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1

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

2

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

3

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

4

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

5

Kinetic description of avalanching systems.  

PubMed

Avalanching systems are treated analytically using the renormalization group (in the self-organized-criticality regime) or mean-field approximation, respectively. The latter describes the state in terms of the mean number of active and passive sites, without addressing the inhomogeneity in their distribution. This paper goes one step further by proposing a kinetic description of avalanching systems making use of the distribution function for clusters of active sites. We illustrate an application of the kinetic formalism to a model proposed for the description of the avalanching processes in the reconnecting current sheet of the Earth's magnetosphere. A description of avalanching systems is proposed that makes use of the distribution function for clusters of active sites. A general kinetic equation is derived that describes the temporal evolution of the distribution function, in terms of growth and shrinking probabilities. The distribution of clusters is derived for the stationary regime, for a quite general class of avalanching systems or arbitrary dimensionality. The approach, including the probability calculation, is illustrated by an application of the kinetic description to the recently proposed burning model. PMID:16241616

Gedalin, M; Balikhin, M; Coca, D; Consolini, G; Treumann, R A

2005-09-01

6

Fluid and drift-kinetic description of a magnetized plasma with low collisionality and slow dynamics orderings. I. Electron theory  

SciTech Connect

A closed theoretical model to describe slow, macroscopic plasma processes in a fusion-relevant collisionality regime is set forward. This formulation is a hybrid one, with fluid conservation equations for particle number, momentum and energy, and drift-kinetic closures. Intended for realistic application to the core of a high-temperature tokamak plasma, the proposed approach is unconventional in that the ion collisionality is ordered lower than in the ion banana regime of neoclassical theory. The present first part of a two-article series concerns the electron system, which is still equivalent to one based on neoclassical electron banana orderings. This system is derived such that it ensures the precise compatibility among the complementary fluid and drift-kinetic equations, and the rigorous treatment of the electric field and the Fokker-Planck-Landau collision operators. As an illustrative application, the special limit of an axisymmetric equilibrium is worked out in detail.

Ramos, J. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge Massachusetts 02139-4307 (United States)

2010-08-15

7

Wave Kinetic Description of Superfluidity  

NASA Astrophysics Data System (ADS)

We propose a wave kinetic description of superfluidity in Bose Einstein condensates. This is based on the traditional two-fluid model, where in contrast with current analysis, the two fluids are treated on similar grounds. Each of the fluids (the condensed gas and the phonon gas) is described by a similar wave kinetic equation. These two equations are coupled. Perturbations of the coupled fluids lead to the formation of excitons which, in the appropriate limits, tend to the first and second sound waves.

Mendonça, J. T.

2014-06-01

8

Kinetic and electromagnetic effects in technical plasmas  

NASA Astrophysics Data System (ADS)

There is an accumulating body of evidence that kinetic effects play a significant role in practically all kinds of technical plasmas. Such plasmas often exhibit several groups of electrons with disparate energies, where electrons from different groups exchange energy only through weak processes. The intrinsically non-Maxwellian charachter of the electron distribution function in this case invalidates the fluid-based approaches for description of the technical plasmas. Rather, a self-consistent kinetic treatment is frequently needed for capturing all the important physics features, whereas fluid models under such conditions can yield quantitatively or even qualitatively erroneous results. Despite this, the fluid-based numerical codes remain a popular tool for investigation of the technical plasmas due to the low computational cost of such codes compared to that of the kinetic ones. The proper description of technical plasmas becomes further complicated if in addition to the kinetic treatment one needs to consider electromagnetic effects, which gain in significance as the electrode size and driving frequency increase, which continues to be the tendency in many CCP industrial plasmas usually described under the electrostatic approximation. In this talk we discuss modern techniques of parallelization of self-consistent kinetic particle-in-cell/Monte-Carlo (PIC/MCC) numerical codes on graphics cards (GPUs), which make kinetic simulations a routine numerical tool for investigation of technical plasmas. Then, we will demonstrate for the plasmas spanning broad parameter range examples of simulations made with such codes, where kinetic effects are important and thus the fluid description is inadequate. Finally, we argue that in many situations the electromagnetic effects relevant to the technical plasmas can be described in the framework of Darwin (magneto-inductive) approximation, which can be implemented as a natural modification in an electrostatic PIC/MCC code, as all the field equations are elliptic. We give the examples of kinetic simulations with electromagnetic effects obtained with such Darwin code.

Eremin, Denis

2012-10-01

9

Lagrangian description of warm plasmas  

NASA Technical Reports Server (NTRS)

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

Kim, H.

1970-01-01

10

Wave-particle-interaction in kinetic plasmas  

NASA Astrophysics Data System (ADS)

Resonant scattering of energetic protons off magnetic irregularities is the main process in cosmic ray diffusion. The typical theoretical description uses Alfvén waves in the low frequency limit. We demonstrate that the usage of Particle-in-Cell (PiC) simulations for particle scattering is feasible. The simulation of plasma waves is performed with the relativistic electromagnetic PiC code ACRONYM and the tracks of test particles are evaluated in order to study particle diffusion. Results for the low frequency limit are equivalent to those obtained with an MHD description, but only for high frequencies results can be obtained with reasonable effort. PiC codes have the potential to be a useful tool to study particle diffusion in kinetic turbulence.

Schreiner, Cedric; Spanier, Felix

2014-07-01

11

Kinetic Simulations of Nonequilibrium Plasmas  

NASA Astrophysics Data System (ADS)

The paper presents study of one of the examples of nonequilibrium plasmas--dielectric barrier discharge in atmospheric air--using kinetic particle-in-cell code VORPAL. It has been demonstrated that the use of state-of-the-art methods for solution of the electrostatic problems and the concept of variable-weight particles for reduction number of particles in dense plasma regions made simulations numerically efficient. Using the developed model the propagation of the cathode-directed streamer driven by 4ns positive pulse has been analyzed in both 2D and 3D. The model reproduced all essential physical phenomena of the streamer propagation. The model has been validated via grid resolution study and study of the concept of variable-weight particles.

Likhanskii, Alexandre

2011-05-01

12

Kinetic simulation of burning plasmas  

NASA Astrophysics Data System (ADS)

Burning plasmas pose new challenges to the fusion theory community. The presence of hot alpha particles generated by fusion reactions introduces new scales and new processes not important in conventional plasmas. Particularly challenging is the fact that the gyroradius of alpha particles can become significant and require a more carefull analysis. For example, in ITER the regular ions at 10keV will have a gyroradius of the order of a tenth of a centimiter, but the alpha particles generated at 3.5MeV will have a gyroradius of 10cm. This scale is no longer small compared to may important processes developing in a fusion device (e.g. neoclassical tearing islands). Therefore many of the approximations we are accustomed to, will no longer be accurate. We present here an approach that is ideally suited to study alpha particles in burning plasmas: the implicit moment kinetic particle in cell method implemented in the code CELESTE. We discuss the method and its aplication to burning plasmas.

Lapenta, Giovanni

2006-04-01

13

A fluid description of plasma double-layers  

NASA Technical Reports Server (NTRS)

The space-charge double-layer that forms between two plasmas with different densities and thermal energies was investigated using three progressively realistic models which are treated by fluid theory, and take into account four species of particles: electrons and ions reflected by the double-layer, and electrons and ions transmitted through it. The two plasmas are assumed to be cold, and the self-consistent potential, electric field and space-charge distributions within the double-layer are determined. The effects of thermal velocities are taken into account for the reflected particles, and the modifications to the cold plasma solutions are established. Further modifications due to thermal velocities of the transmitted particles are examined. The applicability of a one dimensional fluid description, rather than plasma kinetic theory, is discussed. Theoretical predictions are compared with double layer potentials and lengths deduced from laboratory and space plasma experiments.

Levine, J. S.; Crawford, F. W.

1979-01-01

14

Kinetic Profiles in NSTX Plasmas  

SciTech Connect

The National Spherical Torus Experiment (NSTX) is a low aspect ratio (R/a approximately 1.3) device with auxiliary heating from neutral-beam injection (NBI) and high-harmonic fast-wave heating (HHFW). Typical NSTX parameters are R(subscript ''0'') = 85 cm, a = 67 cm, I(subscript ''p'') = 0.7-1.4 MA, B(subscript ''phi'') = 0.25-0.45 T. Three co-directed deuterium neutral-beam sources have injected P(subscript ''NB'') less than or equal to 4.7 MW. HHFW plasmas typically have delivered P(subscript ''RF'') less than or equal to 3 MW. Important to the understanding of NSTX confinement are the new kinetic profile diagnostics: a multi-pulse Thomson scattering system (MPTS) and a charge-exchange recombination spectroscopy (CHERS) system. The MPTS diagnostic currently measures electron density and temperature profiles at 30 Hz at ten spatial locations. The CHERS system has recently become available to measure carbon ion temperature and toroidal flow at 17 radial positions spanning the outer half of the minor radius with 20 msec time resolution during NBI. Experiments conducted during the last year have produced a wide range of kinetic profiles in NSTX. Some interesting examples are presented below.

R.E. Bell; B.P. LeBlanc; C. Bourdelle; D.R. Ernst; E.D. Fredrickson; D.A. Gates; J.C. Hosea; D.W. Johnson; S.M. Kaye; R. Maingi; S. Medley; J.E. Menard; D. Mueller; M. Ono; F. Paoletti; M. Peng; S.A. Sabbagh; D. Stutman; D.W. Swain; E.J. Synakowski; and J.R. Wilson

2001-07-10

15

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

16

Kinetic Theory of the Completely Ionized Plasma.  

National Technical Information Service (NTIS)

The Bogolyubov trial solution for solving the BBGKY hierarchy is generalized for a plasma such that it includes the description of plasma operations. This means that it can be used for unstable as well as for weakly stable and weakly inhomogeneous plasmas...

G. Diener

1973-01-01

17

NLTE4 Plasma Population Kinetics Database  

National Institute of Standards and Technology Data Gateway

SRD 159 NLTE4 Plasma Population Kinetics Database (Web database for purchase)   This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 4th Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.

18

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

19

Mathematical description of the kinetics of metallurgical processes  

Microsoft Academic Search

In the mathematical description of the kinetics of metallurgical processes, empirical and physicomathematical methods may be employed. In the empirical method, the experimental data are approximated by arbitrary functions with no physical basis. The corresponding mathematical models only apply within the range described by the experimental data. This method does not explain the mechanism of the process and therefore provides

A. G. Svyazhin

2008-01-01

20

Relativistic (covariant) kinetic theory of linear plasma waves and instabilities  

SciTech Connect

The fundamental kinetic description is of vital importance in high-energy astrophysics and fusion plasmas where wave phenomena evolve on scales small comparing with binary collision scales. A rigorous relativistic analysis is required even for nonrelativistic plasma temperatures for which the classical theory yielded unphysical results: e.g. collisonless damping of superluminal waves (phase velocity exceeds the speed of light). The existing nonrelativistic approaches are now improved by covariantly correct dispersion theory. As an important application, the Weibel instability has been recently investigated and confirmed as the source of primordial magnetic field in the intergalactic medium.

Lazar, M. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); 'Alexandru Ioan Cuza' University, Faculty of Physics, 6600 Iasi (Romania); Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Centre for Plasma Science and Astrophysics, Ruhr-University, D-44780 Bochum (Germany)

2006-06-19

21

Kinetic Simulation of Recombining Divertor Plasmas  

NASA Astrophysics Data System (ADS)

Fokker-Planck code ALLA can simulate coupled plasma (electrons and ions) and neutral atoms dynamics in the 1D2V approximation by taking into account non-linear Coulomb, and other elastic and inelastic binary collisions [1]. We discuss addition of 3-body recombination process, which is thought to be important for the deeply detached scrape-off layer plasmas. We present first kinetic model of recombining plasma in the tokamak divertor. We discuss observed kinetic phenomena, in particular, effect of non-Maxwellian electron distributions on the effective 3-b volume recombination rate for the realistic conditions of the divertor of Alcator C-Mod and other machines. [1] O.Batishchev, Proc. 16th Int. Conf. Num. Sim. Plasmas, Santa Barbara 155 (1998).

Batishcheva, A. A.; Batishchev, O. V.

1998-11-01

22

Photon kinetic description of nonlinear cross-phase modulation  

NASA Astrophysics Data System (ADS)

We present an alternative description of nonlinear cross-phase modulation based on the kinetic equation for photons. The most relevant feature of this new approach is that phase itself is completely ignored. Formal exact solutions and approximate analytical solutions are discussed. Experimental measurements of cross-phase modulation of two-color ultrashort laser pulses propagating in a highly nonlinear photonic crystal fiber reveal a good agreement with the analytical results.

Mendonça, J. T.; Crespo, H.; Amorim, A. A.; Bernardo, L. M.

2013-11-01

23

Atomic population kinetics in fluctuating plasmas  

NASA Astrophysics Data System (ADS)

A kinetic model for atomic populations in a turbulent plasma is developed in the framework of the so-called continuous time random walk theory. A special emphasis is devoted to the role of temperature fluctuations. With an application to the 1s, 2s and 2p levels of atomic hydrogen, we demonstrate that a resonance effect can be observed.

Catoire, F.; Rosato, J.; Marandet, Y.; Koubiti, M.; Mekkaoui, S.; Capes, H.; Stamm, R.

2012-11-01

24

BOOK REVIEW: Plasma Kinetics in Atmospheric Gases  

Microsoft Academic Search

The book Plasma Kinetics in Atmospheric Gases is a worthwhile contribution to the basic phenomena in nitrogen, oxygen and other atmospheric gases. It contains basic introductory chapters on relaxation in translational, rotational (short) and vibrational (extensive) distribution and on the physics of electron excitation and electron distribution functions. In the latter, electron beam excitation (i.e. high electron energies) are included.

M. Capitelli; C. M. Ferreira; B. F. Gordiets; A. I. Osipov

2001-01-01

25

Fundamental statistical descriptions of plasma turbulence in magnetic fields  

NASA Astrophysics Data System (ADS)

A pedagogical review of the historical development and current status (as of early 2000) of systematic statistical theories of plasma turbulence is undertaken. Emphasis is on conceptual foundations and methodology, not practical applications. Particular attention is paid to equations and formalism appropriate to strongly magnetized, fully ionized plasmas. Extensive reference to the literature on neutral-fluid turbulence is made, but the unique properties and problems of plasmas are emphasized throughout. Discussions are given of quasilinear theory, weak-turbulence theory, resonance-broadening theory, and the clump algorithm. The direct-interaction approximation (DIA) is developed as a central focus of the article, and its relationship to the earlier plasma theories is explained. Various methods of renormalized perturbation theory are described, then unified with the aid of the generating-functional formalism of Martin, Siggia, and Rose. A general expression for the renormalized dielectric function is deduced and discussed in detail. Modern approaches such as decimation and PDF methods are described. Derivations of DIA-based Markovian closures are discussed. The eddy-damped quasinormal Markovian (EDQNM) closure is shown to be nonrealizable in the presence of waves, and a new realizable Markovian closure is presented. The test-field model and a realizable modification thereof are also summarized. Numerical solutions of various closures for some plasma-physics paradigms are reviewed. The variational approach to bounds on transport is developed. Miscellaneous topics include Onsager symmetries for turbulence, the interpretation of entropy balances for both kinetic and fluid descriptions, self-organized criticality, statistical interactions between disparate scales, and the roles of both mean and random shear. Appendices are provided on Fourier transform conventions, dimensional and scaling analysis, the derivations of nonlinear gyrokinetic and gyrofluid equations, stochasticity criteria for quasilinear theory, formal aspects of resonance-broadening theory, Novikov's theorem, the treatment of weak inhomogeneity, the derivation of the Vlasov and gyrokinetic weak-turbulence wave kinetic equation from a fully renormalized description, some features of a code for solving the DIA and related Markovian closures, the details of the solution of the EDQNM closure for a solvable three-wave model, and the notation used in the article.

Krommes, John A.

2002-04-01

26

Nonlinear Kinetic Modeling of Stimulated Raman Scattering in a Plasma  

NASA Astrophysics Data System (ADS)

When a large amplitude plasma wave grows inside a plasma, it strongly modifies the electron distribution function which, in turn, affects the propagation of this wave. The purpose of this paper is to provide a theoretical description of these nonlinear kinetic phenomena when the electrostatic wave results from stimulated Raman scattering (SRS), in order to address the efficiency of this process. In particular, two effects will be discussed in detail, collisionless dissipation, which needs to be described much more generally than by simply resorting to Landau damping, and the impact of the nonlinear variations of the wave frequency on the matching conditions required for the growth of SRS. A very accurate description of these phenomena allows the quantification of Raman reflectivity, which is a key issue for inertial confinement fusion, using an envelope code that runs much faster than those (the so-called kinetic codes) which explicitly calculate the nonlinear variations of the electron distribution function. Comparisons between the outcomes of our envelope modeling and of kinetic simulations will be shown and discussed.

Bénisti, D.

2012-07-01

27

Kinetic description of the far regions of the 3d tails/streamers formed by coupling of the external maxwellian plasma flows with magnetic dipole and toroid at active region  

NASA Astrophysics Data System (ADS)

We consider in terms of the Vlasov Maxwell kinetic approach a classical problem of inductive generation by the solar wind flow of the 3D solar streamer tail structures originating by magnetic flux sources at the Sun magnetoactive regions The input flow is a hot collisionless plasma with maxwellian distribution function We separated magnetic field interacting particles on trapped and untrapped fly by particles Trapped particles partly are parameterized by magnetic flux source configuration The source is approximated by densities of magnetic dipole and magnetic toroid currents distributed on the characteristic scale and characterized by ratio of their integral currents Fly by particles motion we treat via perturbations resulting a linear analytical approach to the flowing plasma Plasma appeared as a result in the problem like resistive and diamagnetic media Non local resistive currents are characterized by anomalous skin scale and diamagnetic currents by magnetic Debye scale Ratio of the diamagnetic currents to the resistive currents is a Quality of the streamer magnetosphere We get integral representation of a selfconsistent global 3D magnetic configuration which is defined via two different kinds of cylindrical harmonics For maxwellian plasma we get a low Quality regime when 3D structure is with resistive currents and only parameter is a specific collisionless magnetic Reynolds number A dipole generates 3D two wire multi magnetic ropes current configuration cylindrical dipole harmonics which is observed in the far down tail

Gubchenko, V. M.; Biernat, H. K.; Rucker, H. O.

28

Fundamental Statistical Descriptions of Plasma Turbulence in Magnetic Fields  

SciTech Connect

A pedagogical review of the historical development and current status (as of early 2000) of systematic statistical theories of plasma turbulence is undertaken. Emphasis is on conceptual foundations and methodology, not practical applications. Particular attention is paid to equations and formalism appropriate to strongly magnetized, fully ionized plasmas. Extensive reference to the literature on neutral-fluid turbulence is made, but the unique properties and problems of plasmas are emphasized throughout. Discussions are given of quasilinear theory, weak-turbulence theory, resonance-broadening theory, and the clump algorithm. Those are developed independently, then shown to be special cases of the direct-interaction approximation (DIA), which provides a central focus for the article. Various methods of renormalized perturbation theory are described, then unified with the aid of the generating-functional formalism of Martin, Siggia, and Rose. A general expression for the renormalized dielectric function is deduced and discussed in detail. Modern approaches such as decimation and PDF methods are described. Derivations of DIA-based Markovian closures are discussed. The eddy-damped quasinormal Markovian closure is shown to be nonrealizable in the presence of waves, and a new realizable Markovian closure is presented. The test-field model and a realizable modification thereof are also summarized. Numerical solutions of various closures for some plasma-physics paradigms are reviewed. The variational approach to bounds on transport is developed. Miscellaneous topics include Onsager symmetries for turbulence, the interpretation of entropy balances for both kinetic and fluid descriptions, self-organized criticality, statistical interactions between disparate scales, and the roles of both mean and random shear. Appendices are provided on Fourier transform conventions, dimensional and scaling analysis, the derivations of nonlinear gyrokinetic and gyrofluid equations, stochasticity criteria for quasilinear theory, formal aspects of resonance-broadening theory, Novikov's theorem, the treatment of weak inhomogeneity, the derivation of the Vlasov weak-turbulence wave kinetic equation from a fully renormalized description, some features of a code for solving the direct-interaction approximation and related Markovian closures, the details of the solution of the EDQNM closure for a solvable three-wave model, and the notation used in the article.

John A. Krommes

2001-02-16

29

Kinetic ion-acoustic solitary waves in collisional plasmas  

NASA Astrophysics Data System (ADS)

The excitation and the propagation of solitary waves of ion-acoustic nature are analyzed by means of kinetic Eulerian simulations, in both collision-free and collisional plasmas, composed of kinetic warm protons and linear Boltzmannian electrons. The process of soliton formation is discussed in detail through the description of the time evolution of the electrostatic potential and of the associated phase space portraits of the proton distribution function. We study the effects of collisions on the propagation of solitary waves, by modeling proton-proton interactions through the one-dimensional nonlinear Dougherty operator, which is a collisional operator of the Fokker-Planck type. We show how, in a case of non-negligible collisionality, short spatial scales in the electrostatic potential are dissipated in time and the phase space structures, observed in the distribution function in absence of collisions, are significantly smoothed out. Finally, by exploiting the analogy between ion-acoustic waves in neutral infinite plasma and Trivelpiece-Gould waves in nonneutral plasmas columns, a recipe to observe solitary structures in nonneutral plasma devices is proposed. Contribution to the Topical Issue "Theory and Applications of the Vlasov Equation", edited by Francesco Pegoraro, Francesco Califano, Giovanni Manfredi and Philip J. Morrison.

Pezzi, Oreste; Valentini, Francesco; Veltri, Pierluigi

2014-05-01

30

Kinetic Modeling of Complex Plasma Equipment  

NASA Astrophysics Data System (ADS)

Kinetics of electrons, ions and neutrals play an important role in industrial plasma systems. These systems are often characterized by complex geometries and require 2D and 3D models of varying resolution for realistic simulations of relevant processes. We will describe hybrid approach to modeling such systems using kinetic models for electrons and hydrodynamic (fluid) models for ion and neutral components. Kinetic modeling of electrons involves numerical solution of the Boltzmann equation or its derivatives. Using two-term spherical harmonics expansion in velocity space, the 6D Boltzmann equation can be reduced to a 4D Fokker-Plank (F-P) equation for the Electron Energy Distribution Function (EEDF), which depends of electron energy and spatial position. This equation can be conveniently solved using total electron energy (kinetic + potential) for a wide range of discharge conditions. Further simplifications are possible in the two extremes. At high gas pressures one can solve local F-P equation for the EEDF as a function of local electric field and plasma composition, and generate Look-Up-Tables (LUTs) for electron transport coefficients and rates of electron induced chemical reactions to be used in fluid models for electrons. The other extreme corresponds to a ``nonlocal approach'' where the EEDF depend solely on the total energy and does to depend explicitly on spatial position. We will describe the architecture of the F-P solver for electrons in the CFD-ACE+ software package and its application to simulations of low-pressure ICP, CCP, and DC discharges, as well as high-pressure micro-plasmas. The peculiarities of the EEDF formation in these systems, and the importance of nonlocal kinetic effects for the formation of striations, electron heating and macro-plasma parameters will be discussed. We will also discuss the limitations of the F-P approach and our current efforts to develop a full Boltzmann solver for simulations of fast (runaway) electrons and nonlocal electromagnetic phenomena in low-pressure RF discharges.

Kolobov, Vladimir

2009-10-01

31

Kinetic theory of sheath formation in solar wind plasma  

Microsoft Academic Search

We present a general self-consistent kinetic theory for plasma sheath formation in solar wind plasma. The theory could be applied to anisotropic, as well as to isotropic collisionless plasma without resorting to any simplifications, limitations, or assumptions, such as the necessary existence of a ‘pre-sheath’ region of ions acceleration to ensure the Bohm criterion. The kinetic framework is first applied

Vladimir Pines; Marianna Zlatkowski; Arnon Chait

2010-01-01

32

Consistent description of kinetic equation with triangle anomaly  

SciTech Connect

We provide a consistent description of the kinetic equation with a triangle anomaly which is compatible with the entropy principle of the second law of thermodynamics and the charge/energy-momentum conservation equations. In general an anomalous source term is necessary to ensure that the equations for the charge and energy-momentum conservation are satisfied and that the correction terms of distribution functions are compatible to these equations. The constraining equations from the entropy principle are derived for the anomaly-induced leading order corrections to the particle distribution functions. The correction terms can be determined for the minimum number of unknown coefficients in one charge and two charge cases by solving the constraining equations.

Pu Shi; Gao Jianhua; Wang Qun [Interdisciplinary Center for Theoretical Study and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

2011-05-01

33

On kinetic dissipation in collisionless turbulent plasmas  

NASA Astrophysics Data System (ADS)

Plasma turbulence is a phenomenon that is present in astrophysical as well as terrestrial plasmas. The earth is embedded in a turbulent plasma, emitting from the sun, called the solar wind. It is important to understand the nature of this plasma in order to understand space weather. A critical unsolved problem is that of the source of dissipation in turbulent plasmas. It is believed to play a central role in the heating of the solar corona which in turn drives the solar wind. The solar wind itself is observed to be highly turbulent and hotter than predicted through adiabatic expansion models. Turbulence and its associated dissipation have been studied extensively through the use of MHD models. However, the solar wind and large regions of the solar corona have very low collisionality, which calls into question the use of simple viscosity and resistivity in most MHD models. A kinetic treatment is needed for a better understanding of turbulent dissipation. This thesis studies the dissipation of collisionless turbulence using direct numerical hybrid simulations of turbulent plasmas. Hybrid simulations use kinetic ions and fluid electrons. Having full kinetic ion physics, the dissipation in these simulations at the ion scales is self consistent and requires no assumptions. We study decaying as well as quasi steady state systems (driven magnetically). Initial studies of the Orszag-Tang vortex [Orszag, JFM, 1979] (which is an initial condition that quickly generates decaying strong turbulence) showed preferential perpendicular heating of protons (with T_perp /T_|| > 1). An energy budget analysis showed that in the turbulent regime, almost all the dissipation occurs through magnetic interactions. We study the energy budget of waves using the k - o spectra (energy in the wavenumber-frequency space). The k - o spectra of this study and subsequent studies of driven turbulent plasmas do not show any significant power in the linear wave modes of the system. This suggests that in the strong 2D limit, contrary to the conventional belief, waves do not appear to play an important role in the heating of plasma. We also study the onset of turbulence and heating of plasma as a function of the driving frequency. We find that the onset of turbulence has a critical dependence on the relative size of the driving time scales and the nonlinear time scales of the system. The driving time scale has to be longer than the nonlinear time of the system or the intrinsic nonlinear time associated with the driving function. For smaller driving time scales (or higher driving frequencies) we do not generate turbulence and do not heat the plasma. This setup has a resemblance to the generation of turbulence and heating of the plasma in the solar corona. The driving frequency corresponds to the frequency of driving because of the foot point motions of the field lines. Our results are consistent with Parker's picture for heating the corona (e.g. Parker, Planets Earth and Space, 2001). The time scale of the foot points has to be longer than the nonlinear time of the system in order to generate turbulence and heat the corona.

Parashar, Tulasi Nandan

34

Kinetic Theory of Dawson Plasma Sheet Model  

NASA Astrophysics Data System (ADS)

A kinetic theory of one-dimensional plasma sheet model (Dawson model) is developed. The Vlasov equation, the Landau equation, and the Balescu--Lenard equation corresponding to this model are derived. For the Vlasov equation, it is shown that the linearized Vlasov equation exhibits a typical behavior of plasmas as in the three-dimensional space. The Landau collision term and the Balescu--Lenard collision term are identically zero. The fact of the vanishing collision term agrees with the behavior of generic one-dimesional systems. In an approximation that the system is in a thermal bath, the derived Landau equation and Balescu--Lenard equation are transformed into the Fokker--Planck equations. Some physical quantities such as thermal conductivity, relaxation rate, etc., are estimated. A discussion on physical meaning of these results, in particular, the zero collision terms, will be given.

Sano, Mitsusada M.; Kitahara, Kazuo

2011-08-01

35

Detailed and reduced chemical-kinetic descriptions for hydrocarbon combustion  

NASA Astrophysics Data System (ADS)

Numerical and theoretical studies of autoignition processes of fuels such as propane are in need of realistic simplified chemical-kinetic descriptions that retain the essential features of the detailed descriptions. These descriptions should be computationally feasible and cost-effective. Such descriptions are useful for investigating ignition processes that occur, for example, in homogeneous-charge compression-ignition engines, for studying the structures and dynamics of detonations and in fields such as multi-dimensional Computational Fluid Dynamics (CFD). Reduced chemistry has previously been developed successfully for a number of other hydrocarbon fuels, however, propane has not been considered in this manner. This work focuses on the fuels of propane, as well propene, allene and propyne, for several reasons. The ignition properties of propane resemble those of other higher hydrocarbons but are different from those of the lower hydrocarbons (e.g. ethylene and acetylene). Propane, therefore, may be the smallest hydrocarbon that is representative of higher hydrocarbons in ignition and detonation processes. Since the overall activation energy and ignition times for propane are similar to those of other higher hydrocarbons, including liquid fuels that are suitable for many applications, propane has been used as a model fuel for several numerical and experimental studies. The reason for studying elementary chemistry of propene and C3H4 (allene or propyne) is that during the combustion process, propane breaks down to propene and C3H4 before proceeding to products. Similarly, propene combustion includes C3H4 chemistry. In studying propane combustion, it is therefore necessary to understand the underlying combustion chemistry of propene as well as C3H 4. The first part of this thesis focuses on obtaining and testing a detailed chemical-kinetic description for autoignition of propane, propene and C 3H4, by comparing predictions obtained with this detailed mechanism against numerous experimental data available from shock-tube studies and flame-speed measurements. To keep the detailed mechanism small, attention is restricted to pressures below about 100 atm, temperatures above about 1000 K and equivalence ratios less than about 3. Based on this detailed chemistry description, short (or skeletal) mechanisms are then obtained for each of the three fuels by eliminating reactions that are unimportant for the autoignition process under conditions presented above. This was achieved by utilizing tools such as sensitivity and reaction pathway analyses. Two distinct methodologies were then used in order to obtain a reduced mechanism for autoignition from the short mechanisms. A Systematic Reduction approach is first taken that involves introducing steady-state approximations to as many species as analytically possible. To avoid resorting to numerical methods, the analysis for obtaining ignition times for heptane, presented by Peters and co-workers is followed in order to obtain a rough estimate for an expression of propane ignition time. The results from this expression are then compared to the ignition times obtained computationally with the detailed mechanism. The second method is an Empirical Approach in which chemistry is not derived formally, but rather postulated empirically on the basis of experimental, computational and theoretical observations. As a result, generalized reduced mechanisms are proposed for autoignition of propane, propene and C3H 4. Expressions for ignition times obtained via this empirical approach are compared to the computational results obtained from the detailed mechanism.

Petrova, Maria V.

36

Magnetized plasma kinetic theory. I. Derivation of the kinetic equation for a uniform magnetized plasma  

Microsoft Academic Search

A kinetic equation for a multi-species plasma in an external uniform magnetic field is derived from the BBGKY hierarchy of equations. The equation generalizes the equation of Rostoker (1960), which assumes that the distribution function is independent of the azimuthal angle, and all previous results can be derived from it. An additional advantage is that the collision integral is obtained

M H A Hassan; C J H Watson

1977-01-01

37

BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas  

NASA Astrophysics Data System (ADS)

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

Porkolab, Miklos

1998-11-01

38

Comet giacobini-zinner: plasma description.  

PubMed

A strong interaction between the solar wind and comet Giacobini-Zinner was observed oh 11 September 1985 with the Los Alamos plasma electron experiment on the International Cometary Explorer (ICE) spacecraft. As ICE approached an intercept point 7800 kilometers behind the nucleus from the south and receded to the north, upstream phenomena due to the comet were observed. Periods of enhanced electron heat flux from the comet as well as almost continuous electron density fluctuations were measured. These effects are related to the strong electron heating observed in the cometary interaction region and to cometary ion pickup by the solar wind, respectively. No evidence for a conventional bow shock was found as ICE entered and exited the regions of strongest interaction of the solar wind with the cometary environment. The outer extent of this strong interaction zone was a transition region in which the solar wind plasma was heated, compressed, and slowed. Inside the inner boundary of the transition region was a sheath that enclosed a cold intermediate coma. In the transition region and sheath, small-scale enhancements in density were observed. These density spikes may be due to an instability associated with cometary ion pickup or to the passage of ICE through cometary ray structures. In the center of the cold intermediate coma a narrow, high-density core of plasma, presumably the developing plasma tail was found. In some ways this tail can be compared to the plasma sheet in Earth's magnetotail and to the current sheet in the tail at Venus. This type of configuration is expected in the double-lobe magnetic topology detected at the comet, possibly caused by the theoretically expected draping of the interplanetary magnetic field around its ionosphere. PMID:17792144

Bame, S J; Anderson, R C; Asbridge, J R; Baker, D N; Feldman, W C; Fuselier, S A; Gosling, J T; McComas, D J; Thomsen, M F; Young, D T; Zwickl, R D

1986-04-18

39

Phase Transition in Dusty Plasmas: A Microphysical Description  

Microsoft Academic Search

Dust grains immersed in plasma discharges acquire a large negative charge and settle into a dust cloud at the edge of the sheath. In this region, the plasma ions stream toward the electrode at a velocity u approx. cs=(Te\\/mi)1\\/2. Experimentally at sufficiently high gas pressure P, the random kinetic energy of the grains is damped by gas friction, and the

Glenn Joyce; Gurudas Ganguli; Martin Lampe

2002-01-01

40

New description of Io's cold plasma torus  

NASA Astrophysics Data System (ADS)

Despite more than 25 years of study of the Io plasma torus, its generation, dynamics, and even its spatial structure are still poorly understood, especially in the case of the inner, cold region of the torus. To remedy this lack, we analyzed ground-based coronagraphic images of the torus in S+ 6371 Å emission. We derived cold torus properties by modeling and removing these images' inherent line-of-sight integration and atmospheric blurring, using new deconvolution techniques, obtaining high-spatial-resolution estimates of the three-dimensional (3-D) S+ distributions. From these 3-D distributions, we discovered that the cold torus is washer-shaped, with a roughly constant vertical thickness ?0.25 Jovian radius (RJ), and a radial width that varies from 0.6 to 0.9 RJ. The cold torus is separated by a 0.1-0.2 RJ-wide low-density region, or "gap," from the "ribbon" region which lies just outside it. The small, approximately constant washer height implies an ion parallel temperature (T?) of ˜3 eV, compared with a ribbon T? that varies from about 20 to 50 eV as a function of Jovian magnetic longitude (?III). The washer has a distinct inner edge, not seen before, whose jovicentric distance varies with ?III so as to create the variable cold torus width. Thus this inner edge is concentric with neither Jupiter nor the rest of the torus. We also confirm the existence of a tilt between the midplanes of the ribbon and cold torus, with an orientation that cannot be produced by the magnetic mirror force acting on ion temperature anisotropy. The structure and composition of the gap and cold torus are best explained by a model in which a small amount of warm S+ plasma diffuses inwards while radiatively cooling. While still warm, its distribution over a large scale height keeps its density small, forming the gap. After sufficient cooling, it collapses to the centrifugal equator, where its higher density and continued inward diffusion make it more visible as the cold torus washer. However, its low electron temperature (probably ? T?) must be kept from further decline by a hitherto-unsuspected energy source that powers the observed visible wavelength radiation from the cold torus and fluctuates on timescales less than the plasma diffusion time. The formation of the abrupt cold torus inner edge might indicate the loss there of either this energy source or the plasma itself.

Herbert, Floyd; Schneider, Nicholas M.; Dessler, A. J.

2008-01-01

41

The use of variational principles in plasma kinetic-theory  

Microsoft Academic Search

A variational method is applied to a plasma kinetic equation which contains Balescu-Lenard, Boltzmann and Landau collision integrals. The method enables one to account for electron-electron collisions and plasma nonideality. It was applied to a partially ionized cesium plasma.

G. A. Pavlov; E. E. Son

1976-01-01

42

A kinetic description for the destabilization process of protein foams  

Microsoft Academic Search

In the present work a new kinetic model to describe the protein foam destabilization was determined by the conductimetric method. The second order, two term kinetic of foam destabilization by liquid drainage proposed in the current study was more adequate for describing the destabilization process than those presented until present, showing the existence of two simultaneous mechanisms of foam destabilization

L. A. Panizzolo; L. E. Mussio; M. C. Añón

2010-01-01

43

Simulations of Magnetic Reconnection - Kinetic Mechanisms Underlying the Fluid Description of Ions  

NASA Technical Reports Server (NTRS)

Because of its ability to transfer the energy stored in magnetic field together with the breaking of the flux freezing constraint, magnetic reconnection is considered as one of the most important phenomena in plasma physics. When it happens in a collision less environment such as the terrestrial magnetosphere, it should a priori be modelled with in the framework of kinetic physics. The evidence of kinetic features has incidentally for a long time, been shown by researchers with the help of both numerical simulations and satellite observations. However, most of our understanding of the process comes from the more intuitive fluid interpretation with simple closure hypothesis which do not include kinetic effects. To what extent are these two separate descriptions of the same phenomenon related? What is the role of kinetic effects in the averaged/fluid dynamics of reconnection? This thesis addresses these questions for the proton population in the particular case of anti parallel merging with the help of 2D Hybrid simulations. We show that one can not assume, as is usually done, that the acceleration of the proton flow is only due to the Laplace force. Our results show, for symmetric and asymmetric connection, the importance of the pressure force, opposed to the electric one on the separatrices, in the decoupling region. In the symmetric case, we emphasize the kinetic origin of this force by analyzing the proton distribution functions and explain their structure by studying the underlying particle dynamics. Protons, as individual particles, are shown to bounce in the electric potential well created by the Hall effect. The spatial divergence of this well results in a mixing in phase space responsible for the observed structure of the pressure tensor. A detailed energy budget analysis confirms the role of the pressure force for the acceleration; but, contrary to what is sometimes assumed, it also reveals that the major part of the incoming Poynting flux is transferred to the thermal energy flux rather than to the convective kinetic energy flux, although the latter is generally supposed dominant. In the symmetric case, we propose the pressure tensor to be an additional proxy of the ion decoupling region in satellite data and verify this suggestion by studying a reconnection event encountered by the Cluster spacecrafts. Finally, the last part of this thesis is devoted to the study of the kinetic structure of asymmetric tangential current sheets where connection can develop. This theoretical part consists in finding a steady state solution to the Vlasov-Maxwell system for the protons in such a configuration. We present the theory and its first confrontation to numerical tests.

Aunai, icolas; Belmont, Gerard; Smets, Roch

2012-01-01

44

Solitary kinetic Alfvén waves in dusty plasmas  

NASA Astrophysics Data System (ADS)

Solitary kinetic Alfvén waves in dusty plasmas are studied by considering the dust charge variation. The effect of the dust charge-to-mass ratio on the soliton solution is discussed. The Sagdeev potential is derived analytically with constant dust charge and then calculated numerically by taking the dust charge variation into account. We show that the dust charge-to-mass ratio plays an important role in the soliton properties. The soliton solutions are comprised of two branches. One branch is sub-Alfvénic and the soliton velocity is obviously smaller than the Alfvén speed. The other branch is super-Alfvénic and the soliton velocity is very close to or greater than the Alfvén speed. Both compressive and rarefactive solitons can exist. For the sub-Alfvénic branch, the rarefactive soliton is bell-shaped and it is much narrower than the compressive one. However, for the super-Alfvénic branch, the compressive soliton is bell-shaped and narrower, and the rarefactive one is broadened. When the charge-to-mass ratio of the dust grains is sufficiently high, the width of the rarefactive soliton, in the super-Alfvénic branch, will broaden extremely and a electron depletion will be observed. It is also shown that the bell-shaped soliton can transition to a cusped structure when the velocity is sufficiently high.

Li, Yang-Fang; Wu, D. J.; Morfill, G. E.

2008-08-01

45

Fully implicit kinetic modelling of collisional plasmas  

SciTech Connect

This dissertation describes a numerical technique, Matrix-Free Newton Krylov, for solving a simplified Vlasov-Fokker-Planck equation. This method is both deterministic and fully implicit, and may not have been a viable option before current developments in numerical methods. Results are presented that indicate the efficiency of the Matrix-Free Newton Krylov method for these fully-coupled, nonlinear integro-differential equations. The use and requirement for advanced differencing is also shown. To this end, implementations of Chang-Cooper differencing and flux limited Quadratic Upstream Interpolation for Convective Kinematics (QUICK) are presented. Results are given for a fully kinetic ion-electron problem with a self consistent electric field calculated from the ion and electron distribution functions. This numerical method, including advanced differencing, provides accurate solutions, which quickly converge on workstation class machines. It is demonstrated that efficient steady-state solutions can be achieved to the non-linear integro-differential equation, obtaining quadratic convergence, without incurring the large memory requirements of an integral operator. Model problems are presented which simulate plasma impinging on a plate with both high and low neutral particle recycling typical of a divertor in a Tokamak device. These model problems demonstrate the performance of the new solution method.

Mousseau, V.A.

1996-05-01

46

Kinetic theory of sheath formation in solar wind plasma  

NASA Astrophysics Data System (ADS)

We present a general self-consistent kinetic theory for plasma sheath formation in solar wind plasma. The theory could be applied to anisotropic, as well as to isotropic collisionless plasma without resorting to any simplifications, limitations, or assumptions, such as the necessary existence of a 'pre-sheath' region of ions acceleration to ensure the Bohm criterion. The kinetic framework is first applied to sheath formation around an arbitrary oriented planar absorbing surface, charged by solar wind anisotropic plasma, under the condition of negligible photoelectric effect. We then make use of our kinetic approach for the plane geometry in isotropic collisionless plasma, as a particular case of a planar electrode orientation parallel to plasma streaming velocity, also analyzing the sheath structure around spherical and cylindrical absorbing electrodes submerged in isotropic collisionless plasma. Obtained results demonstrate principal differences in spatial charge distributions in sheath regions between spherical or cylindrical electrodes of large size and an unbound planar surface submerged in isotropic plasma. In the case of a planar electrode, we directly compare results obtained in our kinetic and hydrodynamic theories and conventional hydrodynamic theory of plasma sheath formation. The outcome from the present study have direct implications to the analysis of plasma sheath structure and associated distribution in space of charged dust grains, which is relevant to the moon exploration near the optical terminator region or in shadowed craters in the moon.

Pines, Vladimir; Zlatkowski, Marianna; Chait, Arnon

2010-10-01

47

Hamiltonian field description of two-dimensional vortex fluids and guiding center plasmas  

SciTech Connect

The equations that describe the motion of two-dimensional vortex fluids and guiding center plasmas are shown to possess underlying field Hamiltonian structure. A Poisson bracket which is given in terms of the vorticity, the physical although noncanonical dynamical variable, casts these equations into Heisenberg form. The Hamiltonian density is the kinetic energy density of the fluid. The well-known conserved quantities are seen to be in involution with respect to this Poisson bracket. Expanding the vorticity in terms of a Fourier-Dirac series transforms the field description given here into the usual canonical equations for discrete vortex motion. A Clebsch potential representation of the vorticity transforms the noncanonical field description into a canonical description.

Morrison, P.J.

1981-03-01

48

Good relationship between saliva cotinine kinetics and plasma cotinine kinetics after smoking one cigarette.  

PubMed

This study investigated the relationship between plasma and saliva cotinine kinetics after smoking one cigarette and the relationship between cotinine kinetics and estimated nicotine intake, which was calculated as mouth level exposure (MLE) of nicotine, from smoking two test cigarettes with different nicotine yields. This study was conducted in 16 healthy adult Japanese smokers, who did not have null nor reduced-activity alleles of CYP2A6, with a quasi-randomized crossover design of smoking a low-tar cigarette or a high-tar cigarette. Saliva cotinine showed similar concentration profiles to plasma cotinine, and all of the calculated pharmacokinetic parameters of cotinine showed the same values in plasma and saliva. The Cmax and AUC of cotinine showed almost the same dose-responsiveness to the estimated MLE of nicotine between plasma and saliva, but the tmax and t1/2 of cotinine were not affected by the estimated MLE of nicotine in either plasma or saliva. The results show that saliva cotinine kinetics reflects plasma cotinine kinetics, and measurement of saliva cotinine concentration gives the same information as plasma cotinine on the nicotine intake. Thus, saliva cotinine would be a good and less-invasive exposure marker of cigarette smoke, reflecting the plasma cotinine concentration and kinetics. PMID:23933006

Yuki, Dai; Kikuchi, Akira; Miura, Naoki; Kakehi, Aoi; Onozawa, Masahiro

2013-11-01

49

Kinetic Modeling of Plasma Methane Conversion Using Gliding Arc  

Microsoft Academic Search

Plasma methane (CH4) conversion in gliding arc discharge was examined. The result data of experiments regarding the performance of gliding arc discharge were presented in this paper. A simulation which is consisted some chemical kinetic mechanisms has been provided to analyze and describe the plasma process. The effect of total gas flow rate and input frequency refers to power consumption

Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

50

Fully Kinetic Simulations of Dense Plasma Focus Z-Pinch  

NASA Astrophysics Data System (ADS)

Dense plasma focus (DPF) z pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We now have, for the first time, demonstrated a capability to model these plasmas fully kinetically, allowing us to simulate the pinch process at the particle scale. We present here the results of the initial kinetic simulations, which reproduce experimental neutron yields and high energy (MeV) beams for the first time. We present a comparison between fully kinetic, hybrid (kinetic ions/fluid electrons), and fluid simulations. Only fully kinetic simulations predict MeV-energy ions and experimental neutron yields. A frequency analysis of the electric field in the fully kinetic simulation shows plasma fluctuations near the lower hybrid frequency. This suggests the presence of lower hybrid drift instability, a possible contributor to anomalous resistivity in the plasma. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) at LLNL.

Schmidt, Andrea; Tang, Vincent; Welch, Dale

2012-10-01

51

Pedestal Fueling Simulations with a Coupled Kinetic-kinetic Plasma-neutral Transport Code  

SciTech Connect

A Monte Carlo neutral transport routine, based on DEGAS2, has been coupled to the guiding center ion-electron-neutral neoclassical PIC code XGC0 to provide a realistic treatment of neutral atoms and molecules in the tokamak edge plasma. The DEGAS2 routine allows detailed atomic physics and plasma-material interaction processes to be incorporated into these simulations. The spatial pro le of the neutral particle source used in the DEGAS2 routine is determined from the uxes of XGC0 ions to the material surfaces. The kinetic-kinetic plasma-neutral transport capability is demonstrated with example pedestal fueling simulations.

D.P. Stotler, C.S. Chang, S.H. Ku, J. Lang and G.Y. Park

2012-08-29

52

Theory of spatially non-symmetric kinetic equilibria for collisionless plasmas  

SciTech Connect

The problem posed by the possible existence/non-existence of spatially non-symmetric kinetic equilibria has remained unsolved in plasma theory. For collisionless magnetized plasmas, this involves the construction of stationary solutions of the Vlasov-Maxwell equations. In this paper, the issue is addressed for non-relativistic plasmas both in astrophysical and laboratory contexts. The treatment is based on a Lagrangian variational description of single-particle dynamics. Starting point is a non-perturbative formulation of gyrokinetic theory, which allows one to construct 'a posteriori' with prescribed order of accuracy an asymptotic representation for the magnetic moment. In terms of the relevant particle adiabatic invariants generalized bi-Maxwellian equilibria are proved to exist. These are shown to recover, under suitable assumptions, a Chapman-Enskog form which permits an analytical treatment of the corresponding fluid moments. In particular, the constrained posed by the Poisson and the Ampere equations are analyzed, both for quasi-neutral and non-neutral plasmas. The conditions of existence of the corresponding non-symmetric kinetic equilibria are investigated. As a notable feature, both astrophysical and laboratory plasmas are shown to exhibit, under suitable conditions, a kinetic dynamo, whereby the equilibrium magnetic field can be self-generated by the equilibrium plasma currents.

Cremaschini, Claudio [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy); Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezrucovo nam.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)

2013-01-15

53

Kinetic theory and simulation of multi-species plasmas in tokamaks excited with ICRF microwaves  

SciTech Connect

This paper presents a description of a bounce-averaged Fokker-Planck quasilinear model for the kinetic description of tokamak plasmas. The non-linear collision and quasilinear resonant diffusion operators are represented in a form conducive to numerical solution with specific attention to the treatment of the boundary layer separating trapped and passing orbit regions of velocity space. The numerical techniques employed are detailed in so far as they constitute significant departure from those used in the conventional uniform magnetic field case. Examples are given to illustrate the combined effects of collisional and resonant diffusion.

