

    1985-09-01

    PROJECT. T ASK0 Artificial Inteligence Laboratory AREA It WORK UNIT NUMBERS V 545 Technology Square ( Cambridge, HA 02139 I I* CONTOOL1LIN@4OFFICE NAME...ARD-A1t62 62 EDGE DETECTION(U) NASSACNUSETTS INST OF TECH CAMBRIDGE 1/1 ARTIFICIAL INTELLIGENCE LAB E C HILDRETH SEP 85 AI-M-8 N99SI4-8S-C-6595...used to carry out this analysis. cce~iO a N) ’.~" D LI’BL. P p ------------ Sj. t i MASSACHUSETTS INSTITUTE OF TECHNOLOGY i ARTIFICIAL INTELLIGENCE

  20. Improved core-edge tokamak transport simulations with the CORSICA 2 code

    International Nuclear Information System (INIS)

    Tarditi, A.; Cohen, R.H.; Crotinger, J.A.

    1996-01-01

    The CORSICA 2 code models the nonlinear transport between the core and the edge of a tokamak plasma. The code couples a 2D axisymmetric edge/SOL model (UEDGE) to a 1D model for the radial core transport in toroidal flux coordinates (the transport module from the CORSICA 1 code). The core density and temperature profiles are joined to the flux-surface average profiles from the 2D code sufficiently inside the magnetic separatrix, at a flux surface on which the edge profiles are approximately constant. In the present version of the code, the deuterium density and electron and ion temperatures are coupled. The electron density is determined by imposing quasi-neutrality, both in the core and in the edge. The model allows the core-edge coupling of multiple ion densities while retaining a single temperature (corresponding to the equilibration value) for the all ion species. Applications of CORSICA 2 to modeling the DIII-D tokamak are discussed. This work will focus on the simulation of the L-H transition, coupling a single ion species (deuterium) and the two (electron and ion) temperatures. These simulations will employ a new self-consistent model for the L-H transition that is being implemented in the UEDGE code. Applications to the modeling of ITER ignition scenarios are also discussed. This will involve coupling a second density species (the thermal alphas), bringing the total number of coupled variables up to four. Finally, the progress in evolving the magnetic geometry is discussed. Currently, this geometry is calculated by CORSICA's MHD equilibrium module (TEQ) at the beginning of the run and fixed thereafter. However, CORSICA 1 can evolve this geometry quasistatically, and this quasistatic treatment is being extended to include the edge/SOL geometry. Recent improvements for code speed-up are also presented

  1. Dislocation density and Burgers vector population in fiber-textured Ni thin films determined by high-resolution X-ray line profile analysis

    DEFF Research Database (Denmark)

    Csiszár, Gábor; Pantleon, Karen; Alimadadi, Hossein

    2012-01-01

    distribution are determined by high-resolution X-ray diffraction line profile analysis. The substructure parameters are correlated with the strength of the films by using the combined Taylor and Hall-Petch relations. The convolutional multiple whole profile method is used to obtain the substructure parameters......Nanocrystalline Ni thin films have been produced by direct current electrodeposition with different additives and current density in order to obtain 〈100〉, 〈111〉 and 〈211〉 major fiber textures. The dislocation density, the Burgers vector population and the coherently scattering domain size...

  2. First-principles study of graphene edge properties and flake shapes

    OpenAIRE

    Gan, Chee Kwan; Srolovitz, David J.

    2009-01-01

    We use density functional theory to determine the equilibrium shape of graphene flakes, through the calculation of the edge orientation dependence of the edge energy and edge stress of graphene nanoribbons. The edge energy is a nearly linear function of edge orientation angle; increasing from the armchair orientation to the zigzag orientation. Reconstruction of the zigzag edge lowers its energy to less than that of the armchair edge. The edge stress for all edge orientations is compressive, h...

  3. Gemini NIFS survey of feeding and feedback processes in nearby active galaxies - II. The sample and surface mass density profiles

    Science.gov (United States)

    Riffel, R. A.; Storchi-Bergmann, T.; Riffel, R.; Davies, R.; Bianchin, M.; Diniz, M. R.; Schönell, A. J.; Burtscher, L.; Crenshaw, M.; Fischer, T. C.; Dahmer-Hahn, L. G.; Dametto, N. Z.; Rosario, D.

    2018-02-01

    We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14-195 keV luminosities LX ≥ 1041.5 erg s-1, redshift z ≤ 0.015, being accessible for observations with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended [O III]λ5007 emission. Our goal is to study Active Galactic Nucleus (AGN) feeding and feedback processes from near-infrared integral-field spectra, which include both ionized (H II) and hot molecular (H2) emission. This sample is complemented by other nine Seyfert galaxies previously observed with NIFS. We show that the host galaxy properties (absolute magnitudes MB, MH, central stellar velocity dispersion and axial ratio) show a similar distribution to those of the 69 BAT AGN. For the 20 galaxies already observed, we present surface mass density (Σ) profiles for H II and H2 in their inner ˜500 pc, showing that H II emission presents a steeper radial gradient than H2. This can be attributed to the different excitation mechanisms: ionization by AGN radiation for H II and heating by X-rays for H2. The mean surface mass densities are in the range (0.2 ≤ ΣH II ≤ 35.9) M⊙ pc-2, and (0.2 ≤ ΣH2 ≤ 13.9)× 10-3 M⊙ pc-2, while the ratios between the H II and H2 masses range between ˜200 and 8000. The sample presented here will be used in future papers to map AGN gas excitation and kinematics, providing a census of the mass inflow and outflow rates and power as well as their relation with the AGN luminosity.

  4. Living edge

    DEFF Research Database (Denmark)

    Earon, Ofri

    2014-01-01

    was originally introduced to enhance indoor qualities including light and view. Throughout the paper, it is argued that these ecological motives have grown to architectural and urban dimensions. The paper analyzes the characteristics and potentials of these dimensions and their interconnections. The paper...... on the ground level, but there is a lack of recognition in the significance of communicative characters as well at the higher part of the edge. The city’s planning approach is “Consider urban life before urban space. Consider urban space before buildings” This urban strategy neglects the possible architectural...... contribution to the street atmosphere and its effect on urban life. Bay balcony has been a common architectural element in Copenhagen’s residential buildings, since the end of the twenties. It is a domestic border with an architectural thickness combining window, door, windowsill and balcony. The bay balcony...

  5. Energetics of edge oxidization of graphene nanoribbons

    Science.gov (United States)

    Yasuma, Airi; Yamanaka, Ayaka; Okada, Susumu

    2018-06-01

    On the basis of the density functional theory, we studied the geometries and energetics of O atoms adsorbed on graphene edges for simulating the initial stage of the edge oxidization of graphene. Our calculations showed that oxygen atoms are preferentially adsorbed onto the graphene edges with the zigzag portion, resulting in a large adsorption energy of about 5 eV. On the other hand, the edges with armchair shape are rarely oxidized, or the oxidization causes substantial structural reconstructions, because of the stable covalent bond at the armchair edge with the triple bond nature. Furthermore, the energetics sensitively depends on the edge angles owing to the inhomogeneity of the charge density at the edge atomic sites.

  6. Edge Modeling by Two Blur Parameters in Varying Contrasts.

    Science.gov (United States)

    Seo, Suyoung

    2018-06-01

    This paper presents a method of modeling edge profiles with two blur parameters, and estimating and predicting those edge parameters with varying brightness combinations and camera-to-object distances (COD). First, the validity of the edge model is proven mathematically. Then, it is proven experimentally with edges from a set of images captured for specifically designed target sheets and with edges from natural images. Estimation of the two blur parameters for each observed edge profile is performed with a brute-force method to find parameters that produce global minimum errors. Then, using the estimated blur parameters, actual blur parameters of edges with arbitrary brightness combinations are predicted using a surface interpolation method (i.e., kriging). The predicted surfaces show that the two blur parameters of the proposed edge model depend on both dark-side edge brightness and light-side edge brightness following a certain global trend. This is similar across varying CODs. The proposed edge model is compared with a one-blur parameter edge model using experiments of the root mean squared error for fitting the edge models to each observed edge profile. The comparison results suggest that the proposed edge model has superiority over the one-blur parameter edge model in most cases where edges have varying brightness combinations.

  7. Disruption avoidance in the SINP-Tokamak by means of electrode-biasing at the plasma edge

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Debjyoti [Saha Institute of Nuclear Physics, 1/AF-Bidhannagar, Kolkata 700064, WB (India); Instituto de Ciencias Nucleares-UNAM, Mexico D.F. 04510 (Mexico); Pal, Rabindranath [Saha Institute of Nuclear Physics, 1/AF-Bidhannagar, Kolkata 700064, WB (India); Martinell, Julio J. [Instituto de Ciencias Nucleares-UNAM, Mexico D.F. 04510 (Mexico); Ghosh, Joydeep; Chattopadhyay, Prabal K. [Institute for Plasma Research, Gandhinagar (India)

    2013-05-15

    Control of plasma disruption by a biased edge electrode is reported in SINP-Tokamak. The features that characterize a plasma disruption are reduced with increasing bias potential. The disruption can be completely suppressed with the concomitant stabilization of observed MHD modes that are allegedly precursors of the disruption. An m = 3/n = 1 tearing mode, which apparently causes disruption can be stabilized when a negative biasing potential is applied near the edge. These changes in the disruptive behavior with edge biasing are hypothesized to be due to changes in the current density profile.

  8. Disruption avoidance in the SINP-Tokamak by means of electrode-biasing at the plasma edge

    International Nuclear Information System (INIS)

    Basu, Debjyoti; Pal, Rabindranath; Martinell, Julio J.; Ghosh, Joydeep; Chattopadhyay, Prabal K.

    2013-01-01

    Control of plasma disruption by a biased edge electrode is reported in SINP-Tokamak. The features that characterize a plasma disruption are reduced with increasing bias potential. The disruption can be completely suppressed with the concomitant stabilization of observed MHD modes that are allegedly precursors of the disruption. An m = 3/n = 1 tearing mode, which apparently causes disruption can be stabilized when a negative biasing potential is applied near the edge. These changes in the disruptive behavior with edge biasing are hypothesized to be due to changes in the current density profile

  9. Experimental study of particle transport and density fluctuation in LHD

    International Nuclear Information System (INIS)

    Tanaka, K.; Michael, C.; Sanin, A.

