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.
On kinetic description of electromagnetic processes in a quantum plasma
Tyshetskiy, Yu.; Vladimirov, S. V.; Kompaneets, R.
2011-11-15
A nonlinear kinetic equation for nonrelativistic quantum plasma with electromagnetic interaction of particles is obtained in the Hartree's mean-field approximation. It is cast in a convenient form of Vlasov-Boltzmann-type equation with ''quantum interference integral'', which allows for relatively straightforward modification of existing classical Vlasov codes to incorporate quantum effects (quantum statistics and quantum interference of overlapping particles wave functions), without changing the bulk of the codes. Such modification (upgrade) of existing Vlasov codes may provide a direct and effective path to numerical simulations of nonlinear electrostatic and electromagnetic phenomena in quantum plasmas, especially of processes where kinetic effects are important (e.g., modulational interactions and stimulated scattering phenomena involving plasma modes at short wavelengths or high-order kinetic modes, dynamical screening and interaction of charges in quantum plasma, etc.) Moreover, numerical approaches involving such modified Vlasov codes would provide a useful basis for theoretical analyses of quantum plasmas, as quantum and classical effects can be easily separated there.
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.
Kinetic theory of QED plasmas in a strong electromagnetic field. II. The mean-field description
A. Hoell; V. Morozov; G. Roepke
2001-06-01
Starting from a general relativistic kinetic equation, a self-consistent mean-field equation for fermions is derived within a covariant density matrix approach of QED plasmas in strong external fields. A Schr\\"odinger picture formulation on space-like hyperplanes is applied. The evolution of the distribution function is described by the one-particle gauge-invariant 4x4 Wigner matrix, which is decomposed in spinor space. A coupled system of equations for the corresponding Wigner components is obtained. The polarization current is expressed in terms of the Wigner function. Charge conservation is obeyed. In the quasi-classical limit for the Wigner components a relativistic Vlasov equation is obtained, which is presented in an invariant, i.e. hyperplane independent, form.
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.
Population kinetics in fluctuating plasmas
Catoire, F.; Capes, H.; Marandet, Y.; Mekkaoui, A.; Rosato, J.; Koubiti, M.; Stamm, R. [Laboratoire de Physique des Interactions Ioniques et Moleculaires, UMR 6633 CNRS-Universite de Provence, Centre de Saint Jerome, Marseille F-13397 (France)
2011-01-15
We address a model for atomic population kinetics in fluctuating plasmas. An analytical expression for the ensemble-average populations is obtained in terms of two statistical functions that can be retrieved experimentally, namely the probability density function and the autocorrelation of the plasma fluid fields. This expression, allowing for very fast calculations, is of great interest to thoroughly analyze the radiative properties of fluctuating plasmas. Two limits, where the fluctuations are either faster or slower than the atomic relaxation time scales, are discussed in detail. Finally, an application to atomic hydrogen is presented.
Computer models for kinetic equations of magnetically confined plasmas
Killeen, J.; Kerbel, G.D.; McCoy, M.G.; Mirin, A.A.; Horowitz, E.J.; Shumaker, D.E.
1987-01-01
This paper presents four working computer models developed by the computational physics group of the National Magnetic Fusion Energy Computer Center. All of the models employ a kinetic description of plasma species. Three of the models are collisional, i.e., they include the solution of the Fokker-Planck equation in velocity space. The fourth model is collisionless and treats the plasma ions by a fully three-dimensional particle-in-cell method.
Kinetics of Ar-Hg plasma in dielectric barrier discharge
NASA Astrophysics Data System (ADS)
Xu, Xueji; Jie, Yiaxiong
1995-11-01
A kinetic description of the Ar-Hg plasma in dielectric barrier discharge is given on the basis of establishing a Collisional Radiative Atomic and Molecular Model (CRAM). The population transfers among atoms and excimers are taken into account. A new method to treat the recombination of electrons and ionized particles is developed. The time-dependent model gives us a description of the evolution of the plasma phase performing chemical reactions in a microdischarge and the spectroscopic information on the atomic and molecular radiation as well.
Kinetic Modeling of Martian Atmosphere Aerobraking Plasma
NASA Astrophysics Data System (ADS)
Drake, Dereth; Smithwick, Evan
2014-10-01
During Martian atmospheric aerobraking the plasma that forms around a spacecraft can be considered a high-volume plasma reactor that is sustained by the dissipation of the spacecraft's kinetic energy. At altitudes below 100 km, it has been shown that the plasma parameters vary considerably depending on the spacecraft's trajectory. However, in the range which is applicable to aerobraking, 100 km < h < 200 km, little of this work has been completed. We have evaluated a simple kinetic model to determine a probable range of plasma parameters for altitudes between 100 and 200 km using existing Martian atmospheric data and available probe trajectories.
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.
Wave kinetics of relativistic quantum plasmas
Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
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.
Kinetic equilibria of plasma shear layers
NASA Technical Reports Server (NTRS)
Cai, D.; Storey, L. R. O.; Neubert, T.
1990-01-01
The analysis of plasma beam and shear problems in magnetic fields is usually based on a hydromagnetic fluid model. In a low-density collisionless plasma, however, the kinetic effects of the plasma, such as finite Larmor radius effects, are not yet clearly understood. In this paper, the kinetic equilibria of plasma shears in a uniform and fixed magnetic field, with full ion motion, are discussed by solving the Vlasov equation with a given electric field and drift velocity. In this model, the ion density profile through the plasma shear layer is quite different from the one predicted by a hydromagnetic model. As a result of a complicated ion gyromotion through the shear layer, single- and double-humped ion density profiles are obtained. The dependence on the temperature and the strength of the shear will be discussed. The results show a significant difference between positive and negative shears.
Numerical method for kinetic dense plasma transport
NASA Astrophysics Data System (ADS)
Adams, Mark L.
2011-10-01
The development of novel theoretical and computational kinetic models is required to describe the nonlocal and non-Markovian transport channels that exist in a growing number of high energy density physics (HEDP) laboratory experiments. In this poster I develop a numerical method that significantly accelerates the convergence of computational kinetic transport methods in dense plasmas. The method self- consistently couples a kinetic transport model with a set of moment equations that conserve mass, momentum, and energy as well as retain the salient properties of the Boltzmann H-theorem. Extensions of the method to multi-component plasmas and dynamic boundary conditions are considered. I illustrate the method using common parallel plate, shock, and plasma relaxation problems; the examples show rapid convergence in the collisional limit and retain the appealing properties of the kinetic transport computational method in the collisionless limit. The numerical method it is easily extensible to more sophisticated kinetic transport models, computational methods, and higher dimensions. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.
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.
KINETIC THEORY OF PLASMAS: TRANSLATIONAL ENERGY
T. E. Magin; B. Graille; A N D M. Massot
2009-01-01
In the present contribution, we derive from kinetic theory a unified fluid\\u000amodel for multicomponent plasmas by accounting for the electromagnetic field\\u000ainfluence. We deal with a possible thermal nonequilibrium of the translational\\u000aenergy of the particles, neglecting their internal energy and the reactive\\u000acollisions. Given the strong disparity of mass between the electrons and heavy\\u000aparticles, such as molecules,
Crystallization kinetics of plasma sprayed basalt coatings
Gunhan Bayrak; Senol Yilmaz
2006-01-01
Crystallization kinetics concerning the conversion of a glass coating layer made from natural basalt volcanic rock to glass-ceramic have been investigated. The basalt-based coatings were deposited on AISI 1040 steel substrates pre-coated with Ni–5wt.% Al using atmospheric plasma spraying system. Glass coatings were heat treated at 800, 900 and 1000°C for 1–4h in order to obtain glass-ceramic coating layer. DSC
Kinetic simulations of turbulent fusion plasmas
Idomura, Y. [Japan Atomic Energy Agency, Higashi-Ueno 6-9-3, Taitou, Tokyo 110-0015 (Japan); Watanabe, T.-H.; Sugama, H. [National Institute for Fusion Science/Graduate University for Advanced Studies, Toki, Gifu 509-5292 (Japan)
2008-05-14
In this paper, advances in kinetic simulations of turbulent fusion plasmas are reviewed by focusing on physical and numerical models used in five dimensional (5D) gyrokinetic simulations. Theoretical frameworks of physical models from the 6D Vlasov equation to the 5D gyrokinetic equation are presented. Properties of numerical approaches, namely, particle and mesh approaches are described, and roles of numerical dissipation in collisionless turbulence simulations are discussed.
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.
A kinetic model of plasma turbulence
NASA Astrophysics Data System (ADS)
Servidio, S.; Valentini, F.; Perrone, D.; Greco, A.; Califano, F.; Matthaeus, W. H.; Veltri, P.
2015-01-01
A Hybrid Vlasov-Maxwell (HVM) model is presented and recent results about the link between kinetic effects and turbulence are reviewed. Using five-dimensional (2D in space and 3D in the velocity space) simulations of plasma turbulence, it is found that kinetic effects (or non-fluid effects) manifest through the deformation of the proton velocity distribution function (DF), with patterns of non-Maxwellian features being concentrated near regions of strong magnetic gradients. The direction of the proper temperature anisotropy, calculated in the main reference frame of the distribution itself, has a finite probability of being along or across the ambient magnetic field, in general agreement with the classical definition of anisotropy T ?/T ? (where subscripts refer to the magnetic field direction). Adopting the latter conventional definition, by varying the global plasma beta (?) and fluctuation level, simulations explore distinct regions of the space given by T ?/T ? and ??, recovering solar wind observations. Moreover, as in the solar wind, HVM simulations suggest that proton anisotropy is not only associated with magnetic intermittent events, but also with gradient-type structures in the flow and in the density. The role of alpha particles is reviewed using multi-ion kinetic simulations, revealing a similarity between proton and helium non-Maxwellian effects. The techniques presented here are applied to 1D spacecraft-like analysis, establishing a link between non-fluid phenomena and solar wind magnetic discontinuities. Finally, the dimensionality of turbulence is investigated, for the first time, via 6D HVM simulations (3D in both spaces). These preliminary results provide support for several previously reported studies based on 2.5D simulations, confirming several basic conclusions. This connection between kinetic features and turbulence open a new path on the study of processes such as heating, particle acceleration, and temperature-anisotropy, commonly observed in space plasmas.
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.
BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas
NASA Astrophysics Data System (ADS)
Porkolab, Miklos
1998-11-01
The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this addition to the literature, for it gives the teacher of the subject a valuable reference where the inquisitive student will be able to read up on and satisfy himself about the practicality and reliability of the Vlasov theory in a hot magnetized and collisionless plasma. The book has excellent treatments of several new topics not included in previous textbooks, for example, the relativistic theory of plasma wave propagation, so important in electron cyclotron heating of magnetically confined fusion plasmas, a discussion of current drive theory and there is a welcome introduction to parametric instabilities in the final chapter. There are some things that make the readability of the book somewhat difficult. In the early parts, certain advanced concepts are introduced without much motivation or explanation, although the author is trying to be helpful by providing a list of relevant references at the end of each chapter. Here the teacher's role will be critical. Again, a certain amount of previous knowledge of the subject would prove to be invaluable to the student. The main content of the book is included in 11 chapters. Use is made of CGS Gaussian units, a favourite of plasma theorists. As the author states, these are still widely used in advanced plasma theory, and the student is well advised to become familiar with this system of units (as well as the SI system for applications). To help the reader in the Introduction, the author defines various expressions often used in plasma physics in practical units (frequencies in hertz, lengths in centimetres, temperatures in kiloelectronvolts and magnetic fields in teslas). Chapter 2 is entitled `Plasma Electrodynamics' and it introduces the Maxwell-Vlasov set of equations, as well as the important fundamentals of wave propagation, such as polarization, dispersion and the dielectric tensor, and energy relations. In Chapter 3, `Elementary Plasma Kinetic Theory', the author derives the Vlasov equation and the Fokker-Planck equation from the BBGKY hierarchy. This is a somewhat unusual chapter in a book on plasma waves, but I
Kinetic effects on particle and heat fluxes in detached plasmas
Batishchev, O.V. [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States); [Lodestar Research Corporation, Boulder, Colorado 80301 (United States); Xu, X.Q.; Byers, J.A.; Cohen, R.H. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States); Krasheninnikov, S.I. [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States); Rognlien, T.D. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States); Sigmar, D.J. [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States)] [Massachusetts Institute of Technology, Plasma Fusion Center, Cambridge, Massachusetts 02139 (United States)
1996-09-01
A model of high recycling scrape-off layer plasmas in tokamaks is presented where both ion and electron species are described by nonlinear kinetic equations. Coulomb and charged-neutral particle collisions are included. The ambipolar electric field and electrostatic sheath potential are evaluated self-consistently. Two models of fluid neutral transport are used to distinguish the neutral density variation for different tokamak divertor geometries. These models are incorporated into a comprehensive three-dimensional (1-D, 2 V) hybrid collisional particle-in-cell{endash}Monte Carlo code W1 [Contrib. Plasma Phys. {bold 34}, 436 (1994)]. This code is used to investigate the effects of neutrals on divertor plasma detachment phenomena and on parallel heat and particle fluxes in the presence of strong gradients where fluid descriptions break down. Results are given for simulations of detached and attached divertor plasmas, and comparisons are made with solutions from a one-dimensional fluid model and with experimental observations. {copyright} {ital 1996 American Institute of Physics.}
NASA Astrophysics Data System (ADS)
Gubchenko, V. M.; Biernat, H. K.; Rucker, H. O.
We consider in terms of the Vlasov Maxwell kinetic approach a classical problem of inductive generation by the solar wind flow of the 3D solar streamer tail structures originating by magnetic flux sources at the Sun magnetoactive regions The input flow is a hot collisionless plasma with maxwellian distribution function We separated magnetic field interacting particles on trapped and untrapped fly by particles Trapped particles partly are parameterized by magnetic flux source configuration The source is approximated by densities of magnetic dipole and magnetic toroid currents distributed on the characteristic scale and characterized by ratio of their integral currents Fly by particles motion we treat via perturbations resulting a linear analytical approach to the flowing plasma Plasma appeared as a result in the problem like resistive and diamagnetic media Non local resistive currents are characterized by anomalous skin scale and diamagnetic currents by magnetic Debye scale Ratio of the diamagnetic currents to the resistive currents is a Quality of the streamer magnetosphere We get integral representation of a selfconsistent global 3D magnetic configuration which is defined via two different kinds of cylindrical harmonics For maxwellian plasma we get a low Quality regime when 3D structure is with resistive currents and only parameter is a specific collisionless magnetic Reynolds number A dipole generates 3D two wire multi magnetic ropes current configuration cylindrical dipole harmonics which is observed in the far down tail
Kinetic theory of partially ionized complex (dusty) plasmas
Tsytovich, V.N.; De Angelis, U.; Ivlev, A.V.; Morfill, G.E. [General Physics Institute, Russian Academy of Sciences, 117942 Moscow (Russian Federation); Department of Physical Sciences, University of Naples 'Federico II', 80126 Naples (Italy); Max-Planck-Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany)
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.
Kinetic modeling of the Saturn ring-ionosphere plasma environment
G. R. Wilson; J. H. Waite 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
Fundamental statistical descriptions of plasma turbulence in magnetic fields
NASA Astrophysics Data System (ADS)
Krommes, John A.
2002-04-01
A pedagogical review of the historical development and current status (as of early 2000) of systematic statistical theories of plasma turbulence is undertaken. Emphasis is on conceptual foundations and methodology, not practical applications. Particular attention is paid to equations and formalism appropriate to strongly magnetized, fully ionized plasmas. Extensive reference to the literature on neutral-fluid turbulence is made, but the unique properties and problems of plasmas are emphasized throughout. Discussions are given of quasilinear theory, weak-turbulence theory, resonance-broadening theory, and the clump algorithm. The direct-interaction approximation (DIA) is developed as a central focus of the article, and its relationship to the earlier plasma theories is explained. Various methods of renormalized perturbation theory are described, then unified with the aid of the generating-functional formalism of Martin, Siggia, and Rose. A general expression for the renormalized dielectric function is deduced and discussed in detail. Modern approaches such as decimation and PDF methods are described. Derivations of DIA-based Markovian closures are discussed. The eddy-damped quasinormal Markovian (EDQNM) closure is shown to be nonrealizable in the presence of waves, and a new realizable Markovian closure is presented. The test-field model and a realizable modification thereof are also summarized. Numerical solutions of various closures for some plasma-physics paradigms are reviewed. The variational approach to bounds on transport is developed. Miscellaneous topics include Onsager symmetries for turbulence, the interpretation of entropy balances for both kinetic and fluid descriptions, self-organized criticality, statistical interactions between disparate scales, and the roles of both mean and random shear. Appendices are provided on Fourier transform conventions, dimensional and scaling analysis, the derivations of nonlinear gyrokinetic and gyrofluid equations, stochasticity criteria for quasilinear theory, formal aspects of resonance-broadening theory, Novikov's theorem, the treatment of weak inhomogeneity, the derivation of the Vlasov and gyrokinetic weak-turbulence wave kinetic equation from a fully renormalized description, some features of a code for solving the DIA and related Markovian closures, the details of the solution of the EDQNM closure for a solvable three-wave model, and the notation used in the article.
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.
Parametric instabilities of Alfven waves in a multispecies plasma: Kinetic effects
Kauffmann, K.; Araneda, J. A.
2008-06-15
Parametric instabilities of a circularly polarized Alfven wave in a multispecies magnetized plasma are considered. An analytic kinetic description and hybrid simulations for the linear behavior of the instabilities are given. It is found that, even for low-{beta} regimes, both the kinetic effects and the presence of heavy ions substantially modify the characteristics of parametric instabilities as compared to the fluid model. The decay instability can be severely quenched in a plasma composed of massless electrons, protons, and alpha particles when the alphas are slightly hotter than the protons. These results could be important in describing the heating processes of heavy ions in the solar corona.
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 [Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China); Max-Planck-Institute for Extraterrestrial Physics, 85748 Garching (Germany); Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China); Morfill, G. E. [Max-Planck-Institute for Extraterrestrial Physics, 85748 Garching (Germany)
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.
Towards adaptive kinetic-fluid simulations of weakly ionized plasmas
NASA Astrophysics Data System (ADS)
Kolobov, V. I.; Arslanbekov, R. R.
2012-02-01
This paper describes an Adaptive Mesh and Algorithm Refinement (AMAR) methodology for multi-scale simulations of gas flows and the challenges associated with extending this methodology for simulations of weakly ionized plasmas. The AMAR method combines Adaptive Mesh Refinement (AMR) with automatic selection of kinetic or continuum solvers in different parts of computational domains. We first review the discrete velocity method for solving Boltzmann and Wang Chang-Uhlenbeck kinetic equations for rarefied gases. Then, peculiarities of AMR implementation with octree Cartesian mesh are discussed. A Unified Flow Solver (UFS) uses AMAR method with adaptive Cartesian mesh to dynamically introduce kinetic patches for multi-scale simulations of gas flows. We describe fluid plasma models with AMR capabilities and illustrate how physical models affect simulation results for gas discharges, especially in the areas where electron kinetics plays an important role. We introduce Eulerian solvers for plasma kinetic equations and illustrate the concept of adaptive mesh in velocity space. Specifics of electron kinetics in collisional plasmas are described focusing on deterministic methods of solving kinetic equations for electrons under different conditions. We illustrate the appearance of distinct groups of electrons in the cathode region of DC discharges and discuss the physical models appropriate for each group. These kinetic models are currently being incorporated into AMAR methodology for multi-scale plasma simulations.
Phys 783 Plasma Kinetic Theory CLASS DETAILS
Cassak, Paul
PHYS 481 (Intro Plasma) & PHYS 631 (Graduate Classical Mechanics) & PHYS 634 (Graduate Electricity AT http://farside.ph.utexas.edu/teaching/plasma/plasma.html** · There are a lot of older books that cover
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...
Solitary kinetic Alfven waves in a plasma with negative ions
NASA Astrophysics Data System (ADS)
Sahoo, H.; Mondal, K. K.; Ghosh, B.
2015-05-01
By using the Sagdeev pseudo-potential approach, the solitary kinetic Alfven waves have been theoretically investigated in a collisionless magnetized plasma in presence of negative ions. Sagdeev potential is plotted for different plasma parameters and it is shown that both hump and dip solitons may exist for kinetic Alfven waves which support the data received from space satellites. The negative ions are shown to have significant effects on the conditions for existence and properties of these solitons.
Kinetic signatures and intermittent turbulence in the solar wind plasma.
Osman, K T; Matthaeus, W H; Hnat, B; Chapman, S C
2012-06-29
A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 A.U. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are nonuniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures. PMID:23004954
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.
Detailed and reduced chemical-kinetic descriptions for hydrocarbon combustion
NASA Astrophysics Data System (ADS)
Petrova, Maria V.
Numerical and theoretical studies of autoignition processes of fuels such as propane are in need of realistic simplified chemical-kinetic descriptions that retain the essential features of the detailed descriptions. These descriptions should be computationally feasible and cost-effective. Such descriptions are useful for investigating ignition processes that occur, for example, in homogeneous-charge compression-ignition engines, for studying the structures and dynamics of detonations and in fields such as multi-dimensional Computational Fluid Dynamics (CFD). Reduced chemistry has previously been developed successfully for a number of other hydrocarbon fuels, however, propane has not been considered in this manner. This work focuses on the fuels of propane, as well propene, allene and propyne, for several reasons. The ignition properties of propane resemble those of other higher hydrocarbons but are different from those of the lower hydrocarbons (e.g. ethylene and acetylene). Propane, therefore, may be the smallest hydrocarbon that is representative of higher hydrocarbons in ignition and detonation processes. Since the overall activation energy and ignition times for propane are similar to those of other higher hydrocarbons, including liquid fuels that are suitable for many applications, propane has been used as a model fuel for several numerical and experimental studies. The reason for studying elementary chemistry of propene and C3H4 (allene or propyne) is that during the combustion process, propane breaks down to propene and C3H4 before proceeding to products. Similarly, propene combustion includes C3H4 chemistry. In studying propane combustion, it is therefore necessary to understand the underlying combustion chemistry of propene as well as C3H 4. The first part of this thesis focuses on obtaining and testing a detailed chemical-kinetic description for autoignition of propane, propene and C 3H4, by comparing predictions obtained with this detailed mechanism against numerous experimental data available from shock-tube studies and flame-speed measurements. To keep the detailed mechanism small, attention is restricted to pressures below about 100 atm, temperatures above about 1000 K and equivalence ratios less than about 3. Based on this detailed chemistry description, short (or skeletal) mechanisms are then obtained for each of the three fuels by eliminating reactions that are unimportant for the autoignition process under conditions presented above. This was achieved by utilizing tools such as sensitivity and reaction pathway analyses. Two distinct methodologies were then used in order to obtain a reduced mechanism for autoignition from the short mechanisms. A Systematic Reduction approach is first taken that involves introducing steady-state approximations to as many species as analytically possible. To avoid resorting to numerical methods, the analysis for obtaining ignition times for heptane, presented by Peters and co-workers is followed in order to obtain a rough estimate for an expression of propane ignition time. The results from this expression are then compared to the ignition times obtained computationally with the detailed mechanism. The second method is an Empirical Approach in which chemistry is not derived formally, but rather postulated empirically on the basis of experimental, computational and theoretical observations. As a result, generalized reduced mechanisms are proposed for autoignition of propane, propene and C3H 4. Expressions for ignition times obtained via this empirical approach are compared to the computational results obtained from the detailed mechanism.
A kinetic description of electron beam ejection from spacecraft
NASA Astrophysics Data System (ADS)
Khazanov, George V.; Neubert, Torsten; Gefan, Grigorii D.; Trukhan, Aleksander A.; Mishin, Evgeni V.
1993-09-01
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.
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.
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.
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.
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.
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.
Global limits on kinetic Alfvenon speed in quasineutral plasmas
Akbari-Moghanjoughi, M.
2011-04-15
Large-amplitude kinetic Alfvenon (exact Alfven soliton) matching condition is investigated in quasineutral electron-ion and electron-positron-ion plasmas immersed in a uniform magnetic field. Using the standard pseudopotential method, the magnetohydrodynamics equations are exactly solved, and a global allowed matching condition for propagation of kinetic solitary waves is derived. It is remarked that, depending on the plasma parameters, the kinetic solitons can be sub-Alfvenic or super-Alfvenic, in general. It is further revealed that, either upper or lower soliton speed-limit is independent of fractional plasma parameters. Furthermore, the soliton propagation angle with respect to that of the uniform magnetic field is found to play a fundamental role in controlling the soliton matching speed-range.
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.
Gas Kinetic Study of Magnetic Field Effects on Plasma Plumes
Ebersohn, Frans 1987-
2012-12-07
continuum-based description and computation valid; ii) in the context of MHD framework, the generalized Ohm’s law must be used to capture all of the relevant physics. This work also continues the development of the Magneto Gas Kinetic Method (MGKM...
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.
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.
Structural and reactive kinetics in gas-liquid interfacial plasmas
NASA Astrophysics Data System (ADS)
Kaneko, T.; Chen, Q.; Harada, T.; Hatakeyama, R.
2011-06-01
Basic physical and chemical processes in novel gas-liquid interfacial plasmas applicable to nano-bio conjugates creation are investigated, where the boundary between ionic liquids (ILs) and gas phase discharge plasmas plays a key role. First the electrostatic potential is found to be formed at the plasma-liquid interface, and the precise potential and density structures are clearly measured. Then gas-liquid discharge kinetics, namely the dynamic behaviors of ions and electrons, are clarified in gas pressures ranging from atmospheric to low pressures owing to the unique properties of the ILs. Finally kinetics of interface reactions such as IL dissociation promoted by the plasma irradiation through the electric field just above the IL are explored, which enables us to create innovative conjugates of carbon nanotubes and nanoparticles.
Comet giacobini-zinner: plasma description.
Bame, S J; Anderson, R C; Asbridge, J R; Baker, D N; Feldman, W C; Fuselier, S A; Gosling, J T; McComas, D J; Thomsen, M F; Young, D T; Zwickl, R D
1986-04-18
A strong interaction between the solar wind and comet Giacobini-Zinner was observed oh 11 September 1985 with the Los Alamos plasma electron experiment on the International Cometary Explorer (ICE) spacecraft. As ICE approached an intercept point 7800 kilometers behind the nucleus from the south and receded to the north, upstream phenomena due to the comet were observed. Periods of enhanced electron heat flux from the comet as well as almost continuous electron density fluctuations were measured. These effects are related to the strong electron heating observed in the cometary interaction region and to cometary ion pickup by the solar wind, respectively. No evidence for a conventional bow shock was found as ICE entered and exited the regions of strongest interaction of the solar wind with the cometary environment. The outer extent of this strong interaction zone was a transition region in which the solar wind plasma was heated, compressed, and slowed. Inside the inner boundary of the transition region was a sheath that enclosed a cold intermediate coma. In the transition region and sheath, small-scale enhancements in density were observed. These density spikes may be due to an instability associated with cometary ion pickup or to the passage of ICE through cometary ray structures. In the center of the cold intermediate coma a narrow, high-density core of plasma, presumably the developing plasma tail was found. In some ways this tail can be compared to the plasma sheet in Earth's magnetotail and to the current sheet in the tail at Venus. This type of configuration is expected in the double-lobe magnetic topology detected at the comet, possibly caused by the theoretically expected draping of the interplanetary magnetic field around its ionosphere. PMID:17792144
Kinetic axisymmetric gravitational equilibria in collisionless accretion disk plasmas
Cremaschini, Claudio; Miller, John C.; Tessarotto, Massimo
2010-07-15
A theoretical treatment is presented of kinetic equilibria in accretion disks (AD) around compact objects, for cases where the plasma can be considered as collisionless. The plasma is assumed to be axisymmetric and to be acted on by gravitational and electromagnetic fields; in this paper, the particular case is considered where the magnetic field admits a family of toroidal magnetic surfaces, which are locally mutually nested and closed. It is pointed out that there exist asymptotic kinetic equilibria represented by generalized bi-Maxwellian distribution functions and characterized by primarily toroidal differential rotation and temperature anisotropy. It is conjectured that kinetic equilibria of this type can exist which are able to sustain both toroidal and poloidal electric current densities, the latter being produced via finite Larmor-radius effects associated with the temperature anisotropy. This leads to the possibility of existence of a new kinetic effect - referred to here as a 'kinetic dynamo effect - resulting in the self-generation of toroidal magnetic field even by a stationary plasma, without any net radial accretion flow being required. The conditions for these equilibria to occur, their basic theoretical features, and their physical properties are all discussed in detail.
Fluid and kinetic plasma modeling of redeposition regimes
NASA Astrophysics Data System (ADS)
Canik, J. M.; Tang, X.
2013-10-01
Strong redeposition of eroded material from plasma-facing components (PFC) is required in a fusion reactor to ensure long PFC lifetimes. Reaching redeposition regimes depends on the plasma conditions near the PFC surface, as well as the surface material itself. Here we present plasma modeling of experiments performed at the PISCES device studying the erosion properties of Be surfaces that have been produced via seeding to simulate the redeposition process. Initial modeling has utilized the SOLPS code, which treats the plasma as a fluid, and can simulate the long-range transport of eroded impurities. To treat the effect of the magnetic sheath near the surface, which can dominate the prompt redeposition characteristics of heavy PFC materials including W, requires a kinetic plasma simulation, and is being addressed using the VPIC code. Results from the fluid plasma modeling will be presented, and the coupling of the VPIC and SOLPS codes will be discussed. Strong redeposition of eroded material from plasma-facing components (PFC) is required in a fusion reactor to ensure long PFC lifetimes. Reaching redeposition regimes depends on the plasma conditions near the PFC surface, as well as the surface material itself. Here we present plasma modeling of experiments performed at the PISCES device studying the erosion properties of Be surfaces that have been produced via seeding to simulate the redeposition process. Initial modeling has utilized the SOLPS code, which treats the plasma as a fluid, and can simulate the long-range transport of eroded impurities. To treat the effect of the magnetic sheath near the surface, which can dominate the prompt redeposition characteristics of heavy PFC materials including W, requires a kinetic plasma simulation, and is being addressed using the VPIC code. Results from the fluid plasma modeling will be presented, and the coupling of the VPIC and SOLPS codes will be discussed. Work supported by U.S. DOE Contract #DE-AC05-00OR22725
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.
Emergence of kinetic behavior in streaming ultracold neutral plasmas
NASA Astrophysics Data System (ADS)
McQuillen, P.; Castro, J.; Bradshaw, S. J.; Killian, T. C.
2015-04-01
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.
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.
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.
Complexity reduction of collisional-radiative kinetics for atomic plasma
Le, Hai P. [ERC Inc., Edwards AFB, California 93524 (United States)] [ERC Inc., Edwards AFB, California 93524 (United States); Karagozian, Ann R. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States)] [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States); Cambier, Jean-Luc [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)] [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)
2013-12-15
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.
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.
Yeung, Man-Chung
KINETICS, CATALYSIS, AND REACTION ENGINEERING Nonthermal Plasma Reactions of Dilute Nitrogen Oxide technical potential, the nonthermal plasma reactions and their kinetics are poorly understood the rate of the electron collision reactions, which de- pends on the electron energy distribution.4
Decay of a magnetic-field-aligned Alfven wave into inertial and kinetic Alfven waves in plasmas
Shukla, P.K.; Stenflo, L.
2005-08-15
A simple description of three-wave decay interactions involving a magnetic-field-aligned dispersive Alfven wave (DAW) pump and two dispersive (either inertial or kinetic) Alfven waves that are propagating obliquely to the external magnetic-field direction in a uniform plasma is presented. The nonlinear dispersion relations and growth rates are obtained. The present results are useful for understanding the origin of constant-amplitude pump-driven nonthermal DAWs in ionospheric, magnetospheric, and heliospheric plasmas.
Plasma kinetic processes in a strong d.c. magnetic field
NASA Technical Reports Server (NTRS)
Montgomery, D.
1976-01-01
Recent results in the kinetic theory of a strongly magnetized plasma are surveyed. Emphasis is on the electrostatic guiding-center plasma in two dimensions, in both the fluid and 'charged rod' descriptions. The basic kinetic description of the plasma is in terms of the statistically-distributed Fourier coefficients associated with the velocity and 'enstrophy' (charge density) fields. It is a universal tendency in such media for enstrophy to flow to shorter wavelengths but for energy to flow to longer wavelengths. A consequence of the energy flow to longer wavelengths is the generation of long-range order in the form of macroscopic vortices. These kinds of structure have been called 'convection cells' and can be extraordinarily efficient in transporting particles transverse to a magnetic field. The tendency to vortex formation can be disrupted by collisions between particles. Modifications of the Fokker-Planck equation for a plasma produced by a strong dc magnetic field are considered in both two and three dimensions.
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.
Nonlinear gyrofluid description of turbulent magnetized plasmas
NASA Astrophysics Data System (ADS)
Brizard, Alain
1992-05-01
Nonlinear gyrofluid equations are obtained from the gyrocenter-fluid moments of the nonlinear gyrokinetic Vlasov equation, which describes an equilibrium magnetized nonuniform plasma perturbed by electromagnetic field fluctuations (??,?A?,?B?), whose space-time scales satisfy the gyrokinetic ordering: ???i, ?k??/k??1, and ???(k??i)2?O(1). These low-frequency (reduced) fluid equations contain terms of arbitrary order in ?? 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(??), by expressing the gyrocenter-fluid moments appearing in the gyrofluid equations in terms of the particle-fluid moments, and then keeping terms up to O(??) in the ?? 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).
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.
Kinetic two-dimensional modeling of inductively coupled plasmas based on a hybrid kinetic approach
Kortshagen, U.; Heil, B.G.
1999-10-01
In recent years the design cycle for semiconductor manufacturing equipment has shortened to about 18 months. The ever shorter period of development and the need for cost-effective design of new plasma processing tools has created demand for efficient, engineering-type plasma modeling. In this paper, the authors present a two-dimensional (2-D) kinetic model for low-pressure inductively coupled discharges. The kinetic treatment of the plasma electrons is based on a hybrid kinetic scheme in which the range of electron energies is divided into two subdomains. In the low energy range the electron distribution function is determined from the traditional nonlocal approximation. In the high energy part the complete spatially dependent Boltzmann equation is solved. The scheme provides computational efficiency and enables inclusion of electron-electron collisions which are important in low-pressure high-density plasmas. The self-consistent scheme is complemented by a 2-D fluid model for the ions and the solution of the complex wave equation for the RF electric field. Results of this model are compared to experimental results. Good agreement in terms of plasma density and potential profiles is observed. In particular, the model is capable of reproducing the transition from on-axis to off-axis peaked density profiles as observed in experiments which underlines the significant improvements compared to models purely based on the traditional nonlocal approximation.
Pedestal fueling simulations with a coupled kinetic plasma-kinetic neutral transport code
NASA Astrophysics Data System (ADS)
Stotler, D. P.; Chang, C. S.; Ku, S. H.; Lang, J.; Park, G. Y.
2013-07-01
The simplified neutral transport routine in the guiding center ion-electron-neutral neoclassical PIC code XGC0 has been replaced by one that calls the Monte Carlo neutral transport code DEGAS2. This provides a more realistic treatment of neutral atoms in the tokamak edge plasma and allows detailed atomic physics and plasma-material interaction processes to be incorporated into the simulations. The spatial profile of the neutral particle source used in DEGAS2 is determined from the fluxes of XGC0 ions to the material surfaces, and DEGAS2 is run in a time dependent manner synchronized with XGC0. The kinetic plasma-kinetic neutral transport capability is demonstrated with example pedestal fueling simulations.
Hamiltonian field description of two-dimensional vortex fluids and guiding center plasmas
Morrison, P.J.
1981-03-01
The equations that describe the motion of two-dimensional vortex fluids and guiding center plasmas are shown to possess underlying field Hamiltonian structure. A Poisson bracket which is given in terms of the vorticity, the physical although noncanonical dynamical variable, casts these equations into Heisenberg form. The Hamiltonian density is the kinetic energy density of the fluid. The well-known conserved quantities are seen to be in involution with respect to this Poisson bracket. Expanding the vorticity in terms of a Fourier-Dirac series transforms the field description given here into the usual canonical equations for discrete vortex motion. A Clebsch potential representation of the vorticity transforms the noncanonical field description into a canonical description.
On bias of kinetic temperature measurements in complex plasmas
Kantor, M. [Association Euratom-Max-Planck-Institut für Plasmaphysik, D-85748 Garching bei München (Germany) [Association Euratom-Max-Planck-Institut für Plasmaphysik, D-85748 Garching bei München (Germany); Association Euratom-FOM Institute DIFFER, 3430 BE Nieuwegein (Netherlands); Ioffe Institute, RAS, St. Petersburg 194021 (Russian Federation); Moseev, D., E-mail: dmitry.moseev@ipp.mpg.de [Association Euratom-Max-Planck-Institut für Plasmaphysik, D-85748 Garching bei München (Germany); Association Euratom-FOM Institute DIFFER, 3430 BE Nieuwegein (Netherlands); Salewski, M. [Association Euratom-DTU, Department of Physics, Technical University of Denmark, DTU Ris o Campus, DK-4000 Roskilde (Denmark)] [Association Euratom-DTU, Department of Physics, Technical University of Denmark, DTU Ris o Campus, DK-4000 Roskilde (Denmark)
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 theory of Jeans instability of a dusty plasma.
Pandey, B P; Lakhina, G S; Krishan, V
1999-12-01
A kinetic theory of the Jeans instability of a dusty plasma has been developed in the present work. The effect of grain charge fluctuations due to the attachment of electrons and ions to the grain surface has been considered in the framework of Krook's collisional model. We demonstrate that the grain charge fluctuations alter the growth rate of the gravitational collapse of the dusty plasma. The Jeans length has been derived under limiting cases, and its dependence on the attachment frequency is shown. In the absence of gravity, we see that the damping rate of the dust acoustic mode is proportional to the electron-dust collision frequency. PMID:11970688
Kinetic Alfvén solitary and rogue waves in superthermal plasmas
Bains, A. S.; Li, Bo, E-mail: bbl@sdu.edu.cn; Xia, Li-Dong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai (China)] [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai (China)
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.
