Consistent description of kinetics and hydrodynamics of dusty plasma
Markiv, B.; Tokarchuk, M.; National University “Lviv Polytechnic,” 12 Bandera St., 79013 Lviv
2014-02-15
A consistent statistical description of kinetics and hydrodynamics of dusty plasma is proposed based on the Zubarev nonequilibrium statistical operator method. For the case of partial dynamics, the nonequilibrium statistical operator and the generalized transport equations for a consistent description of kinetics of dust particles and hydrodynamics of electrons, ions, and neutral atoms are obtained. In the approximation of weakly nonequilibrium process, a spectrum of collective excitations of dusty plasma is investigated in the hydrodynamic limit.
Tensor magnetohydrodynamics: Quasi-kinetic description of rarefied plasma
Laptukhov, A. I.
2009-05-15
A power-series method for solving the kinetic equation is proposed. A simple procedure for deriving equations for arbitrary moments of the distribution function is described. An analysis of wave propagation in a stationary uniform hot magnetoactive plasma shows that allowance for tensors of ranks up to n and omission of higher rank tensors in the equations of tensor magnetohydrodynamics corresponds to taking into account waves at cyclotron harmonics with numbers up to n inclusive and ignoring higher harmonics. Thus, from the standpoint of accuracy and complexity of plasma description, tensor magnetohydrodynamics occupies an intermediate position between the kinetic approach and the conventional magnetohydrodynamics with a scalar pressure.
Kinetic description of electron plasma waves with orbital angular momentum
Mendonca, J. T.
2012-11-15
We describe the kinetic theory of electron plasma waves with orbital angular momentum or twisted plasmons. The conditions for a twisted Landau resonance to exist are established, and this concept is introduced for the first time. Expressions for the kinetic dispersion relation and for the electron Landau damping are derived. The particular case of a Maxwellian plasma is examined in detail. The new contributions to wave dispersion and damping due the orbital angular momentum are discussed. It is shown that twisted plasmons can be excited by rotating electron beams.
Cremaschini, Claudio; Tessarotto, Massimo
2011-11-15
A largely unsolved theoretical issue in controlled fusion research is the consistent kinetic treatment of slowly-time varying plasma states occurring in collisionless and magnetized axisymmetric plasmas. The phenomenology may include finite pressure anisotropies as well as strong toroidal and poloidal differential rotation, characteristic of Tokamak plasmas. Despite the fact that physical phenomena occurring in fusion plasmas depend fundamentally on the microscopic particle phase-space dynamics, their consistent kinetic treatment remains still essentially unchallenged to date. The goal of this paper is to address the problem within the framework of Vlasov-Maxwell description. The gyrokinetic treatment of charged particles dynamics is adopted for the construction of asymptotic solutions for the quasi-stationary species kinetic distribution functions. These are expressed in terms of the particle exact and adiabatic invariants. The theory relies on a perturbative approach, which permits to construct asymptotic analytical solutions of the Vlasov-Maxwell system. In this way, both diamagnetic and energy corrections are included consistently into the theory. In particular, by imposing suitable kinetic constraints, the existence of generalized bi-Maxwellian asymptotic kinetic equilibria is pointed out. The theory applies for toroidal rotation velocity of the order of the ion thermal speed. These solutions satisfy identically also the constraints imposed by the Maxwell equations, i.e., quasi-neutrality and Ampere's law. As a result, it is shown that, in the presence of nonuniform fluid and EM fields, these kinetic equilibria can sustain simultaneously toroidal differential rotation, quasi-stationary finite poloidal flows and temperature anisotropy.
Cremaschini, Claudio; Miller, John C.; Tessarotto, Massimo
2011-06-15
A kinetic treatment is developed for collisionless magnetized plasmas occurring in high-temperature, low-density astrophysical accretion disks, such as are thought to be present in some radiatively inefficient accretion flows onto black holes. Quasi-stationary configurations are investigated, within the framework of a Vlasov-Maxwell description. The plasma is taken to be axisymmetric and subject to the action of slowly time-varying gravitational and electromagnetic fields. The magnetic field is assumed to be characterized by a family of locally nested but open magnetic surfaces. The slow collisionless dynamics of these plasmas is investigated, yielding a reduced gyrokinetic Vlasov equation for the kinetic distribution function. For doing this, an asymptotic quasi-stationary solution is first determined, represented by a generalized bi-Maxwellian distribution expressed in terms of the relevant adiabatic invariants. The existence of the solution is shown to depend on having suitable kinetic constraints and conditions leading to particle trapping phenomena. With this solution, one can treat temperature anisotropy, toroidal and poloidal flow velocities, and finite Larmor-radius effects. An asymptotic expansion for the distribution function permits analytic evaluation of all the relevant fluid fields. Basic theoretical features of the solution and their astrophysical implications are discussed. As an application, the possibility of describing the dynamics of slowly time-varying accretion flows and the self-generation of magnetic field by means of a ''kinetic dynamo effect'' are discussed. Both effects are shown to be related to intrinsically kinetic physical mechanisms.
On description of quantum plasma
S. V. Vladimirov; Yu. O. Tyshetskiy
2011-01-21
A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)
NASA Astrophysics Data System (ADS)
Bénisti, Didier
2015-07-01
This paper addresses the linear propagation of an electron wave in a plasma whose distribution function, at zero order in the wave amplitude, may be chosen arbitrarily, provided that it is not strongly peaked at the wave phase velocity, and that it varies very little over one wave period and one wavelength. Then, from first principles is derived an equation for the wave action density that allows for Landau damping, whose rate is calculated at first order in the variations of the wave number and frequency. Moreover, the effect of collisions is accounted for in a way that adapts to any choice for the collision operator in Boltzmann equation. The wave may also be externally driven, so that the results presented here apply to stimulated Raman scattering.
Ramos, J. J.
2010-08-15
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.
2011-10-15
The ion side of a closed, fluid and drift-kinetic theoretical model to describe slow and macroscopic plasma processes in a fusion-relevant, low collisionality regime is presented. It follows the ordering assumptions and the methodology adopted in the companion electron theory [Ramos, Phys. Plasmas 17, 082502 (2010)]. To reach the frequency scale where collisions begin to play a role, the drift-kinetic equation for the ion distribution function perturbation away from a Maxwellian must be accurate to the second order in the Larmor radius. The macroscopic density, flow velocity and temperature are accounted for in the Maxwellian, and are evolved by a fluid system which includes consistently the gyroviscous part of the stress tensor and second-order contributions to the collisionless perpendicular heat flux involving non-Maxwellian fluid moments. The precise compatibility among these coupled high-order fluid and drift-kinetic equations is made manifest by showing that the evolution of the non-Maxwellian part of the distribution function is such that its first three velocity moments remain equal to zero.
NASA Astrophysics Data System (ADS)
Gubchenko, V. M.
2015-12-01
In part I of the work, the physical effects responsible for the formation of low-speed flows in plasma coronas, coupled with formation of coronas magnetosphere-like structures, are described qualitatively. Coronal domain structures form if we neglect scales of spatial plasma dispersion: high-speed flows are accumulated in magnetic tubes of the open domains, while magnetic structures and low-speed flows are concentrated within boundaries of domains. The inductive electromagnetic process occurring in flows of the hot collisionless plasma is shown to underlie the formation of magnetosphere-like structures. Depending on the form of the velocity distribution function of particles (PDF), a hot flow differently reveals its electromagnetic properties, which are expressed by the induction of resistive and diamagnetic scales of spatial dispersion. These determine the magnetic structure scales and structure reconstruction. The inductive electromagnetic process located in lines of the plasma nontransparency and absorption, in which the structures of excited fields are spatially aperiodic and skinned to the magnetic field sources. The toroidal and dipole magnetic sources of different configurations are considered for describing the corona structures during the solar maximum and solar minimum.
Lagrangian description of warm plasmas
NASA Technical Reports Server (NTRS)
Kim, H.
1970-01-01
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.
Kinetic theory of relativistic plasmas
NASA Technical Reports Server (NTRS)
Gould, R. J.
1981-01-01
The thermalization of particle kinetic motion by binary collisions is considered for a plasma with a Boltzmann constant-temperature product approximately equal to 10 to 100 times the product of the electron mass with the square of the speed of light. At this temperature, the principal mechanism for relaxation of electron motion is via radiationless electron-electron collisions (Moller scattering). Ions are nonrelativistic, but are energetic enough so that their Coulomb scattering can be treated in the Born approximation. Relaxation times are computed and Boltzmann-equation Fokker-Planck operators are derived for the various binary-collision processes. The expression for the rate of kinetic energy exchange between electron and ion gases is derived for the case where the gases are at different temperatures.
Propagation of radiation in fluctuating multiscale plasmas. I. Kinetic theory
Tyshetskiy, Yu.; Pal Singh, Kunwar; Thirunavukarasu, A.; Robinson, P. A.; Cairns, Iver H.
2012-11-15
A theory for propagation of radiation in a large scale plasma with small scale fluctuations is developed using a kinetic description in terms of the probability distribution function of the radiation in space, time, and wavevector space. Large scale effects associated with spatial variations in the plasma density and refractive index of the plasma wave modes and small scale effects such as scattering of radiation by density clumps in fluctuating plasma, spontaneous emission, damping, and mode conversion are included in a multiscale kinetic description of the radiation. Expressions for the Stokes parameters in terms of the probability distribution function of the radiation are used to enable radiation properties such as intensity and polarization to be calculated.
Kinetic equation for spin-polarized plasmas
Cowley, S.C.; Kulsrud, R.M.; Valeo, E.
1984-07-01
The usual kinetic description of a plasma is extended to include variables to describe the spin. The distribution function, over phase-space and the new spin variables, provides a sufficient description of a spin-polarized plasma. The evolution equation for the distribution function is given. The equations derived are used to calculate depolarization due to four processes, inhomogeneous fields, collisions, collisions in inhomogeneous fields, and waves. It is found that depolarization by field inhomogeneity on scales large compared with the gyroradius is totally negligible. The same is true for collisional depolarization. Collisions in inhomogeneous fields yield a depolarization rate of order 10/sup -4/S/sup -1/ for deuterons and a negligible rate for tritons in a typical fusion reactor design. This is still sufficiently small on reactor time scales. However, small amplitude magnetic fluctuations (of order one gauss) resonant with the spin precession frequency can lead to significant depolarization (depolarises triton in ten seconds and deuteron in a hundred seconds.)
Application of Nonlocalpp Electron Kinetics to Plasma
Kaganovich, Igor
, and C.E. Theodosiou, IEEE Trans ANODE CATHODE Plasma Sci. 33, 510 (2005). 7 #12;Explosive generationApplication of Nonlocalpp Electron Kinetics to Plasma TechnologiesTechnologies Igor D. Kaganovich1 Schweigert4, and Alexander S. Mustafaev5 1Princeton Plasma Physics Laboratory, NJ, USA 2 University
A kinetic description of particle fragmentation Pierre-Emmanuel Jabin
Jabin, Pierre-Emmanuel
A kinetic description of particle fragmentation Pierre-Emmanuel Jabin & Juan Soler June 2, 2006 by a mathematical approach of the kinetic theory. We consider a fairly general model which may require a description be analyzed with the use of correct entropies. Key words: Fragmentation kernels, kinetic equations, Boltzmann
The Gaussian radial basis function method for plasma kinetic theory
NASA Astrophysics Data System (ADS)
Hirvijoki, E.; Candy, J.; Belli, E.; Embréus, O.
2015-10-01
Description of a magnetized plasma involves the Vlasov equation supplemented with the non-linear Fokker-Planck collision operator. For non-Maxwellian distributions, the collision operator, however, is difficult to compute. In this Letter, we introduce Gaussian Radial Basis Functions (RBFs) to discretize the velocity space of the entire kinetic system, and give the corresponding analytical expressions for the Vlasov and collision operator. Outlining the general theory, we also highlight the connection to plasma fluid theories, and give 2D and 3D numerical solutions of the non-linear Fokker-Planck equation. Applications are anticipated in both astrophysical and laboratory plasmas.
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.
Complete Spectrum of Kinetic Eigenmodes for Plasma
Ng, Chung-Sang
Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations in a Weakly Collisional Plasma C. S damping rate measured with a discrete spectrum. Ng, Bhattacharjee, & Skiff (1999): discrete collisional spectrum found numerically which tends to Landau spectrum as collision tends to zero. Short & Simon (2002
Wave kinetics of relativistic quantum plasmas
Mendonca, J. T.
2011-06-15
A quantum kinetic equation, valid for relativistic unmagnetized plasmas, is derived here. This equation describes the evolution of a quantum quasi-distribution, which is the Wigner function for relativistic spinless charged particles in a plasma, and it is exactly equivalent to a Klein-Gordon equation. Our quantum kinetic equation reduces to the Vlasov equation in the classical limit, where the Wigner function is replaced by a classical distribution function. An approximate form of the quantum kinetic equation is also derived, which includes first order quantum corrections. This is applied to electron plasma waves, for which a new dispersion relation is obtained. It is shown that quantum recoil effects contribute to the electron Landau damping with a third order derivative term. The case of high frequency electromagnetic waves is also considered. Its dispersion relation is shown to be insensitive to quantum recoil effects for equilibrium plasma distributions.
A fluid description of plasma double-layers
NASA Technical Reports Server (NTRS)
Levine, J. S.; Crawford, F. W.
1979-01-01
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.
Growth kinetics of plasma-polymerized films
Hwang, Sukyoung; Seo, Hosung; Jeong, Dong-Cheol; Wen, Long; Han, Jeon Geon; Song, Changsik; Kim, Yunseok
2015-01-01
The growth kinetics of polymer thin films prepared by plasma-based deposition method were explored using atomic force microscopy. The growth behavior of the first layer of the polythiophene somewhat differs from that of the other layers because the first layer is directly deposited on the substrate, whereas the other layers are deposited on the polymer itself. After the deposition of the first layer, each layer is formed with a cycle of 15?s. The present work represents the growth kinetics of the plasma-polymerized films and could be helpful for further studies on growth kinetics in other material systems as well as for applications of plasma-polymerized thin films. PMID:26084630
Neutral Vlasov kinetic theory of magnetized plasmas
Tronci, Cesare; Camporeale, Enrico
2015-02-15
The low-frequency limit of Maxwell equations is considered in the Maxwell-Vlasov system. This limit produces a neutral Vlasov system that captures essential features of plasma dynamics, while neglecting radiation effects. Euler-Poincaré reduction theory is used to show that the neutral Vlasov kinetic theory possesses a variational formulation in both Lagrangian and Eulerian coordinates. By construction, the new model recovers all collisionless neutral models employed in plasma simulations. Then, comparisons between the neutral Vlasov system and hybrid kinetic-fluid models are presented in the linear regime.
Inertial range turbulence in kinetic plasmas
G. G. Howes
2007-11-27
The transfer of turbulent energy through an inertial range from the driving scale to dissipative scales in a kinetic plasma followed by the conversion of this energy into heat is a fundamental plasma physics process. A theoretical foundation for the study of this process is constructed, but the details of the kinetic cascade are not well understood. Several important properties are identified: (a) the conservation of a generalized energy by the cascade; (b) the need for collisions to increase entropy and realize irreversible plasma heating; and (c) the key role played by the entropy cascade--a dual cascade of energy to small scales in both physical and velocity space--to convert ultimately the turbulent energy into heat. A strategy for nonlinear numerical simulations of kinetic turbulence is outlined. Initial numerical results are consistent with the operation of the entropy cascade. Inertial range turbulence arises in a broad range of space and astrophysical plasmas and may play an important role in the thermalization of fusion energy in burning plasmas.
Kinetic Theory of Plasma Waves - Part III: Inhomogeneous Plasma
Lamalle, P.U
2004-03-15
Given the extent of the subject, the present text merely provides a list of topics, striking features and references relevant to the kinetic theory of high-frequency wave propagation and absorption in inhomogeneous plasmas. The discussion focuses on tokamak geometry.
Linking plasma kinetics to plasma-bio interactions
NASA Astrophysics Data System (ADS)
Bruggeman, Peter
2015-05-01
Cold non-equilibrium atmospheric pressure plasmas have received a lot of attention in the last decade due to their huge potential for biomedical applications. In my group, we have characterized an RF driven APPJ in great detail. The characterization includes electrical measurements, imaging, optical emission spectroscopy, (two photon enhanced) laser induced fluorescence, Thomson scattering, Rayleigh scattering, Raman scattering and mass spectrometry. This led to a detailed knowledge of the electron density, electron temperature, gas temperature, NO, O, OH, O3 densities, ionic species and air concentrations in the plasma effluent. Living organisms for in vitro studies are typically kept in complex solutions or culture media. Plasma-bio interactions involves not only the production of reactive species in the plasma gas phase but also transport to the liquid phase and plasma induced liquid phase chemistry and its impact on the living organisms. Reactive nitrogen and oxygen species have been identified as the key reactive species. Recent results of my group show that controlling the gas phase plasma chemistry can lead to significant different biological responses of the living organisms corresponding to different chemical pathways. The effect of plasma jet interaction with liquids containing mammalian cells, bacteria and virus will be discussed. The outcomes of these studies allow unraveling chemical pathways responsible for plasma-bio interactions and linking plasma kinetics to plasma-bio interactions.
Kinetic effects in Enceladus plasma environment
NASA Astrophysics Data System (ADS)
Stverak, Stepan; Travnicek, Pavel M.; Sebek, Ondrej; Hellinger, Petr; Khurana, Krishan
2015-04-01
The southern plume of Enceladus represents a significant source of neutrals, ions and dust for the neighboring plasma environment and even for the inner magnetosphere of Saturn. The ion mass loading rate from the plume is not only confirmed by direct plasma measurements but can also be deduced from the strong signatures observed on the Kronian magnetospheric background magnetic field. In view of recent knowledge, namely based on in situ observations provided by numerous Cassini flybys, we try to model numerically and reconstruct the complex plasma environment in the vicinity of the moon by use of a full 3-dimensional hybrid code. With obtained results we attempt to investigate the role of kinetic effects in generation of the ion-cyclotron waves instantaneously observed by the Cassini spacecraft.
Kinetic description of quantum Brownian motion
Bassano Vacchini; Francesco Petruccione
2008-09-03
We stress the relevance of the two features of translational invariance and atomic nature of the gas in the quantum description of the motion of a massive test particle in a gas, corresponding to the original picture of Einstein used in the characterization of Brownian motion. The master equation describing the reduced dynamics of the test particle is of Lindblad form and complies with the requirement of covariance under translations.
Kinetic theory of electrical conductivity in plasmas
Boercker, D.B.
1981-04-01
A recently developed quantum kinetic theory for time-correlation functions is applied to the calculation of the electrical conductivity in dense, strongly coupled plasmas. In the weak-collision limit the theory generalizes the Ziman expression to finite temperatures while, for strong collisions, it generalizes the result of Gould and of Williams and DeWitt to include strong ion coupling. Numerical results which compare the effects that strong ion coupling, bound (core) electrons, and strong collisions have upon the collision frequency are also presented.
Kinetics of wet sodium vapor complex plasma
Mishra, S. K.; Sodha, M. S.
2014-04-15
In this paper, we have investigated the kinetics of wet (partially condensed) Sodium vapor, which comprises of electrons, ions, neutral atoms, and Sodium droplets (i) in thermal equilibrium and (ii) when irradiated by light. The formulation includes the balance of charge over the droplets, number balance of the plasma constituents, and energy balance of the electrons. In order to evaluate the droplet charge, a phenomenon for de-charging of the droplets, viz., evaporation of positive Sodium ions from the surface has been considered in addition to electron emission and electron/ion accretion. The analysis has been utilized to evaluate the steady state parameters of such complex plasmas (i) in thermal equilibrium and (ii) when irradiated; the results have been graphically illustrated. As a significant outcome irradiated, Sodium droplets are seen to acquire large positive potential, with consequent enhancement in the electron density.
Kinetic theory of partially ionized complex (dusty) plasmas
Tsytovich, V.N.; De Angelis, U.; Ivlev, A.V.; Morfill, G.E.
2005-08-15
The general approach to the kinetic theory of complex (dusty) plasmas [Tsytovich and de Angelis, Phys. Plasmas 6, 1093 (1999)], which was formulated with the assumption of a regular (nonfluctuating) source of plasma particles, is reformulated to include ionization by electron impact on neutrals as the plasma source and the effects of collisions of ions and dust particles with neutrals.
Generalized Langmuir Waves in Magnetized Kinetic Plasmas
NASA Technical Reports Server (NTRS)
Willes, A. J.; Cairns, Iver H.
2000-01-01
The properties of unmagnetized Langmuir waves and cold plasma magnetoionic waves (x, o, z and whistler) are well known. However, the connections between these modes in a magnetized kinetic plasma have not been explored in detail. Here, wave properties are investigated by numerically solving the dispersion equation derived from the Vlasov equations both with and without a beam instability present. For omega(sub p)>Omega(sub e), it is shown that the generalized Langmuir mode at oblique propagation angles has magnetic z-mode characteristics at low wave numbers and thermal Langmuir mode characteristics at high wave numbers. For omega(sub p)
Kinetic Alfv'en Eigenmodes in a Hot Tokamak Plasma
Jaun, AndrÃ©
Kinetic Alfv'en Eigenmodes in a Hot Tokamak Plasma A.JAUN 1 , K.APPERT 2 , A.FASOLI 2;3 , T, Oxon, OX14 3EA, UK ABSTRACT. Kinetic effects such as finite ion Larmor excursions and resonant Landau. It generates a group of kinetic Alfv'en eigenmodes (KAE) in the neighborhood of each fluid eigenmode
Active transport: A kinetic description based on thermodynamic grounds
S. Kjelstrup; J. M. Rubi; D. Bedeaux
2004-12-17
We show that active transport processes in biological systems can be understood through a local equilibrium description formulated at the mesoscale, the scale to describe stochastic processes. This new approach uses the method established by nonequilibrium thermodynamics to account for the irreversible processes occurring at this scale and provides nonlinear kinetic equations for the rates in terms of the driving forces. The results show that the application domain of nonequilibrium thermodynamics method to biological systems goes beyond the linear domain. A model for transport of Ca$^{2+}$ by the Ca$^{2+}$-ATPase, coupled to the hydrolysis of adenosine-triphosphate is analyzed in detail showing that it depends on the reaction Gibbs energy in a non-linear way. Our results unify thermodynamic and kinetic descriptions, thereby opening new perspectives in the study of different transport phenomena in biological systems.
The Gaussian Radial Basis Function Method for Plasma Kinetic Theory
Hirvijoki, Eero; Belli, Emily; Embréus, Ola
2015-01-01
A fundamental macroscopic description of a magnetized plasma is the Vlasov equation supplemented by the nonlinear inverse-square force Fokker-Planck collision operator [Rosenbluth et al., Phys. Rev., 107, 1957]. The Vlasov part describes advection in a six-dimensional phase space whereas the collision operator involves friction and diffusion coefficients that are weighted velocity-space integrals of the particle distribution function. The Fokker-Planck collision operator is an integro-differential, bilinear operator, and numerical discretization of the operator is far from trivial. In this letter, we describe a new approach to discretize the entire kinetic system based on an expansion in Gaussian Radial Basis functions (RBFs). This approach is particularly well-suited to treat the collision operator because the friction and diffusion coefficients can be analytically calculated. Although the RBF method is known to be a powerful scheme for the interpolation of scattered multidimensional data, Gaussian RBFs also...
Surface kinetics and plasma equipment model for Si etching by fluorocarbon plasmas
Kushner, Mark
Surface kinetics and plasma equipment model for Si etching by fluorocarbon plasmas Da Zhanga August 1999; accepted for publication 18 October 1999 Plasma-surface interactions during plasma etching processing is towards the use of low pressure, high plasma density etching reactors in which re- active
Contrib. Plasma Phys. 41 (2001) 2-3, 259-262 Quantum Kinetic Theory of Laser Plasmas
Bonitz, Michael
2001-01-01
Contrib. Plasma Phys. 41 (2001) 2-3, 259-262 Quantum Kinetic Theory of Laser Plasmas D. Krempa perturbation theory. 1 Generalized kinetic equation The classical kinetic theory of plasmas in time dependent.kremp@physik.uni-rostock.de Received 29 September 2000, in final form 8 December 2000 Abstract A quantum kinetic equation for plasmas
Fundamental Statistical Descriptions of Plasma Turbulence in Magnetic Fields
John A. Krommes
2001-02-16
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.
Kinetic description of classical matter infalling in black holes
Piero Nicolini; Massimo Tessarotto
2006-11-16
A popular aspect of black holes physics is the mathematical analogy between their laws, coming from general relativity and the laws of thermodynamics. The analogy is achieved by identifying a suitable set of observables, precisely: \\emph{(a)} $E=M$ (being $E$ the thermodynamic free energy and $M$ the mass of the BH), \\emph{(b)} $T=\\alpha \\kappa $ (with $T$ the absolute temperature, $\\kappa $ the so-called surface gravity on event horizon and $% \\alpha $ a suitable dimensional constant) and \\emph{(c)} $S=(1/8\\pi \\alpha)A $ (where $S$ is the thermodynamic entropy of the black hole and $A$ the surface of the event horizon). However, despite numerous investigations and efforts spent on the subject, the theoretical foundations of such identifications between physical quantities belonging to apparently unrelated frameworks are not yet clear. The goal of this work is to provide the contribution to the black hole entropy, coming from matter in the black hole exterior. We propose a classical solution for the kinetic description of matter falling into a black hole, which permits to evaluate both the kinetic entropy and the entropy production rate of classical infalling matter at the event horizon. The formulation is based on a relativistic kinetic description for classical particles in the presence of an event horizon. An H-theorem is established which holds for arbitrary models of black holes and is valid also in the presence of contracting event horizons.
Fully implicit kinetic modelling of collisional plasmas
Mousseau, V.A.
1996-05-01
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.
Solitary kinetic Alfven waves in dusty plasmas
Li Yangfang; Wu, D. J.; Morfill, G. E.
2008-08-15
Solitary kinetic Alfven 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-Alfvenic and the soliton velocity is obviously smaller than the Alfven speed. The other branch is super-Alfvenic and the soliton velocity is very close to or greater than the Alfven speed. Both compressive and rarefactive solitons can exist. For the sub-Alfvenic branch, the rarefactive soliton is bell-shaped and it is much narrower than the compressive one. However, for the super-Alfvenic 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-Alfvenic 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.
Solar wind plasma : kinetic properties and micro-instabilities
Kasper, Justin Christophe, 1977-
2003-01-01
The kinetic properties of ions in the solar wind plasma are studied. Observations of solar wind +H and +2He by the Faraday Cup instrument component of the Solar Wind Experiment on the Wind spacecraft show that these ions ...
Plasma Kinetics in the Ethanol/Water/Air Mixture in "Tornado" Type Electrical Discharge
Levko, D; Chernyak, V; Olszewski, S; Nedybaliuk, O
2011-01-01
This paper presents the results of a theoretical and experimental study of plasma-assisted reforming of ethanol into molecular hydrogen in a new modification of the "tornado" type electrical discharge. Numerical modeling clarifies the nature of the non-thermal conversion and explains the kinetic mechanism of nonequilibrium plasma-chemical transformations in the gas-liquid system and the evolution of hydrogen during the reforming as a function of discharge parameters and ethanol-to-water ratio in the mixture. We also propose a scheme of chemical reactions for plasma kinetics description. It is shown that some characteristics of the investigated reactor are at least not inferior to characteristics of other plasma chemical reactors.
On electromagnetic ballooning modes in fluid and kinetic descriptions
Froejdh, M.; Nordman, H.; Jhowry, B.
1995-11-01
A comparison between two-fluid, gyrofluid, and gyrokinetic descriptions of the collisionless ballooning mode in the toroidal limit is performed. The two-fluid model [A. Jarmen {ital et} {ital al}., Nucl. Fusion {bold 27}, 941 (1987)] is reactive and expanded in the finite-Larmor radius (FLR), in contrast to the gyrofluid model [R. E. Waltz {ital et} {ital al}., Phys. Fluids B {bold 4}, 3138 (1992)], which is dissipative and includes finite-Larmor-radius effects to all orders. The eigenmode differential equation is derived and solved numerically. It is shown that the fluid models are able to reproduce the gyrokinetic result, at least qualitatively. The role of the ion magnetic drift resonance and the ion FLR terms, in the fluid and kinetic descriptions, is discussed. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Kinetic modelling of runaway electron avalanches in tokamak plasmas
Nilsson, E; Peysson, Y; Granetz, R S; Saint-Laurent, F; Vlainic, M
2015-01-01
Runaway electrons (REs) can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force due to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate REs mainly through knock-on collisions, where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of REs. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3-D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. A bounce-averaged knock-on source term is derived. The generation of REs from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a s...
Multi-species and kinetic effects in ICF plasmas
NASA Astrophysics Data System (ADS)
Bellei, Claudio
2013-10-01
Traditionally, numerical codes that are used in the ICF community treat the plasma as an average-species fluid, neglecting the presence of multiple ion species, self-consistent electric (and magnetic) fields and kinetic effects. As compute power increases, multi-species, collisional particle-in-cell simulations of dense fusion plasmas are now becoming feasible. These simulations reveal rich and complex physics that has so far been mostly unexplored in the context of ICF implosions. This talk will present highly detailed simulations that push the boundary of conventional ICF modeling. In particular, we will show how gradients in pressure, temperature and electrostatic potential can lead to appreciable ion species separation as the ion-ion mean free paths increase during convergence of the spherical shock in the inner gas of an ICF capsule. The effects of species separation on fusion yield in ICF targets will be discussed. In addition, a kinetic description of the shock physics reveals characteristics of a weakly collisional system, including ion diffusion across the shock and reflection of the upstream ions at the shock front. When these (strong) shocks propagate across an interface that separates different materials (such as an ablator-gas interface), they can push a fraction of the ions from the ablator into the gas, enhancing mix. How this mix influences neutron yield will be examined. 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 LDRD-11-ERD-075 (LLNL) and NLUF/DOE DE-NA0002035 (MIT).
Kinetic study of ion-acoustic plasma vortices
Khan, S. A.; Aman-ur-Rehman; Mendonca, J. T.
2014-09-15
The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.
Kinetic modelling of runaway electron avalanches in tokamak plasmas
NASA Astrophysics Data System (ADS)
Nilsson, E.; Decker, J.; Peysson, Y.; Granetz, R. S.; Saint-Laurent, F.; Vlainic, M.
2015-09-01
Runaway electrons can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force owing to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate runaway electrons mainly through knock-on collisions (Hender et al 2007 Nucl. Fusion 47 S128-202), where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of runaway electrons. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. For this purpose, a bounce-averaged knock-on source term is derived. The generation of runaway electrons from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a solver of the 3D linearized bounce-averaged relativistic electron Fokker-Planck equation (Decker and Peysson 2004 DKE: a fast numerical solver for the 3D drift kinetic equation Report EUR-CEA-FC-1736, Euratom-CEA), through the calculation of the response of the electron distribution function to a constant parallel electric field. The model, which has been successfully benchmarked against the standard Dreicer runaway theory now describes the runaway generation by knock-on collisions as proposed by Rosenbluth (Rosenbluth and Putvinski 1997 Nucl. Fusion 37 1355-62). This paper shows that the avalanche effect can be important even in non-disruptive scenarios. Runaway formation through knock-on collisions is found to be strongly reduced when taking place off the magnetic axis, since trapped electrons can not contribute to the runaway electron population. Finally, the relative importance of the avalanche mechanism is investigated as a function of the key parameters for runaway electron formation, namely the plasma temperature and the electric field strength. In agreement with theoretical predictions, the LUKE simulations show that in low temperature and electric field the knock-on collisions becomes the dominant source of runaway electrons and can play a significant role for runaway electron generation, including in non-disruptive tokamak scenarios.
Energy Conservation Tests of a Coupled Kinetic-kinetic Plasma-neutral Transport Code
Stotler, D. P.; Chang, C. S.; Ku, S. H.; Lang, J.; Park, G.
2012-08-29
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.
Pedestal Fueling Simulations with a Coupled Kinetic-kinetic Plasma-neutral Transport Code
D.P. Stotler, C.S. Chang, S.H. Ku, J. Lang and G.Y. Park
2012-08-29
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.
A kinetic description of electron beam ejection from spacecraft
NASA Technical Reports Server (NTRS)
Khazanov, George V.; Neubert, Torsten; Gefan, Grigorii D.; Trukhan, Aleksander A.; Mishin, Evgeni V.
1993-01-01
A model based on the Boltzmann kinetic equation describing electron beam ejection from spacecraft is presented. Results are shown for steady-state, beam-atmosphere interaction (BAI) and for beam-plasma interaction (BPI). The BPI considered is that of elastic scattering of beam electrons with strong, short-scale Langmuir turbulence. This mechanism has been suggested for prompt echoes of beam electrons observed in sounding rocket experiments. It is shown that the interaction is sufficiently strong to account for observations of back-scattered electrons at the beam accelerator energy. However, it is clear from observations that particles undergo diffusion in energy at a rate exceeding levels expected for BAI. Inelastic scattering in BPI must therefore also be important.
Theory of spatially non-symmetric kinetic equilibria for collisionless plasmas
Cremaschini, Claudio; Tessarotto, Massimo
2013-01-15
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.
Consistent description of kinetic equation with triangle anomaly
Pu Shi; Gao Jianhua; Wang Qun
2011-05-01
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.
A consistent description of kinetic equation with triangle anomaly
Shi Pu; Jian-hua Gao; Qun Wang
2011-05-06
We provide a consistent description of the kinetic equation with 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 minimum number of unknown coefficients in one charge and two charge cases by solving the constraining equations.
Kinetic Modifications to MHD Phenomena in Toroidal Plasmas
C.Z. Cheng; N.N. Gorelenkov; G.J. Kramer; E. Fredrickson
2004-09-03
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.
Intermittent Dissipation and Heating in 3D Kinetic Plasma Turbulence.
Wan, M; Matthaeus, W H; Roytershteyn, V; Karimabadi, H; Parashar, T; Wu, P; Shay, M
2015-05-01
High resolution, fully kinetic, three dimensional (3D) simulation of collisionless plasma turbulence shows the development of turbulence characterized by sheetlike current density structures spanning a range of scales. The nonlinear evolution is initialized with a long wavelength isotropic spectrum of fluctuations having polarizations transverse to an imposed mean magnetic field. We present evidence that these current sheet structures are sites for heating and dissipation, and that stronger currents signify higher dissipation rates. The analyses focus on quantities such as J·E, electron, and proton temperatures, and conditional averages of these quantities based on local electric current density. Evidently, kinetic scale plasma, like magnetohydrodynamics, becomes intermittent due to current sheet formation, leading to the expectation that heating and dissipation in astrophysical and space plasmas may be highly nonuniform. Comparison with previous results from 2D kinetic simulations, as well as high frequency solar wind observational data, are discussed. PMID:25978241
Plasma outflow from a corrugated trap in the kinetic regime
Skovorodin, D. I.; Beklemishev, A. D.
2012-03-15
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.
Kinetic Modeling of Low-Temperature Plasma Assisted Combustion
NASA Astrophysics Data System (ADS)
Adamovich, Igor
2013-11-01
Quantitative insight into kinetics of low-temperature plasma assisted fuel oxidation and ignition would be impossible without kinetic modeling. The principal challenges in development of a predictive kinetic model of nonequilibrium plasmas sustained in fuel-air mixtures include (i) lack of ``conventional'' chemical kinetics mechanisms validated at low temperatures, (ii) lack of data on rates and products of reactions of excited species generated in the plasma, some of which are not well understood, and their coupling with fuel-air plasma chemistry, and (iii) scarcity of data obtained in well-characterized plasma-assisted combustion experiments, which can be used for model validation. ``Conventional'' combustion chemistry mechanisms have been developed for relatively high temperature conditions. Their applicability at temperatures below ignition temperature, common in plasma assisted combustion environments, needs to be assessed to determine if they can be used as a basis for a plasma-assisted combustion chemistry mechanism. This requires time-resolved measurements of radical species concentrations during low-temperature fuel oxidation, when an initial pool of primary radicals (O, H, and OH) is generated in the plasma, such as in the late afterglow of an electric discharge. This allows isolating relatively slow ``conventional'' low-temperature fuel oxidation reactions triggered by the radicals from the reactions of excited species generated in the discharge, which decay relatively rapidly. Kinetic modeling calculations demonstrated that some of the existing combustion mechanisms provide good agreement with the experimental data taken in lean H2-, CH4-, and C2H4-air mixtures at low temperatures, while data taken in C3H8-air are not reproduced by any of the mechanisms tested. A complementary approach is to focus on kinetics of ``rapid'' reactions of electronically and vibrationally excited species in the electric discharge, as well as oxygen dissociation by electron impact, and their effect on production of radicals in the early afterglow. These experiments provide key data on coupling of molecular energy transfer processes in the plasma with ``conventional'' chemical reactions. Time-resolved and spatially-resolved measurements of temperature, vibrational and electronic levels populations, and radical species concentrations are critical for characterization of the nonequilibrium reacting mixture at these conditions. Kinetic modeling of recent experiments in a diffuse filament, nanosecond pulse electric discharges in air suggest that the role of electronically excited N2* molecules on chemical reactions in the afterglow, such as NO generation reactions, has been significantly underestimated in the past. Further experiments in fuel-air mixtures are expected to provide additional data on the role of these excited species on low-temperature fuel-air chemistry.
Fully kinetic simulations of megajoule-scale dense plasma focus
Schmidt, A.; Link, A.; Tang, V.; Halvorson, C.; May, M.; Welch, D.; Meehan, B. T.; Hagen, E. C.
2014-10-15
Dense plasma focus (DPF) Z-pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. Megajoule-scale DPFs can generate 10{sup 12} neutrons per pulse in deuterium gas through a combination of thermonuclear and beam-target fusion. However, the details of the neutron production are not fully understood and past optimization efforts of these devices have been largely empirical. Previously, we reported on the first fully kinetic simulations of a kilojoule-scale DPF and demonstrated that both kinetic ions and kinetic electrons are needed to reproduce experimentally observed features, such as charged-particle beam formation and anomalous resistivity. Here, we present the first fully kinetic simulation of a MegaJoule DPF, with predicted ion and neutron spectra, neutron anisotropy, neutron spot size, and time history of neutron production. The total yield predicted by the simulation is in agreement with measured values, validating the kinetic model in a second energy regime.
Fully kinetic simulations of megajoule-scale dense plasma focus
NASA Astrophysics Data System (ADS)
Schmidt, A.; Link, A.; Welch, D.; Meehan, B. T.; Tang, V.; Halvorson, C.; May, M.; Hagen, E. C.
2014-10-01
Dense plasma focus (DPF) Z-pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. Megajoule-scale DPFs can generate 1012 neutrons per pulse in deuterium gas through a combination of thermonuclear and beam-target fusion. However, the details of the neutron production are not fully understood and past optimization efforts of these devices have been largely empirical. Previously, we reported on the first fully kinetic simulations of a kilojoule-scale DPF and demonstrated that both kinetic ions and kinetic electrons are needed to reproduce experimentally observed features, such as charged-particle beam formation and anomalous resistivity. Here, we present the first fully kinetic simulation of a MegaJoule DPF, with predicted ion and neutron spectra, neutron anisotropy, neutron spot size, and time history of neutron production. The total yield predicted by the simulation is in agreement with measured values, validating the kinetic model in a second energy regime.
Cremaschini, Claudio; Ková?, Ji?í; Slaný, Petr; Stuchlík, Zden?k; Karas, Vladimír
2013-11-01
The possible occurrence of equilibrium off-equatorial tori in the gravitational and electromagnetic fields of astrophysical compact objects has been recently proved based on non-ideal magnetohydrodynamic theory. These stationary structures can represent plausible candidates for the modeling of coronal plasmas expected to arise in association with accretion disks. However, accretion disk coronae are formed by a highly diluted environment, and so the fluid description may be inappropriate. The question is posed of whether similar off-equatorial solutions can also be determined in the case of collisionless plasmas for which treatment based on kinetic theory, rather than a fluid one, is demanded. In this paper the issue is addressed in the framework of the Vlasov-Maxwell description for non-relativistic, multi-species axisymmetric plasmas subject to an external dominant spherical gravitational and dipolar magnetic field. Equilibrium configurations are investigated and explicit solutions for the species kinetic distribution function are constructed, which are expressed in terms of generalized Maxwellian functions characterized by isotropic temperature and non-uniform fluid fields. The conditions for the existence of off-equatorial tori are investigated. It is proved that these levitating systems are admitted under general conditions when both gravitational and magnetic fields contribute to shaping the spatial profiles of equilibrium plasma fluid fields. Then, specifically, kinetic effects carried by the equilibrium solution are explicitly provided and identified here with diamagnetic energy-correction and electrostatic contributions. It is shown that these kinetic terms characterize the plasma equation of state by introducing non-vanishing deviations from the assumption of thermal pressure.
Kinetics of complex plasma with liquid droplets
Misra, Shikha; Sodha, M. S.; Mishra, S. K.
2013-12-15
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.
Emergence of kinetic behavior in streaming ultracold neutral plasmas
McQuillen, P.; Castro, J.; Bradshaw, S. J.; Killian, T. C.
2015-04-15
We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data are compared with results from a one-dimensional, two-fluid numerical simulation.
NASA Technical Reports Server (NTRS)
Roth, J. R.
1976-01-01
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.
NASA Technical Reports Server (NTRS)
Roth, J. R.
1976-01-01
Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.
Kinetic theory of nonlinear transport phenomena in complex plasmas
Mishra, S. K.; Sodha, M. S.
2013-03-15
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.
Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations in a Weakly Collisional Plasma
Ng, Chung-Sang
Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations in a Weakly Collisional Plasma C. S. These eigenmodes, which are smooth and compose a complete discrete spectrum, play the same role for weakly, a broad and continuous spectrum of CaseVan Kampen modes is excited. The Landau-damped solutions emerge
Complexity reduction of collisional-radiative kinetics for atomic plasma
Le, Hai P.; Karagozian, Ann R.; Cambier, Jean-Luc
2013-12-15
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.
Toward a Fully Kinetic Theory of Turbulence in Magnetized Plasmas
Yoon, Peter H.
2010-12-30
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.
Transition from Kinetic to MHD Behavior in a Collisionless Plasma
NASA Astrophysics Data System (ADS)
Parashar, Tulasi N.; Matthaeus, William H.; Shay, Michael A.; Wan, Minping
2015-10-01
The study of kinetic effects in heliospheric plasmas requires representation of dynamics at sub-proton scales, but in most cases the system is driven by magnetohydrodynamic (MHD) activity at larger scales. The latter requirement challenges available computational resources, which raises the question of how large such a system must be to exhibit MHD traits at large scales while kinetic behavior is accurately represented at small scales. Here we study this implied transition from kinetic to MHD-like behavior using particle-in-cell (PIC) simulations, initialized using an Orszag-Tang Vortex. The PIC code treats protons, as well as electrons, kinetically, and we address the question of interest by examining several different indicators of MHD-like behavior.
Cremaschini, Claudio Stuchlík, Zden?k; Tessarotto, Massimo; Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste
2014-03-15
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.
Lankin, A. V.; Norman, G. E.
2010-12-15
A model capable of describing the kinetics of collisional recombination in nonideal plasmas by the methods of molecular dynamics is developed. The dependence of the collisional recombination rate on the coupling parameter is found to differ substantially from the extrapolation of the three-body recombination rate in nonideal plasmas. A sharp decrease in the recombination rate in strongly nonideal plasmas is revealed. As the coupling parameter decreases, collisional recombination transforms into three-body recombination.
Non Equilbrium Vibrational Kinetics in Expanding Plasma Flows
Colonna, Gianpiero
2008-12-31
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.
Simulations of Magnetic Reconnection - Kinetic Mechanisms Underlying the Fluid Description of Ions
NASA Technical Reports Server (NTRS)
Aunai, icolas; Belmont, Gerard; Smets, Roch
2012-01-01
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.
The kinetic approach in magnetospheric plasma transport modeling
NASA Technical Reports Server (NTRS)
Horwitz, J. L.
1988-01-01
The need for a kinetic approach in magnetospheric plasma transport problems is reviewed, as are the trends in its recent applications. The need for kinetic modeling is particularly obvious when confronted with the astonishing variety of magnetospheric particle measurements that display compelling energy and pitch angle-related spatial and/or temporal dispersion, and various types of highly non-Maxwellian features in the distribution functions. Global problems in which the kinetic approach has recently been applied include solar wind plasma injection and dispersion over the cusp, substorm particle injection near synchronous orbit, synergistic energization of ionospheric ions into ring current populations by waves and induced electric field-driven convection, and ionospheric outflow from restricted source regions into the magnetosphere. Kinetic modeling can include efforts ranging from test-particle techniques to particle-in-cell studies, and this range is considered here. There are some areas where fluid and kinetic approaches have been combined or patched together, and these will be briefly discussed.
Cremaschini, Claudio; Stuchlík, Zden?k; Tessarotto, Massimo
2013-05-15
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.
Kinetic Alfvén solitary and rogue waves in superthermal plasmas
Bains, A. S.; Li, Bo Xia, Li-Dong
2014-03-15
We investigate the small but finite amplitude solitary Kinetic Alfvén waves (KAWs) in low ? plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter ?, plasma ?, and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfvénic, compressive solitons are supported. We then extend the study to examine kinetic Alfvén rogue waves by deriving a nonlinear Schrödinger equation from the KdV equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermality whereas the opposite is true when the plasma ? increases. The findings of this study may find applications to low ? plasmas in astrophysical environments where particles are superthermally distributed.
Species separation and kinetic effects in collisional plasma shocks
Bellei, C. Wilks, S. C.; Amendt, P. A.; Rinderknecht, H.; Zylstra, A.; Rosenberg, M.; Sio, H.; Li, C. K.; Petrasso, R.
2014-05-15
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{sup ?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 D{sup 3}He fusion reactivity is discussed in the fluid limit and is estimated to be moderately important.
Transition of electron kinetics in weakly magnetized inductively coupled plasmas
Kim, Jin-Yong; Lee, Hyo-Chang; Kim, Young-Do; Chung, Chin-Wook; Kim, Young-Cheol
2013-10-15
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.
On bias of kinetic temperature measurements in complex plasmas
Kantor, M.; Association Euratom-FOM Institute DIFFER, 3430 BE Nieuwegein; Ioffe Institute, RAS, St. Petersburg 194021 ; Moseev, D.; Salewski, M.
2014-02-15
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.
Kinetic modeling of the Saturn ring-ionosphere plasma environment
NASA Technical Reports Server (NTRS)
Wilson, G. R.; Waite, J. H., Jr.
1989-01-01
A time-independent kinetic plasma model was developed on the basis of the Li et al. (1988) semikinetic plasma model and was used to study the interaction of the Saturnian ionosphere and ring plasma. The model includes the gravitational magnetic mirror and centripetal and ambipolar electric forces, and the effect of the mixing of two plasma populations. The results obtained indicate that the density, temperature, and composition of plasma near the rings changing in the direction from the inner C ring to the outer A ring, due to the fact that the predominant source of plasma changes from the ionosphere to the rings. The model results also suggest that the outflow of hydrogen from the ionosphere to the rings may be shut off for field lines passing through the outer B and A ring, due to the ambipolar electric field set up by the warm ring plasma trapped near the ring plane by the centipetal force. In these regions, there will be a net flux of O(+) ions from the rings to the ionosphere.
Plasma transport induced by kinetic Alfven wave turbulence
Izutsu, T.; Hasegawa, H.; Fujimoto, M.; Nakamura, T. K. M.
2012-10-15
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.