    2005-01-01

    A variety of electron density (n e ) profiles have been observed in Large Helical Device (LHD). The density profiles change dramatically with heating power and toroidal magnetic field (B t ) under the same line averaged density. The particle transport coefficients, i.e., diffusion coefficient (D) and convection velocity (V) are experimentally obtained in the standard configuration from density modulation experiments. The values of D and V are estimated separately in the core and edge. The diffusion coefficients are found to be a strong function of electron temperature (T e ) and are proportional to T e 1.7±0.9 in the core and T e 1.1±0.14 in the edge. Edge diffusion coefficients are proportional to B t -2.08 . It is found that the scaling of D in the edge is close to gyro-Bohm-like in nature. Non-zero V is observed and it is found that the electron temperature gradient can drive particle convection, particularly in the core region. The convection velocity in the core reverses direction from inward to outward as the T e gradient increases. In the edge, convection is inward directed in most cases of the present data set. It shows a modest tendency, being proportional to T e gradient and remaining inward directed. However, the toroidal magnetic field also significantly affects the value and direction of V. The density fluctuation spectrum varies with heating power suggesting that it has an influence on particle transport. The value of K sub(perpendicular) ρ i is around 0.1, as expected for gyro-Bohm diffusion. Fluctuations are localized in both positive and negative density gradient regions of the hollow density profiles. The fluctuation power in each region is clearly distinguished having different phase velocity profiles. (author)

  10. Effects of probiotic supplementation in different nutrient density diets on growth performance, nutrient digestibility, blood profiles, fecal microflora and noxious gas emission in weaning pig.

    Science.gov (United States)

    Lan, Ruixia; Tran, Hoainam; Kim, Inho

    2017-03-01

    Probiotics can serve as alternatives to antibiotics to increase the performance of weaning pigs, and the intake of probiotics is affected by dietary nutrient density. The objective of this study was to evaluate the effects of a probiotic complex in different nutrient density diets on growth performance, digestibility, blood profiles, fecal microflora and noxious gas emission in weaning pigs. From day 22 to day 42, both high-nutrient-density and probiotic complex supplementation diets increased (P probiotic complex supplementation diets had higher (P probiotic complex supplementation diets. Interactive effects on average daily feed intake (ADFI) were observed from day 22 to day 42 and overall, where probiotic complex improved ADFI more dramatically in low-nutrient-density diets. The beneficial effects of probiotic complex (Bacillus coagulans, Bacillus licheniformis, Bacillus subtilis and Clostridium butyricum) supplementation on ADFI is more dramatic with low-nutrient-density diets. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  11. Latent Profiles of Macronutrient Density and their Association with Mobility Limitations in an Observational Longitudinal Study of Older U.S. Adults.

    Science.gov (United States)

    Bishop, N J; Zuniga, K E; Lucht, A L

    2018-01-01

    Our first objective was to estimate empirically-derived subgroups (latent profiles) of observed carbohydrate, protein, and fat intake density in a nationally representative sample of older U.S. adults. Our second objective was to determine whether membership in these groups was associated with levels of, and short term change in, physical mobility limitations. Measures of macronutrient density were taken from the 2013 Health Care and Nutrition Study, an off-year supplement to the Health and Retirement Study, which provided indicators of physical mobility limitations and sociodemographic and health-related covariates. 3,914 community-dwelling adults age 65 years and older. Percent of daily calories from carbohydrate, protein, and fat were calculated based on responses to a modified Harvard food frequency questionnaire. Latent profile analysis was used to describe unobserved heterogeneity in measures of carbohydrate, protein, and fat density. Mobility limitation counts were based on responses to 11 items indicating physical limitations. Poisson regression models with autoregressive controls were used to identify associations between macronutrient density profile membership and mobility limitations. Sociodemographic and health-related covariates were included in all Poisson regression models. Four latent subgroups of macronutrient density were identified: "High Carbohydrate", "Moderate with Fat", "Moderate", and "Low Carbohydrate/High Fat". Older adults with the lowest percentage of daily calories coming from carbohydrate and the greatest percentage coming from fat ("Low Carbohydrate/High Fat") were found to have greater reported mobility limitations in 2014 than those identified as having moderate macronutrient density, and more rapid two-year increases in mobility limitations than those identified as "Moderate with Fat" or "Moderate". Older adults identified as having the lowest carbohydrate and highest fat energy density were more likely to report a greater number

  12. Visible imaging of edge turbulence in NSTX

    International Nuclear Information System (INIS)

    Zweben, S.; Maqueda, R.; Hill, K.; Johnson, D.

    2000-01-01

    Edge plasma turbulence in tokamaks and stellarators is believed to cause the radical heat and particle flux across the separatrix and into the scrape-off-layers of these devices. This paper describes initial measurements of 2-D space-time structure of the edge density turbulence made using a visible imaging diagnostic in the National Spherical Torus Experiment (NSTX). The structure of the edge turbulence is most clearly visible using a method of gas puff imaging to locally illuminate the edge density turbulence

  13. Visible imaging of edge turbulence in NSTX

    International Nuclear Information System (INIS)

    S. Zweben; R. Maqueda; K. Hill; D. Johnson; S. Kaye; H. Kugel; F. Levinton; R. Maingi; L. Roquemore; S. Sabbagh; G. Wurden

    2000-01-01

    Edge plasma turbulence in tokamaks and stellarators is believed to cause the radial heat and particle flux across the separatrix and into the scrape-off-layers of these devices. This paper describes initial measurements of 2-D space-time structure of the edge density turbulence made using a visible imaging diagnostic in the National Spherical Torus Experiment (NSTX). The structure of the edge turbulence is most clearly visible using a method of ''gas puff imaging'' to locally illuminate the edge density turbulence

  14. The effect of ingestion of egg and low density lipoprotein (LDL oxidation on serum lipid profiles in hypercholesterolemic women

    Directory of Open Access Journals (Sweden)

    Taweesak Techakriengkrai1

    2012-04-01

    Full Text Available Egg is a major source of dietary cholesterol. The serum lipid response to egg shows marked individual variation, beingpartly genetically determined, and influence by ethnic groups and the overall diet response. In the present investigation, weinvestigated the effect of ingestion of egg and low density lipoprotein (LDL oxidation on serum lipid profile in hypercholesterolemicwomen. Forty hypercholesterolemic women volunteers on a cholesterol-lowering diet (CLD divided into 2 groups ina randomized controlled cross-over study of one egg per day (CLD + 1 egg for 4-week and three eggs per day (CLD + 3 eggsfor 4-week, separated by 4-week period egg-free. The body weight, blood pressure, serum lipid profiles and LDL oxidationwere measured at 4-week intervals. Cholesterol-lowering diet was applied throughout the study by a dietitian using a foodexchange program and 3-day dietary recall every 4 weeks. Compared to the values obtained at baseline, the mean serum totalcholesterol and LDL cholesterol of CLD + 3 eggs was not significantly different from baseline whereas of those of 4-week ofegg-free period and CLD + 1 egg were significantly decreased (238.3±2.9 mg/dL and 228.3±4.7 mg/dL compared to thebaseline (252.2±5.9 mg/dL as was LDL cholesterol (161.2±3.0 mg/dL and 155.7±4.8 mg/dL compared to the baseline (177.5±6.0 mg/dL (p<0.05. The study showed there were no significantly difference the body weight, blood pressure, HDL cholesterol,triglycerides or LDL oxidation during the study. However, serum total cholesterol and LDL cholesterol of 1 or 3 eggsper day after 4-week of egg consumption was not significantly higher than the egg-free period. The study suggests that inhypercholesterolemic women who are on cholesterol-lowering diet, consuming one or three eggs per day did not raise serumcholesterol or LDL cholesterol levels at 4 weeks or result in any change in LDL oxidation.

  15. GALAXY CLUSTERING AND PROJECTED DENSITY PROFILES AS TRACED BY SATELLITES IN PHOTOMETRIC SURVEYS: METHODOLOGY AND LUMINOSITY DEPENDENCE

    International Nuclear Information System (INIS)

    Wang Wenting; Jing, Y. P.; Li Cheng; Okumura, Teppei; Han Jiaxin

    2011-01-01

    We develop a new method which measures the projected density distribution w p (r p )n of photometric galaxies surrounding a set of spectroscopically identified galaxies and simultaneously the projected cross-correlation function w p (r p ) between the two populations. In this method, we are able to divide the photometric galaxies into subsamples in luminosity intervals even when redshift information is unavailable, enabling us to measure w p (r p )n and w p (r p ) as a function of not only the luminosity of the spectroscopic galaxy, but also that of the photometric galaxy. Extensive tests show that our method can measure w p (r p ) in a statistically unbiased way. The accuracy of the measurement depends on the validity of the assumption inherent to the method that the foreground/background galaxies are randomly distributed and are thus uncorrelated with those galaxies of interest. Therefore, our method can be applied to the cases where foreground/background galaxies are distributed in large volumes, which is usually valid in real observations. We have applied our method to data from the Sloan Digital Sky Survey (SDSS) including a sample of 10 5 luminous red galaxies at z ∼ 0.4 and a sample of about half a million galaxies at z ∼ 0.1, both of which are cross-correlated with a deep photometric sample drawn from the SDSS. On large scales, the relative bias factor of galaxies measured from w p (r p ) at z ∼ 0.4 depends on luminosity in a manner similar to what is found for those at z ∼ 0.1, which are usually probed by autocorrelations of spectroscopic samples in previous studies. On scales smaller than a few Mpc and at both z ∼ 0.4 and z ∼ 0.1, the photometric galaxies of different luminosities exhibit similar density profiles around spectroscopic galaxies at fixed luminosity and redshift. This provides clear observational support for the assumption commonly adopted in halo occupation distribution models that satellite galaxies of different luminosities are

  16. LoCuSS: THE MASS DENSITY PROFILE OF MASSIVE GALAXY CLUSTERS AT z = 0.2 {sup ,}

    Energy Technology Data Exchange (ETDEWEB)

