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1

Low-Frequency Microinstabilities in Rotating Tokamak Plasmas  

Microsoft Academic Search

Low-frequency drift-type microinstabilities have often been suggested as the leading candidates to account for the anomalously large transport; observed in tokamak plasmas. The effects of sheared equilibrium flows on this important class of instabilities is systematically investigated in the present thesis. In particular, the analysis is carried out in two parts. In order to gain some insight into the key

Mehmet Artun

1994-01-01

2

Effects of Sheared Flow on Microinstabilities and Transport in Plasmas  

NASA Astrophysics Data System (ADS)

Theoretical and experimental studies associated with electric field effects on the stability and transport are briefly surveyed. The effects of radial electric field on the suppression and/or enhancement of various microinstabilities such as drift waves, flute mode and temperature gradient modes are discussed. The suppression of flow shear on the electron temperature gradient mode in plasmas with slightly hollow density profiles is investigated by solving the gyrokinetic integral eigenvalue equation. Comparison between theoretical predictions and experimental observations based on the HIBP measurements with high temporal and spatial resolutions is made in bumpy tori and heliotron (CHS) devices.

H, Sanuki; K, Itoh; A, Fujisawa; J, Q. Dong

2005-02-01

3

Microinstability of a Mirror-Confined Plasma  

Microsoft Academic Search

Infinite uniform magnetized plasmas with non-Maxwellian particle distributions are subject to electrostatic longitudinal instabilities of the type discussed by Harris. Mirror confinement leads to depletion of low energy ion populations and thus to the Rosenbluth-Post ``maser'' instability at frequencies ? » ?ci, the ion gyrofrequency, and to the flute-like instability of Dory, Guest, and Harris with ? ? ?ci and

G. E. Guest; R. A. Dory

1965-01-01

4

Structure of micro-instabilities in tokamak plasmas: Stiff transport or plasma eruptions?  

SciTech Connect

Solutions to a model 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the tokamak. This corresponds to the conventional picture of a ballooning mode. However, for most profiles, this mode cannot exist, and instead, a more stable mode is found that balloons closer to the top or bottom of the plasma. Good quantitative agreement with a 1D ballooning analysis is found, provided the constraints associated with higher order profile effects, often neglected, are taken into account. A sudden transition from this general mode to the more unstable ballooning mode can occur for a critical flow shear, providing a candidate model for why some experiments observe small plasma eruptions (Edge Localised Modes, or ELMs) in place of large Type I ELMs.

Dickinson, D., E-mail: dd502@york.ac.uk [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Roach, C. M. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)] [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Skipp, J. M.; Wilson, H. R. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)] [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)

2014-01-15

5

Solar wind plasma : kinetic properties and micro-instabilities  

E-print Network

The kinetic properties of ions in the solar wind plasma are studied. Observations of solar wind +H and +2He by the Faraday Cup instrument component of the Solar Wind Experiment on the Wind spacecraft show that these ions ...

Kasper, Justin Christophe, 1977-

2003-01-01

6

Microinstabilities in space plasmas: Anisotropy bounds by wave-particle scattering  

SciTech Connect

If a large-scale computer model fails to provide an accurate description of a space plasma, the discrepancy is often blamed on computational limitations, for example, the boundary conditions may not be predicted with sufficient accuracy, or the computational mesh may not be sufficiently fine. However, another possible source of inaccuracy in such models may be the physics; if the fluid equations used to represent a plasma are obtained by means of inappropriate assumptions, they cannot provide a good description of the system. In a relatively dense, relatively cold plasma, particle/particle collisions are strong. Such collisions drive the species velocity distributions toward local thermodynamic equilibrium. By considering distributions to have only small perturbations about such an equilibrium state, a set of fluid equations can be derived which is well-posed theoretically and which provides a useful description of such plasmas. Many space plasmas are relatively tenuous and relatively hot so that particle/particle interactions are weak; such plasmas are called {open_quotes}collisionless.{close_quotes} In such plasmas, interactions between particles are mediated by electromagnetic fields, including both the slowly varying electric and magnetic fields which are well represented by large-scale models and the rapidly varying, short wavelength fields which are not.

Gary, S.P.

1997-04-01

7

Magnetic compressibility and ion-temperature-gradient-driven microinstabilities in magnetically confined plasmas  

E-print Network

The electromagnetic theory of the strongly driven ion-temperature-gradient (ITG) instability in magnetically confined toroidal plasmas is developed. Stabilizing and destabilizing effects are identified, and a critical $\\beta_{e}$ (the ratio of the electron to magnetic pressure) for stabilization of the toroidal branch of the mode is calculated for magnetic equilibria independent of the coordinate along the magnetic field. Its scaling is $\\beta_{e}\\sim L_{Te}/R,$ where $L_{Te}$ is the characteristic electron temperature gradient length, and $R$ the major radius of the torus. We conjecture that a fast particle population can cause a similar stabilization due to its contribution to the equilibrium pressure gradient. For sheared equilibria, the boundary of marginal stability of the electromagnetic correction to the electrostatic mode is also given. For a general magnetic equilibrium, we find a critical length (for electromagnetic stabilization) of the extent of the unfavourable curvature along the magnetic field....

Zocco, A; Connor, J W

2015-01-01

8

Microinstabilities in weak density gradient tokamak systems  

SciTech Connect

A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

Tang, W.M.; Rewoldt, G.; Chen, L.

1986-04-01

9

Microinstabilities in the Gasdynamic Mirror Propulsion System  

NASA Technical Reports Server (NTRS)

The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohydrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regime where microinstabilities could potentially be significant.

Emrich, William

2005-01-01

10

Microinstabilities in the Gasdynamic Mirror Propulsion System  

NASA Technical Reports Server (NTRS)

The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohdrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regine where microinstabilities could potentially be significant.

Emrich, William

2005-01-01

11

Toroidal microinstability studies of high temperature tokamaks  

SciTech Connect

Results from comprehensive kinetic microinstability calculations are presented showing the effects of toroidicity on the ion temperature gradient mode and its relationship to the trapped-electron mode in high-temperature tokamak plasmas. The corresponding particle and energy fluxes have also been computed. It is found that, although drift-type microinstabilities persist over a wide range of values of the ion temperature gradient parameter /eta//sub i/ /equivalent to/ (dlnT/sub i//dr)/(dlnn/sub i//dr), the characteristic features of the dominant mode are those of the /eta//sub i/-type instability when /eta//sub i/ > /eta//sub ic/ /approximately/1.2 to 1.4 and of the trapped-electron mode when /eta//sub i/ < /eta//sub ic/. 16 refs., 7 figs.

Rewoldt, G.; Tang, W.M.

1989-07-01

12

Review of electron beam microinstabilities and their relevance to EBIS devices  

SciTech Connect

Plasma kinetic theory and some examples of microinstabilities are briefly reviewed. Although the velocity space configuration of any EBIS is inherently susceptible to a number of classical beam microinstabilities, the small radial dimension of an EBIS plasma may prevent modes from occurring in EBIS traps due to physical limitation. In EBIS devices with high electron beam compression, where the potential for beam microinstabilities is great, the radial dimension is smaller than the Debye length, which renders plasma kinetic theory invalid. Potential for parametric instabilities exists due to coupling of structure excited modes into plasma modes by various mode-mode coupling ``decay`` processes.

Hershcovitch, A.

1994-05-31

13

Gyrokinetic studies of microinstabilities in the reversed field pinch  

SciTech Connect

An analytic equilibrium, the Toroidal Bessel Function Model, is used in conjunction with the gyrokinetic code GYRO to investigate the nature of microinstabilities in a reversed field pinch plasma. The effect of the normalized electron plasma pressure ? on the characteristics of the microinstabilities is studied. At a ? of 4.5%, a transition between an ion temperature gradient (ITG) and a microtearing mode is observed. Suppression of the ITG mode occurs as in the tokamak, through coupling to shear Alfvén waves, with a critical ? for stability higher than its tokamak equivalent due to a shorter parallel connection length. A steep dependence of the microtearing growth rate on the temperature gradient suggests high profile stiffness. There is evidence for a collisionless microtearing mode. The properties of this mode are investigated, and it is found that electron curvature drift plays an important role in the instability.

Carmody, D.; Pueschel, M. J.; Terry, P. W. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2013-05-15

14

Microinstability Studies for the Large Helical Device  

SciTech Connect

Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the Large Helical Device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc., for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared.

G. Rewoldt; L.-P. Ku; W.M. Tang; H. Sugama; N. Nakajima; K.Y. Watanabe; S. Murakami; H. Yamada; W.A. Cooper

2002-01-28

15

Finite-? simulation of microinstabilities  

SciTech Connect

A new split-weight perturbative particle simulation scheme for finite-? plasmas in the presence of background inhomogeneities is presented. The scheme is an improvement over the original split-weight scheme, which splits the perturbed particle response into adiabatic and non-adiabatic parts to improve numerical properties. In the new scheme, by further separating out the adiabatic response of the particles associated with the quasi-static bending of the magnetic field lines in the presence of background inhomogeneities of the plasma, we are able to demonstrate the finite-? stabilization of drift waves and ion temperature gradient modes using a simple gyrokinetic particle code based on realistic fusion plasma parameters. However, for ?m{sub i}/m{sub e} ? 1, it becomes necessary to use the electron skin-depth as the grid size of the simulation to achieve accuracy in solving the resulting equations, unless special numerical arrangement is made for the cancelling of the two large terms on the either side of the governing equation. The proposed scheme is most suitable for studying shear-Alfvén physics in general geometry using straight field line coordinates for microturbulence and magnetic reconnection problems.

Startsev, Edward A.; Lee, W. W. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2014-02-15

16

Gyrokinetic Simulations of Microinstabilities in Stellarator Geometry  

SciTech Connect

A computational study of microinstabilities in general geometry is presented. The ion gyrokinetic is solved as an initial value problem. The advantage of this approach is the accurate treatment of some important kinetic effects. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally-efficient systematic study of the impact of the magnetic structure on microinstabilities.

J.L.V. Lewandowski

2003-08-29

17

Microinstability-based model for anomalous thermal confinement in tokamaks  

SciTech Connect

This paper deals with the formulation of microinstability-based thermal transport coefficients (chi/sub j/) for the purpose of modelling anomalous energy confinement properties in tokamak plasmas. Attention is primarily focused on ohmically heated discharges and the associated anomalous electron thermal transport. An appropriate expression for chi/sub e/ is developed which is consistent with reasonable global constraints on the current and electron temperature profiles as well as with the key properties of the kinetic instabilities most likely to be present. Comparisons of confinement scaling trends predicted by this model with the empirical ohmic data base indicate quite favorable agreement. The subject of anomalous ion thermal transport and its implications for high density ohmic discharges and for auxiliary-heated plasmas is also addressed.

Tang, W.M.

1986-03-01

18

Microinstabilities in the high latitude F region: a brief review  

SciTech Connect

This is a review of the theory of plasma microinstabilities that may arise in the high latitude F region ionosphere below 1000 km. Three free energy sources are considered: a density gradient perpendicular to the ambient magnetic field B, a current parallel to B and a steady electric field perpendicular to B. The BGK model for charged-neutral collisions is used, and the short wavelength properties of the universal density drift, current convective and E x B gradient drift instabilities are compared. At sufficiently high altitudes and sufficiently steep gradients, the universal instability is the short wavelength mode most likely to grow and, through wave-particle diffusion, to cause relatively steep wavenumber dependences in power spectra.

Gary, S.P.

1983-01-01

19

Collisionless microinstabilities in stellarators. III. The ion-temperature-gradient mode G. G. Plunk, P. Helander, P. Xanthopoulos, and J. W. Connor  

E-print Network

Collisionless microinstabilities in stellarators. III. The ion-temperature-gradient mode G. G simulations Phys. Plasmas 20, 122506 (2013); 10.1063/1.4846835 Comparing linear ion-temperature-gradient damping of ion and electron temperature gradient modes Phys. Plasmas 11, 1810 (2004); 10

20

Core micro-instability analysis of JET hybrid and baseline discharges with carbon wall  

NASA Astrophysics Data System (ADS)

The core micro-instability characteristics of hybrid and baseline plasmas in a selected set of JET plasmas with carbon wall are investigated through local linear and non-linear and global linear gyro-kinetic simulations with the GYRO code (Candy and Belli 2011 General Atomics Report GA-A26818). In particular, we study the role of plasma pressure on the micro-instabilities, and scan the parameter space for the important plasma parameters responsible for the onset and stabilization of the modes under experimental conditions. We find that a good core confinement due to strong stabilization of the micro-turbulence driven transport can be expected in the hybrid plasmas due to the stabilizing effect of the fast ion pressure that is more effective at the low magnetic shear of the hybrid discharges. While parallel velocity gradient destabilization is important for the inner core, at outer radii the hybrid plasmas may benefit from a strong quench of the turbulence transport by E × B rotation shear.

Moradi, S.; Pusztai, I.; Voitsekhovitch, I.; Garzotti, L.; Bourdelle, C.; Pueschel, M. J.; Lupelli, I.; Romanelli, M.; JET-EFDA Contributors, the

2014-12-01

21

Collisionless microinstabilities in stellarators. II. Numerical simulations  

SciTech Connect

Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.

Proll, J. H. E.; Xanthopoulos, P.; Helander, P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)

2013-12-15

22

Comparison of Linear Microinstability Calculations of Varying Input Realism  

SciTech Connect

The effect of varying ''input realism'' or varying completeness of the input data for linear microinstability calculations, in particular on the critical value of the ion temperature gradient for the ion temperature gradient mode, is investigated using gyrokinetic and gyrofluid approaches. The calculations show that varying input realism can have a substantial quantitative effect on the results.

G. Rewoldt

2003-09-08

23

Comparison of Microinstability Properties for Stellarator Magnetic Geometries  

SciTech Connect

The microinstability properties of seven distinct magnetic geometries corresponding to different operating and planned stellarators with differing symmetry properties are compared. Specifically, the kinetic stability properties (linear growth rates and real frequencies) of toroidal microinstabilities (driven by ion temperature gradients and trapped-electron dynamics) are compared, as parameters are varied. The familiar ballooning representation is used to enable efficient treatment of the spatial variations along the equilibrium magnetic field lines. These studies provide useful insights for understanding the differences in the relative strengths of the instabilities caused by the differing localizations of good and bad magnetic curvature and of the presence of trapped particles. The associated differences in growth rates due to magnetic geometry are large for small values of the temperature gradient parameter n identical to d ln T/d ln n, whereas for large values of n, the mode is strongly unstable for all of the different magnetic geometries.

G. Rewoldt; L.-P. Ku; W.M. Tang

2005-06-16

24

Microinstabilities and turbulent transport in the reversed field pinch  

NASA Astrophysics Data System (ADS)

The work presented in this thesis is concerned with addressing the nature of drift wave microturbulence in the reversed field pinch (RFP). Microturbulence is an important phenomenon and contributor to heat and particle transport in tokamaks, where it has been studied for several decades, but its role in the RFP is a rather new topic of study. As such, the nature of RFP drift waves and their relationship to their tokamak counterparts is still developing, and many of the results in this work are focused on addressing this challenge. Fundamental advances in microturbulence research have been made in recent decades through two parallel developments: the theoretical framework encompassed in the gyrokinetic model, and the computational power offered by massively-parallel, high-performance computing systems. Gyrokinetics is a formulation of kinetic theory in such a way that the fast timescale gyromotion of particles around magnetic field lines is averaged out. The implementation and use of RFP equilibrium models in gyrokinetic codes constitutes the bulk of this thesis. A simplified analytic equilibrium, the toroidal Bessel function model (TBFM), is used in the gyrokinetic code GYRO to explore the fundamental scaling properties of drift waves in the RFP geometry. Two drift wave instabilities, the ion temperature gradient (ITG) mode and the microtearing mode (MTM) are found to occur, and the relationship of their critical threshold in driving gradients and plasma beta is explored. The critical values in these parameters are found to be above those of similar tokamak cases by roughly a factor of the flux surface aspect ratio. The MTM is found to be stabilized by increasing the RFP pinch parameter theta, making it unlikely for it to unstable in the high-theta improved confinement pulsed poloidal current drive (PPCD) discharges. Efforts are also made to address microinstabilities in specific experimental discharges of the Madison Symmetric Torus (MST). A semi-analytic equilibrium, the adjusted circular model (ACM), is developed and implemented in the gyrokinetic code GENE to investigate representative PPCD discharges. The flexibility of the ACM enables it to be used for the high-theta PPCD discharges where the TBFM breaks down. The dominant linear instabilites for the discharges modeled here---ITG and the trapped electron mode (TEM)---are studied, as are their scaling properties in the PPCD regime. It is found that these instabilities are present outside of the reversal surface, where the driving gradients are strongest. Nonlinear simulations of the TEM turbulence are performed, the first such done for the RFP, and zonal flows are found to play an important role in the nonlinear saturation mechanism. These zonal flows lead to a large Dimits-like shift and suppressed transport. There is also evidence that residual global tearing mode fluctuations are a necessary part of modeling transport in the RFP, even in improved confinement PPCD discharges, and by modeling these residual fluctuations through the use of an externally imposed perpendicular magnetic field perturbation it is possible to bring simulated fluxes into agreement with experiment. Finally, the nature of the collisionless MTM, an instability seen to arise in some parameter regimes of the RFP, is investigated analytically using a fluid expansion in the drift-kinetic framework. Particular attention is paid to the role of magnetic drifts, and some evidence for their role in the collisionless instability is presented. Comparisons are made to gyrokinetic simulations and to earlier theory on the magnetic-curvature drift instability.

Carmody, Daniel Richard

25

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

NASA Astrophysics Data System (ADS)

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fülöp, T.; Timchenko, N.

2011-08-01

26

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

SciTech Connect

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fueloep, T. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden); Timchenko, N. [Institute of Tokamak Physics, NRC ''Kurchatov Institute,'' 123182, Kurchatov Sq. 1, Moscow (Russian Federation)

2011-08-15

27

MICROINSTABILITY OF THE SHOULDER IN THE OVERHEAD ATHLETE  

PubMed Central

The overhead throwing athlete is an extremely challenging patient in sports medicine. The repetitive microtraumatic stresses and extreme ranges of motion observed within the athlete’s shoulder joint complex during the throwing motion constantly place the athlete at risk for injury. While gross instability of the shoulder is possible, microinstability is seen far more frequently and is associated with a variety of different pathologies, including rotator cuff tendonitis, internal impingement, and labral lesions. Treatment of the overhead athlete requires the understanding of several principles based on the unique physical characteristics of this type of athlete and the demands placed upon the static stabilizing structures during the act of throwing. The purpose of this paper is to describe these principles and incorporate them into in a multi?phase progressive rehabilitation program designed to prevent injuries and rehabilitate the injured athlete, both non?operatively and postoperatively. PMID:24175140

Curtis, Alan S.

2013-01-01

28

Dynamics and microinstabilities at perpendicular collisionless shock: A comparison of large-scale two-dimensional full particle simulations with different ion to electron mass ratio  

SciTech Connect

Large-scale two-dimensional (2D) full particle-in-cell (PIC) simulations are carried out for studying the relationship between the dynamics of a perpendicular shock and microinstabilities generated at the shock foot. The structure and dynamics of collisionless shocks are generally determined by Alfven Mach number and plasma beta, while microinstabilities at the shock foot are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the ratio of the plasma-to-cyclotron frequency. With a fixed Alfven Mach number and plasma beta, the ratio of the upstream bulk velocity to the electron thermal velocity is given as a function of the ion-to-electron mass ratio. The present 2D full PIC simulations with a relatively low Alfven Mach number (M{sub A} ? 6) show that the modified two-stream instability is dominant with higher ion-to-electron mass ratios. It is also confirmed that waves propagating downstream are more enhanced at the shock foot near the shock ramp as the mass ratio becomes higher. The result suggests that these waves play a role in the modification of the dynamics of collisionless shocks through the interaction with shock front ripples.

Umeda, Takayuki, E-mail: umeda@stelab.nagoya-u.ac.jp; Kidani, Yoshitaka [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan)] [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Matsukiyo, Shuichi, E-mail: matsukiy@esst.kyushu-u.ac.jp [Earth System Science and Technology, Kyushu University, Kasuga 816-8580 (Japan)] [Earth System Science and Technology, Kyushu University, Kasuga 816-8580 (Japan); Yamazaki, Ryo, E-mail: ryo@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258 (Japan)] [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 252-5258 (Japan)

2014-02-15

29

On microinstabilities in the foot of high Mach number perpendicular shocks  

Microsoft Academic Search

Microinstabilities excited in the foot of a supercritical perpendicular shock wave are investigated. A two-dimensional full particle simulation with periodic boundary conditions in both directions using the physical ion to electron mass ratio is performed as a proxy for the foot region where incoming and specularly reflected ions overlap. The simulation shows that six types of different instabilities are excited

S. Matsukiyo; M. Scholer

2006-01-01

30

Electron cyclotron microinstability in the foot of a perpendicular shock: A self-consistent PIC simulation  

E-print Network

Electron cyclotron microinstability in the foot of a perpendicular shock: A self-consistent PIC simulations of perpendicular shocks and found that an electron cyclotron micr- oinstability can develop, has a frequency comparable to the electron cyclotron frequency and a wavelength shorter than

California at Berkeley, University of

31

Microinstability properties of negative magnetic shear discharges in the Tokamak Fusion Test Reactor and DIII-D  

SciTech Connect

The microinstability properties of discharges with negative (reversed) magnetic shear in the Tokamak Fusion Test Reactor (TFTR) [R. J. Hawryluk {ital et al.}, {ital Plasma Physics and Controlled Nuclear Fusion Research, 1994} (International Atomic Energy Agency, Vienna, 1995), Vol. 1, p. 11] and DIII-D [R. D. Stambaugh for the DIII-D Team, {ital Plasma Physics and Controlled Nuclear Fusion Research, 1994} (International Atomic Energy Agency, Vienna, 1995), Vol. 1, p. 83] experiments with and without confinement transitions are investigated. A comprehensive kinetic linear eigenmode calculation employing the ballooning representation is employed with experimentally measured profile data, and using the corresponding numerically computed magnetohydrodynamic (MHD) equilibria. The instability considered is the toroidal drift mode (trapped-electron-{eta}{sub i} mode). A variety of physical effects associated with differing q-profiles are explained. In addition, different negative magnetic shear discharges at different times in the discharge for TFTR and DIII-D are analyzed. The effects of sheared toroidal rotation, using data from direct spectroscopic measurements for carbon, are analyzed using comparisons with results from a two-dimensional calculation. Comparisons are also made for nonlinear stabilization associated with shear in E{sub r}/RB{sub {theta}}. The relative importance of changes in different profiles (density, temperature, q, rotation, etc.) on the linear growth rates is considered. {copyright} {ital 1997 American Institute of Physics.}

Rewoldt, G. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States)] [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States); Lao, L.L. [General Atomics, San Diego, California 92186-9784 (United States)] [General Atomics, San Diego, California 92186-9784 (United States); Tang, W.M. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States)] [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States)

1997-09-01

32

Effects of E B flows on electrostatic microinstabilities  

E-print Network

a strong stabilizing effect on toroidal Ion Temperature Gradient (ITG) modes. If the plasma rotation called internal transport barrier by the presence of a strong radial electric field in the plasma used to study the effects of a radial electric field in the presence of trapped particles in particular

33

Microstability of Magnetically Confined Electron-Positron Plasmas  

NASA Astrophysics Data System (ADS)

It is shown that magnetically confined electron-positron plasmas can enjoy remarkable stability properties. Many of the microinstabilities driving turbulence and transport in electron-ion plasmas are absent if the density is so low that the Debye length is significantly larger than the gyroradius. In some magnetic configurations, almost complete linear stability may be attainable in large parts of the parameter space.

Helander, P.

2014-09-01

34

Microinstabilities associated with a high Mach number, perpendicular bow shock  

NASA Technical Reports Server (NTRS)

Instability analyses incorporating insights gained through ISEE observations and hybrid simulations are used in an examination of the instabilities associated with a high Mach number perpendicular shock akin to the earth's bow shock. In the regions in front of, and at, the shock transition the cross-field instabilities are subdivided into the ion-ion streaming, kinetic cross-field streaming, and drift lower hybrid instability low frequency modes, as well as the electron cyclotron drift, ion sound, and electron whisker instability high frequency modes. Further downstream, ion ring-like and anisotropy-driven instabilities are considered. The implications of these results for wave signatures, plasma heating and acceleration are noted.

Wu, C. S.; Winske, D.; Tanaka, M.; Papadopoulos, K.; Akimoto, K.; Goodrich, C. C.; Zhou, Y. M.; Tsai, S. T.; Rodriguez, P.; Lin, C. S.

1984-01-01

35

On microinstabilities in the foot of high Mach number perpendicular shocks  

NASA Astrophysics Data System (ADS)

Microinstabilities excited in the foot of a supercritical perpendicular shock wave are investigated. A two-dimensional full particle simulation with periodic boundary conditions in both directions using the physical ion to electron mass ratio is performed as a proxy for the foot region where incoming and specularly reflected ions overlap. The simulation shows that six types of different instabilities are excited in a time period shorter than ion gyroperiod of the reflected ions. The most dominant instability is the modified two-stream instability, which leads to strong parallel electron heating through a so-called two step instability and to ion phase space holes.

Matsukiyo, S.; Scholer, M.

2006-06-01

36

Preconditioning Eigensolvers for Computing Unstable Modes of Plasma List of authors  

E-print Network

of the microinstabilities in the plasma produced by gradients in the temperature, magnetic field and density and a sparse part Lg. The latter matrix has a block diagonal sparse multi-banded structure because of the processes occurring in magnetically confined plasmas, such as the anomalous transport (large amounts

Boyer, Edmond

37

Collisionless microinstabilities in stellarators. I. Analytical theory of trapped-particle modes  

SciTech Connect

This is the first in a series of papers about collisionless, electrostatic micro-instabilities in stellarators, with an emphasis on trapped-particle modes. It is found that, in so-called maximum-J configurations, trapped-particle instabilities are absent in large regions of parameter space. Quasi-isodynamic stellarators have this property (approximately), and the theory predicts that trapped electrons are stabilizing to all eigenmodes with frequencies below the electron bounce frequency. The physical reason is that the bounce-averaged curvature is favorable for all orbits, and that trapped electrons precess in the direction opposite to that in which drift waves propagate, thus precluding wave-particle resonance. These considerations only depend on the electrostatic energy balance and are independent of all geometric properties of the magnetic field other than the maximum-J condition. However, if the aspect ratio is large and the instability phase velocity differs greatly from the electron and ion thermal speeds, it is possible to derive a variational form for the frequency showing that stability prevails in a yet larger part of parameter space than what follows from the energy argument. Collisionless trapped-electron modes should therefore be more stable in quasi-isodynamic stellarators than in tokamaks.

Helander, P.; Proll, J. H. E.; Plunk, G. G. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany) [Max-Planck-Institut für Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany); Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)

2013-12-15

38

Effect of Plasma Shape on Electron Heat Transport in the Presence of Extreme Temperature Gradients Variations in TCV  

Microsoft Academic Search

Electron heat transport experiments are performed in L-mode plasmas at various plasma triangularities, using radially localised electron cyclotron (EC) heating to vary the normalised electron temperature gradient R\\/LTe (where 1\\/LTe= ?Te\\/Te) and the electron temperature Te over an unusually large range. Local gyro-fluid (GLF23) and global collisionless gyro-kinetic (LORB5) linear simulations allow the determination of the unstable micro-instabilities. Ion temperature

A. Pochelon; Y. Camenen; R. Behn; A. Bortolon; A. Bottino; S. Coda; B. P. Duval; E. Fable; T. P. Goodman; M. A. Henderson; A. N. Karpushov; J.-M. Moret; A. Mück; E. Nelson-Melby

39

Microinstability properties of negative magnetic shear discharges in the Tokamak Fusion Test Reactor and DIII-D  

SciTech Connect

The microinstability properties of discharges with negative (reversed) magnetic shear in the Tokamak Fusion Test Reactor (TFTR) and DIII-D experiments with and without confinement transitions are investigated. A comprehensive kinetic linear eigenmode calculation employing the ballooning representation is employed with experimentally measured profile data, and using the corresponding numerically computed magnetohydrodynamic (MHD) equilibria. The instability considered is the toroidal drift mode (trapped-electron-{eta}{sub i} mode). A variety of physical effects associated with differing q-profiles are explained. In addition, different negative magnetic shear discharges at different times in the discharge for TFTR and DIII-D are analyzed. The effects of sheared toroidal rotation, using data from direct spectroscopic measurements for carbon, are analyzed using comparisons with results from a two-dimensional calculation. Comparisons are also made for nonlinear stabilization associated with shear in E{sub r}/RB{sub {theta}}. The relative importance of changes in different profiles (density, temperature, q, rotation, etc.) on the linear growth rates is considered.

Rewoldt, G.; Tang, W.M. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.; Lao, L.L. [General Atomics, San Diego, CA (United States)

1997-03-01

40

Comparing Linear Microinstability of the National Compact Stellarator Expriment and a Shaped Tokamak  

SciTech Connect

One metric for comparing con nement properties of di erent magnetic fusion energy con gurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion tem- perature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the pro les of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing e ects of the stellarator con guration o set this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar critical gradients, though beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/LT ?#25; 1:5 a/LT;crit, when it surpassed the tokamak's. A discussion of the results presented with respect to a/LT vs R/LT is included.

J.A. Baumgaertel, G.W. Hammett and D.R. Mikkelsen

2012-11-20

41

plasmas  

NASA Astrophysics Data System (ADS)

As-deposited HfO2 films were modified by CHF3, C4F8, and mixed C4F8/O2 plasmas in a dual-frequency capacitively coupled plasma chamber driven by radio frequency generators of 60 MHz as the high frequency (HF) source and 2 MHz as the low frequency source (60/2 MHz). The influences of various surface plasma treatments under CHF3, C4F8, and C4F8/O2 were investigated in order to understand the chemical and structural changes in thin-film systems, as well as their influence on the electrical properties. Fluorine atoms were incorporated into the HfO2 films by either CHF3 or C4F8 plasma treatment; meanwhile, the C/F films were formed on the surface of the HfO2 films. The formation of C/F layers decreased the k value of the gate stacks because of its low dielectric constant. However, the addition of O2 gas in the discharge gases suppressed the formation of C/F layers. After thermal annealing, tetragonal HfO2 phase was investigated in both samples treated with CHF3 and C4F8 plasmas. However, the samples treated with O-rich plasmas showed monoclinic phase, which indicated that the addition of O plasmas could influence the Hf/O ratio of the HfO2 films. The mechanism of the t-HfO2 formation was attributed to oxygen insufficiency generated by the incorporation of F atoms. The capacitors treated with C4F8/O2 plasmas displayed the highest k value, which ascribed that the C/F layers were suppressed and the tetragonal phase of HfO2 was formed. Good electrical properties, especially on the hysteresis voltage and frequency dispersion, were obtained because the bulk traps were passivated by the incorporation of F atoms. However, the H-related traps were generated during the CHF3 plasma treatments, which caused the performance degradation. All the treated samples showed lower leakage current density than the as-deposited HfO2 films at negative bias due to the reduced trap-assisted tunneling by the incorporation of F to block the electrons transferring from metal electrode to the trap level.

Zhang, H. Y.; Jin, C. G.; Yang, Y.; Ye, C.; Zhuge, L. J.; Wu, X. M.

2014-12-01

42

Updating Plasma Scattering of Electromagnetic Radiation  

NASA Astrophysics Data System (ADS)

The monograph Plasma Scattering of Electromagnetic Radiation was published by Academic Press in 1975. A Russian edition, Atomidzat, came out in 1978. An updated version is being prepared by D. Froula, S. Glenzer. N Luhmann, and J. Sheffield for publication in 2010 by Elsevier. The new version will discuss the broader applications of Thomson scattering, which include the full range of plasmas used in research and industry. The expansion of the field has been made possible by the growing number of powerful radiation sources (from X-rays to microwaves), detectors, and innovative techniques. When the book was published, the highest temperatures in laboratory plasmas were around 2 keV for the electrons. Compare this to today's 25 keV where the relativistic effects are dramatic. The application to low temperature plasmas with Te in the range of 1 - 30+ eV, important in industry, has grown. Important capabilities have been developed in the areas of energetic particle, micro-instability, and high energy density plasma measurements. For the future, we look forward to the use of scattering as a diagnostic on the large new fusion facilities-NIF, LMJ, and ITER.

Sheffield, J.

2010-05-01

43

Evolution of the IR-T1 Tokamak Plasma Local and Global Parameters  

NASA Astrophysics Data System (ADS)

In this contribution, an attempt is made to investigate of evolution of some local and global plasma parameters in IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed and installed on outer surface of the tokamak and then asymmetry factor is obtained from them. On the other hand, diamagnetic loop were designed and installed on IR-T1 and poloidal beta is determined from it. Therefore, the internal inductance and effective edge safety factor measured. Also, time evolution of the energy confinement time is measured using the diamagnetic loop. Experimental results show that maximum energy confinement time (which correspond to minimum collisions, minimum microinstabilities and minimum transport), relate to the low values of effective edge safety factor and also relate to the low values of internal inductance.

Salar Elahi, A.; Ghoranneviss, M.

2013-09-01

44

Production of superthermal electrons and ion cyclotron waves in a reversed-field-pinch plasma  

SciTech Connect

Production of superthermal electrons through kinetic interactions with electromagnetic fluctuations is studied to account for observations of fast electrons and ion cyclotron waves in reversed field pinch plasmas. Low-frequency Alfvenic (torsional) modes can interact with electrons through the Landau resonance when the wavelength perpendicular to the magnetic field is as small as the ion gyroradius. Such kinetic Alfven waves induce simultaneous diffusion (double diffusion) in the coordinate and velocity spaces, and produce a field aligned superthermal electron beam in the edge region. Microinstabilities are driven by the electron-beam and ion cyclotron waves are excited. Through these precesses the fluctuation energy in the low-frequency regime may be transported to the ion cyclotron frequency regime.

Yoshida, Z. (Department of Nuclear Engineering, University of Tokyo, Hongo, Tokyo 113 (Japan)); Hasegawa, A. (Department of Communication Engineering, Osaka University, Suita, Osaka 565 (Japan)); Wakatani, M. (Plasma Physics Laboratory, Kyoto University, Gokasho, Uji 611 (Japan))

1993-09-01

45

Trapped ion mode in toroidally rotating plasmas  

SciTech Connect

The influence of radially sheared toroidal flows on the Trapped Ion Mode (TIM) is investigated using a two-dimensional eigenmode code. These radially extended toroidal microinstabilities could significantly influence the interpretation of confinement scaling trends and associated fluctuation properties observed in recent tokamak experiments. In the present analysis, the electrostatic drift kinetic equation is obtained from the general nonlinear gyrokinetic equation in rotating plasmas. In the long perpendicular wavelength limit k{sub {tau}}{rho}{sub bi} {much_lt} 1, where {rho}{sub bi} is the average trapped-ion banana width, the resulting eigenmode equation becomes a coupled system of second order differential equations nmo for the poloidal harmonics. These equations are solved using finite element methods. Numerical results from the analysis of low and medium toroidal mode number instabilities are presented using representative TFTR L-mode input parameters. To illustrate the effects of mode coupling, a case is presented where the poloidal mode coupling is suppressed. The influence of toroidal rotation on a TFTR L-mode shot is also analyzed by including a beam species with considerable larger temperature. A discussion of the numerical results is presented.

Artun, M.; Tang, W.M.; Rewoldt, G.

1995-04-01

46

Instabilities in counter-propagating ion beams and plasmas  

NASA Astrophysics Data System (ADS)

Collisionless shocks are frequent events in the interstellar medium, they can also take place in inertial fusion targets where high energy ion beams interact with target plume plasma. The understanding of the processes is consequently important from a theoretical point of view and for laboratory laser--plasma interaction experiments. In this paper, we consider interaction of two counter-propagating homogeneous plasma beams with sub-relativistic velocities and no external magnetic field applied. In numerical simulations performed with a particle-in-cell code three stages of evolution can be identified. The shock formation is initiated with development of the electron-ion Weibel-like micro-instabilities, followed by fast electron heating and ion de-acceleration and heating. We present a theoretical analysis of the instabilities development and nonlinear saturation to explore the origins of the heating and the magnetic field generation. The analysis is done in the center of mass frame, considering the Lorentz transformation for each beam from its own reference frame. From the dispersion relation, instability is characterized and dependence on the electron temperature and ion velocity is studied.The growth rate and characteristic scales of instability are compared to simulations.

Jequier, Sophie; Tikhonchuck, Vladimir; D'Humieres, Emmanuel; Capdessus, Remi; Davis, Stanley

2012-10-01

47

Transport properties of H-mode plasmas with dominant electron heating in comparison to dominant ion heating at ASDEX Upgrade  

NASA Astrophysics Data System (ADS)

The influence of electron heating compared to ion heating on plasma performance has been analysed in order to make valid projections towards future devices. The capabilities of the newly upgraded electron cyclotron resonance heating system at ASDEX Upgrade make this analysis feasible by replacing neutral beam injection. Dominantly electron heated plasmas are analysed and compared to dominantly ion heated plasmas. It is investigated if they behave systematically different or if the change of heated species is fully compensated by heat exchange from electrons to ions. Studies of plasmas at high collisionalities are presented in Sommer et al (2012 Nucl. Fusion 52 114018). Here, these former investigations are extended towards lower collisionalities. The global plasma parameters show a slight reduction with increasing electron heating arising from a significant decrease of the ion temperature, whereas the electron temperature profile is unchanged. The density profile shows a strong peaking which remains unchanged when modifying the heating mix. The power balance analysis shows an important impact of the heat exchange between electrons and ions. The electron and ion temperatures and the plasma density are modelled with the transport model TGLF. The experimental observations are reproduced verifying the applied code. Linear gyrokinetic calculations with GS2 found the ion temperature gradient mode to be the dominant microinstability in all analysed cases.

Sommer, F.; Stober, J.; Angioni, C.; Fable, E.; Bernert, M.; Burckhart, A.; Bobkov, V.; Fischer, R.; Fuchs, C.; McDermott, R. M.; Suttrop, W.; Viezzer, E.; the ASDEX Upgrade Team

2015-03-01

48

Currents between tethered electrodes in a magnetized laboratory plasma  

NASA Technical Reports Server (NTRS)

Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

Stenzel, R. L.; Urrutia, J. M.

1989-01-01

49

SciDAC - Center for Plasma Edge Simulation - Project Summary  

SciTech Connect

Final Technical Report: Center for Plasma Edge Simulation (CPES) Principal Investigator: Scott Parker, University of Colorado, Boulder Description/Abstract First-principle simulations of edge pedestal micro-turbulence are performed with the global gyrokinetic turbulence code GEM for both low and high confinement tokamak plasmas. The high confinement plasmas show a larger growth rate, but nonlinearly a lower particle and heat flux. Numerical profiles are obtained from the XGC0 neoclassical code. XGC0/GEM code coupling is implemented under the EFFIS (“End-to-end Framework for Fusion Integrated Simulation”) framework. Investigations are underway to clearly identify the micro-instabilities in the edge pedestal using global and flux-tube gyrokinetic simulation with realistic experimental high confinement profiles. We use both experimental profiles and those obtained using the EFFIS XGC0/GEM coupled code framework. We find there are three types of instabilities at the edge: a low-n, high frequency electron mode, a high-n, low frequency ion mode, and possibly an ion mode like kinetic ballooning mode (KBM). Investigations are under way for the effects of the radial electric field. Finally, we have been investigating how plasmas dominated by ion-temperature gradient (ITG) driven turbulence, how cold Deuterium and Tritium ions near the edge will naturally pinch radially inward towards the core. We call this mechanism “natural fueling.” It is due to the quasi-neutral heat flux dominated nature of the turbulence and still applies when trapped and passing kinetic electron effects are included. To understand this mechanism, examine the situation where the electrons are adiabatic, and there is an ion heat flux. In such a case, lower energy particles move inward and higher energy particles move outward. If a trace amount of cold particles are added, they will move inward.