Nonlinear gyrofluid description of turbulent magnetized plasmas
Brizard, A. )
1992-05-01
Nonlinear {ital gyrofluid} equations are obtained from the {ital gyrocenter}-{ital fluid} moments of the nonlinear gyrokinetic Vlasov equation, which describes an equilibrium magnetized nonuniform plasma perturbed by electromagnetic field fluctuations ({delta}{phi},{delta}{ital A}{sub {parallel}},{delta}{ital B}{sub {parallel}}), whose space-time scales satisfy the gyrokinetic ordering: {omega}{much lt}{Omega}{sub {ital i}}, {vert bar}{ital k}{sub {parallel}}{vert bar}/{ital k}{sub {perpendicular}}{much lt}1, and {epsilon}{sub {perpendicular}}{equivalent to}({ital k}{sub {perpendicular}}{rho}{sub {ital i}}){sup 2}{congruent}O(1). These low-frequency ({ital reduced}) fluid equations contain terms of arbitrary order in {epsilon}{sub {perpendicular}} and take into account the nonuniformity in the equilibrium density and temperature of the ion and electron species, as well as the nonuniformity in the equilibrium magnetic field. From the gyrofluid equations, one can systematically derive nonlinear reduced fluid equations with finite-Larmor-radius (FLR) corrections, which contain linear and nonlinear terms of O({epsilon}{sub {perpendicular}}), by expressing the {ital gyrocenter}-{ital fluid} moments appearing in the gyrofluid equations in terms of the {ital particle}-{ital fluid} moments, and then keeping terms up to O({epsilon}{sub {perpendicular}}) in the {epsilon}{sub {perpendicular}} expansion of the gyrofluid equations. By using gyrocenter-fluid moments, this new gyrofluid approach effectively bypasses the issue of the gyroviscous cancellations, while retaining all the important diamagnetic effects and the gyroviscous corrections. From the present FLR-corrected reduced fluid equations, the reduced Braginskii equations are recoverd for the ion and electron species (without collisional dissipation) and the ideal reduced magnetohydrodynamic (MHD) equations (in the absence of FLR effects).
Igor D. Kaganovich; Oleg Polomarov
2003-05-19
In low-pressure discharges, when the electron mean free path is larger or comparable with the discharge length, the electron dynamics is essentially non-local. Moreover, the electron energy distribution function (EEDF) deviates considerably from a Maxwellian. Therefore, an accurate kinetic description of the low-pressure discharges requires knowledge of the non-local conductivity operator and calculation of the non-Maxwellian EEDF. The previous treatments made use of simplifying assumptions: a uniform density profile and a Maxwellian EEDF. In the present study a self-consistent system of equations for the kinetic description of nonlocal, non-uniform, nearly collisionless plasmas of low-pressure discharges is derived. It consists of the nonlocal conductivity operator and the averaged kinetic equation for calculation of the non-Maxwellian EEDF. The importance of accounting for the non-uniform plasma density profile on both the current density profile and the EEDF is demonstrated.
Plasma turbulence and instabilities at ion kinetic scales
NASA Astrophysics Data System (ADS)
Hellinger, Petr; Matteini, Lorenzo; Landi, Simone; Verdini, Andrea; Franci, Luca; Travnicek, Pavel
2015-04-01
In situ observations in the solar wind indicate existence of many bounds on plasma parameters which are often compatible with constraints expected from theoretical linear predictions for kinetic instabilities in homogeneous plasmas. Relationship between these instabilities and ubiquitous large-amplitude turbulent fluctuations in the expanding solar wind remains to large extent an open problem. We will present results from a two-dimensional, large-scale hybrid expanding box simulation of the solar wind plasma turbulence. We impose an initial ambient magnetic field perpendicular to the simulation box, and we add an isotropic and balanced spectrum of large-scale, linearly polarized Alfvén waves with relatively strong amplitudes and we let the system evolve in a slowly expanding medium. A turbulent cascade rapidly develops with a Kolmogorov-like spectrum on large scales and a steeper spectrum on smaller scales. The turbulent spectrum heats protons both in parallel and perpendicular directions but this heating is not sufficient to overcome the double-adiabatic perpendicular cooling due to the expansion. This generates an important proton parallel temperature anisotropy which eventually leads to a fire hose-like instability which locally develops and reduces the temperature anisotropy. The present work demonstrates that fire hose can coexist with turbulence and even in the regime of strong turbulence constrains the plasma parameter space. This supports the interpretation of the many observed bounds being consequence of constraints owing to kinetic instabilities.
NASA Technical Reports Server (NTRS)
Manning, Robert M.
2009-01-01
Based on a theoretical model of the propagation of electromagnetic waves through a hypersonically induced plasma, it has been demonstrated that the classical radiofrequency communications blackout that is experienced during atmospheric reentry can be mitigated through the appropriate control of an external magnetic field of nominal magnitude. The model is based on the kinetic equation treatment of Vlasov and involves an analytical solution for the electric and magnetic fields within the plasma allowing for a description of the attendant transmission, reflection and absorption coefficients. The ability to transmit through the magnetized plasma is due to the magnetic windows that are created within the plasma via the well-known whistler modes of propagation. The case of 2 GHz transmission through a re-entry plasma is considered. The coefficients are found to be highly sensitive to the prevailing electron density and will thus require a dynamic control mechanism to vary the magnetic field as the plasma evolves through the re-entry phase.
Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas G. G. Howes,1,* W. Dorland,2
Tatsuno, Tomoya
Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas G. G. Howes,1,* W. Dorland,2 electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma turbulence of AlfveÂ´n waves above the ion gyroscale (spectral index Ã¿5=3) and of kinetic AlfveÂ´n waves below
Intermittent Dissipation at Kinetic Scales in Collisionless Plasma Turbulence W. H. Matthaeus,1
Shay, Michael
of the solar wind [5]. Recently we showed, using state of the art kinetic simulations [10], that a hierarchyIntermittent Dissipation at Kinetic Scales in Collisionless Plasma Turbulence M. Wan,1 W. H August 2012; published 5 November 2012) High resolution kinetic simulations of collisionless plasma
Kinetic description of fermion production in the oscillator representation
V. N. Pervushin; V. V. Skokov
2006-11-25
We investigate the fermion creation in quantum kinetic theory by applying ``oscillator representation'' approach, which was earlier developed for bosonic systems. We show that in some particular cases (Yukawa-like interaction, fixed direction of external vector field) resulting Kinetic Equation (KE) reduces to KE obtained by time-dependent Bogoliubov transformation method. We conclude ``oscillator representation'' approach to be more universal for the derivation of quantum transport equations in strong space-homogeneous time-dependent fields. We discuss some possible applications of obtained KE to cosmology and particle production in strong laser fields.
Kinetic phenomena in charged particle transport in gases and plasmas
Petrovic, Zoran Lj.; Dujko, Sasa; Sasic, Olivera; Stojanovic, Vladimir; Malovic, Gordana
2012-05-25
The key difference between equilibrium (thermal) and non-equilibrium (low temperature - a.k.a. cold) plasmas is in the degree in which the shape of the cross sections influences the electron energy distribution function (EEDF). In this paper we will discuss the issue of kinetic phenomena from two different angles. The first will be how to take advantage of the strong influence and use low current data to obtain the cross sections. This is also known as the swarm technique and the product of a ''swarm analysis'' is a set of cross sections giving good number, momentum and energy balances of electrons or other charged particles. At the same time understanding the EEDF is based on the cross section data. Nevertheless sometimes the knowledge of the cross sections and even the behaviour of individual particles are insufficient to explain collective behaviour of the ensemble. The resulting ''kinetic'' effects may be used to favour certain properties of non-equilibrium plasmas and even may be used as the basis of some new plasma applications.
Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas
G. G. Howes; W. Dorland; S. C. Cowley; G. W. Hammett; E. Quataert; A. A. Schekochihin; T. Tatsuno
2007-11-27
This letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale). Magnetic and electric-field energy spectra show a break at the ion gyroscale; the spectral slopes are consistent with scaling predictions for critically balanced turbulence of Alfven waves above the ion gyroscale (spectral index -5/3) and of kinetic Alfven waves below the ion gyroscale (spectral indices of -7/3 for magnetic and -1/3 for electric fluctuations). This behavior is also qualitatively consistent with in situ measurements of turbulence in the solar wind. Our findings support the hypothesis that the frequencies of turbulent fluctuations in the solar wind remain well below the ion cyclotron frequency both above and below the ion gyroscale.
Propagation of radiation in fluctuating multiscale plasmas. II. Kinetic simulations
Pal Singh, Kunwar; Robinson, P. A.; Cairns, Iver H.; Tyshetskiy, Yu.
2012-11-15
A numerical algorithm is developed and tested that implements the kinetic treatment of electromagnetic radiation propagating through plasmas whose properties have small scale fluctuations, which was developed in a companion paper. This method incorporates the effects of refraction, damping, mode structure, and other aspects of large-scale propagation of electromagnetic waves on the distribution function of quanta in position and wave vector, with small-scale effects of nonuniformities, including scattering and mode conversion approximated as causing drift and diffusion in wave vector. Numerical solution of the kinetic equation yields the distribution function of radiation quanta in space, time, and wave vector. Simulations verify the convergence, accuracy, and speed of the methods used to treat each term in the equation. The simulations also illustrate the main physical effects and place the results in a form that can be used in future applications.
Ultrahigh performance three-dimensional electromagnetic relativistic kinetic plasma simulation
Bowers, K. J.; Albright, B. J.; Yin, L.; Bergen, B.; Kwan, T. J. T.
2008-05-15
The algorithms, implementation details, and applications of VPIC, a state-of-the-art first principles 3D electromagnetic relativistic kinetic particle-in-cell code, are discussed. Unlike most codes, VPIC is designed to minimize data motion, as, due to physical limitations (including the speed of light{exclamation_point}), moving data between and even within modern microprocessors is more time consuming than performing computations. As a result, VPIC has achieved unprecedented levels of performance. For example, VPIC can perform {approx}0.17 billion cold particles pushed and charge conserving accumulated per second per processor on IBM's Cell microprocessor--equivalent to sustaining Los Alamos's planned Roadrunner supercomputer at {approx}0.56 petaflop (quadrillion floating point operations per second). VPIC has enabled previously intractable simulations in numerous areas of plasma physics, including magnetic reconnection and laser plasma interactions; next generation supercomputers like Roadrunner will enable further advances.
Kinetic Description of Vacuum Creation of Massive Vector Bosons
Blaschke, D.B.; Prozorkevich, A.V.; Smolyansky, S.A.; Reichel, A.V.
2005-06-01
In the simple model of massive vector field in a flat spacetime, we derive the kinetic equation of non-Markovian type describing the vacuum pair creation under action of external fields of different nature. We use for this aim the nonperturbative methods of kinetic theory in combination with a new element when the transition of the instantaneous quasiparticle representation is realized within the oscillator (holomorphic) representation. We study in detail the process of vacuum creation of vector bosons generated by a time-dependent boson mass in accordance with the framework of a conformal-invariant scalar-tensor gravitational theory and its cosmological application. It is indicated that the choice of the equation of state allows one to obtain a number density of vector bosons that is sufficient to explain the observed number density of photons in the cosmic microwave background radiation.
Dextromethorphan and codeine: comparison of plasma kinetics and antitussive effects.
Aylward, M; Maddock, J; Davies, D E; Protheroe, D A; Leideman, T
1984-05-01
Plasma kinetics of dextromethorphan (as dextrorphan ) and codeine were investigated after acute oral doses in 8 patients with pathological cough; after which the patients participated in an acute dose-response study of the antitussive effects of each drug administered as syrups. Maximum plasma codeine concentrations averaged 384 ng.ml-1 (s.d. +/- 78.3) occurring between 0.75 and 2h after ingestion of 60 mg codeine phosphate; in comparison mean peak plasma dextrorphan levels were 386 ng.ml-1 (s.d. +/- 107.2) and 388 ng.ml-1 (s.d. +/- 101.3) respectively, after administration of 60 mg dextromethorphan syrup and tablet formulations. Bioavailability of dextromethorphan tablets was comparable to syrup. No correlation emerged between instantaneous plasma concentrations of either dextrorphan or codeine and antitussive responses; however, peak antitussive effect was significantly related to log dose with both drugs. Antitussive effects of 30 mg codeine phosphate and 60 mg dextromethorphan hydrobromide did not differ significantly; both were superior to 30 mg dextromethorphan hydrobromide and placebo. PMID:6539224
Kee, R.J.; Rupley, F.M.; Meeks, E.; Miller, J.A.
1996-05-01
This document is the user`s manual for the third-generation CHEMKIN package. CHEMKIN is a software package whose purpose is to facilitate the formation, solution, and interpretation of problems involving elementary gas-phase chemical kinetics. It provides a flexible and powerful tool for incorporating complex chemical kinetics into simulations of fluid dynamics. The package consists of two major software components: an Interpreter and a Gas-Phase Subroutine Library. The Interpreter is a program that reads a symbolic description of an elementary, user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Gas-Phase Subroutine Library. This library is a collection of about 100 highly modular FORTRAN subroutines that may be called to return information on equations of state, thermodynamic properties, and chemical production rates. CHEMKIN-III includes capabilities for treating multi-fluid plasma systems, that are not in thermal equilibrium. These new capabilities allow researchers to describe chemistry systems that are characterized by more than one temperature, in which reactions may depend on temperatures associated with different species; i.e. reactions may be driven by collisions with electrons, ions, or charge-neutral species. These new features have been implemented in such a way as to require little or no changes to CHEMKIN implementation for systems in thermal equilibrium, where all species share the same gas temperature. CHEMKIN-III now has the capability to handle weakly ionized plasma chemistry, especially for application related to advanced semiconductor processing.
cathode in the afterglow of an rf plasma. The measured sheath potential shrunk to zero as the plasmaKinetic Theory of Plasma Sheaths Surrounding Electron-Emitting Surfaces J. P. Sheehan* and N. D. Kaganovich, H. Wang, and Y. Raitses Princeton Plasma Physics Laboratory, Princeton, New Jersey
From kinetic MHD in stellarators to a fully kinetic description of wave particle interaction
Koenies, Axel; Mishchenko, Alexey; Hatzky, Roman
2008-11-01
We use a linearized model of kinetic MHD for the perturbative calculation of growth rates of Alfven eigenmodes.The numerical model, a code called CAS3D-K, is based on the three-dimensional ideal MHD stability code CAS3D and a numeric solution of the drift kinetic equation which avoids approximations to the magnetic geometry but neglects the drifts of the particles away from the flux surface.The approach is used to discuss stability boundaries in W7-X and W7-AS and considers both, passing and reflected particles. The limits of the applicability of the model will be discussed as well.It will be shown that gyro-kinetic PIC codes offer a very promising way to improve the model. The two-dimensional linear PIC code GYGLES is used to calculate gyro-kinetic counterparts of ideal MHD modes in cylindrical and in tokamak geometry.
Fluid description of multi-component solar partially ionized plasma
Khomenko, E. Collados, M.; Vitas, N.; Díaz, A.
2014-09-15
We derive self-consistent formalism for the description of multi-component partially ionized solar plasma, by means of the coupled equations for the charged and neutral components for an arbitrary number of chemical species, and the radiation field. All approximations and assumptions are carefully considered. Generalized Ohm's law is derived for the single-fluid and two-fluid formalism. Our approach is analytical with some order-of-magnitude support calculations. After general equations are developed, we particularize to some frequently considered cases as for the interaction of matter and radiation.
Fluid description of multi-component solar partially ionized plasma
NASA Astrophysics Data System (ADS)
Khomenko, E.; Collados, M.; Díaz, A.; Vitas, N.
2014-09-01
We derive self-consistent formalism for the description of multi-component partially ionized solar plasma, by means of the coupled equations for the charged and neutral components for an arbitrary number of chemical species, and the radiation field. All approximations and assumptions are carefully considered. Generalized Ohm's law is derived for the single-fluid and two-fluid formalism. Our approach is analytical with some order-of-magnitude support calculations. After general equations are developed, we particularize to some frequently considered cases as for the interaction of matter and radiation.
Microscopic Lagrangian description of warm plasmas. IV - Macroscopic approximation
NASA Technical Reports Server (NTRS)
Kim, H.; Crawford, F. W.
1983-01-01
The averaged-Lagrangian method is applied to linear wave propagation and nonlinear three-wave interaction in a warm magnetoplasma, in the macroscopic approximation. The microscopic Lagrangian treated by Kim and Crawford (1977) and by Galloway and Crawford (1977) is first expanded to third order in perturbation. Velocity integration is then carried out, before applying Hamilton's principle to obtain a general description of wave propagation and coupling. The results are specialized to the case of interaction between two electron plasma waves and an Alfven wave. The method is shown to be more powerful than the alternative possibility of working from the beginning with a macroscopic Lagrangian density.
KInetic Effect on Dynamics of Plasma Coherent Structures
NASA Astrophysics Data System (ADS)
Ishiguro, Seiji; Hasegawa, Hiroki
2013-10-01
Kinetic effects on plasma blob dynamics have been studied by means of a three dimensional electrostatic plasma particle simulation code with particle absorbing boundaries. In the particle simulation, an external magnetic field B is pointing into the z direction (corresponding to the toroidal direction). The strength of magnetic field increases in the positive x direction (corresponding to the counter radial direction), i.e., ?B / ?x > 0 . A coherent structure is initially set as a column along the external magnetic field and propagates in the - x direction. In this study, we have investigated the dependence of blob propagation on the ion-to-electron temperature ratio and the magnetic field strength. When the magnetic field strength is decreased (or the ion-to-electron temperature ratio is increased), we have found that the symmetry breaking in a blob profile occurs. This fact is thought to indicate that the effect of gyro motion of plasma particles induces the symmetry breaking. Supported by NIFS Collaboration Research programs (NIFS13KNSS038 and NIFS13KNXN258) and a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (KAKENHI 23740411).
Complex (dusty) plasmas-kinetic studies of strong coupling phenomena
Morfill, Gregor E.; Ivlev, Alexei V.; Thomas, Hubertus M.
2012-05-15
'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.
Kinetic description of particle emission from expanding source
V. K. Magas; L. P. Csernai
2008-04-22
The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine kinetic freeze out equations with Bjorken type system expansion into a unified model. The important feature of the proposed scenario is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersurface) to infinity. The dependence of the post freeze out distribution function on the freeze out time will be studied. As an example, model is completely solved and analyzed for the gas of pions. We shall see that the basic freeze out features, pointed out in the earlier works, are not smeared out by the expansion of the system. The entropy evolution in such a scenario is also studied.
Phase Transition in Dusty Plasmas: A Microphysical Description
NASA Technical Reports Server (NTRS)
Joyce, Glenn; Ganguli, Gurudas; Lampe, Martin
2002-01-01
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.
Kinetic Stress and Intrinsic Flow in a Toroidal Plasma W. X. Ding,1,3
Wisconsin at Madison, University of
2012; published 8 February 2013) A new mechanism for intrinsic plasma flow has been experimentally with magnetic fluctuations create a kinetic stress that can affect momentum balance and the evolution field pinch plasma. Measurements reveal that the force density associated with the kinetic stress
Effect of driving frequency on excitation of turbulence in a kinetic plasma T. N. Parashar,1
Shay, Michael
hybrid simulations have full kinetic ion physics including Ki- netic Alfve´n Waves, our simulations of turbulence generation through magnetic forcing is studied using kinetic hybrid simulations with fully kinetic energy is much lower. The heating of the plasma is correlated with intermittent properties
Kinetics of a Model Weakly Ionized Plasma in the Presence of Multiple Equilibria
Kinetics of a Model Weakly Ionized Plasma in the Presence of Multiple Equilibria by E. Carlen 1 , R mann type kinetic equation containing a full nonlinear electronelectron collision term as well a coupled set of nonlinear ODE's that constitute the ``hydrodynamical'' equations for this kinetic system
Quantum kinetic theory of plasmas in strong laser fields D. Kremp, Th. Bornath, and M. Bonitz
Bonitz, Michael
Quantum kinetic theory of plasmas in strong laser fields D. Kremp, Th. Bornath, and M. Bonitz Received 9 February 1999 A kinetic theory for quantum many-particle systems in time-dependent electromagnetic fields is developed based on a gauge-invariant formulation. The resulting kinetic equation
Cremaschini, Claudio Stuchlík, Zden?k; Tessarotto, Massimo; Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste
2014-05-15
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.
Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model
NASA Technical Reports Server (NTRS)
Lipatov, Alexander S.; Combi, Michael R.
2004-01-01
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.
Kinetic theory of weak turbulence in magnetized plasmas: Perpendicular propagation
NASA Astrophysics Data System (ADS)
Yoon, Peter H.
2015-08-01
The present paper formulates a weak turbulence theory in which electromagnetic perturbations are assumed to propagate in directions perpendicular to the ambient magnetic field. By assuming that all wave vectors lie in one direction transverse to the ambient magnetic field, the linear solution and second-order nonlinear solutions to the equation for the perturbed distribution function are obtained. Nonlinear perturbed current from the second-order nonlinearity is derived in general form, but the limiting situation of cold plasma temperature is taken in order to derive an explicit nonlinear wave kinetic equation that describes three-wave decay/coalescence interactions among X and Z modes. A potential application of the present formalism is also discussed.
Advances in petascale kinetic plasma simulation with VPIC and Roadrunner
Bowers, Kevin J; Albright, Brian J; Yin, Lin; Daughton, William S; Roytershteyn, Vadim; Kwan, Thomas J T
2009-01-01
VPIC, a first-principles 3d electromagnetic charge-conserving relativistic kinetic particle-in-cell (PIC) code, was recently adapted to run on Los Alamos's Roadrunner, the first supercomputer to break a petaflop (10{sup 15} floating point operations per second) in the TOP500 supercomputer performance rankings. They give a brief overview of the modeling capabilities and optimization techniques used in VPIC and the computational characteristics of petascale supercomputers like Roadrunner. They then discuss three applications enabled by VPIC's unprecedented performance on Roadrunner: modeling laser plasma interaction in upcoming inertial confinement fusion experiments at the National Ignition Facility (NIF), modeling short pulse laser GeV ion acceleration and modeling reconnection in magnetic confinement fusion experiments.
Splitting of CO2 by vibrational excitation in non-equilibrium plasmas: a reaction kinetics model
NASA Astrophysics Data System (ADS)
Kozák, Tomáš; Bogaerts, Annemie
2014-08-01
We present a zero-dimensional kinetic model of CO2 splitting in non-equilibrium plasmas. The model includes a description of the CO2 vibrational kinetics (25 vibrational levels up to the dissociation limit of the molecule), taking into account state-specific VT and VV relaxation reactions and the effect of vibrational excitation on other chemical reactions. The model is applied to study the reaction kinetics of CO2 splitting in an atmospheric-pressure dielectric barrier discharge (DBD) and in a moderate-pressure microwave discharge. The model results are in qualitative agreement with published experimental works. We show that the CO2 conversion and its energy efficiency are very different in these two types of discharges, which reflects the important dissociation mechanisms involved. In the microwave discharge, excitation of the vibrational levels promotes efficient dissociation when the specific energy input is higher than a critical value (2.0 eV/molecule under the conditions examined). The calculated energy efficiency of the process has a maximum of 23%. In the DBD, vibrationally excited levels do not contribute significantly to the dissociation of CO2 and the calculated energy efficiency of the process is much lower (5%).
Unified description of linear screening in dense plasmas
NASA Astrophysics Data System (ADS)
Stanton, L. G.; Murillo, M. S.
2015-03-01
Electron screening of ions is among the most fundamental properties of plasmas, determining the effective ionic interactions that impact all properties of a plasma. With the development of new experimental facilities that probe high-energy-density physics regimes ranging from warm dense matter to hot dense matter, a unified framework for describing dense plasma screening has become essential. Such a unified framework is presented here based on finite-temperature orbital-free density functional theory, including gradient corrections and exchange-correlation effects. We find a new analytic pair potential for the ion-ion interaction that incorporates moderate electronic coupling, quantum degeneracy, gradient corrections to the free energy, and finite temperatures. This potential can be used in large-scale "classical" molecular dynamics simulations, as well as in simpler theoretical models (e.g., integral equations and Monte Carlo), with no additional computational complexity. The new potential theoretically connects limits of Debye-Hückel-Yukawa, Lindhard, Thomas-Fermi, and Bohmian quantum hydrodynamics descriptions. Based on this new potential, we predict ionic static structure factors that can be validated using x-ray Thomson scattering data.
Unified description of linear screening in dense plasmas.
Stanton, L G; Murillo, M S
2015-03-01
Electron screening of ions is among the most fundamental properties of plasmas, determining the effective ionic interactions that impact all properties of a plasma. With the development of new experimental facilities that probe high-energy-density physics regimes ranging from warm dense matter to hot dense matter, a unified framework for describing dense plasma screening has become essential. Such a unified framework is presented here based on finite-temperature orbital-free density functional theory, including gradient corrections and exchange-correlation effects. We find a new analytic pair potential for the ion-ion interaction that incorporates moderate electronic coupling, quantum degeneracy, gradient corrections to the free energy, and finite temperatures. This potential can be used in large-scale "classical" molecular dynamics simulations, as well as in simpler theoretical models (e.g., integral equations and Monte Carlo), with no additional computational complexity. The new potential theoretically connects limits of Debye-Hückel-Yukawa, Lindhard, Thomas-Fermi, and Bohmian quantum hydrodynamics descriptions. Based on this new potential, we predict ionic static structure factors that can be validated using x-ray Thomson scattering data. PMID:25871221
Electrical and kinetic model of an atmospheric rf device for plasma aerodynamics applications
Pinheiro, Mario J.; Martins, Alexandre A.
2010-08-15
The asymmetrically mounted flat plasma actuator is investigated using a self-consistent two-dimensional fluid model at atmospheric pressure. The computational model assumes the drift-diffusion approximation and uses a simple plasma kinetic model. It investigated the electrical and kinetic properties of the plasma, calculated the charged species concentrations, surface charge density, electrohydrodynamic forces, and gas speed. The present computational model contributes to understand the main physical mechanisms, and suggests ways to improve its performance.
Magnetized Plasma Sheath Simulation with the Kinetic Finite Mass Method
NASA Astrophysics Data System (ADS)
Young, Christopher; Larson, David; Cappelli, Mark
2013-09-01
First results of a magnetized plasma sheath simulation using the Kinetic Finite Mass (KFM) Method are presented. The KFM Method, derived from the Finite Mass Method of, is a gridless Lagrangian simulation technique that partitions the system mass into packets that evolve over time. The packets have finite extent in 1D phase space, continuous Gaussian internal mass distributions, and a defining set of Gauss-Hermite quadrature points that move under the action of forces. Much like in a Particle-In-Cell (PIC) approach, the electric field is calculated by solving Poisson's equation over a temporary grid and the local Lorentz force is mapped back to the particle locations. A Gaussian Mixture Model is employed periodically to reset the Gaussian character of the packets after distortion by the system forces. Sheath results are compared with conventional PIC simulations. This work provides a demonstration of the powerful KFM method in preparation for simulating more complex plasma phenomena. CY acknowledges support from the DOE NNSA Stewardship Science Graduate Fellowship, Contract DE-FC52-08NA28752. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory, Contract DE-AC52-07NA27344.
Diamagnetic boundary layers - A kinetic theory. [for collisionless magnetized plasmas
NASA Technical Reports Server (NTRS)
Lemaire, J.; Burlaga, L. F.
1976-01-01
A kinetic theory is presented for boundary layers associated with MHD tangential 'discontinuities' in a collisionless magnetized plasma, such as those observed in the solar wind. The theory consists of finding self-consistent solutions of Vlasov's equation and Maxwell's equation for stationary one-dimensional boundary layers separating two Maxwellian plasma states. Layers in which the current is carried by electrons are found to have a thickness of the order of a few electron gyroradii, but the drift speed of the current-carrying electrons is found to exceed the Alfven speed, and accordingly such layers are not stable. Several types of layers in which the current is carried by protons are discussed; in particular, cases are considered in which the magnetic-field intensity, direction, or both, changed across the layer. In every case, the thickness was of the order of a few proton gyroradii, and the field changed smoothly, although the characteristics depended somewhat on the boundary conditions. The drift speed was always less than the Alfven speed, consistent with stability of such structures. These results are consistent with observations of boundary layers in the solar wind near 1 AU.
Galvao, R. A.; Ziebell, L. F.
2012-09-15
In this work, we detail the derivation of a plasma kinetic theory leading to the components of the dielectric tensor for a magnetized dusty plasma with variable charge on the dust particles, considering that the dust component of the plasma contains spherical dust particles with different sizes, which are charged both by inelastic collisions of electrons and ions and by photoionization.
Microphysics of Cosmic Plasmas: Hierarchies of Plasma Instabilities from MHD to Kinetic
NASA Astrophysics Data System (ADS)
Brown, M. R.; Browning, P. K.; Dieckmann, M. E.; Furno, I.; Intrator, T. P.
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 .
Microphysics of Cosmic Plasmas: Hierarchies of Plasma Instabilities from MHD to Kinetic
NASA Astrophysics Data System (ADS)
Brown, M. R.; Browning, P. K.; Dieckmann, M. E.; Furno, I.; Intrator, T. P.
2013-10-01
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 .
Numerical modeling of radiation physics in kinetic plasmas [II
NASA Astrophysics Data System (ADS)
Paraschiv, Ioana; Sentoku, Yasuhiko; Mancini, Roberto
2014-10-01
X-ray radiation is an important feature of ultra-intense laser interactions with high Z materials. In order to take into account the radiation effects in the high energy density plasmas created by such interactions, we have modified the collisional particle-in-cell code PICLS to self-consistently model the x-ray radiation transport (RT). Solving the equation of radiation transport requires the creation of a non-LTE database of emissivities and opacities as functions of photon frequency for given densities, bulk electron temperatures, hot electron temperatures, and hot electron fractions. The database was generated using results computed by a non-equilibrium, collisional-radiative atomic kinetics code. Using the two-dimensional RT-PICLS code we have studied the X-ray transport in an ultrafast heated target and the dependence of the emitted K- ? radiation on the fast electron dynamics in the solid target. The details of these results obtained from the implementation of the radiation transport model into the PICLS calculations will be reported in this presentation. Work supported by the DOE Office of Science Grant No. DE-SC0008827 and by the NNSA/DOE Grants No. DE-FC52-06NA27616 and DE-NA0002075.
Richardson Extrapolation Based Error Estimation for Stochastic Kinetic Plasma Simulations
NASA Astrophysics Data System (ADS)
Cartwright, Keigh
2014-10-01
To have a high degree of confidence in simulations one needs code verification, validation, solution verification and uncertainty qualification. This talk will focus on numerical error estimation for stochastic kinetic plasma simulations using the Particle-In-Cell (PIC) method and how it impacts the code verification and validation. A technique Is developed to determine the full converged solution with error bounds from the stochastic output of a Particle-In-Cell code with multiple convergence parameters (e.g. ?t, ?x, and macro particle weight). The core of this method is a multi parameter regression based on a second-order error convergence model with arbitrary convergence rates. Stochastic uncertainties in the data set are propagated through the model usin gstandard bootstrapping on a redundant data sets, while a suite of nine regression models introduces uncertainties in the fitting process. These techniques are demonstrated on Flasov-Poisson Child-Langmuir diode, relaxation of an electro distribution to a Maxwellian due to collisions and undriven sheaths and pre-sheaths. Sandia National Laboratories is a multie-program laboratory managed and operated by Sandia Corporation, a wholly owned subisidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.
Simplex-In-Cell Method for Kinetic Plasma Simulation
NASA Astrophysics Data System (ADS)
Totorica, Samuel; Kates-Harbeck, Julian; Zrake, Jonathan; Abel, Tom
2014-10-01
We present a new particle-based method for kinetic plasma simulation that interprets the simulation particles as tracers of the distribution function in phase space. The construction of a piecewise linear approximation to the distribution function is enabled by interpolation of the tracer particles. With access to the full distribution function, moments such as density and velocity dispersion are defined continuously over the spatial domain. Charge and current densities obtained in this way are utilized in an improved particle-mesh force calculation, reducing particle discretization noise and more accurately modeling the continuum limit. The new method is implemented for 1D2V and compared with a cloud-in-cell deposit for electrostatic and electromagnetic test problems. Significant computational savings are shown when using the new method to model linear evolution. To simulate into the nonlinear regime we implement adaptive refinement of the mesh defined by the tracer particles, capturing the fine detail in the distribution function. These ideas may also be used as a post processing tool for standard PIC simulations, where the continuous density and velocity fields obtained eliminate the necessity of averaging over control volumes and associated statistical noise.
SOLAR WIND TURBULENT SPECTRUM AT PLASMA KINETIC SCALES
Alexandrova, O.; Lacombe, C.; Mangeney, A.; Maksimovic, M.; Grappin, R.
2012-12-01
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.
Effects of dust particles in plasma kinetics: Ion dynamics time scales
Angelis, U. de; Tolias, P.; Ratynskaia, S.
2012-07-15
The self-consistent kinetic theory of dusty plasmas [V. N. Tsytovich and U. de Angelis, Phys. Plasmas 6, 1093 (1999)] is extended to frequency regimes relevant for ion dynamics, accounting for both constant and fluctuating plasma sources. In contrast to earlier models, binary plasma collisions are no longer neglected with respect to collisions with dust; hence, the model developed here is also valid for low dust densities. Expressions are found for the system's permittivity, the ion collision integral, and the spectral densities of ion density fluctuations. The structure of the ion kinetic equation is analyzed, and applications of the model for both astrophysical and laboratory environments are discussed.
Effects of dust particles in plasma kinetics: Ion dynamics time scales
NASA Astrophysics Data System (ADS)
de Angelis, U.; Tolias, P.; Ratynskaia, S.
2012-07-01
The self-consistent kinetic theory of dusty plasmas [V. N. Tsytovich and U. de Angelis, Phys. Plasmas 6, 1093 (1999)] is extended to frequency regimes relevant for ion dynamics, accounting for both constant and fluctuating plasma sources. In contrast to earlier models, binary plasma collisions are no longer neglected with respect to collisions with dust; hence, the model developed here is also valid for low dust densities. Expressions are found for the system's permittivity, the ion collision integral, and the spectral densities of ion density fluctuations. The structure of the ion kinetic equation is analyzed, and applications of the model for both astrophysical and laboratory environments are discussed.
Effect of antenna size on electron kinetics in inductively coupled plasmas
Lee, Hyo-Chang; Chung, Chin-Wook
2013-10-15
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.
Ju, Yiguang
American Institute of Aeronautics and Astronautics 1 Kinetic Effects of Non-Equilibrium Plasma and Astronautics, Inc. All rights reserved. #12;American Institute of Aeronautics and Astronautics 2 Xf = fuel mole
Initial measurement of the kinetic dust temperature of a weakly coupled dusty plasma
Williams, Jeremiah D.; Thomas, Edward Jr.
2006-06-15
Measurements of the velocity space distribution function of 2.9 {mu}m diameter silica particles in an argon dc glow discharge dusty plasma are made through the use of stereoscopic particle image velocimetry (stereo-PIV). These distribution functions are then used to determine the kinetic temperature of the dust component. These measurements show that the kinetic temperature of the dust component is significantly larger than the other plasma components (electrons, ions, and background neutrals)
Kinetic parameters for plasma. beta. -endorphin in lean and obese Zucker rats
Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H. )
1991-03-01
To determine plasma clearance kinetics for {beta}-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats.
Kinetic and dynamic probability-density-function descriptions of disperse turbulent two-phase flows
NASA Astrophysics Data System (ADS)
Minier, Jean-Pierre; Profeta, Christophe
2015-11-01
This article analyzes the status of two classical one-particle probability density function (PDF) descriptions of the dynamics of discrete particles dispersed in turbulent flows. The first PDF formulation considers only the process made up by particle position and velocity Zp=(xp,Up) and is represented by its PDF p (t ;yp,Vp) which is the solution of a kinetic PDF equation obtained through a flux closure based on the Furutsu-Novikov theorem. The second PDF formulation includes fluid variables into the particle state vector, for example, the fluid velocity seen by particles Zp=(xp,Up,Us) , and, consequently, handles an extended PDF p (t ;yp,Vp,Vs) which is the solution of a dynamic PDF equation. For high-Reynolds-number fluid flows, a typical formulation of the latter category relies on a Langevin model for the trajectories of the fluid seen or, conversely, on a Fokker-Planck equation for the extended PDF. In the present work, a new derivation of the kinetic PDF equation is worked out and new physical expressions of the dispersion tensors entering the kinetic PDF equation are obtained by starting from the extended PDF and integrating over the fluid seen. This demonstrates that, under the same assumption of a Gaussian colored noise and irrespective of the specific stochastic model chosen for the fluid seen, the kinetic PDF description is the marginal of a dynamic PDF one. However, a detailed analysis reveals that kinetic PDF models of particle dynamics in turbulent flows described by statistical correlations constitute incomplete stand-alone PDF descriptions and, moreover, that present kinetic-PDF equations are mathematically ill posed. This is shown to be the consequence of the non-Markovian characteristic of the stochastic process retained to describe the system and the use of an external colored noise. Furthermore, developments bring out that well-posed PDF descriptions are essentially due to a proper choice of the variables selected to describe physical systems and guidelines are formulated to emphasize the key role played by the notion of slow and fast variables.
NASA Astrophysics Data System (ADS)
Dodd, E. S.; Barnes, D. C.; Bezzerides, B.; Dubois, D. F.; Vu, H. X.
2003-10-01
RPIC is a reduced-description PIC code designed to investigate laser-plasma instabilities (LPI) in physical systems with vastly-different time scales prevalent under ICF conditions(H.X. Vu, B. Bezzerides, D.F. DuBois, J. Comp. Phys. 156), 12 (1999)., typically studied with the extended Zakharov model. Comparisons between the extended Zakharov model and RPIC were presented in a series of papers(K.Y. Sanbonmatsu, H.X. Vu, D.F. DuBois, and B. Bezzerides, Phys. Rev. Lett. 82), 932 (1999); K.Y. Sanbonmatsu, H.X. Vu, B. Bezzerides, and D.F. DuBois, Phys. Plasmas. 7, 1723,2824 (2000)., where quantitative agreements are obtained in the fluid and quasi-linear regime. In the kinetic regime where particle trapping is important, differences were found. The RPIC model itself is limited, e.g., Langmuir wave frequency harmonics are neglected. Our goal is two fold in comparing RPIC with full PIC in 1-d. First, advantages of RPIC over full PIC will be quantitatively assessed. Second, for strong laser drives, harmonics may be important to LPI physics. We would like to establish the regime of validity for RPIC, and to assess if the regimes where RPIC fails is of interest to ICF indirect drive.
Zharkova, Valentina V.
THE NUMERIC CODE FOR MODELLING NONSTATIONARY KINETIC PROCESSES OF CHARGED PARTICLE BEAMS IN HOT numerical algorithm and Ccode is developed for modelling kinetics of charged particle beams in hot plasmas in a presence of external field. How does the work advance the stateoftheart?: The code gives fast temporal
Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model
NASA Technical Reports Server (NTRS)
Lipatov, Alexander S.; Combi, Michael R.
2006-01-01
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.
Generation of kinetic Alfven waves by beam-plasma interaction in non-uniform plasma
Hong, M. H.; Lin, Y.; Wang, X. Y.
2012-07-15
This work reports a novel mechanism of the generation of kinetic Alfven waves (KAWs) using a two-dimensional hybrid simulation: the KAWs are generated by ion beam-plasma interaction in a non-uniform plasma boundary layer, in which the bulk velocity of the ion beam is assumed to be parallel to the ambient magnetic field. As a result of the beam-plasma interaction, strong shear Alfven waves as well as fast mode compressional waves are first generated on the side of the boundary layer with a high density and thus a low Alfven speed, propagating along the background magnetic field. Later, Alfven waves also form inside the boundary layer with a continuous spectrum. As the perpendicular wave number k{sub Up-Tack} of these unstably excited waves increases with time, large-amplitude, short wavelength KAWs with k{sub Up-Tack } Much-Greater-Than k{sub ||} clearly form in the boundary layer. The physics for the generation of KAWs is discussed.
Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas
Cheng, C.Z.
1989-04-01
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.
Measurement of the kinetic dust temperature of a weakly coupled dusty plasma
Williams, Jeremiah D.; Thomas, Edward Jr.
2007-06-15
Measurements of the kinetic velocity space distribution function of 3.11 {mu}m diam melamine and 1.51 {mu}m diam silica particles in an argon dc glow discharge dusty plasma are made through the use of stereoscopic particle image velocimetry. These distribution functions are then used to determine the kinetic temperature of the dust component. These measurements show that the kinetic temperature of the dust component is significantly larger than the other plasma components (electrons, ions, and background neutrals)
Derivation and Implementation of Hybrid Fluid/Kinetic Model for Fusion Plasmas
Held, E. D.
2005-08-15
This is a final report for Dr. Eric Held’s Junior Faculty in Plasmas Physics grant entitled, “Derivation and Implementation of Hybrid Fluid/Kinetic Model for Fusion Plasmas”. Progress over the three years and six months of this project included work on analytical and numerical fronts.
Gas Kinetic Study of Magnetic Field Effects on Plasma Plumes
Ebersohn, Frans 1987-
2012-12-07
Plasma flow physics in magnetic nozzles must be clearly understood for optimal design of plasma propulsion devices. Toward that end, in this thesis we: i) perform an extensive literature survey of magnetic nozzle physics, ii) assess the validity...
Benisti, Didier; Morice, Olivier; Gremillet, Laurent; Siminos, Evangelos; Strozzi, David J.
2010-10-15
In this paper, we present our nonlinear kinetic modeling of stimulated Raman scattering in a uniform and collisionless plasma using envelope equations. We recall the derivation of these equations, as well as our theoretical predictions for each of the nonlinear kinetic terms, the precision of which having been carefully checked against Vlasov simulations. We particularly focus here on the numerical resolution of these equations, which requires the additional concept of ''self-optimization'' that we explain, and we describe the envelope code BRAMA that we used. As an application of our modeling, we present one-dimensional BRAMA simulations of stimulated Raman scattering which predict threshold intensities, as well as time scales for Raman growth above threshold, in very good agreement with those inferred from Vlasov simulations. Finally, we discuss the differences between our modeling and other published ones.
The Plasma Interaction Experiment (PIX) description and test program. [electrometers
NASA Technical Reports Server (NTRS)
Ignaczak, L. R.; Haley, F. A.; Domino, E. J.; Culp, D. H.; Shaker, F. J.
1978-01-01
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 plasma densities encountered during available telemetry coverage periods are deemed sufficient to determine first order interactions between the space plasma environment and the biased experimental surfaces. The specific objectives of the PIX flight experiment are to measure the plasma coupling current and the negative voltage breakdown characteristics of a solar array segment and a gold plated steel disk. Measurements will be made over a range of surface voltages up to plus or minus kilovolt. The orbital environment will provide a range of plasma densities. The experimental surfaces will be voltage biased in a preprogrammed step sequence to optimize the data returned for each plasma region and for the available telemetry coverage.
Fully kinetic simulations of dense plasma focus Z-pinch devices.
Schmidt, A; Tang, V; Welch, D
2012-11-16
Dense plasma focus 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 (~10(7)) and high-energy (MeV) beams for the first time. We compare our fluid, hybrid (kinetic ions and fluid electrons), and fully kinetic simulations. Fluid simulations predict no neutrons and do not allow for nonthermal ions, while hybrid simulations underpredict neutron yield by ~100x and exhibit an ion tail that does not exceed 200 keV. Only fully kinetic simulations predict MeV-energy ions and experimental neutron yields. A frequency analysis in a fully kinetic simulation shows plasma fluctuations near the lower hybrid frequency, possibly implicating lower hybrid drift instability as a contributor to anomalous resistivity in the plasma. PMID:23215497
Approximate analytical description of the underdense short plasma lens
Amatuni, A.Ts.
1996-05-01
The perturbative approach for describing the underdense plasma-ultrarelativistic electron bunch system is developed, using the ratio n{sup o}{sub b} as a small parameter (n{sub b}-bunch, n{sub o} plasma electron densities). Focusing of the electron bunch emerged in the first approximation of the perturbative procedure as a result of the plasma electrons redistribution. Focusing gradient and strength for ultrarelativistic, flat, uniform and short bunch are obtained and compared with the previous results.
Plasma kinetics of sup 125 I beta endorphin turnover in lean and obese Zucker rats
Rodd, D.; Caston, A.L.; Green M.H.; Farrell, P.A. )
1990-02-26
Plasma clearance kinetics for Beta Endorphin (BEP) are not well-defined and no definitive data exist for lean versus obese animals. To determine such kinetic parameters, a bolus of {sup 125}I BEP (1{mu}Ci/kg) was infused into awake lean(L) and obese(O) Zucker rats. Arterial blood samples were withdrawn initially at 20 seconds intervals and less frequently as a 3-hour experimental period progressed. Donor rat blood was infused (venous catheter) to replace withdrawn blood. At 180 minutes approximately 10% of the initial dose remained in the plasma. Clearance kinetics for {sup 125}I BEP were analyzed by compartmental analysis. A 3-component equation (i.e., 3 compartment model) provided the best fit for both L and O groups. Plasma transit times were very rapid; however, plasma fractional catabolic rate was low. Plasma mean residence time was similar for both groups (50 minutes) as was recycle time. These data suggest that BEP kinetics are similar in L and O rats, and that this peptide may undergo extensive recycling into and out of the plasma compartment. The identity of the other two compartments requires further investigation.
A kinetic description of the dissipative quasi-parallel solar wind termination shock
NASA Astrophysics Data System (ADS)
Verscharen, D.; Fahr, H.-J.
2008-08-01
Context: As a special case of astrophysical MHD shock waves, the solar wind termination shock is typically treated using the MHD jump conditions as they have been determined by Rankine and Hugoniot. A kinetic analysis becomes necessary for both a more detailed view of the governing processes and a deeper understanding of the plasma behaviour. Aims: In the case of a parallel shock, only an electric field can be considered as the main process decelerating the solar wind ions. This field leads to a strong acceleration for the electrons due to the other sign of their charge and the much lower mass of the electrons than of the ions. This situation enforces a two-stream instability, which is considered to be compensated by wave-particle interactions with electrostatic plasma waves. Methods: The kinetic approach leads to an equation in Fokker-Planck form, which can be solved by using It?'s calculus for stochastic differential equations. Results: These two processes (electric field and wave-particle interaction) yield a decelerated subsonic solar wind on the downstream side of the termination shock, showing some new features in the ion distribution function, such as a double-hump structure and a comparatively large number of reflected ions. Within these considerations, we estimate of the spatial size of the shock region.
Nonstationary kinetic theory of ion transport in plasma with small perturbations
Brantov, A. V. Bychenkov, V. Yu.; Rozmus, W.
2013-05-15
A theory of charged particle transport for small potential perturbations in a fully ionized plasma is developed on the basis of solving a linearized kinetic equation with the Landau collision integral. This theory is free of any constraints on the characteristic time and spatial scales of perturbations. Ion fluxes appropriate for an arbitrary ion-ion collision frequency that can ensure nonlocal space-time transport in the plasma are calculated. The obtained ion transport coefficients are used to calculate the partial contribution of ions to the longitudinal permittivity of collisional plasma. The resulting expression for the plasma permittivity is applicable in the entire range of frequencies and wavenumbers.
KINETIC THEORY OF PLASMA ADIABATIC MAJOR RADIUS COMPRESSION IN TOKAMAKS.
change are obtained for a plasma with high aspect ratio and circular magnetic surfaces. The particle induced loss of alpha particles produced by DT fusion reactions in Tokamak Fusion Test Reactor particle behavior as well as plasma macro parameters (temperature, density, etc.) during the adiabatic R
Limits of the M1 and M2 angular moments models for kinetic plasma physics studies
NASA Astrophysics Data System (ADS)
Guisset, S.; Moreau, J. G.; Nuter, R.; Brull, S.; d' Humières, E.; Dubroca, B.; Tikhonchuk, V. T.
2015-08-01
Angular moments closures are widely used in numerical solutions of kinetic equations. While in the strongly collisional limit they provide a good approximation of the full kinetic equation, their validity domain in the weakly collisional limit is unknown. This work is devoted to defining the validity domain of the M1 model and its extensions, the two populations M1 and the M2 angular moments models for the collisionless kinetic physics applications. Three typical kinetic plasma effects are considered, which are the charged particle beams interaction, the Landau damping and the electromagnetic wave absorption in an overdense semi-infinite plasma. For each case, a perturbative analysis is performed and the dispersion relation is established using the moments models. These relations are compared with those computed by considering the Vlasov equation. The validity limits of each model are demonstrated.
Ion-kinetic-energy measurements and energy balance in a Z-pinch plasma at stagnation.
Kroupp, E; Osin, D; Starobinets, A; Fisher, V; Bernshtam, V; Maron, Y; Uschmann, I; Förster, E; Fisher, A; Deeney, C
2007-03-16
The ion-kinetic energy throughout K emission in a stagnating plasma was determined from the Doppler contribution to the shapes of optically thin lines. X-ray spectroscopy with a remarkably high spectral resolution, together with simultaneous imaging along the pinch, was employed. Over the emission period, a drop of the ion-kinetic energy down to the electron thermal energy was seen. Axially resolved time-dependent electron-density measurements and absolute intensities of line and continuum allowed for investigating, for the first time, each segment of the pinch, the balance between the ion-kinetic energy at the stagnating plasma, and the total radiation emitted. Within the experimental uncertainties, the ion-kinetic energy is shown to account for the total radiation. PMID:17501061
Existence of weakly damped kinetic Alfven eigenmodes in reversed shear tokamak plasmas
Gorelenkov, N. N.