    Okabe, Nobuhiro; Umetsu, Keiichi [Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P. O. Box 23-141, Taipei 10617, Taiwan (China); Smith, Graham P. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Takada, Masahiro [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Chiba 277-8582 (Japan); Futamase, Toshifumi, E-mail: okabe@asiaa.sinica.edu.tw, E-mail: gps@star.sr.bham.ac.uk [Astronomical Institute, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

    2013-06-01

    We present a stacked weak-lensing analysis of an approximately mass-selected sample of 50 galaxy clusters at 0.15 < z < 0.3, based on observations with Suprime-Cam on the Subaru Telescope. We develop a new method for selecting lensed background galaxies from which we estimate that our sample of red background galaxies suffers just 1% contamination. We detect the stacked tangential shear signal from the full sample of 50 clusters, based on this red sample of background galaxies, at a total signal-to-noise ratio of 32.7. The Navarro-Frenk-White model is an excellent fit to the data, yielding sub-10% statistical precision on mass and concentration: M{sub vir}=7.19{sup +0.53}{sub -0.50} Multiplication-Sign 10{sup 14} h{sup -1} M{sub sun}, c{sub vir}=5.41{sup +0.49}{sub -0.45} (c{sub 200}=4.22{sup +0.40}{sub -0.36}). Tests of a range of possible systematic errors, including shear calibration and stacking-related issues, indicate that they are subdominant to the statistical errors. The concentration parameter obtained from stacking our approximately mass-selected cluster sample is broadly in line with theoretical predictions. Moreover, the uncertainty on our measurement is comparable with the differences between the different predictions in the literature. Overall, our results highlight the potential for stacked weak-lensing methods to probe the mean mass density profile of cluster-scale dark matter halos with upcoming surveys, including Hyper-Suprime-Cam, Dark Energy Survey, and KIDS.

  17. Nonlinear neoclassical transport in toroidal edge plasmas

    International Nuclear Information System (INIS)

    Fueloep, T.; Helander, P.

    2001-01-01

    In conventional neoclassical theory, the density and temperature gradients are not allowed to be as steep as frequently observed in the tokamak edge. In this paper the theory of neoclassical transport in a collisional, impure plasma is extended to allow for steeper profiles than normally assumed. The dynamics of highly charged impurity ions then becomes nonlinear, which affects the transport of all species. As earlier found in the banana regime, when the bulk plasma gradients are large the impurity ions undergo a poloidal redistribution, which reduces their parallel friction with the bulk ions and suppresses the neoclassical ion particle flux. The neoclassical confinement is thus improved in regions with large radial gradients. When the plasma is collisional and the gradients are large, the impurities accumulate on the inboard side of the torus

  18. 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.

  19. New Vary-Chap Profile of the Topside Ionosphere Electron Density Distribution for use with the IRI Model and the GIRO Real-Time Data

    Science.gov (United States)

    Nsumei, Patrick; Reinisch, Bodo W.; Huang, Xueqin; Bilitza, Dieter

    2012-01-01

    A new Vary-Chap function is introduced for the empirical modeling of the electron density N(h) profile in the topside ionosphere that uses a shape function S(h) in the generalized Chapman function. The Vary-Chap profile extends the bottomside profile that is specified by the IRI model or measured by the Global Ionospheric Radio Observatory (GIRO) to the altitude of the ISIS-2 satellite. Some 80,000 topside profiles, measured by the topside sounder on the ISIS-2 satellite were analyzed, and the shape function S(h) was calculated for each profile. A parameterized function S*(h), composed of two sub-functions S1(h) and S2(h), is fitted to the measured S(h) profile using three free parameters. At altitudes just above the F2 layer peak height hmF2, the shape function S1 controls S(h), and at greater altitudes S2 controls S(h). The height of the intersection of S1 and S2 is defined as the transition height h(sub T) indicating the transition from an O(+) to an H(+)-dominated profile shape. The observed transition heights range from approx.500 km to 800 km.

  20. A gravity study along a profile across the Sichuan Basin, the Qinling Mountains and the Ordos Basin (central China): Density, isostasy and dynamics

    Science.gov (United States)

    Zhang, Yongqian; Teng, Jiwen; Wang, Qianshen; Lü, Qingtian; Si, Xiang; Xu, Tao; Badal, José; Yan, Jiayong; Hao, Zhaobing

    2017-10-01

    In order to investigate the structure of the crust beneath the Middle Qinling Mountains (MQL) and neighboring areas in the North China Block and South China Block, a north-south gravity profile from Yuquan in the Sichuan Basin to Yulin in the Ordos Basin was conducted in 2011. The Bouguer gravity anomaly is determined from a high-quality gravity dataset collected between 31°N and 36°N of latitude, and varies between -200 and -110 mGal in the study region. Using accredited velocity density relationships, an initial crust-mantle density model is constructed for MQL and adjacent areas, which is later refined interactively to simulate the observed gravity anomaly. The present study reveals the features of the density and Bouguer gravity with respect to the tectonic units sampled by the profile. The lithosphere density model shows typical density values that depict a layered structure and allow differentiate the blocks that extend along the reference profile. The gravity field calculated by forward modeling from the final density distribution model correlates well with the measured gravity field within a standard deviation of 1.26 mGal. The density in the crystalline crust increases with depth from 2.65 g/cm3 up to the highest value of 2.95 g/cm3 near the bottom of the crust. The Conrad interface is identified as a density jump of about 0.05 g/cm3. The average density of the crust in MQL is clearly lower than the density in the formations on both sides. Starting from a combined Airy-Pratt isostatic compensation model, a partly compensated crust is found below MQL, suggesting future growth of the crust, unlike the Ordos and Sichuan basins that will remain stable. On the basis of the density and isostatic state of the crust and additional seismological research, such as the P-wave velocity model and Poisson's ratio, it is concluded that the lower crust delamination is a reasonable interpretation for the geophysical characteristics below the Qinling Orogen.

  1. Evolution of edge pedestal transport between edge-localized modes in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, J.-P.; Stacey, W. M.; Mellard, S. C. [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Groebner, R. J. [General Atomics, San Diego, California 92186 (United States)

    2015-02-15

    Evolution of measured profiles of densities, temperatures, and velocities in the edge pedestal region between successive ELM (edge-localized mode) events are analyzed and interpreted in terms of the constraints imposed by particle, momentum and energy balance in order to gain insights regarding the underlying evolution of transport processes in the edge pedestal between ELMs in a series of DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] discharges. The data from successive inter-ELM periods during an otherwise steady-state phase of the discharges were combined into a composite inter-ELM period for the purpose of increasing the number of data points in the analysis. Variation of diffusive and non-diffusive (pinch) particle, momentum, and energy transport over the inter-ELM period are interpreted using the GTEDGE code for discharges with plasma currents from 0.5 to 1.5 MA and inter-ELM periods from 50 to 220 ms. Diffusive transport is dominant for ρ < 0.925, while non-diffusive and diffusive transport are very large and nearly balancing in the sharp gradient region 0.925 < ρ < 1.0. During the inter-ELM period, diffusive transport increases slightly more than non-diffusive transport, increasing total outward transport. Both diffusive and non-diffusive transport have a strong inverse correlation with plasma current.

  2. Edge localized mode physics and operational aspects in tokamaks

    International Nuclear Information System (INIS)

    Becoulet, M; Huysmans, G; Sarazin, Y; Garbet, X; Ghendrih, Ph; Rimini, F; Joffrin, E; Litaudon, X; Monier-Garbet, P; Ane, J-M; Thomas, P; Grosman, A; Parail, V; Wilson, H; Lomas, P; Vries, P de; Zastrow, K-D; Matthews, G F; Lonnroth, J; Gerasimov, S; Sharapov, S; Gryaznevich, M; Counsell, G; Kirk, A; Valovic, M; Buttery, R; Loarte, A; Saibene, G; Sartori, R; Leonard, A; Snyder, P; Lao, L L; Gohil, P; Evans, T E; Moyer, R A; Kamada, Y; Chankin, A; Oyama, N; Hatae, T; Asakura, N; Tudisco, O; Giovannozzi, E; Crisanti, F; Perez, C P; Koslowski, H R; Eich, T; Sips, A; Horton, L; Hermann, A; Lang, P; Stober, J; Suttrop, W; Beyer, P; Saarelma, S

    2003-01-01

    Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely the high confinement regimes, that is, H-modes and advanced scenarios. Theoretical approaches to ELM physics, from a linear ideal magnetohydrodynamic (MHD) stability analysis to non-linear transport models with ELMs are discussed with respect to experimental observations, in particular the fast collapse of pedestal pressure profiles, magnetic measurements and scrape-off layer transport during ELMs. High confinement regimes with different types of ELMs are addressed in this paper in the context of development of operational scenarios for ITER. The key parameters that have been identified at present to reduce the energy losses in Type I ELMs are operation at high density, high edge magnetic shear and high triangularity. However, according to the present experimental scaling for the energy losses in Type I ELMs, the extrapolation of such regimes for ITER leads to unacceptably large heat loads on the divertor target plates exceeding the material limits. High confinement H-mode scenarios at high triangularity and high density with small ELMs (Type II), mixed regimes (Type II and Type I) and combined advanced regimes at high beta p are discussed for present-day tokamaks. The optimum combination of high confinement and small MHD activity at the edge in Type II ELM scenarios is of interest to ITER. However, to date, these regimes have been achieved in a rather narrow operational window and far from ITER parameters in terms of collisionality, edge safety factor and beta p . The compatibility of the alternative internal transport barrier (ITB) scenario with edge pedestal formation and ELMs is also addressed. Edge physics issues related to the possible combination of small benign ELMs (Type III, Type II ELMs, quiescent double barrier) and high performance ITBs are discussed for present-day experiments (JET, JT-60U, DIII-D) in

  3. Edge localized mode physics and operational aspects in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Becoulet, M [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Huysmans, G [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Sarazin, Y [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Garbet, X [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Ghendrih, Ph [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Rimini, F [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Joffrin, E [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Litaudon, X [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Monier-Garbet, P [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Ane, J-M [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Thomas, P [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Grosman, A [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Parail, V [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Wilson, H [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Lomas, P [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Vries, P de[Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Zastrow, K-D [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Matthews, G F [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Lonnroth, J [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Gerasimov, S [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom)] [and others