Parker, Scott

2014-11-03

50

Currents between tethered electrodes in a magnetized laboratory plasma  

SciTech Connect

Laboratory experiments on important plasma physics issues of electrodynamic tethers are performed. These include current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The current system is established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential differences up to V {approx} 100 kT{sub e}/e. The total current density in space and time is obtained from complete measurements of the perturbed magnetic field. J = {gradient} {times} B(r,t)/{mu}{sub 0}. The fast spacecraft motion is reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generall accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large-amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions, and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects.

Stenzel, R.L.; Urrutia, J.M. (Univ. of California, Los Angeles (United States))

1990-05-01

51

Flute instability growth on a magnetized plasma column.  

SciTech Connect

The growth of the flute-type instability for a field-aligned plasma column immersed in a uniform magnetic field is studied. Particle-in-cell simulations are compared with a semi-analytic dispersion analysis of the drift cyclotron instability in cylindrical geometry with a Gaussian density profile in the radial direction. For the parameters considered here, the dispersion analysis gives a local maximum for the peak growth rates as a function of R/r{sub i}, where R is the Gaussian characteristic radius and r{sub i} is the ion gyroradius. The electrostatic and electromagnetic particle-in-cell simulation results give azimuthal and radial mode numbers that are in reasonable agreement with the dispersion analysis. The electrostatic simulations give linear growth rates that are in good agreement with the dispersion analysis results, while the electromagnetic simulations yield growth rate trends that are similar to the dispersion analysis but that are not in quantitative agreement. These differences are ascribed to higher initial field fluctuation levels in the electromagnetic field solver. Overall, the simulations allow the examination of both the linear and nonlinear evolution of the instability in this physical system up to and beyond the point of wave energy saturation. Keywords: Microinstabilities, Magnetic confinement and equilibrium, Particle-in-cell method.

Genoni, Thomas C. (Voss Scientific, LLC, Albuquerque, NM); Welch, Dale Robert (Voss Scientific, LLC, Albuquerque, NM); Ditmire, T. (University of Texas at Austin, Austin, TX); Rose, David Vincent (Voss Scientific, LLC, Albuquerque, NM); Mehlhorn, Thomas Alan; Porter, John Larry, Jr.

2006-08-01

52

Sheared Rotation Effects on Kinetic Stability in Enhanced Confinement Tokamak Plasmas, and Nonlinear Dynamics of Fluctuations and Flows in Axisymmetric Plasmas  

SciTech Connect

Sheared rotation dynamics are widely believed to have signficant influence on experimentally observed confinement transitions in advanced operating modes in major tokamak experiments, such as the Tokamak Fusion Test Reactor (TFTR) [D.J. Grove and D.M. Meade, Nuclear Fusion 25, 1167 (1985)], with reversed magnetic shear regions in the plasma interior. The high-n toroidal drift modes destabilized by the combined effects of ion temperature gradients and trapped particles in toroidal geometry can be strongly affected by radially sheared toroidal and poloidal plasma rotation. In previous work with the FULL linear microinstability code, a simplified rotation model including only toroidal rotation was employed, and results were obtained. Here, a more complete rotation model, that includes contributions from toroidal and poloidal rotation and the ion pressure gradient to the total radial electric field, is used for a proper self-consistent treatment of this key problem. Relevant advanced operating mode cases for TFTR are presented. In addition, the complementary problem of the dynamics of fluctuation-driven E x B flow is investigated by an integrated program of gyrokinetic simulation in annulus geometry and gyrofluid simulation in flux tube geometry.

Beer, M.A.; Chance, M.S.; Hahm, T.S.; Lin, Z.; Rewoldt, G.; Tang, W.M.

1997-11-01

53

Modeling of impurity effect on drift instabilities in plasmas with many ion species  

SciTech Connect

Drift microinstabilities, being the main cause of anomalous transport of charged particles and energy in fusion plasmas, can be strongly influenced by the presence of impurities. Normally a large amount of different ion species from diverse charge states and chemical elements is present. An approach, providing a possibility to take into account an arbitrary number of ion species in analysis of instabilities, is proposed and applied to study the impurity effect on unstable modes due to ion temperature gradient and trapped electrons described in a linear fluid approximation. The method is validated by comparing with the results from direct calculations in a one impurity ion case. The dependence of instability characteristics and anomalous transport coefficients on the absolute level and radial gradient of impurity density is investigated. Plasmas with several impurity ion species, including C{sup +6}, N{sup +7}, O{sup +8}, Ne{sup +10}, and Ar{sup +18} whose density peaking factors are determined self-consistently from the impurity zero flux condition, are considered as an example of applications.

Moradi, S. [Department of Statistical and Plasma Physics, Universite Libre de Bruxelles, 1050 Brussels (Belgium); Tokar, M. Z. [Institute fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Trilateral Euregio Cluster, 52425 Juelich (Germany); Weyssow, B. [EFDA-CSU, D-85748 Garching, Muenchen (Germany)

2010-01-15

54

Plasma turbulence  

SciTech Connect

The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.

Horton, W. [Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies; Hu, G. [Globalstar LP, San Jose, CA (United States)

1998-07-01

55

Numerical simulation of non-equilibrium plasma flow in a cylindrical MPD thruster using a high-order flux-difference splitting method  

NASA Astrophysics Data System (ADS)

A two-dimensional axisymmetric computational algorithm is developed to simulate the plasma flow field in a self-field MPD thruster, in order to determine the flow behavior and the electromagnetic characteristics distribution. The convective flux vector is computed by using Roe's scheme in combination with Powell's eigensystem technique, and a new modified MUSCL technique called OMUSCL2 is employed to obtain the stable high-accuracy solution. Madrane-Tadmor entropy correction is used to prevent unrealistic expansion shocks near the electrodes tips. To accurately capture the physics of plasma in the system, different physical-chemical sub-models including multi-level non-equilibrium ionization model, generalized Ohm's law for partially ionized plasma, micro-instabilities effects, two-temperature model, and a real equation of state are considered. Numerical results of plasma flow simulation in a cylindrical lab-scale thruster, with mass flow rate of 6 g/s and total discharge current of 8 kA, are presented and comparison with experimental data shows good agreement between the predicted and measured contours of enclosed current and electric potential. The estimated thrust is 16.34 N which exhibits less than 5% difference compared with measured value. Furthermore, this simulation properly predicts the experimentally observed argon jet structure.

Ahangar, Mahdy; Ebrahimi, Reza; Shams, Mehrzad

2014-10-01

56

Plasma jets and plasma bullets  

Microsoft Academic Search

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma

M G Kong; B N Ganguly; R F Hicks

2012-01-01

57

Plasma universe  

NSDL National Science Digital Library

This single-page reading underlines how abundant plasmas are in the universe. The reading, which is the final page in a tutorial about the plasma phase of matter, points out that understanding plasma is central to understanding what happens in the universe. Through space technologies, researchers have been able to study plasmas in areas like those shown in the images that illustrate this reading. One of the images shows plasma loops on the Sun. Copyright 2005 Eisenhower National Clearinghouse

Space Science Institute

2005-01-01

58

Integrated plasma physics modelling for the Culham steady state spherical tokamak fusion power plant  

NASA Astrophysics Data System (ADS)

Integrated modelling of important plasma physics issues related to the design of a steady-state spherical tokamak (ST) fusion power plant is described. The key is a steady-state current drive, and 92% of this is provided by a combination of bootstrap and diamagnetic currents, both of which have a substantial toroidal component in a ST. The remaining current is to be provided by either neutral beam injection or radio-frequency waves, and various schemes for providing this are discussed and quantified. The desire to achieve a high bootstrap current drives the design to high plasma pressure, bgr (normalized to the magnetic field pressure), and high elongation. Both these requirements have implications for ideal magneto-hydrodynamic instability which are discussed. Confinement is addressed both through comparison with the recent scaling laws developed from the conventional tokamak database and self-consistent one-dimensional modelling of the transport processes. This modelling shows that the power required for the current drive (~50 MW) is sufficient to heat the plasma to a regime where more than 3 GW of fusion power is produced, taking into account the dilution due to He ash and prompt agr-particle losses, which are small. A preliminary study of the micro-instabilities, which may be responsible for the turbulent transport is provided. Given assumptions about the particle confinement, we make estimates of the fuelling requirements to maintain the steady state. Finally, the power loading due to the exhaust is derived using theory-based scalings for the scrape-off layer width.

Wilson, H. R.; Ahn, J.-W.; Akers, R. J.; Applegate, D.; Cairns, R. A.; Christiansen, J. P.; Connor, J. W.; Counsell, G.; Dnestrovskij, A.; Dorland, W. D.; Hole, M. J.; Joiner, N.; Kirk, A.; Knight, P. J.; Lashmore-Davies, C. N.; McClements, K. G.; McGregor, D. E.; O'Brien, M. R.; Roach, C. M.; Tsaun, S.; Voss, G. M.

2004-08-01

59

Plasma Physics  

Microsoft Academic Search

Beginning at an introductory level, this text presents a thorough treatment of plasma physics, including an extensive discussion of its applications in thermonuclear fusion research. A novel feature of this book is its comprehensive description of the various concepts and formulas widely used in fusion theory based on the fundamental equations of the plasma fluid. The physics of fusion plasmas

Kyoji Nishikawa; Masashiro Wakatani

1990-01-01

60

Amazing plasmas  

NSDL National Science Digital Library

A space weather site offers this tutorial about the state of matter called plasma. Animations, two games, and numerous enlargeable graphics are included in the tutorial. It presents information about what plasma is and where it is naturally found. The tutorial explains that understanding plasma and how it interacts with electric and magnetic fields is central to understanding much about our universe. In addition, one section of the tutorial discusses experimental fusion reactors in which man-made plasmas are used on earth. Plasma is the main type of matter in the universe, but it rarely occurs naturally on Earth because of the world's relatively cool temperatures. Copyright 2005 Eisenhower National Clearinghouse

Space Science Institute

2005-01-01

61

Dusty plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.

Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.

1996-05-01

62

[Plasma cells].  

PubMed

Plasma cells are specialized terminally differentiated B cells that synthesize and secrete antibodies to maintain humoral immunity. By the production of pathogenic antibodies, plasma cells contribute to the development of many conditions, such as autoimmune disorders, transplant rejection and allergies. Two different plasma cell compartments can independently generate different types of pathogenic antibodies: (1) short-lived plasmablasts (proliferating precursors of mature plasma cells) and plasma cells, which live only as long as B cells are activated. Consequently, these cells cause disease flares that respond to immunosuppressive drugs and B cell targeting therapies. (2) Long-lived non-proliferating memory plasma cells, which survive in niches in bone marrow and inflamed tissues for months, years or a lifetime independent of B or T cell help or antigen contact. Because they do not respond to immunosuppressants or treatment targeting B cells, they are responsible for refractory chronic conditions. Therefore, long-lived memory plasma cells in particular have emerged as important therapeutic targets and strategies to target these cells are discussed in this article. So far long-lived plasma cells can only be depleted by immunoablative therapy with antithymocyte globulin in the setting of stem cell transplantation or by treatment with proteasome inhibitors approved for multiple myeloma. These strategies provide options for treating refractory autoantibody-mediated diseases. One interesting approach aims at an antigen-specific elimination of target plasma cells without depleting the protective plasma cells responsible for maintaining humoral immunity. PMID:25616773

Hiepe, F; Alexander, T; Voll, R E

2015-02-01

63

Linear gyrokinetic calculations of toroidal momentum transport in the presence of trapped electron modes in tokamak plasmas  

SciTech Connect

The toroidal momentum transport in the presence of trapped electron mode microinstabilities in tokamak plasmas is studied by means of quasilinear gyrokinetic calculations. In particular, the role of the Coriolis drift in producing an inward convection of toroidal momentum is investigated. The Coriolis drift term has been implemented in the gyrokinetic code GS2 [W. Dorland et al., Phys. Rev. Lett. 85, 5579 (2000)] specifically for the completion of this work. A benchmark between the GS2 implementation of the Coriolis drift and the implementations included in two other gyrokinetic codes is presented. The numerical calculations show that in the presence of trapped electron modes, despite of a weaker symmetry breaking of the eigenfunctions with respect to the case of ion temperature gradient modes, a pinch of toroidal momentum is produced in most conditions. The toroidal momentum viscosity is also computed, and found to be small as compared with the electron heat conductivity, but significantly larger than the ion heat conductivity. In addition, interesting differences are found in the dependence of the toroidal momentum pinch as a function of collisionality between trapped electron modes and ion temperature gradient modes. The results identify also parameter domains in which the pinch is predicted to be small, which are also of interest for comparisons with the experiments.

Kluy, N.; Angioni, C. [Max-Planck-Institut fuer Plasmaphysik, IPP-EURATOM Association, D-85748 Garching bei Muenchen (Germany); Camenen, Y.; Peeters, A. G. [Department of Physics, Center for Fusion, Space, and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2009-12-15

64

Observation of shock-generated turbulence in a magnetized plasma by CO/sub 2/ laser scattering  

SciTech Connect

Small angle CO/sub 2/ laser scattering is used to sense density fluctuations produced by microinstabilities in a collisionless plasma driven by a magnetic implosion in a high voltage theta pinch. Turbulent density fluctuations are measured at a wavelength near the Debye length within and behind the current sheet of the imploding shock. Two main scattering features are found. The earlier feature, occurring at the leading edge of the current sheet, is only about 30 nsec wide and is narrowly radial. It appears to be driven by ions reflected from the shock front and is believed due to an ion beam driven electron cyclotron instability. The later feature, peaking about 70 nsec after the first, is broader in time and has a maximum rotated about 25/sup 0/ from the azimuthal (current sheet) direction, with a half-width of 40/sup 0/. It appears to be due to the ion acoustic instability, driven by relative drift of electrons and ions in the current sheet.

Gold, S.H.; DeSilva, A.W.; Huba, J.D.

1980-06-01

65

Earth plasmas  

NSDL National Science Digital Library

Fusion is the focus of this section of a tutorial about plasma, one of the four states of matter. This section deals with plasmas on Earth. There is little naturally-occurring plasma here because of the Earth's relatively cool (by universe standards) temperature, but human-made plasma is produced for industry and research purposes. The section explores the use of plasmas in experimental fusion reactors, pointing out three categories of significant unresolved issues that stand in the way of fusion becoming a viable energy source. The use of electromagnets to confine plasmas is discussed. Enlargeable images of fusion reactors are provided, and an explanation of the difference between fission and fusion is supplemented by animations of the two reaction types. Copyright 2005 Eisenhower National Clearinghouse

Space Science Institute

2005-01-01

66

Plasma accelerator  

DOEpatents

There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

Wang, Zhehui (Los Alamos, NM); Barnes, Cris W. (Santa Fe, NM)

2002-01-01

67

Plasma valve  

DOEpatents

A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

Hershcovitch, Ady (Mount Sinai, NY); Sharma, Sushil (Hinsdale, IL); Noonan, John (Naperville, IL); Rotela, Elbio (Clarendon Hills, IL); Khounsary, Ali (Hinsdale, IL)

2003-01-01

68

Thermal plasmas  

Microsoft Academic Search

Although many thermal plasma processes have been developed for industrial applications, the wide acceptance as a manufacturing technology is prevented due to economical and competitive reasons, and\\/or reproducibility and reliability aspects. This paper is devoted to an assessment of the present knowledge in the following topics: (1) plasma torch and performance of blown arc (dc or ac), transferred arc and

P. Fauchais; A. Vardelle

1997-01-01

69

Plasma Effects  

NASA Technical Reports Server (NTRS)

Radio communication with space probes requires sending signals through the Earth's ionosphere and usually the solar wind. During planetary flybys, the signal may also pass through the ionosphere of another planet. These ionized media can perturb the radio signal in a variety of ways. Examples of these perturbations are variations in the electrical length between the spacecraft and the ground station, Faraday rotation of linearly polarized signals, amplitude and phase scintillations, and spectral and angular broadening. These plasma effects can have undesirable influences on telemetry performance and thus need to be understood from a communications engineering viewpoint. The plasma effects are, however, useful from a scientific viewpoint, since the effects on the communications link can often be inverted to estimate the physical conditions in the plasma.

Armstrong, J. W.

1983-01-01

70

Plasma Physics  

NSDL National Science Digital Library

This is a PDF version of lecture slides by Dr. Philip D. Rack (Assistant Professor, Department of Materials Science and Engineering at the University of Tennessee in Knoxville) that discuss information from the silicon's crystal structure to how to make doped semiconductors and the mechanics. Although the slides were written by Dr. Rack when he taught at the Rochester Institute of Technology, they are currently hosted by him at the University of Tennessee. Slide topics include plasma properties, DC glow discharge, ionization, plasma species, magnetrons, collisions, and chemical reactions. Numerous mathematical formulas are also presented.

Rack, Philip D.

71

Burning plasmas  

SciTech Connect

The fraction of fusion-reaction energy that is released in energetic charged ions, such as the alpha particles of the D-T reaction, can be thermalized within the reacting plasma and used to maintain its temperature. This mechanism facilitates the achievement of very high energy-multiplication factors Q, but also raises a number of new issues of confinement physics. To ensure satisfactory reaction operation, three areas of energetic-ion interaction need to be addressed: single-ion transport in imperfectly symmetric magnetic fields or turbulent background plasmas; energetic-ion-driven (or stabilized) collective phenomena; and fusion-heat-driven collective phenomena. The first of these topics is already being explored in a number of tokamak experiments, and the second will begin to be addressed in the D-T-burning phase of TFTR and JET. Exploration of the third topic calls for high-Q operation, which is a goal of proposed next-generation plasma-burning projects. Planning for future experiments must take into consideration the full range of plasma-physics and engineering R D areas that need to be addressed on the way to a fusion power demonstration.

Furth, H.P.; Goldston, R.J.; Zweben, S.J. (Princeton Univ., NJ (USA). Plasma Physics Lab.); Sigmar, D.J. (Massachusetts Inst. of Tech., Cambridge, MA (USA))

1990-10-01

72

Complex Plasmas  

Microsoft Academic Search

\\u000a An ionized gas containing ions, electrons and neutral atoms is called a plasma if it meets the conditions quasineutrality\\u000a and collective behavior. The quasineutrality exists for distances much larger than the Debye length at which the potential\\u000a caused by a charged particle has dropped to \\u000a 1\\/e1\\/e\\u000a due to the shielding by oppositely charged species. Collective behavior arises when one charged

Christina A. Knapek

73

Kinetic theory of plasma waves, homogeneous plasmas  

Microsoft Academic Search

The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is

Miklos Porkolab

1998-01-01

74

Properties of large scale plasma flow during the early stage of the plasmaspheric refilling  

NASA Technical Reports Server (NTRS)

The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate ionospheres towards the equator; the equatorial temperature is found to be as high as about 8000 K compared to the ionospheric temperature of 3600 K.

Singh, Nagendra; Craven, P.; Torr, D. G.; Richards, P. G.

1990-01-01

75

Plasma Waves  

Microsoft Academic Search

\\u000a The interest in wave propagation in plasmas has different roots. One of these was the reflection of electromagnetic waves\\u000a by the ionosphere [91]. Stimulated by Guglielmo Marconi’s (1874–1937) experiments on long-distance radio in 1901, Oliver Heaviside\\u000a (1850–1925) [92] and, independently, Arthur Edwin Kennelly (1861–1939) [93] postulated, in 1902, that the Earth’s atmosphere\\u000a at high altitude must contain an electrically conducting

Alexander Piel

76

Principles of Plasma Spectroscopy  

Microsoft Academic Search

This book gives a comprehensive treatment of plasma spectroscopy, the quantitative study of line and continuous radiation from high temperature plasmas. This highly interdisciplinary field combines elements of atomic, plasma and statistical physics, and has wide application to simulations and diagnostics of laboratory and astrophysical plasmas. Plasma spectroscopy is naturally intertwined with magnetic and inertial fusion energy science. Radiative processes

A. L. Osterheld

1998-01-01

77

The Pervasive Plasma State  

NSDL National Science Digital Library

This site by the Division of Plasma Physics of the American Physical Society explores plasma, a state of matter that blankets the Earth as a result of solar winds. Pictures and text are used to convey the significance and commonplace use of plasmas in society. Information provided by the site includes understanding plasmas, commercial applications, plasma in space, the future of plasma use, and more.

Berk, Herbert L.

78

Boundary Plasma Issues in Burning Plasma Science  

E-print Network

Boundary Plasma Issues in Burning Plasma Science C S Pitcher, MIT PSFC Issues present in any impurity production 4. screening of impurities 5. burning plasma experiment? #12;(1) Wide Dispersal) on divertor plate, significant erosion expected above 1.5 MJ m-2 · mitigating factors: - radiation (non

Pitcher, C. S.

79

Boundary Plasma Issues in Burning Plasma Science  

E-print Network

Boundary Plasma Issues in Burning Plasma Science C S Pitcher, MIT PSFC Issues present in any impurity production 4. screening of impurities · why a burning plasma experiment? · BP contribution.06, gives 2 to 6 MJ m-2 (ITER) on divertor plate, significant erosion expected above 1.5 MJ m-2 · mitigating

Pitcher, C. S.

80

Boundary Plasma Issues in Burning Plasma Science  

E-print Network

Boundary Plasma Issues in Burning Plasma Science C S Pitcher, MIT PSFC Issues present in any impurity production 4. screening of impurities 5. burning plasma experiment? #12;(1) Wide Dispersal plate, significant erosion expected above 1.5 MJ m-2 · mitigating factors: - radiation (non-coronal) - P

81

Plasma Polymerization on Metals  

Microsoft Academic Search

An ellipsometric technique is described for accurately measuring the film thickness of plasma-polymerized polymers on metallic substrates. The index of refraction n and absorption index Kof the plasma polymer film can also be studied by ellipsometry. Films of plasma polystyrene and polyepichlorohydrin were deposited on evaporated aluminum substrates and their thickness and optical constants determined. Plasma polystyrene films from 20

P. J. Dynes; D. H. Kaelble

1976-01-01

82

Progress on plasma accelerators  

SciTech Connect

Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

Chen, P.

1986-05-01

83

Thermal plasma processing  

Microsoft Academic Search

A review is given of the fundamental aspects involved in material processing using thermal plasma technology. The description of plasma generating devices covers DC plasma torches, DC transferred arcs, RF inductively coupled plasma torches and hybrid combinations of them. Emphasis is given to the identification of the basic energy coupling mechanism in each case and the principal characteristics of the

Maher I. Boulos

1991-01-01

84

Plasma sweeper. [Patents  

DOEpatents

A device is described for coupling RF power (a plasma sweeper) from RF power introducing means to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the RF power introducing means. Means are described for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

Motley, R.W.; Glanz, J.

1982-10-25

85

Industrial plasmas in academia  

NASA Astrophysics Data System (ADS)

The present review, written at the occasion of the 2014 EPS Innovation award, will give a short overview of the research and development of industrial plasmas within the last 30?years and will also provide a first glimpse into future developments of this important topic of plasma physics and plasma chemistry. In the present contribution, some of the industrial plasmas studied at the CRPP/EPFL at Lausanne are highlighted and their influence on modern plasma physics and also discharge physics is discussed. One of the most important problems is the treatment of large surfaces, such as that used in solar cells, but also in more daily applications, such as the packaging industry. In this contribution, the advantages and disadvantages of some of the most prominent plasmas such as capacitively- and inductively-coupled plasmas are discussed. Electromagnetic problems due to the related radio frequency and its consequences on the plasma reactor performance, and also dust formation due to chemical reactions in plasma, are highlighted. Arcing and parasitic discharges occurring in plasma reactors can lead to plasma reactor damages. Some specific problems, such as the gas supply of a large area reactor, are discussed in more detail. Other topics of interest have been dc discharges such as those used in plasma spraying where thermal plasmas are applied for advanced material processing. Modern plasma diagnostics make it possible to investigate sparks in electrical discharge machining, which surprisingly show properties of weakly-coupled plasmas. Nanosecond dielectric barrier discharge plasmas have been applied to more speculative topics such as applications in aerodynamics and will surely be important in the future for ignition and combustion. Most of the commonly-used plasma sources have been shown to be limited in their performance. Therefore new, more effective plasma sources are urgently required. With the recent development of novel resonant network antennas for new advanced large area or large volume plasma sources, an important step towards high performance plasmas and new fast processes is made.

Hollenstein, Ch; Howling, AA; Guittienne, Ph; Furno, I.

2015-01-01

86

Plasma Physics PART Al: INTRODUCTION TO PLASMA SCIENCE  

E-print Network

Plasma Physics PART Al: INTRODUCTION TO PLASMA SCIENCE I. What is a plasma? 1 II. Plasma fundamentals 3 1. Quasineutrality and Debye length 2. Plasma frequency and acoustic velocity 3. Larmor radius; magnetic buckets Cross section data 21 PART A3: PLASMA SOURCES I IV. Introduction to plasma sources 25 1

Chen, Francis F.

87

Plasma window characterization  

SciTech Connect

Parameters of an arc Ar plasma discharge used as a plasma window with a discharge current of {approx}50 A and a voltage of {approx}58 V are presented. It is shown that this arc discharge allows one to decrease the pressure at the low pressure end of the plasma window almost 380 times using relatively low pumping at the low pressure end of the plasma window. Calculations of the plasma parameters and their spatial distribution using a simple wall-stabilized arc model showed a satisfactory agreement with the experimentally obtained data. It is shown that a significant decrease in gas flow through the plasma window occurs due to the increase in plasma viscosity. An improvement of the plasma window ignition and some of its design aspects are described as well.

Krasik, Ya. E.; Gleizer, S.; Gurovich, V.; Kronhaus, I.; Hershcovitch, A.; Nozar, P.; Taliani, C. [Physics Department, Technion, 32000 Haifa (Israel); Brookhaven National Laboratory, New York 11973-5000 (United States); Istituto per lo Studio dei Materiali Nanostrutturati, 40 129 Bologna (Italy)

2007-03-01

88

Plasma photonic crystal  

Microsoft Academic Search

Plasma photonic crystals are presented in this paper. A plasma photonic crystal can control the propagation of electromagnetic\\u000a waves. Similar to other photonic crystals, the permittivity of a plasma photonic crystal is distributed as periodic arrays.\\u000a The properties of periodic arrays of plasma can broaden the range of frequency and enhance the efficiency of beam-wave interaction.\\u000a In special uses, the

Wei Li; Yong Zhao; Ruizhen Cui; Haitao Zhang

2009-01-01

89

Coalition for Plasma Science  

NSDL National Science Digital Library

Created to increase public understanding of plasma science, this site presents brief papers introducing particular aspects of plasma science and its practical applications, plus an excellent Teachers Guide to Plasma Science Resources (see "Educational Materials"), designed by teachers for teachers and students. The Guide provides annotated links to the best of online plasma-education materials, including classroom-tested materials and K-12 teaching aids. Most of the listings are accompanied by a checklist of the National Science Standards the resource fulfills.

90

Basic plasma physics II  

Microsoft Academic Search

The basic physics of classical ideal plasmas is presented in reviews of recent theoretical and experimental investigations, with an emphasis on nonlinear interactions violating the assumptions of weak turbulence. Topics examined include Kolmogorov spectra, parametric instabilities in magnetoactive plasmas, collapse and self-focusing of Langmuir waves, collective dissipation and transport, spontaneous reconnection of magnetic-field lines in a collisionless plasma, collective-beam\\/plasma interaction,

A. A. Galeev; R. N. Sudan

1984-01-01

91

Plasma Treatment of Polymers  

Microsoft Academic Search

Plasma treatment of polymers encompasses a variety of plasma technologies and polymeric materials for a wide range of applications and dates back to at least the 1960s. In this article we provide a brief review of the United States patent literature on plasma surface modification technologies and a brief review of the scientific literature on investigations of the effects of

Jeremy M. Grace; Louis J. Gerenser

2003-01-01

92

Perspectives on Plasma  

NSDL National Science Digital Library

Originally conceived and launched by consultant and Senior Research Associate Dr. Timothy E. Eastman at the Space Science Institute in Boulder, Colorado, the Perspectives on Plasma Web site represents all aspects of plasma science and technology. Visitors can explore the basics of plasma, its applications, view a photo gallery, and much more.

Eastman, Timothy E.

93

Plasma window characterization  

Microsoft Academic Search

Parameters of an arc Ar plasma discharge used as a plasma window with a discharge current of ~50 A and a voltage of ~58 V are presented. It is shown that this arc discharge allows one to decrease the pressure at the low pressure end of the plasma window almost 380 times using relatively low pumping at the low pressure

Ya. E. Krasik; S. Gleizer; V. Gurovich; I. Kronhaus; A. Hershcovitch; P. Nozar; C. Taliani

2007-01-01

94

Industrial Plasma Antennas  

Microsoft Academic Search

This presentation summarizes an extensive program on plasma antennas. Plasma antennas are just as effective as metal antennas. In addition, they can transmit, receive and reflect lower frequency signals while being transparent to higher frequency signals. When de-energized, they electrically disappear. Plasma noise does not appear to be a problem. New technology that has been developed include a method of

Igor Alexeff

2007-01-01

95

Transient plasma ignition  

Microsoft Academic Search

This paper presents images of transient plasma applied in varied circumstances to fuel ignition and subsequent combustion. The transient plasma occurs during the formative phase of an arc discharge, and persists for ?50 ns. The results demonstrate that transient plasma ignition initiates combustion efficiently, produces excited species distinct from traditional spark ignition, and that for some applications, including reduced delays

Jianbang Liu; Fei Wang; Guoqiang Li; Andras Kuthi; Ephraim J. Gutmark; Paul D. Ronney; Martin A. Gundersen

2005-01-01

96

Mirror plasma apparatus  

Microsoft Academic Search

A mirror plasma apparatus is described which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is

Moir

1978-01-01

97

Mirror plasma apparatus  

Microsoft Academic Search

A mirror plasma apparatus which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is spun with

Moir; Ralph W

1981-01-01

98

Plasma and magnetospheric research  

NASA Technical Reports Server (NTRS)

Research activities on the following topics were summarized: (1) software for the Space Plasma computer Analysis Network (SPAN), (2) plasmaspheric field-aligned temperature gradients, (3) the shift in spacecraft potential as a function of plasma density, (4) plasma flow, (5) the Fabry-Perot interferometer, and (6) the Differential Ion Flux Probe (DIFP).

Comfort, R. H.; Horwitz, J. L.

1984-01-01

99

A reconfigurable plasma antenna  

SciTech Connect

An experiment aimed at investigating the antenna properties of different plasma structures of a plasma column as a reconfigurable plasma antenna, is reported. A 30 cm long plasma column is excited by surface wave, which acts as a plasma antenna. By changing the operating parameters, e.g., working pressure, drive frequency, input power, radius of glass tube, length of plasma column, and argon gas, single plasma antenna (plasma column) can be transformed to multiple small antenna elements (plasma blobs). It is also reported that number, length, and separation between two antenna elements can be controlled by operating parameters. Moreover, experiments are also carried out to study current profile, potential profile, conductivity profile, phase relations, radiation power patterns, etc. of the antenna elements. The effect on directivity with the number of antenna elements is also studied. Findings of the study indicate that entire structure of antenna elements can be treated as a phased array broadside vertical plasma antenna, which produces more directive radiation pattern than the single plasma antenna as well as physical properties and directivity of such antenna can be controlled by operating parameters. The study reveals the advantages of a plasma antenna over the conventional antenna in the sense that different antennas can be formed by tuning the operating parameters.

Kumar, Rajneesh [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Bora, Dhiraj [ITER Organisation, Cadarache 13108 (France)

2010-03-15

100

Plasma & RF Fundamentals  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. One third of modern semiconductor process steps and a variety of other applications employ plasma technology. RF energy is commonly used to generate and maintain a plasma which accelerates chemical processes or provides other desired outcomes such as light emission. This module is the first in a series that builds a knowledge foundation for understanding plasma technology and RF energy. Concepts and principles covered include particle behavior under plasma conditions, changes in electromagnetic wave forms, and related variables that affect RF/plasma applications.

101

Mirror plasma apparatus  

DOEpatents

A mirror plasma apparatus which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is spun with angular velocity great enough to keep the liquid lithium against the first material wall, a blanket plasma preventing the lithium vapor from contaminating the plasma.

Moir, Ralph W. (Livermore, CA)

1981-01-01

102

Plasmas for medicine  

NASA Astrophysics Data System (ADS)

Plasma medicine is an innovative and emerging field combining plasma physics, life science and clinical medicine. In a more general perspective, medical application of physical plasma can be subdivided into two principal approaches. (i) “Indirect” use of plasma-based or plasma-supplemented techniques to treat surfaces, materials or devices to realize specific qualities for subsequent special medical applications, and (ii) application of physical plasma on or in the human (or animal) body to realize therapeutic effects based on direct interaction of plasma with living tissue. The field of plasma applications for the treatment of medical materials or devices is intensively researched and partially well established for several years. However, plasma medicine in the sense of its actual definition as a new field of research focuses on the use of plasma technology in the treatment of living cells, tissues, and organs. Therefore, the aim of the new research field of plasma medicine is the exploitation of a much more differentiated interaction of specific plasma components with specific structural as well as functional elements or functionalities of living cells. This interaction can possibly lead either to stimulation or inhibition of cellular function and be finally used for therapeutic purposes. During recent years a broad spectrum of different plasma sources with various names dedicated for biomedical applications has been reported. So far, research activities were mainly focused on barrier discharges and plasma jets working at atmospheric pressure. Most efforts to realize plasma application directly on or in the human (or animal) body for medical purposes is concentrated on the broad field of dermatology including wound healing, but also includes cancer treatment, endoscopy, or dentistry. Despite the fact that the field of plasma medicine is very young and until now mostly in an empirical stage of development yet, there are first indicators of its enormous economic potential. This ambivalent situation fundamentally requires a responsible use of plasma sources, which are specifically designated for biomedical applications. To enable physicians as well as life scientists to decide whether a given plasma source is really suitable for medical applications or biological experiments, a meaningful and mandatory spectrum of indicators has to be compiled to allow for a basic estimation of the potential of this plasma source.

von Woedtke, Th.; Reuter, S.; Masur, K.; Weltmann, K.-D.

2013-09-01

103

Plasma Biomedicine in Orthopedics  

NASA Astrophysics Data System (ADS)

Various effects of plasmas irradiation on cells, tissues, and biomaterials relevant for orthopedic applications have been examined. For direct application of plasmas to living cells or tissues, dielectric barrier discharges (DBDs) with helium flows into ambient air were used. For biomaterial processing, on the other hand, either helium DBDs mentioned above or low-pressure discharges generated in a chamber were used. In this presentation, plasma effects on cell proliferation and plasma treatment for artificial bones will be discussed. First, the conditions for enhanced cell proliferation in vitro by plasma applications have been examined. The discharge conditions for cell proliferation depend sensitively on cell types. Since cell proliferation can be enhanced even when the cells are cultured in a plasma pre-treated medium, long-life reactive species generated in the medium by plasma application or large molecules (such as proteins) in the medium modified by the plasma are likely to be the cause of cell proliferation. It has been found that there is strong correlation between (organic) hydroperoxide generation and cell proliferation. Second, effects of plasma-treated artificial bones made of porous hydroxyapatite (HA) have been examined in vitro and vivo. It has been found that plasma treatment increases hydrophilicity of the surfaces of microscopic inner pores, which directly or indirectly promotes differentiation of mesenchymal stem cells introduced into the pores and therefore causes faster bone growth. The work has been performed in collaboration with Prof. H. Yoshikawa and his group members at the School of Medicine, Osaka University.

Hamaguchi, Satsohi

2012-10-01

104

Plasma abatement of perfluorocompounds in inductively coupled plasma reactors  

E-print Network

Plasma abatement of perfluorocompounds in inductively coupled plasma reactors Xudong ``Peter'' Xu PFCs , gases which have large global warming potentials, are widely used in plasma processing, the effluents from plasma tools using these gases typically have large mole fractions of PFCs. The use of plasma

Kushner, Mark

105

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala  

E-print Network

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala Department plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having

Kushner, Mark

106

Plasma-Therm Workshop: Fundamentals of Plasma Processing (Etching & Deposition)  

E-print Network

Plasma-Therm Workshop: Fundamentals of Plasma Processing (Etching & Deposition) Nanofabrication The workshop will focus on the fundamentals of plasma etching and deposition. Lectures will include an introduction to vacuum technology, the basics of plasma and plasma reactors and an overview of mechanisms

Martin, Jan M.L.

107

What is a plasma?  

SciTech Connect

This introduction will define the plasma fourth state of matter, where we find plasmas on earth and beyond, and why they are useful. There are applications to many consumer items, fusion energy, scientific devices, satellite communications, semiconductor processing, spacecraft propulsion, and more. Since 99% of our observable universe is ionized gas, plasma physics determines many important features of astrophysics, space physics, and magnetosphere physics in our solar system. We describe some plasma characteristics, examples in nature, some useful applications, how to create plasmas. A brief introduction to the theoretical framework includes the connection between kinetic and fluid descriptions, quasi neutrality, Debye shielding, ambipolar electric fields, some plasma waves. Hands-on demonstrations follow. More complete explanations will follow next week.

Intrator, Thomas P. [Los Alamos National Laboratory

2012-08-30

108

Plasma Membrane ATPases  

Microsoft Academic Search

\\u000a The plasma membrane separates the cellular contents from the surrounding environment. Nutrients must enter through the plasma\\u000a membrane in order to reach the cell interior, and toxic metabolites and several ions leave the cell by traveling across the\\u000a same barrier. Biological pumps in the plasma membrane include ABC transporters, vacuolar (V-type) H+ pumps, and P-type pumps. These pumps all utilize

Michael G. Palmgren; Lone Bækgaard; Rosa López-Marqués; Anja Fuglsang

109

Space plasma physics research  

NASA Technical Reports Server (NTRS)

During the course of this grant, work was performed on a variety of topics and there were a number of significant accomplishments. A summary of these accomplishments is included. The topics studied include empirical model data base, data reduction for archiving, semikinetic modeling of low energy plasma in the inner terrestrial magnetosphere and ionosphere, O(+) outflows, equatorial plasma trough, and plasma wave ray-tracing studies. A list of publications and presentations which have resulted from this research is also included.

Comfort, Richard H.; Horwitz, James L.

1993-01-01

110

Plasma Membrane Protein Trafficking  

Microsoft Academic Search

\\u000a The plasma membrane is the interface between the cytosol and the external environment. The proteins that reside and function\\u000a on the plasma membrane regulate the cellular entrance and exit of bioactive molecules, actuate signaling cascades in response\\u000a to external stimuli, and potentiate interactions between cells. The presence and abundance of proteins on the plasma membrane\\u000a is regulated by anterograde and

Wendy Ann Peer

111

Chiral plasma instabilities.  

PubMed

We study the collective modes in relativistic electromagnetic or quark-gluon plasmas with an asymmetry between left- and right-handed chiral fermions, based on the recently formulated kinetic theory with Berry curvature corrections. We find that there exists an unstable mode, signaling the presence of a plasma instability. We argue the fate of this "chiral plasma instability" including the effect of collisions, and briefly discuss its relevance in heavy ion collisions and compact stars. PMID:23952387

Akamatsu, Yukinao; Yamamoto, Naoki

2013-08-01

112

Princeton Plasma Physics Laboratory  

SciTech Connect

This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

Not Available

1990-01-01

113

Planetary plasma waves  

NASA Technical Reports Server (NTRS)

The primary types of plasma waves observed in the vicinity of the planets Venus, Mars, Earth, Jupiter, Saturn, Uranus, and Neptune are described. The observations are organized according to the various types of plasma waves observed, ordered according to decreasing distance from the planet, starting from the sunward side of the planet, and ending in the region near the closest approach. The plasma waves observed include: electron plasma oscillations and ion acoustic waves; trapped continuum radiation; electron cyclotron and upper hybrid waves; whistler-mode emissions; electrostatic ion cyclotron waves; and electromagnetic ion cyclotron waves.

Gurnett, Donald A.

