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1

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

NASA Astrophysics Data System (ADS)

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.; Roach, C. M.; Skipp, J. M.; Wilson, H. R.

2014-01-01

2

Two and three dimensional particle simulation models for study of plasma microinstabilities  

SciTech Connect

Two and three dimensional particle simulation models suitabe for the study of low frequency instabilities in inhomogeneous magnetized plasmas are described. Using the guiding center approximation for electrons transverse to the magentic field and exact electron dynamics parallel, as well as full ion dynamics, the necessary physics is included to study a class of microinstabilities known as drift waves (the universal mode). Applications of the model to studies of drift wave stability in sheared fields with single and multiple rational surfaces are discussed.

Sydora, R.D.; Leboeuf, J.N.; Tajima, T.

1985-09-01

3

Unified fluid/kinetic description of plasma microinstabilities. Part I: Basic equations in a sheared slab geometry  

SciTech Connect

Unified fluid/kinetic equations for the plasma perturbed density ({ital {tilde n}}), parallel flow velocity ({ital {tilde u}}{sub {parallel}}) and temperature ({ital {tilde T}}) are developed in a sheared slab geometry by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) nonlinear perturbed fluid equations for {ital {tilde n}}, {ital {tilde u}}{sub {parallel}} and {ital {tilde T}} is developed using a drift ordering analysis and a new gyroviscous force ((spec. char. missing){center dot}{Pi}{sub {ital g}}). Thereafter, to develop linear closure relations for {bold b}{center dot}{del}{center dot}{tilde {Pi}}{sub {parallel}} and {ital {tilde q}}{sub {parallel}}, a drift-kinetic version of a new Chapman--Enskog-like (CEL) equation is developed and solved by using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms). The resultant closure relations for {bold b}{center dot}(spec. char. missing){center dot}{tilde {Pi}}{sub {parallel}} and {ital {tilde q}}{sub {parallel}} unify the fluid and kinetic approaches. In the collisional fluid limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that this new CEL approach is more compatible with a fluidlike description of plasmas than the usual drift/gyrokinetic approach. Remarkably simplified forms of the closure relations are presented. The results are compared with other Landau damping models and shown to be more accurate, complete, and physically realistic. Applications of this set of equations to various microinstabilities in tokamak plasmas are presented in a separate paper (Part II) (Phys. Fluids B {bold 4}, 1182 (1992)).

Chang, Z.; Callen, J.D. (Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706-1687 (United States))

1992-05-01

4

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

5

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

6

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

7

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

8

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

9

Microinstabilities at perpendicular collisionless shocks: A comparison of full particle simulations with different ion to electron mass ratio  

NASA Astrophysics Data System (ADS)

A full particle simulation study is carried out for studying microinstabilities generated at the shock front of perpendicular collisionless shocks. The structure and dynamics of shock waves are determined by Alfvén Mach number and plasma beta, while microinstabilities are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the plasma-to-cyclotron frequency. Thus, growth rates of microinstabilities are changed by the ion-to-electron mass ratio, even with the same Mach number and plasma beta. The present two-dimensional simulations show that the electron cyclotron drift instability is dominant for a lower mass ratio, and electrostatic electron cyclotron harmonic waves are excited. For a higher mass ratio, the modified two-stream instability is dominant and oblique electromagnetic whistler waves are excited, which can affect the structure and dynamics of collisionless shocks by modifying shock magnetic fields.

Umeda, Takayuki; Kidani, Yoshitaka; Matsukiyo, Shuichi; Yamazaki, Ryo

2012-04-01

10

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

11

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

12

Survey of microinstability and simulated turbulent transport in NSTX  

NASA Astrophysics Data System (ADS)

Linear gyrokinetic simulations demonstrate a large variety of microinstabilities are possible in NSTX. Microtearing modes are often unstable in the core region (r/a=0.5-0.8) of NBI heated H-modes. In cases without Lithium wall conditioning, the local ExB shearing rates are larger than linear growth rates (r/a=0.5-0.6). Instead, the ETG instability (at electron scales) is unstable; nonlinear simulations in this region will be presented. Farther out (r/a=0.7-0.8), and in plasmas with Lithium wall conditioning, other ion scale instabilities can co-exist with, or dominate, microtearing modes. The nature of these ballooning modes is complicated and can exhibit ITG/TEM or KBM behavior depending on the MHD alpha parameter (?MHD=-q^2R??). In limited cases tearing-parity ITG modes have also been identified. While non-linear simulations of these ``mixed-mode'' conditions are challenging, first attempts are underway. This work is supported by US DOE contract DE-AC02-09CH11466.

Guttenfelder, Walter; Candy, Jeff; Kaye, Stanley; Bell, Ronald; Leblanc, Benoit; Ren, Yang; Yuh, Howard

2012-10-01

13

Collisionless microinstabilities in stellarators. II. Numerical simulations  

NASA Astrophysics Data System (ADS)

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.

2013-12-01

14

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

15

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

16

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

17

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

18

Collisionality dependence of the quasilinear particle flux due to microinstabilities  

SciTech Connect

The collisionality dependence of the quasilinear particle flux due to the ion temperature gradient (ITG) and trapped electron mode (TEM) instabilities is studied by including electron collisions modeled by a pitch-angle scattering collision operator in the gyrokinetic equation. The inward transport due to ITG modes is caused mainly by magnetic curvature and thermodiffusion and can be reversed as electron collisions are introduced, if the plasma is far from marginal stability. However, if the plasma is close to marginal stability, collisions may even enhance the inward transport. The sign and the magnitude of the transport are sensitive to the form of the collision operator, to the magnetic drift normalized to the real frequency of the mode, and to the density and temperature scale lengths. These analytical results are in agreement with previously published gyrokinetic simulations. Unlike the ITG-driven flux, the TEM-driven flux is expected to be outwards for conditions far from marginal stability and inwards otherwise.

Fueloep, T.; Pusztai, I. [Department of Radio and Space Science, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden); Helander, P. [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany)

2008-07-15

19

A comprehensive gyrokinetic description of global electrostatic microinstabilities in a tokamak  

SciTech Connect

It is believed that low frequency microinstabilities such as ion temperature gradient (ITG) driven modes and trapped electron modes (TEMs) are largely responsible for the experimentally observed anomalous transport via the ion and electron channels in a tokamak. In the present work, a comprehensive global linear gyrokinetic model incorporating fully kinetic (trapped and passing) electrons and ions, actual ion to electron mass ratio, radial coupling, and profile variation is used to investigate the ITG driven modes and pure TEMs. These modes are found to exhibit multiscale structures in the presence of nonadiabatic passing electrons. The multiscale structure is related to the large nonadiabaticity of electrons in the vicinity of mode rational magnetic surfaces and leads to reduced mixing length estimates of transport compared to those obtained from adiabatic electron models.

Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Brunner, S.; Vaclavik, J.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Angelino, P. [Association Euratom-CEA, CEA/DSM/DRFC, Cadarache, 13108 St. Paul-lez-Durance (France)

2009-05-15

20

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

21

Gyrokinetic Calculations of Microinstabilities and Transport During RF H-Modes on Alcator C-Mod  

SciTech Connect

Physics understanding for the experimental improvement of particle and energy confinement is being advanced through massively parallel calculations of microturbulence for simulated plasma conditions. The ultimate goal, an experimentally validated, global, non-local, fully nonlinear calculation of plasma microturbulence is still not within reach, but extraordinary progress has been achieved in understanding microturbulence, driving forces and the plasma response in recent years. In this paper we discuss gyrokinetic simulations of plasma turbulence being carried out to examine a reproducible, H-mode, RF heated experiment on the Alcator CMOD tokamak3, which exhibits an internal transport barrier (ITB). This off axis RF case represents the early phase of a very interesting dual frequency RF experiment, which shows density control with central RF heating later in the discharge. The ITB exhibits steep, spontaneous density peaking: a reduction in particle transport occurring without a central particle source. Since the central temperature is maintained while the central density is increasing, this also suggests a thermal transport barrier exists. TRANSP analysis shows that ceff drops inside the ITB. Sawtooth heat pulse analysis also shows a localized thermal transport barrier. For this ICRF EDA H-mode, the minority resonance is at r/a * 0.5 on the high field side. There is a normal shear profile, with q monotonic.

M.H. Redi; C. Fiore; P. Bonoli; C. Bourdelle; R. Budny; W.D. Dorland; D. Ernst; G. Hammett; D. Mikkelsen; J. Rice; S. Wukitch

2002-06-18

22

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

23

Hybrid particle-fluid approach to low-frequency turbulence in magnetically confined plasmas  

SciTech Connect

We have developed a hybrid particle-fluid computer model for quasineutral microinstabilities in magnetically confined plasmas. The ions are treated in the fluid approximation. The electrons are taken as guiding-center macroparticles. The model has been extensively tested for frequency and fluctuation spectra. Linear and nonlinear studies of drift waves, /eta//sub i/ modes, interchange modes, and trapped electron modes have also been carried out. 4 refs., 3 figs.

Leboeuf, J.N.; Fowler, R.H.; Han, J.H.; Lyster, P.M.

1989-01-01

24

Stellarator and tokamak plasmas: a comparison  

NASA Astrophysics Data System (ADS)

An overview is given of physics differences between stellarators and tokamaks, including magnetohydrodynamic equilibrium, stability, fast-ion physics, plasma rotation, neoclassical and turbulent transport and edge physics. Regarding microinstabilities, it is shown that the ordinary, collisionless trapped-electron mode is stable in large parts of parameter space in stellarators that have been designed so that the parallel adiabatic invariant decreases with radius. Also, the first global, electromagnetic, gyrokinetic stability calculations performed for Wendelstein 7-X suggest that kinetic ballooning modes are more stable than in a typical tokamak.

Helander, P.; Beidler, C. D.; Bird, T. M.; Drevlak, M.; Feng, Y.; Hatzky, R.; Jenko, F.; Kleiber, R.; Proll, J. H. E.; Turkin, Yu; Xanthopoulos, P.

2012-12-01

25

Plasma Density Measurements in the Large Experiment on Instabilities and Anisotropies  

NASA Astrophysics Data System (ADS)

An RF compensated Langmuir probe has been constructed for initial measurements of the plasma density and electron temperature in the Large Experiment on Instabilities and Anisotropies (LEIA) at West Virginia University. LEIA is designed to produce space-relevant plasmas for investigations of collisionless microinstabilities. The Langmuir probe is absolutely calibrated against a microwave reflectometer system. The dependence of the plasma parameters in LEIA on the plasma source RF power, fill pressure, and gas species will be presented. Work supported by the U.S. Department of Energy and the National Science Foundation

Badeau, Allen E., Jr.; Balkey, Matthew M.; Keiter, Paul A.; Kline, John L.; Scime, Earl E.

1997-11-01

26

Magnetic insulation of secondary electrons in plasma source ion implantation  

SciTech Connect

The uncontrolled loss of accelerated secondary electrons in plasma source ion implantation (PSII) can significantly reduce system efficiency and poses a potential x-ray hazard. This loss might be reduced by a magnetic field applied near the workpiece. The concept of magnetically-insulated PSII is proposed, in which secondary electrons are trapped to form a virtual cathode layer near the workpiece surface where the local electric field is essentially eliminated. Subsequent electrons that are emitted can then be reabsorbed by the workpiece. Estimates of anomalous electron transport from microinstabilities are made. Insight into the process is gained with multi-dimensional particle-in-cell simulations.

Rej, D.J.; Wood, B.P.; Faehl, R.J. [Los Alamos National Lab., NM (United States); Fleischmann, H.H. [Cornell Univ., Ithaca, NY (United States). Dept. of Applied Physics

1993-09-01

27

Effect of alpha drift and instabilities on tokamak plasma edge conditions  

SciTech Connect

As suprathermal fusion products slow down in a Tokamak, their average drift is inward. The effect of this drift on the alpha heating and thermalization profiles is examined. In smaller TFTR-type devices, heating in the outer region can be cut in half. Also, the fusion-product energy-distribution near the plasma edge has a positive slope with increasing energy, representing a possible driving mechanism for micro-instabilities. Another instability that can seriously affect outer plasma conditions and shear Alfven transport of alphas is also considered.

Miley, G H; Choi, C K

1983-01-01

28

Magnetic confinement fusion plasma theory, Task 1  

SciTech Connect

The research performed under this grant during the current year has concentrated on a few key tokamak plasma confinement and heating theory issues: extensive development of a new Chapman-Enskog-like fluid/kinetic hybrid approach to deriving rigorously valid fluid moment equations; applications (neoclassical viscous force, instabilities in the banana-plateau collisionality regime, nonlinear gyroviscous force, unified plasma microinstability equations and their implications, semi-collisional presheath modeling, etc.) of this new formalism; interactions of fluctuating bootstrap-current-driven magnetic islands; determination of net transport processes and equations for a tokamak; and some other topics (extracting more information from heat-pulse-propagation data, modeling of BES fluctuation data, exploring sawtooth effects on energy confinement in DIII-D, divertor X-point modeling). Recent progress and publications in these areas, and in the management of the local NERSC node and fusion theory DECstation 5000 at UW-Madison are summarized briefly in this report.

Callen, J.D.

1991-07-01

29

Nonlinear gyrokinetic theory for finite-BETA plasmas  

SciTech Connect

A self-consistent and energy-conserving set of nonlinear gyrokinetic equations, consisting of the averaged Vlasov and Maxwell's equations for finite-..beta.. plasmas, is derived. The method utilized in the present investigation is based on the Hamiltonian formalism and Lie transformation. The resulting formation is valid for arbitrary values of k/perpendicular//rho//sub i/ and, therefore, is most suitable for studying linear and nonlinear evolution of microinstabilities in tokamak plasmas as well as other areas of plasma physics where the finite Larmor radius effects are important. Because the underlying Hamiltonian structure is preserved in the present formalism, these equations are directly applicable to numerical studies based on the existing gyrokinetic particle simulation techniques. 31 refs.

Hahm, T.S.; Lee, W.W.; Brizard, A.

1988-02-01

30

Plasma confinement experiments in the TMX tandem mirror. Paper IAEA-CN-38/F-1  

SciTech Connect

Results from the new Tandem Mirror Experiment (TMX) are described. Tandem-mirror density and potential profiles are produced using end-plug neutral-beam injection and central-cell gas-fueling. TMX parameters are near those predicted theoretically. The end-plug electron temperature is higher than in the comparably sized single-mirror 2XIIB. Axial confinement of the finite-beta central-cell plasma is improved by the end plugs by as much as a factor of 9. In TMX, end-plug microinstability limits central-cell confinement in agreement with theory.

Simonen, T.C.; Anderson, C.A.; Casper, T.A.

1980-05-22

31

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

32

Dimits Shift in Realistic Gyrokinetic Plasma-Turbulence Simulations  

SciTech Connect

In simulations of turbulent plasma transport due to long wavelength (k{sub perpendicular}){rho}{sub i}{<=}1) electrostatic drift-type instabilities, we find a persistent nonlinear up-shift of the effective threshold. Next-generation tokamaks will likely benefit from the higher effective threshold for turbulent transport, and transport models should incorporate suitable corrections to linear thresholds. The gyrokinetic simulations reported here are more realistic than previous reports of a Dimits shift because they include nonadiabatic electron dynamics, strong collisional damping of zonal flows, and finite electron and ion collisionality together with realistic shaped magnetic geometry. Reversing previously reported results based on idealized adiabatic electrons, we find that increasing collisionality reduces the heat flux because collisionality reduces the nonadiabatic electron microinstability drive.

Mikkelsen, D. R.; Dorland, W. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); University of Maryland, College Park, Maryland 20742 (United States)

2008-09-26

33

Magnetic confinement fusion plasma theory, Task 1. Final report, November 16, 1990--November 15, 1991  

SciTech Connect

The research performed under this grant during the current year has concentrated on a few key tokamak plasma confinement and heating theory issues: extensive development of a new Chapman-Enskog-like fluid/kinetic hybrid approach to deriving rigorously valid fluid moment equations; applications (neoclassical viscous force, instabilities in the banana-plateau collisionality regime, nonlinear gyroviscous force, unified plasma microinstability equations and their implications, semi-collisional presheath modeling, etc.) of this new formalism; interactions of fluctuating bootstrap-current-driven magnetic islands; determination of net transport processes and equations for a tokamak; and some other topics (extracting more information from heat-pulse-propagation data, modeling of BES fluctuation data, exploring sawtooth effects on energy confinement in DIII-D, divertor X-point modeling). Recent progress and publications in these areas, and in the management of the local NERSC node and fusion theory DECstation 5000 at UW-Madison are summarized briefly in this report.

Callen, J.D.

1991-07-01

34

Particle in cell simulation of instabilities in space and astrophysical plasmas  

NASA Astrophysics Data System (ADS)

Several plasma instabilities relevant to space physics are investigated using the parallel PIC plasma simulation code P3arsec. This thesis addresses electrostatic micro-instabilities relevant to ion ring distributions, proceeds to electromagnetic micro-instabilities pertinent to streaming plasmas, and then to the stability of a plasma held in the field of a current rod. The physical relevance of each of these instabilities is discussed, a phenomenological description is given, and analytic and simulation results are presented and compared. Instability of a magnetized plasma with a portion of the ions in a velocity ring distribution around the magnetic field is investigated using simulation and analytic theory. The physics of this distribution is relevant to solar flares, x-ray emission by comets, and pulsars. Physical parameters, including the mass ratio, are near those of a solar flare in the simulation. The simulation and analytic results show agreement in the linear regime. In the nonlinear stage the simulation shows highly accelerated electrons in agreement with the observed spectrum of x-rays emitted by solar flares. A mildly relativistic streaming electron positron plasma with no ambient magnetic field is known to be unstable to electrostatic (two-stream/beam instability) and purely electromagnetic (Weibel) modes. This instability is relevant to highly energetic interstellar phenomena, including pulsars, supernova remnants, and the early universe. It is also important for experiments in which relativistic beams penetrate a background plasma, as in fast ignitor scenarios. Cold analytic theory is presented and compared to simulations. There is good agreement in the regime where cold theory applies. The simulation and theory shows that to properly characterize the instability, directions parallel and perpendicular to propagation of the beams must be considered. A residual magnetic field is observed which may be of astro-physical significance. The stability of a plasma in the magnetic field of a current rod is investigated for various temperature and density profiles. Such a plasma obeys similar physics to a plasma in a dipole magnetic field, while the current rod is much easier to analyze theoretically and realize in simulations. The stability properties of a plasma confined in a dipole field are important for understanding a variety of space phenomena and the Levitated Dipole eXperiment (LDX). Simple energy principle calculations and simulations with a variety of temperature and density profiles show that the plasma is stable to interchange for pressure profiles ? r-10/3. The simulations also show that the density profile will be stationary as long as density ? r -2 even though the temperature profile may not be stable.

Tonge, John William

35

CONFERENCE DESCRIPTION Theory of Fusion Plasmas: Varenna-Lausanne International Workshop  

NASA Astrophysics Data System (ADS)

The Joint Varenna-Lausanne international workshop on Theory of Fusion Plasmas takes place every other year in a place particularly favourable for informal and in-depth discussions. Invited and contributed papers present state-of-the-art research in theoretical plasma physics, covering all domains relevant to fusion plasmas. This workshop always welcomes a fruitful mix of experienced researchers and students, to allow a better understanding of the key theoretical physics models and applications. Theoretical issues related to burning plasmas Anomalous Transport (Turbulence, Coherent Structures, Microinstabilities) RF Heating and Current Drive Macroinstabilities Plasma-Edge Physics and Divertors Fast particles instabilities Further details: http://Varenna-Lausanne.epfl.ch The conference is organized by: Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne, Association EURATOM - Confédération Suisse 'Piero Caldirola' International Centre for the Promotion of Science and International School of Plasma Physics Istituto di Fisica del Plasma del CNR, Milano Editors: X Garbet (CEA, Cadarache, France) and O Sauter (CRPP-EPFL, Lausanne, Switzerland)

Garbet, X.; Sauter, O.

2010-12-01

36

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

37

A 3D gyrokinetic particle-in-cell simulation of fusion plasma microturbulence on parallel computers  

NASA Astrophysics Data System (ADS)

One of the grand challenge problems now supported by HPCC is the Numerical Tokamak Project. A goal of this project is the study of low-frequency micro-instabilities in tokamak plasmas, which are believed to cause energy loss via turbulent thermal transport across the magnetic field lines. An important tool in this study is gyrokinetic particle-in-cell (PIC) simulation. Gyrokinetic, as opposed to fully-kinetic, methods are particularly well suited to the task because they are optimized to study the frequency and wavelength domain of the microinstabilities. Furthermore, many researchers now employ low-noise delta(f) methods to greatly reduce statistical noise by modelling only the perturbation of the gyrokinetic distribution function from a fixed background, not the entire distribution function. In spite of the increased efficiency of these improved algorithms over conventional PIC algorithms, gyrokinetic PIC simulations of tokamak micro-turbulence are still highly demanding of computer power--even fully-vectorized codes on vector supercomputers. For this reason, we have worked for several years to redevelop these codes on massively parallel computers. We have developed 3D gyrokinetic PIC simulation codes for SIMD and MIMD parallel processors, using control-parallel, data-parallel, and domain-decomposition message-passing (DDMP) programming paradigms. This poster summarizes our earlier work on codes for the Connection Machine and BBN TC2000 and our development of a generic DDMP code for distributed-memory parallel machines. We discuss the memory-access issues which are of key importance in writing parallel PIC codes, with special emphasis on issues peculiar to gyrokinetic PIC. We outline the domain decompositions in our new DDMP code and discuss the interplay of different domain decompositions suited for the particle-pushing and field-solution components of the PIC algorithm.

Williams, T. J.

1992-12-01

38

Alpha-driven mironoinstability in tandem mirror plasma  

SciTech Connect

Alpha particles born at deuterium-tritium (D-T) fusion are mirror confined in the tandem mirror with a loss-cone-type distribution in the velocity space. The anisotropy created is susceptible to microinstabilities and the objective of this work is to study possible instabilities that can be driven by the alpha loss-cone. The low-frequency (at the order of the ion cyclotron frequency) wave spectrum is examined to seek the waves that can be destabilized by the alphas. A marginal stability boundary in ion density-temperature space is found. The central cell of the tandem mirror is modeled by an infinite, long plasm cylinder with azimuthal symmetry. The plasma consists of both deuteron and triton as fuel ions and is assumed to be cold since the ion velocity is much smaller than that of the alpha. This model also considers a sharp boundary plasma, with a vacuum region separating it from the conducting wall. To examine reactor implication, the authors have calculated the stability boundary for the cases of the MARS and MINIMARS parameters. The operating regime for both cases is found to be unstable. this could be a key problem for reactor operation and deserves more study. 4 refs., 2 figs.

Ho, S.K.; Miley, G.H.; Smith, G.R.; Nevins, W.M.

1986-01-01

39

Anomalous transport in toroidal plasmas. Final progress report  

SciTech Connect

Anomalous transport in toroidal plasmas arises from the presence of more complicated magnetic and electric fields than are required by the macroscopic equilibrium of the plasma. If one knew these fields, then the transport coefficients, calculated by classical methods, would be correct except for the direct transport of energy by fields (which is usually considered negligible). The limitation of this procedure is the lack of knowledge of the field perturbations, but there are a number of features that are generally accepted whether the perturbations are due to microinstabilities or due to macroscopic effects such as tearing modes. In particular, the frequencies and the wave numbers of perturbations satisfy {omega}* {approx_lt} {omega}, k{sub {perpendicular}} {rho}{sub i} {approx_lt} 1, and k{sub {parallel}} {rho}{sub i} {much_lt} 1 which imply that the magnetic moments of both the ions and the electrons are conserved and that the particle trajectories obey drift equations. The drift equations imply that if magnetic surfaces exist, particles can cross a surface only if there is a spatial variation in the field strength or the electric potential in the surface. If surfaces fail to exist, then particles can also cross the toroidal flux surfaces by moving along the field lines. Here the authors develop Monte Carlo codes to study anomalous transport in ZT-40 and TOKAPOLE 2.

Punjabi, A.

1992-12-31

40

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

41

The Effects of Weak Collisions on Nonlinear Plasma Kinetics  

NASA Astrophysics Data System (ADS)

Kinetic plasma behaviors have long been of interest to those studying space and laboratory plasmas. For instance, kinetic plasma instabilities are widely believed to be responsible for the generation of anomalous resistivity in reconnection layers, providing a possible mechanism for fast reconnection. The concept of Landau damping is fundamental to such wave kinetic instabilities in space, and is treated typically within the framework of the collisionless Vlasov equation. It has become clear in recent theoretical and experimental work that weak collisions are a singular perturbation on the collisionless theory, and qualitatively alter the results of the collisionless theory. In particular, it has been demonstrated by C. S. Ng, A. Bhattacharjee, and F. Skiff that the Case-Van Kampen continuous spectrum, which are the underlying eigenmodes of the collisionless system, are completely eliminated and replaced by a discrete spectrum (hereafter referred to as the NBS spectrum). The NBS spectrum includes Landau-damped roots as exact eigenmodes, but is significantly broader, including a larger spectrum of discrete roots. We discuss the implications of these results for two nonlinear applications, the plasma wave echo and the ion acoustic instability, by means of a new Vlasov code that has been modified to include the Lenard-Bernstein collision operator. We show that the existing collisional theories for the echo, which fail to account for the discrete collisional spectrum, come close, but do not quite yield the appropriate collisional damping rates. Of greater practical importance to problems involving dissipation and anomalous transport is the generation of anomalous resistivity due to microinstabilities. As a specific example, we consider the ion acoustic wave. We compare our numerical findings with the anomalous resistivity estimates of A. Galeev and R. Z. Sagdeev for both collisionless and weakly collisional systems. In the regime of applicability of the theoretical estimates, the agreement is good within an order of magnitude.

Black, Carrie E.

42

Unified fluid/kinetic description of magnetized plasmas  

NASA Astrophysics Data System (ADS)

Unified fluid/kinetic equations for the plasma perturbed density (tilde n), parallel flow velocity (tilde u(parallel)) and temperature (tilde T) are developed in a sheared slab geometry by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) nonlinear perturbed fluid equations for (tilde n), (tilde u(parallel)) and (tilde T) is developed using a drift ordering analysis and a new gyroviscous force (del (center dot) Pi sub g). Thereafter, to develop linear closure relations for b (center dot) del (center dot) tilde Pi(parallel) and tilde q(parallel), a drift-kinetic version of a Chapman-Enskog-like (CEL) equation is developed and solved by using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms.) The resultant closure relations for b (center dot) del (center dot) tilde Pi(parallel) and tilde q(parallel) unify both the fluid and kinetic approaches. In the collisional fluid limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that the CEL approach is more compatible with a fluid-like description of plasmas than the usual drift/gyro kinetic approach. A remarkable simplification of these complicated closure relations is achieved by using single power of plasma dispersion functions with modified arguments. The results are compared with other recently developed Landau damping models and shown to be more accurate, complete and physically meaningful. The resultant set of nonlinear fluid/kinetic equations (with linear closure relations) will be applied to various microinstabilities in tokamak plasmas and drift type microturbulence in a separate paper.

Chang, Zuoyang; Callen, J. D.

1991-06-01

43

Unified fluid/kinetic description of magnetized plasmas  

SciTech Connect

Unified fluid/kinetic equations for the plasma perturbed density ({tilde n}), parallel flow velocity ({tilde u}{sub {parallel}}) and temperature ({tilde T}) are developed in a sheared slab geometry by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) nonlinear perturbed fluid equations for {tilde n}, {tilde u}{sub {parallel}} and {tilde T} is developed using a drift ordering analysis and a new gyroviscous force ({del} {center dot} {product}{sub g}). Thereafter, to develop linear closure relations for b {center dot} {del} {center dot} {tilde product}{sub {parallel}} and {tilde q}{sub {parallel}}, a drift-kinetic version of a Chapman-Enskog-like (CEL) equation is developed and solved by using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms.) The resultant closure relations for b {center dot} {del} {center dot} {tilde product}{sub {parallel}} and {tilde q}{sub {parallel}} unify both the fluid and kinetic approaches. In the collisional fluid limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that the CEL approach is more compatible with a fluid-like description of plasmas than the usual drift/gyro kinetic approach. A remarkable simplification of these complicated closure relations is achieved by using single power of plasma dispersion functions with modified arguments. The results are compared with other recently developed Landau damping models and shown to be more accurate, complete and physically meaningful. The resultant set of nonlinear fluid/kinetic equations (with linear closure relations) will be applied to various microinstabilities in tokamak plasmas and drift type microturbulence in a separate paper. 19 refs., 7 refs., 1 tab.

Chang, Zuoyang; Callen, J.D.

1991-06-01

44

Unified fluid/kinetic description of magnetized plasmas  

NASA Astrophysics Data System (ADS)

The unified fluid/kinetic equations developed in part 1 of this work are used to study plasma drift type microinstabilities. A generalized perturbed Ohm's law derived which is uniformly valid for arbitrary collisionality omega/nu and adiabaticity omega/k(parallel) upsilon(sub t). For electron drift waves we demonstrate that the collisional and collisionless drift wave instabilities can be uniformly described by replacing the Spitzer resistivity with a generalized pseudo-resistivity. Similarly, for ion drift type modes we obtain a uniformly valid dispersion relation for the ion temperature gradient modes (eta(sub i) modes). The eta(sub i) threshold as a function of ion-ion collisionality and ion Landau damping strength is addressed. Applying the unified equations to electron electromagnetic modes leads to generalized coupled equations for tilde phi and tilde A(parallel) which include electron Landau damping effects and are valid for any omega/nu. It is shown that the semi-collisional micro-tearing and drift-tearing modes of Drake and Lee can be easily reproduced in the appropriate limit. Generalization of the two-field Hasegawa-Wakatani turbulent equations to include electron temperature fluctuations and linear Landau damping effects is also discussed. Finally, a new method is presented to facilitate the study of magnetic trapped particle modes using our kinetic closure procedure. It is found that by including the trapped particle effects in the closure relations, the usual separation of the fluid equations into trapped and untrapped components becomes unnecessary.