Kinetic modeling of a two-dimensional, collisionless bounded plasma
H. Pedit; S. Kuhn
1994-01-01
A (2d,3v), electrostatic, collisionless kinetic slab model for a wide class of negative-bias dc states of the single-ended Q machine is developed. The self-consistent plasma state is found by means of an iterative scheme in which the charge-density and potential distributions are alternately advanced. The electron and ion velocity distribution functions are calculated via trajectory integration, which ensures high accuracy
Analysis of plasma antioxidant capacity by competition kinetics.
Tubaro, F; Ghiselli, A; Rapuzzi, P; Maiorino, M; Ursini, F
1998-05-01
A competition kinetics procedure for measuring plasma antioxidant capacity is described. This procedure is based on the "crocin bleaching test" (Bors, W., et al. Biochim. Biophys. Acta 796:312-319; 1984) modified for analyzing the antioxidant capacity of complex mixtures (Tubaro, F., et al. J. Am. Oil Chem. Soc. 73:173-179; 1996). The information produced by this test is similar to that of the popular "total radical trapping antioxidant potential" (TRAP) analysis. However, the adopted kinetic approach is, in principle, more precise, taking into account both the concentration of antioxidants and their rate constant for the reaction with peroxy radical, which is overlooked in TRAP tests, as implied by the theory of the approach and confirmed by dynamic modeling. The kinetic analysis has also the advantage of accounting for the average between antioxidant effect (reduction of peroxy radicals) and possible prooxidant effect (oxidation by the radical of the antioxidant of the target supposed to be protected) if any. Thus, the result of this analysis provides a more precise evaluation of the efficiency of antioxidant defense. The intraassay variation resulted in less than 8% and, in young healthy subjects, the plasma antioxidant capacity, expressed as mM equivalents of a reference antioxidant (Trolox C), gave 1.59 +/- 0.28. The validated procedure has been used to show that plasma antioxidant capacity is deeply influenced by the consumption of wine. PMID:9626578
Weakly Ionized Plasmas in Hypersonics: Fundamental Kinetics and Flight Applications
Macheret, Sergey [Department of Mechanical and Aerospace Engineering, Princeton University, D-418 Engineering Quadrangle, Princeton, NJ 08544 (United States)
2005-05-16
The paper reviews some of the recent studies of applications of weakly ionized plasmas to supersonic/hypersonic flight. Plasmas can be used simply as means of delivering energy (heating) to the flow, and also for electromagnetic flow control and magnetohydrodynamic (MHD) power generation. Plasma and MHD control can be especially effective in transient off-design flight regimes. In cold air flow, nonequilibrium plasmas must be created, and the ionization power budget determines design, performance envelope, and the very practicality of plasma/MHD devices. The minimum power budget is provided by electron beams and repetitive high-voltage nanosecond pulses, and the paper describes theoretical and computational modeling of plasmas created by the beams and repetitive pulses. The models include coupled equations for non-local and unsteady electron energy distribution function (modeled in forward-back approximation), plasma kinetics, and electric field. Recent experimental studies at Princeton University have successfully demonstrated stable diffuse plasmas sustained by repetitive nanosecond pulses in supersonic air flow, and for the first time have demonstrated the existence of MHD effects in such plasmas. Cold-air hypersonic MHD devices are shown to permit optimization of scramjet inlets at Mach numbers higher than the design value, while operating in self-powered regime. Plasma energy addition upstream of the inlet throat can increase the thrust by capturing more air (Virtual Cowl), or it can reduce the flow Mach number and thus eliminate the need for an isolator duct. In the latter two cases, the power that needs to be supplied to the plasma would be generated by an MHD generator downstream of the combustor, thus forming the 'reverse energy bypass' scheme. MHD power generation on board reentry vehicles is also discussed.
Plasma transport induced by kinetic Alfven wave turbulence
Izutsu, T. [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Hasegawa, H.; Fujimoto, M. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Nakamura, T. K. M. [X-Computational Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2012-10-15
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.
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 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.
Plasma kinetics issues in an ESA study for a plasma laboratory in space
NASA Astrophysics Data System (ADS)
Annaratone, B. M.; Biancalani, A.; Bruno, D.; Capitelli, M.; Ceccherini, F.; Daly, E.; de Pascale, O.; Diomede, P.; D'Ammando, G.; Hilgers, A.; Longo, S.; Marcuccio, S.; Mendonca, J. T.; Nagnibeda, V.; Pegoraro, F.; Sanmartin, J. R.
2008-07-01
A study supported by the European Space Agency (ESA), in the context of its General Studies Programme, performed an investigation of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by 'space plasma physics'. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on a spatial scale (101-104 m) intermediate between what is achievable on the ground and the usual solar system plasma observations. Detailed feasibility studies have been performed for three experiments: active magnetic experiments, large-scale discharges and long tether-plasma interactions. The perspectives opened by these experiments are discussed for magnetic reconnection, instabilities, MHD turbulence, atomic excited states kinetics, weakly ionized plasmas, plasma diagnostics, artificial auroras and atmospheric studies. The discussion is also supported by results of numerical simulations and estimates.
Linear gyrokinetic theory for kinetic magnetohydrodynamic eigenmodes in tokamak plasmas
Qin, H.; Tang, W.M.; Rewoldt, G. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)
1999-06-01
A two-dimensional (2D) numerical solution method is developed for the recently derived linear gyrokinetic system which describes arbitrary wavelength electromagnetic perturbations in tokamak plasmas. The system consists of the gyrokinetic equation, the gyrokinetic Poisson equation, and the gyrokinetic moment equation. Since familiar magnetohydrodynamic (MHD) results can be recovered entirely from this gyrokinetic model, and all interesting kinetic effects are intrinsically included, this gyrokinetic system offers an approach for kinetic MHD phenomena which is more rigorous, self-consistent, and comprehensive than the previous hybrid models. Meanwhile, drift type microinstabilities can be also investigated systematically in this theoretical framework. The linear gyrokinetic equation is solved for the distribution function in terms of the perturbed fields by integrating along unperturbed particle orbits. The solution is substituted back into the gyrokinetic moment equation and the gyrokinetic Poisson equation. When the boundary conditions are incorporated, an eigenvalue problem is formed. The resulting numerical code, KIN-2DEM, is applied to kinetic ballooning modes, internal kink modes, and toroidal Alfv{acute e}n eigenmodes (TAEs). The numerical results are benchmarked against the well-established FULL code [G. Rewoldt, W. M. Tang, and M. S. Chance, Phys. Fluids {bold 25}, 480 (1982)], the PEST code [J. Manickam, Nucl. Fusion {bold 24}, 595 (1984)], and the NOVA-K code [C. Z. Cheng, Phys. Rep. {bold 211}, No. 1 (1992)]. More importantly, kinetic effects on MHD modes can be investigated nonperturbatively. In particular, the kinetic effects of the background plasma on internal kink modes and the hot particle destabilization of TAEs are studied numerically. {copyright} {ital 1999 American Institute of Physics.}
Active plasma resonance spectroscopy: A functional analytic description
Lapke, Martin; Mussenbrock, Thomas; Brinkmann, Ralf Peter
2012-01-01
The term "Active Plasma Resonance Spectroscopy" refers to a class of diagnostic methods which employ the ability of plasmas to resonate on or near the plasma frequency. The basic idea dates back to the early days of discharge physics: An signal in the GHz range is coupled to the plasma via an electrical probe; the spectral response is recorded, and then evaluated with a mathematical model to obtain information on the electron density and other plasma parameters. In recent years, the concept has found renewed interest as a basis of industry compatible plasma diagnostics. This paper analyzes the diagnostics technique in terms of a general description based on functional analytic (or Hilbert Space) methods which hold for arbitrary probe geometries. It is shown that the response function of the plasma-probe system can be expressed as a matrix element of the resolvent of an appropriately defined dynamical operator. A specialization of the formalism for a symmetric probe desing is given, as well as an interpreation...
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.
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.
Kinetic phenomena in charged particle transport in gases and plasmas
Petrovic, Zoran Lj.; Dujko, Sasa; Sasic, Olivera; Stojanovic, Vladimir; Malovic, Gordana [Institute of Physics, University of Belgrade, POB 68 11080 Zemun (Serbia); Faculty of Traffic Engineering, University of Belgrade Belgrade (Serbia); Institute of Physics, University of Belgrade, POB 68 11080 Zemun (Serbia)
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.
Intermittent Dissipation and Heating in 3D Kinetic Plasma Turbulence W. H. Matthaeus,1
Shay, Michael
of reduced dimensionality models, reduced physics models, or very small kinetic scale systems [4; published 30 April 2015) High resolution, fully kinetic, three dimensional (3D) simulation of collisionless such a complete 3D kinetic model. An important feature of plasma turbulence found in some reduced kinetic
Dynamic processes and kinetic theory of plasma fluctuations: ARCS3
Tang, K.
1988-01-01
Dynamic processes on the ARCS3 fight involve six related coordinate systems: Rocket System, Local Geographic System, Local Geomagnetic System, Global Geographic System, Wave Vector System and Artificial Argon Beam System. The present thesis has found the relationships needed to carry out coordinate transformations between all these six coordinate systems. These coordinate transformations are used to investigate ion trajectories and the directional response of the detector OCTO4. A technique to calculate the 3-component acceleration of the main payload was completed, and the trajectory of the main payload relative to the sub payload was given. A method to use the measured spin plane component of the electric field vector to construct the full 3 dimensional electric field vector in the Local Geomagnetic System has been provided. A model to simulate the artificial argon beam distribution is proposed, and used to calculate the beam's flux, density and evolution. Several kinds of plasma waves were observed by the University of Minnesota ACE detector. To explain the wave observations, a kinetic theory of plasma fluctuations was developed. This theory includes magnetized plasma species with or without parallel streaming. It is also valid for plasma including an unmagnetized two temperature plasma species that is streaming in any direction. As an application of the theory, the thermal fluctuations of the O{sup +} acoustic wave mode was calculated and compared with observations. The O{sup +} - He{sup +} bihybrid mode is also evaluated and compared with the observed wave spectra.
Quantitative description of realistic wealth distributions by kinetic trading models
NASA Astrophysics Data System (ADS)
Lammoglia, Nelson; Muñoz, Víctor; Rogan, José; Toledo, Benjamín; Zarama, Roberto; Valdivia, Juan Alejandro
2008-10-01
Data on wealth distributions in trading markets show a power law behavior x-(1+?) at the high end, where, in general, ? is greater than 1 (Pareto’s law). Models based on kinetic theory, where a set of interacting agents trade money, yield power law tails if agents are assigned a saving propensity. In this paper we are solving the inverse problem, that is, in finding the saving propensity distribution which yields a given wealth distribution for all wealth ranges. This is done explicitly for two recently published and comprehensive wealth datasets.
Application of Nonlocal Electron Kinetics to Plasma Technologies
NASA Astrophysics Data System (ADS)
Kaganovich, Igor D.
2011-10-01
Partially ionized plasmas are typically in a highly non-equilibrium thermodynamic state: the electrons are not in equilibrium with the neutral particle species or the ions, and the electrons are also not in equilibrium within their own ensemble, which results in a significant departure of the electron velocity distribution function (EVDF) from a Maxwellian. These non-equilibrium conditions provide considerable freedom to choose optimal plasma parameters for applications, which make gas-discharge plasmas remarkable tools for a variety of plasma applications, including plasma processing, discharge lighting, plasma propulsion, particle beam sources, and nanotechnology. Significant progress in understanding the formation of non-Maxwellian EVDF in the self-consistent electric fields has been one of the major achievements in the low-temperature plasmas during the last decade. This progress was made possible by a synergy between full-scale particle-in-cell simulations, analytical models, and experiments. Specific examples include rf discharges, dc discharges with auxiliary electrodes, Hall thruster discharges. In each example, nonlocal kinetic effects are identified as the main mechanisms responsible for the surprising degree of discharge self-organization. These phenomena include: explosive generation of cold electrons with rf power increase in low-pressure rf discharges; abrupt changes in discharge structure with increased bias voltage on a third electrode in a dc discharge with hot cathode; absence of a steady-state regime in Hall thruster discharges with intense secondary electron emission due to coupling of the sheath properties and the EVDF. In collaboration with Y. Raitses, A.V. Khrabrov, M. Campanell, V. I. Demidov, D. Sydorenko, I. Schweigert, and A. S. Mustafaev. Research supported by the U.S. Department of Energy.
NASA Technical Reports Server (NTRS)
Tanaka, Motohiko; Sato, Tetsuya; Hasegawa, A.
1989-01-01
The excitation of the kinetic Alfven wave by resonant mode conversion and longitudinal heating of the plasma by the kinetic Alfven wave were demonstrated on the basis of a macroscale particle simulation. The longitudinal electron current was shown to be cancelled by the ions. The kinetic Alfven wave produced an ordered motion of the plasma particles in the wave propagation direction. The electrons were pushed forward along the ambient magnetic field by absorbing the kinetic Alfven wave through the Landau resonance.
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.
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.
NASA Astrophysics Data System (ADS)
Howes, Gregory G.
The weak collisionality typical of turbulence in many diffuse astrophysical plasmas invalidates an MHD description of the turbulent dynamics, motivating the development of a more comprehensive theory of kinetic turbulence. In particular, a kinetic approach is essential for the investigation of the physical mechanisms responsible for the dissipation of astrophysical turbulence and the resulting heating of the plasma. This chapter reviews the limitations of MHD turbulence theory and explains how kinetic considerations may be incorporated to obtain a kinetic theory for astrophysical plasma turbulence. Key questions about the nature of kinetic turbulence that drive current research efforts are identified. A comprehensive model of the kinetic turbulent cascade is presented, with a detailed discussion of each component of the model and a review of supporting and conflicting theoretical, numerical, and observational evidence.
Howes, Gregory G
2015-01-01
The weak collisionality typical of turbulence in many diffuse astrophysical plasmas invalidates an MHD description of the turbulent dynamics, motivating the development of a more comprehensive theory of kinetic turbulence. In particular, a kinetic approach is essential for the investigation of the physical mechanisms responsible for the dissipation of astrophysical turbulence and the resulting heating of the plasma. This chapter reviews the limitations of MHD turbulence theory and explains how kinetic considerations may be incorporated to obtain a kinetic theory for astrophysical plasma turbulence. Key questions about the nature of kinetic turbulence that drive current research efforts are identified. A comprehensive model of the kinetic turbulent cascade is presented, with a detailed discussion of each component of the model and a review of supporting and conflicting theoretical, numerical, and observational evidence.
a Self-Consistent Kinetic Theory of DC and RF Glow Discharge Plasmas.
NASA Astrophysics Data System (ADS)
Sommerer, Timothy John
1990-01-01
A widely-applicable numerical algorithm based on propagators or Green's functions has been developed and used to describe various discharge plasmas, with helium being the gas used as an example throughout. The charged particle dynamics are calculated at the kinetic level and in a manner that is mutually consistent with the electric fields present. The accuracy of the results is therefore dependent upon only the quality of basic input data (cross sections, discharge operating point) and is not hindered by the ad hoc assumptions required to mathematically close models that are not kinetic or not self-consistent. The kinetic electron portion of the calculation is first benchmarked by imposing a field configuration and comparing with experiment and Monte Carlo simulation. Both swarm (uniform field) and cathode fall (linearly-varying field) cases are examined. A kinetic model of electron behavior is then combined with a mobility description of helium ions to yield a self-consistent calculation of the cathode fall of a dc helium glow discharge. The results are shown to be in excellent agreement with non-invasive spectroscopic measurements of the electric field in such a discharge. Helium rf glow discharges are then studied. The mobility description of the ions used previously is replaced with a kinetic model. The result is a fully-kinetic calculation of all charged species throughout the discharge that is mutually-consistent with the fields present. The numerical requirements for this calculation are much more stringent than for those preceding; improvements to the method are detailed, including a scheme for advancing the calculation on the ion collision time. Electrons in the low-field, high-density central bulk region of the rf discharges studied are found to have very low average energies, and the electric field in the region is largely out of phase with the strong sheath fields near the electrodes. The predicted average energies are lower by an order of magnitude than those obtained with calculations that are not both self-consistent and kinetic, but are in much better agreement with the relatively sparse experimental data.
Kjelstrup, Signe
role in the cell for information transfer, regulation, and catalysis. The RNA molecule is relativelyUnifying Thermodynamic and Kinetic Descriptions of Single-Molecule Processes: RNA Unfolding under; In Final Form: June 15, 2007 We use mesoscopic nonequilibrium thermodynamics theory to describe RNA
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.
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 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.
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. 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.
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
The kinetic plasma physics of solar wind turbulence
NASA Astrophysics Data System (ADS)
Klein, Kristopher Gregory
As means of investigating the various mechanisms which contribute to the persistence of magnetized turbulence in the solar wind, this dissertation details the development of tools through which turbulence theories can be directly compared to in situ observations. This comparison is achieved though the construction of synthetic spacecraft time series from spectra of randomly phased linear eigenmodes. A broad overview of the current understanding of plasma turbulence through analytic theory, spacecraft observation, and numerical simulation is presented with particular emphasis on previous uses of linear eigenmode characteristics in the literature. An analytic treatment of relevant fluid and kinetic linear waves follows, providing motivation for the choice of three eigenmode characteristics for studying solar wind turbulence in this dissertation. The novel synthetic spacecraft time series method is next detailed and its use in describing magnetized turbulence justified. The three metrics are then individually employed as a means of comparing the turbulence models used to generate synthetic time series with in situ observations. These comparisons provide useful constraints on various proposed mechanisms for sustaining the turbulence cascade and heating the solar wind plasma.
Fundamentals of the Plasma Sail Concept: MHD and Kinetic Studies
NASA Technical Reports Server (NTRS)
Khazanov, G.; Delamere, P.; Kabin, K.; Linde, T. J.; Krivorutsky, E.
2003-01-01
The Mini-Magnetospheric Plasma Propulsion (M2P2), originally proposed by Winglee et al. [2000] predicts that a 15-km standoff distance (or 20-km cross-sectional dimension) of the magnetic bubble will provide for sufficient momentum transfer from the solar wind to accelerate a spacecraft to the unprecedented speeds of 50-80 km/s after an acceleration period of about three months. Such velocities will enable travel out of the solar system in period of about seven years-almost an order of magnitude improvement over present chemical based propulsion systems. However, for the parameters of the simulation of Winglee et al. [2000], a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the MHD fluid model, normally applied to planetary magnetospheres, that the characteristic scale-size is much greater than the Larmor radius and ion skin depth of the solar wind. In the case of M2P2, the size of the magnetic bubble is actually less than or, comparable to, the scale of these characteristic parameters. Therefore, a kinetic approach, which addresses the small-scale physical mechanisms, must be used. We have adopted a two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail. The first component is a self-consistent MHD simulation of the small-scale expansion phase of the magnetic bubble. The fluid treatment is valid to roughly 5 km from the source and the steady-state MHD solution at the 5 km boundary was then used as initial conditions for the hybrid simulation. The hybrid simulations showed that the momentum transfer to the innermost regions of the plasma sail is negligible.
NASA Astrophysics Data System (ADS)
Germaschewski, K.; Raeder, J.; Ruhl, H.
2010-12-01
Advances in processor technology provide the opportunity to simulate space plasma dynamics at unprecedented resolution. As processor clock speeds have begun to plateau in recent years, new technologies have emerged that maintain exponential growth in computational capability, in particular multi-core processors and heterogeneous approaches to computing, e.g., the STI Cell processor and general purpose GPUs. We will discuss two projects that aim at porting existing codes to efficiently run on heterogeneous processors. The Particle Simulation Code (PSC) is a 3D fully electromagnetic particle-in-cell code, solving the kinetic plasma equations, including a collision operator. This code is applied to problems requiring a kinetic model, like particle acceleration and modeling the microscopic structure of a reconnecting current sheets. We will discuss the performance gains enabled by porting the code to NVIDIA's GPU CUDA programming environment, as well as the challenges in exploiting the full capabilities of GPUs for the current deposition step. OpenGGCM is a community global magnetosphere model. The main computational challenge is the solution of the 3D MHD equations which are discretized using finite-difference / finite-volume. We ported this code to the Cell processor using a novel code generator. This approach allows us to specify the discretized equations in near-symbolic form as a stencil computation, and then have highly-optimized code be generated automatically. From the same description we are able to generate plain C code, C code with SIMD/SSE2 extensions and code for the Cell processor, yielding significant performance gains. We will also present first results of a new extension to the code generator that creates CUDA code for GPUs.
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.
Kinetic Modeling of the Lunar Dust-Plasma Environment
NASA Astrophysics Data System (ADS)
Kallio, Esa; Alho, Markku; Alvarez, Francisco; Barabash, Stas; Dyadechkin, Sergey; Fernandes, Vera; Futaana, Yoshifumi; Harri, Ari-Matti; Haunia, Touko; Heilimo, Jyri; Holmström, Mats; Jarvinen, Riku; Lue, Charles; Makela, Jakke; Porjo, Niko; Schmidt, Walter; Shahab, Fatemi; Siili, Tero; Wurz, Peter
2014-05-01
Modeling of the lunar dust and plasma environment is a challenging task because a self-consistent model should include ions, electrons and dust particles and numerous other factors. However, most of the parameters are not well established or constrained by measurements in the lunar environment. More precisely, a comprehensive model should contain electrons originating from 1) the solar wind, 2) the lunar material (photoelectrons, secondary electrons) and 3) the lunar dust. Ions originate from the solar wind, the lunar material, the lunar exosphere and the dust. To model the role of the dust in the lunar plasma environment is a highly complex task since the properties of the dust particles in the exosphere are poorly known (e.g. mass, size, shape, conductivity) or not known (e.g. charge and photoelectron emission) and probably are time dependent. Models should also include the effects of interactions between the surface and solar wind and energetic particles, and micrometeorites. Largely different temporal and spatial scales are also a challenge for the numerical models. In addition, the modeling of a region on the Moon - for example on the South Pole - at a given time requires also knowledge of the solar illumination conditions at that time, mineralogical and electric properties of the local lunar surface, lunar magnetic anomalies, solar UV flux and the properties of the solar wind. Harmful effects of lunar dust to technical devices and to human health as well as modeling of the properties of the lunar plasma and dust environment have been topics of two ESA funded projects L-DEPP and DPEM. In the presentation we will summarize some basic results and characteristics of plasma and fields near and around the Moon as studied and discovered in these projects. Especially, we analyse three different space and time scales by kinetic models: [1] the "microscale" region near surface with an electrostatic PIC (ions and electrons are particles) model, [2] the "mesoscale" region including lunar magnetic anomalies and [3] the global scale Moon-solar wind interaction with hybrid (ions as particles in massless electron fluid) models.
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.
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.
CURRENT SHEETS AND COLLISIONLESS DAMPING IN KINETIC PLASMA TURBULENCE
TenBarge, J. M.; Howes, G. G., E-mail: jason-tenbarge@uiowa.edu [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)
2013-07-10
We present the first study of the formation and dissipation of current sheets at electron scales in a wave-driven, weakly collisional, three-dimensional kinetic turbulence simulation. We investigate the relative importance of dissipation associated with collisionless damping via resonant wave-particle interactions versus dissipation in small-scale current sheets in weakly collisional plasma turbulence. Current sheets form self-consistently from the wave-driven turbulence, and their filling fraction is well correlated to the electron heating rate. However, the weakly collisional nature of the simulation necessarily implies that the current sheets are not significantly dissipated via Ohmic dissipation. Rather, collisionless damping via the Landau resonance with the electrons is sufficient to account for the measured heating as a function of scale in the simulation, without the need for significant Ohmic dissipation. This finding suggests the possibility that the dissipation of the current sheets is governed by resonant wave-particle interactions and that the locations of current sheets correspond spatially to regions of enhanced heating.
Galvao, R. A.; Ziebell, L. F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil)
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.
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.
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.
Kinetic theory for distribution functions of wave-particle interactions in plasmas
Kominis, Y.
The evolution of a charged particle distribution function under the influence of coherent electromagnetic waves in a plasma is determined from kinetic theory. For coherent waves, the dynamical phase space of particles is ...
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
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.
Kinetic Modeling of Plasma formed during Aerobraking in the Martian Atmosphere
NASA Astrophysics Data System (ADS)
Smithwick, Evan; Drake, Dereth
2014-03-01
During Martian atmospheric aerobraking the plasma that forms around a spacecraft can be considered a high-volume plasma reactor that is sustained by the dissipation of the spacecraft's kinetic energy. At altitudes below 100 km, it has been shown that the plasma parameters vary considerably depending on the spacecraft's trajectory. However, in range which is applicable to aerobraking, 100 km < h <200 km, little of this work has been completed. We have evaluated a simple kinetic model to determine a probable range of plasma parameters for altitudes between 100 and 200 km using existing Martian atmospheric data and all recorded probe trajectories.
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.
Effects of dust particles in plasma kinetics: Ion dynamics time scales
Angelis, U. de [Department of Physical Sciences, University of Naples and INFN, Sezione di Napoli 80126 (Italy); Tolias, P.; Ratynskaia, S. [Space and Plasma Physics, Royal Institute of Technology, Stockholm SE-100 44 (Sweden)
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.
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.
Initial plasma density dependence of kinetic energy of ions collected on electrode
NASA Astrophysics Data System (ADS)
Ogura, Koichi; Shibata, Takemasa
1994-01-01
Gadolinium plasma was produced between parallel-plate electrodes by resonance photoionization. The kinetic energy of the ions, which were extracted from the plasma and collected on the electrode by means of an electric field, was measured by the time-of-flight method. At the applied potential of V(sub 0), the kinetic energy of ions increased continuously from 0.5 eV(sub 0) to eV(sub 0) with increasing initial plasma density. The initial plasma density which was required to change the kinetic energy of ions from 0.5 eV(sub 0) to eV(sub 0) or to maintain the quasi-neutral plasma was estimated using a simple one-dimensional model.
Kinetic parameters for plasma. beta. -endorphin in lean and obese Zucker rats
Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H. (Department of Exercise and Sport Science, Pennsylvania State University, University Park (USA))
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.
Measurement of the kinetic dust temperature of a weakly coupled dusty plasma
Williams, Jeremiah D.; Thomas, Edward Jr. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)
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)
Advances in Fully-Kinetic PIC Simulations of a Near-Vacuum Hall Thruster and Other Plasma Systems
Advances in Fully-Kinetic PIC Simulations of a Near- Vacuum Hall Thruster and Other Plasma Systems;3 Advances in Fully-Kinetic PIC Simulations of a Near- Vacuum Hall Thruster and Other Plasma Systems generation of simulations used the fully-kinetic particle-in-cell (PIC) model. Although much more
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,2RevLett.100.065004 PACS numbers: 52.35.Ra, 52.65.Tt, 96.50.Tf Introduction.--A wide variety of astrophysical mean field related by kk / k2=3 ? . This implies that in most astrophysical plasmas, the frequencies
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.
New Kinetic Equations and Bogolyubov Energy Spectrum in a Fermi Quantum Plasma
Tsintsadze, Nodar L.; Tsintsadze, Levan N.
2009-10-08
New type of quantum kinetic equations of the Fermi particles are derived. The Bogolyubov's type of dispersion relation, which is valid for the Bose fluid, is disclosed. Model of neutral Bose atoms in dense strongly coupled plasmas with attractive interaction is discussed. A set of fluid equations describing the quantum plasmas is obtained. Furthermore, the equation of the internal energy of degenerate Fermi plasma particles is derived.
NASA Astrophysics Data System (ADS)
Gaboriau, F.; Boeuf, J. P.
2014-12-01
This paper presents a systematic kinetic characterization of a low pressure high power hydrogen plasma. The plasma physics is described with a global model coupled to a homogeneous kinetic model for hydrogen. This model involves reactions which describe the vibrational and electronic excited kinetics of H2, the positive ?ft( H{+}{,}H2{+}{,}H3{+} \\right) and negative (H?) ion kinetics and the H chemistry. This enables the estimation of the particle density and the electron temperature and their evolutions as a function of power (1–100 kW) and pressure (0.3–4 Pa). These very specific plasma conditions involve physical phenomena not occurring in more usual plasmas, such as gas depletion. To account for this gas depletion, we incorporate in the global model both the H neutral heat equation to calculate the H temperature, and the gas pumping. Indeed, the gas depletion is mainly due to H atom heating leading to a higher pumping loss for H atoms. The consideration of the gas depletion allows us to obtain similar behaviors to the experiments when varying power and pressure. From an accurate analysis of the main formation and destruction pathways for each particle, the species kinetics is discussed and a simplified kinetic model that may be used to describe the non-equilibrium plasma in the negative source for ITER is proposed. Finally, the results point to strong coupling existing between the H atom wall recombination coefficient ?H and the gas depletion. An increase of ?H reduces the gas depletion, affecting the electron temperature and the electron density as well as the whole plasma kinetics.
Ion beam generation at the plasma sheet boundary layer by kinetic Alfven waves
NASA Technical Reports Server (NTRS)
Moghaddam-Taaheri, E.; Goertz, C. K.; Smith, R. A.
1989-01-01
A two-dimensional quasi-linear numerical code was developed for studying ion beam generation at the plasma sheet boundary layer by kinetic Alfven waves. The model assumes that the central plasma sheet is the particle source, and that the last magnetic field lines on which kinetic Alfven waves exist and diffusion occurs can be either open or closed. As the possible source for the excitement of the kinetic Alfven waves responsible for ion diffusion, the resonant mode conversion of the surface waves to kinetic Alfven waves is considered. It is shown that, depending on the topology of the magnetic field at the lobe side of the simulation system, i.e., on whether field lines are open or closed, the ion distribution function may or may not reach a steady state.
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.
Towards adaptive kinetic-fluid simulations of low-temperature plasmas
NASA Astrophysics Data System (ADS)
Kolobov, Vladimir
2013-09-01
The emergence of new types of gaseous electronics in multi-phase systems calls for computational tools with adaptive kinetic-fluid simulation capabilities. We will present an Adaptive Mesh and Algorithm Refinement (AMAR) methodology for multi-scale simulations of gas flows and discuss current efforts towards extending this methodology for weakly ionized plasmas. The AMAR method combines Adaptive Mesh Refinement (AMR) with automatic selection of kinetic or fluid solvers in different parts of computational domains. This AMAR methodology was implemented in our Unified Flow Solver (UFS) for mixed rarefied and continuum flows. UFS uses discrete velocity method for solving Boltzmann kinetic equation under rarefied flow conditions coupled to fluid (Navier-Stokes) solvers for continuum flow regimes. The main challenge of extending AMAR to plasmas comes from the distinction of electron and atom mass. We will present multi-fluid, two-temperature plasma models with AMR capabilities for simulations of glow, corona, and streamer discharges. We will briefly discuss specifics of electron kinetics in collisional plasmas, and deterministic methods of solving kinetic equations for different electron groups. Kinetic solvers with Adaptive Mesh in Phase Space (AMPS) will be introduced to solve Boltzmann equation for electrons in the presence of electric fields, elastic and inelastic collisions with atoms. These kinetic and fluid models are currently being incorporated into AMAR methodology for multi-scale simulations of low-temperature plasmas in multi-phase systems. The emergence of new types of gaseous electronics in multi-phase systems calls for computational tools with adaptive kinetic-fluid simulation capabilities. We will present an Adaptive Mesh and Algorithm Refinement (AMAR) methodology for multi-scale simulations of gas flows and discuss current efforts towards extending this methodology for weakly ionized plasmas. The AMAR method combines Adaptive Mesh Refinement (AMR) with automatic selection of kinetic or fluid solvers in different parts of computational domains. This AMAR methodology was implemented in our Unified Flow Solver (UFS) for mixed rarefied and continuum flows. UFS uses discrete velocity method for solving Boltzmann kinetic equation under rarefied flow conditions coupled to fluid (Navier-Stokes) solvers for continuum flow regimes. The main challenge of extending AMAR to plasmas comes from the distinction of electron and atom mass. We will present multi-fluid, two-temperature plasma models with AMR capabilities for simulations of glow, corona, and streamer discharges. We will briefly discuss specifics of electron kinetics in collisional plasmas, and deterministic methods of solving kinetic equations for different electron groups. Kinetic solvers with Adaptive Mesh in Phase Space (AMPS) will be introduced to solve Boltzmann equation for electrons in the presence of electric fields, elastic and inelastic collisions with atoms. These kinetic and fluid models are currently being incorporated into AMAR methodology for multi-scale simulations of low-temperature plasmas in multi-phase systems. Supported by AFOSR, NASA, and DoE
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. (Pennsylvania State Univ., University Park (United States))
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.
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.
Dick C. Chan; Gerald F. Watts; Trevor G. Redgrave; Trevor A. Mori; P. Hugh R. Barrett
2002-01-01
Obesity is strongly associated with dyslipidemia, which may account for the associated increased risk of atherosclerosis and coronary disease. We aimed to test the hypothesis that kinetics of hepatic apolipoprotein B-100 (apoB) metabolism are disturbed in men with visceral obesity and to examine whether these kinetic defects are associated with elevated plasma concentration of apolipoprotein C-III (apoC-III). Very[ndash ]low-density lipoprotein
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.
Kinetic description of charmonium production in high-energy nuclear collisions
Polleri, Alberto; Weise, Wolfram; Renk, Thorsten; Schneider, Roland
2004-10-01
We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows us to study in detail the evolution in different regimes, controlled by collision energy, kinematics, and geometry. The data collected at the CERN-SPS accelerator are well described and new estimates for J/{psi} production at BNL-RHIC are presented.
Nonlinear kinetic Alfvén waves with non-Maxwellian electron population in space plasmas
NASA Astrophysics Data System (ADS)
Masood, W.; Qureshi, M. N. S.; Yoon, P. H.; Shah, H. A.
2015-01-01
The present work discusses the effects of non-Maxwellian electron distributions on kinetic Alfvén waves in low-beta plasmas. Making use of the two-potential theory and employing the Sagdeev potential approach, the existence of solitary kinetic Alfvén waves having arbitrary amplitude is investigated. It is found that the use of non-Maxwellian population of electrons in the study of kinetic Alfvén waves leads to solutions corresponding to solitary structures that do not exist for Maxwellian electrons. The present investigation solves the riddle of plasma density fluctuations associated with strong electromagnetic perturbations observed by the Freja satellite. The present findings can also be applied to regions of space where various satellite missions have observed the presence of suprathermal populations of plasma species and where the low ? assumption is valid.
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 ...
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 ...
Visualizing the Kohn-Sham kinetic energy density and its orbital-free description in molecules
Cancio, Antonio C; Kuna, Aeryk I
2015-01-01
We visualize the Kohn-Sham kinetic energy density (KED), and the ingredients -- the electron density, its gradient and Laplacian -- used to construct orbital-free models of it, for the AE6 test set of molecules. These are compared to related quantities used in metaGGA's, to characterize two important limits -- the gradient expansion and the localized-electron limit typified by the covalent bond. We find the second-order gradient expansion of the KED to be a surprisingly successful predictor of the exact KED, particularly at low densities where this approximation fails for exchange. This contradicts the conjointness conjecture that the optimal enhancement factors for orbital-free kinetic and exchange energy functionals are identical. In addition we find significant problems with a recent metaGGA-level orbital-free KED, especially for regions of strong electron localization. We define an orbital-free description of electron localization and a revised metaGGA that improves upon atomization energies significantly...
Drift kinetic Alfvén wave in temperature anisotropic plasma
Naim, Hafsa, E-mail: roohi-phy@yahoo.com; Bashir, M. F. [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan) [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Department of Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Murtaza, G. [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan)] [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan)
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.
NASA Astrophysics Data System (ADS)
Agafonova, L. E.; Shumyantseva, V. V.; Archakov, A. I.
2014-06-01
The quartz crystal microbalance (QCM) was exploited for cardiac markers detection and kinetic studies of immunochemical reaction of cardiac troponin I (cTnI) and human heart fatty acid binding protein (H-FABP) with the corresponding monoclonal antibodies in undiluted plasma (serum) and standard solutions. The QCM technique allowed to dynamically monitor the kinetic differences in specific interactions and nonspecific sorption, without multiple labeling procedures and separation steps. The affinity binding process was characterized by the association (ka) and the dissociation (kd) kinetic constants and the equilibrium association (K) constant, all of which were obtained from experimental data.
Kinetic measurements of shock wave propagation in a three-dimensional complex (dusty) plasma
NASA Astrophysics Data System (ADS)
Samsonov, D.; Morfill, G.; Thomas, H.; Hagl, T.; Rothermel, H.; Fortov, V.; Lipaev, A.; Molotkov, V.; Nefedov, A.; Petrov, O.; Ivanov, A.; Krikalev, S.
2003-03-01
“Complex plasmas” consist of electrons, ions, and charged microparticles. The latter are individually observable, allowing kinetic measurements in plasmas. Using a sudden gas pulse, a traveling perturbation was initiated in such a complex plasma and its propagation, acceleration, and steepening—possibly into a shock was followed. The experiment was performed in the PKE-Nefedov laboratory under microgravity conditions on the international space station, i.e., in a complex plasma cloud with very little stored (potential or free) energy and thus free of, e.g., parametric instabilities. The perturbation front remained remarkably smooth, with a microroughness of the order of the interparticle distance. The observations are presented and interpreted.
Nonstationary kinetic theory of ion transport in plasma with small perturbations
Brantov, A. V., E-mail: brantov@sci.lebedev.ru; Bychenkov, V. Yu. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Rozmus, W. [University of Alberta, Department of Physics (Canada)
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.
Time-dependent gas phase kinetics in a hydrogen diluted silane plasma
Nunomura, S.; Kondo, M.; Yoshida, I.
2009-02-16
The gas phase kinetics in a high-pressure hydrogen diluted silane plasma has been studied at time scales of 10{sup -2}-6x10{sup 2} s. The time-resolved gas phase composition shows the following kinetics at different time scales: silane decomposition and polysilane generation in < or approx. 2x10{sup -1} s, nanoparticle formation and plasma density reduction in 10{sup -1}-10{sup 0} s, polysilane accumulation in 10{sup 0}-10{sup 2} s, and silane depletion and electrode heating in > or approx. 10{sup 1} s. Disilane radicals are implied to be the dominant film precursors in addition to silyl radicals.