1993-01-01

114

Plasma Adiabatic Lapse Rate  

NASA Astrophysics Data System (ADS)

The plasma analog of an adiabatic lapse rate (or temperature variation with height) in atmospheric physics is obtained. A new source of plasma temperature gradient in a binary ion species mixture is found that is proportional to the concentration gradient ??? and difference in average ionization states Z2-Z1. Application to inertial-confinement-fusion implosions indicates a potentially strong effect in plastic (CH) ablators that is not modeled with mainline (single-fluid) simulations. An associated plasma thermodiffusion coefficient is derived, and charge-state diffusion in a single-species plasma is also predicted.

Amendt, Peter; Bellei, Claudio; Wilks, Scott

2012-08-01

115

Plasma processing of biomaterials.  

PubMed

Surface properties of biomaterials can easily be modified by glow-discharge plasma processing for very diverse biomedical applications. Activated carbon granules can be coated with a very thin polymeric membrane by plasma polymerization to improve their blood compatibilities without changing their adsorption capabilities. The problems associated with the microporous polypropylene oxygenator membranes can be eliminated by coating with a nonporous thin polymeric film in a glow-discharge reactor. Cell attachment and growth on polystyrene microcarriers can significantly be increased by alkylamine plasma treatment. Physical and chemical properties of polyurethane biomaterials can be tailor-made by plasma modification. PMID:1463701

Piskin, E

1992-01-01

116

Pilot Plasma Engine  

NASA Technical Reports Server (NTRS)

The Pilot Plasma Engine. This traveling wave accelerator, being operated by Raymond W. Plamer of the Lewis Electromagnetic Propulsion Division, uses an alternating current power supply. The AC feature avoids the life limitations of direct current accelerators where electrode parts rapidly deteriorate from touching the plasma. The traveling wave accelerator works like its name. A neutral plasma of electrons and ions is produced in the source at the left. This plasma moves to the right and is accelerated by a moving magnetic field in the four black coils. Such acceleration produces thrust, perhaps enough to propel a future spacecraft beyond the Moon.

1961-01-01

117

Plasma Processing Of Hydrocarbon  

SciTech Connect

The Idaho National Laboratory (INL) developed several patented plasma technologies for hydrocarbon processing. The INL patents include nonthermal and thermal plasma technologies for direct natural gas to liquid conversion, upgrading low value heavy oil to synthetic light crude, and to convert refinery bottom heavy streams directly to transportation fuel products. Proof of concepts has been demonstrated with bench scale plasma processes and systems to convert heavy and light hydrocarbons to higher market value products. This paper provides an overview of three selected INL patented plasma technologies for hydrocarbon conversion or upgrade.

Grandy, Jon D; Peter C. Kong; Brent A. Detering; Larry D. Zuck

2007-05-01

118

Thermalization and plasma instabilities  

E-print Network

I review recent analytical and numerical advances in the study of non-equilibrium quark-gluon plasma physics. I concentrate on studies of the dynamics of plasmas which are locally anisotropic in momentum space. In contrast to locally isotropic plasmas such anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse (chromo)-magnetic fields at short times. Parametrically the instabilities provide the fastest method for generation of soft background fields and dominate the short-time dynamics of the system.

Michael Strickland

2006-08-15

119

Plasma deposition method and apparatus  

Microsoft Academic Search

A plasma deposition apparatus comprising a plasma formation chamber into which a gas is introduced to produce plasma, a specimen chamber in which a specimen table is disposed for placing thereon a speciment substrate on which a thin film is to be formed, a plasma extraction window interposed between the plasma formation chamber and the specimen chamber, a target which

S. Matsuo; T. Ono

1985-01-01

120

PLASMA PHYSICS PPPL UC Davis  

E-print Network

PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis, 2006 Hyatt Regency, Dallas, TX #12;PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis Two spatial positions Outboard Launch Inboard Launch #12;PRINCETON PLASMA

121

Laboratory Dipole Plasma Physics  

NASA Astrophysics Data System (ADS)

Modern laboratory studies of plasma confined by a strong dipole magnet originated twenty years ago when it was learned that planetary magnetospheres have centrally-peaked plasma pressure profiles that form naturally when solar wind drives plasma circulation and heating. Unlike other internal rings devices, like spherators and octupoles, the magnetic flux tubes of the dipole field expand rapidly with radius. Unlike plasma confinement devices that obtain stability from magnetic shear and average good curvature, like tokamaks and levitrons, the dipole-confined plasma obtains stability from plasma compressibility. These two geometric characteristics of the dipole field have profound consequences: (i) plasma can be stable with local beta exceeding unity, (ii) fluctuations can drive either heat or particles inward to create stationary profiles that are strongly peaked, and (iii) the confinement of particles and energy can decouple. During the past decade, several laboratory dipole experiments and modeling efforts have lead to new understanding of interchange, centrifugal and entropy modes, nonlinear gyrokinetics, and plasma transport. Two devices, the LDX experiment at MIT and RT-1 at the University of Tokyo, operate with levitated superconducting dipole magnets. With a levitated dipole, not only is very high-beta plasma confined in steady state but, also, levitation produces high-temperature at low input power and demonstrates that toroidal magnetic confinement of plasma does not require a toroidal field. Modeling has explained many of the processes operative in these experiments, including the observation of a strong inward particle pinch. Turbulent low-frequency fluctuations in dipole confined plasma cause adiabatic transport and form a fundamental linkage between the radial variation of flux-tube volume and the centrally peaked density and pressure profiles.

Kesner, Jay

2011-11-01

122

Measuring the plasma density of a ferroelectric plasma source in an expanding plasma  

E-print Network

Measuring the plasma density of a ferroelectric plasma source in an expanding plasma A. Dunaevsky and N. J. Fisch Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements

123

Partially ionized plasmas, including the Third Symposium on Uranium Plasmas  

NASA Technical Reports Server (NTRS)

Fundamentals of both electrically and fission generated plasmas are discussed. Research in gaseous fuel reactors using uranium hexafluoride is described and other partially ionized plasma applications are discussed.

Krishnan, M.

1976-01-01

124

Plasma sheet boundary layer  

Microsoft Academic Search

The plasma sheet boundary layer is a temporally variable transition region located between the magnetotail lobes and the central plasma sheet. We have made a survey of these regions by using particle spectra and three-dimensional velocity-space distributions sampled by the ISEE 1 LEPEDEA. Ion composition measurements obtained by the Lockhead ion mass spectrometers indicate that ionospheric ions play a crucial

T. E. Eastman; L. A. Frank; W.K. Peterson; W. Lennartsson

1984-01-01

125

Broadband plasma absorber  

Microsoft Academic Search

Summary form only given, as follows. A tenuous plasma generated in a background gas at atmospheric pressure is highly collisional. The cold collisional dispersion relation was used to model electromagnetic effects. For a plasma generated by a point source such as an ultraviolet flash lamp the electron number density decreases as a function of distance from the source. An Epstein

R. J. Vidmar

1990-01-01

126

80 Years of Plasma  

Microsoft Academic Search

Irving Langmuir proposed the term 'plasma' in a paper in 1928 (Proc. Natl Acad. Sci. USA14 627–637) to describe a 'region containing balanced charges of ions and electrons'. There does not appear to be any record of the thinking behind this proposal, so it is difficult to be definitive. One idea is that since the Greek word 'plasma' was used

2009-01-01

127

Magnetic Reconnection in Plasmas  

Microsoft Academic Search

This book provides a comprehensive introduction to the theory of magnetic field line reconnection, now a major subject in plasma physics. Biskamp focuses on the various reconnection mechanisms dominating magnetic processes under the different plasma conditions encountered in astrophysical systems and in laboratory fusion devices. The book consists of two major parts: the first deals with the classical resistive approach,

Dieter Biskamp

2000-01-01

128

Compact plasma accelerator device  

Microsoft Academic Search

A compact plasma accelerator concept based on plasma production at a magnetic cusp was designed and fabricated. Plume and discharge characteristics of the device were documented using a Faraday probe and a retarding potential analyzer. The discharge current variations with increasing discharge voltage were nonlinear with the discharge current increasing rapidly with voltage. The device demonstrated the capability of generating

John E. Foster

2002-01-01

129

Madison Plasma Dynamo Experiment  

NASA Astrophysics Data System (ADS)

The Madison Plasma Dynamo Experiment (MPDX) is investigating the self-generation of magnetic fields and related processes in a large, weakly magnetized, fast flowing, and hot (conducting) plasma. The dynamo re-creates conditions highly similar to many astrophysical plasmas. Stars and other planets have dynamos, and so do galaxies and clusters of galaxies, which makes it extremely crucial for researchers in the field to carry out experiments in this previously uninvestigated plasma regime, which will help for the development of a comprehensive theory of how magnetic fields are generated in planets, the Sun and other stars. MPDX is a laboratory astrophysical experiment where 200,000-degree Fahrenheit plasma is confined within a three-meter diameter spherical aluminum vacuum chamber with the help of multiple tracks of cusp magnets covering the inside shell. The dynamo utilizes six robotic insertion sweep probes that are programmed to find any point inside the sphere by given radial and angular coordinates. This innovative mechanical system allows us to take measurements of the state variables in key points in the plasma flow and to better investigate its cosmic-like plasma behavior. The probes are able to autonomously calculate coordinate transformations, move in a two dimensional plane, and return information about their relative position. This makes them an extremely useful, highly accurate, and easily controlled tool for plasma analysis.

Kostadinova, Evdokiya; Forest, C.; Cooper, C.; Coquerel, M.

2014-01-01

130

Diamagnetism of rotating plasma  

SciTech Connect

Diamagnetism and magnetic measurements of a supersonically rotating plasma in a shaped magnetic field demonstrate confinement of plasma pressure along the magnetic field resulting from centrifugal force. The Grad-Shafranov equation of ideal magnetohydrodynamic force balance, including supersonic rotation, is solved to confirm that the predicted angular velocity is in agreement with spectroscopic measurements of the Doppler shifts.

Young, W. C.; Hassam, A. B.; Romero-Talamas, C. A.; Ellis, R. F.; Teodorescu, C. [IREAP, University of Maryland, College Park, Maryland 20742 (United States)

2011-11-15

131

Plasma electrolysis for surface engineering  

Microsoft Academic Search

This paper overviews the relatively new surface engineering discipline of plasma electrolysis, the main derivative of this being plasma electrolytic deposition (PED), which includes techniques such as plasma electrolytic oxidation (PEO) and plasma electrolytic saturation (PES) processes such as plasma electrolytic nitriding\\/carburizing (PEN\\/PEC). In PED technology, spark or arc plasma micro-discharges in an aqueous solution are utilised to ionise gaseous

A. L. Yerokhin; X. Nie; A. Leyland; A. Matthews; S. J. Dowey

1999-01-01

132

Solar system plasma waves  

NASA Technical Reports Server (NTRS)

An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

Gurnett, Donald A.

1995-01-01

133

Plasma opening switch  

DOEpatents

A command triggered plasma opening switch assembly using an amplification stage. The assembly surrounds a coaxial transmission line and has a main plasma opening switch (POS) close to the load and a trigger POS upstream from the main POS. The trigger POS establishes two different current pathways through the assembly depended on whether it has received a trigger current pulse. The initial pathway has both POS's with plasma between their anodes and cathodes to form a short across the transmission line and isolating the load. The final current pathway is formed when the trigger POS receives a trigger current pulse which energizes its fast coil to push the conductive plasma out from between its anode and cathode, allowing the main transmission line current to pass to the fast coil of the main POS, thus pushing its plasma out the way so as to establish a direct current pathway to the load.

Savage, Mark E. (Albuquerque, NM); Mendel, Jr., Clifford W. (Albuquerque, NM)

2001-01-01

134

PLASMA ENGINEERING. PART III. APPLICATIONS OF PLASMA  

Microsoft Academic Search

Practical applications of plasma are studied and used in controlled ; thermonuclear fusion experiments, magnetohydrodynamic and thermionic power ; conversion, spacecraft propulsion, and electronics. Specific examples are given ; for each of the fields covered above. Specific electronic applications are ; microwave traveling-wave amplifiers, backward-wave oscillators, uhf parametric ; amplifiers, phase detectors, harmonic amplifiers, mixers, and switches. Other ; devices

M. F. ed

1961-01-01

135

Plasma-surface modification of biomaterials  

Microsoft Academic Search

Plasma-surface modification (PSM) is an effective and economical surface treatment technique for many materials and of growing interests in biomedical engineering. This article reviews the various common plasma techniques and experimental methods as applied to biomedical materials research, such as plasma sputtering and etching, plasma implantation, plasma deposition, plasma polymerization, laser plasma deposition, plasma spraying, and so on. The unique

P. K. Chu; J. Y. Chen; L. P. Wang; N. Huang

2002-01-01

136

CHAPTER 1. COLLECTIVE PLASMA PHENOMENA 1 Collective Plasma  

E-print Network

CHAPTER 1. COLLECTIVE PLASMA PHENOMENA 1 Chapter 1 Collective Plasma Phenomena The properties of a medium are determined by the microscopic processes in it. In a plasma the microscopic processes is actually limited to a distance of order the Debye length in a plasma. On length scales longer than

Callen, James D.

137

Undriven periodic plasma oscillation in electron cyclotron resonance Ar plasma  

Microsoft Academic Search

We report experimental observation of periodic oscillation in a steady state electron cyclotron resonance argon plasma that is not driven by extra periodic forces. We interpret the oscillation according to the predator-prey model, which is a nonlinear plasma-neutral coupling in the plasma production region. The oscillation is observed in a narrow plasma parameter window and is evidence for neutral density

Pyung-Woo Lee; Sang-Won Lee; Hong-Young Chang

1996-01-01

138

BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas  

Microsoft Academic Search

The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is

M. Brambilla

1998-01-01

139

Double glow plasma surface alloying and plasma nitriding  

Microsoft Academic Search

Based on plasma nitriding technique, Double Glow Plasma Surface Alloying Technology (DG Technique) was developed in 1980. This technique breaks the restriction of traditional plasma nitriding and successfully applies solid alloying elements, such as Ni, Cr, W, Mo, Ti, Al, Nb et al., to realize plasma surface alloying. Numerous experiment results concerning the DG technique have demonstrated that various alloys

Z. Xu; X. Liu; P. Zhang; Y. Zhang; G. Zhang; Z. He

2007-01-01

140

Plasma and magnetospheric research  

NASA Technical Reports Server (NTRS)

Methods employed in the analysis of plasmas and the magnetosphere are examined. Computer programs which generate distribution functions are used in the analysis of charging phenomena and non maxwell plasmas in terms of density and average energy. An analytical model for spin curve analysis is presented. A program for the analysis of the differential ion flux probe on the space shuttle mission is complete. Satellite data analysis for ion heating, plasma flows in the polar cap, polar wind flow, and density and temperature profiles for several plasmasphere transits are included.

Comfort, R. H.; Horwitz, J. L.

1984-01-01

141

Cortisol Binding in Uremic Plasma  

Microsoft Academic Search

We measured cortisol binding to albumin in uremic plasma during a study to see if increased morning plasma free cortisol values, reported previously in chronic renal failure patients, could be explained by binding abnormalities of plasma proteins. Cortisol binding was measured in plasma from chronic renal failure patients and compared to values in normal controls. The unbound and albumin-bound fractions

Paul M. Rosman; Renrick Benn; Martin Kay; Eleanor Z. Wallace

1984-01-01

142

Theory of plasma antenna windowing  

Microsoft Academic Search

Summary form only given. This paper sets forth a detailed numerical analysis of the performance of a reconfigurable antenna comprised of a linear omni-directional antenna surrounded by a cylindrical shell of conducting plasma. The plasma shield consists of a series of tubes containing a gas, which upon electrification, forms a plasma (in practice fluorescent light bulbs are used). The plasma

T. Anderson; I. Alexeff

2004-01-01

143

Plasma surface modification of polymers  

NASA Technical Reports Server (NTRS)

Thin plasma polymerization films are discussed from the viewpoint of simplicity in production stages. The application of selective, absorbent films and films used in selective permeability was tested. The types of surface modification of polymers discussed are: (1) plasma etching, (2) surface coating by plasma polymerized thin films, and (3) plasma activation surface graft polymerization.

Hirotsu, T.

1980-01-01

144

Nanowire coating by plasma processing  

Microsoft Academic Search

We present a plasma-based method for the deposition of hydrogenated amorphous carbon films on metallic nanowires. Gold nanowires in mixture with silica nanospheres are introduced in a capacitively coupled radio-frequency Ar plasma where they become trapped to form a dusty plasma. Isopropanol is introduced in the plasma where it reacts to produce an amorphous film of hydrogenated carbon that deposits

Jin Cao; Themis Matsoukas

2005-01-01

145

Michigan Institute for Plasma Science  

E-print Network

Technology. His research interests include thermal plasma processing of materials and plasma spray coatings Michigan Institute for Plasma Science and Engineering Seminar Dynamics of Droplet Impact of a ceramic or superalloy is often the best way to protect and extend the lives of such components. Plasma

Shyy, Wei

146

Atmospheric pressure plasmas: A review  

Microsoft Academic Search

This article attempts to give an overview of atmospheric plasma sources and their applications. The aim is to introduce, in a first part, the main scientific background concerning plasmas as well as the different atmospheric plasma sources (description, working principle). The second part focuses on the various applications of the atmospheric plasma technologies, mainly in the field of surface treatments.Thus

Claire Tendero; Christelle Tixier; Pascal Tristant; Jean Desmaison; Philippe Leprince

2006-01-01

147

Plasma-based accelerator structures  

SciTech Connect

Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

Schroeder, Carl B.

1999-12-01

148

Princeton Plasma Physics Laboratory  

NSDL National Science Digital Library

The Princeton Plasma Physics Laboratory: the Fusion Laboratories facilities and mission, including the recent tokamak experiments which resulted in the production of more than 9 million watts of thermonuclear energy.

149

The plasma state  

NSDL National Science Digital Library

This segment of a tutorial about plasma--the main state of matter in space--deals with what plasma is and how it is formed. Background information on electric and magnetic fields is also included because plasmas interact with these fields. Enlargeable graphics and an interactive game about the four states of matter complement the segment's four pages of text. In the game, students direct falling objects, such as rocks, lightning, and gasoline, into the appropriate state-of-matter slot. The segment also explains why plasma is so rare on Earth and so abundant in space. A concluding vignette explores Hannes Alfven's ongoing influence on space physics. Alfven was a twentieth-century Nobel laureate. Copyright 2005 Eisenhower National Clearinghouse

Space Science Institute

2005-01-01

150

Simulation of Fusion Plasmas  

ScienceCinema

The upcoming ITER experiment (www.iter.org) represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the ?burning plasma? regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

Chris Holland

2010-01-08

151

Simulation of Fusion Plasmas  

SciTech Connect

The upcoming ITER experiment represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the 'burning plasma' regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

Holland, Chris (UC San Diego) [UC San Diego

2008-12-17

152

Simulation of Fusion Plasmas  

SciTech Connect

The upcoming ITER experiment (www.iter.org) represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the “burning plasma” regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

Chris Holland

2008-12-17

153

Plasma Cell Disorders  

MedlinePLUS

... Resources for Help and Information The One-Page Merck Manual of Health Medical Terms Conversion Tables Manuals available ... Significance (MGUS) Multiple Myeloma Macroglobulinemia Heavy Chain Diseases Merck Manual > Patients & Caregivers > Blood Disorders > Plasma Cell Disorders 4 ...

154

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, Donald E. (Los Alamos, NM)

1984-01-01

155

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, D.E.

1982-07-02

156

Plasma jet effects on the ionospheric plasma  

NASA Technical Reports Server (NTRS)

Heavy ion beams were injected into the ionospheric plasma (experiments ARCS 1 and ARCS 2). In ARCS 1, operation of a 25eV argon ion source, mounted on a plasma diagnostic payload, produced an accelerated electron population; broadband electric field turbulence; large, spin synchronized electric field perturbations; and depletions of thermal ions. In ARCS 2, the ion source was deployed upward along the local magnetic field direction away from the diagnostic payload, and observed effects are contained within several meters of the ion source. However, enhanced wave levels near the LHR frequency are observed at distances up to 1 km, as are the injected ions themselves. A measurement of the dominant wavelength of the enhanced waves is consistent with an inference based upon the accelerated electron population seen in ARCS 1. This electron population is not evident during ARCS 2.

Moore, T. E.; Arnoldy, R. L.; Cahill, L. J.; Kintner, P. M.

1983-01-01

157

Plasmas in Saturn's magnetosphere  

Microsoft Academic Search

The solar wind plasma analyzer on board Pioneer 11 proves first observations of low-energy positive ions in the magnetosphere of Saturn. Measurable intensities of ions within the energy per unit charge (E\\/Q) range 100 eV to 8 eV are present over the planetocentric radial distance range approx.4--16 R\\/sub s\\/ in the day-side magnetosphere. The plasmas are found to be rigidly

L. A. Frank; B. G. Burek; K. L. Ackerson; J. H. Wolfe; J. D. Mihalov

1980-01-01

158

Plasma Screen Floating Mount  

SciTech Connect

A mounting system for a flat display screen, particularly a plasma display screen, suspends the screen separately in each of the x-, y- and z-directions. A series of frames located by linear bearings and isolated by springs and dampers allows separate controlled movement in each axis. The system enables the use of relatively larger display screens in vehicles in which plasma screen are subject to damage from vibration.

Eakle, Robert F. (New Ellenton, SC); Pak, Donald J. (Martine, GA)

2004-10-26

159

Waves in Space Plasmas  

Microsoft Academic Search

Although low-frequency radio waves of extra-terrestrial origin were known over a century ago, it wasn't until the beginning of the space era fifty years ago that the origin of these waves could be adequately investigated. Since then spacecraft-borne instruments have shown that space plasmas exhibit an almost bewildering variety of wave phenomena, sometimes referred to as the plasma wave zoo.

Donald Gurnett

2008-01-01

160

Plasma interaction with microbes  

Microsoft Academic Search

The germicidal effects of a non-equilibrium atmospheric pressure plasma generated by a novel resistive barrier discharge on representatives of the two classes of bacteria (Gram-negative and Gram-positive) are discussed. The plasma exposure, while being lethal to both bacterial classes, also produced gross structural damage in the Gram-negative E. coli while none was observed in the more structurally robust Gram-positive Bacillus

M. Laroussi; D. A. Mendis; M. Rosenberg

2003-01-01

161

Plasma electron analysis: Voyager plasma science experiment  

NASA Technical Reports Server (NTRS)

The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.

Sittler, E. C., Jr.

1983-01-01

162

Plasma tomography systems for industrial plasma tools  

SciTech Connect

Addressing the geometry constraints that have inhibited the use of optical emission based tomography systems on industrial plasma tools, the University of Michigan has developed a plasma tomography system which uses optical emission spectroscopy (OES) technology and can be operated from a relatively small window compared to the standard Abel geometry previously used by many authors; this change in geometry may make the technique more applicable to industrial plasma tools, which have relatively small windows. The light collection system is based on a rotating point sensor at the surface of the window and reconstructs emissivity from thin wedges of vertically collimated light. This design not only allows for use in small window geometries, but also collects more light than the traditional parallel rays arrangement, thereby providing a better signal to noise ratio for the measurement. This current sensor`s design, results, and a comparison with findings based on Langmuir probe and other OES methods will be presented. Plans for future sensor improvements to allow for multipeak analysis and compatibility with more confining geometries will also be presented.

Shannon, S.C.; Pollack, S.; Holloway, J.P.; Brake, M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences

1996-12-31

163

Plasma contactor research - 1991  

NASA Technical Reports Server (NTRS)

A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research.

Buchholtz, Brett; Williams, John D.; Wilbur, Paul J.

1992-01-01

164

Plasma scattering of electromagnetic radiation  

Microsoft Academic Search

The scattered power spectrum is considered along with aspects of incoherent scattering, constraints on scattering experiments, optical systems, the theory concerning the scattered spectrum for a low-temperature plasma, and questions of scattering from a low-temperature stable plasma. Attention is also given to scattering from a magnetized plasma, scattering from a high-temperature plasma, scattering from unstable plasmas, the kinetic theory of

J. Sheffield

1975-01-01

165

Plasma plume propagation characteristics of pulsed radio frequency plasma jet  

SciTech Connect

A 4 cm long helium cold atmospheric pressure plasma jet with pulsed radio frequency (rf) excitation was obtained by a copper electrode inside a quartz tube. The plasma bullet propagation characteristics common to the microseconds direct current pulse and kilohertz plasma jet is not observed in this case. The space-, time-, and wavelength-resolved optical emission profiles suggest the pulsed rf plasma channel out of the tube was strengthened by ions and metastables with longer life time than the rf period, and the plasma propagation was actually an illumination of the plasma channel caused by energetic electrons accelerated along the channel.

Liu, J. H.; Liu, X. Y.; Hu, K.; Liu, D. W.; Lu, X. P. [Advanced Electromagnetic Engineering and Technology Laboratory, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

2011-04-11

166

DC Dusty Plasma Simulation  

NASA Astrophysics Data System (ADS)

We describe the development of simulations of a complex plasma-composed of a low-temperature plasma and dust grains-to be used in comparing the electron, dust and ion interactions in the simulations to the Dusty Plasma eXperiments (DPX) being conducted at the Princeton Plasma Physics Laboratory (PPPL). There are two DPX experiments: a ground-based experiment used to investigate the spontaneous formation of dust acoustic waves and the flight-based experiment that has gone on three flights on NASA's ``Weightless Wonder.'' The latter experiment has recently been outfitted with a thermal heater used to generate a thermal gradient in the device. This thermal gradient produces a thermophoretic force on the charged dust grains that counteracts gravity, thereby simulating the flights on the ``Weightless Wonder.'' We have modified the XOOPIC code (J.P. Verboncoeur et al., Comp. Phys. Comm., 87, May 11, 1995, pp. 199-211) to simulate the DPX apparatuses by adding a new dielectric particle species and creating additional modules to handle dust by allowing variable charge and deposition currents during the collision phase of the code. Using these simulations, plasma dynamics and dust cloud characteristics are compared with experimental results (C. Udemgba, these proceedings).

Blumenkopf, Joshua; Wissel, Stephanie; Zwicker, Andrew

2011-11-01

167

Archimedes Plasma Mass Filter  

NASA Astrophysics Data System (ADS)

The Archimedes' Plasma Mass Filter is a novel plasma-based mass separation device. The basic physics of the Filter concept and a description of its primary application for nuclear waste separation at Hanford will be presented along with initial experimental results from a Demo device. The Demo is a 3.89 m long cylindrical device with a plasma radius of 0.4 m and an axial magnetic field up to 1600 Gauss. The plasma is produced by helicon waves launched by two four-strap antennas placed symmetrically either side of a central source region. One strap of each antenna is powered by one of four phase controlled 1 MW transmitters operating in the frequency range from 3.9 - 26 MHz. Each end of the device has ten concentric ring electrodes used to apply an electric field to rotate the plasma. Application of a parabolic voltage profile results in a rigid body rotation. Heavy ions above the cut-off mass number are extracted radially and collected by a heavy ion collector surrounding the source injection region while light ions are collected at the ends of the cylinder. Initial experiments will use noble gas and trace metals to demonstrate separation before attempting to operate with complex waste characteristic of Hanford.

Freeman, Richard; Agnew, Steve; Anderegg, Francois; Cluggish, Brian; Gilleland, John; Isler, Ralph; Litvak, Andrei; Miller, Robert; O'Neill, Ray; Ohkawa, Tihiro; Pronko, Steve; Putvinski, Sergei; Sevier, Leigh; Sibley, Andy; Umstadter, Karl; Wade, Terry; Winslow, David

2003-12-01

168

Anatomy of plasma turbulence  

NASA Astrophysics Data System (ADS)

Turbulence is a state of fluids and plasma where nonlinear interactions including cascades to finer scales take place to generate chaotic structure and dynamics. However, turbulence could generate global structures, such as dynamo magnetic field, zonal flows, transport barriers, enhanced transport and quenching transport. Therefore, in turbulence, multiscale phenomena coevolve in space and time, and the character of plasma turbulence has been investigated in the laboratory as a modern and historical scientific mystery. Here, we report anatomical features of the plasma turbulence in the wavenumber-frequency domain by using nonlinear spectral analysis including the bi-spectrum. First, the formation of the plasma turbulence can be regarded as a result of nonlinear interaction of a small number of irreducible parent modes that satisfy the linear dispersion relation. Second, the highlighted finding here, is the first identification of a streamer (state of bunching of drift waves) that should degrade the quality of plasmas for magnetic confinement fusion. The streamer is a poloidally localized, radially elongated global structure that lives longer than the characteristic turbulence correlation time, and our results reveal that the streamer is produced as the result of the nonlinear condensation, or nonlinear phase locking of the major triplet modes.

Yamada, Takuma; Itoh, Sanae-I.; Maruta, Takashi; Kasuya, Naohiro; Nagashima, Yoshihiko; Shinohara, Shunjiro; Terasaka, Kenichiro; Yagi, Masatoshi; Inagaki, Shigeru; Kawai, Yoshinobu; Fujisawa, Akihide; Itoh, Kimitaka

2008-09-01

169

Plasma jet ignition device  

DOEpatents

An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

McIlwain, Michael E. (Franklin, MA); Grant, Jonathan F. (Wayland, MA); Golenko, Zsolt (North Reading, MA); Wittstein, Alan D. (Fairfield, CT)

1985-01-15

170

Plasma effects on subcellular structures  

SciTech Connect

Atmospheric pressure helium plasma treated human hepatocytes exhibit distinctive zones of necrotic and live cells separated by a void. We propose that plasma induced necrosis is attributed to plasma species such as oxygen radicals, charged particles, metastables and/or severe disruption of charged cytoskeletal proteins. Interestingly, uncharged cytoskeletal intermediate filaments are only minimally disturbed by plasma, elucidating the possibility of plasma induced electrostatic effects selectively destroying charged proteins. These bona fide plasma effects, which inflict alterations in specific subcellular structures leading to necrosis and cellular detachment, were not observed by application of helium flow or electric field alone.

Gweon, Bomi; Kim, Dan Bee; Jung, Heesoo; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Daeyeon [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Shin, Jennifer H. [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2010-03-08

171

Partial pressure analysis of plasmas  

SciTech Connect

The application of partial pressure analysis for plasma diagnostic measurements is reviewed. A comparison is made between the techniques of plasma flux analysis and partial pressure analysis for mass spectrometry of plasmas. Emphasis is given to the application of quadrupole mass spectrometers (QMS). The interface problems associated with the coupling of a QMS to a plasma device are discussed including: differential-pumping requirements, electromagnetic interferences from the plasma environment, the detection of surface-active species, ion source interactions, and calibration procedures. Example measurements are presented from process monitoring of glow discharge plasmas which are useful for cleaning and conditioning vacuum vessels.

Dylla, H.F.

1984-11-01

172

Large area plasma source  

NASA Technical Reports Server (NTRS)

An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

Foster, John (Inventor); Patterson, Michael (Inventor)

2008-01-01

173

Glossary of Plasma Physics  

NSDL National Science Digital Library

From the Princeton Plasma Physics Laboratory's FusEdWeb: Fusion Energy Educational Web Site, this glossary of plasma physics "seeks to provide plain-language definitions of over 3600 frequently used technical terms in Plasma Physics (all areas) and Fusion Energy Research." The glossary is intended to help facilitate discussion "between experts and non-experts, and even between experts in different subfields." Users may search, submit new terms for review by editors, or browse alphabetically for terms in fields including scientific vocabulary, names of research facilities, experimental machines and devices used, names of researchers, key mathematical symbols, and acronyms. Over a thousand of these terms are fully defined on-site, and references are provided for looking up most of the remaining terms.

174

Pulsed Plasma Accelerator Modeling  

NASA Technical Reports Server (NTRS)

This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics.

Goodman, M.; Kazeminezhad, F.; Owens, T.

2009-01-01

175

Processes in relativistic plasmas  

NASA Technical Reports Server (NTRS)

The establishment and maintenance of a Boltzmann distribution in particle kinetic energies is investigated for a plasma with theta = KTe/mc-squared much greater than unity, where m is the electron mass. It is shown that thermalization of the electron gas by binary collisions is not sufficiently effective to maintain the equilibrium distribution when other processes that perturb the equilibrium are taken into account. Electron-positron pair production in electron-electron and electron-ion collisions, and perturbations of a Boltzmann distribution by nonthermal processes are evaluated. Thermalization by means of other mechanisms, such as interaction with plasma waves is discussed, and the opacity of a relativistic plasma is computed for Compton scattering, pair production in the fields of electrons and ions, inverse bremsstrahlung, and synchrotron self-absorption.

Gould, R. J.

1982-01-01

176

Novel Large Area Plasma Source Injection Using Multihelicon Plasma Sources  

NASA Astrophysics Data System (ADS)

A large-area multi-helicon plasma source has been developed for 300mm wafer etching. Large-area plasmas are formed by injection high-density plasmas with six helicon plasma sources distributed around the circular vacuum chamber. Plasma uniformity may be determined both by equal distribution of RF powers and by symmetric plasma confinement. To provide RF power deposition uniformly, we tried two method of antenna connection. The one is a hybrid of series and parallel connection, and the other is six-parallel antenna arrangement. Twelve electromagnets for plasma generation are arranged to form magnetic multi-cusp field configuration that can improve plasma uniformity as well as confinement. We achieved radial and azimuthal density uniformity of 10 percent with the diameter of 250mm at the level of processing target that is located 13cm below the level of multi source positions

Han, S. H.; Kim, Y. J.; Choi, Y. H.; Hwang, Y. S.

2001-10-01

177

Quark-Gluon Plasma Thermalization and Plasma Instabilities  

E-print Network

In this talk, I review the important role played by plasma instabilities in the thermalization of quark-gluon plasmas at very high energy. [Conference talk presented at Strong and Electroweak Mattter 2004, Helsinki, Finland, June 16--19.

Peter Arnold

2004-08-31

178

The 2012 Plasma Roadmap  

NASA Astrophysics Data System (ADS)

Low-temperature plasma physics and technology are diverse and interdisciplinary fields. The plasma parameters can span many orders of magnitude and applications are found in quite different areas of daily life and industrial production. As a consequence, the trends in research, science and technology are difficult to follow and it is not easy to identify the major challenges of the field and their many sub-fields. Even for experts the road to the future is sometimes lost in the mist. Journal of Physics D: Applied Physics is addressing this need for clarity and thus providing guidance to the field by this special Review article, The 2012 Plasma Roadmap. Although roadmaps are common in the microelectronic industry and other fields of research and development, constructing a roadmap for the field of low-temperature plasmas is perhaps a unique undertaking. Realizing the difficulty of this task for any individual, the plasma section of the Journal of Physics D Board decided to meet the challenge of developing a roadmap through an unusual and novel concept. The roadmap was divided into 16 formalized short subsections each addressing a particular key topic. For each topic a renowned expert in the sub-field was invited to express his/her individual visions on the status, current and future challenges, and to identify advances in science and technology required to meet these challenges. Together these contributions form a detailed snapshot of the current state of the art which clearly shows the lifelines of the field and the challenges ahead. Novel technologies, fresh ideas and concepts, and new applications discussed by our authors demonstrate that the road to the future is wide and far reaching. We hope that this special plasma science and technology roadmap will provide guidance for colleagues, funding agencies and government institutions. If successful in doing so, the roadmap will be periodically updated to continue to help in guiding the field.

Samukawa, Seiji; Hori, Masaru; Rauf, Shahid; Tachibana, Kunihide; Bruggeman, Peter; Kroesen, Gerrit; Whitehead, J. Christopher; Murphy, Anthony B.; Gutsol, Alexander F.; Starikovskaia, Svetlana; Kortshagen, Uwe; Boeuf, Jean-Pierre; Sommerer, Timothy J.; Kushner, Mark J.; Czarnetzki, Uwe; Mason, Nigel

2012-06-01

179

Plasma Simulation Program  

SciTech Connect

Many others in the fusion energy and advanced scientific computing communities participated in the development of this plan. The core planning team is grateful for their important contributions. This summary is meant as a quick overview the Fusion Simulation Program's (FSP's) purpose and intentions. There are several additional documents referenced within this one and all are supplemental or flow down from this Program Plan. The overall science goal of the DOE Office of Fusion Energy Sciences (FES) Fusion Simulation Program (FSP) is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in International Thermonuclear Experimental Reactor (ITER) research and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical Integrated Science Application (ISA) areas: ISA1, the plasma edge; and ISA2, whole device modeling (WDM) including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical impediment to successful operation of machines like ITER. If disruptions prove unable to be avoided, their associated dynamics and effects will be addressed in the next phase of the FSP.

Greenwald, Martin

2011-10-04

180

QED Plasma and Magnetars  

E-print Network

Magnetars are surrounded by diffuse plasma in magnetic field strengths well above the quantum electrodynamic critical value. We derive equations of "quantum force-free electrodynamics" for this plasma using an effective field theory arguments. We argue that quantum effects do not modify the large scale structure of the magnetosphere, and in particular that the spin-down rate does not deviate significantly from the classical result. We provide definite evolution equations that can be used to explore potentially important small-scale corrections, such as shock formation, which has been proposed as a mechanism for both burst and quiescent emission from magnetars.

Freytsis, Marat

2015-01-01

181

Plasma diagnostic reflectometry  

SciTech Connect

Theoretical and experimental studies of plasma diagnostic reflectometry have been undertaken as a collaborative research project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Plasma Diagnostics Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. Theoretical analyses have explored the basic principles of reflectometry to understand its limitations, to address specific gaps in the understanding of reflectometry measurements in laboratory experiments, and to explore extensions of reflectometry such as ultra-short-pulse reflectometry. The theory has supported basic laboratory reflectometry experiments where reflectometry measurements can be corroborated by independent diagnostic measurements.

Cohen, B.I.; Afeyan, B.B.; Garrison, J.C.; Kaiser, T.B. [Lawrence Livermore National Lab., CA (United States); Luhmann, N.C. Jr.; Domier, C.W.; Chou, A.E.; Baang, S. [California Univ., Davis, CA (United States). Dept. of Applied Science

1996-02-26

182

Fission induced plasmas  

NASA Technical Reports Server (NTRS)

The possibility of creating a plasma from fission fragments was investigated, as well as the probability of utilizing the energy of these particles to create population inversion leading to laser action. Eventually, it is hoped that the same medium could be used for both fissioning and lasing, thus avoiding inefficiences in converting one form of energy to the other. A central problem in understanding a fission induced plasma is to obtain an accurate model of the electron behavior; some calculations are presented to this end. The calculations are simple, providing a compendium of processes for reference.

Harries, W. L.

1977-01-01

183

DUST-PLASMA INTERACTIONS  

SciTech Connect

The objective of our theoretical research under this grant over the past 3 years was to develop new understanding in a range of topics in the physics of dust-plasma interactions, with application to space and the laboratory. We conducted studies related to the physical properties of dust, waves and instabilities in both weakly coupled and strongly coupled dusty plasmas, and innovative possible applications. A major consideration in our choice of topics was to compare theory with experiments or observations, and to motivate new experiments, which we believe is important for developing this relatively new field. Our research is summarized, with reference to our list of journal publications.

Dr. M. Rosenberg

2010-01-05

184

Solar flares. [plasma physics  

NASA Technical Reports Server (NTRS)

The present paper deals with explosions in a magnetized solar plasma, known as flares, whose effects are seen throughout the electromagnetic spectrum, from gamma-rays through the visible and to the radio band. The diverse phenomena associated with flares are discussed, along with the physical mechanisms that have been advanced to explain them. The impact of solar flare research on the development of plasma physics and magnetohydrodynamics is noted. The rapid development of solar flare research during the past 20 years, owing to the availability of high-resolution images, detailed magnetic field measurements, and improved spectral data, is illustrated.

Rust, D. M.