    2003-12-01

    Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely the high confinement regimes, that is, H-modes and advanced scenarios. Theoretical approaches to ELM physics, from a linear ideal magnetohydrodynamic (MHD) stability analysis to non-linear transport models with ELMs are discussed with respect to experimental observations, in particular the fast collapse of pedestal pressure profiles, magnetic measurements and scrape-off layer transport during ELMs. High confinement regimes with different types of ELMs are addressed in this paper in the context of development of operational scenarios for ITER. The key parameters that have been identified at present to reduce the energy losses in Type I ELMs are operation at high density, high edge magnetic shear and high triangularity. However, according to the present experimental scaling for the energy losses in Type I ELMs, the extrapolation of such regimes for ITER leads to unacceptably large heat loads on the divertor target plates exceeding the material limits. High confinement H-mode scenarios at high triangularity and high density with small ELMs (Type II), mixed regimes (Type II and Type I) and combined advanced regimes at high beta{sub p} are discussed for present-day tokamaks. The optimum combination of high confinement and small MHD activity at the edge in Type II ELM scenarios is of interest to ITER. However, to date, these regimes have been achieved in a rather narrow operational window and far from ITER parameters in terms of collisionality, edge safety factor and beta{sub p}. The compatibility of the alternative internal transport barrier (ITB) scenario with edge pedestal formation and ELMs is also addressed. Edge physics issues related to the possible combination of small benign ELMs (Type III, Type II ELMs, quiescent double barrier) and high performance ITBs are discussed for present-day experiments (JET, JT-60U

  4. Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources; Profile der Plasmaparameter und Dichte negativer Wasserstoffionen mittels Laserdetachmentmessungen in HF-angeregten Ionenquellen

    Energy Technology Data Exchange (ETDEWEB)

    Christ-Koch, Sina

    2007-12-20

    This work shows the application of the Laserdetachment method for spatially resolved measurements of negative Hydrogen/Deuterium ion density. It was applied on a high power low pressure RF-driven ion source. The Laser detachment method is based on the measurement of electron currents on a positively biased Langmuir probe before and during/after a laser pulse. The density ratio of negative ions to electrons can be derived from the ratio of currents to the probe. The absolute density of negative ions can be obtained when the electron density is measured with the standard Langmuir probe setup. Measurements with the Langmuir probe additionally yield information about the floating and plasma potential, the electron temperature and the density of positive ions. The Laser detachment setup had to be adapted to the special conditions of the RF-driven source. In particular the existence of RF fields (1 MHz), high source potential (-20 kV), magnetic fields ({proportional_to} 7 mT) and caesium inside the source had to be considered. The density of negative ions could be identified in the range of n(H{sup -})=1.10{sup 17} 1/m{sup 3}, which is in the same order of magnitude as the electron density. Only the application of the Laser detachment method with the Langmuir probe measurements will yield spatially resolved plasma parameters and H- density profiles. The influence of diverse external parameters, such as pressure, RF-power, magnetic fields on the plasma parameters and their profiles were studied and explained. Hence, the measurements lead to a detailed understanding of the processes inside the source. (orig.)

  5. Ion distribution near a mask edge with arbitrary shape for VLSI IC applications

    International Nuclear Information System (INIS)

    Lutsch, A.G.K.; Oosthuizen, D.R.

    1985-01-01

    The profile of the mask edge during ion implantation determines the electrical field in the critical drain region of a MOS-transistor. Equal ion density lines are computed for various mask edges for the example of boron implanted into silicon at 70 keV. Four moments of the impurity depth distribution (without mask material are taken into consideration. Homogenisation and, therefore a higher noise immunity, can be obtained by the proper choice of the mask etching process. The influence of a too-thin mask material is also shown. (author)

  6. Derivation of the threshold condition for the ion temperature gradient mode with an inverted density profile from a simple physics picture

    Science.gov (United States)

    Jhang, Hogun

    2018-05-01

    We show that the threshold condition for the toroidal ion temperature gradient (ITG) mode with an inverted density profile can be derived from a simple physics argument. The key in this picture is that the density inversion reduces the ion compression due to the ITG mode and the electron drift motion mitigates the poloidal potential build-up. This condition reproduces the same result that has been reported from a linear gyrokinetic calculation [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. The destabilizing role of trapped electrons in toroidal geometry is easily captured in this picture.

  7. Edge Thomson scattering on RFX-mod

    International Nuclear Information System (INIS)

    Alfier, A.; Pasqualotto, R.

    2006-01-01

    Electron temperature and density profiles of the RFX-mod experiment are characterized by edge gradients typically steeper than the flatter central region. The main Thomson scattering (TS) diagnostic which measures 84-point profiles along a diameter is mainly devoted to cover the core region. A second TS system has been developed to measure 12-point profiles in the external region 0.8< r/a<1, with a spatial resolution of 1 cm. It uses a single shot ruby laser. Input and collection optics share the same vacuum port and they are mounted on one optical bench, which allows offline aligning the system before connecting it to the vessel. The scattered signal is collected by a row of 12 fibers, while 4 fibers on the sides are used to check the alignment and measure the plasma light. The fibers, arranged in a 4x4 pattern, are fed into a four channel filter spectrometer and the spectrum is detected by a GaAs intensified charge-coupled device camera. The filters are arranged in a zigzag geometry, such that only one detector is needed

  8. Comparison of electron density profiles observed in China's low latitude station with that produced by the International Reference Ionosphere (IRI2001)

    International Nuclear Information System (INIS)

    Zhang Manlian; Shi Jiankui; Wang Xiao

    2003-01-01

    One month's data of ionograms observed by DPS-4 digisonde in China's low latitude station Hainan (19.4 deg N/109.0 deg E) for the high solar activity year 2002 is used to make a comparison study between the observational electron density profiles and that produced by the newly updated International Reference Ionosphere (IRI2001). The present study showed that for the month studied (April, 2002): (1) When B0-Tab value is used, profiles given by IRI2001 are in poor agreement with the observational results during daytime and nearby midnight hours when standard Ne(h) option is chosen, whereas when the LAY functions version is chosen, IRI2001 produces profiles with erroneous features during evening and nighttime hours, although it produces profiles in a reasonable good agreement with the observational ones during daytime hours. (2) In general, profiles produced by IRI2001 with B0-Gulyaeva choice is in better agreement with observational profiles than when B0-Tab is chosen. When the B0-Gulyaeva and LAY functions version of Ne(h) are both chosen, IRI2001 produced the best results when compared with the observational results. (3) The B0 parameter given by B0-Gulyaeva choice in IRI2001 is much closer to the observed (best fitted) one than that given by the B0-Tab choice is. (author)

  9. Relativistic self-focusing of ultra-high intensity X-ray laser beams in warm quantum plasma with upward density profile

    International Nuclear Information System (INIS)

    Habibi, M.; Ghamari, F.

    2014-01-01

    The results of a numerical study of high-intensity X-ray laser beam interaction with warm quantum plasma (WQP) are presented. By means of an upward ramp density profile combined with quantum factors specially the Fermi velocity, we have demonstrated significant relativistic self-focusing (RSF) of a Gaussian electromagnetic beam in the WQP where the Fermi temperature term in the dielectric function is important. For this purpose, we have considered the quantum hydrodynamics model that modifies refractive index of inhomogeneous WQPs with the inclusion of quantum correction through the quantum statistical and diffraction effects in the relativistic regime. Also, to better illustration of the physical difference between warm and cold quantum plasmas and their effect on the RSF, we have derived the envelope equation governing the spot size of X-ray laser beam in Q-plasmas. In addition to the upward ramp density profile, we have found that the quantum effects would be caused much higher oscillation and better focusing of X-ray laser beam in the WQP compared to that of cold quantum case. Our computational results reveal the importance of the use of electrons density profile and Fermi speed in enhancing self-focusing of laser beam

  10. Evaluation of the methodologies used to generate random pavement profiles based on the power spectral density: An approach based on the International Roughness Index

    Directory of Open Access Journals (Sweden)

    Boris Jesús Goenaga

    2017-01-01

    Full Text Available The pavement roughness is the main variable that produces the vertical excitation in vehicles. Pavement profiles are the main determinant of (i discomfort perception on users and (ii dynamic loads generated at the tire-pavement interface, hence its evaluation constitutes an essential step on a Pavement Management System. The present document evaluates two specific techniques used to simulate pavement profiles; these are the shaping filter and the sinusoidal approach, both based on the Power Spectral Density. Pavement roughness was evaluated using the International Roughness Index (IRI, which represents the most used index to characterize longitudinal road profiles. Appropriate parameters were defined in the simulation process to obtain pavement profiles with specific ranges of IRI values using both simulation techniques. The results suggest that using a sinusoidal approach one can generate random profiles with IRI values that are representative of different road types, therefore, one could generate a profile for a paved or an unpaved road, representing all the proposed categories defined by ISO 8608 standard. On the other hand, to obtain similar results using the shaping filter approximation a modification in the simulation parameters is necessary. The new proposed values allow one to generate pavement profiles with high levels of roughness, covering a wider range of surface types. Finally, the results of the current investigation could be used to further improve our understanding on the effect of pavement roughness on tire pavement interaction. The evaluated methodologies could be used to generate random profiles with specific levels of roughness to assess its effect on dynamic loads generated at the tire-pavement interface and user’s perception of road condition.

  11. Helical variation of density profiles and fluctuations in the tokamak pedestal with applied 3D fields and implications for confinement

    Science.gov (United States)

    Wilcox, R. S.; Rhodes, T. L.; Shafer, M. W.; Sugiyama, L. E.; Ferraro, N. M.; Lyons, B. C.; McKee, G. R.; Paz-Soldan, C.; Wingen, A.; Zeng, L.