Kerbel, G.D.; McCoy, M.G.

1984-12-21

54

Kinetic Modifications to MHD Phenomena in Toroidal Plasmas  

SciTech Connect

Particle kinetic effects involving small spatial and fast temporal scales can strongly affect MHD phenomena and the long time behavior of plasmas. In particular, kinetic effects such as finite ion gyroradii, trapped particle dynamics, and wave-particle resonances have been shown to greatly modify the stability of MHD modes. Here, the kinetic effects of trapped electron dynamics and finite ion gyroradii are shown to have a large stabilizing effect on kinetic ballooning modes in low aspect ratio toroidal plasmas such as NSTX [National Spherical Torus Experiment]. We also present the analysis of Toroidicity-induced Alfven Eigenmodes (TAEs) destabilized by fast neutral-beam injected ions in NSTX experiments and TAE stability in ITER due to alpha-particles and MeV negatively charged neutral beam injected ions.

C.Z. Cheng; N.N. Gorelenkov; G.J. Kramer; E. Fredrickson

2004-09-03

55

Plasma outflow from a corrugated trap in the kinetic regime  

SciTech Connect

The problem of stationary plasma outflow from an open corrugated trap in the kinetic regime is considered with allowance for pair collisions in the framework of a kinetic equation with the Landau collision integral. The distribution function is studied in the limit of small-scale corrugation and a large mirror ratio. In considering a single corrugation cell, a correction for the distribution function is calculated analytically. An equation describing variations of the distribution function along the system is derived and used to study the problem of plasma outflow into vacuum.

Skovorodin, D. I.; Beklemishev, A. D. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

2012-03-15

56

Kinetic description of electron beams in the solar chromosphere  

NASA Technical Reports Server (NTRS)

We formulate the relativistic Fokker-Plank equation for a beam of accelerated electrons interacting with a partially ionized plasma. In our derivation we conserved those terms contributing to velocity diffusion and found that this effect cannot be neglected a priori. We compute the terms accounting for elastic and inelastic collisions with neutral hydrogen and helium. Collisions with neutral hydrogen are found to be dominant throughout the chromosphere, except at the uppermost layers close to the transition region. As an application, we compute the loss of energy and momentum for a power-law beam impinging on the solar chromosphere, for a particular case in which the Fokker-Planck equation can be integrated analytically. We find that most of the beam energy is deposited in a relatively thin region of the chromosphere, a result which is largely insensitive to the theoretical method employed to compute the energy deposition rate.

Gomez, Daniel O.; Mauas, Pablo J.

1992-01-01

57

Kinetic Processes and Intermittent Turbulence in the Solar Wind Plasma  

NASA Astrophysics Data System (ADS)

A connection between intermittent turbulence and kinetic processes in the solar wind is presented using measurements from the Wind spacecraft. Temperature anisotropy is found to be concentrated near coherent structures, such as current sheets, which are non-uniformly distributed in space. Hence, these structures are preferentially found in plasma that is unstable to temperature anisotropy-driven mirror and firehose instabilities. The coherent structures heat the plasma, resulting in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is insufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.

Osman, K.; Matthaeus, W. H.; Hnat, B.; Chapman, S. C.

2012-12-01

58

Kinetic simulations of ultra-intense laser plasma interactions  

Microsoft Academic Search

Kinetic simulations are used to investigate the interaction of an ultra-intense, small spot-size laser beam with a preformed plasma. the beam is sufficiently intense to drive the electrons relativistically and to impart a pressure in excess of hundreds of Mbars to the plasma. Key features of the interaction include generation of electrons and inward-directed ions with energies in the Mev

W. L. Kruer; S. C. Wilks

1992-01-01

59

Kinetic simulations of ultra-intense laser plasma interactions  

Microsoft Academic Search

Kinetic simulations are used to investigate the interaction of an ultra-intense, small spot-size laser beam with a preformed plasma. The beam is sufficiently intense to drive the electrons relativistically and to impart a pressure in excess of hundreds of Mbars to the plasma. Key features of the interaction include generation of electrons and inward-directed ions with energies in the Mev

W. L. Kruer; S. C. Wilks

1992-01-01

60

Dynamic and kinetic plasma processes at Saturn  

NASA Astrophysics Data System (ADS)

At Saturn is a complex, dynamic system where plasma processes are governed by the interactions between plasmas and the moons and neutral cloud that orbit the planet. Each of those bodies has a different interaction with their surroundings and affects the system in different ways. We study these interactions using data from the Cassini magnetometer. In this thesis, we examine these interactions in order to learn about both the bodies and the plasma with which they interact. Two of Saturn's icy moons on which we focus are Enceladus and Iapetus. The first orbits at a distance of 3.95 Saturn radii (R S ) and is in the densest part of the neutral cloud; the second is 60 R S from the planet and spends much of its orbit outside of the magnetosphere. The plume at Enceladus' southern pole is known to be a major source of neutral cloud orbiting Saturn and modeling suggests that lapetus may also be a neutral source. The plasma environments of these two moons are very different, so we use different approach es to study them. For Iapetus, we use magnetometer and plasma wave observations made during Cassini's single close flyby, made when the moon was in the solar wind. Both instruments find perturbations that do not resemble solar wind structures but are well-correlated with the moon. After examining the possibilities, we conclude that Iapetus is not a significant source of neutrals. To perturb the solar wind as observed, we believe that the most geophysically-probable conclusion is a conducting layer, such as an ocean, beneath the moon's surface. At Enceladus, we examine the moon's control of the neutral cloud structure and its effect on the magnetospheric plasma. To probe variation in the neutral cloud, we use ion cyclotron waves as a diagnostic of the local neutral density. We find that Enceladus strongly controls the cloud's azimuthal structure between 3.7 and 4.5 R S . To study the moon's effect on the plasma, we use downstream observations of the moon's wake. The interaction between Enceladus' plume and the magnetospheric plasma slows the bulk plasma flow and causes a perturbation in the magnetic field. This perturbation convects downstream to where Cassini observes it. We find that Enceladus' wake persists until at least 120 degrees downstream and the magnetic perturbation is strong enough to produce significant energy deposition into the ionosphere. We discuss these conclusions with respect to the null observation of auroral emissions associated with the moon.

Leisner, Jared Scott

61

Nonlocal, Kinetic Stimulated Raman Scattering in Nonuniform Plasmas  

NASA Astrophysics Data System (ADS)

Excitation of continuously phase-locked (autoresonant) plasma waves in a nonuniform plasma via stimulated Raman backscattering is analyzed with a focus on the kinetic regime (k?D˜1). The dominant nonlinear effect in this regime is that of resonant particles and the plasma wave excitation is a nonlocal process involving formation and transport of the electron phase space holes. Whitham's averaged variational principle is applied in studying the coupled plasma, laser pump and seed waves dynamics. A flat-top electron velocity distribution is used as the simplest model allowing a variational formulation within the water bag theory. The corresponding Lagrangian, averaged over the fast phase variable, yields evolution equations for the slow field variables. The adiabatic multiple water bag extension of the theory for application to autoresonant plasma waves in nonuniform plasmas with more realistic initial distributions is also discussed. Numerical solutions of the system of slow variational equations are compared with Vlasov-Ampere simulations.

Khain, Pavel; Friedland, Lazar; Shagalov, Arkadiy; Wurtele, Jonathan

2012-10-01

62

Kinetics of complex plasma with liquid droplets  

SciTech Connect

This paper provides a theoretical basis for the reduction of electron density by spray of water (or other liquids) in hot plasma. This phenomenon has been observed in a hypersonic flight experiment for relief of radio black out, caused by high ionization in the plasma sheath of a hypersonic vehicle, re-entering the atmosphere. The analysis incorporates a rather little known phenomenon for de-charging of the droplets, viz., evaporation of ions from the surface and includes the charge balance on the droplets and number cum energy balance of electrons, ions, and neutral molecules; the energy balance of the evaporating droplets has also been taken into account. The analysis has been applied to a realistic situation and the transient variations of the charge and radius of water droplets, and other plasma parameters have been obtained and discussed. The analysis through made in the context of water droplets is applicable to all liquids.

Misra, Shikha; Sodha, M. S. [Centre of Energy Studies, Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India)] [Centre of Energy Studies, Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India); Mishra, S. K. [Institute for Plasma Research (IPR), Gandhinagar 382428 (India)] [Institute for Plasma Research (IPR), Gandhinagar 382428 (India)

2013-12-15

63

Phase Transition in Dusty Plasmas: A Microphysical Description  

NASA Technical Reports Server (NTRS)

Dust grains immersed in plasma discharges acquire a large negative charge and settle into a dust cloud at the edge of the sheath. In this region, the plasma ions stream toward the electrode at a velocity u approx. cs=(T(sub e)/m(sub i))(exp 1/2). Experimentally at sufficiently high gas pressure P, the random kinetic energy of the grains is damped by gas friction, and the grains are strongly coupled and self-organize into a crystalline configuration. For lower pressures despite the dissipation of grain kinetic energy to gas friction, the dust grains reach a steady-state kinetic temperature T(sub d) which is much larger than the temperature of any other component in the plasma. T(sub d) is so large that the dust acts like a fluid. We have used the dynamically shielded dust (DSD) model to simulate these physical processes. We find that the known experimental features are nicely reproduced in the simulations, and that additional features are revealed. In the figure we plot the variation of T(sub d) as P is continuously varied in a DSD code run. A marked difference is evident between the critical pressure P(sub m) for the melting transition as P is decreased, and the critical pressure P(sub c) for the condensation transition as P is increased. For P(sub m) is less than P is less than P(sub c), mixed phase states are seen. This hysteresis occurs because the instability which triggers melting is different from the instability that heats the dust in the fluid phase and inhibits freezing. At low pressure, the dust is subject to a two-stream instability with the ions. This instability is responsible for the high temperature of the dust at low pressure. The basic physics underlying the melting transition has been elucidated in a series of papers. We are developing a first-principles analytic approach to the melting transition, which embodies the same physics that is present in the DSD code.

Joyce, Glenn; Ganguli, Gurudas; Lampe, Martin

2002-01-01

64

Application of a consistent kinetic equation to an inhomogeneous plasma  

Microsoft Academic Search

A consistent kinetic model is developed for investigating wave ; propagation in a two-componeit fully ionized, inhomogeneous, low-pressure plasma ; with collisions. A Gross-Krook-type model is developed with arbitrary parameters ; determined by the method of Morse STAPhys. Fluids 7, 20l 2 (1964)!. The ; collision terms of the model satisfy all conservation requirements to a ; consistent order. A

Ezra D. Heitowit; Richard L. Liboff

1973-01-01

65

An energy integral and variational principle for plasma kinetic modes  

Microsoft Academic Search

An energy principle is extended to include kinetic processes, finite gyroradius effects and wave-particle interactions, in electromagnetic instabilities in a toroidal plasma. The present arguments are based on the energy integrals which are derived from the eigenmode equations for electromagnetic perturbations. Inclusion of the finite gyroradius effects in the energy integral shows that this integral can be used for eigenmode

S. I. Itoh; K. Itoh; Y. Terashima

1981-01-01

66

An energy integral and variational principle for plasma kinetic modes  

Microsoft Academic Search

An energy principle is extended to include kinetic processes, finite gyroradius effects and wave-particle interactions, in electromagnetic instabilities in a toroidal plasma. The present arguments are based on the energy integrals which are derived from the eigenmode equations for electromagnetic perturbations. First, the finite gyroradius effects are included in the energy integral and it is shown that this integral can

Sanae-Inoue Itoh; Kimitaka Itoh; Yoshinosuke Terashima

1982-01-01

67

Kinetic theory of weak turbulence in plasmas.  

PubMed

From the nonlinear Vlasov equation, a nonlinear turbulence scattering term is found to describe stochastic dissipation on a time scale longer than the turbulence correlation time. The evolution of the plasma distribution is determined by the well-understood unperturbed motion of charged particles, with the effects of the fluctuating part of fields described by the turbulence scattering term. In the present framework, one can identify various important physics, from the linear and quasilinear regimes to the nonlinear regime, in particular, the connections between the widely used Kadomtsev-Pogutse equation [B. B. Kadomtsev and O. P. Pogutse, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1970), pp. 368-387] and the Frieman-Chen equation [Frieman and Chen, Phys. Fluids 25, 502 (1982)]. The nonlinear scattering term indicates the Onsager symmetry relation of turbulent transport and a nonlinear frequency or k spectrum shift of a resonantly excited wave. PMID:23848785

Wang, Shaojie

2013-06-01

68

Kinetic theory of nonlinear transport phenomena in complex plasmas  

SciTech Connect

In contrast to the prevalent use of the phenomenological theory of transport phenomena, a number of transport properties of complex plasmas have been evaluated by using appropriate expressions, available from the kinetic theory, which are based on Boltzmann's transfer equation; in particular, the energy dependence of the electron collision frequency has been taken into account. Following the recent trend, the number and energy balance of all the constituents of the complex plasma and the charge balance on the particles is accounted for; the Ohmic loss has also been included in the energy balance of the electrons. The charging kinetics for the complex plasma comprising of uniformly dispersed dust particles, characterized by (i) uniform size and (ii) the Mathis, Rumpl, and Nordsieck power law of size distribution has been developed. Using appropriate expressions for the transport parameters based on the kinetic theory, the system of equations has been solved to investigate the parametric dependence of the complex plasma transport properties on the applied electric field and other plasma parameters; the results are graphically illustrated.

Mishra, S. K. [Institute for Plasma Research (IPR), Gandhinagar 382428 (India); Sodha, M. S. [Centre for Energy Studies (CES), Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India)

2013-03-15

69

Plasma kinetic processes in a strong d.c. magnetic field  

NASA Technical Reports Server (NTRS)

Recent results in the kinetic theory of a strongly magnetized plasma are surveyed. Emphasis is on the electrostatic guiding-center plasma in two dimensions, in both the fluid and 'charged rod' descriptions. The basic kinetic description of the plasma is in terms of the statistically-distributed Fourier coefficients associated with the velocity and 'enstrophy' (charge density) fields. It is a universal tendency in such media for enstrophy to flow to shorter wavelengths but for energy to flow to longer wavelengths. A consequence of the energy flow to longer wavelengths is the generation of long-range order in the form of macroscopic vortices. These kinds of structure have been called 'convection cells' and can be extraordinarily efficient in transporting particles transverse to a magnetic field. The tendency to vortex formation can be disrupted by collisions between particles. Modifications of the Fokker-Planck equation for a plasma produced by a strong dc magnetic field are considered in both two and three dimensions.

Montgomery, D.

1976-01-01

70

Hamiltonian and Lagrangian approaches to hybrid kinetic-fluid plasmas  

NASA Astrophysics Data System (ADS)

The development of multiscale multiphysics models is required in different contexts of plasma physics, from fusion theory to space plasmas. Indeed, plasmas are often found to consist of two different species: a cold (fluid) species and a hot (kinetic) component. Several modeling efforts over the last two decades culminated in the formulation of two main types of hybrid kinetic-fluid models: current-coupling schemes (CCS') and pressure-coupling schemes (PCS'). Although CCS' conserve energy exactly, PCS' (used in simulations) require certain approximations that break exact energy conservation. In this work, we formulate new PCS models, whose exact energy conservation is guaranteed by an appropriate Hamiltonian (and Lagrangian) structure. A comparison of Hamiltonian and non-Hamiltonian models is then presented, in terms of linear and non-linear stability.

Tronci, Cesare; Morrison, P. J.; Tassi, Emanuele

2012-10-01

71

Toward a Fully Kinetic Theory of Turbulence in Magnetized Plasmas  

SciTech Connect

This paper outlines the present status of the kinetic theory of turbulence in magnetized plasmas as being developed by the present author. The systematic program to formulate the theory of turbulence starting from the Vlasov-Klimontovich formalism began with the works by pioneers of modern plasma physics in the 1960s and 1970s. However, early efforts adopted the heuristic semi-classical method instead of the statistical mechanical formulation, which is necessary for a quantitative analysis. Recently, the present author picked up where the early pioneers left, and began to reformulate the kinetic turbulence theory of turbulence in magnetized plasmas from statistical mechanical formalism. This paper is a brief outline of the progress to date.

Yoon, Peter H. [IPST, University of Maryland, College Park, MTL, Inc., 330 Pleasant Street, Belmont, MA, SSR, Kyung Hee University (Korea, Republic of)

2010-12-30

72

Complexity reduction of collisional-radiative kinetics for atomic plasma  

SciTech Connect

Thermal non-equilibrium processes in partially ionized plasmas can be most accurately modeled by collisional-radiative kinetics. This level of detail is required for an accurate prediction of the plasma. However, the resultant system of equations can be prohibitively large, making multi-dimensional and unsteady simulations of non-equilibrium radiating plasma particularly challenging. In this paper, we present a scheme for model reduction of the collisional-radiative kinetics, by combining energy levels into groups and deriving the corresponding macroscopic rates for all transitions. Although level-grouping is a standard approach to this type of problem, we provide here a mechanism for achieving higher-order accuracy by accounting for the level distribution within a group. The accuracy and benefits of the scheme are demonstrated for the generic case of atomic hydrogen by comparison with the complete solution of the master rate equations and other methods.

Le, Hai P. [ERC Inc., Edwards AFB, California 93524 (United States)] [ERC Inc., Edwards AFB, California 93524 (United States); Karagozian, Ann R. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States)] [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States); Cambier, Jean-Luc [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)] [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)

2013-12-15

73

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

NASA Technical Reports Server (NTRS)

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

Roth, J. R.

1976-01-01

74

Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis Bumpy Torus plasma  

NASA Technical Reports Server (NTRS)

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

Roth, J. R.

1976-01-01

75

Chemical Cycle Kinetics: Removing the Limitation of Linearity of a Non-equilibrium Thermodynamic Description  

NASA Astrophysics Data System (ADS)

Chemical cycle kinetics is customarily analyzed by means of the law of mass action which describes how the concentrations of the substances vary with time. The connection of this approach with non-equilibrium thermodynamics (NET) has traditionally been restricted to the linear domain close to equilibrium in which the reaction rates are linear functions of the affinities. We show, by a pertinent formulation of the concept of local equilibrium in the mesoscopic description along the reaction coordinates, that the connection between kinetic and thermodynamic approaches is deeper than thought and holds in the nonlinear domain far from equilibrium, for higher values of the affinity. This new perspective indicates how to overcome the inherent limitation of classical NET in treating cyclic reactions, providing a description of closed and open cycles operating far from equilibrium, in accordance with thermodynamic principles. We propose that the new set of equations are tested and used for data reduction in chemical reaction kinetics.

Rubi, J. M.; Bedeaux, D.; Kjelstrup, S.; Pagonabarraga, I.

2013-07-01

76

Non Equilbrium Vibrational Kinetics in Expanding Plasma Flows  

SciTech Connect

The supersonic expansion of a plasma is a system of interest for aerospace applications, ranging from propulsion to hypersonic wind tunnels. Under these conditions the plasma shows significant departures from chemical and thermal equilibrium, similarly to post-discharge conditions. The multitemperature description is not adequate because the internal level distributions show tails overpopulated with respect to a Boltzmann distribution. The state-to-state approach has to be used, including the interaction with free electrons which follow non-maxwellian distributions.

Colonna, Gianpiero [CNR-IMIP, sede di Bari, Via Amendola 122/D, 70126, Bari (Italy)

2008-12-31

77

Kinetic equilibria of relativistic collisionless plasmas in the presence of non-stationary electromagnetic fields  

NASA Astrophysics Data System (ADS)

The kinetic description of relativistic plasmas in the presence of time-varying and spatially non-uniform electromagnetic (EM) fields is a fundamental theoretical issue both in astrophysics and plasma physics. This refers, in particular, to the treatment of collisionless and strongly-magnetized plasmas in the presence of intense radiation sources. In this paper, the problem is investigated in the framework of a covariant gyrokinetic treatment for Vlasov-Maxwell equilibria. The existence of a new class of kinetic equilibria is pointed out, which occur for spatially-symmetric systems. These equilibria are shown to exist in the presence of non-uniform background EM fields and curved space-time. In the non-relativistic limit, this feature permits the determination of kinetic equilibria even for plasmas in which particle energy is not conserved due to the occurrence of explicitly time-dependent EM fields. Finally, absolute stability criteria are established which apply in the case of infinitesimal symmetric perturbations that can be either externally or internally produced.

Cremaschini, Claudio; Tessarotto, Massimo; Stuchlík, Zden?k

2014-03-01

78

Kinetic theory of weak turbulence in plasmas  

NASA Astrophysics Data System (ADS)

From the nonlinear Vlasov equation, a nonlinear turbulence scattering term is found to describe stochastic dissipation on a time scale longer than the turbulence correlation time. The evolution of the plasma distribution is determined by the well-understood unperturbed motion of charged particles, with the effects of the fluctuating part of fields described by the turbulence scattering term. In the present framework, one can identify various important physics, from the linear and quasilinear regimes to the nonlinear regime, in particular, the connections between the widely used Kadomtsev-Pogutse equation [B. B. Kadomtsev and O. P. Pogutse, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1970), pp. 368-387] and the Frieman-Chen equation [Frieman and Chen, Phys. FluidsPFLDAS0031-917110.1063/1.863762 25, 502 (1982)]. The nonlinear scattering term indicates the Onsager symmetry relation of turbulent transport and a nonlinear frequency or k spectrum shift of a resonantly excited wave.

Wang, Shaojie

2013-06-01

79

Merging for Complex Particle Kinetic modeling of multiple plasma beams (inter-penetrating flows) Merging for Complex Particle Kinetic modeling of multiple plasma beams (inter-penetrating flows)  

NASA Astrophysics Data System (ADS)

We suggest a merging procedure for the Complex Particle Kinetic (CPK) model in case of inter-penetrating flow (multiple plasma beams). Each CPK macro-particle includes a Maxwellian distribution in velocity and Gaussian distribution in space with internal dynamics (see [Hewett, 2003], for details). It is assumed that an arbitrary distribution of real particles can be represented by such a superposition in phase space (moving--finite----element approach). The CPK method allows us to provide a global simulation of the complex plasma objects on the Hall-MHD (fluid) scale (aggressive merging) with automatic incorporation of the kinetic/particle description of the particle-wave processes (aggressive fragmentation) where it is necessary. The CPK approximation works well for ions, electrons, dust grains and neutral components. This code was tested in the simulations for the study of the interaction of the plasma flow with comets and Io's atmosphere. In this report we examine the standard (PIC) and the CPK methods in the case of the particle acceleration by shock surfing.

Lipatov, Alexander

2008-03-01

80

Collisionless energy-independent kinetic equilibria in axisymmetric magnetized plasmas.  

PubMed

The proof of existence of Vlasov-Maxwell equilibria which do not exhibit a functional dependence in terms of the single-particle energy is established. The theory deals with the kinetic treatment of multispecies axisymmetric magnetized plasmas, with particular reference to plasma systems which are slowly time varying. Aside from collisionless laboratory plasmas, the theory concerns important aspects of astrophysical scenarios, such as accretion-disk and coronal plasmas arising in the gravitational field of compact objects. Qualitative properties of the solution are investigated by making use of a perturbative kinetic theory. These concern the realization of the equilibrium kinetic distribution functions in terms of generalized Gaussian distributions and the constraints imposed by the Maxwell equations. These equilibria are shown to be generally non-neutral and characterized by the absence of the Debye screening effect. As a further application, the stability properties of these equilibria with respect to axisymmetric electromagnetic perturbations are addressed. This permits us to establish absolute stability criteria holding in such a case. PMID:24125369

Cremaschini, Claudio; Stuchlík, Zden?k; Tessarotto, Massimo

2013-09-01

81

Kinetic theory of quasi-stationary collisionless axisymmetric plasmas in the presence of strong rotation phenomena  

SciTech Connect

The problem of formulating a kinetic treatment for quasi-stationary collisionless plasmas in axisymmetric systems subject to the possibly independent presence of local strong velocity-shear and supersonic rotation velocities is posed. The theory is developed in the framework of the Vlasov-Maxwell description for multi-species non-relativistic plasmas. Applications to astrophysical accretion discs arising around compact objects and to plasmas in laboratory devices are considered. Explicit solutions for the equilibrium kinetic distribution function (KDF) are constructed based on the identification of the relevant particle adiabatic invariants. These are shown to be expressed in terms of generalized non-isotropic Gaussian distributions. A suitable perturbative theory is then developed which allows for the treatment of non-uniform strong velocity-shear/supersonic plasmas. This yields a series representation for the equilibrium KDF in which the leading-order term depends on both a finite set of fluid fields as well as on the gradients of an appropriate rotational frequency. Constitutive equations for the fluid number density, flow velocity, and pressure tensor are explicitly calculated. As a notable outcome, the discovery of a new mechanism for generating temperature and pressure anisotropies is pointed out, which represents a characteristic feature of plasmas considered here. This is shown to arise as a consequence of the canonical momentum conservation and to contribute to the occurrence of temperature anisotropy in combination with the adiabatic conservation of the particle magnetic moment. The physical relevance of the result and the implications of the kinetic solution for the self-generation of quasi-stationary electrostatic and magnetic fields through a kinetic dynamo are discussed.

Cremaschini, Claudio; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)] [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)

2013-05-15

82

Merging for Complex Particle Kinetic modeling of multiple plasma beams (inter-penetrating flows)  

NASA Astrophysics Data System (ADS)

We suggest a merging procedure for the Complex Particle Kinetic (CPK) model in case of inter-penetrating flow (multiple plasma beams). Each CPK macro-particle includes a Maxwellian distribution in velocity and Gaussian distribution in space with internal dynamics (see [Hewett, 2003], for details). It is assumed that an arbitrary distribution of real particles can be represented by such a superposition in phase space (moving--finite----element approach) at least as well as could be done with the standard particle in cell (PIC)/Monte Carlo (MC) delta functions and their associated ``shape factors". The CPK method allows us to provide a global simulation of the complex plasma objects on the Hall-MHD (fluid) scale (aggressive merging) with automatic incorporation of the kinetic/particle description of the particle-wave processes (aggressive fragmentation) where it is necessary. The CPK approximation works well for ions, electrons, dust grains and neutral components. This code was tested in the simulations for the study of the interaction of the plasma flow with comets and Io's atmosphere. In this report we examine the standard (PIC) and the CPK methods in the case of the particle acceleration by shock surfing. The plasma dynamics is described by a standard (particle-ion-- fluid- electron) hybrid model. While a particle-mesh method is well enough verified approach, the CPK model seems to be a good approach in case of multiscale simulation which includes multiple subdomains with various particle/fluid plasma behavior.

Lipatov, Alexander

2008-03-01

83

Solitary Kinetic Alfvén Waves in a Low-? Dusty Plasma  

NASA Astrophysics Data System (ADS)

The nonlinear kinetic Alfvén waves in a low-? (0 ll ? ll 1) dusty plasma have been investigated with the fluid model of three-component plasma. The nonlinear equation governing the perturbation density of electrons in a form of the energy integral has been derived. In the approximation of small amplitude, the soliton solution for the perturbation density of electrons is found, and the characteristics of solitons in different range of plasma parameters is studied numerically. The results show that the density dip or hump can be formed in a dusty plasma for different ranges of parameters, the amplitude of density dip is enhanced and the amplitude of density hump is reduced with increasing dust grain content.

Yin-Hua, Chen; Wei, Lu

2000-02-01

84

Kinetic Ballooning/Interchange Instability in a Bent Plasma Sheet  

NASA Astrophysics Data System (ADS)

We use THEMIS and GOES observations to investigate the plasma sheet evolution on 28 February 2008 between 6:50 and 7:50 UT, when there developed strong magnetic field oscillations with period of 100 s. Using multi-spacecraft analysis of the plasma sheet observations and an empirical plasma sheet model, we determine both the large-scale evolution of the plasma sheet and the properties of the oscillations. We found that the oscillations exhibited signatures of kinetic ballooning/interchange instability fingers that developed in a bent current sheet. The interchange oscillations had a sausage structure, propagated duskward at a velocity of about 100 km/s, and were associated with periodical radial electron flows. We suggest that the observed negative gradient of the ZGSM magnetic field component (dBZ/dX) was a free energy source for the kinetic ballooning/interchange instability. Tens of minutes later a fast elongation of ballooning/interchange fingers was detected between 6 and 16 RE downtail with the legnth-to-width ratio exceeding 20. The finger elongation ended with signatures of reconnection in an embedded current sheet near the bending point. These observations suggest a complex interplay between the midtail and near-Earth plasma sheet dynamics, involving localized fluctuations both in cross-tail and radial directions before current sheet reconnection.

Panov, E. V.; Nakamura, R.; Baumjohann, W.; Kubyshkina, M. G.; Artemyev, A. V.; Sergeev, V. A.; Petrukovich, A. A.; Angelopoulos, V.; Glassmeier, K.-H.; McFadden, J. P.; Larson, D.

2012-04-01

85

Kinetic ballooning/interchange instability in a bent plasma sheet  

NASA Astrophysics Data System (ADS)

We use Time History of Events and Macroscale Interactions during Substorms (THEMIS) and GOES observations to investigate the plasma sheet evolution on 28 February 2008 between 6:50 and 7:50 UT, when there developed strong magnetic field oscillations with periods of 100 s. Using multispacecraft analysis of the plasma sheet observations and an empirical plasma sheet model, we determine both the large-scale evolution of the plasma sheet and the properties of the oscillations. We found that the oscillations exhibited signatures of kinetic ballooning/interchange instability fingers that developed in a bent current sheet. The interchange oscillations had a sausage structure, propagated duskward at a velocity of about 100 km/s, and were associated with fast radial electron flows. We suggest that the observed negative gradient of the ZGSM magnetic field component (?BZ/?X) was a free energy source for the kinetic ballooning/interchange instability. Tens of minutes later a fast elongation of ballooning/interchange fingers was detected between 6 and 16 RE downtail with the length-to-width ratio exceeding 20. The finger elongation ended with signatures of reconnection in an embedded current sheet near the bending point. These observations suggest a complex interplay between the midtail and near-Earth plasma sheet dynamics, involving localized fluctuations in both cross-tail and radial directions before current sheet reconnection.

Panov, E. V.; Nakamura, R.; Baumjohann, W.; Kubyshkina, M. G.; Artemyev, A. V.; Sergeev, V. A.; Petrukovich, A. A.; Angelopoulos, V.; Glassmeier, K.-H.; McFadden, J. P.; Larson, D.

2012-06-01

86

Kinetic models for the VASIMR thruster helicon plasma source  

NASA Astrophysics Data System (ADS)

Helicon gas discharge [1] is widely used by industry because of its remarkable efficiency [2]. High energy and fuel efficiencies make it very attractive for space electrical propulsion applications. For example, helicon plasma source is used in the high specific impulse VASIMR [3] plasma thruster, including experimental prototypes VX-3 and upgraded VX-10 [4] configurations, which operate with hydrogen (deuterium) and helium plasmas. We have developed a set of models for the VASIMR helicon discharge. Firstly, we use zero-dimensional energy and mass balance equations to characterize partially ionized gas condition/composition. Next, we couple it to one-dimensional hybrid model [6] for gas flow in the quartz tube of the helicon. We compare hybrid model results to a purely kinetic simulation of propellant flow in gas feed + helicon source subsystem. Some of the experimental data [3-4] are explained. Lastly, we discuss full-scale kinetic modeling of coupled gas and plasmas [5-6] in the helicon discharge. [1] M.A.Lieberman, A.J.Lihtenberg, 'Principles of ..', Wiley, 1994; [2] F.F.Chen, Plas. Phys. Contr. Fus. 33, 339, 1991; [3] F.Chang-Diaz et al, Bull. APS 45 (7) 129, 2000; [4] J.Squire et al., Bull. APS 45 (7) 130, 2000; [5] O.Batishchev et al, J. Plasma Phys. 61, part II, 347, 1999; [6] O.Batishchev, K.Molvig, AIAA technical paper 2000-3754, -14p, 2001.

Batishchev, Oleg; Molvig, Kim

2001-10-01

87

Species separation and kinetic effects in collisional plasma shocksa)  

NASA Astrophysics Data System (ADS)

The properties of collisional shock waves propagating in uniform plasmas are studied with ion-kinetic calculations, in both slab and spherical geometry and for the case of one and two ion species. Despite the presence of an electric field at the shock front—and in contrast to the case where an interface is initially present [C. Bellei et al., Phys. Plasmas 20, 044702 (2013)]—essentially no ion reflection at the shock front is observed due to collisions, with a probability of reflection ?10-4 for the cases presented. A kinetic two-ion-species spherical convergent shock is studied in detail and compared against an average-species calculation, confirming effects of species separation and differential heating of the ion species at the shock front. The effect of different ion temperatures on the DT and D3He fusion reactivity is discussed in the fluid limit and is estimated to be moderately important.

Bellei, C.; Rinderknecht, H.; Zylstra, A.; Rosenberg, M.; Sio, H.; Li, C. K.; Petrasso, R.; Wilks, S. C.; Amendt, P. A.

2014-05-01

88

Transition of electron kinetics in weakly magnetized inductively coupled plasmas  

SciTech Connect

Transition of the electron kinetics from nonlocal to local regime was studied in weakly magnetized solenoidal inductively coupled plasma from the measurement of the electron energy probability function (EEPF). Without DC magnetic field, the discharge property was governed by nonlocal electron kinetics at low gas pressure. The electron temperatures were almost same in radial position, and the EEPFs in total electron energy scale were radially coincided. However, when the DC magnetic field was applied, radial non-coincidence of the EEPFs in total electron energy scale was observed. The electrons were cooled at the discharge center where the electron heating is absent, while the electron temperature was rarely changed at the discharge boundary with the magnetic field. These changes show the transition from nonlocal to local electron kinetics and the transition is occurred when the electron gyration diameter was smaller than the skin depth. The nonlocal to local transition point almost coincided with the calculation results by using nonlocal parameter and collision parameter.

Kim, Jin-Yong; Lee, Hyo-Chang; Kim, Young-Do; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)] [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Young-Cheol [Department of Nanoscale Semiconductor Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)] [Department of Nanoscale Semiconductor Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2013-10-15

89

On bias of kinetic temperature measurements in complex plasmas  

NASA Astrophysics Data System (ADS)

The kinetic temperature in complex plasmas is often measured using particle tracking velocimetry. Here, we introduce a criterion which minimizes the probability of faulty tracking of particles with normally distributed random displacements in consecutive frames. Faulty particle tracking results in a measurement bias of the deduced velocity distribution function and hence the deduced kinetic temperature. For particles with a normal velocity distribution function, mistracking biases the obtained velocity distribution function towards small velocities at the expense of large velocities, i.e., the inferred velocity distribution is more peaked and its tail is less pronounced. The kinetic temperature is therefore systematically underestimated in measurements. We give a prescription to mitigate this type of error.

Kantor, M.; Moseev, D.; Salewski, M.

2014-02-01

90

Analysis of Plasma Antioxidant Capacity by Competition Kinetics  

Microsoft Academic Search

A competition kinetics procedure for measuring plasma antioxidant capacity is described. This procedure is based on the “crocin bleaching test” (Bors, W., et al. Biochim. Biophys. Acta 796:312–319; 1984) modified for analyzing the antioxidant capacity of complex mixtures (Tubaro, F., et al. J. Am. Oil Chem. Soc. 73:173–179; 1996). The information produced by this test is similar to that of

Franco Tubaro; Andrea Ghiselli; Pierpaolo Rapuzzi; Matilde Maiorino; Fulvio Ursini

1998-01-01

91

Alcuronium kinetics and plasma concentration–effect relationship  

Microsoft Academic Search

The kinetics and dynamics of the neuromuscular blocker alcuronium were investigated in 12 surgical patients who received bolus and infusion regimens. In six patients the duration of the infusion was sufficiently long so that a steady-state alcuronium plasma concentration was reached (mean SD, 0.80 ± 0.23 µg\\/ml). In the remaining six patients a steady state was not reached but the

Judith S Walker; Colin Shanks; Kenneth F Brown

1983-01-01

92

Plasma transport induced by kinetic Alfven wave turbulence  

SciTech Connect

At the Earth's magnetopause that separates the hot-tenuous magnetospheric plasma from the cold dense solar wind plasma, often seen is a boundary layer where plasmas of both origins coexist. Plasma diffusions of various forms have been considered as the cause of this plasma mixing. Here, we investigate the plasma transport induced by wave-particle interaction in kinetic Alfven wave (KAW) turbulence, which is one of the candidate processes. We clarify that the physical origin of the KAW-induced cross-field diffusion is the drift motions of those particles that are in Cerenkov resonance with the wave: E Multiplication-Sign B-like drift that emerges in the presence of non-zero parallel electric field component and grad-B drift due to compressional magnetic fluctuations. We find that KAW turbulence, which has a spectral breakpoint at which an MHD inertial range transits to a dissipation range, causes selective transport for particles whose parallel velocities are specified by the local Alfven velocity and the parallel phase velocity at the spectral breakpoint. This finding leads us to propose a new data analysis method for identifying whether or not a mixed plasma in the boundary layer is a consequence of KAW-induced transport across the magnetopause. The method refers to the velocity space distribution function data obtained by a spacecraft that performs in situ observations and, in principle, is applicable to currently available dataset such as that provided by the NASA's THEMIS mission.

Izutsu, T. [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Hasegawa, H.; Fujimoto, M. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Nakamura, T. K. M. [X-Computational Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2012-10-15

93

Application of Nonlocal Electron Kinetics to Plasma Technologies  

NASA Astrophysics Data System (ADS)

Partially ionized plasmas are typically in a highly non-equilibrium thermodynamic state: the electrons are not in equilibrium with the neutral particle species or the ions, and the electrons are also not in equilibrium within their own ensemble, which results in a significant departure of the electron velocity distribution function (EVDF) from a Maxwellian. These non-equilibrium conditions provide considerable freedom to choose optimal plasma parameters for applications, which make gas-discharge plasmas remarkable tools for a variety of plasma applications, including plasma processing, discharge lighting, plasma propulsion, particle beam sources, and nanotechnology. Significant progress in understanding the formation of non-Maxwellian EVDF in the self-consistent electric fields has been one of the major achievements in the low-temperature plasmas during the last decade. This progress was made possible by a synergy between full-scale particle-in-cell simulations, analytical models, and experiments. Specific examples include rf discharges, dc discharges with auxiliary electrodes, Hall thruster discharges. In each example, nonlocal kinetic effects are identified as the main mechanisms responsible for the surprising degree of discharge self-organization. These phenomena include: explosive generation of cold electrons with rf power increase in low-pressure rf discharges; abrupt changes in discharge structure with increased bias voltage on a third electrode in a dc discharge with hot cathode; absence of a steady-state regime in Hall thruster discharges with intense secondary electron emission due to coupling of the sheath properties and the EVDF.

Kaganovich, Igor D.

2011-11-01

94

Mixed particle-grid method for kinetic simulation of plasmas  

NASA Astrophysics Data System (ADS)

Latest development of a hybrid PIC-Vlasov method [1] for the kinetic modeling of collisionless plasmas is presented. Such plasma system is described by Poisson equation for self-consistent electric potential, and by set of Vlasov equations for electron and ionic plasma species. Traditional approach uses either PIC or Vlasov method. PIC suffers from high statistical noise, while Vlasov shows high numerical diffusion. New hybrid method combines best features of the two methods, while suppressing both numerical noise and diffusion. A comparison of various methods will be given for a few model problems raging from beam-plasma system [2] to plasma-wall interaction. First results of coupling new particle-mesh method with adaptive RRC method, which utilizes adaptive grid refinement and coarsening will be reported. [1] O.Batishchev , Proc. 17th Int. Conf. on Num. Sim. of Plasmas, Banff, Canada, May 2000, p.24; [2] O.Batishchev et al., Bull. Aps 45 (7) DPP/ICPP 2000 Meeting, Quebec City, Canada, Bull. APS 45 (7) 72, 2000; [3] A.Batishcheva and O.Batishchev, Proc. 17th Int. Conf. on Num. Sim. of Plasmas, p.29, 2000.

Batishchev, Oleg

2001-06-01

95

Consistent Description of Kinetics and Hydrodynamics of Weakly Nonequilibrium Processes in Simple Liquids  

NASA Astrophysics Data System (ADS)

The generalized transport equations for a consistent description of kinetic and hydrodynamic processes in dense gases and liquids are considered and the intrinsic structure of the generalized transport kernels for these equations is established. As a result, we show how to obtain the transport equation of molecular hydrodynamics in our approach. We also investigate the spectrum of collective modes for a system with the model potential of interaction presented as a sum of the hard sphere and long-range parts.

Markiv, B.; Omelyan, I.; Tokarchuk, M.

2014-04-01

96

Consistent Description of Kinetics and Hydrodynamics of Weakly Nonequilibrium Processes in Simple Liquids  

NASA Astrophysics Data System (ADS)

The generalized transport equations for a consistent description of kinetic and hydrodynamic processes in dense gases and liquids are considered and the intrinsic structure of the generalized transport kernels for these equations is established. As a result, we show how to obtain the transport equation of molecular hydrodynamics in our approach. We also investigate the spectrum of collective modes for a system with the model potential of interaction presented as a sum of the hard sphere and long-range parts.

Markiv, B.; Omelyan, I.; Tokarchuk, M.

2014-06-01

97

Kinetic properties of shear Alfvén eigenmodes in tokamak plasmas  

NASA Astrophysics Data System (ADS)

This work reports on numerical calculations concerning the kinetic properties of low-n, low-m toroidal Alfvén eigenmodes (TAEs) in tokamak plasmas for fusion relevant parameters. The self-consistent and nonperturbative code LIGKA [Ph. Lauber, Ph.D. thesis, TU München (2003)] is employed. It is based on a linear gyrokinetic model consisting of the quasineutrality equation and the moment equation for the perturbed current. It is shown that in a certain limit the underlying equations of LIGKA can be simplified to the equations known as the ``reduced kinetic model.'' An antenna-like version of LIGKA allows one to systematically find all shear-Alfvén-type modes in a given frequency interval, such as kinetic TAEs (KTAEs) and kinetically modified TAEs. The coupling to the kinetic Alfvén wave (KAW) is found in the form of continuum damping and radiative damping. For the cases examined here, no mode conversion in the centre is found. In the case of a large nonideal parameter, damping rates around 0.5%-1% are found, close to experimental measurements.

Lauber, Ph.; Günter, S.; Pinches, S. D.

2005-12-01

98

Hybrid Kinetic-Fluid Electromagnetic Simulations of Imploding High Energy Density Plasmas for IFE  

NASA Astrophysics Data System (ADS)

A new simulation technique is being developed to study high current and moderate density-radius product (?R) z-pinch plasmas relevant to Inertial Fusion Energy (IFE). Fully kinetic, collisional, and electromagnetic simulations of the time evolution of up to 40-MA current (deuterium and DT) z-pinches, but with relatively low ?R, have yielded new insights into the mechanisms of neutron production.ootnotetextD. R. Welch, et al., Phys. Rev. Lett. 103, 255002 (2009). At fusion relevant conditions (?R > 0.01 gm/cm^2), however, this technique requires a prohibitively large number of cells and particles. A new hybrid implicit technique has been developed that accurately describes high-density and magnetized imploding plasmas. The technique adapts a recently published algorithm,ootnotetextT. C. Genoni, et al., Open Plasma Phys. J. 3, 36 (2010). that enables accurate descriptions of highly magnetized particle orbits, to high density plasmas and also makes use of an improved kinetic particle remap technique. We will discuss the new technique, stable range of operation, and application to an IFE relevant z-pinch design at 60 MA.

Welch, Dale; Rose, Dave; Thoma, Carsten; Genoni, Thomas; Bruner, Nichelle; Clark, Robert; Stygar, William; Leeper, Ramon

2011-11-01

99

Kinetic simulations of ultra-intense laser plasma interactions  

SciTech Connect

Kinetic simulations are used to investigate the interaction of an ultra-intense, small spot-size laser beam with a preformed plasma. the beam is sufficiently intense to drive the electrons relativistically and to impart a pressure in excess of hundreds of Mbars to the plasma. Key features of the interaction include generation of electrons and inward-directed ions with energies in the Mev range and strong hole boring which enhances the absorption. The simulations also show self-generated magnetic fields of order 10{sup 8} Gauss, a Rayleigh-Taylor like instability of the light-plasma interface, as well as self-focusing of the laser beam and strong Raman backscatter.

Kruer, W.L.; Wilks, S.C.

1992-06-01

100

Kinetic simulations of ultra-intense laser plasma interactions  

SciTech Connect

Kinetic simulations are used to investigate the interaction of an ultra-intense, small spot-size laser beam with a preformed plasma. the beam is sufficiently intense to drive the electrons relativistically and to impart a pressure in excess of hundreds of Mbars to the plasma. Key features of the interaction include generation of electrons and inward-directed ions with energies in the Mev range and strong hole boring which enhances the absorption. The simulations also show self-generated magnetic fields of order 10[sup 8] Gauss, a Rayleigh-Taylor like instability of the light-plasma interface, as well as self-focusing of the laser beam and strong Raman backscatter.

Kruer, W.L.; Wilks, S.C.

1992-06-01

101

Can kinetic plasma simulation and MHD talk to each other?  

NASA Astrophysics Data System (ADS)

Kinetic simulations show faster tearing mode growth and higher amplitude saturation with electron temperature anisotropy. Implicit simulations in 3D show the lower-hybrid drift instability (LHDI) generates anisotropy and that spontaneous, small-scale tearing evolves into rapid, large-scale reconnection. These results for idealized problems on very small scales need to be tested on larger systems with more realistic boundary conditions, for which we need new methods. We extend implicit simulation to magnetohydrodynamic (MHD) scales by adding a simple but self-consistent collision model to Celeste. An input parameter switches Celeste from a kinetic simulation to Hall-MHD, and can be given different values in different regions so that MHD and kinetic regions interact, flux conservation conditions are rigorously satisfied, and the two plasma populations mix on ion time scales. In 2D, we simulate the LHDI with uniform collisionality, and it grows and saturates normally at low collision rates, but with reduced temperature anisotropy. We model a finite-width current sheet in the direction of current flow, as in the magnetotail, using adjacent collisional and collision-less regions. The resistance to current flow in the collisional region induces an out-of-plane return current flow in the collision-less region. To study embedding a kinetic region in a larger MHD domain, we introduce a collisional region along the magnetic field direction, which can cause localized reconnection unless done carefully. We characterize the transparency of the boundary between kinetic and MHD regions to the propagation of waves and plasma flow, and evaluate the adequacy of our simple collision model.

Brackbill, J. U.; Lapenta, G.

2007-12-01

102

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.

103

Kinetic Properties of Alfvén Modes in Tokamak Plasmas  

NASA Astrophysics Data System (ADS)

The ability to predict the stability of fast-particle-driven Alfvén eigenmodes in burning fusion plasmas requires a detailed understanding of the dissipative mechanisms that damp these modes. In order to address this question, the linear gyro-kinetic, electromagnetic code LIGKA is employed to investigate their behaviour in realistic tokamak geometry. The eigenvalue formulation of LIGKA allows to calculate self-consistently the coupling of large-scaled MHD modes to the gyroradius scale-length kinetic Alfvén waves. Therefore, the properties of the kineticly modified TAE mode in or near the gap (KTAE, radiative damping or `tunnelling') and its coupling to the continuum close to the edge can be analysed numerically. In addition, an antenna-like version of LIGKA allows for a frequency scan, analogous to an external antenna. The model and the implementation of LIGKA were recently extended in order to capture the coupling of the shear Alfvén waves to the sound waves. This coupling becomes important for the investigation of kinetic effects on the low-frequency phase of cascade modes, where e.g. geodesic acoustic effects play a significant role.

Lauber, Ph.; Günter, S.; Brüdgam, M.; Könies, A.; Pinches, S. D.

2006-11-01

104

A two-temperature kinetic model of SF6 plasma  

NASA Astrophysics Data System (ADS)

Studying the influence of thermal departures from equilibrium in SF6 circuit-breakers, we develop a two-temperature kinetic model to calculate the composition. Such a kinetic approach has not been adopted until now for SF6 plasma because of the complexity of chemical processes. Our model takes into account the collisional mechanisms responsible for the creation and disappearance of atoms and molecules through 19 species linked by 66 chemical reactions. To solve the conservation equations, the model uses the direct rates of reactions, that mainly proceed from the literature, and reverse rates, that are computed by two-temperature micro-reversibility laws. Thus, we point out the importance of the choice of the expression of Saha law, comparing Potapov and van de Sanden formulations of this law. We then discuss the impact of thermal departures from equilibrium on plasma composition, on `mean path' of molecules before dissociation in the plasma, and on the reactions that govern the disappearance of electrons.

