CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Plasma Descriptions I
Callen, James D.
CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Chapter 5 Plasma Descriptions I: Kinetic, Two-Fluid Descriptions of plasmas are obtained from extensions of the kinetic theory of gases of charged particles in the plasma, and because the electric and magnetic fields in the plasma must
Consistent description of kinetics and hydrodynamics of dusty plasma
Markiv, B. [Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv (Ukraine)] [Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv (Ukraine); Tokarchuk, M. [Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv (Ukraine) [Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv (Ukraine); National University “Lviv Polytechnic,” 12 Bandera St., 79013 Lviv (Ukraine)
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. [Russian Academy of Sciences, Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Russian Federation)
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.
Active plasma resonance spectroscopy: a kinetic functional analytic description
NASA Astrophysics Data System (ADS)
Oberrath, J.; Brinkmann, R. P.
2014-08-01
The term active plasma resonance spectroscopy (APRS) denotes a class of related techniques which utilize, for diagnostic purposes, the natural ability of plasmas to resonate on or near the electron plasma frequency ?pe: a radio frequent signal (in the GHz range) is coupled into the plasma via an antenna or probe, the spectral response is recorded, and a mathematical model is used to determine plasma parameters such as the electron density or the electron temperature. This paper provides a kinetic description of APRS valid for all pressures and probe geometries. Subject of the description is the interaction of the probe with the plasma of its influence domain. In a first step, the kinetic free energy of that domain is established which has a definite time derivative with respect to the radio frequency (RF) power. In the absence of RF excitation, it assumes the properties of a Lyapunov functional; its minimum provides the stable equilibrium of the plasma-probe system. Equipped with a scalar product motivated by the second variation of the free energy, the set of all perturbations of the equilibrium forms a Hilbert space. The dynamics of the perturbations can be cast in an evolution equation in that space. The spectral response function of the plasma-probe system consists of matrix elements of the resolvent of the dynamical operator. An interpretation in terms of an equivalent electric circuit model is given and the residual broadening of the spectrum in the collisionless regime is explained.
Kinetic description of electron plasma waves with orbital angular momentum
NASA Astrophysics Data System (ADS)
Mendonça, J. T.
2012-11-01
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.
Kinetic description of electron plasma waves with orbital angular momentum
Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2012-11-15
We describe the kinetic theory of electron plasma waves with orbital angular momentum or twisted plasmons. The conditions for a twisted Landau resonance to exist are established, and this concept is introduced for the first time. Expressions for the kinetic dispersion relation and for the electron Landau damping are derived. The particular case of a Maxwellian plasma is examined in detail. The new contributions to wave dispersion and damping due the orbital angular momentum are discussed. It is shown that twisted plasmons can be excited by rotating electron beams.
Cremaschini, Claudio [International School for Advanced Studies (SISSA) and INFN, Trieste (Italy); Tessarotto, Massimo [Department of Mathematics and Informatics, University of Trieste (Italy)
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.
NASA Astrophysics Data System (ADS)
Cremaschini, Claudio; Miller, John C.; Tessarotto, Massimo
2011-06-01
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.
Cremaschini, Claudio [International School for Advanced Studies (SISSA), Trieste 34136 (Italy); Miller, John C. [International School for Advanced Studies (SISSA) and INFN, Trieste 34136, Italy and Department of Physics (Astrophysics), University of Oxford, Oxford OX1 3RH (United Kingdom); Tessarotto, Massimo [Department of Mathematics and Informatics, University of Trieste, Trieste 34127 (Italy)
2011-06-15
A kinetic treatment is developed for collisionless magnetized plasmas occurring in high-temperature, low-density astrophysical accretion disks, such as are thought to be present in some radiatively inefficient accretion flows onto black holes. Quasi-stationary configurations are investigated, within the framework of a Vlasov-Maxwell description. The plasma is taken to be axisymmetric and subject to the action of slowly time-varying gravitational and electromagnetic fields. The magnetic field is assumed to be characterized by a family of locally nested but open magnetic surfaces. The slow collisionless dynamics of these plasmas is investigated, yielding a reduced gyrokinetic Vlasov equation for the kinetic distribution function. For doing this, an asymptotic quasi-stationary solution is first determined, represented by a generalized bi-Maxwellian distribution expressed in terms of the relevant adiabatic invariants. The existence of the solution is shown to depend on having suitable kinetic constraints and conditions leading to particle trapping phenomena. With this solution, one can treat temperature anisotropy, toroidal and poloidal flow velocities, and finite Larmor-radius effects. An asymptotic expansion for the distribution function permits analytic evaluation of all the relevant fluid fields. Basic theoretical features of the solution and their astrophysical implications are discussed. As an application, the possibility of describing the dynamics of slowly time-varying accretion flows and the self-generation of magnetic field by means of a ''kinetic dynamo effect'' are discussed. Both effects are shown to be related to intrinsically kinetic physical mechanisms.
On description of quantum plasma
S. V. Vladimirov; Yu. O. Tyshetskiy
2011-01-21
A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)
Fluid description of non-local electron kinetics in inductively coupled plasmas
NASA Astrophysics Data System (ADS)
Hagelaar, G. J. M.
2008-05-01
Due to thermal motion, the electrons in inductively coupled plasmas (ICPs) show a non-local response to the electromagnetic field, which gives rise to the anomalous skin effect and stochastic heating. In a recent letter (Hagelaar G J M 2008 Phys. Rev. Lett. 100 025001) we have shown that this can be approximately described through a fluid equation for electron momentum including a viscosity term with an effective viscosity coefficient. The present paper provides a more extensive presentation and discussion of our effective viscosity fluid approach. We present analytical solutions of the improved fluid equations coupled to the Maxwell equations for a semi-infinite plasma, showing scaling laws for the non-monotonic spatial structure of the anomalous skin and a condition for the appearance of local negative power absorption. We also present a numerical comparison with a particle-in-cell model, including non-linear effects due to the ponderomotive force. Consistent results are obtained for a wide range of conditions. The proposed equations have a simple form and could be of practical use for ICP modeling.
Ramos, J. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge Massachusetts 02139-4307 (United States)
2010-08-15
A closed theoretical model to describe slow, macroscopic plasma processes in a fusion-relevant collisionality regime is set forward. This formulation is a hybrid one, with fluid conservation equations for particle number, momentum and energy, and drift-kinetic closures. Intended for realistic application to the core of a high-temperature tokamak plasma, the proposed approach is unconventional in that the ion collisionality is ordered lower than in the ion banana regime of neoclassical theory. The present first part of a two-article series concerns the electron system, which is still equivalent to one based on neoclassical electron banana orderings. This system is derived such that it ensures the precise compatibility among the complementary fluid and drift-kinetic equations, and the rigorous treatment of the electric field and the Fokker-Planck-Landau collision operators. As an illustrative application, the special limit of an axisymmetric equilibrium is worked out in detail.
Ramos, J. J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States)
2011-10-15
The ion side of a closed, fluid and drift-kinetic theoretical model to describe slow and macroscopic plasma processes in a fusion-relevant, low collisionality regime is presented. It follows the ordering assumptions and the methodology adopted in the companion electron theory [Ramos, Phys. Plasmas 17, 082502 (2010)]. To reach the frequency scale where collisions begin to play a role, the drift-kinetic equation for the ion distribution function perturbation away from a Maxwellian must be accurate to the second order in the Larmor radius. The macroscopic density, flow velocity and temperature are accounted for in the Maxwellian, and are evolved by a fluid system which includes consistently the gyroviscous part of the stress tensor and second-order contributions to the collisionless perpendicular heat flux involving non-Maxwellian fluid moments. The precise compatibility among these coupled high-order fluid and drift-kinetic equations is made manifest by showing that the evolution of the non-Maxwellian part of the distribution function is such that its first three velocity moments remain equal to zero.
CHAPTER 6. PLASMA DESCRIPTIONS II: MHD 1 Plasma Descriptions II
Callen, James D.
for the electromagnetic fields. The main equations, properties and applications of the MHD model are developed conditions (Section 6.4), dynamical responses (Section 6.5), and the Alfv`en waves (Section 6.6) that result:31 January 28, 2003 c J.D Callen, Fundamentals of Plasma Physics #12;CHAPTER 6. PLASMA DESCRIPTIONS II: MHD 2
Lagrangian description of warm plasmas
NASA Technical Reports Server (NTRS)
Kim, H.
1970-01-01
Efforts are described to extend the averaged Lagrangian method of describing small signal wave propagation and nonlinear wave interaction, developed by earlier workers for cold plasmas, to the more general conditions of warm collisionless plasmas, and to demonstrate particularly the effectiveness of the method in analyzing wave-wave interactions. The theory is developed for both the microscopic description and the hydrodynamic approximation to plasma behavior. First, a microscopic Lagrangian is formulated rigorously, and expanded in terms of perturbations about equilibrium. Two methods are then described for deriving a hydrodynamic Lagrangian. In the first of these, the Lagrangian is obtained by velocity integration of the exact microscopic Lagrangian. In the second, the expanded hydrodynamic Lagrangian is obtained directly from the expanded microscopic Lagrangian. As applications of the microscopic Lagrangian, the small-signal dispersion relations and the coupled mode equations are derived for all possible waves in a warm infinite, weakly inhomogeneous magnetoplasma, and their interactions are examined.
Propagation of radiation in fluctuating multiscale plasmas. I. Kinetic theory
Tyshetskiy, Yu.; Pal Singh, Kunwar; Thirunavukarasu, A.; Robinson, P. A.; Cairns, Iver H. [School of Physics, University of Sydney, NSW 2006 (Australia)
2012-11-15
A theory for propagation of radiation in a large scale plasma with small scale fluctuations is developed using a kinetic description in terms of the probability distribution function of the radiation in space, time, and wavevector space. Large scale effects associated with spatial variations in the plasma density and refractive index of the plasma wave modes and small scale effects such as scattering of radiation by density clumps in fluctuating plasma, spontaneous emission, damping, and mode conversion are included in a multiscale kinetic description of the radiation. Expressions for the Stokes parameters in terms of the probability distribution function of the radiation are used to enable radiation properties such as intensity and polarization to be calculated.
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.
Kinetic equation for spin-polarized plasmas
Cowley, S.C.; Kulsrud, R.M.; Valeo, E.
1984-07-01
The usual kinetic description of a plasma is extended to include variables to describe the spin. The distribution function, over phase-space and the new spin variables, provides a sufficient description of a spin-polarized plasma. The evolution equation for the distribution function is given. The equations derived are used to calculate depolarization due to four processes, inhomogeneous fields, collisions, collisions in inhomogeneous fields, and waves. It is found that depolarization by field inhomogeneity on scales large compared with the gyroradius is totally negligible. The same is true for collisional depolarization. Collisions in inhomogeneous fields yield a depolarization rate of order 10/sup -4/S/sup -1/ for deuterons and a negligible rate for tritons in a typical fusion reactor design. This is still sufficiently small on reactor time scales. However, small amplitude magnetic fluctuations (of order one gauss) resonant with the spin precession frequency can lead to significant depolarization (depolarises triton in ten seconds and deuteron in a hundred seconds.)
NLTE4 Plasma Population Kinetics Database
National Institute of Standards and Technology Data Gateway
SRD 159 NLTE4 Plasma Population Kinetics Database (Web database for purchase) This database contains benchmark results for simulation of plasma population kinetics and emission spectra. The data were contributed by the participants of the 4th Non-LTE Code Comparison Workshop who have unrestricted access to the database. The only limitation for other users is in hidden labeling of the output results. Guest users can proceed to the database entry page without entering userid and password.
Complete Spectrum of Kinetic Eigenmodes for Plasma
Ng, Chung-Sang
Complete Spectrum of Kinetic Eigenmodes for Plasma Oscillations in a Weakly Collisional Plasma C. S damping rate measured with a discrete spectrum. Ng, Bhattacharjee, & Skiff (1999): discrete collisional spectrum found numerically which tends to Landau spectrum as collision tends to zero. Short & Simon (2002
A fluid description of plasma double-layers
NASA Technical Reports Server (NTRS)
Levine, J. S.; Crawford, F. W.
1979-01-01
The space-charge double-layer that forms between two plasmas with different densities and thermal energies was investigated using three progressively realistic models which are treated by fluid theory, and take into account four species of particles: electrons and ions reflected by the double-layer, and electrons and ions transmitted through it. The two plasmas are assumed to be cold, and the self-consistent potential, electric field and space-charge distributions within the double-layer are determined. The effects of thermal velocities are taken into account for the reflected particles, and the modifications to the cold plasma solutions are established. Further modifications due to thermal velocities of the transmitted particles are examined. The applicability of a one dimensional fluid description, rather than plasma kinetic theory, is discussed. Theoretical predictions are compared with double layer potentials and lengths deduced from laboratory and space plasma experiments.
Growth kinetics of plasma-polymerized films.
Hwang, Sukyoung; Seo, Hosung; Jeong, Dong-Cheol; Wen, Long; Han, Jeon Geon; Song, Changsik; Kim, Yunseok
2015-01-01
The growth kinetics of polymer thin films prepared by plasma-based deposition method were explored using atomic force microscopy. The growth behavior of the first layer of the polythiophene somewhat differs from that of the other layers because the first layer is directly deposited on the substrate, whereas the other layers are deposited on the polymer itself. After the deposition of the first layer, each layer is formed with a cycle of 15?s. The present work represents the growth kinetics of the plasma-polymerized films and could be helpful for further studies on growth kinetics in other material systems as well as for applications of plasma-polymerized thin films. PMID:26084630
Growth kinetics of plasma-polymerized films
Hwang, Sukyoung; Seo, Hosung; Jeong, Dong-Cheol; Wen, Long; Han, Jeon Geon; Song, Changsik; Kim, Yunseok
2015-01-01
The growth kinetics of polymer thin films prepared by plasma-based deposition method were explored using atomic force microscopy. The growth behavior of the first layer of the polythiophene somewhat differs from that of the other layers because the first layer is directly deposited on the substrate, whereas the other layers are deposited on the polymer itself. After the deposition of the first layer, each layer is formed with a cycle of 15?s. The present work represents the growth kinetics of the plasma-polymerized films and could be helpful for further studies on growth kinetics in other material systems as well as for applications of plasma-polymerized thin films. PMID:26084630
Atomic population kinetics in fluctuating plasmas
NASA Astrophysics Data System (ADS)
Catoire, F.; Rosato, J.; Marandet, Y.; Koubiti, M.; Mekkaoui, S.; Capes, H.; Stamm, R.
2012-11-01
A kinetic model for atomic populations in a turbulent plasma is developed in the framework of the so-called continuous time random walk theory. A special emphasis is devoted to the role of temperature fluctuations. With an application to the 1s, 2s and 2p levels of atomic hydrogen, we demonstrate that a resonance effect can be observed.
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,
Nonlocal electron kinetics in collisional gas discharge plasmas
Vladimir I. Kolobov; Valery A. Godyak
1995-01-01
Nonlocal phenomena in electron kinetics of collisional gas discharge plasmas, their kinetic treatment by a nonlocal approach, and relevant experimental results are reviewed in this paper. Using the traditional two-term approximation for the electron distribution function, a general method to analyze electron kinetics in nonuniform plasmas in DC and RF fields for atomic gases is presented for the nonlocal case,
Kinetic effects in Enceladus plasma environment
NASA Astrophysics Data System (ADS)
Stverak, Stepan; Travnicek, Pavel M.; Sebek, Ondrej; Hellinger, Petr; Khurana, Krishan
2015-04-01
The southern plume of Enceladus represents a significant source of neutrals, ions and dust for the neighboring plasma environment and even for the inner magnetosphere of Saturn. The ion mass loading rate from the plume is not only confirmed by direct plasma measurements but can also be deduced from the strong signatures observed on the Kronian magnetospheric background magnetic field. In view of recent knowledge, namely based on in situ observations provided by numerous Cassini flybys, we try to model numerically and reconstruct the complex plasma environment in the vicinity of the moon by use of a full 3-dimensional hybrid code. With obtained results we attempt to investigate the role of kinetic effects in generation of the ion-cyclotron waves instantaneously observed by the Cassini spacecraft.
Kinetic Theory of Dawson Plasma Sheet Model
NASA Astrophysics Data System (ADS)
Sano, Mitsusada M.; Kitahara, Kazuo
2011-08-01
A kinetic theory of one-dimensional plasma sheet model (Dawson model) is developed. The Vlasov equation, the Landau equation, and the Balescu--Lenard equation corresponding to this model are derived. For the Vlasov equation, it is shown that the linearized Vlasov equation exhibits a typical behavior of plasmas as in the three-dimensional space. The Landau collision term and the Balescu--Lenard collision term are identically zero. The fact of the vanishing collision term agrees with the behavior of generic one-dimesional systems. In an approximation that the system is in a thermal bath, the derived Landau equation and Balescu--Lenard equation are transformed into the Fokker--Planck equations. Some physical quantities such as thermal conductivity, relaxation rate, etc., are estimated. A discussion on physical meaning of these results, in particular, the zero collision terms, will be given.
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
Physical Principles of Kinetic Modeling of Plasma Display Panels
NASA Astrophysics Data System (ADS)
Arslanbekov, Robert; Kolobov, Vladimir; Kudryavtsev, Anatoly; Tsendin, Lev
2001-10-01
The plasma display panel (PDP) cells usually feature a short glow discharge with no positive column (PC). Typically, the product pressure--length of PDP cell pL ~ 5 cmTorr, whereas those of the cathode fall (CF) and negative glow (NG) are, respectively, ~1.3--1.4 and 3--6 cmTorr in He. The ionization and excitation take place mostly in the NG and are produced by fast electrons streaming from the CF. These fast (non-equilibrium) electrons determine the PDP luminescence characteristics. The weak electric field in the NG is reversed to trap (and cool) most of electrons. The key parameter is the electron temperature Te which must be calculated at the kinetic level, taking into account the distribution of superthermal electrons, heating by these electrons in Coulomb interactions and diffusion cooling. The spatial pattern of ionization in the transition region between the Faraday dark space and PC may become periodic, and the formation can take place, via kinetic mechanisms, of the standing striations similar to those observed in experiment. The description of the PDP must therefore be consistently kinetic and nonlocal for the whole electron ensemble, the fluid (or global) and local-field-approximation (LFA) models being physically inappropriate. In this paper, we present an analytical model of PDP and describe the application of a deterministic Boltzmann solver.
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.
Contrib. Plasma Phys. 41 (2001) 2-3, 259-262 Quantum Kinetic Theory of Laser Plasmas
Bonitz, Michael
2001-01-01
Contrib. Plasma Phys. 41 (2001) 2-3, 259-262 Quantum Kinetic Theory of Laser Plasmas D. Krempa perturbation theory. 1 Generalized kinetic equation The classical kinetic theory of plasmas in time dependent.kremp@physik.uni-rostock.de Received 29 September 2000, in final form 8 December 2000 Abstract A quantum kinetic equation for plasmas
Kinetic plasma modeling with quiet Monte Carlo direct simulation.
Albright, B. J. (Brian J.); Jones, M. E. (Michael E.); Lemons, D. S. (Don S.); Winske, D. (Dan)
2001-01-01
The modeling of collisions among particles in space plasma media poses a challenge for computer simulation. Traditional plasma methods are able to model well the extremes of highly collisional plasmas (MHD and Hall-MHD simulations) and collisionless plasmas (particle-in-cell simulations). However, neither is capable of trealing the intermediate, semi-collisional regime. The authors have invented a new approach to particle simulation called Quiet Monte Carlo Direct Simulation (QMCDS) that can, in principle, treat plasmas with arbitrary and arbitrarily varying collisionality. The QMCDS method will be described, and applications of the QMCDS method as 'proof of principle' to diffusion, hydrodynamics, and radiation transport will be presented. Of particular interest to the space plasma simulation community is the application of QMCDS to kinetic plasma modeling. A method for QMCDS simulation of kinetic plasmas will be outlined, and preliminary results of simulations in the limit of weak pitch-angle scattering will be presented.
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.
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.
Kinetic instability of ion acoustic mode in permeating plasmas
Vranjes, J.; Poedts, S. [Center for Plasma Astrophysics and Leuven Mathematical Modeling and Computational Science Center (LMCC), K. U. Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Ehsan, Zahida [Salam Chair in Department of Physics, GC University, Lahore 54000, Pakistan and Plasma Physics Group, Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)
2009-07-15
In plasmas with electron drift (current) relative to static ions, the ion acoustic wave is subject to the kinetic instability which takes place if the directed electron speed exceeds the ion acoustic speed. The instability threshold becomes different in the case of one quasineutral electron-ion plasma propagating through another static quasineutral (target) plasma. The threshold velocity of the propagating plasma may be well below the ion acoustic speed of the static plasma. Such a currentless instability may frequently be expected in space and astrophysical plasmas.
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.