    2018-05-01

    Small 3D perturbations to the magnetic field in DIII-D ( δB /B ˜2 ×10-4 ) result in large modulations of density fluctuation amplitudes in the pedestal, which are shown using Doppler backscattering measurements to vary by a factor of 2. Helical perturbations of equilibrium density within flux surfaces have previously been observed in the pedestal of DIII-D plasmas when 3D fields are applied and were correlated with density fluctuation asymmetries in the pedestal. These intra-surface density and pressure variations are shown through two fluid MHD modeling studies using the M3D-C1 code to be due to the misalignment of the density and temperature equilibrium iso-surfaces in the pedestal region. This modeling demonstrates that the phase shift between the two iso-surfaces corresponds to the diamagnetic direction of the two species, with the mass density surfaces shifted in the ion diamagnetic direction relative to the temperature and magnetic flux iso-surfaces. The resulting pedestal density, potential, and turbulence asymmetries within flux surfaces near the separatrix may be at least partially responsible for several poorly understood phenomena that occur with the application of 3D fields in tokamaks, including density pump out and the increase in power required to transition from L- to H-mode.

  12. Experimental study of particle transport and density fluctuation in LHD

    International Nuclear Information System (INIS)

    Tanaka, K.; Morita, S.; Sanin, A.; Michael, C.; Kawahata, K.; Yamada, H.; Miyazawa, J.; Tokuzawa, T.; Akiyama, T.; Goto, M.; Ida, K.; Yoshinuma, M.; Narihara, K.; Yamada, I.; Yokoyama, M.; Masuzaki, S.; Morisaki, T.; Sakamoto, R.; Funaba, H.; Komori, A.; Vyacheslavov, L.N.; Murakami, S.; Wakasa, A.

    2005-01-01

    A variety of electron density (n e ) profiles have been observed in Large Helical Device (LHD). The density profiles change dramatically with heating power and toroidal magnetic field (B t ) under the same line averaged density. The particle transport coefficients, i.e., diffusion coefficient (D) and convection velocity (V) are experimentally obtained from density modulation experiments in the standard configuration. The values of D and V are estimated separately at the core and edge. The diffusion coefficients are strong function of electron temperature (T e ) and are proportional to T e 1.7±0.9 in core and T e 1.1±0.14 in edge. And edge diffusion coefficients are proportional to B t -2.08 . It is found that the scaling of D in edge is close to gyro-Bohm-like in nature. The existence of non-zero V is observed. It is observed that the electron temperature (T e ) gradient can drive particle convection. This is particularly clear in the core region. The convection velocity in the core region reverses direction from inward to outward as the T e gradient increases. In the edge, the convection is inward directed in the most of the case of the present data set. And it shows modest tendency, whose value is proportional to T e gradient keeping inward direction. However, the toroidal magnetic field also significantly affects value and direction of V. The spectrum of density fluctuation changes at different heating power suggesting that it has an influence on particle transport. The peak wavenumber is around 0.1 times the inversed ion Larmor radius, as is expected from gyro-Bohm diffusion. The peaks of fluctuation intensity are localized at the plasma edge, where density gradient becomes negative and diffusion contributes most to the particle flux. These results suggest a qualitative correlation of fluctuations with particle diffusion. (author)

  13. Bayesian electron density inference from JET lithium beam emission spectra using Gaussian processes

    Science.gov (United States)

    Kwak, Sehyun; Svensson, J.; Brix, M.; Ghim, Y.-C.; Contributors, JET

    2017-03-01

    A Bayesian model to infer edge electron density profiles is developed for the JET lithium beam emission spectroscopy (Li-BES) system, measuring Li I (2p-2s) line radiation using 26 channels with  ∼1 cm spatial resolution and 10∼ 20 ms temporal resolution. The density profile is modelled using a Gaussian process prior, and the uncertainty of the density profile is calculated by a Markov Chain Monte Carlo (MCMC) scheme. From the spectra measured by the transmission grating spectrometer, the Li I line intensities are extracted, and modelled as a function of the plasma density by a multi-state model which describes the relevant processes between neutral lithium beam atoms and plasma particles. The spectral model fully takes into account interference filter and instrument effects, that are separately estimated, again using Gaussian processes. The line intensities are inferred based on a spectral model consistent with the measured spectra within their uncertainties, which includes photon statistics and electronic noise. Our newly developed method to infer JET edge electron density profiles has the following advantages in comparison to the conventional method: (i) providing full posterior distributions of edge density profiles, including their associated uncertainties, (ii) the available radial range for density profiles is increased to the full observation range (∼26 cm), (iii) an assumption of monotonic electron density profile is not necessary, (iv) the absolute calibration factor of the diagnostic system is automatically estimated overcoming the limitation of the conventional technique and allowing us to infer the electron density profiles for all pulses without preprocessing the data or an additional boundary condition, and (v) since the full spectrum is modelled, the procedure of modulating the beam to measure the background signal is only necessary for the case of overlapping of the Li I line with impurity lines.

  14. Near-surface density profiling of Fe ion irradiated Si (100) using extremely asymmetric x-ray diffraction by variation of the wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany); Doyle, S. [Synchrotron Light Source ANKA, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2014-10-20

    In this work, we report on correlations between surface density variations and ion parameters during ion beam-induced surface patterning process. The near-surface density variations of irradiated Si(100) surfaces were investigated after off-normal irradiation with 5 keV Fe ions at different fluences. In order to reduce the x-ray probing depth to a thickness below 5 nm, the extremely asymmetrical x-ray diffraction by variation of wavelength was applied, exploiting x-ray refraction at the air-sample interface. Depth profiling was achieved by measuring x-ray rocking curves as function of varying wavelengths providing incidence angles down to 0°. The density variation was extracted from the deviations from kinematical Bragg angle at grazing incidence angles due to refraction of the x-ray beam at the air-sample interface. The simulations based on the dynamical theory of x-ray diffraction revealed that while a net near-surface density decreases with increasing ion fluence which is accompanied by surface patterning, there is a certain threshold of ion fluence to surface density modulation. Our finding suggests that the surface density variation can be relevant with the mechanism of pattern formation.

  15. The role of concavo-convex walls of a nanopore on the density profile, adsorption, solvation force, and capillary condensation of confined fluids: A DFT study

    International Nuclear Information System (INIS)

    Helmi, Abbas; Keshavarzi, Ezat

    2014-01-01

    Highlights: • The effect of concavo-convex walls of nanopores on the density profile was studied. • For HS fluids the contact density at concave wall is greater than for convex wall. • For Yukawa fluid the contact density at concave wall can be less than convex wall. • Capillary condensation was observed for Yukawa fluids in the homocentric pores. - Abstract: We investigate the effects of concavo-convex walls of a nanopore on the structure and certain thermodynamic properties of confined fluids. Adsorption, solvation force, and capillary condensation in a nanopore formed between two homocentric spheres will be determined using the MFMT. For hard sphere fluids, contact density is greater at the concave wall than it is at the convex wall. In Yukawa fluids, for the thermodynamic state in which the energy effect is the dominant factor, contact density at a concave wall is less than that at a convex wall; this will be reversed for the thermodynamic state in which the entropy effect is the dominant factor. It is possible to find thermodynamic states in which contact densities at concave and convex walls become identical. The adsorption and solvation force of hard sphere fluid show an oscillatory behavior versus H. Capillary condensation is in certain cases observed for Yukawa fluids

  16. Localized Edge Vibrations and Edge Reconstruction by Joule Heating in Graphene Nanostructures

    DEFF Research Database (Denmark)

    Engelund, Mads; Fürst, Joachim Alexander; Jauho, Antti-Pekka

    2010-01-01

    Control of the edge topology of graphene nanostructures is critical to graphene-based electronics. A means of producing atomically smooth zigzag edges using electronic current has recently been demonstrated in experiments [Jia et al., Science 323, 1701 (2009)]. We develop a microscopic theory...... for current-induced edge reconstruction using density functional theory. Our calculations provide evidence for localized vibrations at edge interfaces involving unpassivated armchair edges. We demonstrate that these vibrations couple to the current, estimate their excitation by Joule heating, and argue...

  17. Measuring the stellar luminosity function and spatial density profile of the inner 0.5 pc of the Milky Way nuclear star cluster

    Science.gov (United States)

    Do, Tuan; Ghez, Andrea; Lu, Jessica R.; Morris, Mark R.; Yelda, Sylvana; Martinez, Gregory D.; Peter, Annika H. G.; Wright, Shelley; Bullock, James; Kaplinghat, Manoj; Matthews, K.

    2012-07-01

    We report on measurements of the luminosity function of early (young) and late-type (old) stars in the central 0.5 pc of the Milky Way nuclear star cluster as well as the density profiles of both components. The young (~ 6 Myr) and old stars (> 1 Gyr) in this region provide different physical probes of the environment around a supermassive black hole; the luminosity function of the young stars offers us a way to measure the initial mass function from star formation in an extreme environment, while the density profile of the old stars offers us a probe of the dynamical interaction of a star cluster with a massive black hole. The two stellar populations are separated through a near-infrared spectroscopic survey using the integral-field spectrograph OSIRIS on Keck II behind the laser guide star adaptive optics system. This spectroscopic survey is able to separate early-type (young) and late-type (old) stars with a completeness of 50% at K' = 15.5. We describe our method of completeness correction using a combination of star planting simulations and Bayesian inference. The completeness corrected luminosity function of the early-type stars contains significantly more young stars at faint magnitudes compared to previous surveys with similar depth. In addition, by using proper motion and radial velocity measurements along with anisotropic spherical Jeans modeling of the cluster, it is possible to measure the spatial density profile of the old stars, which has been difficult to constrain with number counts alone. The most probable model shows that the spatial density profile, n(r) propto r-γ, to be shallow with γ = 0.4 ± 0.2, which is much flatter than the dynamically relaxed case of γ = 3/2 to 7/4, but does rule out a 'hole' in the distribution of old stars. We show, for the first time, that the spatial density profile, the black hole mass, and velocity anisotropy can be fit simultaneously to obtain a black hole mass that is consistent with that derived from

  18. High density operation on the HT-7 superconducting tokamak

    International Nuclear Information System (INIS)