2008-11-15
A kinetic theory of weakly damped Alfven eigenmode solutions strongly interacting with the continuum is developed for tokamak plasmas with reversed magnetic shear. It is shown that finite Larmor radius (FLR) effects are required for global eigenmode solutions. FLR effects induce multiple kinetic subeigenmodes and collisionless radiative damping. The theory explains the existence of experimentally observed Alfvenic instabilities with frequencies sweeping down and reaching their minimum (bottom)
Implicit Methods for the Magnetohydrodynamic Description of Magnetically Confined Plasmas
S.C. Jardin
2010-09-28
Implicit algorithms are essential for predicting the slow growth and saturation of global instabilities in today’s magnetically confined fusion plasma experiments. Present day algorithms for obtaining implicit solutions to the magnetohydrodynamic (MHD) equations for highly magnetized plasma have their roots in algorithms used in the 1960s and 1970s. However, today’s computers and modern linear and non?linear solver techniques make practical much more comprehensive implicit algorithms than were previously possible. Combining these advanced implicit algorithms with highly accurate spatial representations of the vector fields describing the plasma flow and magnetic fields and with improved methods of calculating anisotropic thermal conduction now makes possible simulations of fusion experiments using realistic values of plasma parameters and actual configuration geometry.
Consistent holographic description of boost-invariant plasma
Michal P. Heller; R. Loganayagam; Michal Spalinski; Piotr Surowka; Samuel E. Vazquez
2009-02-26
Prior attempts to construct the gravity dual of boost-invariant flow of N=4 supersymmetric Yang-Mills gauge theory plasma suffered from apparent curvature singularities in the late time expansion. This Letter shows how these problems can be resolved by a different choice of expansion parameter. The calculations presented correctly reproduce the plasma energy-momentum tensor within the framework of second order viscous hydrodynamics.
Plasma membrane recovery kinetics of a microfluidic intracellular delivery platform
Poceviciute, Roberta
Intracellular delivery of materials is a challenge in research and therapeutic applications. Physical methods of plasma membrane disruption have recently emerged as an approach to facilitate the delivery of a variety of ...
Fully kinetic numerical modeling of a plasma thruster
Szabo, James Joseph, 1969-
2001-01-01
A Hall effect plasma thruster with conductive acceleration channel walls was numerically modeled using 2D3V Particle-in-Cell (PIC) and Monte-Carlo Collision (MCC) methodolo- gies. Electron, ion, and neutral dynamics were ...
Kinetic development of crystallization fronts in complex plasmas
Loss, Daniel
to oscillations in the surface roughness. Crystal growth may take place under a variety of conditions, the most and mechanical properties of the meso- or macroscopic material. Therefore, kinetic measurements (at: they are optically thin, charge-neutral, weakly damped systems, where the dominant component, the microparticles, can
Exact kinetic theory for the instability of an electron beam in a hot magnetized plasma
Timofeev, I. V.; Annenkov, V. V.
2013-09-15
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.
Nonlocal, kinetic stimulated Raman scattering in nonuniform plasmas: Averaged variational approach
Khain, P.; Friedland, L.; Shagalov, A. G.; Wurtele, J. S.
2012-07-15
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{lambda}{sub D}{approx}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.
A first-principles self-consistent model of plasma turbulence and kinetic neutral dynamics in the
Thévenaz, Jacques
-exchange, recombination, and elastic collisional processes. The solution of the neutral kinetic equation is implementedA first-principles self-consistent model of plasma turbulence and kinetic neutral dynamics Plasma Center (SPC), CH-1015 Lausanne, Switzerland E-mail: christoph.wersal@epfl.ch May 2015 Abstract
Excitation of Kinetic Alfvén Waves by Density Striation in Magneto-plasmas
NASA Astrophysics Data System (ADS)
Wu, D. J.; Chen, L.
2013-07-01
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 Alfvén 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.
Numerical description of discharge characteristics of the plasma needle
Brok, W.J.M.; Bowden, M.D.; Dijk, J. van; Mullen, J.J.A.M. van der; Kroesen, G.M.W.
2005-07-01
The plasma needle is a small atmospheric, nonthermal, radio-frequency discharge, generated at the tip of a needle, which can be used for localized disinfection of biological tissues. Although several experiments have characterized various qualities of the plasma needle, discharge characteristics and electrical properties are still not well known. In order to provide initial estimates on electrical properties and quantities such as particle densities, we employed a two-dimensional, time-dependent fluid model to describe the plasma needle. In this model the balance equation is solved in the drift-diffusion approach for various species and the electron energy, as well as Poisson's equation. We found that the plasma production occurs in the sheath region and results in a steady flux of reactive species outwards. Even at small (<0.1%) admixtures of N{sub 2} to the He background, N{sub 2}{sup +} is the dominant ion. The electron density is typically 10{sup 11} cm{sup -3} and the dissipated power is in the order of 10 mW. These results are consistent with the experimental data available and can give direction to the practical development of the plasma needle.
Zonca, Fulvio
Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas Z. Qiu, L. Chen://scitation.aip.org/termsconditions. Downloaded to IP: 192.107.52.30 On: Thu, 06 Feb 2014 15:42:45 #12;Excitation of kinetic geodesic acoustic) Effects of system nonuniformities and kinetic dispersiveness on the spontaneous excitation of Geodesic
Macroscopic Lagrangian description of warm plasmas. II Nonlinear wave interactions
NASA Technical Reports Server (NTRS)
Kim, H.; Crawford, F. W.
1983-01-01
A macroscopic Lagrangian is simplified to the adiabatic limit and expanded about equilibrium, to third order in perturbation, for three illustrative cases: one-dimensional compression parallel to the static magnetic field, two-dimensional compression perpendicular to the static magnetic field, and three-dimensional compression. As examples of the averaged-Lagrangian method applied to nonlinear wave interactions, coupling coefficients are derived for interactions between two electron plasma waves and an ion acoustic wave, and between an ordinary wave, an electron plasma wave, and an ion acoustic wave.
NASA Astrophysics Data System (ADS)
Farley, Donald
2010-05-01
In 1958 W. E. Gordon first suggested that huge radars could probe the ionosphere via scattering from independent electrons, even though the radar cross section of a single electron is only 10-28 m2. This suggestion quickly led to the construction of two enormous radars in the early 1960s, one near Lima, Peru, and one near Arecibo, Puerto Rico. It soon became apparent that the theory of this scatter was more complicated than originally envisaged by Gordon. Although the new theory was more complicated, it was much richer: by measuring the detailed shape of the Doppler frequency spectrum (or alternatively the signal autocorrelation function, the ACF), a radar researcher could determine many, if not most, of the parameters of interest of the plasma. There is now a substantial network of major radar facilities scattered from the magnetic equator (Peru) to the high arctic latitudes (Svalbard and Resolute Bay), all doing important ionospheric research. The history of what is now called Incoherent Scatter (even though it is not truly incoherent) is fascinating, and I will touch on a few highlights. The sophisticated radar and data processing techniques that have been developed are also impressive. In this talk, however, I want to focus mainly on the details of the theory and on how the radar observations have confirmed the predictions of classical linear plasma kinetic theory to an amazingly high degree of precision, far higher than has any other technique that I am aware of. The theory can be, and has been, developed from two very different points of view. One starts with 'dressed particles,' or Coulomb 'clouds' around ions and electrons moving with a Maxwellian velocity distribution; the second starts by considering all the charged particles to be made up of a spectrum of density plane waves and then invokes a generalized version of the Nyquist Noise Theorem to calculate the thermal amplitudes of the waves. Both approaches give exactly the same results, results that allow us to predict exactly the scattered power and Doppler spectrum for any given set of plasma parameters (e.g., electron and ion temperatures, ionic composition, mean drifts and currents, the geomagnetic field, and particle collisions). So far, these predictions have not failed, although in recent years we have had to resort to numerical simulations to do a proper calculation of electron Coulomb collisions when the radar beam is pointed very nearly perpendicular to the magnetic field. This is because no analytic way has yet been found to properly apply the Fokker-Planck Coulomb collision model to the scattering process. Of course the theory predicts the spectrum, given all the plasma parameters, when what we really want to do in ionospheric research is the inverse, namely find the parameters, given the radar data. This inverse process can be quite difficult to do optimally if there are too many unknown parameters. Statistical inverse theory can require enormous computing power, but progress is being made.
Solar wind kinetic instabilities at small plasma betas
Ibscher, D. Schlickeiser, R.
2014-02-15
The ordinary perpendicular mode of drifting bi-Maxwellian plasma particle distributions with and without temperature anisotropy can provide aperiodic instabilities. These instabilities occur if the perpendicular thermal energy is much smaller than the streaming energy. This provides instabilities at small parallel plasma betas ?{sub ?}<1 and temperature anisotropies A?
Drift kinetic Alfvén wave in temperature anisotropic plasma
Naim, Hafsa Bashir, M. F.; Department of Physics, G. C. University Lahore, Katchery Road, Lahore 54000 ; Murtaza, G.
2014-03-15
By using the gyrokinetic theory, the kinetic Alfvén waves (KAWs) are discussed to emphasize the drift effects through the density inhomogeneity and the temperature anisotropy on their dispersion characteristics. The dependence of stabilization mechanism of the drift-Alfvén wave instability on the temperature anisotropy is highlighted. The estimate of the growth rate and the threshold condition for a wide range of parameters are also discussed.
Yeung, Man-Chung
KINETICS, CATALYSIS, AND REACTION ENGINEERING Nonthermal Plasma Reactions of Dilute Nitrogen Oxide atom and N2(A) are found to control the conversion of nitrogen oxides and the evolution of byproducts for the conversion of nitrogen oxides,1,2,4-10 sulfur dioxide,11 and volatile organic car- bons.12 Despite its
Modeling of neutral plasma in a divertor in the fluid-kinetic transition1
Karney, Charles
Modeling of neutral plasma in a divertor in the fluid-kinetic transition1 C. F. F. Karney, D. P University, New York, NY 10012-1605 Abstract The neutrals in a tokamak divertor in the so-called "detached ionization front, while the cold neutrals in front of the divertor plate are adequately described by fluid
Symmetry Extensions and Their Physical Reasons in the Kinetic and Hydrodynamic Plasma Models
Volodymyr B. Taranov
2008-01-17
Characteristic examples of continuous symmetries in hydrodynamic plasma theory (partial differential equations) and in kinetic Vlasov-Maxwell models (integro-differential equations) are considered. Possible symmetry extensions conditional and extended symmetries are discussed. Physical reasons for these symmetry extensions are clarified.
Comparisons of dense-plasma-focus kinetic simulations with experimental measurements.
Schmidt, A; Link, A; Welch, D; Ellsworth, J; Falabella, S; Tang, V
2014-06-01
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 and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency. PMID:25019717
Comparisons of dense-plasma-focus kinetic simulations with experimental measurements
Schmidt, A.; Link, A.; Welch, D.; Ellsworth, J.; Falabella, S.; Tang, V.
2014-06-01
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 and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency.
Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling
NASA Astrophysics Data System (ADS)
DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.
2008-02-01
Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.
Localization of linear kinetic Alfvén wave in an inhomogeneous plasma and generation of turbulence
Sharma, R. P.; Goyal, R.; Scime, Earl E.; Dwivedi, N. K.
2014-04-15
This paper presents a model for the propagation of Kinetic Alfvén waves (KAWs) in inhomogeneous plasma when the inhomogeneity is transverse to the background magnetic field. The semi-analytical technique and numerical simulations have been performed to study the KAW dynamics when plasma inhomogeneity is incorporated in the dynamics. The model equations are solved in order to study the localization of KAW and their magnetic power spectrum which indicates the direct transfer of energy from lower to higher wave numbers. The inhomogeneity scale length plays a very important role in the turbulence generation and its level. The relevance of these investigations to space and laboratory plasmas has also been pointed out.
Ehst, D.A.; Hassanein, A.
1996-02-01
Ablation damage to solid targets with high heat flux impulses is generally greater high-energy electron beam heat sources compared to low-energy plasma guns. This sensitivity to incoming particle kinetic energy is explored with computer modelling; a fast-running routine (DESIRE) is developed for initial scoping analysis and is found to be in reasonable agreement with several experiments on graphite and tungsten targets. If tokamak disruptions are characterized by particle energies less than {approximately}1 keV, then we expect plasma guns are a better analogue than electron beams for simulating disruption behavior and testing candidate plasma-facing materials.
Jupiter's magnetosphere: Plasma description from the Ulysses flyby
Bame, S.J.; Barraclough, B.L.; Feldman, W.C.; Gisler, G.R.; Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Thomsen, M.F. ); Goldstein, B.E.; Neugebauer, M. )
1992-09-11
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.
High-order continuum kinetic method for modeling plasma dynamics in phase space
NASA Astrophysics Data System (ADS)
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-01
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,vx,vy) is presented [1]. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volume algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,vr,vz) phase space are presented.
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,vx,vy) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volumemore »algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,vr,vz) phase space are presented.« less
NASA Astrophysics Data System (ADS)
Kubes, P.; Prykarpatsky, A. K.; Zagrodzinski, J.; Prykarpatsky, Y. A.
In this article we will follow the approach developed in articles N.~N.~Bogoliubov, V.~Hr.~Samoilenko, Ukr. Fiz. Zh., 37, 147 (1992); J.~Gibbon, Physica D, 3, 503 (1981) using modern Lie--algebraic and symplectic geometry methods. It is devoted to the description of Boltzman--Vlasov type kinetic equations and some two--dimensional hydrodynamic Benney type flows associated with them. In our case of the cylindrical symmetry taking place at the interrupted magnetic z--pinch in plasma we used intensively the corresponding two--dimensionality of the plasma flow under consideration which made it possible to build a kinetic model of the plasmoid vortex structure with a conserved number of linkages of vortex lines. The latter can be used to explain the observed earlier stability of the plasmoid structure at the magnetic z--pinch.
NASA Astrophysics Data System (ADS)
Liu, Chang; Dodin, Ilya Y.
2015-08-01
The nonlinear frequency shift is derived in a transparent asymptotic form for intense Langmuir waves in general collisionless plasma. The formula describes both fluid and kinetic effects simultaneously. The fluid nonlinearity is expressed, for the first time, through the plasma dielectric function, and the kinetic nonlinearity accounts for both smooth distributions and trapped-particle beams. Various known limiting scalings are reproduced as special cases. The calculation avoids differential equations and can be extended straightforwardly to other nonlinear plasma waves.
Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures
Cremaschini, Claudio; Stuchlík, Zden?k
2014-04-15
The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed.
Alfven continuum deformation by kinetic geodesic effect in rotating tokamak plasmas
Elfimov, A. G.
2010-02-15
Using a quasitoroidal set of coordinates with coaxial circular magnetic surfaces, Vlasov equation is solved for collisionless plasmas in drift approach and a perpendicular dielectric tensor is found for large aspect ratio tokamaks in a low frequency band. Taking into account plasma rotation and charge separation parallel electric field, it is found that an ion geodesic effect deform Alfven wave continuum producing continuum minimum at the rational magnetic surfaces, which depends on the plasma rotation and poloidal mode numbers. In kinetic approach, the ion thermal motion defines the geodesic effect but the mode frequency also depends on electron temperature. A geodesic ion Alfven mode predicted below the continuum minimum has a small Landau damping in plasmas with Maxwell distribution but the plasma rotation may drive instability.
Three-Dimensional Drift Kinetic Response of High-? Plasmas in the DIII-D Tokamak
NASA Astrophysics Data System (ADS)
Wang, Z. R.; Lanctot, M. J.; Liu, Y. Q.; Park, J.-K.; Menard, J. E.
2015-04-01
A quantitative interpretation of the experimentally measured high-pressure plasma response to externally applied three-dimensional (3D) magnetic field perturbations, across the no-wall Troyon ? limit, is achieved. The self-consistent inclusion of the drift kinetic effects in magnetohydrodynamic (MHD) modeling [Y. Q. Liu et al., Phys. Plasmas 15, 112503 (2008)] successfully resolves an outstanding issue of the ideal MHD model, which significantly overpredicts the plasma-induced field amplification near the no-wall limit, as compared to experiments. The model leads to quantitative agreement not only for the measured field amplitude and toroidal phase but also for the measured internal 3D displacement of the plasma. The results can be important to the prediction of the reliable plasma behavior in advanced fusion devices, such as ITER [K. Ikeda, Nucl. Fusion 47, S1 (2007)].
Kinetic theory of a two-dimensional magnetized plasma. II - Balescu-Lenard limit.
NASA Technical Reports Server (NTRS)
Vahala, G.
1972-01-01
The kinetic theory of a two-dimensional one-species plasma in a uniform dc magnetic field is investigated in the small plasma parameter limit. The plasma consists of charged rods interacting through the logarithmic Coulomb potential. Vahala and Montgomery earlier (1971) derived a Fokker-Planck equation for this system, but it contained a divergent integral, which had to be cut off on physical grounds. This cutoff is compared to the standard cutoff introduced in the two-dimensional unmagnetized Fokker-Planck equation. In the small plasma parameter limit, it is shown that the Balescu-Lenard collision term is zero in the long time average limit if only two-body interactions are considered. The energy transfer from a test particle to an equilibrium plasma is discussed and is also shown to be zero in the long time average limit. This supports the unexpected result of zero Balescu-Lenard collision term.
Kinetic Alfven solitary waves in a magnetized plasma with superthermal electrons
NASA Astrophysics Data System (ADS)
Panwar, A.; Ryu, C. M.; Bains, A. S.
2015-09-01
A study of the ion Larmor radius effects on the solitary kinetic Alfven waves (SKAWs) in a magnetized plasma with superthermal electrons is presented by employing the kinetic theory. The linear dispersion relation of SKAW is shown to depend on the superthermal parameter ?, ion to electron temperature ratio, and the angle of wave propagation. Using the Sagdeev potential approach, the energy balance equation has been derived to study the dynamics of SKAWs. The effects of various plasma parameters are investigated for the propagation of SKAWs. It is shown that only compressive solitons can exist and in the Maxwellian limit our results are in good agreement with previous studies. Further, the characteristics of small amplitude SKAWs are investigated. Present study could be useful for the understanding of SKAWs in a low ? plasma in astrophysical environment, where particle distributions are superthermal in nature.
Plasma-Resistivity-Induced Strong Damping of the Kinetic Resistive Wall Mode
NASA Astrophysics Data System (ADS)
He, Yuling; Liu, Yueqiang; Liu, Yue; Hao, Guangzhou; Wang, Aike
2014-10-01
An energy-principle-based dispersion relation is derived for the resistive wall mode, which incorporates both the drift kinetic resonance between the mode and energetic particles and the resistive layer physics. The equivalence between the energy-principle approach and the resistive layer matching approach is first demonstrated for the resistive plasma resistive wall mode. As a key new result, it is found that the resistive wall mode, coupled to the favorable average curvature stabilization inside the resistive layer (as well as the toroidal plasma flow), can be substantially more stable than that predicted by drift kinetic theory with fast ion stabilization, but with the ideal fluid assumption. Since the layer stabilization becomes stronger with decreasing plasma resistivity, this regime is favorable for reactor scale, high-temperature fusion devices.
Kinetic shear Alfvén instability in the presence of impurity ions in tokamak plasmas
Lu, Gaimin; Shen, Y.; Xie, T.; He, Zhixiong; He, Hongda; Qi, Longyu; Cui, Shaoyan
2013-10-15
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.
Finite amplitude solitary structures of coupled kinetic Alfven-acoustic waves in dense plasmas
NASA Astrophysics Data System (ADS)
Sabeen, A.; Shah, H. A.; Masood, W.; Qureshi, M. N. S.
2015-02-01
In this paper, we have investigated the nonlinear propagating coupled Kinetic Alfven-acoustic waves in a low beta degenerate quantum plasma in the presence of trapped Fermi electrons using the quantum hydrodynamic (QHD) model. By using the two potential theory and the Sagdeev potential approach, we have investigated the formation of solitary structures for coupled kinetic Alfven-acoustic waves in the presence of quantum mechanically trapped electrons. We have shown that there are regions of propagation and non-propagation for such solitary structures. We have also highlighted the differences between the classical and quantum mechanically trapped electrons. Interestingly, it has been found that the nature of the nonlinearity for the quantum mechanically trapped electrons is different from its classical counterpart. The results presented here may have applications in white dwarf asteroseismology as well as next generation laser-plasma experiments where low beta plasma condition is met.
Test-particle method in kinetic theory of a plasma.
NASA Technical Reports Server (NTRS)
Matsuda, K.
1971-01-01
The introduction of a test particle into a system is considered. The system may be described by the Born-Bogoliubov-Green-Kirkwood-Yvon hierarchy. The field particles form a cloud which surrounds the test particle. The cloud is described by a conditional probability function which satisfies a certain equation. A generalization of the superposition principle reported by Rostoker (1964) to higher order correlation functions is discussed. Kinetic equations with the generalized Lenard-Balescu term are obtained, taking into account also diffusion by waves. The characteristics regarding the absorption or emission of waves by particles can be calculated.
Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics
Alexandrov, A. L. Schweigert, I. V.; Ariskin, D. A.
2013-04-15
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.
Kinetic Alfven wave in the presence of kappa distribution function in plasma sheet boundary layer
NASA Astrophysics Data System (ADS)
Shrivastava, G.; Shrivastava, J.; Ahirwar, G.
2015-07-01
The particle aspect approach is adopted to investigate the trajectories of charged particles in the electromagnetic field of kinetic Alfven wave. Expressions are found for the dispersion relation, damping/growth rate and associated currents in the presence of kappa distribution function. Kinetic effect of electrons and ions are included to study kinetic Alfven wave because both are important in the transition region. It is found that the ratio ? of electron thermal energy density to magnetic field energy density and the ratio of ion to electron thermal temperature (Ti/Te), and kappa distribution function affect the dispersion relation, damping/growth rate and associated currents in both cases(warm and cold electron limit).The treatment of kinetic Alfven wave instability is based on assumption that the plasma consist of resonant and non resonant particles. The resonant particles participate in an energy exchange process, whereas the non resonant particles support the oscillatory motion of the wave.
The Fluid-Kinetic Particle-in-Cell Solver for Plasma Simulations
Markidis, Stefano; Lapenta, Giovanni; Ronnmark, Kjell; Hamrin, Maria; Meliani, Zakaria; Laure, Erwin
2013-01-01
A new 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 solver has been implemented in a three-dimensional electromagnetic code, and tested against the ion cyclotron resonance and magnetic reconnection problems. The new method is a promising approach for coupling fluid and kinetic methods in a unified framework.
Ion Kinetic Properties in Mercury's Pre-Midnight Plasma Sheet
NASA Technical Reports Server (NTRS)
Gershman, Daniel J.; Slavin, James A.; Raines, Jim M.; Zurbuchen, Thomas H.; Anderson, Brian J.; Korth, Haje; Baker, Daniel N.; Solomon, Sean C.
2014-01-01
With data from the Fast Imaging Plasma Spectrometer sensor on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, we demonstrate that the average distributions for both solar wind and planetary ions in Mercury's pre-midnight plasma sheet are well-described by hot Maxwell-Boltzmann distributions. Temperatures and densities of the H(+)-dominated plasma sheet, in the ranges is approx. 1-10 cm(exp -3) and is approx. 5-30MK, respectively, maintain thermal pressures of is approx.1 nPa. The dominant planetary ion, Na(+), has number densities about 10% that of H(+). Solar wind ions retain near-solar-wind abundances with respect to H(+) and exhibit mass-proportional ion temperatures, indicative of a reconnection-dominated heating in the magnetosphere. Conversely, planetary ion species are accelerated to similar average energies greater by a factor of is approx. 1.5 than that of H(+). This energization is suggestive of acceleration in an electric potential, consistent with the presence of a strong centrifugal acceleration process in Mercury's magnetosphere.
Economou, Demetre J.
. Kolobov Plasma Processing Laboratory, Department of Chemical Engineering, University of Houston, Houston 95054 D. J. Economou Plasma Processing Laboratory, Department of Chemical Engineering, UniversityElectron kinetics and non-Joule heating in near-collisionless inductively coupled plasmas V. I
Tarvainen, O. Laulainen, J.; Komppula, J.; Kronholm, R.; Kalvas, T.; Koivisto, H.; Izotov, I.; Mansfeld, D.; Skalyga, V.
2015-02-15
Electron cyclotron resonance ion source (ECRIS) plasmas are prone to kinetic instabilities due to anisotropy of the electron energy distribution function stemming from the resonant nature of the electron heating process. Electron cyclotron plasma instabilities are related to non-linear interaction between plasma waves and energetic electrons resulting to strong microwave emission and a burst of energetic electrons escaping the plasma, and explain the periodic oscillations of the extracted beam currents observed in several laboratories. It is demonstrated with a minimum-B 14 GHz ECRIS operating on helium, oxygen, and argon plasmas that kinetic instabilities restrict the parameter space available for the optimization of high charge state ion currents. The most critical parameter in terms of plasma stability is the strength of the solenoid magnetic field. It is demonstrated that due to the instabilities the optimum B{sub min}-field in single frequency heating mode is often ?0.8B{sub ECR}, which is the value suggested by the semiempirical scaling laws guiding the design of modern ECRISs. It is argued that the effect can be attributed not only to the absolute magnitude of the magnetic field but also to the variation of the average magnetic field gradient on the resonance surface.
Dust kinetic Alfvén solitary and rogue waves in a superthermal dusty plasma
NASA Astrophysics Data System (ADS)
Saini, N. S.; Singh, Manpreet; Bains, A. S.
2015-11-01
Dust kinetic Alfvén solitary waves (DKASWs) have been examined in a low-? dusty plasma comprising of negatively charged dust grains, superthermal electrons, and ions. A nonlinear Korteweg-de Vries (KdV) equation has been derived using the reductive perturbation method. The combined effects of superthermality of charged particles (via ?), plasma ?, obliqueness of propagation (?), and dust concentration (via f) on the shape and size of the DKASWs have been examined. Only negative potential (rarefactive) structures are observed. Further, characteristics of dust kinetic Alfvén rogue waves (DKARWs), by deriving the non-linear Schrödinger equation (NLSE) from the KdV equation, are studied. Rational solutions of NLSE show that rogue wave envelopes are supported by this plasma model. It is observed that the influence of various plasma parameters (superthermality, plasma ?, obliqueness, and dust concentration) on the characteristics of the DKARWs is very significant. This fundamental study may be helpful in understanding the formation of coherent nonlinear structures in space and astrophysical plasma environments where superthermal particles are present.
Orszag Tang vortex-Kinetic study of a turbulent plasma
NASA Astrophysics Data System (ADS)
Parashar, T. N.; Servidio, S.; Shay, M. A.; Matthaeus, W. H.; Cassak, P. A.
2010-03-01
Kinetic evolution of the Orszag-Tang vortex is studied using collisionless hybrid simulations based on particle in cell ions and fluid electrons. In magnetohydrodynamics (MHD) this configuration leads rapidly to broadband turbulence. An earlier study [1] estimated the dissipation in the system. A comparison of MHD & hybrid simulations showed similar behavior at large scales but substantial differences at small scales. The hybrid magnetic energy spectrum shows a break at the scale where Hall term in the Ohm's law becomes important. The protons heat perpendicularly and most of the energy is dissipated through magnetic interactions. Here, the space time structure of the system is studied using frequency-wavenumber (k-?) decomposition. No clear resonances appear, ruling out the cyclotron resonances as a likely candidate for the perpendicular heating. The only distinguishable wave modes present, which constitute a small percentage of total energy, are magnetosonic modes.
Kinetic effects in the transverse filamentation instability of pair plasmas
NASA Astrophysics Data System (ADS)
D'Angelo, M.; Fedeli, L.; Sgattoni, A.; Pegoraro, F.; Macchi, A.
2015-12-01
The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. During the nonlinear stage of the instability, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.
Quantification of Transthyretin Kinetic Stability in Human Plasma Using Subunit Exchange
2015-01-01
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
Plasma radioiron kinetics in man: explanation for the effect of plasma iron concentration.
Skarberg, K; Eng, M; Huebers, H; Marsaglia, G; Finch, C
1978-01-01
The plasma iron turnover was measured in 19 normal subjects. A correlation was found between plasma iron concentration and plasma iron turnover. In addition to the turnover of 55Fe at normal plasma iron concentration (predominantly monoferric transferrin), a second turnover in which the labeled plasma was saturated with iron (to produce predominantly diferric transferrin) was studied with 50Fe. It was demonstrated that diferric transferrin had a greater rate of iron turnover but that the distribution between erythroid and non-erythroid tissues was unchanged. It was concluded that plasma iron turnover is dependent on the monoferric/diferric transferrin ratio in the plasma but that the internal distribution of iron is unaffected. PMID:274740
Kinetics and Statistical Behaviour of Iron Recovery from Red Mud using Plasma Arc Furnace
NASA Astrophysics Data System (ADS)
Rath, Swagat S.; Jayasankar, K.; Satapathy, Bijoy K.; Mishra, Barada K.; Mukherjee, Partha S.
2011-06-01
Study of the recovery of pig iron from dry red mud through plasma smelting has been done. The reductant used was graphite. Various fluxes were used for the formation of slag. The parameters varied were smelting time, basicity and concentration of reductant and fluxes. It was observed that the reduction kinetics improved progressively with the increase of all the variables up to certain level and on further increase the metal recovery decreased. The results were interpreted kinetically and rate determining step was evaluated. Multi Linear Regression Analysis studies were carried out. The variables were subjected to Principal Component Analysis. Four factors could explain 75.4% of the variables.
Description of plasma focus current sheath as the Turner relaxed state of a Hall magnetofluid
Auluck, S. K. H.
2009-12-15
The central mystery of plasma focus research is the two orders-of-magnitude-higher-than-thermal fusion reaction rate and the fact that both the space-resolved neutron spectra and space-resolved reaction proton spectra show features which can be ascribed only to a rotational motion of the center-of-mass of the reacting deuteron population. It has been suggested earlier [S. K. H. Auluck, IEEE Trans. Plasma Sci. 25, 37 (1997)] that this and other experimental observations can be consistently explained in terms of a hypothesis involving rotation of the current carrying plasma annulus behind the imploding gas-dynamic shock. Such rotation (more generally, mass flow) is an in-built feature of relaxed state of a two-fluid plasma [R. N. Sudan, Phys. Rev. Lett. 42, 1277 (1979)]. Relaxation in the 'Hall magnetofluid' approximation, in which the generalized Ohm's law includes the Hall effect term and the magnetic convection term but omits the contributions to the electric field from resistive dissipation, electron pressure gradient, thermoelectric effect, electron inertia, etc., has been extensively studied by many authors. In the present paper, Turner's [IEEE Trans. Plasma Sci. PS-14, 849 (1986)] degenerate solution for the relaxed state of the Hall magnetohydrodynamic plasma has been adapted to the case of an infinitely long annular current carrying plasma, a tractable idealization of the current sheath of a plasma focus. The resulting model is consistent with experimental values of ion kinetic energy and observation of predominantly radially directed neutron emission in good shots.
Description of plasma focus current sheath as the Turner relaxed state of a Hall magnetofluid
NASA Astrophysics Data System (ADS)
Auluck, S. K. H.
2009-12-01
The central mystery of plasma focus research is the two orders-of-magnitude-higher-than-thermal fusion reaction rate and the fact that both the space-resolved neutron spectra and space-resolved reaction proton spectra show features which can be ascribed only to a rotational motion of the center-of-mass of the reacting deuteron population. It has been suggested earlier [S. K. H. Auluck, IEEE Trans. Plasma Sci. 25, 37 (1997)] that this and other experimental observations can be consistently explained in terms of a hypothesis involving rotation of the current carrying plasma annulus behind the imploding gas-dynamic shock. Such rotation (more generally, mass flow) is an in-built feature of relaxed state of a two-fluid plasma [R. N. Sudan, Phys. Rev. Lett. 42, 1277 (1979)]. Relaxation in the "Hall magnetofluid" approximation, in which the generalized Ohm's law includes the Hall effect term and the magnetic convection term but omits the contributions to the electric field from resistive dissipation, electron pressure gradient, thermoelectric effect, electron inertia, etc., has been extensively studied by many authors. In the present paper, Turner's [IEEE Trans. Plasma Sci. PS-14, 849 (1986)] degenerate solution for the relaxed state of the Hall magnetohydrodynamic plasma has been adapted to the case of an infinitely long annular current carrying plasma, a tractable idealization of the current sheath of a plasma focus. The resulting model is consistent with experimental values of ion kinetic energy and observation of predominantly radially directed neutron emission in good shots.
Measurement of the Kinetic Dust Temperature of a Weakly-Coupled Dusty Plasma
Williams, Jeremiah; Thomas, Edward Jr.
2005-10-31
Over the past 5 years, two-dimensional particle image velocimetry techniques have been used to obtain detailed measurements of microparticle transport in dusty plasma. Recently, the Auburn Plasma Sciences Laboratory has extended these techniques to a three-dimensional velocity vector measurement using stereoscopic particle image velocimetry (stereo-PIV). In this paper, we discuss the use of the stereo-PIV technique for determining the velocity space distribution function of the microparticle component of a dc glow discharge dusty plasma. These distribution functions are then used to make measurements of the kinetic temperature of the dust component. Preliminary results show that the temperature of the dust component is significantly larger than the other plasma components (electrons, ions and background neutrals)
Kinetics of the Raman Instability in Laser Plasma
NASA Astrophysics Data System (ADS)
Mašek, M.; Rohlena, K.
2005-08-01
The phase-space evolution in a non-relativistic and homogeneous laser plasma in the presence of the stimulated Raman scattering is studied. Transform method is used for a solution of the set of partial differential equations which consists of the Vlasov equation and of the full set of Maxwell equations in a 1D model. Numerical instability of the Fourier-Hermite representation is described and discussed. To overcome numerical instabilities during the simulation, a simplified Fokker-Planck collision term is employed. In the collisionless case the solution is pushed to the practicable limit and the initial phase of particle trapping and acceleration in the potential wells of the electrostatic wave accompanying the Raman backscattered wave was recorded. Also the growth of the electrostatic partner of the Raman forward scattered wave was observed.
Kinetic theory of a two-dimensional magnetized plasma.
NASA Technical Reports Server (NTRS)
Vahala, G.; Montgomery, D.
1971-01-01
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.
A Hybrid Fluid-Kinetic Theory for Plasma Physics
Tor Fla
2001-10-30
We parameterize the phase space density by time dependent diffeomorphic, Poisson preserving transformations on phase space acting on a reference density solution. We can look at these as transformations which fix time on the extended space of phase space and time. In this formulation the Vlasov equation is replaced by a constraint equation for the above maps. The new equations are formulated in terms of hamiltonian generators of one parameter families of diffeomorphic, Poisson preserving maps e.g. generators with respect to time or a perturbation parameter. We also show that it is possible to parameterize the space of solutions of the Vlasov equation by composition of maps subject to certain compatibility conditions on the generators. By using this composition principle we show how to formulate new equations for a hybrid fluid kinetic theory. This is done by observing that a certain subgroup of the group of phase space maps with generators which are linear in momentum correspond to the group of diffeomorphic maps parameterizing the continuity equation in fluid theory.
Akatsuka, Hiroshi
2009-04-15
Population densities of excited states of argon atoms are theoretically examined for ionizing argon plasma in a state of nonequilibrium under atmospheric pressure from the viewpoint of elementary processes with collisional radiative model. The dependence of excited state populations on the electron and gas temperatures is discussed. Two electron density regimes are found, which are distinguished by the population and depopulation mechanisms for the excited states in problem. When the electron impact excitation frequency for the population or depopulation is lower than the atomic impact one, the electron density of the plasma is considered as low to estimate the population and depopulation processes. Some remarkable characteristics of population and depopulation mechanisms are found for the low electron density atmospheric plasma, where thermal relaxation by atomic collisions becomes the predominant process within the group of close-energy states in the ionizing plasma of atmospheric pressure, and the excitation temperature is almost the same as the gas temperature. In addition to the collisional relaxation by argon atoms, electron impact excitation from the ground state is also an essential population mechanism. The ratios of population density of the levels pairs, between which exists a large energy gap, include information on the electron collisional kinetics. For high electron density, the effect of atomic collisional relaxation becomes weak. For this case, the excitation mechanism is explained as electron impact ladderlike excitation similar to low-pressure ionizing plasma, since the electron collision becomes the dominant process for the population and depopulation kinetics.
Numerical solution of the time-dependent kinetic equation for electrons in magnetized plasma
NASA Technical Reports Server (NTRS)
Hamilton, Russell J.; Lu, Edward T.; Petrosian, Vahe
1990-01-01
A numerical solution is developed for the time-dependent kinetic equation describing the evolution of arbitrary distributions of electrons injected into a magnetized plasma. Included in the equation are pitch-angle scattering and energy loss because of Coulomb collisions and magnetic mirroring. The numerical code can be easily modified to include other scattering or radiation terms. The numerical results are shown to agree well with known analytic solutions for various simplified configurations such as homogeneous injection in a homogeneous plasma, electron beams moving with small pitch angle with respect to the magnetic field, and injection into a magnetic trap.
Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas
Hussain, Azhar; Stefan, Martin; Brodin, Gert
2014-03-15
We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.
Charge exchange in fluid description of partially ionized plasmas
Vranjes, J; Luna, M
2015-01-01
The effects of charge exchange on waves propagating in weakly ionized plasmas are discussed. It is shown that for low-frequency processes, ions and neutrals should be treated as a single fluid with some effective charge on all of them. We have derived a new momentum equation which should be used in such an environment. As a result, the low-frequency magnetic waves can propagate even if particles are not magnetized, which is entirely due to the charge exchange and the fact that it is not possible to separate particles into two different populations as charged and neutral species. So there can be no friction force between ions and neutrals in the usual sense. The mean force per particle is proportional to the ionization ratio $n_i/(n_i+ n_n)$. Regarding the application of the theory to the Alfven wave propagation in the lower solar atmosphere, the results predict that the plane of displacement of the fluid must change by 90 degrees when an Alfven wave propagates from the area where particles are un-magnetized (...
NASA Astrophysics Data System (ADS)
Karengin, A. A.; Karengin, A. G.; Vlasov, V. A.
2015-09-01
A kinetic model of droplet evaporation in an air-plasma flow is developed. Patterns of the influence of the initial air-plasma flow and droplet parameters and of the initial mass ratio of liquid and gaseous phases on the evaporation kinetics of droplets dispersed in aqueous-organic compositions in the air-plasma flow are established. It is shown that for aqueous-organic compositions having the adiabatic combustion temperature no less than 1200°C, the stage of solvent (water) evaporation is the limiting stage of the whole process in the air-plasma flow.
Geodesic acoustic mode in anisotropic plasmas using double adiabatic model and gyro-kinetic equation
Ren, Haijun; Cao, Jintao
2014-12-15
Geodesic acoustic mode in anisotropic tokamak plasmas is theoretically analyzed by using double adiabatic model and gyro-kinetic equation. The bi-Maxwellian distribution function for guiding-center ions is assumed to obtain a self-consistent form, yielding pressures satisfying the magnetohydrodynamic (MHD) anisotropic equilibrium condition. The double adiabatic model gives the dispersion relation of geodesic acoustic mode (GAM), which agrees well with the one derived from gyro-kinetic equation. The GAM frequency increases with the ratio of pressures, p{sub ?}/p{sub ?}, and the Landau damping rate is dramatically decreased by p{sub ?}/p{sub ?}. MHD result shows a low-frequency zonal flow existing for all p{sub ?}/p{sub ?}, while according to the kinetic dispersion relation, no low-frequency branch exists for p{sub ?}/p{sub ?}? 2.
Von Kármán energy decay and heating of protons and electrons in a kinetic turbulent plasma.
Wu, P; Wan, M; Matthaeus, W H; Shay, M A; Swisdak, M
2013-09-20
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
Fokker–Planck kinetic modeling of suprathermal ?-particles in a fusion plasma
Peigney, B.E.
2014-12-01
We present an ion kinetic model describing the transport of suprathermal ?-particles in inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products (?-particles) at a kinetic level. The model assumes spherical symmetry in configuration space and axial symmetry in velocity space around the mean flow velocity. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal ?-particles and the thermal bulk of the imploding plasma. This method provides an accurate numerical treatment of energy deposition and transport processes involving suprathermal particles. The numerical tools presented here are then validated against known analytical results. This enables us to investigate the potential role of ion kinetic effects on the physics of ignition and thermonuclear burn in inertial confinement fusion schemes.
Kolobov, Vladimir; Arslanbekov, Robert; Frolova, Anna
2014-12-09
The paper describes an Adaptive Mesh in Phase Space (AMPS) technique for solving kinetic equations with deterministic mesh-based methods. The AMPS technique allows automatic generation of adaptive Cartesian mesh in both physical and velocity spaces using a Tree-of-Trees data structure. We illustrate advantages of AMPS for simulations of rarefied gas dynamics and electron kinetics on low temperature plasmas. In particular, we consider formation of the velocity distribution functions in hypersonic flows, particle kinetics near oscillating boundaries, and electron kinetics in a radio-frequency sheath. AMPS provide substantial savings in computational cost and increased efficiency of the mesh-based kinetic solvers.
Kinetic plasma processes occurring in the outer plasmasphere
NASA Technical Reports Server (NTRS)
Wilson, Gordon R.
1992-01-01
One area of data analysis work that was begun under this contract is the fitting of the perpendicular velocity distributions of equatorially trapped ions with a Kappa function. This type of characterization of the trapped ions will be very useful for comparison with velocity distributions produced by the model. A second area of data analysis is to study data from consecutive passes when DE 1's apogee was near the magnetic equator and the spacecraft was often skimming along nearly the same L shell. In 1982 three such periods occurred in May, June, and July. For these consecutive events we have Kp histories, density measurements from a number of sources (Whistler data, DE SFR, ISEE SFR) and consecutive samples of ion pitch angle distributions along field lines. It is clear from this data how the pitch angle distributions evolve during a flux tube refilling event. Our modeling of the flow of plasma along closed field lines is following two basic tracks. The first is a study of the basic refilling process without the effect of wave-particle heating near the equator or the effect of large or abrupt field-aligned electric potential drops. This model includes the effects of Coulomb self-collisions and collisions with the O+ ions in the topside ionosphere. The second track is a study of the effects of wave produced pitch-angle scattering and perpendicular heating occurring near the magnetic equator, in connection with the development of large potential drops that result from electron heating and the development of density gradients.
Inertial-range kinetic turbulence in pressure-anisotropic astrophysical plasmas
NASA Astrophysics Data System (ADS)
Kunz, M. W.; Schekochihin, A. A.; Chen, C. H. K.; Abel, I. G.; Cowley, S. C.
2015-10-01
> A theoretical framework for low-frequency electromagnetic (drift-)kinetic turbulence in a collisionless, multi-species plasma is presented. The result generalises reduced magnetohydrodynamics (RMHD) and kinetic RMHD (Schekochihin et al., Astrophys. J. Suppl. Ser., vol. 182, 2009, pp. 310-377) to the case where the mean distribution function of the plasma is pressure-anisotropic and different ion species are allowed to drift with respect to each other - a situation routinely encountered in the solar wind and presumably ubiquitous in hot dilute astrophysical plasmas such as the intracluster medium. Two main objectives are achieved. First, in a non-Maxwellian plasma, the relationships between fluctuating fields (e.g. the Alfvén ratio) are order-unity modified compared to the more commonly considered Maxwellian case, and so a quantitative theory is developed to support quantitative measurements now possible in the solar wind. Beyond these order-unity corrections, the main physical feature of low-frequency plasma turbulence survives the generalisation to non-Maxwellian distributions: Alfvénic and compressive fluctuations are energetically decoupled, with the latter passively advected by the former; the Alfvénic cascade is fluid, satisfying RMHD equations (with the Alfvén speed modified by pressure anisotropy and species drifts), whereas the compressive cascade is kinetic and subject to collisionless damping (and for a bi-Maxwellian plasma splits into three independent collisionless cascades). Secondly, the organising principle of this turbulence is elucidated in the form of a conservation law for the appropriately generalised kinetic free energy. It is shown that non-Maxwellian features in the distribution function reduce the rate of phase mixing and the efficacy of magnetic stresses, and that these changes influence the partitioning of free energy amongst the various cascade channels. As the firehose or mirror instability thresholds are approached, the dynamics of the plasma are modified so as to reduce the energetic cost of bending magnetic-field lines or of compressing/rarefying them. Finally, it is shown that this theory can be derived as a long-wavelength limit of non-Maxwellian slab gyrokinetics.
Zharkova, Valentina V.
THE NUMERIC CODE FOR MODELLING NON-STATIONARY KINETIC PROCESSES OF CHARGED PARTICLE BEAMS IN HOT numerical algorithm and C-code is developed for modelling kinetics of charged particle beams in hot plasmas in a presence of external field. How does the work advance the state-of-the-art?: The code gives fast temporal
NASA Astrophysics Data System (ADS)
Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.
2009-05-01
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 Alfvénic 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 Alfvénic 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-Alfvén-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.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.
2009-04-23
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 turbulentmotions 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-fieldstrength 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 KAWenergy 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.
Core Physics and Kinetics Calculations for the Fissioning Plasma Core Reactor
NASA Technical Reports Server (NTRS)
Butler, C.; Albright, D.
2007-01-01
Highly efficient, compact nuclear reactors would provide high specific impulse spacecraft propulsion. This analysis and numerical simulation effort has focused on the technical feasibility issues related to the nuclear design characteristics of a novel reactor design. The Fissioning Plasma Core Reactor (FPCR) is a shockwave-driven gaseous-core nuclear reactor, which uses Magneto Hydrodynamic effects to generate electric power to be used for propulsion. The nuclear design of the system depends on two major calculations: core physics calculations and kinetics calculations. Presently, core physics calculations have concentrated on the use of the MCNP4C code. However, initial results from other codes such as COMBINE/VENTURE and SCALE4a. are also shown. Several significant modifications were made to the ISR-developed QCALC1 kinetics analysis code. These modifications include testing the state of the core materials, an improvement to the calculation of the material properties of the core, the addition of an adiabatic core temperature model and improvement of the first order reactivity correction model. The accuracy of these modifications has been verified, and the accuracy of the point-core kinetics model used by the QCALC1 code has also been validated. Previously calculated kinetics results for the FPCR were described in the ISR report, "QCALC1: A code for FPCR Kinetics Model Feasibility Analysis" dated June 1, 2002.
The LANL atomic kinetics modeling effort and its application to W plasmas
Colgan, James; Abdallah, Joseph; Fontes, Christopher; Zhang, Honglin
2010-12-10
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.
Kinetic Alfv en waves and plasma transport at the magnetopause Jay R. Johnson and C. Z. Cheng
in the lower-hybrid wave frequency range (700 Hz{1 kHz) can lead to signi#12;cant transport in the magnetopauseKinetic Alfv en waves and plasma transport at the magnetopause Jay R. Johnson and C. Z. Cheng Princeton Plasma Physics Laboratory, Princeton, NJ 08543 Abstract Large amplitude compressional type waves
Kinetic Alfv'en waves and plasma transport at the magnetopause Jay R. Johnson and C. Z. Cheng
with frequency in the lowerhybrid wave frequency range (700 Hz--1 kHz) can lead to significant transportKinetic Alfv'en waves and plasma transport at the magnetopause Jay R. Johnson and C. Z. Cheng Princeton Plasma Physics Laboratory, Princeton, NJ 08543 Abstract Large amplitude compressional type waves
Gyrokinetic Electron and Fully Kinetic Ion Particle Simulation of Collisionless Plasma Dynamics
Yu Lin; Xueyi Wang; Liu Chen; Zhihong Lin
2009-08-11
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.
Vlasov Plasma Turbulence in the Solar Wind at Proton Kinetic Scales
NASA Astrophysics Data System (ADS)
Valentini, F.; Servidio, S.; Matthaeus, W. H.; Osman, K.; Perrone, D.; Califano, F.; Veltri, P.