Girard, R.; Belhaouari, J. B.; Gonzalez, J. J.; Gleizes, A.

1999-11-01

105

Magnetized plasma kinetic theory. II. Derivation of Rosenbluth potentials for a uniform magnetized plasma  

Microsoft Academic Search

For pt.I see ibid., vol.19, p.237 (1977). It is shown that the kinetic equation for a plasma situated in a magnetic field, of a strength such that the ion Larmor radius is larger than the electron Debye length, has the form of a Fokker Planck equation in which the diffusion and friction coefficients can be derived from 'Rosenbluth potentials' in

D E Baldwin; C J H Watson

1977-01-01

106

Role of plasma activation in the kinetics of CNT growth in PECVD process  

Microsoft Academic Search

The work presents kinetic modeling of the effect of acceleration for the growth kinetics of carbon nanotubes by hydrocarbon gas mixture modification with plasma discharge. The plasma activation creates active species in hydrocarbon gas mixture, which can easily adsorb and dissociate on the catalyst surface. So plasma treatment of the gas mixture in the CVD process allows to increase the

Irina Lebedeva; Alexey Gavrikov; Alexey Baranov; Maxim Belov; Andrey Knizhnik; Boris Potapkin; Timothy Sommerer

2009-01-01

107

Kinetic Effects in Tokamak Scrape-off Layer Plasmas  

NASA Astrophysics Data System (ADS)

Transport modeling for the tokamak scrape-off layer is typically done using fluid theory which assumes short Coulomb collisional mean-free paths along the magnetic field, ?, in comparison with the connection length, L. This assumption is often violated for typical discharge parameters, especially above the thermal energy where most of the heat flux is carried; here ? ? ?^2 with ? being the energy. Thus, the tail of the distribution function can strongly depart from Maxwellian owing to nonlocal effects, modifying plasma transport, impurity radiation, and plasma-neutral gas interactions. These nonlocal effects become particularly pronounced for detached plasma conditions which are characterized by sharp gradients of plasma parameters along the magnetic field. These problems are addressed by developing a 1D-2V fully kinetic collisional time-dependent PIC code, W1, and its parallel-computer version, PW1. Both are used here to study divertor plasma detachment. New developments are presented that include a cross-field spatial dimension to assess the competition between radial and parallel transport in determining the SOL particle distribution functions, as well as impurity radiation and volume recombination. Short time-scale transport effects for ELMs in the tokamak edge are modeled also, and incomplete equilibration of the electron distribution function is observed. A comparison is made with a Fokker-Planck code ALLA and with experimental results. Results on the influence of kinetic effects on probe measurement interpretation, impurity radiation and parallel heat conductivity due to non-Maxwellian features in the SOL plasmas are presented and compared with ad hoc heat flux-limit models. Additional topics discussed are the sheath potential increase caused by hot electrons and plasma flow stagnation in the recycling region due to strong plasma-neutral particle interaction. In collaboration with X.Q. Xu, J.A. Byers, T.D. Rognlien, R.H. Cohen, S.I. Krasheninnikov, A.A. Batishcheva, P.J. Catto, M.M. Shoucri, and D.J. Sigmar. Work supported by the U.S.A. DoE Grants DE-FG02-88-ER-53263 at Lodestar, DE-FG02-91-ER-54109 at MIT, and W-7405-ENG-48 at LLNL.

Batishchev, O. V.

1996-11-01

108

The Plasma Interaction Experiment (PIX) Description and Test Program.  

National Technical Information Service (NTIS)

The plasma interaction experiment (PIX) is a battery powered preprogrammed auxiliary payload on the LANDSAT-C launch. This experiment is part of a larger program to investigate space plasma interactions with spacecraft surfaces and components. The varying...

L. R. Ignaczak F. A. Haley E. J. Domino D. H. Culp F. J. Shaker

1978-01-01

109

Effects of the g Factor in Semiclassical Kinetic Plasma Theory  

SciTech Connect

A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analyzing the linear properties, it is found that new types of wave-particle resonances are possible that depend directly on the anomalous magnetic moment of the electron. As a result, new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.

Brodin, Gert; Marklund, Mattias; Zamanian, Jens; Ericsson, Aasa; Mana, Piero L. [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden)

2008-12-12

110

Effects of the g factor in semiclassical kinetic plasma theory.  

PubMed

A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analyzing the linear properties, it is found that new types of wave-particle resonances are possible that depend directly on the anomalous magnetic moment of the electron. As a result, new wave modes, not present in the absence of spin, appear. The implications of our results are discussed. PMID:19113628

Brodin, Gert; Marklund, Mattias; Zamanian, Jens; Ericsson, Asa; Mana, Piero L

2008-12-12

111

Kinetic high-beta equilibria in a plasma slab  

SciTech Connect

Self-consistent, high-beta kinetic equilibria are derived from the Vlasov equation for a plasma slab in a nonzero magnetic field with a density gradient and a gravitational field. It is shown that a magnetic field inhomogeneity and an electric field arise as necessary consequences of the high-beta state. Hence the corresponding equilibrium forces should not be neglected in calculations of individual particle motion. Explicit expressions are derived for equilibrium quantities, useful, e.g., for large Larmor radius (LLR) studies of the Rayleigh--Taylor instability.

Li, J.; Scheffel, J. (Royal Inst. of Tech., Stockholm (Sweden). Dept. of Plasma Physics and Fusion Research)

1991-09-01

112

Kinetic modelling of temperature equilibration rates in the plasma  

NASA Astrophysics Data System (ADS)

Using the new Fokker-Planck code KIPP (KInetic code for Plasma Periphery) we examined the accuracy of the common expressions for temperature equilibration rates. Our simulations give new insights into the role of slow electrons in the equilibration process and show that deviations from the common theory are significant especially for the temperature equilibration between two ion species. The second part of the present work deals with the equalization rate of parallel and perpendicular temperatures of a charged species in a magnetic field. Again the simulations show that significant deviations from analytical results arise. Finally we suggest a correction to the analytical formula which better describes our results.

Meisl, G.; Chankin, A. V.; Coster, D. P.

2013-07-01

113

Partially-Collisional Plasma Simulation using Complex Particle Kinetics  

NASA Astrophysics Data System (ADS)

Unlike traditional PIC particles, the CPK (Complex Particle Kinetics) algorithm [1] allows particles with a Gaussian spatial profile and a Mawellian velocity distribution to evolve self-consistently. These particles are then split spatially and/or in velocity to probe for emerging features as the simulation progresses. Aggressive merging is employed to control the number of simulation particles. The combination of the CPK algorithm with our new collision algorithm [2] should allow simulation of plasmas in the previously cost-prohibitive partially-collisional regime. Results from one-dimensional simulations will be compared to experimental data and 2 and 3-D results will be discussed in the context of energetic high altitude events. [1] D.W. Hewett, 'Fragmentation, merging, and internal dynamics for PIC simulation with finite size particles,' accepted by J. Comp. Phys. (2003). [2] D. J. Larson, 'A Coulomb Collision Model for PIC Plasma Simulation,' J. Comp. Phys. 188 (2003).

Larson, David; Hewett, Dennis

2003-10-01

114

On solitary kinetic Alfven waves in a magnetized plasma  

NASA Astrophysics Data System (ADS)

It is proposed that an external magnetic field may inhibit instabilities of multidimensional solitary waves in plasmas. The solitary kinetic Alfven wave (KAW) is investigated in one, and more than one dimension. Nonlinear terms in the wave equation are retained to all orders in the amplitude consistent with the assumption that the plasma pressure is much less than the magnetic pressure. In a cylindrically symmetric geometry, the wave is self-localized in the radial direction (i.e., transverse to the ambient magnetic field line). The radial profile of the wave steepens with the increasing strength of the nonlinearity. The wave steepening saturates at a finite radius. A Lyapunov method is developed to study the stability properties of the non-integrable system. It is found that the cylindrically symmetric solitary KAW is stable against perturbations which do not break its symmetry. The nonlinear waveguide is unstable to transverse perturbations which do reduce its symmetry.

Sheerin, J. P.

115

Solitary kinetic Alfvén waves in bi-ion plasmas  

NASA Astrophysics Data System (ADS)

In the presence of heavy ions a Sagdeev equation is obtained for the solitary kinetic Alfvén waves SKAWs in a low- beta m e m i ll beta ll1 or m i m e gg alpha gg 1 cold plasma Then the numerical solution can be calculated from the analytical expression and the basic equations set The results show that the density humps of SKAWs can exist in the sub-Alfvénic region and the heavy ion density amplitude and the width of the SKAWs rise with the increase in the initial density of heavy ions n b0 in such bi-ion plasmas The wave phase velocity decreases in this case The perturbed electromagnetic fields E z E x and B y are also studied further to discuss the effects of heavy ions on them These numerical results have been plotted for several different parameters

Yang, Y.; Wu, W.

116

Solitary kinetic Alfvén waves in bi-ion plasmas  

NASA Astrophysics Data System (ADS)

A Sagdeev equation is provided for the solitary kinetic Alfvén waves (SKAWs) in a low-? (me/mi<>?>>1), three-component (electrons, protons, and heavy ions) plasma. Then we get the numerical solution of the equation. It is found that the density humps of SKAWs can exist in the sub-Alfvénic region. The heavy ion density amplitude and the width of the SKAWs rise with the increase in the initial density of heavy ions nb0 in such bi-ion plasmas. The perturbed electromagnetic fields Ez, Ex, and By are also studied further to discuss the effects of heavy ions on them. Also, numerical outcomes have been offered for cases with several different parameters to illustrate these results.

Yang, L.; Wu, D. J.

2005-11-01

117

Age differences in plasma norepinephrine kinetics in humans  

SciTech Connect

To determine if the increased plasma norepinephrine (NE) of older individuals is due to greater plasma NE appearance rate and/or decreased NE clearance, arterialized plasma NE kinetics were measured in 25 healthy young (27 +/- 6 yr, M +/- SD) and 18 healthy older volunteers (68 +/- 5 yr) using a tritium-labeled NE isotope dilution technique. Basal NE levels were 54% greater in the older participants (282 +/- 24 vs. 183 +/- 11 pg/ml, M +/- SEM, p less than .001). The mean plasma NE appearance rate was 32% higher (0.33 +/- 0.03 vs. 0.25 +/- 0.02 microgram/m2/min, p less than .016) and NE clearance was 19% lower (1.21 +/- 0.08 vs. 1.49 +/- 0.06 L/min/m2, p less than .006) in the older participants. There was a close correlation between NE appearance rate and NE levels (r = .76, p less than .001, N = 43), but only modest inverse correlation between NE clearance and NE levels (r = -.37, p less than .01, N = 43). Stepwise multiple linear regression analysis revealed that NE appearance rate and clearance explained 80% of the variance in NE levels and that 57% of the variance was attributable to NE appearance, F (1,41) = 54.8, p less than .001, compared with only 14% by NE clearance, F (1, 41) = 6.5, p = .01. We conclude that the principal factor accounting for the higher plasma NE levels of older individuals is an increase in plasma NE appearance rate.

Veith, R.C.; Featherstone, J.A.; Linares, O.A.; Halter, J.B.

1986-05-01

118

Kinetic description of a planar wiggler free electron laser with ion-channel guiding  

NASA Astrophysics Data System (ADS)

A theoretical study of electron trajectories and gain in a planar wiggler free electron laser (FEL) with ion-channel guiding is presented. A kinetic description is given. The linearized Vlasov-Maxwell equations are solved to investigate the growth rate in a tenuous-beam limit for perturbation about a general beam equilibrium distribution function, and generated harmonics are discussed. Linear gain corresponding to FEL resonance for the case of mono-energetic beam is derived and continuous tuning by varying the ion-channel density, for the fundamental mode, is illustrated.

Mehdian, H.; Abbasi, N.

2007-12-01

119

Kinetic Theory of Plasma Adiabatic Major Radius Compression in Tokamaks  

SciTech Connect

A kinetic approach is developed to understand the individual charged particle behavior as well as plasma macro parameters (temperature, density, etc.) during the adiabatic R-compression in a tokamak. The perpendicular electric field from Ohm's law at zero resistivity E = -v{sub E}{times}B/c is made use of to obtain the equation for particle velocity evolution in order to describe the particle motion during the R-compression. Expressions for both passing and trapped particle energy and pitch angle change are obtained for a plasma with high aspect ratio and circular magnetic surfaces. The particle behavior near the trapped passing boundary during the compression is also studied to understand the shift induced loss of alpha particles produced by D-T fusion reactions in Tokamak Fusion Test Reactor experiments. Qualitative agreement is obtained with the experiments. Solving the drift kinetic equation in the collisional case, i.e., when the collisional frequency of given species exceeds the inverse compression time, we obtain that the temperature and the density evolution is reduced to the MHD results T {approximately} R{super -4/3} and n {approximately} R{super -2}, respectively. In the opposite case, the collisional frequency of given species is smaller than the inverse compression time, the longitudinal component of the temperature evolve like R{super -2} and perpendicular component of the temperature is R{super -1}. The effect of toroidicity is negligible in both cases.

A.N. Romannikov; E.A. Azizov; H.W. Herrmann; M.V. Gorelenkova; N.N. Gorelenkov

1997-10-01

120

Kinetic Effects of Non-Equilibrium Plasma on Partially Premixed Flame Extinction.  

National Technical Information Service (NTIS)

A new plasma assisted combustion system was developed by integrating a counterflow burner with nano-second pulsed non-equilibrium discharge. The kinetic effects of plasma assisted fuel oxidization on the extinction of partially premixed methane flames was...

M. Uddi S. H. Won T. Ombrello W. Sun Y. Ju

2011-01-01

121

Electromagnetic effects of kinetic geodesic acoustic mode in tokamak plasmas  

SciTech Connect

Electromagnetic effects of the kinetic geodesic acoustic modes (KGAMs) are numerically studied in low {beta}(= plasma pressure/magnetic pressure) tokamak plasmas. The parallel component of the perturbed vector potential is considered along with the electrostatic potential perturbation. The finite Larmor radius and finite orbit width of the ions as well as electron parallel dynamics are all taken into account. Systematic harmonic and ordering analysis is performed for collisionless damping of the KGAMs, assuming {beta}{approx}({kappa}{rho}{sub i}){sup 2}, where {kappa}and {rho}{sub i}are the radial component of the KGAM wave vector and the Larmor radius of the ions, respectively. It is found that the electron parallel dynamics enhances the damping of the electrostatic KGAM modes when the safety factor q is high. In addition, the electromagnetic (finite {beta} effect is revealed to enhance and weaken the damping of the modes in plasmas of low and high safety factor q{approx}2.0 and 5.5, respectively. The harmonic features of the KGAMs are discussed as well.

Wang Lingfeng; Shen, Y.; He, H. D. [Southwestern Institute of Physics, Chengdu 610041 (China); Dong, J. Q. [Southwestern Institute of Physics, Chengdu 610041 (China); Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)

2011-05-15

122

Complex (dusty) plasmas-kinetic studies of strong coupling phenomena  

SciTech Connect

'Dusty plasmas' can be found almost everywhere-in the interstellar medium, in star and planet formation, in the solar system in the Earth's atmosphere, and in the laboratory. In astrophysical plasmas, the dust component accounts for only about 1% of the mass, nevertheless this component has a profound influence on the thermodynamics, the chemistry, and the dynamics. Important physical processes are charging, sputtering, cooling, light absorption, and radiation pressure, connecting electromagnetic forces to gravity. Surface chemistry is another important aspect. In the laboratory, there is great interest in industrial processes (e.g., etching, vapor deposition) and-at the fundamental level-in the physics of strong coupling phenomena. Here, the dust (or microparticles) are the dominant component of the multi-species plasma. The particles can be observed in real time and space, individually resolved at all relevant length and time scales. This provides an unprecedented means for studying self-organisation processes in many-particle systems, including the onset of cooperative phenomena. Due to the comparatively large mass of the microparticles (10{sup -12}to10{sup -9}g), precision experiments are performed on the ISS. The following topics will be discussed: Phase transitions, phase separation, electrorheology, flow phenomena including the onset of turbulence at the kinetic level.

Morfill, Gregor E.; Ivlev, Alexei V.; Thomas, Hubertus M. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany)

2012-05-15

123

Chemical kinetics study of a nanosecond pulsed He-O2 plasma Jet  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure, nanosecond pulsed plasma jets have shown promising applications in biomedical and dental fields. In order to better understand the mechanisms associated to the plasma processes, a zero-dimensional plasma chemistry model was used to study the chemical kinetics of an atmospheric-pressure, nanosecond pulsed He-O2 plasma jet. Density kinetics of the charged and neutral species in the plasma jet as a function of the input parameters including the oxygen concentration and the electric field are calculated. The roles played by different reactions in the kinetics schemes are assessed. In addition, both of He-O2 and He-O2-N2 plasma chemical kinetics reaction schemes are discussed to examine the effects of air entrainment on the characteristics of the plasma jet.

Xia, Shengguo; Jiang, Chunqi

2011-11-01

124

Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model  

NASA Technical Reports Server (NTRS)

The global dynamics of the ionized and neutral components in the environment of Io plays an important role in the interaction of Jupiter's corotating magnetospheric plasma with Io. The stationary simulation of this problem was done in the MHD and the electrodynamics approaches. One of the main significant results from the simplified two-fluid model simulations was a production of the structure of the double-peak in the magnetic field signature of the I0 flyby that could not be explained by standard MHD models. In this paper, we develop a method of kinetic ion simulation. This method employs the fluid description for electrons and neutrals whereas for ions multilevel, drift-kinetic and particle, approaches are used. We also take into account charge-exchange and photoionization processes. Our model provides much more accurate description for ion dynamics and allows us to take into account the realistic anisotropic ion distribution that cannot be done in fluid simulations. The first results of such simulation of the dynamics of ions in the Io's environment are discussed in this paper.

Lipatov, Alexander S.; Combi, Michael R.

2004-01-01

125

Fundamental Statistical Descriptions of Plasma Turbulence in Magnetic Fields.  

National Technical Information Service (NTIS)

A pedagogical review of the historical development and current status (as of early 2000) of systematic statistical theories of plasma turbulence is undertaken. Emphasis is on conceptual foundations and methodology, not practical applications. Particular a...

J. A. Krommes

2001-01-01

126

Covariant formulation of spatially non-symmetric kinetic equilibria in magnetized astrophysical plasmas  

NASA Astrophysics Data System (ADS)

Astrophysical plasmas in the surrounding of compact objects and subject to intense gravitational and electromagnetic fields are believed to give rise to relativistic regimes. Theoretical and observational evidences suggest that magnetized plasmas of this type are collisionless and can persist for long times (e.g., with respect to a distant observer, coordinate, time), while exhibiting geometrical structures characterized by the absence of well-defined spatial symmetries. In this paper, the problem is posed whether such configurations can correspond to some kind of kinetic equilibrium. The issue is addressed from a theoretical perspective in the framework of a covariant Vlasov statistical description, which relies on the method of invariants. For this purpose, a systematic covariant variational formulation of gyrokinetic theory is developed, which holds without requiring any symmetry condition on the background fields. As a result, an asymptotic representation of the relativistic particle magnetic moment is obtained from its formal exact solution, in terms of a suitably defined invariant series expansion parameter (perturbative representation). On such a basis, it is shown that spatially non-symmetric kinetic equilibria can actually be determined, an example being provided by Gaussian-like distributions. As an application, the physical mechanisms related to the occurrence of a non-vanishing equilibrium fluid 4-flow are investigated.

Cremaschini, Claudio; Tessarotto, Massimo; Stuchlík, Zden?k

2014-05-01

127

Kinetic equations for systems with long-range interactions: a unified description  

NASA Astrophysics Data System (ADS)

We complete the existing literature on the kinetic theory of systems with long-range interactions. Starting from the BBGKY hierarchy, or using projection operator technics or a quasilinear theory, a general kinetic equation can be derived when collective effects are neglected. This equation (which is not well known) applies to possibly spatially inhomogeneous systems, which is specific to systems with long-range interactions. Interestingly, the structure of this kinetic equation bears a clear physical meaning in terms of generalized Kubo relations. Furthermore, this equation takes a very similar form for stellar systems and two-dimensional point vortices, providing therefore a unified description of the kinetic theory of these systems. If we assume that the system is spatially homogeneous (or axisymmetric for point vortices), this equation can be simplified and reduces to the Landau equation (or its counterpart for point vortices). Our formalism thus offers a simple derivation of Landau-type equations. We also use this general formalism to derive a kinetic equation, written in angle-action variables, describing spatially inhomogeneous systems with long-range interactions. This new derivation solves the shortcomings of our previous derivation (Chavanis 2007 Physica A 377 469). Finally, we consider a test particle approach and derive general expressions for the diffusion and friction (or drift) coefficients of a test particle evolving in a bath of field particles. We make contact with the expressions previously obtained in the literature. As an application of the kinetic theory, we argue that, for one-dimensional systems and two-dimensional point vortices, the relaxation time is shorter for inhomogeneous (or non-axisymmetric) distributions than for homogeneous (or axisymmetric) distributions because there are potentially more resonances. We compare this prediction with existing numerical results. For the HMF model, we argue that the relaxation time scales like N for inhomogeneous distributions and like eN for permanently homogeneous distributions. Phase-space structures can reduce the relaxation time by creating some inhomogeneities and resonances. Similar results are expected for 2D point vortices. For systems with higher dimension, the relaxation time scales like N. The relaxation time of a test particle in a bath also scales like N in any dimension.

Chavanis, Pierre-Henri

2010-05-01

128

Kinetic modeling of plasma methane conversion in a dielectric barrier discharge  

Microsoft Academic Search

Methane conversion by plasma offers a promising route to produce higher value-added products. As plasma reaction is a relatively complex process, kinetic modeling is necessary to obtain a general pattern of the complex interaction on the basis of chemical reaction and products. In this paper, we present a method to obtain the kinetic rate coefficient (k) from the experimental data.

Antonius Indartoa; Nowarat Coowanitwong; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

2008-01-01

129

Hydrocarbon combustion enhancement by applied electric field and plasma kinetics  

NASA Astrophysics Data System (ADS)

Hydrocarbon flame speed and flame structure modifications have been studied using a low dc applied electric field opposing the gas flow directions. Our electrode configuration leads to a relatively high conduction current with a low applied voltage drop in the flame that permits to collect ~1011 cm-3 chemi-ion density at the pre-heat flame zone, which seems to simulate DBDs and other plasma assisted combustion enhancement conditions. The dissociative recombination of major positive chemi-ions H3O+ and HCO+ produces 1011 cm-3 H, O and OH radicals modifying both combustion kinetics and fluidics. Also, flame electrical conductivity measurement was found to correlate very well with the CH, OH and C2 chemiluminescence intensity fluctuations.

Ganguly, B. N.

2007-12-01

130

Kinetic theory of plasma adiabatic major radius compression in tokamaks  

SciTech Connect

A kinetic approach is developed to understand the individual charged particle behavior as well as plasma macro parameters (temperature, density, etc.) during the adiabatic R-compression in a tokamak. The perpendicular electric field from Ohm`s law at zero resistivity E = {minus}v{sub E} x B/c is made use of to obtain the equation for particle velocity evolution in order to describe the particle motion during the R-compression. Expressions for both passing and trapped particle energy and pitch angle change are obtained for a plasma with high aspect ratio and circular magnetic surfaces. The particle behavior near the trapped passing boundary during the compression is also studied to understand the shift induced loss of alpha particles produced by D-T fusion reactions in Tokamak Fusion Test Reactor experiments. Qualitative agreement is obtained with the experiments. Solving the drift kinetic equation in the collisional case, i.e., when the collisional frequency {nu}{sub coll} of given species exceeds the inverse compression time {tau}{sub compr}{sup {minus}1}, the authors obtain that the temperature and the density evolution is reduced to the MHD results T {approximately} R{sup {minus}4/3} and n {approximately} R{sup {minus}2}, respectively. In the opposite case, {nu}{sub coll} {much_lt} {tau}{sub compr}{sup {minus}1}, the longitudinal component of the temperature evolve like R(superscript)-2(end superscript) and perpendicular components of the temperature evolve like T{sub {parallel}} {approximately} R{sup {minus}2} and T{sub {perpendicular}} {approximately} R{sup {minus}1}. The effect of toroidicity is negligible in both cases.

Gorelenkova, M.V.; Gorelenkov, N.N.; Azizov, E.A.; Romannikov, A.N. [Troitsk Inst. for Innovative and Fusion Research (Russian Federation); Herrmann, H.W. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.

1997-10-01

131

A fluid description of plasma double-layers  

NASA Technical Reports Server (NTRS)

The space-charge double layer forming between two plasmas with different densities and thermal energies is described. The double layer is analyzed using fluid theory. The case of cold particles is treated. Thermal effects for the reflected particles and for the transmitted particles are considered. Emphasis is placed on finding a relationship between the magnitude of the potential step and the parameters characterizing the adjoining plasmas. Qualitative statements are made about the length of the double layer, and a characteristic length useful as a quantitative measure is defined and discussed.

Levine, J. S.; Crawford, F. W.

1980-01-01

132

Kinetic stability constraints on magnetized plasma equilibria: Quasi-particle approach.  

National Technical Information Service (NTIS)

Macroscopic adiabatic invariants for the magnetized plasma are studied within the context of the quasi-particle description, as well as constraints which they impose on energy transfer and stable plasma equilibria. 6 refs. (Atomindex citation 27:073763)

P. Sosenko J. Weiland

1996-01-01

133

First-Principles-Based Development of Kinetic Mechanisms in Chemically Active Light-Emitting Nonthermal Plasmas and Gases  

SciTech Connect

Recent progress in several related research areas such as first-principles electronic-structure calculations of atoms and diatomic molecules, theory of elementary processes, kinetics, and numerical engineering, and also continued exponential growth in computational resources enhanced by recent advances in massively parallel computing have opened the possibility of directly designing kinetics mechanisms to describe chemical processes and light emission in such complex media as nonequilibrium plasmas and reacting gases. It is important that plasma and combustion kinetics can be described in the framework of this direct approach to a sufficiently high accuracy, which makes it an independent predictive research tool complementary to experimental techniques. This paper demonstrates the capabilities of the first-principles based approach to develop kinetic mechanisms. Two examples are discussed in detail: (1) the mechanism of hydrocarbon fuel combustion at high temperatures and (2) light emission in non-thermal glow discharge plasma of metal halides; special attention is paid to a comparison of the results obtained at every level of system description with the appropriate experimental data. In house software tools that can be used in such multilevel theoretical works are discussed as well.

Astapenko, Valerie; Bagatur'yants, Alexander; Chernishova, Irina; Deminsky, Maxim; Eletskii, Alexander; Knizhnik, Andrei; Potapkin, Boris; Rykova, Elena; Umanskii, Stanislaw; Zaitsevskii, Andrei; Safonov, Andrei [Kinetics Technologies, Moscow (Russian Federation); Kirillov, Igor; Strelkova, Marina; Sukhanov, Leonid [RRC Kurchatov Institute, Moscow (Russian Federation); Cotzas, George M.; Dean, Anthony; Michael, J. Darryl; Midha, Vikas; Smith, David J.; Sommerer, Timothy J. [GE Global Research, Niskayuna, New York (United States)] (and others)

2007-04-06

134

Microscopic Lagrangian description of warm plasmas, 1, Linear wave propagation  

Microsoft Academic Search

This three-part paper describes linear and nonlinear plasma wave phenomena in an infinite, homogeneous, collisionless, warm magnetoplasma by means of a microscopic Lagrang\\/an. Part 1 derives the dispersion relation for all modes of linear wave propagation. To do so, the charged particle position vectors and the fields are first expanded in terms of sinusoidal perturbations from equilibrium. The contribution to

H. Kim; F. W. Crawford

1977-01-01

135

Jupiter's magnetosphere: Plasma description from the Ulysses flyby  

SciTech Connect

Plasma observations at Jupiter show that the outer regions of the Jovian magnetosphere are remarkably similar to those of Earth. Bow-shock precursor electrons and ions were detected in the upstream solar wind, as at Earth. Plasma changes across the bow shock and properties of the magnetosheath electrons were much like those at Earth, indicating that similar processes are operating. A boundary layer populated by a varying mixture of solar wind and magnetospheric plasmas was found inside the magnetopause, again as at Earth. In the middle magnetosphere, large electron density excursions were detected with a 10-hour periodicity as planetary rotation carried the tilted plasma sheet past Ulysses. Deep in the magnetosphere, Ulysses crossed a region, tentatively described as magnetically connected to the Jovian polar cap on one end and to the interplanetary magnetic field on the other. In the inner magnetosphere and Io torus, where corotation plays a dominant role, measurements could not be made because of extreme background rates from penetrating radiation belt particles.

Bame, S.J.; Barraclough, B.L.; Feldman, W.C.; Gisler, G.R.; Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Thomsen, M.F. (Los Alamos National Lab., NM (United States)); Goldstein, B.E.; Neugebauer, M. (California Inst. of Tech., Pasadena (United States))

1992-09-11

136

Molecular Dynamics Description of Partially Ionized Dense Plasmas  

NASA Astrophysics Data System (ADS)

A report on work in progress: the approach to steady-state of partially ionized dense plasmas, containing more than one atomic element, is being simulated with the quasi-classical method known as Fermi Molecular Dynamics (FMD). We recap the FMD method, recalling its several advantages and disadvantages, and present an overview of past work. we have continued to develop the FMD method as a tool for simulating the behaviors of a variety of inhomogeneous, partially ionized, dense plasma systems, in cases for which more rigorous methods are still unavailable. Predictions of the average ionization state Z* of atoms, in a plasma containing more than one atomic element, is complicated by many factors, especially under conditions of high density, and not too high temperature. Average atom models become problematic when two or more atomic elements are present together. In order to address this problem, we have applied the FMD method to plasmas containing selected mixtures of atomic elements, determining Z* for each element over a range of temperatures and densities. LANL archived abstract: LA-UR-04-2186

Lagattuta, Ken

2004-11-01

137

Fundamentals of the Plasma Sail Concept: MHD and Kinetic Studies  

NASA Technical Reports Server (NTRS)

The Mini-Magnetospheric Plasma Propulsion (M2P2), originally proposed by Winglee et al. [2000] 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 the unprecedented speeds of 50-80 km/s after an acceleration period of about three months. Such velocities will enable travel out of the solar system in period of about seven years-almost an order of magnitude improvement over present chemical based propulsion systems. However, for the parameters of the simulation of Winglee et al. [2000], a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the 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. We have adopted a two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail. 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 momentum transfer to the innermost regions of the plasma sail is negligible.

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

2003-01-01

138

Microphysics of Cosmic Plasmas: Hierarchies of Plasma Instabilities from MHD to Kinetic  

NASA Astrophysics Data System (ADS)

In this article, we discuss the idea of a hierarchy of instabilities that can rapidly couple the disparate scales of a turbulent plasma system. First, at the largest scale of the system, L, current carrying flux ropes can undergo a kink instability. Second, a kink instability in adjacent flux ropes can rapidly bring together bundles of magnetic flux and drive reconnection, introducing a new scale of the current sheet width, ?, perhaps several ion inertial lengths (? i ) across. Finally, intense current sheets driven by reconnection electric fields can destabilize kinetic waves such as ion cyclotron waves as long as the drift speed of the electrons is large compared to the ion thermal speed, v D ?v i . Instabilities such as these can couple MHD scales to kinetic scales, as small as the proton Larmor radius, ? i .

Brown, M. R.; Browning, P. K.; Dieckmann, M. E.; Furno, I.; Intrator, T. P.

139

Kinetic Modeling of the Lunar Dust-Plasma Environment  

NASA Astrophysics Data System (ADS)

Modeling of the lunar dust and plasma environment is a challenging task because a self-consistent model should include ions, electrons and dust particles and numerous other factors. However, most of the parameters are not well established or constrained by measurements in the lunar environment. More precisely, a comprehensive model should contain electrons originating from 1) the solar wind, 2) the lunar material (photoelectrons, secondary electrons) and 3) the lunar dust. Ions originate from the solar wind, the lunar material, the lunar exosphere and the dust. To model the role of the dust in the lunar plasma environment is a highly complex task since the properties of the dust particles in the exosphere are poorly known (e.g. mass, size, shape, conductivity) or not known (e.g. charge and photoelectron emission) and probably are time dependent. Models should also include the effects of interactions between the surface and solar wind and energetic particles, and micrometeorites. Largely different temporal and spatial scales are also a challenge for the numerical models. In addition, the modeling of a region on the Moon - for example on the South Pole - at a given time requires also knowledge of the solar illumination conditions at that time, mineralogical and electric properties of the local lunar surface, lunar magnetic anomalies, solar UV flux and the properties of the solar wind. Harmful effects of lunar dust to technical devices and to human health as well as modeling of the properties of the lunar plasma and dust environment have been topics of two ESA funded projects L-DEPP and DPEM. In the presentation we will summarize some basic results and characteristics of plasma and fields near and around the Moon as studied and discovered in these projects. Especially, we analyse three different space and time scales by kinetic models: [1] the "microscale" region near surface with an electrostatic PIC (ions and electrons are particles) model, [2] the "mesoscale" region including lunar magnetic anomalies and [3] the global scale Moon-solar wind interaction with hybrid (ions as particles in massless electron fluid) models.

Kallio, Esa; Alho, Markku; Alvarez, Francisco; Barabash, Stas; Dyadechkin, Sergey; Fernandes, Vera; Futaana, Yoshifumi; Harri, Ari-Matti; Haunia, Touko; Heilimo, Jyri; Holmström, Mats; Jarvinen, Riku; Lue, Charles; Makela, Jakke; Porjo, Niko; Schmidt, Walter; Shahab, Fatemi; Siili, Tero; Wurz, Peter

2014-05-01

140

Kinetic modelling of the interaction of rotating magnetic fields with a radially inhomogeneous plasma  

Microsoft Academic Search

The interaction of rotating magnetic fields (RMFs) with a plasma is modelled in the linear approximation. A kinetic Hamiltonian model for the rf plasma conductivity is used. A radially inhomogeneous periodic cylindrical plasma with a rotational transform of the magnetic field is studied with parameters relevant to the dynamic ergodic divertor (DED) of TEXTOR. For the case of a finite

Martin F. Heyn; Ivan B. Ivanov; Sergei V. Kasilov; Winfried Kernbichler

2006-01-01

141

SOLAR WIND TURBULENT SPECTRUM AT PLASMA KINETIC SCALES  

SciTech Connect

The description of the turbulent spectrum of magnetic fluctuations in the solar wind in the kinetic range of scales is not yet completely established. Here, we perform a statistical study of 100 spectra measured by the STAFF instrument on the Cluster mission, which allows us to resolve turbulent fluctuations from ion scales down to a fraction of electron scales, i.e., from {approx}10{sup 2} km to {approx}300 m. We show that for k {rho} {sub e} in [0.03, 3] (which corresponds approximately to the frequency in the spacecraft frame f in [3, 300] Hz), all the observed spectra can be described by a general law E(k ){proportional_to}k {sup -8/3} exp (- k {rho} {sub e}), where k is the wavevector component normal to the background magnetic field and {rho} {sub e} the electron Larmor radius. This exponential tail found in the solar wind seems compatible with the Landau damping of magnetic fluctuations onto electrons.

Alexandrova, O.; Lacombe, C.; Mangeney, A.; Maksimovic, M. [LESIA-Observatoire de Paris, CNRS, UPMC Universite Paris 06, Universite Paris-Diderot, 5 place J. Janssen, F-92190 Meudon (France); Grappin, R. [LUTH-Observatoire de Paris, CNRS, Universite Paris-Diderot, 5 place J. Janssen, F-92190 Meudon (France)

2012-12-01

142

Kinetic modeling and molecular dynamics simulation of ultracold neutral plasmas including ionic correlations  

SciTech Connect

A kinetic approach for the evolution of ultracold neutral plasmas including interionic correlations and the treatment of ionization/excitation and recombination/deexcitation by rate equations is described in detail. To assess the reliability of the approximations inherent in the kinetic model, we have developed a hybrid molecular dynamics method. Comparison of the results reveals that the kinetic model describes the atomic and ionic observables of the ultracold plasma surprisingly well, confirming our earlier findings concerning the role of ion-ion correlations [Phys. Rev. A 68, 010703 (2003)]. In addition, the molecular dynamics approach allows one to study the relaxation of the ionic plasma component toward thermodynamical equilibrium.

Pohl, T.; Pattard, T.; Rost, J.M. [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany)

2004-09-01

143

Kinetic approach to microscopic-macroscopic coupling in space and laboratory plasmas  

SciTech Connect

Kinetic plasma simulation typically requires to handle a multiplicity of space and time scales. The implicit moment particle in cell (PIC) method provides a possible route to address the presence of multiple scales effectively. Here, a new implementation of the implicit moment method is described. The present paper has two goals. First, the most modern implementation of the implicit moment method is described. While many of the algorithms involved have been developed in the past, the present paper reports for the first time how the implicit moment method is currently implemented and what specific algorithms have been found to work best. Second, we present the CELESTE3D code, a fully electromagnetic and fully kinetic PIC code, based on the implicit moment method. The code has been in use for a number of years but no previous complete description of its implementation has been provided. The present work fills this gap and introduces a number of new methods not previously presented: a new implementation of the Maxwell solver and a new particle mover based on a Newton-Krylov nonlinear solver for the discretized Newton's equations. A number of benchmarks of CELESTE3D are presented to shown the typical application and to investigate the improvements introduced by the new solver and the new mover.

Lapenta, Giovanni; Brackbill, J.U.; Ricci, Paolo [Plasma Theory Group, Theoretical Division, Los Alamos National Laboratory, Mail Stop: K717, Los Alamos, New Mexico 87545 (United States); Particle Solutions, Portland, Oregon 97214 (United States); Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2006-05-15

144

Effect of antenna size on electron kinetics in inductively coupled plasmas  

SciTech Connect

Spatially resolved measurements of electron energy distribution functions (EEDFs) are investigated in inductively coupled plasmas with two planar antenna coils. When the plasma is sustained by the antenna with a diameter of 18 cm, the nonlocal kinetics is preserved in the argon gas pressure range from 2 mTorr to 20 mTorr. However, electron kinetics transit from nonlocal kinetics to local kinetics in discharge sustained by the antenna coil with diameter 34 cm. The results suggest that antenna size as well as chamber length are important parameters for the transition of the electron kinetics. Spatial variations of plasma potential, effective electron temperature, and EEDF in terms of total electron energy scale are also presented.

Lee, Hyo-Chang; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)] [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

2013-10-15

145

Effect of antenna size on electron kinetics in inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

Spatially resolved measurements of electron energy distribution functions (EEDFs) are investigated in inductively coupled plasmas with two planar antenna coils. When the plasma is sustained by the antenna with a diameter of 18 cm, the nonlocal kinetics is preserved in the argon gas pressure range from 2 mTorr to 20 mTorr. However, electron kinetics transit from nonlocal kinetics to local kinetics in discharge sustained by the antenna coil with diameter 34 cm. The results suggest that antenna size as well as chamber length are important parameters for the transition of the electron kinetics. Spatial variations of plasma potential, effective electron temperature, and EEDF in terms of total electron energy scale are also presented.

Lee, Hyo-Chang; Chung, Chin-Wook

2013-10-01

146

Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model  

NASA Technical Reports Server (NTRS)

The global dynamics of the ionized and neutral gases in the environment of Io plays an important role in the interaction of Jupiter s corotating magnetospheric plasma with Io. Stationary simulations of this problem have already been done using the magnetohydrodynamics (MHD) and the electrodynamics approaches. One of the major results of recent simplified two-fluid model simulations [Saur, J., Neubauer, F.M., Strobel, D.F., Summers, M.E., 2002. J. Geophys. Res. 107 (SMP5), 1-18] was the production of the structure of the double-peak in the magnetic field signature of the Io flyby. These could not be explained before by standard MHD models. In this paper, we present a hybrid simulation for Io with kinetic ions and fluid electrons. This method employs a fluid description for electrons and neutrals, whereas for ions a particle approach is used. We also take into account charge-exchange and photoionization processes and solve self-consistently for electric and magnetic fields. Our model may provide a much more accurate description for the ion dynamics than previous approaches and allows us to account for the realistic anisotropic ion velocity distribution that cannot be done in fluid simulations with isotropic temperatures. The first results of such a simulation of the dynamics of ions in Io s environment are discussed in this paper. Comparison with the Galileo IO flyby results shows that this approach provides an accurate physical basis for the interaction and can therefore naturally reproduce all the observed salient features.

Lipatov, Alexander S.; Combi, Michael R.

2006-01-01

147

The Plasma Kinetics and Tissue Distribution of Enrofloxacin and its Metabolite Ciprofloxacin in the Muscovy Duck  

Microsoft Academic Search

Intorre, L., Mengozzi, G., Bertini, S., Bagliacca, M., Luchetti, E. and Soldani, G., 1997. The plasma kinetics and tissue distribution of enrofloxacin and its metabolite ciprofloxacin in the Muscovy duck. Veterinary Research Communications, 21 (2), 127-136

L. Intorre; G. Mengozzi; S. Bertini; M. Bagliacca; E. Luchetti; G. Soldani

1997-01-01

148

Kinetic model of three-component, weakly ionized, collisional plasma with a beam of neutral particles  

NASA Astrophysics Data System (ADS)

Kinetic model of three component, weakly ionized, collisional plasma with a beam of neutral particles is developed. New dispersion relations for linear perturbations are derived and analyzed in various limiting cases.

Tsiklauri, David

2000-02-01

149

Self-consistent Theory of Young Plasma Bubbles: Kinetic and 3D Aspects  

Microsoft Academic Search

One of the major problems in modeling bursty transport of plasma and magnetic flux in the Earth's magnetotail is incomplete description of the elementary unit of that transport, the localized entropy-depleted flux tube or plasma bubble, which may convect much faster than the rest of the tail plasmas because of the buoyancy effect. Particularly unclear is the bubble formation process,

M. I. Sitnov; P. N. Guzdar; A. V. Divin; M. Swisdak

2006-01-01

150

Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas  

SciTech Connect

A nonvariational kinetic-MHD stability code (NOVA-K) has been developed to integrate a set of non-Hermitian integro-differential eigenmode equations due to energetic particles for axisymmetric toroidal plasmas in a general flux coordinate system with an arbitrary Jacobian. The NOVA-K code employs the Galerkin method involving Fourier expansions in the generalized poloidal angle theta and generalized toroidal angle /zeta/ directions, and cubic-B spline finite elements in the radial /Psi/ direction. Extensive comparisons with the existing variational ideal MHD codes show that the ideal MHD version of the NOVA-K code converges faster and gives more accurate results. The NOVA-K code is employed to study the effects of energetic particles on MHD-type modes: the stabilization of ideal MHD internal kink modes and the excitation of ''fishbone'' internal kink modes; and the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are also presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n = 1 internal kink mode in the hot particle beta space exists even in the absence of the core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to have negligible effects on the stability of the n = 1 internal kink mode, but the circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 60 refs., 24 figs., 1 tab.

Cheng, C.Z.

1989-04-01

151

Quark-Gluon Plasma Formation in Relativistic Heavy Ion Collisions within the Hydrodynamical Description.  

National Technical Information Service (NTIS)

Within the one-dimensional one-component fluid-dynamical description, the space-time picture of the quark-gluon plasma formation with finite rearrangement time during relativistic heavy ion collisions is studied. Maximum effect of the delayed deconfinemen...

B. Kaempfer H. W. Barz B. Lukacs

1985-01-01

152

Non-Markovian renormalization of kinetic coefficients for drift-type turbulence in magnetized plasmas  

SciTech Connect

The problem of derivation of the kinetic equations for inhomogeneous plasma in an external magnetic field is considered. The Fokker-Planck-type equations with the non-Markovian kinetic coefficients are proposed. In the time-local limit (small correlation times with respect to the distribution function relaxation time) the relations obtained recover the results known from the appropriate quasilinear theory and the Dupree-Weinstock theory of plasma turbulence. Kinetic calculations of the dielectric response function are also performed with regard to the influence of turbulent fields on particle motion. The equations proposed are used to describe zonal flow generation and to estimate the diffusion coefficient for saturated turbulence.

Zagorodny, A.; Weiland, J. [Bogolyubov Institute for Theoretical Physics, Kiev (Ukraine)

2009-05-15

153

Two new proofs of the test particle superposition principle of plasma kinetic theory  

Microsoft Academic Search

The test particle superposition principle of plasma kinetic theory is discussed in relation to the recent theory of two-time fluctuations in plasma given by Williams and Oberman. Both a new deductive and a new inductive proof of the principle are presented; the deductive approach appears here for the first time in the literature. The fundamental observation is that two-time expectations

John A. Krommes

1976-01-01

154

Impact of kinetic processes on the macroscopic nonlinear evolution of the electromagnetic-beam-plasma instability  

PubMed

We present a new, fully kinetic mechanism of generation of spatial magnetic vortices that results from the resonant wave-particle interaction in a plasma. This phenomenon is of basic theoretical interest. It can be responsible for the magnetic vortices observed in numerical simulations in the wake of an ultrastrong, ultraintense laser pulse in an underdense plasma. PMID:11019156

Califano; Pegoraro; Bulanov

2000-04-17

155

Observation of kinetic plasma jets in a coronal-loop simulation experiment.  

PubMed

Under certain conditions an intense kinetic plasma jet is observed to emerge from the apex of laboratory simulations of coronal plasma loops. Analytic and numerical models show that these jets result from a particle orbit instability in a helical magnetic field whereby magnetic forces radially eject rather than confine ions with sufficiently large countercurrent axial velocity. PMID:17501208

Tripathi, S K P; Bellan, P M; Yun, G S

2007-03-30

156

Radical kinetics simulation for transient plasma ignition for fuel-air mixtures  

Microsoft Academic Search

Summary form only given. The recent application of nanosecond transient plasma, or pulsed corona, discharges for combustion and detonation ignition has stimulated interest in the plasma chemistry of the role of radical kinetics for hydrocarbon fuel and dry air mixtures including CH4 - air, C3H8 - air, and C2H4 - air mixtures. This simulation study seeks to elucidate reaction mechanisms

C. Jiang; L. C. Lee; F. Wang; M. A. Gundersen

2004-01-01

157

Role of plasma activation in the kinetics of CNT growth in PECVD process  

NASA Astrophysics Data System (ADS)

The work presents kinetic modeling of the effect of acceleration for the growth kinetics of carbon nanotubes by hydrocarbon gas mixture modification with plasma discharge. The plasma activation creates active species in hydrocarbon gas mixture, which can easily adsorb and dissociate on the catalyst surface. So plasma treatment of the gas mixture in the CVD process allows to increase the carbon supply rate by a few orders of magnitude compared to that in thermal CVD process. On the other hand, plasma can also provide etching of carbon species from the catalyst surface. To correctly reproduce both of these effects of plasma, the kinetic model of growth of carbon nanotubes is developed based on first-principles analysis of heterogeneous processes on the catalyst surface and detailed kinetics of gas phase chemistry. The model is used to compare the growth rates of carbon nanotubes in thermal and plasma-enhanced CVD processes and to determine critical gas pressures, at which CNT growth kinetics switches from the adsorption limitation to the limitation by reaction and diffusion on the catalyst.

Lebedeva, Irina; Gavrikov, Alexey; Baranov, Alexey; Belov, Maxim; Knizhnik, Andrey; Potapkin, Boris; Sommerer, Timothy

2009-10-01

158

Extent of validity of the hydrodynamic description of ions in dense plasmas.  

PubMed

We show that the hydrodynamic description can be applied to modeling the ionic response in dense plasmas for a wide range of length scales that are experimentally accessible. Using numerical simulations for the Yukawa model, we find that the maximum wave number k(max) at which the hydrodynamic description applies is independent of the coupling strength, given by k(max)?(s)?0.43, where ?(s) is the ionic screening length. Our results show that the hydrodynamic description can be used for interpreting x-ray scattering data from fourth generation light sources and high power lasers. In addition, our investigation sheds new light on how the domain of validity of the hydrodynamic description depends on both the microscopic properties and the thermodynamic state of fluids in general. PMID:21405737

Mithen, James P; Daligault, Jérôme; Gregori, Gianluca

2011-01-01

159

Extent of validity of the hydrodynamic description of ions in dense plasmas  

SciTech Connect

We show that the hydrodynamic description can be applied to modeling the ionic response in dense plasmas for a wide range of length scales that are experimentally accessible. Using numerical simulations for the Yukawa model, we find that the maximum wave number k{sub max} at which the hydrodynamic description applies is independent of the coupling strength, given by k{sub max}{lambda}s{approx_equal}0.43, where {lambda}{sub s} is the ionic screening length. Our results show that the hydrodynamic description can be used for interpreting x-ray scattering data from fourth generation light sources and high power lasers. In addition, our investigation sheds new light on how the domain of validity of the hydrodynamic description depends on both the microscopic properties and the thermodynamic state of fluids in general.