    Xiang Gao

    2000-01-01

    The structure of the operation region has been studied in the HT-7 superconducting tokamak, and progress on the extension of the HT-7 ohmic discharge operation region is reported. A density corresponding to 1.2 times the Greenwald limit was achieved by RF boronization. The density limit appears to be connected to the impurity content and the edge parameters, so the best results are obtained with very clean plasmas and peaked electron density profiles. The peaking factors of electron density profiles for different current and line averaged densities were observed. The density behaviour and the fuelling efficiency for gas puffing (20-30%), pellet injection (70-80%) and molecular beam injection (40-50%) were studied. The core crash sawteeth and MHD behaviour, which were induced by an injected pellet, were observed and the events correlated with the change of current profile and reversed magnetic shear. The MARFE phenomena on HT-7 are summarized. The best correlation has been found between the total input ohmic power and the product of the edge line averaged density and Z eff . HT-7 could be easily operated in the high density region MARFE-free using RF boronization. (author)

  19. Edge passivation induced single-edge ferromagnetism of zigzag MoS_2 nanoribbons

    International Nuclear Information System (INIS)

    Wang, Rui; Sun, Hui; Ma, Ben; Hu, Jingguo; Pan, Jing

    2017-01-01

    We performed density functional theory study on electronic structure, magnetic properties and stability of zigzag MoS_2 nanoribbons (ZMoS_2NRs) with and without oxygen (O) passivation. The bare ZMoS_2NRs are magnetic metal with ferromagnetic edge states, edge passivation decreases their magnetism because of the decrease of edge unsaturated electrons. Obviously, the electronic structure and magnetic properties of ZMoS_2NRs greatly depend on edge states. When both edges are passivated by O atoms, ZMoS_2NRs are nonmagnetic metals. When either edge is passivated by O atoms, the systems exhibit single-edge ferromagnetism and magnetism concentrates on the non-passivated edge. Edge passivation can not only tune the magnetism of ZMoS_2NRs, but also enhance their stability by eliminating dangling bonds. These interesting findings on ZMoS_2NRs may open the possibility of their application in nanodevices and spintronics. - Highlights: • Edge passivation for tuning magnetism of zigzag MoS_2 nanoribbons (ZMoS_2NRs) is proposed. • Edge passivation can tune ZMoS_2NRs from nonmagnetic metal to ferromagnetic metal. • When either edge is passivated, the systems exhibit single-edge ferromagnetic states. • These findings may inspire great interest in the community of ZMoS_2NRs and motivate numerous experimental researches.

  20. THE BOSS EMISSION-LINE LENS SURVEY. II. INVESTIGATING MASS-DENSITY PROFILE EVOLUTION IN THE SLACS+BELLS STRONG GRAVITATIONAL LENS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, Adam S.; Brownstein, Joel R.; Shu Yiping; Arneson, Ryan A. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States); Kochanek, Christopher S. [Department of Astronomy and Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Schlegel, David J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Eisenstein, Daniel J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States); Wake, David A. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Connolly, Natalia [Department of Physics, Hamilton College, Clinton, NY 13323 (United States); Maraston, Claudia [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Weaver, Benjamin A., E-mail: bolton@astro.utah.edu [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)

    2012-09-20

    We present an analysis of the evolution of the central mass-density profile of massive elliptical galaxies from the SLACS and BELLS strong gravitational lens samples over the redshift interval z Almost-Equal-To 0.1-0.6, based on the combination of strong-lensing aperture mass and stellar velocity-dispersion constraints. We find a significant trend toward steeper mass profiles (parameterized by the power-law density model with {rho}{proportional_to}r {sup -{gamma}}) at later cosmic times, with magnitude d < {gamma} > /dz = -0.60 {+-} 0.15. We show that the combined lens-galaxy sample is consistent with a non-evolving distribution of stellar velocity dispersions. Considering possible additional dependence of <{gamma} > on lens-galaxy stellar mass, effective radius, and Sersic index, we find marginal evidence for shallower mass profiles at higher masses and larger sizes, but with a significance that is subdominant to the redshift dependence. Using the results of published Monte Carlo simulations of spectroscopic lens surveys, we verify that our mass-profile evolution result cannot be explained by lensing selection biases as a function of redshift. Interpreted as a true evolutionary signal, our result suggests that major dry mergers involving off-axis trajectories play a significant role in the evolution of the average mass-density structure of massive early-type galaxies over the past 6 Gyr. We also consider an alternative non-evolutionary hypothesis based on variations in the strong-lensing measurement aperture with redshift, which would imply the detection of an 'inflection zone' marking the transition between the baryon-dominated and dark-matter halo-dominated regions of the lens galaxies. Further observations of the combined SLACS+BELLS sample can constrain this picture more precisely, and enable a more detailed investigation of the multivariate dependences of galaxy mass structure across cosmic time.

  1. Topology and transport in the edge region of RFX-mod helical regimes

    International Nuclear Information System (INIS)

    Scarin, P.; Vianello, N.; Agostini, M.; Spizzo, G.; Spolaore, M.; Zuin, M.; Cappello, S.; Carraro, L.; Cavazzana, R.; De Masi, G.; Martines, E.; Moresco, M.; Munaretto, S.; Puiatti, M. E.; Valisa, M.

    2011-01-01

    New edge diagnostics and detailed analysis of magnetic topology have significantly improved the comprehension of the processes developing at the boundary of a reversed-field pinch (RFP) plasma in RFX-mod (a = 0.46 m, R = 2 m). An upper critical density n C ∼ 0.4 n G (n G Greenwald density) is found to limit the operational space for the improved quasi-single helical (QSH) regime: magnetic topology reconstructions and diagnostic observations suggest that this limit is due to a helical plasma-wall interaction which determines toroidally and poloidally localized edge density accumulation and cooling. The experimental evidence is provided by a variety of diagnostics: the magnetic boundary as reconstructed from equilibrium codes reveals a helical deformation, which is well correlated with the modulation of edge pressure profile as reconstructed from the thermal helium beam diagnostic. Correlations with the helical deformation are also observed on the space- and time-resolved patterns of the floating potential measured at the wall, and with the edge plasma flow, obtained from different diagnostics. The relevance of these findings is that understanding the mechanisms that limit the operational space of QSH is decisive in achieving the goal of high-density stationary helical RFP equilibrium.

  2. Gyrosheath near the tokamak edge

    International Nuclear Information System (INIS)

    Hazeltine, R.D.; Xiao, H.; Valanju, P.M.

    1993-03-01

    A new model for the structure of the radial electric field profile in the edge during the H-mode is proposed. Charge separation caused by the difference between electron and ion gyromotion, or more importantly in a tokamak, the banana motion (halo effect) can self-consistently produce an electric dipole moment that causes the sheared radial electric field. The calculated results based on the model are consistent with D-III D and TEXTOR experimental results

  3. Magnetohydrodynamic stability of tokamak edge plasmas

    International Nuclear Information System (INIS)

    Connor, J.W.; Hastie, R.J.; Wilson, H.R.; Miller, R.L.

    1998-01-01

    A new formalism for analyzing the magnetohydrodynamic stability of a limiter tokamak edge plasma is developed. Two radially localized, high toroidal mode number n instabilities are studied in detail: a peeling mode and an edge ballooning mode. The peeling mode, driven by edge current density and stabilized by edge pressure gradient, has features which are consistent with several properties of tokamak behavior in the high confinement open-quotes Hclose quotes-mode of operation, and edge localized modes (or ELMs) in particular. The edge ballooning mode, driven by the pressure gradient, is identified; this penetrates ∼n 1/3 rational surfaces into the plasma (rather than ∼n 1/2 , expected from conventional ballooning mode theory). Furthermore, there exists a coupling between these two modes and this coupling provides a picture of the ELM cycle

  4. The Effect of Air Density on Sand Transport Structures and the Adobe Abrasion Profile: A Field Wind-Tunnel Experiment Over a Wide Range of Altitude

    Science.gov (United States)

    Han, Qingjie; Qu, Jianjun; Dong, Zhibao; Zu, Ruiping; Zhang, Kecun; Wang, Hongtao; Xie, Shengbo

    2014-02-01

    Aeolian sand transport results from interactions between the surface and the airflow above. Air density strongly constrains airflow characteristics and the resulting flow of sand, and therefore should not be neglected in sand transport models. In the present study, we quantify the influence of air density on the sand flow structure, sand transport rate, adobe abrasion profiles, and abrasion rate using a portable wind-tunnel in the field. For a given wind speed, the flow's ability to transport sand decreases at low air density, so total sand transport decreases, but the saltation height increases. Thus, the damage to human structures increases compared with what occurs at lower altitudes. The adobe abrasion rate by the cloud of blowing sand decreases exponentially with increasing height above the surface, while the wind erosion and dust emission intensity both increase with increasing air density. Long-term feedback processes between air density and wind erosion suggest that the development of low-altitude areas due to long-term deflation plays a key role in dust emission, and will have a profound significance for surface Aeolian processes and geomorphology.

  5. Healthy Snacks: Using Nutrient Profiling to Evaluate the Nutrient-Density of Common Snacks in the United States.

    Science.gov (United States)

    Hess, Julie M; Slavin, Joanne L

    2017-09-01

    To quantify and compare the nutrient-density of commonly consumed snacks using two nutrient-density measures, Nutrient Rich Foods Indices 9.3 (NRF 9.3) and 15.3 (NRF 15.3). Identify commonly consumed categories of snacks and individual snack foods, calculate NRF 9.3 and 15.3 scores, rank snacks by category and by individual food based on nutrient density, compare and contrast scores generated by the two NRF Indices. NRF 9.3 and 15.3 scores. Averages and standard deviations of nutrient-density scores for each snack category. Vegetables and coffee/tea received the highest category scores on both indices. Cakes/cookies/pastries and sweets had the lowest category scores. NRF 9.3 scores for individual snacks ranged from -46 (soda) to 524 (coffee). NRF 15.3 scores ranged from -45 (soda) to 736 (coffee). If added to food labels, NRF scores could help consumers identify more nutritious choices. The differences between NRF 9.3 and 15.3 scores generated for the same foods and the limitations of these indices highlight the need for careful consideration of which nutrient-density measure to include on food labels as well as consumer education. © 2017 Institute of Food Technologists®.