Chang, Zuoyang; Callen, J. D.

1991-07-01

45

Finite beta effects on the drift-cyclotron instability. [pressure ratio in plasma pinch  

NASA Technical Reports Server (NTRS)

The effects of finite plasma beta and strong plasma inhomogeneities on the microinstability resulting from the unstable coupling of ion-cyclotron oscillations and an ion drift wave are examined. A local electromagnetic, kinetic dispersion equation, which takes into account finite orbit modifications of both ions and electrons as well as the effects of strong inhomogeneities on the ions and permits the continuous tracking of the instability from the weak gradient regime to the strong gradient regime, is derived and solved numerically. Finite beta is shown to increase the frequency and reduce the growth rate of the instability, but not completely stabilize it due to electromagnetic effects. When plasma inhomogeneity is sufficiently strong, finite beta reduces the growth rate of the large k sub y band of a given harmonic more than the small k sub y band; however, the most unstable bands remain the same as in the case of zero beta. Implications of these results for the Tandem Mirror Experiment are discussed.

Gladd, N. T.; Huba, J. D.

1979-01-01

46

Models of magnetic field evolution and effective viscosity in weakly collisional extragalactic plasmas  

NASA Astrophysics Data System (ADS)

In weakly collisional plasmas such as the intracluster medium (ICM), the viscous stress and the rate of change of the magnetic energy are proportional to the local pressure anisotropy, so subject to constraints imposed by the pressure-anisotropy-driven microinstabilities (mirror and firehose) and controlled by the local instantaneous plasma ?. The dynamics of such plasmas can be dramatically different from a conventional magnetohydrodynamic fluid. The plasma is expected to stay locally marginal with respect to the instabilities, but how it does this remains an open question. Two models of magnetic field evolution are investigated. In the first, marginality is achieved via suppression of the rate of change of the field. In the second, the instabilities give rise to anomalous collisionality, reducing pressure anisotropy to marginal - at the same time decreasing viscosity and so increasing the turbulent rate of strain. Implications of these two models are studied in a simplified zero-dimensional setting. In the first model, the field grows explosively but on a time-scale that scales with the initial ?, while in the second, dynamical field strength can be reached in one large-scale turbulence turnover time regardless of the initial seed. Both models produce very intermittent fields. Both also suffer from fairly strong constraints on their applicability: for typical cluster-core conditions, scale separation between the fluid motions (with account of suppressed viscous stress) and the miscoscale fluctuations break down at ? ˜ 104-105. At larger ? (weaker fields), a fully collisionless plasma dynamo theory is needed to justify field growth from a tiny primordial seed. However, the models discussed here are appropriate for studying the structure of the currently observed field as well as large-scale dynamics and thermodynamics of the magnetized ICM or similarly dilute astrophysical plasmas.

Mogavero, Federico; Schekochihin, Alexander A.

2014-06-01

47

Numerical simulations of anisotropic plasmas using a modified ZEUS-MP  

NASA Astrophysics Data System (ADS)

Three dimensional linear and nonlinear simulations of collisionless one-fluid plasmas with pressure anisotropy are presented using the Chew- Goldberger-Low (CGL-MHD) and double-isothermal models. For this purpose, the code ZEUS-MP [J. C. Hayes et. al. The APJ Supplement Series 165 (2006) 188.] has been modified. Major modifications include a changed method of characteristics, new compressive and non-compressive forces, and a ``hard wall'' limit on pressure anisotropy that is intended to mimic the effects of plasma micro-instabilities that limit the temperature anisotropy. For purposes of validation, more than 100 test simulations of linear waves (Alfven, slow and fast), instabilities (firehose and mirror) and nonlinear vortices (Orszag-Tang) are presented for a number of initial conditions and parameters. Finally, this model is used to investigate the way that Alfven-wave turbulence leads to a spreading of the temperature-anisotropy probability distribution in the solar wind. Analysis is completed with a detailed analysis of the fluctuation data.

Chandran, Benjamin; Tangri, Varun; Sarkar, Aveek; Perez, Jean; Sharma, Prateek

2012-10-01

48

Plasma physics and plasma electronics  

SciTech Connect

This book contains the proceedings on plasma physics and plasma electronics. Topics covered included: experiments on the L-2 stellarator, investigation of plasma radiation on the L-2 stellarator, investigation of peripheral plasma on the L-2 stellarator, and formation, evolution and explosive disruption of current sheets in plasma.

Kovrizhnykh, L.M.

1989-01-01

49

Plasma generation and plasma sources  

Microsoft Academic Search

This paper reviews the most commonly used methods for the generation of plasmas with special emphasis on non-thermal, low-temperature plasmas for technological applications. We also discuss various technical realizations of plasma sources for selected applications. This paper is further limited to the discussion of plasma generation methods that employ electric fields. The various plasmas described include dc glow discharges, either

H. Conrads; M. Schmidt

2000-01-01

50

PIC Simulations of Hypersonic Plasma Instabilities  

NASA Astrophysics Data System (ADS)

The plasma sheaths formed around hypersonic aircraft (Mach number, M > 10) are relatively unexplored and of interest today to both further the development of new technologies and solve long-standing engineering problems. Both laboratory experiments and analytical/numerical modeling are required to advance the understanding of these systems; it is advantageous to perform these tasks in tandem. There has already been some work done to study these plasmas by experiments that create a rapidly expanding plasma through ablation of a target with a laser. In combination with a preformed magnetic field, this configuration leads to a magnetic "bubble" formed behind the front as particles travel at about Mach 30 away from the target. Furthermore, the experiment was able to show the generation of fast electrons which could be due to instabilities on electron scales. To explore this, future experiments will have more accurate diagnostics capable of observing time- and length-scales below typical ion scales, but simulations are a useful tool to explore these plasma conditions theoretically. Particle in Cell (PIC) simulations are necessary when phenomena are expected to be observed at these scales, and also have the advantage of being fully kinetic with no fluid approximations. However, if the scales of the problem are not significantly below the ion scales, then the initialization of the PIC simulation must be very carefully engineered to avoid unnecessary computation and to select the minimum window where structures of interest can be studied. One method of doing this is to seed the simulation with either experiment or ion-scale simulation results. Previous experiments suggest that a useful configuration for studying hypersonic plasma configurations is a ring of particles rapidly expanding transverse to an external magnetic field, which has been simulated on the ion scale with an ion-hybrid code. This suggests that the PIC simulation should have an equivalent configuration; however, modeling a plasma expanding radially in every direction is computationally expensive. In order to reduce the computational expense, we use a radial density profile from the hybrid simulation results to seed a self-consistent PIC simulation in one direction (x), while creating a current in the direction (y) transverse to both the drift velocity and the magnetic field (z) to create the magnetic bubble observed in experiment. The simulation will be run in two spatial dimensions but retain three velocity dimensions, and the results will be used to explore the growth of micro-instabilities present in hypersonic plasmas in the high-density region as it moves through the simulation box. This will still require a significantly large box in order to compare with experiment, as the experiments are being performed over distances of 104 ?De and durations of 105 ?pe-1.

Niehoff, D.; Ashour-Abdalla, M.; Niemann, C.; Decyk, V.; Schriver, D.; Clark, E.

2013-12-01

51

Plasma Medicine  

NASA Astrophysics Data System (ADS)

Foreword R. Satava and R. J. Barker; Part I. Introduction to Non-equilibrium Plasma, Cell Biology, and Contamination: 1. Introduction M. Laroussi; 2. Fundamentals of non-equilibrium plasmas M. Kushner and M. Kong; 3. Non-equilibrium plasma sources M. Laroussi and M. Kong; 4. Basic cell biology L. Greene and G. Shama; 5. Contamination G. Shama and B. Ahlfeld; Part II. Plasma Biology and Plasma Medicine: 6. Common healthcare challenges G. Isbary and W. Stolz; 7. Plasma decontamination of surfaces M. Kong and M. Laroussi; 8. Plasma decontamination of gases and liquids A. Fridman; 9. Plasma-cell interaction: prokaryotes M. Laroussi and M. Kong; 10. Plasma-cell interaction: eukaryotes G. Isbary, G. Morfill and W. Stolz; 11. Plasma based wound healing G. Isbary, G. Morfill and W. Stolz; 12. Plasma ablation, surgery, and dental applications K. Stalder, J. Woloszko, S. Kalghatgi, G. McCombs, M. Darby and M. Laroussi; Index.

Laroussi, M.; Kong, M. G.; Morfill, G.; Stolz, W.

2012-05-01

52

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

Institute, Space S.

2005-01-01

53

Why Plasma?  

Microsoft Academic Search

The waste that society generates can be converted into various energy products using new conversion technology. This article highlights the benefits of one promising conversion technology known as plasma gasification, which can be used to generate clean fuels, chemicals and clean electric power. A comparison of plasma gasification to conventional gasification technology is also discussed. Implementation of plasma gasification has

Jeffrey E. Surma

2010-01-01

54

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

55

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

Institute, Space S.

2005-01-01

56

Plasma Cell Disorders  

MedlinePLUS

... Blood Disorders > Plasma Cell Disorders 4 Overview of Plasma Cell Disorders (Dysproteinemias; Monoclonal Gammopathies; Paraproteinemias; Plasma Cell Dyscrasias) Plasma cell disorders are uncommon. They ...

57

Simulating gyrokinetic microinstabilities in stellarator geometry with GS2  

SciTech Connect

The nonlinear gyrokinetic code GS2 has been extended to treat non-axisymmetric stellarator geometry. Electromagnetic perturbations and multiple trapped particle regions are allowed. Here, linear, collisionless, electrostatic simulations of the quasi-axisymmetric, three-field period national compact stellarator experiment (NCSX) design QAS3-C82 have been successfully benchmarked against the eigenvalue code FULL. Quantitatively, the linear stability calculations of GS2 and FULL agree to within {approx}10%.

Baumgaertel, J. A.; Guttenfelder, W.; Hammett, G. W.; Mikkelsen, D. R.; Rewoldt, G.; Tang, W. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Belli, E. A. [General Atomics, San Diego, California 92186 (United States); Dorland, W. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Xanthopoulos, P. [Max-Planck-Institut fuer Plasmaphysik, D-17491 Greifswald (Germany)

2011-12-15

58

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

59

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

60

Smoky Plasma  

Microsoft Academic Search

The mesosphere is a naturally occurring complex plasma with nanometer-sized smoke particles from the ablation of meteors that remain aloft as a consequence of their low rate of sedimentation. Methods are discussed for creating and diagnosing a relatively uniform smoky plasma in the laboratory for the purpose of investigating mesospheric physics. Metallic particles, a few nanometers in radius, are created

Scott Robertson; Zoltan Sternovsky

2007-01-01

61

Plasma universe  

NASA Technical Reports Server (NTRS)

Traditionally the views on the cosmic environent have been based on observations in the visual octave of the electromagnetic spectrum, during the last half-century supplemented by infrared and radio observations. Space research has opened the full spectrum. Of special importance are the X-ray-gamma-ray regions, in which a number of unexpected phenomena have been discovered. Radiations in these regions are likely to originate mainly from magnetised cosmic plasmas. Such a medium may also emit synchrotron radiation which is observable in the radio region. If a model of the universe is based on the plasma phenomena mentioned it is found that the plasma universe is drastically different from the traditional visual universe. Information about the plasma universe can also be obtained by extrapolation of laboratory experiments and magnetospheric in situ measurements of plasmas. This approach is possible because it is likely that the basic properties of plasmas are the same everywhere. In order to test the usefulness of the plasma universe model it is applied to cosmogony. Such an approach seems to be rather successful. For example, the complicated structure of the Saturnian C ring can be accounted for. It is possible to reconstruct certain phenomena 4 to 5 billions of years ago with an accuracy of better than 1%.

Alfven, H.

1986-01-01

62

Volume and Surface Plasmas.  

National Technical Information Service (NTIS)

Scaling of volume and surface dominated plasmas were quantified by electrical, microwave and optical measurements. The application of these plasma devices range from RF plasma processing, high flux atom production, plasma switch and plasma assisted combus...

B. N. Ganguly

2004-01-01

63

Amazing Plasmas  

NSDL National Science Digital Library

This exhibit from the Space Weather Center explains what plasmas are and what forms they take on Earth and in space. It contains many helpful images and two games on magnetism and the states of matter.

2010-05-16

64

Plasma Accelerator.  

National Technical Information Service (NTIS)

The accelerator has potential applications in aerodynamic testing, as a source of high-speed plasma for research and as a propulsion system for space vehicles. The accelerator is capable of steady flow operation. The arrangement includes an accelerating c...

G. P. Wood A. F. Carter A. Busemann

1965-01-01

65

Plasma Rain  

NASA Video Gallery

On April 19, 2010 AIA observed one of the largest prominence eruptions in years. The huge structure erupts, but a great deal of the plasma (hundreds of millions of tons) is unable to escape the gra...

66

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.

2012-12-12

67

Plasma Astrophysics  

NASA Astrophysics Data System (ADS)

This volume presents the lecture notes of the 24th Advanced Course of the Swiss Society for Astrophysics and Astronomy in March 1994 at Les Diablerets. In three lectures on magnetohydrodynamics, on kinetic plasma physics and on particle acceleration leading experts describe the physical basis of their subjects and extend the discussion to several applications in modern problems of astrophysics. In style and presentation the texts are well-suited for graduate work in plasma astrophysics, one of the very important tools of modern astronomy. The themes developed in this book will be helpful in understanding many processes in the universe from the solar corona to active galaxies.

Kirk, J. G.; Melrose, D. B.; Priest, E. R.; Benz, A. O.; Courvoisier, T. J.-L.

68

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

69

Principles of plasma electrodynamics  

Microsoft Academic Search

Principles of the linear electrodynamics of uniform plasma in thermodynamic equilibrium are presented. Linear electromagnetic effects in nonequilibrium, spatially nonuniform plasma (plasma equilibrium theory) are studied. Methods for analysis of nonlinear electrodynamic processes in plasma are described.

A. F. Aleksandrov; L. S. Bogdankevich; A. A. Rukhadze

1978-01-01

70

Plasma pharmacy - physical plasma in pharmaceutical applications.  

PubMed

During the last years the use of physical plasma for medical applications has grown rapidly. A multitude of findings about plasma-cell and plasma-tissue interactions and its possible use in therapy have been provided. One of the key findings of plasma medical basic research is that several biological effects do not result from direct plasma-cell or plasma-tissue interaction but are mediated by liquids. Above all, it was demonstrated that simple liquids like water or physiological saline, are antimicrobially active after treatment by atmospheric pressure plasma and that these effects are attributable to the generation of different low-molecular reactive species. Besides, it could be shown that plasma treatment leads to the stimulation of specific aspects of cell metabolism and to a transient and reversible increase of diffusion properties of biological barriers. All these results gave rise to think about another new and innovative field of medical plasma application. In contrast to plasma medicine, which means the direct use of plasmas on or in the living organism for direct therapeutic purposes, this field - as a specific field of medical plasma application - is called plasma pharmacy. Based on the present state of knowledge, most promising application fields of plasma pharmacy might be: plasma-based generation of biologically active liquids; plasma-based preparation, optimization, or stabilization of - mainly liquid - pharmaceutical preparations; support of drug transport across biological barriers; plasma-based stimulation of biotechnological processes. PMID:23923628

von Woedtke, Th; Haertel, B; Weltmann, K-D; Lindequist, U

2013-07-01

71

Surface Plasma Sources with Helicon Plasma Generators  

SciTech Connect

A Surface Plasma Source (SPS) with plasma generation by a saddle type antenna is discussed. The following features of the helicon discharge with a saddle type antenna in magnetic field are identified: efficient plasma generation in resonant condition, low gas density, strong separation of plasma from the wall, possibility to control plasma flux distribution by magnetic field configuration. Applications of saddle type antenna in SPS for accelerators for Homeland Security and for Neutral Beam Injectors (NBI) are considered.

Dudnikov, Vadim; Dudnikova, Galina; Farrell, J. Paul [Brookhaven Technology Group, Inc., Setauket, NY (United States)

2007-08-10

72

Nonthermal Reactive Plasmas  

NASA Astrophysics Data System (ADS)

Reactive low-temperature plasmas have found broad field of applications in the last decades. Beside the thermal plasmas used for coating of material surfaces (e.g., plasma spraying), synthesis of nano/microparticles and plasma chemical conversion of waste, the focus in this chapter is directed on nonthermal reactive plasmas or cold plasmas which are characterized by strong nonequilibrium conditions. Such nonequilibrium plasmas are implemented in many innovative technologies for surface treatment and synthesis of novel materials. Prominent examples are the plasma etching and patterning in semiconductor processing, the surface modification of polymers due to the incorporation of new functional molecular groups which determine the interactions with surrounding media, and/or the deposition of thin films with novel physical and chemical properties. The nonthermal reactive plasma represents a multispecies system consisting of hot electrons and a mixture of several charged and neutral reactive atoms and molecules. The increasing interest in reactive plasmas containing hydrocarbons, fluorocarbons, and organosilicons needs more fundamental knowledge in both the plasma physics and plasma chemistry. Furthermore, the plasma-surface interaction has to be investigated including the plasma sheath in front of surfaces and the chemical reactions at the phase boundary in connection with the volume plasma chemistry. The aim of this chapter is (1) to give an introduction into nonthermal reactive plasmas and plasma-surface interaction, (2) to present useful diagnostics for characterization of the reactive plasmas and plasma-surface interaction, and (3) to show examples of reactive plasmas in contact with material surfaces.

Meichsner, Jürgen

73

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

74

The Physics of Plasmas  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction; 2. Particle orbit theory; 3. Macroscopic equations; 4. Ideal magnetohydrodynamics; 5. Resistive magnetohydrodynamics; 6. Waves in unbounded homogeneous plasmas; 7. Collisionless kinetic theory; 8. Collisional kinetic theory; 9. Plasma radiation; 10. Non-linear plasma physics; 11. Aspects of inhomogeneous plasmas; 12. The classical theory of plasmas; Appendices; References; Index.

Boyd, T. J. M.; Sanderson, J. J.

2003-01-01

75

Improved plasma accelerator  

NASA Technical Reports Server (NTRS)

Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

Cheng, D. Y.

1971-01-01

76

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.

2006-07-14

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.

2008-05-06

78

Plasma Focus Breeder.  

National Technical Information Service (NTIS)

High voltage generation on pinched plasma by a plasma focus device was investigated. Fissile fuels are bred with the help of high current plasma focus device. A mechanism of accelerating proton beam in plasma focus device to high energy changes the induct...

K. Ikuta

1981-01-01

79

Plasma focus devices  

Microsoft Academic Search

The paper examines the principle of operation and the characteristic plasma properties (dimensions of the plasma focus, density, lifetime and macroscopic instability, electric and magnetic fields, electron temperature, turbulence, electron beams, and X-ray emission, ion temperature, ion distribution function, neutron emission) of plasma focus devices. The plasma focus is considered as a source of neutrons, energy, light and X-rays, and

G. Decker; R. Wienecke

1976-01-01

80

Dust-Plasma  

SciTech Connect

Our theoretical research on dust-plasma interactions has concentrated on three main areas: a)studies of grain charging and applications; b) waves and instabilities in weakly correlated dusty plasma with applications to space and laboratory plasmas; c) waves in strongly coupled dusty plasmas.

Marelene Rosenberg

2005-02-22

81

Principles of Plasma Diagnostics  

Microsoft Academic Search

This book provides a systematic introduction to the physics of plasma diagnostics measurements. It develops from first principles the concepts needed to plan, execute and interpret plasma measurements, making it a suitable book for graduate students and professionals with little plasma physics background. The book will also be a valuable reference for seasoned plasma physicists, both experimental and theoretical, as

I. H. Hutchinson

2002-01-01

82

Basics of Plasma Physics  

Microsoft Academic Search

Basic properties of plasmas are introduced, which are valid for an extremely wide range of plasma parameters. Plasmas are\\u000a classified by different physical behaviour. The motion of charged particles in electromagnetic fields is revised with respect\\u000a to drift motions. Adiabatic invariants are discussed and the kinetic description of plasmas is briefly presented.

U. Schumacher

2005-01-01

83

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

84

Plasmas and laser light  

Microsoft Academic Search

A review of theoretical and experimental research to date on interactions between plasmas and high-intensity coherent light. The book discusses small-amplitude waves in hot\\/cold field-free\\/magnetized plasma, modes of radiative energy transfer, incoherent scattering of light by plasma (as affected by magnetic fields, plasma inhomogeneities or impurities, large-amplitude fluctuations, high temperatures), thermonuclear reactions and plasma confinement, modes of ionization and breakdown

T. P. Hughes

1975-01-01

85

Plasma surface cleaning using microwave plasmas  

SciTech Connect

In a microwave electron cyclotron resonance (ECR) plasma source, reactive plasmas of oxygen and its mixture with argon are used for plasma-cleaning experiments. Aluminum test samples (0.95 {times} 1.9 cm) were coated with thin films ({le} 20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in various discharge conditions with fixed microwave power, rf power, biased potential, gas pressures (0.5 and 5 mtorr), and operating time up to 35 min. The status of plasma cleaning has been monitored by using mass spectroscopy. 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}/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces and confirm the effectiveness of plasma cleaning in achieving atomic levels of surface cleanliness. In this paper, significant results are reported and discussed.

Tsai, C.C.; Haselton, H.H.; Nelson, W.D.; 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)

1993-11-01

86

Nonlinear plasma wave in magnetized plasmas  

SciTech Connect

Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic “Four-Ray Star” pattern.

Bulanov, Sergei V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan) [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan)] [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Hosokai, Tomonao; Zhidkov, Alexei G. [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Kodama, Ryosuke [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2013-08-15

87

Plasma etching in semiconductor fabrication  

SciTech Connect

The contents of this book are: Introduction; Plasma Excitation and Reactor Design; Silicon and Silicon Dioxide Etching in Plasmas; Aluminium Etching in Chlorinated Plasmas; The Plasma Etching of III/V Compound Semiconductors; Operating Frequency and the Plasma; Probe Characteristics and Plasma Measurements of an Electrotech Planar Plasma Etcher; The RF Voltage/Current Characteristics and Related DC Negative Bias Properties of an Electrotech Flat Bed Planar Plasma Etcher; and Methods of Reducing the Etch Rate of Positive Photoresist Masks During Plasma Etching.

Morgan, R.A.

1985-01-01

88

High Density Plasma Dynamics.  

National Technical Information Service (NTIS)

A review of the author's research is presented with emphasis on the in-house work. The results contribute to plasma diagnostics and analysis by spectroscopic methods, understanding of the energy transport and exchange mechanisms in high density plasmas, a...

W. G. Braun

1973-01-01

89

Dusty Plasma Laboratory  

NSDL National Science Digital Library

The DPL studies micron size solid objects immersed in a plasma consisting of electrons, ions, and neutrals. A description of experiments and applications is provided in addition to a list of online plasma research resources.

Spann, James

2003-10-10

90

Plasma Cleaning Device.  

National Technical Information Service (NTIS)

An apparatus for cleaning contaminated surfaces such as hydrocarbon contaminant films in high vacuum environments is described. A plasma discharge housing for allowing a plasma to be generated in an environment having a higher pressure than the surface wh...

R. L. Shannon R. B. Gillette

1976-01-01

91

Basics of Dusty Plasma  

SciTech Connect

The paper presents an introductory review of the basic physical processes in dusty plasmas. The topics to be addressed are dust charging, forces acting on dust grains, interaction between dust grains, and dust-plasma structures.

Ignatov, A.M. [Prokhorov Institute of General Physics, Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 (Russian Federation)

2005-01-15

92

Plasma amino acids  

MedlinePLUS

Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Rheumatoid arthritis High or low concentrations of individual plasma amino acids must be interpreted along with other ...

93

Plasma Free Metanephrines  

MedlinePLUS

... of this website will be limited. Search Help? Plasma Free Metanephrines Share this page: Was this page ... Back to top 2. Does the amount of plasma free metanephrines detected correspond to the size of ...

94

Plasma kinetics in molecular plasmas and modeling of reentry plasmas  

NASA Astrophysics Data System (ADS)

State-to-state non-equilibrium plasma kinetics is widely used to characterize cold molecular and reentry plasmas. The approach requires a high level of dynamical information, and demands a large effort in the creation of complete databases of state-resolved cross sections and rate coefficients. Recent results, emphasizing the dependence of elementary process probability on both the vibrational and rotational energy content of the H2 molecule, are presented for those channels governing the microscopic collisional dynamics in non-equilibrium plasmas, i.e. electron-impact induced resonant processes, vibrational deactivation and dissociation in atom-diatom collisions and atomic recombination at the surface. Results for H2 plasmas, i.e. negative ion sources for neutral beam injection in fusion reactors, RF parallel-plate reactors for microelectronics, atmospheric discharges and the shock wave formed in the hypersonic entry of vehicles in planetary atmosphere for aerothermodynamics, are discussed.

Capitelli, M.; Celiberto, R.; Colonna, G.; D'Ammando, G.; De Pascale, O.; Diomede, P.; Esposito, F.; Gorse, C.; Laricchiuta, A.; Longo, S.; Pietanza, L. D.; Taccogna, F.

2011-12-01

95

Plasma diagnostics for FED  

SciTech Connect

An overview of the plasma diagnostic instruments recommended for the Fusion Engineering Device (FED) is described. First the role and need for plasma diagnostics is discussed. This is followed by an identification of particles and radiation eminating from the plasma. Next some design considerations are presented for the overall set of diagnostic instruments. Finally, instruments used for control and for plasma performance measurements are included in separate lists.

Nelson, W.D.

1981-01-01

96

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.

97

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

98

IR plasma emissions  

NASA Astrophysics Data System (ADS)

This final report summarized the latest results in data acquisition and various modeling efforts of the GL-LINUS plasma. Plasma radiance equations relevant to the LINUS plasma are first reviewed. Experimental data on the early-time plasma continuum are next presented. This is followed by discussions of the calculations on Stark broadening, hydrodynamics, and kinetics. Finally, recommendations on future experiments and calculations are made based on the present results.

Ip, Precila C. F.; Armstrong, Russell A.

1990-04-01

99

A reconfigurable plasma antenna  

NASA Astrophysics Data System (ADS)

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; Bora, Dhiraj

2010-03-01

100

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

101

Plasma Focus Breeder.  

National Technical Information Service (NTIS)

Instead of using linear accelerators, it is possible to breed fissile fuels with the help of high current plasma focus device. A mechanism of accelerating proton beam in plasma focus device to high energy would be a change of inductance in plasma column b...

K. Ikuta

1981-01-01

102

Perspectives on Plasmas  

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.

2003-10-10

103

Plasmas for Welding  

NSDL National Science Digital Library

To learn about an important plasma used in manufacturing, visit MIT's Plasmas for Welding. The text describes the arc, which is a plasma, and explains how the arc and the metal to be welded are part of an electric circuit. With photos, the site shows how high-power welding machines cut openings in large sheets of metal.

2006-08-05

104

Perspectives on Plasmas: Basics  

NSDL National Science Digital Library

This website from Plasmas International presents the basic ideas of plasma physics. It includes a chart of temperature versus density that shows the many plasma states on Earth and in space, as well as ordinary matter. It includes a number of links to related sites.

2008-08-12

105

The Plasma Universe  

NASA Astrophysics Data System (ADS)

Preface; 1. The fourth state of matter; 2. The music and dance of plasmas; 3. The Sun-Earth connection; 4. Bringing the Sun to Earth: the story of controlled thermonuclear fusion; 5. The cosmic plasma theater: galaxies, stars, and accretion disks; 6. Putting plasmas to work; Index.

Suplee, Curt

2009-09-01

106

Plasma in astrophysics  

SciTech Connect

Two examples of plasma phenomena of importance to astrophysics are reviewed. These are examples where astrophysical understanding hinges on further progress in plasma physics understanding. The two examples are magnetic reconnection and the collisionless interaction between a population of energetic particles and a cooler gas or plasma, in particular the interaction between galactic cosmic rays and the interstellar medium.

Kulsrud, R.M.

1982-10-01

107

Quasineutrality in Electronegative Plasmas  

Microsoft Academic Search

As is well known, plasmas are good conductors and thus usually keep the electric field small inside. The field is small because most of the voltage, whether developed naturally or applied externally, appears across narrow sheaths at the boundaries. The charge density is therefore high in the sheaths but low in the plasma middle. Most plasmas can thus be viewed

Richard F. Fernsler

2002-01-01

108

Metastable supercooled plasma  

Microsoft Academic Search

The computer ab initio simulation and analytical theory that revealed unexpected nonergodic properties in a classical Coulomb plasma are reviewed. The results of a many-charged-particle system simulation predict the possible existence of a real metastable plasma, supercooled with respect to its degree of ionisation. The existence of such a plasma state is a consequence of the entropy conservation in isolated

S A Mayorov; Aleksei N Tkachev; Sergei I Yakovlenko

1994-01-01

109

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

110

STERILISATION BY ECR PLASMA  

Microsoft Academic Search

Microwave plasma was built to produce plasma in axial direction. Plasma was initiated in a Plaxy Glass made vacuum tube by 2.45GHz commercial magnetron and meanwhile system was driven by 14 Amperes DC current passing through 16cm inner diameter toroid. Measurements with a Longmuir probe and ICCD for optical spectrometry were used to characterize internal parameters like electron density, electron

Selcuk HELHEL

111

Model of detached plasmas  

SciTech Connect

Recently a tokamak plasma was observed in TFTR that was not limited by a limiter or a divertor. A model is proposed to explain this equilibrium, which is called a detached plasma. The model consists of (1) the core plasma where ohmic heating power is lost by anomalous heat conduction and (2) the shell plasma where the heat from the core plasma is radiated away by the atomic processes of impurity ions. A simple scaling law is proposed to test the validity of this model.