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.
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.
Landau damping and kinetic instability in non-Maxwellian highly electronegative multi-species plasma
NASA Astrophysics Data System (ADS)
Arshad, Kashif; Mirza, Arshad M.
2014-02-01
The effect of two negative ions on the Landau damping and stellar solar wind driven instability is analyzed using kinetic theory for the Lorentzian plasmas. It is investigated that the dispersion relations, damping rates and instability growths are appreciably modified in the presence of Generalized Lorentzian or kappa distributed function and additional negative ion in our plasma system. A quantitative measurement of the threshold value of the streaming velocity is also determined to estimate the condition of the growing instability.
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.
PIC simulation of kinetic effects of plasma and consequences for physical sputtering
NASA Astrophysics Data System (ADS)
Kawamura, G.; Tomita, Y.; Kirschner, A.
2011-08-01
Impurities in a fusion plasma device such as carbon, beryllium and tungsten are one of major concerns about performance of the plasma and also engineering design. In simulation codes of impurity transport and redeposition, the physical sputtering yield due to the background plasma is calculated by an empirical model and a Monte Carlo code based on the binary collision model for a plasma without the magnetic field. In this work, kinetic effects of ions in a magnetized plasma on the physical sputtering yield were investigated by using a particle-in-cell simulation code and a sputtering model. An increasing effect of the magnetic field on the yield was found when the field was nearly parallel to the surface. The effect becomes strong when the field is strong and the plasma density is low.
Kinetic theory on the current-filamentation instability in collisional plasmas
Hao Biao [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Sheng, Z.-M.; Zhang, J. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)
2008-08-15
The current filamentation instability (CFI) or Weibel-type instability is studied for a nonrelativistic electron beam penetrating an infinite uniform plasma, taking into account both the collisional effects and the space-charge effect (SCE). We consider three configurations for the beam and plasma: the kinetic domain, the hydrodynamic domain, and the hybrid domain with one in kinetic and the other in hydrodynamic domain. It is shown that the CFI is determined by the current-driven drift-anisotropy rather than the classical anisotropy of the beam and the background plasma. Therefore, collisional effects can either attenuate or enhance the CFI depending on the drift-anisotropy of the beam and the background plasma. It is found that the collisional effects usually attenuate the CFI for nearly symmetric counterstreaming in the whole unstable range but enhance it for asymmetric counterstreaming in the long wavelength region both in the kinetic and the hydrodynamic domains, although the mechanisms are different. As for the case of the hybrid domain the collisional effects enhance the CFI growth rate in the long wavelength region but reduce it in the short wavelength region. The SCE can be ignored for the hydrodynamic domain while for the kinetic and the hybrid domains it is still significant though damped by the collisional effects. The combination of the SCE and the collisional effects usually reduce the CFI growth rate and suppress the unstable range further, especially in the short wavelength region.
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
On The Kinetic Stage Of Instability Of The Electron Beam - Solar Wind Plasma System
Lyahov, V V
2010-01-01
Within the framework of quasilinear theory it has been found that when radio bursts of III type are generated by the inhomogeneous system of electron beam - solar wind plasma, only time of development of the primary stage of instability, i.e., agnetohydrodynamic, is more than the total time of relaxation of an electron beam derived within the homogeneous model. During the development of hydrodynamic instability the electron beam is spread from the Sun to the distance of 4 astonomical unities. The hydrodynamic stage is followed by the development of kinetic instability leading, ultimately, to the formation of horizontal plateau in the beam region at the tail of Maxwell distribution. Parameters of the plateau, such as its length and height, have been calculated as characteristic parameters of an electron beam generated by the active solar bursts. In the development of kinetic beam instability more than a half of kinetic energy of the beam is transmitted to plasma oscillations.
Viriato: a Fourier-Hermite spectral code for strongly magnetised fluid-kinetic plasma dynamics
Loureiro, N F; Fazendeiro, L; Kanekar, A; Mallet, A; Vilelas, M S; Zocco, A
2015-01-01
We report on the algorithms and numerical methods used in Viriato, a novel fluid-kinetic code that solves two distinct sets of equations: (i) the Kinetic Reduced Electron Heating Model (KREHM) equations [Zocco & Schekochihin, Phys. Plasmas 18, 102309 (2011)] (which reduce to the standard Reduced-MHD equations in the appropriate limit) and (ii) the kinetic reduced MHD (KRMHD) equations [Schekochihin et al., Astrophys. J. Suppl. 182:310 (2009)]. Two main applications of these equations are magnetised (Alfvenic) plasma turbulence and magnetic reconnection. Viriato uses operator splitting (Strang or Godunov) to separate the dynamics parallel and perpendicular to the ambient magnetic field (assumed strong). Along the magnetic field, Viriato allows for either a second-order accurate MacCormack method or, for higher accuracy, a spectral-like scheme composed of the combination of a total variation diminishing (TVD) third order Runge-Kutta method for the time derivative with a 7th order upwind scheme for the fluxe...
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.
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.
NASA Astrophysics Data System (ADS)
Mašek, Martin; Rohlena, Karel
2015-05-01
Influence of kinetic effects on 3-wave interaction was examined within the frame of stimulated Raman backward scattering (SRBS) in a rarefied laser corona. The plasma is supposed to be weakly collisional with a negligible density gradient. The model is centred on the physical situation of shock ignition at a large scale direct drive compression experiments. The modelling uses a 1D geometry in a Maxwell-Vlasov model. The method used is a truncated Fourier-Hermite expansion numerically stabilized by a model collisional term with a realistic value of the collision frequency. In parallel, besides the linear theory of SRBS, a coupled mode 3-wave equation system (laser driving wave, Raman back-scattered wave and the daughter forward scattered plasma wave) is solved to demonstrate the correspondence between the full kinetic model and 3-wave interaction with no electron kinetics involved to identify the differences between both the solutions arising due to the electron kinetic effects. We concentrated mainly on the Raman reflectivity, which is one of the important parameters controlling the efficiency of the shock ignition scheme. It was found that the onset of the kinetic effects has a distinct intensity threshold, above which the Raman reflectivity may go down due to the electron kinetics. In addition, we were trying to identify the most important features of the electron phase space behaviour, such as particle trapping in potential minima of the generated plasma wave and its consequences for the 3-wave interaction. The role of the trapped electrons seems to be crucial for a deformation of the plasma wave dispersion curve, as indicated in some earlier work.
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.
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.
EXCITATION OF KINETIC ALFVEN WAVES BY DENSITY STRIATION IN MAGNETO-PLASMAS
Wu, D. J.; Chen, L., E-mail: clvslc214@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
2013-07-01
Field-aligned density striation is one of the most common inhomogeneity phenomena in magneto-plasmas, such as in the solar coronal plasma and terrestrial auroral plasma. Kinetic Alfven waves (KAWs) can play an important role in the inhomogeneous heating of coronal magneto-plasmas as well as in the local acceleration of auroral energetic electrons. In this paper, we study the dispersion and instability of KAWs in a magneto-plasma with density striation structures. Results show that KAWs become unstable in the presence of the density striation and the corresponding instability has a maximal growth rate at the perpendicular wavelength close to the spatial scale of the density gradient. Related experimental phenomena in both laboratory and space plasmas are discussed. It is suggested that the excitation of KAWs by the density striation of magneto-plasmas can be of potential importance in understanding the physics of the formation of magneto-plasma filaments and their heating mechanisms, which are often present in the terrestrial auroral plasma, the solar coronal plasma, and other astrophysical plasmas.
Ott, M. W.
1981-04-01
Using a Krook collision model with relaxation to a flowing Maxwellian distribution function, a one dimensional flowing plasma solution to the kinetic equation is obtained for ions. The theory extends the analysis of collisionless flow from a theta pinch to include collisions, and yields a distribution function in the transition regime between collisonless and collisional flow. The model shows features of each extreme, and permits calculation of the fundamental system parameters including thermal energy flux and parallel viscosity to replace classically derived fluid description concepts which break down in this regime. A second problem which is investigated is the analysis of collisionless flow interaction with a representative reflecting surface. Reflected densities are calculated and presented for both specular and diffuse reflection. A comparison with a conventional reflected shock wave is also presented. The results indicate a density buildup near the reflector, as would be expected, and this effect is more pronounced when the reflected temperature is lower.
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.
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.
G. G. Coppa; Paolo Ricci
2002-01-01
This work deals with a noncollisional kinetic model for non-neutral plasmas in a Penning trap. Using the spatial coordinates r, theta, z and the axial velocity vz as phase-space variables, a kinetic model is developed starting from the kinetic equation for the distribution function f(r,theta,z,vz,t). In order to reduce the complexity of the model, the kinetic equations are integrated along
Kinetic Alfven waves as a source of plasma transport at the dayside magnetopause
Lee, L.C.; Johnson, J.R.; Ma, Z.W. [Univ. of Alaska, Fairbanks, AK (United States)] [Univ. of Alaska, Fairbanks, AK (United States)
1994-09-01
As the shocked solar wind with variable plasma density and magnetic field impinges on the dayside magnetopause, it is likely to generate large-scale Alfven waves at the solar wind magnetosphere interface. However, large gradients in the density and magnetic field at the magnetopause boundary effectively couple large-scale Alfven waves with kinetic Alfven waves. In this paper the authors propose that the wave power converted into kinetic Alfven waves may play an important role in plasma transport at the dayside magnetopause and in electron acceleration along field lines. The transport can occur because, unlike the magnetohydrodynamic (MHD) shear Alfven wave, the kinetic Alfven wave has an associated parallel electric field which breaks down the {open_quotes}frozen-in{close_quotes} condition and decouples the plasma from field lines. The authors calculate the average deviation of the plasma from the field line from which they estimate the diffusion coefficient associated with these {open_quotes}bundles{close_quotes} of decoupled plasma to be approximately 10{sup 9}m{sup 2}/s. The parallel electric field also may lead to acceleration of electrons along field lines in the magnetopause boundary and may possibly provide an explanation for observed counterstreaming electron beams characterized by energies of 50-200 eV. 31 refs., 4 figs.
One-dimensional hybrid-direct kinetic simulation of the discharge plasma in a Hall thruster
Hara, Kentaro; Boyd, Iain D. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Kolobov, Vladimir I. [CFD Research Corporation, Huntsville, Alabama 35805 (United States)
2012-11-15
In order to model the non-equilibrium plasma within the discharge region of a Hall thruster, the velocity distribution functions (VDFs) must be obtained accurately. A direct kinetic (DK) simulation method that directly solves the plasma Boltzmann equation can achieve better resolution of VDFs in comparison to particle simulations, such as the particle-in-cell (PIC) method that inherently include statistical noise. In this paper, a one-dimensional hybrid-DK simulation, which uses a DK simulation for heavy species and a fluid model for electrons, is developed and compared to a hybrid-PIC simulation. Time-averaged results obtained from the hybrid-DK simulation are in good agreement with hybrid-PIC results and experimental data. It is shown from a comparison of using a kinetic simulation and solving the continuity equation that modeling of the neutral atoms plays an important role for simulations of the Hall thruster discharge plasma. In addition, low and high frequency plasma oscillations are observed. Although the kinetic nature of electrons is not resolved due to the use of a fluid model, the hybrid-DK model provides spatially and temporally well-resolved plasma properties and an improved resolution of VDFs for heavy species with less statistical noise in comparison to the hybrid-PIC method.
Plasma-resistivity-induced strong damping of the kinetic resistive wall mode.
He, Yuling; Liu, Yueqiang; Liu, Yue; Hao, Guangzhou; Wang, Aike
2014-10-24
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. PMID:25379920
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.
A comparison of kinetic and multifluid simulations of laser-produced colliding plasmas
Rambo, P.W.; Procassini, R.J. [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)] [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)
1995-08-01
The amount of interpenetration and stagnation in counterstreaming laser-produced plasmas is investigated via a kinetic model and a multifluid model in one-dimensional planar geometry. Each of these models can evolve multiple ion species in the self-consistent electrostatic field with Coulomb collisional interaction. The two approaches are applied to various colliding plasma systems, ranging from simple homogeneous slowing-down and temperature-equilibration problems to colliding plasmas characteristic of laser irradiated thin foils and thick disks. In particular, direct comparisons are made between the kinetic formulation and the multifluid model with various approximations for the multifluid collisional coupling coefficients. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Plasma kinetics of complement component C4: comparison of three models
Wisnieski, J.J.; Nathanson, M.H.
1989-02-01
Plasma C4 kinetics were studied in members of a kindred with hereditary incomplete C4 deficiency and in control subjects. Test subjects received iodine /sup 125/-labeled C4 intravenously, and plasma disappearance curves for 125I-C4 were plotted. By nonlinear least-squares analysis, we fit two-, three-, and four-exponential models of plasma disappearance to the plasma curves of each subject. Goodness of fit was significantly better for all subjects with the three-exponential versus the two-exponential model (p less than 0.0005). No further improvement in curve fit was accomplished by using a four-exponential model (p greater than 0.5). Metabolic rates and extravascular/plasma ratios calculated from the two- and three-exponential models were significantly different. As judged by extravascular/plasma ratio, the two-exponential model underestimated the amount of extravascular C4. Furthermore, the two-exponential model significantly over-estimated catabolic and synthetic rates. Hence, our results show that C4 kinetics are not optimally described by a conventional, two-exponential model. A possible explanation for our findings is that in previous studies of C4 metabolism, the analysis of plasma radioactivity disappearance curves was done by inspection, whereas we used least-squares analysis, a method that determines the number of exponentials with greater reliability.
Measurements of the Linear Kinetic Plasma Response to Alfvén Waves
NASA Astrophysics Data System (ADS)
Schroeder, J. W. R.; Skiff, F.; Howes, G. G.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.
2014-10-01
Alfvén waves likely account for a significant fraction of auroral electron acceleration. However, a direct test of electron acceleration by Alfvén waves has never been accomplished. Complex trajectories and limited resolutions have prevented in situ observations from completing thorough tests of existing theory. Until now, laboratory diagnostics have not been sensitive to the predicted small fluctuations in the tail of the electron distribution function fe. A novel diagnostic developed at the University of Iowa uses the absorption of a small-amplitude whistler wave to measure fe up to 1 keV with 0 . 1 % accuracy. Inertial Alfvén waves (vte /vA ~ 0 . 2) with ?B / B ~10-5 are launched in an overdense plasma at the Large Plasma Device (LaPD) with B0 = 1800 G. Under these conditions, only the whistler mode propagates parallel to the background magnetic field at frequencies just below the electron cyclotron frequency. Results show fluctuations in the tail of the distribution function at the frequency of the Alfvén wave. An analytic solution from the Boltzmann equation is used to describe experimental results. Further analysis of measurements is presented and is compared to theoretical predictions.
Redi, C A; Garagna, S; Heth, G; Nevo, E
1986-04-01
The descriptive kinetics of the spermatogenic process has been studied in the four chromosomal species of Spalax ehrenbergi between November and March, the active period of reproduction. Spermatid development can be subdivided into 16 steps in which the acrosome formation is clearly distinguishable and the Golgi, cap and acrosomic phases are identifiable. The first 12 steps of spermiogenesis can be utilized for the definition of characteristic time-dependent relationships among different germ cell associations (stages): twelve stages, I-XII, are clearly identifiable. In this regard no differences exist among the four chromosomal species. In general, the spermatogenic process in this species has the same pattern as that of Mus domesticus. Two relevant points distinguish Spalax spermatogenesis from Mus spermatogenesis: 1) the presence, throughout the stages I-XII of the seminiferous epithelium cycle of a larger size, oval shaped spermatogonium type containing heterochromatic granulations; 2) the Sertoli cells show only one heterochromatic clump closely attached to the nucleolus; moreover, the Sertoli cell cytoplasm is more PAS-positive than that of Mus. PMID:3711819
Linear description of nonlinear electromagnetic cold plasma modes based on generalized vorticity
NASA Astrophysics Data System (ADS)
Verheest, Frank
2009-08-01
Based on a multispecies plasma description in terms of canonical vorticities, the search for exact harmonic wave profiles at arbitrary amplitudes, and the possible linear superposition of such nonlinear waves, has been discussed in terms of linearizing principles and their validity. Assuming first that the fluid velocities and wave canonical vorticities are parallel, with constant factors of proportionality, leads to incompressible plasmas that always remain charge neutral and to transverse, nondispersive waves with circular polarization. Contrary to claims in the literature, there are only as many wavenumber solutions as plasma species and these cannot serve as a basis for all solutions of the linearized equations describing the chosen plasma model. By simply dropping the nonlinear term in the species vorticity equations, dispersive waves obtain, for unidirectional propagation in incompressible plasmas. There being no wavenumber restrictions, these waves can serve as a full basis to express other solutions in. For pair plasmas the polarization is linear.
Three-dimensional drift kinetic response of high-? plasmas in the DIII-D tokamak.
Wang, Z R; Lanctot, M J; Liu, Y Q; Park, J-K; Menard, J E
2015-04-10
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)]. PMID:25910133
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)].
Sintering Kinetics of Plasma-Sprayed Zirconia TBCs
NASA Astrophysics Data System (ADS)
Cipitria, A.; Golosnoy, I. O.; Clyne, T. W.
2007-12-01
The sintering of free-standing plasma sprayed TBCs has been modeled, based on variational principles of free energy minimization and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with the experimental data obtained by dilatometry and BET analysis, respectively. The sensitivity of the predictions to initial pore architecture and material properties is assessed. The model can be used to predict the evolution of the contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously developed analytical model (I.O. Golosnoy, et al. J. Therm. Spray Technol., 2005, 14(2), p 205-214).
Bistoletti, M; Alvarez, L; Lanusse, C; Moreno, L
2014-01-01
1. To optimise the use of albendazole (ABZ) as an anthelmintic in hens, the effects of fasting and type of diet on the plasma kinetics of ABZ and its metabolites were evaluated. 2. Twenty-four hens were distributed into 4 groups: In experiment I the Fed group were fed ad libitum, while the Fasted group was fasted over a 12-h period. In experiment II the Pelleted group was fed with pelleted commercial food, while the Grain group was fed with cereal grains. All the groups were treated with ABZ by oral route. Blood samples were taken and plasma analysed by HPLC. 3. ABZ and its metabolites albendazole-sulphoxide (ABZSO) and albendazole-sulphone (ABZSO2) were recovered in plasma in all the groups. The 12-h fasting period did not modify the disposition kinetics of ABZ in hens. The type of feed affected ABZ kinetics. ABZSO concentration profile was higher and detected for longer in the Grain group compared to the Pelleted group. Statistical differences were not found for AUC0-? values, whereas the T1/2for and T1/2el were different between groups. 4. Factors affecting ABZ kinetic behaviour should be taken into account to optimise its use to ensure the sustainability of the limited available anthelmintic therapeutic tools in avian parasite control. PMID:25159169
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
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.
A comparison of kinetic and multifluid simulations of laser-produced colliding plasmas
Rambo, P.W.; Procassini, R.J.
1994-09-01
The collision and subsequent interaction of counter-streaming plasmas occurs in several areas of laser-plasma research including double foil targets for x-ray lasers and the plasma blow-off inside ICF hohlraums. Because a single fluid model allows for only one value of the flow velocity at any one spatial location, interpenetration of the plamas is not allowed resulting in immediate stagnation with complete conversion of the ion-streaming kinetic energy to thermal energy. Multifluid models have been developed which employ multiple ion fluid species that interact through the self-consistent electrostatic field and collisional coupling. Because they are approximations to a kinetic situation, the form of these coupling coefficients is not unique, with various workers using differing approximations. More recently, Larroche has implemented a finite difference approach to the ion Fokker-Planck equation while Jones and co-workers have performed two-dimensional simulations of colliding plasmas using a particle-in-cell code with a new collisional model. Our kinetic modeling also makes use of particle in cell (PIC) techniques with Monte Carlo (MC) particle-particle collisions algorithm that is equivalent to the Fokker-Planck collision operator. We have made direct comparison of this MC-PIC model to multifluid simulations on both simple slowing-down and equilibration problems as well as problems characteristic of laser generated colliding plasmas. These comparisons have established the validity of the multifluid model as well as aided in the development of the kinetic capability for more challenging geometries.
Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory
NASA Astrophysics Data System (ADS)
Schlickeiser, R.; Yoon, P. H.
2015-07-01
Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.
Lauber, Ph. Guenter, S.; Koenies, A.; Pinches, S.D.
2007-09-10
In a plasma with a population of super-thermal particles generated by heating or fusion processes, kinetic effects can lead to the additional destabilisation of MHD modes or even to additional energetic particle modes. In order to describe these modes, a new linear gyrokinetic MHD code has been developed and tested, LIGKA (linear gyrokinetic shear Alfven physics) [Ph. Lauber, Linear gyrokinetic description of fast particle effects on the MHD stability in tokamaks, Ph.D. Thesis, TU Muenchen, 2003; Ph. Lauber, S. Guenter, S.D. Pinches, Phys. Plasmas 12 (2005) 122501], based on a gyrokinetic model [H. Qin, Gyrokinetic theory and computational methods for electromagnetic perturbations in tokamaks, Ph.D. Thesis, Princeton University, 1998]. A finite Larmor radius expansion together with the construction of some fluid moments and specification to the shear Alfven regime results in a self-consistent, electromagnetic, non-perturbative model, that allows not only for growing or damped eigenvalues but also for a change in mode-structure of the magnetic perturbation due to the energetic particles and background kinetic effects. Compared to previous implementations [H. Qin, mentioned above], this model is coded in a more general and comprehensive way. LIGKA uses a Fourier decomposition in the poloidal coordinate and a finite element discretisation in the radial direction. Both analytical and numerical equilibria can be treated. Integration over the unperturbed particle orbits is performed with the drift-kinetic HAGIS code [S.D. Pinches, Ph.D. Thesis, The University of Nottingham, 1996; S.D. Pinches et al., CPC 111 (1998) 131] which accurately describes the particles' trajectories. This allows finite-banana-width effects to be implemented in a rigorous way since the linear formulation of the model allows the exchange of the unperturbed orbit integration and the discretisation of the perturbed potentials in the radial direction. Successful benchmarks for toroidal Alfven eigenmodes (TAEs) and kinetic Alfven waves (KAWs) with analytical results, ideal MHD codes, drift-kinetic codes and other codes based on kinetic models are reported.
On the supergravity description of boost invariant conformal plasma at strong coupling
Paolo Benincasa; Alex Buchel; Michal P. Heller; Romuald A. Janik
2007-12-16
We study string theory duals of the expanding boost invariant conformal gauge theory plasmas at strong coupling. The dual supergravity background is constructed as an asymptotic late-time expansion, corresponding to equilibration of the gauge theory plasma. The absence of curvature singularities in the first few orders of the late-time expansion of the dual gravitational background unambiguously determines the equilibrium equation of the state, and the shear viscosity of the gauge theory plasma. While the absence of the leading pole singularities in the gravitational curvature invariants at the third order in late-time expansion determines the relaxation time of the plasma, the subleading logarithmic singularity can not be canceled within a supergravity approximation. Thus, a supergravity approximation to a dual description of the strongly coupled boost invariant expanding plasma is inconsistent. Nevertheless we find that the relaxation time determined from cancellation of pole singularities is quite robust.
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.
Kinetic Alfven wave instability driven by electron temperature anisotropy in high-beta plasmas
Chen, L. [Purple Mountain Observatory, CAS, Nanjing 210008 (China)] [Graduate School, CAS, Beijing 100012 (China); Wu, D. J. [Purple Mountain Observatory, CAS, Nanjing 210008 (China)
2010-06-15
Based on the kinetic dispersion equation in the low-frequency condition of omega
Fokker-Planck kinetic modeling of suprathermal ?-particles in a fusion plasma
NASA Astrophysics Data System (ADS)
Peigney, B. E.; Larroche, O.; Tikhonchuk, V.
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.
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.
Kinetic and Diagnostic Studies of Molecular Plasmas Using Laser Absorption Techniques
NASA Astrophysics Data System (ADS)
Welzel, S.; Rousseau, A.; Davies, P. B.; Röpcke, J.
2007-10-01
Within the last decade mid infrared absorption spectroscopy between 3 and 20 ?m, known as Infrared Laser Absorption Spectroscopy (IRLAS) and based on tuneable semiconductor lasers, namely lead salt diode lasers, often called tuneable diode lasers (TDL), and quantum cascade lasers (QCL) has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry of molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, organo-silicon and boron compounds has lead to further applications of IRLAS because most of these compounds and their decomposition products are infrared active. IRLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetics. Information about gas temperature and population densities can also be derived from IRLAS measurements. A variety of free radicals and molecular ions have been detected, especially using TDLs. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of QCLs offers an attractive new option for the monitoring and control of industrial plasma processes as well as for highly time-resolved studies on the kinetics of plasma processes. The aim of the present article is threefold: (i) to review recent achievements in our understanding of molecular phenomena in plasmas, (ii) to report on selected studies of the spectroscopic properties and kinetic behaviour of radicals, and (iii) to describe the current status of advanced instrumentation for TDLAS in the mid infrared.
Kinetics of complex plasmas having spherical dust particles with a size distribution
Sodha, M. S. [Disha Institute of Management and Technology, Satya Vihar, Vidhan Sabha-Chandrakhuri Marg, Mandir Hasaud, Raipur, 492101 Chhattisgarh (India); Misra, Shikha; Mishra, S. K. [Department of Education Building, University of Lucknow, Lucknow 226007 (India)
2010-11-15
This paper presents an analysis of the kinetics of an illuminated complex plasma having spherical dust particles with a size distribution. It has been pointed out that in the steady state, the electric potential on the surface of all the particles is the same; as a corollary, all particles carry a charge of the same sign. It is seen that in the steady state, the plasma parameters are determined by the number per unit volume and root mean square radius of the dust particles. This fact makes the analysis similar to that for a complex plasma with dust of uniform size. It is seen that it is essential to consider both the number and energy balance of the constituents of the complex plasma. A parametric analysis, a discussion of the numerical results thus obtained, and conclusions have also been given.
A coarse-grained kinetic equation for neutral particles in turbulent fusion plasmas
Mekkaoui, A.; Marandet, Y.; Genesio, P.; Rosato, J.; Stamm, R.; Capes, H.; Koubiti, M.; Godbert-Mouret, L. [PIIM, CNRS/Aix-Marseille Univ., Marseille F-13397 Cedex 20 (France); Reiter, D.; Boerner, P. [IEK-4 Plasmaphysik, Forschungszentrum Juelich GmbH, TEC Euratom association, D-52425 Juelich (Germany); Catoire, F. [CELIA, UMR5107 CNRS-CEA-Universite de Bordeaux I, Talence F-33405 (France)
2012-06-15
A coarse-grained kinetic equation for neutral particles (atoms, molecules) in magnetized fusion plasmas, valid on time scales large compared to the turbulence correlation time, is presented. This equation includes the effects of plasma density fluctuations, described by gamma statistics, on the transport of neutral particles. These effects have so far been neglected in plasma edge modeling, in spite of the fact that the amplitude of fluctuations can be of order unity. Density fluctuations are shown to have a marked effect on the screening of neutrals and on the spatial localization of the ionization source, in particular at high density. The coarse-grained equations obtained in this work are readily implemented in edge code suites currently used for fusion plasma analysis and future divertor design (ITER, DEMO).
Dimension reduction of non-equilibrium plasma kinetic models using principal component analysis
NASA Astrophysics Data System (ADS)
Peerenboom, Kim; Parente, Alessandro; Kozák, Tomáš; Bogaerts, Annemie; Degrez, Gérard
2015-04-01
The chemical complexity of non-equilibrium plasmas poses a challenge for plasma modeling because of the computational load. This paper presents a dimension reduction method for such chemically complex plasmas based on principal component analysis (PCA). PCA is used to identify a low-dimensional manifold in chemical state space that is described by a small number of parameters: the principal components. Reduction is obtained since continuity equations only need to be solved for these principal components and not for all the species. Application of the presented method to a CO2 plasma model including state-to-state vibrational kinetics of CO2 and CO demonstrates the potential of the PCA method for dimension reduction. A manifold described by only two principal components is able to predict the CO2 to CO conversion at varying ionization degrees very accurately.
3D Kinetic Simulation of Plasma Jet Penetration in Magnetic Field
NASA Astrophysics Data System (ADS)
Galkin, Sergei A.; Bogatu, I. N.; Kim, J. S.
2009-11-01
A high velocity plasmoid penetration through a magnetic barrier is a problem of a great experimental and theoretical interest. Our LSP PIC code 3D fully kinetic numerical simulations of high density (10^16 cm-3) high velocity (30-140 km/sec) plasma jet/bullet, penetrating through the transversal magnetic field, demonstrate three different regimes: reflection by field, penetration by magnetic field expulsion and penetration by magnetic self-polarization. The behavior depends on plasma jet parameters and its composition: hydrogen, carbon (A=12) and C60-fullerene (A=720) plasmas were investigated. The 3D simulation of two plasmoid head-on injections along uniform magnetic field lines is analyzed. Mini rail plasma gun (accelerator) modeling is also presented and discussed.
Spectral evolution of two-dimensional kinetic plasma turbulence in the wavenumber-frequency domain
Comi?el, H.; Institute for Space Sciences, Atomi?tilor 409, P.O. Box MG-23, Bucharest-M?gurele RO-077125 ; Verscharen, D.; Narita, Y.; Motschmann, U.; Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Rutherfordstr. 2, D-12489 Berlin
2013-09-15
We present a method for studying the evolution of plasma turbulence by tracking dispersion relations in the energy spectrum in the wavenumber-frequency domain. We apply hybrid plasma simulations in a simplified two-dimensional geometry to demonstrate our method and its applicability to plasma turbulence in the ion kinetic regime. We identify four dispersion relations: ion-Bernstein waves, oblique whistler waves, oblique Alfvén/ion-cyclotron waves, and a zero-frequency mode. The energy partition and frequency broadening are evaluated for these modes. The method allows us to determine the evolution of decaying plasma turbulence in our restricted geometry and shows that it cascades along the dispersion relations during the early phase with an increasing broadening around the dispersion relations.
Effect of driving frequency on excitation of turbulence in a kinetic plasma
Parashar, T. N.; Shay, M. A.; Matthaeus, W. H.; Servidio, S.; Breech, B.
2011-09-15
The effect of driving frequency on the efficiency of turbulence generation through magnetic forcing is studied using kinetic hybrid simulations with fully kinetic ions and fluid electrons. The efficiency of driving is quantified by examining the energy input into magnetic field as well as the thermal energy for various driving frequencies. The driving is efficient in exciting turbulence and heating the plasma when the time period of the driving is larger than the nonlinear time of the system. For driving at faster time scales, the energy input is weak and the steady state energy is much lower. The heating of the plasma is correlated with intermittent properties of the magnetic field, which are manifested as non-Gaussian statistics. Implications for turbulence in solar corona are discussed.
From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations
NASA Astrophysics Data System (ADS)
Capitelli, M.; Celiberto, R.; Colonna, G.; D'Ammando, G.; De Pascale, O.; Diomede, P.; Esposito, F.; Gorse, C.; Laricchiuta, A.; Longo, S.; Pietanza, L. D.
2010-07-01
Non-equilibrium effects in hydrogen plasmas have been investigated in different systems, ranging from RF plasmas to corona discharges. The existing measurements of vibrational and rotational temperatures, obtained by different spectroscopical techniques, are reported, rationalized by results calculated by kinetic models. Input data of these models are discussed with particular attention on the dependence of relevant cross sections on the vibrational quantum number. Moreover, the influence of the vibrational excitation of H2 molecules on the translational distribution of atoms in ground and excited levels is shown. Finally, a collisional radiative model for atomic hydrogen levels, based on the coupling of the Boltzmann equation for electron energy distribution function (EEDF) and the excited state kinetics, is presented, emphasizing the limits of quasi-stationary approximation. In the last case, large deviations of the EEDF and atomic level distributions from the equilibrium are observed.
NASA Astrophysics Data System (ADS)
Kolobov, Vladimir; Arslanbekov, Robert; Frolova, Anna
2014-12-01
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.
Liu, Y.; Liu, S. Q.; Dai, B.
2011-09-15
Arbitrary amplitude solitary kinetic Alfven waves (KAWs) in a plasma with q-nonextensive electrons are investigated by the conventional Sagdeev pseudopotential method, through which the existence of solitary KAWs is analyzed theoretically and numerically. It is shown only solitons with density hump can exist, the amplitude of which depends sensitively on the parameter q and the plasma {beta}. There is an upper limit for the amplitude of solitary wave which decreases with the increase of q and {beta}. The results obtained in the framework of Maxwellian distribution are reproduced when q {yields} 1.
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.
Wilczek, S; Eremin, D; Brinkmann, R P; Schulze, J; Schuengel, E; Derzsi, A; Korolov, I; Hartmann, P; Donkó, Z; Mussenbrock, T
2015-01-01
The kinetic origin of resonance phenomena in capacitively coupled radio frequency plasmas is discovered based on particle-based numerical simulations. The analysis of the spatio-temporal distributions of plasma parameters such as the densities of hot and cold electrons, as well as the conduction and displacement currents reveals the mechanism of the formation of multiple electron beams during sheath expansion. The interplay between highly energetic beam electrons and low energetic bulk electrons is identified as the physical origin of the excitation of harmonics in the current.
Akatsuka, Hiroshi [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10, O-Okayama, Meguro-ku, Tokyo 152-8550 (Japan)
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.
Effective-Viscosity Approach for Nonlocal Electron Kinetics in Inductively Coupled Plasmas
NASA Astrophysics Data System (ADS)
Hagelaar, G. J. M.
2008-01-01
In inductively coupled plasmas, nonlocal electron kinetics lead to the anomalous skin effect. We show that this can be approximately described through a fluid equation for electron momentum including a viscosity term with an effective-viscosity coefficient. The solution of this momentum equation coupled with the Maxwell equations is in good agreement with results from a particle-in-cell simulation over a wide range of conditions, reproducing the nonmonotonic structure of the anomalous skin with sometimes local negative power absorption.
Glucose Kinetics, Plasma Metabolites, and Endocrine Responses During Experimental Ketosis in Steers1
R. R. Lyle; G. deBoer; S. E. Mills; R. W. Russell; D. C. Beitz; J. W. Young
1984-01-01
Phlorizin and 1,3-butanediol were used to determine effects of glucosuria and ketonemia on concentrations of metabo- lites in blood plasma and on kinetics of glucose metabolism. Four steers received four treatments (control; control plus dietary 1,3-butanediol; control plus phlorizin injections; and control plus phlorizin and 1,3-butanediol) in a Latin square design. Treatments lasted 14 days. All steers received a 30%
Kinetic modeling of a one-dimensional, bounded plasma in the ambipolar regime
Monojoy Goswami; H. Ramachandran
2000-01-01
In this paper we present a self-consistent kinetic simulation of a diffusion dominated bulk plasma region. Collisions have been modeled by a velocity-dependent Krook collision operator. The technique is capable of handling large systems-the results presented here are for systems 100lambdamfp in extent-yet retains the details of the edge physics present. The distribution functions for the trapped and the transiting
Extent of validity of the hydrodynamic description of ions in dense plasmas
Mithen, James P.; Gregori, Gianluca [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Daligault, Jerome [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2011-01-15
We show that the hydrodynamic description can be applied to modeling the ionic response in dense plasmas for a wide range of length scales that are experimentally accessible. Using numerical simulations for the Yukawa model, we find that the maximum wave number k{sub max} at which the hydrodynamic description applies is independent of the coupling strength, given by k{sub max}{lambda}s{approx_equal}0.43, where {lambda}{sub s} is the ionic screening length. Our results show that the hydrodynamic description can be used for interpreting x-ray scattering data from fourth generation light sources and high power lasers. In addition, our investigation sheds new light on how the domain of validity of the hydrodynamic description depends on both the microscopic properties and the thermodynamic state of fluids in general.
A new dynamic fluid-kinetic model for plasma transport within the plasmaspheric plume
NASA Astrophysics Data System (ADS)
Wang, Y.; Tu, J.; Song, P.
2011-12-01
A new dynamic fluid-kinetic (DyFk) model is proposed and developed for investigating the plasma transport from the plasmasphere to the dayside magnetopause through the plasmaspheric plume. This model treats a closed flux tube in a local sense, in contrast to the global sense. The flux tube is allowed to move both radially from near the Earth to the magnetopause, which may result in expansion in its volume, and azimuthally around the Earth. Plasma may flow along the flux tube. The numerical simulation model couples a truncated version of the field line interhemispheric plasma (FLIP) model at altitudes below 800 km and a generalized semi-kinetic (GSK) model above it with an overlapped boundary region in each of the hemispheres. A self-consistently treatment of the ionospheric losses and production with possible heat sinks couples to a kinetic treatment of the multiple ion species (O+/ H+/ He+) and electrons in the plasmasphere. This model includes the effects of the convection of the plasmaspheric flux tube, parallel electric field, magnetic mirror force, centrifugal force, changing ionospheric conditions, Coulomb and ion-neutral collisions, and anisotropic temperatures, as well as the wave-particle interaction. The preliminary simulation results of the multi-species ion transport within a plasmaspheric plume will be presented.
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 [Los Alamos National Laboratory; Abdallah, Joseph [Los Alamos National Laboratory; Fontes, Christopher [Los Alamos National Laboratory; Zhang, Honglin [Los Alamos National Laboratory
2010-12-10
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.
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.