1979-01-01

185

Thermal plasma processing of materials  

SciTech Connect

Emphasis has been on plasma synthesis of fine powders, plasma Chemical Vapor Deposition (CVD), on related diagnostics, and on modeling work. Since plasma synthesis as well as plasma CVD make frequent use of plasma jets, the beginning has been devoted of plasma jets and behavior of particulates injected into such plasma jets. Although most of the construction of the Triple-Torch Plasma Reactor (TTPR) has already been done, modifications have been made in particular modifications required for plasma CVD of diamond. A new reactor designed for Counter-Flow Liquid Injection Plasma Synthesis (CFLIPS) proved to be an excellent tool for synthesis of fine powders as well as for plasma CVD. An attempt was made to model flow and temperature fields in this reactor. Substantial efforts were made to single out those parameters which govern particle size, size distribution, and powder quality in our plasma synthesis experiments. This knowledge is crucial for controlling the process and for meaningful diagnostics and modeling work. Plasma CVD of diamond films using both reactors has been very successful and we have been approached by a number of companies interested in using this technology for coating of tools.

Pfender, E.; Heberlein, J.

1992-02-01

186

A microwave plasma cleaning apparatus  

NASA Technical Reports Server (NTRS)

In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films (less than or equal to 20 micrometers in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-m torr) argon/oxygen plasmas were as high as 2.7 micrometers/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

Tsai, C. C.; Nelson, W. D.; Schechter, D. E.; Thompson, L. M.; Glover, A. L.

1995-01-01

187

Recent results for plasma antennas  

SciTech Connect

Plasma antennas are just as effective as metal antennas. They can transmit, receive, and reflect radio waves just as well as metal antennas. In addition, plasma generated noise does not appear to be a problem.

Alexeff, Igor; Anderson, Ted; Farshi, Esmaeil; Karnam, Naresh; Pulasani, Nanditha Reddy [Department of Electrical Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2008-05-15

188

Magnetoacoustic solitons in quantum plasma  

SciTech Connect

Nonlinear magnetoacoustic waves in collisionless homogenous, magnetized quantum plasma is studied. Two fluid quantum magneto-hydrodynamic model (QMHD) is employed and reductive perturbation method is used to derive Korteweg de Vries (KdV) equation for magnetoacoustic waves. The effects of plasma density and magnetic field intensity are investigated on magnetoacoustic solitary structures in quantum plasma. The numerical results are also presented, which are applicable to explain some aspects of the propagation of nonlinear magnetoacosutic wave in dense astrophysical plasma situations.

Hussain, S.; Mahmood, S. [Theoretical Plasma Physics Division (TPPD), PINSTECH, P.O. Nilore, Islamabad (Pakistan); Department of Physics and Applied Mathematics (DPAM), PIEAS, P.O. Nilore, Islamabad (Pakistan)

2011-08-15

189

Millimeter Wave Communication through Plasma  

NASA Technical Reports Server (NTRS)

Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

Bastin, Gary L.

2008-01-01

190

Time Dependence in Plasma Codes  

E-print Network

Time-dependent plasma codes are a natural extension of static nonequilibrium plasma codes. Comparing relevant timescales will determine whether or not time-dependent treatment is necessary. In this article I outline the ingredients for a time-dependent plasma code in a homogeneous medium and discuss the computational method. In the second half of the article I describe recombination in the early Universe as a detailed example of a problem whose solution requires a time-dependent plasma code.

S. Seager

2001-06-12

191

Plasma sources for spacecraft neutralization  

NASA Technical Reports Server (NTRS)

The principles of the operation of plasma sources for the neutralization of the surface of a spacecraft traveling in the presence of hot plasma are discussed with special attention given to the hollow-cathode-based plasma contactors. Techiques are developed that allow the calculation of the potentials and particle densities in the near environment of a hollow cathode plasma contactor in both the test tank and the LEO environment. The techniques and codes were validated by comparison of calculated and measured results.

Davis, V. A.; Katz, I.; Mandell, M. J.

1990-01-01

192

Dissipation in intercluster plasma  

E-print Network

We discuss dissipative processes in strongly gyrotropic, nearly collisionless plasma in clusters of galaxies (ICM). First, we point out that Braginsky theory, which assumes that collisions are more frequent that the system's dynamical time scale, is inapplicable to fast, sub-viscous ICM motion. Most importantly, the electron contribution to collisional magneto-viscosity dominates over that of ions for short-scale Alfvenic motions. Thus, if a turbulent cascade develops in the ICM and propagates down to scales $\\leq 1$ kpc, it is damped collisionally not on ions, but on electrons. Second, in high beta plasma of ICM, small variations of the magnetic field strength, of relative value $\\sim 1/\\beta$, lead to development of anisotropic pressure instabilities (firehose, mirror and cyclotron). Unstable wave modes may provide additional resonant scattering of particles, effectively keeping the plasma in a state of marginal stability. We show that in this case the dissipation rate of a laminar, subsonic, incompressible flows scales as inverse of plasma beta parameter. We discuss application to the problem of ICM heating.

Maxim Lyutikov

2007-09-11

193

Laboratory plasma probe studies  

NASA Technical Reports Server (NTRS)

Diagnostic experiments performed in a collisionless plasma using CO2 as the working gas are described. In particular, simultaneous measurements that have been performed by means of Langmuir- and RF-probes are presented. A resonance occurring above the parallel resonance in the frequency characteristic of a two electrode system is interpreted as being due to the resonant excitation of electroacoustic waves.

Heikkila, W. J.

1975-01-01

194

Plasma antioxidants from chocolate  

Microsoft Academic Search

There is some speculation that dietary flavonoids from chocolate, in particular (-)epicatechin, may promote cardiovascular health as a result of direct antioxidant effects or through antithrombotic mechanisms. Here we show that consumption of plain, dark chocolate (Fig. 1) results in an increase in both the total antioxidant capacity and the (-)epicatechin content of blood plasma, but that these effects are

Mauro Serafini; Rossana Bugianesi; Giuseppe Maiani; Silvia Valtuena; Simone De Santis; Alan Crozier

2003-01-01

195

Microscopic plasma Hamiltonian  

NASA Technical Reports Server (NTRS)

A Hamiltonian for the microscopic plasma model is derived from the Low Lagrangian after the dual roles of the generalized variables are taken into account. The resulting Hamilton equations are shown to agree with the Euler-Lagrange equations of the Low Lagrangian.

Peng, Y.-K. M.

1974-01-01

196

PLASMA ANTIOXIDANT MEASUREMENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Measures of in vivo antioxidant status are important in understanding the role of oxidative events in the initiation and progression of numerous diseases, including cancer, atherosclerosis, and diabetes. In vivo antioxidant status can be assessed by measuring individual plasma or tissue levels of an...

197

Flare Plasma Iron Abundance  

NASA Technical Reports Server (NTRS)

The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

2008-01-01

198

Plasma cell Leukaemia  

Microsoft Academic Search

11 patients with plasma cell leukaemia (PCL) are reported. Diagnostic clinical, haematological, immunological, biochemical and electron microscopical (TEM) data were analysed and compared to the largest series of PCL cases reported in the literature. Special attention was paid to four facets of this disease: (a) the clinical picture at admission; (b) the frequency of PCL; (c) the production of M

V. A. Toma; F. P. Retief; G. M. Potgieter; J. D. Anderson

1980-01-01

199

Nonequilibrium Atmospheric Plasma Deposition  

NASA Astrophysics Data System (ADS)

This study is a review of plasma enhanced chemical vapor deposition (PECVD) at atmospheric pressure. Sources for coatings over large area are presented. Millimetric torches and microplasmas are next studied for localized PECVD. A specific attention is paid to the way power is dissipated and the consequences it has on the deposition rate and on quality of thin films.

Belmonte, T.; Henrion, G.; Gries, T.

2011-06-01

200

Solar thermal plasma chamber  

Microsoft Academic Search

A unique solar thermal chamber has been designed and fabricated to produce the maximum concentration of solar energy and highest temperature possible. Its primary purpose was for solar plasma propulsion experiments and related material specimen testing above 3000 Kelvin. The design not only maximized solar concentration, but also, minimized infrared heat loss. This paper provides the underlining theory and operation

Joseph Bonometti; Donald R. Buchele; Charles H. Castle; Don A. Gregory

2001-01-01

201

Gyrotrons for Plasma Heating  

Microsoft Academic Search

Advances in gyrotron research have led to a new generation of devices that can operate at the megawatt power level at frequencies up to 170 GHz. These gyrotrons allow electron cyclotron heating (ECH) of plasmas to be conducted at the multimegawatt power levels needed for heating present day tokamaks and stellarators. In recent years, several breakthroughs have occurred in research

Richard Temkin

1998-01-01

202

Magnetospheric space plasma investigations  

NASA Technical Reports Server (NTRS)

The topics addressed are: (1) generalized semikinetic models; (2) collision-collisionless transition model; (3) observation of O+ outflows; (4) equatorial transitions; (5) inner plasmasphere-ionosphere coupling; (6) plasma wave physical processes; (7) ULF wave ray-tracing; and (8) nighttime anomalous electron heating events.

Comfort, Richard H.; Horwitz, James L.

1993-01-01

203

Computations in Plasma Physics.  

ERIC Educational Resources Information Center

Discusses contributions of computers to research in magnetic and inertial-confinement fusion, charged-particle-beam propogation, and space sciences. Considers use in design/control of laboratory and spacecraft experiments and in data acquisition; and reviews major plasma computational methods and some of the important physics problems they…

Cohen, Bruce I.; Killeen, John

1983-01-01

204

PLASMA EQUILIBRIUM IN TOKAMAKS  

Microsoft Academic Search

This lecture treats the magnetohydrodynamic (MHD) equi- librium of axisymmetric plasmas, as given by the Grad- Shafranov equation. In a brief introduction, equilibrium pa- rameters such as the q-profile, the internal inductance, and the poloidal beta are introduced. The properties of these quantities will be illustrated in the case of the tokamak, by applying the large aspect ratio tokamak approximation.

H. J. de Blank

2006-01-01

205

A Plasma Display Terminal.  

ERIC Educational Resources Information Center

A graphics terminal designed for use as a remote computer input/output terminal is described. Although the terminal is intended for use in teaching applications, it has several features which make it useful in many other computer terminal applications. These features include: a 10-inch square plasma display panel, permanent storage of information…

Stifle, Jack

206

Plasma edge research on TEXTOR  

Microsoft Academic Search

The relations between plasma wall interaction and plasma core properties are studied by spectroscopic methods applied to the emission of neutral particles at the plasma boundary. The interdependence between the structure of the scrape-off layer (SOL), particle-fluxes and impurity release are analyzed. In particular, the importance of molecule formation for impurity release and particle recycling in a machine with an

U. Samm; H. L. Bay; P. Bogen; H. Hartwig; E. Hintz; K. Höthker; Y. T. Lie; A. Pospieszczyk; G. G. Ross; D. Rusbüldt; B. Schweer

1987-01-01

207

Numerical simulation of dusty plasmas  

SciTech Connect

The numerical simulation of physical processes in dusty plasmas is reviewed, with emphasis on recent results and unresolved issues. Three areas of research are discussed: grain charging, weak dust-plasma interactions, and strong dust-plasma interactions. For each area, we review the basic concepts that are tested by simulations, present some appropriate examples, and examine numerical issues associated with extending present work.

Winske, D.

1995-09-01

208

Plasma Physics for Nuclear Fusion  

Microsoft Academic Search

The book focuses on the properties of gaseous plasmas needed in the attainment of controlled fusion reactions. The first five chapters develop the fundamentals of plasma physics and present the conditions of nuclear fusion reactions. The next four provide a magnetohydrodynamic description of plasmas, followed by four chapters that explain wave phenomena and instabilities by means of a kinetic model.

K. Miyamoto; Robert L. Dewar

1980-01-01

209

Plasma Window for SNS Target  

Microsoft Academic Search

Proton beam loss between the vacuum window and the target in the SNS ring to target beam transport can be completely eliminated, if Plasma Windows replace solid vacuum windows. Consequently, all problems associated with proton solid-window interaction will no longer exist. The Plasma Window is a novel apparatus, which utilized a short plasma arc to provide a vacuum -atmosphere interface

Deepak Raparia; Ady Hershcovitch

210

High-power radiating plasma  

NASA Technical Reports Server (NTRS)

The physical principles underlying the use of radiating plasmas for the optical pumping of lasers are described. Particular consideration is given to the properties of radiating plasmas; radiation selectivity; the dynamics, equilibrium, and stability of radiating plasmas; the radiative Reynolds number; and experimental results on radiating discharges.

Rozanov, V. B.; Rukhadze, A. A.

1984-01-01

211

Plasma chemistry and its applications  

NASA Technical Reports Server (NTRS)

The relationship between discharge phenomena and plasma chemistry, as well as the equipment and mechanisms of plasma chemical reactions are described. Various areas in which plasma chemistry is applied are surveyed, such as: manufacturing of semiconductor integrated circuits; synthetic fibers; high polymer materials for medical uses; optical lenses; and membrane filters (reverse penetration films).

Hozumi, K.

1980-01-01

212

Mixing of supersonic plasma jets  

Microsoft Academic Search

The objective of the present work is to predict the profile of the shock front formed by the interaction of two identical parallel diverging supersonic plasma jets. Line source models were assumed, and the differential equations describing the front location and plasma transport were formulated and solved numerically for two angular distributions of the plasma flux from each source: (a)

E. Gidalevich; R. L. Boxman; S. Goldsmith

1998-01-01

213

Magnetic Structures within Flowing Plasmas  

Microsoft Academic Search

Based on the symmetry between plasma flow and magnetic field, a new physically possible assumption about internal plasma current distribution is used to show that magnetic structures with closed flux surfaces can exist in flowing plasmas. The introduced assumption and the resulted new magnetic structures give new meanings and perspective to an ideal MHD framework initiated by Chandrasekhar in the

Zhehui Wang

2002-01-01

214

Controlled zone microwave plasma system  

DOEpatents

An apparatus and method for initiating a process gas plasma. A conductive plate having a plurality of conductive fingers is positioned in a microwave applicator. An arc forms between the conductive fingers to initiate the formation of a plasma. A transport mechanism may convey process materials through the plasma. A spray port may be provided to expel processed materials.

Ripley, Edward B. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN); Morrell, Jonathan S. (Knoxville, TN)

2009-10-20

215

TOPICAL REVIEW: Thermal plasma modelling  

Microsoft Academic Search

Electrical arcs and, more generally thermal plasmas, are widely used in many applications and the understanding or the improvement of the corresponding processes or systems, often requires precise modelling of the plasma. We present, here, a double approach to thermal plasma modelling, which combines the scientific procedure with an engineering point of view. First, we present the fundamental properties of

A. Gleizes; J. J. Gonzalez; P. Freton

2005-01-01

216

Relativistic thermal plasmas Susan Stepney  

E-print Network

Relativistic thermal plasmas by Susan Stepney Institute of Astronomy and Newnham College University Summary The study of relativistic thermal plasmas, where 2 e ekT m c , is of growing importance the development of a computer program to model a thermal plasma slab at mildly relativistic temperatures. I

Stepney, Susan

217

The Galileo Plasma wave investigation  

Microsoft Academic Search

The purpose of the Galileo plasma wave investigation is to study plasma waves and radio emissions in the magnetosphere of Jupiter. The plasma wave instrument uses an electric dipole antenna to detect electric fields, and two search coil magnetic antennas to detect magnetic fields. The frequency range covered is 5 Hz to 5.6 MHz for electric fields and 5 Hz

D. A. Gurnett; W. S. Kurth; R. R. Shaw; A. Roux; R. Gendrin; C. F. Kennel; F. L. Scarf; S. D. Shawhan

1992-01-01

218

Plasma Physics John F. Kennedy  

E-print Network

v v v v v Princeton Plasma Physics Laboratory N 278 95 1 95 18 NEW YORK John F. Kennedy Int Campus/ Sayre Drive Sign PPPLSayre Dr. Location: Princeton Plasma Physics Laboratory James Forrestal Campus U.S. Route #1 North at Sayre Drive Plainsboro, NJ 08536 Mailing Address: Princeton Plasma Physics

Princeton Plasma Physics Laboratory

219

Gas-discharge plasma sources for nonlocal plasma technology  

SciTech Connect

Nonlocal plasma technology is based on the effect of self-trapping of fast electrons in the plasma volume [V. I. Demidov, C. A. DeJoseph, Jr., and A. A. Kudryavtsev, Phys. Rev. Lett. 95, 215002 (2006)]. This effect can be achieved by changing the ratio of fast electron flux to ion flux incident on the plasma boundaries. This in turn leads to a significant change in plasma properties and therefore can be useful for technological applications. A gas-discharge device which demonstrates control of the plasma properties by this method is described.

Demidov, V. I.; DeJoseph, C. A. Jr.; Simonov, V. Ya. [UES, Inc., Dayton-Xenia Rd., Beavercreek, Ohio 45432 (United States); Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States); St. Petersburg Mining Technical University, St. Petersburg 199026 (Russian Federation)

2007-11-12

220

High Energy Plasma Photonics  

NASA Astrophysics Data System (ADS)

Ultra-intense laser technologies are opening a variety of attractive fields of science and technology using high energy density plasmas. The critical issues in the applications are control of the intense light and the enormous current and energy densities of charged particles. These applications have been usually limited by high power laser technologies and their optics. However, if we have another device consisting of the 4^th state of matter, plasma, higher energy density conditions can be more efficiently generated by this device allowing to explore the more extreme application possibilities. We denote this as ``high energy plasma photonic devices.'' One such attractive device has been demonstrated in the fast ignition scheme of the laser fusion, which is cone-guiding of ultra-intense laser light into high density regions.ootnotetextR. Kodama et al., Nature 412, 798 (2001) ; R. Kodama et al., Nature 418, 933 (2002). Another invention as a novel `photonic-like' device is a plasma fibre (5?m?/1mm) created on a hollow-cone target.ootnotetextR. Kodama et al., Nature 432, 1005 (2004). This device guides and collimates the high-density of MeV electrons generated by ultra-intense laser light in a manner akin to a light control by an optical fibre, enhancing the energy density by more than an order of magnitude and possibly generating of Giga-bar pressures. Such plasma devices hold rich promise for a range of applications utilizing enormous energy-densities of relativistic particles and will trigger a tremendous growth in high energy-density charged particle optics.

Kodama, Ryosuke

2005-10-01

221

Pulsed Electromagnetic Acceleration of Plasmas  

NASA Astrophysics Data System (ADS)

A major shift in paradigm in driving pulsed plasma thruster is necessary if the original goal of accelerating a plasma sheet efficiently to high velocities as a plasma "slug" is to be realized. Firstly, the plasma interior needs to be highly collisional so that it can be dammed by the plasma edge layer not (upstream) adjacent to the driving 'vacuum' magnetic field. Secondly, the plasma edge layer needs to be strongly magnetized so that its Hall parameter is of the order of unity in this region to ensure excellent coupling of the Lorentz force to the plasma. Thirdly, to prevent and/or suppress the occurrence of secondary arcs or restrike behind the plasma, the region behind the plasma needs to be collisionless and extremely magnetized with sufficiently large Hall parameter. This places a vacuum requirement on the bore conditions prior to the shot. These requirements are quantified in the paper and lead to the introduction of three new design parameters corresponding to these three plasma requirements. The first parameter, labeled in the paper as gamma 1, pertains to the permissible ratio of the diffusive excursion of the plasma during the course of the acceleration to the plasma longitudinal dimension. The second parameter is the required Hall parameter of the edge plasma region, and the third parameter the required Hall parameter of the region behind the plasma. Experimental research is required to quantify the values of these design parameters. Based upon fundamental theory of the transport processes in plasma, some theoretical guidance on the choice of these parameters are provided to help designing the necessary experiments to acquire these data.

Thio, Y. C. Francis; Cassibry, Jason T.; Markusic, Tom E.

2002-01-01

222

Pulsed Electromagnetic Acceleration of Plasmas  

NASA Technical Reports Server (NTRS)

A major shift in paradigm in driving pulsed plasma thruster is necessary if the original goal of accelerating a plasma sheet efficiently to high velocities as a plasma "slug" is to be realized. Firstly, the plasma interior needs to be highly collisional so that it can be dammed by the plasma edge layer not (upstream) adjacent to the driving 'vacuum' magnetic field. Secondly, the plasma edge layer needs to be strongly magnetized so that its Hall parameter is of the order of unity in this region to ensure excellent coupling of the Lorentz force to the plasma. Thirdly, to prevent and/or suppress the occurrence of secondary arcs or restrike behind the plasma, the region behind the plasma needs to be collisionless and extremely magnetized with sufficiently large Hall parameter. This places a vacuum requirement on the bore conditions prior to the shot. These requirements are quantified in the paper and lead to the introduction of three new design parameters corresponding to these three plasma requirements. The first parameter, labeled in the paper as gamma (sub 1), pertains to the permissible ratio of the diffusive excursion of the plasma during the course of the acceleration to the plasma longitudinal dimension. The second parameter is the required Hall parameter of the edge plasma region, and the third parameter the required Hall parameter of the region behind the plasma. Experimental research is required to quantify the values of these design parameters. Based upon fundamental theory of the transport processes in plasma, some theoretical guidance on the choice of these parameters are provided to help designing the necessary experiments to acquire these data.

Thio, Y. C. Francis; Cassibry, Jason T.; Markusic, Tom E.; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

223

On description of quantum plasma  

E-print Network

A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)

S. V. Vladimirov; Yu. O. Tyshetskiy

2011-01-21

224

Plasma chemistry for inorganic materials  

NASA Technical Reports Server (NTRS)

Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.

Matsumoto, O.

1980-01-01

225

Modulational interactions in quantum plasmas  

SciTech Connect

A formalism for treating modulational interactions of electrostatic fields in collisionless quantum plasmas is developed, based on the kinetic Wigner-Poisson model of quantum plasma. This formalism can be used in a range of problems of nonlinear interaction between electrostatic fields in a quantum plasma, such as development of turbulence, self-organization, as well as transition from the weak turbulent state to strong turbulence. In particular, using this formalism, we obtain the kinetic quantum Zakharov equations that describe nonlinear coupling of high frequency Langmuir waves to low frequency plasma density variations, for cases of non-degenerate and degenerate plasma electrons.

Sayed, F.; Tyshetskiy, Yu. [School of Physics, University of Sydney, New South Wales 2006 (Australia)] [School of Physics, University of Sydney, New South Wales 2006 (Australia); Vladimirov, S. V. [School of Physics, University of Sydney, New South Wales 2006 (Australia) [School of Physics, University of Sydney, New South Wales 2006 (Australia); Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)] [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)

2013-07-15

226

Plasmas in the earth's magnetotail  

NASA Technical Reports Server (NTRS)

An overview of the general charcteristics of plasmas within the earth's magnetotail and its environs is presented. Present knowledge of the plasma within these regions as gained via in situ measurements provides the general theme, although observations of magnetic fields, energetic particles and plasma waves are included in the discussion. Primary plasma regimes in the magnetotail are the plasma sheet, its boundary layer, the magnetotail lobes, the boundary layer at the magnetopause and the distant magnetotail. Although great progress in the understanding of these regions is evident in the literature of the past several years, many of their features remain as exciting enigmas to be resolved by future observational and theoretical investigation.

Frank, L. A.

1985-01-01

227

Experimental Plasma Research project summaries  

SciTech Connect

This report contains descriptions of the activities supported by the Experimental Plasma Research Branch of APP. The individual project summaries were prepared by the principal investigators and include objectives and milestones for each project. The projects are arranged in six research categories: Plasma Properties; Plasma Heating; Plasma Diagnostics; Atomic, Molecular and Nuclear Physics; Advanced Superconducting Materials; and the Fusion Plasma Research Facility (FPRF). Each category is introduced with a statement of objectives and recent progress and followed by descriptions of individual projects. An overall budget summary is provided at the beginning of the report.

None

1980-09-01

228

Transport processes in space plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth`s magnetosphere and associated waves, the Earth`s magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth`s magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior.

Birn, J.; Elphic, R.C.; Feldman, W.C. [and others

1997-08-01

229

Main Features of Plasma Control  

SciTech Connect

In the recent years Plasma Control has always increased his importance in any advanced experiment. It is now clear that ITER will not be able to operate without a quite advanced and sophisticated control apparatus. Necessarily this system will have to integrate several different aspects of the Plasma behavior. One of the most important parts of a closed loop control system is the quality of the measurement of the plasma parameters that should be controlled. Eventually, this aspect involves sophisticated and complex diagnostic apparatus. This paper presents an overview of the present status, and further studies and developments needed, in the next future, for the design and realization of an integrated plasma control system aimed at both stabilizing the plasma non-axisymmetric instabilities and controlling the most important internal plasma parameters. In particular the Edge Localized Modes (ELMs), the Neo-Classical Tearing Modes (NTM), the Resistive Wall Mode (RWM) and the Plasma Profiles control system necessities will be shortly illustrated.

Crisanti, F. [Associazione Euratom-ENEA sulla Fusione, Frascati, C.P. 65, 00044 Frascati (Italy); Albanese, R.; Ambrosino, G. [Associazione EURATOM/ENEA/CREATE, Univ. Napoli Federico II, Via Claudio21, 80125 Napoli (Italy)

2008-03-12

230

Space plasma contractor research, 1988  

NASA Technical Reports Server (NTRS)

Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included.

Williams, John D.; Wilbur, Paul J.

1989-01-01

231

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma diagnostics  

E-print Network

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma ns laser pulses were performed on argon thermal discharge plasma with electron temperature Te 10 000 discharge plasmas 1­5 , laser-induced plasmas 6­9 , pinch plasmas 10­12 , but also to study thermal plasmas

232

New Aspects of Plasma Physics  

NASA Astrophysics Data System (ADS)

Nonlinear collective processes in very dense plasmas / P. K. Shukla, B. Eliasson and D. Shaikh -- Quantum, spin and QED effects in plasmas / G. Brodin and M. Marklund -- Spin quantum plasmas - new aspects of collective dynamics / M. Marklund and G. Brodin -- Revised quantum electrodynamics with fundamental applications / B. Lehnert -- Quantum methodologies in beam, fluid and plasma physics / R. Fedele -- Plasma effects in cold atom physics / J. T. Mendonca ... [et al.] -- General properties of the Rayleigh-Taylor instability in different plasma configurations: the plasma foil model / F. Pegoraro and S. V. Bulanov -- The Rayleigh-Taylor instability of a plasma foil accelerated by the radiation pressure of an ultra intense laser pulse / F. Pegoraro and S. V. Bulanov -- Generation of galactic seed magnetic fields / H. Saleem -- Nonlinear dynamics of mirror waves in non-Maxwellian plasmas / O. A. Pokhotelov et al. -- Formation of mirror structures near instability threshold / E. A. Kuznetsov, T. Passot and P. L. Sulem -- Nonlinear dispersive Alfvén waves in magnetoplasmas / P. K. Shukla ... [et al.] -- Properties of drift and Alfvén waves in collisional plasmas / J. Vranjes, S. Poedts and B. P. Pandey -- Current driven acoustic perturbations in partially ionized collisional plasmas / J. Vranjes ... [et al.] -- Multifluid theory of solitons / F. Verheest -- Nonlinear wavepackets in pair-ion and electron-positron-ion plasmas / I. Kourakis et al. -- Electro-acoustic solitary waves in dusty plasmas / A. A. Mamun and P. K. Shukla -- Physics of dust in magnetic fusion devices / Z. Wang et al. -- Short wavelength ballooning mode in Tokamaks / A. Hirose and N. Joiner -- Effects of perpendicular shear superposition and hybrid ions intruduction on parallel shear driven plasma instabilities / T. Kaneko and R. Hatakeyama.

Schukla, Padma K.; Stenflo, Lennart; Eliasson, Bengt

2008-03-01

233

Plasma wave accelerator. II  

SciTech Connect

It was shown that the insertion of a cross magnetic field prevents the particles from getting out of phase with the electric field of the plasma wave in the beat wave accelerator scheme. Thus, using a CO/sub 2/ laser, n/sub c//n/sub e/ = (..omega../sub 0//..omega../sub p/)/sup 2/ approx. 35, and a 300 kG magnetic field, electrons can be (in principle) accelerated to 100 GeV in 2 meters. For comparison without the magnetic field, the same energies may be obtained in a n/sub c//n/sub e/ approx. 10/sup 5/ plasma over a distance of 100 meters.

Mori, W.; Joshi, C.; Dawson, J.M.

1982-01-01

234

Recent plasma focus research  

Microsoft Academic Search

The paper shows that the recently reported high pressure limit for the operation of Mather-type plasma focus devices makes discrimination difficult between the scaling laws proposed for the neutron yield. Experimental results are examined, and it is suggested that this limit may explain some well-known contingencies in neutron production. Finally, attention is given to the interpretation of X-ray anisotropy measurements

A. Banuelos; H. Bruzzone; R. Delellis; J. Gratton; R. Gratton; H. Kelly; M. Milanese; J. Pouzo; F. R. Trelles

1979-01-01

235

Platelet-rich plasma  

Microsoft Academic Search

Platelet-rich plasma is an autologous source of platelet-derived growth factor and transforming growth factor beta that is obtained by sequestering and concentrating platelets by gradient density centrifugation. This technique produced a concentration of human platelets of 338% and identified platelet-derived growth factor and transforming growth factor beta within them. Monoclonal antibody assessment of cancellous cellular marrow grafts demonstrated cells that

Robert E Marx; Eric R Carlson; Ralph M Eichstaedt; Steven R Schimmele; James E Strauss; Karen R Georgeff

1998-01-01

236

Princeton Plasma Physics Laboratory:  

SciTech Connect

This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

Phillips, C.A. (ed.)

1986-01-01

237

PLASMA CELL LEUKEMIA  

PubMed Central

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathologic entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (? 20%) and absolute number (? 2 × 10 9/L) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be reexamined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem-cell transplantation (HDT/ASCT) if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL. PMID:23288300

de Larrea, Carlos Fernandez; Kyle, Robert A.; Durie, Brian GM; Ludwig, Heinz; Usmani, Saad; Vesole, David H.; Hajek, Roman; Miguel, Jésus San; Sezer, Orhan; Sonneveld, Pieter; Kumar, Shaji K.; Mahindra, Anuj; Comenzo, Ray; Palumbo, Antonio; Mazumber, Amitabha; Anderson, Kenneth C.; Richardson, Paul G.; Badros, Ashraf Z.; Caers, Jo; Cavo, Michele; LeLeu, Xavier; Dimopoulos, Meletios A.; Chim, CS; Schots, Rik; Noeul, Amara; Fantl, Dorotea; Mellqvist, Ulf-Henrik; Landgren, Ola; Chanan-Khan, Asher; Moreau, Philippe; Fonseca, Rafael; Merlini, Giampaolo; Lahuerta, JJ; Bladé, Joan; Orlowski, Robert Z.; Shah, Jatin J.

2014-01-01

238

A nanoparticle in plasma  

SciTech Connect

Charge and energy fluxes onto a nanoparticle under conditions typical of laboratory plasmas are investigated theoretically. Here, by a nanoparticle is meant a grain the size of which is much smaller than both the electron Larmor radius and Debye length and the thermionic emission from which is not limited by the space charge. Under conditions at which thermionic emission plays an important role, the electric potential and temperature T{sub p} of a nanoparticle are determined by solving a self-consistent set of equations describing the balance of energy and charge fluxes onto the nanoparticle. It is shown that, when the degree of plasma ionization exceeds a critical level, the potential of the nanoparticle and the energy flux onto it increase with increasing nanoparticle temperature, so that, starting from a certain temperature, the nanoparticle potential becomes positive. The critical degree of ionization starting from which the potential of a nanoparticle is always positive is determined as a function of the plasma density and electron temperature. The nanoparticle temperature T{sub p} corresponding to the equilibrium state of a positively charged nanoparticle is found as a function of the electron density for different electron temperatures.

Martynenko, Yu. V.; Nagel', M. Yu.; Orlov, M. A. [Russian Research Centre Kurchatov Institute (Russian Federation)

2009-06-15

239

Sterilization by oxygen plasma  

NASA Astrophysics Data System (ADS)

The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

Moreira, Adir José; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Zambon, Luis da Silva; da Silva, Mônica Valero; Verdonck, Patrick Bernard

2004-07-01

240

Complex plasma--the plasma state of soft matter  

SciTech Connect

Complex plasma is the plasma state of soft matter which consists of weakly ionized gas (plasma) and highly charged microparticles. The microparticles are large enough to be visualized individually and their dynamics can be observed with great accuracy using simple video microscopic technique. These features allow to perform experiments with high temporal and spatial resolutions (in terms of the appropriate plasma frequency and particle separation). Furthermore, since the background gas is dilute, the particle dynamics in strongly coupled complex plasmas is virtually undamped, which provides a direct analogy to regular liquids and solids in terms of the atomistic dynamics. All these unique features allow complex plasma to be used as an ideal model system (complementary to other model systems in soft matter physics such as colloids, granular medium, etc.) to investigate various phenomena (e.g, phase transitions, phase separation, self-organizations, linear and nonlinear waves, transport, etc.) at the most fundamental kinetic level.

Chaudhuri, Manis; Khrapak, Sergei A.; Morfill, Gregor E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741, Garching (Germany)

2010-11-23

241

Plasma generating apparatus for large area plasma processing  

DOEpatents

A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

1991-07-16

242

Plasma generating apparatus for large area plasma processing  

DOEpatents

A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

Tsai, Chin-Chi (Oak Ridge, TN); Gorbatkin, Steven M. (Oak Ridge, TN); Berry, Lee A. (Oak Ridge, TN)

1991-01-01

243

Plasma Sterilization Technology for Spacecraft Applications  

NASA Technical Reports Server (NTRS)

The application of plasma gas technology to sterilization and decontamination of spacecraft components is considered. Areas investigated include: effective sterilizing ranges of four separate gases; lethal constituents of a plasma environment; effectiveness of plasma against a diverse group of microorganisms; penetrating efficiency of plasmas for sterilization; and compatibility of spacecraft materials with plasma environments. Results demonstrated that plasma gas, specifically helium plasma, is a highly effective sterilant and is compatible with spacecraft materials.

Fraser, S. J.; Olson, R. L.; Leavens, W. M.

1975-01-01

244

Measurements of plasma potential in high-pressure microwave plasmas  

Microsoft Academic Search

Plasma potential of a high-pressure (~1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of

A. V. Tarasova; N. K. Podder; E. J. Clothiaux

2009-01-01

245

Measurements of plasma potential in high-pressure microwave plasmas  

Microsoft Academic Search

Plasma potential of a high-pressure (?1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of

A. V. Tarasova; N. K. Podder; E. J. Clothiaux

2009-01-01

246

MHD description of plasma: handbook of plasma physics  

SciTech Connect

The basic sets of MHD equations for the description of a plasma in various limits are derived and their usefulness and limits of validity are discussed. These limits are: the one fluid collisional plasma, the two fluid collisional plasma, the Chew-Goldberger Low formulation of the guiding center limit of a collisionless plasma and the double-adiabatic limit. Conservation relations are derived from these sets and the mathematics of the concept of flux freezing is given. An example is given illustrating the differences between guiding center theory and double adiabatic theory.

Kulsrud, R.M.

1980-10-01

247

Plasma Diagnostics of a Capillary Plasma Channel for Laser Guiding  

SciTech Connect

We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Normarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 200 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

Terauchi, Hiromitsu [Department of Advanced Interdisciplinary Sciences, and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences, and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Bobrova, Nadezhda A. [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya str. 25, 117259 Moscow (Russian Federation)

2010-11-04

248

Plasma surface cleaning in a microwave plasma source  

SciTech Connect

A microwave electron cyclotron resonance (ECR) plasma source has been operated to produce reactive plasmas of oxygen and its mixture with argon. Aluminum samples (0.95 cm by 1.9 cm) were coated with thin films (<20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in discharge conditions of microwave power up to 1300 W, radio frequency power up to 200 W, biased potential up to 400 V, gas pressures up to 5 mtorr, and operating time up to 35 min. The surface texture of the postcleaned samples has been examined visually. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {mu}m/min. X-ray photoelectron spectroscopy (XPS) was used to determine cleanliness of the sample surfaces after plasma cleaning. The XPS study on polished samples confirmed the effectiveness of plasma cleaning in achieving atomic level of surface cleanliness. In this technical memorandum plasma properties, cleaning phenomena, and significant results are reported and discussed.

Tsai, C.C.; Nelson, W.D.; Haselton, H.H.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M. [Oak Ridge Y-12 Plant, TN (United States)

1994-03-01

249

Plasma Chemistry and Plasma Processing, Vol. 12, No.4, 1992 Infrared Radiation from an Arc Plasma and Its  

E-print Network

B ) Plasma Chemistry and Plasma Processing, Vol. 12, No.4, 1992 Infrared Radiation from an Arc Plasma and Its Application to Plasma Diagnostics Takayoshi Ohji1 and Thomas W. Eagar Received May 16 ifinfraredradiation from an arc plasma can fie used for diagnostic purposes. Tire properties of IR radiation

Eagar, Thomas W.

250

Plasma ignition for laser propulsion  

NASA Technical Reports Server (NTRS)

For a specific optical system a pulsed carbon dioxide laser having an energy output of up to 15 joules was used to initiate a plasma in air at one atmosphere pressure. The spatial and temporal development of the plasma were measured using a multiframe image converter camera. In addition the time dependent velocity of the laser supported plasma front which moves opposite to the direction of the laser pulse was measured in order to characterize the type of wavefront developed. Reliable and reproducible spark initiation was achieved. The lifetime of the highly dense plasma at the initial focal spot was determined to be less than 100 nanoseconds. The plasma front propagates toward the laser at a variable speed ranging from zero to 1.6 x 1,000,000 m/sec. The plasma front propagates for a total distance of approximately five centimeters for the energy and laser pulse shape employed.

Askew, R. F.

1982-01-01

251

Electron cyclotron resonance plasma photos  

SciTech Connect

In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

Racz, R.; Palinkas, J. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem ter 18/c (Hungary); University of Debrecen, H-4010 Debrecen, Egyetem ter 1 (Hungary); Biri, S. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem ter 18/c (Hungary)

2010-02-15

252

Adverse Effects of Plasma Transfusion  

PubMed Central

Plasma utilization has increased over the last two decades, and there is a growing concern that many plasma transfusions are inappropriate. Plasma transfusion is not without risk, and certain complications are more likely with plasma than other blood components. Clinical and laboratory investigations of the patients suffering reactions following infusion of fresh frozen plasma (FFP) define the etiology and pathogenesis of the panoply of adverse effects. We review here the pathogenesis, diagnosis, and management of the risks associated with plasma transfusion. Risks commonly associated with FFP include: (1) transfusion related acute lung injury; (2) transfusion associated circulatory overload, and (3) allergic/anaphylactic reactions. Other less common risks include (1) transmission of infections, (2) febrile non-hemolytic transfusion reactions, (3) RBC allo-immunization, and (4) hemolytic transfusion reactions. The affect of pathogen inactivation/reduction methods on these risks are also discussed. Fortunately, a majority of the adverse effects are not lethal and are adequately treated in clinical practice. PMID:22578374

Pandey, Suchitra; Vyas, Girish N.

2012-01-01

253

Cortisol Binding in Uremic Plasma  

Microsoft Academic Search

Increased morning plasma free cortisol levels have been reported previously in chronic renal failure (CRF) patients. To see whether binding abnormalities of plasma proteins contributed to the increase in morning free cortisol, binding characteristics of corticosteroid-binding globulin (CBG) were studied in pooled plasma from CRF patients and normal subjects. Using an isocolloidosmolar equilibrium dialysis method the unbound, albumin-bound, and CBG-bound

Paul M. Rosman; Renrick Benn; Martin Kay; Jean Tito; Eleanor Z. Wallace

1984-01-01

254

Plasma characterization of dry ?-EDM  

Microsoft Academic Search

An attempt was made to characterize the dry microelectric discharge machining (?-EDM) plasma systematically by using optical\\u000a emission spectroscopy. In order to characterize the plasma and its parameters such as plasma temperature, electron density,\\u000a Debye length, and gamma parameter, the optical spectra were recorded for different energies and with different diameters of\\u000a tool electrode. From the recorded spectra, using line

S. Kanmani Subbu; G. Karthikeyan; J. Ramkumar; S. Dhamodaran

2011-01-01

255

Strongly magnetized classical plasma models  

NASA Technical Reports Server (NTRS)

Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).