Yoshikawa, S.; Chance, M.

1986-07-01

112

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.

2012-12-27

113

Industrial Plasma Antennas  

NASA Astrophysics Data System (ADS)

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 operating at high plasma density at minimal power consumption, a novel technique of noise reduction, and a method of opening a plasma window in a plasma microwave barrier on a time scale of microseconds rather than the usual time scale of milliseconds due to plasma decay. We are at present testing an intelligent plasma antenna in which a plasma ``window'' in a circular plasma barrier surrounding an antenna rotates azimuthally, seeking a radio transmitter. When located, a computer locks onto the transmitter. When the transmitter is de-energized, the plasma window recommences scanning. Commercial interest is strong, with invited papers being presented for 4 years in succession at the SMi Stealth Conference in London, UK, an operating model on permanent exhibition at the Booze-Allen headquarters in Alexandria, VA, and strong interest from Lockheed-Martin. In collaboration with Ted Anderson, Haleakala R&D Corp.; Esmaeil Farshi, Fred Dyer, Jeffrey Peck, Eric Pradeep, Nanditha Pulasani, and Naresh Karnam, University of Tennessee.

Alexeff, Igor

2007-11-01

114

Plasma contactor research, 1989  

NASA Technical Reports Server (NTRS)

The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

Williams, John D.

1990-01-01

115

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

116

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

117

PES fabric plasma modification  

NASA Astrophysics Data System (ADS)

Polyester ranks the upper position in the world fiber production — nearly 54% of the total production of synthetic fibers. Troubles connected with minimizing of the textile hydrophobicity are usually being solved by the textile fibers’ surface chemical modification, but from ecological point of view modification of fabric with low temperature plasma is superior to classical chemical wet processes. Application of various plasmas for PES treatment has been already described. To compare the effectiveness of different plasma sources we performed a series of experiment both in RF and MW plasmas. For working gas nitrogen, oxygen and their mixtures were employed. Internal plasma control was provided by measurement of optical emission spectra. The hydrophilicity degree was determined by the drop test. Paper discusses optimal conditions of the PES fabric plasma treatment.

Vatu?a, T.; Špatenka, P.; Píchal, J.; Koller, J.; Aubrecht, L.; Wiener, J.

2004-03-01

118

Plasma skin regeneration technology.  

PubMed

Plasma skin regeneration is a novel type of skin rejuvenation technology developed over the last 3 years. Plasma is the fourth state of matter in which electrons are stripped from atoms to form an ionized gas. Although high temperature plasmas have been used in surgery for over a decade, plasma had previously been used as a conduction medium for electric current. Unlike lasers which rely on the principle of selective photothermolysis to deliver heat to specific targets in the skin, plasma technology delivers heat energy directly to tissue upon contact without reliance on skin chromophores. The plasma itself produces controlled thermal damage to the skin surface to elicit changes such as new collagen formation and improvement in photodamaged skin. The technology can be used at varying energies for different depths of effect, from superficial epidermal effects to deeper dermal heating. PMID:18038498

Bogle, Melissa A; Arndt, Kenneth A; Dover, Jeffrey S

2007-11-01

119

Pulsed plasma electron sources  

NASA Astrophysics Data System (ADS)

There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E<=105 V/cm and duration <=10-5 s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

Krasik, Ya. E.; Yarmolich, D.; Gleizer, J. Z.; Vekselman, V.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J.

2009-05-01

120

Voltage Amplification using Plasma  

SciTech Connect

The purpose of this work is to present experimental results about voltage amplification using plasma produced by a simple neon lamp, series connected with a signal generator and discrete circuit elements. The main advantage of employing plasma as an amplifier is due to its ability to drive larger power and potentially to operate in a larger frequency range compared with traditional amplifiers. Our results show that both, the voltage gain and the frequency range where the gain is bigger than one, are related to the plasma density which may be adjusted by a proper control of electrical discharge conditions. The plasma produced into the neon lamp exhibits a diode characteristic that is the principal responsible by the nonlinear plasma response. The amplification occurs when the plasma shows a negative conductance. In this regime the lamp works as an active amplifier and voltage gain higher than 18 was obtained.

Farias, E. E.; Cavalcanti, G. H.; Santiago, M. A. M. [Av. Gal Milton Tavares de Souza - 24310 240 - Instituto de Fisica - Universidade Federal Fluminense (Brazil)

2006-12-04

121

Pulsed plasma electron sources  

SciTech Connect

There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E{<=}10{sup 5} V/cm and duration {<=}10{sup -5} s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

Krasik, Ya. E.; Yarmolich, D.; Gleizer, J. Z.; Vekselman, V.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J. [Department of Physics, Technion, 32000 Haifa (Israel)

2009-05-15

122

Advances in Novel Plasma Devices Based on the Plasma Lens  

Microsoft Academic Search

We review some new results in the development of novel cylindrical plasma devices based on the electrostatic plasma lens configuration and the concepts of electron magnetic insulation and magnetic field line equipotentialization. The plasma lens configuration of crossed electric and magnetic fields provides an attractive method for establishing a stable plasma discharge at low pressure. Use of the plasma lens

Alexey A. Goncharov; Anton N. Evsyukov; Irina V. Litovko

2009-01-01

123

23rd National Symposium on Plasma Science & Technology (PLASMA2008)  

Microsoft Academic Search

It is our pleasure to present the proceedings of the 23rd National Symposium on Plasma Science and Technology (PLASMA-2008) held at Bhabha Atomic Research Center, Mumbai, 10– December 2008 in association with the Plasma Science Society of India. The Plasma Science Society of India has been holding regular symposia on general topics related to Plasma. The symposium was designed to

V K Mago; P V Ananthapadmanabhan; D S Patil; A K Das

2010-01-01

124

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

125

Plasma induced luminescence (PIL)  

Microsoft Academic Search

Laser-induced breakdown spectroscopy (LIBS) is well known tool for elemental analysis of solid, liquid and gaseous materials. The species emission life times in typical plasma are in 10–50?s range. It is recognized that after this time following plasma formation any useful information does not exist. It is not the case when matrix subjected for plasma excitation is capable to luminescence.

M. Gaft; L. Nagli; Y. Groisman

126

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

127

Cassini Plasma Spectrometer Investigation  

Microsoft Academic Search

The Cassini Plasma Spectrometer (CAPS) will make comprehensive three-dimensional mass-resolved measurements of the full variety of plasma phenomena found in Saturn’s magnetosphere. Our fundamental scientific goals are to understand the nature of saturnian plasmas primarily their sources of ionization, and the means by which they are accelerated, transported, and lost. In so doing the CAPS investigation will contribute to understanding

D. T. Young; J. J. Berthelier; M. Blanc; J. L. Burch; A. J. Coates; R. Goldstein; M. Grande; T. W. Hill; R. E. Johnson; V. Kelha; D. J. Mccomas; E. C. Sittler; K. R. Svenes; K. Szegö; P. Tanskanen; K. Ahola; D. Anderson; S. Bakshi; R. A. Baragiola; B. L. Barraclough; R. K. Black; S. Bolton; T. Booker; R. Bowman; P. Casey; F. J. Crary; D. Delapp; G. Dirks; N. Eaker; H. Funsten; J. D. Furman; J. T. Gosling; H. Hannula; C. Holmlund; H. Huomo; J. M. Illiano; P. Jensen; M. A. Johnson; D. R. Linder; T. Luntama; S. Maurice; K. P. Mccabe; K. Mursula; B. T. Narheim; J. E. Nordholt; A. Preece; J. Rudzki; A. Ruitberg; K. Smith; S. Szalai; M. F. Thomsen; K. Viherkanto; J. Vilppola; T. Vollmer; T. E. Wahl; M. Wüest; T. Ylikorpi; C. Zinsmeyer

2004-01-01

128

Wakes in inhomogeneous plasmas  

NASA Astrophysics Data System (ADS)

The Debye shielding of a charge immersed in a flowing plasma is an old classic problem. It has been given renewed attention in the last two decades in view of experiments with complex plasmas, where charged dust particles are often levitated in a region with strong ion flow. Efforts to describe the shielding of the dust particles in such conditions have been focused on the homogeneous plasma approximation, which ignores the substantial inhomogeneity of the levitation region. We address the role of the plasma inhomogeneity by rigorously calculating the point charge potential in the collisionless Bohm sheath. We demonstrate that the inhomogeneity can dramatically modify the wake, making it nonoscillatory and weaker.

Kompaneets, Roman; Ivlev, Alexei V.; Nosenko, Vladimir; Morfill, Gregor E.

2014-04-01

129

Plasma adiabatic lapse rate.  

PubMed

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 Z(2)-Z(1). 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. PMID:23006377

Amendt, Peter; Bellei, Claudio; Wilks, Scott

2012-08-17

130

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

131

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

132

EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets  

NASA Astrophysics Data System (ADS)

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 plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 35-50% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 1948-1990130031 1991-19952279456 1996-20003447689 2001-20054571914 2006-201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ?0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective technological solution in the early to late 1990s of confining atmospheric plasmas in a small volume

Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

2012-06-01

133

Plasma cleaning for waste minimization  

Microsoft Academic Search

Although plasma cleaning is a recognized substitute for solvent cleaning in removing organic contaminants, some universal problems in plasma cleaning processes prevent wider use of plasma techniques. Lack of understanding of the fundamental mechanisms of the process, unreliable endpoint detection techniques, and slow process times make plasma cleaning processes less than desirable. Our approach to address these plasma cleaning problems

1993-01-01

134

MICROFABRICATED PROBES FOR LABORATORY PLASMAS  

Microsoft Academic Search

We present the first of a series of microfabricated sensors for directly measuring fundamental plasma parameters with unprecedented resolution in typical laboratory plasmas. Microfabricated probes hold the promise of significantly advancing basic plasmas physics by enabling the measurement of some fundamental plasma processes under controlled conditions at the relatively high plasma densities typically of interest. Our first probes are arrays

Janet A. Stillman; Franklin C. Chiang; Patrick A. Pribyl; Mio Nakamoto; Walter Gekelman; Jack W. Judy

135

Laser plasma diagnostics of dense plasmas  

SciTech Connect

The authors describe several experiments on Nova that use laser-produced plasmas to generate x-rays capable of backlighting dense, cold plasmas (p {approximately} 1--3 gm/cm{sup 3}, kT {approximately} 5--10 eV, and areal density {rho}{ell}{approximately} 0.01--0.05 g/cm{sup 2}). The x-rays used vary over a wide range of h{nu}, from 80 eV (X-ray laser) to 9 keV. This allows probing of plasmas relevant to many hydrodynamic experiments. Typical diagnostics are 100 ps pinhole framing cameras for a long pulse backlighter and a time-integrated CCD camera for a short pulse backlighter.

Glendinning, S.G.; Amendt, P.; Budil, K.S.; Hammel, B.A.; Kalantar, D.H.; Key, M.H.; Landen, O.L.; Remington, B.A. [Lawrence Livermore National Lab., CA (United States); Desenne, D.E. [CEL-V, Limeil (France)

1995-07-12

136

Plasmas of Arbitrary Neutrality  

NASA Astrophysics Data System (ADS)

The physics of partially neutralized plasmas is largely unexplored, partly because of the difficulty of confining such plasmas. Plasmas are confined in a stellarator without the need for a plasma current, and regardless of the degree of neutralization. The Columbia Non-neutral Torus (CNT) is a stellarator dedicated to the study of non-neutral, and partially neutralized plasmas. This thesis describes the first systematic studies of plasmas of arbitrary neutrality. The degree of neutralization of the plasma can be parameterized through the quantity eta ? |ne - Z ni|/|ne + Z n i|. In CNT, eta can be varied continuously from pure electron (eta = 1) to quasi-neutral (eta = 0) by adjusting the neutral pressure in the chamber, which controls the volumetric ionization rate. Pure electron plasmas are in macroscopically stable equilibria, and have strong self electric potentials dictated by the emitter filament bias voltage on the magnetic axis. As eta decreases, the plasma potential decouples from the emitter, and spontaneous fluctuations begin to appear. Partially neutralized plasmas (10-3 < eta < 10-1) generally exhibit multi-mode oscillations in CNT. However, when magnetized ions are present, the electron-rich plasma oscillates at a single dominant mode (20 - 100 kHz). As the plasma approaches quasi-neutrality (eta < 10-5), it also reverts to single mode behavior (1 - 20 kHz). A parametric characterization of the single mode fluctuations detected in plasmas of arbitrary neutrality is presented in this thesis along with measurements of the spatial structure of the oscillations. The single mode fluctuations observed for eta ? 0.01 to 0.8 are identified as an ion resonant instability propagating close to the E x B velocity of the plasma. The experiments also show that these oscillations present a poloidal mode number m = 1, and a toroidal number n = 0, which is identical to the spatial structure of the diocotron instability in pure-toroidal traps, and implies that the ion-driven instability breaks parallel force balance and the conservation of poloidal flux in CNT. The low frequency oscillations detected in the quasi-neutral regime are a global instability convected by the E x B flow of the plasma. In this case, the mode aligns almost perfectly with the field lines, and presents a resonant m = 3 poloidal structure.

Sarasola Martin, Xabier

137

On the physics of plasma rotation in fusion plasmas  

SciTech Connect

A view of the mechanisms underlying momentum transport in fusion plasmas devices is presented. Heat and energy transport in fusion plasmas is partly due to turbulent processes having an intermittent character and presenting some universal features. The investigation of the mechanisms underlying the generation of plasma flows (via turbulence and neoclassical effects) is key area of research to control transport in magnetically confined plasmas. Projections of ITER plasma performance require better understanding of plasma rotation.

Hidalgo, Carlos [Laboratorio Nacional de Fusion, EURATOM-CIEMAT, Madrid (Spain)

2008-05-14

138

Hybrid plume plasma rocket  

NASA Technical Reports Server (NTRS)

A technique for producing thrust by generating a hybrid plume plasma exhaust is disclosed. A plasma flow is generated and introduced into a nozzle which features one or more inlets positioned to direct a flow of neutral gas about the interior of the nozzle. When such a neutral gas flow is combined with the plasma flow within the nozzle, a hybrid plume is constructed including a flow of hot plasma along the center of the nozzle surrounded by a generally annular flow of neutral gas, with an annular transition region between the pure plasma and the neutral gas. The temperature of the outer gas layer is below that of the pure plasma and generally separates the pure plasma from the interior surfaces of the nozzle. The neutral gas flow both insulates the nozzle wall from the high temperatures of the plasma flow and adds to the mass flow rate of the hybrid exhaust. The rate of flow of neutral gas into the interior of the nozzle may be selectively adjusted to control the thrust and specific impulse of the device.

Chang, Franklin R. (inventor)

1989-01-01

139

Polar Plasma Wave Instrument.  

National Technical Information Service (NTIS)

The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fiel...

D. A. Gurnett A. M. Persoon R. F. Randall D. L. Odem S. L. Remington

1995-01-01

140

Plasma engineering for MARS  

SciTech Connect

The two-year Mirror Advanced Reactor Study (MARS) has resulted in the conceptual design of a commercial, electricity-producing fusion reactor based on tandem mirror confinement. The physics basis for the MARS reactor was developed through work in two highly coupled areas of plasma engineering: magnetics and plasma performance.

Carlson, G.A.; Baldwin, D.E.; Barr, W.L.

1983-03-24

141

Plasma gasification of coals  

SciTech Connect

To avoid problems of transporting coal from Siberia to the European part of the Soviet Union, plasma gasification could be used to give methane and liquid methyl fuel which could be transported by pipeline. Plasma-assisted gasification is particularly effective in the case of brown coals. (11 refs.)

Kruzhilin, G.I.; Khudyakov, G.N.; Tselishchev, P.A.

1981-01-01

142

Plasma production by laser  

Microsoft Academic Search

A review of high density, high temperature plasma production with pulse lasers is presented. In view of possible applications to thermonuclear fusion we limit our discussion to plasma generation from solid targets of low atomic number Z, with particular emphasis on solid deuterium.

P. Mulser; R. Sigel; S. Witkowski

1973-01-01

143

A possible plasma laser  

Microsoft Academic Search

It is possible for a plasma containing finite-amplitude ion-density ; fluctuations and drifting electrons to exhibit a negative resistance for high-; frequency electric fields. Under such circumstances both longitudinal plasma ; oscillations and electromagnetic waves can be amplified or even undergo unstable ; growth. We have investigated this possibility for longitudinal waves by ; theoretical analysis and numerical simulation of

A. T. Lin; P. K. Kaw; J. M. Dawson

1973-01-01

144

Coaxial microwave plasma source  

SciTech Connect

Physical principles underlying the operation of a pulsed coaxial microwave plasma source (micro-wave plasmatron) are considered. The design and parameters of the device are described, and results of experimental studies of the characteristics of the generated plasma are presented. The possibility of application of this type of plasmatron in gas-discharge physics is discussed.

Gritsinin, S. I. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Gushchin, P. A. [Gubkin State University of Oil and Gas (Russian Federation); Davydov, A. M.; Kossyi, I. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Kotelev, M. S. [Gubkin State University of Oil and Gas (Russian Federation)

2011-11-15

145

Principles of plasma diagnostics  

Microsoft Academic Search

Principles of Plasma Diagnostics provides a detailed derivation and discussion of the plasma physics principles on which diagnostics are base, including magnetic measurements, electric probes, refractive index, radiation emission and scattering, and ionic processes. The text is based on first-principles development of the required concepts and includes examples of diagnostics in action taken from fusion research.

Ian H. Hutchinson

1987-01-01

146

Principles of plasma diagnostics  

Microsoft Academic Search

This book is a reprint of the 1987 edition (44.003.073). Contents: 1. Plasma diagnostics. 2. Magnetic diagnostics. 3. Plasma particle flux. 4. Refractive-index measurements. 5. Electromagnetic emission by free electrons. 6. Electromagnetic radiation from bound electrons. 7. Scattering of electromagnetic radiation. 8. Ion processes.

I. H. Hutchinson

1990-01-01

147

Filamentary magnetohydrodynamic plasmas  

Microsoft Academic Search

A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsa¨sser variables is developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion,

R. Kinney; T. Tajima; J. C. McWilliams; N. Petviashvili

1994-01-01

148

Filamentary magnetohydrodynamic plasmas  

Microsoft Academic Search

A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion,

R. Kinney; T. Tajima; N. Petviashvili; J. C. McWilliams

1993-01-01

149

EAST plasma control system  

Microsoft Academic Search

Experimental advanced superconducting tokamak (EAST), the first tokomak with ITER-like fully superconductive poloidal and toroidal coils, successfully completed its engineering commission in March 2006; had its first plasma in September 2006 [B.N. Wan, et al., The first plasma of EAST, in: 21st IAEA Fusion Energy Conference, Chengdu, China, 16–21 October, 2007. [1

B. J. Xiao; D. A. Humphreys; M. L. Walker; A. Hyatt; J. A. Leuer; D. Mueller; B. G. Penaflor; D. A. Pigrowski; R. D. Johnson; A. Welander; Q. P. Yuan; H. Z. Wang; J. R. Luo; Z. P. Luo; C. Y. Liu; L. Z. Liu; K. Zhang

2008-01-01

150

Dusty plasma for nanotechnology  

Microsoft Academic Search

Over the years dust particles formed in plasmas and used for microelectronic technologies were considered as an important source of irremediable defects. They grow in the gas phase through homogeneous chemical reactions and remain trapped in the plasma gas phase due to the negative charge they acquire by electron attachment. The earlier formed particles are, under certain conditions, crystallites of

L. Boufendi; M. Ch Jouanny; E. Kovacevic; J. Berndt; M. Mikikian

2011-01-01

151

Pulsed Plasma Thruster  

NASA Technical Reports Server (NTRS)

Dr. Tom Markusic, a propulsion research engineer at the Marshall Space Flight Center (MSFC), adjusts a diagnostic laser while a pulsed plasma thruster (PPT) fires in a vacuum chamber in the background. NASA/MSFC's Propulsion Research Center (PRC) is presently investigating plasma propulsion for potential use on future nuclear-powered spacecraft missions, such as human exploration of Mars.

2002-01-01

152

High Energy Plasma Accelerators.  

National Technical Information Service (NTIS)

Colinear intense laser beams omega sub 0 , kappa sub 0 and omega sub 1 , kappa sub 1 shone on a plasma with frequency separation equal to the electron plasma frequency omega /sub pe/ are capable of creating a coherent large longitudinal electric field E/s...

T. Tajima

1985-01-01

153

Plasma cell leukemia  

Microsoft Academic Search

Plasma cell leukemia (PCL) is a rare, yet aggressive plasma cell (PC) neoplasm, variant of multiple myeloma (MM), characterized by high levels of PCs circulating in the peripheral blood. PCL can either originate de novo (primary PCL) or as a secondary leukemic transformation of MM (secondary PCL). Presenting signs and symptoms are similar to those seen in MM such as

Flavio Albarracin; Rafael Fonseca

2011-01-01

154

Focus on Plasma Medicine  

Microsoft Academic Search

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

G E Morfill; M G Kong; J L Zimmermann

2009-01-01

155

Plasma technology directory  

SciTech Connect

The Plasma Technology Directory has two main goals: (1) promote, coordinate, and share plasma technology experience and equipment within the Department of Energy; and (2) facilitate technology transfer to the commercial sector where appropriate. Personnel are averaged first by Laboratory and next by technology area. The technology areas are accelerators, cleaning and etching deposition, diagnostics, and modeling.

Ward, P.P.; Dybwad, G.L.

1995-03-01

156

Plasma Dynamo Experiments  

NASA Astrophysics Data System (ADS)

The Madison Plasma Dynamo Experiment (MPDX) is under construction to explore the self-excitation processes of a range of astrophysical dynamos. Numerical simulations of von K'arm'an flow have shown that a two-vortex flow can produce a dynamo when the magnetic Reynolds number is sufficiently high, which, for a plasma, requires a large, hot, flowing and unmagnetized plasma. This poster discusses experimental plans for von K'arm'an flow in MPDX as well as prototype experiments on the Plasma Couette Experiment (PCX). The PCX is a cylindrical plasma experiment currently being used to optimize a multi-cusp magnetic confinement scheme for experiments on the magnetorotational instability. It also provides a platform for prototyping two types of plasma sources (electron cyclotron heating and LaB6 cathode) as well as an ExB stirring mechanism, diagnostics, and future MPDX dynamo scenarios. This poster will review recent findings from PCX involving the fabrication and operation of a new LaB6 electron source and its use in driving Dean flow. While currently attainable densities (ne 10^17 m-3, using electron cyclotron heating) require Hall MHD in calculating the plasma response to various flow profiles, the new LaB6 electron source may allow high enough densities to place the plasma in a purely MHD regime. Work supported by NSF.

Weisberg, David; Collins, Cami; Katz, Noam; Wallace, John; Khalzov, Ivan; Jara-Almonte, Jonathan; Forest, Cary

2011-11-01

157

Vacuum Plasma Spray Coating.  

National Technical Information Service (NTIS)

Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for...

R. R. Holmes T. N. McKechnie

1989-01-01

158

Plasma spray forming  

Microsoft Academic Search

The technology of plasma spray forming (PSF) is introduced, and the technical processes of plasma spray for fabricating parts and moulds are investigated emphatically in this paper. The technological characteristics of PSF are summarized, including original prototype fabrication and surface treatment, post-treatment of a formed workpiece and demoulding methods. Also, some important factors affecting the qualities of workpiece formed by

J. C Fang; W. J Xu

2002-01-01

159

Triggered plasma opening switch  

DOEpatents

A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

Mendel, Clifford W. (Albuquerque, NM)

1988-01-01

160

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

161

Plasma Physics Research and Instrumentation.  

National Technical Information Service (NTIS)

Experiments in plasma research, technology and applied plasma physics, and plasma theory and computation are reported. The following research activities are identified as being of special interest: Several toroidal confinement devices were constructed. On...

1971-01-01

162

Plasma Contactors for Electrodynamic Tether.  

National Technical Information Service (NTIS)

The role plasma contactors play in effective electrodynamic tether operation is discussed. Hollow cathodes and hollow cathode-based plasma sources have been identified as leading candidates for the electrodynamic tether plasma contactor. Present experimen...

M. J. Patterson P. J. Wilbur

1986-01-01

163

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

164

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

165

Plasma sheath criterion in thermal electronegative plasmas  

SciTech Connect

The sheath formation criterion in electronegative plasma is examined. By using a multifluid model, it is shown that in a collisional sheath there will be upper as well as lower limits for the sheath velocity criterion. However, the parameters of the negative ions only affect the lower limit.

Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Khoramabadi, Mansour; Ghorannevis, Mahmod [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, P.O. Box 14665-678, Tehran (Iran, Islamic Republic of); Shukla, Padma Kant [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2010-09-15

166

Dense Hypervelocity Plasma Jets  

NASA Astrophysics Data System (ADS)

We are developing high velocity dense plasma jets for fusion and HEDP applications. Traditional coaxial plasma accelerators suffer from the blow-by instability which limits the mass accelerated to high velocity. In the current design blow-by is delayed by a combination of electrode shaping and use of a tailored plasma armature created by injection of a high density plasma at a few eV generated by arrays of capillary discharges or sparkgaps. Experimental data will be presented for a complete 32 injector gun system built for driving rotation in the Maryland MCX experiment, including data on penetration of the plasma jet through a magnetic field. We present spectroscopic measurements of plasma velocity, temperature, and density, as well as total momentum measured using a ballistic pendulum. Measurements are in agreement with each other and with time of flight data from photodiodes and a multichannel PMT. Plasma density is above 10^15 cm-3, velocities range up to about 100 km/s. Preliminary results from a quadrature heterodyne HeNe interferometer are consistent with these results.

Case, Andrew; Witherspoon, F. Douglas; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

2007-11-01

167

Origins of magnetospheric plasma  

SciTech Connect

A review is given of recent (1987-1990) progress in understanding of the origins of plasmas in the earth's magnetosphere. In counterpoint to the early supposition that geomagnetic phenomena are produced by energetic plasmas of solar origin, 1987 saw the publication of a provocative argument that accelerated ionospheric plasma could supply all magnetospheric auroral and ring current particles. Significant new developments of existing data sets, as well as the establishment of entirely new data sets, have improved the ability to identify plasma source regions and to track plasma through the magnetospheric system of boundary layers and reservoirs. These developments suggest that the boundary between ionospheric and solar plasmas, once taken to lie at the plasmapause, actually lies much nearer to the magnetopause. Defining this boundary as the surface where solar wind and ionosphere contribute equally to the plasma, it is referred to herein as the 'geopause'. It is now well established that the infusion of ionospheric O(+) plays a major role in the storm-time distention of the magnetotail and inflation of the inner magnetosphere. After more than two decades of observation and debate, the question remains whether magnetosheric are protons of solar or terrestrial origin. 161 refs.

Moore, T.E. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

168

Quasineutrality in Electronegative Plasmas  

NASA Astrophysics Data System (ADS)

As is well known, plasmas are good conductors and thus usually keep the electric field small inside. The field is small because most of the voltage, whether developed naturally or applied externally, appears across narrow sheaths at the boundaries. The charge density is therefore high in the sheaths but low in the plasma middle. Most plasmas can thus be viewed as a quasineutral middle surrounded by a non-neutral sheath. Using this model, Bohm derived a condition in 1949 for the minimum flow velocity at which positive ions enter the sheath at the boundary of electropositive plasmas, and versions of this condition apply wherever quasineutrality fails. The Bohm condition has since been extended to electronegative plasmas by assuming the negative ions, as well as the electrons, obey the Boltzmann relationship. More recently, that assumption has led to the conclusion that non-neutral sheaths can form inside electronegative plasmas, as well as at the boundaries. Such claims are surprising, given the shielding capability of plasmas. The present paper addresses the formation of both internal sheaths and double layers by reexamining the Bohm condition and the Boltzmann assumption.

Fernsler, Richard F.

2002-10-01

169

Research on thermionic plasmas  

NASA Astrophysics Data System (ADS)

Emitter sheath phenomena are important in thermionic energy conventors because the emitter sheath forms the boundary conditions for the plasma in the gap and controls both the ion loss rate and the loss rate of hot (3000 K) plasma electrons to the emitter. This thesis examines three expected emitter sheath phenomena and their effects on conventor performance: (1) reflection of ions coming from the plasma; (2) ions trapped in the double emitter sheath; and (3) surface emission ions. Inclusion of these 3 phenomena combined with elimination of previous sheath approximations requires careful analysis and calculation of the sheath structure. It is shown that the 'Bohm' matching condition must be generalized to insure that self-consistency prevails throughout the entire sheath and not just at the plasma-sheath interface. It is also shown that plasma ion distribution coming into that sheath must have its low energy ions cut off to produce a self-consistent collisionless sheath, and that each of these emitter sheath phenomena reduce the normalized (by plasma density) net loss rate to the emitter. Each of these phenomena also raises the normalized plasma density adjacent to the emitter. The higher plasma density at the emitter causes a greater increase in the loss of hot plasma electron energy to the emitter than the corresponding decrease in the loss of ionization energy (carried by the ions) to the emitter. Therefore these emitter sheath phenomena increase arcdrop. Within the limitations of the current thermionic conventor formulation, all three of these phenomena (which become significant at low currents) steepen the current-voltage characteristic.