Original article Compared kinetics of plasma creatine kinase activity
Boyer, Edmond
Original article Compared kinetics of plasma creatine kinase activity in rabbits after intravenous 1993) Summary ― The purpose of this study was to compare the disposition parameters of creatine muscle damage. creatine kinase / kinetics / muscle damage / rabbit Résumé ― Cinétiques comparées
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...
Kinetic Studies of Thermal Relaxation in Plasma
In Soo Ko
1987-01-01
Thermal relaxation of plasma is investigated in two cases: two dimensional magnetized plasma and three dimensional unmagnetized plasma. The generalized Lenard -Balescu equation and the Fokker-Planck equation are solved respectively. During the numerical calculation, forward time integration is used in both cases. The Lenard-Balescu equation is generalized for a magnetized plasma from the BBGKY hierarchy equation. The random phase approximation
A consistent description of kinetic equation with triangle anomaly
Shi Pu; Jian-hua Gao; Qun Wang
2011-05-06
We provide a consistent description of the kinetic equation with triangle anomaly which is compatible with the entropy principle of the second law of thermodynamics and the charge/energy-momentum conservation equations. In general an anomalous source term is necessary to ensure that the equations for the charge and energy-momentum conservation are satisfied and that the correction terms of distribution functions are compatible to these equations. The constraining equations from the entropy principle are derived for the anomaly-induced leading order corrections to the particle distribution functions. The correction terms can be determined for minimum number of unknown coefficients in one charge and two charge cases by solving the constraining equations.
Consistent description of kinetic equation with triangle anomaly
Pu Shi; Gao Jianhua; Wang Qun [Interdisciplinary Center for Theoretical Study and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)
2011-05-01
We provide a consistent description of the kinetic equation with a triangle anomaly which is compatible with the entropy principle of the second law of thermodynamics and the charge/energy-momentum conservation equations. In general an anomalous source term is necessary to ensure that the equations for the charge and energy-momentum conservation are satisfied and that the correction terms of distribution functions are compatible to these equations. The constraining equations from the entropy principle are derived for the anomaly-induced leading order corrections to the particle distribution functions. The correction terms can be determined for the minimum number of unknown coefficients in one charge and two charge cases by solving the constraining equations.
Kinetic study of ion-acoustic plasma vortices
Khan, S. A. [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad 45320 (Pakistan); Aman-ur-Rehman, E-mail: amansadiq@gmail.com [Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad 45650 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Téchnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2014-09-15
The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.
Kinetic theory of plasma sheaths surrounding electron-emitting surfaces.
Sheehan, J P; Hershkowitz, N; Kaganovich, I D; Wang, H; Raitses, Y; Barnat, E V; Weatherford, B R; Sydorenko, D
2013-08-16
A one-dimensional kinetic theory of sheaths surrounding planar, electron-emitting surfaces is presented which accounts for plasma electrons lost to the surface and the temperature of the emitted electrons. It is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. The sheath potential goes to zero as the plasma electron temperature equals the emitted electron temperature, which can occur in the afterglow of an rf plasma and some low-temperature plasma sources. These results were validated by particle in cell simulations. The theory was tested by making measurements of the sheath surrounding a thermionically emitting cathode in the afterglow of an rf plasma. The measured sheath potential shrunk to zero as the plasma electron temperature cooled to the emitted electron temperature, as predicted by the theory. PMID:23992073
Theory of spatially non-symmetric kinetic equilibria for collisionless plasmas
Cremaschini, Claudio [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy); Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezrucovo nam.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)
2013-01-15
The problem posed by the possible existence/non-existence of spatially non-symmetric kinetic equilibria has remained unsolved in plasma theory. For collisionless magnetized plasmas, this involves the construction of stationary solutions of the Vlasov-Maxwell equations. In this paper, the issue is addressed for non-relativistic plasmas both in astrophysical and laboratory contexts. The treatment is based on a Lagrangian variational description of single-particle dynamics. Starting point is a non-perturbative formulation of gyrokinetic theory, which allows one to construct 'a posteriori' with prescribed order of accuracy an asymptotic representation for the magnetic moment. In terms of the relevant particle adiabatic invariants generalized bi-Maxwellian equilibria are proved to exist. These are shown to recover, under suitable assumptions, a Chapman-Enskog form which permits an analytical treatment of the corresponding fluid moments. In particular, the constrained posed by the Poisson and the Ampere equations are analyzed, both for quasi-neutral and non-neutral plasmas. The conditions of existence of the corresponding non-symmetric kinetic equilibria are investigated. As a notable feature, both astrophysical and laboratory plasmas are shown to exhibit, under suitable conditions, a kinetic dynamo, whereby the equilibrium magnetic field can be self-generated by the equilibrium plasma currents.
The induction plasma chemical reactor: Part II. Kinetic model
G. Y. Zhao; J. Mostaghimi; M. I. Boulos
1990-01-01
A kinetic model has been developed for the prediction of the concentration gelds in an rf plasma reactor. A sample calculation for a SiCl4\\/H2 system is then performed. The model considers the mixing processes along with the kinetics of seven reactions involving the decomposition of these reactants. The results obtained are compared to those assuming chemical equilibrium. The predictions indicate
Phase Transition in Dusty Plasmas: A Microphysical Description
Glenn Joyce; Gurudas Ganguli; Martin Lampe
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=(Te\\/mi)1\\/2. Experimentally at sufficiently high gas pressure P, the random kinetic energy of the grains is damped by gas friction, and the
Electron Kinetic Effects on Raman Backscatter in Plasmas
Hur, M.S.; Suk, H. [Center for Advanced Accelerators, KERI, Changwon, Kyongnam 641-120 (Korea, Republic of); Lindberg, R.R.; Charman, A.E. [Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States); Wurtele, J.S. [Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States); Center for Beam Physics, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2005-09-09
We augment the usual three-wave cold-fluid equations governing Raman backscatter (RBS) with a new kinetic thermal correction, proportional to an average of particle kinetic energy weighted by the ponderomotive phase. From closed-form analysis within a homogeneous kinetic three-wave model and ponderomotively averaged kinetic simulations in a more realistic pulsed case, the magnitude of these new contributions is shown to be a measure of the dynamical detuning between the pump laser, seed laser, and Langmuir wave. Saturation of RBS is analyzed, and the role of trapped particles illuminated. Simple estimates show that a small fraction of trapped particles ({approx}6%) can significantly suppress backscatter. We discuss the best operating regime of the Raman plasma amplifier to reduce these deleterious kinetic effects.
Cremaschini, Claudio; Ková?, Ji?í; Slaný, Petr; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Karas, Vladimír [Astronomical Institute, Academy of Sciences, Bo?ní II, CZ-14131 Prague (Czech Republic)
2013-11-01
The possible occurrence of equilibrium off-equatorial tori in the gravitational and electromagnetic fields of astrophysical compact objects has been recently proved based on non-ideal magnetohydrodynamic theory. These stationary structures can represent plausible candidates for the modeling of coronal plasmas expected to arise in association with accretion disks. However, accretion disk coronae are formed by a highly diluted environment, and so the fluid description may be inappropriate. The question is posed of whether similar off-equatorial solutions can also be determined in the case of collisionless plasmas for which treatment based on kinetic theory, rather than a fluid one, is demanded. In this paper the issue is addressed in the framework of the Vlasov-Maxwell description for non-relativistic, multi-species axisymmetric plasmas subject to an external dominant spherical gravitational and dipolar magnetic field. Equilibrium configurations are investigated and explicit solutions for the species kinetic distribution function are constructed, which are expressed in terms of generalized Maxwellian functions characterized by isotropic temperature and non-uniform fluid fields. The conditions for the existence of off-equatorial tori are investigated. It is proved that these levitating systems are admitted under general conditions when both gravitational and magnetic fields contribute to shaping the spatial profiles of equilibrium plasma fluid fields. Then, specifically, kinetic effects carried by the equilibrium solution are explicitly provided and identified here with diamagnetic energy-correction and electrostatic contributions. It is shown that these kinetic terms characterize the plasma equation of state by introducing non-vanishing deviations from the assumption of thermal pressure.
Kinetic axisymmetric gravitational equilibria in collisionless accretion disk plasmas
Cremaschini, Claudio; Miller, John C. [International School for Advanced Studies (SISSA) and INFN, Trieste 34136 (Italy); Tessarotto, Massimo [Department of Mathematics and Informatics, Trieste University, Trieste 34127 (Italy)
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.
Kinetics of complex plasma with liquid droplets
Misra, Shikha; Sodha, M. S. [Centre of Energy Studies, Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India)] [Centre of Energy Studies, Indian Institute of Technology Delhi (IITD), New Delhi 110016 (India); Mishra, S. K. [Institute for Plasma Research (IPR), Gandhinagar 382428 (India)] [Institute for Plasma Research (IPR), Gandhinagar 382428 (India)
2013-12-15
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.
Kinetics of complex plasma with liquid droplets
NASA Astrophysics Data System (ADS)
Misra, Shikha; Mishra, S. K.; Sodha, M. S.
2013-12-01
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.
Modified Enskog kinetic theory for strongly coupled plasmas
NASA Astrophysics Data System (ADS)
Baalrud, Scott D.; Daligault, Jérôme
2015-06-01
Concepts underlying the Enskog kinetic theory of hard-spheres are applied to include short-range correlation effects in a model for transport coefficients of strongly coupled plasmas. The approach is based on an extension of the effective potential transport theory [S. D. Baalrud and J. Daligault, Phys. Rev. Lett. 110, 235001 (2013), 10.1103/PhysRevLett.110.235001] to include an exclusion radius surrounding individual charged particles that is associated with Coulomb repulsion. This is obtained by analogy with the finite size of hard spheres in Enskog's theory. Predictions for the self-diffusion and shear viscosity coefficients of the one-component plasma are tested against molecular dynamics simulations. The theory is found to accurately capture the kinetic contributions to the transport coefficients, but not the potential contributions that arise at very strong coupling (? ?30 ). Considerations related to a first-principles generalization of Enskog's kinetic equation to continuous potentials are also discussed.
Modified Enskog Kinetic Theory for Strongly Coupled Plasmas
Baalrud, Scott D
2015-01-01
Concepts underlying the Enskog kinetic theory of hard-spheres are applied to include short-range correlation effects in a model for transport coefficients of strongly coupled plasmas. The approach is based on an extension of the effective potential transport theory [S.~D.~Baalrud and J.~Daligault, Phys.~Rev.~Lett.~{\\bf 110}, 235001 (2013)] to include an exclusion radius surrounding individual charged particles that is associated with Coulomb repulsion. This is obtained by analogy with the finite size of hard spheres in Enskog's theory. Predictions for the self-diffusion and shear viscosity coefficients of the one-component plasma are tested against molecular dynamics simulations. The theory is found to accurately capture the kinetic contributions to the transport coefficients, but not the potential contributions that arise at very strong coupling ($\\Gamma \\gtrsim 30$). Considerations related to a first-principles generalization of Enskog's kinetic equation to continuous potentials are also discussed.
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.
Plasma parameters and chemical kinetics of an HCl DC glow discharge
A. M. Efremov; G. H. Kim; D. I. Balashov; C. I. Kim
2006-01-01
The investigations of plasma parameters and active particles kinetics in an HCl DC glow discharge system were carried out. The investigation combines plasma diagnostics by electric probes and plasma modeling based on the self-consistent solution of Boltzmann kinetic equation and the balance equation of chemical kinetic for neutral and charged particles. It was shown that the direct electron impact dissociation
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.
Numerical modeling of radiation physics in kinetic plasmas [I
NASA Astrophysics Data System (ADS)
Sentoku, Yasuhiko; Paraschiv, Ioana; Royle, Ryan; Pandit, Rishi; Mancini, Roberto
2014-10-01
High energy density plasmas created by ultraintense short laser light emit intense x-rays via atomic processes. There is no simulation code available to study the critical details of X-ray emission/absorption and the plasma formation with femtosecond temporal resolution. Since the plasmas are created in less than 1 ps, thermalization or equilibrium cannot be assumed so that we must treat the plasma kinetically. We have developed a novel simulation tool based on the collisional particle-in-cell (PIC) code, PICLS, in which we now solve the X-ray transport and photoionization self-consistently with the plasma dynamics. This talk introduces the idea of the numerical model of the radiation trasport and also introduces several applications such as Bremsstrahlung, K- ? emission, and XFEL-matter interaction, of which details are presented in the following talks. Supported by US DOE DE-SC0008827.
Cremaschini, Claudio, E-mail: claudiocremaschini@gmail.com; Stuchlík, Zden?k [Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic) [Faculty of Philosophy and Science, Institute of Physics, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)
2014-03-15
The kinetic description of relativistic plasmas in the presence of time-varying and spatially non-uniform electromagnetic (EM) fields is a fundamental theoretical issue both in astrophysics and plasma physics. This refers, in particular, to the treatment of collisionless and strongly-magnetized plasmas in the presence of intense radiation sources. In this paper, the problem is investigated in the framework of a covariant gyrokinetic treatment for Vlasov–Maxwell equilibria. The existence of a new class of kinetic equilibria is pointed out, which occur for spatially-symmetric systems. These equilibria are shown to exist in the presence of non-uniform background EM fields and curved space-time. In the non-relativistic limit, this feature permits the determination of kinetic equilibria even for plasmas in which particle energy is not conserved due to the occurrence of explicitly time-dependent EM fields. Finally, absolute stability criteria are established which apply in the case of infinitesimal symmetric perturbations that can be either externally or internally produced.
Non Equilbrium Vibrational Kinetics in Expanding Plasma Flows
Colonna, Gianpiero [CNR-IMIP, sede di Bari, Via Amendola 122/D, 70126, Bari (Italy)
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.
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.
NASA Astrophysics Data System (ADS)
Lipatov, Alexander
2008-03-01
We suggest a merging procedure for the Complex Particle Kinetic (CPK) model in case of inter-penetrating flow (multiple plasma beams). Each CPK macro-particle includes a Maxwellian distribution in velocity and Gaussian distribution in space with internal dynamics (see [Hewett, 2003], for details). It is assumed that an arbitrary distribution of real particles can be represented by such a superposition in phase space (moving--finite----element approach). The CPK method allows us to provide a global simulation of the complex plasma objects on the Hall-MHD (fluid) scale (aggressive merging) with automatic incorporation of the kinetic/particle description of the particle-wave processes (aggressive fragmentation) where it is necessary. The CPK approximation works well for ions, electrons, dust grains and neutral components. This code was tested in the simulations for the study of the interaction of the plasma flow with comets and Io's atmosphere. In this report we examine the standard (PIC) and the CPK methods in the case of the particle acceleration by shock surfing.
HAMILTONIAN DESCRIPTION OF FLUID AND PLASMA SYSTEMS WITH CONTINUOUS SPECTRA
Morrison, Philip J.,
#12;#12;HAMILTONIAN DESCRIPTION OF FLUID AND PLASMA SYSTEMS WITH CONTINUOUS SPECTRA P. J. MORRISON.g. Shepherd, 1990; Morrison, 1998; Marsden & Ratiu, 1999) and second, the class as a whole possesses is novel and possesses some intricacies. pedro.4.08.03.tex; 8/04/2003; 12:45; p.1 #12;2 P. J. MORRISON
Collisionless energy-independent kinetic equilibria in axisymmetric magnetized plasmas.
Cremaschini, Claudio; Stuchlík, Zden?k; Tessarotto, Massimo
2013-09-01
The proof of existence of Vlasov-Maxwell equilibria which do not exhibit a functional dependence in terms of the single-particle energy is established. The theory deals with the kinetic treatment of multispecies axisymmetric magnetized plasmas, with particular reference to plasma systems which are slowly time varying. Aside from collisionless laboratory plasmas, the theory concerns important aspects of astrophysical scenarios, such as accretion-disk and coronal plasmas arising in the gravitational field of compact objects. Qualitative properties of the solution are investigated by making use of a perturbative kinetic theory. These concern the realization of the equilibrium kinetic distribution functions in terms of generalized Gaussian distributions and the constraints imposed by the Maxwell equations. These equilibria are shown to be generally non-neutral and characterized by the absence of the Debye screening effect. As a further application, the stability properties of these equilibria with respect to axisymmetric electromagnetic perturbations are addressed. This permits us to establish absolute stability criteria holding in such a case. PMID:24125369
Electron kinetics in a cooling plasma
Helander, P.; Smith, H.; Fueloep, T.; Eriksson, L.-G. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Department of Electromagnetics, Chalmers University of Technology, 412 96 Goeteborg (Sweden); Association Euratom-CEA, CEA/DSM/DRFC, Centre de Cadarache, 13108 Saint-Paul lez Durance (France)
2004-12-01
The distribution function of suprathermal electrons in a slowly cooling plasma is calculated by an asymptotic expansion in the cooling rate divided by the collision frequency. Since the collision frequency decreases with increasing velocity, a high-energy tail forms in the electron distribution function as the bulk population cools down. Under certain simplifying assumptions (slow cooling, constant density, Born approximation of cross sections), the distribution function evolves to a self-similar state where the tail is inversely proportional to the cube of the velocity. Its practical consequences are discussed briefly.
Cremaschini, Claudio; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)] [Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)
2013-05-15
The problem of formulating a kinetic treatment for quasi-stationary collisionless plasmas in axisymmetric systems subject to the possibly independent presence of local strong velocity-shear and supersonic rotation velocities is posed. The theory is developed in the framework of the Vlasov-Maxwell description for multi-species non-relativistic plasmas. Applications to astrophysical accretion discs arising around compact objects and to plasmas in laboratory devices are considered. Explicit solutions for the equilibrium kinetic distribution function (KDF) are constructed based on the identification of the relevant particle adiabatic invariants. These are shown to be expressed in terms of generalized non-isotropic Gaussian distributions. A suitable perturbative theory is then developed which allows for the treatment of non-uniform strong velocity-shear/supersonic plasmas. This yields a series representation for the equilibrium KDF in which the leading-order term depends on both a finite set of fluid fields as well as on the gradients of an appropriate rotational frequency. Constitutive equations for the fluid number density, flow velocity, and pressure tensor are explicitly calculated. As a notable outcome, the discovery of a new mechanism for generating temperature and pressure anisotropies is pointed out, which represents a characteristic feature of plasmas considered here. This is shown to arise as a consequence of the canonical momentum conservation and to contribute to the occurrence of temperature anisotropy in combination with the adiabatic conservation of the particle magnetic moment. The physical relevance of the result and the implications of the kinetic solution for the self-generation of quasi-stationary electrostatic and magnetic fields through a kinetic dynamo are discussed.
Merging for Complex Particle Kinetic modeling of multiple plasma beams (inter-penetrating flows)
NASA Astrophysics Data System (ADS)
Lipatov, Alexander
2008-03-01
We suggest a merging procedure for the Complex Particle Kinetic (CPK) model in case of inter-penetrating flow (multiple plasma beams). Each CPK macro-particle includes a Maxwellian distribution in velocity and Gaussian distribution in space with internal dynamics (see [Hewett, 2003], for details). It is assumed that an arbitrary distribution of real particles can be represented by such a superposition in phase space (moving--finite----element approach) at least as well as could be done with the standard particle in cell (PIC)/Monte Carlo (MC) delta functions and their associated ``shape factors". The CPK method allows us to provide a global simulation of the complex plasma objects on the Hall-MHD (fluid) scale (aggressive merging) with automatic incorporation of the kinetic/particle description of the particle-wave processes (aggressive fragmentation) where it is necessary. The CPK approximation works well for ions, electrons, dust grains and neutral components. This code was tested in the simulations for the study of the interaction of the plasma flow with comets and Io's atmosphere. In this report we examine the standard (PIC) and the CPK methods in the case of the particle acceleration by shock surfing. The plasma dynamics is described by a standard (particle-ion-- fluid- electron) hybrid model. While a particle-mesh method is well enough verified approach, the CPK model seems to be a good approach in case of multiscale simulation which includes multiple subdomains with various particle/fluid plasma behavior.
Charging kinetics of dust in interplanetary space plasma
NASA Astrophysics Data System (ADS)
Misra, Shikha; Mishra, S. K.
2013-07-01
A theoretical kinetic model for the physical understanding of the charging of dust particles in the interplanetary space plasma has been developed. In contrast to earlier studies, the present analysis incorporates (i) uniform potential theory for complex plasmas with size distribution of the dust particles, (ii) charge, number and energy balance of the constituents and (iii) appropriate expressions for photoelectric emission from a positively charged particle with inherent charge neutrality of the interplanetary space plasma. Further utilizing the population balance equation (given by Matsoukas and Russel) for the interplanetary dust particles, the fluctuations in steady-state charge (or electric potential) has also been investigated. For the illustration purpose, the computations have been performed for the interplanetary space plasma at 1 au from the sun; for this distance, reasonably good information on the gaseous and dust components are available. As an interesting feature, the theoretical predictions are in reasonably good agreement with observations and earlier estimates.