Mithen, James P.; Gregori, Gianluca [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Daligault, Jerome [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-01-15

160

Kinetic effects on streaming instabilities in electron-positron-ion plasmas  

NASA Astrophysics Data System (ADS)

Streaming instabilities in electron-positron-ion plasmas are investigated using kinetic approach in several different limits. The effects of the variation of background temperatures of electrons Teo and positrons Tpo on the growth rates are also presented for the case of ion beam streaming into electron-positron plasmas and positrons beam streaming into electron-ion plasmas. It is noticed that the increase of number density of positrons gives a destabilizing trend to the electrostatic perturbations in the system.

Shan, S. Ali; Saleem, H.

2009-02-01

161

LIGKA: A linear gyrokinetic code for the description of background kinetic and fast particle effects on the MHD stability in tokamaks  

SciTech Connect

In a plasma with a population of super-thermal particles generated by heating or fusion processes, kinetic effects can lead to the additional destabilisation of MHD modes or even to additional energetic particle modes. In order to describe these modes, a new linear gyrokinetic MHD code has been developed and tested, LIGKA (linear gyrokinetic shear Alfven physics) [Ph. Lauber, Linear gyrokinetic description of fast particle effects on the MHD stability in tokamaks, Ph.D. Thesis, TU Muenchen, 2003; Ph. Lauber, S. Guenter, S.D. Pinches, Phys. Plasmas 12 (2005) 122501], based on a gyrokinetic model [H. Qin, Gyrokinetic theory and computational methods for electromagnetic perturbations in tokamaks, Ph.D. Thesis, Princeton University, 1998]. A finite Larmor radius expansion together with the construction of some fluid moments and specification to the shear Alfven regime results in a self-consistent, electromagnetic, non-perturbative model, that allows not only for growing or damped eigenvalues but also for a change in mode-structure of the magnetic perturbation due to the energetic particles and background kinetic effects. Compared to previous implementations [H. Qin, mentioned above], this model is coded in a more general and comprehensive way. LIGKA uses a Fourier decomposition in the poloidal coordinate and a finite element discretisation in the radial direction. Both analytical and numerical equilibria can be treated. Integration over the unperturbed particle orbits is performed with the drift-kinetic HAGIS code [S.D. Pinches, Ph.D. Thesis, The University of Nottingham, 1996; S.D. Pinches et al., CPC 111 (1998) 131] which accurately describes the particles' trajectories. This allows finite-banana-width effects to be implemented in a rigorous way since the linear formulation of the model allows the exchange of the unperturbed orbit integration and the discretisation of the perturbed potentials in the radial direction. Successful benchmarks for toroidal Alfven eigenmodes (TAEs) and kinetic Alfven waves (KAWs) with analytical results, ideal MHD codes, drift-kinetic codes and other codes based on kinetic models are reported.

Lauber, Ph. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany)], E-mail: philipp.lauber@ipp.mpg.de; Guenter, S. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Koenies, A. [Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, EURATOM-Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Pinches, S.D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

2007-09-10

162

LIGKA: A linear gyrokinetic code for the description of background kinetic and fast particle effects on the MHD stability in tokamaks  

NASA Astrophysics Data System (ADS)

In a plasma with a population of super-thermal particles generated by heating or fusion processes, kinetic effects can lead to the additional destabilisation of MHD modes or even to additional energetic particle modes. In order to describe these modes, a new linear gyrokinetic MHD code has been developed and tested, LIGKA (linear gyrokinetic shear Alfvén physics) [Ph. Lauber, Linear gyrokinetic description of fast particle effects on the MHD stability in tokamaks, Ph.D. Thesis, TU München, 2003; Ph. Lauber, S. Günter, S.D. Pinches, Phys. Plasmas 12 (2005) 122501], based on a gyrokinetic model [H. Qin, Gyrokinetic theory and computational methods for electromagnetic perturbations in tokamaks, Ph.D. Thesis, Princeton University, 1998]. A finite Larmor radius expansion together with the construction of some fluid moments and specification to the shear Alfvén regime results in a self-consistent, electromagnetic, non-perturbative model, that allows not only for growing or damped eigenvalues but also for a change in mode-structure of the magnetic perturbation due to the energetic particles and background kinetic effects. Compared to previous implementations [H. Qin, mentioned above], this model is coded in a more general and comprehensive way. LIGKA uses a Fourier decomposition in the poloidal coordinate and a finite element discretisation in the radial direction. Both analytical and numerical equilibria can be treated. Integration over the unperturbed particle orbits is performed with the drift-kinetic HAGIS code [S.D. Pinches, Ph.D. Thesis, The University of Nottingham, 1996; S.D. Pinches et al., CPC 111 (1998) 131] which accurately describes the particles' trajectories. This allows finite-banana-width effects to be implemented in a rigorous way since the linear formulation of the model allows the exchange of the unperturbed orbit integration and the discretisation of the perturbed potentials in the radial direction. Successful benchmarks for toroidal Alfvén eigenmodes (TAEs) and kinetic Alfvén waves (KAWs) with analytical results, ideal MHD codes, drift-kinetic codes and other codes based on kinetic models are reported.

Lauber, Ph.; Günter, S.; Könies, A.; Pinches, S. D.

2007-09-01

163

Simulating Electron Cyclotron Resonance Heating in Kinetic and Dielectric Plasma Models with VORPAL  

NASA Astrophysics Data System (ADS)

We present results of electron cyclotron resonance heating (ECRH) in a plasma sustained by microwaves using VORPAL. Specifically, we look at the electron temperature, sheath size, rate of plasma formation and power absorbed for simulations with an argon gas at 10s of mTorr pressure and 2.45 GHz. We look at the effects of including elastic, inelastic and ionizing Monte Carlo collisions on the formation of the kinetic plasma. We also discuss the use of higher-order particle algorithms for smoothing out the particle current and charge which can help reduce unphysical heating in PIC simulations of high pressure, low temperature plasmas and the effect this has on sheath size and electron temperature. We then compare these simulations to a method replacing the kinetic particles with an equivalent plasma dielectric model.

Roark, Christine; Smithe, David; Stoltz, Peter

2011-11-01

164

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

165

Ion beam generation at the plasma sheet boundary layer by kinetic Alfven waves  

NASA Technical Reports Server (NTRS)

A two-dimensional quasi-linear numerical code was developed for studying ion beam generation at the plasma sheet boundary layer by kinetic Alfven waves. The model assumes that the central plasma sheet is the particle source, and that the last magnetic field lines on which kinetic Alfven waves exist and diffusion occurs can be either open or closed. As the possible source for the excitement of the kinetic Alfven waves responsible for ion diffusion, the resonant mode conversion of the surface waves to kinetic Alfven waves is considered. It is shown that, depending on the topology of the magnetic field at the lobe side of the simulation system, i.e., on whether field lines are open or closed, the ion distribution function may or may not reach a steady state.

Moghaddam-Taaheri, E.; Goertz, C. K.; Smith, R. A.

1989-01-01

166

Theory of Underdense Laser-Plasma Interactions with Photon Kinetic Theory  

NASA Astrophysics Data System (ADS)

We review recent developments in the theory of laser-plasma interactions, with a focus on generalisations of the theory of parametric instabilities driven by lasers in underdense plasmas to include the effects of broadband or partially incoherent radiation via generalised photon kinetic theory. After an introduction addressing the fundamental concepts underlying parametric instabilities, the key concepts and techniques of photon kinetic theory are presented, along with the steps required to obtain the generalised dispersion relations for the different parametric instabilities. The main details of generalised photon kinetic theory are presented such that this chapter can also be used as reference for future work on generalised photon kinetic theory. As a particular example of the application of this theoretical approach, focus will be given to the derivation of the dispersion relation for stimulated Brillouin scattering (SBS). The main results for stimulated Raman scattering (SRS) by a broadband or partially coherent radiation pump field will also be reviewed.

Silva, Luis O.; Bingham, Robert

167

A simplified chemical kinetic model for slightly ionized, atmospheric pressure nitrogen plasmas  

NASA Astrophysics Data System (ADS)

Nitrogen plasmas at atmospheric pressure produced by 2.45 GHz microwaves at a power density of approximately 10 MW m-3 have a degree of ionization less than about 10-7. Nevertheless they have interesting and potentially important effects on polymer and metal surfaces exposed to them. An experimental programme is underway to identify the active species in the plasma and its afterglow. This paper describes a simplified model of the chemical kinetics in the plasma that allows species concentrations to be estimated in a range of conditions, for comparison with experimental data. It predicts a high degree of dissociation combined with low gas temperature in microwave-generated plasmas.

Hugill, J.; Saktioto, T.

2001-02-01

168

Kinetics of plasma nitriding and renitriding of 3% Cr-Mo-V steel  

Microsoft Academic Search

Kinetic studies of plasma nitriding of 3% Cr-Mo-V DIN 39CrMoV13.9 steel were performed at 538, 510, and 483 ?C. It was found\\u000a that the process obeys a parabolic law of diffusion for total case depth and is slower than parabolic for effective case depth\\u000a formation. The kinetics of renitriding was found to be a continuation of the preexisting case growth.

E. Rolinski; D. Clubine; G. Sharp; F. LeClaire; D. Boyer; R. Notman

2000-01-01

169

Development of reduced kinetic schemes for the description of pollutants formation in combustion.  

National Technical Information Service (NTIS)

The typical dimensions of details chemical-kinetic mechanisms proposed to describe combustion systems are too large for multi-dimensional computations applications. The objective of reduction methods is to construct low- dimensional schemes that can be in...

M. Ferrendier

1998-01-01

170

Quartz crystal microbalance for the cardiac markers/antibodies binding kinetic measurements in the plasma samples  

NASA Astrophysics Data System (ADS)

The quartz crystal microbalance (QCM) was exploited for cardiac markers detection and kinetic studies of immunochemical reaction of cardiac troponin I (cTnI) and human heart fatty acid binding protein (H-FABP) with the corresponding monoclonal antibodies in undiluted plasma (serum) and standard solutions. The QCM technique allowed to dynamically monitor the kinetic differences in specific interactions and nonspecific sorption, without multiple labeling procedures and separation steps. The affinity binding process was characterized by the association (ka) and the dissociation (kd) kinetic constants and the equilibrium association (K) constant, all of which were obtained from experimental data.

Agafonova, L. E.; Shumyantseva, V. V.; Archakov, A. I.

2014-06-01

171

Theoretical description of the kinetics of solute adsorption at heterogeneous solid/solution interfaces. On the possibility of distinguishing between the diffusional and the surface reaction kinetics models  

NASA Astrophysics Data System (ADS)

The kinetics of adsorption at solid/liquid interfaces is of crucial importance for life on our planet and a variety of technological processes. Let us remark, for instance, that the oxide/electrolyte interface is the largest natural interface existing on the earth. It is very impressive to observe the growing number of the papers reporting on application of adsorption processes in the technologies of environmental protection. The purification of wastewaters, for instance, has become one of the largest industries now. To optimize the cost and performance of the adsorption technology, one has to consider both the costs of sorbents, and the efficiency of the adsorption process. That efficiency is related not only to the equilibrium features of an adsorption system but also to the kinetics of the adsorption process. In technological processes a sorbent and a solution are brought into contact for a limited period of time, so, the rate of the transport of solute molecules from the bulk to the adsorbed phase is here of a primary importance. According to some generally expressed views a sorption process can be described by four consecutive kinetic steps: transport in the bulk solution; diffusion across the film surrounding the sorbent particles; diffusion in the pores of the sorbent; sorption and desorption on the solid surface viewed as a kind of chemical reaction. One of these steps is the slowest and controls the rate of sorption. Depending on the assumption which of these steps is the rate-controlling one, a variety of equations have been proposed in literature to describe that kinetic step. The knowledge of the nature of that kinetic and its theoretical description are very crucial for practical applications, as a key to design the adsorption equipment and conditions for an optimum efficiency to be achieved. So, first some laboratory experimental tests and next their subsequent theoretical analyses are carried out to elucidate the nature of the rate-controlling kinetic process. Such studies may involve a variety of experiments whose time dependence of adsorption is the most fundamental information. Sometimes accompanying studies of the corresponding adsorption equilibria are also carried out, but it seems that the importance of these studies has not been sufficiently recognized. Only such combined study creates a chance to distinguish correctly between one and another kinetic model to be assumed. However, the most essential condition is using proper theoretical expressions to represent the features of some kind of kinetics. Here we will show how the above-mentioned conditions may affect distinguishing between the kinetics which is governed by the intraparticle diffusion, and that in which surface reactions control the rate of sorption in an adsorption system. This is because these two kinetic models are most frequently assumed in the theoretical interpretation of experimental kinetic data.

Rudzinski, Wladyslaw; Plazinski, Wojciech

2007-04-01

172

Analytical solution of the kinetic equation for a uniform plasma in a magnetic field  

SciTech Connect

The kinetic equation for a single-component uniform plasma in a magnetic field is analytically solved by the moment method. The linear system of ordinary differential equations for the moments is decomposed into subsystems of lower dimensions by a geometric method. The eigensystem of each subsystem shows that parallel moments decay monotonically, but perpendicular lth harmonic moments decay while oscillating with the l,l-2,...,-th harmonics of gyrofrequency. A generalization to a multicomponent plasma is discussed.

Ji, Jeong-Young; Held, Eric D. [Department of Physics, Utah State University, Logan, Utah 84322 (United States)

2010-07-15

173

Two new proofs of the test particle superposition principle of plasma kinetic theory  

Microsoft Academic Search

The test particle superposition principle of plasma kinetic theory is discussed in relation to the recent theory of two-time fluctuations in plasma given by Williams and Oberman. Both a new deductive and a new inductive proof of the principle are presented. The fundamental observation is that two-time expectations of one-body operators are determined completely in terms of the (x,v) phase

J. A. Krommes

1975-01-01

174

Landau damping and kinetic instability in non-Maxwellian highly electronegative multi-species plasma  

NASA Astrophysics Data System (ADS)

The effect of two negative ions on the Landau damping and stellar solar wind driven instability is analyzed using kinetic theory for the Lorentzian plasmas. It is investigated that the dispersion relations, damping rates and instability growths are appreciably modified in the presence of Generalized Lorentzian or kappa distributed function and additional negative ion in our plasma system. A quantitative measurement of the threshold value of the streaming velocity is also determined to estimate the condition of the growing instability.

Arshad, Kashif; Mirza, Arshad M.

2014-02-01

175

The kinetic studies of direct methane oxidation to methanol in the plasma process  

Microsoft Academic Search

The research outlined here includes a study of methanol production from direct methane conversion by means of thermal and\\u000a plasma method. The kinetic study, derived from thermal-based approach, was carried out to investigate thoroughly the possible\\u000a intermediate species likely to be presented in the process. A set of plasma experiments was undertaken by using dielectric\\u000a barrier discharge (DBD), classified as

Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

2008-01-01

176

Analytical Solutions to the Kinetic Theory of Neutrals in a Bounded Plasma Slab  

NASA Astrophysics Data System (ADS)

The integral equation defined on a finite interval with convolution kernel, which is the basic equation in the analytical kinetic theory of neutrals in a bounded plasma slab, is solved by reinvestigating the corresponding Riemann boundary value problem. For the case that the Fourier transform of the kernel is a rational function, a general analytical solution formalism is derived and used to calculate the density of hydrogen neutrals, without numerical means, for the cases of homogeneous and inhomogeneous plasma temperatures.

Bachmann, P.

1987-01-01

177

Obliquely propagating solitary kinetic Alfven wave in a collisional dusty plasma  

Microsoft Academic Search

An obliquely propagating solitary kinetic Alfven wave in a low beta dusty plasma (beta<plasma is re-examined. It is found that there is an upper limit of the possible Alfvenic Mach velocity,

M. H. Woo; C.-M. Ryu; C.-R. Choi

2010-01-01

178

Obliquely propagating solitary kinetic Alfven wave in a collisional dusty plasma  

Microsoft Academic Search

An obliquely propagating solitary kinetic Alfven wave in a low beta dusty plasma (?≪me\\/mi) is studied by considering the ion motion along the magnetic field and the collisional effect of electrons. The existence condition for a solitary wave for a collisionless dusty plasma is re-examined. It is found that there is an upper limit of the possible Alfvenic Mach velocity,

M. H. Woo; C.-M. Ryu; C.-R. Choi

2010-01-01

179

Calculations of kinetic behavior in the supersonic expansion of a helium plasma in a Laval nozzle  

Microsoft Academic Search

The problem of the expansion of a dense, low-temperature helium plasma in a Laval nozzle is considered. The equations of level-by-level kinetics are solved numerically together with the equations of plasma dynamics in a quasi-one-dimensional approximation. The results of the calculations and the dependence of the solutions on the initial conditions in the critical cross section are discussed. The solutions

N. V. Zakrevskii; G. A. Lukyanov; S. I. Tserkovnyi

1982-01-01

180

Growth kinetics and initial stage growth during plasma-enhanced Ti atomic layer deposition  

Microsoft Academic Search

We have investigated the growth kinetics of plasma-enhanced Ti atomic layer deposition (ALD) using a quartz crystal microbalance. Ti ALD films were grown at temperatures from 20 to 200 °C using TiCl4 as a source gas and rf plasma-produced atomic H as the reducing agent. Postdeposition ex situ chemical analyses of thin films showed that the main impurity is oxygen,

H. Kim; S. M. Rossnagel

2002-01-01

181

Kinetic dissipation and anisotropic heating in a turbulent collisionless plasma  

SciTech Connect

The kinetic evolution of the Orszag-Tang vortex is studied using collisionless hybrid simulations. In magnetohydrodynamics (MHD) this configuration leads rapidly to broadband turbulence. At large length scales, the evolution of the hybrid simulations is very similar to MHD, with magnetic power spectra displaying scaling similar to a Kolmogorov scaling of -5/3. At small scales, differences from MHD arise, as energy dissipates into heat almost exclusively through the magnetic field. The magnetic energy spectrum of the hybrid simulation shows a break where linear theory predicts that the Hall term in Ohm's law becomes significant, leading to dispersive kinetic Alfven waves. A key result is that protons are heated preferentially in the plane perpendicular to the mean magnetic field, creating a proton temperature anisotropy of the type observed in the corona and solar wind.

Parashar, T. N.; Shay, M. A.; Cassak, P. A.; Matthaeus, W. H. [Department of Physics and Astronomy, 217 Sharp Laboratory, University of Delaware, Newark, Delaware 19716 (United States)

2009-03-15

182

Exact kinetic theory for the instability of an electron beam in a hot magnetized plasma  

SciTech Connect

Efficiency of collective beam-plasma interaction strongly depends on the growth rates of dominant instabilities excited in the system. Nevertheless, exact calculations of the full unstable spectrum in the framework of relativistic kinetic theory for arbitrary magnetic fields and particle distributions were unknown until now. In this paper, we give an example of such a calculation answering the question whether the finite thermal spreads of plasma electrons are able to suppress the fastest growing modes in the beam-plasma system. It is shown that nonrelativistic temperatures of Maxwellian plasmas can stabilize only the oblique instabilities of relativistic beam. On the contrary, non-Maxwellian tails typically found in laboratory beam-plasma experiments are able to substantially reduce the growth rate of the dominant longitudinal modes affecting the efficiency of turbulent plasma heating.

Timofeev, I. V.; Annenkov, V. V. [Budker Institute of Nuclear Physics SB RAS, Novosibirsk, Russia Novosibirsk State University, Novosibirsk (Russian Federation)] [Budker Institute of Nuclear Physics SB RAS, Novosibirsk, Russia Novosibirsk State University, Novosibirsk (Russian Federation)

2013-09-15

183

Nonlocal, kinetic stimulated Raman scattering in nonuniform plasmas: Averaged variational approach  

NASA Astrophysics Data System (ADS)

Excitation of continuously phase-locked (autoresonant) plasma waves in a nonuniform plasma via stimulated Raman backscattering is analyzed with a focus on the kinetic regime (k?D~1). The dominant nonlinear effect in this regime is that of resonant particles, and the plasma wave excitation is a nonlocal process involving formation and transport of the electron phase space holes. Whitham's averaged variational principle is applied in studying the coupled plasma, laser pump, and seed waves dynamics. A flat-top electron velocity distribution is used as the simplest model allowing a variational formulation within the water bag theory. The corresponding Lagrangian, averaged over the fast phase variable, yields evolution equations for the slow field variables. The adiabatic multiple water bag extension of the theory for application to autoresonant plasma waves in nonuniform plasmas with more realistic initial distributions is also discussed. Numerical solutions of the system of slow variational equations are compared with Vlasov-Ampere simulations.

Khain, P.; Friedland, L.; Shagalov, A. G.; Wurtele, J. S.

2012-07-01

184

PIC simulation of kinetic effects of plasma and consequences for physical sputtering  

NASA Astrophysics Data System (ADS)

Impurities in a fusion plasma device such as carbon, beryllium and tungsten are one of major concerns about performance of the plasma and also engineering design. In simulation codes of impurity transport and redeposition, the physical sputtering yield due to the background plasma is calculated by an empirical model and a Monte Carlo code based on the binary collision model for a plasma without the magnetic field. In this work, kinetic effects of ions in a magnetized plasma on the physical sputtering yield were investigated by using a particle-in-cell simulation code and a sputtering model. An increasing effect of the magnetic field on the yield was found when the field was nearly parallel to the surface. The effect becomes strong when the field is strong and the plasma density is low.

Kawamura, G.; Tomita, Y.; Kirschner, A.

2011-08-01

185

EXCITATION OF KINETIC ALFVEN WAVES BY DENSITY STRIATION IN MAGNETO-PLASMAS  

SciTech Connect

Field-aligned density striation is one of the most common inhomogeneity phenomena in magneto-plasmas, such as in the solar coronal plasma and terrestrial auroral plasma. Kinetic Alfven waves (KAWs) can play an important role in the inhomogeneous heating of coronal magneto-plasmas as well as in the local acceleration of auroral energetic electrons. In this paper, we study the dispersion and instability of KAWs in a magneto-plasma with density striation structures. Results show that KAWs become unstable in the presence of the density striation and the corresponding instability has a maximal growth rate at the perpendicular wavelength close to the spatial scale of the density gradient. Related experimental phenomena in both laboratory and space plasmas are discussed. It is suggested that the excitation of KAWs by the density striation of magneto-plasmas can be of potential importance in understanding the physics of the formation of magneto-plasma filaments and their heating mechanisms, which are often present in the terrestrial auroral plasma, the solar coronal plasma, and other astrophysical plasmas.

Wu, D. J.; Chen, L., E-mail: clvslc214@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2013-07-01

186

Fully kinetic theory of drift-mirror modes in space plasmas. Electron drift-mirror instability  

NASA Astrophysics Data System (ADS)

The fully kinetic linear theory of drift-mirror (DM) instability accounting for arbitrary particle velocity distribution functions is developed. This approach includes nonzero electron temperature effects and plasma pressure anisotropy such that it contains the previous results, obtained in quasi-hydrodynamic approach, as limiting cases. In addition to the previous analysis, two novel instabilities, the hydrodynamic and kinetic electron drift-mirror (EDM) instabilities, have been revealed in the fully kinetic regime. The first one appears in the narrow range of the ion temperature anisotropies in the presence of nonzero electron temperature effects and plasma inhomogeneity below the ion mirror instability threshold. The second instability occurs in kinetic regime when the condition for the ion DM instability is satisfied. The frequency of the kinetic EDM mode is much lower than that of the ion DM mode but when the electron temperature is of the order of the parallel ion temperature the instability growth rate may become comparable or even higher than of the ion DM instability. The free energy necessary for these new instabilities is taken from two sources. On one hand, similar to the usual mirror instability, it is stored in the ion pressure anisotropy. On the other hand, the additional source of free energy arises from the electron pressure gradient which builds up in a plasma with nonzero electron temperature.

Pokhotelov, O. A.; Treumann, R. A.; Sagdeev, R. Z.; Onishchenko, O. G.; Balikhin, M. A.; Pavlenko, V. P.; Sandberg, I.

2002-10-01

187

On quantum plasma kinetic equations with a Bohmian force  

NASA Astrophysics Data System (ADS)

The dispersion relation arising from a Vlasov-Poisson system with a Bohmian force term is examined and compared to the more fundamental Bohm and Pines dispersion relation for quantum plasmas. Discrepancies are found already when considering the leading order thermal effects. The time-averaged energy densities for longitudinal modes are also shown to be noticeably different.

Haas, F.

2010-08-01

188

Generic modeling of surface reaction kinetics in plasma etching systems  

NASA Astrophysics Data System (ADS)

The complexity of both the bulk plasma phase physics and the substrate surface reaction chemistry indicate the need for simplified phenomenological modeling of etching systems. Simplified models are useful for design, analysis and control, within a reasonable time after data collection, and at modest cost. A current typical method in industry is a response surface model (an empirical polynomial), which has no predictive properties outside the range of fitted data, is completely arbitrary, and offers little physical understanding of the system. A set of generic etch rate expressions based on simplified representations of physical phenomena are presented in this dissertation. The model parameter values are regressed from data with a constrained, nonlinear optimization routine. Also presented are a statistical method for discriminating which model best represents the phenomenon of a particular etching system and a statistical model validation procedure. The benefits of this approach are a predictive, statistically validated model; the small number of model parameters may reduce the number of data points required for regression; and there is no need to re-derive a polynomial fit for each new data set. The method will be demonstrated on experimental data for chlorine plasma etching of polysilicon; tetrafluoromethane/oxygen plasma etching of polysilicon and silicon dioxide; and oxygen plasma ashing of photoresist.

Bray, Raymond Paul

189

Kinetic description of coagulation and fragmentation in dilute granular particle ensembles  

Microsoft Academic Search

We derive kinetic equations covering coagulation and fragmentation of granular gases including a combined dynamics of the mass spectrum and the velocity distribution. We will focus on coagulation, that can only occur at low impact velocities where attractive forces and dissipation prevent a post-collisional separation. We calculate an impact speed-dependent threshold velocity gc for coagulation to occur based on binary

F. Spahn; N. Albers; M. Sremcevic; C. Thornton

2004-01-01

190

Slow drift mirror modes in finite electron-temperature plasma: Hydrodynamic and kinetic drift mirror instabilities  

Microsoft Academic Search

We develop a fully kinetic linear theory of the drift mirror (DM) instability accounting for arbitrary particle velocity distribution functions including nonzero electron temperature effects and plasma pressure anisotropy. In the quasi-hydrodynamic limiting case the theory reproduces the results obtained for the ion mirror instability. However, for the very low frequency electron DM modes which can develop in a nonuniform

Oleg A. Pokhotelov; Ingmar Sandberg; Roald Z. Sagdeev; Rudolf A. Treumann; Oleg G. Onishchenko; Michael A. Balikhin; Vladimir P. Pavlenko

2003-01-01

191

Kinetic theory on the current-filamentation instability in collisional plasmas  

NASA Astrophysics Data System (ADS)

The current filamentation instability (CFI) or Weibel-type instability is studied for a nonrelativistic electron beam penetrating an infinite uniform plasma, taking into account both the collisional effects and the space-charge effect (SCE). We consider three configurations for the beam and plasma: the kinetic domain, the hydrodynamic domain, and the hybrid domain with one in kinetic and the other in hydrodynamic domain. It is shown that the CFI is determined by the current-driven drift-anisotropy rather than the classical anisotropy of the beam and the background plasma. Therefore, collisional effects can either attenuate or enhance the CFI depending on the drift-anisotropy of the beam and the background plasma. It is found that the collisional effects usually attenuate the CFI for nearly symmetric counterstreaming in the whole unstable range but enhance it for asymmetric counterstreaming in the long wavelength region both in the kinetic and the hydrodynamic domains, although the mechanisms are different. As for the case of the hybrid domain the collisional effects enhance the CFI growth rate in the long wavelength region but reduce it in the short wavelength region. The SCE can be ignored for the hydrodynamic domain while for the kinetic and the hybrid domains it is still significant though damped by the collisional effects. The combination of the SCE and the collisional effects usually reduce the CFI growth rate and suppress the unstable range further, especially in the short wavelength region.

Hao, Biao; Sheng, Z.-M.; Zhang, J.

2008-08-01

192

PLASMA KINETICS, EXCRETION IN MILK AND TISSUE LEVELS IN THE COW FOLLOWING IMPLANTATION OF TRENBOLONE ACETATE  

Microsoft Academic Search

SUMMARY The plasma kinetics of biologically stable tritiated trenbolone acetate have been studied in the barren, dry and in the lactating dairy cow following a single intravenous injection and implantation. The excretion of the compound in milk has been investigated. Tissue levels were measured 3 or 5 months following implanta- tion. The ester function is hydrolysed rapidly to yield the

J. Pottier; M. Busigny; J. A. Grandadam

2010-01-01

193

Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics  

NASA Astrophysics Data System (ADS)

The afterglow of a dusty plasma of rf discharge in argon is simulated by the particle-in-cell-Monte Carlo collision (PIC-MCC) method. The experimental observation that heavy dust contamination of plasma leads to an anomalous increase in the electron density at the beginning of afterglow is explained by release of electrons from the dust surface. Under the assumption that the floating potential of particles is in equilibrium with plasma conditions, the fast cooling of electrons in afterglow plasma due to a rapid escape of hot electrons from the volume leads to a decrease in the magnitude of the floating potential and hence to a loss of charge by dust. The intensive desorption of electrons from nanoparticles is the origin of anomalous behavior of the electron density. At the next stage of afterglow, when the electrons become cool, the plasma decay is defined by ambipolar diffusion. The effect of metastable argon atoms is also considered. Additional ionization due to metastable atom collisions affects the electron temperature but does not change the behavior of the electron density qualitatively.

Alexandrov, A. L.; Schweigert, I. V.; Ariskin, D. A.

2013-04-01

194

Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics  

SciTech Connect

The afterglow of a dusty plasma of rf discharge in argon is simulated by the particle-in-cell-Monte Carlo collision (PIC-MCC) method. The experimental observation that heavy dust contamination of plasma leads to an anomalous increase in the electron density at the beginning of afterglow is explained by release of electrons from the dust surface. Under the assumption that the floating potential of particles is in equilibrium with plasma conditions, the fast cooling of electrons in afterglow plasma due to a rapid escape of hot electrons from the volume leads to a decrease in the magnitude of the floating potential and hence to a loss of charge by dust. The intensive desorption of electrons from nanoparticles is the origin of anomalous behavior of the electron density. At the next stage of afterglow, when the electrons become cool, the plasma decay is defined by ambipolar diffusion. The effect of metastable argon atoms is also considered. Additional ionization due to metastable atom collisions affects the electron temperature but does not change the behavior of the electron density qualitatively.

Alexandrov, A. L., E-mail: a_alex@itam.nsc.ru; Schweigert, I. V.; Ariskin, D. A. [Siberian Branch of the Russian Academy of Sciences, Institute of Theoretical and Applied Mechanics (Russian Federation)

2013-04-15

195

Role of plasma activation in kinetics of carbon nanotube growth in plasma-enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

The effect of the acceleration of carbon nanotube (CNT) growth from methane via modification of the gas composition with plasma discharge is studied by means of kinetic modeling. A model of CNT growth describing the detailed gas-phase and surface kinetics of hydrocarbons in catalytic chemical vapor deposition is used. It is shown that the effect of plasma is related to the formation of active species in the gas phase that can easily adsorb and dissociate on the catalyst surface. It is also demonstrated that in addition to the adsorption of carbon precursors, the CNT growth rate can be limited by the gas-phase diffusion of carbon species to the catalyst surface. The critical energy input above which the dominant contribution to CNT growth is provided by non-radical neutral species is calculated and confirmed by analytic estimates.

Lebedeva, Irina V.; Knizhnik, Andrey A.; Gavrikov, Alexey V.; Baranov, Alexey E.; Potapkin, Boris V.; Smith, David J.; Sommerer, Timothy J.

2012-04-01

196

Kinetic dust acoustic mode in inhomogeneous partially magnetized plasma  

NASA Astrophysics Data System (ADS)

The dust acoustic mode in inhomogeneous plasmas is discussed in the regime when the electrons and ions are magnetized while at the same time the dust grains remain un-magnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species. It is shown that this may be a powerful mechanism for the excitation of dust acoustic waves. The analysis presented in this work is also applicable to plasmas containing both positive and negative ions and electrons, provided that at least one of the two ion species is un-magnetized.

Vranjes, J.; Poedts, S.

2014-05-01

197

Computer simulation of kinetic properties of plasmas. Final report  

SciTech Connect

The research was directed toward the development and testing of new numerical methods for particle and hybrid simulation of plasmas, and their application to physical problems of current significance to Magnetic Fusion Energy. This project will terminate on August 31, 1982 and this Final Report describes: (1) the research accomplished since the last renewal on October 1, 1981; and (2) a perspective of the work done since the beginning of the project in February 1972.

Denavit, J.

1982-08-01

198

Computer simulation of kinetic properties of plasmas. Final report  

SciTech Connect

The research was directed toward the development and testing of new numerical methods for particle and hybrid simulation of plasmas, and their application to physical problems of current significance in space physics and in energetic charged-particles systems. This project will terminate on August 31, 1982 and this Final Report describes (I) the research accomplished since the last renewal on April 1, 1981, and (II) a perspective of the work done since the beginning of the project in February 1972.

Denavit, J.

1982-08-01

199

One-dimensional hybrid-direct kinetic simulation of the discharge plasma in a Hall thruster  

SciTech Connect

In order to model the non-equilibrium plasma within the discharge region of a Hall thruster, the velocity distribution functions (VDFs) must be obtained accurately. A direct kinetic (DK) simulation method that directly solves the plasma Boltzmann equation can achieve better resolution of VDFs in comparison to particle simulations, such as the particle-in-cell (PIC) method that inherently include statistical noise. In this paper, a one-dimensional hybrid-DK simulation, which uses a DK simulation for heavy species and a fluid model for electrons, is developed and compared to a hybrid-PIC simulation. Time-averaged results obtained from the hybrid-DK simulation are in good agreement with hybrid-PIC results and experimental data. It is shown from a comparison of using a kinetic simulation and solving the continuity equation that modeling of the neutral atoms plays an important role for simulations of the Hall thruster discharge plasma. In addition, low and high frequency plasma oscillations are observed. Although the kinetic nature of electrons is not resolved due to the use of a fluid model, the hybrid-DK model provides spatially and temporally well-resolved plasma properties and an improved resolution of VDFs for heavy species with less statistical noise in comparison to the hybrid-PIC method.

Hara, Kentaro; Boyd, Iain D. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Kolobov, Vladimir I. [CFD Research Corporation, Huntsville, Alabama 35805 (United States)

2012-11-15

200

A DRIFT ORDERED SHORT MEAN-FREE DESCRIPTION FOR PARTIALLY IONIZED MAGNETIZED PLASMA  

SciTech Connect

Effects of neutral particles, most prominently the associated heat flux and viscosity, can be very important or even dominant at the edge of a tokamak and so must be self-consistently accounted for in a description of magnetized tokamak edge plasma. To the best of our knowledge, this has only been done so far for short mean-free path plasma under MHD-like Braginskii's orderings i.e. assuming that species velocities are on the order of the ion thermal speed. Since plasma flows in modern tokamaks are usually slow compared with the ion thermal speed (at least in the absence of strong external momentum sources) it is more appropriate to use drift orderings in which the plasma flow velocity is instead comparable with the diamagnetic heat flow divided by pressure. Employing drift orderings and evaluating species distribution functions through second order in the small gyroradius and mean-free path expansion parameters allows accounting for the important effects of heat fluxes on species momentum transport (viscosities), which are missing from the large flow ordered treatments. In this work we consider short mean-free path plasma consisting of electrons and single species of singly-charged ions and neutrals. We neglect neutral-neutral and elastic electron-neutral collisions and approximate the neutral-ion charge-exchange cross-section with a constant. We employ drift orderings to evaluate ion, neutral, and electron heat fluxes, viscosity tensors, and momentum and energy exchange terms and formulate a self-consistent system of electron, ion, and neutral fluid equations, thereby generalizing the drift-ordered treatment of fully ionized plasma.

SIMAKOV, ANDERI N. [Los Alamos National Laboratory

2007-02-08

201

The Fluid-Kinetic Particle-in-Cell method for plasma simulations  

NASA Astrophysics Data System (ADS)

A method that solves concurrently the multi-fluid and Maxwell's equations has been developed for plasma simulations. By calculating the stress tensor in the multi-fluid momentum equation by means of computational particles moving in a self-consistent electromagnetic field, the kinetic effects are retained while solving the multi-fluid equations. The Maxwell's and multi-fluid equations are discretized implicitly in time enabling kinetic simulations over time scales typical of the fluid simulations. The Fluid-Kinetic Particle-in-Cell method has been implemented in a three-dimensional electromagnetic code, and tested against the two-stream instability, the Weibel instability, the ion cyclotron resonance and magnetic reconnection problems. The method is a promising approach for coupling fluid and kinetic methods in a unified framework.

Markidis, Stefano; Henri, Pierre; Lapenta, Giovanni; Rönnmark, Kjell; Hamrin, Maria; Meliani, Zakaria; Laure, Erwin

2014-08-01

202

Arbitrary amplitude kinetic Alfvén solitary waves and double layers in a non-Maxwellian plasma  

NASA Astrophysics Data System (ADS)

To investigate the existence of kinetic Alfvén wave solitons, warm adiabatic ions and kappa distributed electrons are considered in a magnetized plasma. The kappa distribution (having the spectral index ?) is a velocity distribution that has a high energy tail but approaches the Maxwellian when ?-->?. In this work, by using the Sagdeev pseudopotential method, an exact analytical expression for arbitrary amplitude solitary kinetic Alfvén wave is derived. For different sets of plasma parameter values, the Sagdeev potential ? (?) has been calculated numerically. It is found that the spectral index ? plays a significant role in determining the shape and size of the solitary waves and double layers. Also, it is observed that both compressive solitary waves and double layers exist depending on the values of different plasma parameters.

Gogoi, Runmoni; Khan, Manoranjan

2010-11-01

203

Nonlinear excitations of kinetic Alfvén waves in electron-positron-ion plasmas  

NASA Astrophysics Data System (ADS)

A detailed study of nonlinear excitations (solitons and double layers) of kinetic Alfvén waves in low but finite-? electron-positron-ion plasma is presented using pseudopotential approach, which is valid for arbitrary wave amplitude. While sub- and super-Alfvénic solitonic structures and sub-Alfvénic double layer structures are found for both r (equilibrium positron-to-ion density ratio) <1 and r>1, super-Alfvénic double layers are found to be favorable in the region r>1. In any case, however, only compressive nonlinear excitations are found to exist. This contradicts the earlier result [H. Kakati and K. S. Goswami, Phys. Plasmas 7, 808 (2000)] predicting the existence of small-amplitude rarefactive sub- and super-Alfvénic kinetic Alfvén double layers under the assumption r<<1. The effects of positron/ion density, ion temperature, obliqueness of the wave propagation, and plasma-? on nonlinear excitations are also examined.

Sah, O. P.

2010-03-01

204

Kinetic shear Alfvén instability in the presence of impurity ions in tokamak plasmas  

SciTech Connect

The effects of impurity ions on the kinetic shear Alfvén (KSA) instability in tokamak plasmas are investigated by numerically solving the integral equations for the KSA eigenmode in the toroidal geometry. The kinetic effects of hydrogen and impurity ions, including transit motion, finite ion Larmor radius, and finite-orbit-width, are taken into account. Toroidicity induced linear mode coupling is included through the ballooning-mode representation. Here, the effects of carbon, oxygen, and tungsten ions on the KSA instability in toroidal plasmas are investigated. It is found that, depending on the concentration and density profile of the impurity ions, the latter can be either stabilizing or destabilizing for the KSA modes. The results here confirm the importance of impurity ions in tokamak experiments and should be useful for analyzing experimental data as well as for understanding anomalous transport and control of tokamak plasmas.

Lu, Gaimin; Shen, Y.; Xie, T.; He, Zhixiong; He, Hongda [Southwestern Institute of Physics, P. O. Box 432, Chengdu 610041 (China)] [Southwestern Institute of Physics, P. O. Box 432, Chengdu 610041 (China); Qi, Longyu [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)] [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Cui, Shaoyan [School of Mathematics and Information, Ludong University, Yantai 264025 (China)] [School of Mathematics and Information, Ludong University, Yantai 264025 (China)

2013-10-15

205

Kinetic Alfvén wave instability driven by field-aligned currents in a low-? plasma  

NASA Astrophysics Data System (ADS)

Kinetic Alfvén waves (KAWs) can play an important role in the energization of plasma particles and the formation of filamentous structures, which commonly are encountered and frequently accompanied by field-aligned currents in various magneto-plasmas, such as laboratory, auroral, and coronal plasmas. Based on a low-frequency kinetic dispersion equation in frequency ?plasma of ?kinetic-to-magnetic pressure ratio and Q (?me/mi?1) is the mass ratio of electrons to ions. An instability condition and the corresponding growth rate are obtained, which depends on the plasma ? parameter as well as the drift velocity VD. The results show that the KAW instability occurs in the perpendicular wave number range of k? -plasma ?parameter decreases, the growing wave number range also widens, and the maximal-growing wave number and growth rate both increase. These results have potential importance in understanding the physics of the electric current dissipation and plasma active phenomena since the field-aligned current is one of the most active factors in space and astrophysical plasmas.

Chen, L.; Wu, D. J.; Huang, J.

2013-06-01

206

0.374 Pflop\\/s trillion-particle kinetic modeling of laser plasma interaction on roadrunner  

Microsoft Academic Search

We demonstrate the outstanding performance and scalability of the VPIC kinetic plasma modeling code on the heterogeneous IBM Roadrunner supercomputer at Los Alamos National Laboratory. VPIC is a three-dimensional, relativistic, electromagnetic, particle-in-cell (PIC) code that self-consistently evolves a kinetic plasma. VPIC simulations of laser plasma interaction were conducted at unprecedented fidelity and scale-up to 1.0 times 1012 particles on as

K. J. Bowers; B. J. Albright; B. Bergen; L. Yin; K. J. Barker; D. J. Kerbyson

2008-01-01

207

Kinetic Effects in Plasmas Relevant to Hot Spot Ignition  

NASA Astrophysics Data System (ADS)

The use of radiation hydrodynamics codes to study laser-based Inertial Confinement Fusion and High Energy Density Physics is ubiquitous. In general, a single species fluid approximation is adequate during most of the interaction. However, there are critical times where electric fields, magnetic fields, or kinetic effects are potentially non-negligible. A number of examples where these effects are observed with the hybrid simulation code LSP will be presented. In particular, the effects of the tail of the electron and ion energy distributions on the fuel assembly and burn phases of hot spot ignition have been investigated in detail. The influence of electric and magnetic fields in 2-D will also be discussed.

Wilks, Scott; Amendt, P.; Bellei, C.; Williams, E.; Haines, M. G.; Welch, D.; Li, C.; Petrasso, R.

2012-10-01

208

Theoretical studies on kinetics of singlet oxygen in nonthermal plasma  

NASA Astrophysics Data System (ADS)

An idea to replace singlet delta oxygen (SDO) generator working with wet chemistry by electric discharge generator has got much attention last years. Different kinds of discharge were examined for this purpose, but without a great success. The existing theoretical models are not validated by well-characterized experimental data. To describe complicated kinetics in gas discharge with oxygen one needs to know in detail processes involving numerous electronic excited oxygen molecules and atoms. To gain new knowledge about these processes experimental studies were made on electric discharge properties in gas mixture flow with independent control of inlet SDO concentration. The theoretical model extended to include minor additives like oxygen atoms, water molecules, ozone was developed. Comparison with careful experimental measurements of electric characteristics along with gas composition allows us to verify the model and make theoretical predictions more reliable. Results of numerical simulations using this model for an electron-beam sustained discharge are reported and compared with the experimental data.

Frolov, Mikhail P.; Ionin, Andrei A.; Kotkov, Andrei A.; Kochetov, Igor V.; Napartovich, Anatolii P.; Podmarkov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

2004-09-01

209

Fully kinetic description of the linear excitation and nonlinear saturation of fast-ion-driven geodesic acoustic mode instability  

NASA Astrophysics Data System (ADS)

We show in this paper that geodesic acoustic modes (GAMs) can be efficiently excited by a population of fast ions even when Landau damping on thermal ions is accounted for. We report in particular fully kinetic calculations of the GAM dispersion relation and its complete solution. Written under a variational form, the quasi-neutrality condition, together with the kinetic Vlasov equation, leads to the density of exchanged energy between particles and the mode. In particular, a linear threshold for the GAMs excitation is derived. Two examples of fast ion distribution have been discussed analytically. It turns out that particles with high perpendicular energy compared to the parallel resonance energy are most responsible for the excitation of the mode. Subsequent numerical simulations of circular plasmas using gysela code have been carried out. In particular, the linear kinetic threshold has been reproduced during the excitation phase, and a nonlinear saturation has been observed. Analysis in the phase space of the evolution of the equilibrium distribution function is presented and the saturation level quantified.

Zarzoso, D.; Garbet, X.; Sarazin, Y.; Dumont, R.; Grandgirard, V.

2012-02-01

210

Retooling the creatinine clearance equation to estimate kinetic GFR when the plasma creatinine is changing acutely.  

PubMed

It is often desirable to estimate the GFR (eGFR) at the bedside to assess AKI or renal recovery. Current eGFR equations estimate kidney function when the plasma creatinine is stable, but do not work if the plasma creatinine is changing rapidly. To analyze kidney function in the acute setting, a simple formula is proposed that requires only a modest number of inputs that are readily obtainable from clinical laboratory data. The so-called kinetic eGFR (KeGFR) formula is derived from the initial creatinine content, volume of distribution, creatinine production rate, and the quantitative difference between consecutive plasma creatinines over a given time. For that period, the deciphered creatinine excretion then yields the creatinine clearance rate. The additional formula variables needed are any steady-state plasma creatinine, the corresponding eGFR by an empirical formula, and the maximum increase in creatinine per day if anuric. The kinetic formula complements clinical intuition but also adds a quantitative and visual dimension to the assessment of kidney function, demonstrated by its analysis of GFRs underlying the plasma creatinine fluctuations in several scenarios of AKI or renal recovery. Deduced from first principles regarding the physiology of creatinine balance, the KeGFR formula enhances the fundamental clearance equation with the power and versatility to estimate the kidney function when the plasma creatinine is varying acutely. PMID:23704286

Chen, Sheldon

2013-05-01

211

Quantification of transthyretin kinetic stability in human plasma using subunit exchange.  

PubMed

The transthyretin (TTR) amyloidoses are a group of degenerative diseases caused by TTR aggregation, requiring rate-limiting tetramer dissociation. Kinetic stabilization of TTR, by preferential binding of a drug to the native tetramer over the dissociative transition state, dramatically slows the progression of familial amyloid polyneuropathy. An established method for quantifying the kinetic stability of recombinant TTR tetramers in buffer is subunit exchange, in which tagged TTR homotetramers are added to untagged homotetramers at equal concentrations to measure the rate at which the subunits exchange. Herein, we report a subunit exchange method for quantifying the kinetic stability of endogenous TTR in human plasma. The subunit exchange reaction is initiated by the addition of a substoichiometric quantity of FLAG-tagged TTR homotetramers to endogenous TTR in plasma. Aliquots of the subunit exchange reaction, taken as a function of time, are then added to an excess of a fluorogenic small molecule, which immediately arrests further subunit exchange. After binding, the small molecule reacts with the TTR tetramers, rendering them fluorescent and detectable in human plasma after subsequent ion exchange chromatography. The ability to report on the extent of TTR kinetic stabilization resulting from treatment with oral tafamidis is important, especially for selection of the appropriate dose for patients carrying rare mutations. This method could also serve as a surrogate biomarker for the prediction of the clinical outcome. Subunit exchange was used to quantify the stabilization of WT TTR from senile systemic amyloidosis patients currently being treated with tafamidis (20 mg orally, once daily). TTR kinetic stability correlated with the tafamidis plasma concentration. PMID:24661308

Rappley, Irit; Monteiro, Cecília; Novais, Marta; Baranczak, Aleksandra; Solis, Gregory; Wiseman, R Luke; Helmke, Stephen; Maurer, Mathew S; Coelho, Teresa; Powers, Evan T; Kelly, Jeffery W

2014-04-01

212

Hypovalency--a kinetic-energy density description of a 4c-2e bond.  