  6. Imaging the density profile of a volcano interior with cosmic-ray muon radiography combined with classical gravimetry

    International Nuclear Information System (INIS)

    Okubo, S; Tanaka, H K M

    2012-01-01

    Cosmic-ray muon radiography has the potential to reveal the density structure of gigantic objects. It utilizes the strong penetration ability of high-energy muons. By measuring the number of muons that travel through a target object, the average density can be calculated along the muon path. Since muons travel in straight paths through matter, specially designed detectors can generate density maps with higher spatial resolution than those obtained with conventional geophysical methods. However, this technique has a few notable limitations in that it can only be applied to near-surface structures above the muon sensor and strongly depends on the characteristics of the local topography. This is due to the fact that almost all cosmic-ray muons arrive only from the upper hemisphere. Geological structures, e.g. volcanoes, that allow for muon detectors to be placed on a slope directly below the point of interest are thus the best candidates for this technique. The drawback of muon radiography that only the horizontally integrated density above the sensor is measured with a time resolution larger than several weeks may be partly remedied by combining its results with gravity data, as they are both sensitive to target density while complementary to each other in several aspects. An example of such a combination is presented: real-time monitoring of magma head height in a volcano conduit. (topical review)

  7. CLASH-VLT: The stellar mass function and stellar mass density profile of the z=0.44 cluster of galaxies MACS J1206.2-0847

    CERN Document Server

    Annunziatella, M; Mercurio, A.; Nonino, M.; Rosati, P.; Balestra, I.; Presotto, V.; Girardi, M.; Gobat, R.; Grillo, C.; Medezinski, E.; Kelson, D.; Postman, M.; Scodeggio, M.; Brescia, M.; Sartoris, B.; Demarco, R.; Fritz, A.; Koekemoer, A.; Lemze, D.; Lombardi, M.; Bradley, L.; Coe, D.; Donahue, M.; Regös, E.; Umetsu, K.; Vanzella, E.; Infante, L.; Kuchner, U.; Maier, C.; Verdugo, M.; Ziegler, B.

    2014-01-01

    Context. The study of the galaxy stellar mass function (SMF) in relation to the galaxy environment and the stellar mass density profile, rho(r), is a powerful tool to constrain models of galaxy evolution. Aims. We determine the SMF of the z=0.44 cluster of galaxies MACS J1206.2-0847 separately for passive and star-forming (SF) galaxies, in different regions of the cluster, from the center out to approximately 2 virial radii. We also determine rho(r) to compare it to the number density and total mass density profiles. Methods. We use the dataset from the CLASH-VLT survey. Stellar masses are obtained by SED fitting on 5-band photometric data obtained at the Subaru telescope. We identify 1363 cluster members down to a stellar mass of 10^9.5 Msolar. Results. The whole cluster SMF is well fitted by a double Schechter function. The SMFs of cluster SF and passive galaxies are statistically different. The SMF of the SF cluster galaxies does not depend on the environment. The SMF of the passive population has a signif...

  8. 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.

  9. 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.

  10. Storage affects the phenolic profiles and antioxidant activities of cherries (Prunus avium L) on human low-density lipoproteins

    DEFF Research Database (Denmark)

    Goncalves, B.; Landbo, Anne-Katrine Regel; Let, Mette Bruni

    2004-01-01

    Four sweet cherry cultivars (cvs), Burlat, Saco, Summit and Van, were analysed at harvest and after storage at 2 and 15degreesC for 30 and 6 days respectively. Phenolic profiles in methanolic extracts of freeze-dried samples of the fresh and differently stored cherries were quantified by high...

  11. Internal barrier discharges in JET and their sensitivity to edge conditions

    International Nuclear Information System (INIS)

    Sips, A.C.C.

    2001-01-01

    Experiments in JET have concentrated on steady state discharges with internal transport barriers. The internal transport barriers are formed during the current rise phase of the discharge with low magnetic shear in the centre and with high additional heating power. In order to achieve stability against disruptions at high pressure peaking, typical for ITB discharges, the pressure profile can be broadened with a H-mode transport barrier at the edge of the plasma. However, the strong increase in edge pressure during an ELM free H-mode weakens the internal transport barrier due to a reduction of the rotational shear and pressure gradient at the ITB location. In addition, type I ELM activity, associated with a high edge pedestal pressure, leads to a collapse of the ITB with the input powers available in JET. The best ITB discharges are obtained with input power control to reduce to core pressure, and with the edge of the plasma controlled by argon gas dosing. These discharges achieve steady conditions for several energy confinement times with H97 confinement enhancement factors of 1.2-1.6 at line average densities around 30%-40% of the Greenwald density. This is at much lower density (typically factor 2 to 3) compared to standard H-mode discharges in JET. Increasing the density, using additional deuterium gas dosing or shallow pellet fueling has not been successful so far. A possible route to higher densities should maintain the type III ELM's towards high edge density, giving scope for future experiments in JET. (author)

  12. Predicted solar cell edge radiation effects

    International Nuclear Information System (INIS)

    Gates, M.T.

    1993-01-01

    The Advanced Solar Cell Orbital Test (ASCOT) will test six types of solar cells in a high energy proton environment. During the design of the experiment a question was raised about the effects of proton radiation incident on the edge of the solar cells and whether edge radiation shielding was required. Historical geosynchronous data indicated that edge radiation damage is not detectable over the normal end of life solar cell degradation; however because the ASCOT radiation environment has a much higher and more energetic fluence of protons, considerably more edge damage is expected. A computer analysis of the problem was made by modeling the expected radiation damage at the cell edge and using a network model of small interconnected solar cells to predict degradation in the cell's electrical output. The model indicated that the deepest penetration of edge radiation was at the top of the cell near the junction where the protons have access to the cell through the low density cell/cover adhesive layer. The network model indicated that the cells could tolerate high fluences at their edge as long as there was high electrical resistance between the edge radiated region and the contact system on top of the cell. The predicted edge radiation related loss was less than 2% of maximum power for GaAs/Ge solar cells. As a result, no edge radiation protection was used for ASCOT

  13. Edge-functionalization of armchair graphene nanoribbons with pentagonal-hexagonal edge structures.

    Science.gov (United States)

    Ryou, Junga; Park, Jinwoo; Kim, Gunn; Hong, Suklyun

    2017-06-21

    Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled (5,6)-AGNRs) are metallic, the edge-functionalized (5,6)-AGNRs with substitutional atoms opens a band gap. We find that the band structures of edge-functionalized (5,6)-N-AGNRs by substitution resemble those of defect-free (N-1)-AGNR at the Γ point, whereas those at the X point show the original ones of the defect-free N-AGNR. The overall electronic structures of edge-functionalized (5,6)-AGNRs depend on the number of electrons, supplied by substitutional atoms, at the edges of functionalized (5,6)-AGNRs.

  14. Effects of fueling profiles on plasma transport

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Mense, A.T.; Attenberger, S.E.; Milora, S.L.

    1977-01-01

    The effects of cold particle fueling profiles on particle and energy transport in an ignition sized tokamak plasma are investigated in this study with a one-dimensional, multifluid transport model. A density gradient driven trapped particle microinstability model for plasma transport is used to demonstrate potential effects of fueling profiles on ignition requirements. Important criteria for the development of improved transport models under the conditions of shallow particle fueling profiles are outlined. A discrete pellet fueling model indicates that large fluctuations in density and temperature may occur in the outer regions of the plasma with large, shallowly penetrating pellets, but fluctuations in the pressure profile are small. The hot central core of the plasma remains unaffected by the large fluctuations near the plasma edge

  15. Edge stability and performance of the ELM-free quiescent H-mode and the quiescent double barrier mode on DIII-D

    International Nuclear Information System (INIS)

    West, W.P.; Burrell, K.H.; Snyder, P.B.; Gohil, P.; Lao, L.L.; Leonard, A.W.; Osborne, T.H.; Thomas, D.M.; Casper, T.A.; Lasnier, C.J.; Doyle, E.J.; Wang, G.; Zeng, L.; Nave, M.F.F.

    2005-01-01

    The quiescent H (QH) mode, an edge localized mode (ELM)-free, high-confinement mode, combines well with an internal transport barrier to form quiescent double barrier (QDB) stationary state, high performance plasmas. The QH-mode edge pedestal pressure is similar to that seen in ELMing phases of the same discharge, with similar global energy confinement. The pedestal density in early ELMing phases of strongly pumped counter injection discharges drops and a transition to QH-mode occurs, leading to lower calculated edge bootstrap current. Plasmas current ramp experiment and ELITE code modeling of edge stability suggest that QHmodes lie near an edge current stabilty boundary. At high triangularity, QH-mode discharges operate at higher pedestal density and pressure, and have achieved ITER level values of β PED and ν*. The QDB achieves performance of β N H 89 ∼ 7 in quasi-stationary conditions for a duration of 10 τ E , limited by hardware. Recently we demonstrated stationary state QDB discharges with little change in kinetic and q profiles (q 0 > 1) for 2 s, comparable to ELMing 'hybrid scenarios', yet without the debilitating effects of ELMs. Plasma profile control tools, including electron cyclotron heating and current drive and neutral beam heating, have been demonstrated to control simultaneously the q profile development, the density peaking, impurity accumulation and plasma beta. (author)

  16. Global simulation of edge pedestal micro-instabilities

    Science.gov (United States)

    Wan, Weigang; Parker, Scott; Chen, Yang

    2011-10-01

    We study micro turbulence of the tokamak edge pedestal with global gyrokinetic particle simulations. The simulation code GEM is an electromagnetic δf code. Two sets of DIII-D experimental profiles, shot #131997 and shot #136051 are used. The dominant instabilities appear to be two kinds of modes both propagating in the electron diamagnetic direction, with comparable linear growth rates. The low n mode is at the Alfven frequency range and driven by density and ion temperature gradients. The high n mode is driven by electron temperature gradient and has a low real frequency. A β scan shows that the low n mode is electromagnetic. Frequency analysis shows that the high n mode is sometimes mixed with an ion instability. Experimental radial electric field is applied and its effects studied. We will also show some preliminary nonlinear results. We thank R. Groebner, P. Snyder and Y. Zheng for providing experimental profiles and helpful discussions.