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.
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 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
Kinetics of coal combustion: Part 1, Project description and summary
Gat, N. (TRW Space and Technology Group, Redondo Beach, CA (USA))
1988-12-01
The investigation of the fundamentals of coal combustion kinetics addressed several topics of major importance relative to improved understanding of pulverized coal combustion and included both homogeneous and heterogeneous reactions. The principal topics included are: (1) combustion of volatiles, and (2) heterogeneous combustion of coal/char. Research activities included small-scale experimentation, interpretation of experimental results in terms of mechanistic understanding, and the development and validation of kinetic models of fundamental processes.
Plasma kinetics in man of epicatechin from black chocolate
M Richelle; I Tavazzi; M Enslen; EA Offord
1999-01-01
Objective: To evaluate the plasma kinetics in man of epicatechin from black chocolate.Design: An intervention study with 8 volunteers. Each served as his own control. Theobromine was used as control marker of the chocolate intake.Setting: Metabolic Unit, Nestlé Research Center, Vers-chez-les-Blanc, Switzerland.Subjects: Eight healthy male volunteers (4 smokers and 4 non-smokers) were enrolled in this study. They abstained from foods
Kinetics of low-temperature plasma and gas lasers
A. A. Komar
1984-01-01
The papers contained in this volume provide an overview of experimental and theoretical research of the processes taking place in low-temperature plasmas and active media of gas lasers. Topics discussed include a study of the high-current low-pressure discharge and kinetics of processes occurring in the continuous-wave argon ion laser; collisional and radiative processes involving highly excited states of atoms and
Kinetics of low-temperature plasmas for plasma-assisted combustion and aerodynamics
NASA Astrophysics Data System (ADS)
Aleksandrov, N. L.; Kindysheva, S. V.; Kochetov, I. V.
2014-02-01
Kinetic processes in a weakly ionized non-equilibrium plasma are considered under conditions that are typical for plasma-assisted ignition/combustion and flow control. The focus is on the simulation of active species production that leads to ignition delay reduction, flame stabilization and expansion of the flammability limit of combustible mixtures. We discuss the lack of information on electron cross sections for hydrocarbons and the accuracy of widely used approaches to simulate kinetics of active species production in air and combustible mixtures. Fast gas heating after a high-voltage nanosecond discharge is studied for various gas mixtures and reduced electric fields. We analyze the effect of negative ions generated in the afterglow of a high-voltage discharge with regard to plasma-assisted ignition and plasma aerodynamics application.
Dust kinetic Alfven and acoustic waves in a Lorentzian plasma
Rubab, N.; Biernat, H. K. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz (Austria); Institute of Physics, University of Graz, Universitaetplatz 5, A-8010 Graz (Austria); Erkaev, N. V. [Institute of Computational Modelling, 660036 Krasnoyarsk, Russia and Siberian Federal University, 660041 Krasnoyarsk (Russian Federation)
2009-10-15
Dust kinetic Alfven waves (DKAWs) with finite Larmor radius effects have been examined rigorously in a uniform dusty plasma in the presence of an external magnetic field. A dispersion relation of low-frequency DKAW on the dust acoustic velocity branch is obtained in a low-{beta} Lorentzian plasma. It is found that the influence of the Lorentzian distribution function is more effective for perpendicular component of group velocity as compared with parallel one. Lorentzian-type charging currents are obtained with the aid of Vlasov theory. Damping/instability due to dust charge fluctuation is found to be insensitive with the form of distribution function for DKAW. The possible applications to dusty space plasmas are pointed out.
Kinetic Description of Vacuum Creation of Massive Vector Bosons
Blaschke, D.B. [Fachbereich Physik, Universitaet Rostock (Germany); Fakultaet fuer Physik, Universitaet Bielefeld (Germany); Joint Institute for Nuclear Research, Dubna (Russian Federation); Prozorkevich, A.V.; Smolyansky, S.A. [Saratov State University, Saratov (Russian Federation); Reichel, A.V. [Fachbereich Physik, Universitaet Rostock (Germany)
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.
A description of chemical and diffusion control in isothermal kinetics of cure kinetics
J. E. K. Schawe
2002-01-01
During isothermal polymerization reaction, a thermosetting resin vitrifies if the reaction temperature is lower than the maximum glass transition temperature of the fully reacted material. Due to the vitrification process, the kinetics become diffusion-controlled. The kinetics of such reactions can be described using a diffusion control function. The actual reaction rate can be expressed as a product of the reaction
Chen, Qiang; Chen, Bin
2012-10-01
In this paper, a hybrid electrodynamics and kinetics numerical model based on the finite-difference time-domain method and lattice Boltzmann method is presented for electromagnetic wave propagation in weakly ionized hydrogen plasmas. In this framework, the multicomponent Bhatnagar-Gross-Krook collision model considering both elastic and Coulomb collisions and the multicomponent force model based on the Guo model are introduced, which supply a hyperfine description on the interaction between electromagnetic wave and weakly ionized plasma. Cubic spline interpolation and mean filtering technique are separately introduced to solve the multiscalar problem and enhance the physical quantities, which are polluted by numerical noise. Several simulations have been implemented to validate our model. The numerical results are consistent with a simplified analytical model, which demonstrates that this model can obtain satisfying numerical solutions successfully. PMID:23214707
NASA Astrophysics Data System (ADS)
Chen, Qiang; Chen, Bin
2012-10-01
In this paper, a hybrid electrodynamics and kinetics numerical model based on the finite-difference time-domain method and lattice Boltzmann method is presented for electromagnetic wave propagation in weakly ionized hydrogen plasmas. In this framework, the multicomponent Bhatnagar-Gross-Krook collision model considering both elastic and Coulomb collisions and the multicomponent force model based on the Guo model are introduced, which supply a hyperfine description on the interaction between electromagnetic wave and weakly ionized plasma. Cubic spline interpolation and mean filtering technique are separately introduced to solve the multiscalar problem and enhance the physical quantities, which are polluted by numerical noise. Several simulations have been implemented to validate our model. The numerical results are consistent with a simplified analytical model, which demonstrates that this model can obtain satisfying numerical solutions successfully.
R. B. Winkler; J. Wilhelm
1983-01-01
A kinetic description of the dc Hg-Ar mixture plasma of fluorescent lamp discharges is given on the basis of the main microphysical processes and corresponding atomic data. The investigation comprises particle balances for the excited Hg atoms of the triplet 63P0,1,2 and singulet 61P1 state, the balance of the discharge current and an adequate form of the electron Boltzmann equation
Effects of the g Factor in Semiclassical Kinetic Plasma Theory
Brodin, Gert; Marklund, Mattias; Zamanian, Jens; Ericsson, Aasa; Mana, Piero L. [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden)
2008-12-12
A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analyzing the linear properties, it is found that new types of wave-particle resonances are possible that depend directly on the anomalous magnetic moment of the electron. As a result, new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.
2005 Workshop on NCETIP 1 Kinetic of plasma particles and electron
Kaganovich, Igor
action on metals. · Ablative plasma accelerators · MHD power conversion. · Vacuum arc Cathode spot · Unipolar arcs in Tokamaks. KINETIC OF A CONDENSED MATERIAL VAPORIZATION INTO VACUUM · Langmuir approach · Plasma in vacuum arc cathode spot. Electron transport · Cathode evaporation DIFFERENT CATHODE MATERIALS
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.
Recent advances in H{sub 2}/D{sub 2} plasma kinetics
Gorse, C.; Capitelli, M.; Celiberto, R.; Iasillo, D.; Longo, S. [Department of Chemistry-University of Bari, Centro di Studio per la Chimica dei Plasmi del CNR, 70126 Bari (Italy)
1996-07-01
H{sub 2}/D{sub 2} plasma kinetics is illustrated for different plasma conditions including multicusp magnetic plasmas, RF discharges and divertor plasmas. Particular emphasis is given to the role of Rydberg states in the production of negative ions D{sup {minus}}. {copyright} {ital 1996 American Institute of Physics.}
Kinetic description of electron beams in the solar chromosphere
NASA Technical Reports Server (NTRS)
Gomez, Daniel O.; Mauas, Pablo J.
1992-01-01
We formulate the relativistic Fokker-Plank equation for a beam of accelerated electrons interacting with a partially ionized plasma. In our derivation we conserved those terms contributing to velocity diffusion and found that this effect cannot be neglected a priori. We compute the terms accounting for elastic and inelastic collisions with neutral hydrogen and helium. Collisions with neutral hydrogen are found to be dominant throughout the chromosphere, except at the uppermost layers close to the transition region. As an application, we compute the loss of energy and momentum for a power-law beam impinging on the solar chromosphere, for a particular case in which the Fokker-Planck equation can be integrated analytically. We find that most of the beam energy is deposited in a relatively thin region of the chromosphere, a result which is largely insensitive to the theoretical method employed to compute the energy deposition rate.
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.
Chemical kinetics study of a nanosecond pulsed He-O2 plasma Jet
NASA Astrophysics Data System (ADS)
Xia, Shengguo; Jiang, Chunqi
2011-10-01
Atmospheric-pressure, nanosecond pulsed plasma jets have shown promising applications in biomedical and dental fields. In order to better understand the mechanisms associated to the plasma processes, a zero-dimensional plasma chemistry model was used to study the chemical kinetics of an atmospheric-pressure, nanosecond pulsed He-O2 plasma jet. Density kinetics of the charged and neutral species in the plasma jet as a function of the input parameters including the oxygen concentration and the electric field are calculated. The roles played by different reactions in the kinetics schemes are assessed. In addition, both of He-O2 and He-O2-N2 plasma chemical kinetics reaction schemes are discussed to examine the effects of air entrainment on the characteristics of the plasma jet.
NASA Astrophysics Data System (ADS)
Grubert, G. K.; Becker, M. M.; Loffhagen, D.
2009-09-01
The local-mean-energy approximation (LMEA) and the local-field approximation (LFA) are commonly applied to include the electron properties like transport and rate coefficients into a hydrodynamic description of gas discharge plasmas. Both the approaches base on the solution of the stationary spatially homogeneous Boltzmann equation for the electron component, but the consequences of these approaches differ drastically. These consequences of using both the approaches are studied and discussed on a kinetic level and by comparison of results of hydrodynamic investigations of low-pressure glow discharge plasmas. It is found that the LMEA is to be strongly recommended for the application to a hydrodynamic description of dc as well as rf discharge plasmas, while the LFA is conditionally suitable to describe dc glow discharges with rough reaction kinetics only and its application to rf discharge plasmas is inappropriate.
Kinetic studies of microinstabilities in toroidal plasmas: Simulation and theory
Lee, W.W.; Haham, T.S.; Parker, S.E.; Perkins, F.W.; Rath, S.; Rewoldt, G.; Reynders, J.V.W.; Santoro, R.A.; Tang, W.M.
1992-12-01
A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progress in achieving a physics-based understanding of anomalous transport in toroidal systems which has been based on the proposition that these drift-type electrostatic modes dependent on ion temperature gradient (ITG) and trapped particle effects are dominant in the bulk (``confinement``) region. Although their presence is consistent with a number of significant confinement trends, results from high temperature tokamaks such as TFTR have highlighted the need for better insight into the nonlinear properties of such instabilities in long-mean-free-path plasmas. In addressing this general issue, we report important new results including (i) the first fully toroidal 3D gyrokinetic simulation of ITG modes and (ii) realistic toroidal eigenmode calculations demonstrating the unique capability to deal with large scale kinetic behavior extending over many rational surfaces. The effects of ITG modes (iii) on the inward pinch of impurities in 3D slab geometry and (iv) on the existence of microtearing modes in 2D slab are also discussed. Finally, (v) sheared toroidal flow effects on trapped-particle modes are presented.
Kinetic studies of microinstabilities in toroidal plasmas: Simulation and theory
Lee, W.W.; Haham, T.S.; Parker, S.E.; Perkins, F.W.; Rath, S.; Rewoldt, G.; Reynders, J.V.W.; Santoro, R.A.; Tang, W.M.
1992-12-01
A comprehensive program for the development and use of particle simulation techniques for solving the gyrokinetic Vlasov-Maxwell equations on massively parallel computers has been carried out at Princeton Plasma Physics Laboratory. This is a key element of our ongoing theoretical efforts to systematically investigate physics issues vital to understanding tokamak plasmas. In this paper, our focus is on spatial-gradient-driven microinstabilities. Their importance is supported by the recent progress in achieving a physics-based understanding of anomalous transport in toroidal systems which has been based on the proposition that these drift-type electrostatic modes dependent on ion temperature gradient (ITG) and trapped particle effects are dominant in the bulk ( confinement'') region. Although their presence is consistent with a number of significant confinement trends, results from high temperature tokamaks such as TFTR have highlighted the need for better insight into the nonlinear properties of such instabilities in long-mean-free-path plasmas. In addressing this general issue, we report important new results including (i) the first fully toroidal 3D gyrokinetic simulation of ITG modes and (ii) realistic toroidal eigenmode calculations demonstrating the unique capability to deal with large scale kinetic behavior extending over many rational surfaces. The effects of ITG modes (iii) on the inward pinch of impurities in 3D slab geometry and (iv) on the existence of microtearing modes in 2D slab are also discussed. Finally, (v) sheared toroidal flow effects on trapped-particle modes are presented.
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
Cremaschini, Claudio, E-mail: claudiocremaschini@gmail.com; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Tessarotto, Massimo [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic) [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic); Department of Mathematics and Geosciences, University of Trieste, Via Valerio 12, 34127 Trieste (Italy)
2014-05-15
Astrophysical plasmas in the surrounding of compact objects and subject to intense gravitational and electromagnetic fields are believed to give rise to relativistic regimes. Theoretical and observational evidences suggest that magnetized plasmas of this type are collisionless and can persist for long times (e.g., with respect to a distant observer, coordinate, time), while exhibiting geometrical structures characterized by the absence of well-defined spatial symmetries. In this paper, the problem is posed whether such configurations can correspond to some kind of kinetic equilibrium. The issue is addressed from a theoretical perspective in the framework of a covariant Vlasov statistical description, which relies on the method of invariants. For this purpose, a systematic covariant variational formulation of gyrokinetic theory is developed, which holds without requiring any symmetry condition on the background fields. As a result, an asymptotic representation of the relativistic particle magnetic moment is obtained from its formal exact solution, in terms of a suitably defined invariant series expansion parameter (perturbative representation). On such a basis, it is shown that spatially non-symmetric kinetic equilibria can actually be determined, an example being provided by Gaussian-like distributions. As an application, the physical mechanisms related to the occurrence of a non-vanishing equilibrium fluid 4-flow are investigated.
D-Dimensional Radiative Plasma: A Kinetic Approach
A. Maia Jr.; J. A. S. Lima
1996-10-31
The covariant kinetic approach for the radiative plasma, a mixture of a relativistic moving gas plus radiation quanta (photons, neutrinos, or gravitons) is generalized to D spatial dimensions. The operational and physical meaning of Eckart's temperature is reexamined and the D-dimensional expressions for the transport coefficients (heat conduction, bulk and shear viscosity) are explicitly evaluated to first order in the mean free time of the radiation quanta. Weinberg's conclusion that the mixture behaves like a relativistic imperfect simple fluid (in Eckart's formulation) depends neither on the number of spatial dimensions nor on the details of the collisional term. The case of Thomson scaterring is studied in detail, and some consequences for higher dimensional cosmologies are also discussed.
Advances in petascale kinetic plasma simulation with VPIC and Roadrunner
Bowers, Kevin J [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim [Los Alamos National Laboratory; Kwan, Thomas J T [Los Alamos National Laboratory
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.
NASA Astrophysics Data System (ADS)
Astapenko, Valerie; Bagatur'yants, Alexander; Chernishova, Irina; Deminsky, Maxim; Eletskii, Alexander; Kirillov, Igor; Knizhnik, Andrei; Potapkin, Boris; Rykova, Elena; Umanskii, Stanislaw; Zaitsevskii, Andrei; Strelkova, Marina; Sukhanov, Leonid; Safonov, Andrei; Cotzas, George M.; Dean, Anthony; Michael, J. Darryl; Midha, Vikas; Smith, David J.; Sommerer, Timothy J.; Varatharajan, Bala; Tentner, Adrian
2007-04-01
Recent progress in several related research areas such as first-principles electronic-structure calculations of atoms and diatomic molecules, theory of elementary processes, kinetics, and numerical engineering, and also continued exponential growth in computational resources enhanced by recent advances in massively parallel computing have opened the possibility of directly designing kinetics mechanisms to describe chemical processes and light emission in such complex media as nonequilibrium plasmas and reacting gases. It is important that plasma and combustion kinetics can be described in the framework of this direct approach to a sufficiently high accuracy, which makes it an independent predictive research tool complementary to experimental techniques. This paper demonstrates the capabilities of the first-principles based approach to develop kinetic mechanisms. Two examples are discussed in detail: (1) the mechanism of hydrocarbon fuel combustion at high temperatures and (2) light emission in non-thermal glow discharge plasma of metal halides; special attention is paid to a comparison of the results obtained at every level of system description with the appropriate experimental data. In house software tools that can be used in such multilevel theoretical works are discussed as well.
Astapenko, Valerie; Bagatur'yants, Alexander; Chernishova, Irina; Deminsky, Maxim; Eletskii, Alexander; Knizhnik, Andrei; Potapkin, Boris; Rykova, Elena; Umanskii, Stanislaw; Zaitsevskii, Andrei; Safonov, Andrei [Kinetics Technologies, Moscow (Russian Federation); Kirillov, Igor; Strelkova, Marina; Sukhanov, Leonid [RRC Kurchatov Institute, Moscow (Russian Federation); Cotzas, George M.; Dean, Anthony; Michael, J. Darryl; Midha, Vikas; Smith, David J.; Sommerer, Timothy J. [GE Global Research, Niskayuna, New York (United States)] (and others)
2007-04-06
Recent progress in several related research areas such as first-principles electronic-structure calculations of atoms and diatomic molecules, theory of elementary processes, kinetics, and numerical engineering, and also continued exponential growth in computational resources enhanced by recent advances in massively parallel computing have opened the possibility of directly designing kinetics mechanisms to describe chemical processes and light emission in such complex media as nonequilibrium plasmas and reacting gases. It is important that plasma and combustion kinetics can be described in the framework of this direct approach to a sufficiently high accuracy, which makes it an independent predictive research tool complementary to experimental techniques. This paper demonstrates the capabilities of the first-principles based approach to develop kinetic mechanisms. Two examples are discussed in detail: (1) the mechanism of hydrocarbon fuel combustion at high temperatures and (2) light emission in non-thermal glow discharge plasma of metal halides; special attention is paid to a comparison of the results obtained at every level of system description with the appropriate experimental data. In house software tools that can be used in such multilevel theoretical works are discussed as well.
Electrical and kinetic model of an atmospheric rf device for plasma aerodynamics applications
Pinheiro, Mario J. [Department of Physics, Institute for Plasma and Nuclear Fusion, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Martins, Alexandre A. [Institute for Plasma and Nuclear Fusion, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)
2010-08-15
The asymmetrically mounted flat plasma actuator is investigated using a self-consistent two-dimensional fluid model at atmospheric pressure. The computational model assumes the drift-diffusion approximation and uses a simple plasma kinetic model. It investigated the electrical and kinetic properties of the plasma, calculated the charged species concentrations, surface charge density, electrohydrodynamic forces, and gas speed. The present computational model contributes to understand the main physical mechanisms, and suggests ways to improve its performance.
NASA Astrophysics Data System (ADS)
Kuznetsova, M. M.; Hesse, M.; Aunai, N.; Wendel, D. E.; Rastaetter, L.; Glocer, A.; Toth, G.
2014-12-01
One of the major conclusions of the GEM Reconnection Challenge at the dawn of the millennium was that reconnection rate is independent of the electron mass. This finding allowed to reduce the problem to hall-less pair plasma fluid description and reproduce kinetic reconnection rates in large-scale single-fluid simulations by incorporating kinetic non-gyrotropic corrections to the induction equation. It was demonstrated that nongyrotropic effects incorporated into symmetric magnetotail reconnection could significantly alter the global magnetosphere evolution. In this paper we will extend the approach to non-symmetric configurations relevant to planetary magnetospheres and solar corona. We will examine the applicability of the non-gyrotropic fluid approach to nonsymmetric magnetic reconnection and demonstrate consequences of local kinetic effects on global evolution.
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.
Kinetics of Plasma Epstein-Barr Virus DNA during Radiation Therapy for Nasopharyngeal Carcinoma1
Y. M. Dennis Lo; Sing-Fai Leung; Lisa Y. S. Chan; Anthony T. C. Chan; Kwok-Wai Lo; Philip J. Johnson; Dolly P. Huang
We studied the kinetics of circulating EBV DNA in the plasma of nasopharyngeal carcinoma (NPC) patients. Serial weekly sampling of 10 NPC patients revealed a rapid decline in plasma EBV DNA concentration after treatment. In two subjects, an initial rise in the circulating EBV DNA level was observed immediately after treatment initiation. Plasma EBV DNA levels were monitored daily during
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.