Valter Pohjola; Esa Kallio
2010-01-01
We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up on an earlier quasi-neutral hybrid simulation platform called
Self-consistent multidimensional electron kinetic model for inductively coupled plasma sources
NASA Astrophysics Data System (ADS)
Dai, Fa Foster
Inductively coupled plasma (ICP) sources have received increasing interest in microelectronics fabrication and lighting industry. In 2-D configuration space (r, z) and 2-D velocity domain (??,?z), a self- consistent electron kinetic analytic model is developed for various ICP sources. The electromagnetic (EM) model is established based on modal analysis, while the kinetic analysis gives the perturbed Maxwellian distribution of electrons by solving Boltzmann-Vlasov equation. The self- consistent algorithm combines the EM model and the kinetic analysis by updating their results consistently until the solution converges. The closed-form solutions in the analytical model provide rigorous and fast computing for the EM fields and the electron kinetic behavior. The kinetic analysis shows that the RF energy in an ICP source is extracted by a collisionless dissipation mechanism, if the electron thermovelocity is close to the RF phase velocities. A criterion for collisionless damping is thus given based on the analytic solutions. To achieve uniformly distributed plasma for plasma processing, we propose a novel discharge structure with both planar and vertical coil excitations. The theoretical results demonstrate improved uniformity for the excited azimuthal E-field in the chamber. Non-monotonic spatial decay in electric field and space current distributions was recently observed in weakly- collisional plasmas. The anomalous skin effect is found to be responsible for this phenomenon. The proposed model successfully models the non-monotonic spatial decay effect and achieves good agreements with the measurements for different applied RF powers. The proposed analytical model is compared with other theoretical models and different experimental measurements. The developed model is also applied to two kinds of ICP discharges used for electrodeless light sources. One structure uses a vertical internal coil antenna to excite plasmas and another has a metal shield to prevent the electromagnetic radiation. The theoretical results delivered by the proposed model agree quite well with the experimental measurements in many aspects. Therefore, the proposed self-consistent model provides an efficient and reliable means for designing ICP sources in various applications such as VLSI fabrication and electrodeless light sources.
Large scale kinetic modeling of magnetospheric plasma. Ph.D. Thesis
Perooomian, V.
1994-12-31
In this dissertation, the author investigates the population of the magnetosphere, how magnetospheric plasma is accelerated as it is transported from various source regions, and the mechanisms of plasma loss that results from the plasma acceleration. In the low latitude boundary layer, the author shows that a mixture of plasma from the magnetosphere and magnetosheath populates the region. Unstable features in the electron distribution function generate waves that may effect particle dynamics there. Using the plasma mantle as an ion source in a large scale kinetic model, the author populates the distant magnetotail and shows that quasi-adiabatic acceleration of ions energizes the plasma to keV energies. Ions convection earthward from the magnetotail encounter the transitional `wall` region and are deflected duskward, are quickly energized and then lost to the flanks. Nearer Earth, the author uses an auroral ionospheric source to populate the quiet-time ring current. The author shows that ions from this source could adequately supply plasma to the region. Densities and pressures obtained from these calculations are in good agreement with observations. One of the consequences of distant-tail quasi-adiabatic acceleration is that ions that are scattered during their interaction with the magnetotail make up the central plasma sheet, while ions ejected field-aligned from the neutral plane comprise the plasma sheet boundary layer beams and can be seen to precipitate in the auroral zone as velocity dispersed ion structures (VDIS). The author shows that VDIS are most likely formed by ions from the plasma mantle; they form with the magnetic field configurations assumed here. A 3D study of VDIS showed that these structures can form over a wide range of local times in the nightside auroral zone.
Kinetic Alfven waves as a source of plasma transport at the dayside magnetopause
NASA Technical Reports Server (NTRS)
Lee, L. C.; Johnson, Jay R.; Ma, Z. W.
1994-01-01
As the shocked solar wind with variable plasma density and magnetic field impinges on the dayside magnetopause, it is likely to generate large-scale Alfven waves at the solar wind magnetosphere interface. However, large gradients in the density and magnetic field at the magnetopause boundary effectively couple large-scale Alfven waves with kinetic Alfven waves may play an important role in plasma transport at the dayside magnetopause and in electron acceleration along field lines. The transport can occur because, unlike the magnetohydrodynamic (MHD) shear Alfven wave, the kinetic Alfven wave has an associated parallel electric field which breaks down the 'frozen-in' condition and decouples the plasma from field lines. We calculate the average deviation of the plasma from the field line from which we estimate the diffusion coefficient associated with these 'bundles' of lead to acceleration of electrons along field lines in the magnetopause boundary and may possibly provide an explanation for observed counterstreaming electron beams characterized by energies of 50-200 eV.
NASA Astrophysics Data System (ADS)
Bowman, Sherrie S.
This dissertation presents novel results in the study of nanosecond pulsed, non-equilibrium plasmas. Specifically, an in-depth experimental study of the role of atomic oxygen on the kinetic mechanisms involved in three distinct discharge geometries was conducted. First, a low temperature (˜300 K) and low pressure (<100 Torr) pulsed plasma in a plane-to-plane dielectric barrier discharge was studied using a high repetition rate (40 kHz) high voltage pulsed discharge. Second, a higher temperature (˜1000 K) and low pressure (<100 Torr) pulsed plasma in a bare metal, spherical electrode geometry was studied using a 60 Hz repetition rate high voltage pulsed discharge. Third, a high temperature (˜1200 K) and high pressure (˜760 Torr) pulsed plasma in a pin-to-plane geometry was studied using a 10 Hz repetition rate high voltage pulsed discharge. Additionally, a study of the role of electronically excited molecular oxygen, a1Deltag, on the kinetics of a low temperature (˜300 K) and low pressure (<100 Torr) nonequilibrium plasma in a plane-to-plane dielectric barrier discharge was conducted. Kinetic modeling results were compared to all the experimental results. UV ICCD camera imaging was used to confirm the stable and diffuse nature of the plasma under all of the conditions that were studied. Current and voltage traces were measured using commercially available probes to determine the energy coupled to the plasma. All of these results were used for modeling of experimental results. Two photon Absorption Laser Induced Fluorescence (TALIF) measurements were used for determining atomic oxygen concentration. Calibration by comparison with xenon gas gave absolute O atom concentration in a variety of gas mixtures and discharge geometries. IR emission spectroscopy was used for electronically excited molecular oxygen, a1Delta g, measurements. Calibration by comparison with a blackbody source was used for absolute scale results. The effect of a1Delta g on ignition delay time was measured spontaneous OH A?X(0,0) emission spectroscopy was used. Ignition delay was defined as the onset of continuous OH emission between discharge pulses. It was found that while, in general, the mechanism for atomic oxygen formation and decay in each of the plasmas studied can be compared there are significant differences in quantitative values in each case. Initial conditions, such as the coupled energy and number density of electrons, play a strong role in determining how the chemistry propagates in time. The role of a 1Deltag was found to be complicated by concurrent NO x chemistry happening in the discharge and significantly higher concentrations would be needed to differentiate these effects.
A kinetic study of the source-collector sheath system in a drifting plasma
NASA Astrophysics Data System (ADS)
Rizopoulou, N.; Robinson, A. P. L.; Coppins, M.; Bacharis, M.
2013-06-01
The source-collector sheath system describes a plasma that forms between a Maxwellian source and an absorbing wall. The plasma is assumed to be collisionless and without ionization. Two distinct areas are being formed: the collector sheath, an ion-rich region in contact with the absorbing boundary, and the source sheath, which is an electron-rich area near the Maxwellian source. Our work examines the effect that shifted Maxwellian distributions at the plasma source have on the characteristics of such a system. This is studied for a range of drift velocities and ratios of ion and electron temperatures. We study the problem both analytically and using our kinetic Vlasov code, Yggdrasil. The simulation results are in very good agreement with the predictions of our theoretical model.
Spatially autoresonant stimulated Raman scattering in inhomogeneous plasmas in the kinetic regime
Chapman, T.; Hueller, S.; Pesme, D. [Centre de Physique Theorique, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Masson-Laborde, P. E. [CEA, DAM, DIF, F-91297 Arpajon (France); Rozmus, W. [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada)
2010-12-15
The impact of spatial autoresonance on backward stimulated Raman scattering in inhomogeneous plasmas is investigated in the regime where the dominant nonlinear frequency shift of the Langmuir wave is due to kinetic effects. By numerically solving the coupled mode equations, the spatial growth of the Langmuir wave is observed to self-adjust so as to cancel the detuning from resonance due to inhomogeneity, giving rise to phase-locked solutions to the electron plasma wave equation. For a single resonant point in a linear density profile, the envelope of the electron plasma wave is characterized by a growth that begins at the resonant point and is proportional to the square of distance propagated. In the more physical case where the scattered light is seeded with a broadband noise, autoresonance may lead to a reflectivity well above the level predicted by the usual Rosenbluth gain factor [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)].
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).
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.
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V. [Univ. of California, Berkeley, CA (United States). Applied Science and Technology Program; Colella, P. [Lawrence Berkeley National Lab., CA (United States). Computational Research Div.; Univ. of California, Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Science; Shumlak, U. [Univ. of Washington, Seattle, WA (United States). Aerospace and Energetic Research Program
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.
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.
Kinetics of ion and prompt electron emission from laser-produced plasma
NASA Astrophysics Data System (ADS)
Farid, N.; Harilal, S. S.; Ding, H.; Hassanein, A.
2013-07-01
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.
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.
A Hamiltonian fluid-kinetic model for a two-species non-neutral plasma
Tassi, E.; Chandre, C. [Aix-Marseille Université, Université de Toulon, CNRS CPT UMR 7332, 13288 Marseille (France)] [Aix-Marseille Université, Université de Toulon, CNRS CPT UMR 7332, 13288 Marseille (France); Romé, M. [INFN Sezione di Milano and Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, I-20133 Milano (Italy)] [INFN Sezione di Milano and Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, I-20133 Milano (Italy)
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.
Kinetic effects on Lunar plasma environment on global scale, mesoscale and microscale
NASA Astrophysics Data System (ADS)
Kallio, E.; Dyadechkin, S.; Jarvinen, R.; Wurz, P.; Barabash, S.; Rantala, A.; Alho, M.
2012-12-01
Recent Lunar missions have shown that the solar wind interaction with the Moon is complex and scientifically more interesting than anticipated before, as shown by new in situ plasma, neutral atom and magnetic field observations. Especially, an unexpectedly high fraction of the incident solar wind protons is reflected from the surface, and even larger fraction by the Lunar magnetic anomalies. This effect has been observed both by measuring deviated solar wind flow near the magnetic anomalies and by observing decreased flux of energetic neutral hydrogen atoms, ENAs, from the surface region of strong magnetic anomalies. These "macro scale" processes affect the properties of plasma near the Lunar surface. Consequently, also physical processes at "micro scales" within the Debye sheath layer, where the electric potential of the surface and near surface region are controlled by photoelectrons and solar wind particles, are affected. In this work we introduce two numerical kinetic simulation models developed to study the solar wind interaction with the Moon: (1) a hybrid model (HYB-Moon) to study macro scale processes and (2) a full kinetic PIC model to study micro scale processes. Both models are part of the HYB planetary plasma modelling platform developed at the Finnish Meteorological Institute. In the hybrid model ions are modelled as particles while electrons form a charge neutralizing massless fluid. In the Particle-in-cell (PIC) simulation both ions and electrons are modelled as particles. In the presentation we show results based on these models. A schematic illustration of plasmas and fields which affect the lunar dust-plasma environment near the lunar surface: photoelectrons (e-hf), solar wind electrons (e-sw) and ions (H+sw), dust electrons (e-dust), dust particles (q dust), electric field (E) and magnetic field. Because of the non-zero magnetic field associated with the interplanetary magnetic field (Bsw), electric currents in the plasma and the lunar magnetic anomalies, the charged particle follow gyromotion around the magnetic field. The electric field contains the convective electric field of the solar wind (Esw) and the electric field associated with the charge separation within the potential sheath and possible also within magnetic anomalies. The length scale of the potential sheath is the Debye length (lamda D). See Kallio et al., "Kinetic effects on Lunar plasma environment on global scale, mesoscale and microscale" (PSS, 2012, submitted) for details.
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.
Evolution of large amplitude Alfven waves in solar wind plasmas: Kinetic-fluid models
NASA Astrophysics Data System (ADS)
Nariyuki, Y.
2014-12-01
Large amplitude Alfven waves are ubiquitously observed in solar wind plasmas. Mjolhus(JPP, 1976) and Mio et al(JPSJ, 1976) found that nonlinear evolution of the uni-directional, parallel propagating Alfven waves can be described by the derivative nonlinear Schrodinger equation (DNLS). Later, the multi-dimensional extension (Mjolhus and Wyller, JPP, 1988; Passot and Sulem, POP, 1993; Gazol et al, POP, 1999) and ion kinetic modification (Mjolhus and Wyller, JPP, 1988; Spangler, POP, 1989; Medvedev and Diamond, POP, 1996; Nariyuki et al, POP, 2013) of DNLS have been reported. Recently, Nariyuki derived multi-dimensional DNLS from an expanding box model of the Hall-MHD system (Nariyuki, submitted). The set of equations including the nonlinear evolution of compressional wave modes (TDNLS) was derived by Hada(GRL, 1993). DNLS can be derived from TDNLS by rescaling of the variables (Mjolhus, Phys. Scr., 2006). Nariyuki and Hada(JPSJ, 2007) derived a kinetically modified TDNLS by using a simple Landau closure (Hammet and Perkins, PRL, 1990; Medvedev and Diamond, POP, 1996). In the present study, we revisit the ion kinetic modification of multi-dimensional TDNLS through more rigorous derivations, which is consistent with the past kinetic modification of DNLS. Although the original TDNLS was derived in the multi-dimensional form, the evolution of waves with finite propagation angles in TDNLS has not been paid much attention. Applicability of the resultant models to solar wind turbulence is discussed.
NASA Astrophysics Data System (ADS)
Kallio, Esa; Jarvinen, Riku; Dyadechkin, Sergey; Wurz, Peter; Barabash, Stas; Alvarez, Francisco; Fernandes, Vera A.; Futaana, Yoshifumi; Harri, Ari-Matti; Heilimo, Jyri; Lue, Charles; Mäkelä, Jakke; Porjo, Niko; Schmidt, Walter; Siili, Tero
2012-12-01
The recent in situ particle measurements near the Moon by Chandrayaan-1 and Kaguya missions as well as the earlier observation by the Lunar Prospector have shown that the Moon-solar wind interaction is more complicated than believed earlier. The new observations have arisen the need for a detailed modelling of the near surface plasma-surface processes and regions near the lunar magnetic anomalies. Especially, interpretation of ion, electron, and energetic neutral atoms (ENA) observations have shown that the plasma cannot be treated as a single fluid but that kinetic effects have to be taken into account. We have studied the kinetic effects and, especially, the role of finite gyro-radius effects at the Moon by kinetic plasma simulations at three different length-scales which exist in the Moon-solar wind interaction. The solar wind interaction with a magnetic dipole, which mimics the lunar magnetic anomalies in this study, is investigated by a 3D self-consistent hybrid model (HYB-Moon) where protons are particles and electrons form a charge neutralizing mass less fluid. This study shows that the particle flux and density and the bulk velocity of the solar wind protons that hit the lunar surface just above the dipole are decreased compared to their undisturbed values. In addition, a particle "halo" region was identified in the simulation, a region around the dipole where the proton density and the particle flux are higher than in the solar wind, qualitatively in agreement with energetic hydrogen atom observations made by the Chandrayaan-1 mission. The near surface plasma within the magnetic anomaly within a Debye sheath is studied by an electromagnetic Particle-in-Cell, PIC, simulation (HYB-es). In the PIC simulation both ions and electrons are treated as particles. Further, we assume in the PIC simulation that the magnetic anomaly blocks away all solar wind particles and the simulation contains only photo-electrons. The analysis shows that the increased magnetic field decreases the strength of the electric potential and results in a thinner potential sheath than without the magnetic field. Overall, the simulations give support for the suggestions that kinetic effects play an important role on the properties of the lunar plasma environment.
Nonlinear interaction and parametric instability of kinetic Alfven waves in multicomponent plasmas
Zhao, J. S.; Yang, L. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Lu, J. Y. [College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); National Center for Space Weather, China Meteorology Administration, Beijing 100081 (China)
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 modeling of a one-dimensional, bounded plasma in the ambipolar regime
NASA Astrophysics Data System (ADS)
Goswami, Monojoy; Ramachandran, H.
2000-12-01
In this paper we present a self-consistent kinetic simulation of a diffusion dominated bulk plasma region. Collisions have been modeled by a velocity-dependent Krook collision operator. The technique is capable of handling large systems—the results presented here are for systems 100?mfp in extent—yet retains the details of the edge physics present. The distribution functions for the trapped and the transiting orbits and their moments are obtained. The density and potential profiles inside the bulk shows overall agreement with ambipolar predictions. The kinetic equivalent of DA is obtained and compared to the fluid prediction. The validity of the code and the observed deviations from fluid treatments are discussed.
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...
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)
Hu, Liangbin; Liu, Youliang; Cao, Xijin
2007-07-01
We propose a unified semiclassical description for the kinetic magnetoelectric effect in both k-linear and k-cubic two-dimensional Rashba model in the thermodynamic limit, which takes into account the effects of both spin coherence and spin dephasing by a closed set of Boltzman-like kinetic equations. Based on this unified description, we show that in contrary to the case found in the studies of intrinsic spin Hall effect in such systems, in the linear response regime the kinetic magnetoelectric effect would vanish for the k-cubic Rashba model in the thermodynamic limit but be robust for the k-linear Rashba model in the thermodynamic limit.
Zonca, Fulvio
Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas Z. Qiu, L. Chen modes by drift waves in nonuniform plasmas Z. Qiu,1 L. Chen,1,2 and F. Zonca1,3 1 Inst. Fusion Theory
Kinetic Alfven wave instability driven by a field-aligned current in high-{beta} plasmas
Chen, L.; Wu, D. J.; Hua, Y. P. [Purple Mountain Observatory, CAS, Nanjing 210008, China and Graduate School, CAS, Beijing 100012 (China); Purple Mountain Observatory, CAS, Nanjing 210008 (China); Purple Mountain Observatory, CAS, Nanjing 210008, China and Graduate School, CAS, Beijing 100012 (China)
2011-10-15
Including the ion-gyroradius effect, a general low-frequency kinetic dispersion equation is presented, which simultaneously takes account of a field-aligned current and temperature anisotropy in plasmas. Based on this dispersion equation, kinetic Alfven wave (KAW) instability driven by the field-aligned current, which is carried by the field-aligned drift of electrons relative to ions at a drift velocity V{sub D}, is investigated in a high-{beta} plasma, where {beta} is the kinetic-to-magnetic pressure ratio in the plasma. The numerical results show that the KAW instability driven by the field-aligned current has a nonzero growth rate in the parallel wave-number range 0
Integrated Plasma-Surface Kinetics Model to Predict Deposition Rates in an HDP-CVD Reactor
NASA Astrophysics Data System (ADS)
Bhoj, Ananth; Kothnur, Prashanth; Kinder, Ron
2008-10-01
A comprehensive model for HDP-CVD reactors used in semiconductor processing, such as the Novellus SPEED, remains challenging due to the complex coupling of plasma transport, gas-phase and surface chemical reaction pathways in the chamber. The Hybrid Plasma Equipment Model (HPEM) is employed here to predict deposition rates at the wafer. The HPEM has a Surface Kinetics Module (SKM) that accepts species fluxes from the plasma, computes deposition/etch rates and coverage of various surface resident species and modifies sticking coefficients of plasma species based on their surface reactivity. Discharges in Ar/O2/SiH4 generated at a few mTorr and 2 -- 6 kW power deposition in a dome-shaped 200-mm chamber are considered. The gas-phase and surface reaction mechanisms build on those used by Meeks et al [1] for their well-mixed reactor model. The effect of varying power, pressure and wafer temperature on plasma characteristics and the ensuing effects on deposition rates and surface coverage of species at the wafer will be discussed. [1] E. Meeks, R. S. Larson, P. Ho, C. Apblett, S. M. Han, E. Edelberg, E. S. Aydil, J. Vac. Sci. Technol. A, 16(2), 544 (1998).
Ion beam generation at the plasma sheet boundary layer by kinetic Alfven waves
Moghaddam-Taaheri, E.; Goertz, C.K.; Smith, R.A. (Univ. of Iowa, Iowa City (USA))
1989-08-01
The kinetic Alfven wave, an Alfven wave with a perpendicular wavelength comparable to the ion gyroradius, can diffuse ions both in velocity and coordinate spaces with comparable transport rates. This may lead to the generation of ion beams in the plasma sheet boundary layer (PSBL). To investigate the ion beam generation process numerically, a two-dimensional quasi-linear code was constructed. Assuming that the plasma {beta} (the ratio of plasma pressure to the magnetic pressure) varies from {beta} = 1 to {beta} << 1 across the magnetic field, the dynamics of the ion beam generation in the PSBL was studied. It was found that if your start with an ion distribution function which monotonically decreases with velocity along the magnetic field and a density gradient across the magnetic field, ions diffuse in velocity-coordinate space until nearly a plateau is established along the diffusion path. Depending on the topology of the magnetic field at the lobe side of the simulation system, i.e., open or closed field lines, the ion distribution function may or may not reach a steady state. If the field lines are open there, i.e., if the diffusion extends into the lobe, the double diffusion process may provide a mechanism for continuously transferring the ions from the central plasma sheet to the lobe. The authors comment on the effect of the particle loss on the establishment of the pressure balance in the plasma sheet.
Finite-Larmor-radius kinetic theory of a magnetized plasma in the macroscopic flow reference frame
Ramos, J. J.
2008-08-15
A straightforward operator method is used to derive a form of the drift-kinetic equation for a collisionless plasma species in the moving reference frame of its macroscopic flow. This equation is valid for sonic time scales and flow velocities, with first-order finite-Larmor-radius effects included. It applies rigorously to far-from-Maxwellian distribution functions and to general space and time variations of the magnetic field. Its velocity moments are shown to reproduce exactly the corresponding fluid equations obtained from moments of the full Vlasov equation.
Nikiforova, A.A.; Alksnis, E.G.; Ivanova, E.M.
1985-07-01
The aim of this investigation was to study some kinetic properties of lecithin-cholesterol acyltransferase (LCAT) in the blood plasma of patients with hyper-alpha-lipoproteinemia, enabling the presence of LCAT isozymes in the blood to be detected. The velocity of the LCAT reaction was judged by determining labeled CHE formed from /sup 14/C-nonesterified CH and lecithin of HDL on incubation of the latter with the enzyme. Dependence of the velocity of the LCAT reaction on concentration of substrate (nonesterified HDL cholesterol) in four subjects with hyper-alpha-lipoproteinemia is shown.
Two-Dimensional Self-Consistent Kinetic Model for Solenoidal Inductively Coupled Plasma
NASA Astrophysics Data System (ADS)
Mao, Ming; Dai, Zhongling; Wang, Younian
2007-02-01
A two-dimensional self-consistent kinetic model was developed to study the influence of the various factors on the electron energy distribution function. These factors include gas pressure, the driving frequency, the radius and length of the inductively coupled plasma equipment, the amplitude of the radio-frequency coil current, and the number of turns of rf coils. The spatial profiles of the rf electric field and power density have also been calculated under the same parameters. Numerical results show that the electron energy distribution functions are significantly modified and the spatial profiles of the rf electric field and rf power density are also demonstrated.
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.
Pateau, Amand [Institut des Matériaux Jean Rouxel, Université de Nantes, 2 rue de la Houssiniére 44322 Nantes, France and ST Microelectronics, 10 rue Thals de Milet, 37071 Tours (France); Rhallabi, Ahmed, E-mail: ahmed.rhallabi@univ-nantes.fr; Fernandez, Marie-Claude [Institut des Matériaux Jean Rouxel, Université de Nantes, 2 rue de la Houssiniére 44322 Nantes (France); Boufnichel, Mohamed; Roqueta, Fabrice [ST Microelectronics, 10 rue Thales de Milet, 37071 Tours (France)
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}.
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...
NASA Astrophysics Data System (ADS)
Khorashadizadeh, S. M.; Rastbood, E.; Niknam, A. R.
2015-07-01
The evolution of filamentation instability in a weakly ionized current-carrying plasma with nonextensive distribution was studied in the diffusion frequency region, taking into account the effects of electron-neutral collisions. Using the kinetic theory, Lorentz transformation formulas, and Bhatnagar-Gross-Krook collision model, the generalized dielectric permittivity functions of this plasma system were achieved. By obtaining the dispersion relation of low-frequency waves, the possibility of filamentation instability and its growth rate were investigated. It was shown that collisions can increase the maximum growth rate of instability. The analysis of temporal evolution of filamentation instability revealed that the growth rate of instability increased by increasing the q-parameter and electron drift velocity. Finally, the results of Maxwellian and q-nonextensive velocity distributions were compared and discussed.
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.
EXB-Drift, Current, and Kinetic Effects on Divertor Plasma Profiles During ELMs
Rognlien, T.D.; Shimada, M.
2002-05-23
The transient heat load on divertor surfaces from Edge-Localized Modes (ELMs) in tokamaks can be very large and thus of concern for a large device such as ITER. Models for kinetic modifications to fluid models are discussed that should allow them to reasonably describe the long mean-free path regime encountered owing to the high electron and ion temperatures in the SOL during large ELMs. A set of two-dimensional (2D) simulations of the dynamic response of the scrape-off layer (SOL) plasma to an ELM is presented. The role of plasma currents and E x B motion is emphasized, which cause large changes in the response compared to models neglecting them.
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.
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.
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)
Kinetic theory of ion collection by probing objects in flowing strongly magnetized plasmas
Chung, K.; Hutchinson, I.H.
1988-11-01
A new one-dimensional collisionless kinetic model is developed for the flow of ions to probing structures in drifting plasmas. The cross-field flow into the presheath is modeled by accounting consistently for particle exchange between the collection flux tube and the outer plasma. Numerical solutions of the self-consistent plasma-sheath equations are obtained with arbitrary external ion temperature and parallel plasma flow velocity. Results are presented of the spatial dependence of the ion distribution function as well as its moments (density, particle flux, temperature, and power flux). The ion current to the probe is obtained and the ratio of the upstream to downstream currents is found to be well represented by the form R = exp(Ku/sub d/), where Kapprox.1.7 and u/sub d/ is the drift velocity in units of ..sqrt..(T/sub e//m/sub i/) . The results are in good agreement with comparable recent fluid calculations but show substantial deviations from other models which ignore particle exchange out of the presheath. No evidence is found of the formation of shocks in the downstream wake, contrary to the implications of some fluid theories.
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.
A new dynamic fluid-kinetic model for plasma transport in the plasmasphere
NASA Astrophysics Data System (ADS)
Wang, Y.; Tu, J.; Song, P.
2014-12-01
A new dynamic fluid-kinetic (DyFK) model is developed for investigating the plasma transport along a closed flux tube in the plasmasphere by coupling a truncated version of the field line interhemispheric plasma (FLIP) model at altitudes below 800 km and a generalized semi-kinetic (GSK) model above it with an overlapped boundary region (800 km-1100 km) in both hemispheres. The flux tube is allowed to move both radially away from the Earth and azimuthally around the Earth. Ion species O+ and He+ are for the first time treated as simulation particles in a numerical model for the plasmasphere. The simulation particles are subjected to the parallel electric field, magnetic mirror force, gravity, centrifugal force and Coulomb collisions, as well as possible wave-particle interaction. The effects of ionosphere-plasmasphere coupling on the day-night evolution of the plasmasphere and the relative abundance of O+ and He+ are studied. Simulations are also conducted to investigate the influence of wave-particle interaction on the field-aligned density distributions of ions (O+/ H+/ He+) and their velocity distributions.
Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method
NASA Astrophysics Data System (ADS)
Taitano, William; Knoll, Dana; Chacon, Luis
2009-11-01
The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as linearly implicit methods or one-step Newton methods. However, issues related to time accuracy of these methods still remain. We are pursuing a route to implicit plasma kinetic simulation which eliminates extrapolation, eliminates phase-space from the linear algebra problem, and converges the entire nonlinear system within a time step. We accomplish all this using the Jacobian-Free Newton-Krylov algorithm. The original research along these lines considered particle methods to advance the distribution function [1]. In the current research we are advancing the Vlasov equations on a grid. Results will be presented which highlight algorithmic details for single species electrostatic problems and coupled ion-electron electrostatic problems. [4pt] [1] H. J. Kim, L. Chac'on, G. Lapenta, ``Fully implicit particle in cell algorithm,'' 47th Annual Meeting of the Division of Plasma Physics, Oct. 24-28, 2005, Denver, CO
Ng, Chung-Sang
PHYS 626 -- Fundamentals of Plasma Physics -- Sections 3.1 - 3.2 1. The description of a plasma using single particle motions is the most simplistic theory one can think of. 2. The two basic of particles; (ii) the motion of a single charged particle is not affected by the motions of other particles (i
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.
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 Astrophysics Data System (ADS)
Wang, Z. R.
2014-10-01
Through theory and simulation of drift kinetic effects, modeling with the MARS-K code has for the first time explained the linear plasma response to 3D fields in the vicinity of the ``no-wall'' ideal beta limit. A longstanding issue in understanding resonant field amplification (RFA) of plasma to 3D fields is that the ideal magnetohydrodynamics (MHD) theory predicts an unlimited amplification near the no-wall stability limit. However, in many experiments such as DIID-D and NSTX, the plasma response increases almost monotonically along with the plasma beta across the ideally predicted no-wall limit. This disagreement is now explained by perturbed drift kinetic theory and associated with distorted particle orbits by 3D fields. The upgraded MARS-K code, which has the capability to solve linearized hybrid MHD equations with drift kinetic effects self-consistently, is applied to study the DIII-D RFA experiments through the quantitative comparison. It reveals the kinetic effect due to thermal particles plays a major role in modifying the response structure throughout plasma and keeps the finite amplification of response, as the experimental measurements, around the no-wall beta limit. The perturbed energy analysis shows the modification of plasma response is mainly contributed by the precession, bounce and transit resonances of thermal ions. The kinetic effect of isotropic energetic particles with slowing down distribution can further slightly change the plasma response without significant contribution. RFA experiments in NSTX plasmas are also analyzed to affirm the role of drift kinetic effect on modifying the plasma response. This study shows good agreements between theoretical results and various RFA experimental measurements, providing the possible physics explanation of RFA phenomena observed in many tokamaks. The results also indicate the validity of self-consistent calculation of hybrid drift kinetic-MHD model with drift kinetic effect in high beta tokamaks. Supported by the US DOE under DE-AC02-09CH11466 & DE-FC02-04ER54698.
Herbert H. Sawin; Bai Bo; Guo Wei
2009-01-01
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,
V. Pohjola; E. Kallio
2010-01-01
We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up on an earlier quasi-neutral hybrid simulation platform called
MHD and Kinetic Models for the Interchange Mode in a Confined Plasma.
NASA Astrophysics Data System (ADS)
Vandegrift, Guy George
The curvature driven interchange mode is studied. If the mode is in the pure flute regime (k(,z) = 0), then the ideal MHD equations are equivalent to an L-R-C circuit with the resistor representing linetying. The capacitance (ion polarization drift) and the inductance (curvature drift) are obtained from the plasma density, pressure, and magnetic field profiles. At large beta, a conducting wall close to the plasma enhances the stability of the lowest order (displacement) mode by constraining the perturbed magnetic field. The wall also produces a stabilizing finite ion Larmor radius effect on the displacement mode by imposing a structure on the perturbed electric field. Ion-ion collisions or turbulence can strongly affect the mode even when the inverse radial confinement time is much less than the mode frequency. The unperturbed radial electric field changes the dispersion relation of the interchange mode. The combination of a radial electric field and linetying gives a real (oscillatory) part of the frequency. A z dependent radial electric field produces an electrostatic finite-k(,z) effect. Resonant effects between the wave and the azimuthal curvature drift are not normally important but may be important for a tandem mirror reactor if the central cell is very long and the endplug is very short. A calculation of parallel kinetic effects indicates that the ideal MHD ballooning mode equation is not valid for a collisionless plasma. Experiments were performed to verify several aspects of the theory. The Q of the L-R-C circuit was measured on the three-meter multiple mirror (Marshall gun source) and compared with theory. An anomalous capacitance was observed at the sheath of the ten-meter multiple mirror that could be due to a presheath that accelerates ions out of the plasma. A dispersion relation applicable to the axisymmetric mirror (Ba plasma) at UC Irvine is derived and compared with experiment.
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.
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.
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.
New fully kinetic model for the study of electric potential, plasma, and dust above lunar landscapes
NASA Astrophysics Data System (ADS)
Dyadechkin, S.; Kallio, E.; Wurz, P.
2015-03-01
We have developed a new fully kinetic electrostatic simulation, HYBes, to study how the lunar landscape affects the electric potential and plasma distributions near the surface and the properties of lifted dust. The model embodies new techniques that can be used in various types of physical environments and situations. We demonstrate the applicability of the new model in a situation involving three charged particle species, which are solar wind electrons and protons, and lunar photoelectrons. Properties of dust are studied with test particle simulations by using the electric fields derived from the HYBes model. Simulations show the high importance of the plasma and the electric potential near the surface. For comparison, the electric potential gradients near the landscapes with feature sizes of the order of the Debye length are much larger than those near a flat surface at different solar zenith angles. Furthermore, dust test particle simulations indicate that the landscape relief influences the dust location over the surface. The study suggests that the local landscape has to be taken into account when the distributions of plasma and dust above lunar surface are studied. The HYBes model can be applied not only at the Moon but also on a wide range of airless planetary objects such as Mercury, other planetary moons, asteroids, and nonactive comets.
Kinetic modeling of plasma-limiter interaction in the TEXTOR edge region
Harris, J.A.; McGrath, R.T.
1985-05-01
The plasma flow properties along a field line intercepting a limiter or other neutralizing surface are significantly altered through charge exchange and reionization of neutrals produced at the surface. This problem is investigated using a one-dimensional, steady state kinetic model. The collisional Boltzmann equation is solved for the ion, electron, and neutral particle distribution functions in one velocity variable as a function of distance from the neutralizing surface. The collisional operator in the Boltzmann equation includes the effects of charged particle collisions and calculates charge exchange and electron impact ionization rates through direct integration of the distribution functions. Results have been obtained for plasma conditions simulating those observed for ALT-I operation on TEXTOR. Spatial profiles of particle density, temperature, and presheath electric field strength on flux surfaces at various distances into the scrape-off are calculated. We find that neutral recycle reduces ion temperatures by as much as 30% as the plasma flows toward the neutralizing surface while electron temperatures remain unchanged. Collisional sources generate small presheath electric fields directed away from the limiter surface that have integrated potentials of only a few volts.
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
Theoretical Modeling of Radiation-driven Atomic Kinetics of a Neon Photoionized Plasma
NASA Astrophysics Data System (ADS)
Durmaz, Tunay
We report on a theoretical study on atomic kinetics modeling of a photoionized neon plasma at conditions relevant to laboratory experiments performed at the Z-machine in Sandia National Laboratories. We describe an atomic kinetics model and code, ATOKIN, that was developed and used to compute the atomic level population distribution. The study includes atomic level sensitivity with respect to energy level structure, radiation and transient effects, electron temperature and x-ray drive sensitivity and an idea for electron temperature extraction from a level population ratio. The neon atomic model considers several ionization stages of highly-charged neon ions as well as a detailed structure of non-autoionizing and autoionizing energy levels in each ion. In the energy level sensitivity study, the atomic model was changed by adding certain types of energy levels such as singly-excited, auto-ionizing doubly-excited states. Furthermore, these levels were added ion by ion for the most populated ions. Atomic processes populating and de-populating the energy levels consider photoexcitation and photoionization due to the external radiation flux, and spontaneous and collisional atomic processes including plasma radiation trapping. Relevant atomic cross sections and rates were computed with the atomic structure and scattering FAC code. The calculations were performed at constant particle number density and driven by the time-histories of temperature and external radiation flux. These conditions were selected in order to resemble those achieved in photoionized plasma experiments at the Z facility of Sandia National Laboratories. For the same set of time histories, calculations were done in a full time-dependent mode and also as a sequence of instantaneous, steady states. Differences between both calculations are useful to identify transient effects in the ionization and atomic kinetics of the photoionized plasma, and its dependence on the atomic model and plasma environmental conditions. We also calculated transmission spectra in an effort to identify time-dependent effects in observed spectral features. Furthermore, all the steady state and time-dependent calculations were performed for different electron temperature histories to investigate electron temperature effects in the same way transient effects were examined. The idea for electron temperature extraction based on the population ratio of two energy levels close in energy was investigated after preliminary estimations revealed evidence of dominant electron collisional excitation and de-excitation over photo-excitation and spontaneous radiative decay between the ground state, 1s22 s, and the first excited state, 1s22 p, levels of Li-like Ne. Since the populations of these levels were determined from the analysis of transmission spectra, it was then possible to estimate the temperature via a Boltzmann factor. Further studies were performed for various plasma conditions such as temperature and density in order to confirm the reliability of the method. Calculations were performed for a sequence of steady states and in a full time-dependent mode. Finally, the instantaneous spectra was integrated over several time intervals in order to test the method on conditions similar to those of laboratory experiments.
Kinetic studies of plasma free fatty acid and triglyceride metabolism in man
Eaton, R. Philip; Berman, Mones; Steinberg, Daniel
1969-01-01
Plasma transport of free fatty acids (FFA) and triglyceride fatty acids (TGFA) was studied in seven subjects with normal lipid metabolism, one case of total lipodystrophy, and one case of familial hyperlipemia (Type V). Studies were carried out after intravenous injection of radioactive FFA, of lipoproteins previously labeled in vitro in the triglyceride moiety, or both. Computer techniques were used to evaluate a series of multicompartmental models, and a general model is proposed that yields optimum fitting of experimental data for both FFA and TGFA. The results show that as much as 20-30% of FFA leaving the plasma compartment in normal subjects is transported to an exchanging extravascular pool and quickly reenters the plasma pool as FFA. The rate of irreversible delivery of FFA from plasma to tissues averaged 358 ?Eq/min in normals. The lipodystrophy patient, despite the virtual absence of adipose tissue (confirmed at autopsy), had a plasma FFA concentration and a total FFA transport, both more than twice normal. Total TGFA transport ranged from 25 to 81 ?Eq/min in four normal controls. The rate constant for TGFA turnover in the patient with Type V hyperlipemia was so small that total transport could not be quantified from the data available; the TGFA half-life was over 500 min. In two normal subjects given injections of autologous lipoproteins labeled in vitro with triolein-14C and simultaneously given oleic acid-3H, it was shown that the time course for the disappearance of the TGFA in the in vitro labeled samples conformed almost exactly to that of the physiologically labeled lipoprotein TGFA synthesized from injected FFA (as evidenced by the simultaneous fitting of both sets of data using the same multicompartmental model and the same rate constants). Radioactivity appeared in the plasma FFA fraction at a significant rate after injection of plasma labeled in vitro with TGFA. It was estimated that as much as 50% of the total TGFA transported underwent rapid and rather direct conversion to FFA in the two normal subjects studied this way. The kinetic data suggest that such conversion of TGFA to FFA was not preceded by any extensive dilution, such as would result from complete mixing with tissue triglyceride stores. Images PMID:5796365
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.