PubMed

A bond descriptor based on the kinetic energy density, the localized-orbital locator (LOL), is used to characterize the nature of the chemical bond in electron deficient multi-center bonds. The boranes B(2)H(6), B(4)H(4), B(4)H(10), [B(6)H(6)](2-), and [B(6)H(7)](-) serve as prototypical examples of hypovalent 3c-2e and 4c-2e bonding. The kinetic energy density is derived from a set of Kohn-Sham orbitals obtained from pure density functional calculations (PBE/TZVP), and the topology of LOL is analyzed in terms of (3,-3) attractors (Gamma). The B-B-B and B-H-B 3c-2e, and the B-B-H-B 4c-2e bonding situations are defined by their own characteristic LOL profiles. The presence of one attractor in relation to the three or four atoms that are engaged in electron deficient bonding provides sufficient indication of the type of 3c-2e or 4c-2e bond present. For the 4c-2e bond in [B(6)H(7)](-) the LOL analysis is compared to results from an experimental QTAIM study. PMID:19452076

Jacobsen, Heiko

2009-06-01

213

Kinetic theory of a two-dimensional magnetized plasma.  

NASA Technical Reports Server (NTRS)

Several features of the equilibrium and nonequilibrium statistical mechanics of a two-dimensional plasma in a uniform dc magnetic field are investigated. The charges are assumed to interact only through electrostatic potentials. The problem is considered both with and without the guiding-center approximation. With the guiding-center approximation, an appropriate Liouville equation and BBGKY hierarchy predict no approach to thermal equilibrium for the spatially uniform case. For the spatially nonuniform situation, a guiding-center Vlasov equation is discussed and solved in special cases. For the nonequilibrium, nonguiding-center case, a Boltzmann equation, and a Fokker-Planck equation are derived in the appropriate limits. The latter is more tractable than the former, and can be shown to obey conservation laws and an H-theorem, but contains a divergent integral which must be cut off on physical grounds. Several unsolved problems are posed.

Vahala, G.; Montgomery, D.

1971-01-01

214

A comparison of kinetic and multifluid simulations of laser-produced colliding plasmas  

SciTech Connect

The collision and subsequent interaction of counter-streaming plasmas occurs in several areas of laser-plasma research including double foil targets for x-ray lasers and the plasma blow-off inside ICF hohlraums. Because a single fluid model allows for only one value of the flow velocity at any one spatial location, interpenetration of the plamas is not allowed resulting in immediate stagnation with complete conversion of the ion-streaming kinetic energy to thermal energy. Multifluid models have been developed which employ multiple ion fluid species that interact through the self-consistent electrostatic field and collisional coupling. Because they are approximations to a kinetic situation, the form of these coupling coefficients is not unique, with various workers using differing approximations. More recently, Larroche has implemented a finite difference approach to the ion Fokker-Planck equation while Jones and co-workers have performed two-dimensional simulations of colliding plasmas using a particle-in-cell code with a new collisional model. Our kinetic modeling also makes use of particle in cell (PIC) techniques with Monte Carlo (MC) particle-particle collisions algorithm that is equivalent to the Fokker-Planck collision operator. We have made direct comparison of this MC-PIC model to multifluid simulations on both simple slowing-down and equilibration problems as well as problems characteristic of laser generated colliding plasmas. These comparisons have established the validity of the multifluid model as well as aided in the development of the kinetic capability for more challenging geometries.

Rambo, P.W.; Procassini, R.J.

1994-09-01

215

Kinetic Processes and Plasma Remediation of Toxic Gases  

NASA Astrophysics Data System (ADS)

Regulations on the allowable emissions of toxic gases have resulted in increasing industrial interest in the development of energy efficient methods for remediation. In this work we computationally study the application of Dielectric Barrier Discharges to the remediation of perchloroethylene (C_2Cl_4 or PCE) and N_{x}O _{y}. We determine the kinetic processes that occur in remediation in order to devise methods for improving the energy efficiency of remediation. PCE remediation progresses by a chain chemistry. Removal is efficient in humid gas streams since reactions of H _2O initiate the production of radicals necessary for remediation. The end products can be further treated by conventional methods and then exhausted. Processes during N_{x }O_{y} remediation can be considered in terms of three time regimes. During the pulse, radicals are produced. NO and N_{x}O_{y } are then remediated. At long times NO is converted to NO_2 with no net change in N_{x}O _{y}. Remediation of NO is largely due to reduction by N. Removal is more efficient with higher applied voltage, faster rising pulses, more H_2O in the gas stream, and more pulses of lower energy. Spatial dependencies can affect the energy efficiencies of remediation. Localized energy deposition in the streamer can result in high temperatures facilitating production of NO. Diffusion of NO into the streamer region and advective transport of N outward into the bulk gas increase remediation. At very high energy depositions, transport decreases the instantaneous rate of change of efficiency with energy deposition despite the increased temperature.

Gentile, Ann Catherine

216

Kinetic study of the secondary plasma created in the ITER neutraliser  

NASA Astrophysics Data System (ADS)

The properties of the secondary plasma created inside the ITER Neutral Beam Injector (NBI) neutraliser, through the interaction of the high energetic hydrogen beam with the molecular hydrogen gas, have been analysed. Starting from the results of our OBI-2 PIC Monte-Carlo numerical code, detailed kinetic of the hydrogen plasma has been studied using a Collisional-Radiative model. In this model, the electron distribution function is determined by solving a Boltzmann equation, whereas main plasma species are derived from balance equations. This paper presents preliminary results obtained in a 0D geometry, boundary conditions bing introduced through effective rates for gain and loss of particles at the neutraliser walls. It has been found that the main ion specie is H2+, essentially coming from the ionisation of the target gas. The electron energy distribution function is not maxwellian and its mean energy is about 5 eV. The plasma-wall interactions yield a strong contribution, in particular regarding the density of molecular ion H3+. Assuming several independent slices of plasma along the negative ions beam axis, the axial profile of the secondary plasma has been analysed. It has been found that the density and mean energy profiles of the plasma electrons are directly related to the plasma potential profile, which in turn closely follows the gas density one.

Dure, F.; Lifschitz, A.; Bretagne, J.; Maynard, G.; Katsonis, K.; Simonin, A.; Minea, T.

2009-03-01

217

Kinetic study of the secondary plasma created in the ITER neutraliser  

SciTech Connect

The properties of the secondary plasma created inside the ITER Neutral Beam Injector (NBI) neutraliser, through the interaction of the high energetic hydrogen beam with the molecular hydrogen gas, have been analysed. Starting from the results of our OBI-2 PIC Monte-Carlo numerical code, detailed kinetic of the hydrogen plasma has been studied using a Collisional-Radiative model. In this model, the electron distribution function is determined by solving a Boltzmann equation, whereas main plasma species are derived from balance equations. This paper presents preliminary results obtained in a 0D geometry, boundary conditions bing introduced through effective rates for gain and loss of particles at the neutraliser walls. It has been found that the main ion specie is H{sub 2}{sup +}, essentially coming from the ionisation of the target gas. The electron energy distribution function is not maxwellian and its mean energy is about 5 eV. The plasma-wall interactions yield a strong contribution, in particular regarding the density of molecular ion H{sub 3}{sup +}. Assuming several independent slices of plasma along the negative ions beam axis, the axial profile of the secondary plasma has been analysed. It has been found that the density and mean energy profiles of the plasma electrons are directly related to the plasma potential profile, which in turn closely follows the gas density one.

Dure, F.; Lifschitz, A.; Bretagne, J.; Maynard, G.; Katsonis, K.; Minea, T. [LPGP, CNRS-Universite Paris Sud, Orsay (France); Simonin, A. [DRFC, CEA Cadarache, 13108 Saintt-Paul lez Durance (France)

2009-03-12

218

Kinetics of complex plasmas having spherical dust particles with a size distribution  

SciTech Connect

This paper presents an analysis of the kinetics of an illuminated complex plasma having spherical dust particles with a size distribution. It has been pointed out that in the steady state, the electric potential on the surface of all the particles is the same; as a corollary, all particles carry a charge of the same sign. It is seen that in the steady state, the plasma parameters are determined by the number per unit volume and root mean square radius of the dust particles. This fact makes the analysis similar to that for a complex plasma with dust of uniform size. It is seen that it is essential to consider both the number and energy balance of the constituents of the complex plasma. A parametric analysis, a discussion of the numerical results thus obtained, and conclusions have also been given.

Sodha, M. S. [Disha Institute of Management and Technology, Satya Vihar, Vidhan Sabha-Chandrakhuri Marg, Mandir Hasaud, Raipur, 492101 Chhattisgarh (India); Misra, Shikha; Mishra, S. K. [Department of Education Building, University of Lucknow, Lucknow 226007 (India)

2010-11-15

219

Ion kinetic energies in inductively coupled plasma/mass spectrometry (ICP-MS)  

SciTech Connect

Ion kinetic energies in an inductively coupled plasma/mass spectrometer (ICP-MS) system have been measured with the use of a retarding potential on the analyzing quadrupole. The energies differ markedly from those previously reported in the literature. This is attributed to the elimination of any arcing of the ICP to the sampling orifice or skimmer of the ICP-MS system. In the absence of secondary discharge effects, the ion energies increase with the mass of the ion and are consistent with those expected from molecular beam sampling from a plasma with a temperature of --5000 K and a potential of --2 V. Ion energies are found to be virtually independent of aerosol gas flow, plasma power, and sample matrix composition, allowing independent optimization of plasma parameters and ion optics.

Fulford, J.E.; Douglas, D.J.

1986-09-01

220

A coarse-grained kinetic equation for neutral particles in turbulent fusion plasmas  

SciTech Connect

A coarse-grained kinetic equation for neutral particles (atoms, molecules) in magnetized fusion plasmas, valid on time scales large compared to the turbulence correlation time, is presented. This equation includes the effects of plasma density fluctuations, described by gamma statistics, on the transport of neutral particles. These effects have so far been neglected in plasma edge modeling, in spite of the fact that the amplitude of fluctuations can be of order unity. Density fluctuations are shown to have a marked effect on the screening of neutrals and on the spatial localization of the ionization source, in particular at high density. The coarse-grained equations obtained in this work are readily implemented in edge code suites currently used for fusion plasma analysis and future divertor design (ITER, DEMO).

Mekkaoui, A.; Marandet, Y.; Genesio, P.; Rosato, J.; Stamm, R.; Capes, H.; Koubiti, M.; Godbert-Mouret, L. [PIIM, CNRS/Aix-Marseille Univ., Marseille F-13397 Cedex 20 (France); Reiter, D.; Boerner, P. [IEK-4 Plasmaphysik, Forschungszentrum Juelich GmbH, TEC Euratom association, D-52425 Juelich (Germany); Catoire, F. [CELIA, UMR5107 CNRS-CEA-Universite de Bordeaux I, Talence F-33405 (France)

2012-06-15

221

Chemical kinetics of an argon/methane plasma in a hydrogen reforming reactor  

NASA Astrophysics Data System (ADS)

We have studied the characteristics of a plasma reactor for the promotion of chemical reactions aimed to hydrogen reforming from gaseous hydrocarbons. A plasma torch-like electrode configuration was powered by a limited current, high voltage DC source. Using as process gas an argon/methane mixture at atmospheric pressure, we have produced an intermittent spark discharge which has been investigated at different operating parameters. Experimental information on the discharge have been used to perform a numerical simulation of the plasma chemical kinetics. The evolution of the gas-phase composition during and after the interaction in the discharge region was calculated under different operating conditions. The results have been used to predict the hydrogen production yield in the experiments and to study the role played by the different discharge parameters in order to determine the optimal interaction between plasma and gas mixture.

Barni, R.; Benocci, R.; Broggi, C.; Riccardi, C.

2006-08-01

222

Spectral evolution of two-dimensional kinetic plasma turbulence in the wavenumber-frequency domain  

SciTech Connect

We present a method for studying the evolution of plasma turbulence by tracking dispersion relations in the energy spectrum in the wavenumber-frequency domain. We apply hybrid plasma simulations in a simplified two-dimensional geometry to demonstrate our method and its applicability to plasma turbulence in the ion kinetic regime. We identify four dispersion relations: ion-Bernstein waves, oblique whistler waves, oblique Alfvén/ion-cyclotron waves, and a zero-frequency mode. The energy partition and frequency broadening are evaluated for these modes. The method allows us to determine the evolution of decaying plasma turbulence in our restricted geometry and shows that it cascades along the dispersion relations during the early phase with an increasing broadening around the dispersion relations.

Comi?el, H. [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany) [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany); Institute for Space Sciences, Atomi?tilor 409, P.O. Box MG-23, Bucharest-M?gurele RO-077125 (Romania); Verscharen, D. [Space Science Center, University of New Hampshire, 8 College Rd., Durham, New Hampshire 03824 (United States)] [Space Science Center, University of New Hampshire, 8 College Rd., Durham, New Hampshire 03824 (United States); Narita, Y. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz (Austria)] [Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz (Austria); Motschmann, U. [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany) [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany); Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Rutherfordstr. 2, D-12489 Berlin (Germany)

2013-09-15

223

Kinetic Alfvén wave instability driven by a field-aligned current in high-? plasmas.  

PubMed

Including the ion-gyroradius effect, a general low-frequency kinetic dispersion equation is presented, which simultaneously takes account of a field-aligned current and temperature anisotropy in plasmas. Based on this dispersion equation, kinetic Alfvén wave (KAW) instability driven by the field-aligned current, which is carried by the field-aligned drift of electrons relative to ions at a drift velocity V(D), is investigated in a high-? plasma, where ? is the kinetic-to-magnetic pressure ratio in the plasma. The numerical results show that the KAW instability driven by the field-aligned current has a nonzero growth rate in the parallel wave-number range 0plasma particles, the result shows that the instability conditions for these two driven mechanisms are both modified considerably, in which the growing parametric ranges of KAWs widen. The results have potential importance in understanding the physics of space and astrophysical plasma active phenomena since the field-aligned current, also called the Birkeland current, is one of the most active factors in plasma phenomena. PMID:22181282

Chen, L; Wu, D J; Hua, Y P

2011-10-01

224

Parametric study of kinetic Alfvén solitons in a two electron temperature plasma  

NASA Astrophysics Data System (ADS)

The nonlinear regime of the kinetic Alfvén wave is studied in a collisionless low-? plasma that is composed of a cold ion population and of two electron populations. In the one electron population plasma, it is known that solitary kinetic Alfvén waves (SKAW) propagate either at the Alfvén velocity ?A or at the ion-acoustic velocity cs. In this latter case, only plasma compressions exist. In the two electron population plasma, rarefactions, as well as compressions, may exist at this velocity. Furthermore, when the electron-acoustic mode exists and when ?A>?ea (vea is the electron-acoustic velocity), the inertia of the cold electron component allows for the existence of compressive SKAW which propagate with a velocity lying in a limited interval above ?ea. When ?Aplasma observations is investigated.

Berthomier, Matthieu; Pottelette, Raymond; Treumann, Rudolf A.

1999-02-01

225

One-dimensional solitary kinetic Alfvén waves in low-beta plasma  

NASA Astrophysics Data System (ADS)

A two-dimensional homogeneous magnetohydrodynamic (MHD) model is applied to investigate one-dimensional solitary kinetic Alfvén waves (SKAWs) and their degenerated ion-acoustic solitons in a low-beta plasma, in which electron pressure and electron inertial effects are all taken into account. In contrast to the results of the one-dimensional SKAWs model obtained by Hasegawa and Mima [Phys. Rev. Lett. 37, 690 (1976)], Shukla et al. [J. Plasma Phys. 28, 125 (1982)], and Wu et al. [Phys. Plasmas 3, 2879 (1996)], both density hump and dip Alfvénic solitons are found to exist in the kinetic limit (2me/mi<plasma thermal pressure to the magnetic pressure), while in the transition region (?-2me/mi), both super-Alfvénic and sub-Alfvénic solitons with a density hump or a dip are found to exist. Due to the finite-? effect, the Alfvénic solitons may degenerate into super-acoustic density hump solitons over all the range of plasma ?. This result provides a one-dimensional SKAWs model to account for the observations from the Freja satellite, in which not only SKAWs accompanied by dip density solitons, but also SKAWs accompanied by hump density solitons, are found in the Earth's ionospheric altitude.

Wang, Xu-Yu; Wang, Xue-Yi; Liu, Zhen-Xing; Li, Zhong-Yuan

1998-12-01

226

On PIC-Fokker-Planck hybrid for kinetic modeling of plasmas  

NASA Astrophysics Data System (ADS)

Traditional approach to kinetic simulation of plasmas utilizes either PIC or Vlasov (Fokker-Planck) method. There are well known shortcomings for both of the approaches. For instance, PIC suffers from high statistical noise, while Vlasov shows high numerical diffusion. New hybrid method [1] combines best features of the two methods by suppressing both numerical noise and numerical diffusion. Relative effectiveness of PIC, Vlasov and hybrid methods is demonstrated for a classical problem of non-linear saturation of a strong beam-plasma instability [2]. Further development of the hybrid PIC-Vlasov method [4] for the kinetic modeling of mixed-collisional plasma is discussed. First results on coupling of our hybrid particle-mesh method with adaptive RRC method [3], which uses adaptive grid refinement and coarsening, are presented. [1] O.Batishchev, Proc. 17th Int. Conf. on Num. Sim. Plasmas, p.24, Banff, Canada, May 2000; [2] O.Batishchev et al., Bull. APS 45 (7) 72, APS DPP meeting, Quebec City, Canada, October 2000; [3] A.Batishcheva and O.Batishchev, Proc. 17th Int. Conf. on Num. Sim. Plasmas, p.29, 2000; [4] O.Batishchev, APS DcomP-2001 meeting, R1.025, Cambridge, June 2001.

Batishchev, Oleg

2001-10-01

227

Arbitrary amplitude kinetic Alfvén solitons in a plasma with a q-nonextensive electron velocity distribution  

NASA Astrophysics Data System (ADS)

Arbitrary amplitude solitary kinetic Alfvén waves (KAWs) in a plasma with q-nonextensive electrons are investigated by the conventional Sagdeev pseudopotential method, through which the existence of solitary KAWs is analyzed theoretically and numerically. It is shown only solitons with density hump can exist, the amplitude of which depends sensitively on the parameter q and the plasma ?. There is an upper limit for the amplitude of solitary wave which decreases with the increase of q and ?. The results obtained in the framework of Maxwellian distribution are reproduced when q --> 1.

Liu, Y.; Liu, S. Q.; Dai, B.

2011-09-01

228

Calculations of kinetic behavior in the supersonic expansion of a helium plasma in a Laval nozzle  

SciTech Connect

The problem of the expansion of a dense, low-temperature helium plasma in a Laval nozzle is considered. The equations of level-by-level kinetics are solved numerically together with the equations of plasma dynamics in a quasi-one-dimensional approximation. The results of the calculations and the dependence of the solutions on the initial conditions in the critical cross section are discussed. The solutions are compared with a model approximation of a stationary sink and experimental results, showing their satisfactory agreement.

Zakrevskii, N.V.; Luk'yanov, G.A.; Tserkovnyi, S.I.

1982-07-01

229

Kinetic theory of chiral relativistic plasmas and energy density of their gauge collective excitations  

NASA Astrophysics Data System (ADS)

We use the recently developed kinetic theory with Berry curvature to describe the fermions and antifermions of a chiral relativistic plasma. We check that this transport approach allows us to reproduce the chiral anomaly equation of relativistic quantum field theory at finite temperature. We also check that it allows us to describe the anomalous gauge polarization tensor that appears in the hard thermal (and/or dense) effective field theory. We also construct an energy density associated to the gauge collective modes of the chiral relativistic plasma, valid in the case of small couplings or weak fields, which can be the basis for the study of their dynamical evolution.

Manuel, Cristina; Torres-Rincon, Juan M.

2014-05-01

230

Kinetic temperature of dust particle motion in gas-discharge plasma.  

PubMed

A system of equations describing motion of dust particles in gas discharge plasma is formulated. This system is developed for a monolayer of dust particles with an account of dust particle charge fluctuations and features of the discharge near-electrode layer. Molecular dynamics simulation of the dust particles system is performed. A mechanism of dust particle average kinetic energy increase is suggested on the basis of theoretical analysis of the simulation results. It is shown that heating of dust particles' vertical motion is initiated by forced oscillations caused by the dust particles' charge fluctuations. The process of energy transfer from vertical to horizontal motion is based on the phenomenon of the parametric resonance. The combination of parametric and forced resonances explains the abnormally high values of the dust particles' kinetic energy. Estimates of frequency, amplitude, and kinetic energy of dust particles are close to the experimental values. PMID:22181522

Norman, G E; Timofeev, A V

2011-11-01

231

Von Kármán energy decay and heating of protons and electrons in a kinetic turbulent plasma.  

PubMed

Decay in time of undriven weakly collisional kinetic plasma turbulence in systems large compared to the ion kinetic scales is investigated using fully electromagnetic particle-in-cell simulations initiated with transverse flow and magnetic disturbances, constant density, and a strong guide field. The observed energy decay is consistent with the von Kármán hypothesis of similarity decay, in a formulation adapted to magnetohydrodyamics. Kinetic dissipation occurs at small scales, but the overall rate is apparently controlled by large scale dynamics. At small turbulence amplitudes the electrons are preferentially heated. At larger amplitudes proton heating is the dominant effect. In the solar wind and corona the protons are typically hotter, suggesting that these natural systems are in the large amplitude turbulence regime. PMID:24093244

Wu, P; Wan, M; Matthaeus, W H; Shay, M A; Swisdak, M

2013-09-20

232

Kinetics and continuum emission of negative atomic ions in partially ionized plasmas  

NASA Technical Reports Server (NTRS)

Kinetics and continuum emission of negative ions are studied in stationary atomic hydrogen, nitrogen, and oxygen plasmas. The intensity of the negative-ion emission was found to be neglibible when compared to those of bound-bound and free-bound emission at low and medium particle densities. However, the negative-ion continuum emission can contribute significantly in certain parts of the emission spectrum at high particle densities.

Soon, W. H.; Kunc, J. A.

1991-01-01

233

Electron Acceleration by Small-Amplitude Solitary Kinetic Alfvén Wave in a Low-Beta Plasma  

NASA Astrophysics Data System (ADS)

In the case of a low beta plasma ? ll me/mi, the electron acceleration by small amplitude solitary kinetic Alfvén wave is studied. It is found that the electron can be only accelerated along the ambient magnetic field. The maximum velocity of accelerated electron approaches to twice Alfvén velocity. In the perpendicular direction, the dc electric field acceleration term and surfing acceleration term almost cancel each other out.

Wang, De-Yu; Song, Qi-Wu; Yang, Lei

2008-02-01

234

Disposition kinetics of mebendazole in plasma, milk and ruminal fluid of goats  

Microsoft Academic Search

The experiment was designed to study the kinetics of mebendazole (MBZ) after single dose i.v. (5 mg\\/kg) and oral (40 mg\\/kg) administration in two separate groups of six Black Bengal female goats in each group. The plasma half-life (t12?) and total body clearance (CLB) calculated after an i.v. dose were 23.15 ± 6.71 h and 0.11 ± 0.04 ml kg?1

S. N. Pandey; B. K. Roy

1998-01-01

235

Kinetic Description of Ionospheric Outflows Based on the Exact Form of Fokker-Planck Collision Operator: Electrons  

NASA Technical Reports Server (NTRS)

We present the results of a finite difference implementation of the kinetic Fokker-Planck model with an exact form of the nonlinear collisional operator, The model is time dependent and three-dimensional; one spatial dimension and two in velocity space. The spatial dimension is aligned with the local magnetic field, and the velocity space is defined by the magnitude of the velocity and the cosine of pitch angle. An important new feature of model, the concept of integration along the particle trajectories, is discussed in detail. Integration along the trajectories combined with the operator time splitting technique results in a solution scheme which accurately accounts for both the fast convection of the particles along the magnetic field lines and relatively slow collisional process. We present several tests of the model's performance and also discuss simulation results of the evolution of the plasma distribution for realistic conditions in Earth's plasmasphere under different scenarios.

Khazanov, George V.; Khabibrakhmanov, Ildar K.; Glocer, Alex

2012-01-01

236

The temporal evolution of the kinetic drift-Alfven instability of plasma shear flow  

NASA Astrophysics Data System (ADS)

The linear non-modal kinetic theory of the kinetic drift-Alfven instability, in the presence of shearing plasma flow, exhibits temporal non-modal amplitude growth with time-increasing growth rate. The drift-Alfven instability develops when the evolving frequencies of the density-gradient-driven drift wave and the kinetic Alfven wave become comparable and mode coupling increases significantly. Because the development of the instability depends on the plasma density gradient, drift-Alfven turbulence may be invoked as a possible turbulence driver in the edge pedestal, limiting the pedestal density gradients during the edge localized modes crash. In contrast to the case of shear-modified electrostatic drift-wave turbulence, the scattering of plasma ions by the shear-modified electromagnetic drift-Alven turbulence does not only suppress the turbulence, but can be responsible for transient increase in the instability's growth rate. The instability, i.e., turbulence, stabilizes when the drift and Alfven wave frequencies eventually become different enough that effective coupling between the two modes ends. So, perpendicular-flow shear can cause the growth rate to increase, decrease, become zero, and become negative as a result of shear's time-changing modification to the frequencies of the drift and Alfven waves.

Mikhailenko, V. V.; Mikhailenko, V. S.; June Lee, Hae; Koepke, M. E.

2014-03-01

237

Kinetic simulation of a hot spot formation in high-Z plasma  

NASA Astrophysics Data System (ADS)

The so-called "hot spots" formed in a plasma heated by lasers having transverse spatial modulations give rise to steep temperature gradients with the scale comparable to the electron-ion mean free path. This indicates that the nonlocal transport effects can be important. Both the spatial transport and non-uniform heating of electrons by strong laser field may cause significant deviation of the electron distribution function (EDF) from the Maxwellian [1,2]. To study inhomogeneous hot spot formation we deploy 1D2V Fokker-Planck code ALLA [3], which includes e-e and e-i collisions, ambipolar electric field, and inverse bremsstrahlung plasma heating. Unlike particle methods it's free of statistical fluctuations and allows more accurate resolution of the EDF tail that is important to study the reduction of the electron plasma wave damping. We present results of the kinetic simulations with hot spots of various shapes and intensities, as well as a comparison with the results for homogeneous plasma heating and analytical models for EDF in high Z-plasmas. [1] A.B.Langdon, Phys.Rev.Lett. 44, 575 (1980); [2] E.Fourkal, V.Yu.Bychenkov, W.Rozmus et al., Phys. Plasmas 8 (2) 550 (2001); [3] O.Batishchev et al., J.Plasma Phys. 61 (3) 347 (1999).

Batishchev, Oleg; Bychenkov, Valery; Rozmus, Wojciech

2001-06-01

238

ASTROPHYSICAL GYROKINETICS: KINETIC AND FLUID TURBULENT CASCADES IN MAGNETIZED WEAKLY COLLISIONAL PLASMAS  

SciTech Connect

This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulent motions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the 'inertial range' above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvenic fluctuations and a passive cascade of density and magnetic-field-strength fluctuations. The former are governed by the reduced magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvenic component (in the collisional limit, these compressive fluctuations become the slow and entropy modes of the conventional MHD). In the 'dissipation range' below ion gyroscale, there are again two cascades: the kinetic-Alfven-wave (KAW) cascade governed by two fluid-like electron reduced magnetohydrodynamic (ERMHD) equations and a passive cascade of ion entropy fluctuations both in space and velocity. The latter cascade brings the energy of the inertial-range fluctuations that was Landau-damped at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAW energy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for all of these cascades. The relationship between the theoretical models proposed in this paper and astrophysical applications and observations is discussed in detail.

Schekochihin, A. A. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP (United Kingdom); Cowley, S. C. [Plasma Physics, Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); Dorland, W.; Tatsuno, T. [Department of Physics, University of Maryland, College Park, MD 20742-3511 (United States); Hammett, G. W. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Howes, G. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242-1479 (United States); Quataert, E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)], E-mail: a.schekochihin1@physics.ox.ac.uk

2009-05-15

239

The LANL atomic kinetics modeling effort and its application to W plasmas  

SciTech Connect

This is the work of the LANL group on atomic kinetics modelling. There are various levels of detail in the LANL suite of atomic physics codes: (1) Non-relativistic configuration average kinetics (nl{sup w}) + UTA spectra, (2) Relativistic configuration average kinetics (nlj{sup w}) + UTA spectra, (3) Mixed UTA (MUTA) - configuration average kinetics and spectra composed of mixture of UTAs and fine-structure features and (4) Fine-structure levels. The LANL suite of atomic physics codes consists of 5 codes: (1) CATS/RATS atomic structure codes (semi-relativistic Cowan code or Dirac-Fock-Slater code), (2) ACE collisional excitation code (Plane-wave Born, Columb-Born and distorted-wave methods) and (3) GIPPER ionization code (scaled-hydrogenic and distorted-wave methods). An on-line version of the codes is available at http://aphysics2.lanl.gov/tempweb. ATOMIC kinetics modelling code uses the atomic data for LTE or NLTE population kinetics models and spectral modelling of a broad range of plasma applications. The mixed UTA (MUTA) approach was developed for the spectra of complex ions and the results are in very good agreement with the Sandia-Z Iron opacity experiments. The LANL configuration-average/MUTA calculations were applied to tungsten problems of the non-LTE kinetics code comparison workshops. The LANL group plans to perform much larger calculations to assess the accuracy of the older results and to investigate low-temperature tungsten processes relevant to the divertor modelling.

Colgan, James [Los Alamos National Laboratory; Abdallah, Joseph [Los Alamos National Laboratory; Fontes, Christopher [Los Alamos National Laboratory; Zhang, Honglin [Los Alamos National Laboratory

2010-12-10

240

Nonlinear Interaction of 3D Kinetic Alfvén Waves and Ion Acoustic Waves in Solar Wind Plasmas  

NASA Astrophysics Data System (ADS)

We have investigated the nonlinear interaction between a 3D kinetic Alfvén wave (KAW) and an ion acoustic wave (IAW) in solar wind plasmas. A set of dimensionless equations was developed that describes the pump KAW perturbed by a low-frequency ion acoustic wave. The dependence of the growth rate of the modulational instability on the perturbation wave number was studied. We simulated numerically the dynamical equation of KAW with a pseudo-spectral method, taking ponderomotive nonlinearity into account. The 3D KAW itself propagates in the form of a vortex beam in a magnetised plasma, which manifests the presence of orbital angular momentum of the wave eigenmodes. We discuss the evolution of these vortex structures. Our results reveal that the Kolmogorov scaling is followed by a steeper scaling of power spectra, which is consistent with the solar wind observations by the Cluster spacecraft. We discuss the relevance of our investigation for solar wind plasmas.

Yadav, N.; Sharma, R. P.

2013-11-01

241

Gastrointestinal distribution of albendazole metabolites following netobimin administration to cattle: relationship with plasma disposition kinetics.  

PubMed

The gastrointestinal (GI) distribution and plasma disposition kinetics of albendazole (ABZ) metabolites after oral administration of netobimin (NTB) to cattle were studied. Eight Holstein steers (150-180 kg) were surgically fitted with permanent cannulae in the rumen, abomasum and ileum. After post-surgical recovery, the animals were treated orally with a suspension of netobimin zwitterion (400 mg/ml) at 20 mg/kg. Jugular blood and ruminal, abomasal and ileal fluid samples were taken serially over a 96 h period and analysed by HPLC for NTB and its metabolites, including ABZ, ABZ sulphoxide (ABZSO), ABZ sulphone (ABZSO2) and amino-albendazole sulphone (NH2ABZSO2). NTB parent drug was only found in the GI tract and for only 12-18 h post-treatment. ABZSO and ABZSO2 were the main metabolites found in plasma, being present for 30-36 h. These metabolites were exchanged between plasma and different GI fluids and were greatly concentrated in the abomasum. This phenomenon may account for the presence of ABZ, ABZSO and ABZSO2 in the GI tract for 72 h post-treatment despite the fact that ABZ was not detected in plasma and ABZSO and ABZSO2 were detected for only 30-36 h in plasma. The presence of ABZ and ABZSO in the abomasum and intestine for this extended period of time is probably relevant for anthelmintic efficacy against GI parasites. The NH2 ABZSO2 metabolite was detected in plasma, abomasum and ileum and its disposition kinetics were characterized for the first time. PMID:8478999

Lanusse, C E; Gascon, L H; Prichard, R K

1993-03-01

242

Release kinetics of platelet-derived and plasma-derived growth factors from autologous plasma rich in growth factors.  

PubMed

Many studies have evaluated the biological effects of platelet rich plasma reporting the final outcomes on cell and tissues. However, few studies have dealt with the kinetics of growth factor delivery by plasma rich in growth factors. Venous blood was obtained from three healthy volunteers and processed with PRGF-Endoret technology to prepare autologous plasma rich in growth factors. The gel-like fibrin scaffolds were then incubated in triplicate, in a cell culture medium to monitor the release of PDGF-AB, VEGF, HGF and IGF-I during 8 days of incubation. A leukocyte-platelet rich plasma was prepared employing the same technology and the concentrations of growth factors and interleukin-1? were determined after 24h of incubation. After each period, the medium was collected, fibrin clot was destroyed and the supernatants were stored at -80°C until analysis. The growth factor delivery is diffusion controlled with a rapid initial release by 30% of the bioactive content after 1h of incubation and a steady state release when almost 70% of the growth factor content has been delivered. Autologous fibrin matrix retained almost 30% of the amount of the growth factors after 8 days of incubation. The addition of leukocytes to the formula of platelet rich plasma did not increase the concentration of the growth factors, while it drastically increased the presence of pro-inflammatory IL-1?. Further studies employing an in vitro inflammatory model would be interesting to study the difference in growth factors and pro-inflammatory cytokines between leukocyte-free and leukocyte-rich platelet rich plasma. PMID:23722041

Anitua, Eduardo; Zalduendo, Mari Mar; Alkhraisat, Mohammad Hamdan; Orive, Gorka

2013-10-01

243

A physiologically-based kinetic model for the prediction of plasma cholesterol concentrations in the mouse.  

PubMed

The LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) concentrations are determined by the activity of a complex network of reactions in several organs. Physiologically-based kinetic (PBK) computational models can be used to describe these different reactions in an integrated, quantitative manner. A PBK model to predict plasma cholesterol levels in the mouse was developed, validated, and analyzed. Kinetic parameters required for defining the model were obtained using data from published experiments. To construct the model, a set of appropriate submodels was selected from a set of 65,536 submodels differing in the kinetic expressions of the reactions. A submodel was considered appropriate if it had the ability to correctly predict an increased or decreased plasma cholesterol level for a training set of 5 knockout mouse strains. The model thus defined consisted of 8 appropriate submodels and was validated using data from an independent set of 9 knockout mouse strains. The model prediction is the average prediction of 8 appropriate submodels. Remarkably, these submodels had in common that the rate of cholesterol transport from the liver to HDL was not dependent on hepatic cholesterol concentrations. The model appeared able to accurately predict in a quantitative way the plasma cholesterol concentrations of all 14 knockout strains considered, including the frequently used Ldlr-/- and Apoe-/- mouse strains. The model presented is a useful tool to predict the effect of knocking out genes that act in important steps in cholesterol metabolism on total plasma cholesterol, HDL-C and LDL-C in the mouse. PMID:21320632

van de Pas, Niek C A; Woutersen, Ruud A; van Ommen, Ben; Rietjens, Ivonne M C M; de Graaf, Albert A

2011-05-01

244

Mechanisms of lipid peroxidation in human blood plasma: a kinetic approach.  

PubMed

There is strong evidence that the oxidation of plasma lipoproteins plays an important role in atherogenesis. The exact mechanisms by which lipoprotein oxidation occurs in the presence of other plasma constituents, however, remains unclear. To investigate the role of different antioxidants for this process, we studied the oxidation of human plasma supplemented in vitro with physiological amounts of major plasma antioxidants alpha-tocopherol, ubiquinol-10 ascorbate, urate, bilirubin and albumin. The plasma was diluted 2-fold and oxidized by 3.75 mM Cu(II). The concentrations of the antioxidants, fatty acids, linoleic acid hydroperoxides and oxycholesterols in oxidizing plasma were measured. The oxidation was characterized by three consecutive phases similar to the known lag, propagation, and decomposition phases of low density lipoprotein oxidation. The rate of the initiation of oxidation as calculated from antioxidant consumption rates was raised by supplementation with alpha-tocopherol or ascorbate. The oxidation rate in the lag phase was lowered by supplementation with any of the antioxidants, whereas in the propagation phase the oxidation rate was slightly higher in supplemented than in unsupplemented plasma. The kinetic chain length in the lag phase was less than one in supplemented plasma and about one in unsupplemented plasma. The chain length in the propagation phase was between three and six for all plasma samples. A higher rate of urate consumption and a reduced rate of alpha-tocopherol consumption were found in plasma supplemented with ascorbate in comparison with unsupplemented plasma. These data suggest that: (i) the reduction of Cu(II) by alpha-tocopherol and ascorbate is a major initiating event in Cu(II)-catalyzed oxidation of human plasma; (ii) the following lag phase is caused by radical-scavenging effects of all antioxidants with alpha-tocopherol as a major lipophilic and urate as a major hydrophilic scavenger; (iii) interactions between antioxidants, such as regeneration of ascorbate by urate and of alpha-tocopherol by ascorbate, take place during the lag phase; (iv) in the absence of added antioxidants the oxidation in the lag phase can occur via a chain reaction; and (v) in the propagation phase the oxidation is not inhibited by antioxidants and occurs autocatalytically. PMID:9314186

Karten, B; Beisiegel, U; Gercken, G; Kontush, A

1997-08-29

245

Kinetic effects on Lunar plasma environment on global scale, mesoscale and microscale  

NASA Astrophysics Data System (ADS)

Recent Lunar missions have shown that the solar wind interaction with the Moon is complex and scientifically more interesting than anticipated before, as shown by new in situ plasma, neutral atom and magnetic field observations. Especially, an unexpectedly high fraction of the incident solar wind protons is reflected from the surface, and even larger fraction by the Lunar magnetic anomalies. This effect has been observed both by measuring deviated solar wind flow near the magnetic anomalies and by observing decreased flux of energetic neutral hydrogen atoms, ENAs, from the surface region of strong magnetic anomalies. These "macro scale" processes affect the properties of plasma near the Lunar surface. Consequently, also physical processes at "micro scales" within the Debye sheath layer, where the electric potential of the surface and near surface region are controlled by photoelectrons and solar wind particles, are affected. In this work we introduce two numerical kinetic simulation models developed to study the solar wind interaction with the Moon: (1) a hybrid model (HYB-Moon) to study macro scale processes and (2) a full kinetic PIC model to study micro scale processes. Both models are part of the HYB planetary plasma modelling platform developed at the Finnish Meteorological Institute. In the hybrid model ions are modelled as particles while electrons form a charge neutralizing massless fluid. In the Particle-in-cell (PIC) simulation both ions and electrons are modelled as particles. In the presentation we show results based on these models. A schematic illustration of plasmas and fields which affect the lunar dust-plasma environment near the lunar surface: photoelectrons (e-hf), solar wind electrons (e-sw) and ions (H+sw), dust electrons (e-dust), dust particles (q dust), electric field (E) and magnetic field. Because of the non-zero magnetic field associated with the interplanetary magnetic field (Bsw), electric currents in the plasma and the lunar magnetic anomalies, the charged particle follow gyromotion around the magnetic field. The electric field contains the convective electric field of the solar wind (Esw) and the electric field associated with the charge separation within the potential sheath and possible also within magnetic anomalies. The length scale of the potential sheath is the Debye length (lamda D). See Kallio et al., "Kinetic effects on Lunar plasma environment on global scale, mesoscale and microscale" (PSS, 2012, submitted) for details.

Kallio, E.; Dyadechkin, S.; Jarvinen, R.; Wurz, P.; Barabash, S.; Rantala, A.; Alho, M.

2012-12-01

246

Gyrokinetic Electron and Fully Kinetic Ion Particle Simulation of Collisionless Plasma Dynamics  

SciTech Connect

Fully kinetic-particle simulations and hybrid simulations have been utilized for decades to investigate various fundamental plasma processes, such as magnetic reconnection, fast compressional waves, and wave-particle interaction. Nevertheless, due to disparate temporal and spatial scales between electrons and ions, existing fully kinetic-particle codes have to employ either unrealistically high electron-to-ion mass ratio, me/mi, or simulation domain limited to a few or a few ten's of the ion Larmor radii, or/and time much less than the global Alfven time scale in order to accommodate available computing resources. On the other hand, in the hybrid simulation, the ions are treated as fully kinetic particles but the electrons are treated as a massless fluid. The electron kinetic effects, e.g., wave-particle resonances and finite electron Larmor radius effects, are completely missing. Important physics, such as the electron transit time damping of fast compressional waves or the triggering mechanism of magnetic reconnection in collisionless plasmas is absent in the hybrid codes. Motivated by these considerations and noting that dynamics of interest to us has frequencies lower than the electron gyrofrequency, we planned to develop an innovative particle simulation model, gyrokinetic (GK) electrons and fully kinetic (FK) ions. In the GK-electron and FK-ion (GKe/FKi) particle simulation model, the rapid electron cyclotron motion is removed, while keeping finite electron Larmor radii, realistic me/mi ratio, wave-particle interactions, and off-diagonal components of electron pressure tensor. The computation power can thus be significantly improved over that of the full-particle codes. As planned in the project DE-FG02-05ER54826, we have finished the development of the new GK-electron and FK-ion scheme, finished its benchmark for a uniform plasma in 1-D, 2-D, and 3-D systems against linear waves obtained from analytical theories, and carried out a further convergence test and benchmark for a 2-D Harris current sheet against tearing mode and other instabilities in linear theories/models. More importantly, we have, for the first time, carried out simulation of linear instabilities in a 2-D Harris current sheet with a broad range of guide field BG and the realistic mi/me, and obtained important new results of current sheet instabilities in the presence of a finite BG. Indeed the code has accurately reproduced waves of interest here, such as kinetic Alfven waves, compressional Alfven/whistler wave, and lower-hybrid/modified two-stream waves. Moreover, this simulation scheme is capable of investigating collisionless kinetic physics relevant to magnetic reconnection in the fusion plasmas, in a global scale system for a long-time evolution and, thereby, produce significant new physics compared with both full-particle and hybrid codes. The results, with mi/me=1836 and moderate to large BG as in the real laboratory devices, have not been obtained in previous theory and simulations. The new simulation model will contribute significantly not only to the understanding of fundamental fusion (and space) plasma physics but also to DOE's SciDAC initiative by further pushing the frontiers of simulating realistic fusion plasmas.

Yu Lin; Xueyi Wang; Liu Chen; Zhihong Lin

2009-08-11

247

Kinetics of ion and prompt electron emission from laser-produced plasma  

SciTech Connect

We investigated ion emission dynamics of laser-produced plasma from several elements, comprised of metals and non-metals (C, Al, Si, Cu, Mo, Ta, W), under vacuum conditions using a Faraday cup. The estimated ion flux for various targets studied showed a decreasing tendency with increasing atomic mass. For metals, the ion flux is found to be a function of sublimation energy. A comparison of temporal ion profiles of various materials showed only high-Z elements exhibited multiple structures in the ion time of flight profile indicated by the observation of higher peak kinetic energies, which were absent for low-Z element targets. The slower ions were seen regardless of the atomic number of target material propagated with a kinetic energy of 1–5 keV, while the fast ions observed in high-Z materials possessed significantly higher energies. A systematic study of plasma properties employing fast photography, time, and space resolved optical emission spectroscopy, and electron analysis showed that there existed different mechanisms for generating ions in laser ablation plumes. The origin of high kinetic energy ions is related to prompt electron emission from high-Z targets.

Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States) [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China); Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Ding, H. [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)] [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)

2013-07-15

248

Mass spectrometric detection of F atoms and CFx radicals and their kinetics in CF4 plasmas.  

NASA Astrophysics Data System (ADS)

Detection of atomic fluorine and determination of its kinetics in a discharge environment is essential for understanding the F atom loss mechanisms by surface and/or gas-phase reactions. In this work, threshold-ionization mass spectrometric methods are employed for the detection of F atoms and CFx (x=1-3) radicals present downstream a CF4 microwave plasma (p=15 to 50 mTorr), with emphasis on atomic fluorine detection. Actinometry, on F atoms, and LIF, on CF2 radicals, have also been employed. In addition to the estimation of the fluorine concentration in a continuous discharge, time-resolved measurements allow us to investigate the kinetics of fluorine atoms in the afterglow of a pulsed plasma. The influence of the discharge parameters such as power, pressure, and gas flow, on F atom concentrations and kinetics has been investigated. Important modification of the loss rates of F atoms is observed, under certain conditions, with introduction into the reactor of fluorine-consuming materials, such as a Si or a polymer (Hexatriacontane) surface. All of our observations are consistent with a predominant surface loss of atomic fluorine on the reactor walls and the exposed surfaces.

Tserepi, A.; Derouard, J.; Schwarzenbach, W.; Sadeghi, N.

1996-10-01

249

Ion kinetic simulations of the formation and propagation of a planar collisional shock wave in a plasma  

Microsoft Academic Search

Ion kinetic simulations of the formation and propagation of planar shock waves in a hydrogen plasma have been performed at Mach numbers 2 and 5, and compared to fluid simulations. At Mach 5, the shock transition is far wider than expected on the basis of comparative fluid calculations. This enlargement is due to hot ions streaming from the hot plasma

F. Vidal; J. P. Matte; M. Casanova; O. Larroche

1993-01-01

250

Analysis and Kinetics of Transient Species in Electrode Near Plasma and Plasma Boundary Sheath of RF Plasmas in Molecular Gases  

Microsoft Academic Search

Modern diagnostic methods are applied for investigation of spatial and temporal behaviour of selected reac- tive species in oxygen and fluorocarbon rf plasmas. Comprehensive investigations of the spatial distribution of atomic oxygen were done by means of two-photon absorption laser induced fluorescence spectroscopy. Ex- emplarily, axial and radial O-concentrations are shown for an asymmetric capacitively coupled rf plasma in pure

M. Geigl; S. Peters; O. Gabriel; B. Krames; J. Meichsner

2005-01-01

251

Electron and ion kinetic effects on non-linearly driven electron plasma and ion acoustic waves  

SciTech Connect

Fully non-linear kinetic simulations of electron plasma and ion acoustic waves (IAWs) have been carried out with a new multi-species, parallelized Vlasov code. The numerical implementation of the Vlasov model and the methods used to compute the wave frequency are described in detail. For the first time, the nonlinear frequency of IAWs, combining the contributions from electron and ion kinetic effects and from harmonic generation, has been calculated and compared to Vlasov results. Excellent agreement of theory with simulation results is shown at all amplitudes, harmonic generation being an essential component at large amplitudes. For IAWs, the positive frequency shift from trapped electrons is confirmed and is dominant for the effective electron-to-ion temperature ratio, Z T{sub e}/T{sub i} Greater-Than-Or-Equivalent-To 10 with Z as the charge state. Furthermore, numerical results demonstrate unambiguously the dependence [R. L. Dewar, Phys. Fluids 15, 712 (1972)] of the kinetic shifts on details of the distribution of the trapped particles, which depends in turn on the conditions under which the waves were generated. The trapped particle fractions and energy distributions are derived and, upon inclusion of harmonic effects, shown to agree with the simulation results, completing a consistent picture. Fluid models of the wave evolution are considered but prove unable to capture essential details of the kinetic simulations. Detrapping by collisions and sideloss is also discussed.