2014-12-01
Solar-wind heating through turbulent dissipation at kinetic wavelengths represents one of the most studied and challenging problems in the field of space plasma physics. In this work, kinetic effects in the turbulent solar-wind plasma are investigated by means of multi-dimensional simulations of the hybrid Vlasov-Maxwell (HVM) model [1]. Using 5D (2D in space and 3D in velocity space) and full 6D simulations of plasma turbulence, it is found that kinetic effects manifest through the deformation of the proton distribution function (DF), with patterns of non-Maxwellian features being concentrated near regions of strong magnetic gradients. Recent analyses [2] of solar-wind data from spacecraft aimed to quantify kinetic effects through the temperature anisotropy (T?/T//) on the proton velocity DF, with respect to the local magnetic field. Values of the anisotropy range broadly, with most values between 10-1and 10. Moreover, the distribution of temperature anisotropy depends systematically on the ambient proton parallel beta (?//), the ratio of parallel kinetic pressure to magnetic pressure, manifesting a characteristic rhomboidal shape. In order to make contact with solar-wind observations, temperature anisotropy has been evaluated from an ensemble of HVM simulations [3], obtained by varying the global plasma beta and fluctuation level, in such a way to cover distinct regions of the parameter space defined by T?/T// and ?//. The HVM simulations presented here demonstrate that, when the DF is free to explore the entire velocity subspace, new features appear as complex interactions between the particles and the turbulent background. In particular, our numerical results indicate that the main direction of the proper temperature anisotropy, calculated in the main reference frame of the DF [4], has a finite probability of being along or across the ambient magnetic field, and is associated with magnetic intermittent events and with gradient-type structures in the flow and in the density. Comparison of numerical results with solar-wind data shows remarkable quantitative agreement. [1] B. A. Maruca et al., Phys. Rev. Lett. 107, 201101 (2011). [2] F. Valentini et al., J. Comput. Phys. 225, 753 (2007). [3] S. Servidio et al., AstroPhys. J. Lett. 781, L27 (2014). [4] S. Servidio et al., Phys. Rev. Lett. 108, 045001 (2012).
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,v_{x},v_{y}) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volume algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,v_{r},v_{z}) phase space are presented.
A Hamiltonian fluid-kinetic model for a two-species non-neutral plasma
Tassi, E.; Chandre, C.; Romé, M.
2014-04-15
A model for describing the dynamics of a pure electron plasma in the presence of a population of massive charged particles is presented. The model couples the fluid dynamics of the pure electron plasma with the dynamics of the massive particle population, the latter being treated kinetically. The model is shown to possess a noncanonical Hamiltonian structure and to preserve invariants analogous to those of the two-dimensional (2D) Euler equation for an incompressible inviscid fluid, and of the Vlasov equation. The Hamiltonian structure of the model is used to derive a set of stability conditions for rotating coherent structures of the two-species system, in the case of negatively charged massive particles. According to these conditions, stability is attained if both the equilibrium distribution function of the kinetic species and the equilibrium density of the electron fluid are monotonically decreasing functions of the corresponding single-particle energies in the rotating frame. For radially confined equilibria near the axis, the stability condition corresponds to the existence of a finite interval of rotation frequencies for the reference frame, with the upper bound determined by the presence of the kinetic population.
Plasma Turbulence and Kinetic Instabilities at Ion Scales in the Expanding Solar Wind
NASA Astrophysics Data System (ADS)
Hellinger, Petr; Matteini, Lorenzo; Landi, Simone; Verdini, Andrea; Franci, Luca; Trávní?ek, Pavel M.
2015-10-01
The relationship between a decaying strong turbulence and kinetic instabilities in a slowly expanding plasma is investigated using two-dimensional (2D) hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized, random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations and vanishing correlation between the two fields. A turbulent cascade rapidly develops; magnetic field fluctuations exhibit a power-law spectrum at large scales and a steeper spectrum at ion scales. The turbulent cascade leads to an overall anisotropic proton heating, protons are heated in the perpendicular direction, and, initially, also in the parallel direction. The imposed expansion leads to generation of a large parallel proton temperature anisotropy which is at later stages partly reduced by turbulence. The turbulent heating is not sufficient to overcome the expansion-driven perpendicular cooling and the system eventually drives the oblique firehose instability in a form of localized nonlinear wave packets which efficiently reduce the parallel temperature anisotropy. This work demonstrates that kinetic instabilities may coexist with strong plasma turbulence even in a constrained 2D regime.
Kinetics of ion and prompt electron emission from laser-produced plasma
Farid, N.; Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian ; Harilal, S. S.; Hassanein, A.; Ding, H.
2013-07-15
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.
High-order continuum kinetic Vlasov-Poisson simulations of magnetized plasmas
NASA Astrophysics Data System (ADS)
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-10-01
Continuum methods offer a high-fidelity means of simulating plasma kinetics as modeled by the Boltzmann-Maxwell equation system. These methods are advantageous because they can be cast in conservation law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Thereby the methods can conserve mass, momentum, and energy to a high degree. A fourth-order accurate finite volume method has been developed to solve the continuum kinetic Vlasov-Poisson equation system in one spatial and two velocity dimensions. The method is validated in cartesian coordinates using the Dory-Guest-Harris instability, which is a special case of a perpendicularly-propagating kinetic electrostatic wave in a warm uniformly magnetized plasma. The instability dispersion relation, and its generalization to arbitrary distribution functions, are demonstrated to be well-suited benchmarks for continuum algorithms in higher-dimensional phase space. The numerical method has also been extended to two spatial dimensions, and has been implemented in cylindrical coordinates to simulate axisymmetric configurations such as a Z-pinch. This work was supported by the DOE SCGF fellowship, and grants from DOE ASCR and AFOSR.
Yoon, P. H. E-mail: rsch@tp4.rub.de; Schlickeiser, R. E-mail: rsch@tp4.rub.de; Kolberg, U. E-mail: rsch@tp4.rub.de
2014-03-15
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 n{sub e} are calculated as |?B|=?((?B){sup 2})=2.8(n{sub e}m{sub e}c{sup 2}){sup 1/2}g{sup 1/2}?{sub e}{sup 7/4} and |?E|=?((?E){sup 2})=3.2(n{sub e}m{sub e}c{sup 2}){sup 1/2}g{sup 1/3}?{sub e}{sup 2}, where g and ?{sub 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{sup ?18}G and |?E|=2·10{sup ?16}G result.
Continuum kinetic plasma modeling by the Vlasov-Maxwell system in multiple dimensions
NASA Astrophysics Data System (ADS)
Reddell, Noah; Shumlak, Uri
2014-10-01
A kinetic plasma model for multiple particle species described by the Vlasov equation and coupled to fully dynamic electromagnetic forces is presented. The model is implemented as evolving continuous PDFs (probability density functions) in particle phase space (position-velocity) as opposed to particle-in-cell (PIC) methods which discretely sample the PDF. The hyperbolic model is evolved using a high-order finite element method (discontinuous Galerkin), with excellent conservation of system mass, momentum, and energy - an advantage compared to PIC. Simulations of two- to six-dimensional phase space while resolving the plasma frequency and cyclotron frequency are computationally expensive. To maximize performance and scaling to large simulations, a new framework, WARPM, has been developed for many-core (e.g. GPU) computing architectures. WARPM supports both multi-fluid and continuum kinetic plasma models as coupled hyperbolic systems with nearest neighbor predictable communication. Simulation results are compared to existing benchmark problems and newly achievable studies of wave-particle interactions are presented. This research was supported by a grant from the United States Air Force Office of Scientific Research and Dept. of Energy Computational Science Graduate Fellowship.
NASA Astrophysics Data System (ADS)
Ladouceur, Harold; Baronavski, Andrew; Petrova, Tzvetelina
2006-03-01
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
Electron and ion kinetic effects on non-linearly driven electron plasma and ion acoustic waves
Berger, R. L.; Chapman, T.; Divol, L.; Still, C. H.; Brunner, S.; Valeo, E. J.
2013-03-15
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.
2-D kinetic laser-plasma simulations which include both stimulated Raman and Brillioun scattering
NASA Astrophysics Data System (ADS)
Sanbonmatsu, K. Y.; Vu, H. X.; Dubois, D. F.; Bezzerides, B.; Russell, D. A.
1998-11-01
Preliminary results are presented for a 2-D hybrid fluid-particle simulation capable of studying stimulated Raman and Brillioun scattering simultaneously for plasmas relevant to laser-plasma interaction experiments. This simulation code evolves the ions with a reduced-description particle-in-cell model. This new particle-in-cell model envelopes out the plasma frequency, significantly decreasing the ion numerical noise level. Furthermore, the laser pump frequency is enveloped out, allowing for a larger time step. The electrons are advanced by a fluid Zakharov model, which was shown to be adequate in Langmuir decay instability cascade and weakly driven collapse regimes. We implement this model on the Advanced Strategic Computing Initiative (ASCI) parallel computer at the Los Alamos Advanced Computing Laboratory. This work was performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory.
Nonlinear interaction and parametric instability of kinetic Alfven waves in multicomponent plasmas
Zhao, J. S.; Yang, L.; Wu, D. J.; Lu, J. Y.
2013-03-15
Nonlinear couplings among kinetic Alfven waves are investigated for a three-component plasma consisting of electrons, protons, and heavy ions. The parametric instability is investigated, and the growth rate is obtained. In the kinetic regime, the growth rate for the parallel decay instability increases with the heavy ion content, but the growth rate for the reverse decay is independent of the latter since the perpendicular wavelength is much larger than the ion gyroradius. It decreases with the heavy ion content when the perpendicular wavelength is of the order of the ion gyroradius. It is also found that in the short perpendicular wavelength limit, the growth rate is only weakly affected by the heavy ions. On the other hand, in the inertial regime, for both parallel and reverse decay cases, the growth rate decreases as the number of heavy ions becomes large.
Kinetic microtearing modes and reconnecting modes in strongly magnetised slab plasmas
NASA Astrophysics Data System (ADS)
Zocco, A.; Loureiro, N. F.; Dickinson, D.; Numata, R.; Roach, C. M.
2015-06-01
The problem of the linear microtearing mode in a slab magnetised plasma, and its connection to kinetic reconnecting modes, is addressed. Electrons are described using a novel hybrid fluid-kinetic model that captures electron heating, ions are gyrokinetic. Magnetic reconnection can occur as a result of either electron conductivity and inertia, depending on which one predominates. We eschew the use of an energy dependent collision frequency in the collisional operator model, unlike previous works. A model of the electron conductivity that matches the weakly collisional regime to the exact Landau result at zero collisionality and gives the correct electron isothermal response far from the reconnection region is presented. We identify in the breaking of the constant-A? approximation the necessary condition for microtearing instability in the collisional regime. Connections with the theory of collisional non-isothermal (or semicollisional) and collisionless tearing-parity electron temperature gradient driven (ETG) modes are elucidated.
Plasma turbulence and kinetic instabilities at ion scales in the expanding solar wind
Hellinger, Petr; Landi, Simone; Verdini, Andrea; Franci, Luca; Travnicek, Pavel M
2015-01-01
The relationship between a decaying strong turbulence and kinetic instabilities in a slowly expanding plasma is investigated using two-dimensional (2-D) hybrid expanding box simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly-polarized, random-phase Alfv\\'enic fluctuations which have energy equipartition between kinetic and magnetic fluctuations and vanishing correlation between the two fields. A turbulent cascade rapidly develops, magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at large scales and a steeper spectrum at ion scales. The turbulent cascade leads to an overall anisotropic proton heating, protons are heated in the perpendicular direction, and, initially, also in the parallel direction. The imposed expansion leads to generation of a large parallel proton temperature anisotropy which is at later stages partly reduced by turbulence. The turbulent heating is not sufficient to overco...
Lai, W. N.; Chapman, S. C.; Department of Mathematics and Statistics, University of Tromsø, Tromsø ; Dendy, R. O.; Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB
2013-10-15
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.
Ion kinetics in Ar/H2 cold plasmas: the relevance of ArH+
Jiménez-Redondo, Miguel; Cueto, Maite; Doménech, José Luis; Tanarro, Isabel; Herrero, Víctor J.
2015-01-01
The recent discovery of ArH+ in the interstellar medium has awakened the interest in the chemistry of this ion. In this work, the ion-molecule kinetics of cold plasmas of Ar/H2 is investigated in glow discharges spanning the whole range of [H2]/([H2]+[Ar]) proportions for two pressures, 1.5 and 8 Pa. Ion concentrations are determined by mass spectrometry, and electron temperatures and densities, with Langmuir probes. A kinetic model is used for the interpretation of the results. The selection of experimental conditions evinces relevant changes with plasma pressure in the ion distributions dependence with the H2 fraction, particularly for the major ions: Ar+, ArH+ and H3+. At 1.5 Pa, ArH+ prevails for a wide interval of H2 fractions: 0.3<[H2]/([H2]+[Ar])<0.7. Nevertheless, a pronounced displacement of the ArH+ maximum towards the lowest H2 fractions is observed at 8 Pa, in detriment of Ar+, which becomes restricted to very small [H2]/([H2]+[Ar]) ratios, whereas H3+ becomes dominant for all [H2]/([H2]+[Ar]) > 0.1. The analysis of the data with the kinetic model allows the identification of the sources and sinks of the major ions over the whole range of experimental conditions sampled. Two key factors turn out to be responsible for the different ion distributions observed: the electron temperature, which determines the rate of Ar+ formation and thus of ArH+, and the equilibrium ArH+ + H2 ? H3+ + Ar, which can be strongly dependent of the degree of vibrational excitation of H3+. The results are discussed and compared with previously published data on other Ar/H2 plasmas. PMID:26702354
Pateau, Amand; Rhallabi, Ahmed Fernandez, Marie-Claude; Boufnichel, Mohamed; Roqueta, Fabrice
2014-03-15
A global model has been developed for low-pressure, inductively coupled plasma (ICP) SF{sub 6}/O{sub 2}/Ar mixtures. This model is based on a set of mass balance equations for all the considered species, coupled with the discharge power balance equation and the charge neutrality condition. The present study is an extension of the kinetic global model previously developed for SF{sub 6}/Ar ICP plasma discharges [Lallement et al., Plasma Sources Sci. Technol. 18, 025001 (2009)]. It is focused on the study of the impact of the O{sub 2} addition to the SF{sub 6}/Ar gas mixture on the plasma kinetic properties. The simulation results show that the electron density increases with the %O{sub 2}, which is due to the decrease of the plasma electronegativity, while the electron temperature is almost constant in our pressure range. The density evolutions of atomic fluorine and oxygen versus %O{sub 2} have been analyzed. Those atomic radicals play an important role in the silicon etching process. The atomic fluorine density increases from 0 up to 40% O{sub 2} where it reaches a maximum. This is due to the enhancement of the SF{sub 6} dissociation processes and the production of fluorine through the reactions between SF{sub x} and O. This trend is experimentally confirmed. On the other hand, the simulation results show that O(3p) is the preponderant atomic oxygen. Its density increases with %O{sub 2} until reaching a maximum at almost 40% O{sub 2}. Over this value, its diminution with O{sub 2}% can be justified by the high increase in the loss frequency of O(3p) by electronic impact in comparison to its production frequency by electronic impact with O{sub 2}.
Kinetic simulation of capacitively coupled plasmas driven by trapezoidal asymmetric voltage pulses
Diomede, Paola Economou, Demetre J.
2014-06-21
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.
Excited-state kinetics and radiation transport in low-temperature plasmas
NASA Astrophysics Data System (ADS)
Colonna, G.; D'Ammando, G.; Pietanza, L. D.; Capitelli, M.
2015-01-01
An advanced self-consistent plasma physics model including non-equilibrium vibrational kinetics, a collisional radiative model for atomic species, a Boltzmann solver for the electron energy distribution function, a radiation transport module coupled to a steady inviscid flow solver and, has been applied to study non-equilibrium in high enthalpy flows for Jupiter’s atmosphere. Two systems have been considered, a hypersonic shock tube and nozzle expansion, emphasizing the role of radiation reabsorption on macroscopic and microscopic flow properties. Large differences are found between thin and thick plasma conditions not only for the distributions, but also for the macroscopic quantities. In particular, in the nozzle expansion case, the electron energy distribution functions are characterized by a rich structure induced by superelastic collisions between excited species and cold electrons.
Plasma heating at collisionless shocks due to the kinetic cross-field streaming instability
NASA Technical Reports Server (NTRS)
Winske, D.; Quest, K. B.; Tanaka, M.; Wu, C. S.
1985-01-01
Heating at collisionless shocks due to the kinetic cross-field streaming instability, which is the finite beta (ratio of plasma to magnetic pressure) extension of the modified two stream instability, is studied. Heating rates are derived from quasi-linear theory and compared with results from particle simulations to show that electron heating relative to ion heating and heating parallel to the magnetic field relative to perpendicular heating for both the electrons and ions increase with beta. The simulations suggest that electron dynamics determine the saturation level of the instability, which is manifested by the formation of a flattop electron distribution parallel to the magnetic field. As a result, both the saturation levels of the fluctuations and the heating rates decrease sharply with beta. Applications of these results to plasma heating in simulations of shocks and the earth's bow shock are described.
NASA Technical Reports Server (NTRS)
Lipatov, A. S.; Cooper, J F.; Paterson, W. R.; Sittler, E. C., Jr.; Hartle, R. E.; Simpson, David G.
2013-01-01
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).
Merging for Particle-Mesh Complex Particle Kinetic Modeling of the Multiple Plasma Beams
NASA Technical Reports Server (NTRS)
Lipatov, Alexander S.
2011-01-01
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.
Kinetic Energy Oscillations during Disorder Induced Heating in an Ultracold Plasma
NASA Astrophysics Data System (ADS)
Langin, Thomas; McQuillen, Patrick; Strickler, Trevor; Pohl, Thomas; Killian, Thomas
2015-05-01
Ultracold neutral plasmas of strontium are generated by photoionizing laser-cooled atoms at temperature TMOT ~ 10 mK and density n ~1016 m-3 in a magneto-optical trap (MOT). After photoionization, the ions heat to ~ 1 K by a mechanism known as Disorder Induced Heating (DIH). During DIH kinetic energy oscillations (KEO) occur at a frequency ~ 2?pi , where ?pi is the plasma frequency, indicating coupling to collective modes of the plasma. Electron screening also comes into play by changing the interaction from a Coulomb to a Yukawa interaction. Although DIH has been previously studied, improved measurements combined with molecular dynamics (MD) simulations allow us to probe new aspects. We demonstrate a measurement of the damping of the KEO due to electron screening which agrees with the MD simulations. We show that the MD simulations can be used to fit experimental DIH curves for plasma density n, resulting in very accurate density measurements. Finally, we discuss how ion temperature measurements are affected by the non-thermal distribution of the ions during the early stages of DIH. This work was supported by the United States National Science Foundation and the Department of Energy (PHY-0714603), the Air Force Office of Scientific Research (FA9550- 12-1-0267), the Shell Foundation, and the Department of Defense (NDSEG Fellowship)
Yamamoto, Shoko; Hayasaka, Fumitaka; Deguchi, Kisaburo; Okudera, Toshimitsu; Furusawa, Toshitake; Sakai, Yasuo
2015-12-01
Collagen tripeptide (CTP) is a collagen-derived compound containing a high concentration of tripeptides with a Gly-X-Y sequence. In this study, the concentrations and metabolites of CTP were monitored in rat plasma after its administration. We performed a quantitative analysis using high-performance liquid chromatography tandem mass spectrometry according to the isotopic dilution method with stable isotopes. We confirmed that the tripeptides Gly-Pro-Hyp, Gly-Pro-Ala, and Gly-Ala-Hyp were transported into the plasma. Dipeptides, which are generated by degradation of the N- or C-terminus of the tripeptides Gly-Pro-Hyp, Gly-Pro-Ala, and Gly-Ala-Hyp, were also present in plasma. The plasma kinetics for peroral and intraperitoneal administration was similar. In addition, tripeptides and dipeptides were detected in no-administration rat blood. The pharmacokinetics were monitored in rats perorally administered with Gly-[(3)H]Pro-Hyp. Furthermore, CTP was incorporated into tissues including skin, bone, and joint tissue. Thus, administering collagen as tripeptides enables efficient absorption of tripeptides and dipeptides. PMID:26155906
Lipatov, A S; Paterson, W R; Sittler, E C; Hartle, R E; Simpson, D G
2012-01-01
The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect a 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 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 backgr...
Advanced kinetic plasma model implementation for new large-scale investigations
NASA Astrophysics Data System (ADS)
Reddell, Noah; Shumlak, Uri
2013-10-01
A kinetic plasma model for of one or more particle species described by the Vlasov equation and coupled to fully dynamic electromagnetic forces is presented. The model is implemented as evolving continuous PDF (probability density function) in particle phase space (position-velocity) as opposed to particle-in-cell (PIC) methods which discretely sample the PDF. A new boundary condition for the truncated velocity-space edge, motivated by physical properties of the PDF tail, is introduced. The hyperbolic model is evolved using the discontinuous Galerkin numerical method, conserving system mass, momentum, and energy - an advantage compared to PIC. Simulations of two- to six-dimensional phase space are computationally expensive. To maximize performance and scaling to large simulations, a new framework, WARPM, has been developed for many-core (e.g. GPU) computing architectures. WARPM supports both multi-fluid and continuum kinetic plasma models as coupled hyperbolic systems with nearest neighbor predictable communication. Exemplary physics results and computational performance are presented.
NASA Astrophysics Data System (ADS)
Kosobrodova, E.; Kondyurin, A.; McKenzie, D. R.; Bilek, M. M. M.
2013-06-01
The surface chemistry of a synthetic material in contact with a biological system has a strong influence on the adhesion of proteins to the surface of the material and requires careful consideration in biomedical applications. The structure of plasma immersion ion implantation (PIII) treated polymer and its surface free energy depend on the ion fluence delivered during the treatment and on the time after the PIII treatment. These dependences have been investigated using the example of nitrogen plasma implanted polystyrene (PS). Contact angle measurements, FTIR-ATR spectra and X-ray photoelectron (XPS) spectra were acquired as a function of ion fluence and time after treatment. The results showed a close relationship to the kinetics of free radicals that had been examined in a previous study. The kinetics of oxidation and surface free energy had two stages, one with a characteristic time of several hours and the other with a characteristic time of several days. The concentration of nitrogen-containing groups decreased with time after PIII treatment, partly, due to their release from the PS surface.
Nitric oxide kinetics in the afterglow of a diffuse plasma filament
NASA Astrophysics Data System (ADS)
Burnette, D.; Montello, A.; Adamovich, I. V.; Lempert, W. R.
2014-08-01
A suite of laser diagnostics is used to study kinetics of vibrational energy transfer and plasma chemical reactions in a nanosecond pulse, diffuse filament electric discharge and afterglow in N2 and dry air at 100 Torr. Laser-induced fluorescence of NO and two-photon absorption laser-induced fluorescence of O and N atoms are used to measure absolute, time-resolved number densities of these species after the discharge pulse, and picosecond coherent anti-Stokes Raman spectroscopy is used to measure time-resolved rotational temperature and ground electronic state N2(v = 0-4) vibrational level populations. The plasma filament diameter, determined from plasma emission and NO planar laser-induced fluorescence images, remains nearly constant after the discharge pulse, over a few hundred microseconds, and does not exhibit expansion on microsecond time scale. Peak temperature in the discharge and the afterglow is low, T ? 370 K, in spite of significant vibrational nonequilibrium, with peak N2 vibrational temperature of Tv ? 2000 K. Significant vibrational temperature rise in the afterglow is likely caused by the downward N2-N2 vibration-vibration (V-V) energy transfer. Simple kinetic modeling of time-resolved N, O, and NO number densities in the afterglow, on the time scale longer compared to relaxation and quenching time of excited species generated in the plasma, is in good agreement with the data. In nitrogen, the N atom density after the discharge pulse is controlled by three-body recombination and radial diffusion. In air, N, NO and O concentrations are dominated by the reverse Zel'dovich reaction, N + NO ? N2 + O, and ozone formation reaction, O + O2 + M ? O3 + M, respectively. The effect of vibrationally excited nitrogen molecules and excited N atoms on NO formation kinetics is estimated to be negligible. The results suggest that NO formation in the nanosecond pulse discharge is dominated by reactions of excited electronic states of nitrogen, occurring on microsecond time scale.
NASA Technical Reports Server (NTRS)
Kim, H.; Crawford, F. W.
1977-01-01
It is pointed out that the conventional iterative analysis of nonlinear plasma wave phenomena, which involves a direct use of Maxwell's equations and the equations describing the particle dynamics, leads to formidable theoretical and algebraic complexities, especially for warm plasmas. As an effective alternative, the Lagrangian method may be applied. It is shown how this method may be used in the microscopic description of small-signal wave propagation and in the study of nonlinear wave interactions. The linear theory is developed for an infinite, homogeneous, collisionless, warm magnetoplasma. A summary is presented of a perturbation expansion scheme described by Galloway and Kim (1971), and Lagrangians to third order in perturbation are considered. Attention is given to the averaged-Lagrangian density, the action-transfer and coupled-mode equations, and the general solution of the coupled-mode equations.
Comparison of hydrodynamic and semi-kinetic treatments for plasma flow along closed field lines
NASA Technical Reports Server (NTRS)
Singh, Nagendra; Wilson, G. R.; Horwitz, J. L.
1993-01-01
Hydrodynamic and semi-kinetic treatments of plasma flow along closed geomagnetic field lines are compared. The hydrodynamic treatment is based on a simplified 16-moment set of transport equations as the equations for the heat flows are not solved; the heat flows are treated heuristically. The semi-kinetic treatment is based on a particle code. The comparison deals with the distributions of the plasma density, flow velocity, and parallel and perpendicular temperatures as obtained from the two treatments during the various stages of the flow. In the kinetic treatment, the appropriate boundary condition is the prescription of the velocity distribution functions for the particles entering the flux tubes at the ionospheric boundaries; those particles leaving the system are determined by the processes occurring in the flux tube. The prescribed distributions are half-Maxwellian with temperature T(sub 0) and density n(sub 0). In the hydrodynamic model, the prescribed boundary conditions are on density (n(sub 0)), flow velocity (V(sub 0)) and temperature (T(sub 0). It was found that results from the hydrodynamic treatment critically depend on V(sub 0); for early stages of the flow this treatment yields results in good agreement with those from the kinetic treatment, when V(sub 0) = square root of (kT(sub 0)/2 (pi)m), which is the average velocity of particles moving in a given direction for a Maxwellian distribution. During this early stage, the flows developing form the conjugate ionospheres show some distinct transitions. For the first hour or so, the flows are highly supersonic and penetrate deep into the opposite hemispheres, and both hydrodynamics and kinetic treatments yield almost similar features. It is found that during this period heatflow effects are negligibly small. When a flow penetrates deep into the opposite hemisphere, the kinetic treatment predicts reflection and setting up of counterstreaming. In contrast, the hydrodynamic treatment yields a shock in the flow. The reasons for this difference in the two treatments is discussed, showing that in view of the relatively warm ions, the coupling of ion beams and the consequent shock formation in the offequatorial region are not likely due to the enhancements in the beam temperatures. The counterstreaming in the kinetic treatment and the shock in the hydrodynamic treatment first advance upward to the equator and then downward to the ionospheric boundary from where the flow originated. The transit time for this advancement is found to be about 1 hour for the respective models. After 2 hours or so, both models predict that the flows from the ionospheric boundaries are generally subsonic with respect to the local ion-sound speed. At late stages of the flow, when a substantial fraction of ions entering the flux tube begin to return back in the kinetic treatment, the hydrodynamic treatment with the boundary condition V(sub 0) = square root of (kT(sub 0)/2(pi)m) yields an over-refilling, and the choice of V(sub 0) becomes uncertain.
NASA Astrophysics Data System (ADS)
Yafarov, R. K.; Shanygin, V. Ya.
2015-06-01
The kinetics of self-organization of nanodomains during the deposition of submonolayer carbon coatings on (100) silicon in the microwave plasma of low-pressure ethanol vapors is studied by atomic force microscopy and scanning electron microscopy. The laws of influence of the substrate temperature and the kinetic energy of carbon-containing ions on the mechanisms of formation and structuring of the forming silicon-carbon surface phases are established. It is shown that the deposited carbon-containing nanodomains can be used as nonlithographic mask coatings for the formation of spatial low-dimensional systems on single-crystal silicon upon selective highly anisotropic plasma-chemical etching.
Lee, Joe; Graves, David B.; Kazi, Haseeb; Gaddam, Sneha; Kelber, Jeffry A.
2013-07-15
In-situ x-ray photoelectron spectroscopy (XPS) and ex-situ Fourier transform infrared studies of He plasma and Ar{sup +} ion bombardment pretreatments of organosilicate glass demonstrate that such pretreatments inhibit subsequent O{sub 2} plasma-induced carbon loss by forming a SiO{sub 2}-like damaged overlayer, and that the degree of protection correlates directly with increased ion kinetic energies, but not with the thickness of the SiO{sub 2} overlayer. This thickness is observed by XPS to be roughly constant and <1 nm regardless of ion energies involved. The data indicate that ion kinetic energies are an important parameter in protective noble gas plasma pretreatments to inhibit O{sub 2} plasma-induced carbon loss.
The Effect of Hydrogen on Plasma Nitriding of Austenitic Stainless Steel: Kinetic Modeling
NASA Astrophysics Data System (ADS)
Moskalioviene, Teresa; Galdikas, Arvaidas
2015-12-01
The kinetic model of adsorption and stress-induced diffusion of nitrogen in austenitic stainless steels taking place during plasma nitriding using various mixtures of nitrogen and hydrogen is proposed. On the basis of proposed model, a numerical study has been undertaken to analyze and describe the effect of hydrogen on plasma nitriding of austenitic stainless steel. It was shown that the addition of hydrogen with concentrations in the range ~(30 to 40) pct enhances nitrogen penetration into steel. This is due to two factors: (1) reduction of the surface oxide due to chemical etching of the oxygen by hydrogen and (2) increase of NH radicals which are converted to active nitrogen atoms on the steel surface, i.e., the amount of adsorbed and diffused nitrogen increases. As a result, the thicker nitrogen-containing layer is observed. Moreover, results of numerical prediction show that an excessive amount of hydrogen (more than ~70 pct) in the gas mixture retards the nitriding process in comparison with nitriding in pure nitrogen plasma.
Tskhakaya, D. D.; Kos, L.
2014-10-15
The magnetized plasma-wall transition (MPWT) layer at the presence of the obliquity of the magnetic field to the wall consists of three sub-layers: the Debye sheath (DS), the magnetic pre-sheath (MPS), and the collisional pre-sheath (CPS) with characteristic lengths ?{sub D} (electron Debye length), ?{sub i} (ion gyro-radius), and ? (the smallest relevant collision length), respectively. Tokamak plasmas are usually assumed to have the ordering ?{sub D}??{sub i}??, when the above-mentioned sub-layers can be distinctly distinguished. In the limits of ?{sub Dm}(?{sub D}/?{sub i})?0 and ?{sub mc}(?{sub i}/?)?0 (“asymptotic three-scale (A3S) limits”), these sub-layers are precisely defined. Using the smallness of the tilting angle of the magnetic field to the wall, the ion distribution functions are found for three sub-regions in the analytic form. The equations and characteristic length-scales governing the transition (intermediate) regions between the neighboring sub-layers (CPS – MPS and MPS – DS) are derived, allowing to avoid the singularities arising from the ?{sub Dm}?0 and ?{sub mc}?0 approximations. The MPS entrance and the related kinetic form of the Bohm–Chodura condition are successfully defined for the first time. At the DS entrance, the Bohm condition maintains its usual form. The results encourage further study and understanding of physics of the MPWT layers in the modern plasma facilities.
A fully kinetic, self-consistent particle simulation model of the collisionless plasma-sheath region
NASA Astrophysics Data System (ADS)
Procassini, R. J.; Birdsall, C. K.; Morse, E. C.
1990-12-01
A fully kinetic particle-in-cell (PIC) model is used to self-consistently determine the steady-state potential profile in a collisionless plasma that contacts a floating, absorbing boundary. To balance the flow of particles to the wall, a distributed source region is used to inject particles into the one-dimensional system. The effect of the particle source distribution function on the source region and collector sheath potential drops, and particle velocity distributions is investigated. The ion source functions proposed by Emmert et al. [Phys. Fluids 23, 803 (1980)] and Bissell and Johnson [Phys. Fluids 30, 779 (1987)] (and various combinations of these) are used for the injection of both ions and electrons. The values of the potential drops obtained from the PIC simulations are compared to those from the theories of Emmert et al., Bissell and Johnson, and Scheuer and Emmert [Phys. Fluids 31, 3645 (1988)], all of which assume that the electron density is related to the plasma potential via the Boltzmann relation. The values of the source region and total potential drop are found to depend on the choice of the electron source function, as well as the ion source function. The question of an infinite electric field at the plasma-sheath interface, which arises in the analyses of Bissell and Johnson and Scheuer and Emmert, is also addressed.
Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results
NASA Technical Reports Server (NTRS)
Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.; Simpson, D. G.
2010-01-01
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.
Kinetic effects and nonlinear heating in intense x-ray-laser-produced carbon plasmas.
Sentoku, Y; Paraschiv, I; Royle, R; Mancini, R C; Johzaki, T
2014-11-01
The x-ray laser-matter interaction for a low-Z material, carbon, is studied with a particle-in-cell code that solves the photoionization and x-ray transport self-consistently. Photoionization is the dominant absorption mechanism and nonthermal photoelectrons are produced with energy near the x-ray photon energy. The photoelectrons ionize the target rapidly via collisional impact ionization and field ionization, producing a hot plasma column behind the laser pulse. The radial size of the heated region becomes larger than the laser spot size due to the kinetic nature of the photoelectrons. The plasma can have a temperature of more than 10 000 K (>1eV), an energy density greater than 10^{4} J/cm^{3}, an ion-ion Coulomb coupling parameter ??1, and electron degeneracy ??1, i.e., strongly coupled warm dense matter. By increasing the laser intensity, the plasma temperature rises nonlinearly from tens of eV to hundreds of eV, bringing it into the high energy density matter regime. The heating depth and temperature are also controllable by changing the photon energy of the incident laser light. PMID:25493733
Bonitz, Michael
2005-01-01
Institute of Physics Publishing Journal of Physics: Conference Series 11 (2005) doi:10.1088/1742-6596/11/1/E01 Kinetic Theory of Nonideal Plasmas Preface The International Workshop `Kinetic Theory of Nonideal Plasmas' was held on September 2729 2004 at the ChristianAlbrechtsUniversity in Kiel, Germany
Chan, Anthony Arthur
PHYS 519: Plasma Kinetic Theory Homework 6 Due before 5pm Thursday November 13, 2014. Email. Consider the one-dimensional kinetic equation ux f x = -(f - f0) (1) where f is the electron distribution to the kinetic velocity u. (e) The element xx of the anisotropic pressure tensor contains a term of the form -µ
Dense Plasma Focus Z-Pinch Fully Kinetic Modeling and Ion Probe-Beam Experiments
NASA Astrophysics Data System (ADS)
Schmidt, Andrea
2013-10-01
The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions on a cm-scale length, even for kJ-scale devices. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the mechanisms behind these large gradients using the first fully kinetic simulations of a DPF Z-pinch as well as an ion probe beam experiment in which a 4 MeV deuteron beam is injected along the z-axis of a DPF Z-pinch plasma and accelerated. Our table-top DPF has demonstrated >50 MV/m acceleration gradients during 800 J operation using a fast capacitive driver. We have now directly measured the DPF gradients and demonstrated acceleration of an injected ion beam for the first time. Our particle-in-cell simulations have successfully predicted observed DPF ion beams and neutron yield, which past fluid simulations have not reproduced. We have now experimentally measured and observed in the simulations for the first time, electric field oscillations near the lower hybrid frequency. This is suggestive that the lower hybrid drift instability, long speculated to be the cause of the anomalous plasma resistivity that produces large DPF gradients, is playing an important role. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications. 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.
2005 Workshop on NCETIP 1 Kinetic of plasma particles and electron
Kaganovich, Igor
action on metals. · Ablative plasma accelerators · MHD power conversion. · Vacuum arc Cathode spot · Plasma in vacuum arc cathode spot. Electron transport · Cathode evaporation DIFFERENT CATHODE MATERIALSTeflon evaporation TEFLON Teflon evaporation CATHODE ANODE Plasma expansion Pulsed PlasmaPulsed Plasma Thrusters
A kinetic electron-neutral collision model for particle-in-cell plasma simulation
NASA Astrophysics Data System (ADS)
Pointon, Timothy; Cartwright, Keith
2014-10-01
Details of a kinetic electron-neutral collision model for particle-in-cell plasma simulation codes are presented. The model uses an efficient scheme to randomly select collision events - elastic, excitation and ionization - with the appropriate probability Ionization events create electron-ion pairs, and the secondary electrons can themselves ionize the gas. To maintain a manageable particle count, a particle merger algorithm can be used to periodically replace all particles of a given species in a cell with a new, smaller set that conserves charge, momentum, and energy Small-scale tests show that results with the merger are in good agreement with non-merged runs. Large simulations can only be done with the merger on, and typically show excellent merger efficiency (>90%). Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the U.S. DOE's NNSA under Contract DE-AC04-94-AL85000.
Brunner, S. Hausammann, L.; Berger, R. L. Cohen, B. I.; Valeo, E. J.
2014-10-15
Kinetic Vlasov simulations of one-dimensional finite amplitude Electron Plasma Waves are performed in a multi-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate ? and quasi- wavenumber ?k, is carried out by scanning the amplitude and wavenumber of the initial wave. Simulation results are successfully compared against numerical and analytical solutions to the reduced model by Kruer et al. [Phys. Rev. Lett. 23, 838 (1969)] for the Trapped Particle Instability (TPI). A model recently suggested by Dodin et al. [Phys. Rev. Lett. 110, 215006 (2013)], which in addition to the TPI accounts for the so-called Negative Mass Instability because of a more detailed representation of the trapped particle dynamics, is also studied and compared with simulations.
Brunner, S.; Berger, R. L.; Cohen, B. I.; Hausammann, L.; Valeo, E. J.
2014-10-01
Kinetic Vlasov simulations of one-dimensional finite amplitude Electron Plasma Waves are performed in a multi-wavelength long system. A systematic study of the most unstable linear sideband mode, in particular its growth rate ? and quasi- wavenumber ?k, is carried out by scanning the amplitude and wavenumber of the initial wave. Simulation results are successfully compared against numerical and analytical solutions to the reduced model by Kruer et al. [Phys. Rev. Lett. 23, 838 (1969)] for the Trapped Particle Instability (TPI). A model recently suggested by Dodin et al. [Phys. Rev. Lett. 110, 215006 (2013)], which in addition to the TPI accounts for the so-called Negative Mass Instability because of a more detailed representation of the trapped particle dynamics, is also studied and compared with simulations.
Kinetic theory of dust ion acoustic waves in a kappa-distributed plasma
NASA Astrophysics Data System (ADS)
Baluku, T. K.; Hellberg, M. A.
2015-08-01
Using a kinetic theory approach, dust ion acoustic (DIA) waves are investigated in an unmagnetized collisionless plasma with kappa-distributed electrons and ions, and Maxwellian dust grains of constant charge. Both analytical and numerical results, the latter following from the full solution of the associated dispersion relation, are presented, and a comparison is made. The effects of the ion and electron spectral indices, as well as the species' density ( ne/ni ) and temperature ( Te/Ti ) ratios, on the dispersion and damping of the waves are considered. In the long wavelength regime, increases in both the electron spectral index (?e) and the dust density fraction (reduced f =ne/ni ) lead to an increase in phase velocity. The range in wavelength over which modes are weakly damped increases with an increase in Te/Ti . However, the ion spectral index, ?i, does not have a significant effect on the dispersion or damping of DIA waves.
Kinetic description of ionospheric dynamics in the three-fluid approximation
NASA Technical Reports Server (NTRS)
Comfort, R. H.
1975-01-01
Conservation equations are developed in the three-fluid approximation for general application problems of ionospheric dynamics in the altitude region 90 km to 800 km for all geographic locations. These equations are applied to a detailed study of auroral E region neutral winds and their relationship to ionospheric plasma motions.
Kinetic simulation of the O-X conversion process in dense magnetized plasmas
Ali Asgarian, M.; Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 ; Verboncoeur, J. P.; Parvazian, A.; Trines, R.
2013-10-15
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{sup ?} is obtained, which is in good agreement with efficiencies computed via full-wave simulations.
Fully kinetic simulations of magnetic reconnction in semi-collisional plasmas
Daughton, William S; Roytershteyn, Vadim S; Albright, Brian J; Yin, Lin; Bowers, Kevin J; Karimabadi, Homa
2009-01-01
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.
Kinetic simulation of the O-X conversion process in dense magnetized plasmas
NASA Astrophysics Data System (ADS)
Ali Asgarian, M.; Verboncoeur, J. P.; Parvazian, A.; Trines, R.
2013-10-01
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? is obtained, which is in good agreement with efficiencies computed via full-wave simulations.
NASA Technical Reports Server (NTRS)
Singh, Nagendra
2000-01-01
Under this grant we have done research on the following topics. 1) Development of Parallel PIC Codes (PPIC); 2) Evolution of Lower-Hybrid Pump Waves; 3) Electron-beam Driven Plasma Electrodynamics; and 4) Studies on Inertial and Kinetic Alfven Waves. A brief summary of our findings and resulting publications are given.
KINETIC PLASMA TURBULENCE IN THE FAST SOLAR WIND MEASURED BY CLUSTER
Roberts, O. W.; Li, X.; Li, B.
2013-05-20
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.
A. V. Filatov; S. A. Smolyansky; A. V. Tarakanov
2009-01-05
The kinetic equation of non - Markovian type for description of the vacuum creation of parton - antiparton pairs under action of a space homogeneous time - dependent chromo - electric field of the arbitrary polarization is obtained on the strict non - pertubative foundation in the framework of the oscillator representation. A comparison of the effectiveness of vacuum creation with the case of linear polarization one is fulfilled.
NASA Astrophysics Data System (ADS)
Evstatiev, E. G.
2014-11-01
We formulate a finite-size particle numerical model of strongly magnetized plasmas in the drift-kinetic approximation. We use the phase space action as an alternative to previous variational formulations based on Low’s Lagrangian or on a Hamiltonian with a non-canonical Poisson bracket. The useful property of this variational principle is that it allows independent transformations of particle coordinates and velocities, i.e., transformations in particle phase space. With such transformations, a finite degree-of-freedom drift-kinetic action is obtained through time-averaging of the finite degree-of-freedom fully-kinetic action. Variation of the drift-kinetic Lagrangian density leads to a self-consistent, macro-particles and fields numerical model. Since the computational particles utilize only guiding center coordinates and velocities, there is a large computational advantage in the time integration part of the algorithm. Numerical comparison between the time-averaged fully-kinetic and drift-kinetic charge and current, deposited on a computational grid, offers insight into the range of validity of the model. Being based on a variational principle, the algorithm respects the energy conserving property of the underlying continuous system. The development in this paper serves to further emphasize the advantages of using variational approaches in plasma particle simulations.
Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch
NASA Astrophysics Data System (ADS)
Schmidt, A.; Ellsworth, J.; Falabella, S.; Link, A.; McLean, H.; Rusnak, B.; Sears, J.; Tang, V.; Welch, D.
2014-12-01
The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ˜cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications.
NASA Technical Reports Server (NTRS)
Khazanov, George V.; Khabibrakhmanov, Ildar K.; Glocer, Alex
2012-01-01
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.
Hypovalency--a kinetic-energy density description of a 4c-2e bond.
Jacobsen, Heiko
2009-06-01
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
A mechanistic description of radiation-induced damage to normal tissue and its healing kinetics
NASA Astrophysics Data System (ADS)
Hanin, Leonid; Zaider, Marco
2013-02-01
We introduce a novel mechanistic model of the yield of tissue damage at the end of radiation treatment and of the subsequent healing kinetics. We find explicit expressions for the total number of functional proliferating cells as well as doomed (functional but non-proliferating) cells as a function of time post treatment. This leads to the possibility of estimating—for any given cohort of patients undergoing radiation therapy—the probability distribution of those kinetic parameters (e.g. proliferation rates) that determine times to injury onset and ensuing resolution. The model is suitable for tissues with simple duplication organization, meaning that functionally competent cells are also responsible for tissue renewal or regeneration following injury. An extension of the model to arbitrary temporal patterns of dose rate is presented. To illustrate the practical utility of the model, as well as its limitations, we apply it to data on the time course of urethral toxicity following fractionated radiation treatment and brachytherapy for prostate cancer.
A Continuum Description of Rarefied Gas Dynamics (I)--- Derivation From Kinetic Theory
Xinzhong Chen; Hongling Rao; Edward A. Spiegel
2001-05-20
We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulae at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process-dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity.
Reduced fluid descriptions of toroidally confined plasma with finite ion temperature effects
Hsu, C.T.
1987-03-01
Fluid descriptions of toroidally confined plasma with FLR effects are studied, based on a generalized, energy conserving, self-consistent, nonlinear reduced fluid model (HHM). The model, derived via a fluid approach starting from moment equations, differs from Braginskii's fluid system in retaining O(rho/sub i//sup 2/) terms (where rho/sub i/ is the ion gyroradius) and most of the non-ideal effects. Hence, many of the well-known reduced fluid models can be reproduced from HHM by simply specifying scales of some parameters such as rho/sub i/ and ..beta... On the other hand, a Pade approximation of the full FLR system, obtained from the simplified version of HHM, is also presented.
Ntuli, Tobias M; Pammenter, Norman W
2009-11-01
The response of desiccation-sensitive plant tissues to dehydration is significantly affected by dehydration conditions, particularly the rate of drying. Consequently it is important to be able to quantify drying rate. The aim of the study was to assess two models that have been proposed to describe drying kinetics, and thus to provide a quantification of non-linear drying rates, of embryonic axes excised from recalcitrant seeds. These models are an exponential drying time course, and a modified inverse relationship, respectively. For the six species investigated here the inverse function was generally found to fit drying data better than the exponential function under both rapid and slow drying conditions, and so is recommended. The rate of drying, under the conditions used here, was determined by axis size and possibly the nature of the axis outer coverings, rather than the water activity difference between the tissue and surrounding air. PMID:19903222
Dynamics of Relativistic Interacting Gases : from a Kinetic to a Fluid Description
Jean-Philippe Uzan
1998-01-30
Starting from a microscopic approach, we develop a covariant formalism to describe a set of interacting gases. For that purpose, we model the collision term entering the Boltzmann equation for a class of interactions and then integrate this equation to obtain an effective macroscopic description. This formalism will be useful to study the cosmic microwave background non-perturbatively in inhomogeneous cosmologies. It should also be useful for the study of the dynamics of the early universe and can be applied, if one considers fluids of galaxies, to the study of structure formation.
NASA Astrophysics Data System (ADS)
Cohen, Bruce; Divol, Laurent; Langdon, Bruce; Williams, Ed
2006-10-01
1D and 2D simulations with the BZOHAR^2,3 hybrid code (kinetic PIC ions and Boltzmann fluid electrons) are being used to investigate the saturation of stimulated Brillouin backscatter (SBBS) instability for plasma conditions in ignition campaign experiments in the National Ignition Facility. Ignition targets must be designed so that backscatter is not severe. BZOHAR can simulate ion kinetic and fluid nonlinearities affecting SBBS.^2-4 A reduced model that captures the physics of two-ion-wave-decay instability, ion trapping effects (nonlinear frequency shift and reduction of ion Landau damping^4), and pump depletion has been synthesized in coupled-mode equations that are being implemented in the pF3d fluid simulation code used for macroscopic 2D and 3D simulations of laser-plasma interactions. Progress will be reported including studies of whether ion trapping can ``inflate'' SBBS reflectivities by reducing ion Landau damping. Refs.: ^ 2B.I. Cohen, B.F. Lasinski, A.B. Langdon, and E.A. Williams, Phys. Plasmas 4, 956 (1997). ^3B.I. Cohen, L. Divol, A.B. Langdon, and E.A. Williams, Phys. Plasmas 12, 052703 (2005) and Phys. Plasmas 13, 022705 (2006). ^4L. Divol, et al., Phys. Plasmas 10, 1822 (2003).
NASA Astrophysics Data System (ADS)
Pellat, Rene; Le Contel, Olivier; Roux, Alain; Perraut, Sylvaine; Hurricane, Omar; Coroniti, Ferdinand V.