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.
Variational formulation of particle algorithms for kinetic plasma simulations
NASA Astrophysics Data System (ADS)
Evstatiev, E. G.; Shadwick, B. A.
2013-07-01
Common time-explicit numerical methods for kinetic simulations of plasmas in the low-collisions limit fall into two classes of algorithms: momentum conserving (also known as particle-in-cell (PIC)) and energy conserving. Each has certain drawbacks. The PIC algorithm does not conserve total energy, which may lead to spurious numerical heating (grid heating). Its overall accuracy is at most second due to the nature of the force interpolation between grid and particle position. Energy-conserving algorithms do not exhibit grid heating, but because their formulation uses potentials, computationally undesirable matrix inversions may be necessary. In addition, compared to PIC algorithms for the same accuracy, these algorithms have higher numerical noise due to the restricted choice of particle shapes. Here we formulate time-explicit, finite-size particle algorithms using particular reductions of the particle distribution function. These reductions are used in two variational principles, a Lagrangian-based and a Hamiltonian-based in conjunction with a non-canonical Poisson bracket. The Lagrangian formulations here generalize previous such formulations. The Hamiltonian formulation is presented here for the first time. Many drawbacks of the two classes of particle methods are mitigated. For example, restrictions on particle shapes are relaxed in energy conserving algorithms, which can decrease the numerical noise in these methods. The Hamiltonian formulation of particle algorithms is done in terms of fields instead of potentials, thus avoiding solving Poisson's equation. An algorithm that conserves both energy and momentum is presented. Other features of the algorithms include a natural way to perform coordinate transformations, the use of various time integrating methods, and the ability to increase the overall accuracy beyond second order, including all generalizations. For clarity of presentation, we restrict our discussion to one-dimensional, non-relativistic, unmagnetized, electrostatic plasmas.
NASA Astrophysics Data System (ADS)
Fedele, Renato; Mannan, Abdul; De Nicola, Sergio; Jovanovi?, Dusan; Akhter, Tahmina
2014-09-01
Within the Vlasov's kinetic theory, describing the plasma wake field interaction, the collective transport of a warm nonlaminar relativistic charged particle beam is analyzed in the strongly nonlocal regime, where the beam spot-size is much less than the plasma wavelength. This is done in the overdense regime, i.e., the beam density is much less than the plasma density. The beam is supposed to be sufficiently long to experience the adiabatic shielding by the plasma. In these conditions, we neglect the longitudinal beam dynamics and focus on the transverse one only. We derive the virial description (envelope description) from the 2D Vlasov-Poisson-type system of equations that governs the transverse self-consistent plasma wake field excitation. The resulting envelope equation is then reduced, in the aberration-less approximation, to a differential equation for the beam spot size, where the role of the ambient magnetic field is evaluated in both laboratory and astrophysical environments. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are found. Contribution to the Topical Issue "Theory and Applications of the Vlasov Equation", edited by Francesco Pegoraro, Francesco Califano, Giovanni Manfredi and Philip J. Morrison.
Kinetic approach to microscopic-macroscopic coupling in space and laboratory plasmas
Lapenta, Giovanni; Brackbill, J.U.; Ricci, Paolo [Plasma Theory Group, Theoretical Division, Los Alamos National Laboratory, Mail Stop: K717, Los Alamos, New Mexico 87545 (United States); Particle Solutions, Portland, Oregon 97214 (United States); Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)
2006-05-15
Kinetic plasma simulation typically requires to handle a multiplicity of space and time scales. The implicit moment particle in cell (PIC) method provides a possible route to address the presence of multiple scales effectively. Here, a new implementation of the implicit moment method is described. The present paper has two goals. First, the most modern implementation of the implicit moment method is described. While many of the algorithms involved have been developed in the past, the present paper reports for the first time how the implicit moment method is currently implemented and what specific algorithms have been found to work best. Second, we present the CELESTE3D code, a fully electromagnetic and fully kinetic PIC code, based on the implicit moment method. The code has been in use for a number of years but no previous complete description of its implementation has been provided. The present work fills this gap and introduces a number of new methods not previously presented: a new implementation of the Maxwell solver and a new particle mover based on a Newton-Krylov nonlinear solver for the discretized Newton's equations. A number of benchmarks of CELESTE3D are presented to shown the typical application and to investigate the improvements introduced by the new solver and the new mover.
Numerical modeling of radiation physics in kinetic plasmas [II
NASA Astrophysics Data System (ADS)
Paraschiv, Ioana; Sentoku, Yasuhiko; Mancini, Roberto
2014-10-01
X-ray radiation is an important feature of ultra-intense laser interactions with high Z materials. In order to take into account the radiation effects in the high energy density plasmas created by such interactions, we have modified the collisional particle-in-cell code PICLS to self-consistently model the x-ray radiation transport (RT). Solving the equation of radiation transport requires the creation of a non-LTE database of emissivities and opacities as functions of photon frequency for given densities, bulk electron temperatures, hot electron temperatures, and hot electron fractions. The database was generated using results computed by a non-equilibrium, collisional-radiative atomic kinetics code. Using the two-dimensional RT-PICLS code we have studied the X-ray transport in an ultrafast heated target and the dependence of the emitted K- ? radiation on the fast electron dynamics in the solid target. The details of these results obtained from the implementation of the radiation transport model into the PICLS calculations will be reported in this presentation. Work supported by the DOE Office of Science Grant No. DE-SC0008827 and by the NNSA/DOE Grants No. DE-FC52-06NA27616 and DE-NA0002075.
Measurement of the Kinetic Dust Temperature of a Weakly Coupled Dusty Plasma
Jeremiah D. Williams; E. Thomas
2007-01-01
Measurements of the velocity space distribution function of 1.2-mum-diameter alumina particles in an argon direct-current glow discharge dusty plasma are made using 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,
NASA Astrophysics Data System (ADS)
Vu, H. X.; Bezzerides, B.; DuBois, D. F.
1999-11-01
A fully kinetic, reduced-description particle-in-cell (RPIC) model is presented in which deviations from quasineutrality, electron and ion kinetic effects, and nonlinear interactions between low-frequency and high-frequency parametric instabilities are modeled correctly. The model is based on a reduced description where the electromagnetic field is represented by three separate temporal envelopes in order to model parametric instabilities with low-frequency and high-frequency daughter waves. Because temporal envelope approximations are invoked, the simulation can be performed on the electron time scale instead of the time scale of the light waves. The electrons and ions are represented by discrete finite-size particles, permitting electron and ion kinetic effects to be modeled properly. The Poisson equation is utilized to ensure that space-charge effects are included. The RPIC model is fully three dimensional and has been implemented in two dimensions on the Accelerated Strategic Computing Initiative (ASCI) parallel computer at Los Alamos National Laboratory, and the resulting simulation code has been named ASPEN. We believe this code is the first particle-in-cell code capable of simulating the interaction between low-frequency and high-frequency parametric instabilites in multiple dimensions. Test simulations of stimulated Raman scattering, stimulated Brillouin scattering, and Langmuir decay instability are presented.
Generation of kinetic Alfven waves by beam-plasma interaction in non-uniform plasma
Hong, M. H. [Institute of Geology and Geophysics, CAS, Beijing 100029 (China); Lin, Y. [Physics Department, Auburn University, Auburn, Alabama 36849-5311 (United States); Department of Geophysics and Planetary Science, USTC, Hefei 230026 (China); Wang, X. Y. [Physics Department, Auburn University, Auburn, Alabama 36849-5311 (United States)
2012-07-15
This work reports a novel mechanism of the generation of kinetic Alfven waves (KAWs) using a two-dimensional hybrid simulation: the KAWs are generated by ion beam-plasma interaction in a non-uniform plasma boundary layer, in which the bulk velocity of the ion beam is assumed to be parallel to the ambient magnetic field. As a result of the beam-plasma interaction, strong shear Alfven waves as well as fast mode compressional waves are first generated on the side of the boundary layer with a high density and thus a low Alfven speed, propagating along the background magnetic field. Later, Alfven waves also form inside the boundary layer with a continuous spectrum. As the perpendicular wave number k{sub Up-Tack} of these unstably excited waves increases with time, large-amplitude, short wavelength KAWs with k{sub Up-Tack } Much-Greater-Than k{sub ||} clearly form in the boundary layer. The physics for the generation of KAWs is discussed.
Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas
Cheng, C.Z.
1989-04-01
A nonvariational kinetic-MHD stability code (NOVA-K) has been developed to integrate a set of non-Hermitian integro-differential eigenmode equations due to energetic particles for axisymmetric toroidal plasmas in a general flux coordinate system with an arbitrary Jacobian. The NOVA-K code employs the Galerkin method involving Fourier expansions in the generalized poloidal angle theta and generalized toroidal angle /zeta/ directions, and cubic-B spline finite elements in the radial /Psi/ direction. Extensive comparisons with the existing variational ideal MHD codes show that the ideal MHD version of the NOVA-K code converges faster and gives more accurate results. The NOVA-K code is employed to study the effects of energetic particles on MHD-type modes: the stabilization of ideal MHD internal kink modes and the excitation of ''fishbone'' internal kink modes; and the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are also presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n = 1 internal kink mode in the hot particle beta space exists even in the absence of the core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to have negligible effects on the stability of the n = 1 internal kink mode, but the circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 60 refs., 24 figs., 1 tab.
Derivation and Implementation of Hybrid Fluid/Kinetic Model for Fusion Plasmas
Held, E. D.
2005-08-15
This is a final report for Dr. Eric Held’s Junior Faculty in Plasmas Physics grant entitled, “Derivation and Implementation of Hybrid Fluid/Kinetic Model for Fusion Plasmas”. Progress over the three years and six months of this project included work on analytical and numerical fronts.
Conner, M W; Chaudhuri, I; Rogers, A E; Amdur, M O
1985-02-01
Horseradish peroxidase (HRP) absorption across the wall of the upper airway, monitored by the amount detected in the blood, is used to measure epithelial damage by toxins. Full details of kinetics of absorption and blood clearance have not been reported previously. We measured the kinetics under the experimental conditions used in testing toxins. HRP was administered to guinea pigs either by intraarterial injection of a 7.5 microgram bolus (plasma clearance) or by intratracheal instillation of 1 mg (respiratory tract absorption). Plasma concentrations were monitored for 60 min. Plasma concentrations of HRP rose linearly with time after intratracheal instillation, reaching 236 +/- 51 ng/ml (mean +/- SE) at 60 min after instillation. HRP was cleared from the plasma rapidly after bolus injection. The elimination coefficient, k2, determined from the biphasic log normal plot, was 0.322 min-1. These data were used to estimate the kinetics of absorption across the respiratory epithelium. A single 3-hr exposure to an atmosphere containing 2.5 mg/m3 of submicrometer zinc oxide particles increased plasma concentration of HRP after intratracheal deposition (407 +/- 63 ng/ml at 60 min) and had no effect on plasma clearance (k2 = 0.342 min-1). Therefore plasma concentrations of HRP measured after intratracheal deposition can be used as a sensitive indicator to evaluate the effects of inhalation of a test atmosphere on epithelial permeability, if plasma clearance kinetics are not altered by the exposure. PMID:3987996
Broddak, R.; Voloshchuk, A.M.; Gorlov, V.A.; Dubinin, M.M.; Kochirzhik, M.
1987-01-10
An analytical description has been given of the kinetic adsorption curves with account of the influence of the change in adsorbent temperature due to the evolution of heat and adsorption on the coefficient of intracrystalline diffusion of the adsorbate. The deviation of the experimental kinetic curves for the adsorption of trans-2-butene by finely crystalline NaA zeolite from those calculated from the equation of isothermal diffusion is due to the influence of temperature on the coefficient of intracrystalline diffusion.
Economou, Demetre J.
Electron kinetics and non-Joule heating in near-collisionless inductively coupled plasmas V. I of Houston, Houston, Texas 77204-4792 Received 1 July 1996 Electron kinetics in an inductively coupled plasma for the manufacturing of ultra-large- scale integrated circuits 1 . Inductively coupled plasma ICP sources
M. V. Tokarchuk; I. P. Omelyan; A. E. Kobryn
1999-03-04
A statistical approach to a self-consistent description of kinetic and hydrodynamic processes in systems of interacting particles is formulated on the basis of the nonequilibrium statistical operator method by D.N.Zubarev. It is shown how to obtain the kinetic equation of the revised Enskog theory for a hard sphere model, the kinetic equations for multistep potentials of interaction and the Enskog-Landau kinetic equation for a system of charged hard spheres. The BBGKY hierarchy is analyzed on the basis of modified group expansions. Generalized transport equations are obtained in view of a self-consistent description of kinetics and hydrodynamics. Time correlation functions, spectra of collective excitations and generalized transport coefficients are investigated in the case of weakly nonequilibrium systems of interacting particles.
Assessment of Plasma-Flow Effect on Langmuir Triple-Probe Operation via Kinetic Simulation
Christopher Deline; Éric Choiniere; Brian E. Gilchrist
2009-01-01
A self-consistent steady-state 2-D kinetic plasma solver has been applied to the problem of Langmuir triple-probe plasma diagnostic measurements in a flowing collisionless plasma. The triple-probe response is simulated for ion Mach numbers M = 0 - 5 and probe radii rp = 1 - 90 lambdaD (Debye length). Results indicate that a high probe radius and high ion Mach
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.
NASA Astrophysics Data System (ADS)
Vu, H. X.; Bezzerides, B.; Dubois, D. F.
1998-11-01
A fully kinetic, reduced-description particle-in-cell (RPIC) model is presented in which deviations from quasineutrality, electron and ion kinetic effects, and nonlinear interactions between low-frequency and high-frequency parametric instabilities are modeled correctly. The model is based on a reduced description where the electromagnetic field is represented by three separate temporal WKB envelopes in order to model low-frequency and high-frequency parametric instabilities. Because temporal WKB approximations are invoked, the simulation can be performed on the electron time scale instead of the time scale of the light waves. The electrons and ions are represented by discrete finite-size particles, permitting electron and ion kinetic effects to be modeled properly. The Poisson equation is utilized to ensure that space-charge effects are included. Although RPIC is fully three dimensional, it has been implemented in only two dimensions on a CRAY-T3D with 512 processors and on the Accelerated Strategic Computing Initiative (ASCI) parallel computer at Los Alamos National Laboratory, and the resulting simulation code has been named ASPEN. Given the current computers available to the authors, one and two dimensional simulations are feasible to, and have been, performed. Three dimensional simulations are much more expensive, and are not feasible at this time. However, with rapidly advancing computer technologies, three dimensional simulations may be feasible in the near future. We believe this code is the first PIC code capable of simulating the interaction between low-frequency and high-frequency parametric instabilites in multiple dimensions. Test simulations of stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), and Langmuir decay instability (LDI), are presented.
Fully kinetic simulations of dense plasma focus Z-pinch devices.
Schmidt, A; Tang, V; Welch, D
2012-11-16
Dense plasma focus Z-pinch devices are sources of copious high energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood. We now have, for the first time, demonstrated a capability to model these plasmas fully kinetically, allowing us to simulate the pinch process at the particle scale. We present here the results of the initial kinetic simulations, which reproduce experimental neutron yields (~10(7)) and high-energy (MeV) beams for the first time. We compare our fluid, hybrid (kinetic ions and fluid electrons), and fully kinetic simulations. Fluid simulations predict no neutrons and do not allow for nonthermal ions, while hybrid simulations underpredict neutron yield by ~100x and exhibit an ion tail that does not exceed 200 keV. Only fully kinetic simulations predict MeV-energy ions and experimental neutron yields. A frequency analysis in a fully kinetic simulation shows plasma fluctuations near the lower hybrid frequency, possibly implicating lower hybrid drift instability as a contributor to anomalous resistivity in the plasma. PMID:23215497
Bonitz, Michael
2005-01-01
.1088/1742-6596/11/1/E01 Kinetic Theory of Nonideal Plasmas Preface The International Workshop `Kinetic Theory special attention was devoted to kinetic theory methods. Among the topics presented in this volume, there are plasma kinetic equations, theory of fluctuations, interaction of plasmas with electromagnetic fields
Field Theoretic Description of Ultrarelativistic Electron-Positron Plasmas
Markus H. Thoma
2009-07-06
Ultrarelativistic electron-positron plasmas can be produced in high-intensity laser fields and play a role in various astrophysical situations. Their properties can be calculated using QED at finite temperature. Here we will use perturbative QED at finite temperature for calculating various important properties, such as the equation of state, dispersion relations of collective plasma modes of photons and electrons, Debye screening, damping rates, mean free paths, collision times, transport coefficients, and particle production rates, of ultrarelativistic electron-positron plasmas. In particular, we will focus on electron-positron plasmas produced with ultra-strong lasers.
Fundamental statistical descriptions of plasma turbulence in magnetic fields
John A. Krommes
2002-01-01
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
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.
Ion-kinetic-energy measurements and energy balance in a Z-pinch plasma at stagnation.
Kroupp, E; Osin, D; Starobinets, A; Fisher, V; Bernshtam, V; Maron, Y; Uschmann, I; Förster, E; Fisher, A; Deeney, C
2007-03-16
The ion-kinetic energy throughout K emission in a stagnating plasma was determined from the Doppler contribution to the shapes of optically thin lines. X-ray spectroscopy with a remarkably high spectral resolution, together with simultaneous imaging along the pinch, was employed. Over the emission period, a drop of the ion-kinetic energy down to the electron thermal energy was seen. Axially resolved time-dependent electron-density measurements and absolute intensities of line and continuum allowed for investigating, for the first time, each segment of the pinch, the balance between the ion-kinetic energy at the stagnating plasma, and the total radiation emitted. Within the experimental uncertainties, the ion-kinetic energy is shown to account for the total radiation. PMID:17501061
Plasma-assisted ignition and combustion: nanosecond discharges and development of kinetic mechanisms
NASA Astrophysics Data System (ADS)
Starikovskaia, S. M.
2014-09-01
This review covers the results obtained in the period 2006-2014 in the field of plasma-assisted combustion, and in particular the results on ignition and combustion triggered or sustained by pulsed nanosecond discharges in different geometries. Some benefits of pulsed high voltage discharges for kinetic study and for applications are demonstrated. The necessity of and the possibility of building a particular kinetic mechanism of plasma-assisted ignition and combustion are discussed. The most sensitive regions of parameters for plasma-combustion kinetic mechanisms are selected. A map of the pressure and temperature parameters (P-T diagram) is suggested, to unify the available data on ignition delay times, ignition lengths and densities of intermediate species reported by different authors.
Vladimir Kolobov; Robert Arslanbekov
2003-01-01
A kinetic module has been developed in the commercial software package CFD-ACE+ and applied to simulations of plasma reactors for microelectronics applications. The kinetic module solves the Boltzmann transport equation (BTE) using two-term spherical harmonics expansion (SHE) of the probability distribution function (PDF). This method reduces the 6D BTE to a Fokker Planck equation in a four-dimensional space (three spatial
Shenggang Liu; Robert J. Barker; Yung Yan; Dajun Zhu
2000-01-01
For pt.I see ibid., vol.28, no.6, p.2135-51 (2000) Building upon the theoretical foundations presented in Part I of this paper, the kinetic theory of electron-beam-wave interactions in a magnetized plasma-filled waveguide (MPW) is presented in this second part. This kinetic theory treatment is more generally applicable to cases of less-intense electron-beams (Montgomery and Tidman, 1964). The dispersion relations for longitudinal
Closure of a kinetic model of plasma in strong turbulence by relaxation
NASA Technical Reports Server (NTRS)
Tchen, C. M.
1978-01-01
A Fokker-Planck kinetic equation for a turbulent plasma is derived by a repeated cascade decomposition. Calculation of the propagator and the kinetic equation determine the transport coefficients (diffusivity and turbulent viscosity) by means of a closure based on a relaxation procedure governing the approach to equilibrium. The k to the minus third power spectral law is obtained, which governs the coupling between the velocity and the electrostatic field fluctuations.
Excitation of ion-acoustic perturbations by incoherent kinetic Alfven waves in plasmas
Mendonca, J. T.; Shukla, P. K. [CFP, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum, Germany and School of Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)
2007-12-15
The dispersion relation for ion-acoustic perturbations (IAPs) in the presence of incoherent kinetic Alfven waves (KAWs) in plasmas is derived. The wave-kinetic-approach is used to study the nonlinear interactions between an ensemble of random phase KAWs and IAPs. It is found that incoherent KAW spectrum is unstable against IAPs. The instability growth rates for particular cases are obtained. The present instability offers the possibility of heating ions in a turbulent magnetoplasma composed of incoherent KAWs.