Berger, R. L.; Chapman, T.; Divol, L.; Still, C. H. [Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Brunner, S. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CRPP-PPB, CH-1015 Lausanne (Switzerland); Valeo, E. J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)

2013-03-15

252

Influence of Gas Heating and Vibrational Kinetics on the Ionization Dynamics of Preformed Air Plasma Channels  

NASA Astrophysics Data System (ADS)

An extensive self-consistent air-plasma model based upon the Boltzmann equation for the electron energy distribution function, coupled with a heavy particle kinetics was developed to study electric discharges in a preexisting air plasma column [1]. Incorporated in the model are the steady-state balance equations for various nitrogen and oxygen species in ground and excited states, as well as atomic and molecular ions. The influence of the gas temperature is accounted for by reduction of the neutral density, collisional processes such as recombination, dissociation, V-V and V-T reactions [2], and by reactions involving electronically excited states of O2. The model was applied to study the influence of the gas temperature and vibrational kinetics on the breakdown processes in a preformed air plasma channel. Numerical calculations predict that electrical breakdown occurs at relatively low electric field. The calculated self-consistent breakdown electric field is ˜10 kV/cm for gas temperature of 300 K, while at temperature of 600 K it drops to ˜5.7 kV/cm, in excellent agreement with the experimentally determined breakdown electric field [1]. * NRC-NRL Postdoc [1] Tz.B. Petrova, H.D. Ladouceur, and A.P. Baronavski, 58th Gaseous Electronics Conference, 2005; San Jose, California, FM.00062 [2] J. Loureiro and C.M. Ferreira, J. Phys. D: Appl. Phys 19 (1986) 17-35

Ladouceur, Harold; Baronavski, Andrew; Petrova, Tzvetelina

2006-03-01

253

Dispersion characteristics of kinetic Alfven waves in a multi-ion cometary plasma  

NASA Astrophysics Data System (ADS)

We have studied the stability of the kinetic Alfven wave in a plasma composed of hydrogen and positively and negatively charged oxygen ions and electrons which approximates very well the plasma environment around comet Halley. In the direction parallel to the magnetic field, the electrons have been modelled by a drifting Maxwellian distribution. In the perpendicular direction, another ring simulated by a loss cone type distribution, obtained by subtracting two Maxwellians with different temperatures, model all the constituents of the plasma. The dispersion relation derived for KAWs is a generalisation of the pioneering dispersion relation of Hasegawa on two counts: it has been extended to a plasma described by a generalised distribution function and to a multi - ion plasma containing positively and negatively charged ions. We find that the dispersion characteristics of the KAW can be made independent of the heavy ion parameters by an appropriate choice of densities and temperatures. The source of free energy for the instability is the drift velocity of the electrons; the growth rate increases with increasing drift velocity of the electrons. The positively charged heavier ions enhance the instability while the negatively charged heavier ions tend to damp the wave.

Jayapal, R.; Abraham, Noble P.; Blesson, Jose; Antony, S.; Anilkumar, C. P.; Venugopal, Chandu

254

Kinetic simulation of an extreme ultraviolet radiation driven plasma near a multilayer mirror  

NASA Astrophysics Data System (ADS)

Future generation lithography tools will use extreme ultraviolet radiation to enable the printing of sub-50 nanometer features on silicon wafers. The extreme ultraviolet radiation, coming from a pulsed discharge, photoionizes the low pressure background gas in the tool. A weakly ionized plasma is formed, which will be in contact with the optical components of the lithography device. In the plasma sheath region ions will be accelerated towards the surfaces of multilayer mirrors. A self-consistent kinetic particle-in-cell model has been applied to describe a radiation driven plasma. The simulations predict the plasma parameters and notably the energy at which ions impact on the plasma boundaries. We have studied the influence of photoelectron emission from the mirror on the sheath dynamics and on the ion impact energy. Furthermore, the ion impact energy distribution has been convoluted with the formula of Yamamura and Tawara [At. Data Nucl. Data Tables 62, 149 (1996)] for the sputter yield to obtain the rate of physical sputtering. The model predicts that the sputter rate is dominated by the presence of doubly ionized argon ions.

van der Velden, M. H. L.; Brok, W. J. M.; van der Mullen, J. J. A. M.; Banine, V.

2006-10-01

255

Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory  

NASA Astrophysics Data System (ADS)

Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density ne are calculated as |?B|=?(?B)2 =2.8(nemec2)1/2g1/2?e7/4 and |?E |=?(?E)2 =3.2(nemec2)1/2g1/3?e2, where g and ?e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |?B |=6.10-18G and |?E|=2.10-16G result.

Yoon, P. H.; Schlickeiser, R.; Kolberg, U.

2014-03-01

256

Nonlinear Gyrokinetics: A Powerful Tool for the Description of Microturbulence in Magnetized Plasmas  

SciTech Connect

Gyrokinetics is the description of low-frequency dynamics in magnetized plasmas. In magnetic-confinement fusion, it provides the most fundamental basis for numerical simulations of microturbulence; there are astrophysical applications as well. In this tutorial, a sketch of the derivation of the novel dynamical system comprising the nonlinear gyrokinetic (GK) equation (GKE) and the coupled electrostatic GK Poisson equation will be given by using modern Lagrangian and Lie perturbation methods. No background in plasma physics is required in order to appreciate the logical development. The GKE describes the evolution of an ensemble of gyrocenters moving in a weakly inhomogeneous background magnetic field and in the presence of electromagnetic perturbations with wavelength of the order of the ion gyroradius. Gyrocenters move with effective drifts, which may be obtained by an averaging procedure that systematically, order by order, removes gyrophase dependence. To that end, the use of the Lagrangian differential one-form as well as the content and advantages of Lie perturbation theory will be explained. The electromagnetic fields follow via Maxwell's equations from the charge and current density of the particles. Particle and gyrocenter densities differ by an important polarization effect. That is calculated formally by a "pull-back" (a concept from differential geometry) of the gyrocenter distribution to the laboratory coordinate system. A natural truncation then leads to the closed GK dynamical system. Important properties such as GK energy conservation and fluctuation noise will be mentioned briefly, as will the possibility (and diffculties) of deriving nonlinear gyro fluid equations suitable for rapid numerical solution -- although it is probably best to directly simulate the GKE. By the end of the tutorial, students should appreciate the GKE as an extremely powerful tool and will be prepared for later lectures describing its applications to physical problems.

John E. Krommes

2010-09-27

257

Stability of solitary kinetic Alfvén waves and ion-acoustic waves in a nonthermal plasma  

NASA Astrophysics Data System (ADS)

The KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equations for kinetic Alfvén and ion-acoustic waves in a nonthermal magnetized plasma have been derived. The coefficient of the nonlinear term of this equation for an ion-acoustic wave can vanish along a curve in a two-dimensional parameter space. In this case, two coupled equations constituting a modified KdV-ZK equation describing nonlinear behavior of an ion-acoustic wave are derived. The solitary wave solutions of all these equations are obtained and their stabilities are investigated by the Rowlands-Infeld method. It is found that the kinetic Alfvén solitons are stable. The instability conditions and the maximum growth rate of the instability for ion-acoustic solitons are determined.

Bandyopadhyay, Anup; Das, K. P.

2000-08-01

258

Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers  

SciTech Connect

Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

1993-01-01

259

Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers  

SciTech Connect

Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

1993-03-01

260

Experimental and kinetic studies of C–H–O plasmas for polycrystalline and nano-smooth diamond deposition  

Microsoft Academic Search

CO2–CH4 and CO–H2 plasmas were studied by optical emission spectroscopy, microwave interferometry, Langmuir probing and molecular beam mass spectrometry. The variations of the plasma parameters as well as the concentration variations of both stable species and radicals were obtained as a function of the inlet composition. A modelling of the plasma kinetics taking into account the coupled hydrodynamics of the

T. Gries; S. de Persis; L. Vandenbulcke; C. Met; J. L. Delfau; M. I. De Barros-Bouchet

2009-01-01

261

Self-consistent nonlinear kinetic simulations of the anomalous Doppler instability of suprathermal electrons in plasmas  

SciTech Connect

Suprathermal tails in the distributions of electron velocities parallel to the magnetic field are found in many areas of plasma physics, from magnetic confinement fusion to solar system plasmas. Parallel electron kinetic energy can be transferred into plasma waves and perpendicular gyration energy of particles through the anomalous Doppler instability (ADI), provided that energetic electrons with parallel velocities v{sub ||}?(?+?{sub ce})/k{sub ||} are present; here ?{sub ce} denotes electron cyclotron frequency, ? the wave angular frequency, and k{sub ||} the component of wavenumber parallel to the magnetic field. This phenomenon is widely observed in tokamak plasmas. Here, we present the first fully self-consistent relativistic particle-in-cell simulations of the ADI, spanning the linear and nonlinear regimes of the ADI. We test the robustness of the analytical theory in the linear regime and follow the ADI through to the steady state. By directly evaluating the parallel and perpendicular dynamical contributions to j·E in the simulations, we follow the energy transfer between the excited waves and the bulk and tail electron populations for the first time. We find that the ratio ?{sub ce}/(?{sub pe}+?{sub ce}) of energy transfer between parallel and perpendicular, obtained from linear analysis, does not apply when damping is fully included, when we find it to be ?{sub pe}/(?{sub pe}+?{sub ce}); here ?{sub pe} denotes the electron plasma frequency. We also find that the ADI can arise beyond the previously expected range of plasma parameters, in particular when ?{sub ce}>?{sub pe}. The simulations also exhibit a spectral feature which may correspond to the observations of suprathermal narrowband emission at ?{sub pe} detected from low density tokamak plasmas.

Lai, W. N. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)] [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Chapman, S. C. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom) [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Department of Mathematics and Statistics, University of Tromsø, Tromsø (Norway); Dendy, R. O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom) [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)

2013-10-15

262

Magnetized plasma kinetic theory. III. Fokker-Planck coefficients for a uniform magnetized plasma  

Microsoft Academic Search

The magnetized Balescu-Lenard collision integral for a multi-species plasma in the form derived by Hassan and Watson (1976) is approximated by ignoring wave effects. The resulting collision integral is put in Fokker-Planck form and most of the integrals occurring in the coefficients are performed analytically. The remaining integral is evaluated approximately in various limits for ion-electron, electron-electron and electron-ion interactions.

M H A Hassan; C J H Watson

1977-01-01

263

Arbitrary-amplitude solitary kinetic Alfvén waves in a non-thermal plasma  

NASA Astrophysics Data System (ADS)

An exact Sagdeev equation for arbitrary-amplitude solitary kinetic Alfvén waves in a non-thermal plasma is derived. For small [beta][prime prime or minute], the proportion of fast electrons, an analytical expression for the exact pseudopotential V ([phi]) is obtained. For several values of [beta][prime prime or minute], the Sagdeev potential V ([phi]) has been calculated by integrating the Sagdeev equation. It is found that, depending on the values of [beta][prime prime or minute], both hump and dip solitons exist.

Roychoudhury, Rajkumar

2002-04-01

264

Effects of Charge in Heavy Ions on Solitary Kinetic Alfvén Waves in Double-Ion Plasmas  

NASA Astrophysics Data System (ADS)

After the charge of heavy ions is considered, a Sagdeev equation is obtained for the solitary kinetic Alfvén waves (SKAWs) in a low-? (me/mp << ? << 1 or mp/me >> ? >> 1), three-component (electrons, protons, and highly charged heavy ions) plasma. Numerical results show that the charge number q of heavy ions can cause the width of the solitary structure to decrease, but increase for the maximum of electron density nem<=1.2 and the initial abundance of heavy ions Cb0<=0.1. The parallel phase speed of the waves increases with larger q.

Yang, Lei; Wu, De-Jin

2006-08-01

265

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

266

Obliquely propagating solitary kinetic Alfven wave in a collisional dusty plasma  

NASA Astrophysics Data System (ADS)

An obliquely propagating solitary kinetic Alfven wave in a low beta dusty plasma (?<plasma is re-examined. It is found that there is an upper limit of the possible Alfvenic Mach velocity, imposed by dust particles. The Mach number lies between lz and lz/Nd, where lz is the directional cosine and Nd is the dust particle charge density. In the collisional case, the same upper limit of the Mach velocity is found, and the solitary wave turns into an oscillating double layer. The damping scale and the size of the oscillation structure increase with increasing dust particle charge density. The damping scale and the size of the oscillation structure are estimated by using the virial theorem.

Woo, M. H.; Ryu, C.-M.; Choi, C.-R.

2010-05-01

267

The role of electron scattering with vibrationally excited nitrogen molecules on non-equilibrium plasma kinetics  

SciTech Connect

Electron energy distribution functions have been calculated by a self-consistent model which couples the electron Boltzmann equation with vibrationally and electronically excited state kinetics and plasma chemistry. Moderate pressure nitrogen gas discharges in the E/N range from 30 to 60 Townsend are investigated comparing an electron-impact cross section set considering transitions starting from all the vibrational states, with reduced models, taking into account only collisions involving the ground vibrational level. The results, while confirming the important role of second kind collisions in affecting the eedf, show a large dependence of the eedf on the set of inelastic processes involving vibrationally and electronically excited molecules, pointing out the need of using a cross section database including processes linking excited states in non-equilibrium plasma discharge models.

Capitelli, Mario [Dipartimento di Chimica, Universitá di Bari, Via Orabona 4, 70125 Bari (Italy) [Dipartimento di Chimica, Universitá di Bari, Via Orabona 4, 70125 Bari (Italy); CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Colonna, Gianpiero; D'Ammando, Giuliano; Laricchiuta, Annarita [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy)] [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Laporta, Vincenzo [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)] [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

2013-10-15

268

Kinetic simulation of capacitively coupled plasmas driven by trapezoidal asymmetric voltage pulses  

NASA Astrophysics Data System (ADS)

A kinetic Particle-In-Cell simulation with Monte Carlo Collisions was performed of a geometrically symmetric capacitively coupled, parallel-plate discharge in argon, driven by trapezoidal asymmetric voltage pulses with a period of 200 ns. The discharge was electrically asymmetric, making the ion energy distributions at the two electrodes different from one another. The fraction of the period (?), during which the voltage was kept at a constant (top-flat) positive value, was a critical control parameter. For the parameter range investigated, as ? increased, the mean ion energy on the grounded electrode increased and the ions became more directional, whereas the opposite was found for the ions striking the powered electrode. The absolute value of the DC self-bias voltage decreased as ? increased. Plasma instabilities, promoted by local double layers and electric field reversals during the time of the positive voltage excursion, were characterized by electron plasma waves launched from the sheath edge.

Diomede, Paola; Economou, Demetre J.

2014-06-01

269

Study of stationary plasma thrusters using two-dimensional fully kinetic simulations  

NASA Astrophysics Data System (ADS)

Stationary plasma thrusters are devices that use crossed electric and magnetic fields to accelerate ions to high velocities. Ions are created by collisional ionization of a propellant gas with electrons injected from a hollow cathode external to the thruster. A major issue is the electron transport through the magnetic field. It is known to exceed considerably the values predicted by the classical theory. Various 2D models have shown that wall collisions, which have often been invoked as the origin of this anomalous transport, are in fact insufficient. Anomalous turbulent transport has to be added to the model to recover an adequate conductivity. In the present paper the first 2D kinetic model that shows that, indeed, plasma turbulence can explain the observed conductivity is presented. Without any free parameter the model is able to reproduce numerous experimental features. At the end of the paper a preliminary theoretical analysis of the observed instability is provided.

Adam, J. C.; Héron, A.; Laval, G.

2004-01-01

270

Electron, Atomic, and Radiation Kinetics in Plasma Discharge Lighting: Advanced Models and Observations  

NASA Astrophysics Data System (ADS)

Non-LTE discharges used in lighting sources provide an excellent testbed for understanding the interplay between plasma, atomic, and radiation physics. Standard models for the Hg fluorescent bulb include non-equilibrium kinetics for the species, but employ both a 0-D Boltzmann equation for the electron distribution function (EDF) and Holstein's probability-of-escape for radiation transport. These assumptions overlook some of the more interesting, and challenging, aspects of plasma lighting. The radial ambipolar potential requires the inclusion of the spatial gradient term in the inhomogeneous electron Boltzmann equation. The resulting EDF is found to depend on both electron energy and radial position [1]. Advanced radiation transport techniques account for non-local photo-pumping, line overlap within the Hg resonance lines, and partial frequency redistribution [2]. The results of our completely coupled model match the observed spatial distribution of Hg excited states and the line-of-sight intensity [3]. Due to environmental initiatives there is also recent interest in non-Hg discharges for high intensity lighting. One example is an RF electrodeless Mo-O-Ar plasma discharge bulb which operates by recycling the emitting Mo with an O catalyst. Based on atomic physics calculations for Mo [4], the kinetic pathways leading to visible emission can be identified [5] and explain the measured lighting efficiency of ˜40 lumens/watt of supplied power.[1] J. Appl. Phys., 94, p.62, 2003. [2] Plasma Sources Sci. Tech., 14, p.236, 2005. [3] J. Phys. D., 38, p.4180, 2005. [4] New J. Physics, 6, p.145, 2004. [5] J. Appl. Phys., 95, p.5284, 2004.

Giuliani, John L.

2006-10-01

271

Jovian Plasmas Torus Interaction with Europa. Plasma Wake Structure and Effect of Inductive Magnetic Field: 3D Hybrid Kinetic Simulation  

NASA Technical Reports Server (NTRS)

The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to a variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions). Photoionization, electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider the models with Oþ þ and Sþ þ background plasma, and various betas for background ions and electrons, and pickup electrons. The majority of O2 atmosphere is thermal with an extended non-thermal population (Cassidy et al., 2007). In this paper, we discuss two tasks: (1) the plasma wake structure dependence on the parameters of the upstream plasma and Europa's atmosphere (model I, cases (a) and (b) with a homogeneous Jovian magnetosphere field, an inductive magnetic dipole and high oceanic shell conductivity); and (2) estimation of the possible effect of an induced magnetic field arising from oceanic shell conductivity. This effect was estimated based on the difference between the observed and modeled magnetic fields (model II, case (c) with an inhomogeneous Jovian magnetosphere field, an inductive magnetic dipole and low oceanic shell conductivity).

Lipatov, A. S.; Cooper, J F.; Paterson, W. R.; Sittler, E. C., Jr.; Hartle, R. E.; Simpson, David G.

2013-01-01

272

Kinetic Approach for Studying the Alpha Particle Transport in Plasma Liner Driven Magnetized Target Fusion  

NASA Astrophysics Data System (ADS)

A new promising concept for producing energy from thermonuclear fusion is magnetized target fusion (MTF). In MTF, an imploding material liner is used to compress magnetized plasma to fusion ignition and to inertially confine the resulting burning plasma to obtain the necessary energy gain. Plasma liners have the potential to be formed in a repeatable, standoff manner and allow for the possibility of secondary fusion burn in the liner, which allows for much higher fusion energy yields and relaxes the density and scale length requirements of the magnetized target. To date, no theoretical effort has adequately addressed the issue of thermal transport of high-energy alpha particles from the target to the liner. Although the liner/target system is highly collisional at ignition, the fast alpha particle mean free path is relatively large resulting in nonlocal deposition of the kinetic energy into the liner. Thus, a fluid approach may not be appropriate for assessing the possibility of secondary burn. A MATLAB computer code was developed that numerically modeled the alpha particles, electrons, and Deuterons using distribution functions. These distribution functions were separately evolved over time using the Boltzmann equation for the plasma transport and the nonlinear Fokker-Planck equation for the collisions between the alpha particles and the electrons and Deuterons. Preliminary results from this work shows that the alpha particles collide with the initially at rest Deuterons and transfer enough energy so that both species move outward away from the target. In addition, some of the Deuterons reach fusion burn energies.

Sommer, James

2003-10-01

273

Kinetic theory of acoustic-like modes in nonextensive pair plasmas  

NASA Astrophysics Data System (ADS)

The low-frequency acoustic-like modes in a pair plasma (electron-positron or pair-ion) is studied by employing a kinetic theory model based on the Vlasov and Poisson's equations with emphasizing the Tsallis's nonextensive statistics. The possibility of the acoustic-like modes and their properties in both fully symmetric and temperature-asymmetric cases are examined by studying the dispersion relation, Landau damping and instability of modes. The resultant dispersion relation in this study is compatible with the acoustic branch of the experimental data (Oohara et al. in Phys. Rev. Lett. 95:175003, 2005) in which the electrostatic waves have been examined in a pure pair-ion plasma. Particularly, our study reveals that the occurrence of growing or damped acoustic-like modes depends strongly on the nonextensivity of the system as a measure for describing the long-range Coulombic interactions and correlations in the plasma. The mechanism that leads to the unstable modes lies in the heart of the nonextensive formalism yet, the mechanism of damping is the same developed by Landau. Furthermore, the solutions of acoustic-like waves in an equilibrium Maxwellian pair plasma are recovered in the extensive limit ( q?1), where the acoustic modes have only the Landau damping and no growth.

Saberian, E.; Esfandyari-Kalejahi, A.

2014-02-01

274

Transmission spectroscopy and atomic kinetics of neon photoionized plasma experiments at Z  

NASA Astrophysics Data System (ADS)

We discuss a series of experiments performed at the Z facility in which photoionized plasmas were produced by driving a neon-filled gas cell with the intense x-ray flux emitted at the collapse of a z-pinch. The broad-band radiation flux from the z-pinch is used to both create the neon photoionised plasma and provide a source of backlighting photons to study the atomic kinetics through K-shell transmission spectroscopy. The plasma is contained in cm-scale gas cell and the filling pressure is carefully monitored in situ all the way to shot time since it is the particle number density diagnostic of the plasma. Time-integrated and gated transmission spectra are recorded with a TREX spectrometer equipped with two KAP elliptically-bent crystals and a set of slits to record up to six spatially-resolved spectra per crystal in the same shot. The transmission data shows line absorption transitions in several ionization stages of neon. Detailed modeling calculations are used to interpret the data.

Mancini, R.; Hall, I.; Durmaz, T.; Bailey, J.; Rochau, G.; Cohen, D.; Foord, M.; Heeter, R.

2010-11-01

275

Merging for Particle-Mesh Complex Particle Kinetic Modeling of the Multiple Plasma Beams  

NASA Technical Reports Server (NTRS)

We suggest a merging procedure for the Particle-Mesh Complex Particle Kinetic (PMCPK) method in case of inter-penetrating flow (multiple plasma beams). We examine the standard particle-in-cell (PIC) and the PMCPK methods in the case of particle acceleration by shock surfing for a wide range of the control numerical parameters. The plasma dynamics is described by a hybrid (particle-ion-fluid-electron) model. Note that one may need a mesh if modeling with the computation of an electromagnetic field. Our calculations use specified, time-independent electromagnetic fields for the shock, rather than self-consistently generated fields. While a particle-mesh method is a well-verified approach, the CPK method seems to be a good approach for multiscale modeling that includes multiple regions with various particle/fluid plasma behavior. However, the CPK method is still in need of a verification for studying the basic plasma phenomena: particle heating and acceleration by collisionless shocks, magnetic field reconnection, beam dynamics, etc.

Lipatov, Alexander S.

2011-01-01

276

Kinetics  

NSDL National Science Digital Library

Conceptual questions about kinetics. For example, "[w]hat are the reaction velocity, the rates of formation of N2 and H2, and the rate of decomposition of ammonia for the decomposition of ammonia on a tungsten surface under the conditions reflected in the figure."

Nurrenbern, Susan C.; Robinson, William R.

2008-02-27

277

A plasma concentration of ?-ketoglutarate influences the kinetic interaction of ligands with organic anion transporter 1.  

PubMed

The purpose of the present study was to determine whether a physiologic plasma concentration of ?-ketoglutarate (?KG) influences the kinetic interaction of ligands with organic anion transporter 1 (OAT1). The effect of extracellular ?KG on the kinetics of para-aminohippurate (PAH) and cidofovir transport was examined along with its effect on the potency of 10 drugs in five different classes (uricosuric, nonsteroidal anti-inflammatories, loop diuretics, angiotensin II receptor antagonists, and ?-lactam antibiotics) to inhibit OAT1 expressed in Chinese hamster ovary cells. Extracellular ?KG competitively inhibited PAH and cidofovir transport with Ki values (?5 ?M) approximating its unbound plasma concentration (determined by equilibrium dialysis). When PAH was the substrate, extracellular ?KG (5 ?M) significantly increased IC50 values for some inhibitors (up to 4-fold), such as probenecid, but not for others (an inhibitor-dependent effect). For some inhibitors, a significant increase in IC50 value was observed when cidofovir was the substrate, but not PAH (a substrate-dependent effect). A significant increase in IC50 value was also observed for inhibition of PAH transport by probenecid in renal basolateral membrane vesicles (5.2-fold). The substrate- and inhibitor-dependent effect of extracellular ?KG on ligand interactions with OAT1 highlights the complexity of the OAT1 ligand-binding surface. The effect of extracellular ?KG on the potency of OAT1 inhibition should be considered when assessing drug-drug interaction potential at the transporter. PMID:24770989

Ingraham, Leslie; Li, Mansong; Renfro, J Larry; Parker, Sonda; Vapurcuyan, Arpine; Hanna, Imad; Pelis, Ryan M

2014-07-01

278

Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method  

NASA Astrophysics Data System (ADS)

The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as linearly implicit methods or one-step Newton methods. However, issues related to time accuracy of these methods still remain. We are pursuing a route to implicit plasma kinetic simulation which eliminates extrapolation, eliminates phase-space from the linear algebra problem, and converges the entire nonlinear system within a time step. We accomplish all this using the Jacobian-Free Newton-Krylov algorithm. The original research along these lines considered particle methods to advance the distribution function [1]. In the current research we are advancing the Vlasov equations on a grid. Results will be presented which highlight algorithmic details for single species electrostatic problems and coupled ion-electron electrostatic problems. [4pt] [1] H. J. Kim, L. Chac'on, G. Lapenta, ``Fully implicit particle in cell algorithm,'' 47th Annual Meeting of the Division of Plasma Physics, Oct. 24-28, 2005, Denver, CO

Taitano, William; Knoll, Dana; Chacon, Luis

2009-11-01

279

Chemical kinetics simulation for atmospheric pressure air plasmas in a streamer regime  

SciTech Connect

We present a theoretical analysis of air discharges at high pressure which operates in a streamer regime. The aim is to provide a simplified framework to study the chemical kinetics in the discharge gas phase. We have tried to model the characteristics of actually existing devices, such as dc and ac discharges in sharp point-plane, point to point, or coaxial cylinder configuration, dielectric barrier discharges. Within such scheme it is possible to perform numerical simulations in order to predict the evolution of the gas-phase chemical composition. As a first application we have chosen to simulate the chemical kinetics induced in a single isolated streamer and the results of this approach are examined within this paper. In particular, we have studied the detailed temporal evolution of the discharge gas phase using reference values for the simulation free parameters. The interplay between different time scale processes is shown. The effect due to charged as well as metastable species on chemical kinetics has been discussed too. Then we have studied the dependence of chemical species density on discharge parameters such as the electron temperature, the electron density, the transverse radius of the streamer, and the streamer formation time. Many results can be proven relevant for a better understanding of the operating conditions during technological sensible processing based on atmospheric pressure plasma.

Barni, R.; Esena, P.; Riccardi, C. [Dipartimento di Fisica G. Occhialini, Universita degli Studi di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milan (Italy)

2005-04-01

280

Kinetic simulations of ultra-intense laser plasma interactions and a novel method of generating odd harmonics  

SciTech Connect

We report on computer simulation results for a new laser plasma interaction regime, concentrating on the collisionless, kinetic nature of the plasma motion. It is found that even for normal incidence, the absorption of the laser light by the plasma electrons near critical can be as high as 60%, and that the temperature of the hot electrons produced can be predicted simply by knowing the associated ponderomotive potential of the incident laser. We also describe a new odd harmonic generation mechanism due to the interaction of the laser with the plasma electrons near critical.

Wilks, S.C.; Kruer, W.L. [Lawrence Livermore National Lab., CA (United States); Mori, W.B. [California Univ., Los Angeles, CA (United States)

1993-02-11

281

Numerical Simulation of Laser Fusion Plasmas Using a Reduced Description Formalism.  

National Technical Information Service (NTIS)

A computational study of laser fusion plasmas with a new numerical model is undertaken. The plasma is described by fluid equations and the fields by the time dependent Maxwell's equations. Problems of stimulated Brillouin scattering, self-steepening of th...

R. J. Faehl

1976-01-01

282

A Self-Consistent Description of Dust Interactions in Space and Nano-structured Plasmas  

Microsoft Academic Search

The effect of nano\\/micro-structures and dust voids on the dispersion relations and the overall dynamics of plasma waves has numerous applications in the study of laboratory and space plasmas such as planetary rings and lunar and asteroidal dust. In particular, elastic Coulomb collisions with dust particles and charging interactions affect the overall particle balance of the plasma species and must

Steven Bekhor

2008-01-01

283

Measurements of the gas-kinetic pressure in plasma flows emerging from a micropinch discharge by means of laser interferometry  

NASA Astrophysics Data System (ADS)

A new method for measuring the gas-kinetic pressure in pulsed plasma flows is developed in which an acoustic line in the form of a thin rod built in the optical scheme of a laser interferometer is used as a detector. The time evolution of the gas-kinetic pressure in particle flows emerging from a micropinch discharge (a low-inductance vacuum spark) was studied. Due to the wide dynamic range of the method (˜105), it can be applied in various plasma devices with a wide range of parameters.

Kuznetsov, A. P.; Byalkovskii, O. A.; Gubskii, K. L.; Kozin, G. I.; Protsenko, E. D.; Dodulad, E. I.; Savjolov, A. S.

2014-04-01

284

Kinetic description of electron-proton instability in high-intensity proton linacs and storage rings based on the Vlasov-Maxwell equations  

Microsoft Academic Search

The present analysis makes use of the Vlasov-Maxwell equations to develop a fully kinetic description of the electrostatic, electron-ion two-stream instability driven by the directed axial motion of a high-intensity ion beam propagating in the z direction with average axial momentum gammabmbbetabc through a stationary population of background electrons. The ion beam has characteristic radius rb and is treated as

Ronald C. Davidson; Hong Qin; Peter H. Stoltz; Tai-Sen F. Wang

1999-01-01

285

Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results  

NASA Technical Reports Server (NTRS)

The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa-moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements, (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy etal.,2007;Shematovichetal.,2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyro radius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions).Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization,electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma:(a) with O(++) ions; (b) with O(++) and S(++) ions. The majority of O2 atmosphere is thermal with an extended cold population (Cassidyetal.,2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.

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

2010-01-01

286

Propagator expansion method for solving linearized plasma kinetic equations with collisions. Environmental research papers, June 1983-June 1984  

SciTech Connect

A propagator expansion method is presented for solving linearized plasma kinetic equations with collisions. The essence of the method is the representation and use of the collisional propagator for a given problem as an expansion in powers of the collision frequency. The linearized Balescu-Lenard collision operator and the zero-order distribution function Maxwellian were determined. An exact expression for the collisional damping rate is obtained in the long-wavelength approximation to the first order in the plasma parameter.

Jasperse, J.R.

1984-06-25

287

Jovian's plasma torus interaction with Europa: 3D hybrid kinetic simulation  

NASA Astrophysics Data System (ADS)

The hybrid kinetic model approach supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical to improved interpretation of the existing measurements for surface and atmospheric composition from previous missions and to planning of future missions. The simulations are based on recent models of the atmosphere of Europa [1,2]. The hybrid model allows us to take into account the finite gyroradius effect and to estimate correctly the ions velocity distribution and the fluxes along the magnetic field in opposite the MHD simulation with the Maxwellian velocity distribution for background and pickup ions. The hybrid model also allows us to investigate the effects of the electron pressure on plasma wake structure that was already done for Jovian torus Io interaction [3]. Photoionization, electron-impact ionization and charge exchange are included in our model. The temperature of the background electrons and pickup electrons was also included into the generalized Ohm's law. We also take into account the collisions between the ions and neutrals. The background plasma contains only the ions with SO++ (Model A) [4] and O++ and S++ (Model B) [5]. The pickup ions were created from the atmosphere. The majority of O2 atmosphere is thermal with an extended non-thermal population [1]. The moon is modeled in this initial work as a weakly conducting body. Important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work. In this report we discuss the first results of the hybrid kinetic simulation of Europa's environment, namely, the global plasma structures, e.g., the formation of the magnetic barrier, Alfvén wing, pickup ion tail etc., and the computed map for the ion flux on the surface of the moon. References [1] Cassidy, T.A., R.E. Johnson, M.A. McGrath, M.C. Wong, J.F. Cooper, The spatial morphology of Europa's near-surface O2 atmosphere, Icarus, 191, 755-764, 2007. [2] Shematovich, V.I., R.E. Johnson, J.F. Cooper, M.C. Wong, Surface-bounded atmosphere of Europa, Icarus, 173, 480-498, 2005. [3] Lipatov, A.S. and M.R. Combi, Effects of kinetic processes in shaping Io's global plasma environment: A 3D hybrid model, Icarus, 180, 412-427, 2006. [4] Kabin, K., et al., On Europa's magnetospheric interaction: A MHD simulation of the E4 Flyby, JGR, 104, 19983-19992, 1999. [5] Paterson, W.R. et al., Galileo plasma observations at Europa: Ion energy spectra and moments, JGR, 104, 22779-22791, 1999.

Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.

2009-12-01

288

Lagrangian fluid description with simple applications in compressible plasma and gas dynamics  

Microsoft Academic Search

The Lagrangian fluid description, in which the dynamics of fluids is formulated in terms of trajectories of fluid elements, not only presents an alternative to the more common Eulerian description but has its own merits and advantages. This aspect, which seems to be not fully explored yet, is getting increasing attention in fluid dynamics and related areas as Lagrangian codes

Hans Schamel

2004-01-01

289

Kinetics of illuminated complex plasmas considering Mie scattering by spherical dust particles with a size distribution  

SciTech Connect

In this paper Mie scattering of light by dust particles having Mathis, Rumpl, and Nordsieek power law distribution of size has been incorporated in the formulation of the kinetics of an illuminated complex plasma which takes into account the ionization of neutral atoms by an external agency, ion-electron recombination, photoemission of electrons by the dust particles, and accretion of electrons and ions on the surface of the particles; the number and energy balance of the constituent species has also been taken into account. An interesting conclusion is that unlike the usual case (when Mie scattering is neglected) the charge on a particle is not proportional to the radius and that for certain sets of parameters the smaller particles are negatively charged while the larger particles, carry positive charge.

Sodha, M. S. [Disha Institute of Management and Technology, Satya Vihar, Vidhan Sabha-Chandrakhuri Marg, Mandir Hasaud, Raipur, 492101 Chhattisgarh (India); Mishra, S. K.; Misra, Shikha [Department of Education Building, University of Lucknow, Lucknow 226007 (India)

2011-01-01

290

Kinetic simulation of the O-X conversion process in dense magnetized plasmas  

NASA Astrophysics Data System (ADS)

One scheme for heating a dense magnetized plasma core, such as in a tokamak, involves launching an ordinary (O) electromagnetic wave at the low density edge. It is converted to a reflected extraordinary (X) electromagnetic wave under certain conditions, and then transformed into an electron Bernstein wave able to reach high density regions inaccessible to most other waves. The O-X mode conversion is important in heating and diagnostic processes in different devices such as tokamaks, stellarators, and some types of pinches. The goal of this study has been to demonstrate that the kinetic particle-in-cell (PIC) scheme is suitable for modeling the O-X conversion process as the first step toward a more complete simulation of O-X-B heating. The O-X process is considered and simulated with a kinetic particle model for parameters of the TJ-II stellarator using the PIC code, XOOPIC. This code is able to model the non-monotonic density and the magnetic profile of the TJ-II stellarator. It can also statistically represent the self-consistent distribution function of the plasma, which has not been possible in previous fluid models. By considering the electric and magnetic components of launched and reflected waves, the O-mode and X-mode waves can be detected, and the O-X conversion can be demonstrated. In this work, the optimum angle for conversion efficiency, as predicted by the previous theory and experimentally confirmed, is used. Via considering the power of the launched O-mode wave and the converted X-mode wave, the efficiency of 63% for O-X conversion for the optimum theoretical launch angle of 47\\convolu is obtained, which is in good agreement with efficiencies computed via full-wave simulations.

Ali Asgarian, M.; Verboncoeur, J. P.; Parvazian, A.; Trines, R.

2013-10-01

291

Fully kinetic simulations of magnetic reconnction in semi-collisional plasmas  

SciTech Connect

The influence of Coulomb collisions on the dynamics of magnetic reconnection is examined using fully kinetic simulations with a Monte-Carlo treatment of the Fokker-Planck collision operator. This powerful first-principles approach offers a bridge between kinetic and fluid regimes, which may prove useful for understanding the applicability of various fluid models. In order to lay the necessary groundwork, the collision algorithm is first carefully bench marked for a homogeneous plasma against theoretical predictions for beam-plasma interactions and electrical resistivity. Next, the collisional decay of a current layer is examined as a function of guide field, allowing direct comparisons with transport theory for the parallel and perpendicular resistivity as well as the thermoelectric force. Finally, the transition between collisional and collision less reconnection is examined in neutral sheet geometry. For modest Lundquist numbers S {approx}< 1000, a distinct transition is observed when the thickness of the Sweet-Parker layers falls below the ion inertia length {delta}{sub sp} {approx}< d,. At higher Lundquist number, deviations from the Sweet-Parker scaling are observed due to the growth of plasmoids (secondary-islands) within the elongated resistive layer. In certain cases, this instability leads to the onset of fast reconnection sooner than expected from {delta}{sub sp} {approx} d, condition. After the transition to fast reconnection, elongated electron current layers are formed which are unstable to the formation of new plasmoids. The structure and time-dependence of the electron diffusion region in these semi-collisional regimes is profoundly different than reported in two-fluid simulations.

Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim S [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Karimabadi, Homa [UCSD

2009-01-01

292

KINETIC PLASMA TURBULENCE IN THE FAST SOLAR WIND MEASURED BY CLUSTER  

SciTech Connect

The k-filtering technique and wave polarization analysis are applied to Cluster magnetic field data to study plasma turbulence at the scale of the ion gyroradius in the fast solar wind. Waves are found propagating in directions nearly perpendicular to the background magnetic field at such scales. The frequencies of these waves in the solar wind frame are much smaller than the proton gyrofrequency. After the wavevector k is determined at each spacecraft frequency f{sub sc}, wave polarization property is analyzed in the plane perpendicular to k. Magnetic fluctuations have {delta}B > {delta}B{sub Parallel-To} (here the Parallel-To and refer to the background magnetic field B{sub 0}). The wave magnetic field has right-handed polarization at propagation angles {theta}{sub kB} < 90 Degree-Sign and >90 Degree-Sign . The magnetic field in the plane perpendicular to B{sub 0}, however, has no clear sense of a dominant polarization but local rotations. We discuss the merits and limitations of linear kinetic Alfven waves (KAWs) and coherent Alfven vortices in the interpretation of the data. We suggest that the fast solar wind turbulence may be populated with KAWs, small-scale current sheets, and Alfven vortices at ion kinetic scales.

Roberts, O. W.; Li, X. [Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth, Ceredigion SY23 3BZ (United Kingdom); Li, B., E-mail: xxl@aber.ac.uk [School of Space Science and Physics, Shandong University, Weihai 246209 (China)

2013-05-20

293

Detection of the kinetic geodesic acoustic mode (KGAM) near the centre region of JIPPT-IIU tokamak plasmas  

NASA Astrophysics Data System (ADS)

The broad and intense spectrum of the geodesic acoustic mode (GAM) oscillations near the magnetic axis of tokamak plasmas with Te/Ti Gt 1 becomes narrow and weak during neutral beam heating. It then becomes wide and weak during third harmonics ICRF heating. The wide spectra of GAMs are generally consistent with recent kinetic GAM (KGAM) theories.

Hamada, Y.; Watari, T.; Nishizawa, A.; Yamagishi, O.; Narihara, K.; Ida, K.; Kawasumi, Y.; Ido, T.; Kojima, M.; Toi, K.; JIPPT-IIU Group

2011-03-01

294

Calculating the plasma deformation tensor and kinetic vorticity from magnetic field time series: Applications to the solar wind  

Microsoft Academic Search

It is shown that the magnetic induction equation reduces to an autoregressive model equation. Assuming weakly ergodic field variations in steady mean plasma flow, this model permits the estimation of the mean flow deformation tensor, velocity divergence and kinetic vorticity from magnetic field time series. Applications, made to hourly-averaged, in-ecliptic interplanetary magnetic field (IMF) measurements from Ulysses spacecraft, showed that

J. M. Polygiannakis; X. Moussas

1996-01-01

295

Negative-energy modes in a magnetically confined plasma in the framework of Maxwell-drift kinetic theory.  

National Technical Information Service (NTIS)

The general expression for the second-order perturbation energy of a Maxwell-drift kinetic system derived by Pfirsch and Morrison is evaluated for the case of a magnetically confined plasma for which the equilibrium quantities depend on one Cartesian coor...

G. N. Throumoulopoulos D. Pfirsch

1993-01-01

296

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

297

The GHIBLI plasma wind tunnel: Description of the new CIRA-PWT facility  

Microsoft Academic Search

A new plasma wind tunnel is under construction at the Italian Aerospace Research Centre (CIRA) located at Capua. It is named GHIBLI and the plasma is generated by a segmented arc heater whose power is about 2MW. Such a new facility will be able to perform test campaigns on models up to 80mm in diameter, and may be used to

Carlo Purpura; Federico De Filippis; Egidio Graps; Eduardo Trifoni; Raffaele Savino

2007-01-01

298

Magnetospheric Physics (Program Description)  

NSF Publications Database

... Magnetospheric Physics Description Supports research on the magnetized plasma envelope of the ... and waves and instabilities in the natural plasma. Also supported are ground-based observational ...

299

Dispersion characteristics of kinetic Alfven waves in a multi-ion plasma  

NASA Astrophysics Data System (ADS)

The stability of the kinetic Alfven wave (KAW) has been studied in a plasma composed of electrons, hydrogen and positively and negatively charged oxygen ions. Using the two potential theory of Hasegawa, we have derived an expression for the frequency and growth/damping rate of the KAW. The dispersion relation derived in this paper is a generalization of the dispersion relation of Hasegawa on two counts: (i) we use a more generalized distribution function and show that our relation reduces to the dispersion relation of Hasegawa in the limiting case, and (ii) it is applicable to a multi-ion plasma containing lighter ions and positively and negatively charged heavier ions. We find the growth rate of the wave increases with increasing drift velocities of the electrons. Negatively charged oxygen ions (O-) decrease the growth rate; however, the growth rate is very sensitively dependent on O- ion density, especially when its density is greater than that of the positively charged oxygen ions (O+). Interestingly, the dispersion characteristics of KAWs can be made insensitive to the presence of the heavier ions by an appropriate choice of their densities and temperatures.

Venugopal, Chandu; Jayapal, R.; Sreekala, G.; Jose, Blesson; Savithri Devi, E.; Antony, S.

2014-06-01

300

Implementation of the Kinetic Plasma Code with Locally Recursive non-Locally Asynchronous Algorithms  

NASA Astrophysics Data System (ADS)

Numerical simulation is presently considered impractical for several relevant plasma kinetics problems due to limitations of computer hardware even with the use of supercomputers. To overcome the existing limitations it is suggested to develop algorithms which would effectively utilize the computer memory subsystem hierarchy to optimize the dependency graph traversal rules. The ideas for general cases of numerical simulation and implementation of such algorithms to particle-in-cell code is discussed in the paper. This approach enables the simulation of previously unaccessible for modeling problems and the execution of series of numerical experiments in reasonable time. The latter is demonstrated on a multiscale problem of the development of filamentation instability in laser interaction with overdense plasma. One variant of the simulation with parameters typical for simulations on supercomputers is performed with the use of one cluster node. The series of such experiments revealed the dependency of energy loss on incoming laser pulse amplitude to be nonmonotonic and reach over 4%, an interesting result for research of fast ignition concept.

Perepelkina, A. Yu; Levchenko, V. D.; Goryachev, I. A.

2014-05-01

301

Kinetic modeling of electronically enhanced reaction pathways in Plasma Assisted Combustion  

NASA Astrophysics Data System (ADS)

The use of plasma energy to enhance and control the chemical reactions during combustion, a technology referred to as ``plasma assisted combustion'' (PAC), can result in a variety of beneficial effects: e.g. stable lean operation, pollution reduction, and wider range of p-T operating conditions. While experimental evidence abounds, theoretical understanding of PAC is at best incomplete, and numerical tools still lack in reliable predictive capabilities. In the context of a joint experimental-numerical effort at Michigan State University, we present here a modular Python framework dedicated to the dynamic optimization of non-equilibrium PAC systems. We first describe a novel kinetic global model, which aims at exploring scaling laws in parameter space, as well as the effect of a non-Maxwellian electron energy distribution function (EEDF). With such a model, we reproduce literature results and we critically review the effect of data uncertainty and limiting assumptions. Then, we explore means of measuring a non-Maxwellian EEDF through the use of a detailed collisional-radiative model, coupled to optical emission spectroscopy. Finally, we investigate the effect of different numerical integrators, as well as customized routines specifically designed to solve stiff sparse ODE systems.

Parsey, Guy; Gü?lü, Yaman; Verboncoeur, John; Christlieb, Andrew

2012-10-01

302

Nonlinear kinetic effects in inductively coupled plasmas via particle-in-cell simulations  

NASA Astrophysics Data System (ADS)

Kinetic effects in inductively coupled plasmas due to thermal motion of particles modified by self-consistent magnetic fields are studied using a particle-in-cell code. In the low pressure, low frequency regime, electron mean free paths are large relative to device size and the trajectories are strongly curved by the induced rf magnetic field. Analytic linear theories are unable to recover effects accumulated along each nonlinear path. Therefore, the simulated ICP is made progressively more complex to find the source of observed plasma behaviours. With only thermal motion modifying the wave-particle interaction, nonlocal behaviour becomes dominant at low frequencies, causing an anomalous skin effect with increased skin depth and power absorption and decreased ponderomotive force. However, when influenced by magnetic fields, the nonlocal effects are suppressed at large wave amplitudes due to nonlinear trapping. A mechanism is proposed for this low frequency restoration of local behaviour. Finally, a low rate of electron-neutral collisions is found to counteract the nonlinear behaviour, and hence reinforces nonlocal behaviour.

Froese, Aaron; Smolyakov, Andrei; Sydorenko, Dmytro

2007-11-01

303

Kinetics of plasmachemical processes in the expanding flow of nitrogen plasma  

NASA Astrophysics Data System (ADS)

The extended state-to-state kinetic model, taking into account the possibility of the formation of non-Boltzmann distribution over the vibrational levels for different electronic states (X1?+g, A3?+u, B3?g, a'1?-u and C3?u) of N2 molecules in strongly nonequilibrium conditions, has been built. The numerical analysis of the processes in the expanding supersonic flow of primary equilibrium nitrogen plasma has demonstrated that disruption of thermodynamic equilibrium in a supersonic flow results in the formation of plateau type vibrational distribution both in the ground X1?+g and in the excited electronic states. It has been shown that the neglect of the disruption of thermodynamic equilibrium between vibronic states of N2 molecules and translational degrees of freedom can lead to significant errors in the populations of vibrational levels even in the ground state of the N2 molecule, as well as in the concentrations of charged species and in the electron and translational temperatures. The principal processes responsible for the formation of non-Boltzmann distribution over vibrational levels, both in the ground and in the excited electronic states of the N2 molecule, are carefully investigated. It is revealed that in the expanding supersonic flow of nitrogen plasma the population inversion at the (B3?g,V ) ? (A3?+u,V +n) transition with V >24 and n = 1, 2 can form.

Kadochnikov, I. N.; Loukhovitski, B. I.; Starik, A. M.

2013-11-01

304

Absolute number density and kinetic analysis of the CF radical in pulsed CF4 + H2 radio-frequency plasmas  

NASA Astrophysics Data System (ADS)

The infrared tunable diode laser absorption spectroscopy (IR-TDLAS) experimental technique was employed to study CF radical kinetics in pulsed capacitively coupled CF4/H2 rf plasmas. In particular, the special data acquisition approach (so-called ‘burst mode’) was adapted and applied to monitor the absolute number density of CF with a temporal resolution of better than 1 ms. This enabled a proper kinetic analysis of the radical during both ‘plasma on’ and ‘plasma off’ phases. Thus, during the ‘plasma off’ phase, the CF species was found to be rapidly consumed, mostly in the reactor volume. Possible surface losses (sticking) of CF were shown to be of minor importance, and became notable only at total pressures lower than 10 Pa. During the ‘plasma on’ phase the CF concentration was measured to increase rapidly, reach a maximum and then decrease to its steady-state value. The observed overshoot in the CF density trace was shown to correlate with the corresponding decay of the C2F4 species also measured in the ‘plasma on’ phase. The electron impact fragmentation of C2F4 was supposed to contribute significantly to the effective production of CF at the beginning of the ‘plasma on’ phase, which might have caused the observed overshoots.

Stepanov, S.; Meichsner, J.

2012-04-01

305

A model of chlorophyll a fluorescence induction kinetics with explicit description of structural constraints of individual photosystem II units.  