Main, G. L.; Lam, S. H.

1984-06-01

170

Plasma theory and computations  

NASA Astrophysics Data System (ADS)

The general collaboration programs of plasma theory and computation conducted through the Nagoya Institute are described. The programs addressed the following subjects: (1) general fusion theory; (2) theoretical and computational studies of confinement physics: studies on Tokamak and stellerator, efforts for compact toroid, and works pertinent to reversed field pinch, bumpy torus and tandem mirror; (3) theoretical and computational studies on current drive, wave heating, and relevant problems; (4) fundamental problems in plasma theory: MHD turbulence, non-linear wave phenomena, and high density charged particle system; and (5) works in related fields as astrophysical plasma physics, stellar dynamics, and molecular dynamics.

1984-03-01

171

EDITORIAL: Laser and plasma accelerators Laser and plasma accelerators  

Microsoft Academic Search

This special issue on laser and plasma accelerators illustrates the rapid advancement and diverse applications of laser and plasma accelerators. Plasma is an attractive medium for particle acceleration because of the high electric field it can sustain, with studies of acceleration processes remaining one of the most important areas of research in both laboratory and astrophysical plasmas. The rapid advance

Robert Bingham

2009-01-01

172

Impulsive Plasma Produced by a Coaxial Plasma Gun  

Microsoft Academic Search

This paper is concerned with an impulsive plasma mass produced by a coaxial plasma gun. According to spectroscopic observation the following results have been obtained. When the plasma is produced with an oscillatory current, the gun ejects more than two plasma masses successively. Except the first one they consist mainly of impurities. Spectral lines from helium are recognized only in

Katsumi Hirano; Juichi Irisawa; Yoshiei Nakano

1969-01-01

173

Novel plasma generation devices based on the plasma lens  

Microsoft Academic Search

We describe some.novel plasma devices based on the electrostatic plasma lens configuration and plasma- optics principles. These low cost, high reliability, low maintenance devices can be used for manipulating heavy ion beams in a number of different applications for ion treatment and material surface modification. I. INTRODUCTION Primary features of plasma-optical devices for control of ion beams are the related

A. Goncharov; I. Brown

2004-01-01

174

Plasma diagnostics in plasma processing for nanotechnology and nanolevel chemistry  

Microsoft Academic Search

The author reviews the role of various plasma diagnostics in plasma processing for nanotechnology, and points out some essential methods of spectroscopic methods to diagnose plasmas for nanoprocessing. Two experimental examples are discussed between the characteristics of nanomaterials and plasma parameters. One is measurement of rotation temperature in processing of carbon nanotube. The other is that of vibrational temperature in

Hiroshi Akatsuka

2004-01-01

175

An inverse pinch plasma source for plasma opening switches  

Microsoft Academic Search

A plasma source has been developed for use in cylindrical plasma opening switches (POS). The “inverse pinch” (IP) produces a radially expanding plasma ring formed from a gas puff and is designed to be mounted inside the center conductor of a POS. Interferometric measurements and magnetic probes were used to study the expansion dynamics of the plasma that behaves similar

John J. Moschella; Richard C. Hazelton; Caterina Vidoli; Edward J. Yadlowsky

2000-01-01

176

Plasma renin activity and plasma aldosterone in acute renal failure  

Microsoft Academic Search

Plasma renin activity and plasma aldosterone were determined by radioimmunoassay methods in 20 patients in oliguric phase, in 11 patients in polyuric phase and in 7 patients in convalescent phase of acute renal failure of various origin. The oliguric phase of acute renal failure was characterized by significant increase of plasma renin activity and plasma aldosterone. There was no direct

M. Mydlík; K. Horký; P. Jonáš; I. Gregorová; I. Machá?ová; K. Derzsiová; M. Taká?

1980-01-01

177

Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma  

SciTech Connect

The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma.

A. Dunaevsky; N.J. Fisch

2003-10-02

178

Gingival plasma cell granuloma  

PubMed Central

Plasma cell granuloma, also known as inflammatory pseudotumor is a tumor-like lesion that manifests primarily in the lungs. But it may occur in various other anatomic locations like orbit, head and neck, liver and rarely in the oral cavity. We here report an exceedingly rare case of gingival plasma cell granuloma in a 58 year old woman who presented with upper gingival polypoidal growth. The histopathological examination revealed a mass composed of proliferation of benign spindle mesenchymal cells in a loose myxoid and fibrocollagenous stroma along with dense infiltrate of chronic inflammatory cells predominantly containing plasma cells. Immunohistochemistry for kappa and lambda light chains showed a polyclonal staining pattern confirming a diagnosis of plasma cell granuloma.

Pandav, Amitkumar B; Gosavi, Alka V; Lanjewar, Dhaneshwar N; Jagadale, Rakhi V

2012-01-01

179

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.

180

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

181

Plasma Motor Generator System.  

National Technical Information Service (NTIS)

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 ...

G. E. Hite

1987-01-01

182

Filamentary magnetohydrodynamic plasmas.  

National Technical Information Service (NTIS)

A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results ide...

R. Kinney T. Tajima N. Petviashvili J. C. McWilliams

1993-01-01

183

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

184

Simulation of Fusion Plasmas  

ScienceCinema

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.

185

Plasma Deposition of Tungsten.  

National Technical Information Service (NTIS)

Tungsten films were plasma-deposited using an abnormal glow discharge through a mixture of tungsten hexafluoride, hydrogen, and argon. The films adhered well to silicon, silicon dioxide, gallium arsenide, and aluminum substrates placed directly on the dis...

K. E. Greenberg

1986-01-01

186

PlasmaLyte.  

PubMed

PlasmaLyte is a family of balanced crystalloid solutions with multiple different formulations available worldwide according to regional clinical practices and preferences. It closely mimics human plasma in its content of electrolytes, osmolality, and pH. These solutions also have additional buffer capacity and contain anions such as acetate, gluconate, and even lactate that are converted to bicarbonate, CO2, and water. The advantages of PlasmaLyte include volume and electrolyte deficit correction while addressing acidosis. It shares the same problems as most other crystalloid fluids (fluid overload, edema with weight gain, lung edema, and worsening of the intracranial pressure). A unique concern is that most formulations contain magnesium, which may affect peripheral vascular resistance, heart rate, and worsen organ ischemia. There are few studies on its use in trauma or hypovolemic shock. There is no evidence that PlasmaLyte is superior to other crystalloids for the prehospital management of traumatic hypovolemia. PMID:21841561

Rizoli, Sandro

2011-05-01

187

Neutrino electron plasma instability  

NASA Astrophysics Data System (ADS)

Weak interactions play an important role in early universe plasma collection, especially on neutrinos and the corresponding leptons. It also has important effects on the detail balance of the primordial nucleosynthesis, especially on the production of He and light elements. At around T = 300 GeV, the primordial plasma undergone electroweak spontaneous symmetry breaking (SSB) phase transition. Some of the gauge bosons and other particles gain mass via Higgs mechanism. Deduced from Weinberg-Salam electroweak theory, a Boltzmann equation and subsequent fluid equations are derived for the primordial electron-positron-neutrino- photon plasma. A collective instability that separates the phases of electrons (and positrons) and neutrinos (and anti-neutrinos) is discussed. We also discussed the application of the fluctuation-dissipation theory in this system of plasma. An approach with Hubble expansion included in Boltzmann equation is also discussed. Astrophysical applications and implications are explored, particularly in supernovae.

Lai, Chi-Hsuan

1999-03-01

188

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

189

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

Institute, Space S.

2005-01-01

190

A Cold Plasma Jet Device With Multiple Plasma Plumes Merged  

Microsoft Academic Search

As nonthermal atmospheric pressure plasmas come to play an important role in diverse applications, reliable and arcing-free low-temperature plasma sources are needed urgently. In this paper, a low-temperature plasma jet device, which generated four plasma plumes simultaneously, is developed. The plasma jet device can be driven by pulsed dc or kilohertz ac power supply. There is no risk of arcing.

Xinpei Lu; Qing Xiong; Zhiyuan Tang; Zhonghe Jiang; Yuan Pan

2008-01-01

191

Plasma-Sheath Model  

NASA Astrophysics Data System (ADS)

In typical gas discharges a quasineutral plasma is shielded from a negativ absorbing wall by a thin positive sheath that is nearly planar and collision-free. The subdivision of ``plasma'' and ``sheath'' was introduced by Langmuir and is based on a small ratio of the electron Debye lenghth ?D to the dominant competing characteristic plasma length l. Depending on the special conditions, l may represent, e.g., the plasma extension, the ionization length, the ion mean free path, the ion gyro radius, or a geometric length. Strictly speaking, this subdivion is possible only in the asymptotic limit ?D/l->0. The asymptotic analysis results in singularities at the ``sheath edge'' closely related to the ``Bohm criterion.'' Due to these singularities a direct smooth matching of the separate plasma and sheath soltions is not possible. To obtain a consistent smooth transition, the singular sheath edge must be bridged by an additinal narrow ``intermediate'' model zone accounting both for plasma processes (e.g., collisions) and for the first build up of space charge. Due to this complexity and to different interpretations of the ``classical'' papers by Langmuir and Bohm, the asymptotic plasma-sheath concept and the definition of the sheath edge were questioned and resulted in controversies during the last two decades. We discuss attempts to re-define the sheath edge, to account for finite values of ?D/l in the Bohm criterion, and demonstrate the consistent matching of plasma and sheath. The investigations of the plasma-sheath transition discussed so far are based on a simplified fluid analysis that cannot account for the essential inhomogeneity of the boundary layer and for the dominant role of slow ions in space charge formation. Therefore we give special emphasis to the kinetic theory of the plasma-sheath transition. Unfortunately this approach results in an additional mathematical difficulty caused by ions with zero velocity. We discuss attempts to avoid this singularity by a modification of the kinetic Bohm criterion and investigate the influence of slow ions on the structure of the plasma-sheath transition. The most important conclusions are illustrated with selected examples.

Riemann, Karl-Ulrich

2012-10-01

192

Atmospheric-pressure plasma technology  

Microsoft Academic Search

Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona

U. Kogelschatz

2004-01-01

193

Fueling by coaxial plasma guns  

Microsoft Academic Search

A review of the operational characteristics of ''snowplow'' and ''deflagration'' coaxial plasma guns is given. The injection of these plasmas into containment fields is discussed. The effect of a background plasma on low-beta injection is mentioned. The use of high-beta injection for reactor plasmas is described. (MOW)

1977-01-01

194

An Introduction to Plasma Vortices.  

National Technical Information Service (NTIS)

An investigation is made of a property of plasmas which has far-reaching consequences for indoor plasmas as created in the laboratory and for outdoor (astrophysical) plasmas. The property is this: If a plasma exists in the presence of a magnetic field, fo...

J. Norwood D. R. Wells

1969-01-01

195

Plasma Redshift versus Big Bang  

Microsoft Academic Search

The newly discovered plasma redshift of photons penetrating hot plasmas gives a simpler, more accurate explanation of many cosmological phenomena than the Big-Bang cosmology. The plasma redshift of photons occurs only in hot low-density plasma. The corresponding energy loss of photons is converted into heat. This heating is responsible for the sharp temperature rise in the transition zone to the

Ari Brynjolfsson

2005-01-01

196

Pulsed Electromagnetic Acceleration of Plasmas.  

National Technical Information Service (NTIS)

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 s...

Y. C. F. Thio J. T. Cassibry T. E. Markusic

2002-01-01

197

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

198

Plasma pyrolysis of toxic waste  

Microsoft Academic Search

The comparison of technical economic indexes of different waste treatment methods and plasma pyrolysis is presented in the paper. It testifies that plasma technologies are economically expedient for these purposes. Physical prerequisites allowing realizing plasma technologies are presented. Reliable and economical (70–120 Euro per ton of treated product) plasma generation is the basic condition of the technology realization. In this

Ph G Rutberg

2003-01-01

199

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

200

Optical properties of cluster plasma  

Microsoft Academic Search

It is shown that unlike a gas plasma or an electron plasma in a metal, an ionized clustered material (``cluster plasma'') permits propagation below the plasma cut-off of electromagnetic (EM) waves whose phase velocity is close to but below the speed of light. Its unique properties allow a variety of applications, including direct acceleration of particles with its EM fields

T. Tajima; Y. Kishimoto; M. C. Downer

1999-01-01

201

Plasma contactor performance characterization  

NASA Astrophysics Data System (ADS)

The plasma contactor performance is outlined. Some performance objectives are given including expellant compatibility, high electron production capability, high ion production capability, high reliability for starting and operation, passive emission control, switchover capability between ion/electron emission, low ion and electron energies, low system mass, and low expellant consumption rate. The basic elements of the hollow cathode are shown along with key features of the plasma source.

Wilbur, P.

1986-06-01

202

[Plasma hypertonicity in children].  

PubMed

The plasma hypertonicity is a severe and quite frequent disorder in children. The most frequent causes are hypernatremia related conditions, even though other causes of hyperosmolarity, such as hyperglycaemia and exogenous solutes accumulation also occur. The management and treatment of this condition is delicate and requires a thorough understanding of the underlying hydro electrolytic disorder. The authors perform a theoretical review of plasma hypertonicity in children, focusing on the three most frequent associated conditions: hypernatremic dehydration, salt poisoning and hyperosmolar coma. PMID:20654264

Teixeira, Ana; Ribeiro, Augusto

2010-01-01

203

Plasma Screen Floating Mount  

DOEpatents

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

204

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

205

Strongly coupled colloidal plasmas  

NASA Astrophysics Data System (ADS)

The research of strongly coupled effects in colloidal plasmas started a few years ago with the discovery of the Coulomb crystallization of micron-sized particles in a plasma. The particles are charged negatively to a few thousands of electron charges due to the flux of electrons and ions from the plasma and then react via their Coulomb-potentials. The Coulomb coupling parameter ? - which is the ratio of the Coulomb energy between two neighboring particles to their thermal energy - could be much larger than the critical value of 172 (calculated for an one-component-plasma). That means that Coulomb-crystallization can be achieved easily. Such systems, which reach equilibrium very rapidly and can be easily tuned between their ordered and disordered states, are ideally suited for investigating the processes underlying the solid-to-liquid phase transition. Furthermore, the strongly coupled collidal plasma can be excited externally and the response can be studied in great detail dynamically. Gravity plays an important role for the production and stability of plasma crystals. In laboratory plasmas gravity has to be balanced out by the electrostatic field in the sheath of the electrodes of the experimental apparatus. Thus, in the vertical direction only monolayer crystals or crystals with a few lattice layers can be formed. This restricts the analysis to processes in 2-dimensional or ``2 1/2-dimensional'' crystals (e.g. the physics of monolayers, nano-crystals or grain boundaries). Under zero gravity larger (volume) systems are possible and the field of plasma crystal research can be extended to include the physics of 3-dimensional systems. We performed the worldwide first experiments under zero-g conditions on parabolic flights and two sounding rockets. During these experiments the behaviour of dust particles in a rf-discharge under zero-g conditions was investigated. Very interesting experiments were performed, which are possible only under low gravity conditions.

Thomas, Hubertus M.; Morfill, Gregor E.; Konopka, Uwe; Rothermel, Hermann; Zuzic, Milenko

1998-11-01

206

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

207

Plasma diagnostics and plasma-surface interactions in inductively coupled plasmas  

Microsoft Academic Search

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 \\

Monica Joy Titus

2010-01-01

208

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

NASA Astrophysics Data System (ADS)

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.; Helander, P.; Xanthopoulos, P.; Connor, J. W.

2014-03-01

209

Understanding helicon plasmas  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive overview of work on the helicon plasmas and also discusses various aspects of RF power deposition in such plasmas. Some of the work presented here is a review of earlier work on theoretical [A. Ganguli et al., Phys. Plasmas 14, 113503 (2007)] and experimental [A. Ganguli et al., Plasma Sources Sci. Technol. 20(1), 015021 (2011)] investigations on helicon plasmas in a conducting cylindrical waveguide for m = -1 mode. This work also presents an approach to investigate the mechanisms by which the helicon and associated Trivelpiece-Gould (TG) waves are responsible for RF power deposition in Helicon discharges. Experiment design adopts the recent theory of damping and absorption of Helicon modes in conducting waveguides [A. Ganguli et al., Phys. Plasmas 14, 113503 (2007)]. The effort has also been made to detect the warm electrons, which are necessary for ionization, because Helicon discharges are of high density, low Te discharges and the tail of the bulk electron population may not have sufficient high-energy electrons. Experimental set up also comprises of the mirror magnetic field. Measurements using RF compensated Langmuir probes [A. Ganguli et al., Plasma Sources Sci. Technol. 17, 015003 (2008)], B-dot probe and computations based on the theory shows that the warm electrons at low pressure (0.2-0.3 mTorr) Helicon discharges, are because of the Landau damping of TG waves. In collisional environment, at a pressure ~10 mTorr, these high-energy electrons are due to the acceleration of bulk electrons from the neighboring regions across steep potential gradients possibly by the formation of double layers.

Tarey, R. D.; Sahu, B. B.; Ganguli, A.

2012-07-01

210

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

211

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

212

Microphysics in Astrophysical Plasmas  

NASA Astrophysics Data System (ADS)

Although macroscale features dominate astrophysical images and energetics, the physics is controlled through microscale transport processes (conduction, diffusion) that mediate the flow of mass, momentum, energy, and charge. These microphysical processes manifest themselves in key (all) boundary layers and also operate within the body of the plasma. Crucially, most plasmas of interest are rarefied to the extent that classical particle collision length- and time-scales are long. Collective plasma kinetic phenomena then serve to scatter or otherwise modify the particle distribution functions and in so-doing govern the transport at the microscale level. Thus collisionless plasmas are capable of supporting thin shocks, current sheets which may be prone to magnetic reconnection, and the dissipation of turbulence cascades at kinetic scales. This paper lays the foundation for the accompanying collection that explores the current state of knowledge in this subject. The richness of plasma kinetic phenomena brings with it a rich diversity of microphysics that does not always, if ever, simply mimic classical collision-dominated transport. This can couple the macro- and microscale physics in profound ways, and in ways which thus depend on the astrophysical context.

Schwartz, Steven J.; Zweibel, Ellen G.; Goldman, Martin

2013-10-01

213

Plasma theory and simulation  

NASA Astrophysics Data System (ADS)

The Pierce diode linear behavior with external R, C, or L was verified very accurately by particle simulation. The Pierce diode non-linear equilibria with R, C, or L are described theoretically and explored via computer simulation. A simple model of the sheath outside the separatrix of an FRC was modeled electrostatically in 2d and large potentials due to the magnetic well and peak which were found. These may explain the anomalously high ion confinement in the FRC edge layer. A planar plasma source with cold ions and warm electrons produces a source sheath with sufficient potential drop to accelerate ions to sound velocity, which obviates the need for a Bohm pre-collector-sheath electric field. Final reports were prepared for collector sheath, presheath, and source sheath in a collisionless, finite ion temperature plasma; potential drop and transport in a bounded plasma with ion reflection at the collector; potential drop and transport in a bounded plasma with secondary electron emission at the collector. A movie has been made displaying the long-lived vortices resulting from the Kelvin-Helmholtz instability in a magnetized sheath. A relativistic Monte Carlo binary (Coulomb) collision model has been developed and tested for inclusion into the electrostatic particle simulation code TESS. Two direct implicit time integration schemes are tested for self-heating and self-cooling and regions of neither are found as a function of delta t and delta x for the model of a freely expanding plasma slab.

Birdsall, Charles K.

1986-12-01

214

Plasma Colloquium Travel Grant Program  

SciTech Connect

OAK B188 Plasma Colloquium Travel Grant Program. The purpose of the Travel Grant Program is to increase the awareness of plasma research. The new results and techniques of plasma research in fusion plasmas, plasma processing space plasmas, basic plasma science, etc, have broad applicability throughout science. The benefits of these results are limited by the relatively low awareness and appreciation of plasma research in the larger scientific community. Whereas spontaneous interactions between plasma scientists and other scientists are useful, a focused effort in education and outreach to other scientists is efficient and is needed. The academic scientific community is the initial focus of this effort, since that permits access to a broad cross-section of scientists and future scientists including undergraduates, graduate students, faculty, and research staff.

Hazeltine, R.D.

1998-09-14

215

Relaxation of magnetotail plasmas  

NASA Technical Reports Server (NTRS)

A quasi-thermodynamic model is presented for the relaxation of magnetotail plasmas during substorms, followed by quiet times. It is proposed that the plasma relaxes to a state of low-potential energy subject to a small number of global constraints. The constraints are exactly preserved by all ideal motions and, approximately, by a wide class of motions of the plasma undergoing magnetic reconnection. A variational principle which minimizes the free energy predicts the relaxed state. Exact, two-dimensional solutions of the relaxed state are obtained. A universal feature of the exact solutions is a chain of magnetic islands along the tail axis. Sufficient conditions for the stability of relaxed states are obtained from the second variation of the free-energy functional.

Bhattacharjee, A.

1987-01-01

216

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.

2007-05-04

217

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.

218

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

219

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

220

Deflagration plasma thruster  

NASA Technical Reports Server (NTRS)

This paper introduces the application of the magnetized plasma deflagration process to space propulsion. The deflagration process has the unique capability of efficiently converting input energy into kinetic energy in the accelerating direction. To illustrate the totally divergent characters of 'snowplow' detonation and deflagration discharges, examples of the differences between deflagration and detonation 'snowplow' discharges are expressed in terms of current densities, temperature, and particle velocities. Magnetic field profiles of the deflagration mode of discharges are measured. Typical attainable plasma characteristics are described in terms of velocity, electron temperature, and density, as well as measurement techniques. Specific impulses measured by piezo-electric probe and pendulum methods are presented. The influence of the transmission line in the discharge circuits on plasma velocity is measured by means of a microwave time-of-flight method. The results for the deflagration thruster are compared with other space thrusters. Further research areas are identified.

Cheng, D. Y.; Chang, C. N.

1984-01-01

221

Dusty Silane Plasmas  

NASA Astrophysics Data System (ADS)

A low pressure capacitively coupled radio frequency discharge using 5% silane in argon is studied. Special emphasis is put on the initial stages of dust formation immediately after ignition of the discharge. The particle polymerisation process as well as the particle plasma interaction are studied. The latter is evident in changing electrical characterics of the discharge outside (current and voltage) as well as inside (plasma density) the plasma. Several diagnostic techniques will be combined to obtain a complete picture. Diagnostics which currently are under development are: infrared cavity ringdown spectroscopy to determine chemical characteristics; fast measurement of voltage and current of the driving rf frequency and its higher harmonics; microwave resonance for electron density determination and laser induced photodetachment for ion density and particle charge.

Stoffels, Winfred; Remy, Jerome; Sorokine, Mikhail; Groothuis, Charlotte; Kroesen, Gerrit

2002-10-01

222

Laser spectroscopy of thermal plasma  

NASA Astrophysics Data System (ADS)

Thermal plasma, due to its applications, is a research field of great importance, but reliable diagnostics of such plasma remains a challenging task. Spatially resolved methods, which provide local values of plasma parameters, are crucial for understanding the underlying physics. This can be achieved using pump–probe techniques. Two methods applicable and useful for thermal plasma diagnostics—four-wave mixing and scattering of laser beams—are discussed in this paper. Experimental examples of their application, namely four-wave mixing in argon arc plasma and scattering of laser light by laser-induced plasma, are presented.

Pokrzywka, Bart?omiej; Dzier??ga, Krzysztof; Mendys, Agata; Pellerin, Stephane

2014-05-01

223

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

224

Undamped plasma waves  

NASA Technical Reports Server (NTRS)

This paper describes small-amplitude nonlinear plasma wave solutions to the one-dimensional Vlasov-Maxwell equations. A sufficient condition for waves of a given phase velocity to exist arbitrarily close to a given spatially uniform Vlasov equilibrium is developed, and sufficient analytical information for the construction of approximate expressions for the electric potential and distribution functions is derived, with exact knowledge of the asymptotic behavior of the error terms. These results have a very surprising physical implication: the Landau damping of small-amplitude waves is not inevitable. Instead, there exist plasma waves that trap particles even at arbitrarily small amplitude and do not damp.

Holloway, James P.; Dorning, J. J.

1991-01-01

225

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

226

Dense astrophysical plasmas.  

PubMed

Degenerate bodies composed primarily of dense hydrogen and helium plasmas range from giant planets to the so far hypothetical brown dwarfs. More massive objects begin their lives as nondegenerate stars and may end as white dwarfs, composed primarily of carbon and oxygen, or as neutron stars, with solid crusts of iron or heavier elements and cores of neutron matter. The physical properties of dense plasmas that are necessary to construct theoretical models of such degenerate stars include the equation of state, transport properties, and nuclear reaction rates. PMID:17740936

VAN Horn, H M

1991-04-19

227

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

228

Plasma Spray System  

NASA Technical Reports Server (NTRS)

Computer aided, fully-automatic TRW system sprays very hot plasma onto a turbine blade. Composed of gas into which metallic and ceramic powders have been injected, the plasma forms a two-layer coating which insulates the blade. Critical part of operation is controlling the thickness of the deposit which is measured in thousandths of an inch. This is accomplished by an optical detector which illuminates spots at various locations on the blade and determines thickness by measuring the light reflections. Optical sensor monitors spraying process until precise thickness is attained, then computer halts the spraying.

1980-01-01

229

Nonlinear Quantum Plasma Physics  

NASA Astrophysics Data System (ADS)

We present simulation studies of the formation and dynamics of dark solitons and vortices, and of nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) dense in quantum electron plasmas. The electron dynamics in the latter is governed by a pair of equations comprising the nonlinear Schrödinger and Poisson system of equations, which conserves electrons and their momentum and energy. Nonlinear fluid simulations are carried out to investigate the properties of fully developed two-dimensional (2D) electron fluid turbulence in a dense Fermi (quantum) plasma. We report several distinguished features that have resulted from our 2D computer simulations of the nonlinear equations which govern the dynamics of nonlinearly interacting electron plasma oscillations (EPOs) in the Fermi plasma. We find that a 2D quantum electron plasma exhibits dual cascades, in which the electron number density cascades towards smaller turbulent scales, while the electrostatic potential forms larger scale eddies. The characteristic turbulent spectrum associated with the nonlinear electron plasma oscillations determined critically by quantum tunneling effect. The turbulent transport corresponding to the large-scale potential distribution is predominant in comparison with the small-scale electron number density variation, a result that is consistent with the classical diffusion theory. The dynamics of the CPEM waves is also governed by a nonlinear schrödinger equation, which is nonlinearly coupled with the nonlinear Schrödinger equation of the EPOs via the relativistic ponderomotive force, the relativistic electron mass increase in the CPEM field, and the electron density fluctuations. The present governing equations in one spatial dimension admit stationary solutions in the form a dark envelope soliton. The dynamics of the latter reveals its robustness. Furthermore, we numerically demonstrate the existence of cylindrically symmetric two-dimensional quantum electron vortices, which survive during collisions. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma.

Shukla, Padma K.; Eliasson, Bengt; Shaikh, Dastgeer

230

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

231

Electromagnetic strong plasma turbulence  

NASA Astrophysics Data System (ADS)

The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c<=v<=0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v>=0.1c to just free eigenstates for v<=0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

Melatos, A.; Jenet, F. A.; Robinson, P. A.

2007-02-01

232

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

233

Some plasma aspects and plasma diagnostics of ion sources.  

PubMed

We consider plasma properties in the most advanced type of plasma ion sources, electron cyclotron resonance ion sources for highly charged ions. Depending on the operation conditions the plasma in these sources may be highly ionized, which completely changes its transport properties. The most striking difference to weakly ionized plasma is that diffusion will become intrinsically ambipolar. We further discuss means of plasma diagnostics. As noninvasive diagnostic methods we will discuss analysis of the ion beam, optical spectroscopy, and measurement of the x-ray bremsstrahlung continuum. From beam analysis and optical spectroscopy one may deduce ion densities, and electron densities and distribution functions as a mean over the line of sight along the axis (optical spectroscopy) or at the plasma edge (ion beam). From x-ray spectra one obtains information about the population of highly energetic electrons and the energy transfer from the driving electromagnetic waves to the plasma -- basic data for plasma modeling. PMID:18315191

Wiesemann, Klaus

2008-02-01

234

Design of a Plasma Injector for a Pulsed Plasma Accelerator  

NASA Technical Reports Server (NTRS)

In recent years, a pulsed plasma accelerator has been proposed as a candidate stand-off driver for the formation of an imploding liner in magnetized target fusion. For a near-term physics exploratory experiment to study the feasibility of this standoff approach, a plasma accelerator has been proposed that requires the controlled introduction and preparation of the initial plasma for acceleration. This includes uniform injection of the propellant downstream of the breech with a high degree of ionization. The design of a plasma feed is presented, which injects a high conductivity, highly collisional propellant transverse to the conductor. The plasma injector is designed to establish an initial plasma with a moderate Hall parameter at the trailing edge of the plasma slug, high Hall parameter behind the slug for magnetic insulation, and a short diffusion length in comparison with characteristic dimensions of the plasma slug to avoid propellant loss at the trailing edge.