We describe a new self-consistent kinetic approach of collisionless plasmas. The basic equations are obtained from a linearization of the cyclotron and bounce averaged Vlasov and Maxwell equations. In the low frequency limit the Gauss equation is shown to be equivalent to the Quasi-Neutrality Condition (QNC). First we describe the work of Hurricane et al., 1995b, who investigated the effect of stochasticity on the stability of ballooning modes. An expression for the energy principle is obtained in the stochastic case, with comparisons with the adiabatic case. Notably, we show how the non adiabaticity of ions allows to recover a MHD-like theory with a modification of the polytropic index, for waves with frequencies smaller than the bounce frequency of protons. The stochasticity of protons can be due, in the far plasma sheet (beyond 10-12 RE, RE being the Earth radius), to the development of thin Current Sheet (CS) with a curvature radius that becomes smaller than the ion Larmor radius. Conversely the near Earth plasma sheet (6-8 RE), where the curvature radius is larger, is expected to be in the adiabatic regime. We give a description of slowly evolving (quasi-static) magnetic configurations, during the formation of high altitudes CS's, for instance during substorm growth phase in the Earth magnetosphere, and tentatively during the formation of CS's in the solar corona. Thanks to the use of a simple equilibrium magnetic field, a 2D dipole, the linear electromagnetic perturbations are computed analytically as functions of a forcing electrical current. The QNC, which is valid for long perpendicular wavelength electromagnetic perturbations (k?D1 where ?D is the Debye length), is developed via an expansion in the small parameter Te/Ti. To the lowest order in Te/Ti (Te/Ti->0) we find that the enforcement of the QNC implies the presence of an electrostatic potential which is constant along the field line, but varies across it. The corresponding potential electric field is perpendicular to the magnetic field; it corresponds to the self-consistent response of the plasma to an externally applied time varying perturbation. This potential electric field tends to reduce the effect of the induced electric field, hence producing a partial ``shielding'' of the motion that would correspond to the induced electric field if it was alone. The effect of the total azimuthal electric field, obtained from the QNC, on the radial transport of the plasma is investigated. We show that the direction of the perpendicular electric field varies with the latitude. As a consequence, for a time dependent transport, the equatorial electric field cannot usually be mapped onto the low altitude electric field (ionosphere for the Earth), even in the absence of a parallel electric field. Present calculations show that during the substorm growth phase, the (total) azimuthal electric field is directed eastward, close to the equator, and westward off-equator. Thus, large equatorial pitch-angle particles drift tailward whereas small pitch-angle particles drift earthward. Finally, to the next order in Te/Ti, we show that the formation of the thin current sheet lead to the development of a finite parallel electric field. Thus time variations in high altitude CS's are coupled to the low altitude regions (ionosphere for the Earth) via (i) an electrostatic component constant along the magnetic field line and via (ii) the parallel electric fields. Associated with this parallel electric field, a parallel current develops. We suggest that this current drives an instability at frequencies well above that imposed by the forcing current. Unstable waves are electromagnetic and have frequencies of the order of the proton gyrofrequency. Given their large amplitudes these waves can produce a fast electron and ion diffusion which modify the electrical currents in a such manner that the reconfiguration of the magnetic field occurs.
NASA Technical Reports Server (NTRS)
Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.
2008-01-01
Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.
Péronnet, F; Meynier, A; Sauvinet, V; Normand, S; Bourdon, E; Mignault, D; St-Pierre, D H; Laville, M; Rabasa-Lhoret, R; Vinoy, S
2015-01-01
Background/Objectives: Foods with high contents of slowly digestible starch (SDS) elicit lower glycemic responses than foods with low contents of SDS but there has been debate on the underlying changes in plasma glucose kinetics, that is, respective contributions of the increase in the rates of appearance and disappearance of plasma glucose (RaT and RdT), and of the increase in the rate of appearance of exogenous glucose (RaE) and decrease in endogenous glucose production (EGP). Subjects/Methods: Sixteen young healthy females ingested in random order four types of breakfasts: an extruded cereal (0.3% SDS: Lo-SDS breakfast) or one of three biscuits (39–45% SDS: Hi-SDS breakfasts). The flour in the cereal products was labeled with 13C, and plasma glucose kinetics were measured using [6,6-2H2]glucose infusion, along with the response of plasma glucose, insulin and glucose-dependent insulinotropic peptide (GIP) concentrations. Results: When compared with the Lo-SDS breakfast, after the three Hi-SDS breakfasts, excursions in plasma glucose, the response of RaE, RaT and RdT, and the reduction in EGP were significantly lower (P<0.05). The amount of exogenous glucose absorbed over the 4.5-h postprandial period was also significantly lower by ~31% (P<0.001). These differences were associated with lower responses of GIP and insulin concentrations. Conclusions: Substituting extruded cereals with biscuits slows down the availability of glucose from the breakfast and its appearance in peripheral circulation, blunts the changes in plasma glucose kinetics and homeostasis, reduces excursions in plasma glucose, and possibly distributes the glucose ingested over a longer period following the meal. PMID:25852025
NASA Technical Reports Server (NTRS)
Gary, S. P.
1984-01-01
This paper describes the linear kinetic theory of electrostatic instabilities driven by a density gradient drift and a magnetic-field-aligned current in a plasma with weak charged neutral collisions. The configuration is that of a uniform magnetic field B, a weak, uniform density gradient in the x direction and a weak, uniform electric field in the z direction. Collisions are represented by the BGK model. The transition from the (kinetic) universal density drift instability to the (fluidlike) current convective instability is studied in detail, and the short wavelength properties of the latter mode are investigated.
High-resolution Hybrid Simulations of Kinetic Plasma Turbulence at Proton Scales
NASA Astrophysics Data System (ADS)
Franci, Luca; Landi, Simone; Matteini, Lorenzo; Verdini, Andrea; Hellinger, Petr
2015-10-01
We investigate properties of plasma turbulence from magnetohydrodynamic (MHD) to sub-ion scales by means of two-dimensional, high-resolution hybrid particle-in-cell simulations. We impose an initial ambient magnetic field perpendicular to the simulation box, and we add a spectrum of large-scale magnetic and kinetic fluctuations with energy equipartition and vanishing correlation. Once the turbulence is fully developed, we observe an MHD inertial range, where the spectra of the perpendicular magnetic field and the perpendicular proton bulk velocity fluctuations exhibit power-law scaling with spectral indices of -5/3 and -3/2, respectively. This behavior is extended over a full decade in wavevectors and is very stable in time. A transition is observed around proton scales. At sub-ion scales, both spectra steepen, with the former still following a power law with a spectral index of ? -3. A -2.8 slope is observed in the density and parallel magnetic fluctuations, highlighting the presence of compressive effects at kinetic scales. The spectrum of the perpendicular electric fluctuations follows that of the proton bulk velocity at MHD scales, and flattens at small scales. All these features, which we carefully tested against variations of many parameters, are in good agreement with solar wind observations. The turbulent cascade leads to on overall proton energization with similar heating rates in the parallel and perpendicular directions. While the parallel proton heating is found to be independent on the resistivity, the number of particles per cell, and the resolution employed, the perpendicular proton temperature strongly depends on these parameters.
Guo Wei; Bai Bo; Sawin, Herbert H.
2009-03-15
In this article the major kinetics models for plasma-surface interactions were reviewed highlighting their strengths and limitations. As a subset of reactive-site modeling, mixing-layer kinetics model was developed based upon the assumption of random atomic mixing in the top surface layer. The translation of the layer enabled the modeling of both etching and deposition. A statistical concept, nearest-neighbor bonding probability, was defined to express the concentration of any surface moieties with the surface elemental composition. A lumped set of reactions was adopted to carry on the overall physichemical processes including ion incorporation, neutral adsorption, physical sputtering, ion-enhanced etching, dangling bond generation and annihilation, and spontaneous etching. The rate coefficients were fitted to the experimental etching yields at various beam etching conditions. The good match between the kinetics modeling and the experimental results verified the capability of the mixing-layer model of predicting the poly-Si etching in chlorine plasma at various operating conditions. Then the kinetics model was incorporated into the three-dimensional Monte Carlo profile simulator. The concept of the mixing layer was simulated by a cellular-based model through composition averaging among neighboring cells. The reactions were sorted out in terms of ion initiated and neutral initiated, respectively, as discrete events. The reaction rates were calculated based upon the cellular composition and used as probabilities to remove particles from the cell. Results showed that the profile simulation combined with the kinetics, the numeric kinetics model, and the experimental etching yields are in quantitative agreement, which demonstrated the accuracy of kinetics after incorporation into the profile simulation. The simulation was compared to the published research work comprehensively including the etching yields, surface compositions, and dominant product distributions.
Mainz Organics Mechanism (MOM): description and sensitivity to some estimated kinetic parameters
NASA Astrophysics Data System (ADS)
Taraborrelli, Domenico; Cabrera Perez, David; Sander, Rolf; Pozzer, Andrea
2015-04-01
Despite decades of reasearch, global atmospheric chemistry models still have significant biases compared to the estimated distribution and evolution of tropospheric ozone and hydroxyl radical. The gas-phase oxidation of volatile organic compounds (VOC) is acknowledged to play an important role among the processes affecting tropospheric ozone, methane lifetime and aerosol evolution. Thus, chemical mechanisms of very diverse complexity have been developed for the major VOCs. However, all mechanisms present shortcomings such as neglection or lumping of intermediates and estimate of many rate constants and product distributions. Here, we present a VOC oxidation mechanism of intermediate complexity called the Mainz Organics Mechanism (MOM). With about 400 species and 1500 reactions, it represents the oxidation of about 20 primarily emitted VOCs comprising small alkanes and alkenes, isoprene, pinenes and monocyclic aromatic compounds. The development protocol significantly borrows from the Master Chemical Mechanism (MCM). However, MOM distinguishes itself for a number of features. First, the structure activity relationship for estimating the rate constants involving hydroxyl radical is site-specific and dependent on temperature. Second, the alkyl nitrate yields are considered to be dependent on temperature, pressure and molecular structure. RO2 + HO2 reaction kinetics is consistent with the recent direct studies of \\chem{OH}-reformation. Isoprene chemistry includes the latest experimental advancements with respect to OH-recycling and alkyl nitrate chemistry. Pinenes chemistry is largely the one by the MCM but with some modifications according to the work of the Leuven's group. Finally, the chemistry of the aromatics is also borrowed from the MCM but with additional photolysis of ortho-nitrophenols leading to \\chem{HONO} formation. The sensitivity of the model to the temperature and pressure dependence of estimated \\chem{OH} rate constants and alkyl nitrate yields will be investigated and its impact on tropospheric ozone distribution will be shown.
NASA Astrophysics Data System (ADS)
Lauber, Philipp
2013-12-01
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.
Sharma, S. K.
2010-11-23
In this paper we show that identical collision terms are known by different names in gaseous plasmas and solids. Method used by plasma physicists and the one used by solid state physicists to solve Kinetic equation are also exactly same but they are also known by different names. In fact the physical explanation of damping of plasma Waves given by plasma physicists is quite similar to that given by solid state physicists to explain the absorption of acoustic waves in solids.
Lagrangian fluid description with simple applications in compressible plasma and gas dynamics
NASA Astrophysics Data System (ADS)
Schamel, Hans
2004-03-01
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 and experimental techniques are developed utilizing the Lagrangian point of view with the ultimate goal of a deeper understanding of flow dynamics. In this tutorial review we report on recent progress made in the analysis of compressible, more or less perfect flows such as plasmas and dilute gases. The equations of motion are exploited to get further insight into the formation and evolution of coherent structures, which often exhibit a singular or collapse type behavior occurring in finite time. It is argued that this technique of solution has a broad applicability due to the simplicity and generality of equations used. The focus is on four different topics, the physics of which being governed by simple fluid equations subject to initial and/or boundary conditions. Whenever possible also experimental results are mentioned. In the expansion of a semi-infinite plasma into a vacuum the energetic ion peak propagating supersonically towards the vacuum-as seen in laboratory experiments-is interpreted by means of the Lagrangian fluid description as a relic of a wave breaking scenario of the corresponding inviscid ion dynamics. The inclusion of viscosity is shown numerically to stabilize the associated density collapse giving rise to a well defined fast ion peak reminiscent of adhesive matter. In purely convection driven flows the Lagrangian flow velocity is given by its initial value and hence the Lagrangian velocity gradient tensor can be evaluated accurately to find out the appearance of singularities in density and vorticity and the emergence of new structures such as wavelets in one-dimension (1D). In cosmology referring to the pancake model of Zel'dovich and the adhesion model of Gurbatov and Saichev, both assuming a clumping of matter at the intersection points of fluid particle trajectories (i.e. at the caustics), the foam-like large-scale structure of our Universe observed recently by Chandra X-ray observatory may be explained by the 3D convection of weakly interacting dark matter. Recent developments in plasma and nanotechnology-the miniaturization and fabrication of nanoelectronic devices being one example-have reinforced the interest in the quasi-ballistic electron transport in diodes and triodes, a field which turns out to be best treated by the Lagrangian fluid description. It is shown that the well-known space-charge-limited flow given by Child-Langmuir turns out to be incorrect in cases of finite electron injection velocities at the emitting electrode. In that case it is an intrinsic bifurcation scenario which is responsible for current limitation rather than electron reflection at the virtual cathode as intuitively assumed by Langmuir. The inclusion of a Drude friction term in the electron momentum equation can be handled solely by the Lagrangian fluid description. Exploiting the formula in case of field emission it is possible to bridge ballistic and drift-dominated transport. Furthermore, the transient processes in the electron transport triggered by the switching of the anode potential are shown to be perfectly accounted for by means of the Lagrangian fluid description. Finally, by use of the Lagrangian ion fluid equations in case of a two component, current driven plasma we derive a system of two coupled scalar wave equations which involve the specific volume of ions and electrons, respectively. It has a small amplitude strange soliton solution with unusual scaling properties. In case of charge neutrality the existence of two types of collapses are predicted, one being associated with a density excavation, the other one with a density clumping as in the laser induced ion expansion problem and in the cosmic sticking matter problem. Howev
Mithaiwala, Manish; Crabtree, Chris; Ganguli, Gurudas; Rudakov, Leonid
2012-10-15
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 can survive because the background kinetic Alfven wave (KAW) turbulence creates a plateau by quasilinear (QL) diffusion in the solar wind electron distribution at small velocities. It is found that for whistler energy density of only {approx}10{sup -3} that of the kinetic Alfven waves, the quasilinear diffusion rate due to whistlers is comparable to KAW. Thus, very small amplitude whistler turbulence can have a significant consequence on the evolution of the solar wind electron distribution function.
Kinetic Mie ellipsometry to determine the time-resolved particle growth in nanodusty plasmas
NASA Astrophysics Data System (ADS)
Groth, Sebastian; Greiner, Franko; Tadsen, Benjamin; Piel, Alexander
2015-11-01
The growth of nanometer-sized particles in a reactive argon-acetylene plasma is investigated by means of kinetic single-wavelength Mie ellipsometry from the change of the polarization state of scattered light. This requires advanced measurement techniques as well as complex methods for the analysis of the measured data. Today commercial devices reduce the metrological effort, but the data analysis is still a challenging topic. We present a scheme to gain time-resolved information about the size evolution of monodisperse spherical particles and to determine their optical properties, represented by the complex refractive index N, without limiting assumptions concerning the evolution of the particle size or the need for additional ex situ diagnostics. The method is applied on typical particle growth processes at varying optical depth and compared to ex situ SEM measurements. It is shown that more complex processes, including particle etching, can be analyzed. This demonstrates the applicability of the analysis on a strongly non-linear process.
In vitro kinetics of nerve agent degradation by fresh frozen plasma (FFP).
Wille, Timo; Thiermann, Horst; Worek, Franz
2014-02-01
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
Shear viscosity of the quark-gluon plasma in a kinetic theory approach
Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.
2014-05-09
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.
NASA Astrophysics Data System (ADS)
Xu, X. Q.; Belli, E.; Bodi, K.; Candy, J.; Chang, C. S.; Cohen, R. H.; Colella, P.; Dimits, A. M.; Dorr, M. R.; Gao, Z.; Hittinger, J. A.; Ko, S.; Krasheninnikov, S.; McKee, G. R.; Nevins, W. M.; Rognlien, T. D.; Snyder, P. B.; Suh, J.; Umansky, M. V.
2009-06-01
We present edge gyrokinetic simulations of tokamak plasmas using the fully non-linear (full-f) continuum code TEMPEST. A non-linear Boltzmann model is used for the electrons. The electric field is obtained by solving the 2D gyrokinetic Poisson equation. We demonstrate the following. (1) High harmonic resonances (n > 2) significantly enhance geodesic-acoustic mode (GAM) damping at high q (tokamak safety factor), and are necessary to explain the damping observed in our TEMPEST q-scans and consistent with the experimental measurements of the scaling of the GAM amplitude with edge q95 in the absence of obvious evidence that there is a strong q-dependence of the turbulent drive and damping of the GAM. (2) The kinetic GAM exists in the edge for steep density and temperature gradients in the form of outgoing waves, its radial scale is set by the ion temperature profile, and ion temperature inhomogeneity is necessary for GAM radial propagation. (3) The development of the neoclassical electric field evolves through different phases of relaxation, including GAMs, their radial propagation and their long-time collisional decay. (4) Natural consequences of orbits in the pedestal and scrape-off layer region in divertor geometry are substantial non-Maxwellian ion distributions and parallel flow characteristics qualitatively like those observed in experiments.
Kaganovich, Igor
the cathode to the plasma for cathode materials with strongly different thermal properties is considered a large electric field at the cathode surface (like ), or a virtual cathode ( ), or double plasma sheath on the cathode material. Index Terms--Ablative wall, current structure, current-car- rying plasma, double sheath
NASA Astrophysics Data System (ADS)
Moiseev, T.; Isella, G.; Chrastina, D.; Cavallotti, C.
2009-11-01
An assessment of main electron-impact and secondary (homogeneous) gas-phase reaction rates of silane in an argon-silane-hydrogen plasma during nano-crystalline silicon deposition is presented. Radially resolved Langmuir probe plasma parameters (electron temperature and density) and electron energy distribution functions (eedfs) have been evaluated for Ar, Ar-H2 and Ar-SiH4-H2 plasma in a low-energy plasma-enhanced chemical vapour deposition reactor. Input flow rates of 50 sccm Ar, 10 sccm SiH4 and 0-50 sccm H2 have been used for a reactor pressure range 1-4 Pa. The eedfs are used to evaluate kinetic rate constants for electron-impact dissociative processes of SiH4 and H2 and to infer the amount of atomic H available for the silane-hydrogen gas-phase reaction, observing trends with an increase in H2 input flow. The evolution of silane kinetic rates with an increase in H2 input indicates that conditions corresponding to nc-Si deposition are characterized by a dominance of silane-hydrogen gas-phase rates over electron-impact dissociation rates up to about two orders of magnitude.
NASA Astrophysics Data System (ADS)
Gubchenko, Vladimir
In terms of the Vlasov-Maxwell kinetic approach we consider analytically the global Chapman- Ferraro problem (CFP) of inductive generation by the solar wind plasma flow of 3D magnetotail/solar streamer (M/S) structures in the process of electromagnetic (e.m.) interaction of the flow with the magnetized region. The input undisturbed flow is a hot collisionless plasma with an isotropic velocity distribution function (VDF) of any form, characterized by the introduced dimensionless kinetic parameter G. The 3D analytical stationary solution and set of new CFP parameters are a result of the classical simplification method based on separation of plasma particles in the velocity phase space into "trapped" and "flyby" groups that interact electromagnetically. The "flyby" particles form the "flowing media" with large scale kinetic inductive e.m. plasma eigenmodes disturbing the plasma VDF. The trapped particles in the magnetic dipole field form the prescribed "magnetic quasiparticle". The quasiparticle is described as stationary 3D spatial magnetization formed by the superposition of dipole like magnetization with N and S poles and toroidal circular magnetization without the poles. The spatial scale of the "quasiparticle", the ratio of the integral currents in the dipole and the toroidal components, and angle of mutual orientation of the components are the "quasiparticle" parameters. The "quasiparticle" models magnetic loop, sigma and helmet magnetoactive structures for the Sun and models circular and partial ring currents in the internal magnetosphere. The "quasiparticle" induces downflow the elongated quasicylindrical "dipole"-like and "toroidal"-like 3D M/S structures with fine multyrope and multicurrent sheets forming magnetic reconnection topology inside described by the package of inductive modes. Currents in the structures have resistive and diamagnetic components, which are related with "thin" structures inside "thick" current systems, respectively. Current scales are related with two different e.m. plasma kinetic spatial dispersion scales induced by the flow. They are defined by two dimensionless parameters of the plasma flow anisotropy. The anomalous skin scale defined via the "flow pulse" anisotropy stipulated by "resonant" particles which, in turn, provide resistivity in the flow. The magnetic Debye skin scale defined via the "flow energy" anisotropy formed by "nonresonant" particles which provide the diamagnetizm. We obtain these effects only in the subthermal (with respect to electrons) regime of the flow velocity. Squared ratio of two scales defines "quality" G equal to cotangent of the "losses angle" which measures the flow reactivity also and G can be a new characteristic for space weather. The value of G depends only on the form factor of the VDF and determines topology of the M/S states. We obtain the asymmetric "the resistive elongated state" for M/S when G is small with possibility of adiabatic transition to symmetric "the diamagnetic dipolized state" when G is large. Nonadiabatic transitions can be considered as substorm/CME relaxation substructure in the M/S structures.
Rosenberg, Michael Jonathan
2014-01-01
Studies of ion kinetic effects during the shock-convergence phase of inertial confinement fusion (ICF) implosions and magnetic reconnection in strongly-driven, laser-produced plasmas have been facilitated by the use of ...
Nonlinear Gyrokinetics: A Powerful Tool for the Description of Microturbulence in Magnetized Plasmas
John E. Krommes
2010-09-27
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.
Kinetic and thermodynamic properties of a convecting plasma in a two-dimensional dipole field
NASA Technical Reports Server (NTRS)
Huang, T. S.; Birmingham, T. J.
1994-01-01
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.
Reduced-fluid descriptions of toroidally confined plasma with finite-ion-temperature effects
Hsu, C.T.
1986-01-01
Fluid descriptions of toroidally confined plasma with FLR effects are studied, based on a generalized, energy-conserving, self-consistent, nonlinear reduced-fluid model (HHM). The model, derived via a fluid approach starting from moment equations, differs from Braginskii's fluid system in retaining O(rho/sub i//sup 2/) terms (where rho/sub i/ is the ion gyroradius) and most of the non-ideal effects. Hence, many of the well-known reduced-fluid models can be reproduced from HHM by simply specifying scales of some parameters such as rho/sub i/ and ..beta... On the other hand, a Pade approximation of the full FLR system, obtained from the simplified version of HHM, is also presented. This simplified model is not only energy-conserving and much easier to access, but also can be shown to retain FLR effects quite accurately. It is therefore remarked that this version should deserve further analytical and numerical studies. The possible applications of HHM are discussed in a general way so that further detailed studies can readily follow. In particular, linear toroidal drift-tearing modes with finite ion-temperature effects are studied. In addition, the non-canonical Hamiltonian theory and it's application to the reduced system are discussed. This fast developing theory has been useful for studying the equilibria and nonlinear instability of the fluid system
NASA Technical Reports Server (NTRS)
Roth, J. R.
1977-01-01
The degree of toroidal symmetry of the plasma, the number of midplane electrode rings, the configuration of electrode rings, and the location of the diagnostic instruments with respect to the electrode rings used to generate the plasma are discussed. Impurities were deliberately introduced into the plasma, and the effects of the impurity fraction on ion kinetic temperature and electron number density were observed. It is concluded that, if necessary precautions are taken, the plasma communicates extremely well along the magnetic field lines and displays a high degree of symmetry from sector to sector for a wide range of electrode ring configurations and operating conditions. Finally, some characteristic data taken under nonoptimized conditions are presented, which include the highest electron number density and the longest particle containment time (1.9 msec) observed. Also, evidence from a paired comparison test is presented which shows that the electric field acting along the minor radius of the toroidal plasma improves the plasma density and the calculated containment time more than an order of magnitude if the electric field points inward, relative to the values observed when it points (and pushes ions) radially outward.
NASA Astrophysics Data System (ADS)
Viktorov, M. E.; Golubev, S. V.; Zaitsev, V. V.; Mansfeld, D. A.
2015-05-01
We study the stability of a dense nonequilibrium plasma of the electron cyclotron resonance (ECR) discharge in an open magnetic trap immediately after the end of heating. The observed instability is accompanied by pulse-periodic generation of high-power electromagnetic radiation at a frequency that is close to the frequency of the upper hybrid resonance and the double gyrofrequency of electrons and by synchronous precipitations of fast electrons from the trap. It is shown that the observed instability is connected with excitation of plasma waves under the conditions of double plasma resonance in the decaying plasma of the ECR discharge.
Self-consistent surface kinetics models for plasma etching and deposition processes
NASA Astrophysics Data System (ADS)
Abdollahi-Alibeik, Shahram
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.
First Author = C.Z. Cheng; Jay R. Johnson
1998-07-10
A nonlinear kinetic-fluid model for high-beta plasmas with multiple ion species which can be applied to multiscale phenomena is presented. The model embeds important kinetic effects due to finite ion Larmor radius (FLR), wave-particle resonances, magnetic particle trapping, etc. in the framework of simple fluid descriptions. When further restricting to low frequency phenomena with frequencies less than the ion cyclotron frequency the kinetic-fluid model takes a simpler form in which the fluid equations of multiple ion species collapse into single-fluid density and momentum equations and a low frequency generalized Ohm's law. The kinetic effects are introduced via plasma pressure tensors for ions and electrons which are computed from particle distribution functions that are governed by the Vlasov equation or simplified plasma dynamics equations such as the gyrokinetic equation. The ion FLR effects provide a finite parallel electric field, a perpendicular velocity that modifies the ExB drift, and a gyroviscosity tensor, all of which are neglected in the usual one-fluid MHD description. Eigenmode equations are derived which include magnetosphere-ionosphere coupling effects for low frequency waves (e.g., kinetic/inertial Alfven waves and ballooning-mirror instabilities).
Carpenko, E.I.; Devaytov, B.N.; Zhukov, M.F.
1995-07-01
This report is devoted to the problem of increase of the efficiency of new plasma technology of coal burning providing minimum negative influence to the environment. In particular, common method of statement and solution of inverse kinetic problem allowing to show plasma gasification advantages is represented here.
NASA Astrophysics Data System (ADS)
Wersal, C.; Ricci, P.
2015-11-01
A first-principles self-consistent model that couples plasma and neutral physics suitable for the simulation of turbulent plasma behavior in the tokamak SOL is presented. While the plasma is modeled by the drift-reduced two fluid Braginskii equations, a kinetic model for the neutrals is developed, valid in short and in long mean free path scenarios. The model includes ionization, charge-exchange, recombination, and elastic collisional processes. The solution of the neutral kinetic equation is implemented within the GBS plasma turbulence code (Ricci et al 2012 Plasma Phys. Control. Fusion 54 124047) and it is performed by using the method of characteristics. The details of the numerical implementation are discussed. Finally, we show initial results of the first self-consistent simulations of plasma turbulence and neutral dynamics.
Ng, Chung-Sang
Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations ... http://www.aps.org/meet/DPP03 Southeast Exhibit Hall, ACC [FP1.121] Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations are smooth and comprise a complete discrete spectrum, play the same role for weakly collisional plasmas
Vlasov simulations of kinetic enhancement of Raman backscatter in laser fusion plasmas
Strozzi, D. J. (David J.)
2006-01-01
Stimulated Raman scattering (SRS) is studied in plasmas relevant to inertial confinement fusion (ICF). The Eulerian Vlasov-Maxwell code ELVIS was developed and run for this purpose. Plasma waves are heavily Landau damped ...
NASA Astrophysics Data System (ADS)
Mithaiwala, M.; Rudakov, L.; Ganguli, G.; Crabtree, C. E.
2011-12-01
The high beta solar wind plasma turbulence is dominated by the kinetic Alfven waves (KAW) [1]. Though the measured high-energy tail on the electron distribution function can be a signature of the presence of whistler waves (WW) as well [2]. In Maxwellian plasma both KAW and WW are Landau damped at high beta, and only for the specific case of WW with kperp=0 is there no Landau damping. Due to the inhomogeneous solar wind plasma these parallel propagating WW should quickly develop large perpendicular wavenumbers kperp>k|| . However, as we have shown recently using measured KAW spectra, Landau damping establishes a plateau in the parallel electron distribution function and damping is strongly diminished [3]. The theory of WW in high beta inhomogeneous plasma will be presented and the impact of the electron cyclotron resonance with WW on the evolution of the electrons high energy tail will be discussed. [1] O. Alexandrova et. al., PRL (2009) ; F. Sahraoui et. al., PRL (2010). [2] T. Nieves-Chinchilla and A. F. Vinas, JGR (2008). [3] L. Rudakov et. al., Phys. Plasma, 18, 012307 (2011).
Acharya, Ananta R. E-mail: anantaach@gmail.com; Thoms, Brian D.; Nepal, Neeraj; Eddy, Charles R.
2015-03-15
The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88?±?0.06) eV and pre-exponential factor of (1.5?±?0.5)?×?10{sup 5?}s{sup ?1}.
Yu, T; Shi, Y L; Cai, J Z; Li, C H; Lei, M T; Pan, B L; Wang, M
2015-12-01
The plasma pharmacokinetics and mammary excretion of eprinomectin were determined in dairy yaks following topical administration at a dose of 0.5 mg/kg. The kinetics of plasma and milk concentrations were analyzed using a noncompartmental model. Plasma and milk concentrations of eprinomectin increased to reach maximal concentrations of 5.45 ± 2.84 and 2.29 ± 0.90 ng/mL at a Tmax of 1.79 ± 0.57 and 2.00 ± 0.82 days, respectively. The concentration of eprinomectin in plasma was remained >0.5 ng/mL for more than 30 days after administration. The mean residence times of eprinomectin in plasma and milk were 14.73 ± 6.22 and 9.37 ± 2.81 days, respectively. The AUC value in plasma (55.89 ± 18.16 ng day/mL) was threefold greater than that in milk (18.02 ± 6.48 ng day/mL). The AUC milk/plasma ratio was 0.33 ± 0.08. The systemic availability of eprinomectin in yaks was lower than that observed value in other domestic bovines. The low level of eprinomectin excretion in milk suggests that eprinomectin can be used in yaks with zero milk-withdrawal time. The efficacy of eprinomectin against naturally acquired larvae of Hypoderma spp. was also determined in yaks. Topically administrated eprinomectin at a dose of 0.5 mg/kg was 100% efficacious against larvae of Hypoderma bovis, H. lineatum, and H. sinense. PMID:25728454
Abedi-Varaki, Mehdi; Ganjovi, Alireza; Shojaei, Fahimeh; Hassani, Zahra
2015-01-01
In this work, a zero-dimensional kinetics model is used to study the temporal behavior of different species such as charged particles, radicals and excited states inside a Dielectric Barrier Discharge plasma reactor. It is shown that, the reactor significantly reduces the concentration of nitrogen monoxide as an environmental pollutant. After a drastic increase, a decrease in the concentration of the NO2 molecules inside the reactor is seen. Nitrogen monoxide molecules with a very low concentration are produced inside the reactor and its quick conversion to other products is proved. The obtained results are compared with the existing experimental and simulation findings, whenever possible. PMID:26457188
Han, Lihao E-mail: A.H.M.Smets@tudelft.nl; Zeman, Miro; Smets, Arno H. M. E-mail: A.H.M.Smets@tudelft.nl
2015-05-25
The growth mechanism of silicon nanocrystals (Si NCs) synthesized at a high rate by means of expanding thermal plasma chemical vapor deposition technique are studied in this letter. A bimodal Gaussian size distribution is revealed from the high-resolution transmission electron microscopy images, and routes to reduce the unwanted large Si NCs are discussed. Photoluminescence and Raman spectroscopies are employed to study the size-dependent quantum confinement effect, from which the average diameters of the small Si NCs are determined. The surface oxidation kinetics of Si NCs are studied using Fourier transform infrared spectroscopy and the importance of post-deposition passivation treatments of hydrogenated crystalline silicon surfaces are demonstrated.
Kline, J L; Bertsche, W A; Kurnit, N A; Montgomery, D S; Johnson, R P; Niemann, C
2012-01-01
A nitrogen gas Raman cell system has been constructed to shift a 70 J 527 nm laser beam to 600 nm with 20 J of energy. The 600 nm probe and a 200J, 527 nm pump beam were optically mixed in a laser produced (gas jet) plasma. The beating of the two laser beams formed a ponderomotive force that can drive Kinetic Electrostatic Electron Nonlinear (KEEN) waves discovered in Vlasov-Poisson simulations by Afeyan et al [1,2]. KEEN waves were detected in these experiments where traditional plasma theory would declare there to be a spectral gap (ie no linear waves possible). The detection was done using Thomson scattering with probe wavelengths of both 351 nm and 263.5 nm.
Adamovich, Igor V; Li, Ting; Lempert, Walter R
2015-08-13
This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N2 vibrational energy transfer, reactions of excited electronic species of N2, O2, N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N2 vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H2-air, CH4-air and C2H4-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C3H8-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C3H8-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H2-air, CH4-air and C2H4-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate 'conventional' chemistry mechanism. PMID:26170427
Shie, Je-Lueng; Lee, Chiu-Hsuan; Chiou, Chyow-San; Chen, Yi-Hung; Chang, Ching-Yuan
2014-01-01
This study investigates the feasibility of applications of the plasma surface modification of photocatalysts and the removal of toluene from indoor environments. N-doped TiO2 is prepared by precipitation methods and calcined using a muffle furnace (MF) and modified by radio frequency plasma (RF) at different temperatures with light sources from a visible light lamp (VLL), a white light-emitting diode (WLED) and an ultraviolet light-emitting diode (UVLED). The operation parameters and influential factors are addressed and prepared for characteristic analysis and photo-decomposition examination. Furthermore, related kinetic models are established and used to simulate the experimental data. The characteristic analysis results show that the RF plasma-calcination method enhanced the Brunauer Emmett Teller surface area of the modified photocatalysts effectively. For the elemental analysis, the mass percentages of N for the RF-modified photocatalyst are larger than those of MF by six times. The aerodynamic diameters of the RF-modifiedphotocatalyst are all smaller than those of MF. Photocatalytic decompositions of toluene are elucidated according to the Langmuir-Hinshelwood model. Decomposition efficiencies (eta) of toluene for RF-calcined methods are all higher than those of commercial TiO2 (P25). Reaction kinetics ofphoto-decomposition reactions using RF-calcined methods with WLED are proposed. A comparison of the simulation results with experimental data is also made and indicates good agreement. All the results provide useful information and design specifications. Thus, this study shows the feasibility and potential use of plasma modification via LED in photocatalysis. PMID:24645445
NASA Astrophysics Data System (ADS)
Nakamura, Minoru; Ohno, Toshiyuki; Miyata, Kenji; Konishi, Nobutake; Suzuki, Takaya
1989-04-01
In order to study hydrogenation kinetics of post-plasma-treated chemical-vapor-deposited amorphous Si film, changes in bonding of Si and H, content of bonded hydrogen, the hydrogen profile in the depth direction of the film, and spin elimination were measured as functions of plasma exposure time and temperature (Tp) and film thickness. The activation energy of hydrogen diffusion estimated from the change of hydrogen content with Tp and exposure time was small, i.e., 0.2-0.4 eV in comparison with that of bond breaking diffusion (˜1.5 eV). Accordingly, bond breaking diffusion was minor for the post-hydrogenation of Si film by hydrogen plasma. All the observed physical quantities in this study could be explained by the fast diffusion of atomic hydrogen through weakly bound sites such as interstitials and its capture by reactive sites such as dangling bonds and weak SiSi bonds. For the capture process, preferential capture of the hydrogen by dangling bonds always occurred. The surface etching of the film, often observed in plasma hydrogenation experiments, was attributable to the evaporation of hydrosilane molecules created by adding hydrogen to the SiSi bond in the surface region.
A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas
Li, J. Huang, X. B. Cai, H. C. Yang, L. B. Xie, W. P. Duan, S. C.
2014-12-15
Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.
A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas
NASA Astrophysics Data System (ADS)
Li, J.; Huang, X. B.; Cai, H. C.; Yang, L. B.; Xie, W. P.; Duan, S. C.
2014-12-01
Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.
Statistical theory of plasma-molecular systems
NASA Astrophysics Data System (ADS)
Klimontovich, Iurii L.; Wilhelmsson, Hans; Iakimenko, Ivan P.; Zagorodnii, Anatolii G.
The fundamental principles of the kinetic theory of combined plasma-molecular systems containing free and bound charged particles are formulated. The collective electromagnetic processes occurring in unbounded and bounded plasma-molecular systems are investigated using a model description of the molecular subsystem. In particular, attention is given to the effect of boundaries on the collision integrals, kinetic coefficients, and particle distributions near the interface. A theory is developed for electromagnetic fluctuations in bounded plasma-molecular systems. The spontaneous emission spectra of plasma-molecular systems of various spatial configurations are analyzed numerically.
Impact of cold plasma on Citrobacter freundii in apple juice: inactivation kinetics and mechanisms.
Surowsky, Björn; Fröhling, Antje; Gottschalk, Nathalie; Schlüter, Oliver; Knorr, Dietrich
2014-03-17
Various studies have shown that cold plasma is capable of inactivating microorganisms located on a variety of food surfaces, food packaging materials and process equipment under atmospheric pressure conditions; however, less attention has been paid to the impact of cold plasma on microorganisms in liquid foodstuffs. The present study investigates cold plasma's ability to inactivate Citrobacter freundii in apple juice. Optical emission spectroscopy (OES) and temperature measurements were performed to characterise the plasma source. The plasma-related impact on microbial loads was evaluated by traditional plate count methods, while morphological changes were determined using scanning electron microscopy (SEM). Physiological property changes were obtained through flow cytometric measurements (membrane integrity, esterase activity and membrane potential). In addition, mathematical modelling was performed in order to achieve a reliable prediction of microbial inactivation and to establish the basis for possible industrial implementation. C. freundii loads in apple juice were reduced by about 5 log cycles after a plasma exposure of 480s using argon and 0.1% oxygen plus a subsequent storage time of 24h. The results indicate that a direct contact between bacterial cells and plasma is not necessary for achieving successful inactivation. The plasma-generated compounds in the liquid, such as H2O2 and most likely hydroperoxy radicals, are particularly responsible for microbial inactivation. PMID:24462703
NASA Astrophysics Data System (ADS)
Kim, Y.; Herrmann, H. W.; Hoffman, N. M.; Schmitt, M. J.; Bradley, P. A.; Kagan, G.; Gales, S.; Horsfield, C. J.; Rubery, M.; Leatherland, A.; Gatu Johnson, M.; Glebov, V.; Seka, W.; Marshall, F.; Stoeckl, C.; Church, J.
2014-10-01
Kinetic plasma and turbulent mix effects on inertial confinement fusion have been studied using a series of DT-filled plastic-shell implosions at the OMEGA laser facility. Plastic capsules of 4 different shell thicknesses (7.4, 15, 20, 29 micron) were shot at 2 different fill pressures in order to vary the ion mean free path compared to the size of fuel region (i.e., Knudsen number). We varied the empirical Knudsen number by a factor of 25. Measurements were obtained from the burn-averaged ion temperature and fuel areal density. Preliminary results indicate that as the empirical Knudsen number increases, fusion performances (e.g., neutron yield) increasingly deviate from hydrodynamic simulations unless turbulent mix and ion kinetic terms (e.g., enhanced ion diffusion, viscosity, thermal conduction, as well as Knudsen-layer fusion reactivity reduction) are considered. We are developing two separate simulations: one is a reduced-ion-kinetics model and the other is turbulent mix model. Two simulation results will be compared with the experimental observables.
Vlasov simulations of kinetic Alfvén waves at proton kinetic scales
Vásconez, C. L.; Valentini, F.; Veltri, P.; Camporeale, E.
2014-11-15
Kinetic Alfvén waves represent an important subject in space plasma physics, since they are thought to play a crucial role in the development of the turbulent energy cascade in the solar wind plasma at short wavelengths (of the order of the proton gyro radius ?{sub p} and/or inertial length d{sub p} and beyond). A full understanding of the physical mechanisms which govern the kinetic plasma dynamics at these scales can provide important clues on the problem of the turbulent dissipation and heating in collisionless systems. In this paper, hybrid Vlasov-Maxwell simulations are employed to analyze in detail the features of the kinetic Alfvén waves at proton kinetic scales, in typical conditions of the solar wind environment (proton plasma beta ?{sub p}?=?1). In particular, linear and nonlinear regimes of propagation of these fluctuations have been investigated in a single-wave situation, focusing on the physical processes of collisionless Landau damping and wave-particle resonant interaction. Interestingly, since for wavelengths close to d{sub p} and ?{sub p} ? 1 (for which ?{sub p} ? d{sub p}) the kinetic Alfvén waves have small phase speed compared to the proton thermal velocity, wave-particle interaction processes produce significant deformations in the core of the particle velocity distribution, appearing as phase space vortices and resulting in flat-top velocity profiles. Moreover, as the Eulerian hybrid Vlasov-Maxwell algorithm allows for a clean almost noise-free description of the velocity space, three-dimensional plots of the proton velocity distribution help to emphasize how the plasma departs from the Maxwellian configuration of thermodynamic equilibrium due to nonlinear kinetic effects.
Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas
Qiu, Z.; Chen, L.; Dept. Physics and Astronomy, Univ. of California, Irvine, California 92697-4575 ; Zonca, F.; Associazione Euratom-ENEA sulla Fusione, C.P. 65 - I-00044 - Frascati
2014-02-15
Effects of system nonuniformities and kinetic dispersiveness on the spontaneous excitation of Geodesic Acoustic Mode (GAM) by Drift Wave (DW) turbulence are investigated based on nonlinear gyrokinetic theory. The coupled nonlinear equations describing parametric decay of DW into GAM and DW lower sideband are derived and then solved both analytically and numerically to investigate the effects on the parametric decay process due to system nonuniformities, such as nonuniform diamagnetic frequency, finite radial envelope of DW pump, and kinetic dispersiveness. It is found that the parametric decay process is a convective instability for typical tokamak parameters when finite group velocities of DW and GAM associated with kinetic dispersiveness and finite radial envelope are taken into account. When, however, nonuniformity of diamagnetic frequency is taken into account, the parametric decay process becomes, time asymptotically, a quasi-exponentially growing absolute instability.
NASA Astrophysics Data System (ADS)
Mínguez, E.; Florido, R.; Rodríguez, R.; Gil, J. M.; Rubiano, J. G.; Mendoza, M. A.; Espinosa, G.; Martel, P.
2012-12-01
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.
Comparison of two-fluid and gyrokinetic models for kinetic Alfvén waves in solar and space plasmas
Yang, L.; Wu, D. J.; Wang, S. J.; Lee, L. C.
2014-09-01
An analytical comparative study of a two-fluid and a gyrokinetic model of kinetic Alfvén waves (KAWs) is presented for various solar and space plasma environments. Based on the linear KAW dispersion relation for gyrokinetics (Howes et al. 2006), the wave group velocity and electromagnetic polarizations are obtained analytically. Then the gyrokinetic wave properties are compared with those of the two-fluid model. The results show that both models agree well with each other not only in the long wavelength regime (>> the ion gyroradius ? {sub i}) for all cases considered, but also in wavelengths ?? {sub i} and <>1) ion/electron temperature ratio T {sub 0i}/T {sub 0e}, respectively. However, the fluid model calculations deviate strongly from the gyrokinetic model at scales plasma ? {sub i} can make the gyrokinetic dispersion relation of KAWs become complex and sometimes have an oscillation-like structure. With the inherent simplicity of the fluid theory, these results may improve our understanding of the applicability of the two-fluid model, and may have important implications for computer simulation studies of KAWs in the solar and space plasma surroundings.
Johnson, Derek C; Shamamian, Vasgen A; Callahan, John H; Denes, Ferencz S; Manolache, Sorin O; Dandy, David S
2003-10-15
Plasma treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. This study examines the kinetic and oxidation mechanisms of methyl tert-butyl ether (MTBE) in a dense medium plasma (DMP) reactor utilizing gas chromatography-mass spectrometry and gas chromatography-thermal conductivity techniques. A rate law is developed for the removal of MTBE from an aqueous solution in the DMP reactor. Rate constants are also derived for three reactor configurations and two pin array spin rates. The oxidation products from the treatment of MTBE-contaminated water in the DMP reactor were found to be predominately carbon dioxide, with smaller amounts of acetone, tert-butyl formate, and formaldehyde. The lack of stable intermediate products suggests that the MTBE is, to some extent, oxidized directly to carbon dioxide, making the DMP reactor a promising tool in the future remediation of water. Chemical and physical mechanisms together with carbon balances are used to describe the formation of the oxidation products and the important aspects of the plasma discharge. PMID:14594395
Tholeti, Siva Sashank; Alexeenko, Alina A.; Shneider, Mikhail N.
2014-06-15
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.
Study of surface kinetics in PECVD chamber cleaning using remote plasma source
An, Ju Jin
2008-01-01
The scope of this research work is to characterize the Transformer Coupled Toroidal Plasma (TCTP); to understand gas phase reactions and surface reactions of neutrals in the cleaning chamber by analyzing the concentration ...
Yin, Yunpeng, Ph. D. Massachusetts Institute of Technology
2007-01-01
Plasma etching processes often roughen the feature sidewalls forming anisotropic striations. A clear understanding of the origin and control of sidewall roughening is extremely desirable, particularly at the gate level ...
Kinetics modeling and 3-dimensional simulation of surface roughness during plasma etching
Guo, Wei, Ph. D. Massachusetts Institute of Technology
2009-01-01
The control of feature profiles in directional plasma etching processes is crucial as critical dimension, line-edge roughening, and other artifacts affect device performance and process yields. A profile simulator is ...
Wen, Huiqiang; Pan, Baoliang; Wang, Yuwan; Wang, Fangfei; Yang, Zhenzhong; Wang, Ming
2010-11-24
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
Descriptions of a linear device developed for research on advanced plasma imaging and dynamics
Chung, J.; Lee, K. D.; Seo, D. C.; Nam, Y. U.; Ko, W. H.; Lee, J. H.; Choi, M. C.
2009-10-15
The research on advanced plasma imaging and dynamics (RAPID) device is a newly developed linear electron cyclotron resonance (ECR) plasma device. It has a variety of axial magnetic field profiles provided by eight water-cooled magnetic coils and two dc power supplies. The positions of the magnetic coils are freely adjustable along the axial direction and the power supplies can be operated with many combinations of electrical wiring to the coils. A 6 kW 2.45 GHz magnetron is used to produce steady-state ECR plasmas with central magnetic fields of 875 and/or 437.5 G (second harmonic). The cylindrical stainless steel vacuum chamber is 300 mm in diameter and 750 mm in length and has eight radial and ten axial ports including 6-in. and 8-in. viewing windows for heating and diagnostics. Experimental observation of ECR plasma heating has been recently carried out during the initial plasma operation. The main diagnostic systems including a 94 GHz heterodyne interferometer, a high-resolution 25 channel one-dimensional array spectrometer, a single channel survey spectrometer, and an electric probe have been also prepared. The RAPID device is a flexible simulator for the understanding of tokamak edge plasma physics and new diagnostic system development. In this work, we describe the RAPID device and initial operation results.
NASA Astrophysics Data System (ADS)
Minárik, Stanislav; Va?a, Dušan
2015-11-01
Applicability of random sequential adsorption (RSA) model for the material removal during a surface plasma polishing is discussed. The mechanical nature of plasma polishing process is taken into consideration in modified version of RSA model. During the plasma polishing the surface layer is aligned such that molecules of material are removed from the surface mechanically as a consequence of the surface deformation induced by plasma particles impact. We propose modification of RSA technique to describe the reduction of material on the surface provided that sequential character of molecules release from the surface is maintained throughout the polishing process. This empirical model is able to estimate depth profile of material density on the surface during the plasma polishing. We have shown that preliminary results obtained from this model are in good agreement with experimental results. We believe that molecular dynamics simulation of the polishing process, possibly also other types of surface treatment, can be based on this model. However influence of material parameters and processing conditions (including plasma characteristics) must be taken into account using appropriate model variables.
Intrator, Thomas P.
2012-08-30
This introduction will define the plasma fourth state of matter, where we find plasmas on earth and beyond, and why they are useful. There are applications to many consumer items, fusion energy, scientific devices, satellite communications, semiconductor processing, spacecraft propulsion, and more. Since 99% of our observable universe is ionized gas, plasma physics determines many important features of astrophysics, space physics, and magnetosphere physics in our solar system. We describe some plasma characteristics, examples in nature, some useful applications, how to create plasmas. A brief introduction to the theoretical framework includes the connection between kinetic and fluid descriptions, quasi neutrality, Debye shielding, ambipolar electric fields, some plasma waves. Hands-on demonstrations follow. More complete explanations will follow next week.
High-energy kinetic theory of a particle beam generated plasma
NASA Astrophysics Data System (ADS)
Peyraud, N.