PubMed

Chlorophyll a fluorescence induction (FI) kinetics, in the microseconds to the second range, reflects the overall performance of the photosynthetic apparatus. In this paper, we have developed a novel FI model, using a rule-based kinetic Monte Carlo method, which incorporates not only structural and kinetic information on PSII, but also a simplified photosystem I. This model has allowed us to successfully simulate the FI under normal or different treatment conditions, i.e., with different levels of measuring light, under 3-(3',4'-dichlorophenyl)-1,1-dimethylurea treatment, under 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone treatment, and under methyl viologen treatment. Further, using this model, we have systematically studied the mechanistic basis and factors influencing the FI kinetics. The results of our simulations suggest that (1) the J step is caused by the two-electron gate at the Q B site; (2) the I step is caused by the rate limitation of the plastoquinol re-oxidation in the plastoquinone pool. This new model provides a framework for exploring impacts of modifying not only kinetic but also structural parameters on the FI kinetics. PMID:23912704

Xin, Chang-Peng; Yang, Jin; Zhu, Xin-Guang

2013-11-01

306

Pulsar electrodynamics: Relativistic kinetic theory of radiative plasmas—collective phenomena and their radiation  

NASA Astrophysics Data System (ADS)

The classical modeling of radiation by accelerated charged particles in pulsars predicts a cutoff in photon energy at around 25 GeV. While this is broadly consistent with observations, the classical treatment is not self-consistent, and cannot be extended to explain the rare high-energy detections of photons in the 100s of GeV range. In this paper we revisit the theoretical modeling of high-energy radiation processes in very strong electromagnetic fields, in the context of both single particles and collective plasmas. There are no classical constraints on this description. We find that there is indeed a critical energy of around 50 GeV that arises naturally in this self-consistent treatment, but rather than being a cutoff, this critical energy signals a transition from radiation that is classical to a quasiquantum description, in which the particle is able to radiate almost its total energy in a single event. This new modeling therefore places pulsar radiation processes on a more secure physical basis, and admits the possibility of the production of TeV photons in a self-consistent way.

da Costa, A. A.; Diver, D. A.; Laing, E. W.; Stark, C. R.; Teodoro, L. F. A.

2011-01-01

307

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

308

Kinetics of plasma membrane and mitochondrial alterations in cells undergoing apoptosis  

SciTech Connect

Programmed cell death or apoptosis is characterized by typical morphological alterations. By transmission electron microscopy, apoptotic cells are identified by condensation of the chromatin in tight apposition to the nuclear envelope, alteration of the nuclear envelope and fragmentation of the nucleus, whereas integrity of the plasma membrane and organelles is preserved. Conversely cells undergoing necrosis display and early desintegration of cytoplasmic membrane and swelling of mitochondria. In this study we assessed by flow cytometry the sequential alterations of forward angle light scatter, 90{degrees} light scatter, and fluorescence associated with fluorescein diacetate, rhodamine 123, and propidium iodide in two human B cell lines undergoing apoptosis induced by the topoisomerase II inhibitor VP-16. The kinetics of these modifications were compared to those of cells undergoing necrosis induced by the topoisomerase II inhibitor VP-16. The kinetics of these modifications were compared to those of cells undergoing necrosis induced by sodium azide. At the same time intervals, cells were examined by transmission electron microscopy and by UV microscopy after staining with Hoechst 33342. We report that sequential changes in light scatters and fluorescein diacetate are similar in cells undergoing apoptosis or necrosis, whereas apoptosis is characterized by a slightly delayed decrease of mitochondrial activity as assessed by rhodamine 123 staining. Surprisingly, a part of cells undergoing apoptosis displayed an early uptake of propidium iodide followed by a condensation and then a fragmentation of their nuclei. It is concluded that uptake of propidium iodide is a very early marker of cell death which does not discriminate between necrosis and apoptosis. Along with biochemical criteria, nuclear morphology revealed by staining with Hoechst 33342 would seem to be of the most simple and most discriminative assay of apoptosis. 33 refs., 5 figs., 1 tab.

Lizard, G.; Fournel, S.; Genestier, L.; Dhedin, N. [Hospital Edouard Herriot, Lyon (France)] [and others

1995-11-01

309

Fast, kinetically self-consistent simulation of RF modulated plasma boundary sheaths  

NASA Astrophysics Data System (ADS)

A mathematical model is presented which enables the efficient, kinetically self-consistent simulation of RF modulated plasma boundary sheaths in all technically relevant discharge regimes. It is defined on a one-dimensional geometry where a Cartesian x-axis points from the electrode or wall at xE ? 0 towards the plasma bulk. An arbitrary endpoint xB is chosen ‘deep in the bulk’. The model consists of a set of kinetic equations for the ions, Boltzmann's relation for the electrons and Poisson's equation for the electrical field. Boundary conditions specify the ion flux at xB and a periodically—not necessarily harmonically—modulated sheath voltage V(t) or sheath charge Q(t). The equations are solved in a statistical sense. However, it is not the well-known particle-in-cell (PIC) scheme that is employed, but an alternative iterative algorithm termed ensemble-in-spacetime (EST). The basis of the scheme is a discretization of the spacetime, the product of the domain [xE, xB] and the RF period [0, T]. Three modules are called in a sequence. A Monte Carlo module calculates the trajectories of a large set of ions from their start at xB until they reach the electrode at xE, utilizing the potential values on the nodes of the spatio-temporal grid. A harmonic analysis module reconstructs the Fourier modes nim(x) of the ion density ni(x, t) from the calculated trajectories. A field module finally solves the Boltzmann-Poisson equation with the calculated ion densities to generate an updated set of potential values for the spatio-temporal grid. The iteration is started with the potential values of a self-consistent fluid model and terminates when the updates become sufficiently small, i.e. when self-consistency is achieved. A subsequent post-processing determines important quantities, in particular the phase-resolved and phase-averaged values of the ion energy and angular distributions and the total energy flux at the electrode. A drastic reduction of the computational effort compared with PIC calculations is achieved. As a first application of the new model, the influence of ion inertia on the dynamics of a collisionless sheath is studied and a comparison of the simulated ion energy distribution with published analytical solutions is performed.

Shihab, Mohammed; Ziegler, Dennis; Brinkmann, Ralf Peter

2012-05-01

310

A lattice kinetic Monte Carlo code for the description of vacancy diffusion and self-organization in Si  

Microsoft Academic Search

We have investigated the mechanism driving void evolution in crystalline Si by means of 'on lattice' kinetic Monte Carlo (MC) simulations. The implementation of an efficient algorithm allowed us to compare, on a macroscopic time scale, the predictions of simulation codes using three different binding models. We demonstrate that the use of a modified Ising model, taking also into account

A. La Magna; S. Coffa; L. Colombo

1999-01-01

311

Kinetics of memory B cell and plasma cell responses in the mice immunized with plague vaccines.  

PubMed

In our previous studies, we found that plague vaccines can induce long-term antibody response, but no significant antibody boost was observed when the immunized mice were challenged with virulent Yersinia pestis. However, a booster vaccination of subunit vaccine on week 3 after primary immunization elicited a significantly higher antibody titre than a single dose, whereas no significant antibody titre difference was observed between a single dose and two doses of EV76 vaccination. To address these issues, in this study, we first investigated the kinetics of memory B cells and plasma cells in the mice immunized with EV76 or F1 protein by flow cytometry and then determined antibody titre in five groups of mice immunized with various vaccination strategy. The results showed that memory B cells dropped to a low level at day 56 after primary immunization. In contrast, plasma cells were maintained for more than 98 days. The group with primary immunization of EV76 and booster of F1 antigen developed a higher antibody titre than the group with immunization of F1 antigen and booster of EV76. This result supports a hypothesis that an excess of antigens can neutralize pre-existing antibodies, and then the redundant antigen induces antibody boost. Taken together, a boost of antibody titre after revaccination may be dependent on the existence of memory B cells and an excess of antigen vaccination. In addition, this study showed an ideal immunization strategy that involves first immunization with a live attenuated vaccine, such as EV76, and then with a subunit vaccine. PMID:24383627

Zhang, X; Wang, Q; Bi, Y; Kou, Z; Zhou, J; Cui, Y; Yan, Y; Zhou, L; Tan, Y; Yang, H; Du, Z; Han, Y; Song, Y; Zhang, P; Zhou, D; Yang, R; Wang, X

2014-03-01

312

Shear viscosity of the quark-gluon plasma in a kinetic theory approach  

NASA Astrophysics Data System (ADS)

One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound ?/s=1/4? for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed ?/s and have a comparison with physical observables like elliptic flow.

Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.

2014-05-01

313

In vitro kinetics of nerve agent degradation by fresh frozen plasma (FFP).  

PubMed

Great efforts have been undertaken in the last decades to develop new oximes to reactivate acetylcholinesterase inhibited by organophosphorus compounds (OP). So far, a broad-spectrum oxime effective against structurally diverse OP is still missing, and alternative approaches, e.g. stoichiometric and catalytic scavengers, are under investigation. Fresh frozen plasma (FFP) has been used in human OP pesticide poisoning which prompted us to investigate the in vitro kinetics of OP nerve agent degradation by FFP. Degradation was rapid and calcium-dependent with the G-type nerve agents tabun, sarin, soman and cyclosarin with half-lives from 5 to 28 min. Substantially longer and calcium-independent degradation half-lives of 23-33 h were determined with the V-type nerve agents CVX, VR and VX. However, at all the tested conditions, the degradation of V-type nerve agents was several-fold faster than spontaneous hydrolysis. Albumin did not accelerate the degradation of nerve agents. In conclusion, the fast degradation of G-type nerve agents by FFP might be a promising tool, but would require transfusion shortly after poisoning. FFP does not seem to be suitable for detoxifying relevant agent concentrations in case of human poisoning by V-type nerve agents. PMID:24057572

Wille, Timo; Thiermann, Horst; Worek, Franz

2014-02-01

314

Super-thermal particles in hot plasmas—Kinetic models, numerical solution strategies, and comparison to tokamak experiments  

NASA Astrophysics Data System (ADS)

The excitation of collective instabilities by super-thermal particles in hot plasmas and the related transport processes attract increasing interest due to their fundamental challenges for theoretical models and their practical importance for burning fusion plasmas. In fact, the physics of a self-heated thermonuclear plasma due to fusion-born 3.5 MeV ?-particles is one of the most important outstanding fundamental research topics on the way to a fusion power plant with magnetic confinement. Within the last 10 years significant advances on both the theoretical and the experimental sides have been made leading to a more detailed and quantitative understanding of fast-particle-driven instabilities. On the theoretical side, the crucial step was to move from fluid models for the plasma background with a hybrid kinetic expression for the energetic particles to a fully kinetic model for all the plasma species, i.e. background ions, background electrons, and fast ions. This improvement allows one to describe consistently the resonant interaction between global plasma waves such as shear Alfvén and Alfvén-acoustic waves, and the particles via Landau damping, i.e. the dynamics parallel to the magnetic background field. Also, mode conversion mechanisms require the inclusion of background ion scales in a kinetic, non-perturbative way. This accurate treatment of the plasma background leads not only to changes in the linear mode properties such as frequency, growth/damping rate, and mode structure but also influences the non-linear dynamics. Due to major advances, innovations and installation of diagnostics in present day experiments, this comparison can be carried out in a more detailed and comprehensive way than a few years ago. For example, the measurement of damping rates via active external antennas, the imaging of 2D mode structures via electron-cyclotron-emission spectroscopy, and the direct detection of escaping fast ions allow to diagnose various kinetic features of the plasma modes that are responsible for the transport of energetic particles. Furthermore, the fast particle distribution function itself can also be measured with much greater confidence. Therefore, the new physics accessible due to a more comprehensive model and numerical implementation can be directly verified and validated with experimental data.

Lauber, Philipp

2013-12-01

315

Full description of copper uptake by algal biomass combining an equilibrium NICA model with a kinetic intraparticle diffusion driving force approach.  

PubMed

In this work kinetic and equilibrium studies related to copper binding to the protonated macroalga Sargassum muticum are reported. An intraparticle-diffusion linear driving force (LDF) model has been chosen for the quantitative description of the kinetics at several initial metal concentrations. Copper intraparticle homogeneous diffusion coefficient (D(h)) obtained is in the range 0.2-0.9×10(-10) m(2) s(-1). NICA isotherm is demonstrated to constitute a substantial improvement with respect to a simpler Langmuir competitive equation. The binding parameters were chosen to provide the best simultaneous description of the equilibrium experiments. Values of log K(Cu) (4.3), n(Cu) (1) and p (0.31) in NICA isotherm, and log K(Cu) (3.5-5) in Langmuir competitive model, have been obtained. These parameters have been also used to predict the competition between copper and cadmium for binding sites. Two acids, HNO(3) and HCl, have been tested to evaluate their effectiveness to release copper from the metal-laden biomass. PMID:20980146

Herrero, Roberto; Lodeiro, Pablo; García-Casal, Lino J; Vilariño, Teresa; Rey-Castro, Carlos; David, Calin; Rodríguez, Pilar

2011-02-01

316

Kinetic Study of the Solid-State Transformation of Vacuum-Plasma-Sprayed Ti-6Al-4V Alloy  

NASA Astrophysics Data System (ADS)

Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of ? phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of ?-phase grain boundary, and the second mechanism was ?-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the phase transformation at different constant temperatures, a time-temperature-transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.

Salimijazi, H. R.; Mousavi, Z. A.; Golozar, M. A.; Mostaghimi, J.; Coyle, T.

2014-01-01

317

LSENS, a general chemical kinetics and sensitivity analysis code for homogeneous gas-phase reactions. 2: Code description and usage  

NASA Technical Reports Server (NTRS)

LSENS, the Lewis General Chemical Kinetics Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 2 of a series of three reference publications that describe LSENS, provide a detailed guide to its usage, and present many example problems. Part 2 describes the code, how to modify it, and its usage, including preparation of the problem data file required to execute LSENS. Code usage is illustrated by several example problems, which further explain preparation of the problem data file and show how to obtain desired accuracy in the computed results. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions. Part 1 (NASA RP-1328) derives the governing equations describes the numerical solution procedures for the types of problems that can be solved by lSENS. Part 3 (NASA RP-1330) explains the kinetics and kinetics-plus-sensitivity-analysis problems supplied with LSENS and presents sample results.

Radhakrishnan, Krishnan; Bittker, David A.

1994-01-01

318

Spatially modulated phase in the holographic description of quark-gluon plasma.  

PubMed

We present a string theory construction of a gravity dual of a spatially modulated phase. Our earlier work shows that the Chern-Simons term in the five-dimensional Maxwell theory destabilizes the Reissner-Nordström black holes in anti-de Sitter space if the Chern-Simons coupling is sufficiently high. In this Letter, we show that a similar instability is realized on the world volume of 8-branes in the Sakai-Sugimoto model in the quark-gluon plasma phase. Our result suggests a new spatially modulated phase in quark-gluon plasma when the baryon density is above 0.8Nf??fm(-3) at temperature 150 MeV. PMID:21405455

Ooguri, Hirosi; Park, Chang-Soon

2011-02-11

319

Cell-Free Fetal DNA in Maternal Plasma during Physiological Single Male Pregnancies: Methodology Issues and Kinetics  

Microsoft Academic Search

Objective: To analyze methodological influences and characterize the concentrations of cell-free fetal DNA (cffDNA) circulating in maternal plasma at different gestational ages in physiological pregnancies. Methods: We investigated 238 independent samples from single male-bearing pregnancies of different gestation age. In the other 50 pregnancies, the samples were collected three times during pregnancy (at all trimesters) to evaluate the kinetics of

Ales Horinek; Marie Korabecna; Ales Panczak; Zdenka Ulcova Gallova; Kamila Nouzova; Pavel Calda; Miroslava Hancarova

2008-01-01

320

The parameters of plasma and the kinetics of generation and loss of active particles in chlorine-nitrogen mixtures  

Microsoft Academic Search

An investigation is performed of the effect of the initial composition of Cl2\\/N2 mixture on the electrophysical and kinetic parameters of plasma of a dc glow discharge. It is found that the dilution of\\u000a chlorine with nitrogen causes a variation of the electron energy distribution function (EEDF), which is accompanied by an\\u000a increase in the average electron energy and in

A. M. Efremov; D. V. Sitanov; V. I. Svettsov

2008-01-01

321

TORE SUPRA first-wall description and behaviour during the initial plasma experiments  

NASA Astrophysics Data System (ADS)

TORE SUPRA is a large-size, high-field superconducting tokamak ( B ? = 4.5 T, R = 2.37 m, a = 0.8 m). It has been completed in the beginning of 1988 and is starting its experimental operation. The plasma-wall interaction programme will be mainly devoted to obtaining very long pulses in the next future, i.e. the control of impurity content, power and particule exhaust. The design of the first-wall items takes this into account. The inner wall is made of graphite tiles brazed on stainless steel tubes, the outer wall of stainless steel panels. Moreover, three graphite limiters and six ergodic divertor modules have already been installed. Each of these elements is water-cooled ( T water = 150-230 °C, p = 3.6 Mpa). Vessel pumping is achieved by means of three turbomolecular pumps providing 9000 1/s H 2 pumping speed. A 250 °C baking capability of the vessel is also available. First operations were mainly devoted to conditioning and carbonizing the whole plasma chamber, with RG discharges, allowing to work in homogeneous conditions. The first tokamak discharges are studied for a better knowledge of plasma control and stability in this configuration. Then, power deposition will be particularly investigated so as to prepare for the next steps: additional power and pump limiter operation.

Grosman, A.; Achard, M.-H.; Chappuis, P.; Cordier, J.-J.; Deschamps, P.; Gauthier, E.; Lipa, M.

1989-04-01

322

Kinetic Simulations of the Lunar Plasma Environment with the VORPAL Framework  

Microsoft Academic Search

Numerical simulations help gaining insight into the lunar plasma environment, which is of importance to the design of human habitats or instruments. We report on a massively parallel plasma simulation code used to investigate these dusty plasmas.

P. Messmer; M. Horanyi; Z. Sternovsky; S. Robertson

2008-01-01

323

Kinetic Simulations of the Lunar Plasma Environment with the VORPAL Framework  

NASA Astrophysics Data System (ADS)

Numerical simulations help gaining insight into the lunar plasma environment, which is of importance to the design of human habitats or instruments. We report on a massively parallel plasma simulation code used to investigate these dusty plasmas.

Messmer, P.; Horanyi, M.; Sternovsky, Z.; Robertson, S.

2008-07-01

324

Chemical kinetics and reactive species in atmospheric pressure helium-oxygen plasmas with humid-air impurities  

NASA Astrophysics Data System (ADS)

In most applications helium-based plasma jets operate in an open-air environment. The presence of humid air in the plasma jet will influence the plasma chemistry and can lead to the production of a broader range of reactive species. We explore the influence of humid air on the reactive species in radio frequency (rf)-driven atmospheric-pressure helium-oxygen mixture plasmas (He-O2, helium with 5000 ppm admixture of oxygen) for wide air impurity levels of 0-500 ppm with relative humidities of from 0% to 100% using a zero-dimensional, time-dependent global model. Comparisons are made with experimental measurements in an rf-driven micro-scale atmospheric pressure plasma jet and with one-dimensional semi-kinetic simulations of the same plasma jet. These suggest that the plausible air impurity level is not more than hundreds of ppm in such systems. The evolution of species concentration is described for reactive oxygen species, metastable species, radical species and positively and negatively charged ions (and their clusters). Effects of the air impurity containing water humidity on electronegativity and overall plasma reactivity are clarified with particular emphasis on reactive oxygen species.

Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

2013-02-01

325

Spatial plasma potentials and electron energy distributions in inductively and capacitively coupled plasmas under a weakly collisional and nonlocal electron kinetic regime  

NASA Astrophysics Data System (ADS)

Spatial profiles of the plasma potential and electron energy distribution function (EEDF) were measured in inductively and capacitively coupled plasmas (ICP and CCP) under weakly collisional and nonlocal electron kinetic regimes [1]. The measured EEDF at the discharge center was a bi-Maxwellain distribution with low (T1) and high (T2) electron temperature groups at both the ICP and the CCP, while the EEDF at the radial boundary was closely Maxwellian distribution in the ICP due to cutting of the low energy electrons by relatively large ambipolar potential in this discharge regime. The ambipolar potential in the entire radial region was in the scale of Teff -1.5 Teff, where Teff is the effective electron temperature. At the boundary region with the ion mean free path scale, the ambipolar potential increased abruptly and was about Teff,edge/2, where the Teff,edge is the effective electron temperature at the boundary, which corresponds to the presheath scale. These results of the ICP, which are contrary to the ambipolar potential of the CCP in a nearly free-fall regime [2], are caused by relatively high T1 and a small portion of low energy electron group density to total electron density in the ICP under the weakly collisional and nonlocal electron kinetic regimes. [4pt] [1] H. C. Lee and C. W. Chung, Phys. Plasmas 19 033514 (2012).[0pt] [2] V. A. Godyak, V. P. Meytlis, and H. R. Strauss, IEEE Trans. Plasma Sci. 23 728 (1995).

Lee, Hyo-Chang; Chung, Chin-Wook

2012-10-01

326

INTERMITTENT HEATING IN SOLAR WIND AND KINETIC SIMULATIONS  

SciTech Connect

Low-density astrophysical plasmas may be described by magnetohydrodynamics at large scales, but require kinetic description at ion scales in order to include dissipative processes that terminate the cascade. Here kinetic plasma simulations and high-resolution spacecraft observations are compared to facilitate the interpretation of signatures of various dissipation mechanisms. Kurtosis of increments indicates that kinetic scale coherent structures are present, with some suggestion of incoherent activity near ion scales. Conditioned proton temperature distributions suggest heating associated with coherent structures. The results reinforce the association of intermittent turbulence, coherent structures, and plasma dissipation.

Wu, P.; Wan, M.; Matthaeus, W. H.; Shay, M. A. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Perri, S. [Dipartimento di Fisica, Universita della Calabria, I-87036 Cosenza (Italy); Osman, K.; Chapman, S. [Centre for Fusion, Space and Astrophysics, University of Warwick (United Kingdom); Goldstein, M. L. [NASA/GSFC, Greenbelt, MD (United States); Karimabadi, H., E-mail: penny@udel.edu, E-mail: whm@udel.edu [University of California at San Diego, La Jolla, CA 92093 (United States)

2013-02-01

327

Kinetic and thermodynamic properties of a convecting plasma in a two-dimensional dipole field  

NASA Technical Reports Server (NTRS)

Charged particle guiding center motion is considered in the magnetic field of a two-dimensional ('line') dipole on which is superimposed a small, static, perpendicular electric field. The parallel equation of motion is that of a simple harmonic oscillator for cos theta, the cosine of magnetic colatitude theta. Equations for the perpendicular electric and magnetic drifts are derived as well as their bounce-averaged forms. The latter are solved to yield a bounce-averaged guiding center trajectory, which is the same as that obtained from conversation of magnetic moment mu, longitudinal invariant J, and total (kinetic plus electrostatic) energy K. The algebraic simplicity of the trajectory equations is also manifest in the forms of the invariants. An interesting result is that guiding centers drift in such a way that they preserve the values of their equatorial pitch angles and (equivalently) mirror latitudes. The most general Maxwellian form of the equilibrium one-particle distribution function f is constructed from the invariants, and spatially varying density and pressure moments, parallel and perpendicular to the magnetic field, are identified. Much of the paper deals with the more restricted problem in which f is specified as a bi-Maxwellian over a straight line of finite length in the equatorial plane of the dipole and perpendicular to field lines. This might be thought of as specifying a cross-tail ion injection source; our formalism then describes the subsequent spatial development. The distribution away from the source is a scaled bi-Maxwellian but one that is cut off at large and small kinetic energies, which depend on position. Density and pressure components are reduced from the values they would have if the total content of individual flux tubes convected intact. The equatorial and meridional variations of density and pressure components are examined and compared systematically for the isotropic and highly anisotropic situations. There appears to be little qualitative difference due to anisotropy. An anisotropy measure is defined, and its spatial variation determined as a signature of possible MHD instability. Extreme values are found, larger than at the source, but the plasma beta in such regions is probably so low as to render the effect inconsequential energetically. Finally, the possible consequence of 'nonadia- batic' pressure profiles on electrostatic interchanges is considered, and a boundary delineating stabilizing and destabilizing regions determined.

Huang, T. S.; Birmingham, T. J.

1994-01-01

328

Kinetics of the Reactions Involving CF2 and CF in a Pure Tetrafluoromethane Plasma: I. Production of CF2 and CF via Electron-Impact Dissociation  

NASA Astrophysics Data System (ADS)

The kinetics of the production and loss of CF2 and CF radicals in a glow discharge in pure CF4 is investigated by the laser-induced fluorescence method. The effective rate constants for electron-impact dissociation of CF4 molecules along the pathways toward CF2 and CF radicals are determined within a wide range of the reduced electric field (80-250 Td). It is shown that, along with the direct electron-impact dissociation of CF4, the radicals are also produced via the dissociation of the CxFy polymer fluorocarbon particles that form in the plasma. A detailed analysis of the kinetics of the radical production and loss in a modulated discharge made it possible to evaluate the contribution of the electron-impact dissociation of CF4 to the production of radicals and, consequently, to determine the dissociation rate constants k_{CF_2 } and k CF. A comparison of the obtained k_{CF_2 } and k CF values with the results of calculations by the Monte Carlo method and the literature data on the cross sections for electron-impact dissociation of CF4 molecules enabled the normalization of these cross sections in the threshold region and the construction of the model cross sections for the electron-impact dissociation of CF4 into neutral products. The calculated cross sections allow a satisfactory description of the experimental results throughout the entire range of E/N under study. A significant scatter (up to 100%) in the experimental data on k_{CF_2 } and k CF at low values of E/N is related to the considerable contribution of the CxFy polymer molecules (and, probably, CxF{y/+} ions and fluorocarbon grains) to the production of CF2 and CF radicals both in the plasma volume and on the surface of a fluorocarbon film covering the discharge tube wall.

Ivanov, V. V.; Klopovskii, K. S.; Lopaev, D. V.; Proshina, O. V.; Rakhimov, A. T.; Rakhimova, T. V.; Rulev, G. B.

2002-03-01

329

Co-existence of Whistler Waves with Kinetic Alfven Wave Turbulence for the High-Beta Solar Wind Plasma*  

NASA Astrophysics Data System (ADS)

It is shown that the dispersion relation for whistler waves is identical for a high or low beta plasma. Furthermore in the high-beta solar wind plasma whistler waves meet the Landau resonance with electrons for velocities less than the thermal speed, and consequently the electric force is small compared to the mirror force. As whistlers propagate through the inhomogeneous solar wind, the perpendicular wave number increases through refraction, increasing the Landau damping rate. However, the whistlers are not damped since the background kinetic Alfven wave turbulence creates a plateau by quasilinear diffusion in the solar wind electron distribution at small velocities [Rudakov et al., 2011]. The diffusion coefficient for whistlers in a high beta plasma is determined from mirror force. For a whistler spectrum similar to that of KAW, it is found that for whistler energy density of only ~10-3 of the kinetic Alfven waves, the quasilinear diffusion rate due to whistlers and KAW are comparable. Thus very small amplitude whistler turbulence can have a significant consequence on the evolution of the solar wind electron distribution function. L. Rudakov, M. Mithaiwala, G. Ganguli, and C. Crabtree. Phys. Plasmas 18, 012307 (2011) * Supported by Naval Research Laboratory Base Program

Mithaiwala, M.; Rudakov, L.; Ganguli, G.; Crabtree, C. E.

2012-12-01

330

Mechanisms of lipid peroxidation in human blood plasma: a kinetic approach  

Microsoft Academic Search

There is strong evidence that the oxidation of plasma lipoproteins plays an important role in atherogenesis. The exact mechanisms by which lipoprotein oxidation occurs in the presence of other plasma constituents, however, remains unclear. To investigate the role of different antioxidants for this process, we studied the oxidation of human plasma supplemented in vitro with physiological amounts of major plasma

Barbara Karten; Ulrike Beisiegel; Günther Gercken; Anatol Kontush

1997-01-01

331

Self-consistent surface kinetics models for plasma etching and deposition processes  

NASA Astrophysics Data System (ADS)

Gas-phase etching and deposition are among the most important processes in modern integrated circuit manufacturing and Micro-Electro-Mechanical-Systems (MEMS) fabrication. Developing simulation tools driven by improved etching and deposition models can facilitate an in-depth understanding of various processes. It can also help bring down the development cost of new processes. The focus of this work was on developing analytical self-consistent feature scale models, which were incorporated into our etch and deposition profile simulator, SPEEDIE. A self-consistent approach, in both flux transport and surface velocity calculations, enabled us to analytically model more complex surface kinetics such as chemical reactions. It also gave the models more physical meaning and empowered us with tools to discover phenomena, which would otherwise go unnoticed. Our approach was based on Langmuir adsorption model and mass/site balance equations. Using this approach, surface recombination of species was recognized as an important surface reaction mechanism, especially for predicting Aspect Ratio Dependent Etching (ARDE). In addition, a model was developed for the calculation of ion flux reflection from feature sidewalls in order to simulate micro-trenching phenomenon in silicon etching. A similar self-consistent approach was used to incorporate chemical reaction rates in analytical feature scale simulations. This reaction rate method was verified for tungsten chemical vapor deposition. The site balance approach was used to develop a self-consistent model for ion-enhanced deposition of CFx polymer in C4F8 plasma. This deposition is an important part of the Bosch deep trench etch process.

Abdollahi-Alibeik, Shahram

332

Unified First Principles Description from Warm Dense Matter to Ideal Ionized Gas Plasma: Electron-Ion Collisions Induced Friction  

SciTech Connect

Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

Dai Jiayu; Hou Yong; Yuan Jianmin [Department of Physics, College of Science, National University of Defense Technology, Changsha 410073 (China)

2010-06-18

333

Chemical kinetics of radio-frequency driven atmospheric-pressure helium-oxygen plasmas in humid air  

NASA Astrophysics Data System (ADS)

We describe the chemical kinetics of radio-frequency (rf) driven atmospheric-pressure helium-based plasmas in ambient air as determined through a zero-dimensional time-dependent global model. The effects of humid-air admixtures on the plasma-induced chemical reactions and the evolution of species concentrations in the helium-oxygen mixture (He-O2, helium with 5000 ppm admixture of oxygen) are studied for wide air impurity levels of 1-5000 ppm with the relative humidity of 0-100%. Comparisons made with experiments using an rf driven micro-scale atmospheric pressure plasma jet and one-dimensional simulations suggest that the plausible air impurity level in the experiments is not more than hundreds ppm. Effects of the air impurity containing water-humidity on electro-negativity and chemical activity are clarified with particular emphasis on reactive oxygen species.

Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William

2011-11-01

334

Measurement of free radical kinetics in pulsed plasmas by UV and VUV absorption spectroscopy and by modulated beam mass spectrometry  

NASA Astrophysics Data System (ADS)

This paper reviews recent progress in the development of time-resolved diagnostics to probe high-density pulsed plasma sources. We focus on time-resolved measurements of radicals' densities in the afterglow of pulsed discharges to provide useful information on production and loss mechanisms of free radicals. We show that broad-band absorption spectroscopy in the ultraviolet and vacuum ultraviolet spectral domain and threshold ionization modulated beam mass spectrometry are powerful techniques for the determination of the time variation of the radicals' densities in pulsed plasmas. The combination of these complementary techniques allows detection of most of the reactive species present in industrial etching plasmas, giving insights into the physico-chemistry reactions involving these species. As an example, we discuss briefly the radicals' kinetics in the afterglow of a SiCl4/Cl2/Ar discharge.

Cunge, G.; Bodart, P.; Brihoum, M.; Boulard, F.; Chevolleau, T.; Sadeghi, N.

2012-04-01

335

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

NASA Technical Reports Server (NTRS)

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

Roth, J. R.

1977-01-01

336

Retrospective descriptive analysis of the physiological kinetics of prostate-specific antigen in men older than 75 years.  

PubMed

Several studies have compared prostate-specific antigen (PSA) kinetics in men with and without cancer, but there has been no adequate analysis of the longitudinal variation in PSA. The aim of this study was to assess the fluctuations in PSA in a cohort of elderly men in an attempt to define a physiological pattern of PSA kinetics. We searched a specific cohort of patients aged > 75 years and with PSA value < 2.0 ng mL(-1). A history of all PSA values over the past 10 years was compiled for each patient to create a database of patients fitting the following criteria: (1) minimum of five PSA measurements, (2) over at least 5 years. Exclusion criteria were: (1) PSA < 0.2 ng mL(-1) at each measurement and (2) having had more than one PSA test per year. In all, 1 327 patients (mean age: 78.52 years) fit the inclusion criteria. The mean variation from the first to the last PSA test was 0.05 +/- 0.43, with a mean follow-up of 6.79 +/- 1.71 years. Over the same period, the mean fluctuation from the lowest to the highest PSA value was 0.04 +/- 0.55 (P = 0.925). The mean annual PSA velocity (PSAV) was calculated by dividing the mean variation from the first to the last PSA test by the number of years of observation for each patient and was set at 0.0104 +/- 0.1050. Concluding, in a large-scale cohort of elderly individuals considered healthy and evaluated for a considerable follow-up, the average annual PSAV as well as the average fluctuation from the lowest to the highest PSA value are insignificant. PMID:19448643

Sighinolfi, Maria Chiara; Micali, Salvatore; De Stefani, Stefano; Cicero, Arrigo; Cianci, Filippo; Giacometti, Marco; Bianchi, Giampaolo

2009-07-01

337

Kinetic simulation of radio-frequency driven plasmas in He/O2 mixtures at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Over the past years microplasma research gained a lot of attention both from an experimental and theoretical perspective. One particular type of microplasma sources that shows a variety of interesting physics and applications are radio-frequency plasma jets. This contribution investigates radio-frequency driven plasmas with an electrode gap of below 1 mm. The discharge is operated in a mixture of He and O2 (0.5 percent) at atmospheric pressure. A typical simulation of this kind of discharges is based on the hydrodynamic approximation of the relevant species. Sometimes this approach is extended by a quasi-kinetic treatment of the fast electron component (hybrid codes). Still certain kinetic effects are neglected in both of these methods. In this work a 1d self-consistent Particle-in-Cell model of the discharge is developed, to investigate kinetic effects and to verify the validity of the corresponding fluid model. All the relevant species and reactions regarding the underlying chemistry are taken into account by means of a Monte Carlo Collision model.

Eremin, Denis; Hemke, Torben; Brinkmann, Ralf Peter; Mussenbrock, Thomas

2011-11-01

338

A Fractional Differential Kinetic Equation and Applications to Modelling Bursts in Turbulent Nonlinear Space Plasmas  

NASA Astrophysics Data System (ADS)

Since the 1960s Mandelbrot has advocated the use of fractals for the description of the non-Euclidean geometry of many aspects of nature. In particular he proposed two kinds of model to capture persistence in time (his Joseph effect, common in hydrology and with fractional Brownian motion as the prototype) and/or prone to heavy tailed jumps (the Noah effect, typical of economic indices, for which he proposed Lévy flights as an exemplar). Both effects are now well demonstrated in space plasmas, notably in the turbulent solar wind. Models have, however, typically emphasised one of the Noah and Joseph parameters (the Lévy exponent ? and the temporal exponent ?) at the other's expense. I will describe recent work in which we studied a simple self-affine stable model-linear fractional stable motion, LFSM, which unifies both effects and present a recently-derived diffusion equation for LFSM. This replaces the second order spatial derivative in the equation of fBm with a fractional derivative of order ?, but retains a diffusion coefficient with a power law time dependence rather than a fractional derivative in time. I will also show work in progress using an LFSM model and simple analytic scaling arguments to study the problem of the area between an LFSM curve and a threshold. This problem relates to the burst size measure introduced by Takalo and Consolini into solar-terrestrial physics and further studied by Freeman et al [PRE, 2000] on solar wind Poynting flux near L1. We test how expressions derived by other authors generalise to the non-Gaussian, constant threshold problem. Ongoing work on extension of these LFSM results to multifractals will also be discussed.

Watkins, N. W.; Rosenberg, S.; Sanchez, R.; Chapman, S. C.; Credgington, D.

2008-12-01

339

Radu Balescu and the search for an stochastic description of turbulent transport in plasmas  

SciTech Connect

An idea that the late Prof. Radu Balescu often pondered during his long and distinguished scientific career was the possibility of constructing simple stochastic or probabilistic models able to capture the basic features of the complex dynamics of turbulent transport in magnetically confined plasmas. In particular, the application of the continuous-time random walk (CTRW) concept to this task was one of his favorites. In the last few years prior to his death, we also became interested in applying (variations of the standard) CTRW to these problems. In our case, it was the natural way to move beyond the simple paradigms based on sandpile constructs that we had been previously studying. This common interest fueled an intense electronic correspondence between Prof. Balescu and us that started in 2004 and was only interrupted by his unexpected death in June 2006. In this paper, we pay tribute to his memory by reviewing some of these exciting concepts that interested him so much and by sketching the problems and ideas that we discussed so frequently during these two years. Regretfully, he will no longer be here to help us solve them.

Sanchez, Raul [ORNL; Carreras, Benjamin A [ORNL; van Milligen, B. Ph. [Asociacion EURATOM-CIEMAT

2007-01-01

340

Temporal description of aluminum laser-induced plasmas by means of a collisional-radiative model  

NASA Astrophysics Data System (ADS)

A 0D numerical approach including a Collisional-Radiative model is elaborated in the purpose of describing the behavior of the nascent plasma resulting from the interaction between a laser pulse (? = 532 nm, ? = 4 ns and F = 6.5 J cm?2) with an aluminum sample. The species considered are Al, Al+, Al2+ and Al3+ on their different excited states and free electrons. Both groups of particles are characterized by their translation temperature in thermal non-equilibrium state. Besides, each population density is assumed to be in chemical non-equilibrium and behaves freely through the seven involved elementary processes (electron impact induced excitation and ionization, elastic collisions, multi-photon ionization, inverse laser Bremsstrahlung, direct electron Bremsstrahlung and spontaneous emission). Atoms passing from sample to gas phase are described by considering classical vaporization phenomena so that the surface temperature is limited to values less than the critical point. The relative role of the elementary processes is discussed and the time-evolution of the excitation of the species is analyzed.

Morel, Vincent; Bultel, Arnaud; Chéron, Bruno G.

2014-05-01

341

A new approach to the application of the classic methods of physicochemical kinetics in the analysis of the efficiency of plasma technology of coal gasification  

Microsoft Academic Search

This work is devoted to the problem of improving the efficiency of new plasma technologies of coal combustion that have minimum negative environmental impact. In particular, the authors consider a general method of formulating and solving the inverse kinetic problem to elucidate advantages of plasma gasification.

E. I. Karpenko; B. N. Devyatov

1995-01-01

342

A new approach to the application of the classic methods of physicochemical kinetics in the analysis of the efficiency of plasma technology of coal gasification  

SciTech Connect

This work is devoted to the problem of improving the efficiency of new plasma technologies of coal combustion that have minimum negative environmental impact. In particular, the authors consider a general method of formulating and solving the inverse kinetic problem to elucidate advantages of plasma gasification.

Karpenko, E.I.; Devyatov, B.N. [Kutateladze Inst. of Thermal Physics, Novosibirsk (Russian Federation)

1995-07-01

343

Kinetic Theory of Inhomogeneous Bounded Plasmas. Pt. 1. The Vlasov-Poisson System of Equations.  

National Technical Information Service (NTIS)

The formal solution of the linearized Vlasov-Poisson system of equations is carried out for an inhomogeneous strong magnetized plasma column. The system considered is closely related to several experiments in magnetically confined cylindrical plasmas. A g...

C. J. Diaz

1980-01-01

344

Kinetic Simulation of Inhomogeneous Plasma with a Variable Sized Grid System  

NASA Technical Reports Server (NTRS)

Space plasmas are usually inhomogeneous and irregular. Particle in cell (PIC) plasma simulations, however, often consider the plasma to be homogeneous and periodic. Here non-periodic PIC simulations with inhomogeneities in the density, temperature and background magnetic field are considered. Boundary conditions and a variable sized grid system are discussed, along with an application to a magnetospheric plasma physics problem in the auroral zone.

Schriver, David

2003-01-01

345

Factors influencing nortriptyline steady-state kinetics: Plasma and saliva levels  

Microsoft Academic Search

Proportionality between dose and steady-state nortriptyline (NT) plasma levels was found both during initial treatment and after long-term treatment (years) within the NT Plasma level range of 20 to 296 ng\\/ml. There were day-to-day variations of 10% to 20% (coefficient of variation) but no systematic changes in plasma levels over time. A significant age variation in NT plasma levels was

Per Kragh-Sørensen; Niels-Erik Larsen

1980-01-01

346

Von Karman similarity decay of energy and the heating of protons and electrons in a kinetic plasma  

NASA Astrophysics Data System (ADS)

Decay in time of fluid scale fluctuation energy in undriven weakly collisional kinetic plasma turbulence is a problem of broad interest in space physics. We study this in systems large compared to the ion kinetic scales using fully electromagnetic particle-in-cell simulations initiated with transverse flow and magnetic disturbances, constant density, and a strong guide field. The observed energy decay is consistent with the von Karman hypothesis of similarity decay, in a formulation adapted to magnetohydrodyamics (MHD). Kinetic dissipation occurs at small scales, but the overall rate is apparently controlled by large scale dynamics, as it is in the hydrodynamic case. The mechanisms of kinetic dissipation are of particular interest: At small turbulence amplitude the electrons are preferentially heated. At larger amplitudes proton heating is the dominant effect. We suggest this is due to availability of more channels for proton dissipation when the gradients produced by turbulence are larger at proton scales. In the solar wind and corona the protons are typically hotter, suggesting that these natural systems are in large amplitude turbulence regime.

Wu, P.; Wan, M.; Matthaeus, W. H.; Shay, M. A.; Swisdak, M. M.

2013-12-01

347

Kinetic Approach for Studying the Alpha Particle Transport in Plasma Liner Driven Magnetized Target Fusion  

Microsoft Academic Search

A new promising concept for producing energy from thermonuclear fusion is magnetized target fusion (MTF). In MTF, an imploding material liner is used to compress magnetized plasma to fusion ignition and to inertially confine the resulting burning plasma to obtain the necessary energy gain. Plasma liners have the potential to be formed in a repeatable, standoff manner and allow for

James Sommer

2003-01-01

348

Kinetic Analysis of Secretory Protein Traffic and Characterization of Golgi to Plasma Membrane Transport Intermediates in Living Cells  

PubMed Central

Quantitative time-lapse imaging data of single cells expressing the transmembrane protein, vesicular stomatitis virus ts045 G protein fused to green fluorescent protein (VSVG–GFP), were used for kinetic modeling of protein traffic through the various compartments of the secretory pathway. A series of first order rate laws was sufficient to accurately describe VSVG–GFP transport, and provided compartment residence times and rate constants for transport into and out of the Golgi complex and delivery to the plasma membrane. For ER to Golgi transport the mean rate constant (i.e., the fraction of VSVG–GFP moved per unit of time) was 2.8% per min, for Golgi to plasma membrane transport it was 3.0% per min, and for transport from the plasma membrane to a degradative site it was 0.25% per min. Because these rate constants did not change as the concentration of VSVG–GFP in different compartments went from high (early in the experiment) to low (late in the experiment), secretory transport machinery was never saturated during the experiments. The processes of budding, translocation, and fusion of post-Golgi transport intermediates carrying VSVG– GFP to the plasma membrane were also analyzed using quantitative imaging techniques. Large pleiomorphic tubular structures, rather than small vesicles, were found to be the primary vehicles for Golgi to plasma membrane transport of VSVG–GFP. These structures budded as entire domains from the Golgi complex and underwent dynamic shape changes as they moved along microtubule tracks to the cell periphery. They carried up to 10,000 VSVG–GFP molecules and had a mean life time in COS cells of 3.8 min. In addition, they fused with the plasma membrane without intersecting other membrane transport pathways in the cell. These properties suggest that the post-Golgi intermediates represent a unique transport organelle for conveying large quantities of protein cargo from the Golgi complex directly to the plasma membrane.

Hirschberg, Koret; Miller, Chad M.; Ellenberg, Jan; Presley, John F.; Siggia, Eric D.; Phair, Robert D.; Lippincott-Schwartz, Jennifer

1998-01-01

349

Application of modified moments method for kinetics description of nano-, micro-particles formation in gas phase  

NASA Astrophysics Data System (ADS)

The description of dynamics of particles size distribution function (PDF) in processes of new phase formation is important task in various technologies. Moments method is one of modern approaches which meet demands of accuracy and moderate usage of computer resources. Modified moments method which permits one to describe correctly both particles growth (in results of nucleation, coagulation and surface reactions) and gasification is proposed and developed in this work. Proposed approach connect correctly balance between growing particles and chemical precursors in contrary to present state of art. This is important when rates of particle decomposition, gasification, combustion are compatible with the rate of particle growth. The model calculations were carried out to show that approach gives incorrect rate of soot formation in the mentioned above case. Modified method of moment was applied for simulation of hydrocarbons combustion and conversion. In particular steam reforming of methane was simulated in details. The processes of soot formation include polycyclic aromatic hydrocarbon (PAH) lumping mechanism, soot formation in results of PAH coagulation in three dimensional structures, coagulation of soot particles, soot particles growth and gasification due to surface chemistry. Chemical mechanism also includes the general chemistry of methane decomposition with PAH and soot precursors formation. The comparison of theoretical and experimental results demonstrates that developed approach can describe species concentration and PDF evolution adequately.

Durov, A.; Deminsky, M.; Strelkova, M.; Potapkin, B. V.

2004-05-01

350

Calculating the Plasma Deformation Tensor and Kinetic Vorticity from Magnetic Field Time Series: Applications to the Solar Wind  

NASA Astrophysics Data System (ADS)

It is shown that the magnetic induction equation reduces to an autoregressive model equation. Assuming weakly ergodic field variations in steady mean plasma flow, this model permits the estimation of the mean flow deformation tensor, velocity divergence and kinetic vorticity from magnetic field time series. Applications, made to hourly-averaged, in-ecliptic interplanetary magnetic field (IMF) measurements from Ulysses spacecraft, showed that the direction of maximum deformation rate was, for most of the time, aligned to the mean field, while the vorticity tended to become perpendicular to the mean radial direction at large heliodistances.

Polygiannakis, J. M.; Moussas, X.

1996-07-01

351

Compact, accurate description of diagnostic neutral beam propagation and attenuation in a high temperature plasma for charge exchange recombination spectroscopy analysis  

NASA Astrophysics Data System (ADS)

Charge exchange recombination spectroscopy on Alcator C-Mod relies on the use of the diagnostic neutral beam injector as a source of neutral particles which penetrate deep into the plasma. It employs the emission resulting from the interaction of the beam atoms with fully ionized impurity ions. To interpret the emission from a given point in the plasma as the density of emitting impurity ions, the density of beam atoms must be known. Here, an analysis of beam propagation is described which yields the beam density profile throughout the beam trajectory from the neutral beam injector to the core of the plasma. The analysis includes the effects of beam formation, attenuation in the neutral gas surrounding the plasma, and attenuation in the plasma. In the course of this work, a numerical simulation and an analytical approximation for beam divergence are developed. The description is made sufficiently compact to yield accurate results in a time consistent with between-shot analysis.

Bespamyatnov, Igor O.; Rowan, William L.; Granetz, Robert S.

2008-10-01

352

Kinetic instability of the dust acoustic mode in inhomogeneous, partially magnetized plasma with both positively and negatively charged grains  

SciTech Connect

A purely kinetic instability of the dust acoustic mode in inhomogeneous plasmas is discussed. In the presence of a magnetic field, electrons and ions may be magnetized while at the same time dust grains may remain unmagnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species. It is shown that this may be a powerful mechanism for the excitation of dust acoustic waves. The analysis presented in the work is also directly applicable to plasmas containing both positive and negative ions and electrons, provided that at least one of the two ion species is unmagnetized.

Vranjes, J.; Poedts, S. [Centre for Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven (Belgium) and Leuven Mathematical Modeling and Computational Science Research Centre (LMCC), Celestijnenlaan 200B, 3001 Leuven (Belgium)

2010-08-15

353

Drift wave instability analysis in pair-ion-electron plasmas using kinetic approach  

SciTech Connect

Drift wave is studied in pair-ion plasmas in the presence of electrons using the Vlasov-Poisson set of equations. The growth rate of this universal instability depends on the concentration of electrons. The real frequency and the growth rate are reduced as the number density of electrons decreases. If the laboratory produced pair-ion plasmas contain relatively small amount of electrons then very low frequency almost stable drift waves can be produced which will indicate that the plasma is not a pure pair-ion plasma. The present investigation can be useful for future experiments on pair-ion plasmas and low density low temperature industrial plasmas which contain negative ions.