Cassibry, J. T.; Thio, Y. C. F.; Markusic, T. E.; Sommers, J.; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

235

Design of A Plasma Injector for a Pulsed Plasma Accelerator  

NASA Astrophysics Data System (ADS)

In recent years, a pulsed plasma accelerator has been proposed as a candidate stand-off driver for the formation of an imploding liner in magnetized target fusion. For a near-term physics exploratory experiment to study the feasibility of this standoff approach, a plasma accelerator has been proposed that requires the controlled introduction and preparation of the initial plasma for acceleration. This includes uniform injection of the propellant downstream of the breech with a high degree of ionization. The design of a plasma feed is presented, which injects a high conductivity, highly collisional propellant transverse to the conductor. The plasma injector is designed to establish an initial plasma with a moderate Hall parameter at the trailing edge of the plasma slug, high Hall parameter behind the slug for magnetic insulation, and a short diffusion length in comparison with characteristic dimensions of the plasma slug to avoid propellant loss at the trailing edge. The development has applications in space propulsion.

Cassibry, Jason; Thio, Y. C. Francis; Markusic, Thomas; Sommer, James

2002-11-01

236

A contoured gap coaxial plasma gun with injected plasma armature  

Microsoft Academic Search

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 mug of plasma with density above 1017 cm-3 to greater than 200 km\\/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined

F. Douglas Witherspoon; Andrew Case; Sarah J. Messer; Richard Bomgardner; Michael W. Phillips; Samuel Brockington; Raymond Elton

2009-01-01

237

Relativistic Plasma Physics 3.Relativistic Laser-Plasma Interaction (1)  

Microsoft Academic Search

Relativistic laser-plasma interaction is one of the more active topics in recent plasma physics. In this paper, the laser-plasma interactions in underdense plasmas are explained briefly, and the related experimental results and numerical simulations are introduced. Several characteristic phenomena, including relativistic self-focusing, nonlinear laser wake field, nonlinear parametric scattering and so on, are analyzed using a quasi-static approximation model. However,

Keisuke Nagashima

2002-01-01

238

Measurement of plasma parameters in an inductively coupled plasma reactor  

Microsoft Academic Search

The objective is to deepen the understanding of basic plasma properties in a high-density inductively coupled plasma (ICP) reactor. The experiment using a Langmuir probe, which is made of tungsten wire having length of 2.3 mm and diameter of 0.65 mm, is carried out to determine the characteristics of argon plasma. The axial and radial distributions of the plasma density,

Hiroshi Sasaki; Kenichi Nanbu; Masayoshi Takahashi

2001-01-01

239

Laser-plasma interactions in ignition-scale hohlraum plasmas  

Microsoft Academic Search

Scattering of laser light by stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) is a concern for indirect drive inertial confinement fusion (ICF). The hohlraum designs for the National Ignition Facility (NIF) raise particular concerns due to the large scale and homogeneity of the plasmas within them. Experiments at Nova have studied laser–plasma interactions within large scale length plasmas

B. J. MacGowan; B. B. Afeyan; C. A. Back; R. L. Berger; G. Bonnaud; M. Casanova; B. I. Cohen; D. E. Desenne; D. F. Dubois; A. G. Dulieu; K. G. Estabrook; J. C. Fernandez; S. H. Glenzer; D. E. Hinkel; T. B. Kaiser; R. L. Kauffman; R. K. Kirkwood; W. L. Kruer; A. B. Langdon; B. F. Lasinski; D. S. Montgomery; J. D. Moody; D. H. Munro; L. V. Powers; H. A. Rose; C. Rousseaux; R. E. Turner; B. H. Wilde; S. C. Wilks; E. A. Williams

1996-01-01

240

Formation of the plasma layer in a plasma focus device  

Microsoft Academic Search

The formation of the current carrying plasma layer in a plasma focus device has been studied using time resolved photographs and space and time resolved magnetic flux measurements. The magnetic flux time derivative has been recorded through two magnetic probes, noting no distortion of the plasma layer by the probe. The formation of a double layer produced by a discharge

H. Krompholz; W. Neff; F. Ruehl; K. Schoenbach; G. Herziger

1980-01-01

241

Impurity Content of Plasma Produced by a Coaxial Plasma Gun  

Microsoft Academic Search

The impurity content of plasmas produced by a coaxial plasma gun, while ; low, has generally been estimated by measurements of qualitative nature. Since ; impurities constitute the primary source of radiation loss and cooling, a study ; was made to explore this plasma property. (R.E.U.);

Harold P. Eubank

1963-01-01

242

Studies of Plasma Expelled from a Coaxial Plasma Gun  

Microsoft Academic Search

An experimental study of the plasma leaving a coaxial gun is described. The plasma shows a conical shape with a central axial pinch. When a radial magnetic field is applied at the muzzle of the gun, magnetized plasma rings are formed. Under certain conditions the central pinch shows a helical instability, resulting in a considerable increase of the poloidal magnetic

L. Lindberg; C. T. Jacobsen

1964-01-01

243

Plasma Polarization Spectroscopy: Principles and Application to Laboratory Plasmas  

Microsoft Academic Search

An ensemble of atoms or ions in plasma is expressed in terms of population and alignment of excited levels and the ground state. If the plasma is spatially anisotropic, an alignment is produced along with a population in an excited level, and the emission line originating from this level becomes linearly polarized. Plasma Polarization Spectroscopy (PPS) is a new technique

Takashi Fujimoto

1998-01-01

244

THE ROLE OF PLASMA VORTICES IN PLASMA TURBULENCE  

Microsoft Academic Search

The generation mechanisms of plasma vortices in geometries such as those ; occurring in the coaxial accelerator, in the conical theta -pinch, and when a ; plasma from a field-free region encounters a magnetic field which is ; perpendicular to the direction of propagation of the plasma are discussed. When ; the vortices are numerous and random, they are called

Bostick

1963-01-01

245

Tokamak plasma self-organization---synergetics of magnetic trap plasmas  

Microsoft Academic Search

Analysis of a wide range of experimental results in plasma magnetic confinement investigations shows that in most cases, plasmas are self-organized. In the tokamak case, it is realized in the self-consistent pressure profile, which permits the tokamak plasma to be macroscopically MHD stable. Existing experimental data permit suggesting a hypothesis about the mechanism of pressure profile regulation and to give

K. A. Razumova; V. F. Andreev; L. G. Eliseev; A. Ya. Kislov; R. J. La Haye; S. E. Lysenko; A. V. Melnikov; G. E. Notkin; Yu. D. Pavlov; M. Yu. Kantor

2011-01-01

246

Design of A Plasma Injector for a Pulsed Plasma Accelerator  

Microsoft Academic Search

In recent years, a pulsed plasma accelerator has been proposed as a candidate stand-off driver for the formation of an imploding liner in magnetized target fusion. For a near-term physics exploratory experiment to study the feasibility of this standoff approach, a plasma accelerator has been proposed that requires the controlled introduction and preparation of the initial plasma for acceleration. This

Jason Cassibry; Y. C. Francis Thio; Thomas Markusic; James Sommer

2002-01-01

247

Magnetized Plasma Experiments Using Thermionic- Thermoelectronic Plasma Emitter  

NASA Astrophysics Data System (ADS)

We are developing a magnetic mirror device, which is the first magnetized plasma device in Taiwan, to explore basic plasma sciences relevant to fusion, space and astrophysical plasmas. Our research subjects include electromagnetically induced transparency (EIT), Alfven wave physics, and plasma turbulence. A large diameter (> 200 mm) plasma emitter1, which utilizes thermionic- thermoelectronic emission from a mixture of LaB6 (Lanthanum-hexaboride) and beta-eucryptite (lithium type aluminosylicate) powders, is employed as a plasma source because of its production ability of fully ionized plasma and controllability of plasma emission rate. The plasma emitter has been installed recently and investigation of its characteristics will be started. The employment of beta-eucryptite in plasma emitter is the first experimental test because such investigation of beta-eucryptite has previously been used only for Li+-ion source2. Our plan for magnetized plasma experiments and results of the plasma emitter investigation will be presented. 1. K. Saeki, S. Iizuka, N. Sato, and Y. Hatta, Appl. Phys. Lett., 37, 1980, pp. 37-38. 2. M. Ueda, R. R. Silva, R. M. Oliveira, H. Iguchi, J. Fujita and K. Kadota, J. Phys. D: Appl. Phys. 30 1997, pp. 2711--2716.

Kawamori, Eiichirou; Cheng, C. Z.; Fujikawa, Nobuko; Lee, Jyun-Yi; Peng, Albert

2008-11-01

248

Shock Physics of Nonideal Plasmas.  

National Technical Information Service (NTIS)

This study is an experimental investigation of nonideal plasmas produced by strong shock waves. The study centered about the understanding of factors controlling the specific energy and transport properties of dense plasma in an explosively energized plas...

D. W. Baum W. L. Shimmin R. F. Flagg S. P. Gill D. Mukherjee

1979-01-01

249

Suspension and solution plasma spraying  

NASA Astrophysics Data System (ADS)

Suspension and solution plasma spraying makes it possible to achieve coatings with fine microstructural features and is becoming a common route in laboratories to elaborate coatings a few tenths to a few hundreds of micrometres thick. This paper presents the recent developments in direct current plasma spraying of suspensions or solutions. It begins with a short description of the main plasma torches used for liquid feedstock spraying as well as the techniques used to experimentally observe droplets and particles in the plasma jet and characterize the void network of nanostructured plasma-sprayed coatings. The paper then turns to the momentum and heat transfers between fine particles and the plasma jet and the interactions between the plasma jet and a liquid in the form of a jet or drops. It concludes by linking some characteristic features of coating microstructures with the liquid processing in the plasma jet.

Fauchais, P.; Joulia, A.; Goutier, S.; Chazelas, C.; Vardelle, M.; Vardelle, A.; Rossignol, S.

2013-06-01

250

Theoretical Solar Terrestrial Plasma Physics.  

National Technical Information Service (NTIS)

A nonlinear fluctuation - dissipation theorem relating quadratic plasma response functions to ternary equilibrium correlations has been derived. Large ampligude non-linear waves in a magnetized plasma with and without collisions have been studied. A compu...

G. Kalman P. Bakshi

1971-01-01

251

Electrostatic-Inertial Plasma Confinement.  

National Technical Information Service (NTIS)

The work was directed towards an answer to the question: 'How dense a plasma can be confined by electrostatic-inertial means.' Electrostatic-inertial plasma confinement consists of trapping charged particles in potential wells (of the electric field), whi...

T. J. Dolan J. T. Verdeyen B. E. Cherrington D. J. Meeker

1970-01-01

252

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

253

Study of Cryogenic Complex Plasma.  

National Technical Information Service (NTIS)

This Report describes the investigation entitled by 'Study of Cryogenic Complex Plasma.' The research has been carried out at Yokohama National University. Our overall goal is to study the cryogenic complex plasma experimentally and theoretically and to r...

C. Kijima M. Shindo O. Ishihara Y. Nakamura

2007-01-01

254

Platelet-Rich Plasma (PRP)  

MedlinePLUS

... 2011 American Academy of Orthopaedic Surgeons Platelet-Rich Plasma (PRP) During the past several years, much has been written about a preparation called platelet-rich plasma (PRP) and its potential effectiveness in the treatment ...

255

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

256

Plasma Arc Machining.  

National Technical Information Service (NTIS)

The concept of metal removal by Plasma-Arc machining utilizing DC transferred and non-transferred arc techniques was explored. Tests on various metal alloys at a power level of 50KW show that optimum torch-to-work geometry, feed and surface speed provide ...

J. F. Ordway G. A. Colligan J. A. Browning

1966-01-01

257

Plasma Focus Device Study.  

National Technical Information Service (NTIS)

A program to determine the X-ray and neutron yields from a plasma focus device as a function of capacitor bank energy was carried out. The capacitor bank energy was varied from 20 kJ to 90 kJ, and empirical scaling laws were determined. In addition, X-ray...

H. F. Rugge D. E. Maxwell S. A. Zwick

1967-01-01

258

Pulverized coal plasma gasification  

Microsoft Academic Search

A number of experiments on the plasma-vapor gasification of brown coals of three types have been carried out using an experimental plant with an electric-arc reactor of the combined type. On the basis of the material and heat balances, process parameters have been obtained: the degree of carbon gasification (?c), the level of sulfur conversion into the gas phase (?s),

R. A. Kalinenko; A. P. Kuznetsov; A. A. Levitsky; V. E. Messerle; Yu. A. Mirokhin; L. S. Polak; Z. B. Sakipov; A. B. Ustimenko

1993-01-01

259

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

260

Modeling electronegative plasma discharges  

SciTech Connect

A macroscopic analytic model for a three-component electronegative plasma has been developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is found. The electron density is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane rf driven oxygen plasma for two cases: (1) [ital p]=50 mTorr, [ital n][sub [ital e]0]=2.4[times]10[sup 15] m[sup [minus]3], and (2) 10 mTorr, [ital n][sub [ital e]0]=1.0[times]10[sup 16] m[sup [minus]3]. In the simulation, for the low power case (1), the ratio of negative ion to electron density was found to be [alpha][sub 0][approx]8, while in the higher power case [alpha][sub 0][approx]1.3. Using an electron energy distribution that approximates the simulation distribution by a two-temperature Maxwellian, the analytic values of [alpha][sub 0] are found to be close to, but somewhat larger than, the simulation values. The average electron temperature found self-cosistently in the model is close to that in the simulation. The results indicate the need for determining a two-temperature electron distribution self-consistently within the model.

Lichtenberg, A.J.; Vahedi, V.; Lieberman, M.A. (Department of Electrical Engineering and Computer Sciences and the Electronics Research Laboratory, University of California, Berkeley, California 94720 (United States)); Rognlien, T. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1994-03-01

261

Radioimmunoassay of Plasma Corticotrophin.  

National Technical Information Service (NTIS)

An assay has been established, based on antibodies against the N-terminal part of the ACTH molecule with a high affinity, a detection limit of 2 pg ACTH when assaying 200 ul unextracted plasma, and implying a total incubation time of three days. The antib...

L. Hummer

1977-01-01

262

High Pressure Plasma Research.  

National Technical Information Service (NTIS)

The research goals, the approach, and the results of the High Pressure Plasma Research, Group V-4, are presented. Also included is a brief description of Air Force applications of this research as well as comprehensive list of publications and presentatio...

U. H. Bauder

1972-01-01

263

Principles of Plasma Spectroscopy  

Microsoft Academic Search

This monograph presents a comprehensive description of the theoretical foundations and experimental applications of spectroscopic methods in plasma physics research. The first three chapters introduce the classical and quantum theory of radiation, with detailed descriptions of line strengths and high density effects. The next chapter describes theoretical and experimental aspects of spectral line broadening. The following five chapters are concerned

Hans R. Griem

2005-01-01

264

Solitary vortices in plasmas  

Microsoft Academic Search

Recent work in the nonlinear theory of drift and Alfven waves in plasmas is reviewed. In such waves, even at comparatively small amplitudes, nonlinearity gives rise to qualitatively new effects. Stationary drift waves can exist only as solitary two-dimensional vortices which are traveling in a direction nearly perpendicular to the magnetic field and to the density gradient. Because of their

V. I. Petviashvili; O. A. Pokhotelov

1986-01-01

265

Solitary vortices in plasma  

Microsoft Academic Search

Recent research related to the nonlinear theory of drift and Alfven waves in plasma is reviewed. In particular, it is noted that, in such waves, nonlinearity gives rise to qualitatively new effects even at relatively low amplitudes. Stationary drift waves can exist only in the form of two-dimensional solitary vortices. Due to their local nature, such vortices are insensitive to

V. I. Petviashvili; O. A. Pokhotelov

1986-01-01

266

Filamentary magnetohydrodynamic plasmas  

NASA Astrophysics Data System (ADS)

A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.

Kinney, R.; Tajima, T.; Petviashvili, N.; McWilliams, J. C.

1993-05-01

267

Filamentary magnetohydrodynamic plasmas  

SciTech Connect

A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsaesser variables is developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. A statistical treatment of a collection of discrete current-vorticity concentrations is given. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is presented as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a nonzero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. Possible applications to a variety of physical phenomena are suggested.

Kinney, R.; Tajima, T. (Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)); McWilliams, J.C. (National Center for Atmospheric Research, Boulder, Colorado 80307 (United States)); Petviashvili, N. (Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States))

1994-02-01

268

Plasma conductivity gage  

NASA Technical Reports Server (NTRS)

Gage permits determination of stagnation conductivity from measurement of shunt impedance presented by the plasma between the inner and outer conductors of a segment of coaxial transmission line. Response of gage permits its use in shock-tube work and research on explosive propagation.

Gill, S. P.

1970-01-01

269

Plasma based accelerators  

SciTech Connect

A plasma medium can support a variety of wave motions which may be useful for accelerating charged particles. For highly relativistic beams the longitudinal electrostatic wave is most suitable and may be driven by laser or by particle beams. The basic principles, limitations and prospects for these devices are discussed.

Evans, R.G.

1987-05-05

270

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

271

Lassa Fever Immune Plasma.  

National Technical Information Service (NTIS)

122 Units of plasma were obtained in Liberia from convalescents from Lassa fever. 98 units were forwarded to the USAMRIID for its use, of these, 59 were found to have Log Neutralization titers of 00.3 or higher, indicating a protective value against Lassa...

J. D. Frame

1983-01-01

272

Lassa Fever Immune Plasma.  

National Technical Information Service (NTIS)

One hundred forty-one Lassa Fever Immune Plasma (LFIP)Units have been obtained by plasmapheresis in the last 12 months; 59 have been forwarded to USAMRIID and 16 more are awaiting shipment to the United States. Virological and serological testing for Lass...

J. D. Frame

1984-01-01

273

Plasma Redshift Cosmology  

Microsoft Academic Search

The newly discovered plasma redshift cross section explains a long range of phenomena; including the cosmological redshift, and the intrinsic redshift of Sun, stars, galaxies and quasars. It explains the beautiful black body spectrum of the CMB, and it predicts correctly: a) the observed XRB, b) the magnitude redshift relation for supernovae, and c) the surface- brightness-redshift relation for galaxies.

Ari Brynjolfsson

2011-01-01

274

On the Plasma Sheath†  

Microsoft Academic Search

A formalism has been devised for dealing efficaciously with the vexatious boundary-valued, one-dimensional sheath problem which admits series solutions that automatically yield the Bohm stability criterion. A great advantage enjoyed by the present theory is the embodiment of natural boundary conditions associated with the region where the sheath and ambient plasma potentials merge. In this manner the much criticized and

LOUIS GOLD

1964-01-01

275

Vacuum plasma spray coating  

NASA Technical Reports Server (NTRS)

Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

Holmes, Richard R.; Mckechnie, Timothy N.

1989-01-01

276

Plasma heating in JET  

Microsoft Academic Search

Heating the JET plasma well above temperatures reached in the ohmic phase is the aim of the two additional heating systems planned for JET: ion cyclotron resonance heating (ICRF) and neutral beam injection (NBI). Operations with the latter started in February 1986, initially with hydrogen injection, up to a power level of 7 MW. ICRF power has been delivered to

A. Ainsworth; H. Altmann; R. J. Anderson; J. Arbez; D. Bartlett; W. Bailey; K. Behringer; E. Bertolini; P. Bertoldi; C. H. Best; V. Bhatnagar; R. J. Bickerton; G. Boissin; T. Bonicelli; S. Booth; A. Boschi; G. Bosia; M. Botman; H. Brelen; H. Brinkschulte; M. L. Browne; M. Brusati; T. Budd; M. Bures; P. Butcher; H. Buttgereit; D. Cacaut; C. Caldwell-Nichols; D. Campbell; J. Carwardine; G. Celentano; C. D. Challis; A. Cheetman; J. Christiansen; C. Christodoulopoulos; P. Chuilon; R. Claesen; J. P. Coad; M. Cooke; J. G. Cordey; W. Core; S. Corti; A. E. Costley; G. Cottrell; J. Dean; E. Deksnis; G. Deschamps; K. J. Dietz; J. Dobbing; S. E. Dorling; D. F. Duechs; G. Duesing; H. Duquenoy; L. de Kock; A. Edwards; W. Engelhardt; F. Erhorn; B. Eriksson; H. Falter; T. Hellsten; J. L. Hemmerich; R. Hemsworth; F. Hendriks; R. F. Herzog; L. Horton; J. How; M. Huart; A. Hubbard; M. Hugon; P. Jones; J. Kaeline; A. Kaellne; A. Kaye; B. E. Keen; M. Keilhacker; G. Kinahan; A. Konstantellos; P. Kupschus; P. Lallia; J. R. Last; N. Foden; C. Froger; K. Fullard; A. Galetsas; A. Gallacher; A. Gibson; R. D. Gill; A. Geode; A. Gondhalekar; N. A. Gottardi; C. Gowers; R. Granetz; B. Green; S. Gregoli; F. S. Griph; R. Haange; C. J. Hancock; P. Harbour; R. F. Herog; J. Kaellne; L. Lauro-Taroni; E. Lazzaro; R. C. Lobel; P. Lomas; M. Lorenzo-Gottardi; C. Lowry; G. Magyar; D. Maissonneir; M. Malacarne; V. Marchese; P. Massmann; P. McMullen; M. J. Mead; P. Meriguet; V. Merlo; S. Mills; P. Millward; A. Moissonnier; P. L. Mondini; P. Morgan; G. Murphy; M. F. Nave; L. Nickesson; P. Nielson; P. Noll; S. Nowak; W. Obert; B. Oliver; M. Olsson; J. O'Rourke; M. G. Pacco; J. Paillere; L. Pannacione; S. Papastergiou; D. Pasini; M. Pescatore; J. Planncoulaine; J. P. Poffe; R. Prentice; T. Raimondi; C. Raymond; P. H. Rebut; J. Removille; W. Riediker; R. Roberts; A. Rolfe; R. T. Ross; G. Sadler; J. Saffert; N. Salmon; A. Sand; A. Santagiustina; R. Saunders; M. Schmid; F. C. Schueller; K. Selin; R. Shaw; D. Sigournay; R. Simonini; P. Smeulders; L. Sonnerup; K. Sonnenberg; M. Stamp; C. A. Steed; D. Stork; P. E. Stott; T. E. Stringer; D. Summers; A. Tanga; A. Taroni; A. Terrington; A. Tesini; P. R. Thomas; E. Thompson; F. Tibone; R. Tivery; E. Usselmann; H. Van der Beken; M. Von Hellerman; J. E. Van Montfoort; T. Wade; C. Walker; B. A. Wallander; M. Walravens; K. Walter; M. L. Watkins; M. Watson; D. Webberley; J. Wesson; J. Wilks; T. Winkel; C. Woodward; M. Wykes; D. Young; L. Zennelili; J. Zwart; B. Beaumont; D. Gambier; D. Moreau; J. Ehrenberg; H. Jaeckel; S. Kissel; U. Kuephnapfel; R. Mueller; A. Staebler; A. Weller; J. H. Hamnen; M. Evrared; M. Gadeberg; K. Thomsen; P. Dupperrex; G. Tonetti; N. Lopez-Cardozo; B. Tubbing; J. Von Seggern; J. Tagle; F. Bombarda; G. Bracco; R. Giannella; R. Carolan; M. Cox; M. Forrest; D. Goodall; N. Hawkes; P. Haynes; J. Hugill; K. D. Lawson; G. McCracken; J. Partridge; N. Peacock; J. Snipes; T. Todd; H. Schamel; H. Summers; S. Tsuji; G. Tallents

1986-01-01

277

Filamentary magnetohydrodynamic plasmas  

SciTech Connect

A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected. the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories. but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.

Kinney, R.; Tajima, T.; Petviashvili, N. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; McWilliams, J.C. [National Center for Atmospheric Research, Boulder, CO (United States)

1993-05-01

278

Quark gluon plasma  

Microsoft Academic Search

Recent trends in the research of quark gluon plasma (QGP) are surveyed and the current experimental and theoretical status\\u000a regarding the properties and signals of QGP is reported. We hope that the experiments commencing at relativistic heavy-ion\\u000a collider (RHIC) in 2000 will provide a glimpse of the QGP formation.

C P Singh

2000-01-01

279

Plasma atomic layer etching  

Microsoft Academic Search

Summary form only given. The thinning of the dielectric in the metal (and non-metal) gate stacks and the need to resolve etching on an atomic layer basis present large technological challenges. Conventional plasma processes which utilize reactive ion etching typically do not have sufficient controllability to achieve atomic layer resolution and to avoid damage. To ensure atomic-level control it is

A. Agarwal; M. J. Kushner

2006-01-01

280

Electromagnetic Simulations of Dusty Plasmas  

Microsoft Academic Search

\\u000a Dusty plasmas are ionized gases containing small particles of solid matter, occurring e.g. in space, fusion devices or plasma\\u000a processing discharges. While understanding the behavior of these plasmas is important for a variety of applications, an analytic\\u000a treatment is difficult and numerical methods are required. Ideally, the dusty plasma would be treated kinetically, modeling\\u000a each particle individually. However, this is

Peter Messmer

2004-01-01

281

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

282

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

283

Plasma cell leukemia with myelofibrosis  

Microsoft Academic Search

Summary We describe a case of plasma cell leukemia associated with myelofibrosis. A 60-year-old woman was admitted due to lumbago and monoclonal hypergammaglobulinemia. Peripheral blood showed about 40% of plasma-cell-like cells. A bone marrow aspiration was dry tap. The patient was diagnosed as having plasma cell leukemia with myelofibrosis by bone marrow biopsy. Plasma cell leukemia as well as myelofibrosis

T. Murayama; T. Matsui; Y. Hayashi; T. Taniguchi; M. Ito; T. Natazuka; S. Imoto; N. Iwata; T. Isobe; H. Ito; K. Chihara

1994-01-01

284

Shock physics of nonideal plasmas  

Microsoft Academic Search

This study is an experimental investigation of nonideal plasmas produced by strong shock waves. The study centered about the understanding of factors controlling the specific energy and transport properties of dense plasma in an explosively energized plasma source. The study addressed specifically the gas cavity geometry, pressure-density effects, radial velocity effects, and size scaling. Both argon and xenon were used

D. W. Baum; W. L. Shimmin; R. F. Flagg; S. P. Gill; D. Mukherjee

1979-01-01

285

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

286

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

287

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

288

Enhanced incoherent scatter plasma lines  

Microsoft Academic Search

Detailed model calculations of auroral secondary and photoelectron distributions for varying conditions have been used to calculate the theoretical enhancement of incoherent scatter plasma lines. These calculations are compared with EISCAT UHF radar measurements of enhanced plasma lines from both the E and F regions, and published EISCAT VHP radar measurements. The agreement between the calculated and observed plasma line

H. Nilsson; S. Kirkwood; J. Lilensten; M. Galand

1997-01-01

289

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

290

Tomographic diagnostics of nonthermal plasmas  

NASA Astrophysics Data System (ADS)

In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

Denisova, Natalia

2009-10-01

291

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

292

Electromagnetic vortices in a plasma  

Microsoft Academic Search

It is shown that electromagnetic solitary vortices (with a nonpotential electric field) can exist in a plasma. Vortices of two types are discussed: Alfven and ballooning. An Alfven vortex can exist in a homogeneous plasma immersed in a homogeneous magnetic field. A ballooning vortex is predicted for a plasma with homogeneous density immersed in crossed magnetic and gravitational fields.

G. D. Aburdzhaniia; A. B. Mikhailovskii; O. G. Onishchenko; S. E. Sharapov; A. P. Churikov

1984-01-01

293

Gas injected washer plasma gun  

Microsoft Academic Search

A plasma gun similar in geometry to the washer plasma gun has been operated with gas injected externally. Hydrogen, nitrogen and argon plasmas have been ionised and accelerated to velocities of the order of 107 mm s-1 and densities 1011 mm-3. Higher parameter range is possible with higher electrical input power.

K. K. Jain; P. I. John; A. M. Punithavelu; P. P. Rao

1980-01-01

294

On Plasma Synthetic Jet Actuators  

Microsoft Academic Search

The term plasma actuator refers to an asymmetric arrangement of two electrodes (typ- ically rectangular strips) separated by dielectric material that can be used as active flow control devices. A plasma actuator design consisting of an annular electrode array, the plasma synthetic jet actuator (PSJA), is experimentally investigated in this paper. This particular geometry creates a zero-net mass flux (or

Arvind Santhanakrishnan; Jamey D. Jacob

2006-01-01

295

Plasma non-cholesterol sterols  

Microsoft Academic Search

Increased levels of plasma sterols other than cholesterol can serve as markers for abnormalities in lipid metabolism associated with clinical disease. Premature atherosclerosis and xanthomatosis occur in two rare lipid storage diseases, Cerebrotendinous xanthomatosis (CTX) and sitosterolemia. In CTX, cholestanol is present in all tissues. In sitosterolemia, dietary campesterol and sitosterol accumulate in plasma and red blood cells. Plasma accumulation

A Kuksis

2001-01-01

296

Plasma transport from multicomponent approach  

Microsoft Academic Search

Plasma measurements in the Earth's magnetotail have revealed occasional existence of multiple plasma components. In this work, we present the first quantitative comparison between single-component and multicomponent approaches on the transport of mass and energy in the magnetotail with Geotail 3D plasma measurements. Two events are examined in detail, one during substorm expansion and the other during substorm recovery. It

A. T. Y. Lui; T. Hori; G. Ueno; T. Mukai

2005-01-01

297

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

298

Progress on Laser Plasma Accelerators.  