Kinetic models for the VASIMR thruster helicon plasma source
Oleg Batishchev; Kim Molvig
2001-01-01
Helicon gas discharge [1] is widely used by industry because of its remarkable efficiency [2]. High energy and fuel efficiencies make it very attractive for space electrical propulsion applications. For example, helicon plasma source is used in the high specific impulse VASIMR [3] plasma thruster, including experimental prototypes VX-3 and upgraded VX-10 [4] configurations, which operate with hydrogen (deuterium) and
Kinetic approach to low-frequency waves in dusty self-gravitating plasmas.
Yaroshenko, V V; Jacobs, G; Verheest, F
2001-06-01
A kinetic model is derived for the propagation of low-frequency waves in a dusty plasma containing very heavy dust particles, when the self-gravitational interaction due to these grains is included in the analysis. Analytical expressions for the dispersion function are used to examine the instability and damping of the modes. The stability regions of low-frequency waves are compared in the kinetic and the analogous hydrodynamic models, showing that there are only slight differences. However, the kinetic analysis modifies the growth rates of the Jeans instability and can considerably alter the conditions for the propagation of stable dust modes. PMID:11415234
Tautz, R. C.; Schlickeiser, R.; Lerche, I. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum-und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Institut fuer Geowissenschaften, Naturwissenschaftliche Fakultaet III, Martin-Luther-Universitaet Halle, D-06099 Halle (Germany)
2007-01-15
The stability properties of relativistic plasmas embedded in a uniform magnetic field are investigated for longitudinal and transverse modes and with coupling effects between these modes. The direction of wave propagation in the plasma is not necessarily either parallel or transverse to the ambient magnetic field. The basic dispersion relation equations are given for arbitrary propagation directions. Detailed examination is focused on perpendicular wave propagation in this paper. The concept of neutral points in wave number space, introduced by Harris [Phys. Rev. Lett. 2, 34 (1959)], is generalized to allow for the inclusion of ion effects and the effects of fluctuating magnetic fields. Starting from the relativistic conductivity tensor, an expansion procedure for low wave frequencies is used to determine the stability properties in the neighborhood of neutral points and in the frequency regime below the ion cyclotron frequency. The bulk plasma properties determine stability or instability but the mode structure is derivable only from a particle kinetic picture, as with Weibel [Phys. Rev. Lett. 2, 83 (1959)] instabilities, and not from a magnetohydrodynamic description. For monoenergetic plasma distribution functions of electrons and ions, as well as for electrons and positrons, numerical examples are given to illustrate the neutral points and the unstable wave number regimes.
R. Winkler; J. Wilhelm
1983-01-01
In continuation of recent kinetic investigations of the main macroscopic quantities of the Ar-Hg plasma which include realistic electron kinetics at various Hg partial pressures, this paper deals with the study of the macroscopic plasma behaviour at varying discharge current and buffer gas pressure respectively in a wide range of practical interest. By simultaneously solving the particle balances for the
Kinetics of the appearance of cereal alkylresorcinols in pig plasma.
Linko, Anna-Maria; Ross, Alastair B; Kamal-Eldin, Afaf; Serena, Anja; Kjaer, Anna Kirstin Bjørnbak; Jørgensen, Henry; Peñalvo, José L; Adlercreutz, Herman; Aman, Per; Knudsen, Knud Erik Bach
2006-02-01
Alkylresorcinols (AR) are phenolic lipids found in high amounts in wholegrain wheat and rye. They may be important as bioactive components and/or biomarkers of wholegrain wheat and rye intake. AR absorption was studied with pigs during a habitual diet and after a single meal of AR-rich diet. In study 1, four pigs were fed wholegrain rye (RD) and white wheat bread (WD) for 1 week in a cross-over design. Arterial and venous AR concentrations were determined over 540 min after feeding on days 5 and 7. In study 2, four pigs were fed a synthetic, starch-based diet for 5 d, and arterial and venous AR concentrations were determined over 960 min after feeding a single meal of RD. In study 1, plasma AR concentrations after consuming RD peaked at 120 min, remained elevated between 120 and 420 min, and were re-elevated on refeeding at 480 min. In study 2, AR appeared in the plasma after 60 min, peaked at 180-240 min, and remained elevated after 960 min. The apparent elimination half-life was 3.93 h, and the maximum plasma concentration was 666 (sem 35) nmol/l. Arterial and venous plasma AR concentrations were similar, suggesting that AR are absorbed via the lymphatic system. AR concentrations in pig plasma increase rapidly after a meal containing AR, and persist in plasma for at least 5 d, indicating that AR may be a useful biomarker of wholegrain wheat and rye intake. PMID:16469143
Page 1 Topical Area: MFE Title: Burning Plasma Experimental Options______________________________ · Description The options for a Next Step Burning Plasma Experiment are defined by the overall strategic but have not garnered the required scientific and financial support to proceed with construction
E. A. Bogdanov; A. A. Kudryavtsev; L. D. Tsendin; R. R. Arslanbekov; V. I. Kolobov; V. V. Kudryavtsev
2003-01-01
Results from kinetic and fluid simulations of the positive column plasma of a dc oxygen discharge are compared using commercial\\u000a CFDRC software (http:\\/\\/www.cfdrc.com\\/?cfdplasma), which enables one to perform numerical simulations in an arbitrary 3D geometry with the use of both the fluid equations\\u000a for all the components (fluid model) and the kinetic equation for the electron energy distribution function (kinetic
Simulation of Low Pressure Plasma Processing Reactors: Kinetics of Electrons and Neutrals
R. R. Arslanbekov; V. I. Kolobov
In this paper, we illustrate different aspects of electron kinetics and rarefied gas effects in low pressure inductively coupled plasmas (ICPs). We focus on deterministic methods of solving the Boltzmann equation and its derivatives. Due to small electron mass, the Boltzmann equation for electrons can be reduced to a Fokker-Planck equation of lower dimensionality and solved together with electromagnetic and
Comparisons of dense-plasma-focus kinetic simulations with experimental measurements.
Schmidt, A; Link, A; Welch, D; Ellsworth, J; Falabella, S; Tang, V
2014-06-01
Dense-plasma-focus (DPF) Z-pinch devices are sources of copious high-energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency. PMID:25019717
Comparisons of dense-plasma-focus kinetic simulations with experimental measurements
Schmidt, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Link, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Welch, D. [Voss Scientific, Inc., Albuquerque, NM (United States); Ellsworth, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Falabella, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tang, V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2014-06-01
Dense-plasma-focus (DPF) Z-pinch devices are sources of copious high-energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency.
Ju, Yiguang
American Institute of Aeronautics and Astronautics 1 Kinetic Effects of Non-Equilibrium Plasma 2011, Orlando, Florida AIAA 2011-971 Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. #12;American Institute of Aeronautics and Astronautics 2 Xf = fuel mole
Symmetry Extensions and Their Physical Reasons in the Kinetic and Hydrodynamic Plasma Models
Volodymyr B. Taranov
2008-01-17
Characteristic examples of continuous symmetries in hydrodynamic plasma theory (partial differential equations) and in kinetic Vlasov-Maxwell models (integro-differential equations) are considered. Possible symmetry extensions conditional and extended symmetries are discussed. Physical reasons for these symmetry extensions are clarified.
Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling
NASA Astrophysics Data System (ADS)
DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.
2008-02-01
Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.
Localization of linear kinetic Alfvén wave in an inhomogeneous plasma and generation of turbulence
Sharma, R. P.; Goyal, R., E-mail: ravig.iitd@gmail.com [Centre for Energy Studies, Indian Institute of Technology, Delhi-110016 (India); Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)] [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Dwivedi, N. K. [Austrian Academy of Sciences, Space Research Institute, Schmiedlstrasse 6, 8042 Graz (Austria)] [Austrian Academy of Sciences, Space Research Institute, Schmiedlstrasse 6, 8042 Graz (Austria)
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.
Solar wind kinetic instabilities at small plasma betas
Ibscher, D., E-mail: ibscher@tp4.rub.de; Schlickeiser, R. [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)] [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)
2014-02-15
The ordinary perpendicular mode of drifting bi-Maxwellian plasma particle distributions with and without temperature anisotropy can provide aperiodic instabilities. These instabilities occur if the perpendicular thermal energy is much smaller than the streaming energy. This provides instabilities at small parallel plasma betas ?{sub ?}<1 and temperature anisotropies A?
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.
Electron kinetics of weakly ionized collision-dominated rf plasmas in CO
Winkler, R.; Capitelli, M.; Dilonardo, M.; Gorse, C.; Wilhelm, J.
1986-12-01
Based on the nonstationary electron Boltzmann equation this paper deals with the time-resolved electron kinetics in the rf plasma in CO, i.e., with the calculation of the temporal evolution of the energy distribution and of the resultant macroscopic quantities for the established steady state. A particular aspect of this plasma is the distinctly resonance-like behavior of the vibrational excitation of the CO molecules by electron collisions. This causes the lumped frequencies for energy and impulse dissipation in collisions, recently introduced in the study of the rf kinetics in Ne and H/sub 2/, to become extremely dependent on the electron energy. Despite this fact, it could be verified that the field frequency dependence of the temporal evolution of the electron kinetics can be interpreted by means of these two dissipation frequencies even under such complicated conditions as given by the atomic data in CO.
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...
On the magnetohydrodynamic description of a two-component plasma in the Kerr metric
Ramon Khanna
1998-03-09
The magnetohydrodynamic equations describing an inviscid, fully ionized plasma in the vicinity of a rotating black hole are derived from a two-component plasma theory within the framework of the 3+1 split of the Kerr metric. Of central interest is the generalized Ohm's law. In the limit of quasi-neutral plasma it contains no new terms as compared with special relativity. Gravitomagnetic terms appear in Ohm's law only if the plasma is charged in its rest frame or the magnetohydrodynamic approximation is not applied. It is argued that a relativistic single-fluid description of a multiple-component plasma is possible only for cold (i.e. intrinsically non-relativistic) components. As seen by local stationary observers, close to the horizon the electron collision time becomes longer than dynamical timescales, i.e. the plasma appears to behave as particles.
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.
Generic modeling of surface reaction kinetics in plasma etching systems
NASA Astrophysics Data System (ADS)
Bray, Raymond Paul
The complexity of both the bulk plasma phase physics and the substrate surface reaction chemistry indicate the need for simplified phenomenological modeling of etching systems. Simplified models are useful for design, analysis and control, within a reasonable time after data collection, and at modest cost. A current typical method in industry is a response surface model (an empirical polynomial), which has no predictive properties outside the range of fitted data, is completely arbitrary, and offers little physical understanding of the system. A set of generic etch rate expressions based on simplified representations of physical phenomena are presented in this dissertation. The model parameter values are regressed from data with a constrained, nonlinear optimization routine. Also presented are a statistical method for discriminating which model best represents the phenomenon of a particular etching system and a statistical model validation procedure. The benefits of this approach are a predictive, statistically validated model; the small number of model parameters may reduce the number of data points required for regression; and there is no need to re-derive a polynomial fit for each new data set. The method will be demonstrated on experimental data for chlorine plasma etching of polysilicon; tetrafluoromethane/oxygen plasma etching of polysilicon and silicon dioxide; and oxygen plasma ashing of photoresist.
Kinetics of Dusty (Complex) Plasmas: Role of Variable Charges
A. V. Ivlev; S. K. Zhdanov; B. A. Klumov; G. E. Morfill
2005-01-01
Summary form only given. Charges of microparticles in complex (dusty) plasmas are not constant, but fluctuate in time around some equilibrium value which, in turn, is some function of spatial coordinates. Generally, ensembles of particles with variable charges are non-Hamiltonian systems where the mutual collisions do not conserve energy. An appropriate way to investigate evolution of such systems is to
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.
Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures
Cremaschini, Claudio; Stuchlík, Zden?k [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám.13, CZ-74601 Opava (Czech Republic)
2014-04-15
The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed.
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
Kinetic shear Alfvén instability in the presence of impurity ions in tokamak plasmas
NASA Astrophysics Data System (ADS)
Lu, Gaimin; Shen, Y.; Xie, T.; Qi, Longyu; He, Zhixiong; He, Hongda; Cui, Shaoyan
2013-10-01
The effects of impurity ions on the kinetic shear Alfvén (KSA) instability in tokamak plasmas are investigated by numerically solving the integral equations for the KSA eigenmode in the toroidal geometry. The kinetic effects of hydrogen and impurity ions, including transit motion, finite ion Larmor radius, and finite-orbit-width, are taken into account. Toroidicity induced linear mode coupling is included through the ballooning-mode representation. Here, the effects of carbon, oxygen, and tungsten ions on the KSA instability in toroidal plasmas are investigated. It is found that, depending on the concentration and density profile of the impurity ions, the latter can be either stabilizing or destabilizing for the KSA modes. The results here confirm the importance of impurity ions in tokamak experiments and should be useful for analyzing experimental data as well as for understanding anomalous transport and control of tokamak plasmas.
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}.
Kinetic theory of a two-dimensional magnetized plasma. II - Balescu-Lenard limit.
NASA Technical Reports Server (NTRS)
Vahala, G.
1972-01-01
The kinetic theory of a two-dimensional one-species plasma in a uniform dc magnetic field is investigated in the small plasma parameter limit. The plasma consists of charged rods interacting through the logarithmic Coulomb potential. Vahala and Montgomery earlier (1971) derived a Fokker-Planck equation for this system, but it contained a divergent integral, which had to be cut off on physical grounds. This cutoff is compared to the standard cutoff introduced in the two-dimensional unmagnetized Fokker-Planck equation. In the small plasma parameter limit, it is shown that the Balescu-Lenard collision term is zero in the long time average limit if only two-body interactions are considered. The energy transfer from a test particle to an equilibrium plasma is discussed and is also shown to be zero in the long time average limit. This supports the unexpected result of zero Balescu-Lenard collision term.
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.
Test-particle method in kinetic theory of a plasma.
NASA Technical Reports Server (NTRS)
Matsuda, K.
1971-01-01
The introduction of a test particle into a system is considered. The system may be described by the Born-Bogoliubov-Green-Kirkwood-Yvon hierarchy. The field particles form a cloud which surrounds the test particle. The cloud is described by a conditional probability function which satisfies a certain equation. A generalization of the superposition principle reported by Rostoker (1964) to higher order correlation functions is discussed. Kinetic equations with the generalized Lenard-Balescu term are obtained, taking into account also diffusion by waves. The characteristics regarding the absorption or emission of waves by particles can be calculated.
Kinetic simulations of argon dusty plasma afterglow including metastable atom kinetics
Alexandrov, A. L., E-mail: a_alex@itam.nsc.ru; Schweigert, I. V.; Ariskin, D. A. [Siberian Branch of the Russian Academy of Sciences, Institute of Theoretical and Applied Mechanics (Russian Federation)
2013-04-15
The afterglow of a dusty plasma of rf discharge in argon is simulated by the particle-in-cell-Monte Carlo collision (PIC-MCC) method. The experimental observation that heavy dust contamination of plasma leads to an anomalous increase in the electron density at the beginning of afterglow is explained by release of electrons from the dust surface. Under the assumption that the floating potential of particles is in equilibrium with plasma conditions, the fast cooling of electrons in afterglow plasma due to a rapid escape of hot electrons from the volume leads to a decrease in the magnitude of the floating potential and hence to a loss of charge by dust. The intensive desorption of electrons from nanoparticles is the origin of anomalous behavior of the electron density. At the next stage of afterglow, when the electrons become cool, the plasma decay is defined by ambipolar diffusion. The effect of metastable argon atoms is also considered. Additional ionization due to metastable atom collisions affects the electron temperature but does not change the behavior of the electron density qualitatively.
Kinetic dust acoustic mode in inhomogeneous partially magnetized plasma
NASA Astrophysics Data System (ADS)
Vranjes, J.; Poedts, S.
2014-05-01
The dust acoustic mode in inhomogeneous plasmas is discussed in the regime when the electrons and ions are magnetized while at the same time the dust grains remain un-magnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species. It is shown that this may be a powerful mechanism for the excitation of dust acoustic waves. The analysis presented in this work is also applicable to plasmas containing both positive and negative ions and electrons, provided that at least one of the two ion species is un-magnetized.
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
Lauber, Ph. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany)], E-mail: philipp.lauber@ipp.mpg.de; Guenter, S. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Koenies, A. [Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, EURATOM-Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Pinches, S.D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, Boltzmannstrasse 2, D-85748 Garching (Germany)
2007-09-10
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.
Quantification of transthyretin kinetic stability in human plasma using subunit exchange.
Rappley, Irit; Monteiro, Cecília; Novais, Marta; Baranczak, Aleksandra; Solis, Gregory; Wiseman, R Luke; Helmke, Stephen; Maurer, Mathew S; Coelho, Teresa; Powers, Evan T; Kelly, Jeffery W
2014-04-01
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
Orszag Tang vortex-Kinetic study of a turbulent plasma
NASA Astrophysics Data System (ADS)
Parashar, T. N.; Servidio, S.; Shay, M. A.; Matthaeus, W. H.; Cassak, P. A.
2010-03-01
Kinetic evolution of the Orszag-Tang vortex is studied using collisionless hybrid simulations based on particle in cell ions and fluid electrons. In magnetohydrodynamics (MHD) this configuration leads rapidly to broadband turbulence. An earlier study [1] estimated the dissipation in the system. A comparison of MHD & hybrid simulations showed similar behavior at large scales but substantial differences at small scales. The hybrid magnetic energy spectrum shows a break at the scale where Hall term in the Ohm's law becomes important. The protons heat perpendicularly and most of the energy is dissipated through magnetic interactions. Here, the space time structure of the system is studied using frequency-wavenumber (k-?) decomposition. No clear resonances appear, ruling out the cyclotron resonances as a likely candidate for the perpendicular heating. The only distinguishable wave modes present, which constitute a small percentage of total energy, are magnetosonic modes.
Capitelli, M. [Department of Chemistry, University of Bari, Bari (Italy); CSCP-IMIP (CNR), Sezione Terriroriale di Bari, Bari (Italy); De Pascale, O. [CSCP-IMIP(CNR), Sezione Terriroriale di Bari, Bari (Italy); Diomede, P.; Gorse, C.; Longo, S.; Pagano, D. [Department of Chemistry, University of Bari, Bari (Italy); Gicquel, A.; Hassouni, K. [LIMHP-CNRS, Univerite Paris Nord, Villetaneuse (France)
2005-04-06
Different approaches to study vibrational kinetics coupled to electron one for modeling different kinds of negative ion sources are presented. In particular two types of sources are investigated. The first one is a classical negative ion source in which the plasma is generated by thermoemitted electrons; in the second one, electrons already present in the mixture are accelerated by an RF field to sufficiently high energy to ionize the gas molecules. For the first kind of ion source a new computational scheme is presented to couple heavy particle and electron kinetics. Moreover models developed for an RF inductive discharge and for a parallel plate discharge are described.
Zaitsev, F.S. (Moscow State University, Moscow (Russian Federation)); O'Brien, M.R.; Cox, M. (UKAEA/EURATOM Fusion Association, Culham Laboratory, Abingdon (United Kingdom))
1993-02-01
The three-dimensional nonlinear kinetic equation for low collisionality tokamak plasmas with consistent consideration of neoclassical effects is obtained using an approach differing from the standard neoclassical theory technique. This allows treatment of large banana widths and large inverse aspect ratios. The equation is suitable for computer modeling of bootstrap currents and other phenomena arising from non-Maxwellian distributions. The formalism described in this paper, which is for noncanonical variables, might also be of use for the consistent derivation of three-dimensional kinetic equations that treat other effects, for example, additional heating.
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.
Peter J. Catto; Andrei N. Simakov
2003-01-01
Short mean free path descriptions of magnetized plasmas have existed for almost 50 years. The earliest work adopted an ordering in which the flow velocity was assumed to be comparable to the ion thermal speed. Later work extended the treatment to the normally more interesting limit in which the pressure times the mean flow velocity is comparable to the diamagnetic
Peter J. Catto; Andrei N. Simakov
2004-01-01
Short mean free path descriptions of magnetized plasmas have existed for almost 50 years so it is surprising to find that further modifications are necessary. The earliest work adopted an ordering in which the flow velocity is assumed to be comparable to the ion thermal speed. Later, less well-known studies extended the short mean free path treatment to the normally
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.
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).
Spectral evolution of two-dimensional kinetic plasma turbulence in the wavenumber-frequency domain
Comi?el, H. [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany) [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany); Institute for Space Sciences, Atomi?tilor 409, P.O. Box MG-23, Bucharest-M?gurele RO-077125 (Romania); Verscharen, D. [Space Science Center, University of New Hampshire, 8 College Rd., Durham, New Hampshire 03824 (United States)] [Space Science Center, University of New Hampshire, 8 College Rd., Durham, New Hampshire 03824 (United States); Narita, Y. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz (Austria)] [Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz (Austria); Motschmann, U. [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany) [Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, D-38016 Braunschweig (Germany); Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, Rutherfordstr. 2, D-12489 Berlin (Germany)
2013-09-15
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.