1984-08-01
The equilibrium high-energy electron distribution in a particle-beam-generated plasma is calculated. The tail of the distribution, above the first excited state, is derived from a Boltzmann equation which contains inelastic collisional processes and a continuous source term. This equation is analytically solved by a Laplace-transformation method, and (in a numerical application for the case of an argon plasma created by a high-energy electron beam between 1 and 1000 keV), the branching ratios for energy deposition in ionization and excitation states are calculated. The results are compared with those of the laser group of Orsay (Bretagne et al., 1981).
Problems and perspectives of state-to-state kinetics for high enthalpy plasma flows (Invited)
NASA Astrophysics Data System (ADS)
Colonna, Gianpiero
2014-12-01
The paper will present a brief overview of the applications of state-to-state kinetics in modeling fluid dynamics. The research activities ranges from hypersonic entry (boundary layer, shock wave) to ground test facilities, from MHD interaction to DBD flow control. The state-to-state model in fluid dynamics in the last years is rapidly diffusing, promising new interesting developments in the next future.
Optimization of kinetic parameters for the degradation of plasmid DNA in rat plasma
NASA Astrophysics Data System (ADS)
Chaudhry, Q. A.
2014-12-01
Biotechnology is a rapidly growing area of research work in the field of pharmaceutical sciences. The study of pharmacokinetics of plasmid DNA (pDNA) is an important area of research work. It has been observed that the process of gene delivery faces many troubles on the transport of pDNA towards their target sites. The topoforms of pDNA has been termed as super coiled (S-C), open circular (O-C) and linear (L), the kinetic model of which will be presented in this paper. The kinetic model gives rise to system of ordinary differential equations (ODEs), the exact solution of which has been found. The kinetic parameters, which are responsible for the degradation of super coiled, and the formation of open circular and linear topoforms have a great significance not only in vitro but for modeling of further processes as well, therefore need to be addressed in great detail. For this purpose, global optimization techniques have been adopted, thus finding the optimal results for the said model. The results of the model, while using the optimal parameters, were compared against the measured data, which gives a nice agreement.
MULTICOMPARTMENT KINETIC MODEL FOR LEAD. PART 3. LEAD IN BLOOD PLASMA AND ERYTHROCYTES
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 ...
Full kinetic simulations of plasma flow interactions with meso- and microscale magnetic dipoles
Ashida, Y.; Yamakawa, H.; Usui, H.; Miyake, Y.; Shinohara, I.; Funaki, I.; Nakamura, M.
2014-12-15
We examined the plasma flow response to meso- and microscale magnetic dipoles by performing three-dimensional full particle-in-cell simulations. We particularly focused on the formation of a magnetosphere and its dependence on the intensity of the magnetic moment. The size of a magnetic dipole immersed in a plasma flow can be characterized by a distance L from the dipole center to the position where the pressure of the local magnetic field becomes equal to the dynamic pressure of the plasma flow under the magnetohydrodynamics (MHD) approximation. In this study, we are interested in a magnetic dipole whose L is smaller than the Larmor radius of ions r{sub iL} calculated with the unperturbed dipole field at the distance L from the center. In the simulation results, we confirmed the clear formation of a magnetosphere consisting of a magnetopause and a tail region in the density profile, although the spatial scale is much smaller than the MHD scale. One of the important findings in this study is that the spatial profiles of the plasma density as well as the current flows are remarkably affected by the finite Larmor radius effect of the plasma flow, which is different from the Earth's magnetosphere. The magnetopause found in the upstream region is located at a position much closer to the dipole center than L. In the equatorial plane, we also found an asymmetric density profile with respect to the plasma flow direction, which is caused by plasma gyration in the dipole field region. The ion current layers are created in the inner region of the dipole field, and the electron current also flows in the region beyond the ion current layer because ions with a large inertia can closely approach the dipole center. Unlike the ring current structure of the Earth's magnetosphere, the current layers in the microscale dipole fields are not circularly closed around the dipole center. Since the major current is caused by the particle gyrations, the current is independently determined to be in the direction of the electron and ion gyrations, which are the same in both the upstream and downstream regions. The present analysis on the formation of a magnetosphere in the regime of a microscale magnetic dipole is significant for understanding the solar wind response to the crustal magnetic anomalies on the Moon surface, such as were recently observed by spacecraft.
Cluster observations of kinetic structures and electron acceleration within a dynamic plasma bubble
NASA Astrophysics Data System (ADS)
Zhou, Meng; Deng, Xiaohua; Ashour-Abdalla, Maha; Walker, Raymond; Pang, Ye; Tang, Chaoling; Huang, Shiyong; El-Alaoui, Mostafa; Yuan, Zhigang; Li, Huimin
2013-02-01
Fast plasma flows are believed to play important roles in transporting mass, momentum, and energy in the magnetotail during active periods, such as the magnetospheric substorms. In this paper, we present Cluster observations of a plasma-depleted flux tube, i.e., a plasma bubble associated with fast plasma flow before the onset of a substorm in the near-Earth tail around X = -18 RE. The bubble is bounded by both sharp leading (?bz/?x < 0) and trailing (?bz/?x > 0) edges. The two edges are thin current layers (approximately ion inertial length) that carry not only intense perpendicular current but also field-aligned current. The leading edge is a dipolarization front (DF) within a slow plasma flow, while the trailing edge is embedded in a super-Alfvénic convective ion jet. The electron jet speed exceeds the ion flow speed thus producing a large tangential current at the trailing edge. The electron drift is primarily given by the E × B drift. Interestingly, the trailing edge moves faster than the leading edge, which causes shrinking of the bubble and local flux pileup inside the bubble. This resulted in a further intensification of Bz, or a secondary dipolarization. Both the leading and trailing edges are tangential discontinuities that confine the electrons inside the bubble. Strong electron acceleration occurred corresponding to the secondary dipolarization, with perpendicular fluxes dominating the field-aligned fluxes. We suggest that betatron acceleration is responsible for the electron energization. Whistler waves and lower hybrid drift waves were identified inside the bubble. Their generation mechanisms and potential roles in electron dynamics are discussed.
López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Viñas, Adolfo F.; Valdivia, J. Alejandro
2014-09-15
We use a kinetic treatment to study the linear transverse dispersion relation for a magnetized isotropic relativistic electron-positron plasma with finite relativistic temperature. The explicit linear dispersion relation for electromagnetic waves propagating along a constant background magnetic field is presented, including an analytical continuation to the whole complex frequency plane for the case of Maxwell-Jüttner velocity distribution functions. This dispersion relation is studied numerically for various temperatures. For left-handed solutions, the system presents two branches, the electromagnetic ordinary mode and the Alfvén mode. In the low frequency regime, the Alfvén branch has two dispersive zones, the normal zone (where ??/?k?>?0) and an anomalous zone (where ??/?k?plasma frequency with the temperature. We complemented the analytical and numerical approaches with relativistic full particle simulations, which consistently agree with the analytical results.
Arbitrary amplitude double layers in warm dust kinetic Alfven wave plasmas
Gogoi, Runmoni; Devi, Nirupama
2008-07-15
Large amplitude electrostatic structures associated with low-frequency dust kinetic Alfvenic waves are investigated under the pressure (temperature) gradient indicative of dust dynamics. The set of equations governing the dust dynamics, Boltzmann electrons, ions and Maxwell's equation have been reduced to a single equation known as the Sagdeev potential equation. Parameter ranges for the existence of arbitrary amplitude double layers are observed. Exact analytical expressions for the energy integral is obtained and computed numerically through which sub-Alfvenic arbitrary amplitude rarefactive double layers are found to exist.
Spatially Modulated Phase in the Holographic Description of Quark-Gluon Plasma
Ooguri, Hirosi; Park, Chang-Soon
2011-02-11
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-Nordstroem 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 0.8N{sub f} fm{sup -3} at temperature 150 MeV.
Spatially modulated phase in the holographic description of quark-gluon plasma.
Ooguri, Hirosi; Park, Chang-Soon
2011-02-11
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
NASA Technical Reports Server (NTRS)
Radhakrishnan, Krishnan; Bittker, David A.
1994-01-01
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.
Vasylkiv, Oleg; Demirskyi, Dmytro; Sakka, Yoshio; Ragulya, Andrey; Borodianska, Hanna
2012-06-01
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
Kinetic simulations of the self-focusing and dissipation of finite-width electron plasma waves.
Winjum, B J; Berger, R L; Chapman, T; Banks, J W; Brunner, S
2013-09-01
Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus ?m relative to the initial width ?0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability ?TPMI divided by the loss rate of field energy ?E to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing ?TPMI/?E?1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)]. PMID:25166675
A Variational Formulation of Macro-Particle Algorithms for Kinetic Plasma Simulations
NASA Astrophysics Data System (ADS)
Shadwick, B. A.
2013-10-01
Macro-particle based simulations methods are in widespread use in plasma physics; their computational efficiency and intuitive nature are largely responsible for their longevity. In the main, these algorithms are formulated by approximating the continuous equations of motion. For systems governed by a variational principle (such as collisionless plasmas), approximations of the equations of motion is known to introduce anomalous behavior, especially in system invariants. We present a variational formulation of particle algorithms for plasma simulation based on a reduction of the distribution function onto a finite collection of macro-particles. As in the usual Particle-In-Cell (PIC) formulation, these macro-particles have a definite momentum and are spatially extended. The primary advantage of this approach is the preservation of the link between symmetries and conservation laws. For example, nothing in the reduction introduces explicit time dependence to the system and, therefore, the continuous-time equations of motion exactly conserve energy; thus, these models are free of grid-heating. In addition, the variational formulation allows for constructing models of arbitrary spatial and temporal order. In contrast, the overall accuracy of the usual PIC algorithm is at most second due to the nature of the force interpolation between the gridded field quantities and the (continuous) particle position. Again in contrast to the usual PIC algorithm, here the macro-particle shape is arbitrary; the spatial extent is completely decoupled from both the grid-size and the ``smoothness'' of the shape; smoother particle shapes are not necessarily larger. For simplicity, we restrict our discussion to one-dimensional, non-relativistic, un-magnetized, electrostatic plasmas. We comment on the extension to the electromagnetic case. Supported by the US DoE under contract numbers DE-FG02-08ER55000 and DE-SC0008382.
Trapping oscillations, discrete particle effects and kinetic theory of collisionless plasma
F. Doveil; M-C. Firpo; Y. Elskens; D. Guyomarc'h; M. Poleni; P. Bertrand
2001-03-09
Effects induced by the finite number $N$ of particles on the evolution of a monochromatic electrostatic perturbation in a collisionless plasma are investigated. For growth as well as damping of a single wave, discrete particle numerical simulations show a $N$-dependent long time behavior which differs from the numerical errors incurred by vlasovian approaches and follows from the pulsating separatrix crossing dynamics of individual particles.
Schindler, K.; Birn, J.; Hesse, M.
2012-08-15
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.
NASA Technical Reports Server (NTRS)
Schindler, K.; Birn, J.; Hesse, M.
2012-01-01
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.
A kinetic equation for linear fractional stable motion with applications to space plasma physics
Nicholas W. Watkins; Daniel Credgington; Raul Sanchez; Sandra C. Chapman
2008-03-19
Levy flights and fractional Brownian motion (fBm) have become exemplars of the heavy tailed jumps and long-ranged memory seen in space physics and elsewhere. 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-dubbed "ambivalent" by Brockmann et al (2006}-have for many years been modelled using the fully fractional (FF) kinetic equation for the continuous time random walk (CTRW), with power laws in the pdfs 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 develop earlier comments by Lutz (2001) on how fBm differs from its fractional time process counterpart. We go on to argue more physically why LFSM and the FFCTRW might indeed be expected to differ, and discuss some preliminary results on the scaling of burst "sizes" and "durations" in LFSM time series, with applications to modelling existing observations in space physics.
Oscillatory patterns in three-dimensional kinetic simulations of space plasma
NASA Astrophysics Data System (ADS)
Olshevsky, Vyacheslav; Deca, Jan; Divin, Andrey; Lapenta, Giovanni; Markidis, Stefano
2015-04-01
We analyse kinetic simulations of the relaxation of a magnetic field configuration with multiple null-points. The power spectral density of the magnetic field is dissipative and exhibits two breaks: at ion-inertial and at electron-gyration scales; the slopes are steeper than observed in solar wind. Although different simulations in the same configuration show similar energetics, the local evolution pattern is rather chaotic. Most of the null-points in the simulations are of the spiral type, they are surrounded by twisted field lines, and powerful currents establish through them forming Z-pinches. Various instabilities are associated with the current channels, especially prominent is the kinking which drives secondary magnetic reconnection that dissipates the magnetic energy. In some regions the current channels produce thin secondary threads that show lower hybrid drift-like oscillatory characteristics. Oscillatory patterns are also detected at the halo boundary above dipolar lunar anomalies in 3-D kinetic simulations. It is found that they are (at least partially) in relation to the position of the B=0 line across the halo formed due to the opposing directions of the dipolar and interplanetary magnetic field in the simulation set-up, as well is to the strength of both fields and the solar wind parameters. We investigate and compare the detailed characteristics of small-scale wave patterns in both 3D simulations of null points and lunar magnetic anomalies.
A kinetic-MHD model for studying low frequency multiscale phenomena
Cheng, C.Z.; Johnson, J.R.
1996-05-01
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.
Ion plasma wave and its instability in interpenetrating plasmas
Vranjes, J.; Kono, M.
2014-04-15
Some essential features of the ion plasma wave in both kinetic and fluid descriptions are presented. The wave develops at wavelengths shorter than the electron Debye radius. Thermal motion of electrons at this scale is such that they overshoot the electrostatic potential perturbation caused by ion bunching, which consequently propagates as an unshielded wave, completely unaffected by electron dynamics. So in the simplest fluid description, the electrons can be taken as a fixed background. However, in the presence of magnetic field and for the electron gyro-radius shorter than the Debye radius, electrons can participate in the wave and can increase its damping rate. This is determined by the ratio of the electron gyro-radius and the Debye radius. In interpenetrating plasmas (when one plasma drifts through another), the ion plasma wave can easily become growing and this growth rate is quantitatively presented for the case of an argon plasma.
The Ulysses solar wind plasma investigation: Description and initial in-ecliptic results
Bame, S. J.; Phillips, J. L.; McComas, D. J.; Gosling, J. T.; Goldstein, B. E.
1991-01-01
During the in-ecliptic flight of Ulysses from the Earth toward its encounter with Jupiter, the Los Alamos solar wind plasma experiment has performed well. Briefly described, the instrumentation contains two independent electrostatic analyzers, one for ions and one for electrons. Initial analysis of solar wind electron core temperatures obtained between 1.15 and 3.76 AU yields a gradient of T {proportional to} R{sup {minus}0.7} which is flatter than expected for adiabatic expansion of a single-temperature Maxwellian velocity distribution and steeper than that obtained from Mariner-Voyager.
Microscopic Lagrangian description of warm plasmas. III - Nonlinear wave-particle interaction
NASA Technical Reports Server (NTRS)
Galloway, J. J.; Crawford, F. W.
1977-01-01
The averaged-Lagrangian method is applied to nonlinear wave-particle interactions in an infinite, homogeneous, magnetic-field-free plasma. The specific example of Langmuir waves is considered, and the combined effects of four-wave interactions and wave-particle interactions are treated. It is demonstrated how the latter lead to diffusion in velocity space, and the quasilinear diffusion equation is derived. The analysis is generalized to the random phase approximation. The paper concludes with a summary of the method as applied in Parts 1-3 of the paper.
Macroscopic Lagrangian description of warm plasmas. I Formulation of the Lagrangian
NASA Technical Reports Server (NTRS)
Peng, Y.-K. M.; Crawford, F. W.
1983-01-01
A macroscopic Lagrangian is derived which includes a pressure tensor, heat conduction, and elastic collisions. Its Euler-Lagrange equations are shown to be the Maxwell equations and the macroscopic force law. The corresponding Hamiltonian is derived, and Hamilton's canonical equations are also demonstrated to lead to the Maxwell equations and the macroscopic force law. The treatment is facilitated by working in a mixture of Eulerian coordinates (for the fields) and Lagrangian coordinates (for the particle motions), and the introduction of a macroscopic potential expressed in terms of the plasma thermal energy and the energy losses by heat conduction.
Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics
Vitelaru, Catalin; National Institute for Optoelectronics, Magurele-Bucharest, RO 077125 ; Lundin, Daniel; Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 ; Brenning, Nils; Minea, Tiberiu
2013-09-02
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.
Convective Raman amplification of light pulses causing kinetic inflation in inertial fusion plasmas
Ellis, I. N.; Strozzi, D. J.; Williams, E. A.; Winjum, B. J.; Tsung, F. S.; Mori, W. B.; Fahlen, J. E.; Grismayer, T.
2012-11-15
We perform 1D particle-in-cell (PIC) simulations using OSIRIS, which model a short-duration ({approx}500{omega}{sub 0}{sup -1} FWHM) scattered light seed pulse in the presence of a constant counter-propagating pump laser with an intensity far below the absolute instability threshold. The seed undergoes linear convective Raman amplification and dominates over fluctuations due to particle discreteness. Our simulation results are in good agreement with results from a coupled-mode solver when we take into account special relativity and the use of finite size PIC simulation particles. We present linear gain spectra including both effects. Extending the PIC simulations past when the seed exits the simulation domain reveals bursts of large-amplitude scattering in many cases, which does not occur in simulations without the seed pulse. These bursts can have amplitudes several times greater than the amplified seed pulse, and we demonstrate that this large-amplitude scattering is the result of kinetic inflation by examining trapped particle orbits. This large-amplitude scattering is caused by the seed modifying the distribution function earlier in the simulation. We perform some simulations with longer duration seeds, which lead to parts of the seeds undergoing kinetic inflation and reaching amplitudes several times more than the steady-state linear theory results. Simulations with continuous seeds demonstrate that the onset of inflation depends on seed wavelength and incident intensity, and we observe oscillations in the reflectivity at a frequency equal to the difference between the seed frequency and the frequency at which the inflationary stimulated Raman scattering grows.
Schlickeiser, R.; Krakau, S.; Supsar, M. E-mail: steffen.krakau@rub.de
2013-11-01
The interaction of TeV gamma-rays from distant blazars with the extragalactic background light produces relativistic electron-positron pair beams by the photon-photon annihilation process. Using the linear instability analysis in the kinetic limit, which properly accounts for the longitudinal and the small but finite perpendicular momentum spread in the pair momentum distribution function, the growth rate of parallel propagating electrostatic oscillations in the intergalactic medium is calculated. Contrary to the claims of Miniati and Elyiv, we find that neither the longitudinal nor the perpendicular spread in the relativistic pair distribution function significantly affect the electrostatic growth rates. The maximum kinetic growth rate for no perpendicular spread is even about an order of magnitude greater than the corresponding reactive maximum growth rate. The reduction factors in the maximum growth rate due to the finite perpendicular spread in the pair distribution function are tiny and always less than 10{sup –4}. We confirm earlier conclusions by Broderick et al. and our group that the created pair beam distribution function is quickly unstable in the unmagnetized intergalactic medium. Therefore, there is no need to require the existence of small intergalactic magnetic fields to scatter the produced pairs, so that the explanation (made by several authors) for the Fermi non-detection of the inverse Compton scattered GeV gamma-rays by a finite deflecting intergalactic magnetic field is not necessary. In particular, the various derived lower bounds for the intergalactic magnetic fields are invalid due to the pair beam instability argument.
Modeling the chemical kinetics of atmospheric plasma for cell treatment in a liquid solution
Kim, H. Y.; Kang, S. K.; Lee, H. Wk.; Lee, H. W.; Kim, G. C.; Lee, J. K.
2012-07-15
Low temperature atmospheric pressure plasmas have been known to be effective for living cell inactivation in a liquid solution but it is not clear yet which species are key factors for the cell treatment. Using a global model, we elucidate the processes through which pH level in the solution is changed from neutral to acidic after plasma exposure and key components with pH and air variation. First, pH level in a liquid solution is changed by He{sup +} and He(2{sup 1}S) radicals. Second, O{sub 3} density decreases as pH level in the solution decreases and air concentration decreases. It can be a method of removing O{sub 3} that causes chest pain and damages lung tissue when the density is very high. H{sub 2}O{sub 2}, HO{sub 2}, and NO radicals are found to be key factors for cell inactivation in the solution with pH and air variation.
Kinetic Simulations of the Self-Focusing and Dissipation of Finite-Width Electron Plasma Waves
Winjum, B. J.; Berger, R. L.; Chapman, T.; Banks, J. W.; Brunner, S.
2013-09-01
Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus ?m relative to the initial width ?0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability ?_{TPMI} divided by the loss rate of field energy ?_{E} to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing ?_{TPMI}/?_{E}~1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)].
Continuum Kinetic Plasma Modeling Using a Conservative 4th-Order Method with AMR
NASA Astrophysics Data System (ADS)
Vogman, Genia; Colella, Phillip
2012-10-01
When the number of particles in a Debye sphere is large, a plasma can be accurately represented by a distribution function, which can be treated as a continuous incompressible fluid in phase space. In the most general case the evolution of such a distribution function is described by the 6D Boltzmann-Maxwell partial differential equation system. To address the challenges associated with solving a 6D hyperbolic governing equation, a simpler 3D Vlasov-Poisson system is considered. A 4th-order accurate Vlasov-Poisson model has been developed in one spatial and two velocity dimensions. The governing equation is cast in conservation law form and is solved with a finite volume representation. Adaptive mesh refinement (AMR) is used to allow for efficient use of computational resources while maintaining desired levels of resolution. The model employs a flux limiter to remedy non-physical effects such as numerical dispersion. The model is tested on the two-stream, beam-plasma, and Dory-Guest-Harris instabilities. All results are compared with linear theory.
Nartikova, V F; Egorova, T P; Rets, E V; Paskhina, T S
1986-03-01
A relatively simple procedure for isolation and purification of human blood plasma kallikrein (HPK) by QAE-Sephadex A-50 SP-Sephadex C-50 and affinity chromatography on Sepharose 4B with immobilized soybean trypsin inhibitor with the activity yield of about 40% has been developed. The method allows for simultaneous isolation of low (LMW) and high molecular weight (HMW) kininogens from the same HPK sample. HPK preparations are homogeneous upon 7.5% polyacrylamide gel electrophoresis in the presence of 0.1% SDS; its Mr is 90,000. After treatment with beta-mercaptoethanol, HPK dissociates into two fragments with Mr of 43,000 and 37,000. HPK preparations have high specific activities of esterase (31 microM/min), amidase (78 microM/min), and kininogenase (420 micrograms equiv. bradikinin/min). The high degree of protein purification was demonstrated by titration of active centers with 4-methylumbelliferylguanidine benzoate. The values of equilibrium dissociation constants for the HPK complex with aprotinin (Ki) equal to 1 X 10(-8) M (ethyl ester of N-alpha-benzoyl-L-arginine) and 1,5 X 10(-9) M (HMW) were determined. The kinetics of HPK-induced liberation of bradikinin from purified preparations of HMW and LMW was studied. The kinetic parameters (Km, kcat and kcat/Km) of this reaction suggest a high affinity of HPK for HMW, but not for LMW. LMW does not compete with HMW for the enzyme active center. It is assumed that LMW is not a physiological substrate for HPK. PMID:3634630
Davidson, R.C.; Chen, C.
1997-08-01
A kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field B{sup sol}({rvec x}) is developed. The analysis is carried out for a thin beam with characteristic beam radius r{sub b} {much_lt} S, and directed axial momentum {gamma}{sub b}m{beta}{sub b}c (in the z-direction) large compared with the transverse momentum and axial momentum spread of the beam particles. Making use of the nonlinear Vlasov-Maxwell equations for general distribution function f{sub b}({rvec x},{rvec p},t) and self-consistent electrostatic field consistent with the thin-beam approximation, the kinetic model is used to investigate detailed beam equilibrium properties for a variety of distribution functions. Examples are presented both for the case of a uniform solenoidal focusing field B{sub z}(z) = B{sub 0} = const. and for the case of a periodic solenoidal focusing field B{sub z}(z + S) = B{sub z}(z). The nonlinear Vlasov-Maxwell equations are simplified in the thin-beam approximation, and an alternative Hamiltonian formulation is developed that is particularly well-suited to intense beam propagation in periodic focusing systems. Based on the present analysis, the Vlasov-Maxwell description of intense nonneutral beam propagation through a periodic solenoidal focusing field {rvec B}{sup sol}({rvec x}) is found to be remarkably tractable and rich in physics content. The Vlasov-Maxwell formalism developed here can be extended in a straightforward manner to investigate detailed stability behavior for perturbations about specific choices of beam equilibria.
Quantitative description of ion transport via plasma membrane of yeast and small cells
Volkov, Vadim
2015-01-01
Modeling of ion transport via plasma membrane needs identification and quantitative understanding of the involved processes. Brief characterization of main ion transport systems of a yeast cell (Pma1, Ena1, TOK1, Nha1, Trk1, Trk2, non-selective cation conductance) and determining the exact number of molecules of each transporter per a typical cell allow us to predict the corresponding ion flows. In this review a comparison of ion transport in small yeast cell and several animal cell types is provided. The importance of cell volume to surface ratio is emphasized. The role of cell wall and lipid rafts is discussed in respect to required increase in spatial and temporary resolution of measurements. Conclusions are formulated to describe specific features of ion transport in a yeast cell. Potential directions of future research are outlined based on the assumptions. PMID:26113853
Quantitative description of ion transport via plasma membrane of yeast and small cells
Vadim Volkov
2012-12-18
Modelling of ion transport via plasma membrane needs identification and quantitative understanding of the involved processes. Brief characterisation of ion transport systems of a yeast cell (Pma1, Ena1, TOK1, Nha1, Trk1, Trk2, non-selective cation conductance) and estimates concerning the number of molecules of each transporter per a cell allow predicting the corresponding ion flows. Comparison of ion transport in small yeast cell and several animal cell types is provided and importance of cell volume to surface ratio is stressed. Role of cell wall and lipid rafts is discussed in aspect of required increase in spatial and temporary resolution of measurements. Conclusions are formulated to describe specific features of ion transport in a yeast cell. Potential directions of future research are outlined based on the assumptions.
_____________________________________________ · Description Fusion energy is released by burning light elements using nuclear reactions which consume mass reactive fusion fuel is a 50/50 mix of deuterium (D) and tritium (T) which requires fuel temperatures but higher temperatures and better confinement is required. In magnetic fusion, plasmas are heated
NASA Astrophysics Data System (ADS)
Rekaa, Vegard L.; Chapman, Sandra C.; Dendy, Richard O.
2014-05-01
Supernova remnant and heliopause termination shock plasmas may contain significant populations of minority heavy ions such as alpha-particles, with relative number densities n?/ni up to 50%. Fully self-consistent kinetic simulations of quasi-perpendicular, supercritical shocks can show non-steady, reforming solutions with consequences for ion acceleration local to the shock. We present the first set of particle-in-cell simulations that span the entire range of values of n?/ni from zero to one, where the two ion species and electrons are all treated fully self-consistently. These '1.5D' simulations evolve the full three dimensional particle trajectories and electromagnetic vector fields as a function of one space co-ordinate and time. The simulated supercritical (Mach number ~ 8) shocks have perpendicular geometry, plasma ? = 0.15, upstream magnetic field B1 = 10-7T and particle density n ? 107m-3. Crucial to the time evolving phenomenology of the shocks and particles at different n?/ni are the interplay between the differing characteristic gyroscales of the two ion species. Ions can gain energy both directly by acceleration in the electromagnetic foot-ramp region of the shock, and in the strongly fluctuating fields downstream. The downstream field fluctuations are driven by the free energy that both ion species gain in their initial interaction with the shock. The details of all these processes, and their efficiency for energization, are found to depend on n?/ni. Disclaimer: This work was partly funded by the UK Engineering and Physics Sciences Research Council under grant EP/G003955 and by The European Communities under the contract of association between Euratom and CCFE. The views and opinions expressed herein do not necessarily represent those of the European Communities.
Kinetic simulation of the O-X conversion process in dense magnetized plasmas
Asgarian, M Ali; Parvazian, A; Trines, R
2013-01-01
The ordinary-extraordinary-Bernstein (O-X-B) double conversion is considered and simulated with a kinetic particle model vs full wave model for parameters of the TJ-II stellarator. This simulation has been done with the particle-in-cell code, XOOPIC (X11-based object-oriented particle-incell). XOOPIC is able to model the non-monotonic density and magnetic profile of TJ-II. The first step of conversion, O-X conversion, is observed clearly. By applying some optimizations such as increasing the number of computational particles in the region of the X-B conversion, the simulation of the second step is also possible. By considering the electric and magnetic components of launched and reflected waves, the O-mode wave and the X-mode wave can be easily detected. Via considering the power of launched O-mode wave and converted X-mode wave, the efficiency of O-X conversion for the best theoretical launch angle is obtained, which is in good agreement with previous computed efficiencies via full-wave simulations. For the ...
Mehdian, H. Kargarian, A.; Hajisharifi, K.
2015-06-15
In this paper, the effect of an external inhomogeneous magnetic field on the high intensity laser absorption rate in a sub-critical plasma has been investigated by employing a relativistic electromagnetic 1.5 dimensional particle-in-cell code. Relying on the effective nonlinear phenomena such as phase-mixing and scattering, this study shows that in a finite-size plasma the laser absorption increases with inhomogeneity of the magnetic field (i.e., reduction of characteristic length of inhomogeneous magnetic field, ?{sub p}) before exiting a considerable amount of laser energy from the plasma due to scattering process. On the other hand, the presence of the external inhomogeneous magnetic field causes the maximum absorption of laser to occur at a shorter time. Moreover, study of the kinetic results associated with the distribution function of plasma particles shows that, in a special range of the plasma density and the characteristic length of inhomogeneous magnetic field, a considerable amount of laser energy is transferred to the particles producing a population of electrons with kinetic energy along the laser direction.
Hosseini Jenab, S. M.; Kourakis, I.
2014-04-15
A series of numerical simulations based on a recurrence-free Vlasov kinetic algorithm presented earlier [Abbasi et al., Phys. Rev. E 84, 036702 (2011)] are reported. Electron-ion plasmas and three-component (electron-ion-dust) dusty, or complex, plasmas are considered, via independent simulations. Considering all plasma components modeled through a kinetic approach, the nonlinear behavior of ionic scale acoustic excitations is investigated. The focus is on Bernstein–Greene–Kruskal (BGK) modes generated during the simulations. In particular, we aim at investigating the parametric dependence of the characteristics of BGK structures, namely of their time periodicity (?{sub trap}) and their amplitude, on the electron-to-ion temperature ratio and on the dust concentration. In electron-ion plasma, an exponential relation between ?{sub trap} and the amplitude of BGK modes and the electron-to-ion temperature ratio is observed. It is argued that both characteristics, namely, the periodicity ?{sub trap} and amplitude, are also related to the size of the phase-space vortex which is associated with BGK mode creation. In dusty plasmas, BGK modes characteristics appear to depend on the dust particle density linearly.
The kinetics of grain growth in near-micrometre grain size copper produced by spark plasma sintering
NASA Astrophysics Data System (ADS)
Zhu, K. N.; Ruan, Q.; Godfrey, A.
2015-08-01
Samples of copper with a grain size in the near-micrometre regime and in a nearly fully recrystallized condition have been prepared by a spark plasma sintering (SPS) process. The thermal stability of these samples in the temperature range from 950 to 1050 °C has been investigated by an analysis of the kinetics of grain growth, based on microstructural measurements using electron backscatter diffraction. In the temperature range from 950 to 1000 °C the activation energy for grain growth is approx. 300 kJ mol-1, corresponding to a value one and a half times the activation energy for self-diffusion in pure copper. In the temperature range from 1000 to 1050 °C the activation energy for grain growth is found to decrease, although annealing in this temperature range additionally results in non-uniform grain growth. For preparation of samples with a desired uniform grain size at present the best method appears to be via control of the temperature during the SPS process.
Janulewicz, K.A.; Tuemmler, J.; Priebe, G.; Nickles, P.V.
2005-10-15
Some aspects of plasma kinetics in a Ni-like Ag soft x-ray laser have been analyzed, starting from the real shape of the pump laser pulse measured with a third-order correlator. The role for pump energy reduction of a complex pump pulse structure at a low intensity level has been identified, and the modeling results on the gain lifetime correspond well with the length of the output x-ray pulse measured in the experiment.
Zonca, Fulvio
Theory and simulation of discrete kinetic beta induced AlfvÃ©n eigenmode in tokamak plasmas.1088/0741-3335/52/11/115005 Theory and simulation of discrete kinetic beta induced AlfvÂ´en eigenmode in tokamak plasmas X Wang1,2 , F Zonca1,3 and L Chen1,2 1 Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou
Human muscle sympathetic nerve activity and plasma noradrenaline kinetics in space
NASA Technical Reports Server (NTRS)
Ertl, Andrew C.; Diedrich, Andre; Biaggioni, Italo; Levine, Benjamin D.; Robertson, Rose Marie; Cox, James F.; Zuckerman, Julie H.; Pawelczyk, James A.; Ray, Chester A.; Buckey, Jay C Jr; Lane, Lynda D.; Shiavi, Richard; Gaffney, F. Andrew; Costa, Fernando; Holt, Carol; Blomqvist, C. Gunnar; Eckberg, Dwain L.; Baisch, Friedhelm J.; Robertson, David
2002-01-01
Astronauts returning from space have reduced red blood cell masses, hypovolaemia and orthostatic intolerance, marked by greater cardio-acceleration during standing than before spaceflight, and in some, orthostatic hypotension and presyncope. Adaptation of the sympathetic nervous system occurring during spaceflight may be responsible for these postflight alterations. We tested the hypotheses that exposure to microgravity reduces sympathetic neural outflow and impairs sympathetic neural responses to orthostatic stress. We measured heart rate, photoplethysmographic finger arterial pressure, peroneal nerve muscle sympathetic activity and plasma noradrenaline spillover and clearance, in male astronauts before, during (flight day 12 or 13) and after the 16 day Neurolab space shuttle mission. Measurements were made during supine rest and orthostatic stress, as simulated on Earth and in space by 7 min periods of 15 and 30 mmHg lower body suction. Mean (+/- S.E.M.) heart rates before lower body suction were similar pre-flight and in flight. Heart rate responses to -30 mmHg were greater in flight (from 56 +/- 4 to 72 +/- 4 beats min(-1)) than pre-flight (from 56 +/- 4 at rest to 62 +/- 4 beats min(-1), P < 0.05). Noradrenaline spillover and clearance were increased from pre-flight levels during baseline periods and during lower body suction, both in flight (n = 3) and on post-flight days 1 or 2 (n = 5, P < 0.05). In-flight baseline sympathetic nerve activity was increased above pre-flight levels (by 10-33 %) in the same three subjects in whom noradrenaline spillover and clearance were increased. The sympathetic response to 30 mmHg lower body suction was at pre-flight levels or higher in each subject (35 pre-flight vs. 40 bursts min(-1) in flight). No astronaut experienced presyncope during lower body suction in space (or during upright tilt following the Neurolab mission). We conclude that in space, baseline sympathetic neural outflow is increased moderately and sympathetic responses to lower body suction are exaggerated. Therefore, notwithstanding hypovolaemia, astronauts respond normally to simulated orthostatic stress and are able to maintain their arterial pressures at normal levels.
Species separation and kinetic effects in collisional plasma shocksa) C. Bellei, H. Rinderknecht, A://scitation.aip.org/termsconditions. Downloaded to IP: 198.125.181.33 On: Mon, 19 May 2014 15:17:29 #12;Species separation and kinetic effects against an average-species calculation, confirming effects of species separation and differential heating
NASA Astrophysics Data System (ADS)
Gubchenko, Vladimir
The task was to provide an analytical elementary magnetosphere-like model in kinetics for verification of the 3D EM PIC codes created for space/aerospace and HED plasmas applications. Kinetic approach versus cold MHD approach takes into account different behavior in the EM fields of resonant and non resonant particles in the velocity phase space, which appears via shape characteristics of the particle velocity distribution function (PVDF) and via the spatial dispersion effect forming the collisionless dissipation in the EM fields. The external flow is a hot collisionless plasma characterized by the particle velocity distribution function (PVDF) with different shapes: Maxwellian, kappa, etc. The flow is in a “hot regime”: it can be supersonic but its velocity remains less the thermal velocity of the electrons. The “internal” part of the magnetosphere formed by trapped particles is the prescribed 3D stationary magnetization considered as a spherical “quasiparticle” with internal magnetodipole and toroidal moments represented as a broadband EM driver. We obtain after the linearization of Vlasov/Maxwell equations a self-consistent 3D large scale kinetic solution of the classic problem. Namely, we: model the “outer” part of the magnetosphere formed by external hot plasma flow of the flyby particles. Solution of the Vlasov equation expressed via a tensor of dielectric permittivity of nonmagnetized and magnetized flowing plasma. Here, we obtain the direct kinetic dissipative effect of the magnetotail formation and the opposite diamagnetic effect of the magnetosphere “dipolization”. We get MHD wave cone in flow magnetized by external guiding magnetic (GM) field. Magnetosphere in our consideration is a 3D dissipative “wave” package structure of the skinned EM fields formed by the “waves” excited at frequency bands where we obtain negative values and singularities (resonances) of squared EM refractive index of the cold plasma. The hot regime provides kinetic effects near singularities depending from reshaping of the PVDF. Flow behaves as metal with generation of inductive conductive currents or as dielectric with diamagnetic polarization currents. The basic high beta flow regime is equivalent to the absence of the GM field, nonmagnetized plasma flow particles, and operation with a diagonal tensor, that is, the Chapman approach to magnetosphere modeling considered often as “minimagnetosphere” modeling. The magnetosphere formation is the wide band Cerenkov resonance effect of interaction of the magnetization with “resonant” and “nonresonant” plasma flow particles. We also obtain the resistive (“thin”) scale of anomalous skin which is related with process of resonant particle acceleration by inductive fields providing EM dissipation and the effect of magnetic reconnection. We get also the diamagnetic (“thick”) scale which is related to the magnetic field action on the plasma flow particles. The ratio of the diamagnetic to resistive current densities in the 3D magnetosphere forms the flow quality parameter G. The EM value G depends on the shape of the PDF of the incoming flow only. The parameter G characterizes the EM part of the “space weather”. For the Maxwellian PDF G is much less then 1 - metal-like flow and the formation of the magnetotail state, reshaping PDF to G more then 1 - diamagnetic flow, which provides a transition to the dipolized state. Note that the acoustic Mach number characterizes the SW compressibility and the shock wave formation effect only. The low-beta hot-flow regime is equivalent to the magnetized by the GM field plasma flow (Dangey approach). Here, the tensor is non diagonal, and by the GM field action plasma became MHD transparent in the nontransparent band, which provides MHD radiation in the Alvenic cone. Negative values of the squared refractive index are at the cyclotron and at the modified Cerenkov EM narrow band frequency resonances for the EM fields with ordinary and non ordinary polarizations. This takes place for the packages with the “waves”
NASA Astrophysics Data System (ADS)
Altunpak, Yahya; Akbulut, Hatem; Üstel, Fatih
2010-02-01
The Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.
Ronald C. Davidson; Hong Qin; Stephan I. Tzenov; Edward A. Startsev
2003-02-26
The Vlasov-Maxwell equations are used to investigate the nonlinear evolution of an intense sheet beam with distribution function f{sub b}(x,x{prime},s) propagating through a periodic focusing lattice k{sub x}(s+S) = k{sub x}(s), where S = const is the lattice period. The analysis considers the special class of distribution functions with uniform phase-space density f{sub b}(x,x{prime},s) = A = const inside of the simply connected boundary curves, x{prime}{sub +}(x,s) and x{prime}{sub -}(x,s), in the two-dimensional phase space (x,x{prime}). Coupled nonlinear equations are derived describing the self-consistent evolution of the boundary curves, x{prime}{sub +}(x,s) and x{prime}{sub -}(x,s), and the self-field potential {psi}(x,s) = e{sub b}{phi}(x,s)/{gamma}{sub b}m{sub b}{beta}{sub g}{sup 2}c{sup 2}. The resulting model is shown to be exactly equivalent to a (truncated) warm-fluid description with zero heat flow and triple-adiabatic equation-of-state with scalar pressure P{sub b}(x,s) = const x [n{sub b}(x,s)]. Such a fluid model is amenable to direct analysis by transforming to Lagrangian variables following the motion of a fluid element. Specific examples of periodically focused beam equilibria are presented, ranging from a finite-emittance beam in which the boundary curves in phase space (x,x{prime}) correspond to a pulsating parallelogram, to a cold beam in which the number density of beam particles, n{sub b}(x,s), exhibits large-amplitude periodic oscillations. For the case of a sheet beam with uniform phase-space density, the present analysis clearly demonstrates the existence of periodically focused beam equilibria without the undesirable feature of an inverted population in phase space that is characteristic of the Kapchinskij-Vladimirskij beam distribution.
Energetic particle physics with applications in fusion and space plasmas
Cheng, C.Z.
1997-05-01
Energetic particle physics is the study of the effects of energetic particles on collective electromagnetic (EM) instabilities and energetic particle transport in plasmas. Anomalously large energetic particle transport is often caused by low frequency MHD instabilities, which are driven by these energetic particles in the presence of a much denser background of thermal particles. The theory of collective energetic particle phenomena studies complex wave-particle interactions in which particle kinetic physics involving small spatial and fast temporal scales can strongly affect the MHD structure and long-time behavior of plasmas. The difficulty of modeling kinetic-MHD multiscale coupling processes stems from the disparate scales which are traditionally analyzed separately: the macroscale MHD phenomena are studied using the fluid MHD framework, while microscale kinetic phenomena are best described by complicated kinetic theories. The authors have developed a kinetic-MHD model that properly incorporates major particle kinetic effects into the MHD fluid description. For tokamak plasmas a nonvariational kinetic-MHD stability code, the NOVA-K code, has been successfully developed and applied to study problems such as the excitation of fishbone and Toroidal Alfven Eigenmodes (TAE) and the sawtooth stabilization by energetic ions in tokamaks. In space plasmas the authors have employed the kinetic-MHD model to study the energetic particle effects on the ballooning-mirror instability which explains the multisatellite observation of the stability and field-aligned structure of compressional Pc 5 waves in the magnetospheric ring current plasma.
Ebrahimi, V.; Esfandyari-Kalejahi, A.
2014-09-15
In this paper, first we represent the differences between spatial and temporal dispersions and their dependence on the measurement techniques for electrostatic waves in unmagnetized collisionless plasma. Then, three different experimental data are compared to the solutions of exact nonextensive dispersion relations for electron-ion and pair plasma. The results confirm the existence of new acoustic plasma waves. Furthermore, these comparisons yield a Maxwellian and a nonextensive plasma with nonextensive parameter q larger than one, and a Maxwellian plasma with some abnormal dispersion properties.
Advances in electron kinetics and theory of gas discharges
Kolobov, Vladimir I.; The University of Alabama in Huntsville, Huntsville, Alabama 35899
2013-10-15
“Electrons, like people, are fertile and infertile: high-energy electrons are fertile and able to reproduce.”—Lev TsendinModern physics of gas discharges increasingly uses physical kinetics for analysis of non-equilibrium plasmas. The description of underlying physics at the kinetic level appears to be important for plasma applications in modern technologies. In this paper, we attempt to grasp the legacy of Professor Lev Tsendin, who advocated the use of the kinetic approach for understanding fundamental problems of gas discharges. We outline the fundamentals of electron kinetics in low-temperature plasmas, describe elements of the modern kinetic theory of gas discharges, and show examples of the theoretical approach to gas discharge problems used by Lev Tsendin. Important connections between electron kinetics in gas discharges and semiconductors are also discussed. Using several examples, we illustrate how Tsendin's ideas and methods are currently being developed for the implementation of next generation computational tools for adaptive kinetic-fluid simulations of gas discharges used in modern technologies.
Yin Yunpeng; Sawin, Herbert H.
2007-07-15
The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ion scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.
Response to “Comment on ‘The ion-kinetic D'Angelo mode’” [Phys. Plasmas 22, 044703 (2015)
Chibisov, D. V.; Mikhailenko, V. S.
2015-04-15
A response to “Comment on ‘The ion-kinetic D'Angelo mode’” by Aman-ur-Rehman, Shaukat Ali Shan, and Hamid Saleem is given. We find that all Comments are grounded on the misinterpretations of the results of our paper “The ion-kinetic D'Angelo mode” and are erroneous.
On the kinetic foundations of Kaluza's magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Sandoval-Villalbazo, Alfredo; Sagaceta-Mejía, Alma R.; García-Perciante, Ana L.
2015-06-01
Recent work has shown the existence of a relativistic effect present in a single component non-equilibrium fluid, corresponding to a heat flux due to an electric field [J. Non-Equilib. Thermodyn. 38 (2013), 141-151]. The treatment in that work was limited to a four-dimensional Minkowski space-time in which the Boltzmann equation was treated in a special relativistic approach. The more complete framework of general relativity can be introduced to kinetic theory in order to describe transport processes associated to electromagnetic fields. In this context, the original Kaluza's formalism is a promising approach [Sitz. Ber. Preuss. Akad. Wiss. (1921), 966-972; Gen. Rel. Grav. 39 (2007), 1287-1296; Phys. Plasmas 7 (2000), 4823-4830]. The present work contains a kinetic theory basis for Kaluza's magnetohydrodynamics and gives a novel description for the establishment of thermodynamic forces beyond the special relativistic description.
NASA Astrophysics Data System (ADS)
Chalise, Roshan; Khanal, Raju
2015-11-01
We have developed a self-consistent 1d3v (one dimension in space and three dimension in velocity) Kinetic Trajectory Simulation (KTS) model, which can be used for modeling various situations of interest and yields results of high accuracy. Exact ion trajectories are followed, to calculate along them the ion distribution function, assuming an arbitrary injection ion distribution. The electrons, on the other hand, are assumed to have a cut-off Maxwellian velocity distribution at injection and their density distribution is obtained analytically. Starting from an initial guess, the potential profile is iterated towards the final time-independent self-consistent state. We have used it to study plasma sheath region formed in presence of an oblique magnetic field. Our results agree well with previous works from other models, and hence, we expect our 1d3v KTS model to provide a basis for the studying of all types of magnetized plasmas, yielding more accurate results.
Cavalieri, Ralph R.; Steinberg, Martin; Searle, Gilbert L.
1970-01-01
The kinetics of distribution of 3,3?,5-triiodo-L-thyronine (T3) have been studied employing both a single-injection and a continuous infusion of T3-131I. External monitoring of radioactivity in the liver during the infusion permitted estimation of the hepatic distribution volume (VH) and the one-way hepatic clearance (CH) of the hormone. Among 10 euthyroid control subjects, VH averaged 2.07 liters ±0.50 (SD), and the mean value for CH, 231 ml of plasma per min (±64). In three euthyroid men whose plasma showed decreased binding capacity by thyroxine-binding globulin (TBG) abnormally high VH and CH values were found, the increase in CH being proportional to the decrease in binding activity by plasma proteins. Among all 13 subjects, there was a high correlation (+ 0.86) between CH and the proportion of free hormone in plasma, measured in vitro. In four patients with hyperthyroid Graves' disease VH ranged from 3.2 to 4.2 liters and CH was elevated in every case, averaging 989 ml/min. The increase in CH in this group was out of proportion to the elevation of free hormone fraction in plasma. Seven patients who were either euthyroid or hypothyroid after treatment of Graves' disease showed a slight but significant increase in CH compared with the euthyroid controls without Graves' disease. The percentage of free hormone in the plasma of the treated group was normal or low and therefore could not explain the persistent elevation in unidirectional hepatic clearance observed. The rate of accumulation of labeled T3 in the tissues of the thigh during the interval from 10 to 60 min of the sustaining infusion of tracer was slow compared to the rate of equilibration in the liver and did not differ significantly among the various groups studied. These latter findings suggest that in slowly equilibrating tissues such as the thigh the kinetics of T3 distribution are relatively insensitive to alterations in hormone-binding activity by plasma proteins. PMID:4987168
NASA Astrophysics Data System (ADS)
Liu, Chao; Liu, Yue
2015-10-01
> The effect of a parallel viscous force induced damping and the magnetic precessional drift resonance induced damping on the stability of the resistive wall mode (RWM) is numerically investigated for one of the advanced steady-state scenarios in international thermonuclear experimental reactor (ITER). The key element of the investigation is to study how different plasma rotation profiles affect the stability prediction. The single-fluid, toroidal magnetohydrodynamic (MHD) code MARS-F (Liu et al., Phys. Plasmas, vol. 7, 2000, p. 3681) and the MHD-kinetic hybrid code MARS-K (Liu et al., Phys. Plasmas, vol. 15, 2008, 112503) are used for this purpose. Three extreme rotation profiles are considered: (a) a uniform profile with no shear, (b) a profile with negative flow shear at the rational surface ( is the equilibrium safety factor), and (c) a profile with positive shear at . The parallel viscous force is found to be effective for the mode stabilization at high plasma flow speed (about a few percent of the Alfven speed) for the no shear flow profile and the negative shear flow profile, but the stable domain does not appear with the positive shear flow profile. The predicted eigenmode structure is different with different rotation profiles. With a self-consistent inclusion of the magnetic precession drift resonance of thermal particles in MARS-K computations, a lower critical flow speed, i.e. the minimum speed needed for full suppression of the mode, is obtained. Likewise the eigenmode structure is also modified by different rotation profiles in the kinetic results.