Montgomery, D.; Peyraud, J.; Dewitt, C.

1974-01-01

256

Plasma Edge Diagnostics for TEXTOR  

Microsoft Academic Search

The exploration of plasma-wall-interaction physics is one of the major tasks of the tokamak TEXTOR. A characterization of the high-temperature plasma edge is essential to interpret the interaction processes of the different charged and uncharged particles in the boundary layer. In the design of the TEXTOR, much effort was made to optimize diagnostic access to the plasma edge for the

S. Brezinsek; A. Huber; S. Jachmich; A. Pospieszczyk; B. Schweer; G Sergienko

2005-01-01

257

Particle simulations in magnetospheric plasmas  

NASA Technical Reports Server (NTRS)

In view of the recent remarkable advancement of computer technology and simulation software, simulation studies are one of the most powerful academic tools for establishment of quantitative space physics and modelling of our space environment. The complex nature encountered in space plasma physics has motivated considerable development in computer simulations, which have played an essential role in the development of space plasma theory. This report describes research undertaken to understand physical processes involved in plasma waves observed in the magnetospheric plasmas, and associated nonlinear phenomena such as heating, diffusion, and acceleration of particles due to excited waves. The research explains and clarifies the observational data both qualitatively and quantitatively.

Nishikawa, Ken-Ichi

1990-01-01

258

Vacuum Plasma Spraying Replaces Electrodeposition  

NASA Technical Reports Server (NTRS)

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

1992-01-01

259

Method for generating surface plasma  

DOEpatents

A method for generating a discharge plasma which covers a surface of a body in a gas at pressures from 0.01 Torr to atmospheric pressure, by applying a radio frequency power with frequencies between approximately 1 MHz and 10 GHz across a plurality of paired insulated conductors on the surface. At these frequencies, an arc-less, non-filamentary plasma can be generated to affect the drag characteristics of vehicles moving through the gas. The plasma can also be used as a source in plasma reactors for chemical reaction operations.

Miller, Paul A. (Albuquerque, NM); Aragon, Ben P. (Albuquerque, NM)

2003-05-27

260

Ultrarelativistic Electron-Positron Plasma  

E-print Network

Ultrarelativistic electron-positron plasmas can be produced in high-intensity laser fields and play a role in various astrophysical situations. Their properties can be calculated using QED at finite temperature. Here we will use perturbative QED at finite temperature for calculating various important properties, such as the equation of state, dispersion relations of collective plasma modes of photons and electrons, Debye screening, damping rates, mean free paths, collision times, transport coefficients, and particle production rates, of ultrarelativistic electron-positron plasmas. In particular, we will focus on electron-positron plasmas produced with ultra-strong lasers.

Markus H. Thoma

2008-10-06

261

Theory of Space Dusty Plasma  

NASA Astrophysics Data System (ADS)

Ionized gases, contaminated with fine (nanometer to micrometer-sized) charged dust, loosely referred to a dusty plasmas, occur in a wide variety of cosmic and laboratory environments. In this topical review I will discuss the underlying theory of such plasmas, with emphasis on the space environment. Central to the discussion is the electrostatic charging of the dust grains by the various currents that they experience in the plasma and radiative environment in which they are immersed. This charging could lead to both physical and dynamical consequences for the dust as well as for the plasma. Among the physical effects for the dust are electrostatic disruption and electrostatic levitation from charged surfaces. The dynamics of the charged dust is affected by the Lorentz force they experience, since space plasmas are generally magnetized. The physical effects for plasma result from the fact that the dust can act both as a sink and as a source of electrons in different space environments. The dynamical effects on the plasma arise from the fact that the charged dust can alter the phase velocity of normal wave modes (e.g., the Ion acoustic mode) by changing the charge equilibrium in the plasma. Additionally the charged dust can also participate in the wave dynamics, leading, for example, to the very low frequency, novel, "dust-acoustic" wave that has been observed in the laboratory. Finally the possibility that charged dust in a space plasma, may indirectly influence the propagation of electromagnetic radiation through it, will also be, briefly, discussed.

Mendis, A.

2012-12-01

262

Human Plasma Membrane Receptome  

NSDL National Science Digital Library

Cell receptor researchers have an excellent online resource in the Human Plasma Membrane Receptome (HPMR) database from the Aaron Hsueh lab, part of the Division of Reproductive Biology at Stanford University Medical Center. The database contains information for over 1000 individual cell receptors and offers a number of search options. For instance, users can navigate a concept map diagram organized by receptor function or browse a phylogenetic tree with receptor families organized by evolutionary relationship. The database provides detailed information for each receptor, including PubMed citations.

263

Renormalization and plasma physics  

SciTech Connect

A review is given of modern theories of statistical dynamics as applied to problems in plasma physics. The derivation of consistent renormalized kinetic equations is discussed, first heuristically, later in terms of powerful functional techniques. The equations are illustrated with models of various degrees of idealization, including the exactly soluble stochastic oscillator, a prototype for several important applications. The direct-interaction approximation is described in detail. Applications discussed include test particle diffusion and the justification of quasilinear theory, convective cells, E vector x B vector turbulence, the renormalized dielectric function, phase space granulation, and stochastic magnetic fields.

Krommes, J.A.

1980-02-01

264

Research on plasma physics  

NASA Astrophysics Data System (ADS)

This annual progress describes work done under AFOSR Contract 81-0093 during the period from March 15, 1984 to March 14, 1985. The experimental program accomplished extensive measurements of RF emissions from the classical Penning discharge which is operated in the UTK Plasma Science Laboratory. RF emissions were observed over a wide frequency range, megahertz to more than 1 gigahertz. These emissions appear to be incoherent; the emitted radiation intensity is approximately proportional to the electron number density. An important accomplishment underlying these RF emission measurements was the development a calibrated, broadband antenna with an approximately 100 megahertz to 1.2 gigahertz.

Roth, J. R.

1985-04-01

265

Auroral plasma waves  

NASA Technical Reports Server (NTRS)

A review is given of auroral plasma wave phenomena, starting with the earliest ground-based observations and ending with the most recent satellite observations. Two types of waves are considered, electromagnetic and electrostatic. Electromagnetic waves include auroral kilometric radiation, auroral hiss, ELF noise bands, and low-frequency electric and magnetic noise. Electrostatic waves include upper hybrid resonance emissions, electron cyclotron waves, lower hybrid waves, ion cyclotron waves and broadband electrostatic noise. In each case, a brief overview is given describing the observations, the origin of the instability, and the role of the waves in the physics of the auroral acceleration region.

Gurnett, Donald A.

1989-01-01

266

Plasma Structure and Dynamics  

NASA Astrophysics Data System (ADS)

Despite over a century of observations, the physical processes by which prominence plasma forms and evolves remain controversial. In this chapter we review the observational constraints on all mass formation models, review the four leading models—injection, levitation, evaporation-condensation, and magneto-thermal convection, describe the strengths and weaknesses of each model, and point out opportunities for future work. As needed, short tutorials are provided on fundamental physical mechanisms and concepts not covered in other chapters, including magnetic reconnection and energy balance in coronal loops.

Karpen, Judith T.

267

Analysis of Microwave Propagation In Plasma  

E-print Network

Analysis of Microwave Propagation In Plasma Elaine Chung Advisor: Dr. John Rodgers #12;Plasma OverviewPlasma Overview · Plasma ­ ionized gas htt[p://www.noaa.gov http://www.photoeverywhere.co.uk http://sohowww.nascom.nasa.gov/ #12;Experimental Plasma · Formed by collisional excitation of gas in an electric field Electrode Non

Anlage, Steven

268

FAST plasma scenarios and equilibrium configurations  

Microsoft Academic Search

In this paper we present the fusion advanced studies torus (FAST) plasma scenarios and equilibrium configurations, designed to reproduce the ITER ones (with scaled plasma current) and suitable to fulfil plasma conditions for integrated studies of plasma-wall interaction, burning plasma physics, ITER relevant operation problems and steady state scenarios. The attention is focused on FAST flexibility in terms of both

G. Calabrò; F. Crisanti; G. Ramogida; R. Albanese; A. Cardinali; A. Cucchiaro; G. Granucci; G. Maddaluno; M. Marinucci; S. Nowak; A. Pizzuto; V. Pericoli Ridolfini; A. Pironti; A. A. Tuccillo; F. Zonca

2009-01-01

269

Experimental results from detached plasmas in TFTR  

SciTech Connect

Detached plasmas are formed in TFTR which have the principal property of the boundary to the high temperature plasma core being defined by a radiating layer. This paper documents the properties of TFTR ohmic-detached plasmas with a range of plasma densities at two different plasma currents.

Strachan, J.D.; Boody, F.P.; Bush, C.E.; Cohen, S.A.; Grek, B.; Grisham, L.; Jobes, F.C.; Johnson, D.W.; Mansfield, D.K.; Medley, S.S.

1986-10-01

270

Surface reaction mechanisms in plasma etching processes  

Microsoft Academic Search

Plasma etching is an essential process in the fabrication of submicron features in the semiconductor industry. Plasma-surface interactions in plasma etching processes are capable of influencing bulk plasma properties as well as determining etch rates and feature profiles. To address the coupling of plasma and surface processes, the Surface Kinetics Model (SKM) was developed and was linked to the Hybrid

Da Zhang

2000-01-01

271

Purification of tantalum by plasma arc melting  

DOEpatents

Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

Dunn, Paul S. (Santa Fe, NM); Korzekwa, Deniece R. (Los Alamos, NM)

1999-01-01

272

BOOK REVIEW: Principles of Plasma Spectroscopy  

Microsoft Academic Search

This book gives a comprehensive treatment of plasma spectroscopy, the quantitative study of line and continuous radiation from high temperature plasmas. This highly interdisciplinary field combines elements of atomic, plasma and statistical physics, and has wide application to simulations and diagnostics of laboratory and astrophysical plasmas. Plasma spectroscopy is naturally intertwined with magnetic and inertial fusion energy science. Radiative processes

H. R. Griem

1998-01-01

273

Probe measurements in thermal plasma jets  

Microsoft Academic Search

Measurements of composition, temperature, and velocity in atmospheric argon plasma jets are reported, using enthalpy probes. The plasma jets are generated by a commercial type plasma gun and the measurements are expected to be of particular interest for industrial applications such as plasma spraying. Emphasis has been on the central and downstream regions of the plasma flame. The entrainment of

M. Brossa; E. Pfender

1988-01-01

274

Cold plasma processing technology makes advances  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cold plasma (AKA nonthermal plasma, cool plasma, gas plasma, etc.) is a rapidly maturing antimicrobial process being developed for applications in the food industry. A wide array of devices can be used to create cold plasma, but the defining characteristic is that they operate at or near room temper...

275

Plasma, The Fourth State of Matter  

ERIC Educational Resources Information Center

Discusses plasma as a source of energy through nuclear fission processes, as well as the difficulties encountered in such a process. States that 99 percent of the matter in the universe is plasma, and only 1 percent is the common three states of matter. Describes the fundamental properties of plasma, plasma "pinch, and plasma oscillations. (RR)

Zandy, Hassan F.

1970-01-01

276

Tool kit for space plasma physics  

E-print Network

2 Tool kit for space plasma physics Most of the Universe is made of plasma. And yet, plasmas kit for space plasma physics Figure 2.1 Solids, liquids and gases abound on the Earth, but most plasma physics: non-Maxwellian distributions, which are ubiquitous in the heliosphere ­ fooling our

Demoulin, Pascal

277

Cold plasma: overview of plasma technologies and applications  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cold plasma is a novel nonthermal food processing technology. It is based on energetic, reactive gases which inactivate contaminating microbes on meats, poultry and fruits and vegetables. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization pro...

278

Average plasma properties in the central plasma sheet  

Microsoft Academic Search

A statistical study on the behaviors of ion and electron moments in the central plasma sheet was carried out using tail data obtained by the three-dimensional plasma instrument on board the AMPTE\\/IRM satellite in 1986. Results show that the ion temperature increases with increasing magnetic activity and the ion density decreases during disturbed intervals, except in the neutral sheet neighborhood

W. Baumjohann; G. Paschmann; C. A. Cattell

1989-01-01

279

Inductively coupled plasma heating in a weakly magnetized plasma  

Microsoft Academic Search

A one-dimensional analysis of electron heating process in a weakly magnetized, inductively coupled plasma (MICP) is presented. It is found that the main difference in the heating process of a MICP from that of a usual unmagnetized ICP is in that circularly polarized wave modes can exist in the plasma. The right handed circularly polarized wave (R-wave) can propagate into

S. S. Kim; C. S. Chang; N. S. Yoon; Ki-Woong Whang

1999-01-01

280

EDITORIAL: 80 Years of Plasma 80 Years of Plasma  

Microsoft Academic Search

Irving Langmuir proposed the term 'plasma' in a paper in 1928 (Proc. Natl Acad. Sci. USA 14 627-637) to describe a 'region containing balanced charges of ions and electrons'. There does not appear to be any record of the thinking behind this proposal, so it is difficult to be definitive. One idea is that since the Greek word 'plasma' was

R. N. Franklin; N. St J. Braithwaite

2009-01-01

281

Plasma probe characteristics in low density hydrogen pulsed plasmas  

E-print Network

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

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

2014-01-01

282

Plasma Materials Interaction Issues For Burning Plasma Experiments  

E-print Network

, stress corrosion, creep, bonding, and hydrogen trapping · Engineering science for stress management, heat surface sees high density and temperature plasma · Key issues are hydrogen trapping, erosion, and thermal radiation of plasma and impurity species · Surface physics for sputtering, chemical erosion, hydrogen

283

Analysis of plasma waves observed within local plasma injections seen in Saturn's magnetosphere  

E-print Network

Analysis of plasma waves observed within local plasma injections seen in Saturn's magnetosphere J; published 17 May 2008. [1] Plasma injections or density depletion regions have been reported plasma in a cooler, locally produced plasma background. The injected plasma undergoes dispersion

Gurnett, Donald A.

284

Magnetized dusty plasmas: the next frontier for complex plasma research  

NASA Astrophysics Data System (ADS)

This paper discusses the role of magnetic fields in dusty (complex) plasma experiments. It first provides a description of the conditions necessary for a dusty plasma to become fully magnetized. The paper then briefly reviews a series of experimental studies that illustrate how magnetic fields are applied to dusty plasmas—from experiments that use magnetic fields to control the background plasma to those that have strong enough magnetic fields to directly modify the confinement and dynamics of the charged microparticles. The paper will then discuss the newest experiment that is currently under development at Auburn University, the magnetized dusty plasma experiment device. The paper concludes with a discussion of important outstanding physics and technical issues that will define the next generation of experiments.

Thomas, E., Jr.; Merlino, R. L.; Rosenberg, M.

2012-12-01

285

Plasma motor generator system  

NASA Technical Reports Server (NTRS)

The significant potential advantages of a plasma motor generator system over conventional systems for the generation of electrical power and propulsion for spacecraft in low Earth orbits warrants its further investigation. The two main components of such a system are a long insulated wire and the plasma generating hollow cathodes needed to maintain electrical contact with the ionosphere. Results of preliminary theoretical and experimental investigations of this system are presented. The theoretical work involved the equilibrium configurations of the wire and the nature of small oscillation about these equilibrium positions. A particularly interesting result was that two different configurations are allowed when the current is above a critical value. Experimental investigations were made of the optimal starting and running conditions for the proposed, low current hollow cathodes. Although optimal ranges of temperature, argon pressure and discharge voltage were identified, start up became progressively more difficult. This supposed depletion or contamination of the emissive surface could be countered by the addition of new emissive material.

Hite, Gerald E.

1987-01-01

286

Localized plasma balls  

NASA Astrophysics Data System (ADS)

In this paper we numerically construct localized black hole solutions in the IR end of the confining geometry of the AdS soliton, Witten's early holographic model for confinement. These black holes should be thought of as finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrized by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, these these black holes spread out in the directions parallel to IR end of the space-time, whilst their extent in the holographic radial direction remains finite. In these new black hole backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy.

Figueras, Pau; Tunyasuvunakool, Saran

2014-06-01

287

Fission-induced plasmas  

NASA Technical Reports Server (NTRS)

The possibility of creating a plasma from fission fragments, and to utilize the energy of the particles to create population inversion that would lead to laser action is investigated. An investigation was made of various laser materials which could be used for nuclear-pumped lasing. The most likely candidate for a fissioning material in the gaseous form is uranium hexafluoride - UF6, and experiments were performed to investigate materials that would be compatible with it. One of the central problems in understanding a fission-induced plasma is to obtain a model of the electron behavior, and some preliminary calculations are presented. In particular, the rates of various processes are discussed. A simple intuitive model of the electron energy distribution function is also shown. The results were useful for considering a mathematical model of a nuclear-pumped laser. Next a theoretical model of a (3)He-Ar nuclear-pumped laser is presented. The theory showed good qualitative agreement with the experimental results.

Harries, W. L.; Shiu, Y. J.

1979-01-01

288

Pulsed Plasma Thruster Contamination  

NASA Technical Reports Server (NTRS)

Pulsed Plasma Thrusters (PPT's) are currently baselined for the Air Force Mightysat II.1 flight in 1999 and are under consideration for a number of other missions for primary propulsion, precision positioning, and attitude control functions. In this work, PPT plumes were characterized to assess their contamination characteristics. Diagnostics included planar and cylindrical Langmuir probes and a large number of collimated quartz contamination sensors. Measurements were made using a LES 8/9 flight PPT at 0.24, 0.39, 0.55, and 1.2 m from the thruster, as well as in the backflow region behind the thruster. Plasma measurements revealed a peak centerline ion density and velocity of approx. 6 x 10(exp 12) cm(exp -3) and 42,000 m/s, respectively. Optical transmittance measurements of the quartz sensors after 2 x 10(exp 5) pulses showed a rapid decrease in plume contamination with increasing angle from the plume axis, with a barely measurable transmittance decrease in the ultraviolet at 90 deg. No change in optical properties was detected for sensors in the backflow region.

Myers, Roger M.; Arrington, Lynn A.; Pencil, Eric J.; Carter, Justin; Heminger, Jason; Gatsonis, Nicolas

1996-01-01

289

Periodically oscillating plasma sphere  

SciTech Connect

The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); University of Wisconsin, Madison, Wisconsin 53706 (United States)

2005-05-15

290

Arc Plasma Gun With Coaxial Powder Feed  

NASA Technical Reports Server (NTRS)

Redesigned plasma gun provides improved metallic and ceramic coatings. Particles injected directly through coaxial bore in cathode into central region of plasma jet. Introduced into hotter and faster region of plasma jet.

Zaplatynsky, Isidor

1988-01-01

291

Control of impurities in toroidal plasma devices  

DOEpatents

A method and apparatus for plasma impurity control in closed flux plasma systems such as Tokamak reactors is disclosed. Local axisymmetrical injection of hydrogen gas is employed to reverse the normally inward flow of impurities into the plasma.

Ohkawa, Tihiro (La Jolla, CA)

1980-01-01

292

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2010-04-01

293

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2011-04-01

294

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2012-04-01

295

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2013-04-01

296

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2014-04-01

297

MHD control in burning plasmas MHD control in burning plasmas  

NASA Astrophysics Data System (ADS)

Fusion physics focuses on the complex behaviour of hot plasmas confined by magnetic fields with the ultimate aim to develop a fusion power plant. In the future generation of tokamaks like ITER, the power generated by the fusion reactions substantially exceeds the external input power (Pfusion}/Pin >= 10). When this occurs one speaks of a burning plasma. Twenty per cent of the generated fusion power in a burning plasma is carried by the charged alpha particles, which transfer their energy to the ambient plasma in collisions, a process called thermalization. A new phenomenon in burning plasmas is that the alpha particles, which form a minority but carry a large fraction of the plasma kinetic energy, can collectively drive certain types of magneto-hydrodynamic (MHD) modes, while they can suppress other MHD modes. Both types of MHD modes can have desirable effects on the plasma, as well as be detrimental to the plasma. For example, the so-called sawtooth instability, on the one hand, is largely responsible for the transport of the thermalized alpha particles out of the core, but, on the other hand, may result in the loss of the energetic alphas before they have fully thermalized. A further undesirable effect of the sawtooth instability is that it may trigger other MHD modes such as neoclassical tearing modes (NTMs). These NTMs, in turn, are detrimental to the plasma confinement and in some cases may even lead to disruptive termination of the plasma. At the edge of the plasma, finally, so-called edge localized modes or ELMs occur, which result in extremely high transient heat and particle loads on the plasma-facing components of a reactor. In order to balance the desired and detrimental effects of these modes, active feedback control is required. An additional complication occurs in a burning plasma as the external heating power, which is nowadays generally used for plasma control, is small compared to the heating power of the alpha particles. The scientific challenge in the field of burn control is to find the proper balance between desired and detrimental effects of the various MHD modes and to develop the methods and tools for active feedback control of MHD modes in burning plasmas. Therefore, it is necessary to understand the dynamics of the system, in this case the mutual interactions between the fast alpha particles and the MHD instabilities. Since burning plasmas do not yet exist, the relevant experimental work until ITER comes into full operation needs to be largely based on alpha-particle simulation experiments in which the alpha particles are accelerated to high energies by means of special heating techniques. The precise conditions of a burning plasma can be only partly mimicked in present tokamaks. Hence, also a detailed computational modelling effort is needed, in order to understand the impact of findings in present machines for those of the future. In 2011 two dedicated workshops were devoted to MHD control. Firstly, there was a workshop on Control of Burning Plasmas that took place from 21-25 March 2011 at the Lorentz Centre in Leiden, The Netherlands. Secondly, the 480th Wilhelm and Else Heraeus Seminar that took place from 16-18 June in Bad Honnef, Germany was devoted to Active Control of Instabilities in Hot Plasmas. This special issue presents a collection of papers that have been presented at the two workshops, along with a few papers that are the result of an open call to contribute to this special issue.

Donné, Tony; Liang, Yunfeng

2012-07-01

298

Probe System for Plasma Research  

Microsoft Academic Search

A probe system for studying the plasma of a stellarator is described. Such a fully ionized plasma can have a density ?1013 cm?3 and a temperature ?50 eV. The probe translator can carry various probes (we take as an example a simple Langmuir electrostatic probe) and forms part of an ultrahigh vacuum system. The associated circuitry for probe biasing, control,

J. M. Chapuk; V. L. Corso; V. S. Foote; W. L. Harries; R. M. Sinclair; J. L. Upham; S. Yoshikawa

1963-01-01

299

Plasma-heating by induction  

NASA Technical Reports Server (NTRS)

Induction-heated plasma torch operates with an input of 1 Mw of direct current of which 71 percent is transferred to the plasma and the remainder is consumed by electrical losses in the system. Continuous operation of the torch should be possible for as long as 5,000 hours.

Harrington, K.; Thorpe, M. L.

1969-01-01

300

NRL Plasma Formulary: Revised 1998  

NSDL National Science Digital Library

The latest edition of the US Naval Research Laboratory's NRL Plasma Formulary, (discussed in the November 27, 1997 Scout Report) is available. This "mini-bible" for plasma physicists compiles a variety of pertinent mathematical and scientific formulas. Available in three formats, the formulary can be downloaded in its entirety or by thematic section.

301

Reactive bed plasma air purification  

Microsoft Academic Search

This invention comprises an alternating current plasma device with a porous spherical or granular material packed into the plasma zone. The device of the invention overcomes limitations of previously described air-purification systems by decomposing and deactivating toxic contaminants and producing breathable air. The contaminants that can be successfully processed include toxic vapors, gases and aerosols. In addition, the air by-products

J. G. Birmingham; R. R. Moore

1988-01-01

302

THE PARALLEL PLATE PLASMA PROBLEM  

Microsoft Academic Search

The parallel plate plasma problem is considered under the assumption of ; uniform density and a specular reflection boundary condition at the plates. The ; impedance of the device is derived for several different models of the plasma ; medium. The impedance of a hydromagnetic medium exhibits resonances whenever the ; plate separation is an odd multiple of a half

Hall

1962-01-01

303

Transferrin Receptors in Rat Plasma  

Microsoft Academic Search

Antigenic material in rat plasma reacting with rat transferrin receptor antibodies was identified as an intact receptor molecule complexed with transferrin. Plasma transferrin receptors were measured by ELISA in rats of different age and sex, of different iron status, with different degrees of erythropoiesis, and with inflammation. An inverse relationship between iron status and receptor number was found, whereas a

Yves Beguin; H. A. Huebers; B. Josephson; C. A. Finch

1988-01-01

304

Plasma suppression of beamstrahlung: Revision  

SciTech Connect

We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results. 17 refs., 5 figs., 5 tabs.

Whittum, D.H.; Sessler, A.M.; Stewart, J.J.; Yu, S.S.

1988-06-01

305

Plasma treatment advantages for textiles  

Microsoft Academic Search

The textile industry is searching for innovative production techniques to improve the product quality, as well as society requires new finishing techniques working in environmental respect. Plasma surface treatments show distinct advantages, because they are able to modify the surface properties of inert materials, sometimes with environment friendly devices. For fabrics, cold plasma treatments require the development of reliable and

Amelia Sparavigna

2008-01-01

306

Plasma phenomena in gas discharges  

Microsoft Academic Search

Basic concepts of discharges and plasmas are examined, taking into account the motion of a charged particle in a gas, the inclusion of the effects of inelastic collisions, the motion of charged particles in a magnetic field, the motion of an electron gas, Boltzmann's equation, and plasma variables in terms of the distribution functions. The positive column is considered along

R. N. Franklin

1976-01-01

307

Plasma theory and simulation research  

SciTech Connect

Our research group uses both theory and simulation as tools in order to increase the understanding of instabilities, heating, diffusion, transport and other phenomena in plasmas. We also work on the improvement of simulation, both theoretically and practically. Our focus has been more and more on the plasma edge (the sheath''), interactions with boundaries, leading to simulations of whole devices (someday a numerical tokamak).

Birdsall, C.K.

1989-01-01

308

Particle behavior in thermal plasmas  

Microsoft Academic Search

In this overview, effects exerted on the motion and on heat and mass transfer of particulates injected into a thermal plasma are discussed, including an assessment of their relative importance in the context of thermal plasma processing of materials. Results of computer experiments are shown for particle sizes ranging from 5–50 µm, and for alumina and tungsten as sample materials.

E. Pfender

1989-01-01

309

Model for resonant plasma probe.  

SciTech Connect

This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.

Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue

2007-04-01

310

Michigan Institute for Plasma Sci-  

E-print Network

Michigan Institute for Plasma Sci- ence and Engi- neering Seminar Physics of Low Pressure Inductive Inductively Coupled Plasmas (ICPs) are reviewed. In these discharges, the interaction of an electromag- netic of nonlocal electrodynamics. Nonlinear effects induced by the rf Lorentz force, such as the 2nd harmonic

Shyy, Wei

311

Space plasma contactor research, 1987  

NASA Technical Reports Server (NTRS)

A simple model describing the process of electron collection from a low pressure ambient plasma in the absence of magnetic field and contactor velocity effects is presented. Experimental measurments of the plasma surrounding the contactor are used to demonstrate that a double-sheath generally develops and separates the ambient plasma from a higher density, anode plasma located adjacent to the contactor. Agreement between the predictions of the model and experimental measurements obtained at the electron collection current levels ranging to 1 A suggests the surface area at the ambient plasma boundary of the double-sheath is equal to the electron current being collected divided by the ambient plasma random electron current density; the surface area of the higher density anode plasma boundary of the double-sheath is equal to the ion current being emitted across this boundary divided by the ion current density required to sustain a stable sheath; and the voltage drop across the sheath is determined by the requirement that the ion and electron currents counterflowing across the boundaries be at space-charge limited levels. The efficiency of contactor operation is shown to improve when significant ionization and excitation is induced by electrons that stream from the ambient plasma through the double-sheath and collide with neutral atoms being supplied through the hollow cathode.

Wilbur, Paul J.

1988-01-01

312

Hollow Plasma in a Solenoid  

SciTech Connect

A ring cathode for a pulsed, high-current, multi-spot cathodic arc discharge was placed inside a pulsed magnetic solenoid. Photography is used to evaluate the plasma distribution. The plasma appears hollow for cathode positions close the center of the solenoid, and it is guided closer to the axis when the cathode is away from the center.

Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

2010-11-30

313

Drift waves in rotating plasmas  

SciTech Connect

The stability of the electron drift wave is investigated in the presence of E x B plasma rotation typical of the central cell plasma in tandem mirrors. It is shown that a rotationally-driven drift wave may occur at low azimuthal mode numbers. Conditions for rotational instabilities are derived. Quasilinear formulas are given for the anomalous transport associated with the unstable fluctuations.

Horton, W.; Liu, J.

1983-09-01

314

Plasma diagnostics and plasma-surface interactions in inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

The semiconductor industry's continued trend of manufacturing device features on the nanometer scale requires increased plasma processing control and improved understanding of plasma characteristics and plasma-surface interactions. This dissertation presents a series of experimental results for focus studies conducted in an inductively coupled plasma (ICP) system. First novel "on-wafer" diagnostic tools are characterized and related to plasma characteristics. Second, plasma-polymer interactions are characterized as a function of plasma species and processing parameters. Complementary simulations accompany each focus study to supplement experimental findings. Wafer heating mechanisms in inductively coupled molecular gas plasmas are explored with PlasmaTemp(TM), a novel "on-wafer" diagnostic tool. Experimental wafer measurements are obtained with the PlasmaTemp(TM) wafer processed in argon (Ar) and argon-oxygen (Ar/O2) mixed plasmas. Wafer heating mechanisms were determined by combining the experimental measurements with a 3-dimensional heat transfer model of the wafer. Comparisons between pure Ar and Ar/O2 plasmas demonstrate that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. Thermal heat conduction from the neutral gas and O-atom recombination on wafer surface can contribute as much as 60% to wafer heating under conditions of low-energy ion bombardment in molecular plasmas. Measurements of a second novel "on-wafer" diagnostic sensor, the PlasmaVolt(TM), were tested and validated in the ICP system for Ar plasmas varying in power and pressure. Sensor measurements were interpreted with a numerical sheath simulation and comparison to scaling laws derived from the inhomogeneous sheath model. The study demonstrates sensor measurements are proportional to the RF-current through the sheath and the scaling is a function of sheath impedance. PlasmaVolt(TM) sensor measurements are proportional to the square root of the plasma density at the plasma-sheath interface, one-fourth root of the electron temperature, and one-fourth root of the RF bias voltage under conditions where the sheath is predominantly capacitive. When the sheath impedance becomes increasingly resistive, the sensor measurements deviate from the scaling law and tend to be directly proportional to the plasma density. Vacuum ultraviolet (VUV) emissions in Ar ICPs are characterized and the chemical and physical modifications to 193 nm photoresist (PR) polymer materials processed in Ar ICPs are investigated. Fourier transform infrared (FTIR) transmission measurements as a function of VUV photon fluence demonstrate that VUV-induced bond breaking occurs over a period of time. A numerical model demonstrates that VUV photons deplete near-surface O-containing bonds, leading to deeper, subsequent penetration and more bond losses, while the remaining near-surface C--C bonds absorb the incident radiation and slow VUV photon penetration. The roughening mechanism of blanket and patterned 193 nm PR samples are explored in a well characterized Ar ICP. FTIR and atomic force microscopy (AFM) analysis of plasma processed 193 nm PR suggests that ion-induced generation of a graphitized layer at high energies, combined with VUV bulk modification of 193 nm PR may initiate PR roughening. The roughness of blanket samples increases as a function of VUV fluence, ion energy, and substrate temperature. Line width roughness (LWR) measurements of patterned samples demonstrate a similar trend suggesting that LWR may correlate with surface roughness of patterns. The results are compared to PR studies previously conducted in an ultra-high vacuum beam system demonstrating that the vacuum beam system is a useful tool that can deconvolute and simplify complex plasma systems.

Titus, Monica Joy

315

Plasma treatment advantages for textiles  

E-print Network

The textile industry is searching for innovative production techniques to improve the product quality, as well as society requires new finishing techniques working in environmental respect. Plasma surface treatments show distinct advantages, because they are able to modify the surface properties of inert materials, sometimes with environment friendly devices. For fabrics, cold plasma treatments require the development of reliable and large systems. Such systems are now existing and the use of plasma physics in industrial problems is rapidly increasing. On textile surfaces, three main effects can be obtained depending on the treatment conditions: the cleaning effect, the increase of microroughness (anti-pilling finishing of wool) and the production of radicals to obtain hydrophilic surfaces. Plasma polymerisation, that is the deposition of solid polymeric materials with desired properties on textile substrates, is under development. The advantage of such plasma treatments is that the modification turns out to ...

Sparavigna, Amelia

2008-01-01

316

Plasma Melting Technology and Applications  

NASA Astrophysics Data System (ADS)

A plasma arc melter is a modular high-intensity skull melter capable of rapidly melting a wide variety of materials, both conductive and nonconductive. Although its commercial use to melt and process metals is well known, the method is less well known as a method of melting glass. Extensive research has been conducted by several organizations into the use of skull melting of glass using plasma arcs. This research has shown plasma melting to be a promising technology that can achieve high efficiencies, high temperatures, extreme flexibility, low capital cost, rapid changeovers of glass formulas, and minimal scrap. Plasma melting lends itself to modular melting in which each step of the glass melting process is partitioned into functional modules, which can greatly improve melting efficiency and throughput. Also, plasma arc melting has been shown to be a promising technology for rapidly and inexpensively producing "synthetic minerals" melted from common commercial oxides.

Gonterman, J. Ronald; Weinstein, M. A.

317

Current Drive in Recombining Plasma  

SciTech Connect

The Langevin equations describing the average collisional dynamics of suprathermal particles in nonstationary plasma remarkably admit an exact analytical solution in the case of recombining plasma. The current density produced by arbitrary particle fluxes is derived including the effect of charge recombination. Since recombination has the effect of lowering the charge density of the plasma, thus reducing the charged particle collisional frequencies, the evolution of the current density can be modified substantially compared to plasma with fixed charge density. The current drive efficiency is derived and optimized for discrete and continuous pulses of current, leading to the discovery of a nonzero "residual" current density that persists indefinitely under certain conditions, a feature not present in stationary plasmas.

P.F. Schmit and N.J. Fisch

2012-05-15

318

Helicon plasma thruster discharge model  

SciTech Connect

By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000?s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

Lafleur, T., E-mail: trevor.lafleur@lpp.polytechnique.fr [Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau, France and ONERA - The French Aerospace Lab, 91120 Palaiseau (France)

2014-04-15

319

Helicon plasma thruster discharge model  

NASA Astrophysics Data System (ADS)

By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

Lafleur, T.

2014-04-01

320

Transferrin receptors in rat plasma.  

PubMed Central

Antigenic material in rat plasma reacting with rat transferrin receptor antibodies was identified as an intact receptor molecule complexed with transferrin. Plasma transferrin receptors were measured by ELISA in rats of different age and sex, of different iron status, with different degrees of erythropoiesis, and with inflammation. An inverse relationship between iron status and receptor number was found, whereas a direct relationship existed between erythropoiesis and receptors. These changes in receptor number can be explained by assuming that the number of tissue receptors determined the number of plasma receptors and that the erythroid cells possessed most of the body's receptors. Increases in plasma receptors lagged behind the appearance of circulating reticulocytes, suggesting that receptors were released to the plasma during the terminal phase of erythrocyte maturation. PMID:3422446

Beguin, Y; Huebers, H A; Josephson, B; Finch, C A

1988-01-01

321

Photovoltaic Plasma Interaction Test 2  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) program is developing a plasma contactor to mitigate the harmful effects of charge collection on the station's large photovoltaic arrays. The purpose of the present test was to examine the effects of charge collection on the solar array electrical circuit and to verify the effectiveness of the plasma contactor. The results showed that the plasma contactor was able to eliminate structure arcing for any array output voltage. However, the current requirements of the plasma contactor were higher than those for prior testing and predicted by analysis. Three possible causes for this excess current demand are discussed. The most likely appeared to be a high local pressure on or very near the surface of the array as a result of vacuum tank conditions. Therefore, in actual space conditions, the plasma contactor should work as predicted.

Kaufman, Bradford A.; Chrulski, Daniel; Myers, Roger M.

1996-01-01

322

Industrial applications of thermal plasmas  

NASA Astrophysics Data System (ADS)

The main characteristics and applications of thermal plasmas are reviewed here. The industrial applications of thermal plasmas can be divided in: low power-cutting, welding, spraying; metallurgical and steelmaking; materials; environment. Some of the processes described in this article include: powder spraying, metal refining, tundish and laddle heating, production of ferroalloys and ceramic materials, and treatment of residues (aluminum scrap, steel dusts, ashes, hospital wastes, electroplating mud). The use of thermal plasmas in the environment arena in particular has attracted increasingly attention as the regulations for disposal of residues become tougher. More research and development is needed particularly for decreasing the erosion of the electrodes of plasma torches and fundamental understanding of high temperature chemistry, heat transfer, and electric arcs for broadening the applications of thermal plasmas.

Szente, Roberto Nunes

1995-09-01

323

Filters for cathodic arc plasmas  

DOEpatents

Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

Anders, Andre (Albany, CA); MacGill, Robert A. (Richmond, CA); Bilek, Marcela M. M. (Engadine, AU); Brown, Ian G. (Berkeley, CA)

2002-01-01

324

Collisionless microinstabilities in stellarators. III. The ion-temperature-gradient mode  

SciTech Connect

We investigate the linear theory of the ion-temperature-gradient (ITG) mode, with the goal of developing a general understanding that may be applied to stellarators. We highlight the Wendelstein 7X (W7-X) device. Simple fluid and kinetic models that follow closely from existing literature are reviewed and two new first-principle models are presented and compared with results from direct numerical simulation. One model investigates the effect of regions of strong localized shear, which are generic to stellarator equilibria. These “shear spikes” are found to have a potentially significant stabilizing affect on the mode; however, the effect is strongest at short wavelengths perpendicular to the magnetic field, and it is found to be significant only for the fastest growing modes in W7-X. A second model investigates the long-wavelength limit for the case of negligible global magnetic shear. The analytic calculation reveals that the effect of the curvature drive enters at second order in the drift frequency, confirming conventional wisdom that the ITG mode is slab-like at long wavelengths. Using flux tube simulations of a zero-shear W7-X configuration, we observe a close relationship to an axisymmetric configuration at a similar parameter point. It is concluded that scale lengths of the equilibrium gradients constitute a good parameter space to characterize the ITG mode. Thus, to optimize the magnetic geometry for ITG mode stability, it may be fruitful to focus on local parameters, such as the magnitude of bad curvature, connection length, and local shear at locations of bad curvature (where the ITG mode amplitude peaks)

Plunk, G. G., E-mail: gplunk@ipp.mpg.de; Helander, P.; Xanthopoulos, P. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany) [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany); Connor, J. W. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)] [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2014-03-15

325

Aerospace applications of pulsed plasmas  

NASA Astrophysics Data System (ADS)

The use of a thermal equilibrium plasma for combustion control dates back more than a hundred years to the advent of internal combustion (IC) engines and spark ignition systems. The same principles are still applied today to achieve high efficiency in various applications. Recently, the potential use of nonequilibrium plasma for ignition and combustion control has garnered increasing interest due to the possibility of plasma-assisted approaches for ignition and flame stabilization. During the past decade, significant progress has been made toward understanding the mechanisms of plasma chemistry interactions, energy redistribution and the nonequilibrium initiation of combustion. In addition, a wide variety of fuels have been examined using various types of discharge plasmas. Plasma application has been shown to provide additional combustion control, which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine (GTE) relight, detonation initiation in pulsed detonation engines (PDE) and distributed ignition control in homogeneous charge-compression ignition (HCCI) engines, among others. The present paper describes the current understanding of the nonequilibrium excitation of combustible mixtures by electrical discharges and plasma-assisted ignition and combustion. Nonequilibrium plasma demonstrates an ability to control ultra-lean, ultra-fast, low-temperature flames and appears to be an extremely promising technology for a wide range of applications, including aviation GTEs, piston engines, ramjets, scramjets and detonation initiation for pulsed detonation engines. To use nonequilibrium plasma for ignition and combustion in real energetic systems, one must understand the mechanisms of plasma-assisted ignition and combustion and be able to numerically simulate the discharge and combustion processes under various conditions.