National Technical Information Service (NTIS)

Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experime...

P. Chen

1986-01-01

299

Plasma spray consolidation of materials  

Microsoft Academic Search

Plasma spray deposition, long considered a coating process for applying thin protective layers has experienced recent major advances. Technology, such as the introduction the process into vacuum, the development of higher enthalpy plasma torches and the fabrication of composite materials deposition, as well as others has enabled a wide range of structural applications for the plasma spray deposition process. Spray

R. W. Smith; D. Apelian

1990-01-01

300

Micromachined probes for laboratory plasmas  

Microsoft Academic Search

As we begin to find more applications for plasmas in our everyday lives, the ability to characterize and understand their inner workings becomes increasingly important. Much of our current understanding of plasma physics comes from investigations conducted in diffuse, outer space plasmas where experimenters have no control over the environment or experimental conditions and one measures interesting phenomena only by

Franklin Changta Chiang

2009-01-01

301

Dynamics of H+ + H ionization in plasmas  

NASA Astrophysics Data System (ADS)

Collision dynamics of H+ + H ionization in plasma-free cases and plasmas is studied by the classical trajectory Monte Carlo (CTMC) method. The plasma screening effects of dense quantum plasmas have been compared with these of weakly coupled plasmas. It is shown the plasma screening effects increase the ionization cross sections. Cross sections in dense quantum plasmas are bigger than these in weakly coupled plasmas.

Zhang, L. Y.; Qi, X.; Zhao, X. Y.; Yang, L.

2014-04-01

302

Dense Plasma Injectors for the HyperV Plasma Jets  

NASA Astrophysics Data System (ADS)

HyperV is developing high velocity dense plasma jets for application to fusion and HEDP. The approach uses symmetric pulsed injection of high density plasma into a coaxial EM accelerator having a cross-section tailored to prevent formation of the blow-by instability. Work to date has focused on injection using ablative plasma sources, such as capillaries and sparkgaps, but injection of pure plasma, such as D and T, or high-Z gases such as Argon, require a different approach. We describe experiments and diagnostic measurements to develop small parallel plate railguns (MiniRailguns) to generate high density plasma pulses for injection into the coax gun. We also present a brief update of latest results from the 112 electrode sparkgap gun and the 64 capillary TwoPi plasma jet merging experiment, both of which have been upgraded with higher energy pulse forming networks to double the mass of ablatively injected plasma.

Witherspoon, F. Douglas; Bomgardner, Richard; Case, Andrew; Messer, Sarah; Brockington, Samuel

2008-04-01

303

Tomographic Investigation of Plasma Jets Produced by Multielectrode Plasma Torches  

NASA Astrophysics Data System (ADS)

Recent advances in the development of new plasma torches rely on the use of multiple electrodes to improve plasma jet stability. Examples are the Triplex, employing three cathodes and a single anode, and the Delta, which uses three anodes with a single common cathode. To characterize the plasma jet produced by these plasma torches, initial experiments have been performed using tomography in the visible range. Due to the improved stability of the plasma jet in the multielectrode configuration it is possible to carry out tomography by means of a regular charge-coupled device (CCD) camera, which is rotated around the plasma jet axis. The two-dimensional information obtained by the CCD camera is subsequently processed to produce an image of the three-dimensional emission distribution. The tomographic analysis is mated with a simple but effective simulation tool, which can be used as a basis for parameter-dependent multielectrode plasma torch design.

Schein, J.; Richter, M.; Landes, K. D.; Forster, G.; Zierhut, J.; Dzulko, M.

2008-09-01

304

Modelling of Complex Plasmas  

NASA Astrophysics Data System (ADS)

Nowadays plasmas are used for various applications such as the fabrication of silicon solar cells, integrated circuits, coatings and dental cleaning. In the case of a processing plasma, e.g. for the fabrication of amorphous silicon solar cells, a mixture of silane and hydrogen gas is injected in a reactor. These gases are decomposed by making a plasma. A plasma with a low degree of ionization (typically 10_5) is usually made in a reactor containing two electrodes driven by a radio-frequency (RF) power source in the megahertz range. Under the right circumstances the radicals, neutrals and ions can react further to produce nanometer sized dust particles. The particles can stick to the surface and thereby contribute to a higher deposition rate. Another possibility is that the nanometer sized particles coagulate and form larger micron sized particles. These particles obtain a high negative charge, due to their large radius and are usually trapped in a radiofrequency plasma. The electric field present in the discharge sheaths causes the entrapment. Such plasmas are called dusty or complex plasmas. In this thesis numerical models are presented which describe dusty plasmas in reactive and nonreactive plasmas. We started first with the development of a simple one-dimensional silane fluid model where a dusty radio-frequency silane/hydrogen discharge is simulated. In the model, discharge quantities like the fluxes, densities and electric field are calculated self-consistently. A radius and an initial density profile for the spherical dust particles are given and the charge and the density of the dust are calculated with an iterative method. During the transport of the dust, its charge is kept constant in time. The dust influences the electric field distribution through its charge and the density of the plasma through recombination of positive ions and electrons at its surface. In the model this process gives an extra production of silane radicals, since the growth of dust is not included. Results are presented for situations in which the dust signi_cantly changes the discharge characteristics, both by a strong reduction of the electron density and by altering the electric field by its charge. Simulations for dust with a radius of 2 mu-m show that the stationary solution of the dust density and the average electric field depend on the total amount of the dust. The presence of dust enhances the deposition rate of amorphous silicon 2 at the electrodes because of the rise in the average electron energy associated with the decrease of the electron density and the constraint of a constant power input. This increase of deposition rate has also been observed in experiments by others. To study the behavior of dust in a less complicated environment, experiments in non-reactive plasmas have been carried out by a number of research groups. In these experiments the dust particles are injected through the electrodes in an argon discharge. These experiments have shown very interesting phenomena. Dust particles start to interact with each other in the discharge and form two-dimensional Coulomb clusters. These experiments often show an appearance of a void, a dustfree region in the discharge. Similar experiments have also been carried out under microgravity. These experiments have shown three-dimensional Coulomb clusters of dust particles also with the appearance of a void. Also rotating dust clouds (vortices) near the edges of the electrodes have been observed, that tend to rotate as long as the plasmas is on. To understand the behavior of the particles, we have developed a two-dimensional fluid model for a dusty argon plasma in which the plasma and dust parameters are solved self-consistently to study the behavior of dust particles. Simulations for dust with a radius of 7.5 mu-m show that a double space charge layer is created around the sharp boundary of the dust crystal. The inter-particle interaction is taken into account by means of an equation of state for the dust. A central dust-free region (void) is created by the ion drag force. The con

Akdim, Mohamed Reda

2003-09-01

305

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

306

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

307

Plasma processing and synthesis of materials  

SciTech Connect

These proceedings compile papers about plasma. Topics include: Plasma arc spraying, vacuum melting, plasma melters for nuclear waste vitrification, thermal degradation of metal oxides in plasma, electrohydrodynamics, laser-induced fluorescence, measurements of temperature in plasma, and modeling and diagnostics in plasma processing.

Apelian, D.; Szekely, J.

1987-01-01

308

Experimental Studies of Coaxial Plasma Gun Current  

Microsoft Academic Search

In this investigation of a coaxial plasma gun, plasma sheath currents and related behavior are examined. Plasma behavior in the gun affects gun characteristics. Plasma gun applications are determined by the plasma behavior. The AFWL PUFF capacitor bank (72 mu F, 29 nH, 120 kV) drives the plasma gun using a deuterium fill gas. The gas breakdown site is isolated

David Wayne Price

1988-01-01

309

Plasma-surface interactions  

NASA Astrophysics Data System (ADS)

Materials processing is at a crossroads. Currently much of industrially viable materials processing is via plasmas. However as this processing has reached the nano-scale, development of industrially viable processes has become more and more difficult. In part this is because of all of the free parameters that exist in plasmas. To overcome this economic issue, tool vendors and semiconductor companies have turned to complex computational models of processing plasmas. For those models to work, one requires a through understanding of all of the gas-phase and surface-phase processes that are exhibited in plasmas. Unfortunately, these processes are not well understood. Fortunately, one can examine the influence the plasma properties on the desired surface processes and through this ultimately optimize manufacturing. It is well known that the surface processes (etch or deposition), occur in the top few mono-layers of the surface. For example, growth of a film will require that molecules from the gas-phase land and bond on the surface. In order to understand the mechanism of deposition and etch on a surface, we begin with a basic reaction rate density R_particle = int_0^infty sigma(epsilon,T)n_bonds v_particle n_particle f_particle (epsilon)d epsilon (1) Here sigma (theta,epsilon,T) is defined as the cross section of a particle either filling or creating an available bond site on the a surface of temperature T, n_bonds is the density of surface bonds, v_particle is the gas particle velocity, n_particle is the gas particle density and f_particle (epsilon) is the gas energy distribution function. Assuming that the fraction of bond sites that are open is Theta, then at any given time the open bond density will be Theta n_bonds and the closed bond density is (1 - Theta) n_bonds. Under the assumption that most of these processes occur at open bond sites, our group has arrived at a general formula for the process rate (here applied to C_x F_y etch of SiO_2) of: Equation (2) Here, S.C or Y approx is the deposition sticking coefficient or etch yield, K_X is a species dependent proportionality constant, is the particle flux, and rho_X is the surface material density. In this paper we will examine the implications of Equation 2. Specifically we will examine how the surface interactions set how process tools work. From this we will examine the potential future of the plasma-processing field.

Goeckner, M. J.; Nelson, C. T.; Sant, S. P.; Jindal, A. K.; Joseph, E. A.; Zhou, B. S.; Pardon-Wells, G.; Jarvis, B.; Pierce, R.; Overzet, L. J.

2008-07-01

310

Atmospheric-pressure plasma technology  

NASA Astrophysics Data System (ADS)

Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

Kogelschatz, U.

2004-12-01

311

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

312

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

313

Plasma beat-wave accelerator  

SciTech Connect

We perform an analytic study of some quantities relevant to the plasma beat-wave accelerator (PBWA) concept. We obtain analytic expressions for the plasma frequency, longitudinal electron velocity, plasma density and longitudinal plasma electric field of a nonlinear longitudinal electron plasma oscillation with amplitude less than the wave-breaking limit and phase velocity approaching the speed of light. We also estimate the luminosity of a single-pass e/sup +/e/sup -/ linear PBWA collider assuming the energy and collision beamstrahlung are fixed parameters.

Noble, R.J.

1983-06-01

314

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

315

Closed inductively coupled plasma cell  

DOEpatents

A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies is disclosed. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy. 1 fig.

Manning, T.J.; Palmer, B.A.; Hof, D.E.

1990-11-06

316

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

317

Plasma turbulence calculations on supercomputers  

SciTech Connect

To predict the size, expense, and performance of magnetic fusion reactors, it is critical to know the scaling of particle transport and losses across the magnetic field with machine and plasma parameters. The mechanism for transport in magnetically confined plasmas is not yet known. However, at the plasma edge, losses larger than those predicted by classical theory have been shown to be induced by fluctuations. Numerical calculations of plasma turbulence are expected to lead to the identification of the transport scaling parameters. This paper discusses how the fluid approach to plasma dynamics makes tractable some plasma turbulence problems for which kinetic theory calculations are, at present, too complex. Only with present supercomputers can this problem be treated for the edge plasma.

Carreras, B.A.; Dominquez, N.; Drake, J.B.; Leboeuf, J.N. (Oak Ridge National Lab., Oak Ridge, TN (US)); Charlton, L.A.; Holmes, J.A.; Lee, D.K.; Lynch, V.E. (Computing and Telecommunications Div., Martin Marietta Energy Systems, Inc., Oak Ridge, TN (US)); Garcia, L. (Univ. Complutense and Association CIEMAT-EURATOM, Madrid (ES))

1990-01-01

318

Plasma Generated Spherules  

NASA Astrophysics Data System (ADS)

Z-pinch plasma simulations have been performed that indicate the production of spherules under certain experimental parameters. (A. L. Peratt, private communication) While performing experiments dealing with the impact of plasma discharges on various materials, we observed that spherules were created at the surface of some of the materials. For specific materials and conditions, spherules were always produced. Both individual spherules and joined spherules were created. The size and shapes were nearly identical to items found by the Mars rover, Opportunity, and called ``blueberries.'' Sky & Telescope, June 2004, p. 20, among other sources indicated the blueberries were gray spherules composed of hematite. The experiments produced hematite spherules identical in appearance to those found on Mars. These experiments suggest how the newly discovered blueberries were formed on Mars while providing an explanation that does not depend on the presence of water.

Ransom, C. J.

2005-04-01

319

Plasma jet takes off.  

PubMed

Thanks to a series of joint research projects by Los Alamos National Laboratory, Beta Squared of Allen, Texas, and the University of California at Los Angeles, there is now a more environmentally sound method for cleaning semiconductor chips that may also be effective in cleaning up chemical, bacterial, and nuclear contaminants. The Atmospheric Pressure Plasma Jet uses a type of ionized gas called plasma to clean up contaminants by binding to them and lifting them away. In contrast to the corrosive acids and chemical solvents traditionally used to clean semiconductor chips, the jet oxidizes contaminants, producing only benign gaseous by-products such as oxygen and carbon dioxide. The new technology is also easy to transport, cleans thoroughly and quickly, and presents no hazards to its operators. PMID:10417375

Frazer, L

1999-08-01

320

Plasma dust crystallization  

NASA Technical Reports Server (NTRS)

In a ground-based definition study, a concept for a new type of microgravity experiment is developed. We formed a new state of matter: a crystalline lattice structure of charged micron-size spheres, suspended in a charge-neutral plasma. The plasma is formed by a low-pressure radio-frequency argon discharge. Solid microspheres are introduced, and they gain a negative electric charge. They are cooled by molecular drag on the ambient neutral gas. They are detected by laser light scattering and video photography. Laboratory experiments have demonstrated that a two-dimensional nonquantum lattice forms through the Coulomb interaction of these spheres. Microgravity is thought to be required to observe a three-dimensional structure.

Goree, John; Thomas, H.; Morfill, G.

1994-01-01

321

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

322

Plasma boundaries around Venus  

NASA Astrophysics Data System (ADS)

We use data of the ASPERA-4 ion and electron spectrometers onboard Venus Express to define the location and shape of bow shock and magnetic barrier at Venus and their dependence on solar wind pressure and radiation. We compare our results with those of the Pioneer Venus Orbiter and discuss implications for atmospheric escape. We also discuss the differences to similar observations made by the ASPERA-3 instrument for the Martian plasma evironment.

Martinecz, C.; Fraenz, M.; Woch, J.; Krupp, N.; Dubinin, E.; Roussos, E.; Barabash, S.; Lundin, R.

323

Solid Fuel Plasma Gasification  

Microsoft Academic Search

This paper presents a numerical analysis and experimental investtigation of the gasification under steam and air plasma conditions\\u000a of two very different solid fuels, a low-rank bituminous coal of 40% ash content and a petrocoke of 3% ash content; with an\\u000a aim of producing synthesis gas. The numerical analysis was fulfilled using the software package TERRA for equilibrium computation.\\u000a Using

V. E. Messerle; A. B. Ustimenko

324

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

325

Unconventional plasma focus devices  

Microsoft Academic Search

The Plasma Focus (PF) characteristics have been investigated in the Two-Guns configuration (TWIN) with a 10-kJ class device. Electrodes with two different heads shapes, hollow (GYN) or hemispherical (PHAL), have been tested and the results show that the neutron yield is greater in the GYN configuration. In simple Two-Guns configuration, with the two anodes facing frontally in the vacuum vessel,

Maurizio Samuelli; Luigi Rapezzi; Maurizio Angelone; Mario Pillon; Massimo Rapisarda; Silvia Vitulli

2006-01-01

326

Electrons, Ions and Plasmas  

NSDL National Science Digital Library

This series of web pages provides information on a range of topics regarding charged particles. Starting with the properties of atomic electrons, this material describes the Edison and photoelectric effects, the interaction between charged particles and magnetic fields, and the creation of plasmas and positive ions. Other topics, including the history of research on charges, are covered in linked pages. This is part of a series of non-mathematical, linked explorations of the Earth's Magnetosphere.

Mendez, J.; Peredo, Mauricio; Stern, David P. (David Peter), 1931-

2009-04-15

327

Plasma source of ions  

SciTech Connect

The plasma source is generated by a Penning discharge in a system with a hollow cathode and provides an ion current of up to 20 mA at an extracting voltage of 20 kV. A discharge current of 200 mA is produced. The ion source, as described by the author, is provided with a replaceable hollow cathode and an exchangeable torus-shaped insert in the emitter cathode.

Semenov, A.P.

1985-03-01

328

Primary plasma cell leukemia  

Microsoft Academic Search

Four cases of primary plasma cell leukemia (PPCL) admitted to Zhongshan Hospital from 1959 to 1987 are reported with a review\\u000a on additional 40 cases reported in China. Comparing with the 57 cases of multiple myeloma (MM) treated in our hospital, the\\u000a following features were observed in PPCL: (1) The age was younger, with a mean of 45.2 years, 34.1%

Cai Zeji; Zhang Guozhen

1991-01-01

329

Plasma cell leukemia  

Microsoft Academic Search

Opinion statement  Plasma cell leukemia (PCL) is a rare aggressive variant of multiple myeloma (MM) characterized by a fulminant course and poor\\u000a prognosis. The median survival is measured in months. Therapy and prognosis partially depend on whether the disease presents\\u000a de novo or as a secondary process involving the leukemic transformation of a previously diagnosed MM. Secondary PCL represents\\u000a a terminal

Suzanne R. Hayman; Rafael Fonseca

2001-01-01

330

Beam-Plasma Interactions  

SciTech Connect

We describe the theory of a cyclotron maser instability which appears to be a likely source of auroral kilometric radiation and its generation in a laboratory experiment. We then outline plans for future development of the experiment to investigate a wider range of instabilities resulting from the existence of electron beams in a plasma. The basic theory theory underlying a few of these is then discussed.

Cairns, R. A.; Vorgul, I. [School of Mathematics and Statistics, University of St Andrews, St Andrews, Fife, KY16 9SS UK (United Kingdom); Bingham, R. [SUPA Department of Physics, University of Strathclyde, Glasgow, G4 0NG (United Kingdom); Rutherford Appleton Laboratory, Chilton, Didcot, Oxon. OX11 0QX (United Kingdom); Ronald, K.; Speirs, D. C.; Phelps, A. D. R.; McConville, S. L.; Gillespie, K. M.; Cross, A. W.; Robertson, C. W.; Whyte, C. G. [SUPA Department of Physics, University of Strathclyde, Glasgow, G4 0NG (United Kingdom); Kellett, B. J. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon. OX11 0QX (United Kingdom)

2009-11-10

331

Plasma pinchlamp surface preparation  

Microsoft Academic Search

A high-pressure laser-guided gas-embedded plasma pinchlamp is described for the generation of intense UV radiation. It has been configured to optimize energy transfer from the storage PFN. The output energy peaks within the spectral range 150 - 250 nm with a pulsed power of 20 MW at 10 Hz. The device employs a working gas of argon at 3 AMAGAT

John F. Asmus

1997-01-01

332

Electrons, Ions and Plasma  

NSDL National Science Digital Library

This explanation of the factors that produce the polar aurora, (northern lights) discusses the role of electrons in the ionosphere, positive ions in the solar wind, and the mixing of the two to create plasma. The work of Kristian Birkeland of Norway in exploring the cause of the aurora is cited and a link leads to in-depth information on auroras, including some dramatic photographs.

Stern, David

333

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

334

Plasma Properties of Microwave Produced Plasma in a Toroidal Device  

NASA Astrophysics Data System (ADS)

We have modified a small tokamak, STOR-1M, on loan from University of Saskatchewan, to operate as a low-temperature (˜5 eV) toroidal plasma machine with externally induced toroidal magnetic fields ranging from zero to ˜50 G. The plasma is produced using microwave discharges at relatively high pressures. Microwaves are produced by a kitchen microwave-oven magnetron operating at 2.45 GHz in continuous operating mode, resulting in pulses ˜0.5 s in duration. Initial measurements of plasma formation in this device with and without applied magnetic fields are presented. Plasma density and temperature profiles have been measured using Langmuir probes and the magnetic field profile inside the plasma has been obtained using Hall probes. When the discharge is created with no applied toroidal magnetic field, the plasma does not fill the entire torus due to high background pressure. However, when a toroidal magnetic field is applied, the plasma flows along the applied field, filling the torus. Increasing the applied magnetic field seems to aid plasma formation - the peak density increases and the density gradient becomes steeper. Above a threshold magnetic field, the plasma develops low-frequency density oscillations due to probable excitation of flute modes in the plasma.

Singh, Ajay; Edwards, W. F.; Held, Eric

2011-11-01

335

Precise plasma process control based on combinatorial plasma etching  

NASA Astrophysics Data System (ADS)

For the realization of super-fine plasma etching process, fluctuations of plasma parameters such as densities of radicals, ions and electrons is required to be minimized. In particular, conditions of inner surface of reactor wall can significantly influence on the radical density in subsequent plasma process owing to outgas consisting of deposited reaction products and adsorbed species from the previous process on the wall. To investigate variety of gaseous radical densities for H2/N2 plasma when inner wall condition was changed by the previous process, we analyzed the radical densities using vacuum ultraviolet absorption spectroscopy (VUVAS). It was clearly confirmed that the radical densities in 100-MHz capacitively coupled plasma (CCP) of H2/N2 were temporally changed subsequently after different kind of conditions for H2/N2 plasma, O2 plasma, and air exposure. We clarified how and what kind of etched products or process gases adsorbed on inner wall surface during the previous process and what species desorbed from the wall into bulk plasmas. Then we are trying to establish a precise process control systematically based on the plasma nano-science database that is constructing using the combinatorial plasma etching approach [1]. [4pt] [1] C. Moon, et al., Applied Physics Express 2 (2009) 096001.

Sekine, Makoto; Suzuki, Toshiya; Takeda, Keigo; Kondo, Hiroki; Ishikawa, Kenji; Setsuhara, Yuichi; Shiratani, Masaharu; Hori, Masaru

2012-10-01

336

The Coalition for Plasma Science: Bringing Plasmas to the Public  

NASA Astrophysics Data System (ADS)

The Coalition for Plasma Science is a group of institutions, organizations, and companies that have joined forces to increase awareness and understanding of plasma science and its many applications and benefits for society. The CPS undertakes a range of activities to support this goal. Members include national laboratories, universities, industries, and individuals. The CPS maintains a web page (http://www.plasmacoalition.org), and has developed several types of plasma-related publications. The web page includes a compilation of evaluated plasma web sites. The evaluations were conducted by teachers and based on national teaching standards. The web site also contains copies of CPS publications including the brochure ''Plasmas are Everywhere.'' Thousands of these brochures are distributed each year, and a poster version is now available. Another publication is the ''About Plasmas'' series. Each of these two-page papers (which is written for a general audience) is about a specific plasma-related topic, such as lighting, fusion, space plasmas and plasma decontamination of biological hazards. Papers on other topics are under development. The CPS also organizes educational luncheon/seminars for Members of Congress and their staff. The most recent seminar was given by David Newman on January 28th of this year and was his ''state of the universe'' address. A second seminar is planned this year on the topic of semiconductor manufacturing. Activities under discussion include a topical science fair award for a project on plasmas and the development of a broad, history-based educational web site.

Berry, Lee

2003-10-01

337

Electrosurgical Plasma Discharges  

NASA Astrophysics Data System (ADS)

Electrosurgical instruments employing plasmas to volumetrically ablate tissue are now enjoying widespread use in medical applications. We have studied several commercially available instruments in which luminous plasma discharges are formed near electrodes immersed in saline solutions when sufficiently large amplitude bipolar voltage waveforms are applied. Different aqueous salt solutions have been investigated, including isotonic NaCl solution as well as solutions of KCl, and BaCl_2. With strong driving voltage applied, a vapor layer is formed as well as visible and UV optical emissions. Spectroscopic measurements reveal the predominant emissions are from the low ionization potential salt species, but significant emissions from electron impact dissociated water fragments such as OH and H-atoms also are observed. The emissions also coincide with negative bias on the active electrode. These optical emissions are consistent with an electron density of about 10^12cm-3 and an electron temperature of about 4 eV. Experimental results and model calculations of the vapor layer formation process and plasma formation in the high-field region will be discussed.

Stalder, K. R.; Woloszko, J.

2002-10-01

338

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.

de Larrea, Carlos Fernandez; Kyle, Robert A.; Durie, Brian GM; Ludwig, Heinz; Usmani, Saad; Vesole, David H.; Hajek, Roman; Miguel, Jesus 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; Blade, Joan; Orlowski, Robert Z.; Shah, Jatin J.

2014-01-01

339

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

340

Global Core Plasma Model  

NASA Technical Reports Server (NTRS)

Over 40 years of ground and spacecraft plasmaspheric measurements have resulted in many statistical descriptions of plasmaspheric properties. In some cases, these properties have been represented as analytical descriptions that are valid for specific regions or conditions. For the most part, what has not been done is to extend regional empirical descriptions or models to the plasmasphere as a whole. In contrast, many related investigations depend on the use of representative plasmaspheric conditions throughout the inner magnetosphere. Wave propagation, involving the transport of energy through the magnetosphere, is strongly affected by thermal plasma density and its composition. Ring current collisional and wave particle losses also strongly depend on these quantities. Plasmaspheric also plays a secondary role in influencing radio signals from the Global Positioning System satellites. The Global Core Plasma Model (GCPM) is an attempt to assimilate previous empirical evidence and regional models for plasmaspheric density into a continuous, smooth model of thermal plasma density in the inner magnetosphere. In that spirit, the International Reference Ionosphere is currently used to complete the low altitude description of density and composition in the model. The models and measurements on which the GCPM is currently based and its relationship to IRI will be discussed.

Gallagher, Dennis L.; Craven, Paul D.; Comfort, Richard H.

1999-01-01

341

Plasma source nitriding  

NASA Astrophysics Data System (ADS)

A new method of surface nitriding, called "plasma source nitriding", has been developed. This method is different from "ion nitriding" in the following respects: (1) the function of nitrogen- and hydrogen-ion bombardment of a workpiece is independent of the function of plasma production, (2) a homogeneity of nitriding depth is obtainable even if the geometrical shape of the workpiece is complicated, (3) the cost of nitriding gases is reduced due to the lower operating gas pressure which is of the order of 10 -4 Torr in the vacuum vessel, and (4) there is no trouble of arcing between workpieces and plasma. On the basis of the experimental results, the activation energy for nitrogen diffusion in 316 stainless steel by this method was calculated to be about 3.9 kcal/mol. This value was remarkably small compared to the value of 17.3 kcal/mol in 304 stainless steel by ion nitriding. The nitriding time was about 3 h by the new method and 15 h by ion nitriding to get a hardened depth of 27 ?m in 316 stainless steel; the nitriding time was shortened to one-fifth.

Nunogaki, M.; Suezawa, H.; Hayasi, K.; Miyazaki, K.

1988-09-01

342

Plasma leptin, plasma zinc, and plasma copper are associated in elite female and male judo athletes.  

PubMed

The purpose of this study was to compare plasma leptin, plasma zinc, and plasma copper levels and their relationship in trained female and male judo athletes (n = 10 women; n = 8 men). Blood samples were obtained 24 h after training to measure plasma zinc, copper, and leptin levels. Subjects presented similar values to age (22 +/- 2 years old), body mass index (24 +/- 1 kg/m(2)), plasma zinc (17.2 +/- 2 micromol/L), copper (12.5 +/- 2 micromol/L), and leptin (5.6 +/- 1.3 microg/L). However, height, total body mass, lean mass, fat mass, and sum of ten-skinfold thickness were higher in male than female. Plasma leptin was associated with sum of ten skinfolds in male (r = 0.91; p < 0.001) and female athletes (r = 0.84; p < 0.003). Plasma zinc was associated with leptin in males (r = 0.82; p < 0.05) while copper was associated with plasma leptin in females (r = 0.66; p < 0.05). Our results suggest that young judo athletes lost sex-related differences in leptin levels. Plasma zinc, plasma copper, and energy homeostasis may be involved in regulation of plasma leptin. PMID:18953509

Casimiro-Lopes, Gustavo; de Oliveira-Junior, Astrogildo Vianna; Portella, Emilson Souza; Lisboa, Patrícia Cristina; Donangelo, Carmen Marino; de Moura, Egberto Gaspar; Koury, Josely Correa

2009-02-01

343

Visualization of Intermittent Blobby Plasma Transport in Attached and Detached Plasmas of the NAGDIS-II  

NASA Astrophysics Data System (ADS)

We investigated the intermittent convective plasma transport in a attached and?or detached plasma condition of the linear divertor plasma simulator, NAGDIS-II. Images taken by a fast-imaging camera clearly show that in attached plasmas, blobs are peeled off the bulk plasma, and propagate outward with an azimuthal motion. In detached plasmas, plasma turbulence observed near the plasma recombining region drives strong intermittent radial plasma transport, which could broaden the radial density profile.

Ohno, Noriyasu; Furuta, Katsuhiro; Takamura, Shuichi

344

Lithium plasma emitter for collisionless magnetized plasma experiment.  