T. Gyergyek; B. Jurcic-Zlobec; M. Cercek
2008-01-01
Potential formation in a bounded plasma system that contains electrons with a two-temperature velocity distribution and is terminated by a floating, electron emitting electrode (collector) is studied by a one-dimensional kinetic model. A method on how to determine the boundary conditions at the collector for the numerical solution of the Poisson equation is presented. The difference between the regular and
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.
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. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, Lausanne, (Switzerland); Berger, R. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cohen, B. I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hausammann, L. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, Lausanne, (Switzerland); Valeo, E. J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
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.
NASA Astrophysics Data System (ADS)
Feygin, F. Z.; Khabazin, Yu. G.
2014-11-01
A slow drift mirror (SDM) instability has been analyzed in the scope of kinetic approximation, with accounting for the electron pressure for different particle distribution functions. The dependence of the SDM instability increment growth rate on the parameters of the anisotropic ? distribution with the loss cone, which is used to model real space plasma particle distributions, has been studied. An analysis indicated that the appearance of the loss cone in the ion distribution function results in a decrease in the SDM mode frequency, and an enhancement of the suprathermal tail (a decrease in ?) increases the SDM mode frequency as compared to the Maxwellian distribution. In other words, particle redistribution from the region of low velocities into that of high velocities results in an increase in the SDM mode frequency.
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.
H. J. de Vega
2000-11-21
We implement the dynamical renormalization group (DRG) using the hard thermal loop (HTL) approximation for the real-time nonequilibrium dynamics in hot plasmas. The focus is on the study of the relaxation of gauge and fermionic mean fields and on the quantum kinetics of the photon and fermion distribution functions. As a concrete physical prediction, we find that for a QGP of temperature T sim 200 MeV and lifetime 10 < t < 50 fm/c there is a new contribution to the hard (k \\sim T) photon production from off-shell bremsstrahlung (q rightarrow q gamma and bar{q} rightarrow bar{q} gamma) at just O (alpha) that grows logarithmically in time and is comparable to the known on-shell Compton scattering and pair annihilation at O(alpha alpha_s).
Variational Formulation of Particle Algorithms for Kinetic E&M Plasma Simulations
NASA Astrophysics Data System (ADS)
Stamm, Alexander; Shadwick, Bradley; Evstatiev, Evstati
2013-10-01
A rigorous variational method was used to derive a self-consistent set of equations of motion from a discretized Lagrangian to study kinetic plasmas. Discretization of the Lagrangian was performed by reduction of the phase-space distribution function to a collection of finite-sized macro-particles of arbitrary shape and discretization of field quantities onto a spatial grid. The equations of motion were then obtained by demanding the action be stationary. This approach may be used in both lab frame and moving window coordinates, which improve computational efficiency when modeling laser-plasma interactions. The primary advantage of the variational approach is preservation of Lagrangian symmetries, which in our case leads to energy conservation and avoids difficulties with grid heating. Additionally, this approach decouples particle size from grid spacing and relaxes restrictions on particle shape, leading to a decrease in numerical noise. The variational approach also guarantees consistent ordering and is amiable to higher order methods in both space and time. Simulations conducted with the new equations of motion demonstrate the desired energy conservation and a decrease in numerical noise. A rigorous variational method was used to derive a self-consistent set of equations of motion from a discretized Lagrangian to study kinetic plasmas. Discretization of the Lagrangian was performed by reduction of the phase-space distribution function to a collection of finite-sized macro-particles of arbitrary shape and discretization of field quantities onto a spatial grid. The equations of motion were then obtained by demanding the action be stationary. This approach may be used in both lab frame and moving window coordinates, which improve computational efficiency when modeling laser-plasma interactions. The primary advantage of the variational approach is preservation of Lagrangian symmetries, which in our case leads to energy conservation and avoids difficulties with grid heating. Additionally, this approach decouples particle size from grid spacing and relaxes restrictions on particle shape, leading to a decrease in numerical noise. The variational approach also guarantees consistent ordering and is amiable to higher order methods in both space and time. Simulations conducted with the new equations of motion demonstrate the desired energy conservation and a decrease in numerical noise. This work was supported by the U.S. Department of Education grant P200A090156 and by the U.S. Department of Energy under Contract No. DE-FG02-08ER55000.
Kinetic plasma turbulence during the nonlinear stage of the Kelvin-Helmholtz instability
Kemel, Koen; Lapenta, Giovanni; Califano, Francesco; Markidis, Stefano
2014-01-01
Using a full kinetic, implicit particle-in-cell code, iPiC3D, we studied the properties of plasma kinetic turbulence, such as would be found at the interface between the solar wind and the Earth magnetosphere at low latitude during northwards periods. In this case, in the presence of a magnetic field B oriented mostly perpendicular to the velocity shear, turbulence is fed by the disruption of a Kelvin-Helmholtz vortex chain via secondary instabilities, vortex pairing and non-linear interactions. We found that the magnetic energy spectral cascade between ion and electron inertial scales, $d_i$ and $d_e$, is in agreement with satellite observations and other previous numerical simulations; however, in our case the spectrum ends with a peak beyond $d_e$ due to the occurrence of the lower hybrid drift instability. The electric energy spectrum is influenced by effects of secondary instabilities: anomalous resistivity, fed by the development of the lower hybrid drift instability, steepens the spectral decay and, de...
Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Hardee, P.; Zhang, B.; Du?an, I.; Medvedev, M.; Choi, E. J.; Min, K. W.; Niemiec, J.; Mizuno, Y.; Nordlund, A.; Frederiksen, J. T.; Sol, H.; Pohl, M.; Hartmann, D. H.
2013-09-01
We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic jet and an unmagnetized sheath plasma. We have examined the strong magnetic fields generated by kinetic shear (Kelvin-Helmholtz) instabilities. Compared to the previous studies using counter-streaming performed by Alves et al. (2012), the structure of the kinetic Kelvin-Helmholtz instability (KKHI) of our jet-sheath configuration is slightly different, even for the global evolution of the strong transverse magnetic field. In our simulations the major components of growing modes are the electric field Ez, perpendicular to the flow boundary, and the magnetic field By, transverse to the flow direction. After the By component is excited, an induced electric field Ex, parallel to the flow direction, becomes significant. However, other field components remain small. We find that the structure and growth rate of KKHI with mass ratios mi/me = 1836 and mi/me = 20 are similar. In our simulations saturation in the nonlinear stage is not as clear as in counter-streaming cases. The growth rate for a mildly-relativistic jet case (?j = 1.5) is larger than for a relativistic jet case (?j = 15).
KINETIC PLASMA TURBULENCE IN THE FAST SOLAR WIND MEASURED BY CLUSTER
Roberts, O. W.; Li, X. [Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth, Ceredigion SY23 3BZ (United Kingdom); Li, B., E-mail: xxl@aber.ac.uk [School of Space Science and Physics, Shandong University, Weihai 246209 (China)
2013-05-20
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.
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.
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.
The Role of the Kinetic Ballooning/Interchange Instability in Near-Earth Plasma Sheet Dynamics
NASA Astrophysics Data System (ADS)
Pritchett, P. L.; Coroniti, F. V.
2012-12-01
While theoretical treatments of the near-Earth plasma sheet frequently start from a simple neutral sheet configuration, the actual behavior of the plasma sheet is much more complex than is implied by such a model. The presence of the finite normal Bz component produces a curved magnetic geometry which introduces intrinsically kinetic effects such as bounce and drift-resonant interactions in the particle dynamics and can lead to new classes of instabilities. We present recent results concerning one such mode, the kinetic Ballooning/InterChange Instability (BICI). While the first treatments found that this mode could exist in the presence of a tailward gradient in Bz, it now appears that excitation can occur more generally provided that the entropy profile decreases with distance down the tail. The mode exhibits a cross-tail wavelength of several thousand km (comparable to the local equatorial proton gyroradius), a real frequency on the order of half of the midplane proton cyclotron frequency, and drifts westward at about 100 km/s. The eigenmodes are strongly field aligned and feature pronounced parallel electron flows comparable to the proton thermal velocity and in-phase oscillations of the Bx and Bz fields. The dominant mode polarization is ? ? and ? B||. Once excited, the growth of the modes is robust and leads to the formation of intense interchange heads with magnetic field comparable to the lobe field that propagate earthward. The relevance of the BICI mode dynamics to the formation of dipolarization fronts, the possible breakup of reconnection exhausts, and the initiation of substorms will be discussed.
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.
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 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.
Capitelli, M. [Department of Chemistry-University of Bari (Italy); IMIP CNR - Bari (Italy); De Pascale, O. [IMIP CNR - Bari (Italy); Shakatov, V. [Centro Laser s.r.l. - Valenzano (Italy); Hassouni, K.; Lombardi, G.; Gicquel, A. [LIMHP-CNRS Universite Paris Nord - Villetaneuse (France)
2005-05-16
Vibrational and rotational experimental temperatures of molecular hydrogen obtained by Coherent Anti-Stokes Spectroscopy (CARS) in Radiofrequency Inductive Plasmas have been analyzed and interpreted in terms of vibration, electron, dissociation-recombination and attachment kinetics. The analysis clarifies the role of atomic hydrogen and its heterogeneous recombination in affecting the vibrational content of the molecules.
Kinetics of ion and prompt electron emission from laser-produced plasma N. Farid,1,2
Harilal, S. S.
particle emission from LPP. In general, ions are emitted from the solid target in the form of a cone dueKinetics of ion and prompt electron emission from laser-produced plasma N. Farid,1,2 S. S. Harilal by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University
Kinetic modeling of electronically enhanced reaction pathways in Plasma Assisted Combustion
NASA Astrophysics Data System (ADS)
Parsey, Guy; Gü?lü, Yaman; Verboncoeur, John; Christlieb, Andrew
2012-10-01
The use of plasma energy to enhance and control the chemical reactions during combustion, a technology referred to as ``plasma assisted combustion'' (PAC), can result in a variety of beneficial effects: e.g. stable lean operation, pollution reduction, and wider range of p-T operating conditions. While experimental evidence abounds, theoretical understanding of PAC is at best incomplete, and numerical tools still lack in reliable predictive capabilities. In the context of a joint experimental-numerical effort at Michigan State University, we present here a modular Python framework dedicated to the dynamic optimization of non-equilibrium PAC systems. We first describe a novel kinetic global model, which aims at exploring scaling laws in parameter space, as well as the effect of a non-Maxwellian electron energy distribution function (EEDF). With such a model, we reproduce literature results and we critically review the effect of data uncertainty and limiting assumptions. Then, we explore means of measuring a non-Maxwellian EEDF through the use of a detailed collisional-radiative model, coupled to optical emission spectroscopy. Finally, we investigate the effect of different numerical integrators, as well as customized routines specifically designed to solve stiff sparse ODE systems.
Nonlinear kinetic effects in inductively coupled plasmas via particle-in-cell simulations
NASA Astrophysics Data System (ADS)
Froese, Aaron; Smolyakov, Andrei; Sydorenko, Dmytro
2007-11-01
Kinetic effects in inductively coupled plasmas due to thermal motion of particles modified by self-consistent magnetic fields are studied using a particle-in-cell code. In the low pressure, low frequency regime, electron mean free paths are large relative to device size and the trajectories are strongly curved by the induced rf magnetic field. Analytic linear theories are unable to recover effects accumulated along each nonlinear path. Therefore, the simulated ICP is made progressively more complex to find the source of observed plasma behaviours. With only thermal motion modifying the wave-particle interaction, nonlocal behaviour becomes dominant at low frequencies, causing an anomalous skin effect with increased skin depth and power absorption and decreased ponderomotive force. However, when influenced by magnetic fields, the nonlocal effects are suppressed at large wave amplitudes due to nonlinear trapping. A mechanism is proposed for this low frequency restoration of local behaviour. Finally, a low rate of electron-neutral collisions is found to counteract the nonlinear behaviour, and hence reinforces nonlocal behaviour.
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.
Implementation of the Kinetic Plasma Code with Locally Recursive non-Locally Asynchronous Algorithms
NASA Astrophysics Data System (ADS)
Perepelkina, A. Yu; Levchenko, V. D.; Goryachev, I. A.
2014-05-01
Numerical simulation is presently considered impractical for several relevant plasma kinetics problems due to limitations of computer hardware even with the use of supercomputers. To overcome the existing limitations it is suggested to develop algorithms which would effectively utilize the computer memory subsystem hierarchy to optimize the dependency graph traversal rules. The ideas for general cases of numerical simulation and implementation of such algorithms to particle-in-cell code is discussed in the paper. This approach enables the simulation of previously unaccessible for modeling problems and the execution of series of numerical experiments in reasonable time. The latter is demonstrated on a multiscale problem of the development of filamentation instability in laser interaction with overdense plasma. One variant of the simulation with parameters typical for simulations on supercomputers is performed with the use of one cluster node. The series of such experiments revealed the dependency of energy loss on incoming laser pulse amplitude to be nonmonotonic and reach over 4%, an interesting result for research of fast ignition concept.
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.
NASA Astrophysics Data System (ADS)
Hakim, Ammar; Hammett, Greg; Shi, Eric
2013-10-01
A new high-order discontinuous Galerkin (DG) code for the solution of drift- and gyrokinetic equations in edge plasma is under development. Gkeyll implements extensions of recently developed DG schemes to general Hamiltonian systems, including to the case of discontinuous potentials. The collisionless part of the dynamics is evolved with an energy conserving DG discretization. Diffusion operators are handled with a consistent recovery-based algorithm. It is shown that traditional penalty and local DG schemes for diffusion are inconsistent, and can lead to large errors in predicting high-order moments of the solution. An energy and momentum conserving Lenard-Bernstein collision operator is implemented. The velocity space drag and diffusion operators, as well as the boundary conditions, need to be handled carefully to conserve the discrete particles, momentum and energy. Extension of Gkeyll to multiple dimension are presented, and initial tests of the code in 1D/2V and 2D/2V are shown. In addition, application of the code to computing heat-loads on divertor plates using a variety of 1D/1V kinetic models will be shown. A new high-order discontinuous Galerkin (DG) code for the solution of drift- and gyrokinetic equations in edge plasma is under development. Gkeyll implements extensions of recently developed DG schemes to general Hamiltonian systems, including to the case of discontinuous potentials. The collisionless part of the dynamics is evolved with an energy conserving DG discretization. Diffusion operators are handled with a consistent recovery-based algorithm. It is shown that traditional penalty and local DG schemes for diffusion are inconsistent, and can lead to large errors in predicting high-order moments of the solution. An energy and momentum conserving Lenard-Bernstein collision operator is implemented. The velocity space drag and diffusion operators, as well as the boundary conditions, need to be handled carefully to conserve the discrete particles, momentum and energy. Extension of Gkeyll to multiple dimension are presented, and initial tests of the code in 1D/2V and 2D/2V are shown. In addition, application of the code to computing heat-loads on divertor plates using a variety of 1D/1V kinetic models will be shown. Supported by Max-Planck/Princeton Center for Plasma Physics and DOE Contract DE-AC02-09CH11466.
Sowa, M. J. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Littau, M. E. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Pohray, V. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Cecchi, J. L. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
2000-09-01
Maintaining dimensional control and adequate throughput during the etching of submicron features requires plasma etch tools that operate at low pressures and high densities, such as inductively coupled plasmas (ICPs). Unfortunately, in this regime, it has proven difficult to achieve a stable, reproducible chemistry for selective oxide etching of contacts and vias. In particular, it is difficult to control the passivating polymer film which provides etching selectivity to silicon, nitride, and photoresist. As a first step toward sorting out the complicated oxide etching chemistry, we have measured and modeled the kinetics of the polymer film deposition in an ICP reactor for C{sub 2}F{sub 6}/H{sub 2} and CHF{sub 3} chemistries. Using a unique application of statistical design of experiments, we have explored the pressure range of 3-15 mTorr, power range of 300-2000 W, residence times from 0.5 to 1.0 s, and magnetic field from 0 to 24 G. Polymer deposition rates on a bare Si wafer are measured using a laser interferometer. The concentration of fluorocarbon radicals, CF, CF{sub 2}, and CF{sub 3}, are measured in the plasma using wavelength modulated infrared diode laser absorption spectroscopy. Additional measurements include actinometric F atom density and ion saturation current. These measurements are analyzed in terms of a polymer deposition model and the important physical phenomena are inferred. Significantly, we find a unique polymer deposition mechanism over the entire range of tool parameters including direct deposition of CF and ion-assisted deposition of CF{sub 2}. (c) 2000 American Vacuum Society.
NASA Astrophysics Data System (ADS)
Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.
2013-03-01
Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism of energy dissipation. One example of occurrence of sacrificial bonds and hidden length is in the polymeric glue connection between collagen fibrils in animal bone. In this talk, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the revelation of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation, at the mean-field level, allowing for the number of bonds and hidden lengths to take up non-integer values between successive, discrete bond-breakage events. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.
Rudzinski, W?adys?aw; Plazinski, Wojciech
2008-04-01
It is shown that the kinetics of dyes sorption from aqueous solutions by solids can be considered as a two-step process. The first initial kinetics is governed by the rate of surface reaction. When the adsorbed amount reaches about 80% of the equilibrium coverage, it switches to another kinetics governed by the rate of intraparticle diffusion. Equations we developed recently are used to calculate the whole composite kinetic isotherm, and a simple numerical procedure is proposed to use these equations in the quantitative analysis of experimental data. This procedure is illustrated by the analysis of kinetic isotherms of sorption of metal complex yellow by pine sawdust. PMID:18504983
NASA Astrophysics Data System (ADS)
Stepanov, S.; Meichsner, J.
2012-04-01
The infrared tunable diode laser absorption spectroscopy (IR-TDLAS) experimental technique was employed to study CF radical kinetics in pulsed capacitively coupled CF4/H2 rf plasmas. In particular, the special data acquisition approach (so-called ‘burst mode’) was adapted and applied to monitor the absolute number density of CF with a temporal resolution of better than 1 ms. This enabled a proper kinetic analysis of the radical during both ‘plasma on’ and ‘plasma off’ phases. Thus, during the ‘plasma off’ phase, the CF species was found to be rapidly consumed, mostly in the reactor volume. Possible surface losses (sticking) of CF were shown to be of minor importance, and became notable only at total pressures lower than 10 Pa. During the ‘plasma on’ phase the CF concentration was measured to increase rapidly, reach a maximum and then decrease to its steady-state value. The observed overshoot in the CF density trace was shown to correlate with the corresponding decay of the C2F4 species also measured in the ‘plasma on’ phase. The electron impact fragmentation of C2F4 was supposed to contribute significantly to the effective production of CF at the beginning of the ‘plasma on’ phase, which might have caused the observed overshoots.
Costa, A. A. da; Diver, D. A.; Laing, E. W.; Stark, C. R.; Teodoro, L. F. A.
2011-01-15
The classical modeling of radiation by accelerated charged particles in pulsars predicts a cutoff in photon energy at around 25 GeV. While this is broadly consistent with observations, the classical treatment is not self-consistent, and cannot be extended to explain the rare high-energy detections of photons in the 100s of GeV range. In this paper we revisit the theoretical modeling of high-energy radiation processes in very strong electromagnetic fields, in the context of both single particles and collective plasmas. There are no classical constraints on this description. We find that there is indeed a critical energy of around 50 GeV that arises naturally in this self-consistent treatment, but rather than being a cutoff, this critical energy signals a transition from radiation that is classical to a quasiquantum description, in which the particle is able to radiate almost its total energy in a single event. This new modeling therefore places pulsar radiation processes on a more secure physical basis, and admits the possibility of the production of TeV photons in a self-consistent way.
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.
Kinetics of plasma membrane and mitochondrial alterations in cells undergoing apoptosis
Lizard, G.; Fournel, S.; Genestier, L.; Dhedin, N.
1995-11-01
Programmed cell death or apoptosis is characterized by typical morphological alterations. By transmission electron microscopy, apoptotic cells are identified by condensation of the chromatin in tight apposition to the nuclear envelope, alteration of the nuclear envelope and fragmentation of the nucleus, whereas integrity of the plasma membrane and organelles is preserved. Conversely cells undergoing necrosis display and early desintegration of cytoplasmic membrane and swelling of mitochondria. In this study we assessed by flow cytometry the sequential alterations of forward angle light scatter, 90{degrees} light scatter, and fluorescence associated with fluorescein diacetate, rhodamine 123, and propidium iodide in two human B cell lines undergoing apoptosis induced by the topoisomerase II inhibitor VP-16. The kinetics of these modifications were compared to those of cells undergoing necrosis induced by the topoisomerase II inhibitor VP-16. The kinetics of these modifications were compared to those of cells undergoing necrosis induced by sodium azide. At the same time intervals, cells were examined by transmission electron microscopy and by UV microscopy after staining with Hoechst 33342. We report that sequential changes in light scatters and fluorescein diacetate are similar in cells undergoing apoptosis or necrosis, whereas apoptosis is characterized by a slightly delayed decrease of mitochondrial activity as assessed by rhodamine 123 staining. Surprisingly, a part of cells undergoing apoptosis displayed an early uptake of propidium iodide followed by a condensation and then a fragmentation of their nuclei. It is concluded that uptake of propidium iodide is a very early marker of cell death which does not discriminate between necrosis and apoptosis. Along with biochemical criteria, nuclear morphology revealed by staining with Hoechst 33342 would seem to be of the most simple and most discriminative assay of apoptosis. 33 refs., 5 figs., 1 tab.
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.
NASA Astrophysics Data System (ADS)
Schafer, J.; Lyons, W.; Tong, W. G.; Danehy, P. M.
2009-04-01
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 radio-frequency plasma using a continuous-wave, tunable 811.5 nm diode laser to excite the 4s3P2?4p3D3 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±150 K. Electron densities measured range from 6.1 (±0.3)×1015 cm-3 to 10.1 (±0.3)×1015 cm-3. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. The 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.
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.
NASA Astrophysics Data System (ADS)
Gruzinov, Irina
The dissertation consists of two parts, both of which relate to the topic of the self-organization in plasma. Self-organization in plasma is a process of spontaneous formation of ordered structures at scales much larger than the turbulent correlation scale. Examples of such structures could be a mean magnetic field in interstellar or in interplanetary space, accretion disks around dense objects, zonal fields and zonal flows in fusion plasmas, steep gradient profiles in tokamaks etc. Part I of the dissertation addresses the fundamental problem of magnetic field generation (dynamo action). The novelty of our work is that, applying a quasilinear theory to the kinetic Alfven wave (KAW) turbulence, we demonstrate the possibility of the 'fast dynamo', i.e. a dynamo action which does not depend on plasma resistivity, which is extremely small in most of the relevant plasmas in space and in laboratories. Instead, the irreversibility of the dynamo action is provided by the Landau damping of the kinetic Alfven waves on plasma electrons. Whereas Part I explicitly exploite microscopic properties of the plasma instability, the opposite methodology is applied in Part II to the problem of L ? H transition and pedestal formation in magnetically confined plasmas. There a generic dynamical model, known as a sandpile cellular automaton is applied. This model is independent of the particular kind of underlying turbulence and incorporates the key features of a confined plasma, namely, collisional diffusion, shear induced bistability of turbulent transport and a local MHD limit on the gradient. One chapter of Part II describes the general phenomenology of the pedestal formation. Another chapter is concerned with an effect of the diffusion. Diffusion changes the character of the edge discharge events and can lead to hysteresis in the L ? H ? L transition.
Fast, kinetically self-consistent simulation of RF modulated plasma boundary sheaths
NASA Astrophysics Data System (ADS)
Shihab, Mohammed; Ziegler, Dennis; Brinkmann, Ralf Peter
2012-05-01
A mathematical model is presented which enables the efficient, kinetically self-consistent simulation of RF modulated plasma boundary sheaths in all technically relevant discharge regimes. It is defined on a one-dimensional geometry where a Cartesian x-axis points from the electrode or wall at xE ? 0 towards the plasma bulk. An arbitrary endpoint xB is chosen ‘deep in the bulk’. The model consists of a set of kinetic equations for the ions, Boltzmann's relation for the electrons and Poisson's equation for the electrical field. Boundary conditions specify the ion flux at xB and a periodically—not necessarily harmonically—modulated sheath voltage V(t) or sheath charge Q(t). The equations are solved in a statistical sense. However, it is not the well-known particle-in-cell (PIC) scheme that is employed, but an alternative iterative algorithm termed ensemble-in-spacetime (EST). The basis of the scheme is a discretization of the spacetime, the product of the domain [xE, xB] and the RF period [0, T]. Three modules are called in a sequence. A Monte Carlo module calculates the trajectories of a large set of ions from their start at xB until they reach the electrode at xE, utilizing the potential values on the nodes of the spatio-temporal grid. A harmonic analysis module reconstructs the Fourier modes nim(x) of the ion density ni(x, t) from the calculated trajectories. A field module finally solves the Boltzmann-Poisson equation with the calculated ion densities to generate an updated set of potential values for the spatio-temporal grid. The iteration is started with the potential values of a self-consistent fluid model and terminates when the updates become sufficiently small, i.e. when self-consistency is achieved. A subsequent post-processing determines important quantities, in particular the phase-resolved and phase-averaged values of the ion energy and angular distributions and the total energy flux at the electrode. A drastic reduction of the computational effort compared with PIC calculations is achieved. As a first application of the new model, the influence of ion inertia on the dynamics of a collisionless sheath is studied and a comparison of the simulated ion energy distribution with published analytical solutions is performed.
Kinetic driven turbulence: Structure in space and time T. N. Parashar, S. Servidio,a
Shay, Michael
wave description for a simple but relevant model of a kinetic plasma. In particular we examineKinetic driven turbulence: Structure in space and time T. N. Parashar, S. Servidio,a B. Breech,b M October 2010 The structure in space and time of a driven turbulent magnetoplasma is analyzed using kinetic
Pegasus: A new hybrid-kinetic particle-in-cell code for astrophysical plasma dynamics
NASA Astrophysics Data System (ADS)
Kunz, Matthew W.; Stone, James M.; Bai, Xue-Ning
2014-02-01
We describe Pegasus, a new hybrid-kinetic particle-in-cell code tailored for the study of astrophysical plasma dynamics. The code incorporates an energy-conserving particle integrator into a stable, second-order-accurate, three-stage predictor-predictor-corrector integration algorithm. The constrained transport method is used to enforce the divergence-free constraint on the magnetic field. A ?f scheme is included to facilitate a reduced-noise study of systems in which only small departures from an initial distribution function are anticipated. The effects of rotation and shear are implemented through the shearing-sheet formalism with orbital advection. These algorithms are embedded within an architecture similar to that used in the popular astrophysical magnetohydrodynamics code Athena, one that is modular, well-documented, easy to use, and efficiently parallelized for use on thousands of processors. We present a series of tests in one, two, and three spatial dimensions that demonstrate the fidelity and versatility of the code.
Agostoni, Piergiuseppe; Banfi, Cristina; Magrì, Damiano; Vignati, Carlo; Doria, Elisabetta; Salvioni, Elisabetta; Moliterni, Paola; Marenzi, Giancarlo; Tremoli, Elena; Sisillo, Erminio
2011-09-15
Receptor-of-Advanced-Glycation-End-products (RAGE) and Surfactant-Protein-type-B (SPB) are reported as lung injury markers. Unlike SPB, RAGE is secreted by several tissues, so that RAGE specificity as lung injury marker is questionable. We measured SPB and RAGE in 19 patients undergoing major vascular abdominal surgery. SPB and RAGE were measured before mechanical ventilation (T0), at 1st (T1), 2nd (T2) and, when present, 3rd (T3) hour of mechanical ventilation, and 1h after extubation (T(POST)). Last data during mechanical ventilation, either T2 or T3, are reported as T(END). SPB and RAGE values were normalized for total protein (SPB(N) and RAGE(N)). SPB(N) and RAGE(N) increments from T0 to T(END) were 56.2 [39.1] ng/mg (mean [75-25 percentile]) and 10.6[7.1] pg/mg, respectively. SPB values increased progressively during mechanical ventilation, whereas RAGE values increased at T(1) but not thereafter. SPB(N) increase (T(END)-T0), but not RAGE(N), was related to ?PaO(2)/FiO2 changes during mechanical ventilation (r=0.575, p=0.01). Plasma RAGE(N) and SPB(N) kinetics in patients undergoing major vascular surgery are different. PMID:21736957
High-resolution hybrid simulations of kinetic plasma turbulence at proton scales
Franci, Luca; Matteini, Lorenzo; Verdini, Andrea; Hellinger, Petr
2015-01-01
We investigate properties of plasma turbulence from magneto-hydrodynamic (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 a 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 ...
Kinetic Study of the Solid-State Transformation of Vacuum-Plasma-Sprayed Ti-6Al-4V Alloy
NASA Astrophysics Data System (ADS)
Salimijazi, H. R.; Mousavi, Z. A.; Golozar, M. A.; Mostaghimi, J.; Coyle, T.
2014-01-01
Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of ? phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of ?-phase grain boundary, and the second mechanism was ?-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the phase transformation at different constant temperatures, a time-temperature-transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.
Kinetics of gas-phase chemical reactions in a remote RF plasma reactor with electron spin resonance
Janca, J.; Talsky, A.; Zvonicek, V. [Masaryk Univ., Brno (Czech Republic)
1995-12-31
A remote RF plasma reactor is inherently a reactive gas flow system in which the gas-phase chemical reactions of interest occur outside (downstream) the plasma and involve paramagnetic ground state or excited species (e.g. H, O, O{sub 2}, N, NO). Consequently, the kinetics of the gas-phase reactions can be quantitatively characterized by electron spin resonance (ESR). Gas flows and tube pressure are essential parameters for quantitative analysis. The ESR measurements provides the absolute value of paramagnetic species, the determination of recombination and rate coefficients of selected reactions. The goal of the measurements described in the present paper was to find the wall recombination coefficient in pure nitrogen and oxygen and to explain the effect of impurities on both dissociation and recombination of N and O. Next the reaction of atomic oxygen with the molecules of tetraethoxysilane (TEOS) was studied and the kinetic coefficient of this reaction was determined.
Radical kinetics in an inductively-coupled plasma in CF4
Booth, J.P.; Abada, H.; Chabert, P.; Graves, D.B.
2004-12-01
Radiofrequency discharges in low pressure fluorocarbon gases are used for anisotropic and selective etching of dielectric materials (SiO2 and derivatives), a key step in the manufacture of integrated circuits. Plasmas in these gases are capable not only of etching, but also of depositing fluorocarbon films, depending on a number of factors including the ion bombardment energy, the gas composition and the surface temperature: this behavior is indeed responsible for etch selectivity between materials and plays a role in achieving the desired etched feature profiles. Free radical species, such as CFx and fluorine atoms, play important but complex roles in these processes. We have used laser-induced fluorescence (LIF), with time and space resolution in pulsed plasmas, to elucidate the kinetics of CF and CF2 radicals, elucidating their creation, destruction and transport mechanisms within the reactor. Whereas more complex gas mixtures are used in industrial processes, study of the relatively simple system of a pure CF4 plasma is more appropriate for the study of mechanisms. Previously the technique was applied to the study of single-frequency capacitively-coupled 'reactive ion etching' reactors, where the substrate (placed on the powered electrode) is always bombarded with high-energy CF{sub x}{sup +} ions. In this case it was found that the major source of CFx free radicals was neutralization, dissociation and backscattering of these incident ions, rather than direct dissociation of the feedstock gas. Subsequently, an inductively-coupled plasma (ICP) in pure CF4 was studied. This system has a higher plasma density, leading to higher gas dissociation, whereas the energy of ions striking the reactor surfaces is much lower (in the absence of additional RF biasing). The LIF technique also allows the gas temperature to be measured with good spatial and temporal resolution. This showed large gas temperature gradients within the ICP reactor, which must be taken into account in reactive species transport. In the ICP reactor we saw significant production of CF and CF2 radicals at the reactor top and bottom surfaces, at rates that cannot be explained by the neutralization of incident CF{sub x}{sup +} ions. These two species are also lost at very high rates in the gas phase. We postulate that these two phenomena are caused by electron-impact excitation of these radicals into low-lying metastable levels. The metastable molecules produced (that are invisible to LIF) diffuse to the reactor walls where they are quenched back to their ground state. In the afterglow the gas cools rapidly and contracts, causing gas convection. Whereas the density of the more reactive species decays monotonically in the afterglow, the density of CF2 initially increases. This is partly due to the gas contraction, bringing back CF2 (which is a relatively stable species) from the outer regions of the reactor, and partly due to chemical reactions producing CF2, as it is more thermodynamically stable than the other radical species such as CF and CF3.
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.
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.
Statistical description of the fluctuation particle fluxes in the plasma edge
NASA Astrophysics Data System (ADS)
Saenko, V.
2009-04-01
Plasma turbulence studies carried out in the last few decades have shown that the measured distributions of amplitudes of the fluctuational particle fluxes in the laboratory plasma as well as in the solar wind have non-Gaussian probability density functions. These distributions are leptocurtic and have slowly decreasing exponential tails. Fractional stable densities (FSD) « ? Î²?? Î²?? q(x;?,Î²,Î&)cedil; = 0 g(xy ;?,Î&)cedil;g(y;Î²,1)y dy, was applied for it description, where 0 < ? ? 2, 0 < Î² ? 1, |Î&|cedil;? min(1,2?? - 1) and g(x;?,Î&)cedil; and g(y;Î²,1) respectively is strictly stable and one sided strictly stable distribution. This distributions have heavy slowly decreasing exponential tails too. As is well known [1] through the FSD the solution of the generalization diffusion equation ?Î²p(x,t) ??2 t-Î²^(x) --?tÎ²---= - D(- ) p(x,t)+ Î? (1--Î²) is expressed. Here Î² ??tÎ² is Riman-Liuville fractional derivative and (-)??2 is Laplacian of the fractional order. The probability density function of the fluctuational particle fluxes in plasma peripheral region of stellarator L-2m is studied in the work. The parameters of fractional stable distributions were statistically estimated from measured signals [2]. It is shown that fractional stable distributions give a good fit to the probability density functions of amplitudes of fluctuating particle fluxes. The Hurst parameter was calculated for all the discharges under study. Its values lie in the range 0.64 to 0.75, which agrees with results obtained in other devices. Algorithms for data processing and the algorithm for estimation of parameters of FS densities, along with results of calculations, will be presented in the report. The work is completed under the support of the Russian Fund for Basic Research (projects No's. 07-01-00517, 07-02-00455, 08-02-00651) References [1] V. V. Uchaikin. International Journal of Theoretical Physics 39 p. 2087 (2000). [2] V. E. Bening, V. Yu. Korolev, V. N. Kolokol'tsov, V. V. Saenko, V. V. Uchaikin, and V. M. Zolotarev. J. Math. Sci., 123 p.3722 (2004)
NASA Astrophysics Data System (ADS)
Lee, W. Wei-Li; Davidson, Ronald C.; Stoltz, Peter
1997-11-01
This paper presents a detailed formulation and analysis of the rate equations for statistically-averaged quantities for an intense nonneutral beam propagating through a periodic solenoidal focusing field. B^sol(x) = B_z(z)hatez - (1/2)B'_z(z)(xhatex + yhate_y), where B_z(z+S) = B_z(z), and S = const. is the axial periodicity length. The anaysis assumes a thin beam with characteristic beam radius rb << S, and is based on the nonlinear Vlasov-Maxwell equations. Particularly important in experimental applications and in numerical simulations schemes, such as the nonlinear ? f- scheme,(Q. Qian, W. Lee, and R. Davidson, Phys. Plasmas 4), 1915 (1997). is an understanding of the self-consistent nonlinear evolution of various quantities averaged over the distribution of beam particles f_b(x,p,t). Self-consistent rate equations are derived for the nonlinear evolution of the mean-square beam radius
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 ...
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.
NASA Astrophysics Data System (ADS)
Pasquiers, S.; Blin-Simiand, N.; Magne, L.
2013-12-01
In plasmas of atmospheric gases, the kinetics of some aliphatic organic molecules belonging to the hydrocarbons (propene, propane), aldehydes (acetaldehyde) and ketones (acetone) families were studied using a photo-triggered discharge (homogeneous plasma). It was shown that quenchings of N2 metastable states, A\\,^{3}\\Sigma_{u}^{+} and the group of singlets a'\\,^{1}\\Sigma_{u}^{-} , a 1?g and w 1?u, are important processes for the decomposition of such molecules. It plays a fundamental role in the nitrogen plasma, but it is also present in air. At low temperature, the oxidation reactions by the oxygen atom or by the hydroxyl radical are not always sufficiently effective to induce an increase of the molecule decomposition when oxygen is added to the nitrogen/organic mixture. For most cases, quenching processes appear purely dissociative. However, recent results obtained for propene lead to the conclusion that a non-dissociative exit route could exist. The quenching of the singlet states induces a break of the double bound C = O for the acetaldehyde and acetone molecules. Some kinetic analogies appear between filamentary and homogeneous plasmas, which could be very useful to get a comprehensive understanding of the physico-chemical processes in dielectric barriers or corona discharges used for various applications.