Starikovskiy, Andrey

2012-10-01

326

Experimental plasma research project summaries  

NASA Astrophysics Data System (ADS)

This is the latest in a series of Project Summary books that date back to 1976. It is the first after a hiatus of several years. They are published to provide a short description of each project supported by the Experimental Plasma Research Branch of the Division of Applied Plasma Physics in the Office of Fusion Energy. The Experimental Plasma Research Branch seeks to provide a broad range of experimental data, physics understanding, and new experimental techniques that contribute to operation, interpretation, and improvement of high temperature plasma as a source of fusion energy. In pursuit of these objectives, the branch supports research at universities, DOE laboratories, other federal laboratories, and industry. About 70 percent of the funds expended are spent at universities and a significant function of this program is the training of students in fusion physics. The branch supports small- and medium-scale experimental studies directly related to specific critical plasma issues of the magnetic fusion program. Plasma physics experiments are conducted on transport of particles and energy within plasma. Additionally, innovative approaches for operating, controlling, and heating plasma are evaluated for application to the larger confinement devices of the magnetic fusion program. New diagnostic approaches to measuring the properties of high temperature plasmas are developed to the point where they can be applied with confidence on the large-scale confinement experiments. Atomic data necessary for impurity control, interpretation of diagnostic data, development of heating devices, and analysis of cooling by impurity ion radiation are obtained. The project summaries are grouped into the three categories of plasma physics, diagnostic development, and atomic physics.

1992-06-01

327

Method & apparatus for monitoring plasma processing operations  

DOEpatents

The invention generally relates to various aspects of a plasma process and, more specifically, to the monitoring of such plasma processes. One aspect relates to a plasma monitoring module that may be adjusted in at least some manner so as to re-evaluate a previously monitored plasma process. For instance, optical emissions data on a plasma process that was previously monitored by the plasma monitoring module may be replayed through the plasma monitoring module after making at least one adjustment in relation to the plasma monitoring module.

Smith Jr., Michael Lane; Ward, Pamela Denise; Stevenson, Joel O'Don

2004-10-19

328

Meter scale plasma source for plasma wakefield experiments  

SciTech Connect

High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J. [Department of Electrical Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

2012-12-21

329

Surface plasma source with anode layer plasma accelerator  

SciTech Connect

Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

Dudnikov, Vadim [Muons, Inc., Batavia, Illinois 60510 (United States)

2012-02-15

330

Calculation Studies for Plasma Parameters in Pulsed Plasma Thruster  

NASA Astrophysics Data System (ADS)

Mathematical modeling for the processes in pulsed plasma thrusters is the main subject of a large number of works. However, known mathematical models do not account for the entire complex of physical phenomena, taking place inside the channel of ablative pulsed plasma thruster (APPT). In general, calculation results correspond to the test data qualitatively only. Let's consider suggested model APPT. The discharge channel of the engine from above and from below is limited to the parallel metal plates playing a role of electrodes to which the having voltage from the condenser store of energy is brought. Plates have identical size and are executed in the form of trapezes or rectangulars. The having voltage is brought to the smaller basis of trapezes, and plasma goes from the smaller basis to the greater. Plates are from each other on distance d and have length eL . The part of lateral walls of the channel is closed by the teflon blocks having length tefL in a direction of movement of plasma. It is supposed, that tefe LL > , i.e. electrodes have the big length, than teflon blocks. It is also supposed, that the small initial weight of a plasma blob is set. The plasma blob is accelerated in the channel basically due to electromagnetic forces, and its weight adds for the account ablation teflon blocks as a result of absorption by teflon of energy of radiation of plasma.

Khrustalev, M.; Lyubinskaya, N.

2004-10-01

331

Production of plasma with large area for plasma application  

NASA Astrophysics Data System (ADS)

An electron cyclotron resonance plasma (ECR plasma) with large area for plasma processing is produced with a multi slot antenna whose diameter is chosen independently of microwave frequency, and the uniformity is examined as a function of pressure, microwave power, and magnetic field configuration. The plasma parameters are: ne=2.3×1011 cm-3, Te=5-10 eV, and the plasma potential Vs=20-30 V. A circular TE01 mode converted from the principal rectangular mode, TE10, is also developed to produce a high density plasma with large area. The ion saturation current density of 36 mA/cm2 is achieved for the input microwave power of 3 kW at 5×10-4 Torr. The uniformity of the ion saturation current density is within ±3% over 200 mm in diameter. Furthermore, in order to avoid window contamination, a new microwave launcher with reflector plates is designed and a dense plasma of 1013 cm-3 is realized.

Kawai, Y.; Ueda, Y.; Tanaka, M.; Shinohara, S.

1995-09-01

332

Space plasma research  

NASA Technical Reports Server (NTRS)

Temperature and density analysis in the Automated Analysis Program (for the global empirical model) were modified to use flow velocities produced by the flow velocity analysis. Revisions were started to construct an interactive version of the technique for temperature and density analysis used in the automated analysis program. A sutdy of ion and electron heating at high altitudes in the outer plasmasphere was initiated. Also the analysis of the electron gun experiments on SCATHA were extended to include eclipse operations in order to test a hypothesis that there are interactions between the 50 to 100 eV beam and spacecraft generated photoelectrons. The MASSCOMP software to be used in taking and displaying data in the two-ion plasma experiment was tested and is now working satisfactorily. Papers published during the report period are listed.

Comfort, R. H.; Horwitz, J. L.

1986-01-01

333

Magnetospheric space plasma investigations  

NASA Technical Reports Server (NTRS)

A time dependent semi-kinetic model that includes self collisions and ion-neutral collisions and chemistry was developed. Light ion outflow in the polar cap transition region was modeled and compared with data results. A model study of wave heating of O+ ions in the topside transition region was carried out using a code which does local calculations that include ion-neutral and Coulomb self collisions as well as production and loss of O+. Another project is a statistical study of hydrogen spin curve characteristics in the polar cap. A statistical study of the latitudinal distribution of core plasmas along the L=4.6 field line using DE-1/RIMS data was completed. A short paper on dual spacecraft estimates of ion temperature profiles and heat flows in the plasmasphere ionosphere system was prepared. An automated processing code was used to process RIMS data from 1981 to 1984.

Comfort, Richard H.; Horwitz, James L.

1994-01-01

334

Research in plasma physics  

NASA Technical Reports Server (NTRS)

Three aspects of barium ion cloud dynamics are discussed. First, the effect of the ratio of ion cloud conductivity to background ionospheric conductivity on the motion of barium ion clouds is investigated and compared with observations of barium ion clouds. This study led to the suggestion that the conjugate ionosphere participates in the dynamics of barium ion clouds. Second, analytic work on the deformation of ion clouds is presented. Third, a linearized stability theory was extended to include the effect of the finite extent of an ion cloud, as well as the effect of the ratio of ion cloud to ionospheric conductivities. The stability properties of a plasma with contra-streaming ion beams parallel to a magnetic field are investigated. The results are interpreted in terms of parameters appropriate for collisionless shock waves. It is found that this particular instability can be operative only if the up-stream Alfven Mach number exceeds 5.5.

1973-01-01

335

NCSX Plasma Heating Methods  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral beam injection, and radio-frequency (rf). Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, neutral beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The experimental plan requires 3 MW of 50-keV balanced neutral beam tangential injection with pulse lengths of 500 ms for initial experiments, to be upgradeable to pulse lengths of 1.5 s. Subsequent upgrades will add 3MW of neutral beam injection (NBI). This paper discusses the NCSX NBI requirements and design issues and shows how these are provided by the candidate PBX-M NBI system. In addition, estimations are given for beam heating efficiencies, scaling of heating efficiency with machine size and magnetic field level, parameter studies of the optimum beam injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of rf heating by mode conversion ion Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron cyclotron heating. The initial MCIBW heating technique and the design of the rf system lend themselves to current drive, so if current drive became desirable for any reason, only minor modifications to the heating system described here would be needed. The rf system will also be capable of localized ion heating (bulk or tail), and possiblyIBW-generated sheared flows.

H.W. Kugel, D. Spong, R. Majeski and M. Zarnstorff

2008-01-18

336

PlasmaLab/Eco-Plasma - The future of complex plasma research in space  

NASA Astrophysics Data System (ADS)

The next Russian-German cooperation for the investigation of complex plasmas under microgravity conditions on the International Space Station (ISS) is the PlasmaLab/Eco-Plasma project. Here, a new plasma chamber -- the ``Zyflex'' chamber -- is being developed. The chamber is a cylindrical plasma chamber with parallel electrodes and a flexible system geometry. It is designed to extend the accessible plasma parameter range, i.e. neutral gas pressure, plasma density and electron temperature, and also to allow an independent control of the plasma parameters, therefore increasing the experimental quality and expected knowledge gain significantly. With this system it will be possible to reach low neutral gas pressures (which means weak damping of the particle motion) and to generate large, homogeneous 3D particle systems for studies of fundamental phenomena such as phase transitions, dynamics of liquids or phase separation. The Zyflex chamber has already been operated in several parabolic flight campaigns with different configurations during the last years, yielding a promising outlook for its future development. Here, we will present the current status of the project, the technological advancements the Zyflex chamber will offer compared to its predecessors, and the latest scientific results from experiments on ground and in microgravity conditions during parabolic flights. This work and some of the authors are funded by DLR/BMWi (FKZ 50 WP 0700).

Knapek, Christina; Thomas, Hubertus; Huber, Peter; Mohr, Daniel; Hagl, Tanja; Konopka, Uwe; Lipaev, Andrey; Morfill, Gregor; Molotkov, Vladimir

337

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube. 8 figs.

Kong, P.C.; Watkins, A.D.

1999-05-25

338

Observation of an ultracold plasma instability  

E-print Network

Ultracold plasmas (UCPs), produced by photoionizing of a sample of laser-cooled and trapped atoms, have extended neutral plasma parameters by over two orders of magnitude, to electron temperatures below 1 K \\cite{killian1999}. Studies of UCPs have primarily concentrated on temperature measurements \\cite{roberts2004, gupta2007, fletcher2007}, and expansion dynamics \\cite{kulin2000, bergeson2003, robicheaux2003}, and recent work has identified a stable collective mode \\cite{fletcher2006}. A signature of the collective and nonlinear nature of plasmas is the existence of plasma instabilities, perturbations that grow exponentially to large amplitudes and dominate plasma dynamics. Much of the quest for fusion energy involves control and suppression of plasma instabilities \\cite{conway2000}. This universal dynamics occurs in all kinds of plasmas, including space plasmas \\cite{oppenheim2003, farley1963, buneman1963}, dusty plasmas \\cite{Merlino1998}, magnetically confined plasmas \\cite{krall1971}, and plasmas used fo...

Zhang, X L; Rolston, S L

2008-01-01

339

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube.

Kong, Peter C. (Idaho Falls, ID); Watkins, Arthur D. (Idaho Falls, ID)

1999-01-01

340

Propagation of an atmospheric pressure plasma plume  

SciTech Connect

The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2009-02-15

341

Propagation of an atmospheric pressure plasma plume  

NASA Astrophysics Data System (ADS)

The "plasma bullet" behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

2009-02-01

342

High energy laser plasma accelerators  

NASA Astrophysics Data System (ADS)

Intense colinear laser beams omega(O), k(O), omega(1) and k(1) shone on a plasma with a frequency separation equal to the electron plasma frequency omega(pe) are capable of creating a large coherent longitudinal electric field E(L) = mc omega(pe)/e of the order of 1 GeV/cm for a plasma density of 10 to the 18th per cu cm by the laser beat excitation of plasma oscillations. Accompanying favorable and deleterious physical effects using this process for a high energy beat-wave accelerator are discussed: longitudinal dephasing, pump depletion, transverse laser diffraction, plasma turbulence effects, self-steepening, self-focusing, etc. The basic equation, the driven nonlinear Schroedinger equation, is derived to describe this system. Advanced accelerator concepts to overcome some of these problems are proposed, including various forms of the plasma fiber accelerator. An advanced laser architecture suitable for the beat-wave accelerator is suggested. Accelerator physics issues such as the luminosity are discussed. Applications of the present process to the current drive in a plasma and to the excitation of collective oscillations within nuclei are also discussed.

Tajima, T.

1985-11-01

343

Nonlinear ICRF-Plasma Interactions  

SciTech Connect

The well developed linear theory of ICRF (including FW, HHFW and IBW) interactions with plasma has enjoyed considerable success in describing antenna coupling and wave propagation, and provides a well-known framework for calculating power absorption, current drive, etc. In some situations, less well studied nonlinear effects are of interest, such as flow drive, ponderomotive forces, rf sheaths, parametric decay and related interactions with the edge plasma. Standard ICRF codes have begun to integrate this physics to achieve improved modeling capabilities. This paper concentrates on basic rf-plasma-interaction physics with illustrative applications to tokamaks. For FW antennas, the parallel electric field near launching structures is known to drive rf-sheaths which can give rise to convective cells, interaction with plasma 'blobs', impurity production, and edge power dissipation. In addition to sheaths, IBW waves in the edge plasma are subject to strong ponderomotive effects and parametric decay. In the core plasma, slow waves can sometimes induce nonlinear effects. Mechanisms by which these waves can influence the radial electric field and its shear are summarized, and related to the general (reactive-ponderomotive and dissipative) force on a plasma from rf waves. It is argued that there are significant opportunities now for new predictive capabilities by advances in integrated simulation.

Myra, J.R.; D'Ippolito, D.A.; Russell, D.A.; Berry, L.A.; Jaeger, E.F.; Carter, M.D. [Lodestar Research Corporation, Boulder, Colorado (United States); Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)

2005-09-26

344

Atmospheric-pressure plasma jet  

DOEpatents

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Selwyn, Gary S. (Los Alamos, NM)

1999-01-01

345

Plasma medicine: an introductory review  

NASA Astrophysics Data System (ADS)

This introductory review on plasma health care is intended to provide the interested reader with a summary of the current status of this emerging field, its scope, and its broad interdisciplinary approach, ranging from plasma physics, chemistry and technology, to microbiology, biochemistry, biophysics, medicine and hygiene. Apart from the basic plasma processes and the restrictions and requirements set by international health standards, the review focuses on plasma interaction with prokaryotic cells (bacteria), eukaryotic cells (mammalian cells), cell membranes, DNA etc. In so doing, some of the unfamiliar terminology—an unavoidable by-product of interdisciplinary research—is covered and explained. Plasma health care may provide a fast and efficient new path for effective hospital (and other public buildings) hygiene—helping to prevent and contain diseases that are continuously gaining ground as resistance of pathogens to antibiotics grows. The delivery of medically active 'substances' at the molecular or ionic level is another exciting topic of research through effects on cell walls (permeabilization), cell excitation (paracrine action) and the introduction of reactive species into cell cytoplasm. Electric fields, charging of surfaces, current flows etc can also affect tissue in a controlled way. The field is young and hopes are high. It is fitting to cover the beginnings in New Journal of Physics, since it is the physics (and non-equilibrium chemistry) of room temperature atmospheric pressure plasmas that have made this development of plasma health care possible.

Kong, M. G.; Kroesen, G.; Morfill, G.; Nosenko, T.; Shimizu, T.; van Dijk, J.; Zimmermann, J. L.

2009-11-01

346

Cold plasma decontamination of foods.  

PubMed

Cold plasma is a novel nonthermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This flexible sanitizing method uses electricity and a carrier gas, such as air, oxygen, nitrogen, or helium; antimicrobial chemical agents are not required. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization process. A wide array of cold plasma systems that operate at atmospheric pressures or in low pressure treatment chambers are under development. Reductions of greater than 5 logs can be obtained for pathogens such as Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus. Effective treatment times can range from 120 s to as little as 3 s, depending on the food treated and the processing conditions. Key limitations for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods. Also, the antimicrobial modes of action for various cold plasma systems vary depending on the type of cold plasma generated. Optimization and scale up to commercial treatment levels require a more complete understanding of these chemical processes. Nevertheless, this area of technology shows promise and is the subject of active research to enhance efficacy. PMID:22149075

Niemira, Brendan A

2012-01-01

347

Logistics of automated plasma collection.  

PubMed

Plasmapheresis is widely carried out to produce plasma for fractionation. Production of Factor VIII and albumin, two proteins in plasma, drives the plasma industry. The Canadian Red Cross would like to achieve national self-sufficiency in plasma production to meet the rising demands for these proteins in the next 4 years. In order to achieve this goal we must make efficient use of our automated plasmapheresis machines and available human resources to produce a cost-effective plasma product. An assessment was undertaken at the Ottawa Centre to evaluate the number of procedures which could be performed on each machine per day and the staff required to operate these machines safely and efficiently. Donor availability, reliability and reasons for donating plasma were recorded to determine if our population could support such an escalated programme. Donor/staff interest and acceptance of automated equipment was determined. The results showed that four automated plasmapheresis devices could be operated by one nurse and one clinic assistant processing 32 donors a day with an average time of 27 min required for a 500-ml donation of plasma. The donor population was available and extremely interested; however, the logistics of scheduling proved to be an area for concern requiring special attention. PMID:3397371

McCombie, N; Rock, G

1988-01-01

348

A study of solitary plasma rings in axisymmetric plasma configurations  

E-print Network

In this thesis, we search for the plasma and field configurations that can exist under stationary conditions around a collapsed object such as a black hole. Regimes where the iso rotational condition corresponding to ...

Rabga, Tenzin

2013-01-01

349

Plasma acceleration processes in an ablative pulsed plasma thruster  

SciTech Connect

Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Advanced Energy, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2007-03-15

350

Effect of plasma surface interactions on PLT plasma parameters  

SciTech Connect

This paper gives a brief description of the geometry and parameters of the PLT tokamak, reviews some of the last four years' results that are particularly relevant to plasma-boundary interactions, and then concentrates on two specific problems.

Meservey, E.B.; Arunasalam, V.; Barnes, C.

1980-07-01

351

The absence of plasma in ``spark plasma sintering''  

NASA Astrophysics Data System (ADS)

Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employs three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include in situ atomic emission spectroscopy, direct visual observation, and ultrafast in situ voltage measurements. Using these experimental techniques, no evidence of plasma was found during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.

Hulbert, Dustin M.; Anders, André; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan; Anselmi-Tamburini, Umberto; Lavernia, Enrique J.; Mukherjee, Amiya K.

2008-08-01

352

The Absence of Plasma in"Spark Plasma Sintering"  

SciTech Connect

Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employees three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include: in-situ atomic emission spectroscopy, direct visual observation and ultra-fast in-situ voltage measurements. It was found using these experimental techniques that no plasma is present during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.

Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan; Anselmi-Tamburini, Umberto; Lavernia, Enrique J.; Mukherjee, Amiya K.

2008-04-10

353

Surface plasma source with saddle antenna radio frequency plasma generator  

SciTech Connect

A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

Dudnikov, V.; Johnson, R. P. [Muons, Inc., Batavia, Illinios 60510 (United States); Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R. [ORNL, Oak Ridge, Tennessee 37831 (United States)

2012-02-15

354

HIV inactivation in plasma products.  

PubMed

This is a review of therapeutic plasma products viz., coagulation factor concentrates, immunoglobulins, volume expanders, and protease inhibitors, and the progress made in rendering them free from transmitting infectious virus. Problems associated with the development of plasma products and the risks associated with their use are addressed. The recent technical advances designed to inactivate the hepatitis virus which led to the inactivation of HIV while preserving most of the biologic activity are reviewed. Today manufactured plasma products are essentially free from transmitting viral diseases of any significant clinical consequences. PMID:8226706

Mozen, M M

1993-01-01

355

Antimatter Plasmas in the Laboratory  

NASA Astrophysics Data System (ADS)

Progress in the ability to accumulate and cool positrons and antiprotons is enabling new scientific and technological opportunities. The driver for this work is plasma physics research - developing new ways to create and manipulate antimatter plasmas [1]. This talk presents an overview of the enabling plasma technology, recent physics results, and near-term goals and challenges. In atomic physics, new experiments on the resonant capture of positrons by molecules provide the first direct evidence that positrons bind to "ordinary" matter (i.e., atoms and molecules) [2]. The formation of low-energy antihydrogen was observed recently by injecting low-energy antiprotons into a cold positron plasma [3]. This opens up a range of new scientific opportunities, including precision tests of the CPT theorem and study of the chemistry of matter and antimatter. These studies will, however, require solving a number of challenging plasma physics problems. The first laboratory study of electron-positron plasmas was conducted by passing an electron beam through a positron plasma [4]. Electron-positron plasma experiments such as these and next-generation experiments with simultaneously confined electrons and positrons provide the possibility of studying the unusual nonlinear behavior predicted for this unique plasma system. The use of trap-based positron beams to study transport in fusion plasmas and to characterize materials will be reviewed. More challenging proposals such as the creation of a Bose-condensed gas of positronium atoms and an annihilation gamma-ray laser will also be discussed. Finally, near-term technological goals will be described, including the development of a novel multicell trap to increase by orders of magnitude the number of positrons trapped [5], portable antimatter traps, and cold antimatter beams (e.g., with energy spreads 3/4 1 meV) for precision studies of positron-matter interactions. [1] Greaves, R. G. and Surko, C. M., Phys. Plasmas 4, 1528 (1997). [2] Barnes, L. D., et al., Phys. Rev. A 67, 032706 (2003). [3] Amoretti, M.., et al., Nature 419, 456 (2002); Gabrielse, G., et al., Phys. Rev. Lett. 89, 213401 (2002). [4] Gilbert, S. J., et al., Phys. Plasmas 8, 4982-94 (2001). [5] Surko, C. M. and Greaves, R. G., Radiation Chemistry and Physics. (in press, 2003).

Surko, Clifford M.

2003-10-01

356

Fast pulse nonthermal plasma reactor  

DOEpatents

A fast pulsed nonthermal plasma reactor includes a discharge cell and a charging assembly electrically connected thereto. The charging assembly provides plural high voltage pulses to the discharge cell. Each pulse has a rise time between one and ten nanoseconds and a duration of three to twenty nanoseconds. The pulses create nonthermal plasma discharge within the discharge cell. Accordingly, the nonthermal plasma discharge can be used to remove pollutants from gases or break the gases into smaller molecules so that they can be more efficiently combusted.

Rosocha, Louis A.

2005-06-14

357

Radioimmunoassay of ACTH in plasma  

PubMed Central

Techniques are described in detail for a radioimmunoassay of plasma adrenocorticotropin (ACTH) that is capable of detecting hormone in unextracted normal human plasma at 1:5 dilution under the conditions described. The sensitivity of the assay is at the level of 1 ??g/ml (equivalent to 0.014 mU/100 ml). In normal subjects ACTH concentrations averaged 22 ??g/ml (equivalent to 0.308 mU/100 ml) plasma at 8-10 a.m. In a smaller group the concentrations averaged 9.6 ??g/ml (equivalent to 0.134 mU/100 ml) at 10-11 p.m. Although a circadian rhythm in normal subjects was not always well marked throughout the daytime hours, plasma ACTH usually fell to its lowest value in the late evening. In hospital patients who were not acutely ill, concentrations were infrequently above 100 ??g/ml in the morning and usually fell to significantly lower levels in the late evening. Severely ill hospital patients occasionally exhibited a.m. concentrations above 200 ??g/ml. In a group of subjects showing frequent spiking of plasma 17-OHCS concentrations throughout the day parallel spiking of plasma ACTH as well was generally observed. Metyrapone produced marked increases in plasma ACTH within 24 hr in all cases and generally within 3-6 hr except when started late in the day. Dexamethasone brought about a persistent reduction in plasma ACTH in a patient under continued treatment with metyrapone. Hypoglycemia, electroshock, surgery under general anesthesia, histalog and vasopressin administration were usually followed by significant increases in plasma ACTH concentration. Prior administration of dexamethasone blocked the response to hypoglycemia. Marked elevations in plasma ACTH were observed in patients with adrenal insufficiency off steroid therapy, in Cushing's disease after adrenalectomy even in the presence of persistent hypercortisolemia, and in some untreated patients with Cushing's disease. Umbilical cord blood contained higher plasma ACTH concentrations than maternal blood at delivery in seven of eight cases. After suppression of ACTH secretion by dexamethasone or cortisol. ACTH disappeared from plasma with half-times ranging from 22 min to 30 min in three cases studied. Images PMID:4302180

Berson, Solomon A.; Yalow, Rosalyn S.

1968-01-01

358

Torque on an ideal plasma.  

PubMed

Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essential contribution arises from other nonlinear terms in the equations of motion. The net force is confined to the singular layer, in the direction of the ripple wave vector and related to the energy absorbed in the layer. PMID:14525433

Taylor, J B

2003-09-12

359

Interactions between satellites and plasma  

NASA Technical Reports Server (NTRS)

The interactions of a spacecraft with the surrounding, streaming plasma were determined by the following effects: the fade out of the plasma in the wake of the probe, the emission of photoelectrons and secondary electrons, the differential charging of the surface of the probe, and a spatial potential distribution in the vicinity of the space probe. These effects and their importance are discussed and following plasma conditions are considered: (1) geostationary satellite orbits; (2) in the solar wind (HELIOS mission); and (3) in the ionosphere at an altitude of 250 km (the projected OSV on Spacelab). The fundamental models are reviewed.

Isensee, U.; Lehr, W.; Maassberg, H.

1984-01-01

360

Plasma Gate: Free Software for Atomic and Plasma Physics  

NSDL National Science Digital Library

Maintained by the Plasma Laboratory of Weizmann Institute of Science, the Free Software for Atomic and Plasma Physics Web site contains over thirty links to various programs. Examples of available software include Weizmann Institutes: 369j-symbol calculator and Russia's Institute of Spectroscopy's spectral bibliography database. Although several of the links currently seem to be dead, the site does give those working in this field access to several sites with useful software programs.

361

The Diagnostics of the External Plasma for the Plasma Rocket  

NASA Technical Reports Server (NTRS)

The plasma rocket is located at NASA Johnson Space Center. To produce a thrust in space. an inert gas is ionized into a plasma and heated in the linear section of a tokamak fusion device to 1 x 10(exp 4) - 1.16 x 10(exp 6)K(p= 10(exp 10) - 10(exp 14)/cu cm ). The magnetic field used to contain the plasma has a magnitude of 2 - 10k Gauss. The plasma plume has a variable thrust and specific impulse. A high temperature retarding potential analyzer (RPA) is being developed to characterize the plasma in the plume and at the edge of the magnetically contained plasma. The RPA measures the energy and density of ions or electrons entering into its solid angle of collection. An oscilloscope displays the ion flux versus the collected current. All measurements are made relative to the facility ground. A RPA is being developed in a process which involves the investigation of several prototypes. The first prototype has been tested on a thermal plasma. The knowledge gained from its development and testing were applied to the development of a RPA for collimated plasma. The prototypes consist of four equally spaced grids and an ion collector. The outermost grid is a ground. The second grid acts as a bias to repel electrons. The third is a variable v voltage ion suppressor. Grid four (inner grid) acts to repel secondary electrons, being biased equal to the first. Knowledge gained during these two stages are being applied to the development of a high temperature RPA Testing of this device involves the determination of its output parameters. sensitivity, and responses to a wide range of energies and densities. Each grid will be tested individually by changing only its voltage and observing the output from the RPA. To verify that the RPA is providing proper output. it is compared to the output from a Langmuir or Faraday probe.

Karr, Gerald R.

1997-01-01

362

Plasma-sheet dynamics induced by plasma mantle  

SciTech Connect

Is the magnetic field in the Earth's magnetotail static If yes, why if not, what causes the magnetic field to change and how does it evolve with time Although significant progress has been made in this area of research, a consensus still does not exist. This thesis approaches the problem from the most fundamental basis - Faraday's law relating the curl of the electric field to the time variation of the magnetic field. If we can reach an independent theory that relates the electric field to the magnetic field, the whole problem can, at least in principle, be solved. This thesis pursues the problem both physically and mathematically. Answers to the questions listed at the beginning are: (1) the magnetic field is generally not static; (2) the change is powered by the energy transfer from the solar wind to the magnetosphere, the agent that effects the change is plasma injection from the high-latitude plasma mantle; (3) the time-dependence is closely related to the velocity distribution of the mantle plasma; A decrease of B{sub z} in the near tail and a flux buildup at the farther end of tail are two primary features of the time evolution; (4) a dense, drifting plasma mantle causes an intensive reconfiguration in the plasma sheet and is likely to lead to plasma sheet instability.

Liu, W.W.

1988-01-01

363

Plasma Chemistry and Plasma Processing, Vol. 23, No. 1, March 2003 ( 2003) Model of the Negative DC Corona Plasma  

E-print Network

Plasma Chemistry and Plasma Processing, Vol. 23, No. 1, March 2003 ( 2003) Model of the Negative DC Corona Plasma: Comparison to the Positive DC Corona Plasma Junhong Chen1 and Jane H. Davidson1,2 Receiûed March 26, 2002, reûised June 14, 2002 A numerical model of the negatiûe DC corona plasma along a thin

Chen, Junhong

364

Diagnostics and etch characteristics in UHF plasmas  

Microsoft Academic Search

Plasma properties, etch characteristics and advantages of a new plasma source where a UHF power is used to ignite the plasma are reported. Plasma was produced using two different antennas and data obtained are discussed comparatively. First, a spokewise antenna consisted of 12 spokes arranged similar to the spokes in a wheel was studied. Though, the UHF power was applied

Yukito Nakagawa; Tsutomu Tsukada; Seiji Samukawa

1998-01-01

365

Recent developments in DBD plasma flow control  

NASA Astrophysics Data System (ADS)

Flow control using DBD (dielectric-barrier-discharge) plasma actuators is a relatively new, but rapidly expanding area of research. There are a number of review papers available on this subject, but few discuss on their latest developments. The purpose of the present article is to “fill the gap” by reviewing the recent trend of plasma actuator design and to summarise aerodynamic control techniques. Here, we review new plasma actuators, such as plasma synthetic jet actuators, plasma spark jet actuators, three-dimensional plasma actuators and plasma vortex generators, which can induce three-dimensional flows away from the wall. We also review the starting vortex that leads to formation of a plasma wall jet. This is an important subject not only for a better understanding of the flow induced by DBD plasma actuators, but also as a database that can be used to calibrate the numerical models for plasma flow control. Design of DBD plasma actuators to obtain turbulent skin-friction reduction is shown and the modifications to near-wall turbulence structures are summarised. Novel applications of DBD plasma actuators for aerodynamic control are then discussed, including pitch and roll control, plasma jet vectoring, circulation control and plasma flap, showing a potential of DBD plasma actuators for replacing movable, aircraft control surfaces. Finally, vortex shedding control techniques by a number of different plasma actuators are surveyed.

Wang, Jin-Jun; Choi, Kwing-So; Feng, Li-Hao; Jukes, Timothy N.; Whalley, Richard D.

2013-10-01

366

Plasma waves in the Jovian magnetosphere  

Microsoft Academic Search

Any waves which are influenced by the presence of a plasma are called plasma waves. In general, plasma waves can be classified as either electromagnetic, which have both electric and magnetic fields, or electrostatic, which have no magnetic field. The recent Voyager encounters provide the basis for the first comprehensive investigation of plasma waves in the magnetosphere of Jupiter. The

D. A. Gurnett; F. L. Scarf

1983-01-01

367

Gas discharge plasmas and their applications  

Microsoft Academic Search

This paper attempts to give an overview of gas discharge plasmas in a broad perspective. It is meant for plasma spectroscopists who are familiar with analytical plasmas (glow discharges, ICPs and microwave discharges), but who are not so well aware of other applications of these and related plasmas. In the first part, an overview will be given of the various

Annemie Bogaerts; Erik Neyts; Renaat Gijbels; Joost van der Mullen

2002-01-01

368

Electron plasma orbits from competing diocotron drifts.  

PubMed

The perpendicular dynamics of a pure electron plasma column are investigated when the plasma spans two Penning-Malmberg traps with noncoinciding axes. The plasma executes noncircular orbits described by competing image-charge electric-field (diocotron) drifts from the two traps. A simple model is presented that predicts a set of nested orbits in agreement with observed plasma trajectories. PMID:25062198

Hurst, N C; Danielson, J R; Baker, C J; Surko, C M

2014-07-11

369

Electron Plasma Orbits from Competing Diocotron Drifts  

NASA Astrophysics Data System (ADS)

The perpendicular dynamics of a pure electron plasma column are investigated when the plasma spans two Penning-Malmberg traps with noncoinciding axes. The plasma executes noncircular orbits described by competing image-charge electric-field (diocotron) drifts from the two traps. A simple model is presented that predicts a set of nested orbits in agreement with observed plasma trajectories.

Hurst, N. C.; Danielson, J. R.; Baker, C. J.; Surko, C. M.

2014-07-01

370

Characterization of electron cyclotron resonance hydrogen plasmas  

Microsoft Academic Search

Electron cyclotron resonance (ECR) plasmas yield low energy and high ion density plasmas. The characteristics downstream of an ECR hydrogen plasma were investigated as a function of microwave power and magnetic field. A fast-injection Langmuir probe and a carbon resistance probe were used to determine plasma potential ({ital V}{sub {ital p}} ), electron density ({ital N}{sub {ital e}} ), electron

C. A. Outten; J. C. Barbour; W. R. Wampler

1991-01-01

371

Double layers in laser-produced plasmas  

Microsoft Academic Search

Double layers (DLs) are defined as discontinuities in the plasma potential and are related to regions of plasma without space charge neutrality. In this review the knowledge of double layers in laser-produced plasmas is summarized. It has been shown that DLs are generated in the coronal or outer region of the laser-plasma system. The space charges there were detected experimentally.

S. Eliezer; H. Hora

1989-01-01

372

Plasma particle rotation by microwave fields  

Microsoft Academic Search

Summary form only given. Orthogonal standing electric field waves with 90deg phase difference form a rotating electrical field vector that has been observed to induce plasma rotation. Similarly, electric field waves traveling linearly have been shown to propel plasma. In both cases the plasmas are at high pressure, and collisional effects are important. This analysis demonstrates that low density plasma,

G. B. Kirby Meacham

2006-01-01

373

Applications of neural networks to plasma spectroscopy  

Microsoft Academic Search

The authors are investigating the use of neural networks to interpret spectra emitted by hot plasmas. The relative intensities of spectral lines emitted by ions in a plasma reveal much information about the electron temperature, density, and the degree of ionization of the plasma. They have developed a feed-forward, back propagation artificial neural network to infer plasma conditions from the

A. L. Osterheld; W. H. Goldstein; B. K. F. Young

1993-01-01

374

SYLLABUS: PHYSICS 8120 PLASMA PHYSICS FALL 2007  

E-print Network

SYLLABUS: PHYSICS 8120 PLASMA PHYSICS FALL 2007 Instructor: Prof. Paul J. Wiita Class Timings time. Required Text: Russell M. Kulsrud, Plasma Physics for Astrophysics (Princeton University Press A. Sturrock, Plasma Physics 3) Nicholas A. Krall & Alvin W. Trivelpiece, Principles of Plasma

Wiita, Paul J.

375

H IGHLIGHTS PRINCETON PLASMA PHYSICS LABORATORY  

E-print Network

H IGHLIGHTS PRINCETON PLASMA PHYSICS LABORATORY Princeton Plasma Physics Laboratory Fiscal Year 1996 #12; This publication highlights activities at the Princeton Plasma Physics Laboratory for fiscal. Park. 2 #12; Vision Statement Mission Statement The primary mission of the Princeton Plasma Physics

376

The physics of laser plasma interactions  

Microsoft Academic Search

Contents, abridged: Computer simulation of plasmas using particle codes. Propagation of obliquely incident light waves. Collisional absorption of electromagnetic waves in plasmas. Parametric excitation of electron and ion waves. Stimulated Raman scattering. Stimulated Brillouin scattering. Heating by plasma waves. Laser plasma experiments.

William L. Kruer

1988-01-01

377

Plasma reactor waste management systems  

NASA Technical Reports Server (NTRS)

The University of North Dakota is developing a plasma reactor system for use in closed-loop processing that includes biological, materials, manufacturing, and waste processing. Direct-current, high-frequency, or microwave discharges will be used to produce plasmas for the treatment of materials. The plasma reactors offer several advantages over other systems, including low operating temperatures, low operating pressures, mechanical simplicity, and relatively safe operation. Human fecal material, sunflowers, oats, soybeans, and plastic were oxidized in a batch plasma reactor. Over 98 percent of the organic material was converted to gaseous products. The solids were then analyzed and a large amount of water and acid-soluble materials were detected. These materials could possibly be used as nutrients for biological systems.

Ness, Robert O., Jr.; Rindt, John R.; Ness, Sumitra R.

1992-01-01

378

Space Flight Plasma Data Analysis  

NASA Technical Reports Server (NTRS)

This slide presentation reviews a method to analyze the plasma data that is reported on board the International Space station (ISS). The Floating Potential Measurement Unit (FPMU), the role of which is to obtain floating potential and ionosphere plasma measurements for validation of the ISS charging model, assess photo voltaic array variability and interpreting IRI predictions, is composed of four probes: Floating Potential Probe (FPP), Wide-sweep Langmuir Probe (WLP), Narrow-sweep Langmuir Probe (NLP) and the Plasma Impedance Probe (PIP). This gives redundant measurements of each parameter. There are also many 'boxes' that the data must pass through before being captured by the ground station, which leads to telemetry noise. Methods of analysis for the various signals from the different sets are reviewed. There is also a brief discussion of LP analysis of Low Earth Orbit plasma simulation source.

Wright, Kenneth H.; Minow, Joseph I.

2009-01-01

379

Mobile inductively coupled plasma system  

DOEpatents

A system for sampling and analyzing a material located at a hazardous site. A laser located remote from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer.

D'Silva, Arthur P. (Ames, IA); Jaselskis, Edward J. (Ames, IA)

1999-03-30

380

Hall Effect in a Plasma.  

ERIC Educational Resources Information Center

Describes an apparatus and procedure for conducting an undergraduate laboratory experiment to quantitatively study the Hall effect in a plasma. Includes background information on the Hall effect and rationale for conducting the experiment. (JN)

Kunkel, W. B.

1981-01-01

381

Plasma Heating: An Advanced Technology  

NASA Technical Reports Server (NTRS)

The Mercury and Apollo spacecraft shields were designed to protect astronauts from high friction temperatures (well over 2,000 degrees Fahrenheit) when re-entering the Earth's atmosphere. It was necessary to test and verify the heat shield materials on Earth before space flight. After exhaustive research and testing, NASA decided to use plasma heating as a heat source. This technique involves passing a strong electric current through a rarefied gas to create a plasma (ionized gas) that produces an intensely hot flame. Although NASA did not invent the concept, its work expanded the market for commercial plasma heating systems. One company, Plasma Technology Corporation (PTC), was founded by a member of the team that developed the Re-entry Heating Simulator at Ames Research Center (ARC). Dr. Camacho, President of PTC, believes the technology has significant environmental applications. These include toxic waste disposal, hydrocarbon, decomposition, medical waste disposal, asbestos waste destruction, and chemical and radioactive waste disposal.

1994-01-01

382

Laser Assisted Plasma Arc Welding  

SciTech Connect

Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

FUERSCHBACH,PHILLIP W.

1999-10-05

383

Layered plasma polymer composite membranes  

DOEpatents

Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

Babcock, Walter C. (Bend, OR)

1994-01-01

384

Plasma transport near material boundaries  

SciTech Connect

The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix.

Singer, C.E.