PubMed

This paper presents a newly developed lithium plasma emitter, which can provide quiescent and low-temperature collisionless conditions for magnetized plasma experiments. This plasma emitter generates thermal emissions of lithium ions and electrons to produce a lithium plasma. Lithium type beta-eucryptite and lanthanum-hexaboride (LaB(6)) powders were mixed and directly heated with a tungsten heater to synthesize ion and electron emissions. As a result, a plasma with a diameter of ~15 cm was obtained in a magnetic mirror configuration. The typical range of electron density was 10(12)-10(13) m(-3) and that of electron temperature was 0.1-0.8 eV with the emitter operation temperature of about 1500 K. The amplitude fluctuations for the plasma density were lower than 1%. PMID:21974582

Kawamori, Eiichirou; Lee, Jyun-Yi; Huang, Yi-Jue; Syugu, Wun-Jheng; Song, Sung-Xuang; Hsieh, Tung-Yuan; Cheng, C Z

2011-09-01

345

Lithium plasma emitter for collisionless magnetized plasma experiment  

NASA Astrophysics Data System (ADS)

This paper presents a newly developed lithium plasma emitter, which can provide quiescent and low-temperature collisionless conditions for magnetized plasma experiments. This plasma emitter generates thermal emissions of lithium ions and electrons to produce a lithium plasma. Lithium type beta-eucryptite and lanthanum-hexaboride (LaB6) powders were mixed and directly heated with a tungsten heater to synthesize ion and electron emissions. As a result, a plasma with a diameter of ~15 cm was obtained in a magnetic mirror configuration. The typical range of electron density was 1012-1013 m-3 and that of electron temperature was 0.1-0.8 eV with the emitter operation temperature of about 1500 K. The amplitude fluctuations for the plasma density were lower than 1%.

Kawamori, Eiichirou; Lee, Jyun-Yi; Huang, Yi-Jue; Syugu, Wun-Jheng; Song, Sung-Xuang; Hsieh, Tung-Yuan; Cheng, C. Z.

2011-09-01

346

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

347

Fundamental and harmonic plasma emission in different plasma environments  

NASA Astrophysics Data System (ADS)

Aims: Emission of radio waves from plasmas through plasma emission with fundamental and harmonic frequencies is a familiar process known from solar type II radio bursts. Current models assume the existence of counterstreaming electron beam populations excited at shocks as sources for these emission features, which limits the plasma parameters to reasonable heliospheric shock conditions. However, situations in which counterstreaming electron beams are present can also occur with different plasma parameters, such as higher magnetisation, including but not limited to our Sun. Similar radio emissions might also occur from these situations. Methods: We used particle-in-cell simulations to compare plasma microphysics of radio emission processes from counterstreaming beams in different plasma environments that differed in density and magnetization. Results: Although large differences in wave populations are evident, the emission process of type II bursts appears to be qualitatively unaffected and shows the same behaviour in all environments.

Ganse, U.; Kilian, P.; Spanier, F.; Vainio, R.

2014-04-01

348

Complex plasma-the plasma state of soft matter  

NASA Astrophysics Data System (ADS)

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.

2010-11-01

349

Influence of Plasma Instabilities in Ceramic Suspension Plasma Spraying  

NASA Astrophysics Data System (ADS)

Direct current Suspension Plasma Spraying (SPS) allows depositing finely structured coatings. This article presents an analysis of the influence of plasma instabilities on the yttria-stabilized suspension drops fragmentation. A particular attention is paid to the treatment of suspension jet or drops according to the importance of voltage fluctuations (linked to those of the arc root) and depending on the different spray parameters such as the plasma forming gas mixture composition and mass flow rate and the suspension momentum. By observing the suspension drops injection with a fast shutter camera and a laser flash sheet triggered by a defined transient voltage level of the plasma torch, the influence of plasma fluctuations on jet or drops fragmentation is studied through the deviation and dispersion trajectories of droplets within the plasma jet.

Etchart-Salas, R.; Rat, V.; Coudert, J. F.; Fauchais, P.; Caron, N.; Wittman, K.; Alexandre, S.

2007-12-01

350

REVIEWS OF TOPICAL PROBLEMS: Amplification in recombining plasmas (plasma lasers)  

Microsoft Academic Search

A review is given of the investigations of lasers in which the amplifying medium is a rapidly recombining (supercooled in respect to free electrons) dense plasma. Efficient amplification of visible and ultraviolet radiation is possible in a plasma with a free-electron density Ne = 1013-1018 cm-3 and an electron temperature Te=0.05-2 eV. At short wavelengths and high energies, the plasma

L. I. Gudzenko; Leonid A. Shelepin; Sergei I. Yakovlenko

1975-01-01

351

Plasma dragged microparticles as a method to measure plasma flows  

SciTech Connect

The physics of microparticle motion in flowing plasmas is studied in detail for plasmas with electron and ion densities n{sub e,i}{approx}10{sup 19} m{sup -3}, electron and ion temperatures of no more than 15 eV, and plasma flows on the order of the ion thermal speed, v{sub f}{approx}v{sub ti}. The equations of motion due to Coulomb interactions and direct impact with ions and electrons, of charge variation, as well as of heat exchange with the plasma, are solved numerically for isolated particles (or dust grains) of micron sizes. It is predicted that microparticles can survive in plasma long enough, and can be dragged in the direction of the local ion flow. Based on the theoretical analysis, we describe a new plasma flow measurement technique called microparticle tracer velocimetry (mPTV), which tracks microparticle motion in a plasma with a high-speed camera. The mPTV can reveal the directions of the plasma flow vectors at multiple locations simultaneously and at submillimeter scales, which is hard to achieve by most other techniques. Thus, mPTV can be used to study plasma flows produced in the laboratory.

Ticos, Catalin M.; Wang Zhehui; Delzanno, Gian Luca; Lapenta, Giovanni [Plasma Physics Group P-24, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2006-10-15

352

A contoured gap coaxial plasma gun with injected plasma armature  

SciTech Connect

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 {mu}g of plasma with density above 10{sup 17} cm{sup -3} to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 {mu}g has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond [HyperV Technologies Corp., Chantilly, Virginia 20151 (United States)

2009-08-15

353

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

354

Measurement of plasma parameters in an inductively coupled plasma reactor  

NASA Astrophysics Data System (ADS)

The objective is to deepen the understanding of basic plasma properties in a high-density inductively coupled plasma (ICP) reactor. The experiment using a Langmuir probe, which is made of tungsten wire having length of 2.3 mm and diameter of 0.65 mm, is carried out to determine the characteristics of argon plasma. The axial and radial distributions of the plasma density, electron temperature, and plasma potential are measured. It was found that the electron density is in the range of 1.0×1010 to 1.0×1011 cm-3, electron temperature 4~6 eV, and plasma potential 35~45 V, respectively. These plasma parameters are spatially nonuniform in the axial direction; they depend on the distance between the plasma source and the measuring point. Next, etching of polycristalline silicon wafer by chlorine plasma is studied. The results obtained in this study indicate the effects of rf coil power, gas pressure, and substrate rf bias power on the distributions of the etch rate. .

Sasaki, Hiroshi; Nanbu, Kenichi; Takahashi, Masayoshi

2001-08-01

355

Surface plasma wave excitation via laser irradiated overdense plasma foil  

SciTech Connect

A laser irradiated overdense plasma foil is seen to be susceptible to parametric excitation of surface plasma wave (SPW) and ion acoustic wave (IAW) on the ion plasma period time scale. The SPW is localised near the front surface of the foil while IAW extends upto the rear. The evanescent laser field and the SPW exert a ponderomotive force on electrons driving the IAW. The density perturbation associated with the latter beats with the laser induced oscillatory electron velocity to drive the SPW. At relativistic laser intensity, the growth rate is of the order of ion plasma frequency.

Kumar, Pawan; Tripathi, V. K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

2012-04-09

356

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

357

Surface currents on ideal plasmas  

SciTech Connect

The surface (or 'skin') current that can flow at a perturbed interface between plasma and vacuum is considered in the approximation where a surface marks a sharp transition from plasma to vacuum. A short magnetohydrodynamic calculation gives an exact and general expression for the component perpendicular to the average of the magnetic field either side of the surface, finding it proportional to the edge plasma pressure. A consequence is that for all plasmas with zero surface current at equilibrium, the surface current associated with any linear instability will flow parallel to the magnetic field. The surface current is calculated for a simple but realistic model of a cylindrical plasma, and found to depend on the type of instability, and consequently on the particular plasma equilibrium. This is illustrated for two well known cases.

Webster, Anthony J. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)

2010-11-15

358

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

359

MPD thruster plasma instability studies  

NASA Technical Reports Server (NTRS)

Results of an ongoing experimental/theoretical effort to understand the influence of plasma waves and instabilities upon coaxial plasma thruster performance and longevity are discussed. An experiment which permits measurement of the plasma dispersion relation plus a suite of plasma parameters for each one millisecond quasi-steady discharge is described. This investigation is guided by a linearized Boltzmann-Poisson kinetic numerical model which can accommodate the effects of collisions, inhomogeneities and the magnetic field. Preliminary tests reveal the presence of the low-frequency branch of an ion cyclotron wave. Although the stability of these waves still has to be established through spatial growth rate measurements, it is well known that they are prone to 'current-driven' instabilities. 'Current-driven' instabilities in the collisional tensor conducting plasma of the MPD thruster are analytically discussed and their relevance to the MPD plasma is illustrated by estimating a critical total current at which their onset occurs.

Kelly, A. J.; Jahn, R. G.; Choueiri, E. Y.

1987-01-01

360

Characterizing plasma mirrors near breakdown  

SciTech Connect

Experiments dedicated to the characterization of plasma mirrors with a high energy, single shot short-pulse laser were performed at the 100 TW target area of the Z-Backlighter Facility at Sandia National Laboratories. A suite of beam diagnostics was used to characterize a high energy laser pulse with a large aperture through focus imaging setup. By varying the fluence on the plasma mirror around the plasma ignition threshold, critical performance parameters were determined and a more detailed understanding of the way in which a plasma mirror works could be deduced. It was found, that very subtle variations in the laser near field profile will have strong effects on the reflected pulse if the maximum fluence on the plasma mirror approaches the plasma ignition threshold.

Geissel, Matthias; Schollmeier, Marius S.; Kimmel, Mark W.; Rambo, Patrick K.; Schwarz, Jens; Atherton, Briggs W. [Sandia National Laboratories, Z-Backlighter Facility, Albuquerque, New Mexico 87185-1193 (United States); Brambrink, Erik [Ecole Polytechnique, Laboratoire d'Utilisation des Lasers Intenses, Palaiseau (France)

2011-05-15

361

Autoresonant Excitation of Antiproton Plasmas  

NASA Astrophysics Data System (ADS)

We will present results of the first longitudinal autoresonant excitation of a thermal antiproton plasma. We apply a swept-frequency drive field to an antiproton plasma in an anharmonic potential to resonantly control the longitudinal energy of the particles in the potential. We observe autoresonant excitation of the plasma as a macroparticle in the regime of cold, dense plasmas, while warmer, tenuous plasmas are not excited completely (as predicted by theory [1]). This technique has been used for initiating the formation of antihydrogen, as it provides a flexible method for injecting antiprotons into a positron plasma of fluctuating space-charge while minimizing the kinetic energy of the antiprotons possessed by the antiprotons just after injection. As efforts to trap and conduct spectroscopy on antihydrogen require the formation of cold antihydrogen, minimizing energy mismatches in formation is key to successful trapping. References [1] Barth, I., et al, Phys. Rev. Lett. 103, 155001 (2009)

Bertsche, William

2010-11-01

362

Plasma Sail Concept Fundamentals  

NASA Technical Reports Server (NTRS)

The mini-magnetospheric plasma propulsion (M2P2) device, originally proposed by Winglee et al., predicts that a 15-km standoff distance (or 20-km cross-sectional dimension) of the magnetic bubble will provide for sufficient momentum transfer from the solar wind to accelerate a spacecraft to unprecedented speeds of 50 C80 km/s after an acceleration period of 3 mo. Such velocities will enable travel out of the solar system in period of 7 yr almost an order of magnitude improvement over present chemical-based propulsion systems. However, for the parameters of the simulation of Winglee et al., a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the magnetohydrodynamic (MHD) fluid model, normally applied to planetary magnetospheres, that the characteristic scale size is much greater than the Larmor radius and ion skin depth of the solar wind. In the case of M2P2, the size of the magnetic bubble is actually less than or comparable to the scale of these characteristic parameters. Therefore, a kinetic approach, which addresses the small-scale physical mechanisms, must be used. A two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail has been adopted. The first component is a self-consistent MHD simulation of the small-scale expansion phase of the magnetic bubble. The fluid treatment is valid to roughly 5 km from the source and the steady-state MHD solution at the 5 km boundary was then used as initial conditions for the hybrid simulation. The hybrid simulations showed that the forces delivered to the innermost regions of the plasma sail are considerably ( 10 times) smaller than the MHD counterpart, are dominated by the magnetic field pressure gradient, and are directed primarily in the transverse direction.

Khazanov, G. V.; Delamere, P.; Kabin, K.; Linde, T. J.

2004-01-01

363

Dust growth in magnetised plasmas  

NASA Astrophysics Data System (ADS)

The evolution and character of plasma dust has wide-ranging implications for astrophysics, including plasma chemistry and the evolution of planetary atmospheres. Here we present calculations of dust growth by ion accretion, under the combined influence of an applied magnetic field and the evolving electrostatic field arising from the charged grain. Simulations of ion trajectories through a magnetised plasma sheath will demonstrate the inhomogeneity of mass loading on an isolated grain surface.

Alharbi, M.; Diver, D. A.

2013-09-01

364

The plasma environment of comets  

SciTech Connect

U.S. research activities in the area of cometary plasma physics during 1987-1990 are reviewed. Consideration is given to mass loading and its consequences in the upstream region, the cometary shock, the cometosheath, the diamagnetic cavity boundary and the inner shock, and the plasma tail. Special attention is given to models and observations that have modified the pre-encounter understanding of cometary plasma environments. 211 refs.

Gombosi, T.I. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

365

Parallel plasma fluid turbulence calculations  

Microsoft Academic Search

The study of plasma turbulence and transport is a complex problem of critical importance for fusion-relevant plasmas. To this day, the fluid treatment of plasma dynamics is the best approach to realistic physics at the high resolution required for certain experimentally relevant calculations. Core and edge turbulence in a magnetic fusion device have been modeled using state-of-the-art, nonlinear, three-dimensional, initial-value

J. N. Leboeuf; B. A. Carreras; L. A. Charlton; J. B. Drake; V. E. Lynch; D. E. Newman; K. L. Sidikman; D. A. Spong

1994-01-01

366

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

367

Magnetic insulation for plasma propulsion  

NASA Technical Reports Server (NTRS)

The design parameters of effective magnetic insulation for plasma engines are discussed. An experimental model used to demonstrate the process of plasma acceleration and magnetic insulation is considered which consists of a copper strap that is wound around a glass tube and connected to a capacitor. In order to adequately model the magnetic insulation mechanisms, a computer algorithm is developed. Plasma engines, with their efficient utilization of the propellant mass, are expected to provide the next-generation advanced propulsion systems.

Gonzalez, Dora E.

1990-01-01

368

Progress on laser plasma accelerators  

SciTech Connect

Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.

Chen, P.

1986-04-01

369

Modeling of Photoionized Plasmas  

NASA Technical Reports Server (NTRS)

In this paper I review the motivation and current status of modeling of plasmas exposed to strong radiation fields, as it applies to the study of cosmic X-ray sources. This includes some of the astrophysical issues which can be addressed, the ingredients for the models, the current computational tools, the limitations imposed by currently available atomic data, and the validity of some of the standard assumptions. I will also discuss ideas for the future: challenges associated with future missions, opportunities presented by improved computers, and goals for atomic data collection.

Kallman, Timothy R.

2010-01-01

370

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

371

Plasma actuated heat transfer  

NASA Astrophysics Data System (ADS)

We introduce plasmas for film cooling enhancement in gas turbines and other engineering applications. We identify mechanisms to actuate essentially stagnant fluid just downstream of the cooling hole by employing three-dimensional body force for different hole geometries. Such methods actively alter flow structures in the vicinity of an actuator using an electrodynamic mechanism that induces attachment of cold jet to the work surface. Numerical results are compared with published experimental data and other numerical predictions for the latest film cooling technology. An effectiveness improvement of above 100% over the standard baseline design is predicted.

Roy, Subrata; Wang, Chin-Cheng

2008-06-01

372

Pulsed Plasma Thruster Technology  

NASA Technical Reports Server (NTRS)

The continuing emphasis on reducing costs and downsizing spacecraft is forcing increased emphasis on reducing the subsystem mass and integration costs. For many commercial, scientific, and Department of Defense space missions, onboard propulsion is either the predominant spacecraft mass or it limits the spacecraft lifetime. Electromagnetic-pulsed-plasma thrusters (PPT's) offer the combined benefits of extremely low average electric power requirements (1 to 150 W), high specific impulse (approx. 1000 sec), and system simplicity derived from the use of an inert solid propellant. Potential applications range from orbit insertion and maintenance of small satellites to attitude control for large geostationary communications satellites.

1996-01-01

373

Compact Plasma Accelerator  

NASA Technical Reports Server (NTRS)

A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

Foster, John E.

2004-01-01

374

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

375

Complexity and Space Plasmas  

NASA Astrophysics Data System (ADS)

In this study the general theoretical framework of Complexity theory is presented, viewed through non-extensive statistical theory introduced by Constantino Tsallis in 1988. Nonlinear dynamics, fractional dynamics, thermodynamics and statistical physics constitute the basic elements of Complexity theory which can be applied to processes near, as well as, far from equilibrium. Moreover, the nonextensive statistics can be the fundamental linchpin of Complexity theory from microscopical to macroscopical level. Finally, a brief review of results concerning nonlinear analysis of space plasma time series corresponding to different complex systems is given.

Pavlos, G.; Iliopoulos, A.; Karakatsanis, L.; Xenakis, M.; Pavlos, E.

2013-09-01

376

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

377

Autoresonant Excitation of Antiproton Plasmas  

SciTech Connect

We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

2011-01-14

378

First Observation of Electrorheological Plasmas  

SciTech Connect

We report the experimental discovery of ''electrorheological (ER) complex plasmas,'' where the control of the interparticle interaction by an externally applied electric field is due to distortion of the Debye spheres that surround microparticles (dust) in a plasma. We show that interactions in ER plasmas under weak ac fields are mathematically equivalent to those in conventional ER fluids. Microgravity experiments, as well as molecular dynamics simulations, show a phase transition from an isotropic to an anisotropic (string) plasma state as the electric field is increased.

Ivlev, A. V.; Morfill, G. E.; Thomas, H. M.; Raeth, C.; Huber, P.; Kompaneets, R. [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching (Germany); Joyce, G. [University of Maryland, College Park, Maryland 20742 (United States); Fortov, V. E.; Lipaev, A. M.; Molotkov, V. I. [Institute for High Energy Densities, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Reiter, T. [European Astronaut Centre, 51147 Cologne (Germany); Turin, M.; Vinogradov, P. [RSC Energia, 141070 Korolev (Russian Federation)

2008-03-07

379

Important plasma problems in astrophysics  

SciTech Connect

In astrophysics, plasmas occur under very extreme conditions. For example there are ultra strong magnetic fields in neutron stars) relativistic plasmas around black holes and in jets, extremely energetic particles such as cosmic rays in the interstellar medium, extremely dense plasmas in accretion disks, and extremely large magnetic Reynold`s numbers in the interstellar medium. These extreme limits for astrophysical plasmas make plasma phenomena much simpler to analyze in astrophysics than in the laboratory. An understanding of such phenomena often results in an interesting way, by simply taking the extreme limiting case of a known plasma theory. I will describe one of the more exciting examples. I will attempt to convey the excitement I felt when I was first exposed to it. However, not all plasma astrophysical phenomena are so simple. There are certain important plasma phenomena in astrophysics, which have not been so easily resolved. In fact a resolution of them is blocking significant progress in astrophysical research. They have not yet yielded to attacks by theoretical astrophysicists nor to extensive numerical simulation. I will attempt to describe one of the more important of these plasma-astrophysical problems, and discuss why its resolution is so important to astrophysics. This significant example is fast, magnetic reconnection. Another significant example is the large-magnetic-Reynold`s-number MHD dynamos.

Kulsrud, R.M.

1995-01-01

380

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

381

Ternary gas plasma welding torch  

NASA Technical Reports Server (NTRS)

A plasma arc welding torch is discussed. A first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasma gas enters one end of the electrode and exits the electrode at the tip thereof for co-acting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body and circulates around the head of the torch adjacent to the electrode tip.

Rybicki, Daniel J. (inventor); Mcgee, William F. (inventor); Waldron, Douglas J. (inventor)

1995-01-01

382

Optical properties of cluster plasma  

SciTech Connect

It is shown that unlike a gas plasma or an electron plasma in a metal, an ionized clustered material ({open_quotes}cluster plasma{close_quotes}) permits propagation below the plasma cut-off of electromagnetic (EM) waves whose phase velocity is close to but below the speed of light. Its unique properties allow a variety of applications, including direct acceleration of particles with its EM fields and the phase matching of waves of high harmonic generation (HHG). The particle-in-cell simulation demonstrates the new optical mode, the cluster mode. {copyright} {ital 1999 American Institute of Physics.}

Tajima, T. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Kishimoto, Y. [Advanced Photon Research Center, Japan Atomic Energy Research Institute, Naka, Ibaraki 311-0195 (Japan)] [Advanced Photon Research Center, Japan Atomic Energy Research Institute, Naka, Ibaraki 311-0195 (Japan); Downer, M.C. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

1999-10-01

383

Optical properties of cluster plasma  

NASA Astrophysics Data System (ADS)

It is shown that unlike a gas plasma or an electron plasma in a metal, an ionized clustered material (``cluster plasma'') permits propagation below the plasma cut-off of electromagnetic (EM) waves whose phase velocity is close to but below the speed of light. Its unique properties allow a variety of applications, including direct acceleration of particles with its EM fields and the phase matching of waves of high harmonic generation (HHG). The particle-in-cell simulation demonstrates the new optical mode, the cluster mode.

Tajima, T.; Kishimoto, Y.; Downer, M. C.

1999-10-01

384

On the excess energy of nonequilibrium plasma  

SciTech Connect

The energy that can be released in plasma due to the onset of instability (the excess plasma energy) is estimated. Three potentially unstable plasma states are considered, namely, plasma with an anisotropic Maxwellian velocity distribution of plasma particles, plasma with a two-beam velocity distribution, and an inhomogeneous plasma in a magnetic field with a local Maxwellian velocity distribution. The excess energy can serve as a measure of the degree to which plasma is nonequilibrium. In particular, this quantity can be used to compare plasmas in different nonequilibrium states.

Timofeev, A. V. [National Research Centre Kurchatov Institute, Institute of Hydrogen Power Engineering and Plasma Technologies (Russian Federation)

2012-01-15

385

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

386

Thermal plasma processing in the nineties  

Microsoft Academic Search

In the context of materials which are expected to be one of the major technical issues in the nineties, an attempt is made to describe the role which thermal plasma processing may play in these years. Newer developments in plasma melting\\/remelting, extractive metallurgy, plasma deposition, plasma synthesis, and plasma densification are briefly described since it is anticipated that these developments

E. Pfender

1988-01-01

387

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

388

Redshift of photons penetrating a hot plasma  

Microsoft Academic Search

A new interaction, plasma redshift, is derived, which is important only when photons penetrate a hot, sparse electron plasma. The derivation of plasma redshift is based entirely on conventional axioms of physics. When photons penetrate a cold and dense plasma, they lose energy through ionization and excitation, Compton scattering on the individual electrons, and Raman scattering on the plasma frequency.

Ari Brynjolfsson

2004-01-01

389

The physics of laser plasma interactions  

Microsoft Academic Search

The interactions of laser plasmas are considered theoretically in an introduction for advanced students and practicing scientists. Chapters are devoted to the basic concepts and two-fluid descriptions of plasmas, computer simulations of plasmas using particle codes, EM wave propagation in plasmas, propagation of obliquely incident light waves in inhomogeneous plasmas, collisional absorption of EM waves, and parametric excitation of electron

William L. Kruer

1988-01-01

390

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

391

Perspectives on space and astrophysical plasma physics  

Microsoft Academic Search

The current status and future prospects of space and astrophysical plasma research are reviewed. Topics discussed include the relationship between laboratory and space plasma physics, the relationship between space and astrophysical plasma research, and critical problems of space and astrophysical plasma physics. Two types of MHD systems, winds and magnetospheres, and two important plasma processes, reconnection and particle acceleration, are

C. F. Kennel; F. Coroniti; J. Arons; R. Blandford; M. Israel

1985-01-01

392

PhotoResist Ashing Byatmospheric Pressure Plasma  

Microsoft Academic Search

Summary form only given. Atmospheric plasma has an advantage not to use vacuum equipments. Thus, many researchers are beginning to develop methods of plasma generation at the atmospheric pressure and to find various industrial applications of the atmospheric plasmas, which may replace vacuum plasmas. Photo-resist (PR) ashing process has been conducted in vacuum plasma. PR ashing has been conventionally done

K. H. Han; J. G. Kang; H. S. Uhm; B. K. Kang

2005-01-01

393

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

394

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

395

Undamped electrostatic plasma waves  

SciTech Connect

Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

Valentini, F.; Perrone, D.; Veltri, P. [Dipartimento di Fisica and CNISM, Universita della Calabria, 87036 Rende (CS) (Italy); Califano, F.; Pegoraro, F. [Dipartimento di Fisica and CNISM, Universita di Pisa, 56127 Pisa (Italy); Morrison, P. J. [Institute for Fusion Studies and Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States); O'Neil, T. M. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

2012-09-15

396

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

397

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

398

L2 Plasma Environments  

NASA Technical Reports Server (NTRS)

The second LaGrange point, 1.5 million miles from the Earth in the anti-solar direction, is becoming an important destination for scientific spacecraft. The quasi-stable gravity field requires little energy resources for station keeping and astronomical missions-infrared and microwave in particular-find the minimal impact from Earth albedo radiation and limited restrictions on viewing directions a tremendous advantage in their mission design. Spacecraft design for L2 missions will have to consider the plasma environments of the ambient solar wind, magnetosheath, and magnetotail from energies of a few 10s of an eV through 10s of keV in addition to enhanced energetic particle populations from 10s to 1000 keV during solar energetic particle events. This presentation will provide a background on the appropriate L2 charged particle environments at L2 and describe modeling efforts at MSFC to develop environment specification tools for the L2 plasma environment.

Minow, Joseph I.; Blackwell, William C., Jr.

2003-01-01

399

L2 Plasma Environments  

NASA Technical Reports Server (NTRS)

The second LaGrange point, 1.5 million miles from the Earth in the anti-solar direction, is becoming an important destination for scientific spacecraft. The quasi-stable gravity field requires little energy resources for station keeping and astronomical missions-infrared and microwave in particular-find the minimal impact from Earth albedo radiation and limited restrictions on viewing directions a tremendous advantage in their mission design. Spacecraft design for L2 missions will have to consider the plasma environments of the ambient solar wind, magnetosheath, and magnetotail from energies of a few 10s of an eV through 10 s of keV in addition to enhanced energetic particle populations from 10s to l000 keV during solar energetic particle events. This presentation will provide a background on the appropriate L2 charged particle environments at L2 and describe modeling efforts at MSFC to develop environment specification tools for the L2 plasma environment.

Minow, Joseph I.; Blackwell, William C., Jr.

2003-01-01

400

Quarantine Plasma: Quo vadis?  

PubMed Central

Summary Upon the introduction of mandatory nucleic acid amplification technology (NAT) testing in Germany for HCV, quarantining of fresh frozen plasma (FFP) was reduced in 2002 from 6 to 4 months. In 2004 HIV-1 NAT and in 2005 anti-HBc testing were introduced to further reduce the residual transmission risks for transfusion relevant viruses. After testing more than 40 million donations by HCV NAT it became obvious that NAT testing has a very significant impact on viral blood safety by reducing the residual risk by a factor of 10. Only one documented HCV transmission occurred during more than 10 years of NAT testing in Germany, indicating that the remaining risk is marginal. Similar data were obtained for HIV-1. The question arises whether we could discontinue quarantining of FFP or further reduce the quarantining interval for retesting of the donor. This could facilitate logistics and reduce losses as quarantine FFP can be released earlier after donation and at regular donation intervals. Essential parameters for estimating the remaining infectious risks are the minimal infectious dose and replication kinetics of the viruses involved, the detection limits of the NAT tests applied, and the volume of plasma transfused. In essence it can be assumed that discontinuation of quarantining would only marginally increase the residual risk and that the reduction of the quarantine period to only 4 weeks would add an additional benefit to the viral safety of quarantine FFP.