Kinetics of Sodium Dodecyl Sulfate Solubilization of Mycoplasma laidlawii Plasma Membranes
James J. Auborn; Edward M. Eyring; G. Lew Choules
1971-01-01
The kinetics of sodium dodecyl sulfate solubilization of aqueous suspensions of Mycoplasma laidlawii membranes have been investigated by light scattering in a stopped-flow apparatus. There was evidence of direct interaction between the membranes and sodium dodecyl sulfate micelles above the critical micelle concentration, although of lower order kinetically than with monomeric dodecyl sulfate anions below the critical micelle concentration. The
NASA Astrophysics Data System (ADS)
Soni, Dilip; Sharma, Giriraj; Saxena, Ajay; Jadhav, Akhilesh
2015-07-01
An analytical study on propagation characteristics of longitudinal electro-kinetic (LEK) waves is presented. Based on multi-fluid model of plasma, we have derived a dispersion relation for LEK waves in colloid laden GaN semiconductor plasmas. It is assumed that ions are implanted to form colloids in the GaN sample. The colloids are continuously bombarded by the plasma particles and stick on them, but they acquire a net negative charge due to relatively higher mobility of electrons. It is found from the dispersion relation that the presence of charged colloids not only modifies the existing modes but also supports new novel modes of LEKWs. It is hoped that the study would enhance understanding on dispersion and absorption of LEKWs and help in singling out the appropriate configurations in which GaN crystal would be better suited for fabrication of microwave devices.
Gibbons, M.R.
1995-06-01
This dissertation describes a new algorithm for simulating low frequency, kinetic phenomena in plasmas. DArwin Direct Implicit Particle-in-Cell (DADIPIC), as its name implies, is a combination of the Darwin and direct implicit methods. One of the difficulties in simulating plasmas lies in the enormous disparity between the fundamental scale lengths of a plasma and the scale lengths of the phenomena of interest. The objective is to create models which can ignore the fundamental constraints without eliminating relevant plasma properties. Over the past twenty years several PIC methods have been investigated for overcoming the constraints on explicit electrodynamic PIC. These models eliminate selected high frequency plasma phenomena while retaining kinetic phenomena at low frequency. This dissertation shows that the combination of Darwin and Direct Implicit allows them to operate better than they have been shown to operate in the past. Through the Darwin method the hyperbolic Maxwell`s equations are reformulated into a set of elliptic equations. Propagating light waves do not exist in the formulation so the Courant constraint on the time step is eliminated. The Direct Implicit method is applied only to the electrostatic field with the result that electrostatic plasma oscillations do not have to be resolved for stability. With the elimination of these constraints spatial and temporal discretization can be much larger than that possible with explicit, electrodynamic PIC. The code functions in a two dimensional Cartesian region and has been implemented with all components of the particle velocities, the E-field, and the B-field. Internal structures, conductors or dielectrics, may be placed in the simulation region, can be set at desired potentials, and driven with specified currents.
Jaeger, E. F. [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)] [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States); Berry, L. A. [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)] [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States); Batchelor, D. B. [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)] [P.O. Box 2009, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)
2000-02-01
A comprehensive kinetic theory is developed to treat radio frequency (rf) driven plasma flow in one-dimensional geometry. The kinetic equation is expanded to second order in the perturbing rf electric field. No assumption is made regarding the smallness of the ion Larmor radius relative to wavelength. Moments of the second-order distribution function give time-averaged expressions for the rf-driven particle transport, forces, and heating, including the wave kinetic flux. On the transport time scale, the rf force in the poloidal direction is balanced by neoclassical viscosity, and the force in the radial direction is balanced by ambipolar electric fields. Comparison is made with previous theories which have relied on incompressible fluid approximations and a Reynolds stress model for the rf pressure. Substantial differences are seen in situations involving the ion Bernstein wave, which is compressional in nature. Linear electron Landau damping and magnetic pumping, by themselves, do not lead to significant poloidal flow. But ion cyclotron damping of either fast magnetosonic waves or ion Bernstein waves can drive significant flow at power levels typical of plasma heating experiments. (c)
Steiner, S A; Castellino, F J
1985-01-29
A study of the effect of monovalent cations on the steady-state kinetic parameters for the hydrolysis of the synthetic substrate N alpha-benzoyl-L-arginine-p-nitroanilide by activated bovine plasma protein C (APC) has been undertaken. The enzyme displayed a strict requirement for monovalent cations in its expression of amidolytic activity toward this substrate. Analysis of the variation in initial hydrolytic reaction rates, as a function of metal ion concentrations, suggested that at least two cation sites, or classes of sites, were necessary for catalysis to occur. After examination of the rate equations consequential to many different enzymic mechanisms that could account for these kinetic data, a mechanism was developed that fit the great majority of the experimental observations. In this mechanism it is postulated that cations bind to the enzyme in pairs, with a kinetically observable single binding constant, either preceded by or followed by binding of substrate. Catalysis occurs only after the enzyme-(metal cation)2-substrate complex is assembled. Some physical support for this mechanism was obtained upon the discovery that the binding (dissociation) constant for a competitive inhibitor of APC, p-aminobenzamidine, as determined by kinetic methodology, was independent of the concentration of Na+ and Cs+. PMID:2986681
INTERMITTENT HEATING IN SOLAR WIND AND KINETIC SIMULATIONS
Wu, P.; Wan, M.; Matthaeus, W. H.; Shay, M. A. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Perri, S. [Dipartimento di Fisica, Universita della Calabria, I-87036 Cosenza (Italy); Osman, K.; Chapman, S. [Centre for Fusion, Space and Astrophysics, University of Warwick (United Kingdom); Goldstein, M. L. [NASA/GSFC, Greenbelt, MD (United States); Karimabadi, H., E-mail: penny@udel.edu, E-mail: whm@udel.edu [University of California at San Diego, La Jolla, CA 92093 (United States)
2013-02-01
Low-density astrophysical plasmas may be described by magnetohydrodynamics at large scales, but require kinetic description at ion scales in order to include dissipative processes that terminate the cascade. Here kinetic plasma simulations and high-resolution spacecraft observations are compared to facilitate the interpretation of signatures of various dissipation mechanisms. Kurtosis of increments indicates that kinetic scale coherent structures are present, with some suggestion of incoherent activity near ion scales. Conditioned proton temperature distributions suggest heating associated with coherent structures. The results reinforce the association of intermittent turbulence, coherent structures, and plasma dissipation.
Jin, Weidong, 1975-
2004-01-01
This work characterized the Cl2/HBr ion enhanced plasma-surface interactions with poly-silicon as a function of the gas composition, ion energy, ion incident angle and other important process parameters. A realistic ...
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 ...
Shionoiri, H; Gotoh, E; Kaneko, Y; Eggena, P; Sambhi, M P
1983-12-01
We have previously reported on the differences in physical and chemical characteristics between the high-molecular weight renin substrate (HMS greater than 150,000 daltons) and the normal substrate (NMS = 60,000). In this study, the kinetic constants were determined in both HMS and NMS which were prepared by gel exclusion chromatography from the plasma of pregnant women at term. Renin substrate (angiotensinogen) levels were expressed by radioimmunoassay of angiotensin I after incubation of samples with added semi-purified human kidney renin in the presence of angiotensinase inhibitors. The kinetic constants (Km and Vmax) were determined by the method of Line-weaver-Burk plots and also the method of Wilkinson. The Km for the HMS was 1.79 micrograms angiotensin 1 equivalents ( AIeq )/ml and the Vmax = 41.2 ngAIeq /ml/h, and the Km for the NMS was 3.52 micrograms AIeq /ml and the Vmax = 138 ng/ml/h. When adding small amounts of the HMS to the NMS, the production of angiotensin I was found to increase more than that in the NMS alone. It was also observed that the renin substrate reactivities of the plasma of pregnant women, which contained small amounts of the HMS, were higher than that found in the plasma of normotensive women not taking oral contraceptives. It is suggested that the existence of small amounts of the HMS may therefore contribute to the elevation in blood pressure under the influence of estrogens. PMID:6373244
2005 Workshop on NCETIP 1 Kinetic of plasma particles and electron
Kaganovich, Igor
RAILGUNRAILGUN · Electromagnetic solid body acceleration The electromagnetic force generates in the current loop I~LindU/dt, I~B Arc plasma generates by the rail evaporation E Accelerated Plasma Arc I V FIELD: · MHD-Generation of Electrical Power GIVEN: plasma flow V OBTAIN: E-electrical field
NASA Technical Reports Server (NTRS)
Horwitz, James L.
1996-01-01
During the indicated period of performance, we had a number of publications concerned with kinetic polar ionosphere-lower magnetosphere plasma transport. For the IUGG 1991-4 Quadrennial Report, we reviewed aspects of U.S. accomplishments concerned with polar plasma transport, among other issues. In another review, we examined the computer simulations of multiple-scale processes in space plasmas, including polar plasma outflow and transport. We also examined specifically multiscale processes in ionospheric outflows. We developed a Generalized Semi-Kinetic(GSK) model for the topside-lower magnetosphere which explored the synergistic action of wave heating and electric potentials in the formation of auroral Ion conics, in particular the "pressure cooker" mechanism. We extended the GSK model all the way down to 120 km and applied this code to illustrate the response of the ionosphere- magnetosphere to soft-electron precipitation and convection-driven frictional ion heating, respectively. Later, the convection-driven heating work was extended to a paper for the Journal of Geophysical Research. In addition to the above full published papers, we also presented the first developments of the coupled fluid-semikinetic model for polar plasma transport during this period. The results from a steady-state treatment were presented, with the second presentation being concerned with the effects of photo-electrons on the polar wind, and the first garnering an outstanding student paper award from the American Geophysical Union. We presented the first results from a time-dependent version of this coupled fluid-semikinetic model.
The Plasma Interaction Experiment /PIX/ - Description and flight qualification test program
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 1 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.
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).
Indium kinetics during the plasma-assisted molecular beam epitaxy of semipolar (11-22) InGaN layers
Das, A.; Kotsar, Y.; Kandaswamy, P. K.; Gayral, B.; Monroy, E.; Ruterana, P.
2010-05-03
We report on the growth kinetics of semipolar (11-22) InGaN layers by plasma-assisted molecular beam epitaxy. Similarly to (0001)-oriented InGaN, optimum growth conditions for this crystallographic orientation correspond to the stabilization of two atomic layers of In on the growing InGaN surface, and the limits of this growth window in terms of substrate temperature and In flux lie at same values for both polar and semipolar material. However, in semipolar samples, the incorporation of In is inhibited, even for growth temperatures within the Ga-limited regime of polar InGaN growth.
Measuring the EOS of a Dense, Strongly Coupled Plasma; Description of the Technique
Benage, John F. Jr.; Kyraka, George; Workman, Jonathan; Tierney, Thomas
1997-12-31
This paper describes a new experimental design which we believe can produce reasonably accurate data for the equation of state (EOS) of a dense plasma. This design takes advantage of the standard shock technique used for determining the high pressure EOS of solids. It also utilizes recently developed experimental techniques for producing dense, strongly coupled plasmas as well as new diagnostic techniques for measuring the properties of these plasmas. The results should be able to distinguish among theoretical models for plasmas at just under solid density and temperatures of 10`s of eV.
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
Kaganovich, Igor
of the target are described. The mechanism of cathode vaporization taking into account cathode electron emission ( ), depending on the ratio of the electron emission flux to the vaporized atom flux, which in turn depends on the cathode material. Index Terms--Ablative wall, current structure, current-car- rying plasma, double sheath
Plasma heating by a relativistic electron beam. I - Wave kinetic equation and spectral function
NASA Astrophysics Data System (ADS)
Okazaki, T.; Kato, T.
1980-10-01
A new possibility for plasma heating is proposed and theoretical investigation is performed. Under a suitable experimental condition, the wave induced by the two-stream instability and Buneman/ion-acoustic wave induced by the return current can coexist and interact to yield a new contribution to plasma heating by the relativistic electron beam. The authors assume this is the case and develop the formulation necessary for the analysis of the spectral function of turbulent plasma.
Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas
Qiu, Z. [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China)] [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China); Chen, L. [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China) [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China); Dept. Physics and Astronomy, Univ. of California, Irvine, California 92697-4575 (United States); Zonca, F. [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China) [Inst. Fusion Theory and Simulation, Zhejiang Univ., Hangzhou 310027 (China); Associazione Euratom-ENEA sulla Fusione, C.P. 65 - I-00044 - Frascati (Italy)
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)
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.
NASA Astrophysics Data System (ADS)
Gao, Cheng; Zeng, Jiaolong; Li, Yongqiang; Jin, Fengtao; Yuan, Jianmin
2013-09-01
A versatile code DLAYZ based on collisional-radiative model is developed for investigating the population kinetics and radiative properties of plasmas in non-local thermodynamic equilibrium. DLAYZ is implemented on the detailed level accounting (DLA) approach and can be extended to detailed configuration accounting (DCA) and hybrid DLA/DCA approaches. The code can treat both steady state and time-dependent problems. The implementation of the main modules of DLAYZ is discussed in detail including atomic data, rates, population distributions and radiative properties modules. The complete set of basic atomic data is obtained using relativistic quantum mechanics. For dense plasmas, the basic atomic data with plasma screening effects can be obtained. The populations are obtained by solving the coupled rate equations, which are used to calculate the radiative properties. A parallelized version is implemented in the code to treat the large-scale rate equations. Two illustrative examples of a steady state case for carbon plasmas and a time-dependent case for the relaxation of a K-shell excited argon are employed to show the main features of the present code.
Zocco, Alessandro; Schekochihin, Alexander A.
2011-10-15
A minimal model for magnetic reconnection and, generally, low-frequency dynamics in low-beta plasmas is proposed. The model combines analytical and computational simplicity with physical realizability: it is a rigorous limit of gyrokinetics for plasma beta of order the electron-ion mass ratio. The model contains collisions and can be used both in the collisional and collisionless reconnection regimes. It includes gyrokinetic ions (not assumed cold) and allows for the topological rearrangement of the magnetic field lines by either resistivity or electron inertia, whichever predominates. The two-fluid dynamics are coupled to electron kinetics--electrons are not assumed isothermal and are described by a reduced drift-kinetic equation. The model, therefore allows for irreversibility and conversion of magnetic energy into electron heat via parallel phase mixing in velocity space. An analysis of the exchanges between various forms of free energy and its conversion into electron heat is provided. It is shown how all relevant linear waves and regimes of the tearing instability (collisionless, semicollisional, and fully resistive) are recovered in various limits of our model. An efficient way to simulate our equations numerically is proposed, via the Hermite representation of the velocity space. It is shown that small scales in velocity space will form, giving rise to a shallow Hermite-space spectrum, whence it is inferred that, for steady-state or sufficiently slow dynamics, the electron heating rate will remain finite in the limit of vanishing collisionality.
NASA Astrophysics Data System (ADS)
Moreau, D.; Walker, M. L.; Ferron, J. R.; Liu, F.; Schuster, E.; Barton, J. E.; Boyer, M. D.; Burrell, K. H.; Flanagan, S. M.; Gohil, P.; Groebner, R. J.; Holcomb, C. T.; Humphreys, D. A.; Hyatt, A. W.; Johnson, R. D.; La Haye, R. J.; Lohr, J.; Luce, T. C.; Park, J. M.; Penaflor, B. G.; Shi, W.; Turco, F.; Wehner, W.; the ITPA-IOS Group members; experts
2013-06-01
The first real-time profile control experiments integrating magnetic and kinetic variables were performed on DIII-D in view of regulating and extrapolating advanced tokamak scenarios to steady-state devices and burning plasma experiments. Device-specific, control-oriented models were obtained from experimental data using a generic two-time-scale method that was validated on JET, JT-60U and DIII-D under the framework of the International Tokamak Physics Activity for Integrated Operation Scenarios (Moreau et al 2011 Nucl. Fusion 51 063009). On DIII-D, these data-driven models were used to synthesize integrated magnetic and kinetic profile controllers. The neutral beam injection (NBI), electron cyclotron current drive (ECCD) systems and ohmic coil provided the heating and current drive (H&CD) sources. The first control actuator was the plasma surface loop voltage (i.e. the ohmic coil), and the available beamlines and gyrotrons were grouped to form five additional H&CD actuators: co-current on-axis NBI, co-current off-axis NBI, counter-current NBI, balanced NBI and total ECCD power from all gyrotrons (with off-axis current deposition). Successful closed-loop experiments showing the control of (a) the poloidal flux profile, ?(x), (b) the poloidal flux profile together with the normalized pressure parameter, ?N, and (c) the inverse of the safety factor profile, \\bar{\\iota}(x)=1/q(x) , are described.
Duyen, Huynh T. L.; Ngoc, Tran V.; Hang, Vu T. T.; Kieu, Nguyen T. T.; Young, Paul R.; Farrar, Jeremy J.; Simmons, Cameron P.; Wolbers, Marcel; Wills, Bridget A.
2011-01-01
We describe the magnitude and kinetics of plasma viremia and nonstructural protein 1 (sNS1) levels in sequential samples from 167 children with acute dengue, enrolled early in a community study in Vietnam. All children recovered fully, and only 5 required hospitalization. Among those with dengue virus type 1 (DENV-1), plasma viremia was significantly greater in primary (49) than secondary (44) infections and took longer to resolve. In primary DENV-2 and 3 infections, viremia was significantly lower than among primary DENV-1 infections. Concentrations of sNS1 were significantly higher for DENV-1 than for DENV-2 after adjusting for viremia, with marked differences in the kinetic profiles between primary and secondary infections. Secondary infection and higher viremia were independent predictors of more severe thrombocytopenia, and higher viremia was associated with a small increase in hemoconcentration. Our findings identify clear serotype and immune-status related effects on the dynamics of dengue viremia and sNS1 responses, together with associations with important clinical parameters. PMID:21335562
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
Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method
William Taitano; Dana Knoll; Luis Chacon
2009-01-01
The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as
Measurement of plasma histamine: description of an improved method and normal values
Dyer, J.; Warren, K.; Merlin, S.; Metcalfe, D.D.; Kaliner, M.
1982-08-01
The single isotopic-enzymatic assay of histamine was modified to increase its sensitivity and to facilitate measurement of plasma histamine levels. The modification involved extracting /sup 3/H-1-methylhistamine (generated by the enzyme N-methyltransferase acting on histamine in the presence of S-(methyl-/sup 3/H)-adenosyl-L-methionine) into chloroform and isolating the /sup 3/H-1-methylhistamine by thin-layer chromatography (TLC). The TLC was developed in acetone:ammonium hydroxide (95:10), and the methylhistamine spot (Rf . 0.50) was identified with an o-phthalaldehyde spray, scraped from the plate, and assayed in a scintillation counter. The assay in plasma demonstrated a linear relationship from 200 to 5000 pg histamine/ml. Plasma always had higher readings than buffer, and dialysis of plasma returned these values to the same level as buffer, suggesting that the baseline elevations might be attributable to histamine. However, all histamine standard curves were run in dialyzed plasma to negate any additional influences plasma might exert on the assay. The arithmetic mean (+/- SEM) in normal plasma histamine was 318.4 +/- 25 pg/ml (n . 51), and the geometric mean was 280 +/- 35 pg/ml. Plasma histamine was significantly elevated by infusion of histamine at 0.05 to 1.0 micrograms/kg/min or by cold immersion of the hand of a cold-urticaria patient. Therefore this modified isotopic-enzymatic assay of histamine is extremely sensitive, capable of measuring fluctuations in plasma histamine levels within the normal range, and potentially useful in analysis of the role histamine plays in human physiology.
NASA Astrophysics Data System (ADS)
Lehn, Scott A.; Warner, Kelly A.; Huang, Mao; Hieftje, Gary M.
2002-11-01
Thomson scattering, Rayleigh scattering and line-of-sight emission intensities of Ca ion and Sr ion from the inductively coupled plasma were measured in the presence and in the absence of an inductively coupled plasma mass spectrometry sampler interface. When present, the sampler interface was located 13 mm above the load coil (ALC); optical measurements were made 6, 7 and 8 mm ALC. The experimental results suggest that both the electron temperature ( Te) and gas-kinetic temperature ( Tg) dropped in the presence of the sampler interface, with the change in Tg seemingly greater than that in Te, suggesting a faster cooling process for the heavy particles. In contrast, electron number density ( ne) seemed to be generally increased in the outer regions of the discharge but went down in the central channel, a reflection that ne is possibly dominated by ambipolar diffusion which becomes less efficient as Te drops. Assuming these results, the plasma decays more gradually ALC and deviates from local thermodynamic equilibrium even more significantly in the presence of the sampler interface. Analyte line emission intensity was either depressed or enhanced in the presence of the interface, depending on the element being observed and the operating conditions. In addition, the change in emission intensity caused by the sampler interface became much more dramatic when a matrix element, such as Li or Zn, was introduced.
Kinetic model for the one-dimensional electromagnetic solitons in an isothermal plasma
NASA Astrophysics Data System (ADS)
Tajima, T.
2002-02-01
Two nonlinear second order differential equations for the amplitude of the vector potential and for the electromagnetic potential are derived, starting from the full Maxwell equations where the field sources are calculated by integrating in the momentum space the particle distribution function, which is an exact solution of the relativistic Vlasov equation. The resulting equations are exact in describing a hot one-dimensional plasma sustaining a relativistically intense, circularly polarized electromagnetic polarized electromagnetic radiation. The case of standing soliton-like structures in an electron-positron plasma is then investigated. It is demonstrated that at ultrarelativistic temperatures extremely large amplitude solitons can be formed in a strongly overdense plasma.
A kinetic model for the one-dimensional electromagnetic solitons in an isothermal plasma
NASA Astrophysics Data System (ADS)
Lontano, Maurizio; Bulanov, Sergei V.; Koga, James; Passoni, Matteo; Tajima, Toshiki
2002-06-01
Two nonlinear second order differential equations for the amplitude of the vector potential and for the electrostatic potential are derived, starting from the full Maxwell equations where the field sources are calculated by integrating in the momentum space the particle distribution function, which is an exact solution of the relativistic Vlasov equation. The resulting equations are exact in describing a hot one-dimensional plasma sustaining a relativistically intense, circularly polarized electromagnetic radiation. The case of standing soliton-like structures in an electron-positron plasma is then investigated. It is demonstrated that at ultrarelativistic temperatures extremely large amplitude solitons can be formed in a strongly overdense plasma.
On SUGRA description of boost-invariant conformal plasma at strong coupling
Alex Buchel
2008-03-26
We study string theory duals of the expanding boost invariant conformal gauge theory plasmas at strong coupling. The dual supergravity background is constructed as an asymptotic late-time expansion, corresponding to equilibration of the gauge theory plasma. The absence of curvature singularities in the first few orders of the late-time expansion of the dual gravitational background unambiguously determines the equilibrium equation of the state, and the shear viscosity of the gauge theory plasma. While the absence of the leading pole singularities in the gravitational curvature invariants at the third order in late-time expansion determines the relaxation time of the plasma, the subleading logarithmic singularity can not be canceled within a supergravity approximation. We comment on the possible interpretations of this singularity.
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
2009-10-01
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. PMID:19895060
Decharging of Complex Plasmas: First Kinetic Observations A.V. Ivlev,1
Goree, John
, and charged micro- particles. The latter are visible individually and allow experiments in plasma science rings, see Fig. 1); the particle dispensers in the center were grounded. Also, the lower ring was biased
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 ...
A Simple Ion-Ion Charge Exchange Model for Kinetic Plasma Simulations
David Fillmore; Peter Messmer; Paul Mullowney
2008-01-01
We present a simple modification of the semi-classical over-barrier model of ion-atom charge exchange for the case of electron transfer between positive ions. The charge exchange cross-sections have been incorporated into an electromagnetic particle-in-cell plasma model which also includes schemes for electron impact ionization and electron-ion recombination. The influence of charge exchange on the plasma ionization state is explored for
A kinetic equation for linear stable fractional motion with applications to space plasma physics
Watkins, Nicholas W [British Antarctic Survey, Cambridge, UK; Credgington, Daniel [British Antarctic Survey, Cambridge, UK; Sanchez, Raul [ORNL; Rosenberg, SJ [British Antarctic Survey, Cambridge, UK; Chapman, Sandra C [University of Warwick, UK
2009-01-01
Levy flights and fractional Brownian motion have become exemplars of the heavy-tailed jumps and long-ranged memory widely seen in physics. Natural time series frequently combine both effects, and linear fractional stable motion (lfsm) is a model process of this type, combining {alpha}-stable jumps with a memory kernel. In contrast complex physical spatiotemporal diffusion processes where both the above effects compete have for many years been modeled using the fully fractional kinetic equation for the continuous-time random walk (CTRW), with power laws in the probability density functions of both jump size and waiting time. We derive the analogous kinetic equation for lfsm and show that it has a diffusion coefficient with a power law in time rather than having a fractional time derivative like the CTRW. We discuss some preliminary results on the scaling of burst 'sizes' and 'durations' in lfsm time series, with applications to modeling existing observations in space physics and elsewhere.
Stimulated Brillouin scattering of whistler waves off the kinetic Alfven waves in plasmas
Sharma, R.P.; Rozmus, W.; Offenberger, A.A.
1986-12-01
In this paper an investigation of the parametric process is presented in which a high-power whistler wave decays into another whistler wave and a low-frequency kinetic Alfven wave (mixed mode), viz., the stimulated Brillouin scattering of a whistler. The dominant coupling in the equation for the scattered whistler arises from the electron motion along the static magnetic field in the low-frequency wave and the partially electrostatic nature of the kinetic Alfven wave. On the other hand, interaction of two whistler waves leads to a component of the ponderomotive force along the static magnetic field. This component is responsible for the electrostatic part of the kinetic Alfven wave. Explicit expressions for the growth rate and threshold power are given. At a pump power of --1 kW, the growth time of this parametric process comes out to be --5 ..mu..sec for the parameters of the mirror device. For the magnetospheric parameters, the convective threshold electric field is --0.3 mV/m.
Tholeti, Siva Sashank; Alexeenko, Alina A., E-mail: alexeenk@purdue.edu [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Shneider, Mikhail N. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)
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.
NASA Astrophysics Data System (ADS)
Fougere, Nicolas; Combi, M. R.; Tenishev, V.
2013-10-01
The recent images from the Deep Impact spacecraft at Comet 9P/Tempel 1 and from its extended mission EPOXI at Comet 103P/Hartley 2 showed heterogeneous gas release from the nucleus with multiple jets and complex active areas. The coma structure of a comet with such active areas differs from typical models where gas is often produced more uniformly from the surface of the nucleus. While 2D kinetic models are already able to describe relatively complex gas production and can give some critical insights of the physics of the coma, most of them assume cylindrical symmetry around the Sun-Nucleus axis preventing to model small active areas and solar orientations not aligned with the symmetry axis. With constantly increasing computer capacities, 3D kinetic models can now be implemented to give a complete insight from the near nucleus region of the coma where collisions drive its thermodynamics to larger distances where the atmosphere becomes rarefied. We describe a fully 3D kinetic Direct Simulation of Monte Carlo approach to modeling the coma, and a first application to enable progress toward a general tridimensional description of the rarefied atmosphere of Comet Hartley 2 from Fougere et al. (2013) with realistic day-night illumination not only with respect to the EPOXI geometry at closest approach but for other observations. [This work was supported by grant NNX09AB58G from the NASA Planetary Atmosphere program.
Kinetic properties of the particle-in-cell simulation of a Lorentz plasma
NASA Astrophysics Data System (ADS)
Lin-Liu, Y. R.; Lin, T. Y.; Chen, S. H.
2010-11-01
The phenomenon of numerical thermalization in the standard particle-in-cell (PIC) simulation of Vlasov plasmas has been extensively studied at the early stage of its development [1] and was considered well understood. However, it was recently reported [2] that the well-established scaling law for the thermalization time could be compromised by the presence of an additional stochastic force acting on the particles, which is used to simulate collisional processes in a weakly ionized gas. In the present work, we are interested in the problem of electron-ion collisions in a fully ionized plasma. We investigate the thermal relaxation phenomenon in the PIC simulation of a Lorentz plasma in one dimension [3]. The pitch-angle scattering of the electrons by the stationary ion background is modeled by a Monte-Carlo algorithm. The numerical results obtained indicate that the thermal relaxation time is proportional to ND (the number of particles per Debye length), and not ND^2 as in the standard PIC simulations. Our results appear to complement those found by the previous study [2]. [4pt] [1] C. K. Birdsall and A. B. Langdon, Plasma Physics via Computer Simulation (McGraw-Hill, New York, 1985). [0pt] [2] M. M. Turner, Phys. of Plasmas 13, 033506 (2006). [0pt] [3] R. Shanny, J. M. Dawson, and J. M. Greene, Phys. of Fluids 10, 1281 (1967).
Fokker-Planck description of the scattering of radio frequency waves at the plasma edge
Hizanidis, Kyriakos; Kominis, Yannis; Tsironis, Christos [School of Electrical and Computer Engineering, National Technical University of Athens, Athens GR 15773 (Greece); Ram, Abhay K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2010-02-15
In magnetic fusion devices, radio frequency (rf) waves in the electron cyclotron (EC) and lower hybrid (LH) range of frequencies are being commonly used to modify the plasma current profile. In ITER, EC waves are expected to stabilize the neoclassical tearing mode (NTM) by providing current in the island region [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)]. The appearance of NTMs severely limits the plasma pressure and leads to the degradation of plasma confinement. LH waves could be used in ITER to modify the current profile closer to the edge of the plasma. These rf waves propagate from the excitation structures to the core of the plasma through an edge region, which is characterized by turbulence--in particular, density fluctuations. These fluctuations, in the form of blobs, can modify the propagation properties of the waves by refraction. In this paper, the effect on rf due to randomly distributed blobs in the edge region is studied. The waves are represented as geometric optics rays and the refractive scattering from a distribution of blobs is formulated as a Fokker-Planck equation. The scattering can have two diffusive effects--one in real space and the other in wave vector space. The scattering can modify the trajectory of rays into the plasma and it can affect the wave vector spectrum. The refraction of EC waves, for example, could make them miss the intended target region where the NTMs occur. The broadening of the wave vector spectrum could broaden the wave generated current profile. The Fokker-Planck formalism for diffusion in real space and wave vector space is used to study the effect of density blobs on EC and LH waves in an ITER type of plasma environment. For EC waves the refractive effects become important since the distance of propagation from the edge to the core in ITER is of the order of a meter. The diffusion in wave vector space is small. For LH waves the refractive effects are insignificant but the diffusion in wave vector space is important. The theoretical model is general enough to study the effect of density blobs on all propagating cold plasma waves.
Analytical description of a steady state of multimode beam-plasma system
Tkachenko, V.I.; Tkachenko, I.V. [Scientific Centre of Physical Technologies, Kharkov (Ukraine)
1995-12-31
For many numerical researches of the wave spectrum generated with monoenergetic electron beam in plasma it has been shown that uniform electron beam transforms into bunches. Solutions of initial nonlinear system of equations which the authors have found allow them to define the main features of the steady state condition of multimode beam-plasma system. It follows from the solution obtained, that amplitudes of generated oscillations in short wave limit of spectrum change according to the law m{sup {minus}1}. Two integrals of initial systems are satisfied with founded solutions. Phases spectrum {var_phi}{sub m} at the nonlinear stage are linear functions of time.
DEMOCRITUS code: A kinetic approach to the simulation of complex plasmas
NASA Astrophysics Data System (ADS)
Arinaminpat, Nimlan; Fichtl, Chris; Patacchini, Leonardo; Lapenta, Giovanni; Delzanno, Gian Luca
2006-10-01
The DEMOCRITUS code is a particle-based code for plasma-material interaction simulation. The code makes use of particle in cell (PIC) methods to simulate each plasma species, the material, and their interaction. In this study, we concentrate on a dust particle immersed in a plasma. We start with the simplest case, in which the dust particle is not allowed to emit. From here, we expand the DEMOCRITUS code to include thermionic and photo emission algorithms and obtain our data. Next we expand the physics processes present to include the presence of magnetic fields and collisional processes with a neutral gas. Finally we describe new improvements of the code including a new mover that allows for particle subcycling and a new grid adaptation approach.
Kinetic processes in the plasma formed in combustion of hydrocarbon fuels
NASA Astrophysics Data System (ADS)
Starik, A. M.; Savel'Ev, A. M.; Titova, N. S.
2011-01-01
An analysis of the basic kinetic processes responsible for the formation of ions, electrons, charged and neutral carbon clusters and particles of nanometer size in the combustion of hydrocarbon fuels has been made. It has been shown that the formation of a polydisperse ensemble of positively and negatively charged particles is mainly caused by the ion adhesion to primary particles and secondarily formed particles and also by particle coagulation. Account must be taken not only of the Coulomb interaction but also of the van der Waals and polarization interaction between particles. The distinstice features of the deposition of polar molecules on charged particles have been considered.
Description of HiPIMS plasma regimes in terms of composition, spoke formation and deposition rate
NASA Astrophysics Data System (ADS)
de los Arcos, Teresa; Schröder, Raphael; Aranda Gonzalvo, Yolanda; Schulz-von der Gathen, Volker; Winter, Jörg
2014-10-01
The behaviour of Cu and Cr HiPIMS (high power impulse magnetron sputtering) discharges was investigated by a combination of optical emission spectroscopy, energy-resolved mass spectrometry and optical imaging, for the complete current–voltage characteristic range achievable within our experimental conditions. Inflection points typical of HiPIMS current–voltage characteristics separate plasma regimes perfectly differentiated in terms of flux composition of species towards the substrate, deposition rate, and the nature of plasma self-organization. The reorganization of the HiPIMS plasma into spokes (areas of high ionization over the target) is associated to one regime of high plasma conductivity, where also deposition rate is limited. This spoke-dominated regime can be substituted by a homogeneous regime at higher powers, where there is an increase of deposition rate, which is driven mostly by an increase in the flux of metal neutrals and metal double-charged ions. The relevance of secondary electron emission mechanisms for the support of the spoke-dominated regime in reactive and non-reactive sputtering conditions is discussed.
Kaganovich, Igor
particle-in-cell code. The full-scale two-dimensional numerical simulation of the Weibel instability confinement fusion IFC and accelerator applications.59 Recently, the transport of relativistic electron beams , and the beam density nb is much smaller than the plasma density np. The combination of small nb/np and large
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.
Turbulence healing via plasma-wave interaction: the results of a study via kinetic codes
Chiara Marchetto; Francesco Califano; Maurizio Lontano
2005-01-01
The propagation through a plasma slab of an electrostatic wave with characteristics similar to an Ion Bernstein wave is studied by means of Vlasov simulation codes and grid paradigms. Some interesting results for an application on turbulence healing in fusion devices are illustrated.
Kinetic modelling for an atmospheric pressure argon plasma jet in humid air
NASA Astrophysics Data System (ADS)
Van Gaens, W.; Bogaerts, A.
2013-07-01
A zero-dimensional, semi-empirical model is used to describe the plasma chemistry in an argon plasma jet flowing into humid air, mimicking the experimental conditions of a setup from the Eindhoven University of Technology. The model provides species density profiles as a function of the position in the plasma jet device and effluent. A reaction chemistry set for an argon/humid air mixture is developed, which considers 84 different species and 1880 reactions. Additionally, we present a reduced chemistry set, useful for higher level computational models. Calculated species density profiles along the plasma jet are shown and the chemical pathways are explained in detail. It is demonstrated that chemically reactive H, N, O and OH radicals are formed in large quantities after the nozzle exit and H2, O2(1?g), O3, H2O2, NO2, N2O, HNO2 and HNO3 are predominantly formed as ‘long living’ species. The simulations show that water clustering of positive ions is very important under these conditions. The influence of vibrational excitation on the calculated electron temperature is studied. Finally, the effect of varying gas temperature, flow speed, power density and air humidity on the chemistry is investigated.
Ionization Kinetics in Laser Plasmas D Semkat1, D Kremp1 and M Bonitz2
Bonitz, Michael
of the Bloch equations well-known from atomic and semiconductor physics. We discuss the case of strong fields a partially ionized plasma. Under the influence of an external electromagnetic field, e.g. a strong laser in extended binary collision approximation. The external electromagnetic field is introduced by a manifestly
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.
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, Raymod J.; Pang, Ye; Tang, Chaoling; Huang, Shiyong; El-Alaoui, Mostafa; Yuan, Zhigang; Li, Huimin
2013-04-01
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= -18RE. The bubble is bounded by both sharp leading (?bz/?x<0) and trailing (?bz/?x>0) edges. The two edges are thin current layers (~ 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.
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.
Analytical description of a collisional plasma column in a vacuum arc centrifuge
NASA Astrophysics Data System (ADS)
Hole, M. J.; Simpson, S. W.
2001-10-01
In this work the effects of electron-ion collisions in the plasma column of a vacuum arc centrifuge are modelled using a perturbation technique. It is found that the model agrees reasonably with an earlier fluid simulation, in which ion viscosity effects were also included. Using the perturbed solutions, the axial evolution of the steady-state separation profile is resolved, showing that the effect of electron-ion collisions is to improve separative performance with increasing axial position. The conditions under which separative performance are optimized are suggested. The non-uniformity in the axial magnetic field of a vacuum arc centrifuge caused by plasma rotation is also investigated. It is found that the non-uniformity is weak for standard operating conditions.
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
Hybrid-Kinetic Modelling of Space Plasma with Application to Mercury
NASA Astrophysics Data System (ADS)
Paral, Jan
A planet's magnetosphere is often very dynamic, undergoing large topological changes in response to high speed (˜400km/s) solar wind intervals, coronal mass ejections, and naturally excited plasma wave modes. Plasma waves are very effective at transporting energy throughout the magnetosphere, and are therefore of interest in the context of the coupling between solar wind and magnetosphere. Of relevance to this thesis is Kelvin-Helmholtz macro-instability. Kelvin-Helmholtz instability (KHI) is excited by shear of the flows. KHI is commonly observed at equatorial regions of the magnetopause where fast flowing magnetosheath plasma may interact with slow bulk velocities of magnetospheric plasma. The instability is responsible for exciting shear Alfven waves which (at Earth) may be detected using the ground based magnetometers located at latitude of excited field lines. This thesis uses numerical modelling to understand and to explain the generation and propagation of the KHI in Mercury's magnetosphere. The instability is initiated close to the planet and convectively grows while being transported along the tail. When the wave amplitude reaches a nonlinear stage, the structure of the wave becomes complex due to the wrapping of the plasma into the vortex. A vortex structure is typical for KHI and it is used for identifying the wave in the data from satellites. The instability commonly occurs at the dawn or dusk flank magnetopause (MP) of Earth with approximately the same probability. But the data from NASA's MESSENGER spacecraft, currently in the orbit of the planet Mercury, suggest a strong asymmetry in the observations of KHI. It is shown that the KHI initiated near the subsolar point evolves into large-scale vortices propagating anti-sunward along the dusk-side MP. The simulations are in agreement with the third flyby of the MESSENGER spacecraft, where saw-tooth oscillations in the plasma density, flow, and magnetic field were observed. The observed asymmetry in the KHI between dawn and dusk is found to be controlled by the finite gyro-radius of ions, and by MP pressure gradients and the large-scale solar wind convection electric field.