  17. The use of edge habitats by commuting and foraging bats

    NARCIS (Netherlands)

    Verboom, B.

    1998-01-01

    Travelling routes and foraging areas of many bat species are mainly along edge habitats, such as treelines, hedgerows, forest edges, and canal banks. This thesis deals with the effects of density, configuration, and structural features of edge habitats on the occurrence of bats. Four

  18. Interspecies Interactions in Relation to Root Distribution Across the Rooting Profile in Wheat-Maize Intercropping Under Different Plant Densities

    Directory of Open Access Journals (Sweden)

    Yifan Wang

    2018-04-01

    Full Text Available In wheat-maize intercropping systems, the maize is often disadvantageous over the wheat during the co-growth period. It is unknown whether the impaired growth of maize can be recovered through the enhancement of the belowground interspecies interactions. In this study, we (i determined the mechanism of the belowground interaction in relation to root growth and distribution under different maize plant densities, and (ii quantified the “recovery effect” of maize after wheat harvest. The three-year (2014–2016 field experiment was conducted at the Oasis Agriculture Research Station of Gansu Agricultural University, Wuwei, Northwest China. Root weight density (RWD, root length density (RLD, and root surface area density (RSAD, were measured in single-cropped maize (M, single-cropped wheat (W, and three intercropping systems (i wheat-maize intercropping with no root barrier (i.e., complete belowground interaction, IC, (ii nylon mesh root barrier (partial belowground interaction, IC-PRI, and (iii plastic sheet root barrier (no belowground interaction, IC-NRI. The intercropped maize was planted at low (45,000 plants ha−1 and high (52,000 plants ha−1 densities. During the wheat/maize co-growth period, the IC treatment increased the RWD, RLD, and RSAD of the intercropped wheat in the 20–100 cm soil depth compared to the IC-PRI and IC-NRI systems; intercropped maize had 53% lower RWD, 81% lower RLD, and 70% lower RSAD than single-cropped maize. After wheat harvest, the intercropped maize recovered the growth with the increase of RWD by 40%, RLD by 44% and RSAD by 11%, compared to the single-cropped maize. Comparisons among the three intercropping systems revealed that the “recovery effect” of the intercropped maize was attributable to complete belowground interspecies interaction by 143%, the compensational effect due to root overlap by 35%, and the compensational effect due to water and nutrient exchange (CWN by 80%. The higher maize plant

  19. Changes in the High-Latitude Topside Ionospheric Vertical Electron-Density Profiles in Response to Solar-Wind Perturbations During Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir; Truhlik, Vladimir; Wang, Yongli; Arbacher, Becca

    2011-01-01

    The latest results from an investigation to establish links between solar-wind and topside-ionospheric parameters will be presented including a case where high-latitude topside electron-density Ne(h) profiles indicated dramatic rapid changes in the scale height during the main phase of a large magnetic storm (Dst wind data obtained from the NASA OMNIWeb database indicated that the magnetic storm was due to a magnetic cloud. This event is one of several large magnetic storms being investigated during the interval from 1965 to 1984 when both solar-wind and digital topside ionograms, from either Alouette-2, ISIS-1, or ISIS-2, are potentially available.

  20. Characterisation of the ELM synchronized H-mode edge pedestal in ASDEX upgrade and DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Philip A.; Wolfrum, Elisabeth; Guenter, Sibylle; Kurzan, Bernd; Zohm, Hartmut [Max Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Groebner, Rich; Osborne, Tom H.; Ferron, John; Snyder, Philip B. [General Atomics, San Diego, CA (United States); Dunne, Mike G. [Department of Physics, University College Cork, Association Euratom-DCU, Cork (Ireland); Collaboration: ASDEX Upgrade Team; DIII-D Team

    2011-07-01

    The results of a large database of edge pedestal data from type-I ELMy H-mode discharges from ASDEX Upgrade and DIII-D are presented. The data from high resolution edge diagnostics of both devices is analysed with the same analysis code in order to avoid systematic differences. Furthermore, sophisticated equilibrium reconstructions are used to asses uncertainties which arise during mapping from 2D real space coordinates to 1D flux coordinates. ELM synchronization allows the study of the pedestal structure at the ELM stability boundary. The pedestal is characterized by its top value, the gradient and the width. A large parameter range is covered by the two devices. Over this parameter range the profile shape of edge electron density differs from that of the temperature, irrespective of the device. However, the resulting electron pressure profile shape remains similar for all analysed H-Mode discharges.

  1. Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

    OpenAIRE

    Akemann, G; Bittner, E; Lombardo, M; Markum, H; Pullirsch, R

    2004-01-01

    We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis.

  2. Density profiles of small Dirac operator eigenvalues for two color QCD at nonzero chemical potential compared to matrix models

    International Nuclear Information System (INIS)

    Akemann, Gernot; Bittner, Elmar; Lombardo, Maria-Paola; Markum, Harald; Pullirsch, Rainer

    2005-01-01

    We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian Symplectic Ensemble, confirming its predictions for weak and strong non-Hermiticity. They differ from the QCD symmetry class with three colors by a level repulsion from both the real and imaginary axis

  3. The effect of edge and impurities sites properties on their localized states in semi-infinite zigzag edged 2D honeycomb graphene sheet

    OpenAIRE

    Ahmed, Maher

    2011-01-01

    In this work, the tridiagonal method is used to distinguish between edges modes and area modes to study the edge sites properties effect on edge localized states of semi-infinite zigzag 2D honeycomb graphene sheet. The results show a realistic behavior for the dependance of edge localized states of zigzag graphene on the edge sites properties which explaining the experimental results of measured local density of states at the edge of graphene, while at the same time removing the inconsistence...

  4. Assessment risk of osteoporosis in Chinese people: relationship among body mass index, serum lipid profiles, blood glucose, and bone mineral density

    Directory of Open Access Journals (Sweden)

    Cui RT

    2016-07-01

    Full Text Available Rongtao Cui,1 Lin Zhou,2 Zuohong Li,2 Qing Li,2 Zhiming Qi,2 Junyong Zhang3 1Department of Orthopedic and Trauma Surgery, Surgical Research, Duisburg-Essen University Hospital, Essen, Germany; 2Department of Orthopedics, Dalian Central Hospital, Dalian, 3Department of Gastroenterology, Shandong Provincial Hospital, Jinan, People’s Republic of China Objective: The aim of our study was to investigate the relationship among age, sex, body mass index (BMI, serum lipid profiles, blood glucose (BG, and bone mineral density (BMD, making an assessment of the risk of osteoporosis.Materials and methods: A total of 1,035 male and 3,953 female healthy volunteers (aged 41–95 years were recruited by an open invitation. The basic information, including age, sex, height, weight, waistline, hipline, menstrual cycle, and medical history, were collected by a questionnaire survey and physical examination. Serum lipid profiles, BG, postprandial blood glucose, and glycosylated hemoglobin were obtained after 12 hours fasting. BMD in lumbar spine was measured by dual-energy X-ray absorptiometry scanning.Results: The age-adjusted BMD in females was significantly lower than in males. With aging, greater differences of BMD distribution exist in elderly females than in males (P<0.001, and the fastigium of bone mass loss was in the age range from 51 to 55 in females and from 61 to 65 years in males. After adjustment for sex, there were significant differences in BMD among BMI-stratified groups in both males and females. The subjects with a BMI of <18.5 had a higher incidence of osteoporosis than BMI ≥18.5 in both sexes. BMD in type 2 diabetes mellitus with a BG of >7.0 mmol/L was lower than in people with BG of ≤7.0 mmol/L (P<0.001. People with serum high-density lipoprotein cholesterol levels of ≥1.56 mmol/L had a greater prevalence of osteoporosis compared with high-density lipoprotein cholesterol ≤1.55 mmol/L. Logistic regression with odds ratios showed that

  5. Determination of line edge roughness in low dose top-down scanning electron microscopy images

    Science.gov (United States)

    Verduin, T.; Kruit, P.; Hagen, C. W.

    2014-04-01

    We investigated off-line metrology for LER determination in low-dose SEM images to reduce the acquisition time and the risk of shrinkage. Our first attempts are based on filtering noisy (experimental) SEM images and use peak detection to measure the edge displacements and calculating the discrete PSD. However, the result of the filtering is that the power spectrum of the filter leaks into the PSD. So it is better to avoid a filter at all. We subsequently developed a method to detect edge displacements without the use of a filter. This method considers the signal profile of a SEM by integrating an experimental image of lines in the direction of the edges. The signal profile of an isolated edge is modeled as two merged Gaussians. This signal profile is then fitted against the raw (unfiltered) data of the edge pattern using an interior trust-region-reflective minimization procedure. This gives the edge displacements without the use of a filter and a filter-free version of the discrete PSD is obtained. The determination of edge displacements without the use of a filter, enables us to study how much noise is acceptable and still determine LER. To answer this question we generate random lines using the model of Palasantzas and the algorithm of Thorsos. This gives random generated edge displacements for typical values of experimental lines for the parameters of the model: 2 μm long lines (256 pixels), a correlation length ξ of 25 nm and a roughness exponent of 0.75. A noise-free top-down SEM-like image of lines is created by shifting the profile signal according to the random generated edge displacements. The image is further processed by adding Poisson-distributed noise. We consider three noise cases where the average electron density is about 2, 20 and 200 electrons per pixel. This corresponds to a charge density of (in respective order) 10 μC/cm2, 100 μC/cm2 and 1000 μC/cm2. The edge displacements of the random generated images are determined using our new

  6. Measurements and modeling of transport and impurity radial profiles in the EXTRAP T2R reversed field pinch

    Science.gov (United States)

    Kuldkepp, M.; Brunsell, P. R.; Cecconello, M.; Dux, R.; Menmuir, S.; Rachlew, E.

    2006-09-01

    Radial impurity profiles of oxygen in the rebuilt reversed field pinch EXTRAP T2R [P. R. Brunsell et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] have been measured with a multichannel spectrometer. Absolute ion densities for oxygen peak between 1-4×1010cm-3 for a central electron density of 1×1013cm-3. Transport simulations with the one-dimensional transport code STRAHL with a diffusion coefficient of 20m2 s-1 yield density