Roth, W. Kurt

2010-01-01

401

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

402

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

403

Study of radiative plasma structures in laser driven ablating plasmas  

SciTech Connect

The mechanism is analyzed that generates radiative plasma structures (RPS) [J. P. Dahlburg {ital et al.}, J. Quant Spectros. Radiat. Transfer {bold 54}, 113 (1995)] in driven, ablating plasmas of subcritical density. A reduced set of radiation-hydrodynamics equations is derived which model the onset of RPS phenomenon. {copyright} {ital 1999 American Institute of Physics. }

Hazak, G.; Velikovich, A.L. [Berkeley Research Associates Inc., Springfield, Virginia 22150 (United States)] [Berkeley Research Associates Inc., Springfield, Virginia 22150 (United States); Klapisch, M. [ARTEP Inc, Columbia, Maryland 20145 (United States)] [ARTEP Inc, Columbia, Maryland 20145 (United States); Schmitt, A.J.; Dahlburg, J.P.; Colombant, D. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. (United States)] [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. (United States); Gardner, J.H.; Phillips, L. [LCPFD Naval Research Laboratory, Washington, D.C. (United States)] [LCPFD Naval Research Laboratory, Washington, D.C. (United States)

1999-10-01

404

Study of radiative plasma structures in laser driven ablating plasmas  

NASA Astrophysics Data System (ADS)

The mechanism is analyzed that generates radiative plasma structures (RPS) [J. P. Dahlburg et al., J. Quant Spectros. Radiat. Transfer 54, 113 (1995)] in driven, ablating plasmas of subcritical density. A reduced set of radiation-hydrodynamics equations is derived which model the onset of RPS phenomenon.

Hazak, G.; Velikovich, A. L.; Klapisch, M.; Schmitt, A. J.; Dahlburg, J. P.; Colombant, D.; Gardner, J. H.; Phillips, L.

1999-10-01

405

Ion plasma waves in dusty plasmas - Halley's comet  

Microsoft Academic Search

Ion waves in a plasma are investigated in the presence of massive charged dust particles, a common space-plasma component now known to exist also in planetary rings and comets. An equation is derived describing low-frequency electrostatic perturbations on a nonhomogeneous background, where the inhomogeneity is due to a distribution of charged grains, each surrounded by an equilibrium statistical distribution of

U. de Angelis; V. Formisano; M. Giordano

1988-01-01

406

Advances in Dusty Plasmas 5.Strongly Coupled Dusty Plasmas  

NASA Astrophysics Data System (ADS)

We review thermodynamical and dynamical properties of strongly coupled dusty plasmas, focusing on the recent development of molecular dynamics (MD) simulations. In the present paper, dusty plasmas are modeled by the Yukawa system, which is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials. The phase diagram, wave dispersion relations and some transport coefficients of Yukawa systems are discussed.

Hamaguchi, Satoshi

407

23rd National Symposium on Plasma Science & Technology (PLASMA2008)  

Microsoft Academic Search

The Twentieth Century has been a defining period for Plasma Science and Technology. The state of ionized matter, so named by Irving Langmuir in the early part of twentieth century, has now evolved in to a multidisciplinary area with scientists and engineers from various specializations working together to exploit the unique properties of the plasma medium. There have been great

A K Das

2010-01-01

408

The Coalition for Plasma Science: Bringing Plasmas to the Public  

Microsoft Academic Search

The Coalition for Plasma Science is a group of institutions, organizations, and companies that have joined forces to increase awareness and understanding of plasma science and its many applications and benefits for society. The CPS undertakes a range of activities to support this goal. Members include national laboratories, universities, industries, and individuals. The CPS maintains a web page (http:\\/\\/www.plasmacoalition.org), and

Lee Berry

2003-01-01

409

Measurement of Plasma Parameters in an Inductively Coupled Plasma Reactor.  

National Technical Information Service (NTIS)

The objective is to deepen the understanding of basic plasma properties in a high-density inductively coupled plasma(ICP) reactor. The experiment using a Langmuir probe, which is made of tungsten wire having length of 2.3 mm and diameter of 0.65 mm, is ca...

H. Sasaki K. Nanbu M. Takahashi

2000-01-01

410

Diagnostics of the External Plasma for the Plasma Rocket.  

National Technical Information Service (NTIS)

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 c...

G. R. Karr

1997-01-01

411

Plasma atomic layer etching using conventional plasma equipment  

Microsoft Academic Search

The decrease in feature sizes in microelectronics fabrication will soon require plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching (PALE) is forming a layer of passivation that allows the underlying substrate material to be etched with lower activation energy than in the absence of the passivation. The subsequent removal of the passivation with carefully

Mark J. Kushner; Ankur Agarwal

2009-01-01

412

Hydrodynamic confinement of thermonuclear plasmas trisops VIII (plasma liner confinement)  

Microsoft Academic Search

Experiments on fusion reactions produced by adiabatic compression of plasma vortex structures are discussed. The TRISOPS machine at the University of Miami has been modified by improving the preionization of the plasma and increasing the ring frequency of the conical theta-pinch coils. The results obtained with a series of experiments leading up to the latest machine, TRISOPS VIII, are reviewed.

D. R. Wells; P. E. Ziajka; J. L. Tunstall

1986-01-01

413

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

414

Coupled plasma-neutrals kinetic modeling of SOL plasma  

NASA Astrophysics Data System (ADS)

First completely kinetic 3D (one component in real space and two dimensional in velocity space) model for both charged and neutral particles interaction in the scrape-off layer (SOL) plasma is presented. Electron and ion distribution functions are described by two coupled kinetic equations taking into account non-linear Coulomb collisions and inelastic collisions with neutrals. Kinetic equation for neutrals takes into account collisions with both plasma species and elastic collisions with neutrals. The latter are modeled by simplified Boltzmann term using finite-volume approach. We present first results of modeling of fully kinetic ``parallel'' SOL plasma-neutrals flow with realistic C-Mod-like parameters from extended non-linear Fokker-Planck code ALLA [1,2]. cm [1] A.A.Batishcheva et al., Physics of Plasmas 3 , 1634, 1996 cm [2] O.V.Batishchev et al., Physics of Plasmas 4 (5), 1672, 1997

Batishchev, Oleg V.

1997-11-01

415

Nonlinear plasma and beam physics in plasma wake-fields  

SciTech Connect

In experimental studies of the Plasma Wake-field Accelerator performed to date at the Argonne Advanced Accelerator Test Facility, significant nonlinearities in both plasma and beam behavior have been observed. The plasma waves driven in the wake of the intense driving beam in these experiments exhibit three-dimensional nonlinear behavior which has as yet no quantitative theoretical explanation. This nonlinearity is due in part to the self-pinching of the driving beam in the plasma, as the denser self-focused beam can excite larger amplitude plasma waves. The self-pinching is a process with interesting nonlinear aspects: the initial evolution of the beam envelope and the subsequent approach to Bennett equilibrium through phase mixing. 35 refs., 10 figs.

Rosenzweig, J.B.

1990-02-12

416

Plasma acetate turnover and oxidation.  

PubMed Central

Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.

Skutches, C L; Holroyde, C P; Myers, R N; Paul, P; Reichard, G A

1979-01-01

417

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

418

Rayleigh's Problem in Collisionless Plasmas.  

National Technical Information Service (NTIS)

The initial motion of the unsteady plasma boundary layer flow over an infinite flat plate with heat transfer effects under the influence of an applied magnetic field is studied. Based on a plasma kinetic formulation, small-time exact solutions are derived...

C. M. Chang T. S. Chang

1971-01-01

419

Doppler Shift in a Plasma.  

National Technical Information Service (NTIS)

It is first shown that the ideal electron plasma (presence of protons neglected) is unique among all dispersive media in that it does not distinguish any inertial frame of reference in terms of utility. The theory of the Doppler shift in an ideal plasma i...

B. Manz

1968-01-01

420

Proteome Patterns in Uremic Plasma  

Microsoft Academic Search

In patients with chronic kidney disease (CKD), peptides and proteins circulate at altered concentrations versus in healthy individuals. We have characterized proteome samples from 7 pooled CKD stage 5 patients not yet on dialysis and with no known co-morbidities. We also analyzed pooled plasma samples from 7 healthy age- and sex-matched controls. After immunodepletion of the 6 most abundant plasma

Uzma Naseeb; Jawed Shafqat; Theres Jägerbrink; Shamshad Zarina; Anders Alvestrand; Hans Jörnvall; Jonas Axelsson

2008-01-01

421

Formation of dusty plasma molecules  

Microsoft Academic Search

The electrostatic interaction potential energy for two Debye shielded macroscopic grains or impurities is obtained for all values of intergrain separation both in the plasma as well as in the plasma sheath. The predicted cohesive energy assumes a form familiar from molecular physics but with no ad hoc assumptions regarding the form of the repulsive and attractive regions and no

D. P. Resendes; J. T. Mendonça; P. K. Shukla

1998-01-01

422

Plasma Injector for HTP Reactors.  

National Technical Information Service (NTIS)

A study has been made of the feasibility of producing neutralized ion beams by accelerating the ions in a plasma sheath produced by the interaction of an electron beam with gas. This complex process has been subdivided into three areas, beam-plasma intera...

M. Seidl

1974-01-01

423

Relaxed states with plasma flow.  

National Technical Information Service (NTIS)

In the theory of relaxation, a plasma reaches a state of minimum energy subject to constant magnetic helicity. In this state the plasma velocity is zero. Several authors have attempted to extend the theory, by introducing a number of different helicity in...

K. Avinash J. B. Taylor

1991-01-01

424

Grain charge in dusty plasmas  

Microsoft Academic Search

Measurements [Barkan et al., Phys. Rev. Lett. 73, 3093 (1994)] of the grain charge in dusty plasmas have shown that it can be significantly reduced with respect to the single grain charge. This can have important consequences on the still open problem of strong vs weak coupling in many experiments with dusty plasmas. A simple charging model, based on the

U. de Angelis; A. Forlani

1998-01-01

425

Plasma chemistry and organic synthesis  

NASA Technical Reports Server (NTRS)

The characteristic features of chemical reactions using low temperature plasmas are described and differentiated from those seen in other reaction systems. A number of examples of applications of plasma chemistry to synthetic reactions are mentioned. The production of amino acids by discharge reactions in hydrocarbon-ammonia-water systems is discussed, and its implications for the origins of life are mentioned.

Tezuka, M.

1980-01-01

426

Ionization Equilibrium in Dense Plasmas  

Microsoft Academic Search

The average degree of ionization for a strongly coupled plasma is investigated and calculated. Two widely used approaches: the Saha equation method and the Thomas -Fermi (TF) statistical atomic model are adopted to determine the degree of ionization. Both methods are modified in a number of ways to include the strong coupling effect in the plasma. In the Saha equation

Ruoxian Ying

1987-01-01

427

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

428

Arcs, plasma torches and applications  

Microsoft Academic Search

The applications of arcs and plasma torches can be roughly classified in two domains: electrical engineering and thermal (or chemical) processes. In the first category we can consider circuit-breakers, arc lamps and some aspects concerning lightning. In the second category, we can distinguish metallurgical processes (cutting, welding, arc furnaces and metal heating), plasma spraying, particle production and treatment, fullerenes and

A. Gleizes; J. J. Gonzalez; M. Razafinimanana

2002-01-01

429

The plasma system of RFX  

Microsoft Academic Search

The “plasma system” of RFX includes the first wall, the vacuum vessel, the stabilizing shell, the vacuum and gas injection system, the remote handling system and the relevant auxiliary plants (cooling, baking, glow discharge cleaning, etc.).Since no limiters are provided, the full energy and particle flux from the plasma must be absorbed by the first wall. Taking into account the

F Gnesotto; P Sonato; W. R Baker; A Doria; F Elio; M Fauri; P Fiorentin; G Marchiori; G Zollino

1995-01-01

430

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

431

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

432

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

433

Plasma Ignition of Liquid Propellant  

Microsoft Academic Search

The ignition of a liquid gun propellant that is an aqueous mixture of hydroxylammonium nitrate (HAN) and triethanolammonium nitrate (TEAN), was studied using a plasma-torch igniter. The torch proved to be an excellent device for achieving safe and reproducible ignition, and combustion phenomena in a laboratory setting. Sufficient gas pressure was developed In the intenor of the plasma torch to

R. J. Catiolica; N. Klein

1987-01-01

434

Ultraintense laser-plasma interactions  

Microsoft Academic Search

Lasers currently under construction or completed carry laser-plasma interactions well into the relativistic regime, with intensities of high 1019 or 1020 Wcm-2. In such cases relativistic effects play a major role and may dominate the physics involved in the interaction. There are many plasma physics related applications which aim to make use of these new ultra intense short pulse lasers.

A. Dyson

1999-01-01

435

Modelling of LIBS plasma expansion  

Microsoft Academic Search

A one-dimensional time-dependent fluid dynamic model has been developed to describe the expansion of the plume produced by laser ablation. The model includes chemical reactions considered in local thermodynamic equilibrium to describe the expansion of a TiO plasma. The results are discussed in connection with LIBS plasmas.

G. Colonna; A. Casavola; M. Capitelli

2001-01-01

436

Plasma protein binding of drugs  

Microsoft Academic Search

In blood many drugs are partly associated with blood constituents such as plasma proteins and erythrocytes. For most such drugs, only the unbound fraction of the total amount is available for diffusion out of the vascular system to sites of pharmacological activity. The unbound fraction of drug in plasma is therefore regarded as pharmacologically active, while the fraction bound to

J. J. H. M. Lohman; F. W. H. M. Merkus; K. H. Rahn

1986-01-01

437

EDITORIAL: Focus on Plasma Medicine  

Microsoft Academic Search

'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

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

2009-01-01

438

The quark-gluon plasma  

Microsoft Academic Search

I present various aspects of the physics of the quark-gluon plasma. Known properties of the transition from hadronic matter to the quark-gluon plasma are recalled. Progress in the phenomenology of ultra-relativistic heavy ion collisions is discussed on two examples. Some recent theoretical developments are mentioned.

Jean-Paul Blaizot

1993-01-01

439

Pulsed metallic-plasma generators  

Microsoft Academic Search

A pulsed metallic-plasma generator is described which utilizes a vacuum arc as the plasma source. The arc is initiated on the surface of a consumable cathode which can be any electrically conductive material. Ignition is accomplished by using a current pulse to vaporize a portion of a conductive film on the surface of an insulator separating the cathode from the

D. L. Lockwood

1972-01-01

440

Study of Cryogenic Complex Plasma.  

National Technical Information Service (NTIS)

Overall goal is to study basic physics of a complex plasma at a room temperature as well as in a cryogenic environment and to reveal novel natures of a cryogenic complex plasma produced by a stable discharge above or in super fluid liquid helium . This fi...

O. Ishihara

2008-01-01

441

Polarization spectroscopy of tokamak plasmas  

SciTech Connect

Measurements of polarization of spectral lines emitted by tokamak plasmas provide information about the plasma internal magnetic field and the current density profile. The methods of polarization spectroscopy, as applied to the tokamak diagnostic, are reviewed with emphasis on the polarimetry of motional Stark effect in hydrogenic neutral beam emissions. 25 refs., 7 figs.

Wroblewski, D.

1991-09-01

442

Stationary plasma thruster plume emissions  

Microsoft Academic Search

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

David H. Manzella

1994-01-01

443

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.

444

Superdense Plasma in LHD  

NASA Astrophysics Data System (ADS)

In reduced recycling discharges using a Local Island Divertor (LID) in the Large Helical Device (LHD), a stable superdense plasma develops spontaneously when a series of pellets are injected. A core region with ˜ 4.5 x 10^20 m-3 and temperature of 0.85 keV is maintained by an Internal Diffusion Barrier (IDB). The density gradient at the IDB (r/a ˜ 0.6) is very high, and the particle confinement time in the core region is ˜ 300 ms. The temperature profile inside the IDB (r/a < 0.6) is flat, on the other hand, its gradient in the outer region is steep. Because of the increase in the central pressure, a large, stabilizing Shafranov shift up to ˜ 0.3 m is observed. The critical ingredients for IDB formation are a strongly pumped divertor to reduce edge recycling, and multiple pellet injection to ensure strong central fueling. Gas puffing results in broad, flat or slightly inverted density profiles, and does not lead to formation of a superdense plasma. Low density in the outer region helps to raise the edge temperature gradient there and hence the core temperature. In that sense, for the strong pumping, it does not take an LID to reduce the edge recycling, only if a conventional Helical Divertor (HD) has sufficient pumping capability. Similar discharges can actually be achieved in the HD configuration under exhaustive wall conditioning, although it cannot last for a long time because of the saturation of the pumping capability of the wall. Although use of the island divertor reduces the confinement volume by ˜40 % from its nominal value, superdense LID discharges exhibit the highest performance (n0T0?E = 4.4 x 10^19 m-3.keV.s) obtained so far in LHD. These plasmas provide unique opportunities for exploration of high-beta MHD stability in heliotron/stellarator configurations, and may extrapolate to a novel scenario for fusion ignition at very high density and relatively low temperature.

Morisaki, Tomohiro

2006-10-01

445

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

446

Plasma Treatment of Polymers for Improved Adhesion.  

National Technical Information Service (NTIS)

A variety of plasma treatments of polymer surfaces for improved adhesion are reviewed: noble and reactive gas treatment of fluoropolymers; noble and reactive treatment of polyolefins, and plasma-induced amination of polymer fibers. The plasma induced surf...

J. A. Kelber

1988-01-01

447

New Techniques for Plasma Density Profiling.  

National Technical Information Service (NTIS)

Two new techniques for the measurement of plasma density profiles are presented. The two approaches are aimed at simultaneously overcoming uncertainties due to both the Abel inversion and plasma irreproducibility. Plasmas with densities approximately grea...

R. Kristal

1978-01-01

448

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

449

Pathogen Inactivated Plasma Concentrated: Preparation and Uses.  

National Technical Information Service (NTIS)

Plasma transfusion is a crucial element of casualty care. Unfortunately, two plasma components sharply limit its use: contaminants and excess water. Contamination arises because plasma must be obtained from human donors, and these donors may be infected w...

H. E. Purdum

2004-01-01

450

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

451

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

452

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

453

21 CFR 866.2160 - Coagulase plasma.  

...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

454

A Power Model for Plasma Convection.  

National Technical Information Service (NTIS)

A model for simulating the convection of plasma microstructure has been constructed. Labeled 'striation convection,' the procedure is based on the conservation of the square of plasma density or 'plasma power'. The model is driven by a previously develope...

J. B. Workman S. Y. F. Chu J. R. Ferrante

1979-01-01

455

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

456

Advances in plasma melting technology  

NASA Astrophysics Data System (ADS)

The quest for 'defect-free' high performance metals has benefited from the expansion of plasma hearth melting capacity. 'Skull' melting in water-cooled copper containers under an inert gas atmosphere allows elimination of ceramic and refractory metal inclusions when melting reactive metals and superalloys, while retaining the input alloy content. The interactions of operating variables such as furnace pressure, nature of gas, arc current and heat input pattern with product properties such as homogeneity, grain size, and inclusions are described. By proper process control, plasma hearth melting has been qualified as one of only two processes suitable for particularly demanding rotating grade engine parts made of titanium alloy. Costs of plasma hearth melting are less than with electron beam. Extension of plasma processing to other alloys is being actively pursued. Powder production is currently practical with plasma melting and bottom pouring to make powder. Some speculations on future trends in materials and operating temperatures are offered.

Eschenbach, R.; Hoffelner, W.

457

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

458

Conducting Grains in Dusty Plasmas  

NASA Astrophysics Data System (ADS)

The existence of dusty plasma environments in space is common, with the dust originating from a variety of sources. Such environments include protostellar and protoplanetary systems during their formation and evolution. In addition, iron rich meteors, which contain remnants of primordial solar system material, are also a source for micron-sized metallic dust particles that interact with the surrounding plasma. Although research has been conducted on nonconducting grains within a complex plasma environment, very little experimental data exists on conducting grains within complex plasmas. This study will compare and contrast the dynamics of non-conducting (Melamine Formaldehyde) and conducting particles (Gold-coated Melamine Formaldehyde particles) immersed in a capacitively coupled RF plasma maintained within a GEC reference cell. The resulting experimental data will be related to the fundamental physics behind the charging mechanism for such micron-size particles.

Hyde, Truell; Matthews, Lorin; Carmona-Reyes, Jorge

459

Critical Issues in Plasma Accelerator  

NASA Astrophysics Data System (ADS)

Updated achievements and critical issues in plasma accelerators are summarized. As to laser plasma accelerators, we cover the results of plasma cathodes by U.Michigan, LBNL, LOA and U.Tokyo. Although many new results of accelerated electrons have been reported, the electrons do not yet form a bunch with narrow energy spread. Several injection schemes and measurements to verify ultrashort bunch (tens fs) with narrow energy spread, low emittance and many charges are planned. E-162 experiments by UCLA / USC / SLAC and a newly proposed experiment on density transition trapping are introduced for electron beam driven plasma accelerators. Their main purpose is realization of GeV plasma accelerator, but application to pump-and-probe analysis for investigation of ultrafast quantum phenomena is also promising.

Uesaka, M.; Hosokai, T.

2004-10-01

460

Plasma evolution in the heliosheath  

NASA Astrophysics Data System (ADS)

Voyager 2 is now at 97 AU probably about 20 AU deep into the heliosheath. The Plasma Science experiment provides the only direct observations of plasma in the heliosheath. The plasma parameters depend on many factors; the solar wind source, the motions of the termination shock, and the influence of the interstellar medium among them. I will present the most recent plasma observations. Plasma speeds observed at Voyager 2 have decreased slowly across the heliosheath and remain well above those inferred at Voyager 1. The Voyager 2 flow angles continue to increase with large flows in the T than N directions (RTN coordinates). The density and temperature have decreased across the heliosheath until the beginning of 2011; since then the density has increased by a factor of 2 and the speed and temperature have also increased.

Richardson, J. D.

2011-12-01

461

Turbulence in Hall MHD Plasmas  

SciTech Connect

The Hall MHD description of magnetized plasma is invoked in many space, laboratory and astrophysical plasmas when the characteristic frequency is bigger than the ion cyclotron frequency where the MHD description is inapplicable. In this paper, we present fully self consistent 3D simulations of compressible Hall MHD plasma to describe spectral features relevant to the solar wind plasma. We find that a k{sup -7/3} spectrum sets in for the fluctuations that are smaller than ion gyro radius. We further investigate scale dependent anisotropy led by nonlinear processes relevant to the solar wind plasma. Our work is important particularly in understanding the role of wave and nonlinear cascades in the evolution of the solar wind, structure formation at the largest scales.

Shaikh, Dastgeer [Department of Physics and Center for Space Plasma and Aeronomy Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Shukla, P. K. [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2010-12-14

462

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

463

Laser-produced annular plasmas  

SciTech Connect

A new technique is presented for the formation of annular plasmas on a metal surface with a high-power laser using a combination of axicon and converging lenses. The annular plasma formed on a titanium target in a chamber of hydrogen gas was investigated using schlieren imaging and Mach Zehnder interferometry. Expansion of the plasma was shown to be anisotropic with velocities of {approx}10{sup 3}-10{sup 4} m/s. Electron densities of 10{sup 18} cm{sup -3} were measured with radial profiles that confirm the presence of a hollow structure. The interferometric observations also show the presence of an inward shock wave traveling to the center of the annular plasma, which compresses the background neutrals, reaching a density around 18 times initial gas density, at 95 ns after the initial annular plasma is produced.

Veloso, F.; Chuaqui, H.; Aliaga-Rossel, R.; Favre, M.; Mitchell, I. H.; Wyndham, E. [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860 Macul, Santiago 782-0436 (Chile)

2006-06-15

464

Cyclic olefin copolymer plasma millireactors.  

PubMed

The novelty of this paper lies in the development of a multistep process for the manufacturing of plasma millireactors operating at atmospheric pressure. The fabrication process relies on the integration of metallic electrodes over a cyclic olefin copolymer chip by a combination of photopatterning and sputtering. The developed plasma millireactors were successfully tested by creating air discharges in the gas volume of the millichannel. A sputtered silica layer was deposited on the channel walls to provide a barrier between the plasma and the polymer in order to prevent the alteration of polymer surfaces during the plasma treatment. Interest in this process of employing plasma millireactor as a high reactive environment is demonstrated here by the degradation of a volatile organic compound (acetaldehyde) in ambient air. In this miniaturized device, we obtained a high acetaldehyde conversion (98%) for a specific input energy lower than 200 J L(-1). PMID:24957952

Schelcher, G; Guyon, C; Ognier, S; Cavadias, S; Martinez, E; Taniga, V; Malaquin, L; Tabeling, P; Tatoulian, M

2014-08-21

465

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

466

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

467

Quasisteady state interpulse plasmas  

SciTech Connect

The generation of quasisteady state plasmas in the power off phase, by short pulses [pulse duration ({tau}{sub p}){approx}0.5-1.2 {mu}s] of intense (60-100 kW) microwaves in the X band (9.45 GHz) is observed experimentally. The steady state is sustained from a few to tens of microseconds and depends upon the ionization processes in the interpulse phase and the characteristic diffusion length. The results are explained by a model, which considers the electron acceleration effects by the large amplitude of the field, the energy losses, and the characteristic electromagnetic field decay time. The effects of wave frequency, microwave power density, and particle diffusion on the steady state are investigated. A striking difference with conventional afterglows of pulsed discharges is pointed out.

Bhattacharjee, Sudeep; Dey, Indranuj; Sen, Abhijit; Amemiya, Hiroshi [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Graduate School of Chuo University, Bunkyo, Tokyo 112-8551 (Japan)

2007-06-01

468

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

469

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

470

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

471

Landau damping in space plasmas  

SciTech Connect

Space plasmas typically possess a particle distribution function with an enhanced high-energy tail that is well modeled by a generalized Lorentzian (or kappa) distribution with spectral index {kappa}. The modified plasma dispersion function {bold Z}{sup *}{sub {kappa}}({xi}) is employed to analyze the Landau damping of (electrostatic) Langmuir waves and ion-acoustic waves in a hot, isotropic, unmagnetized, generalized Lorentzian plasma, and the solutions are compared with the classical results for a Maxwellian plasma. Numerical solutions for the real and imaginary parts of the wave frequency {omega}{sub 0}{minus}{ital i}{gamma} are obtained as a function of the normalized wave number {ital k}{lambda}{sub D}, where {lambda}{sub D} is the electron Debye length. For both particle distributions the electrostatic modes are strongly damped, {gamma}/{omega}{sub 0}{much gt}1, at short wavelengths, {ital k}{lambda}{sub D}{much gt}1. This collisionless damping becomes less severe at long wavelengths, {ital k}{lambda}{sub D}{much lt}1, but the attenuation of Langmuir waves is much stronger for a generalized Lorentzian plasma than for a Maxwellian plasma. This will further localize Langmuir waves to frequencies just above the electron plasma frequency in plasmas with a substantial high-energy tail. Landau damping of ion-acoustic waves is only slightly affected by the presence of a high-energy tail, but is strongly dependent on the ion temperature. Owing to the simple analytical form of the modified plasma dispersion function when {kappa}=2 (corresponding to a pronounced high-energy tail), exact analytical results for the real and imaginary parts of the wave frequency can be found in this case; similar solutions are not available for a Maxwellian plasma.

Thorne, R.M. (Department of Atmospheric Sciences, University of California at Los Angeles, Los Angeles, California 90024-1565 (USA)); Summers, D. (Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7 Canada (CA))

1991-08-01

472

NCSX Plasma Heating Methods  

SciTech Connect

The NCSX (National Compact Stellarator Experiment) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral-beam injection, and radio-frequency. Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The plan is to provide 3 MW of 50 keV balanced neutral-beam tangential injection with pulse lengths of 500 msec for initial experiments, and to be upgradeable to pulse lengths of 1.5 sec. Subsequent upgrades will add 3 MW of neutral-beam injection. This Chapter discusses the NCSX neutral-beam injection requirements and design issues, and shows how these are provided by the candidate PBX-M (Princeton Beta Experiment-Modification) neutral-beam injection system. In addition, estimations are given for beam-heating efficiencies, scaling of heating efficiency with machine size an d 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 radio-frequency 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 radio-frequency system lend themselves to current drive, so that if current drive became desirable for any reason only minor modifications to the heating system described here would be needed. The radio-frequency system will also be capable of localized ion heating (bulk or tail), and possibly ion-Bernstein-wave-generated sheared flows.

H.W. Kugel; D. Spong; R. Majeski; M. Zarnstorff

2003-02-28

473

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

474

Plasma cell leukemia.  

PubMed

Plasma cell leukemia (PCL) is a rare, yet aggressive plasma cell (PC) neoplasm, variant of multiple myeloma (MM), characterized by high levels of PCs circulating in the peripheral blood. PCL can either originate de novo (primary PCL) or as a secondary leukemic transformation of MM (secondary PCL). Presenting signs and symptoms are similar to those seen in MM such as renal insufficiency, hypercalcemia, lytic bone lesions, anemia, and thrombocytopenia, but can also include hepatomegaly and splenomegaly. The diagnostic evaluation of a patient with suspected PCL should include a review of the peripheral blood smear, bone marrow aspiration and biopsy, serum protein electrophoresis (SPEP) with immunofixation, and protein electrophoresis of an aliquot from a 24h urine collection (UPEP). The diagnosis is made when a monoclonal population of PCs is present in the peripheral blood with an absolute PC count exceeding 2000/?L and PC comprising 20% or more of the peripheral blood white cells. The prognosis of PCL is poor with a median survival of 7 to 11 months. Survival is even shorter (2 to 7 months) when PCL occurs in the context of refractory or relapsing MM. There have been no prospective randomized trials investigating the treatment of PCL. Recommendations are primarily based upon data from small retrospective series, case reports, and extrapolation of data from patients with MM. In general, patients are treated with induction therapy followed by hematopoietic cell transplantation (HCT) in those who are appropriate candidates for this approach. The best induction regimen for PCL is not known and there is great variability in clinical practice. Newer agents that are being incorporated into frontline and salvage therapy for MM have also demonstrated activity in PCL such as Immunomodulatory agents and the use of bortezomib with different combinations. PMID:21295388

Albarracin, Flavio; Fonseca, Rafael

2011-05-01

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