Various applications of atomic physics and kinetics codes to plasma modeling
NASA Astrophysics Data System (ADS)
Abdallah, J.; Clark, R. E. H.; Kilcrease, D. P.; Csanak, G.; Fontes, C. J.
1996-07-01
A collection of computer codes developed at Los Alamos have been applied to a variety of plasma modeling problems. The CATS, RATS, ACE, and GIPPER codes are used to calculate a consistent set of atomic physics data for a given problem. The calculated data include atomic energy levels, oscillator strengths, electron impact excitation and ionization cross sections, photoionization cross sections, and autoionization rates. The FINE and LINES codes access these data sets directly to perform plasma modeling calculations. Preliminary results of some of the current applications are presented, including, the calculation of holmium opacity, the modeling of plasma flat panel display devices, the analysis of some new results from the LANL TRIDENT laser and prediction of the radiative properties of the plasma wakefield light source for extreme ultraviolet lithography (EUVL). For the latter project, the simultaneous solution of atomic kinetics for the level populations and the Boltzmann equation for the electron energy distribution is currently being implemented.
Plasma surface functionalization and dyeing kinetics of Pan-Pmma copolymers
NASA Astrophysics Data System (ADS)
Labay, C.; Canal, C.; Rodríguez, C.; Caballero, G.; Canal, J. M.
2013-10-01
Fiber surface modification with air corona plasma has been studied through dyeing kinetics under isothermal conditions at 30 °C on an acrylic-fiber fabric with a cationic dye (CI Basic Blue 3) analyzing the absorption, desorption and fixing on the surface of molecules having defined cationic character. The initial dyeing rate in the first 60 s indicates an increase of 58.3% in the dyeing rate due to the effect of corona plasma on the acrylic fiber surface. At the end of the dyeing process, the plasma-treated fabrics absorb 24.7% more dye, and the K/S value of the acrylic fabric increases by 8.8%. With selected dyestuff molecules, new techniques can be designed to amplify the knowledge about plasma-treated surface modifications of macromolecules.
A Hybrid Fluid-Kinetic Theory for Plasma Physics
Tor Fla
2001-10-30
We parameterize the phase space density by time dependent diffeomorphic, Poisson preserving transformations on phase space acting on a reference density solution. We can look at these as transformations which fix time on the extended space of phase space and time. In this formulation the Vlasov equation is replaced by a constraint equation for the above maps. The new equations are formulated in terms of hamiltonian generators of one parameter families of diffeomorphic, Poisson preserving maps e.g. generators with respect to time or a perturbation parameter. We also show that it is possible to parameterize the space of solutions of the Vlasov equation by composition of maps subject to certain compatibility conditions on the generators. By using this composition principle we show how to formulate new equations for a hybrid fluid kinetic theory. This is done by observing that a certain subgroup of the group of phase space maps with generators which are linear in momentum correspond to the group of diffeomorphic maps parameterizing the continuity equation in fluid theory.
Akatsuka, Hiroshi [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.
Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas
Hussain, Azhar [Department of Physics, GC University Lahore, 54000 Lahore (Pakistan)] [Department of Physics, GC University Lahore, 54000 Lahore (Pakistan); Stefan, Martin; Brodin, Gert [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden)] [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden)
2014-03-15
We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.
Effect of driving frequency on excitation of turbulence in a kinetic plasma
Parashar, T. N.; Shay, M. A.; Matthaeus, W. H. [Department of Physics and Astronomy, 217 Sharp Laboratory, University of Delaware, Newark, Delaware 19716 (United States); Servidio, S. [Dipartimento di Fisica, Universita' della Calabria, I-87036 Cosenza (Italy); Breech, B. [Army Research Lab, Aberdeen, Maryland 21005 (United States)
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.
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.
Von Kármán energy decay and heating of protons and electrons in a kinetic turbulent plasma.
Wu, P; Wan, M; Matthaeus, W H; Shay, M A; Swisdak, M
2013-09-20
Decay in time of undriven weakly collisional kinetic plasma turbulence in systems large compared to the ion kinetic scales is investigated using fully electromagnetic particle-in-cell simulations initiated with transverse flow and magnetic disturbances, constant density, and a strong guide field. The observed energy decay is consistent with the von Kármán hypothesis of similarity decay, in a formulation adapted to magnetohydrodyamics. Kinetic dissipation occurs at small scales, but the overall rate is apparently controlled by large scale dynamics. At small turbulence amplitudes the electrons are preferentially heated. At larger amplitudes proton heating is the dominant effect. In the solar wind and corona the protons are typically hotter, suggesting that these natural systems are in the large amplitude turbulence regime. PMID:24093244
NASA Astrophysics Data System (ADS)
Winkler, R. B.; Wilhelm, J.; Winkler, R.
A kinetic description of the dc Hg-Ar mixture plasma of fluorescent lamp discharges is given on the basis of the main microphysical processes and corresponding atomic data. The investigation comprises particle balances for the excited Hg atoms of the triplet 63P0,1,2 and singulet 61P1 state, the balance of the discharge current and an adequate form of the electron Boltzmann equation for such a mixture plasma, the latter including also the various binary collision processes with excited Hg atoms and the Coulomb interaction between the electrons. By simultaneously solving the balances together with the kinetic equation the densities of electrons and excited Hg atoms, the electron energy distribution, the resulting mean energy, mobility and various energy transfer rates of the electrons and the ultraviolet radiation output were determined and in part compared with measured data from the literature. This paper presents and analyses the macroscopic plasma properties mentioned for a wide range of the wall temperature or the corresponding Hg partial pressure variation, where a good agreement of calculated results with experimental data is obtained. In a second paper the change of the macroscopic plasma behaviour due to variation of buffer gas pressure and discharge current will be dealt with.Translated AbstractKinetik des Ar-Hg-Plasmas von Leuchtstofflampenentladungen I. Modell - Grundgleichungen - Hg-PartialdruckvariationDie Arbeit befaßt sich auf der Grundlage der wesentlichen mikrophysikalischen Prozesse und der entsprechenden atomaren Daten mit der kinetischen Beschreibung des de Hg-Ar-Mischplasmas von Leuchtstofflampenentladungen. Die Untersuchung verwendet die Teilchenbilanzen für die angeregten Hg-Atome des Tripletts 63P0,1,2 und des Singuletts 61P1, die Bilanz für den Entladungsstrom und eine adäquate Form der Elektronen-Boltzmann-Gleichung für ein solches Mischplasma, wobei in letzterer auch die verschiedenen Zweierstoßprozesse mit angeregten Hg-Atomen und die Coulomb-Wechselwirkung zwischen den Elektronen berücksichtigt wird. Mittels simultaner Lösung der Bilanzgleichungen zusammen mit der kinetischen Gleichung wurden sowohl die Dichten der Elektronen und angeregten Hg-Atome, die Elektronenenergieverteilung, die sich ergebende mittlere Energie, Beweglichkeit und die verschiedenen Energieübertragungsraten der Elektronen als auch die Ausbeute an ultravioletter Strahlung bestimmt und teilweise mit in der Literatur verfügbaren Meßdaten verglichen. In dieser Arbeit werden die genannten makroskopischen Plasmaeigenschaften für einen weiten Variationsbereich der Wandtemperatur und damit des Hg-Partialdruckes dargestellt und analysiert, wobei gute Übereinstimmung von berechneten und experimentellen Ergebnissen erhalten wird. In einer weiteren Arbeit wird das makroskopische Plasmaverhalten bei Variation des Puffergasdruckes und des Entladungsstromes dargestellt und diskutiert.
Fokker–Planck modeling of electron kinetics in plasmas and semiconductors
Vladimir I. Kolobov
2003-01-01
The paper reviews physical principles and computational methods of solving the multi-dimensional Fokker–Planck equation (FPE) in application to electron kinetics in gas discharge plasmas and semiconductor devices. The four-dimensional (3 spatial coordinates+energy) FPE is obtained from the 6D Boltzmann transport equation (BTE) for the case when momentum relaxation occurs faster than energy relaxation. The FPE-based methods offer a very good
Moment expansion of the kinetic equation and its application to strongly coupled plasmas
K. I. Golden; G. Kalman
1982-01-01
Starting from linearized velocity moment expansions of the first Bogoliubov-Born-Green-Kirkwood-Yvon kinetic equation for one-component plasmas and using the non-linear fluctuation-dissipation theorem, the authors develop a systematic procedure for calculating the dynamical linear polarizability in terms of quadratic ones. This procedure provides insight into the long-wavelength structure of the velocity-average-approximation (VAA) hypothesis invoked by the authors in earlier calculations. At high
Kinetics and continuum emission of negative atomic ions in partially ionized plasmas
NASA Technical Reports Server (NTRS)
Soon, W. H.; Kunc, J. A.
1991-01-01
Kinetics and continuum emission of negative ions are studied in stationary atomic hydrogen, nitrogen, and oxygen plasmas. The intensity of the negative-ion emission was found to be neglibible when compared to those of bound-bound and free-bound emission at low and medium particle densities. However, the negative-ion continuum emission can contribute significantly in certain parts of the emission spectrum at high particle densities.
Plasma kinetics of a chylomicron-like emulsion in patients with coronary artery disease
Raul C. Maranhão; Márcia C. Feres; Márcia T. Martins; Carlos H. Mesquita; Odaly Toffoletto; Carmen G. C. Vinagre; Sergio D. Gianinni; Fulvio Pileggi
1996-01-01
Chylomicron catabolism in the bloodstream consists of lipolysis by lipoprotein lipase and uptake of remnants by the liver. In rats, triglyceride-rich emulsions can mimic chylomicron metabolism. To further validate this model in man, the emulsion was injected intravenously into fasting and into subjects previously fed a test fatty meal. The plasma kinetic curves of the emulsion 3H-triglyceride and 14C-cholesteryl ester
Hariton, C; Jadot, G; Mesdjian, E; Mandel, P
1985-01-01
The regional distribution of diazepam (DZP) was established in eleven discrete brain areas in the rat after i.m. chronic treatment (15 days; 5 mg/kg/day). In addition, the kinetic profiles of this drug were investigated in plasma, eryhtrocytes, and three CNS regions (nucleus caudatus, hippocampus, and cerebellum) upon which the pharmacokinetic study was focused. The modifications occuring in plasma-protein binding and erythrocytes binding were reported. In the CNS, the DZP was rapidly distributed; its concentrations and its kinetic profiles were not uniform in the different brain areas studied. The highest amount of DZP was noted in the hypothalamus, while nucleus caudatus and colliculi also presented important DZP levels. Concerning the kinetic parameters after chronic administration, an increase in the elimination half-life time value in central and peripheral compartments, as compared to values reported after acute administration, was observed. The study of cerebral DZP levels as compared with those in the erythrocytes or in plasma suggests a linear correlation in the three CNS areas investigated. These experimental results demonstrate the interest of such studies for psychotropic drug monitoring. PMID:4043139
Kinetic plasma processes occurring in the outer plasmasphere
NASA Technical Reports Server (NTRS)
Wilson, Gordon R.
1992-01-01
One area of data analysis work that was begun under this contract is the fitting of the perpendicular velocity distributions of equatorially trapped ions with a Kappa function. This type of characterization of the trapped ions will be very useful for comparison with velocity distributions produced by the model. A second area of data analysis is to study data from consecutive passes when DE 1's apogee was near the magnetic equator and the spacecraft was often skimming along nearly the same L shell. In 1982 three such periods occurred in May, June, and July. For these consecutive events we have Kp histories, density measurements from a number of sources (Whistler data, DE SFR, ISEE SFR) and consecutive samples of ion pitch angle distributions along field lines. It is clear from this data how the pitch angle distributions evolve during a flux tube refilling event. Our modeling of the flow of plasma along closed field lines is following two basic tracks. The first is a study of the basic refilling process without the effect of wave-particle heating near the equator or the effect of large or abrupt field-aligned electric potential drops. This model includes the effects of Coulomb self-collisions and collisions with the O+ ions in the topside ionosphere. The second track is a study of the effects of wave produced pitch-angle scattering and perpendicular heating occurring near the magnetic equator, in connection with the development of large potential drops that result from electron heating and the development of density gradients.
Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.
2009-04-23
This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the "inertial range" above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvenic fluctuations and a passive cascade of density and magnetic-fieldstrength fluctuations. The former are governed by the Reduced Magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvenic component (in the collisional limit, these compressive fluctuations become the slow and entropy modes of the conventional MHD). In the "dissipation range" below ion gyroscale, there are again two cascades: the kinetic-Alfven-wave (KAW) cascade governed by two fluid-like Electron Reduced Magnetohydrodynamic (ERMHD) equations and a passive cascade of ion entropy fluctuations both in space and velocity. The latter cascade brings the energy of the inertial-range fluctuations that was Landau-damped at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAWenergy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for all of these cascades. The relationship between the theoretical models proposed in this paper and astrophysical applications and observations is discussed in detail.
Core Physics and Kinetics Calculations for the Fissioning Plasma Core Reactor
NASA Technical Reports Server (NTRS)
Butler, C.; Albright, D.
2007-01-01
Highly efficient, compact nuclear reactors would provide high specific impulse spacecraft propulsion. This analysis and numerical simulation effort has focused on the technical feasibility issues related to the nuclear design characteristics of a novel reactor design. The Fissioning Plasma Core Reactor (FPCR) is a shockwave-driven gaseous-core nuclear reactor, which uses Magneto Hydrodynamic effects to generate electric power to be used for propulsion. The nuclear design of the system depends on two major calculations: core physics calculations and kinetics calculations. Presently, core physics calculations have concentrated on the use of the MCNP4C code. However, initial results from other codes such as COMBINE/VENTURE and SCALE4a. are also shown. Several significant modifications were made to the ISR-developed QCALC1 kinetics analysis code. These modifications include testing the state of the core materials, an improvement to the calculation of the material properties of the core, the addition of an adiabatic core temperature model and improvement of the first order reactivity correction model. The accuracy of these modifications has been verified, and the accuracy of the point-core kinetics model used by the QCALC1 code has also been validated. Previously calculated kinetics results for the FPCR were described in the ISR report, "QCALC1: A code for FPCR Kinetics Model Feasibility Analysis" dated June 1, 2002.
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.
Kinetic double layers in a two electron temperature multi-ion plasma
Baboolal, S.; Bharuthram, R. (University of Durban-Westville, Durban (South Africa) Plasma Physics Research Institute, Department of Physics, University of Natal, Durban (South Africa)); Hellberg, M.A. (Plasma Physics Research Institute, Department of Physics, University of Natal, Durban (South Africa))
1990-09-01
A recent large-amplitude fluid theory of electrostatic ion-acoustic double layers (J. Plasma Phys. {bold 40}, 163 (1988)) is shown to be adaptable to the case of stationary double layers in a two-ion plasma with kinetically determined ions. The influence of ion temperature and light-ion concentration on the double-layer structure is studied and directly compared with fluid theory predictions. The role of the ion trapping parameter is examined. It is found that departure from fluid theory can be explained as being due to the influence of ion Landau damping and/or ion trapping. Extension of the theory to multielectron and multi-ion plasmas is pointed out.
Kinetic Approach to an Adiabatic R-Compression of Tokamak Plasmas
NASA Astrophysics Data System (ADS)
Gorelenkova, M. V.; Gorelenkov, N. N.; Azizov, E. A.; Romannikov, A. N.
1997-11-01
footnotetext[1]Present address: Princeton Plasma Physics Laboratory, P.0. Box 451, Princeton, NJ 08543 An adiabatic major radius compression of the tokamak plasma (R-compression) had been used to study the behavior of energetic particles near the passing-trapped boundary on TFTR [H. Herrman, Ph.D. thesis, Princeton University, 1997]. An unexplained losses of partially thermalized bearly trapped ?-particles at different plasma conditions were uncovered. To study the transitions between the trapped and passing particles near the loss cone during the compression an analytical model is developed. The equation for the variation of the particle velocity during the compression is derived. We introduce the perpendicular electric field from Ohm's law at zero resistivity E=-vE × B/c , which leads to the equation for the particle energy ( d\\cal E/dt=eE \\cdot v_dr, ) where vE is the plasma velocity vector during the compression and v_dr is particle toroidal drift velocity. Expressions for particle energy and pitch angle change of passing and trapped particles are obtained for plasma with high aspect ratio and circular magnetic surfaces. Basing on these equations and solving the drift kinetic equation we also analyze plasma macro parameters, density and temperature in different regimes with the respect to the collisionality.
Kinetic Approach to an Adiabatic R-Compression of Tokamak Plasmas.
NASA Astrophysics Data System (ADS)
Gorelenkova, M. V.; Gorelenkov, N. N.; Azizov, E. A.; Romannikov, A. N.
1997-11-01
footnotetext[1]Present address: Princeton Plasma Physics Laboratory, P.0. Box 451, Princeton, NJ 08543 An adiabatic major radius compression of the tokamak plasma (R-compression) had been used to study the behavior of energetic particles near the passing-trapped boundary on TFTR [H. Herrman, Ph.D. thesis, Princeton University, 1997]. An unexplained losses of partially thermalized bearly trapped ?-particles at different plasma conditions were uncovered. To study the transitions between the trapped and passing particles near the loss cone during the compression an analytical model is developed. The equation for the variation of the particle velocity during the compression is derived. We introduce the perpendicular electric field from Ohm's law at zero resistivity E=-vE × B/c , which leads to the equation for the particle energy ( d\\cal E/dt=eE \\cdot v_dr, ) where vE is the plasma velocity vector during the compression and v_dr is particle toroidal drift velocity. Expressions for particle energy and pitch angle change of passing and trapped particles are obtained for plasma with high aspect ratio and circular magnetic surfaces. Basing on these equations and solving the drift kinetic equation we also analyze plasma macro parameters, density and temperature in different regimes with the respect to the collisionality.
Boonpawa, Rungnapa; Spenkelink, Albertus; Rietjens, Ivonne M C M; Punt, Ans
2014-05-15
Biological activities of flavonoids in vivo are ultimately dependent on the systemic bioavailability of the aglycones as well as their metabolites. In the present study, a physiologically based kinetic (PBK) model was developed to predict plasma concentrations of the flavonoid quercetin and its metabolites and to tentatively identify the regiospecificity of the major circulating metabolites. The model was developed based on in vitro metabolic parameters and by fitting kinetic parameters to literature available in vivo data. Both exposure to quercetin aglycone and to quercetin-4'-O-glucoside, for which in vivo data were available, were simulated. The predicted plasma concentrations of different metabolites adequately matched literature reported plasma concentrations of these metabolites in rats exposed to 4'-O-glucoside. The bioavailability of aglycone was predicted to be very low ranging from 0.004%-0.1% at different oral doses of quercetin or quercetin-4'-O-glucoside. Glucuronidation was a crucial pathway that limited the bioavailability of the aglycone, with 95-99% of the dose being converted to monoglucuronides within 1.5-2.5h at different dose levels ranging from 0.1 to 50mg/kg bw quercetin or quercetin-4'-O-glucoside. The fast metabolic conversion to monoglucuronides allowed these metabolites to further conjugate to di- and tri-conjugates. The regiospecificity of major circulating metabolites was observed to be dose-dependent. As we still lack in vivo kinetic data for many flavonoids, the developed model has a great potential to be used as a platform to build PBK models for other flavonoids as well as to predict the kinetics of flavonoids in humans. PMID:24561179
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.
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).
Kinetics of ion and prompt electron emission from laser-produced plasma
Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States) [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China); Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Ding, H. [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)] [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)
2013-07-15
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.
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.
High-order continuum kinetic Vlasov-Poisson simulations of magnetized plasmas
NASA Astrophysics Data System (ADS)
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-10-01
Continuum methods offer a high-fidelity means of simulating plasma kinetics as modeled by the Boltzmann-Maxwell equation system. These methods are advantageous because they can be cast in conservation law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Thereby the methods can conserve mass, momentum, and energy to a high degree. A fourth-order accurate finite volume method has been developed to solve the continuum kinetic Vlasov-Poisson equation system in one spatial and two velocity dimensions. The method is validated in cartesian coordinates using the Dory-Guest-Harris instability, which is a special case of a perpendicularly-propagating kinetic electrostatic wave in a warm uniformly magnetized plasma. The instability dispersion relation, and its generalization to arbitrary distribution functions, are demonstrated to be well-suited benchmarks for continuum algorithms in higher-dimensional phase space. The numerical method has also been extended to two spatial dimensions, and has been implemented in cylindrical coordinates to simulate axisymmetric configurations such as a Z-pinch. This work was supported by the DOE SCGF fellowship, and grants from DOE ASCR and AFOSR.
Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.