Ali, S.; Saleem, H. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan)

2010-09-15

354

Kinetic simulations of plasma sheath with parallel to the wall magnetic field  

NASA Astrophysics Data System (ADS)

Plasma-wall interactions can play an important role in plasma transport and confinement in tokamaks or Magneto-Inertial Fusion (MIF), where one of the approaches is to use an imploding metal liner to compress magnetized target plasma to thermonuclear temperatures. Since for the MIF applications the magnetic field is parallel to the liner surface, the ions, with their large gyro-radii, positively charge the wall. This creates a strong ExB shear flow which can cause turbulence and influence transport. Here we report on progress of the simulation studies of plasma sheath turbulence using a state-of-the-art VPIC [1] code. Baseline calculations have confirmed the possibility of establishing a quiescent plasma sheath in 1D for a flat liner surface[2,3]. However, in higher dimensions, these self-consistent plasma and field parameters do not always result in a stable sheath. In this work we present the analysis of a 2D equilibrium and quantify its stability characteristics for two cases, with Debye length being intermediate between electron and ion thermal Larmors and Debye length being much smaller than electron Larmor. [1] K. J. Bowers, et al. Phys. Plasmas 15, 055703 (2008). [2] N. Krasheninnikova, et al. Phys. Plasmas 17 057103 (2010). [3] N. Krasheninnikova, et al. Phys. Plasmas 17 063508 (2010).

Krasheninnikova, Natalia; Tang, Xianzhu

2010-11-01

355

Versatile code DLAYZ for investigating population kinetics and radiative properties of plasmas in non-local thermodynamic equilibrium  

NASA Astrophysics Data System (ADS)

A versatile code DLAYZ based on collisional-radiative model is developed for investigating the population kinetics and radiative properties of plasmas in non-local thermodynamic equilibrium. DLAYZ is implemented on the detailed level accounting (DLA) approach and can be extended to detailed configuration accounting (DCA) and hybrid DLA/DCA approaches. The code can treat both steady state and time-dependent problems. The implementation of the main modules of DLAYZ is discussed in detail including atomic data, rates, population distributions and radiative properties modules. The complete set of basic atomic data is obtained using relativistic quantum mechanics. For dense plasmas, the basic atomic data with plasma screening effects can be obtained. The populations are obtained by solving the coupled rate equations, which are used to calculate the radiative properties. A parallelized version is implemented in the code to treat the large-scale rate equations. Two illustrative examples of a steady state case for carbon plasmas and a time-dependent case for the relaxation of a K-shell excited argon are employed to show the main features of the present code.

Gao, Cheng; Zeng, Jiaolong; Li, Yongqiang; Jin, Fengtao; Yuan, Jianmin

2013-09-01

356

Integrated magnetic and kinetic control of advanced tokamak plasmas on DIII-D based on data-driven models  

NASA Astrophysics Data System (ADS)

The first real-time profile control experiments integrating magnetic and kinetic variables were performed on DIII-D in view of regulating and extrapolating advanced tokamak scenarios to steady-state devices and burning plasma experiments. Device-specific, control-oriented models were obtained from experimental data using a generic two-time-scale method that was validated on JET, JT-60U and DIII-D under the framework of the International Tokamak Physics Activity for Integrated Operation Scenarios (Moreau et al 2011 Nucl. Fusion 51 063009). On DIII-D, these data-driven models were used to synthesize integrated magnetic and kinetic profile controllers. The neutral beam injection (NBI), electron cyclotron current drive (ECCD) systems and ohmic coil provided the heating and current drive (H&CD) sources. The first control actuator was the plasma surface loop voltage (i.e. the ohmic coil), and the available beamlines and gyrotrons were grouped to form five additional H&CD actuators: co-current on-axis NBI, co-current off-axis NBI, counter-current NBI, balanced NBI and total ECCD power from all gyrotrons (with off-axis current deposition). Successful closed-loop experiments showing the control of (a) the poloidal flux profile, ?(x), (b) the poloidal flux profile together with the normalized pressure parameter, ?N, and (c) the inverse of the safety factor profile, \\bar{\\iota}(x)=1/q(x) , are described.

Moreau, D.; Walker, M. L.; Ferron, J. R.; Liu, F.; Schuster, E.; Barton, J. E.; Boyer, M. D.; Burrell, K. H.; Flanagan, S. M.; Gohil, P.; Groebner, R. J.; Holcomb, C. T.; Humphreys, D. A.; Hyatt, A. W.; Johnson, R. D.; La Haye, R. J.; Lohr, J.; Luce, T. C.; Park, J. M.; Penaflor, B. G.; Shi, W.; Turco, F.; Wehner, W.; the ITPA-IOS Group members; experts

2013-06-01

357

Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas  

Microsoft Academic Search

Fast time averaged equations are derived for the motion of particles and the generation of electromagnetic wake fields under the action of the ponderomotive potential of an ultraintense laser pulse propagating through a tenuous plasma. Based on these averaged equations, a new particle code is designed which calculates the particle trajectories on the plasma period time scale. The regime of

Patrick Mora; Thomas M. Antonsen Jr.

1997-01-01

358

Modelling of spectral properties and population kinetics studies of inertial fusion and laboratory-astrophysical plasmas  

NASA Astrophysics Data System (ADS)

Fundamental research and modelling in plasma atomic physics continue to be essential for providing basic understanding of many different topics relevant to high-energy-density plasmas. The Atomic Physics Group at the Institute of Nuclear Fusion has accumulated experience over the years in developing a collection of computational models and tools for determining the atomic energy structure, ionization balance and radiative properties of, mainly, inertial fusion and laser-produced plasmas in a variety of conditions. In this work, we discuss some of the latest advances and results of our research, with emphasis on inertial fusion and laboratory-astrophysical applications.

Mínguez, E.; Florido, R.; Rodríguez, R.; Gil, J. M.; Rubiano, J. G.; Mendoza, M. A.; Espinosa, G.; Martel, P.

2012-12-01

359

Plasma and milk kinetics of eprinomectin following topical or oral administration to lactating Chinese Holstein cows.  

PubMed

Chinese Holstein, bred by mating the Holstein-Friesian to Chinese Yellow Cattle, is a major dairy cattle breed in China. Eprinomectin is widely used in the treatment of nematode and ectoparasite infections in lactating cattle. The pharmacokinetics of eprinomectin in the plasma and milk were determined in Chinese Holstein cows following topical (at 0.5 mg kg(-1)) or oral (at 0.2 mg kg(-1)) administration. For topical administration, the concentrations of eprinomectin in plasma reached peak values (C(max)) of 16.16 ± 6.02 ng ml(-1) at 3.20 ± 1.30 days (T(max)). In milk, the C(max) values of 2.28 ± 0.85 ng ml(-1) were obtained at 3.48 ± 0.65 days. The MRT values were 5.00 ± 0.96 days for plasma and 4.65 ± 0.60 days for milk. The AUC values were 91.00 ± 25.32 ng d ml(-1) for plasma and 10.53 ± 1.55 ng d ml(-1) for milk. The ratio of AUC milk/plasma was 0.124 ± 0.041. Significant differences were found in C(max) and AUC of eprinomectin in plasma between Chinese Holstein and Prim Holstein following topical administration. It was probably due to the lower storage of body fat in Chinese Holstein than in Prim Holstein. For oral administration, the concentrations of eprinomectin reach peak values of 30.02 ± 5.73 ng ml(-1) at 1.60 ± 0.55 days in plasma and 3.14 ± 0.88 ng ml(-1) at 1.40 ± 0.27 days in milk. The MRT values for plasma and milk were 3.00 ± 0.46 and 3.18 ± 0.55 days, respectively. The AUC values were 98.46 ± 24.75 ng d ml(-1) for plasma and 10.42 ± 4.22 ng d ml(-1) for milk. The ratio of AUC milk/plasma was 0.104 ± 0.022. Compared with the topical administration, a significantly shorter MRT of eprinomectin in plasma was obtained following oral administration, which would shorten residue time of this compound in faeces and reduce its ecotoxicological effect. The low exposure of eprinomectin in milk would favor the use of eprinomectin in lactating Chinese Holstein for topical or oral administration. PMID:20851527

Wen, Huiqiang; Pan, Baoliang; Wang, Yuwan; Wang, Fangfei; Yang, Zhenzhong; Wang, Ming

2010-11-24

360

Kinetic parameters and intraindividual fluctuations of ochratoxin A plasma levels in humans  

Microsoft Academic Search

The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA\\/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic

Irène Studer-Rohr; Josef Schlatter; Daniel R. Dietrich

2000-01-01

361

Particle and fluid simulations of low-temperature plasma discharges: benchmarks and kinetic effects  

Microsoft Academic Search

Fluid, particle-in-cell and hybrid models are the numerical simulation techniques commonly used for simulating low-temperature plasma discharges. Despite the complexity of plasma systems and the challenges in describing and modelling them, well-organized simulation methods can provide physical information often difficult to obtain from experiments. Simulation results can also be used to identify research guidelines, find optimum operating conditions or propose

H C Kim; F Iza; S S Yang; M Radmilovi?-Radjenovi?; J K Lee

2005-01-01

362

TOPICAL REVIEW: Particle and fluid simulations of low-temperature plasma discharges: benchmarks and kinetic effects  

Microsoft Academic Search

Fluid, particle-in-cell and hybrid models are the numerical simulation techniques commonly used for simulating low-temperature plasma discharges. Despite the complexity of plasma systems and the challenges in describing and modelling them, well-organized simulation methods can provide physical information often difficult to obtain from experiments. Simulation results can also be used to identify research guidelines, find optimum operating conditions or propose

H. C. Kim; F. Iza; S. S. Yang; M. Radmilovic-Radjenovic; J. K. Lee

2005-01-01

363

Particle and fluid simulations of low-temperature plasma discharges: benchmarks and kinetic effects  

Microsoft Academic Search

Fluid, particle-in-cell and hybrid models are the numerical simulation techniques commonly used for simulating low-temperature plasma discharges. Despite the complexity of plasma systems and the challenges in describing and modelling them, well-organized simulation methods can provide physical information often difficult to obtain from experiments. Simulation results can also be used to identify research guidelines, find optimum operating conditions or propose

H C Kim; M Radmilovi ´ c-Radjenovic; J K Lee

364

Plasma kinetics of carbamazepine and its epoxide metabolite in man after single and multiple doses  

Microsoft Academic Search

Carbamazepine (Tegretol®) was administered orally to four patients as a single dose, and one week later three times daily for 15–21 days. The plasma half-lives of the drug were shorter in all patients after multiple doses (20.9±5.0 hours) than after the initial single dose (35.6±15.3 hours). During multiple doses the plasma concentrations of the metabolite carbamazepine-10,11-epoxide followed those of the

M. Eichelbaum; K. Ekbom; L. Bertilsson; V. A. Ringberger; A. Rane

1975-01-01

365

Kinetic modeling of evolution of 3 + 1:Resonance enhanced multiphoton ionization plasma in argon at low pressures  

NASA Astrophysics Data System (ADS)

We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5 Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10 s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

Tholeti, Siva Sashank; Shneider, Mikhail N.; Alexeenko, Alina A.

2014-06-01

366

Gyrokinetic turbulence simulations of high-beta tokamak and helical plasmas with full-kinetic and hybrid models  

NASA Astrophysics Data System (ADS)

Turbulent transport in high-beta toroidal plasmas is investigated by means of an electromagnetic gyrokinetic model and a newly developed electromagnetic hybrid model consisting of the gyrokinetic equation for ions and drift-Landau-fluid equations for electrons. Full gyrokinetic simulation results for Cyclone base case tokamak and for Large Helical Device (LHD) plasmas are quickly and accurately reproduced by the hybrid simulation. In the kinetic ballooning mode (KBM)-driven turbulence the ion heat and particle fluxes are mainly caused by electrostatic perturbation, and the contribution of magnetic perturbation is small and negative. The electron heat flux is caused by both electrostatic and magnetic perturbations. The numerical solutions satisfy the entropy balance equation, and the entropy is transferred from ions to electrons through electrostatic and magnetic perturbations. An analysis based on the entropy balance equation shows that the zonal structure is produced by magnetic nonlinearity corresponding to the Maxwell stress in the fluid limit but is weakened by the electrostatic one related to the Reynolds stress. A linear analysis on the standard configuration of LHD plasmas shows the suppression of the ion temperature gradient mode by finite-beta effects and the destabilization of KBM at high beta.

Ishizawa, A.; Maeyama, S.; Watanabe, T.-H.; Sugama, H.; Nakajima, N.

2013-05-01

367

Modeling of population kinetics of plasmas that are not in local thermodynamic equilibrium, using a versatile collisional-radiative model based on analytical rates.  

PubMed

We discuss the modeling of population kinetics of nonequilibrium steady-state plasmas using a collisional-radiative model and code based on analytical rates (ABAKO). ABAKO can be applied to low-to-high Z ions for a wide range of laboratory plasma conditions: coronal, local thermodynamic equilibrium or nonlocal thermodynamic equilibrium, and optically thin or thick plasmas. ABAKO combines a set of analytical approximations to atomic rates, which yield substantial savings in computer running time, still comparing well with more elaborate codes and experimental data. A simple approximation to calculate the electron capture cross section in terms of the collisional excitation cross section has been adapted to work in a detailed-configuration-accounting approach, thus allowing autoionizing states to be explicitly included in the kinetics in a fast and efficient way. Radiation transport effects in the atomic kinetics due to line trapping in the plasma are taken into account via geometry-dependent escape factors. Since the kinetics problem often involves very large sparse matrices, an iterative method is used to perform the matrix inversion. In order to illustrate the capabilities of the model, we present a number of results which show that the ABAKO compares well with customized models and simulations of ion population distribution. The utility of ABAKO for plasma spectroscopic applications is also outlined. PMID:20365078

Florido, R; Rodríguez, R; Gil, J M; Rubiano, J G; Martel, P; Mínguez, E; Mancini, R C

2009-11-01

368

Plasma and milk kinetic of eprinomectin and moxidectin in lactating water buffaloes (Bubalus bubalis).  

PubMed

The pharmacokinetics and mammary excretion of moxidectin and eprinomectin were determined in water buffaloes (Bubalus bubalis) following topical administration of 0.5mgkg(-1). Following administration of moxidectin, plasma and milk concentrations of moxidectin increased to reach maximal concentrations (C(max)) of 5.46+/-3.50 and 23.76+/-16.63ngml(-1) at T(max) of 1.20+/-0.33 and 1.87+/-0.77 days in plasma and milk, respectively. The mean residence time (MRT) were similar for plasma and milk (5.27+/-0.45 and 5.87+/-0.80 days, respectively). The AUC value was 5-fold higher in milk (109.68+/-65.01ngdayml(-1)) than in plasma (23.66+/-12.26ngdayml(-1)). The ratio of AUC milk/plasma for moxidectin was 5.04+/-2.13. The moxidectin systemic availability (expressed as plasma AUC values) obtained in buffaloes was in the same range than those reported in cattle. The faster absorption and elimination processes of moxidectin were probably due to a lower storage in fat associated with the fact that animals were in lactation. Nevertheless, due to its high excretion in milk and its high detected maximum concentration in milk which is equivalent or higher to the Maximal Residue Level value (MRL) (40ngml(-1)), its use should be prohibited in lactating buffaloes. Concerning eprinomectin, the C(max) were of 2.74+/-0.89 and 3.40+/-1.68ngml(-1) at T(max) of 1.44+/-0.20 and 1.33+/-0.0.41 days in plasma and milk, respectively. The MRT and the AUC were similar for plasma (3.17+/-0.41 days and 11.43+/-4.01ngdayml(-1)) and milk (2.70+/-0.44 days and 8.49+/-3.33ngdayml(-1)). The ratio of AUC milk/plasma for eprinomectin was 0.76+/-0.16. The AUC value is 20 times lower than that reported in dairy cattle. The very low extent of mammary excretion and the milk levels reported lower than the MRL (20ngml(-1)) supports the permitted use of eprinomectin in lactating water buffaloes. PMID:18774650

Dupuy, Jacques; Sutra, Jean-François; Alvinerie, Michel; Rinaldi, Laura; Veneziano, Vincenzo; Mezzino, Laura; Pennacchio, Saverio; Cringoli, Giuseppe

2008-11-01

369

A kinetic simulation of low-frequency electromagnetic phenomena in inhomogeneous plasmas of three-dimensions  

NASA Astrophysics Data System (ADS)

An advanced implicit particle simulation method was developed and implemented in the HIDENEK code to study large space-scale, low-frequency electromagnetic phenomena occurring in inhomogeneous plasmas. The present method is specially designed for high magnetic field (omega(sub ce) is greater than or equal to omega(sub pe)), inhomogeneous plasma simulations. The guiding-center approximation with magnetic drifts is adopted to the perpendicular motion of the electrons whereas the inertia effect is retained in their parallel motion. Also, a slightly backward time-decentered scheme is introduced to the equations of motion and the Maxwell equations. These equations are combined to yield the full-implicit, coupled field-particle equations which allow us to determine the future electromagnetic field in a large time step compared to the electron time scales with the diamagnetic drift and magnetization currents being included. Three physics applications are shown as a demonstration in terms of the electromagnetic beam-plasma instability, the temperature anisotropy-driven Alfven-ion-cyclotron instability, and the external kink instability of the peaked-density current beam. A remarkable pitch-angle scattering of the ions is observed in the first two applications in association with the plasma instabilities. In the third application to an inhomogeneous, finite-beta plasma of the three-dimensions, a helical deformation is shown to take place to the initially straight beam and magnetic axis in an ideal magnetohydrodynamic time scale.

Tanaka, Motohiko

1992-11-01

370

A kinetic equation for linear stable fractional motion with applications to space plasma physics  

SciTech Connect

Levy flights and fractional Brownian motion have become exemplars of the heavy-tailed jumps and long-ranged memory widely seen in physics. Natural time series frequently combine both effects, and linear fractional stable motion (lfsm) is a model process of this type, combining {alpha}-stable jumps with a memory kernel. In contrast complex physical spatiotemporal diffusion processes where both the above effects compete have for many years been modeled using the fully fractional kinetic equation for the continuous-time random walk (CTRW), with power laws in the probability density functions of both jump size and waiting time. We derive the analogous kinetic equation for lfsm and show that it has a diffusion coefficient with a power law in time rather than having a fractional time derivative like the CTRW. We discuss some preliminary results on the scaling of burst 'sizes' and 'durations' in lfsm time series, with applications to modeling existing observations in space physics and elsewhere.

Watkins, Nicholas W [British Antarctic Survey, Cambridge, UK; Credgington, Daniel [British Antarctic Survey, Cambridge, UK; Sanchez, Raul [ORNL; Rosenberg, SJ [British Antarctic Survey, Cambridge, UK; Chapman, Sandra C [University of Warwick, UK

2009-01-01

371

Studies on the formation of large amplitude kinetic Alfvén wave solitons and double layers in plasmas  

NASA Astrophysics Data System (ADS)

A two fluid model has been employed to study the oblique propagation of solitary kinetic Alfvén waves. Formation of solitary waves and double layers is observed. Amplitude, width (in the case of solitons), and thickness (in the case of double layers) of the nonlinear structures are studied in some detail. Wider solitary structures are found to exist for oblique propagation nearer to the magnetic field direction.

Devi, N.; Gogoi, R.; Das, G. C.; Roychoudhury, R.

2007-01-01

372

A steady-state kinetic model of butyrylcholinesterase from horse plasma  

PubMed Central

The steady-state kinetics of the butyrylcholinesterase-catalysed hydrolysis of butyrylthiocholine and thiophenyl acetate were shown to deviate from Michaelis–Menten kinetics. The `best' empirical rate law was selected by fitting different rate equations to the experimental data by non-linear regression methods. The results were analysed in view of two alternative interpretations: (1) the reaction is catalysed by a mixture of enzymes, or (2) the activity is due to a single enzyme displaying deviations from Michaelis–Menten kinetics. It was concluded that the second alternative applies, and this conclusion was further supported by experiments involving simultaneous hydrolysis of alternative thiol ester substrates (butyrylthiocholine/thiophenyl acetate) as well as alternative thiol ester and oxygen ester substrates (butyrylthiocholine/phenyl acetate; thiophenyl acetate/butyrylcholine; acetylthiocholine/phenyl acetate). On the basis of the conclusion that a single enzyme is responsible for the activity, a molecular model is proposed. This model involves an acylated enzyme, and implies binding to the enzyme of one acyl group and one ester molecule, but not two ester molecules at the same time. Thus butyrylcholinesterase, which is structurally a tetramer, behaves functionally as a co-operative dimer, an interpretation in accordance with available data from active-site titrations.

Augustinsson, Klas-Bertil; Bartfai, Tamas; Mannervik, Bengt

1974-01-01

373

Comparison of a global model to semi-kinetic fluid simulations for atmospheric pressure radio-frequency plasmas  

NASA Astrophysics Data System (ADS)

A global model of a homogeneous plasma bulk oscillating between electron-free radio-frequency (rf) sheaths is developed. Particle and power balance, including ohmic heating loss for bulk-electrons and ions in the sheaths, yield the bulk electron temperature and density. Explicit time dependence of the reduced bulk electric field and correspondingly of the total ionization rate and electron transport coefficients is accounted for. Results for a gas mixture of 0.5 vol% oxygen in helium at atmospheric pressure within a 1 mm discharge gap as a function of the 13.56 MHz rf power density are presented and compared with a semi-kinetic 1D-fluid simulation. The quality of agreement is critically analyzed and correlated with the individual global model assumptions.

Niemi, K.; Gans, T.; O'Connell, D.

2013-06-01

374

Kinetic energy measurement of hydrogen in LHD peripheral plasma with a multi-wavelength-range fine-resolution spectrometer  

NASA Astrophysics Data System (ADS)

We have simultaneously measured high resolution emission spectra of the hydrogen atomic Balmer-?, -?, -? lines and molecular Fulcher-? band for a LHD peripheral plasma generated under a central magnetic field strength of 0.4 T. It is found that the velocity distributions of excited atoms calculated from the Balmer-?, -?, and -? line shapes show similar profiles to each other. The translational kinetic energy corresponding to the average velocity is about 13 eV, which is about 300 times larger than the rotational energy of hydrogen molecules estimated from the line intensities in the Fulcher-? band. The velocity distributions differ from Maxwellian and have a high velocity tail over 1×10 5 m/s. A correlation between the high velocity tail and the electron temperature and density is seen and suggesting the excited atoms having such high velocities to be generated by the charge exchange collisions from high velocity protons in the peripheral region.

Fujii, Keisuke; Mizushiri, Keisuke; Nishioka, Tomomi; Shikama, Taiichi; Iwamae, Atsushi; Goto, Motoshi; Morita, Shigeru; Hasuo, Masahiro

2010-11-01

375

Comparison of initial value and eigenvalue codes for kinetic toroidal plasma instabilities  

Microsoft Academic Search

In plasma physics, linear instability calculations can be implemented either as initial value calculations or as eigenvalue calculations. Here, comparisons between comprehensive linear gyrokinetic calculations employing the ballooning formalism for high-n (toroidal mode number) toroidal instabilities are described. One code implements an initial value calculation on a grid using a Lorentz collision operator and the other implements an eigenvalue calculation

Mike Kotschenreuther; G. Rewoldt; W. M. Tang

1995-01-01

376

Kinetic theory of ion acoustic waves in a plasma with collisional electrons  

NASA Astrophysics Data System (ADS)

An analytical theory of ion acoustic waves in Maxwellian plasmas and in plasmas with an externally applied temperature gradient has been developed. The emphasis is upon the effects of electron-electron and electron-ion collisions on ion acoustic wave damping and on the effective electron heat conductivity associated with the waves. The asymptotic limits of weakly and strongly collisional electrons are studied analytically and then a numerical solution is compared to Fokker-Planck simulations and fitted by simple algebraic expressions. The limit of large Z has also been investigated and the condition of validity for the Lorentzian plasma approximation has been found. It is also shown that the heat flux driven ion acoustic instability exists over a wide range of parameters with a smooth transition from the collisionless to the collisional limit. Accounting for ion-ion collisions leads to the separation of the instability region in two domains. The long wavelength part dominates in plasmas with a relatively high ion temperature. (c) 1995 The American Physical Society

Bychenkov, V. Yu.; Myatt, J.; Rozmus, W.; Tikhonchuk, V. T.

1995-12-01

377

MULTICOMPARTMENT KINETIC MODEL FOR LEAD. PART 3. LEAD IN BLOOD PLASMA AND ERYTHROCYTES  

EPA Science Inventory

Multicompartment models have been fitted to experimental data on plasma lead and blood lead concentrations of subjects studied by de Silva (1981, Brit. J. Industr. Med. 38, 209-217) and one subject studied by Manton and Malloy (1983, Brit. J. Industr. Med., 40, 51-57). Nonlinear ...

378

Products and bioenergy from the pyrolysis of rice straw via radio frequency plasma and its kinetics  

Microsoft Academic Search

The radio frequency plasma pyrolysis technology, which can overcome the disadvantages of common pyrolysis methods such as less gas products while significant tar formation, was used for pyrolyzing the biomass waste of rice straw. The experiments were performed at various plateau temperatures of 740, 813, 843 and 880K with corresponding loading powers of 357, 482, 574 and 664W, respectively. The

Wen-Kai Tu; Je-Lung Shie; Ching-Yuan Chang; Chiung-Fen Chang; Cheng-Fang Lin; Sen-Yeu Yang; Jing T. Kuo; Dai-Gee Shaw; Yii-Der You; Duu-Jong Lee

2009-01-01

379

Kinetic Theory of Neutrals in a Bounded Plasma Slab with Inhomogeneous Temperature and Density Profile.  

National Technical Information Service (NTIS)

The transport of a neutral hydrogen atom in a hydrogen plasma slab is considered. The influence of the inhomogeneous ion temperature profile on the neutral density and distribution is discussed as well as the influence of the neutral edge energy, charge-e...

M. Tendler O. Aagren

1981-01-01

380

Roughness Formation During Plasma Etching of Composite Materials: A Kinetic Monte Carlo Approach  

Microsoft Academic Search

The focus of this article is on the plasma-etching behavior of films of composite materials consisting of two randomly distributed phases with different etch rates. Two etching modes are examined as follows: 1) with anisotropic flux of ions (sputtering) and 2) with isotropic flux of etchants (chemical etching). First, analytical relations are derived to describe etch rate and surface coverage

Eleni Zakka; Vassilios Constantoudis; Evangelos Gogolides

2007-01-01

381

On Hamiltonian and Action Principle Formulations of Plasma Dynamics  

Microsoft Academic Search

A general discussion of Hamiltonian and action principle formulations for fluid and plasma models is given. A procedure, based on Hamilton's principle of mechanics but adapted for continua, for the construction of action principles for fluid and kinetic models is given. The transformation from action principles in terms of the Lagrangian variable description to the Eulerian variable description in terms

P. J. Morrison

2009-01-01

382

The toroidal momentum diffusivity in a tokamak plasma: A comparison of fluid and kinetic calculations  

SciTech Connect

Fluid and gyrokinetic calculations of the toroidal momentum diffusivity in a tokamak are compared. The four-moment gyrofluid model predicts the Prandtl number connected with the ion temperature gradient mode reasonably well provided the drift term is kept in the momentum balance. Without the drift term in the momentum balance, some previous gyrofluid models predicted small values of the Prandtl number in the range of experimental observations. It is shown that the drift term enters in the fluid equations through the gyroviscosity. Gyrokinetic calculations of the ion temperature gradient mode with kinetic electrons, and for experimentally relevant parameters yield a Prandtl number in the range 0.7-1.2.

Strintzi, D. [Department of Electrical and Computer Engineering, National Technical University of Athens, GR-157 73 Athens (Greece); Peeters, A. G. [Center for Fusion, Space and Astrophysics, Physics Department, University of Warwick, CV4 7AL, Coventry (United Kingdom); Weiland, J. [Chalmers University of Technology, S-412 96 Goetenborg (Sweden)

2008-04-15

383

A modified pseudo-equilibrium model competing with kinetic models to determine the composition of a two-temperature SF6 atmosphere plasma  

NASA Astrophysics Data System (ADS)

This paper is devoted to calculation of the non-equilibrium composition in a SF6 thermal plasma at atmospheric pressure. Non-equilibrium thermal plasmas are characterized by heavy species temperatures Th below 9000 K with electron temperatures at the maximum three times higher than Th when the latter is below 4000 K. Different theories have been used based on either multi-temperature plasmas, Saha-Potapov modified by André et al, van de Sanden et al, Cliteur et al, or kinetic calculations or the pseudo-equilibrium model, recently developed. This model gives results similar to those of kinetic calculations for N2 and H2 plasmas but with calculation times two orders magnitude faster. Pseudo-equilibrium calculation takes into account the reactions with low activation energies instead of ionization reactions, while keeping all the species present in the kinetic calculation. First, the theories are compared in a case already studied in the literature by Cliteur: a heavy species temperature Th at 6000 K, with the electron temperature Te varying between 6000 and 15 000 K. Comparison of the results shows that the multi-temperature calculations, except those of Cliteur, are far from kinetic especially for ne and nF-. In addition, the pseudo-equilibrium model fits rather well with the kinetic calculations as long as molecular species are present in the plasma. Second, to calculate the composition of non-equilibrium thermal plasmas the ratio Te/Th is assumed to vary as the logarithm of the electron densities ratio ne/ncmax, nemax being the electron density over which equilibrium prevails, i.e. 1023 m-3. For kinetic reactions where electrons are involved (in the direct reaction while heavy species intervene in the reverse reaction), a temperature T* between Te and Th is defined. T* is calculated as a function of the electron flux to that of heavy species. The variation of T* with Th is smoother than that of Te. In such conditions again, there is an excellent agreement between kinetic and pseudo-equilibrium calculations performed at T*, which is not the case for multi-temperature calculations. These results demonstrate that the pseudo-equilibrium calculation developed for thermal plasma simple forming gases such as N2 and H2 can also be applied to more complex gases such as SF6.

Rat, V.; André, P.; Aubreton, J.; Elchinger, M. F.; Fauchais, P.; Lefort, A.

2001-07-01

384

Hybrid-Kinetic Modelling of Space Plasma with Application to Mercury  

NASA Astrophysics Data System (ADS)

A planet's magnetosphere is often very dynamic, undergoing large topological changes in response to high speed (˜400km/s) solar wind intervals, coronal mass ejections, and naturally excited plasma wave modes. Plasma waves are very effective at transporting energy throughout the magnetosphere, and are therefore of interest in the context of the coupling between solar wind and magnetosphere. Of relevance to this thesis is Kelvin-Helmholtz macro-instability. Kelvin-Helmholtz instability (KHI) is excited by shear of the flows. KHI is commonly observed at equatorial regions of the magnetopause where fast flowing magnetosheath plasma may interact with slow bulk velocities of magnetospheric plasma. The instability is responsible for exciting shear Alfven waves which (at Earth) may be detected using the ground based magnetometers located at latitude of excited field lines. This thesis uses numerical modelling to understand and to explain the generation and propagation of the KHI in Mercury's magnetosphere. The instability is initiated close to the planet and convectively grows while being transported along the tail. When the wave amplitude reaches a nonlinear stage, the structure of the wave becomes complex due to the wrapping of the plasma into the vortex. A vortex structure is typical for KHI and it is used for identifying the wave in the data from satellites. The instability commonly occurs at the dawn or dusk flank magnetopause (MP) of Earth with approximately the same probability. But the data from NASA's MESSENGER spacecraft, currently in the orbit of the planet Mercury, suggest a strong asymmetry in the observations of KHI. It is shown that the KHI initiated near the subsolar point evolves into large-scale vortices propagating anti-sunward along the dusk-side MP. The simulations are in agreement with the third flyby of the MESSENGER spacecraft, where saw-tooth oscillations in the plasma density, flow, and magnetic field were observed. The observed asymmetry in the KHI between dawn and dusk is found to be controlled by the finite gyro-radius of ions, and by MP pressure gradients and the large-scale solar wind convection electric field.

Paral, Jan

385

Densification kinetics of nanocrystalline zirconia powder using microwave and spark plasma sintering--a comparative study.  

PubMed

Two-stage densification process of nanosized 3 mol% yttria-stabilized zirconia (3Y-SZ) polycrystalline compacts during consolidation via microwave and spark-plasma sintering have been observed. The values of activation energies obtained for microwave and spark-plasma sintering 260-275 kJ x mol(-1) are quite similar to that of conventional sintering of zirconia, suggesting that densification during initial stage is controlled by the grain-boundary diffusion mechanism. The sintering behavior during microwave sintering was significantly affected by preliminary pressing conditions, as the surface diffusion mechanism (230 kJ x mol(-1)) is active in case of cold-isostatic pressing procedure was applied. PMID:22905503

Vasylkiv, Oleg; Demirskyi, Dmytro; Sakka, Yoshio; Ragulya, Andrey; Borodianska, Hanna

2012-06-01

386

Kinetic simulations of beam-excited Langmuir waves related to Cassini/Rhea plasma measurements  

NASA Astrophysics Data System (ADS)

During a close flyby of Saturn's moon Rhea on March 2, 2010, the plasma instruments aboard the Cassini spacecraft detected, aside from whistler-mode and ion-acoustic emissions, bursty Langmuir waves when the spacecraft is magnetically connected to the surface of the moon (Santolik et al., 2010). These waves around the electron plasma frequency are obviously generated by a cold, low-energy electron beam with relatively high density (~10%) accelerated away from Rhea. Because of the low beam speed of about twice the thermal speed of the background plasma, the beam mode is dominantly unstable and this instability extends over a broad wave number range up to kLD~1 (LD: Debye length) covering frequencies below and above the electron plasma frequency. In this respect, the Langmuir instability differs from the conditions of foreshock Langmuir waves at planets where the beam velocity is correlated with the solar wind Mach number and normally much lower beam densities are present. Particle-in-cell simulations of electron beam-excited Langmuir waves for the above conditions have been carried out. The wave number/frequency analysis of the electric field at the quasi-stationary state shows mode coupling between the Langmuir mode and the electron-acoustic mode which results from the formation of a plateau distribution. The transition from maximum instability to the stationary state is characterized by large amplitude modulations. By comparing the simulations with fixed and mobile ions with varying mass ratios, the role of ion acoustic fluctuations is clarified and shown to be enhanced simultaneously with the high-frequency electrostatic waves.

Sauer, K.; Sydora, R. D.; Santolik, O.; Gurnett, D. A.; Basovnik, M.; Kurth, W. S.; Hospodarsky, G. B.; Schippers, P.

2013-12-01

387

Kinetics of inflow of matter from electrodes in a radiating cluster of arc discharge plasma  

Microsoft Academic Search

The spectrum of the radiation of a gas-discharge plasma cluster is linked with the inflow of the material of the electrodes into the interelectrode space. Therefore the characteristics of the emission of matter from the electrodes can have a significant effect on the results of spectral analysis. It is known [1-3] that in a variable-current arc the disintegration of the

I. G. Nekrashevich; V. M. Tkachenko

1969-01-01

388

Kinetic vortex chain solution in the drift-wave plasma regime  

PubMed

A fully nonlinear Bernstein-Greene-Kruskal stationary solution is found in the form of a quasi-three-dimensional chain of electron holes coupled to hydrodynamic vortices. This new coherent structure is enabled by the trapping and depletion of resonant particles, and the cyclotron dissipation of the singular current sheets. It is expected to play an important role in the collisionless magnetic field line reconnection in the drift-wave plasma regime, where it represents a plausible saturated state. PMID:11015843

Jovanovic; Pegoraro

2000-01-01

389

A kinetic study of methane conversion by a dinitrogen microwave plasma  

Microsoft Academic Search

Conversion of CH4 with a N2 microwave plasma (2.45 GHz) is studied. The experiments cover the absorbed microwave power range 300–700 W with 17–62% of methane in the gas mixture, with pressures of 10–40 mbar and flow rates of 140–650 ml· min-1. The yields of C2 hydrocarbons and dihydrogen are analyzed by gas chromatography. The distance of methane addition downstream

A. Oumghar; J. C. Legrand; A. M. Diamy; N. Turillon; R. I. Ben-Aïm

1994-01-01

390

Two-Dimensional Modeling of the Active Species Flow Generated by an Atmospheric Plasma Jet  

Microsoft Academic Search

A proper description of the flux of active species generated by cold atmospheric-pressure (AP) plasma jets is of crucial importance for plasma applications. To that end, a 2-D fluid model has been constructed to investigate the effect of the coupling between the plasma kinetics and plasma flow. It is shown that pure-argon cold AP RF plasma jets are not only

M. Atanasova; E. A. D. Carbone; DB Mihailova; J. van Dijk; J. J. A. M. van der Mullen; E. Benova; G. Degrez

2011-01-01

391

Hepatic transport kinetics and plasma disappearance curves: distributed modeling versus conventional approach.  

PubMed

The conventional approach to estimating hepatic transfer coefficients from the plasma disappearance curve ignores the effects of blood flow in the splanchnic and peripheral circulations. The effect of these simplifying assumptions on derived estimates of the rate constants has never been studied. To examine this problem we have constructed a distributed model that takes account of intrahepatic concentration profiles, nonuniform blood-flow distribution in the sinusoids, and delayed mixing in the peripheral circulation. Solutions to the new model constructed by numerical inversion of the Laplace transform afford a comparison between the new model and the conventional one. The sensitivity of the conventional equations to experimental error has also been evaluated. The results indicate that conventional estimates of the rate constants for hepatic uptake and cell-to-plasma efflux are subject to a systematic underestimate, the errors increasing rapidly with the initial extraction fraction. Estimates of the uptake constant obtained from the initial slope are especially susceptible to circulatory distortions and proved unacceptable even at low values of the initial extraction fraction. The liver content at 3 min did not in general provide a reliable index to these errors. In contrast to these problems, the conventional model returns generally accurate estimates of the steady-state plasma clearance and the rate constant for excretion. PMID:736124

Forker, E L; Luxon, B

1978-12-01

392

Kinetic model of electric potentials in localized collisionless plasma structures under steady quasi-gyrotropic conditions  

SciTech Connect

Localized plasma structures, such as thin current sheets, generally are associated with localized magnetic and electric fields. In space plasmas localized electric fields not only play an important role for particle dynamics and acceleration but may also have significant consequences on larger scales, e.g., through magnetic reconnection. Also, it has been suggested that localized electric fields generated in the magnetosphere are directly connected with quasi-steady auroral arcs. In this context, we present a two-dimensional model based on Vlasov theory that provides the electric potential for a large class of given magnetic field profiles. The model uses an expansion for small deviation from gyrotropy and besides quasineutrality it assumes that electrons and ions have the same number of particles with their generalized gyrocenter on any given magnetic field line. Specializing to one dimension, a detailed discussion concentrates on the electric potential shapes (such as 'U' or 'S' shapes) associated with magnetic dips, bumps, and steps. Then, it is investigated how the model responds to quasi-steady evolution of the plasma. Finally, the model proves useful in the interpretation of the electric potentials taken from two existing particle simulations.

Schindler, K. [Ruhr University Bochum, 44780 Bochum (Germany); Birn, J. [Space Science Institute, Boulder, Colorado 80301 (United States); Hesse, M. [Nasa Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

2012-08-15

393

Kinetic Model of Electric Potentials in Localized Collisionless Plasma Structures under Steady Quasi-gyrotropic Conditions  

NASA Technical Reports Server (NTRS)

Localized plasma structures, such as thin current sheets, generally are associated with localized magnetic and electric fields. In space plasmas localized electric fields not only play an important role for particle dynamics and acceleration but may also have significant consequences on larger scales, e.g., through magnetic reconnection. Also, it has been suggested that localized electric fields generated in the magnetosphere are directly connected with quasi-steady auroral arcs. In this context, we present a two-dimensional model based on Vlasov theory that provides the electric potential for a large class of given magnetic field profiles. The model uses an expansion for small deviation from gyrotropy and besides quasineutrality it assumes that electrons and ions have the same number of particles with their generalized gyrocenter on any given magnetic field line. Specializing to one dimension, a detailed discussion concentrates on the electric potential shapes (such as "U" or "S" shapes) associated with magnetic dips, bumps, and steps. Then, it is investigated how the model responds to quasi-steady evolution of the plasma. Finally, the model proves useful in the interpretation of the electric potentials taken from two existing particle simulations.

Schindler, K.; Birn, J.; Hesse, M.

2012-01-01

394

Transition form collisional to kinetic reconnection in large-scale plasmas  

SciTech Connect

Using first-principles fully kinetic simulations with a Fokker-Planck collision operator, it is demonstrated that Sweet-Parker reconnection layers are unstable to a chain of plasmoids (secondary islands) for Lundquist numbers beyond S >{approx} 1000. The instability is increasingly violent at higher Lundquist number, both in terms of the number of plasmoids produced and the super-Alfvenic growth rate. A dramatic enhancement in the reconnection rate is observed when the half-thickness of the current sheet between two plasmoids approaches the ion inertial length. During this transition, the reconnection electric field rapidly exceeds the runaway limit, resulting in the formation of electron-scale current layers that are unstable to the continual formation of new plasmoids.

Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim S [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Karimabadi, Homa [UCSD

2009-01-01

395

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES: Numerical Simulation of Solitary Kinetic Alfvén Waves  

NASA Astrophysics Data System (ADS)

Using the two-fluid model in the case of ? ? 1 (? = ?/2Q, ? is the ratio of thermal pressure to magnetic pressure, and Q = me/mi), we numerically investigate the interactions between two solitary kinetic Alfvén waves (SKAWs) and between an SKAW and a density discontinuity. The results show that the two SKAWs would remain in their original shapes and propagate at their initiating speeds, which indicates that SKAWs behave just like standard solitons. The simulation also shows that SKAWs will reflect and refract when crossing a discontinuity and propagating into a higher density region. The transmission wave is an SKAW with increasing density, and the reverberation is a disturbance with lower amplitude.

Ding, Jian; Li, Yi; Wang, Shui

2008-07-01

396

Kinetic and thermodynamic properties of a convecting plasma in a two-dimensional dipole field  

SciTech Connect

Charged particle guiding center motion is considered in the magnetic field of a two-dimensional (`line`) dipole on which is superimposed a small, static, perpendicular electric field. The parallel equation of motion is that of a simple harmonic oscillator for cos{theta}, the cosine of magnetic colatitude. Equations for the perpendicular electric and magnetic drifts are derived as well as their bounce-averaged forms. The latter are solved to yield a bounce-averaged guiding center trajectory, which is the same as that obtained from conservation of magnetic moment {mu}, longitudinal invariant J, and total (kinetic plus electrostatic) energy K. The algebraic simplicity of the trajectory equations is also manifest in the forms of the invariants. An interesting result is that guiding centers drift in such a way that they preserve the values of their equatorial pitch angles and (equivalently) mirror latitudes. The most general Maxwellian form of the equilibrium one-particle distribution function f is constructed from the invariants, and spatially varying density and pressure moments, parallel and perpendicular to the magnetic field, are identified. Much of the paper deals with the more restricted problem in which f is specified as a bi-Maxwellian over a straight line of finite length in the equatorial plane of the dipole and perpendicular to field lines. This might be thought of as specifying a cross-tail ion injection source; the authors formalism then describes the subsequent spatial development. The distribution away from the source is a scaled bi-Maxwellian but one that is cut off at large and small kinetic energies, which depend on position. Density and pressure components are reduced from the values they would have if the total content of individual flux tubes convected intact. The equatorial and meridional variations of density and pressure components are examined and compared systematically for the isotropic and highly anisotropic situations. 22 refs., 10 figs.

Huang, T.S. [Prairie View A& M Univ., TX (United States)] [Prairie View A& M Univ., TX (United States); Birmingham, T.J. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)] [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

1994-09-01

397

Computational Plasma Physics at the Bleeding Edge: Simulating Kinetic Turbulence Dynamics in Fusion Energy Sciences  

NASA Astrophysics Data System (ADS)

Advanced computing is generally recognized to be an increasingly vital tool for accelerating progress in scientific research in the 21st Century. The imperative is to translate the combination of the rapid advances in super-computing power together with the emergence of effective new algorithms and computational methodologies to help enable corresponding increases in the physics fidelity and the performance of the scientific codes used to model complex physical systems. If properly validated against experimental measurements and verified with mathematical tests and computational benchmarks, these codes can provide more reliable predictive capability for the behavior of complex systems, including fusion energy relevant high temperature plasmas. The magnetic fusion energy research community has made excellent progress in developing advanced codes for which computer run-time and problem size scale very well with the number of processors on massively parallel supercomputers. A good example is the effective usage of the full power of modern leadership class computational platforms from the terascale to the petascale and beyond to produce nonlinear particle-in-cell simulations which have accelerated progress in understanding the nature of plasma turbulence in magnetically-confined high temperature plasmas. Illustrative results provide great encouragement for being able to include increasingly realistic dynamics in extreme-scale computing campaigns to enable predictive simulations with unprecedented physics fidelity. Some illustrative examples will be presented of the algorithmic progress from the magnetic fusion energy sciences area in dealing with low memory per core extreme scale computing challenges for the current top 3 supercomputers worldwide. These include advanced CPU systems (such as the IBM-Blue-Gene-Q system and the Fujitsu K Machine) as well as the GPU-CPU hybrid system (Titan).

Tang, William

2013-04-01

398

Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics  

SciTech Connect

The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The ?s temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

Vitelaru, Catalin [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France) [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France); National Institute for Optoelectronics, Magurele-Bucharest, RO 077125 (Romania); Lundin, Daniel [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France) [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France); Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden); Brenning, Nils [Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden)] [Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden); Minea, Tiberiu [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France)] [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France)

2013-09-02

399

Computer simulation of kinetic properties of plasmas. Progress report, July 1, 1980-May 31, 1981  

SciTech Connect

The research is directed toward the development and testing of new numerical methods for particle and hybrid simulation of plasmas, and their application to physical problems of current significance to Magnetic Fusion Energy. During the present period, research on the project has been concerned with the following specific problems: (A) numerical study of non-local trapped-electron modes; (B) particle diffusion due to stochastic orbits in sheared magnetic fields; (C) time-filtering particle simulations with large time steps; (D) non-random initializations of particle codes; and (E) computer studies of field-reversed ion rings.

Denavit, J.

1981-01-01

400

Computer simulation of kinetic properties of plasmas. Progress report, July 1, 1979-June 30, 1980  

SciTech Connect

The research is directed toward the development and testing of new numerical methods for particle and hybrid simulation of plasmas, and their application to physical problems of current significance to Magnetic Fusion Energy. During the present period, research on the project has been concerned with the following specific problems: (1) Consideration of radial dependence and shear stabilization of drift and dissipative trapped-electron instabilities. (2) Long-time-scale algorithms for particle simulation with ..omega../sub pe/..delta..t much greater than 1. (3) Computer studies of field-reversed ion rings.

Denavit, J.

1980-01-01

401

A kinetic-MHD model for studying low frequency multiscale phenomena  

SciTech Connect

A nonlinear kinetic-MHD model for studying low frequency multiscale phenomena has been developed by taking advantage of the single fluid MHD model`s simplicity and by properly accounting for core ion finite Larmor radius (FLR) effects and major kinetic effects of energetic particles. The kinetic-MHD model treats the low energy core plasma by a generalized MHD description and energetic particles kinetically; the coupling between the dynamics of these two components of plasmas is through the plasma pressure. The generalized MHD model for core plasma includes core ion FLR effects which provide a finite parallel electric field, a modified perpendicular velocity from the {bold E} {times} {bold B} drift, and a gyroviscosity tensor, which are neglected in the usual single fluid MHD description. The perturbed core plasma electron and ion densities, velocity and pressure tensor are determined from both the low frequency and high frequency gyro-kinetic equations. From the quasineutrality condition, we obtain the parallel electric field, which arises from the ion gryoradius effects. The kinetic-MHD model is closed by generalized pressure laws for the core and energetic plasmas. When ion gryoradius radius is on the order of the plasma equilibrium scale length, the Vlasov description may be adopted to describe the energetic particle dynamics. From the kinetic-MHD model we derive eigenmode equations for low frequency waves such as shear/kinetic Alfven waves (KAW) and ballooning-mirror modes. The kinetic-MHD model has been successfully applied to study ballooning-mirror instabilities to understand the field-aligned structure and instability threshold of compressional Pc 5 waves in the ring current region. It is also demonstrated that the ion FLR effects in the dispersion relation of KAWs are properly retained; note that these are not properly included in the popularly employed two-fluid equations because the gryoviscosity contribution is usually not retained. 18 refs., 2 figs.

Cheng, C.Z.; Johnson, J.R.

1996-05-01

402