Harilal, S. S.
response of plasma-facing components V. Sizyuk and A. Hassanein Center for Materials under Extreme for accurate response of plasma-facing components This article has been downloaded from IOPscience. Please of line and continuum radiation. 1. Introduction Successful development of future fusion reactors
Wang, Xuewen; Magkos, Faidon; Patterson, Bruce W.; Reeds, Dominic N.; Kampelman, Janine; Mittendorfer, Bettina
2013-01-01
Objective Subclinical hypercortisolemia often occurs in subjects with features of the metabolic syndrome, and it has been suggested that it may be, at least in part, responsible for the development of these metabolic abnormalities. However, the metabolic effects of glucocorticoid administration to mimic subclinical glucocorticoid excess have not been evaluated. Methods We used stable isotope-labeled tracer methods in conjunction with magnetic resonance techniques to measure the effect of glucocorticoid excess within the physiological range (~0.7 mg dexamethasone/day for 3 weeks) on glucose and free fatty acid (FFA) rates of appearance (Ra) into plasma, intrahepatic triglyceride (TG) content, very low density lipoprotein (VLDL)-TG and VLDL-apolipoprotein B-100 (apoB-100) kinetics and plasma lipoprotein subclass concentrations and particle sizes in 9 overweight and obese individuals. Results Dexamethasone treatment led to a very small but significant increase in body weight (from 87.4±7.1 to 88.6±7.2 kg; P=0.003) and increased high-density lipoprotein (HDL)-cholesterol (from 45.9±2.8 to 55.1±4.6 mg/dl; P=0.037) and HDL particle (from 33.7±2.2 to 41.4±4.2 nmol/l; P=0.023) concentrations in plasma but had no effect on intrahepatic TG content, glucose and FFA Ra in plasma, hepatic VLDL-TG and VLDL-apoB-100 secretion rates and mean residence times in the circulation, plasma TG and LDL-cholesterol concentrations, and plasma lipoprotein particle sizes. Conclusion(s) Subclinical hypercortisolemia does not have significant adverse metabolic consequences. PMID:22619349
Properties of kinetic Alfvén waves: A comparison of fluid models with kinetic theory
NASA Astrophysics Data System (ADS)
Hunana, P.; Goldstein, M. L.; Passot, T.; Sulem, P. L.; Laveder, D.; Zank, G. P.
2013-06-01
Although the solar wind, as a collisionless plasma, is properly described by the kinetic Maxwell-Vlasov description, it can be argued that much of our understanding of the solar wind is based on a fluid description of magnetohydrodynamics that derives from interpretation of observational data together with numerical modeling. In recent years, there has been significant interest in better understanding the importance of kinetic effects, i.e., the differences between kinetic and fluid descriptions. Here we concentrate on the physical properties of oblique kinetic Alfvén waves (KAWs) that appear to be a key ingredient in the solar wind turbulence cascade. We use three different fluid models with various degrees of complexity and calculate the polarization and magnetic compressibility of KAWs (propagation angle ? = 88°), which we compare to solutions derived from linear kinetic theory. We explore a wide range of possible proton plasma ? = [0.1, 10.0] and a wide range of length scales k?rL = [0.001, 10.0], where rL denotes the proton gyroscale. It is shown that the ``classical'' isotropic two-fluid model is very compressible in comparison with kinetic theory and that the largest discrepancy occurs at scales larger than the proton gyroscale. We also show that the two-fluid model contains a large error in the polarization of electric field, even at scales k?rL << 1. Furthermore, to understand these discrepancies between the two-fluid model and the kinetic theory, we employ two versions of the Landau fluid model that incorporate linear low-frequency kinetic effects such as Landau damping and finite Larmor radius (FLR) corrections into the fluid description. We show that allowing for anisotropic pressure fluctuations and Landau damping is crucial for correct modeling of magnetic compressibility and that FLR corrections (i.e., nongyrotropic contributions) are required to correctly capture the polarization. We also show that, in addition to Landau damping, FLR corrections are necessary to accurately describe the damping rate of KAWs. We conclude that kinetic effects are important even at scales which are significantly larger than the proton gyroscale k?rL << 1.
Coupled electron and ion nonlinear oscillations in a collisionless plasma
Karimov, A. R.
2013-05-15
Dynamics of coupled electrostatic electron and ion nonlinear oscillations in a collisionless plasma is studied with reference to a kinetic description. Proceeding from the exact solution of Vlasov-Maxwell equations written as a function of linear functions in the electron and ion velocities, we arrive at the two coupled nonlinear equations which describe the evolution of the system.
Landau Diamagnetism of Degenerate Collisional Plasma
A. V. Latyshev; A. A. Yushkanov
2010-07-05
For the first time the kinetic description of Landau diamagnetism for degenerate collisional plasma is given. The correct expression for transverse electric conductivity of the quantum plasma, found by authors (see arXiv:1002.1017 [math-ph] 4 Feb 2010) is used. In work S. Dattagupta, A.M. Jayannavar and N. Kumar [Current science, V. 80, No. 7, 10 April, 2001] was discussed the important problem of dissipation (collisions) influence on Landau diamagnetism. The analysis of this problem is given with the use of exact expression for transverse conductivity of quantum plasma.
Yin, L.; Albright, B. J.; Bowers, K. J.; Daughton, W.; Rose, H. A.
2008-01-15
Backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser are examined in the kinetic regime using particle-in-cell simulations. The SRS reflectivity measured as a function of the laser intensity in a single hot spot from two-dimensional (2D) simulations shows a sharp onset at a threshold laser intensity and a saturated level at higher intensities, as obtained previously in Trident experiments [D. S. Montgomery et al., Phys. Plasmas 9, 2311 (2002)]. In these simulations, wavefront bowing of electron plasma waves (ion acoustic waves) due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) [H. A. Rose, Phys. Plasmas 12, 12318 (2005)] is shown to occur in both two- and three-dimensional SRS simulations. The key physics underlying nonlinear saturation of SRS is identified as a combination of wavefront bowing, TPMI, and self-focusing of electron plasma waves. The wavefront bowing marks the beginning of SRS saturation and self-focusing alone is sufficient to terminate the SRS reflectivity, both effects resulting from cancellation of the source term for SRS and from greatly increased dissipation rate of the electron plasm waves. Ion acoustic wave bowing also contributes to the SBS saturation. Velocity diffusion by transverse modes and rapid loss of hot electrons in regions of small transverse extent formed from self-focusing lead to dissipation of the wave energy and an increase in the Landau damping rate in spite of strong electron trapping that reduces Landau damping initially. The ranges of wavelength and growth rate associated with transverse breakup of the electron-plasma wave are also examined in 2D speckle simulations as well as in 2D periodic systems from Bernstein-Greene-Kruskal equilibrium and are compared with theory predictions.
Positive and negative chlorine ion kinetics in inductively-coupled Cl{sub 2}BCl{sub 3} plasmas
Fleddermann, C.B.; Hebner, G.A.
1997-05-01
Discharges in gas mixtures of Cl{sub 2}, BCl{sub 3}, Ar, and N{sub 2} are used by the integrated circuit industry for metal etching, and are as yet not well understood, especially in inductively-coupled plasma (ICP) sources which are rapidly becoming the industry standard for etching tools. An essential parameter that must be measured in these plasmas is the density of ions, both positive and negative, formed in the plasma. In the work presented here, LIF and laser photodetachment were used to measure relative metastable chlorine ion CL{sup +}* density and temperature and absolute Cl{sup {minus}} density as a function of gas mixture.
NASA Astrophysics Data System (ADS)
Nilsson, E.; Lohou, F.; Lothon, M.; Pardyjak, E.; Mahrt, L.; Darbieu, C.
2015-11-01
The decay of turbulence kinetic energy (TKE) and its budget in the afternoon period from mid-day until zero buoyancy flux at the surface is studied in a two-part paper by means of measurements from the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field campaign for 10 Intensive Observation Period days. Here, in Part 1, near-surface measurements from a small tower are used to estimate a TKE budget. The overall boundary layer characteristics and meso-scale situation at the site are also described based upon taller tower measurements, radiosoundings and remote sensing instrumentation. Analysis of the TKE budget during the afternoon transition reveals a variety of different surface layer dynamics in terms of TKE and TKE decay. This is largely attributed to variations in the 8 m wind speed, which is responsible for different amounts of near-surface shear production on different afternoons and variations within some of the afternoon periods. The partitioning of near surface production into local dissipation and transport in neutral and unstably stratified conditions was investigated. Although variations exist both between and within afternoons, as a rule of thumb, our results suggest that about 50 % of the near surface production of TKE is compensated by local dissipation near the surface, leaving about 50 % available for transport. This result indicates that it is important to also consider TKE transport as a factor influencing the near-surface TKE decay rate, which in many earlier studies has mainly been linked with the production terms of TKE by buoyancy and wind shear. We also conclude that the TKE tendency is smaller than the other budget terms, indicating a quasi-stationary evolution of TKE in the afternoon transition. Even though the TKE tendency was observed to be small, a strong correlation to mean buoyancy production of -0.69 was found for the afternoon period. For comparison with previous results, the TKE budget terms are normalized with friction velocity and measurement height and discussed in the framework of Monin-Obukhov similarity theory. Empirically fitted expressions are presented. Alternatively, we also suggest a non-local parametrization of dissipation using a TKE-length scale model which takes into account the boundary layer depth in addition to distance above the ground. The non-local formulation is shown to give a better description of dissipation compared to a local parametrization.
Thermo field hydrodynamic and kinetic equations of dense quantum nuclear systems
M. V. Tokarchuk; T. Arimitsu; A. E. Kobryn
1999-01-16
Basic equations of nonequilibrium thermo field dynamics of dense quantum systems are presented. A formulation of nonequilibrium thermo field dynamics has been performed using the nonequilibrium statistical operator method by D.N.Zubarev. Hydrodynamic equations have been obtained in thermo field representation. Two levels of the description of kinetics and hydrodynamics of a dense nuclear matter are considered. The first one is a quantum system with strongly coupled states, the second one is a quark-gluon plasma. Generalized transfer equations of a consistent description of kinetics and hydrodynamics have been obtained, as well as limiting cases are considered.
Statistical description of low-latitude plasma blobs as observed by DMSP F15 and KOMPSAT-1
NASA Astrophysics Data System (ADS)
Park, J.; Min, K. W.; Kim, V. P.; Kil, H.; Kim, H. J.; Lee, J. J.; Lee, E.; Kim, S. J.; Lee, D. Y.; Hairston, M.
We investigated the global distribution of low-latitude plasma blobs using in-situ plasma density measurements from Korea Multi-Purpose Satellite-1 KOMPSAT-1 and Defense Meteorological Satellite Program DMSP F15 The seasonal-longitudinal S L distribution of blobs is generally consistent with that of equatorial plasma bubbles EPBs but between them exist two notable differences First during equinoxes the blob activity is inhibited around the Atlantic region Second during the June solstice the African peak is rather suppressed in the distribution KOMPSAT-1 at the lower altitude encountered blobs more frequently than DMSP F15 The occurrence probability of plasma blobs is less subjected to the yearly variation of solar activity And the latitudinal distribution of the blobs shows strong asymmetry during solstices Most of them are concentrated on the winter hemisphere where the background density is low and the inter-hemispheric plasma transport is poleward along the geomagnetic field line And the asymmetry becomes weak as the solar activity decreases suggesting that the blob generation bears connection with the fountain effect inside EPBs and the poleward plasma transport
NASA Astrophysics Data System (ADS)
Muñoz, P. A.; Told, D.; Kilian, P.; Büchner, J.; Jenko, F.
2015-08-01
In this work, we compare gyrokinetic (GK) with fully kinetic Particle-in-Cell (PIC) simulations of magnetic reconnection in the limit of strong guide field. In particular, we analyze the limits of applicability of the GK plasma model compared to a fully kinetic description of force free current sheets for finite guide fields (bg). Here, we report the first part of an extended comparison, focusing on the macroscopic effects of the electron flows. For a low beta plasma (?i = 0.01), it is shown that both plasma models develop magnetic reconnection with similar features in the secondary magnetic islands if a sufficiently high guide field (bg ? 30) is imposed in the kinetic PIC simulations. Outside of these regions, in the separatrices close to the X points, the convergence between both plasma descriptions is less restrictive (bg ? 5). Kinetic PIC simulations using guide fields bg ? 30 reveal secondary magnetic islands with a core magnetic field and less energetic flows inside of them in comparison to the GK or kinetic PIC runs with stronger guide fields. We find that these processes are mostly due to an initial shear flow absent in the GK initialization and negligible in the kinetic PIC high guide field regime, in addition to fast outflows on the order of the ion thermal speed that violate the GK ordering. Since secondary magnetic islands appear after the reconnection peak time, a kinetic PIC/GK comparison is more accurate in the linear phase of magnetic reconnection. For a high beta plasma (?i = 1.0) where reconnection rates and fluctuations levels are reduced, similar processes happen in the secondary magnetic islands in the fully kinetic description, but requiring much lower guide fields (bg ? 3).
Claudio Cremaschini; Massimo Tessarotto
2012-01-09
A notorious difficulty in the covariant dynamics of classical charged particles subject to non-local electromagnetic (EM) interactions arising in the EM radiation-reaction (RR) phenomena is due to the definition of the related non-local Lagrangian and Hamiltonian systems. The lack of a standard Lagrangian/Hamiltonian formulation in the customary asymptotic approximation for the RR equation may inhibit the construction of consistent kinetic and fluid theories. In this paper the issue is investigated in the framework of Special Relativity. It is shown that, for finite-size spherically-symmetric classical charged particles, non-perturbative Lagrangian and Hamiltonian formulations in standard form can be obtained, which describe particle dynamics in the presence of the exact EM RR self-force. As a remarkable consequence, based on axiomatic formulation of classical statistical mechanics, the covariant kinetic theory for systems of charged particles subject to the EM RR self-force is formulated in Hamiltonian form. A fundamental feature is that the non-local effects enter the kinetic equation only through the retarded particle 4-position, which permits the construction of the related non-local fluid equations. In particular, the moment equations obtained in this way do not contain higher-order moments, allowing as a consequence the adoption of standard closure conditions. A remarkable aspect of the theory concerns the short delay-time asymptotic expansions. Here it is shown that two possible expansions are permitted. Both can be implemented for the single-particle dynamics as well as for the corresponding kinetic and fluid treatments. In the last case, they are performed a posteriori on the relevant moment equations obtained after integration of the kinetic equation over the velocity space. Comparisons with literature are pointed out.
NASA Technical Reports Server (NTRS)
Shawhan, S. D.
1982-01-01
The objectives, equipment, and techniques for the plasma diagnostics package (PDP) carried by the OSS-1 instrument payload of the STS-4 and scheduled for the Spacelab-2 mission are described. The goals of the first flight were to examine the Orbiter-magnetoplasma interactions by measuring the electric and magnetic field strengths, the ionized particle wakes, and the generated waves. The RMS was employed to lift the unit out of the bay in order to allow characterization of the fields, EM interference, and plasma contamination within 15 m of the Orbiter. The PDP will also be used to examine plasma depletion, chemical reaction rates, waves, and energized plasma produced by firing of the Orbiter thrusters. Operation of the PDP was carried out in the NASA Space Environment Simulation Laboratory test chamber, where the PDP was used to assay the fields, fluxes, wave amplitudes, and particle energy spectra. The PDP instrumentation is also capable of detecting thermal ions, thermal electrons suprathermal particles, VHF/UHF EMI levels, and the S-band field strength.
Kwon, Ohseung; Sawin, Herbert H.
2006-09-15
Silicon oxide etching processes in C{sub 2}F{sub 6} and C{sub 4}F{sub 8}+80% Ar plasmas were investigated. Neutral and ion compositions in the plasma were measured using quadrupole mass spectrometry and etching yield was measured by a quartz-crystal microbalance. In C{sub 2}F{sub 6} plasma, the concentration of atomic fluorine in the neutral flux was 5%-25%, whereas there was less than 0.5% of atomic fluorine in C{sub 4}F{sub 8}+80% Ar plasma. A surface plot representing the etching yield as a function of neutral and ion fluxes was constructed and used to qualitatively explain the etching characteristics of silicon oxide in fluorocarbon plasmas. In C{sub 2}F{sub 6} chemistry, etching yield decreases slightly with increasing rf coil power. This is attributed to the decrease in both F/ion and CF{sub x}/ion, which is caused by an increase in ion flux, with a more significant effect due to a decrease in F/ion. In C{sub 4}F{sub 8}+80% Ar chemistry, however, etching yield increases with increasing rf coil power. This is attributed to the decrease in CF{sub x}, without the effect of F/ion due to the low atomic fluorine concentration. With increased operating pressure, etching yield decreases for both chemistries because as the pressure increases, ion current decreases, and CF{sub x} neutral concentration increases to have more deposition and less etching.
NASA Astrophysics Data System (ADS)
Barton, Justin E.; Schuster, Eugenio; Besseghir, Karim; Lister, Jonathan
2012-10-01
The ``hybrid'' and ``steady-state'' advanced scenarios are characterized by q profiles higher or equal to one to mitigate plasma instabilities and improve confinement, which are key for ITER to achieve its operational objectives. To achieve these scenarios, active model-based control of the current profile and thermal state of the plasma is required. Towards this goal, two control-oriented, plasma-response models are proposed. First, the poloidal flux diffusion equation is combined with empirical models of the electron density and temperature profiles, plasma resistivity, and non-inductive current drives to obtain a physics-based model of the poloidal flux and stored energy evolutions. Second, the empirical electron temperature model is replaced by the electron heat transport equation, which is combined with empirical models of the electron heat conductivity and heat sources to obtain a physics-based model of the poloidal flux and electron temperature evolutions. Simulation results comparing the evolution of the plasma parameters predicted by the control-oriented, physic-based models and the DINA-CH+CRONOS simulation code are presented for ITER, and the control objectives and challenges are discussed.
Montgomery, D. S.; Focia, R.; Rose, H. A.; Bezzerides, B.; Cobble, J. A.; DuBois, D. F.; Vu, H. X.; Fernández, J. C.
2001-01-01
Laser-plasma instability (LPI) research at Los Alamos is done as a closely coupled theoretical and experimental scientific program to advance the ignition and weapons physics enterprises, which are integrated by the US Department of Energy as a national program. Past LANL experiments, performed as part of the Nova Technical Contract, on hohlraum plasmas approaching NIF conditions have raised two main questions regarding stimulated Raman back-scattering (SRS) in such plasmas: (1) How can the high observed values of SRS reflectivity persist at k;l, = 0.3 -- 0.45? (2) What are the non-linear mechanism(s) whereby SRS saturates? In this paper we address those two questions with results from experiments on the LANL, Trident laser, and from Vlasov and PIC modeling of relevant plasmas, all aimed at understanding the physics involved. We find that non-Maxwellian distributions driven by intense ohmic heating, as well as electron trapping by the daughter SRS plasma wave, are implicated in the high SRS reflectivities observed at high values of Id,. We also find that electron trapping and the secondary Langmuir Decay Instability are important ingredients in the non-linear evolution of SRS.
A Kinetic Theory of Coupled Oscillators
Eric J. Hildebrand; Michael A. Buice; Carson C. Chow
2006-12-12
We present an approach for the description of fluctuations that are due to finite system size induced correlations in the Kuramoto model of coupled oscillators. We construct a hierarchy for the moments of the density of oscillators that is analogous to the BBGKY hierarchy in the kinetic theory of plasmas and gases. To calculate the lowest order system size effect, we truncate this hierarchy at second order and solve the resulting closed equations for the two-oscillator correlation function around the incoherent state. We use this correlation function to compute the fluctuations of the order parameter, including the effect of transients, and compare this computation with numerical simulations.
NASA Astrophysics Data System (ADS)
Simpson, D. G.; Lipatov, A. S.; Sittler, E. C.; Hartle, R. E.; Cooper, J. F.
2013-12-01
Wave-particle interactions play a very important role in the plasma dynamics near Titan: mass loading, excitation of the low-frequency waves and the formation of the particle velocity distribution function, e.g. ring/shell-like distributions, etc. The kinetic approach is important for estimation of the collision processes e.g. a charge exchange. The particle velocity distribution function also plays a key role for understanding the observed particle fluxes. In this report we discuss the ion velocity distribution function dynamics from 3D hybrid modeling. The modeling is based on recent analysis of the Cassini Plasma Spectrometer (CAPS) ion measurements during the TA flyby. In our model the background ions, all pickup ions, and ionospheric ions are considered as particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. The temperatures of the background electrons and pickup electrons were also included into the generalized Ohm's law. We also take into account the collisions between the ions and neutrals. We use Chamberlain profiles for the exosphere's components and include a simple ionosphere model with M=28 ions that were generated inside the ionosphere. The moon is considered as a weakly conducting body. Our modeling shows that interaction between background plasma and pickup ions H+, H2+, CH4+ and N2+ has a more complicated structure than was observed in the T9 flyby and modeling due to the large gyroradius of the background O+ ions [1,2,3,4]. Special attention will be paid to comparing the simulated pickup ion velocity distribution with CAPS TA observations. We also compare our kinetic modeling with other hybrid and MHD modeling of Titan's environment. References [1] Sittler, E.C., et al., Energy Deposition Processes in Titan's Upper Atmosphere and Its Induced Magnetosphere. In: Titan from Cassini-Huygens, Brown, R.H., Lebreton J.P., Waite, J.H., Eds., Springer, (Dordrecht, Heidelberg, London, New York, pp. 393-455, 2009). [2] Sittler, E.C., et al., Saturn's Magnetospheric Interaction with Titan as Defined by Cassini Encounters T9 and T18: New Results, Planet. Space Sci., doi.10.1016/j.pss.2009.09.017. [3] Coates, A.J., Interaction of Titan's ionosphere with Saturn's magnetosphere. Phil. Trans. R. Soc. A (2009) 367, 773-788, doi: 10.1098/rsta.2008.0248. [4] Lipatov, A.S., et al., Background and pickup ion velocity distribution dynamics in Titan's plasma environment: 3D hybrid simulation and comparison with CAPS T9 observations. Adv. Space Res. 48, 1114-1125, 2011.
Kinetic effects of the dust charge fluctuations on the instability of dust ion-acoustic waves
NASA Astrophysics Data System (ADS)
Rouhani, M. R.; Jamshidi, M.; Hakimi Pajouh, H.
2015-05-01
In this paper, a kinetic description is used to derive the perturbed dust grain currents carried by the plasma particles, taking into account dust charge fluctuations. The longitudinal dielectric permittivity and the dispersion relation of dust ion-acoustic waves in an unmagnetized dusty plasma are obtained. It is shown that the dust charge fluctuations effectively modify the damping rate of these waves, which can lead to an excitation of instability in plasma. This instability is due to the thermal velocity of the plasma particles and dust charge fluctuations. It is different from the instability due to the drift speed of the plasma particles. It is found that there is a critical wave number above which these waves are unstable. In addition, the growth rate of these waves is numerically investigated for different plasma parameters. The present theory is applicable in astronomers and space scientists working on dusty plasmas, especially planetary ring systems and cometary tails, where dust charge fluctuations are important.
Shuaibov, A. K.; Grabovaya, I. A.; Minya, A. I.; Homoki, Z. T.; Kalyuzhnaya, A. G.; Shchedrin, A. I.
2011-03-15
A kinetic model of the processes occurring in the plasma of a high-power low-pressure gas-discharge lamp is presented, and the output characteristics of the lamp are described. The lamp is excited by a longitudinal glow discharge and emits the I{sub 2}(D Prime -A Prime ) 342-nm and XeI(B-X) 253-nm bands and the 206.2-nm spectral line of atomic iodine. When the emitter operates in a sealed-off mode on the p(He): p(Xe): p(I{sub 2}) = 400: 120: (100-200) Pa mixture, the fractions of the UV radiation power of iodine atoms, exciplex molecules of xenon iodide, and iodine molecules comprise 55, 10, and 35%, respectively. At the optimal partial pressure, the maximum total radiation power of the lamp reaches 37 W, the energy efficiency being about 15%.
NASA Astrophysics Data System (ADS)
Valdueza-Felip, S.; Bellet-Amalric, E.; Núñez-Cascajero, A.; Wang, Y.; Chauvat, M.-P.; Ruterana, P.; Pouget, S.; Lorenz, K.; Alves, E.; Monroy, E.
2014-12-01
We report the interplay between In incorporation and strain relaxation kinetics in high-In-content InxGa1-xN (x = 0.3) layers grown by plasma-assisted molecular-beam epitaxy. For In mole fractions x = 0.13-0.48, best structural and morphological qualities are obtained under In excess conditions, at In accumulation limit, and at a growth temperature where InGaN decomposition is active. Under such conditions, in situ and ex situ analyses of the evolution of the crystalline structure with the layer thickness point to an onset of misfit relaxation after the growth of 40 nm, and a gradual relaxation during more than 200 nm, which results in an inhomogeneous strain distribution along the growth axis. This process is associated with a compositional pulling effect, i.e., indium incorporation is partially inhibited in presence of compressive strain, resulting in a compositional gradient with increasing In mole fraction towards the surface.
NASA Astrophysics Data System (ADS)
Hur, Min Sup; Wurtele, Jonathan S.
2009-04-01
Focusing of an intense laser pulse produced by backward Raman pulse amplification (BRA) has been numerically studied using a two-dimensional, axisymmetric kinetic model. The two-dimensional averaged particle-in-cell (aPIC) simulation assumes slowly varying field envelopes and is comprised of one-dimensional sub-models that are coupled radially through laser diffraction. A converging 33 TW seed pulse was amplified up to 1 PW. The focusing of the seed pulse, even when particle trapping was important, was maintained. It was also found that the focusing properties of the pulse tail can lead to some rewidening of the longitudinal pulse duration and some ideas for eliminating this effect were suggested. Simulations performed for various plasma densities and temperatures exhibited robust amplification and pulse shortening.
Carey, I; Bruce, M; Horner, M; Zen, Y; D'Antiga, L; Bansal, S; Vergani, D; Mieli-Vergani, G
2015-04-01
We aimed to investigate the ability of HBsAg plasma level kinetics to predict therapy response by studying 23 children with infancy-acquired chronic hepatitis B (CHB) during combination sequential therapy with lead-in lamivudine (LAM) and add-on interferon-? (IFN-?) [5 responders (R = anti-HBs seroconversion) and 18 nonresponders (NR)] and to assess their relationship with pretreatment intrahepatic HBV-DNA and cccDNA and HBsAg and HBcAg liver expression. Plasma HBsAg levels were measured in samples before (treatment week 0 = TW0), during (TW9, TW28, TW52) and after (follow-up week = FUW24) therapy by Abbott ARCHITECT(®) assay [log10 IU/mL]. Baseline liver HBV-DNA and cccDNA were quantified by real-time TaqMan PCR [log10 copies/ng genomic DNA]. HBsAg and HBcAg liver expression was evaluated by immunostaining of formalin-fixed, paraffin-embedded specimens [number of positive cells/1000 hepatocytes]. All results are presented as medians. Plasma: at baseline, on-treatment and during follow-up, HBsAg levels were lower in R than NR (TW0: 4.36 vs 4.75;TW28: 2.44 vs 4.35;TW52: 0 vs 4.08 and FUW24: 0.17 vs 4.35, all P < 0.05). Liver: baseline HBV-DNA (3.82 vs 4.71, P = 0.16) and cccDNA (1.98 vs 2.26, P = 0.18) tended to be lower in R than NR, HBsAg expression was lower in R than NR (0.5 vs 4.7, P = 0.03), and HBcAg expression was similar between R and NR. There were positive correlations between plasma HBsAg levels and liver HBV-DNA (r = 0.44, P = 0.04), cccDNA (r = 0.41, P = 0.04) and HBsAg liver expression (r = 0.38, P = 0.05). Lower baseline HBsAg plasma levels, lower HBsAg expression in liver and on-treatment decline of plasma HBsAg levels heralds HBsAg clearance and response to treatment in tolerant children with CHB. PMID:25278170
Magnetospheric space plasma investigations
NASA Technical Reports Server (NTRS)
Comfort, Richard H.; Horwitz, James L.
1995-01-01
Topics and investigations covering this period of this semiannual report period (August 1994 - January 1995) are as follows: (1) Generalized SemiKinetic (GSK) modeling of the synergistic interaction of transverse heating of ionospheric ions and magnetospheric plasma-driven electric potentials on the auroral plasma transport. Also, presentations of GSK modeling of auroral electron precipitation effects on ionospheric plasma outflows, of ExB effects on such outflow, and on warm plasma thermalization and other effects during refilling with pre-existing warm plasmas; (2) Referees' reports received on the statistical study of the latitudinal distributions of core plasmas along the L = 4.6 field line using DE-1/RIMS data. Other work is concerned in the same field, field-aligned flows and trapped ion distributions; and (3) A short study has been carried out on heating processes in low density flux tubes in the outer plasmasphere. The purpose was to determine whether the high ion temperatures observed in these flux tubes were due to heat sources operating through the thermal electrons or directly to the ions. Other investigations center along the same area of plasmasphere-ionosphere coupling. The empirical techniques and model, the listing of hardware calibrated, and/or tested, and a description of notable meetings attended is included in this report, along with a list of all present publication in submission or accepted and those reference papers that have resulted from this work thus far.
Yamada, N; Shames, D M; Havel, R J
1987-01-01
The kinetics of apolipoprotein (apo) B-100 in particles containing apo E (B,E particles) or lacking apo E (B particles) were studied in Watanabe heritable hyperlipidemic (WHHL) rabbits deficient in low density lipoprotein (LDL) receptors, and compared with those of normal rabbits after injection of radioiodinated very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), and LDL. In both groups results of kinetic modeling were consistent with the hypothesis that all apo B enters the plasma in VLDL, mainly as B,E particles, followed by delipidation and partial conversion to IDL and LDL, with concomitant conversion of some B,E particles to B particles. In WHHL rabbits, production of VLDL apo B was reduced by 40%, but LDL production was increased threefold. Defective removal of B,E and B particles in all three lipoprotein classes, coupled with preserved processes of delipidation, can account for the observed increases in the concentration of apo B (threefold in VLDL, fivefold in IDL, and twenty-twofold in LDL) in WHHL rabbits. PMID:3611356
NASA Astrophysics Data System (ADS)
Sun, Yu; Kulkarni, Kaustubh; Sachdev, Anil K.; Lavernia, Enrique J.
2014-06-01
The current study shows the dramatic effect of an electric field (EF) and use of nanosized cryomilled grains on accelerating sintering kinetics during spark plasma sintering of blended elemental powder compacts of Ti53Al47 targeted to produce ?-TiAl intermetallic compounds. The EF had the dominating effect since it reduced the activation barrier for diffusion through Al3Ti leading to faster growth of Al3Ti; the precursor to ?-TiAl. The Avrami exponent ( n) determined for the micrograin compact lies between 1.0 and 1.5, which indicates that reaction sintering is controlled by bulk diffusion in these compacts, while for cryomilled compacts this is between 0.7 and 1.0 suggesting the important role of dislocations and grain boundaries on the transformation during reaction sintering. The activation energies were found to be in increasing order as: cryomilled compacts with EF (182 kJ/mol); micrograin compacts with EF (290 kJ/mol); cryomilled compacts without EF (331 kJ/mol); and micrograin compacts without EF (379 kJ/mol). The cryomilled microstructure also enhanced the sintering kinetics because of the availability of faster diffusing paths in Al and Ti including larger grain boundary area and dislocation density.
Boonpawa, Rungnapa; Moradi, Nooshin; Spenkelink, Albertus; Rietjens, Ivonne M C M; Punt, Ans
2015-12-15
Biological activities of flavonoids in vivo ultimately depend on the systemic bioavailability of the aglycones and their metabolites. We aimed to develop physiologically based kinetic (PBK) models to predict plasma concentrations of the flavonoid quercetin and its metabolites in individual human subjects and to define species differences compared with male rat. The human models were developed based on in vitro metabolic parameters derived from incubations with pooled and 20 individual human tissue fractions and by fitting kinetic parameters to available in vivo data. The outcomes obtained were compared to a previously developed model for quercetin and its metabolites formation in male rat. Quercetin-3'-O-glucuronide was predicted to be the major circulating metabolite in 19 out of 20 individuals, while in male rat di- and tri-conjugates of quercetin containing a glucuronic acid, sulfate and/or methyl moieties are the major metabolites. Significant species differences occur in major circulating metabolites of quercetin suggesting that rat is not an adequate model to study effects of quercetin in man. The defined PBK models can be used to guide the experimental design of in vitro experiments with flavonoids, especially to better take into account the relevance of metabolism and the contribution of metabolites to the biological activity in humans. PMID:26441251
Kemp, A; Cohen, B; Divol, L
2009-11-16
We present new results on the physics of short-pulse laser-matter interaction of kilojoule-picosecond pulses at full spatial and temporal scale, using a new approach that combines a 3D collisional electromagnetic Particle-in-Cell code with an MHD-hybrid model of high-density plasma. In the latter, collisions damp out plasma waves, and an Ohm's law with electron inertia effects neglected determines the electric field. In addition to yielding orders of magnitude in speed-up while avoiding numerical instabilities, this allows us to model the whole problem in a single unified framework: the laser-plasma interaction at sub-critical densities, energy deposition at relativistic critical densities, and fast-electron transport in solid densities. Key questions such as the multi-picosecond temporal evolution of the laser energy conversion into hot electrons, the impact of return currents on the laser-plasma interaction, and the effect of self-generated electric and magnetic fields on electron transport will be addressed. We will report applications to current experiments.
Huber, S; Antoni, F; Schickaneder, C; Schickaneder, H; Bernhardt, G; Buschauer, A
2015-02-01
Esters of the cytostatic bendamustine (1), previously demonstrated to be much more potent than the parent compound as antiproliferative agents in vitro, were investigated for stability in buffer and plasma, as well as against porcine liver esterase in the presence of different amounts of albumin using a validated RP-HPLC method with fluorescence detection. The hydrolysis of the nitrogen mustard moiety was retarded (for 1: approximately 130 vs. 11 min) in the presence of plasma proteins. For the derivatives, both cleavage of ester and nitrogen mustard moieties were analyzed. Enzymatic hydrolysis was very fast in the case of 2-pyrrolidino-, 2-piperidino- and 2-(4-methylpiperazino)-ethyl esters, whereas methyl, ethyl, morpholinoethyl and branched 2-pyrrolidinoethyl esters were considerably more stable (half-lives between 41 and 116 min, compared to <5 min). Inhibition by physostigmine indicated unspecific cholinesterases to be involved in the rapid ester cleavage. Due to lower protein content and higher enzymatic activity in murine compared to human plasma, reduced stability of all investigated esters in mouse plasma (t½<2 min) has to be taken into account with respect to the design of animal studies. PMID:25499654
Landau Fluid Models for Magnetized Plasmas
Sulem, P. L.; Passot, T.; Marradi, L.
2008-10-15
A Landau fluid model for a magnetized plasma, that retains a linear description of low-frequency kinetic effects involving transverse scales significantly smaller than the ion Larmor radius, is discussed and validated in the context of nonlinear wave dynamics. Preliminary simulations of the turbulent regime are presented in one space dimension, as a first step towards more realistic three-dimensional computations, aimed to analyze the combined effect of dispersion and collisionless dissipation on the energy cascade.
Zhang, Ding; Zhang, Kerong; Gao, Jianfeng; Liu, Jingying; Shahzad, Muhammad; Han, Zhaoqing; Nabi, Fazul; Li, Kun; Li, Jiakui
2015-06-01
Eprinomectin is recommended for use as an anti-parasitic agent in livestock, including cattle. Yaks are a member of the cattle family living in the high altitude mountains of China and adjacent countries; however, there have been no clinical trials of the anthelmintic efficacy and pharmacokinetics of eprinomectin in yaks. The purpose of this study was to investigate the endectocidal efficacy and pharmacokinetics of eprinomectin following topical (at 0.5?mg/kg) and subcutaneous (at 0.2?mg/kg) administration in the yak. After topical administration, plasma eprinomectin reached a peak value of 15.31?±?3.71?ng/ml (Cmax) at 3.01?±?1.22 days (Tmax). In milk, the Cmax was 3.74?±?1.05?ng/ml at 3.00?±?0.88 days. The AUC0-t for plasma was 193.84?±?26.34?ng d/ml and for milk AUC(0-t) was 46.24?±?10.37?ng d/ml. The mean residence time (MRT) was 10.74?±?1.44 days and 10.90?±?3.87 days in plasma and milk, respectively. After subcutaneous administration, the Cmax was 35.78?±?10.53?ng/ml at 0.91?±?0.39 days in plasma and 9.10?±?3.61?ng/ml at 1.61?±?1.05 days in milk. The MRTs in plasma and milk were 3.07?±?1.50 and 3.64?±?1.15 days, respectively. The AUC(0-t) was 133.71?±?32.51?ng d/ml for plasma and 43.85?±?14.16?ng d/ml for milk. Both the pour-on and injectable formulation of eprinomectin were similarly efficacious (minimum egg count reductions of 94% and 96.4%, respectively) at each post-treatment time point. However, Tmax, MRT and t(1/2el) were longer, and Cmax of eprinomectin in the plasma and milk were lower, following topical administration compared to those after subcutaneous administration. In conclusion, these results support the use of eprinomectin in yaks. The pour-on formulation of eprinomectin can be recommended for nematode control in lactating yaks with no milk-withdrawal period because of its low residue profile and good efficacy. PMID:25725422
Water bag modeling of a multispecies plasma
Morel, P.; Gravier, E.; Besse, N.; Klein, R.; Ghizzo, A.; Bertrand, P.; Bourdelle, C.; Garbet, X.
2011-03-15
We report in the present paper a new modeling method to study multiple species dynamics in magnetized plasmas. Such a method is based on the gyrowater bag modeling, which consists in using a multistep-like distribution function along the velocity direction parallel to the magnetic field. The choice of a water bag representation allows an elegant link between kinetic and fluid descriptions of a plasma. The gyrowater bag model has been recently adapted to the context of strongly magnetized plasmas. We present its extension to the case of multi ion species magnetized plasmas: each ion species being modeled via a multiwater bag distribution function. The water bag modelization will be discussed in details, under the simplification of a cylindrical geometry that is convenient for linear plasma devices. As an illustration, results obtained in the linear framework for ion temperature gradient instabilities are presented, that are shown to agree qualitatively with older works.
Belikov, V M; Kudinova, E G; Vorob'ev, M M
1986-01-01
Simple equation for the total rate of proteolysis is proposed. The equation, based on the renal mechanism of proteolysis includes the substrate concentration and some functions of the degree of hydrolysis. These functions are experimentally determined in the case of peptic hydrolysis of chicken heart proteins. The integration of differential equation made it possible to describe the kinetics of the proteolysis in terms of substrate concentration, degree of proteolysis and reaction time. The kinetics of proteolysis does not obey the Michaelis-Menten law. The proposed way for mathematical modelling permits the optimization by productivity. PMID:3528858
Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase-distribution
Pol Bernard Gossiaux; Vincent Guiho; Joerg Aichelin
2004-11-24
We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of $J/\\psi$ production (integrated and differential) stemming from c-$\\bar{c}$ pairs that are initially uncorrelated.
Silaev, A. A. Vvedenskii, N. V.
2015-05-15
When a gas is ionized by a few-cycle laser pulse, some residual current density (RCD) of free electrons remains in the produced plasma after the passage of the laser pulse. This quasi-dc RCD is an initial impetus to plasma polarization and excitation of the plasma oscillations which can radiate terahertz (THz) waves. In this work, the analytical model for calculation of RCD excited by a few-cycle laser pulse is developed for the first time. The dependences of the RCD on the carrier-envelope phase (CEP), wavelength, duration, and intensity of the laser pulse are derived. It is shown that maximum RCD corresponding to optimal CEP increases with the laser pulse wavelength, which indicates the prospects of using mid-infrared few-cycle laser pulses in the schemes of generation of high-power THz pulses. Analytical formulas for optimal pulse intensity and maximum efficiency of excitation of the RCD are obtained. Basing on numerical solution of the 3D time-dependent Schrödinger equation for hydrogen atoms, RCD dependence on CEP is calculated in a wide range of wavelengths. High accuracy of analytical formulas is demonstrated at the laser pulse parameters which correspond to the tunneling regime of ionization.
NASA Astrophysics Data System (ADS)
Héron, A.; Adam, J. C.
2015-07-01
We present a set of 2D collisional particle-in-cell simulations of the interaction of ultra-intense laser pulses with over-dense cold collisional plasmas. The size of these simulations is about 100 times as large as those previously published. This allows studying the transport of energetic particles on time scale of the order of 400 fs without perturbations due to the influence of boundary effects and performing a very detailed analysis of the physics of the transport. We confirm the existence of a threshold in intensity close to the relativistic threshold above which the beam of energetic particles diverges when it penetrates the cold plasma. We also study the applicability of Ohm's law to compute the electric field, which is the method commonly used in hybrid codes. The heating of the cold plasma is then studied and we show that half of the heating is anomalous, i.e., not given by standard Joule effect. We discuss the previously published results in the light of these new simulations.
NASA Astrophysics Data System (ADS)
Siewert, M.; Fahr, H.-J.
2007-08-01
Aims: We attempt to describe kinetic properties of the solar wind termination shock (and similar MHD shocks in general) using the appropriate form of the kinetic Boltzmann equation, for arbitrary inclinations ?Bn between the magnetic field and the shock normal. Methods: In order to understand the deviations from the perpendicular shock, for which we have already derived an exact solution in an earlier publication, we first prove that our current Boltzmann equation is unable to describe a stationary quasiparallel shock. To ease and open up further research, we derive conditions for the specific form of the relevant Boltzmann equation. Results: We demonstrate that the simplest Boltzmann equation aiming to describe a parallel MHD shock is in conflict with the predictions from pure MHD. We identify several possible reasons for this, and likewise derive conditions based on the mass flow conservation which must be fulfilled for the shock to be stationary. Assuming that a model for (quasi-)stationary shocks does exist, we are able to explain the unchanged power law index at the passage of the solar wind termination shock observed by the Voyager 1 spacecraft in 2004. We also show that different dissipation mechanisms lead to different transition scales for perpendicular and parallel MHD shocks, and that these differences in the dissipation process also need to be included in the case-competent Boltzmann equation.
Polarization and Compressibility of Oblique Kinetic Alfven Waves
NASA Technical Reports Server (NTRS)
Hunana, Peter; Goldstein, M. L.; Passot, T.; Sulem, P. L.; Laveder, D.; Zank, G. P.
2012-01-01
Even though solar wind, as a collisionless plasma, is properly described by the kineticMaxwell-Vlasov description, it can be argued that much of our understanding of solar wind observational data comes from an interpretation and numerical modeling which is based on a fluid description of magnetohydrodynamics. In recent years, there has been a significant interest in better understanding the importance of kinetic effects, i.e. the differences between the kinetic and usual fluid descriptions. Here we concentrate on physical properties of oblique kinetic Alfvn waves (KAWs), which are often recognized as one of the key ingredients in the solar wind turbulence cascade. We use three different fluid models with various degrees of complexity and calculate polarization and magnetic compressibility of oblique KAWs (propagation angle q = 88), which we compare to solutions derived from linear kinetic theory. We explore a wide range of possible proton plasma b = [0.1,10.0] and a wide range of length scales krL = [0.001,10.0]. It is shown that the classical isotropic two-fluid model is very compressible in comparison with kinetic theory and that the largest discrepancy occurs at scales larger than the proton gyroscale. We also show that the two-fluid model contains a large error in the polarization of electric field, even at scales krL 1. Furthermore, to understand these discrepancies between the two-fluid model and the kinetic theory, we employ two versions of the Landau fluid model that incorporate linear low-frequency kinetic effects such as Landau damping and finite Larmor radius (FLR) corrections into the fluid description. It is shown that Landau damping significantly reduces the magnetic compressibility and that FLR corrections (i.e. nongyrotropic contributions) are required to correctly capture the polarization.We also show that, in addition to Landau damping, FLR corrections are necessary to accurately describe the damping rate of KAWs. We conclude that kinetic effects are important even at scales which are significantly larger than the proton gyroscale krL 1.
Geerlof, A; Rakels, J J; Straathof, A J; Heijnen, J J; Jongejan, J A; Duine, J A
1994-12-01
Initial rate studies were performed on the oxidation of (racemic) alcohols as well as aldehydes by quinohaemoprotein ethanol dehydrogenase, type 1, from Comamonas testosteroni with potassium ferricyanide as electron acceptor. The data could be fitted with an equation derived for a mechanism (hexa-uni ping-pong) in which alcohols are oxidized to the corresponding carboxylic acids and the intermediate aldehyde becomes released from the enzyme. However, for some substrates it was necessary to assume that they exert uncompetitive inhibition. The same model was used to fit the data of conversion processes. Reversible inactivation of the enzyme takes place during the conversion, the extent being inversely proportional to the concentration of ferricyanide present at the start. From the values of the kinetic parameters obtained for (R)- and (S)-solketal [2,2-dimethyl-4-(hydroxymethyl)-1,3-dioxolane] and their corresponding aldehydes, it appeared that the second step in (S)-solketal conversion is much faster than the first one and that opposite enantiomeric preferences exist for the alcohol and the aldehyde substrates. Since the initial rate measurements as well as the progress curve analysis gave similar kinetic parameter values and product analysis revealed intermediates in the amounts predicted, it is concluded that the kinetic and enantioselective behaviour of the enzyme is adequately described by the model presented here. Finally, the results indicate that both kinetic approaches should be used in conversions with consecutive reactions since they provide complementary information. PMID:8001568
Maron, Y; Starobinets, A; Fisher, V I; Kroupp, E; Osin, D; Fisher, A; Deeney, C; Coverdale, C A; Lepell, P D; Yu, E P; Jennings, C; Cuneo, M E; Herrmann, M C; Porter, J L; Mehlhorn, T A; Apruzese, J P
2013-07-19
Detailed spectroscopic diagnostics of the stagnating plasma in two disparate z pinches allow, for the first time, the examination of the plasma properties within a 1D shock wave picture, demonstrating a good agreement with this picture. The conclusion is that for a wide range of imploding-plasma masses and current amplitudes, in experiments optimizing non-Planckian hard radiation yields, contrary to previous descriptions the stagnating plasma pressure is balanced by the implosion pressure, and the radiation energy is provided by the imploding-plasma kinetic energy, rather than by the magnetic-field pressure and magnetic-field-energy dissipation, respectively. PMID:23909333
NASA Astrophysics Data System (ADS)
Benard, N.; Balcon, N.; Touchard, G.; Moreau, E.
2008-08-01
An axisymmetric air jet exhausting from a 22-degree-angle diffuser is investigated experimentally by particle image velocimetry (PIV) and stereo-PIV measurements. Two opposite dielectric barrier discharge (DBD) actuators are placed along the lips of the diffuser in order to force the mixing by a co-flow actuation. The electrohydrodynamic forces generated by both actuators modify and excite the turbulent shear layer at the diffuser jet exit. Primary air jet velocities from 10 to 40 m/s are studied (Reynolds numbers ranging from 3.2 to 12.8 × 104), and baseline and forced flows are compared by analysing streamwise and cross-stream PIV fields. The mixing enhancement in the near field region is characterized by the potential core length, the centreline turbulent kinetic energy (TKE), the integrated value of the TKE over various slices along the jet, the turbulent Reynolds stresses and the vorticity fields. The time-averaged fields demonstrate that an effective increase in mixing is achieved by a forced flow reattachment along the wall of the diffuser at 10 m/s, whereas mixing enhancement is realized by excitation of the coherent structures for a primary velocity of 20 and 30 m/s. The actuation introduces two pairs of contra-rotating vortices above each actuator. These structures entrain the higher speed core fluid toward the ambient air. Unsteady actuations over Strouhal numbers ranging from 0.08 to 1 are also studied. The results suggest that the excitation at a Strouhal number around 0.3 is more effective to enhance the turbulence kinetic energy in the near-field region for primary jet velocity up to 30 m/s.