1993-03-01
Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.
Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.
1993-01-01
Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.
Kinetics of general electromagnetic fluctuations in unmagnetized plasmas: aperiodic thermal noise
NASA Astrophysics Data System (ADS)
Schlickeiser, R.; Yoon, P. H.
2015-01-01
Any fully-ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations which are of three different types: weakly damped, weakly propagating or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas is governed by the competition of spontaneous emission, absorption and stimulated emission processes. The generalized Kirchhoff laws for both collective and non-collective fluctuations are derived, which in stationary plasmas provide the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission and true absorption coefficients. The equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron–proton plasma of density ne is calculated as \\mid ? B\\mid =\\sqrt{{{(? B)}2}}=2.8{{({{n}e}{{m}e}{{c}2})}1/2}{{g}1/2}? e7/4 and \\mid ? E\\mid =\\sqrt{{{(? E)}2}}=3.2{{({{n}e}{{m}e}{{c}2})}1/2}{{g}1/3}? e2 , where g and ?e denote the plasma parameter and the thermal electron velocity in units of the speed of light. For densities and temperatures of the reionized early intergalactic medium ??B? = 6 · 10?18 G and ??E? = 2 · 10?16 G result.
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. [Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Brunner, S. [Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CRPP-PPB, CH-1015 Lausanne (Switzerland); Valeo, E. J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)
2013-03-15
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.
Electron and ion kinetic effects on non-linearly driven electron plasma and ion acoustic waves
NASA Astrophysics Data System (ADS)
Berger, R. L.; Brunner, S.; Chapman, T.; Divol, L.; Still, C. H.; Valeo, E. J.
2013-03-01
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 Te/Ti ? 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.
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 microtearing modes and reconnecting modes in strongly magnetised slab plasmas
NASA Astrophysics Data System (ADS)
Zocco, A.; Loureiro, N. F.; Dickinson, D.; Numata, R.; Roach, C. M.
2015-06-01
The problem of the linear microtearing mode in a slab magnetised plasma, and its connection to kinetic reconnecting modes, is addressed. Electrons are described using a novel hybrid fluid-kinetic model that captures electron heating, ions are gyrokinetic. Magnetic reconnection can occur as a result of either electron conductivity and inertia, depending on which one predominates. We eschew the use of an energy dependent collision frequency in the collisional operator model, unlike previous works. A model of the electron conductivity that matches the weakly collisional regime to the exact Landau result at zero collisionality and gives the correct electron isothermal response far from the reconnection region is presented. We identify in the breaking of the constant-A? approximation the necessary condition for microtearing instability in the collisional regime. Connections with the theory of collisional non-isothermal (or semicollisional) and collisionless tearing-parity electron temperature gradient driven (ETG) modes are elucidated.
Kinetic theory of QED plasma in a strong electromagnetic field I. The covariant hyperplane formalism
A. Hoell; V. G. Morozov; G. Roepke
2001-06-01
We develop a covariant density matrix approach to kinetic theory of QED plasmas subjected into a strong external electromagnetic field. A canonical quantization of the system on space-like hyperplanes in Minkowski space and a covariant generalization of the Coulomb gauge is used. The condensate mode associated with the mean electromagnetic field is separated from the photon degrees of freedom by a time-dependent unitary transformation of both, the dynamical variables and the nonequilibrium statistical operator. Therefore even in the case of strong external fields a perturbative expansion in orders of the fine structure constant for the correlation functions as well as the statistical operator is applicable. A general scheme for deriving kinetic equations in the hyperplane formalism is presented.
Lai, W. N. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)] [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Chapman, S. C. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom) [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Department of Mathematics and Statistics, University of Tromsø, Tromsø (Norway); Dendy, R. O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom) [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)
2013-10-15
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.
Stability of the kinetic Alfven wave in a current-less plasma
NASA Astrophysics Data System (ADS)
Sreekala, G.; Sebastian, Sijo; Michael, Manesh; Abraham, Noble P.; Renuka, G.; Venugopal, Chandu
2015-06-01
The two potential theory of Hasegawa has been used to derive the dispersion relation for the kinetic Alfven wave (KAW) in a plasma composed of hydrogen, oxygen and electrons. All three components have been modeled by ring distributions (obtained by subtracting two Maxwellian distributions with different temperatures) with the hydrogen and electrons drifting, respectively, with velocities VdH and Vde. For the most general case, the dispersion relation is a polynomial equation of order five; it reduces to a relation which supports only one mode when VdH = 0. For typical parameters at comet Halley, we find that both VdH and Vde can drive the wave unstable; the KAW is thus driven unstable in a current-less plasma. Such an instability was found for the ion acoustic wave by Vranjes et al. (2009).
Kinetic Alfven wave instability in a Lorentzian dusty plasma: Non-resonant particle approach
NASA Astrophysics Data System (ADS)
Rubab, N.; Erkaev, V.; Biernat, H. K.; Langmayr, D.
2011-07-01
Analysis of the electromagnetic streaming instability is carried out which is related to the cross field drift of kappa distributed ions. The linear dispersion relation for electromagnetic wave using Vlasov-fluid equations in a dusty plasma is derived. Modified two stream instability (MTSI) in a dusty plasma has been discussed in the limit ?pd2/c2k?2?1. Numerical calculations of the growth rate of instability have been carried out. Growth rates of kinetic Alfvén instability are found to be small as compared to MTSI. Maximum growth rates for both instabilities occur in oblique directions for V0?VA. It is shown that the presence of both the charged dust particles and perpendicular ion beam sensibly modify the dispersion relation of low-frequency electromagnetic wave. The dispersion characteristics are found to be insensible to the superthermal character of the ion distribution function. Applications to different intersteller regions are discussed.
van de Pas, Niek C A; Rullmann, Johan A C; Woutersen, Ruud A; van Ommen, Ben; Rietjens, Ivonne M C M; de Graaf, Albert A
2014-08-01
We used a previously developed physiologically based kinetic (PBK) model to analyze the effect of individual variations in metabolism and transport of cholesterol on pravastatin response. The PBK model is based on kinetic expressions for 21 reactions that interconnect eight different body cholesterol pools including plasma HDL and non-HDL cholesterol. A pravastatin pharmacokinetic model was constructed and the simulated hepatic pravastatin concentration was used to modulate the reaction rate constant of hepatic free cholesterol synthesis in the PBK model. The integrated model was then used to predict plasma cholesterol concentrations as a function of pravastatin dose. Predicted versus observed values at 40 mg/d pravastatin were 15 versus 22 % reduction of total plasma cholesterol, and 10 versus 5.6 % increase of HDL cholesterol. A population of 7,609 virtual subjects was generated using a Monte Carlo approach, and the response to a 40 mg/d pravastatin dose was simulated for each subject. Linear regression analysis of the pravastatin response in this virtual population showed that hepatic and peripheral cholesterol synthesis had the largest regression coefficients for the non-HDL-C response. However, the modeling also showed that these processes alone did not suffice to predict non-HDL-C response to pravastatin, contradicting the hypothesis that people with high cholesterol synthesis rates are good statin responders. In conclusion, we have developed a PBK model that is able to accurately describe the effect of pravastatin treatment on plasma cholesterol concentrations and can be used to provide insight in the mechanisms behind individual variation in statin response. PMID:25106950
NASA Astrophysics Data System (ADS)
Giuliani, John L.
2006-10-01
Non-LTE discharges used in lighting sources provide an excellent testbed for understanding the interplay between plasma, atomic, and radiation physics. Standard models for the Hg fluorescent bulb include non-equilibrium kinetics for the species, but employ both a 0-D Boltzmann equation for the electron distribution function (EDF) and Holstein's probability-of-escape for radiation transport. These assumptions overlook some of the more interesting, and challenging, aspects of plasma lighting. The radial ambipolar potential requires the inclusion of the spatial gradient term in the inhomogeneous electron Boltzmann equation. The resulting EDF is found to depend on both electron energy and radial position [1]. Advanced radiation transport techniques account for non-local photo-pumping, line overlap within the Hg resonance lines, and partial frequency redistribution [2]. The results of our completely coupled model match the observed spatial distribution of Hg excited states and the line-of-sight intensity [3]. Due to environmental initiatives there is also recent interest in non-Hg discharges for high intensity lighting. One example is an RF electrodeless Mo-O-Ar plasma discharge bulb which operates by recycling the emitting Mo with an O catalyst. Based on atomic physics calculations for Mo [4], the kinetic pathways leading to visible emission can be identified [5] and explain the measured lighting efficiency of ˜40 lumens/watt of supplied power.[1] J. Appl. Phys., 94, p.62, 2003. [2] Plasma Sources Sci. Tech., 14, p.236, 2005. [3] J. Phys. D., 38, p.4180, 2005. [4] New J. Physics, 6, p.145, 2004. [5] J. Appl. Phys., 95, p.5284, 2004.
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).
Vlasov-Maxwell kinetic simulations of radio-frequency-driven ion flows in magnetized plasmas.
Marchetto, Chiara; Califano, Francesco; Lontano, Maurizio
2003-02-01
The generation of a coherent ion flow due to the injection in a plasma of a purely electrostatic wave of finite amplitude, propagating at right angle with the ambient uniform magnetic field, is investigated making use of a kinetic code which solves the fully nonlinear Vlasov equations for electrons and ions, coupled with the Maxwell equations, in one spatial and two velocity dimensions. A uniformly magnetized slab plasma is considered. The wave frequency is assumed in the range of the fourth harmonic of the ion cyclotron frequency, and the wave vector is chosen in order to model the propagation of an ion Bernstein wave. The computation of the first-order moment of the ion distribution function shows that indeed a quasistationary transverse average ion drift velocity is produced. The time evolution of the ion distribution function undergoes a "resonant" interaction of Cherenkov type, even if the plasma ions are magnetized (omega(ci)/omega(pi) approximately 0.5). During the wave-plasma interaction, the electron distribution function remains Gaussian-like, while increasing its energy content. PMID:12636820
NASA Astrophysics Data System (ADS)
Zarzoso, D.; Garbet, X.; Sarazin, Y.; Dumont, R.; Grandgirard, V.
2012-02-01
We show in this paper that geodesic acoustic modes (GAMs) can be efficiently excited by a population of fast ions even when Landau damping on thermal ions is accounted for. We report in particular fully kinetic calculations of the GAM dispersion relation and its complete solution. Written under a variational form, the quasi-neutrality condition, together with the kinetic Vlasov equation, leads to the density of exchanged energy between particles and the mode. In particular, a linear threshold for the GAMs excitation is derived. Two examples of fast ion distribution have been discussed analytically. It turns out that particles with high perpendicular energy compared to the parallel resonance energy are most responsible for the excitation of the mode. Subsequent numerical simulations of circular plasmas using gysela code have been carried out. In particular, the linear kinetic threshold has been reproduced during the excitation phase, and a nonlinear saturation has been observed. Analysis in the phase space of the evolution of the equilibrium distribution function is presented and the saturation level quantified.
A DRIFT ORDERED SHORT MEAN-FREE DESCRIPTION FOR PARTIALLY IONIZED MAGNETIZED PLASMA
SIMAKOV, ANDERI N. [Los Alamos National Laboratory
2007-02-08
Effects of neutral particles, most prominently the associated heat flux and viscosity, can be very important or even dominant at the edge of a tokamak and so must be self-consistently accounted for in a description of magnetized tokamak edge plasma. To the best of our knowledge, this has only been done so far for short mean-free path plasma under MHD-like Braginskii's orderings i.e. assuming that species velocities are on the order of the ion thermal speed. Since plasma flows in modern tokamaks are usually slow compared with the ion thermal speed (at least in the absence of strong external momentum sources) it is more appropriate to use drift orderings in which the plasma flow velocity is instead comparable with the diamagnetic heat flow divided by pressure. Employing drift orderings and evaluating species distribution functions through second order in the small gyroradius and mean-free path expansion parameters allows accounting for the important effects of heat fluxes on species momentum transport (viscosities), which are missing from the large flow ordered treatments. In this work we consider short mean-free path plasma consisting of electrons and single species of singly-charged ions and neutrals. We neglect neutral-neutral and elastic electron-neutral collisions and approximate the neutral-ion charge-exchange cross-section with a constant. We employ drift orderings to evaluate ion, neutral, and electron heat fluxes, viscosity tensors, and momentum and energy exchange terms and formulate a self-consistent system of electron, ion, and neutral fluid equations, thereby generalizing the drift-ordered treatment of fully ionized plasma.
Nitric oxide kinetics in the afterglow of a diffuse plasma filament
NASA Astrophysics Data System (ADS)
Burnette, D.; Montello, A.; Adamovich, I. V.; Lempert, W. R.
2014-08-01
A suite of laser diagnostics is used to study kinetics of vibrational energy transfer and plasma chemical reactions in a nanosecond pulse, diffuse filament electric discharge and afterglow in N2 and dry air at 100 Torr. Laser-induced fluorescence of NO and two-photon absorption laser-induced fluorescence of O and N atoms are used to measure absolute, time-resolved number densities of these species after the discharge pulse, and picosecond coherent anti-Stokes Raman spectroscopy is used to measure time-resolved rotational temperature and ground electronic state N2(v = 0-4) vibrational level populations. The plasma filament diameter, determined from plasma emission and NO planar laser-induced fluorescence images, remains nearly constant after the discharge pulse, over a few hundred microseconds, and does not exhibit expansion on microsecond time scale. Peak temperature in the discharge and the afterglow is low, T ? 370 K, in spite of significant vibrational nonequilibrium, with peak N2 vibrational temperature of Tv ? 2000 K. Significant vibrational temperature rise in the afterglow is likely caused by the downward N2-N2 vibration-vibration (V-V) energy transfer. Simple kinetic modeling of time-resolved N, O, and NO number densities in the afterglow, on the time scale longer compared to relaxation and quenching time of excited species generated in the plasma, is in good agreement with the data. In nitrogen, the N atom density after the discharge pulse is controlled by three-body recombination and radial diffusion. In air, N, NO and O concentrations are dominated by the reverse Zel'dovich reaction, N + NO ? N2 + O, and ozone formation reaction, O + O2 + M ? O3 + M, respectively. The effect of vibrationally excited nitrogen molecules and excited N atoms on NO formation kinetics is estimated to be negligible. The results suggest that NO formation in the nanosecond pulse discharge is dominated by reactions of excited electronic states of nitrogen, occurring on microsecond time scale.
NASA Technical Reports Server (NTRS)
Catto, P. J.
1979-01-01
A simpler technique than those introduced by Lenard and Bernstein (1958), and Dougherty (1964) is employed to obtain the perturbed species density from a specified kinetic equation for a plasma in a given uniform magnetic field. The technique is a generalization of the velocity-Fourier transform method employed by Karpman (1967) for B sub 0 identical to zero, and relies on the fact that in transform space the model collision operator, used to obtain the kinetic equation for waves in a magnetized plasma, contains only first derivatives. The technique is illustrated by evaluating the perturbed density of an arbitrary species.
Kinetic processes for laser induced plasma diagnostic: A collisional-radiative model approach
NASA Astrophysics Data System (ADS)
Pietanza, L. D.; Colonna, G.; De Giacomo, A.; Capitelli, M.
2010-08-01
A zero-dimensional collisional-radiative (CR) model, coupled self-consistently with the electron Boltzmann equation, has been applied to the description of a metallic-laser induced plasma at experimental conditions typical of LIBS experiment. To take in account expansion effects, the experimental temperature and total number density as function of time have been used as input data. Plasma composition and the simultaneous time evolution of both heavy particle level distributions and the electron energy distribution function have been calculated by taking into account the most relevant collisional and radiative processes. This approach estimates the hierarchy of the elementary processes during the expansion and possible deviations from LTE conditions. The comparison of the experimental and theoretical results shows a good agreement, but at the same time new questions arise on the analysis of spectroscopic results and on the assumption generally made in LIBS.
Kinetic studies on CF/sub 4/ plasmas during etching of Si
Brandt, W.W.; Roselle, P.
1983-09-01
Mass spectrometric kinetic measurements were performed on a dc plasma during the etching of Si by CF/sub 4/. The apparatus and procedures used were identical to those developed and used in an earlier study dealing with the Si/SF/sub 6/ system. The signals representative of CF/sup +//sub 3/, CF/sup +//sub 2/, CF/sup +/, F/sup +/, SiF/sup +//sub 3/, SiF/sup +/, and C/sub 2/F/sup +//sub 5/ were studied in some detail. CF/sup +//sub 3/ and CF/sup +//sub 2/ transients produced by stepwise changes of the applied voltage were found to be very similar, on a fractional basis. CF/sup +/ and C/sub 2/F/sup +//sub 5/ signals showed a close correlation, while the F/sup +/ signals indicated a small amount of extra fluorine atoms or ions to be present at relatively high applied voltages. The initial transient rates, following plasma ignition, tended to be slower than those obtained at the higher applied voltages, so the sample surface is somehow etched more rapidly after the first few seconds. In contrast to this, slow signal changes of the sort observed in the Si/SF/sub 6/ system were absent, so the carbonaceous layers which may form on the Si sample surface appear to adjust rapidly to composition changes in the plasma.
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.
van de Pas, Niek C. A.; Woutersen, Ruud A.; van Ommen, Ben; Rietjens, Ivonne M. C. M.; de Graaf, Albert A.
2012-01-01
Increased plasma cholesterol concentration is associated with increased risk of cardiovascular disease. This study describes the development, validation, and analysis of a physiologically based kinetic (PBK) model for the prediction of plasma cholesterol concentrations in humans. This model was directly adapted from a PBK model for mice by incorporation of the reaction catalyzed by cholesterol ester transfer protein and contained 21 biochemical reactions and eight different cholesterol pools. The model was calibrated using published data for humans and validated by comparing model predictions on plasma cholesterol levels of subjects with 10 different genetic mutations (including familial hypercholesterolemia and Smith-Lemli-Opitz syndrome) with experimental data. Average model predictions on total cholesterol were accurate within 36% of the experimental data, which was within the experimental margin. Sensitivity analysis of the model indicated that the HDL cholesterol (HDL-C) concentration was mainly dependent on hepatic transport of cholesterol to HDL, cholesterol ester transfer from HDL to non-HDL, and hepatic uptake of cholesterol from non-HDL-C. Thus, the presented PBK model is a valid tool to predict the effect of genetic mutations on cholesterol concentrations, opening the way for future studies on the effect of different drugs on cholesterol levels in various subpopulations in silico. PMID:23024287
Kinetic effects and nonlinear heating in intense x-ray-laser-produced carbon plasmas
NASA Astrophysics Data System (ADS)
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 (>1 eV ), an energy density greater than 104 J /cm3 , 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.
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
Jasperse, J.R.
1984-06-25
A propagator expansion method is presented for solving linearized plasma kinetic equations with collisions. The essence of the method is the representation and use of the collisional propagator for a given problem as an expansion in powers of the collision frequency. The linearized Balescu-Lenard collision operator and the zero-order distribution function Maxwellian were determined. An exact expression for the collisional damping rate is obtained in the long-wavelength approximation to the first order in the plasma parameter.
Predictive Fully Kinetic Modeling of kJ and MJ Dense Plasma Focus Z-Pinches
NASA Astrophysics Data System (ADS)
Link, A.; Ellsworth, J.; Falabella, S.; McLean, H.; Rusnak, B.; Schmidt, A.; Sears, J.; Tang, V.; Welch, D.
2013-10-01
Dense plasma focus (DPF) Z-pinches are compact devices capable of producing MeV ion beams, x-rays, and (for D or DT gas fill) neutrons but the details of the mechanisms which give rise to these strong accelerating gradients are not well understood. We report on progress in developing predictive, fully kinetic simulations of DPF Z-Pinches using the particle-in-cell code LSP. These simulations include full-scale electrodes; both run-in and pinch phases; and post-pinch behavior. Here we present a comparison between simulations and experiments conducted on the LLNL 4 kJ tabletop DPF. Diagnostics allow us to measure neutron yield, plasma oscillations arising from instabilities, DPF ion beam energies, and the acceleration of an externally injected ion probe beam in the pinch region, which can be compared with simulations. We will further report on the initial work to extend these simulations from kJ to MJ-class devices. LLNL-ABS-640759. Dense plasma focus (DPF) Z-pinches are compact devices capable of producing MeV ion beams, x-rays, and (for D or DT gas fill) neutrons but the details of the mechanisms which give rise to these strong accelerating gradients are not well understood. We report on progress in developing predictive, fully kinetic simulations of DPF Z-Pinches using the particle-in-cell code LSP. These simulations include full-scale electrodes; both run-in and pinch phases; and post-pinch behavior. Here we present a comparison between simulations and experiments conducted on the LLNL 4 kJ tabletop DPF. Diagnostics allow us to measure neutron yield, plasma oscillations arising from instabilities, DPF ion beam energies, and the acceleration of an externally injected ion probe beam in the pinch region, which can be compared with simulations. We will further report on the initial work to extend these simulations from kJ to MJ-class devices. LLNL-ABS-640759. 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.