Modeling the chemical kinetics of atmospheric plasma for cell treatment in a liquid solution
NASA Astrophysics Data System (ADS)
Kim, H. Y.; Lee, H. W.; Kang, S. K.; Wk. Lee, H.; Kim, G. C.; Lee, J. K.
2012-07-01
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+ and He(21S) radicals. Second, O3 density decreases as pH level in the solution decreases and air concentration decreases. It can be a method of removing O3 that causes chest pain and damages lung tissue when the density is very high. H2O2, HO2, and NO radicals are found to be key factors for cell inactivation in the solution with pH and air variation.
Dual cascade and its possible variations in magnetized kinetic plasma turbulence
Jian-Zhou Zhu
2012-06-09
Electrostatic gyrokinetic absolute equilibria with continuum velocity field are obtained through the partition function and through the Green function of the functional integral. The new results justify and explain the prescription for quantization/discretization or taking the continuum limit of velocity. The mistakes in the Appendix D of our earlier work [J.-Z. Zhu and G. W. Hammett, Phys. Plasmas {\\bf 17}, 122307 (2010)] are explained and corrected. If the lattice spacing for discretizing velocity is big enough, all the invariants could concentrate at the lowest Fourier modes in a negative-temperature state, which might indicate a possible variation of the dual cascade picture in two-dimension magnetized plasma turbulence.
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. 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.
Effect of Stochastic Grain Charge Fluctuation on the Kinetic Energy of the Particles in Dusty Plasma
NASA Astrophysics Data System (ADS)
Vaulina, O. S.; Khrapak, S. A.; Samarian, A. A.; Petrov, O. F.
Random charge fluctuations are always present in dusty plasmas due to the discrete nature of currents charging the dust particles. These fluctuations can be a reason of the heating of dust particle systems. In this paper we show by analytical evaluations and numerical simulation that charge fluctuations provide an effective source of energy and can heat the dust particles up to several eV, in conditions close to experimental ones.
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.
Trapping oscillations, discrete particle effects and kinetic theory of collisionless plasma
NASA Astrophysics Data System (ADS)
Doveil, F.; Firpo, M.-C.; Elskens, Y.; Guyomarc'h, D.; Poleni, M.; Bertrand, P.
2001-06-01
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.
Convective Raman Amplification of Light Pulses Causing Kinetic Inflation in Inertial Fusion Plasmas
Ellis, Ian N; Winjum, Benjamin J; Tsung, Frank S; Grismayer, Thomas; Mori, Warren B; Fahlen, Jay E; Williams, Edward A
2012-01-01
We perform 1D particle-in-cell (PIC) simulations using OSIRIS, which model a short-duration (~500/{\\omega}0 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 partic...
Toroidal kinetic {eta}{sub i}-mode study in high temperature plasmas
Dong, J.Q., Horton, W.; Kim, J.Y.
1991-11-01
A new kinetic integral equation for the study of the ion temperature gradient driven mode in toroidal geometry is developed that includes the ion toroidal (curvature and magnetic gradient) drift motion {omega}{sub D}, the mode coupling from finite {kappa}{sub {parallel}} due to the toroidal feature of the sheared magnetic configuration. The integral equation allows the stability study for arbitrary {kappa}{sub {parallel}} {upsilon}{sub i}/({omega} {minus} {omega}{sub D}) and {kappa}{perpendicular}{rho}{sub i}. A systematic parameter study is carried out for the low {beta} circular flux surface equilibrium. Possible correlations between the unstable mode characteristics and some experimental results such as fluctuation spectrum and anomalous ion transport measurements are discussed.
Toroidal kinetic. eta. sub i -mode study in high temperature plasmas
Dong, J.Q., Horton, W.; Kim, J.Y.
1991-11-01
A new kinetic integral equation for the study of the ion temperature gradient driven mode in toroidal geometry is developed that includes the ion toroidal (curvature and magnetic gradient) drift motion {omega}{sub D}, the mode coupling from finite {kappa}{sub {parallel}} due to the toroidal feature of the sheared magnetic configuration. The integral equation allows the stability study for arbitrary {kappa}{sub {parallel}} {upsilon}{sub i}/({omega} {minus} {omega}{sub D}) and {kappa}{perpendicular}{rho}{sub i}. A systematic parameter study is carried out for the low {beta} circular flux surface equilibrium. Possible correlations between the unstable mode characteristics and some experimental results such as fluctuation spectrum and anomalous ion transport measurements are discussed.
Transition form collisional to kinetic reconnection in large-scale plasmas
Daughton, William S; Roytershteyn, Vadim S; Albright, Brian J; Yin, Lin; Bowers, Kevin J; Karimabadi, Homa
2009-01-01
Using first-principles fully kinetic simulations with a Fokker-Planck collision operator, it is demonstrated that Sweet-Parker reconnection layers are unstable to a chain of plasmoids (secondary islands) for Lundquist numbers beyond S >{approx} 1000. The instability is increasingly violent at higher Lundquist number, both in terms of the number of plasmoids produced and the super-Alfvenic growth rate. A dramatic enhancement in the reconnection rate is observed when the half-thickness of the current sheet between two plasmoids approaches the ion inertial length. During this transition, the reconnection electric field rapidly exceeds the runaway limit, resulting in the formation of electron-scale current layers that are unstable to the continual formation of new plasmoids.
5-D Kinetic Modeling of ECRH Plasmas in the HSX Stellarator
NASA Astrophysics Data System (ADS)
Radder, J. W.; Talmadge, J. N.; Likin, K. M.; Anderson, D. T.; Murakami, S.
2007-11-01
The global transport code GNET is used to model the evolution of the perturbed electron distribution function and radial electron transport due to electron cyclotron heating (ECRH) in the HSX stellarator. GNET solves a linearized drift kinetic equation in 5-D phase space, allowing simulation of 3-D HSX magnetic configurations. ECRH is modeled in GNET via a quasi-linear source term calculated with a separate 3-D ray tracing routine for 2nd-harmonic X-mode at 0.5 Tesla operations and 1st-harmonic O--mode at 1.0 Tesla operations. First low input power simulations (< 50kW) show a slight difference between radial transport in quasihelically symmetric and mirror magnetic configurations. GNET predictions of ECRH driven flux, power deposition profiles, and implications for ECE and X-ray diagnostics will be presented.
Kinetic and thermodynamic properties of a convecting plasma in a two-dimensional dipole field
Huang, T.S. [Prairie View A& M Univ., TX (United States)] [Prairie View A& M Univ., TX (United States); Birmingham, T.J. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)] [NASA Goddard Space Flight Center, Greenbelt, MD (United States)
1994-09-01
Charged particle guiding center motion is considered in the magnetic field of a two-dimensional (`line`) dipole on which is superimposed a small, static, perpendicular electric field. The parallel equation of motion is that of a simple harmonic oscillator for cos{theta}, the cosine of magnetic colatitude. Equations for the perpendicular electric and magnetic drifts are derived as well as their bounce-averaged forms. The latter are solved to yield a bounce-averaged guiding center trajectory, which is the same as that obtained from conservation of magnetic moment {mu}, longitudinal invariant J, and total (kinetic plus electrostatic) energy K. The algebraic simplicity of the trajectory equations is also manifest in the forms of the invariants. An interesting result is that guiding centers drift in such a way that they preserve the values of their equatorial pitch angles and (equivalently) mirror latitudes. The most general Maxwellian form of the equilibrium one-particle distribution function f is constructed from the invariants, and spatially varying density and pressure moments, parallel and perpendicular to the magnetic field, are identified. Much of the paper deals with the more restricted problem in which f is specified as a bi-Maxwellian over a straight line of finite length in the equatorial plane of the dipole and perpendicular to field lines. This might be thought of as specifying a cross-tail ion injection source; the authors formalism then describes the subsequent spatial development. The distribution away from the source is a scaled bi-Maxwellian but one that is cut off at large and small kinetic energies, which depend on position. Density and pressure components are reduced from the values they would have if the total content of individual flux tubes convected intact. The equatorial and meridional variations of density and pressure components are examined and compared systematically for the isotropic and highly anisotropic situations. 22 refs., 10 figs.
Convective Raman amplification of light pulses causing kinetic inflation in inertial fusion plasmas
Ellis, I. N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); University of California, Los Angeles, California 90095 (United States); Strozzi, D. J.; Williams, E. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Winjum, B. J.; Tsung, F. S.; Mori, W. B.; Fahlen, J. E. [University of California, Los Angeles, California 90095 (United States); Grismayer, T. [University of California, Los Angeles, California 90095 (United States); Grupo de Lasers e Plasmas, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal)
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: rsch@tp4.rub.de, E-mail: steffen.krakau@rub.de, E-mail: markus.supsar@rub.de [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)
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.
NASA Astrophysics Data System (ADS)
Okada, Takeru; Naoi, Taro; Yoshioka, Toshihiro
2009-06-01
Decay kinetics of luminescence at 5.2 eV and those of sustained electron emission from MgO crystal powders were investigated in order to understand the mechanism of discharge delay in ac plasma display panels and sustained electron emission from insulator. The decay of UV-luminescence was nonexponential and the decay was enhanced by increasing the temperature after showing negligible temperature dependence at low temperature. Existence of carrier traps was indicated by thermoluminescence measurements. As a possible mechanism, luminescence from a donor-acceptor pair in combination with thermal activation from carrier traps was introduced. The electron emission properties were evaluated by the measurement of statistical discharge delay time in ac plasma display panels as an indicator. By coating MgO crystal powders on the MgO protective film, the intensity of electron emission increased and its time and temperature dependence was reduced. A comparison under the same excitation revealed that the decay of UV-luminescence was steeper than that of electron emission. To explain the experimental data, we proposed the involvement of direct electron emission from electron traps synchronized with measuring voltages in addition to luminescence-associated electron emission.
NASA Astrophysics Data System (ADS)
Gilz, Lukas; Anglin, James R.
2015-07-01
Describing local system-reservoir interaction in a quantum kinetic approach allows a first-principles investigation of basic nonequilibirium effects in ultracold atomic vapors. We derive such a quantum kinetic theory and apply it to heat transport in a Bose-condensed gas coupled collisionally to two spatially separated reservoir gases at different temperatures. We show that in the collisionless regime, where a Bogoliubov expansion is applicable, heat is transported by counterpropagating steady currents of condensate and noncondensate fractions, with the condensate flowing towards the source of greater heat. This phenomenon has hitherto only be seen in more strongly interacting systems as superfluid helium and is known as superfluid internal convection. We derive explicit formulas for the steady-state energy current and differential particle currents (with zero net particle flux) in the collisionless regime. As a significant technical detail in this derivation, we show that a correct treatment of this nonequilibrium scenario requires the inclusion of post-Bogoliubov and nonresonant interaction effects.
Description of the Fokker-Plank code used to model ECRH of the Constance 2 plasma
NASA Astrophysics Data System (ADS)
Mauel, M. E.
1982-01-01
The time-dependent Fokker-Plank code which is used to model the development of the electron velocity distribution during ECRH of the Constance 2 mirror-confined plasma is described. The ECRH is modeled a bounce-averaged quasilinear theory. The effect of collisions are found by taking the appropriate gradients of the Rosenbluth potentials, and the electron distribution is advanced in time by using a modified alternating direction implicit technique. The program was written in LISP to be run in the MACSYMA environment of the MACSYMA Consortium's PDP-10 computer.
Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics
Vitelaru, Catalin [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France) [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France); National Institute for Optoelectronics, Magurele-Bucharest, RO 077125 (Romania); Lundin, Daniel [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France) [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France); Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden); Brenning, Nils [Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden)] [Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, SE-100 44 (Sweden); Minea, Tiberiu [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France)] [Laboratoire the Physique de Gaz et Plasmas, UMR 8578 CNRS, Université Paris-Sud, Orsay Cedex 91405 (France)
2013-09-02
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.
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)].
Kinetics and mechanical study of plasma electrolytic carburizing for pure iron
NASA Astrophysics Data System (ADS)
Çavu?lu, F.; Usta, M.
2011-02-01
In this work, plasma electrolytic surface carburizing of pure iron in aqueous solution consisting of water, glycerin and NH4Cl was investigated. Surface carburizing was carried out in 20% glycerin solution treated at 750 °C, 800 °C, 900 °C and 950 °C temperatures for 5, 10 and 30 min. The formation of hard carbon-rich layer on the surface of pure iron was confirmed by XRD analysis. Metallographic and SEM studies revealed a rough and dense carburized layer on the surface of the pure iron. Experimental results showed that the thickness of the carburized layers changes with the time and temperature. The average thickness of the carburized layer ranged from 20 to 160 ?m. The hardness of the carburized samples decreased with the distance from the surface to the interior of the test material. The average hardness values of the carburized layers on the substrate ranged 550-850 HV, while the hardness of the substrate ranged from 110 HV to 170 HV. The dominant phases formed on the pure iron were found to be a mixture of cementite (Fe3C), martensite (Fe + C) and austenite (FCC iron) confirmed by XRD. Wear resistance in all plasma electrolytic carburized samples is considerably improved in relation to the untreated specimen. After carburizing, surface roughness of the samples was increased. Friction coefficients were also increased because of high surface roughness.
Confining domains lead to reaction bursts: reaction kinetics in the plasma membrane.
Kalay, Ziya; Fujiwara, Takahiro K; Kusumi, Akihiro
2012-01-01
Confinement of molecules in specific small volumes and areas within a cell is likely to be a general strategy that is developed during evolution for regulating the interactions and functions of biomolecules. The cellular plasma membrane, which is the outermost membrane that surrounds the entire cell, was considered to be a continuous two-dimensional liquid, but it is becoming clear that it consists of numerous nano-meso-scale domains with various lifetimes, such as raft domains and cytoskeleton-induced compartments, and membrane molecules are dynamically trapped in these domains. In this article, we give a theoretical account on the effects of molecular confinement on reversible bimolecular reactions in a partitioned surface such as the plasma membrane. By performing simulations based on a lattice-based model of diffusion and reaction, we found that in the presence of membrane partitioning, bimolecular reactions that occur in each compartment proceed in bursts during which the reaction rate is sharply and briefly increased even though the asymptotic reaction rate remains the same. We characterized the time between reaction bursts and the burst amplitude as a function of the model parameters, and discussed the biological significance of the reaction bursts in the presence of strong inhibitor activity. PMID:22479350
Plasma transport in stochastic magnetic fields. III. Kinetics of test-particle diffusion
Krommes, J.A.; Oberman, C.; Kleva, R.G.
1982-07-01
A discussion is given of test particle transport in the presence of specified stochastic magnetic fields, with particular emphasis on the collisional limit. Certain paradoxes and inconsistencies in the literature regarding the form of the scaling laws are resolved by carefully distinguishing a number of physically distinct correlation lengths, and thus by identifying several collisional subregimes. The common procedure of averaging the conventional fluid equations over the statistics of a random field is shown to fail in some important cases because of breakdown of the Chapman-Enskog ordering in the presence of a stochastic field component with short autocorrelation length. A modified perturbation theory is introduced which leads to a Kubo-like formula valid in all collisionality regimes. The direct-interaction approximation is shown to fail in the interesting limit in which the orbit exponentiation length L/sub K/ appears explicitly. A higher order renormalized kinetic theory in which L/sub K/ appears naturally is discussed and used to rederive more systematically the results of the heuristic scaling arguments.
NASA Astrophysics Data System (ADS)
Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.
2013-07-01
Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.
Charles K. C. Lieou; Ahmed E. Elbanna; Jean M. Carlson
2013-01-25
Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.
Lieou, Charles K C; Carlson, Jean M
2013-01-01
Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.
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.
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
NASA Astrophysics Data System (ADS)
Somov, B. V.
If you want to learn not only the most fundamental things about the physics of turbulent plasmas but also the current state of the problem including the most recent results in theoretical and experimental investigations - and certainly many physicists and astrophysicists do - this series of three excellent monographs is just for you. The first volume "Physical Kinetics of Turbulent Plasmas" develops the kinetic theory of turbulence through a focus on quasi-particle models and dynamics. It discusses the concepts and theoretical methods for describing weak and strong fluid and phase space turbulence in plasma systems far from equilibrium. The core material includes fluctuation theory, self-similar cascades and transport, mean field theory, resonance broadening and nonlinear wave-particle interaction, wave-wave interaction and wave turbulence, strong turbulence theory and renormalization. The book gives readers a deep understanding of the fields under consideration and builds a foundation for future applications to multi-scale processes of self-organization in tokamaks and other confined plasmas. In spite of a short pedagogical introduction, the book is addressed mainly to well prepared readers with a serious background in plasma physics, to researchers and advanced graduate students in nonlinear plasma physics, controlled fusions and related fields such as cosmic plasma physics
Kinetic theory of electromagnetic plane wave obliquely incident on bounded plasma slab
Angus, J. R.; Krasheninnikov, S. I.; Smolyakov, A. I.
2010-10-15
The effects of electromagnetic plane waves obliquely incident on a warm bounded plasma slab of finite length L are studied by solving the coupled Vlasov-Maxwell set of equations. It is shown that the solution can be greatly simplified in the limit where thermal effects are most important by expanding in small parameters and introducing self-similar variables. These solutions reveal that the coupling of thermal effects with the angle of incidence is negligible in the region of bounce resonance and anomalous skin effect. In the region of the anomalous skin effect, the heating is shown to scale linearly with the anomalous skin depth {delta}{sub a} when {delta}{sub a}<
Phase mixing vs. nonlinear advection in drift-kinetic plasma turbulence
Schekochihin, A A; Highcock, E G; Dellar, P J; Dorland, W; Hammett, G W
2015-01-01
A scaling theory of long-wavelength electrostatic turbulence in a magnetised, weakly collisional plasma (e.g., drift-wave turbulence driven by temperature gradients) is proposed, with account taken both of the nonlinear advection of the perturbed particle distribution by fluctuating ExB flows and of its phase mixing, which is caused by the streaming of the particles along the mean magnetic field and, in a linear problem, would lead to Landau damping. A consistent theory is constructed in which very little free energy leaks into high velocity moments of the distribution, rendering the turbulent cascade in the energetically relevant part of the wave-number space essentially fluid-like. The velocity-space spectra of free energy expressed in terms of Hermite-moment orders are steep power laws and so the free-energy content of the phase space does not diverge at infinitesimal collisionality (while it does for a linear problem); collisional heating due to long-wavelength perturbations vanishes in this limit (also i...
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.
NASA Astrophysics Data System (ADS)
Kong, D. F.; Liu, A. D.; Lan, T.; Qiu, Z. Y.; Zhao, H. L.; Sheng, H. G.; Yu, C. X.; Chen, L.; Xu, G. S.; Zhang, W.; Wan, B. N.; Chen, R.; Ding, W. X.; Sun, X.; Xie, J. L.; Li, H.; Liu, W. D.
2013-11-01
Coexisting multi-geodesic acoustic modes (GAMs), especially coexisting dual GAMs, are observed and studied through Langmuir probe arrays at the edge plasmas of the HT-7 tokamak with lithium-coated walls. The dual GAMs are named a low-frequency GAM (LFGAM) and a high-frequency GAM (HFGAM), and it is found that within the measuring range, the HFGAM propagates outwards while the LFGAM propagates both inwards and outwards with their central frequencies nearly unchanged, and both modes have maximum amplitudes at positions with radial wavenumbers close to zero; meanwhile, the two positions happen to be where the continuum GAM frequency is closest to the central frequencies of the LFGAM and the HFGAM. These characteristics are consistent with those of a kinetic GAM converted from a continuum GAM. The nonlinear couplings between the LFGAM and the HFGAM are also analysed. In this study, we observed not only the interaction between the LFGAM and the HFGAM, but also the self-coupling of the GAM with the beat frequency between them, as well as the coupling between the LFGAM and an unknown mode at ?50 kHz. These nonlinear interactions may play important roles during the saturation process of GAMs. Additionally, amplitude correlation analyses of multi-GAMs indicate that second harmonic GAMs are probably generated from the self-interaction of fundamental GAMs.
Wilson, G.R.
1992-05-01
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 DE1'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 the authors 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. The 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.
Human muscle sympathetic nerve activity and plasma noradrenaline kinetics in space.
Ertl, Andrew C; Diedrich, André; Biaggioni, Italo; Levine, Benjamin D; Robertson, Rose Marie; Cox, James F; Zuckerman, Julie H; Pawelczyk, James A; Ray, Chester A; Buckey, Jay C; 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. PMID:11773339
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.
NASA Astrophysics Data System (ADS)
Gyergyek, T.; Jur?i?-Zlobec, B.; ?er?ek, M.
2008-06-01
Potential formation in a bounded plasma system that contains electrons with a two-temperature velocity distribution and is terminated by a floating, electron emitting electrode (collector) is studied by a one-dimensional kinetic model. A method on how to determine the boundary conditions at the collector for the numerical solution of the Poisson equation is presented. The difference between the regular and the irregular numerical solutions of the Poisson equation is explained. The regular numerical solution of the Poisson equation fulfills the boundary conditions at the source and can be computed for any distance from the collector. The irregular solution does not fulfill the source boundary conditions and the computation breaks down at some distance from the collector. An excellent agreement of the values of the potential at the inflection point found from the numerical solution of the Poisson equation with the values predicted by the analytical model is obtained. Potential, electric field, and particle density profiles found by the numerical solution of the Poisson equation are compared to the profiles obtained with the particle in cell computer simulation. A very good quantitative agreement of the potential and electric field profiles is obtained. For certain values of the parameters the analytical model predicts three possible values of the potential at the inflection point. In such cases always only one of the corresponding numerical solutions of the Poisson equation is regular, while the other two are irregular. The regular numerical solution of the Poisson equation always corresponds to the solution of the model that predicts the largest ion flux to the collector.
NASA Astrophysics Data System (ADS)
Mehdian, H.; Kargarian, A.; Hajisharifi, K.
2015-06-01
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, ?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., E-mail: mehdi.jenab@yahoo.com [Department of Physics, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Kourakis, I., E-mail: IoannisKourakisSci@gmail.com [Center for Plasma Physics, Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)
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.
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.
NASA Astrophysics Data System (ADS)
Ombrello, Timothy M.
The advancement of propulsion devices and combustion systems has created ever increasingly more restrictive reactive environments that push the limits of combustion technology. Precise combustion control for higher efficiencies, reduced emissions, and limited residence times to react can exceed what is possible with traditional combustion chemistry, and therefore require new and creative solutions. The application of plasma to combustion systems offers a promising solution, with significant enhancement having been shown by many researchers. Nevertheless, there remain many unknowns with respect to the key species and mechanisms of enhancement. Detailed systematic experimental and numerical investigations were performed to identify the kinetic mechanisms of combustion enhancement by long-lifetime species generated by non-equilibrium plasma discharges. Two burner systems were adopted and integrated with plasma discharge devices to establish unique combustion platforms to study ignition, flame propagation, and flame stabilization phenomena. A counterflow diffusion flame burner was adopted for the investigation of the effects of plasma on flame stabilization. A newly developed non-equilibrium magnetic gliding arc plasma discharge was integrated with a counterflow diffusion flame burner and was found to significantly extend the limits of flame stabilization when activating air. Laser diagnostic methods of planar Rayleigh scattering and OH planar laser-induced fluorescence were applied and comparison to numerical simulations showed that the extension of the extinction limits was predominately through thermal effects due to rapid recombination of radicals. To elucidate the kinetic effects of plasma, the counterflow burner was augmented for ignition experiments. The application of Fourier transform infrared spectroscopy and comparison to numerical simulations showed significant kinetic ignition enhancement by plasma-produced NOx when activating air. The results established the existence of new ignition regimes for NO x addition that were strongly dependent upon the strain rates (residence times) in the system. The addition of small concentrations of fuel to the air upstream of the plasma produced fuel fragments and partially oxidized products that inhibited ignition. The dominating effects of plasma-produced NOx significantly mitigated the inhibitive effects of these species on chain-branching reaction pathways. To further decouple the plasma-flame interaction, the two long-lifetime plasma species of O3 and O2(a1Delta g) were produced, isolated, measured, and transported to a lifted flame burner to investigate their effect on flame propagation speed. The effects of O3 at atmospheric and sub-atmospheric pressure were found to be significant because of the decomposition of O3 releasing O to rapidly react with the fuel and extract chemical heat early in the pre-heat zone of the flame. The effect of O2(a1Delta g) was isolated by the addition of NO to the plasma afterglow to eliminate O3 and O catalytically. The O2(a1Delta g) was isolated, measured quantitatively using high sensitivity off-axis integrated cavity output absorption spectroscopy, and observed to enhance flame speed. The comparison of experimental and numerical simulation results showed that the current enhancement mechanism including O2(a 1Deltag) could not accurately explain the increase in flame speed observed. Furthermore, a novel filter system was developed to minimize the concentration of all plasma-produced species other than O3 and O2(a1Deltag) through gas phase and wall surface quenching. Lastly, a new simplified and well-defined plasma-combustion system was developed to provide a platform to study the plasma-flame interaction. In addition, a flow visualization technique was proposed by using plasma activation and NO seeding which could be applied to a system where particle seeding of the flow is prohibitive.
Response to "Comment on `The ion-kinetic D'Angelo mode'" [Phys. Plasmas 22, 044703 (2015)
NASA Astrophysics Data System (ADS)
Chibisov, D. V.; Mikhailenko, V. S.
2015-04-01
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.
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”
Ahmad, Mushtaq; Ahmad, Nasim; Riaz, Amjad; Anzar, Muhammad
2014-02-28
This study was designed to compare the kinetics of sperm survival in different types of bull semen. Fresh ejaculates from four bulls were pooled, diluted in Tris-citric acid-egg yolk-glycerol extender, cooled to 4°C, frozen in LN2 and thawed at 37°C. Fresh, diluted, cooled and frozen-thawed semen were incubated at 37°C, and evaluated at 0, 2, 4, 6, 12 and 24h after the beginning of incubation. In Experiment 1, progressive sperm motility, normal acrosomes and plasma membrane integrity and asymmetry were determined. In Experiment 2, generation of superoxide anion (O2•) along with plasma membrane permeability and generation of hydrogen peroxide (H2O2) along with plasma membrane integrity were assessed. In Experiment 1, frozen-thawed semen had shorter survival times for progressive sperm motility, and spermatozoa with intact plasma membranes and acrosomes (IPM-IACR) as compared with other types of semen (P2•- generation and increased plasma membrane permeability, and became necrotic without H2O2 generation during incubation (P2•-, which increased the permeability and compromised the integrity of the plasma membrane. PMID:24576435
Ebrahimi, V.; Esfandyari-Kalejahi, A. [Department of Physics, Faculty of Sciences, Azarbaijan Shahid Madani University, 53714-161 Tabriz (Iran, Islamic Republic of)
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.
Kagan, A; Bar-Khayim, Y; Schafer, Z; Fainaru, M
1990-03-01
We quantified the plasma levels and peritoneal loss of lipids and lipoproteins, and studied the composition of plasma and effluent lipoproteins in 16 patients on CAPD (5 females and 11 males, 18 to 76 years old). Five patients were studied prospectively (at 0, 1, 3 and 6 months) and 11 patients at 6 to 58 months on CAPD (N = 30). Elevated levels of plasma VLDL and reduced levels of plasma HDL were maintained in these patients throughout 58 months of CAPD, whereas the initially increased LDL levels showed a tendency towards normalization. All plasma lipoproteins (VLDL, IDL, LDL and HDL) were present in the peritoneal effluent. The lipoproteins isolated from plasma and peritoneal fluid shared a similar lipid and apolipoprotein composition. The peritoneal transport characteristics of plasma lipoproteins were similar to other plasma macromolecules. Their clearance correlated with their molecular mass, plasma concentration and dwell time, but was not affected by duration of CAPD treatment. The plasma lipid and lipoprotein levels were unaffected by the rate of glucose absorption. The peritoneal protein clearance correlated positively with plasma levels of triglyceride and LDL, and negatively with plasma HDL. An inverse correlation was observed also between plasma levels of HDL and its peritoneal clearance (r = -0.393, P less than 0.025, N = 30). The continuous peritoneal loss of HDL and the hypertriglyceridemia were found to contribute most to the persistent low plasma levels of HDL in CAPD patients, and thus may lead to the accelerated atherosclerosis observed in these patients. PMID:2313985
Killian, Thomas C.
Electron Screening and Kinetic-Energy Oscillations in a Strongly Coupled Plasma Y. C. Chen, C. E of Physics and Astronomy, Rice University, Houston, Texas 77005, USA and Rice Quantum Institute, Rice; published 20 December 2004) We study equilibration of strongly coupled ions in an ultracold neutral plasma
Advances in electron kinetics and theory of gas discharges
Kolobov, Vladimir I. [CFD Research Corporation, Huntsville, Alabama 35805 (United States) [CFD Research Corporation, Huntsville, Alabama 35805 (United States); The University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States)
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.
NASA Astrophysics Data System (ADS)
Cartier-Michaud, T.; Ghendrih, P.; Sarazin, Y.; Dif-Pradalier, G.; Drouot, T.; Estève, D.; Garbet, X.; Grandgirard, V.; Latu, G.; Norscini, C.; Passeron, C.
2014-11-01
A minimum model of plasma turbulence in a kinetic framework is presented. It is based on trapped ion turbulence, gyro and bounce averaged, and implemented in the versatile and efficient code TERESA. Zonal flow - streamer interplay are readily shown to be key players that govern the confinement properties of the model. The parameter space of the model is explored with brute force numerics. A generic result is either a streamer dominated pattern with large transport, or a staircase temperature profile with very marked corrugations and quenched transport. A case with off-axis heating is found to exhibit quasiperiodic relaxation events relevant to investigate dynamical turbulence self-organisation.
A Landau fluid model for electromagnetic plasma microturbulence P.B. Snyder
Hammett, Greg
A Landau fluid model for electromagnetic plasma microturbulence P.B. Snyder General Atomics, P that is being submitted to Physics of Plasmas. A fluid model is developed for the description of microturbulence fluctuations, as well as finite Larmor radius and kinetic effects. Multi-species Landau fluid equations
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.
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.
Kinetic model for molecular contaminant effects in closed cycle, nonequilibrium MHD generators
T. C. Dellinger; E. L. Gray
1978-01-01
The paper outlines the development of a theoretical kinetic model for the energy transfer mechanisms pertinent to an inert gas (Ar)-alkali seeded (Cs or K) nonequilibrium plasma containing, either individually or as a mixture, the molecular contaminants N2, CO, CO2 and H2O. The kinetic formulation includes a description of both the relaxation and the steady-state phenomena. To determine the relaxation
Terpstra, A H; Stucchi, A F; Nicolosi, R J
1991-06-01
We studied the kinetic parameters of high density lipoprotein (HDL) cholesteryl esters in the cebus monkey, an animal species with high plasma cholesteryl ester transfer activity. HDL were radiolabeled with cholesteryl [1-14C]oleate and intravenously administered to 4 cebus monkeys. The calculated fractional catabolic rate (FCR) of the HDL cholesteryl esters was 0.081 +/- 0.002 (mean +/- SD) h-1 and the calculated residence time was 12.3 +/- 0.3 h. The production or disposal rate of plasma HDL cholesteryl esters was 34.3 +/- 4.5 mumol/h. The radiolabeled cholesteryl esters were rapidly transferred from the HDL to the very low and low density lipoproteins (VLDL + LDL) and the amount of tracer in the VLDL + LDL had already reached a maximum at 3.5 +/- 0.7 h after tracer administration. The estimated fraction of VLDL + LDL cholesteryl esters derived from the HDL was 0.77 +/- 0.06. We also used radiolabeled [1,2-3H(N)]cholesteryl palmityl ether to trace HDL cholesteryl esters, but the ether tracer was more slowly cleared from the plasma and less readily transferred between plasma lipoproteins than the ester tracer. PMID:1892490
Li, Ling; Nouraldeen, Amr; Wilson, Alan G E
2013-03-01
1.?In this manuscript we describe a non-radioactive, high-throughput method to evaluate hepatic uptake using cryopreserved hepatocytes. We have validated the uptake of pravastatin with different amounts of hepatocytes and the impact of the oil layer used in separation. The time- and concentration-dependent uptake profiles of several anionic and cationic charged drugs were evaluated. The results with our method compare favourably with the literature for pravastatin, atorvastatin and estrone 3-sulfate. 2.?Two approaches for kinetic determination (temperature difference and fitting the linear and non-saturable passive diffusion rate in the equation, i.e. V = (V(max) × S)/(K(m) + S) + P(dif) × S) have been evaluated. Kinetic studies indicate that the different approaches for determining passive diffusion can affect K(m) and V(max), but not the clearance of active uptake (V(max)/K(m)). 3.?Using pravastatin as a probe substrate, species differences were observed in the organic anion-transporting polypeptide (OATP) 1B1 and 1B3 activities. Plasma protein significantly reduced the uptake of atorvastatin, but not pravastatin. 4.?Our data suggests that evaluation of the role of active uptake in hepatic clearance in humans should consider the relative ratio of active uptake to passive diffusion, species differences and plasma protein binding when applying in vitro uptake data. PMID:22928802
NASA Astrophysics Data System (ADS)
Pfefferle, David; Aiba, Nobuyuki; Graves, Jonathan P.; Cooper, Wilfred A.
2014-10-01
In the framework of hybrid kinetic-MHD with plasma rotation, this project focuses on computing, via a delta-f PIC scheme, the non-adiabatic contribution to the MHD pressure tensor from supra-thermal populations. The orbit code VENUS-LEVIS is employed to evolve an ensemble of weighted markers in the rotating magnetic equilibria produced by the MHD stability code MINERVA. The linearly perturbed Vlasov equation is solved by evolving the marker weights in the presence of MINERVA's most unstable MHD modes. Moments of the perturbed distribution are sequenced to yield the hot ion kinetic response. The Laplace transform of the perturbed parallel and perpendicular pressure is calculated at the resonance as a function of the radial position and the poloidal and toroidal mode number. The resulting profiles are fed back into MINERVA as an additional source term in the MHD force balance equation. The mode structure, the frequency and the growth rate of the perturbations are modified due to resonances with the hot particles' bounce/transit motion and their toroidal precession drift. The effect of toroidal plasma rotation on the mode stability is assessed.
Harilal, S. S.
Environment, School of Nuclear Engineering, Purdue University, West Lafayette 47907, USA E-mail: vsizyuk surface sputtering, melt and vaporization erosion, plasma contamination and component failure that can-facing and structural materi
Fillingim, Matthew
plasma parameters. One of the most compelling science issue in the PSBL region concerns the sources space distribution functions as the primary data product. The main purpose of this article as the primary data product. This approach has yielded new information on the plasma dynamics not revealed
Wang, Xiaozhi; Qian, Xiaoqing; Stumpf, Beate; Fatima, Ammara; Feng, Ke; Schubert, Sven; Hanstein, Stefan
2013-10-01
P-type ATPases, as major consumers of cellular ATP in eukaryotic cells, are characterized by the formation of a phosphorylated enzyme intermediate (E2P), a process that is allosterically coupled to translocation of cations against an electrochemical gradient. The catalytic cycle comprises binding of Mg-ATP at the nucleotide-binding domain, phosphorylation of the E1 state (E1), conformational transition to the E2P state, and dephosphorylation through the actuator domain and re-establishment of the E1 state. Recently, it has been suggested that, for several P-type ATPases, Mg-ATP binds to the phosphorylated enzyme, thereby accelerating the transition to the E1 state, before then becoming the enzyme's catalytic substrate. Here, we provide evidence supporting this viewpoint. We employed kinetic models based on steady-state kinetics in the presence and absence of the reversible inhibitor orthovanadate. Vanadate is generally considered to be a conformational probe that specifically binds to the E2 state, arresting the enzyme in a state analogous to the E2P state. Hydrolytic H(+) -ATPase activities were measured in inside-out plasma membrane vesicles isolated from roots and shoots of maize plants. For root enzymes, kinetic models of vanadate inhibition that allow simultaneous binding of Mg-ATP and vanadate to the same enzyme state were most plausible. For shoot enzymes, application of the competitive inhibitor Mg-free ATP attenuated vanadate inhibition, which is consistent with a model in which either Mg-free ATP or Mg-ATP is bound to the enzyme when vanadate binds. Therefore, data from roots and shoots indicate that binding of ATP species before transition to the E1 state plays an important role in the catalytic cycle of plant plasma membrane H(+) -ATPase. PMID:23879673
Meziani, T.; Colpo, P.; Rossi, F. [European Commission-Joint Research Centre, IHCP, TP 203, Via E. Fermi 1, 21020 Ispra (Vatican City State, Holy See,) (Italy)
2006-02-01
The magnetic pole enhanced inductively coupled source (MaPE-ICP) is an innovative low-pressure plasma source that allows for high plasma density and high plasma uniformity, as well as large-area plasma generation. This article presents an electrical characterization of this source, and the experimental measurements are compared to the results obtained after modeling the source by the equivalent circuit of the transformer. In particular, the method applied consists in performing a reverse electromagnetic modeling of the source by providing the measured plasma parameters such as plasma density and electron temperature as an input, and computing the total impedance seen at the primary of the transformer. The impedance results given by the model are compared to the experimental results. This approach allows for a more comprehensive refinement of the electrical model in order to obtain a better fitting of the results. The electrical characteristics of the system, and in particular the total impedance, were measured at the inductive coil antenna (primary of the transformer). The source was modeled electrically by a finite element method, treating the plasma as a conductive load and taking into account the complex plasma conductivity, the value of which was calculated from the electron density and electron temperature measurements carried out previously. The electrical characterization of the inductive excitation source itself versus frequency showed that the source cannot be treated as purely inductive and that the effect of parasitic capacitances must be taken into account in the model. Finally, considerations on the effect of the magnetic core addition on the capacitive component of the coupling are made.
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.
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.