1985-06-01

385

Plasma in the Jovian magnetosphere  

NASA Technical Reports Server (NTRS)

It is shown that the plasma in Jupiter's ionosphere is collisionless above a certain level. In the outer magnetosphere, where the rotational force dominates the gravitational force, the collisionless plasma has a beam-like distribution and gives rise to a two-stream instability. This leads to trapping of plasma in the centrifugally dominated region of the magnetosphere. Plasma is lost by recombination. Equilibrium-trapped particle densities are calculated by requiring a balance between trapping by wave-particle interaction and loss by recombination. The results are compared with recent observations from Pioneer 10. It is suggested that the observations require an unexplained ion-heating mechanism. Some consequences of the model are discussed.

Goertz, C. K.

1975-01-01

386

Conductivity of a relativistic plasma  

SciTech Connect

The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

Braams, B.J.; Karney, C.F.F.

1989-03-01

387

Mobile inductively coupled plasma system  

DOEpatents

A system is described for sampling and analyzing a material located at a hazardous site. A laser located remotely from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer. 10 figs.

D`Silva, A.P.; Jaselskis, E.J.

1999-03-30

388

Diagnostics of Plasma Propulsion Devices  

NASA Astrophysics Data System (ADS)

Plasma rockets are rapidly emerging as critical technologies in future space flight. These devices take on various forms, ranging from electro-thermal to electromagnetic accelerators, generally categorized by the method in which electrical energy is converted to thrust. As is the case in many plasma devices, non-intrusive optical (emission, or laser-based) diagnostics is an essential element in the characterization of these plasma sources, as access to the discharges in these plasma engines is often limited. Furthermore, laser-based diagnostics offer additional benefits, including improved spatial resolution, and can provide state-specific measurements of species densities, velocities and energy distributions. In recent years, we have developed and applied a variety of emission and laser-based diagnostics strategies to the characterization of arcjet plasma and closed-drift xenon Hall plasma accelerators. Both of these types of plasma propulsion devices are of immediate interest to the space propulsion community, and are under varying stages of development. Arcjet thrusters have unique properties, with strong plasma density, temperature and velocity gradients, which enhance the coupling between the gasdynamic and plasma physics. Closed-drift Hall plasma thrusters are low density electrostatic devices that are inherently turbulent, and exhibit varying degrees of anomalous cross-field electron transport. Our most extensive, collective effort has been to apply laser-induced fluorescence, Doppler-free laser absorption, and Raman scattering to the characterization of hydrogen and helium arcjet flows. Detailed measurements of velocity, temperatures, and electron densities are compared to the results of magneto-hydrodynamic flowfield simulations. The results show that while the simulations capture many aspects of the flow, there are still some unresolved discrepancies. The database established for Hall thrusters is less extensive, as the laser absorption spectroscopy of xenon is somewhat more complicated due to the hyperfine and isotopic structure of electronic transitions. With an understanding of the spectroscopic absorption lineshape for two select transitions in neutral and ionized xenon, we have successfully mapped out the neutral and singly ionized xenon velocities in the acceleration zone of Hall thrusters. These results indicate that the acceleration zone in a short-channel thruster is outside of the device, consistent with the measurements of plasma potential using more conventional Langmuir electrostatic probes. The spectroscopic data has also been used to identify limitations in ground-test facilities.

Cappelli, Mark A.

1998-11-01

389

TFTR plasma regimes  

SciTech Connect

Significant extensions in the TFTR plasma operating regimes have been achieved with additional heating-system capability, installation of a multishot pellet injector, and the development of an enhanced confinement regime. In ohmically heated pellet-fueled discharges characterized by highly peaked density profiles, enhancements in tau/sub E/ have resulted in n/sub e/(0)tau/sub E/(a)-values of 1.5 x 10/sup 20/ m/sup -3/s. In neutral-beam-heated discharges, an operating regime has been developed in which substantial improvements in energy confinement time and neutron source strength are observed. Ion temperatures of approx.20 keV and n/sub e/(0)tau/sub E/(a)T/sub i/(0)-values of 2 x 10/sup 20/ m/sup -3/s keV have been achieved. This enhanced confinement regime is characterized by high values of ..beta../sub p/ and low values of collisionality. The observed surface voltage, which is negative during beam injection, is compared with models including beam-driven and bootstrap currents.

Hawryluk, R.J.; Arunasalam, V.; Bell, M.G.; Bitter, M. Blanchard, W.R.; Bretz, N.L.; Budny, R.; Bush, C.E.; Callen, J.D. Cohen, S.A.

1987-02-01

390

Compact plasma accelerator  

NASA Technical Reports Server (NTRS)

A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

Foster, John E. (Inventor)

2004-01-01

391

Solar thermal plasma chamber  

NASA Astrophysics Data System (ADS)

A unique solar thermal chamber has been designed and fabricated to produce the maximum concentration of solar energy and highest temperature possible. Its primary purpose was for solar plasma propulsion experiments and related material specimen testing above 3000 Kelvin. The design not only maximized solar concentration, but also, minimized infrared heat loss. This paper provides the underlining theory and operation of the chamber and initial optical correlation to the actual fabricated hardware. The chamber is placed at the focal point of an existing primary concentrator with a 2.74-meter (9 foot) focal length. A quartz lens focuses a smaller sun image at the inlet hole of the mirrored cavity. The lens focuses two image planes at prescribed positions; the sun at the cavity's entrance hole, and the primary concentrator at the junction plane of two surfaces that form the cavity chamber. The back half is an ellipsoid reflector that produces a 1.27 cm diameter final sun image. The image is 'suspended in space' 7.1cm away from the nearest cavity surface, to minimize thermal and contaminate damage to the mirror surfaces. A hemisphere mirror makes up the front chamber and has its center of curvature at the target image, where rays leaving the target are reflected back upon themselves, minimizing radiation losses.

Bonometti, Joseph; Buchele, Donald R.; Castle, Charles H.; Gregory, Don A.

2001-11-01

392

Space Plasma Physics  

NASA Technical Reports Server (NTRS)

Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

Wu, S. T.

2000-01-01

393

Welding arc plasma physics  

NASA Technical Reports Server (NTRS)

The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

Cain, Bruce L.

1990-01-01

394

Characterisation of plasma in a rail gun  

NASA Technical Reports Server (NTRS)

The mechanism of plasma and projectile acceleration in a DC rail gun is described from a microscopic point of view through the establishment of the Hall field. The plasma conductivity is shown to be a tensor, indicating that there is a small component of current parallel to the direction of acceleration. The plasma characteristics are evaluated in the experiment of Bauer et. al., as a function of plasma mass through a simple fluid mechanical analysis of the plasma. By equating the energy dissipatated in the plasma with the radiation heat loss, the properties of the plasma are determined.

Ray, P. K.

1986-01-01

395

Ionosphere-magnetosphere coupling. I - Thermal plasma  

NASA Technical Reports Server (NTRS)

The complex interaction of the cold plasma of the plasmasphere and ionosphere with the hot plasma of the ring current and the plasma sheet is studied. It is seen that a coupling, probably through wave particle interactions, exists which seems to have a strong influence on the temperature of the plasma of the outer plasmasphere and on the detailed dynamics of the bulge region, especially the formation of detached plasma regions or plasma tails. Also, there is evidence that the outer plasmasphere may display very high temperatures, and that detached plasma regions are closely associated with ring current injections.

Chappell, C. R.

1975-01-01

396

CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Plasma Descriptions I  

E-print Network

CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Chapter 5 Plasma Descriptions I: Kinetic, Two-Fluid Descriptions of plasmas are obtained from extensions of the kinetic theory of gases of charged particles in the plasma, and because the electric and magnetic fields in the plasma must

Callen, James D.

397

Experimental Investigation of Non-Thermal Electric Fields and Plasma Waves in Pulsed-Power Plasmas  

E-print Network

Experimental Investigation of Non-Thermal Electric Fields and Plasma Waves in Pulsed-Power Plasmas and the properties of plasmas under high-power pulses at the nanosecond time scale. The method is based on resonant in a coaxial-pulsed-plasma configura- tion. The plasma is doped with a laser-produced lithium heam, fol- lowed

398

Diagnostics and Investigations of the Plasma and Field Properties in Pulsed-Plasma Configurations  

E-print Network

Paper Diagnostics and Investigations of the Plasma and Field Properties in Pulsed-Plasma Plasma Switches, and a pinch system are presented. Keywords: plasma spectroscopy, pulsed power, laser methods recently developed for the measurements of electric fields, magnetic fields, and plasma properties

Doron, Ramy

399

SPINNING AN UNMAGNETIZED PLASMA FOR MAGNETOROTATIONAL INSTABILITY STUDIES IN THE PLASMA COUETTE EXPERIMENT  

E-print Network

plasma in the bulk. Plasma is produced with 2.45 GHz microwave heating, reaching Te for the plasma to rotate. A self-consistent, rotation-induced radial electric field is also measured. MaximumSPINNING AN UNMAGNETIZED PLASMA FOR MAGNETOROTATIONAL INSTABILITY STUDIES IN THE PLASMA COUETTE

Wisconsin at Madison, University of

400

Phys780: Basic Plasma Physics 1 PHYS 780. Basic Plasma Physics  

E-print Network

Phys780: Basic Plasma Physics 1 PHYS 780. Basic Plasma Physics Course objective The course objective is to introduce students to basic concepts of plasma physics and magneto theory of plasma. Vlasov equation. #12;Phys780: Basic Plasma Physics 2 9. October 1, Wednesday, Two

401

Neutrino dispersion in magnetized plasma  

E-print Network

The neutrino dispersion in the charge symmetric magnetized plasma is investigated. We have studied the plasma contribution into the additional energy of neutrino and obtained the simple expression for it. We consider in detail the neutrino self-energy under physical conditions of weak field, moderate field and strong field limits. It is shown that our result for neutrino dispersion in moderate magnetic field differ substantially from the previous one in the literature.

N. V. Mikheev; E. N. Narynskaya

2008-12-02

402

Flavors in an expanding plasma  

E-print Network

We consider the effect of an expanding plasma on probe matter by determining time-dependent D7 embeddings in the holographic dual of an expanding viscous plasma. We calculate the chiral condensate and meson spectra including contributions of viscosity. The chiral condensate essentially confirms the expectation from the static black hole. For the meson spectra we propose a scheme that is in agreement with the adiabatic approximation. New contributions arise for the vector mesons at the order of the viscosity terms.

Johannes Große; Romuald A. Janik; Piotr Surówka

2008-02-05

403

Fusion Plasma Theory project summaries  

SciTech Connect

This Project Summary book is a published compilation consisting of short descriptions of each project supported by the Fusion Plasma Theory and Computing Group of the Advanced Physics and Technology Division of the Department of Energy, Office of Fusion Energy. The summaries contained in this volume were written by the individual contractors with minimal editing by the Office of Fusion Energy. Previous summaries were published in February of 1982 and December of 1987. The Plasma Theory program is responsible for the development of concepts and models that describe and predict the behavior of a magnetically confined plasma. Emphasis is given to the modelling and understanding of the processes controlling transport of energy and particles in a toroidal plasma and supporting the design of the International Thermonuclear Experimental Reactor (ITER). A tokamak transport initiative was begun in 1989 to improve understanding of how energy and particles are lost from the plasma by mechanisms that transport them across field lines. The Plasma Theory program has actively-participated in this initiative. Recently, increased attention has been given to issues of importance to the proposed Tokamak Physics Experiment (TPX). Particular attention has been paid to containment and thermalization of fast alpha particles produced in a burning fusion plasma as well as control of sawteeth, current drive, impurity control, and design of improved auxiliary heating. In addition, general models of plasma behavior are developed from physics features common to different confinement geometries. This work uses both analytical and numerical techniques. The Fusion Theory program supports research projects at US government laboratories, universities and industrial contractors. Its support of theoretical work at universities contributes to the office of Fusion Energy mission of training scientific manpower for the US Fusion Energy Program.

Not Available

1993-10-01

404

How a Plasma Etcher Works  

NSDL National Science Digital Library

This website includes an animation which illustrates how a Plasma Etcher works. Objective: Describe all the steps used to load, etch, and unload a wafer from a plasma etcher. This simulation is from Module 048 of the Process & Equipment II Cluster of the MATEC Module Library (MML). You can find this animation under the section "Process & Equipment II." To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtmlKey

405

Transport equations in tokamak plasmas  

SciTech Connect

Tokamak plasma transport equations are usually obtained by flux surface averaging the collisional Braginskii equations. However, tokamak plasmas are not in collisional regimes. Also, ad hoc terms are added for neoclassical effects on the parallel Ohm's law, fluctuation-induced transport, heating, current-drive and flow sources and sinks, small magnetic field nonaxisymmetries, magnetic field transients, etc. A set of self-consistent second order in gyroradius fluid-moment-based transport equations for nearly axisymmetric tokamak plasmas has been developed using a kinetic-based approach. The derivation uses neoclassical-based parallel viscous force closures, and includes all the effects noted above. Plasma processes on successive time scales and constraints they impose are considered sequentially: compressional Alfven waves (Grad-Shafranov equilibrium, ion radial force balance), sound waves (pressure constant along field lines, incompressible flows within a flux surface), and collisions (electrons, parallel Ohm's law; ions, damping of poloidal flow). Radial particle fluxes are driven by the many second order in gyroradius toroidal angular torques on a plasma species: seven ambipolar collision-based ones (classical, neoclassical, etc.) and eight nonambipolar ones (fluctuation-induced, polarization flows from toroidal rotation transients, etc.). The plasma toroidal rotation equation results from setting to zero the net radial current induced by the nonambipolar fluxes. The radial particle flux consists of the collision-based intrinsically ambipolar fluxes plus the nonambipolar fluxes evaluated at the ambipolarity-enforcing toroidal plasma rotation (radial electric field). The energy transport equations do not involve an ambipolar constraint and hence are more directly obtained. The 'mean field' effects of microturbulence on the parallel Ohm's law, poloidal ion flow, particle fluxes, and toroidal momentum and energy transport are all included self-consistently. The final comprehensive equations describe radial transport of plasma toroidal rotation, and poloidal and toroidal magnetic fluxes, as well as the usual particle and energy transport.

Callen, J. D.; Hegna, C. C.; Cole, A. J. [University of Wisconsin, Madison, Wisconsin 53706-1609 (United States)

2010-05-15

406

Microwave scattering by turbulent plasma  

Microsoft Academic Search

Microwave transmission across a column of turbulent plasma is strongly influenced by the presence of small-scale plasma density inhomogeneities. In devices such as ZETA, fluctuations of 10-25% about mean densities of 1014 cm-3 have been observed with correlation lengths of up to 5-10 cm and time scales of 10-5 s. Scattering measurements have used microwaves with a free-space wavelength of

P. E. Stott

1968-01-01

407

Plastic Deformations in Complex Plasmas  

SciTech Connect

Complex plasmas are macroscopic model systems of real solids and liquids, used to study underdamped dynamics and wave phenomena. Plastic deformations of complex plasma crystals under slow uniaxial compression have been studied experimentally and numerically. It is shown that the lattice becomes locally sheared and that this strain is relaxed by shear slips resulting in global uniform compression and heat generation. Shear slips generate pairs of dislocations which move in opposite directions at subsonic speeds.

Durniak, C.; Samsonov, D. [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ (United Kingdom)

2011-04-29

408

Inertial currents in isotropic plasma  

NASA Technical Reports Server (NTRS)

The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasmas, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, MHD plasma. Solutions are developed by taking the MHD limit ot two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

Heinemann, M.; Erickson, G. M.; Pontius, D. H., Jr.

1994-01-01

409

The inductance of compressed plasma  

NASA Astrophysics Data System (ADS)

The experimental results of ATC (Adiabatic Toroidal Compressor) are re-analysed with magnetic-compression theory for clarifying the inductance of compressed plasma. Its time-varying nature during compression is revealed, as there has been uncertainty since 1977 (Daughney et al 1977 Nucl. Fusion 17 2). During compression in the major radius, the plasma inductance decreases quasi-linearly with the major radius, and its magnetic energy increases quasi-linearly with the major radius.

Li, Ge

2015-03-01

410

Experiment of THz transmission through plasma  

NASA Astrophysics Data System (ADS)

Research on terahertz wave transmission through plasma is significant for researches on plasma itself and transmission discipline of terahertz wave through plasma. It is possible for plasma with suitable density to be an available stealth outerwear for plane or missile in THz waveband. In this paper, plasma is gotten by ionizing inert gases such as argon and helium gases with pulsed high alternating voltage. With electro-optic pump-probe measurement, THz transmission phenomena through plasma have been studied. The experiments show that some parts of THz frequency components have been cut off by plasma, and with the density of plasma rising, the starting frequency of THz prohibited by plasma is going higher. Experiments also provide an assistant scheme for plasma diagnose with terahertz technique.

Sun, Jinhai; Gallacher, Jordan; Issac, Riju; Huang, Zhixun; Jaroszynski, Dino

2014-12-01

411

BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas  

NASA Astrophysics Data System (ADS)

The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this addition to the literature, for it gives the teacher of the subject a valuable reference where the inquisitive student will be able to read up on and satisfy himself about the practicality and reliability of the Vlasov theory in a hot magnetized and collisionless plasma. The book has excellent treatments of several new topics not included in previous textbooks, for example, the relativistic theory of plasma wave propagation, so important in electron cyclotron heating of magnetically confined fusion plasmas, a discussion of current drive theory and there is a welcome introduction to parametric instabilities in the final chapter. There are some things that make the readability of the book somewhat difficult. In the early parts, certain advanced concepts are introduced without much motivation or explanation, although the author is trying to be helpful by providing a list of relevant references at the end of each chapter. Here the teacher's role will be critical. Again, a certain amount of previous knowledge of the subject would prove to be invaluable to the student. The main content of the book is included in 11 chapters. Use is made of CGS Gaussian units, a favourite of plasma theorists. As the author states, these are still widely used in advanced plasma theory, and the student is well advised to become familiar with this system of units (as well as the SI system for applications). To help the reader in the Introduction, the author defines various expressions often used in plasma physics in practical units (frequencies in hertz, lengths in centimetres, temperatures in kiloelectronvolts and magnetic fields in teslas). Chapter 2 is entitled `Plasma Electrodynamics' and it introduces the Maxwell-Vlasov set of equations, as well as the important fundamentals of wave propagation, such as polarization, dispersion and the dielectric tensor, and energy relations. In Chapter 3, `Elementary Plasma Kinetic Theory', the author derives the Vlasov equation and the Fokker-Planck equation from the BBGKY hierarchy. This is a somewhat unusual chapter in a book on plasma waves, but I

Porkolab, Miklos

1998-11-01

412

Electric field divertor plasma pump  

DOEpatents

An electric field plasma pump includes a toroidal ring bias electrode (56) positioned near the divertor strike point of a poloidal divertor of a tokamak (20), or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix (40) of the poloidal divertor contacts the ring electrode (56), which then also acts as a divertor plate. A plenum (54) or other duct near the electrode (56) includes an entrance aperture open to receive electrically-driven plasma. The electrode (56) is insulated laterally with insulators (63,64), one of which (64) is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode (56) and a vacuum vessel wall (22), with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E.times.B/B.sup.2 drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable.

Schaffer, Michael J. (San Diego, CA)

1994-01-01

413

Transient plasma physics and applications  

NASA Astrophysics Data System (ADS)

The focus of this dissertation is to investigate the physics and technology of transient plasma discharges, wherein the generation of nanosecond pulsed electrical discharges ignite quiescent and flowing fuel/air mixtures. The purpose is to develop a fundamental understanding of the combustion initiated by the transient plasmas and the gas discharge physics (streamer structures and their evolution), and apply the physics to the improvement of ignition in various engine systems. In this study, significant improvements, by factors as great as 10 times, were achieved in the delay to ignition of pulse detonation engines. These improvements lead to the solution of a major problem in the development of the engines. In this work, we endeavor to understand the dynamics of chemistry occurring in engine ignition, related pulsed power, and characteristics of transient plasma generation and evolution. This study included the design and construction of transient plasma generation system based on pulsed power science, measurement of ignition delay for quiescence combustion chamber and air/fuel mixture with various flow rate from 25 to 300 g/s, measurement of OH* emission during transient plasma ignition process, and sub-nanosecond imaging of transient plasma generation and evolution. Knowledge obtained through this comprehensive study is applied to deflagration initiation and the enhancement of deflagration to detonation transitions in pulsed detonation engines, and for improved ignition for applications of these engines.

Wang, Fei

414

Variability of Plasmas Near Europa  

NASA Astrophysics Data System (ADS)

Observations of particles and fields acquired at the orbit of Europa during the Gailileo mission indicate significant variability of the plasma environment there. It is found that the background plasma density can vary by a factor ~10. Potential causes include changes in the production or transport of plasmas from the Io torus, local-time and longitudinal effects, such as systematic changes in the location of plasma-sheet gradients, or inherent variability of the plasma production rate at Europa. Measurements of the energy and angular distributions of the ions provide a capability for distinguishing thermalized torus ions from pickup ions that have recently been produced within a Europa neutral cloud. Thus the relative density of thermal ions and pickup ions is a measure that can provide insight into the cause of the overall variability of the plasma density at Europa's orbit. In this presentation, we provide an overview of the Galileo observations and discuss their significance in relationship with this above-identified ambiguity.

Paterson, W. R.; Sittler, E. C.; Cooper, J. F.; Hartle, R. E.; Lipatov, A. S.; Gershman, D. J.

2013-12-01

415

Plasma chemistry in wire chambers  

SciTech Connect

The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

Wise, J.

1990-05-01

416

The Archimedes Plasma Mass Filter  

NASA Astrophysics Data System (ADS)

Archimedes Technology Group is developing a plasma technology, called the Archimedes Plasma Mass Filter, which can separate a waste mixture ion by ion into mass groups and as such represents a major advance in waste separations technology. The filter is a plasma device employing a magnetic and electric field configuration that acts as a low-mass-pass filter for ions. Ions with mass above a tunable “cutoff mass” are expelled from the plasma. The Archimedes Plasma Mass Filter satisfies all of the requirements of an economic mass separator system: good single-pass separation, acceptable energy cost per ion, and high material throughput. This technology could significantly reduce the volume of radioactive waste at the Hanford Site in Richland, Washington, which is storing sixty percent of the nation’s defense nuclear waste. The potential waste reduction is dramatic because 82 wtpresently scheduled to be vitrified (immobilized and stored in glass) at Hanford are below mass number 60 while 99.9the radioactivity comes from atoms above mass number 89. We will present the plasma physics basis for the filter effect, the fundamental parameter constraints, and modeling results of filter operation.

Miller, R. L.; Ohkawa, T.; Agnew, S. F.; Cluggish, B. P.; Freeman, R. L.; Gilleland, J.; Putvinski, S.; Sevier, L.; Umstadter, K. R.

2001-10-01

417

Electric field divertor plasma pump  

DOEpatents

An electric field plasma pump includes a toroidal ring bias electrode positioned near the divertor strike point of a poloidal divertor of a tokamak, or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix of the poloidal divertor contacts the ring electrode, which then also acts as a divertor plate. A plenum or other duct near the electrode includes an entrance aperture open to receive electrically-driven plasma. The electrode is insulated laterally with insulators, one of which is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode and a vacuum vessel wall, with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E [times] B/B[sup 2] drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable. 11 figs.

Schaffer, M.J.

1994-10-04

418

Evidence of plasma vortices in the Venus plasma wake  

NASA Astrophysics Data System (ADS)

Measurements conducted with plasma instruments in the Pioneer Venus Orbiter (PVO) and in the Venus Express (VEX) spacecraft have led to the observation of plasma velocity distributions that resemble the presence of vortices in the Venus wake. The velocity vectors of plasma fluxes measured along several orbits of the PVO trajectory reveal cases in which they are sunward oriented, and also instances where the velocity vectors are anti-sunward oriented but they point into the inner plasma wake. At the same time measurements conducted with the ASPERA-4 instrument of the VEX spacecraft show velocity vectors in the plasma wake that are arranged in patterns that are consistent with vorticity vector structures in the downstream vicinity of the polar regions and also in the Venus central wake. A fluid dynamic interpretation of such measurements in terms of vortex structures lead to calculations of the viscosity coefficient with estimates of the damping that they experience through local viscosity forces and are in agreement with those derived from the transport of solar wind momentum to the Venus upper ionosphere. From the analysis of the vorticity equation applied to the plasma conditions in the wake it is found that their evolution requires values of the viscosity coefficient that are comparable to those inferred from calculations of the momentum equation of the solar wind as it streams by the flanks of the Venus ionosheath, and thus the results obtained stress the value of viscosity as an important property of the plasma in the interaction of the solar wind with the Venus ionosphere.

Perez de Tejada, H. A.; Intriligator, D. S.; Lundin, R.; Reyes-Ruiz, M.

2010-12-01

419

Plasma waves in parametric interactions  

NASA Astrophysics Data System (ADS)

The nonlinear laser-plasma interaction is widely discussed in the modern plasma literature with applications to inertial confinement fusion, generation of fast electrons, and amplification of high power radiation. Among nonlinear wave phenomena in plasma, the parametric wave coupling often plays the dominant role in laser-plasma interaction at moderate laser intensities since it is the lowest order nonlinear effect. The plasma wave can mediate the parametric laser coupling with high efficiency. We study the interplay of the parametric laser-plasma interaction and other physical effects which may affect this interaction. We study this interplay with an emphasis on the plasma-based backward Raman amplifier (BRA) based on the three-wave coupling. Three major types of physical effects in the parametric wave coupling are studied. In the first part of the thesis, we find the longitudinal profiles of the interacting waves in cases of interest for pulse compression. We find the solution for the output pulse in backward Raman amplification seeded by a laser pulse of finite duration. We also propose a new scheme for high-power amplification for pulses in the terahertz frequency range. For this scheme, based on the four-wave mixing in a capillary filled with plasma, we find the profile of the output pulse. The second part of this thesis is devoted to transverse effects, which may reduce the focusability of the output pulse in backward Raman amplification. We find that the transverse modulations of the pump can be averaged and do not reduce the amplified pulse focusability if the longitudinal length of these modulations is much smaller than the amplification length. In the third part, we study the kinetic effects. We propose a simplified fluid model for the nonlinear Landau damping of a parametrically driven plasma wave and study the effect of nonlinear Landau damping in backward Raman amplification. This simplified model can be useful not only for understanding complex phenomena, but also for making more complex problems tractable numerically. Finally, we analyze current experimental data and indicate limiting mechanisms in plasma-based backward Raman amplifier.

Yampolsky, Nikolai Andreevich

420

EDITORIAL: Stochasticity in fusion plasmas  

NASA Astrophysics Data System (ADS)

In recent years the importance of externally imposed resonant magnetic fields on plasma has become more and more recognized. These fields will cause ergodization at well defined plasma layers and can induce large size islands at rational q-surfaces. A hope for future large scale tokamak devices is the development of a reliable method for mitigating the large ELMs of type 1 ELMy-H-modes by modifying the edge transport. Other topics of interest for fusion reactors are the option of distributing the heat to a large area and optimizing methods for heat and particle exhaust, or the understanding of the transport around tearing mode instabilities. The cluster of papers in this issue of Nuclear Fusion is a successor to the 2004 special issue (Nuclear Fusion 44 S1-122 ) intended to raise interest in the subject. The contents of this present issue are based on presentations at the Second Workshop on Stochasticity in Fusion Plasmas (SFP) held in Juelich, Germany, 15-17 March 2005. The SFP workshops have been stimulated by the installation of the Dynamic Ergodic Divertor (DED) in the TEXTOR tokamak. It has attracted colleagues working on various plasma configurations such as tokamaks, stellarators or reversed field pinches. The workshop was originally devoted to phenomena on the plasma edge but it has been broadened to transport questions over the whole plasma cross-section. It is a meeting place for experimental and theoretical working groups. The next workshop is planned for February/March 2007 in Juelich, Germany. For details see http://www.fz-juelich.de/sfp/. The content of the workshop is summarized in the following conference summary (K.H. Finken 2006 Nuclear Fusion 46 S107-112). At the workshop experimental results on the plasma transport resulting from ergodization in various devices were presented. Highlights were the results from DIII-D on the mitigation of ELMs (see also T.E. Evans et al 2005 Nuclear Fusion 45 595 ). Theoretical work was focused around the topics of mapping methods of magnetic field lines, 3D-plasma transport modelling efforts of ergodized plasmas and island divertors, and on the penetration of the external field including the resulting force transfer. We hope that the article series in Nuclear Fusion will stimulate interest in this fascinating subject of plasma physics.

Finken, K. H.

2006-04-01

421

Megawatt Electromagnetic Plasma Propulsion  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center program in megawatt level electric propulsion is centered on electromagnetic acceleration of quasi-neutral plasmas. Specific concepts currently being examined are the Magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). In the case of the MPD thruster, a multifaceted approach of experiments, computational modeling, and systems-level models of self field MPD thrusters is underway. The MPD thruster experimental research consists of a 1-10 MWe, 2 ms pulse-forming-network, a vacuum chamber with two 32 diffusion pumps, and voltage, current, mass flow rate, and thrust stand diagnostics. Current focus is on obtaining repeatable thrust measurements of a Princeton Benchmark type self field thruster operating at 0.5-1 gls of argon. Operation with hydrogen is the ultimate goal to realize the increased efficiency anticipated using the lighter gas. Computational modeling is done using the MACH2 MHD code, which can include real gas effects for propellants of interest to MPD operation. The MACH2 code has been benchmarked against other MPD thruster data, and has been used to create a point design for a 3000 second specific impulse (Isp) MPD thruster. This design is awaiting testing in the experimental facility. For the PIT, a computational investigation using MACH2 has been initiated, with experiments awaiting further funding. Although the calculated results have been found to be sensitive to the initial ionization assumptions, recent results have agreed well with experimental data. Finally, a systems level self-field MPD thruster model has been developed that allows for a mission planner or system designer to input Isp and power level into the model equations and obtain values for efficiency, mass flow rate, and input current and voltage. This model emphasizes algebraic simplicity to allow its incorporation into larger trajectory or system optimization codes. The systems level approach will be extended to the pulsed inductive thruster and other electrodeless thrusters at a future date.

Gilland, James; Lapointe, Michael; Mikellides, Pavlos

2003-01-01

422

Maxwell Prize Session: Hot Plasma Effects in Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

Radio frequency (rf) gas discharges have been known for over a century. Recently, interest in low-pressure rf discharges has been revitalized due to great achievements and expectations in using such devices in plasma processing for manufacturing of semiconductor chips and lighting technology. In rf discharges the dominant interaction of the electromagnetic field with the plasma, and thus rf power absorption, takes place in the plasma boundary layer (near the electrode sheath in a capacitive and in the skin layer in an inductive rf discharge). The interaction of the electromagnetic field with plasma can be of local or nonlocal character. In the first case, there is local coupling between the rf current and the electric field described by a local complex conductivity tensor of a cold plasma. That corresponds to traditional (collisional) gas discharge physics. In the second case, electron thermal motion brings spatial dispersion into the relation between the rf current and the electric field, so that the conductivity tensor becomes a nonlocal operator. Stochastic (collisionless) electron heating, anomalous skin effect and a variety of plasma kinetic and nonlinear effects are typical for low-pressure rf discharges operating in the regime of nonlocal electrodynamics. Such phenomena are characteristic of hot fusion and space plasmas, where they are usually observed experimentally as some global effects. The ability to reproduce these phenomena in a table-top rf discharge experiment (equipped with spatially resolved electron kinetic and electromagnetic field diagnostics) makes the rf discharge a unique playground for basic plasma studies highly amenable to theoretical analysis. The subject of this talk is a review of nonlocal and nonlinear effects found in rf discharge experiments and theoretical analysis, where the interaction of electromagnetic field with plasma is controlled by the electron thermal motion rather than the electron-atom collisions. New features in the electron energy distribution, wave phase bifurcation and phase velocity reversal, collisionless and negative power absorption, harmonic generation and ponderomotive effect are found in these experiments and interpreted in terms of non-local, hot electron electrodynamics.

Godyak, Valery

2004-11-01

423

ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma  

NASA Astrophysics Data System (ADS)

ECR type plasma system was built to produce plasma in axial direction. Plasma was initiated in a specially designed Nickel - Chrome cylindrical vacuum tube which is being driven through dielectric window by 2.45GHz commercial magnetron source. Tube is also surrounded by a coil driving 150ADC to generate approximately 875Gauss magnetic field at the center. Langmuir probe and ICCD for optical spectrometry were used to characterize internal parameters like electron density, electron temperature and different characteristics of the plasma. Bacillus Subtilis var nigar, bacillus Stearothermophilus, bacillus pumilus E601, Escherichia coli and staphylococcus aureus type bacteria were selected as a reference. Each is resistant for different actions while the Bacilus cereus is the most resistant bacteria for microwave interaction. This study presents the effect of system on used bacteria. Those are gram positive and gram negative bacteria that refers to structure of cell wall. The sterilization efficacy of Argon type ECR plasma was found to be over 99, 5% in Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis (vegetative cell), Bacillus cereus (vegetative cell), Bacillus pumilus and Escherichia coli. System response type is less than 2 minutes.

Helhel, Selcuk; Oksuz, Lutfi; Cerezci, Osman; Rad, Abbas Y.

2004-09-01

424

Characteristics of plasma properties in an ablative pulsed plasma thruster  

SciTech Connect

Pulsed plasma thrusters are electric space propulsion devices which create a highly transient plasma bulk in a short-time arc discharge that is expelled to create thrust. The transitional character and the dependency on the discharge properties are yet to be elucidated. In this study, optical emission spectroscopy and Mach-Zehnder interferometry are applied to investigate the plasma properties in variation of time, space, and discharge energy. Electron temperature, electron density, and Knudsen numbers are derived for the plasma bulk and discussed. Temperatures were found to be in the order of 1.7 to 3.1 eV, whereas electron densities showed maximum values of more than 10{sup 17} cm{sup -3}. Both values showed strong dependency on the discharge voltage and were typically higher closer to the electrodes. Capacitance and time showed less influence. Knudsen numbers were derived to be in the order of 10{sup -3}-10{sup -2}, thus, indicating a continuum flow behavior in the main plasma bulk.

Schoenherr, Tony; Nees, Frank; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, Kashiwa, Chiba 277-8561 (Japan); Herdrich, Georg [Institute of Space Systems (IRS), University of Stuttgart, 70569 Stuttgart, Baden-Wuerttemberg (Germany)

2013-03-15

425

Plasma Guns for the Plasma Liner Experiment (PLX)  

NASA Astrophysics Data System (ADS)

A spherical array of minirailgun plasma accelerators is planned for the Plasma Liner Experiment (PLX) to be located at LANL. The plasma liner would be formed via merging of 30 dense, high Mach number plasma jets (n˜10^16-17 cm-3, M˜10--35, v˜50--70 km/s, rjet˜5 cm) in a spherically convergent geometry. Small parallel-plate railguns are being developed for this purpose due to their reduced system complexity and cost, with each gun planned to operate at ˜300 kA peak current, and launching up to ˜8000 ?g of high-Z plasma using a ˜50 kJ pfn. We describe experimental development of the minirailguns and their current and projected performance. Fast operating repetitive gas valves have recently been added to allow injection of high density gases including helium, argon, and (eventually) xenon. We will present the latest test results with the high-Z gases, and discuss future plans for augmenting the rails, optimizing the nozzle configuration, preionizing the injected gas, and configuring the pulse forming networks with the capacitors available to the program.

Witherspoon, F. D.; Bomgardner, R.; Case, A.; Messer, S. J.; Brockington, S.; Wu, L.; Elton, R.; Hsu, S. C.; Cassibry, J. T.; Gilmore, M. A.

2009-11-01

426

Wakes in Inertial Fusion Plasmas  

NASA Astrophysics Data System (ADS)

Plasma wave wakes, which are the collective oscillatory response near the plasma frequency to the propagation of particles or electromagnetic waves through a plasma, play a critical role in many plasma processes. New results from backwards stimulated Raman scattering (BSRS), in which wakes with phase velocities much less than the speed of light are induced by the beating of counter-propagating light waves, and from electron beam stopping, in which the wakes are produced by the motion of relativistically propagating electrons through the dense plasma, are discussed. Both processes play important roles in Inertial Confinement Fusion (ICF). In BSRS, laser light is scattered backwards out of the plasma, decreasing the energy available to compress the ICF capsule and affecting the symmetry of where the laser energy hits the hohlraum wall in indirect drive ICF. The plasma wave wake can also generate superthermal electrons that can preheat the core and/or the ablator. Electron beam stopping plays a critical role in the Fast Ignition (FI) ICF concept, in which a beam of relativistic electrons is used to heat the target core to ignition temperatures after the compression stage. The beam stopping power determines the effectiveness of the heating process. This dissertation covers new discoveries on the importance of plasma wave wakes in both BSRS and electron beam stopping. In the SRS studies, 1D particle-in-cell (PIC) simulations using OSIRIS are performed, which model a short-duration (˜500/?0 --1FWHM) counter-propagating scattered light seed pulse in the presence of a constant pump laser with an intensity far below the absolute instability threshold for plasma waves undergoing Landau damping. The seed undergoes linear convective Raman amplification and dominates over the amplification of fluctuations due to particle discreteness. The simulation results are in good agreement with results from a coupled-mode solver when special relativity and the effects of finite size PIC simulation particles are accounted for. Linear gain spectra including both effects are discussed. Extending the PIC simulations past when the seed exits the simulation domain reveals bursts of large-amplitude scattering in many cases, which do not occur in simulations without the seed pulse. These bursts can have amplitudes several times greater than the amplified seed pulse, and an examination of the orbits of particles trapped in the wake illustrates that the bursts are caused by a reduction of Landau damping due to particle trapping. This large-amplitude scattering is caused by the seed inducing a wake earlier in the simulation, thus modifying the distribution function. Performing simulations with longer duration seeds leads to parts of the seeds reaching amplitudes several times more than the steady-state linear theory results, similarly caused by a reduction of Landau damping. Simulations with continuous seeds demonstrate that the onset of inflation depends on the seed wavelength and incident intensity, and oscillations in the reflectivity are observed at a frequency equal to the difference between the seed frequency and the frequency at which the inflationary SRS grows. In the electron beam stopping studies, 3D PIC simulations are performed of relativistic electrons with a momentum of 10mec propagating in a cold FI core plasma. Some of the simulations use one simulation particle per real particle, and particle sizes much smaller than the interparitcle spacing. The wake made by a single electron is compared against that calculated using cold fluid theory assuming the phase velocity of the wake is near the speed of light. The results agree for the first wavelength of the wake. However, the shape of the wake changes for succeeding wavelengths and depends on the background plasma temperature, with the concavity pointing in the direction the electron is moving in cold plasmas and in the opposite direction as the plasma temperature increases. In the warm plasma the curvature is described by electrostatic Vlasov theory (for vparticle >> vth) and is due

Ellis, Ian Norman

427

Recent Progress of Boundary Plasma Research 6.Recent Results in Divertor Plasma Simulators  

Microsoft Academic Search

Recent studies using the linear divertor simulators are reviewed. The experimental results regarding detached recombining plasma, convective blobby plasma transport and plasma-material interaction related to tungsten and carbon dusts are reported.

Noriyasu Ohno

2004-01-01

428

Simulation studies of anomalous slowing down of fusion products  

Microsoft Academic Search

Future fusion reactors will rely on fusion product heating of the plasma for ignited (or near-ignited) operation. One factor that could drastically change such operation would be if the fusion product alpha initiates microinstabilities during slowing down. In addition to changing heating rates, this can result in a preferential transfer of energy to fuel ions as the alphas slow down

W. R. Sutton; C. K. Choi; G. H. Miley

1982-01-01

429

The plasma-wall boundary region in negative-ion-dominated plasmas at low pressures  

Microsoft Academic Search

This paper brings together recent work in low-pressure plasmas dominated by negative ions, examining in detail the structure of the plasma-sheath boundary. The parallels between negative ion-electron plasmas and two-electron-species plasmas are drawn, as are those between probe-plasma and plasma-wall systems. Particular attention is given to the parameter region where, for the temperature ratio Te \\/ Tn greater than a

R. N. Franklin

2000-01-01

430

"Ultracold" neutral plasmas at room temperature.  