A kinetic-MHD model for low frequency phenomena
Cheng, C.Z.
1991-07-01
A hybrid kinetic-MHD model for describing low-frequency phenomena in high beta anisotropic plasmas that consist of two components: a low energy core component and an energetic component with low density. The kinetic-MHD model treats the low energy core component by magnetohydrodynamic (MHD) description, the energetic component by kinetic approach such as the gyrokinetic equation, and the coupling between the dynamics of these two components through plasma pressure in the momentum equation. The kinetic-MHD model optimizes both the physics contents and the theoretical efforts in studying low frequency MHD waves and transport phenomena in general magnetic field geometries, and can be easily modified to include the core plasma kinetic effects if necessary. It is applicable to any magnetized collisionless plasma system where the parallel electric field effects are negligibly small. In the linearized limit two coupled eigenmode equations for describing the coupling between the transverse Alfven type and the compressional Alfven type waves are derived. The eigenmode equations are identical to those derived from the full gyrokinetic equation in the low frequency limit and were previously analyzed both analytically nd numerically to obtain the eigenmode structure of the drift mirror instability which explains successfully the multi-satellite observation of antisymmetric field-aligned structure of the compressional magnetic field of Pc 5 waves in the magnetospheric ring current plasma. Finally, a quadratic form is derived to demonstrate the stability of the low-frequency transverse and compressional Alfven type instabilities in terms of the pressure anisotropy parameter {tau} and the magnetic field curvature-pressure gradient parameter. A procedure for determining the stability of a marginally stable MHD wave due to wave-particle resonances is also presented.
Narapusetti, Anjaneyulu; Bethanabhatla, Syama Sundar; Sockalingam, Anbazhagan; Repaka, Nagakishore; Saritha, Veldandi
2014-01-01
The liquid chromatography–tandem mass spectrometric assay method for the simultaneous determination of rosuvastatin and amlodipine in human plasma using deuterated analogs as internal standards has been developed and validated. The analytes were extracted from 100 ?L aliquots of human plasma via liquid–liquid extraction using a mixture of ethyl acetate and n-hexane (80:20, v/v) as an extraction solvent. The optimized mobile phase was composed of 0.1% formic acid in 5 mM ammonium acetate, methanol, and acetonitrile (20:20:60, v/v/v) and delivered at a flow rate of 0.75 mL/min. The calibration curve obtained was linear (R2 ? 0.999) over the concentration range of 0.52–51.77 ng/mL for rosuvastatin and 0.10–10.07 ng/mL for amlodipine. A sample turnover rate of less than 2.5 min makes it an attractive procedure in high-throughput bioanalysis of rosuvastatin and amlodipine. The present method was found to be applicable to clinical studies and the results were authenticated by incurred sample reanalysis.
Gjesdal, K; Bille, S; Bredesen, J E; Bjørge, E; Halvorsen, B; Langseth, K; Lunde, P K; Silvertssen, E
1985-01-01
Plasma glyceryl trinitrate (GTN) concentration was studied in 12 volunteers producing gun powder. Serial blood samples were obtained from the cubital vein before and during work at two sites of production; high concentrations of GTN were detected in the plasma. Control specimens from a femoral vein contained much less GTN, indicating that blood in the cubital vein was enriched by dermally absorbed GTN. In the roll mill area concentrations of GTN in the cubital vein were higher than in the press area, but individual factors were also important since some workers consistently had higher concentration of GTN than others. Differences in absorption were more important than differences in the metabolism of GTN since only a small variation in disappearance rate was found after a sublingual test dose of GTN. Moderate changes in pulse rate and blood pressure were noted during the day. The major discomfort experienced was a headache that increased during working hours, but this was not significantly related to GTN concentrations in the air or in the blood from the cubital vein. The observations imply that major efforts should be made to reduce dermal contact with GTN during production work. PMID:3917307
Chiu, Y.T.; Lennartsson, O.W.; Korth, A.; Kremser, G.; Fennell, J.F.
1986-09-30
A detailed analysis of ion composition and distribution observed simultaneously by GEOS 2, SCATHA, and ISEE 1 satellites at the initial phases of an injection event in the inner magnetosphere was made. The mean convection electric field observed by GEOS 2 during the data interval was used to determine the space-time variation of a global time-dependent convection electric-field model, which is approximately verified in this report by ISEE 1 plasma flow measurements and by the unusual SCATHA observation of low-energy ions convected from the plalsmasphere cloak region. Theoretical tracing of ion trajectories with the tested electric-field model indicates that multi-satellite observations of keV ion dispersion can be interpreted in terms of a collision/mixing between an injected auroral ion population rich in oxygen with a preinjection population rich in hydrogen and doubly-ionized helium which had previously moved inward from ISEE 1 orbit. The results of this collision/mixing was that ion dispersion signatures afterwards appeared as if they were from a single population, having lost memory of their previous convection history. This is a possible formulation mechanism of the ad hoc injection boundary which is marked only by plasma dispersion signature and not by any other magnetospheric feature.
NASA Technical Reports Server (NTRS)
Radhakrishnan, Krishnan; Bittker, David A.
1994-01-01
LSENS, the Lewis General Chemical Kinetics and Sensitivity 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 II of a series of three reference publications that describe LSENS, provide a detailed guide to its usage, and present many example problems. Part II 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 I (NASA RP-1328) derives the governing equations and describes the numerical solution procedures for the types of problems that can be solved by LSENS. Part III (NASA RP-1330) explains the kinetics and kinetics-plus-sensitivity-analysis problems supplied with LSENS and presents sample results.
NASA Astrophysics Data System (ADS)
Skála, J.; Baruffa, F.; Büchner, J.; Rampp, M.
2015-08-01
Context. The numerical simulation of turbulence and flows in almost ideal astrophysical plasmas with large Reynolds numbers motivates the implementation of magnetohydrodynamical (MHD) computer codes with low resistivity. They need to be computationally efficient and scale well with large numbers of CPU cores, allow obtaining a high grid resolution over large simulation domains, and be easily and modularly extensible, for instance, to new initial and boundary conditions. Aims: Our aims are the implementation, optimization, and verification of a computationally efficient, highly scalable, and easily extensible low-dissipative MHD simulation code for the numerical investigation of the dynamics of astrophysical plasmas with large Reynolds numbers in three dimensions (3D). Methods: The new GOEMHD3 code discretizes the ideal part of the MHD equations using a fast and efficient leap-frog scheme that is second-order accurate in space and time and whose initial and boundary conditions can easily be modified. For the investigation of diffusive and dissipative processes the corresponding terms are discretized by a DuFort-Frankel scheme. To always fulfill the Courant-Friedrichs-Lewy stability criterion, the time step of the code is adapted dynamically. Numerically induced local oscillations are suppressed by explicit, externally controlled diffusion terms. Non-equidistant grids are implemented, which enhance the spatial resolution, where needed. GOEMHD3 is parallelized based on the hybrid MPI-OpenMP programing paradigm, adopting a standard two-dimensional domain-decomposition approach. Results: The ideal part of the equation solver is verified by performing numerical tests of the evolution of the well-understood Kelvin-Helmholtz instability and of Orszag-Tang vortices. The accuracy of solving the (resistive) induction equation is tested by simulating the decay of a cylindrical current column. Furthermore, we show that the computational performance of the code scales very efficiently with the number of processors up to tens of thousands of CPU cores. This excellent scalability of the code was obtained by simulating the 3D evolution of the solar corona above an active region (NOAA AR1249) for which GOEMHD3 revealed the energy distribution in the solar atmosphere in response to the energy influx from the chromosphere through the transition region, taking into account the weak Joule current dissipation and viscosity in the almost dissipationless solar corona. Conclusions: The new massively parallel simulation code GOEMHD3 enables efficient and fast simulations of almost ideal astrophysical plasma flows with large Reynolds numbers well resolved and on huge grids covering large domains. Its abilities are verified by comprehensive set of tests of ideal and weakly dissipative plasma phenomena. The high-resolution (20483 grid points) simulation of a large part of the solar corona above an observed active region proves the excellent parallel scalability of the code up to more than 30 000 processor cores. A movie associated to Fig. 21 is available in electronic form at http://www.aanda.org
Collective effects in ultracold neutral plasmas
NASA Astrophysics Data System (ADS)
Castro Nieto, Jose Antonio
This thesis describes the measurements of collective effects in strongly coupled ultra-cold neutral plasmas (UNPs). It shows the implementation of experimental techniques that perturb either the density or velocity distribution of the plasma and it describes the subsequent excitation, observation and analysis of the aforementioned collective phenomena. UNPs are interesting in that they display physics of strongly coupled systems. For most plasma systems, collective effects are well described with classical hydrodynamic or kinetic descriptions. However, for strongly coupled systems, the Coulomb interaction energy between nearest neighbors exceeds the kinetic energy, and these descriptions must be modified as the plasma crosses over from a gas-like to liquid-like behavior. Strongly coupling can be found in exotic plasma systems found astrophysics, dusty plasmas, non-neutral trapped ion plasmas, intense-laser/matter interactions and inertial confinement fusion experiments. Compared to other strongly coupled plasmas, UNPs are ideal for studying collective effects in this regime since they have lower timescales, precisely controllable initial conditions and non-invasive diagnostics. Previous studies of UNPs concentrated on plasma expansion dynamics and some collective effects such as disorder induced heating, but little work had been done in relaxation or collision rates and collective modes in UNPs. This thesis presents a method for measuring collision rates by perturbing the velocity distribution of the plasma, observing plasma relaxation and measuring the relaxation rate. It also presents a new technique for observing collective modes in the plasma by perturbing the initial density of the plasma and how this results in the excitation of ion acoustic waves and a measurement of its dispersion relation. Finally, this thesis presents how this last technique can be used to create a gap in the center of the plasma and how this leads to hole propagation and plasma streaming and presents a characterization of both phenomena. The result of these experiments will be valuable for predicting the behavior of collective effects in other strongly coupled plasmas and for comparison with theories that describe them.
Sorokin, V.A.; Tarasenko, Yu.P.; Patrikeev, S.V.; Orlovskii, L.A.
1994-11-01
Aluminum powder and Al{sub 2}O{sub 3}-Al, Al{sub 2}O{sub 3}-SiO{sub 2}-Al, Ni-Al composites are studied within the range 20-1000{degrees}C by means of derivatography. Temperature ranges are determined for the reaction of components, interaction with each other and with the reaction medium, as well the dehydration of Al{sub 2}O{sub 3} and NiO. The kinetics of these processes are explained and their thermal effect is described. X-ray methods show that Al{sub 2}O{sub 3}-Al, Al{sub 2}O{sub 3}-SiO{sub 2}-Al composites do not change their phase composition qualitatively after heating in the derivatograph. The thermite composite NiO-Al becomes multiphase as a result of heating (NiO, Al{sub 2}O{sub 3}, NiAl{sub 2}O{sub 4}, Ni, Al, NiAl{sub 3}, NiAl).
Valdueza-Felip, S. Bellet-Amalric, E.; Pouget, S.; Monroy, E.; Wang, Y.; Chauvat, M.-P.; Ruterana, P.; Lorenz, K.; Alves, E.
2014-12-21
We report the interplay between In incorporation and strain relaxation kinetics in high-In-content In{sub x}Ga{sub 1-x}N (x?=?0.3) layers grown by plasma-assisted molecular-beam epitaxy. For In mole fractions x?=?0.13–0.48, best structural and morphological qualities are obtained under In excess conditions, at In accumulation limit, and at a growth temperature where InGaN decomposition is active. Under such conditions, in situ and ex situ analyses of the evolution of the crystalline structure with the layer thickness point to an onset of misfit relaxation after the growth of 40?nm, and a gradual relaxation during more than 200?nm, which results in an inhomogeneous strain distribution along the growth axis. This process is associated with a compositional pulling effect, i.e., indium incorporation is partially inhibited in presence of compressive strain, resulting in a compositional gradient with increasing In mole fraction towards the surface.
NASA Technical Reports Server (NTRS)
Hsu, J.-Y.; Joyce, G.; Montgomery, D.
1974-01-01
Theoretical considerations relevant to the rate of thermal relaxation of a two-dimensional plasma in a strong uniform dc magnetic field are developed. The Vahala-Montgomery (1971) kinetic description is completed by providing a cut-off time for the time of interaction of two particles contributing to the collision term. The kinetic equation is shown to predict that thermal relaxation varies as a function of defined dimensionless time.
Self-consistent Equilibrium Model of Low-aspect-ratio Toroidal Plasma with Energetic Beam Ions
E.V. Belova; N.N. Gorelenkov; C.Z. Cheng
2003-04-09
A theoretical model is developed which allows the self-consistent inclusion of the effects of energetic beam ions in equilibrium calculations of low-aspect-ratio toroidal devices. A two-component plasma is considered, where the energetic ions are treated using a kinetic Vlasov description, while a one-fluid magnetohydrodynamic description is used to represent the thermal plasma. The model allows for an anisotropic distribution function and a large Larmor radius of the beam ions. Numerical results are obtained for neutral-beam-heated plasmas in the National Spherical Torus Experiment (NSTX). Self-consistent equilibria with an anisotropic fast-ion distribution have been calculated for NSTX. It is shown for typical experimental parameters that the contribution of the energetic neutral-beam ions to the total current can be comparable to that of the background plasma, and that the kinetic modifications of the equilibrium can be significant. The range of validity of the finite-Larmor-radius expansion and of the reduced kinetic descriptions for the beam ions in NSTX is discussed. The calculated kinetic equilibria can be used for self-consistent numerical studies of beam-ion-driven instabilities in NSTX.
Salmon, E.; Brooks, D.J.; Leenders, K.L.; Turton, D.R.; Hume, S.P.; Cremer, J.E.; Jones, T.; Frackowiak, R.S. )
1990-05-01
S-(11C)Nomifensine (S-(11C)NMF) is a positron-emitting tracer suitable for positron emission tomography, which binds to both dopaminergic and noradrenergic reuptake sites in the striatum and the thalamus. Modelling of the cerebral distribution of this drug has been hampered by the rapid appearance of glucuronide metabolites in the plasma, which do not cross the blood--brain barrier. To date, (11C)NMF uptake has simply been expressed as regional versus nonspecific cerebellar activity ratios. We have calculated a free NMF input curve from red cell activity curves, using the fact that the free drug rapidly equilibrates between red cells and plasma, while glucuronides do not enter red cells. With this free (11C)NMF input function, all regional cerebral uptake curves could be fitted to a conventional two-compartment model, defining tracer distribution in terms of (11C)NMF regional volume of distribution. Assuming that the cerebellar volume of distribution of (11C)NMF represents the nonspecific volume of distribution of the tracer in striatum and thalamus, we have calculated an equilibrium partition coefficient for (11C)NMF between freely exchanging specific and nonspecific compartments in these regions, representing its binding potential to dopaminergic or noradrenergic uptake sites (or complexes). This partition coefficient was lower in the striatum when the racemate rather than the active S-enantiomer of (11C)NMF was administered. In the striatum of patients suffering from Parkinson's disease and multiple-system atrophy, the specific compartmentation of S-(11C)NMF was significantly decreased compared with that of age-matched volunteers.
Alfven waves in dusty plasmas with plasma particles described by anisotropic kappa distributions
Galvao, R. A.; Ziebell, L. F.; Gaelzer, R.; Juli, M. C. de
2012-12-15
We utilize a kinetic description to study the dispersion relation of Alfven waves propagating parallelly to the ambient magnetic field in a dusty plasma, taking into account the fluctuation of the charge of the dust particles, which is due to inelastic collisions with electrons and ions. We consider a plasma in which the velocity distribution functions of the plasma particles are modelled as anisotropic kappa distributions, study the dispersion relation for several combinations of the parameters {kappa}{sub Parallel-To} and {kappa}{sub Up-Tack }, and emphasize the effect of the anisotropy of the distributions on the mode coupling which occurs in a dusty plasma, between waves in the branch of circularly polarized waves and waves in the whistler branch.
Davidson, Ronald C.; Qin, Hong
2015-09-21
This paper makes use of a one-dimensional kinetic model to investigate the nonlinear longitudinal dynamics of a long coasting beam propagating through a perfectly conducting circular pipe with radius r w . The average axial electric field is expressed as < E_{z} >=–(?/?z)=–e_{b}g???_{b}/?z – e_{b}g_{2}r^{2}_{w}?^{3}?_{b}/?z^{3}, where g_{0} and g_{2} are constant geometric factors, ?_{b}(z,t)=?dp_{z} F_{b} (z,p_{z},t) is the line density of beam particles, and F _{b} (z,p_{z},t) satisfies the 1D Vlasov equation. Detailed nonlinear properties of traveling-wave and traveling-pulse (soliton) solutions with time-stationary waveform are examined for a wide range of system parameters extending from moderate-amplitudes to large-amplitude modulations of the beam charge density. Two classes of solutions for the beam distribution function are considered, corresponding to: (i) the nonlinear waterbag distribution, where F_{b} = const in a bounded region of p_{z}-space; and (ii) nonlinear Bernstein-Green-Kruskal (BGK)-like solutions, allowing for both trapped and untrapped particle distributions to interact with the self-generated electric field.
Davidson, Ronald C.; Qin, Hong
2015-09-21
This paper makes use of a one-dimensional kinetic model to investigate the nonlinear longitudinal dynamics of a long coasting beam propagating through a perfectly conducting circular pipe with radius r w . The average axial electric field is expressed as z >=–(?/?z)=–ebg???b/?z – ebg2r2w?3?b/?z3, where g0 and g2 are constant geometric factors, ?b(z,t)=?dpz Fb (z,pz,t) is the line density of beam particles, and F b (z,pz,t) satisfies the 1D Vlasov equation. Detailed nonlinear properties of traveling-wave and traveling-pulse (soliton) solutions with time-stationary waveform are examined for a wide range of system parameters extending from moderate-amplitudes to large-amplitude modulations ofmore »the beam charge density. Two classes of solutions for the beam distribution function are considered, corresponding to: (i) the nonlinear waterbag distribution, where Fb = const in a bounded region of pz-space; and (ii) nonlinear Bernstein-Green-Kruskal (BGK)-like solutions, allowing for both trapped and untrapped particle distributions to interact with the self-generated electric field.« less
NASA Astrophysics Data System (ADS)
Davidson, Ronald C.; Qin, Hong
2015-09-01
This paper makes use of a one-dimensional kinetic model to investigate the nonlinear longitudinal dynamics of a long coasting beam propagating through a perfectly conducting circular pipe with radius rw. The average axial electric field is expressed as ?Ez?=-(?/?z )?? ?=-ebg0??b/?z -ebg2rw2?3?b/?z3, where g0 and g2 are constant geometric factors, ?b(z ,t )=?d pzFb(z ,pz,t ) is the line density of beam particles, and Fb(z ,pz,t ) satisfies the 1D Vlasov equation. Detailed nonlinear properties of traveling-wave and traveling-pulse (soliton) solutions with time-stationary waveform are examined for a wide range of system parameters extending from moderate-amplitudes to large-amplitude modulations of the beam charge density. Two classes of solutions for the beam distribution function are considered, corresponding to: (i) the nonlinear waterbag distribution, where Fb=const in a bounded region of pz-space; and (ii) nonlinear Bernstein-Green-Kruskal (BGK)-like solutions, allowing for both trapped and untrapped particle distributions to interact with the self-generated electric field ?Ez?.
Kinetic theory of the magnetic Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Onishchenko, O. G.; Pokhotelov, O. A.
2013-09-01
We consider the problem of stabilization of the Rayleigh-Taylor (RT) instability by the effects of the finite ion Larmor radius in a plasma with a curvilinear magnetic field. To this end, we use a kinetic description of flute waves generated by the RT instability with an arbitrary (with respect to the ion Larmor radius) wavelength. It is shown that disturbances with a characteristic scale of the order of the ion Larmor radius make a significant contribution to the instability increment and modify the well-known classic conditions for stabilization.
Constraints on fluid modeling of magnetized collisionless plasmas
NASA Astrophysics Data System (ADS)
Sulem, Pierre-Louis; Passot, Thierry; Laveder, Dimitri; Hunana, Peter; Henri, Pierre
2013-04-01
It is well known that a complete description of the solar wind requires a kinetic description and that, particularly at sub-proton scales, kinetic effects cannot be ignored. It is nevertheless usually assumed that, at scales significantly larger than the proton gyroscale, MHD or bifluid models with isotropic pressures provide a satisfactory description. We demonstrate that in order to accurately capture, even at large scales, the low-frequency dynamics of a collisionless plasma, a fluid model should actually include kinetic effects such as Landau damping and finite Larmor radius corrections. Indeed, the usual polytropic bi-fluid models strongly overestimate the magnetic compressibility of oblique Alfvén waves. Retaining pressure anisotropy and Landau damping partially corrects this deficiency, but an accurate description of the Alfvén wave polarization and of the mirror instability growth rate actually requires to take into account the finite-Larmor corrections to all the retained moments. These remarks lead us to use the so-called FLR Landau fluid model (Phys. Plasmas, 19, 082113, 2012), for which a three-dimensional parallel code has been developed. Preliminary simulations in the turbulent regime will be presented, showing the reduction of the fluid compressibility and the inhibition of the parallel energy transfer. We will also report on the development of temperature anisotropy, associated with non-resonant perpendicular ion heating and constrained by the onset of the mirror instability.
Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.
1996-05-01
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.
NASA Astrophysics Data System (ADS)
Maurer, Calvin R., Jr.; Sauer, Frank; Hu, Bo; Bascle, Benedicte; Geiger, Bernhard; Wenzel, Fabian; Recchi, Filippo; Rohlfing, Torsten; Brown, Christopher R.; Bakos, Robert J.; Maciunas, Robert J.; Bani-Hashemi, Ali R.
2001-05-01
We are developing a video see-through head-mounted display (HMD) augmented reality (AR) system for image-guided neurosurgical planning and navigation. The surgeon wears a HMD that presents him with the augmented stereo view. The HMD is custom fitted with two miniature color video cameras that capture a stereo view of the real-world scene. We are concentrating specifically at this point on cranial neurosurgery, so the images will be of the patient's head. A third video camera, operating in the near infrared, is also attached to the HMD and is used for head tracking. The pose (i.e., position and orientation) of the HMD is used to determine where to overlay anatomic structures segmented from preoperative tomographic images (e.g., CT, MR) on the intraoperative video images. Two SGI 540 Visual Workstation computers process the three video streams and render the augmented stereo views for display on the HMD. The AR system operates in real time at 30 frames/sec with a temporal latency of about three frames (100 ms) and zero relative lag between the virtual objects and the real-world scene. For an initial evaluation of the system, we created AR images using a head phantom with actual internal anatomic structures (segmented from CT and MR scans of a patient) realistically positioned inside the phantom. When using shaded renderings, many users had difficulty appreciating overlaid brain structures as being inside the head. When using wire frames, and texture-mapped dot patterns, most users correctly visualized brain anatomy as being internal and could generally appreciate spatial relationships among various objects. The 3D perception of these structures is based on both stereoscopic depth cues and kinetic depth cues, with the user looking at the head phantom from varying positions. The perception of the augmented visualization is natural and convincing. The brain structures appear rigidly anchored in the head, manifesting little or no apparent swimming or jitter. The initial evaluation of the system is encouraging, and we believe that AR visualization might become an important tool for image-guided neurosurgical planning and navigation.
Supplementary kinetic constants of charged particles
Marijan Ribaric; Luka Sustersic
2006-12-21
We put forward: (A) An improved description of classical, kinetic properties of a charged pointlike physical particle that consists, in addition to its mass and charge, also of the Eliezer and Bhabha kinetic constants; and (B) a proposal to evaluate these kinetic constants by considering the trajectories of charged particles in an acccelerator.
Ion temperature in plasmas with intrinsic Alfven waves
Wu, C. S.; Yoon, P. H.; Wang, C. B.
2014-10-15
This Brief Communication clarifies the physics of non-resonant heating of protons by low-frequency Alfvenic turbulence. On the basis of general definition for wave energy density in plasmas, it is shown that the wave magnetic field energy is equivalent to the kinetic energy density of the ions, whose motion is induced by the wave magnetic field, thus providing a self-consistent description of the non-resonant heating by Alfvenic turbulence. Although the study is motivated by the research on the solar corona, the present discussion is only concerned with the plasma physics of the heating process.
Fluid modeling for ion scale space plasmas
NASA Astrophysics Data System (ADS)
Passot, Thierry; Sulem, Pierre-Louis
2014-05-01
Fluid models with first-order finite Larmor radius (FLR) corrections have been known since the early sixties. It however turns out that a correct dispersion relation for oblique Alfvén waves requires FLR corrections of at least second order in an asymptotics based on temporal and spatial scale separation. Supplementing Landau damping, that provides an essential ingredient for a realistic description of Alfvénic turbulence, is moreover delicate as, in these models, the combination of dispersive and dissipative effects can produce spurious instabilities in some parameter regimes. We thus propose a new kind of fluid model, closed at the level of the fourth-rank moments, that combines the advantages of fully-nonlinear large-scale FLR models, with a small-scale regularization where the nongyrotropic contributions of all the retained moments are evaluated consistently with the low-frequency linear kinetic physics, down to transverse scales comparable to or smaller than the ion gyroradius [see Phys. Plasmas 14, 082502 (2007), Phys. Plasmas 19, 082113 (2012)]. This model, which is based on a matching of the FLR expressions derived both from the fluid formalism and from the kinetic theory, is asymptotically valid at large scales. The small-scale "sub-grid" modeling leads to an accurate description of the linear properties of kinetic Alfvén waves and of the mirror instability, but also provides the correct (in the absence of cyclotron resonance) and sufficient dissipation for turbulent simulations, allowing for the development of power law spectra extending to the smallest resolved scale.
Nonlinear kinetic model for lower-hybrid solitary structures
Jovanovic, D.; Shukla, P. K.; Morfill, G.
2007-08-15
Nonlinear drift-kinetic theory is proposed for lower-hybrid solitary structures in near-Earth plasmas, based on a two time scale kinetic description of nonlinear interactions between the lower-hybrid and dispersive Alfven waves. The detailed derivation of the nonlinear coupling terms in an arbitrary geometry is presented, that include the ponderomotive potential, non-curl-free component of the perpendicular electron velocity, and the electron diffusion in velocity space. It is shown that the resonant particles are trapped by the combined effects of the slow and ponderomotive potentials, and that their density is further modified by their diffusion in velocity space, yielding a new type of coherent structure, which is identified as an electron hole, coupled with a nonlinear Schroedinger-type soliton. A numerical solution is found in the form of train of soliton-like lower-hybrid spikes, trapped inside a weakly two-dimensional slab electron hole.
Holographic kinetic k-essence model
Norman Cruz; Pedro F. Gonzalez-Diaz; Alberto Rozas-Fernandez; Guillermo Sanchez
2009-08-23
We consider a connection between the holographic dark energy density and the kinetic k-essence energy density in a flat FRW universe. With the choice $c\\geq1$, the holographic dark energy can be described by a kinetic k-essence scalar field in a certain way. In this paper we show this kinetic k-essential description of the holographic dark energy with $c\\geq1$ and reconstruct the kinetic k-essence function F(X).
NASA Astrophysics Data System (ADS)
Karpov, S. A.; Potapenko, I. F.
2015-10-01
A stochastic method of simulation of Coulomb interaction is considered. The main idea of the method is to approximate the nonlinear Landau kinetic collision integral by the Boltzmann integral. In its realization, the method can be attributed to a wide class of Monte Carlo-type methods. It is easily combined with the existing particle methods used to simulate collisionless plasmas. This is important for simulation of the dynamics of both laboratory and space plasmas when the mean free path of plasma particles is comparable with the plasma inhomogeneity scale length. Illustrative examples of relaxation of two-temperature plasma being subject to a high-frequency alternating electric field are given, and differences from their classical description are considered. The method satisfies the conservation laws for the number of particles, momentum, and energy and is simple and efficient in implementation.
ERIC Educational Resources Information Center
Wilson, David B.
1981-01-01
Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)
Simulations of 4D edge transport and dynamics using the TEMPEST gyro-kinetic code
NASA Astrophysics Data System (ADS)
Rognlien, T. D.; Cohen, B. I.; Cohen, R. H.; Dorr, M. R.; Hittinger, J. A. F.; Kerbel, G. D.; Nevins, W. M.; Xiong, Z.; Xu, X. Q.
2006-10-01
Simulation results are presented for tokamak edge plasmas with a focus on the 4D (2r,2v) option of the TEMPEST continuum gyro-kinetic code. A detailed description of a variety of kinetic simulations is reported, including neoclassical radial transport from Coulomb collisions, electric field generation, dynamic response to perturbations by geodesic acoustic modes, and parallel transport on open magnetic-field lines. Comparison is made between the characteristics of the plasma solutions on closed and open magnetic-field line regions separated by a magnetic separatrix, and simple physical models are used to qualitatively explain the differences observed in mean flow and electric-field generation. The status of extending the simulations to 5D turbulence will be summarized. The code structure used in this ongoing project is also briefly described, together with future plans.
NASA Astrophysics Data System (ADS)
Esaulov, A. A.; Johnson, W. R.; Safronova, A. S.; Safronova, U. I.; Kantsyrev, V. L.; Weller, M. E.; Ouart, N. D.
2012-09-01
The LTE Saha-Boltzmann plasma ionization balance model and the Braginskii plasma electric resistance model are compared with the results by a suite of codes based on the average-atom model, which is a quantum-mechanical version of the Temperature Dependent Thomas-Fermi Theory. The analysis is focused on low-Z Al, mid-Z Cu and higher-Z Mo plasmas over broad ranges of electron temperature Te and electron number density ne. Calculations of mean ion charge by these two LTE models are compared to the results produced by non-LTE atomic kinetic codes. The applicability of the LTE and non-LTE models to the description of the radiative properties of highly-radiating z-pinch plasmas is also discussed. Two different approaches to the calculation of plasma resistance and their effects on line radiation mechanisms are analyzed.
Vaudolon, J. Mazouffre, S.
2014-09-15
The evaluation of electric fields is of prime interest for the description of plasma characteristics. In this work, different methods for determining the electric field profile in low-pressure discharges using one- and two-dimensional Laser-Induced Fluorescence (LIF) measurements are presented and discussed. The energy conservation, fluid, and kinetic approaches appear to be well-suited for the electric field evaluation in this region of the plasma flow. However, the numerical complexity of a two-dimensional kinetic model is penalizing due to the limited signal-to-noise ratio that can be achieved, making the computation of the electric field subject to large error bars. The ionization contribution which appears in the fluid model makes it unattractive on an experimental viewpoint. The energy conservation and 1D1V kinetic approaches should therefore be preferred for the determination of the electric field when LIF data are used.
Hong, Juhee
We compute the nonequilibrium stress tensor induced by a heavy quark moving through weakly coupled QCD plasma at the speed of light and compare the result to N=4 super-Yang-Mills theory at strong coupling. The QCD Boltzmann ...
Fluid modeling of magnetized plasmas with anisotropic temperatures
NASA Astrophysics Data System (ADS)
Sulem, P. L.; Passot, T.
2012-04-01
We discuss a fluid model for magnetized plasmas that extends the anisotropic magnetohydrodynamics down to the ion gyroscale and below, by retaining low-frequency kinetic effects such as Landau damping and finite Larmor radius (FLR) corrections. Landau damping depletes compressible effects and inhibits longitudinal transfer, but also leads to a correct description of the mirror instability threshold, while FLR corrections arrest the mirror instability at small scales and ensures an accurate dispersion relation for kinetic Alfvén waves. This model provides an efficient tool to describe the solar wind dynamics. Simulations of non-resonant ion perpendicular heating under the effect of turbulence driven by kinetic Alfvén waves, together with the constraining effect of the resulting mirror instability that maintains the system near threshold are in particular discussed and successfully compared with slow solar wind observations.
NASA Astrophysics Data System (ADS)
Karimabadi, H.; Omelchenko, Y.; Schunk, R. W.; Barakat, A. R.; Gardner, L. C.; Khazanov, G. V.; Glocer, A.; Kistler, L. M.
2013-12-01
The Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is complex; it varies on a wide range in spatial and temporal scales, exhibits relatively thin ion-scale boundaries (e.g., bow shock, magnetopause, magnetotail), contains hot and cold particle populations, and the particle distribution functions are typically non-Maxwellian. The existing space weather frameworks are based on global fluid models and therefore cannot address many important issues concerning particle, momentum, and energy coupling in the system. To remedy this situation, we have formed a multi-disciplinary team to create a new kinetic modeling framework. The new framework will include kinetic electron and ion formulations for the ionosphere, plasmasphere, and polar wind domains, and kinetic ions and fluid electrons for the magnetosphere. The proposed methodology is expected to lead to breakthroughs in studying numerous problems/issues, including the self-consistent formation of the ring current, the self-consistent formation of ion scale turbulence and waves, the calculation of appropriate reconnection rates, the effect that multiple species and ion outflows from the ionosphere have on the development and evolution of storms/substorms, among others. The presentation will focus on the current state and capabilities of the global kinetic models that form the framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind Model.
A macroscopic plasma Lagrangian and its application to wave interactions and resonances
NASA Technical Reports Server (NTRS)
Peng, Y. K. M.
1974-01-01
The derivation of a macroscopic plasma Lagrangian is considered, along with its application to the description of nonlinear three-wave interaction in a homogeneous plasma and linear resonance oscillations in a inhomogeneous plasma. One approach to obtain the Lagrangian is via the inverse problem of the calculus of variations for arbitrary first and second order quasilinear partial differential systems. Necessary and sufficient conditions for the given equations to be Euler-Lagrange equations of a Lagrangian are obtained. These conditions are then used to determine the transformations that convert some classes of non-Euler-Lagrange equations to Euler-Lagrange equation form. The Lagrangians for a linear resistive transmission line and a linear warm collisional plasma are derived as examples. Using energy considerations, the correct macroscopic plasma Lagrangian is shown to differ from the velocity-integrated low Lagrangian by a macroscopic potential energy that equals twice the particle thermal kinetic energy plus the energy lost by heat conduction.
Matalas, N.C.
1991-01-01
What constitutes a comprehensive description of drought, a description forming a basis for answering why a drought occurred is outlined. The description entails two aspects that are "naturally" coupled, named physical and economic, and treats the set of hydrologic measures of droughts in terms of their multivariate distribution, rather than in terms of a collection of the marginal distributions. ?? 1991 Springer-Verlag.
Physics issues associated with low-beta plasma generators
NASA Technical Reports Server (NTRS)
Borovsky, Joseph E.
1992-01-01
Kinetic aspects of MHD generators are explored by examining the propagation of dense, low-beta streams of plasma. Three situations are considered: the basic principles of plasma-stream propagation, the propagation of plasma streams into vacuum, and the propagation of plasma streams into ambient plasmas. These three situations are analogous to plasma generators, plasma generators with vacuum loads, and plasma generators with plasma loads. Kinetic (microphysics) aspects include oscillations of the generator plasma, the effects of diocotron instabilities, the acceleration of particles, the starvation of current systems, and plasma-wave production.
NASA Technical Reports Server (NTRS)
Dobson, Chris C.; Hrbud, Ivana
2004-01-01
Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the 1-D Poisson equation for EC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with non-fusing hydrogen-1. The deuterium rates are consistent with predictions from the model.
Botha, R.; Haj Ibrahim, B.; Bulkin, P.; Drevillon, B.
2008-09-15
High-rate, low temperature deposition is an essential requirement for industrial fabrication technology to be suitable for the deposition of optical and protective coatings. High-density, low-pressure plasmas have received significant attention for such applications due to their ability to create large and controllable ion fluxes onto the substrate. In this study, the high-rate deposition of silica films from a silane and oxygen gas mixture in a high-density plasma system based on a matrix distributed electron cyclotron resonance (MDECR) plasma source is investigated using directional jet injection of undiluted silane. The influence of process parameters such as the microwave power, radio frequency biasing of the substrate holder, and gas flows on the OH content of the oxide films is studied using phase-modulated spectroscopic ellipsometry (SE), Fourier transform infrared (FTIR) spectroscopy, and transmission measurements. The results of the measurements, taken at various points across the wafer, show a decrease in the thickness-normalized OH concentration in the areas of higher deposition rates. The corresponding gas phase composition is investigated using optical emission spectroscopy and compared to the FTIR, transmission and SE measurement results in order to validate our findings and ultimately optimize the deposition process. It is found that the primary silane flux onto the surface, which depends on the positioning of the jet injection point and gas flow rate, plays an important role not only on the deposition rate but also on the OH content of the films. The authors conclude that high-density plasma deposition systems such as the MDECR plasma enhanced chemical vapor deposition system cannot be considered as well mixed for gases with dissociation products that have high sticking coefficients, contrary to the accepted paradigm.
Plasma Currents and Electron Distribution Functions under a dc Electric Field of Arbitrary Strength
Weng, S. M.; He, M. Q.; Sheng, Z. M.; Zhang, J.; Norreys, P. A.; Sherlock, M.; Robinson, A. P. L.
2008-05-09
The currents induced by arbitrarily strong dc electric fields in plasma and the evolution of electron distributions have been studied by Fokker-Planck simulations. We find that the electron distributions evolve distinctly under different fields; especially, the electron distribution is well represented by the sum of a stationary and drifting Maxwellian at the moderate field. A set of hydrodynamiclike equations, similar to Spitzer's but without the weak-field limit, is given for calculating the current. It is more suitable for application in hybrid particle-in-cell simulations and may extend plasma transport theory in models that do not employ a kinetic description of the electrons.
Nonlinear instability saturation due to quasi-particle trapping in a turbulent plasma
Mendonca, J. T.; Benkadda, S.
2012-08-15
We consider the problem of a single wave mode stability, dispersion, and nonlinear saturation in a turbulent plasma background. We adopt a wave kinetic description for the quasi-particle turbulence and assume a low frequency perturbation of both the plasma and the turbulent spectrum. We describe an improved theoretical approach, which goes beyond the geometric optics approximation and retains the recoil effects associated with the emission and absorption of low frequency waves by nearly resonant quasi-particles. We illustrate the present approach by considering the case of zonal flow excited by drift wave turbulence.
Modulational interactions in quantum plasmas
Sayed, F.; Tyshetskiy, Yu.; Vladimirov, S. V.; Faculty of Engineering, Yokohama National University, Yokohama 240-8501; Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 ; Ishihara, O.
2013-07-15
A formalism for treating modulational interactions of electrostatic fields in collisionless quantum plasmas is developed, based on the kinetic Wigner-Poisson model of quantum plasma. This formalism can be used in a range of problems of nonlinear interaction between electrostatic fields in a quantum plasma, such as development of turbulence, self-organization, as well as transition from the weak turbulent state to strong turbulence. In particular, using this formalism, we obtain the kinetic quantum Zakharov equations that describe nonlinear coupling of high frequency Langmuir waves to low frequency plasma density variations, for cases of non-degenerate and degenerate plasma electrons.
Akamatsu, Yukinao; Yamamoto, Naoki
2013-08-01
We study the collective modes in relativistic electromagnetic or quark-gluon plasmas with an asymmetry between left- and right-handed chiral fermions, based on the recently formulated kinetic theory with Berry curvature corrections. We find that there exists an unstable mode, signaling the presence of a plasma instability. We argue the fate of this "chiral plasma instability" including the effect of collisions, and briefly discuss its relevance in heavy ion collisions and compact stars. PMID:23952387
Kwon, Ohseung; Bai Bo; Sawin, Herbert H.
2006-09-15
Silicon oxide etching was modeled using a translating mixed-layer model, a novel surface kinetic modeling technique, and the model showed good agreement with measured data. Carbon and fluorine were identified as the primary contributors to deposition and etching, respectively. Atomic fluorine flux is a major factor that determines the etching behavior. With a chemistry having a small amount of atomic fluorine (such as the C{sub 4}F{sub 8} chemistry), etching yield shows stronger dependence on the composition change in the gas flux.
Energy Science and Technology Software Center (ESTSC)
2000-03-20
Given the space-independent, one energy group reactor kinetics equations and the initial conditions, this prgram determines the time variation of reactivity required to produce the given input of flux-time data.
Dimarco, Giacomo; Mieussens, Luc; Rispoli, Vittorio
2014-10-01
In this work we present an efficient strategy to deal with plasma physics simulations in which localized departures from thermodynamical equilibrium are present. The method is based on the introduction of intermediate regions which allows smooth transitions between kinetic and fluid zones. In this paper we extend Domain Decomposition techniques, obtained through dynamic coupling and buffer zones, to the study of plasmas and, moreover, we combine them with Asymptotic Preserving and Asymptotically Accurate strategies for the time integration. We use a hybrid scheme in which both kinetic and fluid descriptions are considered and coupled together while the kinetic model is solved by asymptotic preserving and accurate methods, in order to guarantee high efficiency and accuracy in all regimes. The numerical scheme is validated and its performances are analyzed by numerical simulations.
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.
Capolupo, A; Giampaolo, S M; Illuminati, F
2013-10-01
Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments. PMID:24229140
Kinetic Actviation Relaxation Technique
Béland, Laurent Karim; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand
2011-01-01
We present a detailed description of the kinetic Activation-Relaxation Technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si, self-interstitial diffusion in Fe and structural relaxation in amorphous silicon.
Adding linear kinetic effects to existing finite-difference simulations
Green, David L; Berry, Lee Alan
2013-01-01
We present the proof-of-principle KINETIC-J module for iterative addition of all-order kinetic effects (parallel and perpendicular) in both the IC and EC frequency ranges, to any existing FD or FE frequency-domain full-wave RF simulation. The module calculates the linear, kinetic plasma current, such that given f 0 (r,v) and the cold plasma solution as an initial guess at the wave electric field, iterating the KINETIC-J module and the existing code (its internal plasma current replaced with the output of the module) converges to the kinetic solution. Since KINETIC-J does not use the k-space representation of the hot plasma dielectric, in favor of data parallel numeric integrals, implementing the module requires minimal code changes.
KINETICS STUDY OF CHLORIDE IN RAT
The kinetics of chloride were studied in Sprague-Dawley rats following the oral administration of Na36Cl. The half-life for (36)Cl(-1) absorption from plasma was 19.2 hr corresponding to a rate constant of 0.0361 hr, while the half-life for (36)Cl(-1) elimination from plasma was ...
NASA Astrophysics Data System (ADS)
Rajan, Karthikeyan; Shanmugasundaram, Thangaraju; Subramanya Sarma, Vadlamani; Murty, B. S.
2013-09-01
Nanocrystalline mechanically alloyed powders of 9Cr-1Mo ferritic steels with and without yttria dispersoids were densified using spark plasma sintering (SPS) to near-theoretical density at a temperature of 1073 K (800 °C). Studies on densification behaviour revealed that steels with dispersoids densified faster when compared to Fe-9Cr-1Mo steel. The evaluation of densification mechanisms during SPS reveals that grain boundary and lattice diffusion to be predominant at relative densities ranging from >0.7 to 0.9 in both the alloys.
Theory of the unmagnetized plasma.
NASA Technical Reports Server (NTRS)
Montgomery, D. C.
1971-01-01
The Vlasov mathematical model of a plasma, which has come to be thought more useful than any other in describing the dynamical behavior of the majority of plasmas of interest, is first examined. Macroscopic variables and moment equations; linear electrostatics solutions; plasma oscillations, ion acoustic waves, and linear instabilities are treated, as well as external fields, 'test' charges, and nonlinear Vlasov phenomena. Plasmas are statistically described, and attention is given to the kinetic theory of the stable, uniform plasma and the Balescu-Lenard equation; two-time ensemble averages and fluctuation spectra in stable plasmas; the kinetic theory of the unstable plasma; and ensembles of Vlasov plasmas. Some illustrative experiments are described. Four appendixes deal with the electrostatic approximation and transverse waves; solution of the linearized Vlasov equation in a magnetic field; estimates of correlation functions from thermal equilibrium; and equivalence of spatially uniform BBGKY and Klimontovich correlations.
Kinetic Theory of the Alfvn Wave Acceleration of Auroral Electrons Robert L. Lysak and Yan Song
Lysak, Bob
Kinetic Theory of the Alfvén Wave Acceleration of Auroral Electrons Robert L. Lysak and Yan Song into the plasma sheet boundary layer, the plasma gradients are relatively weak and the local kinetic theory can that describe the time development of the parallel electric fields. However, most of the kinetic theories
Nonlocal kinetic theory of Alfven waves on dipolar field lines Robert L. Lysak and Yan Song
Lysak, Bob
Nonlocal kinetic theory of Alfve´n waves on dipolar field lines Robert L. Lysak and Yan Song School kinetic theory of electrons along auroral field lines is necessary to provide this self and instabilities; 7827 Space Plasma Physics: Kinetic and MHD theory; 7867 Space Plasma Physics: Wave
Laser-seeded modulation instability in a proton driver plasma wakefield accelerator
Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander
2013-10-15
A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (?100–1000 m)
Theory of electrostatic waves in an E region plasma. 1. General formulation
Stubbe, P. )
1989-05-01
In the kinetic theory of waves in an E region plasma, collisions are usually represented by a relaxation model. The particular model used in previous work affords a realistic description of frictional effects, but is not well suited for the description of energy transfer and isotropization. The present paper gives an improved theory of electrostatic waves in an E region plasma by using a new relaxation model which describes realistically momentum transfer, energy transfer, and isotropization. Both kinetic and fluid results are derived, the latter by expansion of the kinetic results into the fluid regime. It is thereby assured that the kinetic and the fluid results are continuously connected with each other. The ion gas is treated in the weak magnetic field limit. Particular emphasis is placed on the polytropic exponent, and its transition from the one-dimensionally adiabatic limit to the isothermal limit, as the number of encounters increases, is discussed in detail. The electron gas is treated in the strong magnetic field limit. The general results are simplified in a sequence of approximations, pertinent to cases of practical interest, as, for instance, electrojet instabilities and incoherent scatter.
NASA Astrophysics Data System (ADS)
Klyucharev, A. N.; Bezuglov, N. N.; Mihajlov, A. A.; Ignjatovic, Lj. M.
2010-07-01
Elementary processes in plasma phenomena traditionally attract physicist`s attention. The channel of charged-particle formation in Rydberg Atom-Atom thermal and subthermal collisions (the low temperature plasmas conditions) leads to creation of the molecular ions - associative ionization (AI), atomic ions - penning-like ionization (PI) and the pair of the negative and positive ions. In our universe the chemical composition of the primordial gas consists mainly of Hydrogen and Helium (H, H- , H+, H2, He, He+ ), Hydrogen-like alkali-metal Litium (Li, Li+, Li-) and combinations (HeH+ , LiH- , LiH+). There is a wide range of plasma parameters in which the Rydberg Atoms of the elements called above make the dominant construction to ionization and that process may be regarded as a prototype of the elementary process of light excitation energy transformation into electric one. The first series of quantitative measurements of the rate constants for Rydberg Atoms starts in 1978 (Devdariani, Klyucharev et al.). The method of AI and PI calculations, so-called "dipole resonant" mechanism proposed in 1971 (Smirnov, Mihaylov) was used in semiclassical (Mihailov and Janev 1981) and quantum mechanical theories (Duman, Shmatov, 1980). The latest stochastic version of chemi-ionisation (AI+PI) on Rydberg Atom - Atom collisions extends the treatment of the "dipole resonant" model by taking into account redistribution of population over a range of Rydberg states prior to ionization. This redistribution is modeled as diffusion in the frame of stochastic dynamic of the Rydberg electron in the Rydberg energy spectrum (Bezuglov, Borodin, Klyucharev et al. 1997). Such approach makes it possible to operate on efficiently of inelastic collisional processes and sometimes to operate on time of Rydberg Atoms life. This may lead to anomalies of Rydberg Atoms spectra. Another result obtained in recent time is understanding that experimental results on chemi-ionization relate to the group of mixed Rydberg Atom closed to the primary selected one. The Rydberg Atoms ionisaton theory today makes a valuable contribution in the deterministic and stochastic approaches correlation in atomic physic.
Descriptive epidemiology studies characterize cancer incidence and mortality temporal trends, age-specific rates, geographic distribution of cancer, race and ethnic differences in cancer rates, and birth cohort effects.
Tsventoukh, M. M.
2010-10-15
A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as {beta} {approx} 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field than those obtained with the simplest MHD description.