Hsu, Albert T; Barrett, Christopher D; DeBusk, George M; Ellson, Christian D; Gautam, Shiva; Talmor, Daniel S; Gallagher, Diana C; Yaffe, Michael B
2015-08-01
Primed neutrophils that are capable of releasing matrix metalloproteinases (MMPs) into the circulation are thought to play a significant role in the pathophysiology of acute respiratory distress syndrome (ARDS). We hypothesized that direct measurement of plasma MMP-9 activity may be a predictor of incipient tissue damage and subsequent lung injury, which was investigated in both an animal model of ARDS and a small cohort of 38 critically ill human patients. In a mouse model of ARDS involving instillation of intratracheal lipopolysaccharide (LPS) to induce lung inflammation, we measured neutrophil-mediated inflammation, along with MMP-9 activity in the airways and lung tissue and MMP-9 expression in the plasma. Neutrophil recruitment, inflammation, and MMP-9 activity in the airways and lung tissue increased throughout the 72 h after LPS instillation, whereas plasma MMP-9 expression was greatest at 12 to 24 h after LPS instillation. The results suggest that the peak in plasma MMP-9 activity may precede the peak of neutrophil inflammation in the airways and lung tissue in the setting of ARDS. Based on this animal study, a retrospective observational cohort study involving 38 patients admitted to a surgical intensive care unit at a tertiary care university hospital with acute respiratory failure requiring intubation and mechanical ventilation was conducted. Plasma samples were collected daily, and MMP-9 activity was compared with lung function as determined by the PaO2/FiO2 ratio. In patients who developed ARDS, a notable increase in plasma MMP-9 activity on a particular day correlated with a decrease in the PaO2/FiO2 ratio on the following day (r = -0.503, P < 0.006). Taken together, these results suggest that plasma MMP-9 activity changes, as a surrogate for primed neutrophils may have predictive value for the development of ARDS in a selected subset of critically ill patients. PMID:26009816
Interplanetary and interstellar plasma turbulence
A. A. Schekochihin; S. C. Cowley; W. Dorland
2006-10-26
Theoretical approaches to low-frequency magnetized turbulence in collisionless and weakly collisional astrophysical plasmas are reviewed. The proper starting point for an analytical description of these plasmas is kinetic theory, not fluid equations. The anisotropy of the turbulence is used to systematically derive a series of reduced analytical models. Above the ion gyroscale, it is shown rigourously that the Alfven waves decouple from the electron-density and magnetic-field-strength fluctuations and satisfy the Reduced MHD equations. The density and field-strength fluctuations (slow waves and the entropy mode in the fluid limit), determined kinetically, are passively mixed by the Alfven waves. The resulting hybrid fluid-kinetic description of the low-frequency turbulence is valid independently of collisionality. Below the ion gyroscale, the turbulent cascade is partially converted into a cascade of kinetic Alfven waves, damped at the electron gyroscale. This cascade is described by a pair of fluid-like equations, which are a reduced version of the Electron MHD. The development of these theoretical models is motivated by observations of the turbulence in the solar wind and interstellar medium. In the latter case, the turbulence is spatially inhomogeneous and the anisotropic Alfvenic turbulence in the presence of a strong mean field may coexist with isotropic MHD turbulence that has no mean field.
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.
Caride, Ariel J.; Filoteo, Adelaida G.; Penniston, John T.; Strehler, Emanuel E.
2008-01-01
The inhibition by the regulatory domain and the interaction with calmodulin (CaM) vary among plasma membrane calcium pump (PMCA) isoforms. To explore these differences, the kinetics of CaM effects on PMCA4a were investigated and compared with those of PMCA4b. The maximal apparent rate constant for CaM activation of PMCA4a was almost twice that for PMCA4b, while the rates of activation for both isoforms showed similar dependence on Ca2+. The inactivation of PMCA4a by CaM removal was also faster than for PMCA4b, and Ca2+ showed a much smaller effect (2- vs. 30-fold modification). The rate constants of the individual steps that determine the overall rates were obtained from stopped-flow experiments in which binding of TA-CaM was observed by changes in its fluorescence. TA-CaM binds to two conformations of PMCA4a, an “open” conformation with high activity, and a “closed” one with lower activity. Compared with PMCA4b (Penheiter et al. (2003) Biochemistry 41:12115–12124), the model for PMCA4a predicts less inhibition in the closed form and a much faster equilibrium between the open and closed forms. Based on the available kinetic parameters, we determined the constants to fit the shape of a Ca2+ signal in PMCA4b-overexpressing CHO cells. Using the constants for PMCA4a, and allowing small variations in parameters of other systems contributing to a Ca2+ signal, we then simulated the effect of PMCA4a on the shape of a Ca2+ signal in CHO cells. The results reproduce the published data (Brini et al. (2003) J. Biol. Chem. 278:24500–24508), and thereby demonstrate the importance of altered regulatory kinetics for the different functional properties of PMCA isoforms. PMID:17595168
1987-01-01
We measured simultaneously in single toad rods the membrane photocurrent and the Ca concentration in a small volume surrounding the outer segment. Illumination causes a rise in the extracellular Ca concentration. Photocurrents and Ca concentration changes occur over the same range of light intensities. Analysis of the time course of the Ca concentration changes suggests that these concentration changes arise from the difference in the transport rates of light-activated Ca influx and efflux across the outer segment plasma membrane. The Ca influx occurs through the light-sensitive channels of the outer segment membrane and the efflux through Na/Ca exchangers. In 0.1 mM external Ca, approximately 1-2% of the dark current is carried by Ca ions. The Ca efflux in the dark is identical to the influx, approximately 2 X 10(6) ions/s. Upon illumination, the Ca influx decreases with a time course and light sensitivity identical to those of the photocurrent. The Ca efflux, on the other hand, has very different kinetics from those of the photocurrent. Upon illumination, the Ca efflux decreases with a time course and light sensitivity determined by the change in membrane voltage and in the free cytoplasmic Ca concentration near the plasma membrane. In response to bright stimuli, which saturate the photocurrent for prolonged periods of time, the Ca efflux decays with an exponential time course from its value in darkness. The average time constant of this decay is 2.5 s. From the kinetics of the light- activated Ca fluxes, it is possible to predict that illumination causes a decrease in the cytoplasmic Ca concentration. We present a model of the regulation of the cytoplasmic Ca concentration by the dynamic balance of the Ca influx and efflux from the rod outer segment. The model accounts for our experimental observations and allows us to predict the time course and extent of the light-dependent decrease in the free cytoplasmic concentration. PMID:3116153
Eric Choiniere
2004-01-01
A steady-state kinetic computational model is developed, allowing for self-consistent simulations of collisionless, unmagnetized flowing plasmas in a vast region surrounding any two-dimensional conductive object. An optimization approach is devised based on a stable, noise-robust Tikhonov-regularized Newton method. Dynamic, adaptive, unstructured meshing allows arbitrary geometries and adequate resolution of plasma sheath features. A 1-D cylindrical solver (KiPS-1D) and a full
Kinetic 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 where there are large gradients in density, pressure and magnetic #12;eld. As compressional waves. In the magnetosheath substantial ULF compressional wave activity exists nearly all of the time, and under most
Kinetic 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 where there are large gradients in density, pressure and magnetic field. As compressional waves an ongoing issue. In the magnetosheath substantial ULF compressional wave activity exists nearly all
Technology Transfer Automated Retrieval System (TEKTRAN)
Background: The search for a reliable, convenient indicator of Zn status has been the focus of research for several decades. Plasma Zn concentration is still the most widely used clinical measurement, despite the known problems of interpretation. More recently, it has been sugggested that isotopi...
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
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
A model is presented that describes the kinetics of the oxidation of micropollutants in water with the combination of ozone and hydrogen peroxide in a sparged, semi batch reactor. he model is based on known reactions of the O3/H2O2 system plus mass-transfer characteristics of the...
Ziemkiewicz, J. [Space Research Center, Warsaw (Poland)] [Space Research Center, Warsaw (Poland)
1995-09-01
A shock in a collisionless plasma should be treated as a place where the superthermal particles are continuously produced. The Rankine-Hugoniot conditions modified so as to describe the loss of the energy flux during the production process are presented. The model of the interaction between the two colliding shocks in the collisionless magnetized plasma is used to describe the behavior of the heliospheric termination shock. Both forward-reverse and reverse-reverse shock pairs are considered. In consequence of these interactions the termination shock is in a constant in and out motion with velocities equal to 100-200 km/s. The dependence of the interaction parameters on the production efficiency of the superthermal population is discussed. 15 refs., 6 figs.
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).
NASA Astrophysics Data System (ADS)
Huebner, Marko; Gorchakov, Sergej; Loffhagen, Detlef; Guaitella, Olivier; Marinov, Daniil; Rousseau, Antoine; Roepcke, Juergen; INP Greifswald, Germany Team; LPP, Ecole Polytechnique, France Collaboration
2014-10-01
The formation of NO has been studied measuring the temporal evolution of the density of NO, NO2 and N2O by high time-resolved quantum cascade laser absorption spectroscopy. The densities of these nitrous oxides have been measured in synthetic air as well as in air with an admixture of 1% of NO2 and N2O, respectively, at a pressure of 1.33 mbar and mean currents between 50 and 150 mA. The measured time-dependent densities of NO, NO2 and N2O have been compared with those calculated by means of a self-consistent numerical model. The modelling approach includes the coupled solution of the time-dependent electron Boltzmann equation and a system of rate equations for various heavy particles. In general, measured and calculated results show good qualitatively agreement. In total four distinct phases of the NO density evolution during the plasma pulse and the early afterglow are found. The densities of NO2 and N2O decrease exponentially during the plasma pulse and remain almost constant in the afterglow. The admixture of NO2 has a remarkable impact on the NO production during the ignition of the plasma. The dominating processes are presented and discussed.
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.
A Multi Water Bag model of drift kinetic electron plasmaa
NASA Astrophysics Data System (ADS)
Morel, Pierre; Ghiro, Florent Dreydemy; Berionni, Vincent; Coulette, David; Besse, Nicolas; Gürcan, Özgür D.
2014-08-01
A Multi Water Bag model is proposed for describing drift kinetic plasmas in a magnetized cylindrical geometry, relevant for various experimental devices, solar wind modeling... The Multi Water Bag (MWB) model is adapted to the description of a plasma with kinetic electrons as well as an arbitrary number of kinetic ions. This allows to describe the kinetic dynamics of the electrons, making possible the study of electron temperature gradient (ETG) modes, in addition to the effects of non adiabatic electrons on the ion temperature gradient (ITG) modes, that are of prime importance in the magnetized plasmas micro-turbulence [X. Garbet, Y. Idomura, L. Villard, T.H. Watanabe, Nucl. Fusion 50, 043002 (2010); J.A. Krommes, Ann. Rev. Fluid Mech. 44, 175 (2012)]. The MWB model is shown to link kinetic and fluid descriptions, depending on the number of bags considered. Linear stability of the ETG modes is presented and compared to the existing results regarding cylindrical ITG modes [P. Morel, E. Gravier, N. Besse, R. Klein, A. Ghizzo, P. Bertrand, W. Garbet, Ph. Ghendrih, V. Grandgirard, Y. Sarazin, Phys. Plasmas 14, 112109 (2007)].
Tsiklauri, D. [Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)
2011-09-15
Dispersive Alfven waves (DAWs) offer, an alternative to magnetic reconnection, opportunity to accelerate solar flare particles in order to alleviate the problem of delivering flare energy to denser parts of the solar atmosphere to match x-ray observations. Here, we focus on the effect of DAW polarisation, left, right, circular and elliptical, in the different regimes inertial and kinetic, aiming to study these effects on the efficiency of particle acceleration. We use 2.5D particle-in-cell simulations to study how the particles are accelerated when DAW, triggered by a solar flare, propagates in the transversely inhomogeneous plasma that mimics solar coronal loop. (1) In the inertial regime, fraction of accelerated electrons (along the magnetic field) in the density gradient regions is {approx_equal}20% by the time when DAW develops three wavelengths and is increasing to {approx_equal}30% by the time when DAW develops thirteen wavelengths. In all considered cases, ions are heated in the transverse to the magnetic field direction and fraction of heated particles is {approx_equal}35%. (2) The case of right circular, left and right elliptical polarisation DAWs, with the electric field in the non-ignorable transverse direction exceeding several times that of in the ignorable direction, produce more pronounced parallel electron beams (with larger maximal electron velocities) and transverse ion beams in the ignorable direction. In the inertial regime, such polarisations yield the fraction of accelerated electrons 20%. In the kinetic regime, this increases to 35%. (3) The parallel electric field that is generated in the density inhomogeneity regions is independent of the electron-ion mass ratio and stays of the order 0.03 {omega}{sub pe}cm{sub e}/e which for solar flaring plasma parameters exceeds Dreicer electric field by eight orders of magnitude. (4) Electron beam velocity has the phase velocity of the DAW. Thus, electron acceleration is via Landau damping of DAWs. For the Alfven speeds of V{sub A} = 0.3c, the considered mechanism can accelerate electrons to energies circa 20 keV. (5) The increase of mass ratio from m{sub i}/m{sub e} = 16 to 73.44 increases fraction of accelerated electrons from 20% to 30-35% (depending on DAW polarisation). For the mass ratio m{sub i}/m{sub e} = 1836, the fraction of accelerated electrons would be >35%. (6) DAWs generate significant density and temperature perturbations that are located in the density gradient regions. DAWs propagating in the transversely inhomogeneous plasma can effectively accelerate electrons along the magnetic field and heat ions across it.
Kinetic Equations, Moment Closures, and Fluid Regimes
Maryland at College Park, University of
@math.umd.edu Kinetic FRG Young Researchers Workshop: Kinetic Description of Multiscale Phenomena: Modeling, Theory; · be solved more efficiently than the full kinetic equation. #12;Uses of Transition Regime Models Such a modelKinetic Equations, Moment Closures, and Fluid Regimes C. David Levermore Department of Mathematics
Vaks, V. G. Zhuravlev, I. A.
2012-10-15
Basic equations of diffusional kinetics in alloys are statistically derived using the master equation approach. To describe diffusional transformations in substitution alloys, we derive the 'quasi-equilibrium' kinetic equation that generalizes its earlier versions by taking possible 'interaction renormalization' effects into account. For the interstitial alloys Me-X, we derive an explicit expression for the diffusivity D of an interstitial atom X. This expression notably differs from those used in previous phenomenological treatments. This microscopic expression for D is applied to describe the diffusion of carbon in austenite based on some simple models of carbon-carbon interaction. The results obtained enable us to make certain conclusions about the real form of these interactions and about the scale of the 'transition state entropy' for diffusion of carbon in austenite.
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.
Landau Fluid Models for Magnetized Plasmas
Sulem, P. L.; Passot, T.; Marradi, L. [Universite de Nice Sophia Antipolis, CNRS Observatoire de la Cote d'Azur, BP 4229, 06304 Nice Cedex 4 (France)
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.
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.
NASA Astrophysics Data System (ADS)
Royle, Ryan; Sentoku, Yasuhiko
2014-10-01
An intense, hard X-ray laser such as an XFEL is an attractive light source since it can directly heat solid matter isochorically to a temperature of millions of degrees on a time scale of a few tens of femtoseconds, which is much shorter than the plasma expansion time scale. The X-ray laser interaction with carbon, aluminum, silicon, and copper 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 non-thermal photoelectrons are produced with energy near the X-ray photon energy. The photoelectrons' stopping range is a few microns and they are quickly thermalized in tens of femtoseconds. As a result, a hot plasma column is formed behind the laser pulse with a temperature of more than 100,000 kelvin (>10 eV) and energy density greater than 1011 J/m3. The heating depth and temperature depend on the material and are also controllable by changing the photon energy of the incident laser light.
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
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.
Magnetospheric space plasma investigations
NASA Astrophysics Data System (ADS)
Comfort, Richard H.; Horwitz, James L.
1995-02-01
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.
The Lunar dusty plasmas -levitation and transport.
NASA Astrophysics Data System (ADS)
Atamaniuk, Barbara; Rothkaehl, Hanna
Lunar dust can exhibit unusual behavior -due to electron photoemission via solar-UV radiation the lunar surface represents a complex plasma -"dusty plasma". The dust grains and lunar surface are electrostatically charged by the Moon's interaction with the local plasma environ-ment and the photoemission of electrons due to solar UV and X-rays. This effect causes the like-charged surface and dust particles to repel each other, and creates a near-surface electric field. Lunar dust must be treated as a dusty plasma. Using analytic (kinetic (Vlasov) and magnetohydrodynamic theory ) and numerical modeling we show physical processes related to levitation and transport dusty plasma on the Moon. These dust grains could affect the lunar environment for radio wave and plasma diagnostics and interfere with exploration activities. References: 1. Wilson T.L. (1992), in Analysis of Interplanetary Dust, M. Zolensky et al. AIP Conf.Proc. 310, 33-44 (AIP, NY), 2.Wilson T.L."LUNAR DUST AND DUSTY PLASMA PHYSICS".40th Lunar and Planetary Science Conference (2009), 3. Grün E., et al.(1993),Nature 363, 144. 4. Morfill G. and Grün E.(1979), Planet. Space Sci.. 27, 1269, 1283, 5. Manka R. and Michel F. (1971), Proc. 2nd Lun. Sci. Conf. 2, 1717 (MIT Press, Cambridge). 6. Manka R. et al.(1973), Lun. Sci.-III, 504. 7. Barbara Atamaniuk "Kinetic Description of Localized Plasma Structure in Dusty Plasmas". Czechoslovak Journal of Physics Vol.54 C 2004
NASA Astrophysics Data System (ADS)
Sukumar, Harikrishnan
Tungsten is a leading candidate material for the diverter in future nuclear fusion reactors. Previous experiments have demonstrated that surface defects and bubbles form in tungsten when ex- posed to helium and hydrogen plasmas, even at modest ion energies. In some regimes, between 1000K and 2000K, and for He energies below 100eV, "fuzz" like features form. The mechanisms leading to these surfaces comprised of nanometer sized tungsten tendrils which include visible helium bubbles are not currently known. The role of helium bubble formation in tendril morphology could very likely be the starting point of these mechanisms. Using Molecular dynamics (MD) simulations, the role of helium and hydrogen exposure in the initial formation mechanisms of tungsten "fuzz" are investigated. Molecular dynamics simulations are well suited to describe the time and length scales associated with initial formation of helium clusters that eventually grow to nano-meter sized helium bubbles. MD simulations also easily enable the modeling of a variety of surfaces such as single crystals, grain boundaries or "tendrils". While the sputtering yield of tungsten is generally low, previous observations of surface modification due to plasma exposure raise questions about the effects of surface morphology and sub-surface helium bubble populations on the sputtering behavior. Results of computational molecular dynamics are reported that investigate the influence of sub-surface helium bubble distributions on the sputtering yield of tungsten (100) and (110) surfaces induced by helium ion exposure in the range of 300 eV to 1 keV. The calculated sputtering yields are in reasonable agreement with a wide range of experimental data; but do not show any significant variation as a result of the pre-existing helium bubbles. Molecular dynamics simulations reveal a number of sub-surface mechanisms leading to nanometer- sized "fuzz" in tungsten exposed to low-energy helium plasmas. We find that during the bubble formation process, helium clusters create self-interstitial defect clusters in tungsten by a trap mutation process, followed by the migration of these defects to the surface that leads to the formation of layers of adatom islands on the tungsten surface. As the helium clusters grow into nanometer sized bubbles, their proximity to the surface and extremely high gas pressures can cause them to rupture the surface thus enabling helium release. Helium bubble bursting induces additional surface damage and tungsten mass loss which varies depending on the nature of the surface. We then show tendril-like geometries have surfaces that are more resilient to helium clustering and bubble formation and rupture. Finally, the study includes hydrogen to reveal the effect of a mixed 90%H-10%He plasma mix on the tungsten surface. We find that hydrogen greatly affects the tungsten surface, with a near surface hydrogen saturation layer, and that helium clusters still form and are attractive trapping sites for hydrogen. Molecular dynamics simulations have also investigated the effect of sub-surface helium bubble evolution on tungsten surface morphology. The helium bubble/tungsten surface interaction has been systematically studied to determine how parameters such as bubble shape and size, temperature, tungsten surface orientation and ligament thickness above the bubble impact bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom islands, craters and pinholes. The study provides insight into the mechanisms and conditions leading to various tungsten topology changes, most notably the formation of nanoscale fuzz. An atomistic study of the mechanisms behind initial phases of tungsten nano-fuzz growth has determined that tungsten surfaces are affected by sub-displacement energy helium and hydrogen fluxes through a series of mechanisms. Sub-surface helium atom clustering, bubble nucleation, growth and rupture lead to tungsten surface deformation. Helium clustering processes vary near grain boundaries o
Caride, Ariel J; Filoteo, Adelaida G; Penniston, John T; Strehler, Emanuel E
2007-08-31
The inhibition by the regulatory domain and the interaction with calmodulin (CaM) vary among plasma membrane calcium pump (PMCA) isoforms. To explore these differences, the kinetics of CaM effects on PMCA4a were investigated and compared with those of PMCA4b. The maximal apparent rate constant for CaM activation of PMCA4a was almost twice that for PMCA4b, whereas the rates of activation for both isoforms showed similar dependence on Ca2+. The inactivation of PMCA4a by CaM removal was also faster than for PMCA4b, and Ca2+ showed a much smaller effect (2- versus 30-fold modification). The rate constants of the individual steps that determine the overall rates were obtained from stopped-flow experiments in which binding of TA-CaM was observed by changes in its fluorescence. TA-CaM binds to two conformations of PMCA4a, an "open" conformation with high activity, and a "closed" one with lower activity. Compared with PMCA4b (Penheiter, A. R., Bajzer, Z., Filoteo, A. G., Thorogate, R., Török, K., and Caride, A. J. (2003) Biochemistry 41, 12115-12124), the model for PMCA4a predicts less inhibition in the closed form and a much faster equilibrium between the open and closed forms. Based on the available kinetic parameters, we determined the constants to fit the shape of a Ca2+ signal in PMCA4b-overexpressing Chinese hamster ovary cells. Using the constants for PMCA4a, and allowing small variations in parameters of other systems contributing to a Ca2+ signal, we then simulated the effect of PMCA4a on the shape of a Ca2+ signal in Chinese hamster ovary cells. The results reproduce the published data (Brini, M., Coletto, L., Pierobon, N., Kraev, N., Guerini, D., and Carafoli, E. (2003) J. Biol. Chem. 278, 24500-24508), and thereby demonstrate the importance of altered regulatory kinetics for the different functional properties of PMCA isoforms. PMID:17595168
Wulff, W; Cheng, H S; Diamond, D J; Khatib-Rahbar, M
1984-01-01
This report documents the physical models and the numerical methods employed in the BWR systems code RAMONA-3B. The RAMONA-3B code simulates three-dimensional neutron kinetics and multichannel core hydraulics of nonhomogeneous, nonequilibrium two-phase flows. RAMONA-3B is programmed to calculate the steady and transient conditions in the main steam supply system for normal and abnormal operational transients, including the performances of plant control and protection systems. Presented are code capabilities and limitations, models and solution techniques, the results of development code assessment and suggestions for improving the code in the future.
NASA Astrophysics Data System (ADS)
Béland, Laurent Karim; Mousseau, Normand
2013-12-01
Diffusion and relaxation of defects in bulk systems is a complex process that can only be accessed directly through simulations. We characterize the mechanisms of low-temperature aging in self-implanted crystalline silicon, a model system used extensively to characterize both amorphization and return to equilibrium processes, over 11 orders of magnitudes in time, from 10 ps to 1 s, using a combination of molecular dynamics and kinetic activation-relaxation technique simulations. These simulations allow us to reassess the atomistic mechanisms responsible for structural relaxations and for the overall logarithmic relaxation, a process observed in a large number of disordered systems and observed here over the whole simulation range. This allows us to identify three microscopic regimes, annihilation, aggregation, and reconstruction, in the evolution of defects and to propose atomistic justification for an analytical model of logarithmic relaxation. Furthermore, we show that growing activation barriers and configurational space exploration are kinetically limiting the system to a logarithmic relaxation. Overall, our long-time simulations do not support the amorphous cluster model but point rather to a relaxation driven by elastic interactions between defect complexes of all sizes.
NASA Astrophysics Data System (ADS)
Stamm, Alexander; Shadwick, Bradley
2014-10-01
The recent variational technique for rigorously deriving discrete, self-consistent equations for electromagnetic particle codes has been further developed in the moving window. The primary advantage of the Lagrangian formulation is the connection between symmetries of the system and conservation laws, which in the present case resolves the grid-heating issue. However, the approach also simplifies coordinate transformations and enables the particle method to be formulated in moving window coordinates. For some laser-plasma interaction scenarios, this leads to computational savings from working in a coordinate system where the evolution of the laser is intrinsically slow. New time advance integrators were developed in this coordinate system and compared to one another; namely, a symplectic method and a split explicit particle and implicit field advance method were developed in the moving window to show the extent of available optimization and improvements over the traditional particle-in-cell (PIC) method. In addition, we examine the phase-space fidelity of our method in cases where the conventional PIC algorithm exhibits unphysical particle trapping. This work was supported by the DoE under Grant DE-SC0008382 and by the NSF under Grant PHY-1104683.
NASA Astrophysics Data System (ADS)
Lazar, M.; Poedts, S.; Schlickeiser, R.; Dumitrache, C.
2015-01-01
Measured in situ, the particle velocity distributions in the solar wind plasma reveal two distinct components: a Maxwellian (thermal) core, and a less dense but hotter suprathermal halo with a power-law distribution described by Lorentzian/Kappa distribution function. Despite this evidence, the existing attempts to parametrize anisotropic distributions and the resulting wave instabilities are limited to idealized models, which either ignore the suprathermal populations, or minimize the core, assuming it is cold. Here, a more realistic approach is identified, combining an isotropic Maxwellian core and an anisotropic bi-Kappa halo. This model is relevant at large heliocentric distances and for the slow winds, when the field-aligned strahl is less pronounced and kinetic energy densities in the core and halo are comparable. A comparative study with the cold-core-based model is performed on the electron whistler-cyclotron instability driven by the anisotropic halo. Derived exactly numerically, the instability thresholds and growth rates confirm the expectation that cyclotron instabilities are inhibited by the core thermal spread. This effect is enhanced by the increase of the halo-core relative density with heliocentric distance, suggesting that local conditions for this instability to develop at large radial distances in the solar wind are less favourable than predicted before.
NASA Astrophysics Data System (ADS)
Arkhipov, A. S.; Bishaev, A. M.
2012-10-01
A numerical method is constructed for solving the system of kinetic equations describing the behavior of a rarefied plasma jet exhausted from a Hall thruster. A similar problem was previously considered in the steady case. Now the same problem is solved in the unsteady formulation. The numerical method is based on a generalization of the splitting method with respect to physical processes, which is widely used in rarefied gas dynamics. The basic difficulty faced in the natural generalization of this method as applied to thruster jets is that a boundary condition has to be taken into account when the ion distribution function is determined. This difficulty is overcome by analytically selecting the corresponding term at the stage of free-molecular motion. Another difficulty that can be coped with by the splitting method is that the ion and neutral velocity spaces have widely different scales. Techniques for making the method conservative are described, and situations in which this is necessary are discussed. Qualitative characteristics of some numerical computations are compared with experimental data. The comparison shows that the numerical method constructed adequately reproduces the behavior of the modeled object.
Catto, P.J. (Massachusetts Institute of Technology, Plasma Fusion Center, 167 Albany Street, NW16-236, Cambridge, Massachusetts 02139 (United States)); Connor, J.W. (UKAEA Government Division, Fusion (Euratom/UKAEA Fusion Association), Culham, Abingdon, Oxfordshire, OX143DB (United Kingdom))
1995-01-01
Earlier two-dimensional (radial and poloidal angle), analytically tractable ion kinetic models of the scrape-off layer (SOL) in which a steady state is achieved by balancing the streaming loss of ions to the divertor target plates with the radial diffusion of ions from the core are unable to distinguish between limited and diverted plasmas. The model presented here removes this limitation while still remaining amenable to a similar Wiener--Hopf solution procedure. To phenomenologically model ion recycling, the boundary conditions employed at the divertor plates allow for partial reflection. The diffusion into the private flux region and the extended divertor channels (all of normalized length [ital d] along the magnetic field), as well as the rest of the SOL, is evaluated. The SOL is shown to be asymmetric about the separatrix because ions from the core must stream by the X point be- fore diffusing into the private flux region. The channel or leg SOL width is of order [[ital LD](1+2[ital d])/[ital v][sub [ital i
Lombardi, Andrea; Faginas-Lago, Noelia; Pacifici, Leonardo; Costantini, Alessandro
2013-11-14
We present extended applications of an established theoretical and computational machinery suitable for the study of the dynamics of CO2+CO2 collisions, focusing on vibrational energy exchange, considered over a wide range of energies and rotational temperatures. Calculations are based on quasi-classical trajectories on a potential energy function (a critical component of dynamics simulations), tailored to accurately describe the intermolecular interactions, modeled by the recently proposed bond-bond semiempirical formulation that allows the colliding molecules to be stretchable, rather than frozen at their equilibrium geometry. In a previous work, the same potential energy surface has been used to show that modifications in the geometry (and in physical properties such as polarizability and charge distribution) of the colliding partners affect the intermolecular interaction and determine the features of the energy exchange, to a large extent driven by long-range forces. As initial partitioning of the energy among the molecular degrees of freedom, we consider the excitation of the vibrational bending mode, assuming an initial rotational distribution and a rotational temperature. The role of the vibrational angular momentum is also carefully assessed. Results are obtained by portable implementations of this approach in a Grid-computing framework and on high performance platforms. Cross sections are basic ingredients to obtain rate constants of use in advanced state-to-state kinetic models, under equilibrium or nonequilibrium conditions, and this approach is suitable for gas dynamics applications to plasmas and modeling of hypersonic flows. PMID:24117231
Water bag modeling of a multispecies plasma
Morel, P.; Gravier, E.; Besse, N.; Klein, R.; Ghizzo, A.; Bertrand, P. [Institut Jean Lamour, UMR 7198 CNRS-Universite Henri Poincare, F-54506 Vandoeuvre-les-Nancy Cedex (France); Bourdelle, C.; Garbet, X. [Association EURATOM-CEA, CEA/DSM/IRFM, CEA Cadarache, Saint-Paul-lez-Durance, F-13108 Cedex (France)
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.
A Landau fluid model for electromagnetic plasma microturbulence P. B. Snydera)
Hammett, Greg
A Landau fluid model for electromagnetic plasma microturbulence P. B. Snydera) General Atomics, P A fluid model is developed for the description of microturbulence and transport in magnetized, long mean radius and kinetic effects. Multispecies Landau fluid equations are derived from moments
Parallel Implicit Kinetic Simulation with PARSEK
Markidis Stefano; Lapenta Giovanni
2004-01-01
Kinetic plasma simulation is the ultimate tool for plasma analysis. One of the prime tools for kinetic simulation is the particle in cell (PIC) method. The explicit or semi-implicit (i.e. implicit only on the fields) PIC method requires exceedingly small time steps and grid spacing, limited by the necessity to resolve the electron plasma frequency, the Debye length and the
Alfven Waves in Gyrokinetic Plasmas
W.W. Lee; H. Qin
2003-04-14
A brief comparison of the properties of Alfven waves that are based on the gyrokinetic description with those derived from the MHD equations is presented. The critical differences between these two approaches are the treatment of the ion polarization effects. As such, the compressional Alfven waves in a gyrokinetic plasma can be eliminated through frequency ordering, whereas geometric simplifications are needed to decouple the shear Alfven waves from the compressional Alfven waves within the context of MHD. Theoretical and numerical procedures of using gyrokinetic particle simulation for studying microturbulence and kinetic-MHD physics including finite Larmor radius effects are also presented.
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
Davidson, Ronald C
2015-01-01
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 $r_{w}$. The average axial electric field is expressed as $\\langle E_{z}\\rangle=-(\\partial/\\partial z)\\langle\\phi\\rangle=-e_{b}g_{0}\\partial\\lambda_{b}/\\partial z-e_{b}g_{2}r_{w}^{2}\\partial^{3}\\lambda_{b}/\\partial z^{3}$, where $g_{0}$ and $g_{2}$ are constant geometric factors, $\\lambda_{b}(z,t)=\\int dp_{z}F_{b}(z,p_{z},t)$ 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 (solitons) 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: (a) the nonlinear waterbag distribution, w...
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
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.
Gabriel, Richard P.
A descriptive formalism along with a philosophy for its use and expansion are presented wherein descriptions are of a highly structured nature. This descriptive system and the method of recognition are extended to the ...
NASA Astrophysics Data System (ADS)
Gray, Patrick J.; Olesik, John W.
2015-03-01
Reaction gas flow rate dependent Ar2+ and Ar+ signals are correlated to fundamental kinetic rate coefficients. A simple calculation, assuming that gas exits the reaction cell due only to effusion, is described to estimate the gas pressure in the reaction cell. The value of the product of the kinetic rate constant and the ion residence time in the reaction cell can be determined from experimental measurement of the decrease in an ion signal as a function of reaction gas flow rate. New kinetic rate constants are determined for the reaction of CH3F with Ar+ and Ar2+.
ERIC Educational Resources Information Center
Burgardt, Erik D.; Ryan, Hank
1996-01-01
Presents a unit on chemical reaction kinetics that consists of a predemonstration activity, the demonstration, and a set of postdemonstration activities that help students transfer the concepts to actual chemical reactions. Simulates various aspects of chemical reaction kinetics. (JRH)
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)
BOOK REVIEW: Physics of Strongly Coupled Plasma
NASA Astrophysics Data System (ADS)
Kraeft, Wolf-Dietrich
2007-07-01
Strongly coupled plasmas (or non-ideal plasmas) are multi-component charged many-particle systems, in which the mean value of the potential energy of the system is of the same order as or even higher than the mean value of the kinetic energy. The constituents are electrons, ions, atoms and molecules. Dusty (or complex) plasmas contain still mesoscopic (multiply charged) particles. In such systems, the effects of strong coupling (non-ideality) lead to considerable deviations of physical properties from the corresponding properties of ideal plasmas, i.e., of plasmas in which the mean kinetic energy is essentially larger than the mean potential energy. For instance, bound state energies become density dependent and vanish at higher densities (Mott effect) due to the interaction of the pair with the surrounding particles. Non-ideal plasmas are of interest both for general scientific reasons (including, for example, astrophysical questions), and for technical applications such as inertially confined fusion. In spite of great efforts both experimentally and theoretically, satisfactory information on the physical properties of strongly coupled plasmas is not at hand for any temperature and density. For example, the theoretical description of non-ideal plasmas is possible only at low densities/high temperatures and at extremely high densities (high degeneracy). For intermediate degeneracy, however, numerical experiments have to fill the gap. Experiments are difficult in the region of `warm dense matter'. The monograph tries to present the state of the art concerning both theoretical and experimental attempts. It mainly includes results of the work perfomed in famous Russian laboratories in recent decades. After outlining basic concepts (chapter 1), the generation of plasmas is considered (chapter 2, chapter 3). Questions of partial (chapter 4) and full ionization (chapter 5) are discussed including Mott transition and Wigner crystallization. Electrical and optical properties are the topics of chapters 6 to 8, followed by problems of metallization (chapter 9), non-neutral and dusty plasmas (chapter 10, chapter 11). References follow after each chapter. The book is of interest for obtaining an overview of the field, and is recommended reading. However, for more detailed information on special (theoretical) topics, one should go into the literature. Little is said with respect to kinetic theory, to the theory of ionization kinetics, to stopping power, effective potentials, and to spectral lines in dense plasmas. The interaction between laser or particle beams and plasmas and the evaluation of the results discussing Hugoniots is only touched on briefly. Astrophysics is not dealt with at all. Some misprints concerning names and years in the references may cause difficulties.
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.
Kinetic energy in a system of particles with a nonreciprocal interaction
NASA Astrophysics Data System (ADS)
Vaulina, Olga S.; Lisina, Irina I.; Lisin, Evgeny A.
2015-09-01
We present a theoretical model for the description of the heating mechanism and the redistribution of kinetic energy in a system of particles with nonreciprocal interactions that occur in disperse systems of different nature. To verify the theory, we carried out the numerical simulations of two-particle systems with a nonreciprocal “quasi-dipole–dipole” interaction that is similar to the interaction due to the effect of ion focusing in a laboratory complex plasma under experimental conditions. The proposed model of heating can explain various features of dust dynamics in anisotropic complex plasma.
Ion temperature in plasmas with intrinsic Alfven waves
Wu, C. S. [CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei (China); Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of); Wang, C. B. [CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei (China)
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.
Ion temperature in plasmas with intrinsic Alfven waves
NASA Astrophysics Data System (ADS)
Wu, C. S.; Yoon, P. H.; Wang, C. B.
2014-10-01
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.
C. Bobeldijk; R. J. J. van Heinjningen
1973-01-01
From 3rd international symposium on toroidal plasma confinement; ; Garching, Germany (26 Mar 1973). A description is given of a Screw Pinch ; Confinement Apparatus with radii R = 60 cm, r = 20 cm. SPICA is designed to ; study the long-term stability of screw pinches with temperatures in the order of ; 300 eV, surrounded by a current-carrying
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.
D. Tsiklauri
2011-01-01
Dispersive Alfven waves (DAWs) offer, an alternative to magnetic reconnection, opportunity to accelerate solar flare particles in order to alleviate the problem of delivering flare energy to denser parts of the solar atmosphere to match x-ray observations. Here, we focus on the effect of DAW polarisation, left, right, circular and elliptical, in the different regimes inertial and kinetic, aiming to
Kinetic Damping of Toroidal Alfven Eigenmodes
G.Y. Fu; H.L. Berk; A. Pletzer
2005-05-03
The damping of Toroidal Alfven Eigenmodes in JET plasmas is investigated by using a reduced kinetic model. Typically no significant damping is found to occur near the center of the plasma due to mode conversion to kinetic Alfven waves. In contrast, continuum damping from resonance near the plasma edge may be significant, and when it is, it gives rise to damping rates that are compatible with the experimental observations.