PubMed

We report a measurement of the electron temperature in a plasma generated by a high-intensity laser focused into a jet of neon. The 15 eV electron temperature is determined using an analytic solution of the plasma equations assuming local thermodynamic equilibrium, initially developed for ultracold neutral plasmas. We show that this analysis method accurately reproduces more sophisticated plasma simulations in our temperature and density range. While our plasma temperatures are far outside the typical "ultracold" regime, the ion temperature is determined by the plasma density through disorder-induced heating just as in ultracold neutral plasma experiments. Based on our results, we outline a pathway for achieving a strongly coupled neutral laser-produced plasma that even more closely resembles ultracold neutral plasma conditions. PMID:22861862

Heilmann, N; Peatross, J B; Bergeson, S D

2012-07-20

431

Non-thermal atmospheric plasmas in dentistry  

NASA Astrophysics Data System (ADS)

Non-thermal atmospheric plasmas are very efficient in the deactivation of bacteria. A relatively new area is the use of these plasmas in biomedical and dental applications. In this work, application of a novel device in dentistry is investigated, the plasma needle. The plasma needle is used to generate a non-thermal atmospheric micro-plasma. A promising application of this micro-plasma is the treatment of dental cavities, to stop caries without causing pain and removing too much healthy tissue. Various bacterial model systems are used to test the bactericidal efficiency of the plasma needle: bacteria in droplets, thin films and (multi-species) biofilms. The effects of plasma needle treatment on bacterial viability, growth and composition are discussed. The results indicate that plasma can become a useful tool for dental treatment.

Sladek, Raymond; Stoffels, Eva

2006-10-01

432

Micro-column plasma emission liquid chromatograph  

DOEpatents

In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

Gay, Don D. (Aiken, SC)

1984-01-01

433

The Madison plasma dynamo experiment: A facility for studying laboratory plasma astrophysics  

E-print Network

The Madison plasma dynamo experiment (MPDX) is a novel, versatile, basic plasma research device designed to investigate flow driven magnetohydrodynamic instabilities and other high-? phenomena with astrophysically relevant ...

Cooper, C. M.

434

Theoretical approach for plasma series resonance effect in geometrically symmetric dual radio frequency plasma  

SciTech Connect

Plasma series resonance (PSR) effect is well known in geometrically asymmetric capacitively couple radio frequency plasma. However, plasma series resonance effect in geometrically symmetric plasma has not been properly investigated. In this work, a theoretical approach is made to investigate the plasma series resonance effect and its influence on Ohmic and stochastic heating in geometrically symmetric discharge. Electrical asymmetry effect by means of dual frequency voltage waveform is applied to excite the plasma series resonance. The results show considerable variation in heating with phase difference between the voltage waveforms, which may be applicable in controlling the plasma parameters in such plasma.

Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H. [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Casilla 306, Santiago 22 (Chile)

2012-02-27

435

Autonomous Method and System for Minimizing the Magnitude of Plasma Discharge Current Oscillations in a Hall Effect Plasma Device  

NASA Technical Reports Server (NTRS)

An autonomous method for minimizing the magnitude of plasma discharge current oscillations in a Hall effect plasma device includes iteratively measuring plasma discharge current oscillations of the plasma device and iteratively adjusting the magnet current delivered to the plasma device in response to measured plasma discharge current oscillations to reduce the magnitude of the plasma discharge current oscillations.

Hruby, Vladimir (Inventor); Demmons, Nathaniel (Inventor); Ehrbar, Eric (Inventor); Pote, Bruce (Inventor); Rosenblad, Nathan (Inventor)

2014-01-01

436

Theoretical investigations of plasma processes  

NASA Technical Reports Server (NTRS)

System analyses are presented for electrically sustained, collision dominated plasma centrifuges, in which the plasma rotates under the influence of the Lorentz forces resulting from the interaction of the current density fields with an external magnetic field. It is shown that gas discharge centrifuges are technically feasible in which the plasma rotates at speeds up to 1 million cm/sec. The associated centrifugal forces produce a significant spatial isotope separation, which is somewhat perturbed in the viscous boundary layers at the centrifuge walls. The isotope separation effect is the more pronounced. The induced magnetic fields have negligible influence on the plasma rotation if the Hall coefficient is small. In the technical realization of collision dominated plasma centrifuges, a trade-off has to be made between power density and speeds of rotation. The diffusion of sputtered atoms to system surfaces of ion propulsion systems and the deposition of the atoms are treated theoretically by means of a simple model which permits an analytical solution. The problem leads to an inhomogeneous integral equation.

Wilhelm, H. E.; Hong, S. H.

1976-01-01

437

Tungsten Spectroscopy for Fusion Plasmas  

SciTech Connect

Tungsten is one of very few candidate materials for plasma facing components in future fusion devices. Therefore, investigations have been started at fusion devices and EBITs to provide atomic data for W in fusion plasmas. Usually the influx of impurities is deduced from the intensity of spectral lines from neutrals or ions in a low ionisation state. For this purpose the appropriate ionisation rates and excitation rates have to be known. At the moment, a WI transition (7S-7P) at 400.9 nm is used, but an extension of the method to other lines is under investigation. In the core of present day plasmas ionisation states up to W56+ can be reached and in a reactor states up to around W68+ will be present. In order to extract information on the local W concentrations over the whole plasma radius atomic data (wavelength, excitation, ionisation, recombination) for all the charge states up to the maximum ionisation state are necessary. Similarly, a high sensitivity has to be achieved since the central W concentrations should stay below 10-4. For an unambiguous identification of the transitions EBIT measurements are of great advantage, but due to the lower electron density compared to fusion plasmas, investigations there are indispensable.

Neu, R.; Puetterich, T.; Dux, R. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Boltzmannstr.2, 85748 Garching (Germany); Pospieszczyk, A.; Sergienko, G. [Institut fuer Plasmaphysik, Euratom Association, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany)

2007-04-06

438

Stationary Plasma Thruster Plume Emissions  

NASA Technical Reports Server (NTRS)

The emission spectrum from a xenon plasma produced by a Stationary Plasma Thruster provided by the Ballistic Missile Defense Organization (BMDO) was measured. Approximately 270 individual Xe I, Xe II, and XE III transitions were identified. A total of 250 mW of radiated optical emission was estimated from measurements taken at the thruster exit plane. There was no evidence of erosion products in the emission signature. Ingestion and ionization of background gas at elevated background pressure was detected. The distribution of excited states could be described by temperatures ranging from fractions of 1 eV to 4 eV with a high degree of uncertainty due to the nonequilibrium nature of this plasma. The plasma was over 95 percent ionized at the thruster exit plane. Between 10 and 20 percent of the ions were doubly charged. Two modes of operation were identified. The intensity of plasma emission increased by a factor of two during operation in an oscillatory mode. The transfer between the two modes of operation was likely related to unidentified phenomena occurring on a time scale of minutes.

Manzella, David H.

1994-01-01

439

Plasma Processing of Advanced Materials  

SciTech Connect

Plasma Processing of Advanced Materials The project had the overall objective of improving our understanding of the influences of process parameters on the properties of advanced superhard materials. The focus was on high rate deposition processes using thermal plasmas and atmospheric pressure glow discharges, and the emphasis on superhard materials was chosen because of the potential impact of such materials on industrial energy use and on the environment. In addition, the development of suitable diagnostic techniques was pursued. The project was divided into four tasks: (1) Deposition of superhard boron containing films using a supersonic plasma jet reactor (SPJR), and the characterization of the deposition process. (2) Deposition of superhard nanocomposite films in the silicon-nitrogen-carbon system using the triple torch plasma reactor (TTPR), and the characterization of the deposition process. (3) Deposition of films consisting of carbon nanotubes using an atmospheric pressure glow discharge reactor. (4) Adapting the Thomson scattering method for characterization of atmospheric pressure non-uniform plasmas with steep spatial gradients and temporal fluctuations. This report summarizes the results.

Heberlein, Joachim, V.R.; Pfender, Emil; Kortshagen, Uwe

2005-02-28

440

Microwave diagnostics of atmospheric plasmas  

NASA Astrophysics Data System (ADS)

Plasma treatment of biological tissues has tremendous potential due to the wide range of applications. Most plasmas have gas temperatures which greatly exceed room temperature. These are often utilized in electro-surgery for cutting and coagulating tissue. Another type of plasma, referred to as cold atmospheric plasma, or CAP, is characterized by heavy particle temperatures which are at or near room temperature. Due to this lack of thermal effect, CAP may provide less invasive medical procedures. Additionally, CAP have been demonstrated to be effective at targeting cancer cells while minimizing damage to the surrounding tissue. A recently fabricated Microwave Electron Density Device (MEDD) utilizes microwave scattering on small atmospheric plasmas to determine the electron plasma density. The MEDD can be utilized on plasmas which range from a fraction of a millimeter to several centimeters at atmospheric pressure when traditional methods cannot be applied. Microwave interferometry fails due to the small size of the plasma relative to the microwave wavelength which leads to diffraction and negligible phase change; electrostatic probes introduce very strong perturbation and are associated with difficulties of application in strongly-collisional atmospheric conditions; and laser Thomson scattering is not sensitive enough to measure plasma densities less than 1012 cm-3. The first part of this dissertation provides an overview of two types of small atmospheric plasma objects namely CAPs and plasmas utilized in the electro-surgery. It then goes on to describe the fabrication, testing and calibration of the MEDD facility. The second part of this dissertation is focused on the application of the MEDD and other diagnostic techniques to both plasma objects. A series of plasma images that illustrate the temporal evolution of a discharge created by an argon electrosurgical device operating in the coagulation mode and its behavior was analyzed. The discharge of the argon electrosurgical system was studied using an Intensified Charge-Coupled Device (ICCD) and the MEDD. The plasma density was measured and found to be in the range of (7.5-9.5) x 1015 cm-3 for applied powers of 15-60 Watts. The discharge can be classified as a glow discharge of alternating current with a contracted positive column. The discharge ignites every half-wave of the driving voltage when voltage increases above the breakdown threshold of about 300 Volts and is interrupted at the end of each half-wave when the voltage approaches zero. Additionally, it was shown that the plasma discharges on the target object during the positive half-wave of the voltage. The power distribution was also analyzed. It was found that 60-70% of the input power is delivered into the tissue and the remaining 30-40% is consumed by the plasma column between the electrosurgical probe and tissue. The application of the MEDD to a helium CAP revealed the temporal dynamics of the discharge. It was observed that streamer development associated with the measured plasma density peak is developing on the decaying part of the main inter-electrode discharge. The third part of the dissertation focuses on the simulation of a helium CAP. A one-dimensional model of a helium CAP was used to simulate twenty-one oxygen, helium, and nitrogen species. One hundred and forty reactions were successfully used. The predicted maximum and average densities of the species were tabulated. Graphs of the species densities were presented showing the change in densities with respect to the radius of the CAP. The plasma bullets can be seen via these graphs, with most species displaying maximum densities at a radius which is not the center of the CAP. This shows that the plasma bullets are a disk-like structure at the moment of time presented. Values of E/p were varied from 20 -- 30 volts/cm Torr. Based on experimental results of moments in time with which the maximum plasma density occurs, this data can be used to predict the actual E/p values for future experiments.

Scott, David

441

[Plasma properties research: Task 3  

SciTech Connect

The principal research activities of the Magneto-Fluid Dynamics Division relate to magnetic fusion plasma physics. In addition, there is a modest amount of work in closely related areas, including space plasma physics, fluid dynamics, and dynamical systems. Members of the Magneto-Fluid Dynamics Division maintain close contacts with fusion researchers in the US and abroad. Some of the work of the Division is clearly directed towards ITER and TPX, while other problems relate to the broader development of fusion plasma physics and to the support of other issues arising in the many experimental programs. Topics of some note in the last year that are discussed in this report are: Application of sophisticated statistical techniques to tokamak data reduction, including time series analysis of TFTR fluctuation data and spline analysis of profile data. Continuing development of edge plasma and divertor modelling, including initial ergodic divertor studies. Analysis of energetic fusion products losses from TFTR plasmas. Examination of anomalous transport in dynamical systems induced by chaotic-like Hamiltonian motion. Numerical simulation of the development of singular MHD equilibria. Exploration of the validity of moment expansions of kinetic equations for weakly collisional systems. Studies of RF- and ripple-induced helium ash removal. Ballooning mode studies in fluids and rotating stars. Studies in dynamical systems, including explosive instabilities, development of chaos, and motion of collisionless particles in a domain with overlapping islands.

Not Available

1992-12-31

442

[Plasma properties research: Task 3  

SciTech Connect

The principal research activities of the Magneto-Fluid Dynamics Division relate to magnetic fusion plasma physics. In addition, there is a modest amount of work in closely related areas, including space plasma physics, fluid dynamics, and dynamical systems. Members of the Magneto-Fluid Dynamics Division maintain close contacts with fusion researchers in the US and abroad. Some of the work of the Division is clearly directed towards ITER and TPX, while other problems relate to the broader development of fusion plasma physics and to the support of other issues arising in the many experimental programs. Topics of some note in the last year that are discussed in this report are: Application of sophisticated statistical techniques to tokamak data reduction, including time series analysis of TFTR fluctuation data and spline analysis of profile data. Continuing development of edge plasma and divertor modelling, including initial ergodic divertor studies. Analysis of energetic fusion products losses from TFTR plasmas. Examination of anomalous transport in dynamical systems induced by chaotic-like Hamiltonian motion. Numerical simulation of the development of singular MHD equilibria. Exploration of the validity of moment expansions of kinetic equations for weakly collisional systems. Studies of RF- and ripple-induced helium ash removal. Ballooning mode studies in fluids and rotating stars. Studies in dynamical systems, including explosive instabilities, development of chaos, and motion of collisionless particles in a domain with overlapping islands.

Not Available

1992-01-01

443

Relativistic nonlinear effects in plasmas  

NASA Astrophysics Data System (ADS)

The purpose of this article is to present a review of the nonlinear effects associated with relativistic electron-mass variation and the ponderomotive force in unmagnetized as well as magnetized plasmas. Many high-frequency waves can become unstable with respect to the electron-mass modulation and the excitation of low-frequency density fluctuations. The nonlinear equations which govern the evolution of the modulationally unstable waves are derived. The phenomena of soliton formation, radiation collapse, and profile modification are investigated. Finite amplitude theories of the envelope solitons are reviewed. In a multidimensional situation, the electromagnetic waves can undergo self-focusing. The use of the variational methods allows one to calculate the nonlinear wavenumber and radius of the self-focused laser beams. Analytical solutions for the self-trapped radiation and the three-dimensional relativistic solitons are obtained. It is found that magnetized plasmas can support the propagation of new types of ultrarelativistic electromagnetic waves. The modulational instability of the latter is analyzed. Furthermore, it is shown that the relativistic ponderomotive force in a magnetized plasma can produce large amplitude field-aligned electrostatic potentials which can effectively accelerate particles to very high energies. Finally, we consider the nonlinear propagation of intense electromagnetic waves in electron-positron plasmas. Possible applications in inertial fusion, beat-wave particle accelerator, rf heating of magnetically confined plasmas, and pulsar radiation are pointed out.

Shukla, P. K.; Rao, N. N.; Yu, M. Y.; Tsintsadze, N. L.

1986-05-01

444

Fundamental Physics within Complex Plasmas  

NASA Astrophysics Data System (ADS)

In this work, both experimental and numerical methods are used to investigate several of the fundamental processes and assumptions commonly found in an earth-based radio-frequency (RF) complex plasma discharge. First the manner in which the dust particle charge varies with the particle's height above the powered electrode is investigated. Knowledge of the dust particle charge is required to understand nearly all complex plasma experiments since it affects the dust particle's levitation height and particle-particle interactions. A fluid model which includes effects due to ion flow and electron depletion (which are significant dust charging effects within the sheath where the particles levitate) is employed to determine the plasma parameters required to calculate the dust particle charge. Second, the levitation limits of the dust particles and the structure of the sheath are investigated. The CASPER GEC RF reference cell is used to perform two experiments: one to measure the dust levitation height as a function of applied RF voltage and one to determine the electric force profile. The fluid model is then used to interpret the experimental results. This study provides a better understanding of the sheath structure, particle behavior within the sheath, and provides a new, in situ experimental method for locating the approximate height of the sheath edge in any dusty plasma system. Finally, both molecular dynamics (MD) simulations and an experiment are employed to determine the physical processes that a complex plasma system goes through as it rapidly transitions from a liquid to solid state.

Douglass, Angela Michelle

445

The plasma environment of Uranus  

NASA Technical Reports Server (NTRS)

An overview of the observational results on the plasma environment at Uranus is given, and the implications of these observations for magnetospheric physics at Uranus are discussed. During the Voyager 2 encounter with Uranus, an extended magnetosphere filled with a tenuous plasma was detected. This low-energy plasma was found to consist of protons and electrons, with no significant heavy ion contribution, and with a density in the regions sampled by the spacecraft of at most three electrons per cubic centimeter. The plasma electrons and ions exhibit both a thermal component (with temperatures of tens of eV) and a hot component (with temperatures of a few keV). The thermal ion component is observed both inside and outside an L-shell value near 5, whereas the hot ion and electron component is excluded from the region inside of that L-shell. The source of the thermal component of the plasma is either the planetary ionosphere or the neutral hydrogen corona surrounding Uranus, whereas the hot component is convected in from the magnetotail, with probably an ionospheric source.

Belcher, J. W.; Mcnutt, R. L., Jr.; Richardson, J. D.; Selesnick, R. S.; Sittler, E. C., Jr.; Bagenal, F.

1991-01-01

446

Relativistic Laser-Plasma Interactions  

SciTech Connect

Ever since the much acclaimed paper of Akhiezer and Polovin plasma theorists have been attempting to comprehend complex dynamics related to the propagation of high and ultra-high intensity electromagnetic (EM) radiation through a plasma. This topic was successfully revisited a number of years later by Kaw and Dawson whose analysis threw more light on the propagation of coupled longitudinal-transverse waves of arbitrary intensity. The high phase velocity case was soon solved exactly by Max and Perkins, (early review). The problem of relativistic laser-plasma interactions is of particular interest concerning the fast ignition concept, relevant to contemporary laser inertial confinement fusion research. Moreover, the understanding of relativistic laser pulse evolution in a plasma is basic to many new applications, including optical-field-ionized x-ray lasers, plasma-based electron accelerator schemes, as well as, interpretation of some astrophysical phenomena, and references, therein). From a text given in two tutorial lectures, in a limited space, we mainly focus on an important paradigm of stimulated Raman scattering.

Skoric, Milos M. [National Institute for Fusion Science, Graduate University of Advanced Studies, Toki-shi (Japan)

2009-11-10

447

EDITORIAL: Focus on Plasma Medicine  

NASA Astrophysics Data System (ADS)

'Plasma Healthcare' is an emerging interdisciplinary research topic of rapidly growing importance, exploring considerable opportunities at the interface of plasma physics, chemistry and engineering with life sciences. Some of the scientific discoveries reported so far have already demonstrated clear benefits for healthcare in areas of medicine, food safety, environmental hygiene, and cosmetics. Examples include ongoing studies of prion inactivation, chronic wound treatment and plasma-mediated cancer therapy. Current research ranges from basic physical processes, plasma chemical design, to the interaction of plasmas with (i) eukaryotic (mammalian) cells; (ii) prokaryotic (bacteria) cells, viruses, spores and fungi; (iii) DNA, lipids, proteins and cell membranes; and (iv) living human, animal and plant tissues in the presence of biofluids. Of diverse interests in this new field is the need for hospital disinfection, in particular with respect to the alarming increase in bacterial resistance to antibiotics, the concomitant needs in private practices, nursing homes etc, the applications in personal hygiene—and the enticing possibility to 'design' plasmas as possible pharmaceutical products, employing ionic as well as molecular agents for medical treatment. The 'delivery' of the reactive plasma agents occurs at the gaseous level, which means that there is no need for a carrier medium and access to the treatment surface is optimal. This focus issue provides a close look at the current state of the art in Plasma Medicine with a number of forefront research articles as well as an introductory review. Focus on Plasma Medicine Contents Application of epifluorescence scanning for monitoring the efficacy of protein removal by RF gas-plasma decontamination Helen C Baxter, Patricia R Richardson, Gaynor A Campbell, Valeri I Kovalev, Robert Maier, James S Barton, Anita C Jones, Greg DeLarge, Mark Casey and Robert L Baxter Inactivation factors of spore-forming bacteria using low-pressure microwave plasmas in an N2 and O2 gas mixture M K Singh, A Ogino and M Nagatsu Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma H J Lee, C H Shon, Y S Kim, S Kim, G C Kim and M G Kong The acidification of lipid film surfaces by non-thermal DBD at atmospheric pressure in air A Helmke, D Hoffmeister, N Mertens, S Emmert, J Schuette and W Vioel Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet D L Bayliss, J L Walsh, G Shama, F Iza and M G Kong The effect of low-temperature plasma on bacteria as observed by repeated AFM imaging René Pompl, Ferdinand Jamitzky, Tetsuji Shimizu, Bernd Steffes, Wolfram Bunk, Hans-Ulrich Schmidt, Matthias Georgi, Katrin Ramrath, Wilhelm Stolz, Robert W Stark, Takuya Urayama, Shuitsu Fujii and Gregor Eugen Morfill Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure Mi Hee Lee, Bong Joo Park, Soo Chang Jin, Dohyun Kim, Inho Han, Jungsung Kim, Soon O Hyun, Kie-Hyung Chung and Jong-Chul Park Cell permeabilization using a non-thermal plasma M Leduc, D Guay, R L Leask and S Coulombe Physical and biological mechanisms of direct plasma interaction with living tissue Danil Dobrynin, Gregory Fridman, Gary Friedman and Alexander Fridman Nosocomial infections-a new approach towards preventive medicine using plasmas G E Morfill, T Shimizu, B Steffes and H-U Schmidt Generation and transport mechanisms of chemical species by a post-discharge flow for inactivation of bacteria Takehiko Sato, Shiroh Ochiai and Takuya Urayama Low pressure plasma discharges for the sterilization and decontamination of surfaces F Rossi, O Kylián, H Rauscher, M Hasiwa and D Gilliland Contribution of a portable air plasma torch to rapid blood coagulation as a method of preventing bleeding S P Kuo, O Tarasenko, J Chang, S Popovic, C Y Chen, H W Fan, A Scott, M Lahiani, P Alusta, J D Drake and M Nikolic A two-dimensional cold atmospheric plasma jet array for uniform treatment of large-area

Morfill, G. E.; Kong, M. G.; Zimmermann, J. L.

2009-11-01

448

Comprehensive computational model for thermal plasma processing  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. The overall computational model is embodied in a new computer code called LAVA. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Plasma-particle interactions including turbulent dispersion have been modeled in a fully self- consistent manner. 17 refs.

Chang, C.H.

1992-01-01

449

Comprehensive computational model for thermal plasma processing  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. The overall computational model is embodied in a new computer code called LAVA. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Plasma-particle interactions including turbulent dispersion have been modeled in a fully self- consistent manner. 17 refs.

Chang, C.H.

1992-08-01

450

Plasma Channels and Accelerator Applications -- A Tutorial  

SciTech Connect

A plasma channel is a narrow preionized column of plasma that can be used for a number of accelerator applications. Plasma channels play a crucial role in the laser wakefield accelerator (LWFA), where they may provide the acceleration medium as well as guiding of the intense laser pulse and accelerated electron bunch. This paper will review methods for producing plasma channels, optical guiding in channels, and the application of channels to the LWFA. The potential advantages of using long plasma channels in the plasma wakefield accelerator (PWFA) will also be discussed.

Hubbard, Richard F. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5346 (United States)

2006-11-27

451

Ferrite Loaded DBD Plasma Device  

NASA Astrophysics Data System (ADS)

An atmospheric pressure plasma jet device with dielectric barrier discharge was built using low cost 5C22 thyratron valve and ferrite transformer. The ferrite transformer increases the intensity about four times the primary pulse and lengthens the high voltage pulse, keeping the rise time of the thyratron pulse. Spectrometer measurement shows excited nitrogen molecular emissions of second positive system. The most intense nitrogen molecular line, 357.69 nm, was chosen to monitor the time dependence of the discharge. Synthetic temperature, using 380.49 nm line of N2 emission and SpecAir simulation, shows plasma gas temperature of 300 K. To corroborate this low temperature, the plasma jet is applied to human tongue with no harm or bad physical feeling.

Machida, M.

2015-02-01

452

Transport coefficients of quantum plasmas  

SciTech Connect

Transport coefficients of fully ionized plasmas with a weakly coupled, completely degenerate electron gas and classical ions with a wide range of coupling strength are expressed within the Bloch transport equation. Using the Kohler variational principle the collision integral of the quantum Boltzmann equation is derived, which accounts for quantum effects through collective plasma oscillations. The physical implications of the results are investigated through comparisons with other theories. For practical applications, electrical and thermal conductivities are derived in simple analytical formulas. The relation between these two transport coefficients is expressed in an explicit form, giving a generalized Wiedemann-Franz law, where the Lorentz ratio is a dependent function of the coupling parameter and the degree of degeneracy of the plasma.

Bennaceur, D.; Khalfaoui, A.H. (Centre de Developpement des Technologies Avancees/Secretariat d'Etat a la Recherche Scientifique et l'Environment, Laboratoire de Fusion Thermonucleaire, 2 boulevard Frantz Fanon, Boite Postale 1017 Alger-gare (Algeria))

1993-09-01

453

A dense plasma ultraviolet source  

NASA Technical Reports Server (NTRS)

The intense ultraviolet emission from the NASA Hypocycloidal-Pinch (HCP) plasma is investigated. The HCP consists of three disk electrodes whose cross section has a configuration similar to the cross section of a Mather-type plasma focus. Plasma foci were produced in deuterium, helium, xenon, and krypton gases in order to compare their emission characteristics. Time-integrated spectra in the wavelength range from 200 nm to 350 nm and temporal variations of the uv emission were obtained with a uv spectrometer and a photomultiplier system. Modifications to enhance uv emission in the iodine-laser pump band (250 to 290 nm) and preliminary results produced by these modifications are presented. Finally, the advantages of the HCP as a uv over use of conventional xenon lamps with respect to power output limit, spectral range, and lifetime are discussed.

Lee, J. H.; Mcfarland, D. R.

1978-01-01

454

Lagrangian description of warm plasmas  

NASA Technical Reports Server (NTRS)

Efforts are described to extend the averaged Lagrangian method of describing small signal wave propagation and nonlinear wave interaction, developed by earlier workers for cold plasmas, to the more general conditions of warm collisionless plasmas, and to demonstrate particularly the effectiveness of the method in analyzing wave-wave interactions. The theory is developed for both the microscopic description and the hydrodynamic approximation to plasma behavior. First, a microscopic Lagrangian is formulated rigorously, and expanded in terms of perturbations about equilibrium. Two methods are then described for deriving a hydrodynamic Lagrangian. In the first of these, the Lagrangian is obtained by velocity integration of the exact microscopic Lagrangian. In the second, the expanded hydrodynamic Lagrangian is obtained directly from the expanded microscopic Lagrangian. As applications of the microscopic Lagrangian, the small-signal dispersion relations and the coupled mode equations are derived for all possible waves in a warm infinite, weakly inhomogeneous magnetoplasma, and their interactions are examined.

Kim, H.

1970-01-01

455

Plasma Panel Based Radiation Detectors  

SciTech Connect

The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels (PDPs). It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in PDPs, it uses non-reactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (< 50 m RMS) and low cost. In this paper we report here on prototype PPS experimental results in detecting betas, protons and cosmic muons, and we extrapolate on the PPS potential for applications including detection of alphas, heavy-ions at low to medium energy, thermal neutrons and X-rays.

Friedman, Dr. Peter S. [Integrated Sensors, LLC; Varner Jr, Robert L [ORNL; Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Bentefour, E [Ion Beam Applications; Levin, Daniel S. [University of Michigan; Moshe, M. [Tel Aviv University; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Zhou, Bing [University of Michigan

2013-01-01

456

Constricted glow discharge plasma source  

DOEpatents

A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.

Anders, Andre (Albany, CA); Anders, Simone (Albany, CA); Dickinson, Michael (San Leandro, CA); Rubin, Michael (Berkeley, CA); Newman, Nathan (Winnetka, IL)

2000-01-01

457

The Quark Gluon Pion Plasma  

E-print Network

While it is commonly believed that there is a {\\it direct} transition from the hadronic to a quark gluon phase at high temperature, it would be prejudicial to rule out a sequence of dynamically generated intermediate scales. Using as guide, an effective lagrangian with unconfined gluons and constituent quarks, interacting with a chiral multiplet, we examine a scenario in which the system undergoes first-order transitions at $ T_{comp}$, the compositeness scale of the pions, at $T_{\\chi}$, the scale for spontaneous chiral symmetry breaking, and at $T_c$, the confinement temperature. We find that at current energies, it is likely that the formation temperature of the plasma, $ T_0 < T_{comp} $, and that this is therefore a quark gluon pion plasma (QGPP) rather than the usual quark gluon plasma (QGP). We propose some dilepton-related signatures of this scenario.

Vikram Soni; Moninder Singh Modgil; Desdeep Sahdev

2002-12-02

458

Plasma-catalyzed fuel reformer  

DOEpatents

A reformer is disclosed that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding method and system are also disclosed and claimed herein.

Hartvigsen, Joseph J.; Elangovan, S.; Czernichowski, Piotr; Hollist, Michele

2013-06-11

459

Nonlinear dynamics and plasma transport  

SciTech Connect

This progress report details work done on a program in nonlinear dynamical aspects of plasma turbulence and transport funded by DOE since 1989. This program has been in cooperation with laboratories in theUSSR [now Russia and the Confederation of Independent States (CIS)]. The purpose of this program has been: To promote the utilization of recent pathbreaking developments in nonlinear science in plasma turbulence and transport. To promote cooperative scientific investigations between the US and CIS in the related areas of nonlinear science and plasma turbulence and transport. In the work reported in our progress report, we have studied simple models which are motivated by observation on actual fusion devices. The models focus on the important physical processes without incorporating the complexity of the geometry of real devices. This allows for a deeper analysis and understanding of the system both analytically and numerically.

Antonsen, T.M. Jr.; Drake, J.F.; Finn, J.M.; Guzdar, P.N.; Hassam, A.B.; Sageev, R.Z.

1993-01-01

460

Impulsive Magnetic Reconnection in Plasma  

NASA Astrophysics Data System (ADS)

Transient effect of magnetic reconnection has been investigated in the TS-4 torus plasma merging device. The two loop merging with pull reconnection converts one common flux to two private fluxes. Under strongly driven inflow, the plasma and magnetic flux inflow exceeded the outflow ones, causing flux and density piled-up in the current sheet. This pile-up effect was found to increase the inflow speed without anomalous resistivity effect. Under strong guiding field, a plasmoid grew in the current sheet during plasma pile-up. When flux pile-up reached a critical value, the plasmoid was ejected from the reconnection region and the reconnection speed transiently increased. The plasmoid ejection made the reconnection rate maximum when its acceleration was maximized.

Hayashi, Yoshinori; , Toru, II; Inomoto, Michiaki; Ono, Yasushi

461

The plasma wave echo revisited  

SciTech Connect

Temporal plasma wave echoes are investigated by solving the Vlasov-Poisson system numerically in detail. The time of appearance and the structure of the echoes, including that of the higher harmonics and the dependence on the time between the excitations, are found to agree well with that from theory and/or experiments. Although Landau damping strongly depends on the small number of in-phase (with the excited plasma waves) electrons, the latter do not noticeably affect echo formation even after they become trapped in the small but finite wave field. As expected, when one or both of the excitations become too strong, the number of trapped particles can become so large that the plasma echo ceases to exist.

Hou, Y. W. [Institute of Plasma Physics, CAS, Hefei, Anhui 230031 (China); Ma, Z. W. [Institute of Plasma Physics, CAS, Hefei, Anhui 230031 (China); Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Yu, M. Y. [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany)

2011-01-15

462

Coupled microwave ECR and radio-frequency plasma source for plasma processing  

DOEpatents

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm.sup.2 at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance.

Tsai, Chin-Chi (Oak Ridge, TN); Haselton, Halsey H. (Knoxville, TN)

1994-01-01

463

Coupled microwave ECR and radio-frequency plasma source for plasma processing  

DOEpatents

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm[sup 2] at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance. 4 figures.

Tsai, C.C.; Haselton, H.H.

1994-03-08

464

Plasma sheet expansion: Statistical characteristics  

NASA Astrophysics Data System (ADS)

The present study addresses the cause of plasma sheet expansion by statistically comparing the characteristics of lobe-to-plasma sheet (LB-to-PS) and PS-to-LB crossings observed by the Geotail satellite. Whereas the flapping motion of the magnetotail causes both types of crossing, the PS expansion (thinning) can be associated only with the LB-to-PS (PS-to-LB) crossing. Thus any systematic difference between the two types of crossing should reflect the difference between the PS expansion and thinning. Geotail observed more LB-to-PS crossings (744 events) than PS-to-LB crossings (640 events), and the preferred occurrence of the LB-to-PS crossing is more manifest closer to the Earth. It is found that at the PS-to-LB crossing, the plasma moves in the same direction as the boundary motion. At the LB-to-PS crossing, in contrast, the plasma often moves in the opposite direction to the boundary motion, indicating that there is a finite electric field in the frame of the boundary motion associated with the PS expansion. The PS expansion is therefore considered to be a manifestation of magnetic reconnection. That is, the PS expands because new PS flux tubes are added onto the preexisting PS. In the course of the PS expansion, the total pressure decreases, which may be interpreted in terms of the replacement of the preexisting PS plasma with new low-pressure plasma originating from the tail lobe. The PS expansion is also characterized by relaxation (dipolarization) of the local magnetic field, which is inferred to be a direct consequence of reconnection. On the basis of recent reports of the lack of a one-to-one correspondence between reconnection and substorm onset, it is suggested that the PS expansion cannot be uniquely associated with a specific substorm phase.

Ohtani, S.; Mukai, T.

2006-05-01

465

Food Predictors of Plasma Carotenoids  

PubMed Central

Empirical prediction models that weight food frequency questionnaire (FFQ) food items by their relation to nutrient biomarker concentrations may estimate nutrient exposure better than nutrient intakes derived from food composition databases. Carotenoids may especially benefit because contributing foods vary in bioavailability and assessment validity. Our objective was to develop empirical prediction models for the major plasma carotenoids and total carotenoids and evaluate their validity compared with dietary intakes calculated from standard food composition tables. 4180 nonsmoking women in the Nurses’ Health Study (NHS) blood subcohort with previously measured plasma carotenoids were randomly divided into training (n = 2787) and testing (n = 1393) subsets. Empirical prediction models were developed in the training subset by stepwise selection from foods contributing ?0.5% to intake of the relevant carotenoid. Spearman correlations between predicted and measured plasma concentrations were compared to Spearman correlations between dietary intake and measured plasma concentrations for each carotenoid. Three to 12 foods were selected for the ?-carotene, ?-carotene, ?-cryptoxanthin, lutein/zeaxanthin, lycopene, and total carotenoids prediction models. In the testing subset, Spearman correlations with measured plasma concentrations for the calculated dietary intakes and predicted plasma concentrations, respectively, were 0.31 and 0.37 for ?-carotene, 0.29 and 0.31 for ?-carotene, 0.36 and 0.41 for ?-cryptoxanthin, 0.28 and 0.31 for lutein/zeaxanthin, 0.22 and 0.23 for lycopene, and 0.22 and 0.27 for total carotenoids. Empirical prediction models may modestly improve assessment of some carotenoids, particularly ?-carotene and ?-cryptoxanthin. PMID:24152746

Hendrickson, Sara J.; Willett, Walter C.; Rosner, Bernard A.; Eliassen, A. Heather

2013-01-01

466

Evaporative cooling of flare plasma  

NASA Technical Reports Server (NTRS)

A one-dimensional loop model for the evaporative cooling of the coronal flare plasma was investigated. Conductive losses dominated radiative cooling, and the evaporative velocities were small compared to the sound speed. The profile and evolution of the temperature were calculated. The model was in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation was to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.

Antiochos, S. K.; Sturrock, P. A.

1976-01-01

467

Analysis of the plasma sweeper  

SciTech Connect

The coupling of lower hybrid waves to a plasma can be modified by placing potentials on electrodes near the mouth of a phased array. Positive potentials on the electrodes create an electric field that sweeps the plasma away at a velocity c anti E x anti B/B/sup 2/. In this paper we derive the electric field created by the applied potential from the nondivergent character of the current flow and the ion momentum equation, in which ion-neutral charge-exchange collisions are retained, and we compare the predictions with experimental data.

Glanz, J.; Motley, R.W.

1982-09-01

468

Experimental study of plasma window  

E-print Network

Plasma window is an advanced apparatus which can work as the interface between vacuum and high pressure region. It can be used in many applications which need atmosphere-vacuum interface, such as gas target, electron beam welding, synchrotron radiation and spallation neutron source. A test bench of plasma window is constructed in Peking University. A series of experiments and corresponding parameter measurements have been presented in this article. The experiment result indicates the feasibility of such a facility acting as an interface between vacuum and high pressure region.

Ben-Liang, Shi; Kun, Zhu; Yuan-Rong, Lu

2013-01-01

469

Bilirubin quantitation with lipemic plasma.  

PubMed

1. In the presence of lipemia, the estimation of BR by diazo method is variable and hence unreliable. 2. The estimation of BR in lipemic plasma by the use of the A-O bilirubinometer yielded BR levels which were consistently lower than theoretical values. 3. By regression analysis of the percent error in BR estimation, (using the A-O bilirubinometer) and TG Concentrations, a straight line is obtained. Based upon this line, a correction factor for plasma BR concentration in the range of 5-25 mg/dl can be obtained if the degree of lipemia is known. PMID:1261006

Chan, G; Merrills, K; Schiff, D

1976-04-01

470

Dynamics of colliding ultracold plasmas  

NASA Astrophysics Data System (ADS)

Formation of a secondary plasma of NO+ ions and electrons within an ultracold plasma produces an observable change in the hydrodynamics of the system. Direct photoionization adds energetic electrons, which increases the rate of expansion. The introduction of a secondary Rydberg gas has the opposite effect. In both cases, the added ions create an inertial drag that acts initially to retard the expansion of the electron gas. A cold-ion hydrodynamic shell model, which accounts well for the effect of energy added by photoionization electrons, predicts the formation of collisionless shock waves.

Morrison, J. P.; Grant, E. R.

2015-02-01

471

Relativistic effects on plasma expansion  

SciTech Connect

The expansion of electron-ion plasma is studied through a fully relativistic multi-fluids plasma model which includes thermal pressure, ambipolar electrostatic potential, and internal energy conversion. Numerical investigation, based on quasi-neutral assumption, is performed for three different regimes: nonrelativistic, weakly relativistic, and relativistic. Ions' front in weakly relativistic regime exhibits spiky structure associated with a break-down of quasi-neutrality at the expanding front. In the relativistic regime, ion velocity is found to reach a saturation limit which occurs at earlier stages of the expansion. This limit is enhanced by higher electron velocity.

Benkhelifa, El-Amine; Djebli, Mourad, E-mail: mdjebli@usthb.dz [USTHB, Faculty of Physics, Theoretical Physics Laboratory, B.P. 32 Bab-Ezzouar, 16079 Algiers (Algeria)

2014-07-15

472

Plasma diagnostic systems for Hall-effect plasma thrusters  

Microsoft Academic Search

A joint programme, involving research laboratories from CNRS (Centre National de le Recherche Scientifique) and ONERA (Office National de Recherches Aérospatiales), was developed in France in connection with the French Space Agency (CNES) and industry (SNECMA) for the understanding of Hall-effect plasma thrusters. Different activities are pursued in parallel: an experimental test of different laboratories' thrusters; the development of diagnostic

M. Touzeau; M. Prioul; S. Roche; N. Gascon; C. Pérot; F. Darnon; S. Béchu; C. Philippe-Kadlec; L. Magne; P. Lasgorceix; D. Pagnon; A. Bouchoule; M. Dudeck

2000-01-01