Hypovalency--a kinetic-energy density description of a 4c-2e bond.
Jacobsen, Heiko
2009-06-01
A bond descriptor based on the kinetic energy density, the localized-orbital locator (LOL), is used to characterize the nature of the chemical bond in electron deficient multi-center bonds. The boranes B(2)H(6), B(4)H(4), B(4)H(10), [B(6)H(6)](2-), and [B(6)H(7)](-) serve as prototypical examples of hypovalent 3c-2e and 4c-2e bonding. The kinetic energy density is derived from a set of Kohn-Sham orbitals obtained from pure density functional calculations (PBE/TZVP), and the topology of LOL is analyzed in terms of (3,-3) attractors (Gamma). The B-B-B and B-H-B 3c-2e, and the B-B-H-B 4c-2e bonding situations are defined by their own characteristic LOL profiles. The presence of one attractor in relation to the three or four atoms that are engaged in electron deficient bonding provides sufficient indication of the type of 3c-2e or 4c-2e bond present. For the 4c-2e bond in [B(6)H(7)](-) the LOL analysis is compared to results from an experimental QTAIM study. PMID:19452076
Renormalized non-modal theory of the kinetic drift instability of plasma shear flows
Mikhailenko, V. S.; Mikhailenko, V. V. [Department of Physics and Technology, V. N. Karazin Kharkov National University, 61108 Kharkov (Ukraine); Stepanov, K. N. [National Science Center, 'Kharkov Institute of Physics and Technology', 61108 Kharkov (Ukraine)
2011-06-15
The linear and renormalized nonlinear kinetic theory of drift instability of plasma shear flow across the magnetic field, which has the Kelvin's method of shearing modes or the so-called non-modal approach as its foundation, is developed. The developed theory proves that the time-dependent effect of the finite ion Larmor radius is the key effect, which is responsible for the suppression of drift turbulence in an inhomogeneous electric field. This effect leads to the non-modal decrease of the frequency and growth rate of the unstable drift perturbations with time. We find that turbulent scattering of the ion gyrophase is the dominant effect which determines the extremely rapid suppression of drift turbulence in shear flow.
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.
A. V. Zobnin; A. D. Usachev; O. F. Petrov; V. E. Fortov
2008-01-01
The ion flux on a small attractive sphere (the sphere radius is much less than the Debye length) and the electric potential distribution around the sphere charged in a stationary weakly ionized plasma are calculated by the direct solution of the kinetic equation with the Bhatnagar–Gross–Krook collision term. Only a weak dependence of the ion flux on the electron temperature
A. V. Zobnin; A. D. Usachev; O. F. Petrov; V. E. Fortov
2008-01-01
The ion flux on a small attractive sphere (the sphere radius is much less than the Debye length) and the electric potential distribution around the sphere charged in a stationary weakly ionized plasma are calculated by the direct solution of the kinetic equation with the Bhatnagar-Gross-Krook collision term. Only a weak dependence of the ion flux on the electron temperature
Fully kinetic simulations of magnetic reconnction in semi-collisional plasmas
Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim S [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Karimabadi, Homa [UCSD
2009-01-01
The influence of Coulomb collisions on the dynamics of magnetic reconnection is examined using fully kinetic simulations with a Monte-Carlo treatment of the Fokker-Planck collision operator. This powerful first-principles approach offers a bridge between kinetic and fluid regimes, which may prove useful for understanding the applicability of various fluid models. In order to lay the necessary groundwork, the collision algorithm is first carefully bench marked for a homogeneous plasma against theoretical predictions for beam-plasma interactions and electrical resistivity. Next, the collisional decay of a current layer is examined as a function of guide field, allowing direct comparisons with transport theory for the parallel and perpendicular resistivity as well as the thermoelectric force. Finally, the transition between collisional and collision less reconnection is examined in neutral sheet geometry. For modest Lundquist numbers S {approx}< 1000, a distinct transition is observed when the thickness of the Sweet-Parker layers falls below the ion inertia length {delta}{sub sp} {approx}< d,. At higher Lundquist number, deviations from the Sweet-Parker scaling are observed due to the growth of plasmoids (secondary-islands) within the elongated resistive layer. In certain cases, this instability leads to the onset of fast reconnection sooner than expected from {delta}{sub sp} {approx} d, condition. After the transition to fast reconnection, elongated electron current layers are formed which are unstable to the formation of new plasmoids. The structure and time-dependence of the electron diffusion region in these semi-collisional regimes is profoundly different than reported in two-fluid simulations.
Kinetic simulation of the O-X conversion process in dense magnetized plasmas
Ali Asgarian, M. [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of) [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Verboncoeur, J. P. [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States)] [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Parvazian, A. [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)] [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Trines, R. [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom)] [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom)
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.
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.
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).
Jet-induced gauge field instabilities in the quark-gluon plasma: A kinetic theory approach
Mannarelli, Massimo; Manuel, Cristina [Instituto de Ciencias del Espacio (IEEC/CSIC), Campus Universitat Autonoma de Barcelona, Facultat de Ciencies, Torre C5 E-08193 Bellaterra, Barcelona (Spain)
2008-03-01
We discuss the properties of the collective modes of a system composed by a thermalized quark-gluon plasma traversed by a relativistic jet of partons. The transport equations obeyed by the components of the plasma and of the jet are studied in the Vlasov approximation. Assuming that the partons in the jet can be described with a tsunamilike distribution function we derive the expressions of the dispersion law of the collective modes. Then the behavior of the unstable gauge modes of the system is analyzed for various values of the velocity of the jet, of the momentum of the collective modes and of the angle between these two quantities. We find that the most unstable modes are those with momentum orthogonal to the velocity of the jet and that these instabilities appear when the velocity of the jet is higher than a threshold value, which depends on the plasma and jet frequencies. The results obtained within the Vlasov approximation are compared with the corresponding results obtained using a chromohydrodynamical approach. The effect we discuss here suggests a possible collective mechanism for the description of the jet quenching phenomena in heavy-ion collisions.
Kinetic Alfven wave instability in a Lorentzian dusty plasma: Non-resonant particle approach
Rubab, N.; Biernat, H. K. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz (Austria); Institute of Physics, University of Graz, Universitaetplatz 5, A-8010 Graz (Austria); Erkaev, V. [Institute of Computational Modelling, 660036 Krasnoyarsk, Russia and Siberian Federal University, 660041 Krasnoyarsk (Russian Federation); Langmayr, D. [Virtual Vehicle Competence Center (vif), Inffeldgasse 21a, 8010 Graz (Austria)
2011-07-15
Analysis of the electromagnetic streaming instability is carried out which is related to the cross field drift of kappa distributed ions. The linear dispersion relation for electromagnetic wave using Vlasov-fluid equations in a dusty plasma is derived. Modified two stream instability (MTSI) in a dusty plasma has been discussed in the limit {omega}{sub pd}{sup 2}/c{sup 2}k{sub perpendicular}{sup 2}<<1. Numerical calculations of the growth rate of instability have been carried out. Growth rates of kinetic Alfven instability are found to be small as compared to MTSI. Maximum growth rates for both instabilities occur in oblique directions for V{sub 0}{>=}V{sub A}. It is shown that the presence of both the charged dust particles and perpendicular ion beam sensibly modify the dispersion relation of low-frequency electromagnetic wave. The dispersion characteristics are found to be insensible to the superthermal character of the ion distribution function. Applications to different intersteller regions are discussed.
Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch
NASA Astrophysics Data System (ADS)
Schmidt, A.; Ellsworth, J.; Falabella, S.; Link, A.; McLean, H.; Rusnak, B.; Sears, J.; Tang, V.; Welch, D.
2014-12-01
The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ˜cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications.
NASA 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.
Bezus, A.G.; Voloshchuk, A.M.; Gorlov, V.A.; Dubinin, M.M.; Zikanova, A.; Kochirzhik, M.
1987-01-10
The authors have presented an analytical description of the temperature and kinetic curves for adsorbent granules in the form of plates, and they have proposed methods for the determination of the mass- and heat-transfer parameters based on experimental temperature curves. In the case of the Xe-CaA system the adsorption process is controlled by the external heat transfer.
Péronnet, F; Meynier, A; Sauvinet, V; Normand, S; Bourdon, E; Mignault, D; St-Pierre, D H; Laville, M; Rabasa-Lhoret, R; Vinoy, S
2015-01-01
Background/Objectives: Foods with high contents of slowly digestible starch (SDS) elicit lower glycemic responses than foods with low contents of SDS but there has been debate on the underlying changes in plasma glucose kinetics, that is, respective contributions of the increase in the rates of appearance and disappearance of plasma glucose (RaT and RdT), and of the increase in the rate of appearance of exogenous glucose (RaE) and decrease in endogenous glucose production (EGP). Subjects/Methods: Sixteen young healthy females ingested in random order four types of breakfasts: an extruded cereal (0.3% SDS: Lo-SDS breakfast) or one of three biscuits (39–45% SDS: Hi-SDS breakfasts). The flour in the cereal products was labeled with 13C, and plasma glucose kinetics were measured using [6,6-2H2]glucose infusion, along with the response of plasma glucose, insulin and glucose-dependent insulinotropic peptide (GIP) concentrations. Results: When compared with the Lo-SDS breakfast, after the three Hi-SDS breakfasts, excursions in plasma glucose, the response of RaE, RaT and RdT, and the reduction in EGP were significantly lower (P<0.05). The amount of exogenous glucose absorbed over the 4.5-h postprandial period was also significantly lower by ~31% (P<0.001). These differences were associated with lower responses of GIP and insulin concentrations. Conclusions: Substituting extruded cereals with biscuits slows down the availability of glucose from the breakfast and its appearance in peripheral circulation, blunts the changes in plasma glucose kinetics and homeostasis, reduces excursions in plasma glucose, and possibly distributes the glucose ingested over a longer period following the meal. PMID:25852025
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 microRNA-499 expression in acute myocardial infarction
Chen, Xi; Zhang, Lizhu; Su, Tong; Li, Heng; Huang, Qiang; Wu, Dan
2015-01-01
Background MicroRNA (miRNA) is reported to be present in human plasma and has been increasingly suggested as a biomarker for diseases. Our study aimed to investigate the kinetics of cardiac-specific microR-499 (miR-499) in acute myocardial infarction (AMI). Methods Circulating concentrations of cardiac enriched miR-499 were measured by quantitative PCR in 73 patients with acute coronary syndrome (ACS), including 53 with AMI and 20 with unstable angina (UA). Thirty healthy subjects were used as controls. Plasma samples in AMI group were obtained immediately after admission and at 12 h, 24 h, 3 d and 7 d after onset of symptoms. Plasma samples in UA and healthy control groups were collected immediately after admission. The severity and extent of coronary stenotic lesions were evaluated on the basis of coronary angiography using Gensini score. Results miR-499 expression levels were significantly higher in the 53 AMI patients than in the 20 UA patients and 30 healthy controls immediately after admission (P<0.01). A measurable increase in miR-499 levels was observed in AMI patients within 24 h of the last onset of chest pain and the levels returned to the baseline after 7 d. Plasma miR-499 levels in the patients with AMI were positively-correlated with cTnI (r=0.384, P<0.01) and CK-MB (r=0.402, P<0.01). In addition, miR-499 levels in AMI patients with two- and three-vessel coronary artery disease (CAD) were significantly higher than those in patients with single-vessel CAD (P<0.05). Gensini scores were used to evaluate the severity of coronary stenosis. miR-499 were positively correlated with Gensini scores (r=0.52, P<0.01). miR-499 levels at admission were significantly higher than that those 24 h after percutaneous coronary intervention (PCI) in AMI patients (P<0.01) and were negatively correlated with LVEF (r=0.36, P=0.008). Conclusions Cardiac-specific miRNA-499 levels were found to be linearly proportional to myocardial damage. MiRNA-499 might prove to be a new biomarker for AMI and a predictor of the risk of myocardial ischemia.
NASA Technical Reports Server (NTRS)
Gary, S. P.
1984-01-01
This paper describes the linear kinetic theory of electrostatic instabilities driven by a density gradient drift and a magnetic-field-aligned current in a plasma with weak charged neutral collisions. The configuration is that of a uniform magnetic field B, a weak, uniform density gradient in the x direction and a weak, uniform electric field in the z direction. Collisions are represented by the BGK model. The transition from the (kinetic) universal density drift instability to the (fluidlike) current convective instability is studied in detail, and the short wavelength properties of the latter mode are investigated.
Kinetics of plasma membrane and mitochondrial alterations in cells undergoing apoptosis
Lizard, G.; Fournel, S.; Genestier, L.; Dhedin, N. [Hospital Edouard Herriot, Lyon (France)] [and others
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.
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.
Lagrangian fluid description with simple applications in compressible plasma and gas dynamics
NASA Astrophysics Data System (ADS)
Schamel, Hans
2004-03-01
The Lagrangian fluid description, in which the dynamics of fluids is formulated in terms of trajectories of fluid elements, not only presents an alternative to the more common Eulerian description but has its own merits and advantages. This aspect, which seems to be not fully explored yet, is getting increasing attention in fluid dynamics and related areas as Lagrangian codes and experimental techniques are developed utilizing the Lagrangian point of view with the ultimate goal of a deeper understanding of flow dynamics. In this tutorial review we report on recent progress made in the analysis of compressible, more or less perfect flows such as plasmas and dilute gases. The equations of motion are exploited to get further insight into the formation and evolution of coherent structures, which often exhibit a singular or collapse type behavior occurring in finite time. It is argued that this technique of solution has a broad applicability due to the simplicity and generality of equations used. The focus is on four different topics, the physics of which being governed by simple fluid equations subject to initial and/or boundary conditions. Whenever possible also experimental results are mentioned. In the expansion of a semi-infinite plasma into a vacuum the energetic ion peak propagating supersonically towards the vacuum-as seen in laboratory experiments-is interpreted by means of the Lagrangian fluid description as a relic of a wave breaking scenario of the corresponding inviscid ion dynamics. The inclusion of viscosity is shown numerically to stabilize the associated density collapse giving rise to a well defined fast ion peak reminiscent of adhesive matter. In purely convection driven flows the Lagrangian flow velocity is given by its initial value and hence the Lagrangian velocity gradient tensor can be evaluated accurately to find out the appearance of singularities in density and vorticity and the emergence of new structures such as wavelets in one-dimension (1D). In cosmology referring to the pancake model of Zel'dovich and the adhesion model of Gurbatov and Saichev, both assuming a clumping of matter at the intersection points of fluid particle trajectories (i.e. at the caustics), the foam-like large-scale structure of our Universe observed recently by Chandra X-ray observatory may be explained by the 3D convection of weakly interacting dark matter. Recent developments in plasma and nanotechnology-the miniaturization and fabrication of nanoelectronic devices being one example-have reinforced the interest in the quasi-ballistic electron transport in diodes and triodes, a field which turns out to be best treated by the Lagrangian fluid description. It is shown that the well-known space-charge-limited flow given by Child-Langmuir turns out to be incorrect in cases of finite electron injection velocities at the emitting electrode. In that case it is an intrinsic bifurcation scenario which is responsible for current limitation rather than electron reflection at the virtual cathode as intuitively assumed by Langmuir. The inclusion of a Drude friction term in the electron momentum equation can be handled solely by the Lagrangian fluid description. Exploiting the formula in case of field emission it is possible to bridge ballistic and drift-dominated transport. Furthermore, the transient processes in the electron transport triggered by the switching of the anode potential are shown to be perfectly accounted for by means of the Lagrangian fluid description. Finally, by use of the Lagrangian ion fluid equations in case of a two component, current driven plasma we derive a system of two coupled scalar wave equations which involve the specific volume of ions and electrons, respectively. It has a small amplitude strange soliton solution with unusual scaling properties. In case of charge neutrality the existence of two types of collapses are predicted, one being associated with a density excavation, the other one with a density clumping as in the laser induced ion expansion problem and in the cosmic sticking matter problem. Howev
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.
Patnaik, Pratap R
2007-01-01
Background For many microbial processes, the complexity of the metabolisms and the responses to transient and realistic conditions are difficult to capture in mechanistic models. The cells seem to have an innate intelligence that enables them to respond optimally to environmental changes. Some "intelligent" models have therefore been proposed and compared with a mechanistic model for fed-batch cultures of Ralstonia eutropha. Results Two kinds of models have been proposed to describe such cellular behavior. Cybernetic models are derived through postulates of cellular intelligence and memory, and neural models use artificial intelligence through neural networks. Some competing models of both kinds have been compared for their ability to portray and optimize the synthesis of poly-?-hydroxybutyrate by Ralstonia eutropha in fed-batch cultures with finite dispersion. Neural models enabled the formation of more of the polymer than cybernetic models, with lesser utilization of the carbon and nitrogen substrates. Both types of models were decidedly superior to a mechanistic model used as a reference, thus supporting the value of intelligent descriptions of microbial kinetics in incompletely dispersed bioreactors. Conclusion Neural and cybernetic models describe and optimize unsteady state fed-batch microbial reactors with finite dispersion more effectively than mechanistic models. However, these "intelligent" models too have weaknesses, and hence a hybrid approach combining such models with some mechanistic features is suggested. PMID:17686143
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
NASA Astrophysics Data System (ADS)
Gangwar, R.; Levasseur, O.; Stafford, L.; Naude, N.; Gherardi, N.; Univ. de Montreal Team
2013-09-01
We have recently extended the range of applications of dielectric barrier discharges (DBD) at atmospheric pressure to the functionalization of wood surfaces with the objective of improving its durability following natural weathering. Having highly complex chemical composition and microstructure, it can release significant amount of impurities, which can play a crucial role on the plasma kinetics, and therefore on the process dynamics. The influence of wood outgassing on the physics driving DBD operated in nominally pure He was investigated using a combination of time-resolved optical emission spectroscopy (OES) and collisional-radiative (CR) modeling. For completely outgassed samples, the He I 588 nm-to-707 nm and 668 nm-to-728 nm line intensity ratios were relatively high early in the discharge cycle, decreased abruptly and then remained stable as the current increased and the discharge eventually extinguished. These results were correlated to a decrease of the electron temperature from about 1 eV early in the cycle to about 0.2 eV in the main discharge lifetime. As wood outgassing evolve, study revealed that the release of products (essentially air) from the wood substrate yields to an increase of the cycle-averaged electron temperature as well as to a significant quenching of He metastable atoms. Selected experiments in presence of trace amounts of N2, O2 and dry-air were also performed to better understand their respective roles.
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.
Shear viscosity of the quark-gluon plasma in a kinetic theory approach
Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V. [Department of Physics and Astronomy, University of Catania, Via S. Sofia 64, I-95125 Catania, Italy and Laboratorio Nazionale del Sud, INFN-LNS, Via S. Sofia 63, I-95125 Catania (Italy)
2014-05-09
One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound ?/s=1/4? for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed ?/s and have a comparison with physical observables like elliptic flow.
Shear viscosity of the quark-gluon plasma in a kinetic theory approach
NASA Astrophysics Data System (ADS)
Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.
2014-05-01
One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound ?/s=1/4? for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed ?/s and have a comparison with physical observables like elliptic flow.
Transport coefficients of Quark-Gluon Plasma in a Kinetic Theory approach
NASA Astrophysics Data System (ADS)
Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.
2014-07-01
One of the main results of heavy ions collision at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound ?/s = 1/4? for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green- Kubo relations give us an exact expression to compute these coefficients. We computed shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigated different cases of particles, for one component system (gluon matter), interacting via isotropic or anisotropic cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. Another transport coefficient of interest is the electric conductivity ?el which determines the response of QGP to the electromagnetic fields present in the early stage of the collision. We study the ?el dependence on microscopic details of interaction and we find also in this case that Relaxation Time Approximation is a good approximation only for isotropic cross-section.
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.
Kinetic model of a decaying SF6 plasma over the temperature range 12000 K to 3000 K
A. Gleizes; F. Mbolidi; A. A. M. Habib
1993-01-01
A kinetic model is presented for decay of an SF6 arc plasma concerning the period when the electrons disappear (the so-called post-arc phase in SF6 circuit breaker operation). The model is based on solution of the rate equations of the 14 species chosen for the study (electrons, atomic ions, atoms, and diatomic molecules and ions). It is applied to a
V. V. Azharonok; I. I. Filatova; V. D. Shimanovich; L. N. Orlov
2001-01-01
Using methods of emission spectroscopy, we have determined the gas-kinetic temperature fields of planar high-frequency capacitive discharge plasma in N2\\/CO2\\/He gas mixtures depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture. It is shown that the dominant contribution to the neutral component heating in the center of the discharge chamber is made by the processes
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)
Andreev, Pavel A.
2015-06-01
We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.
NASA Astrophysics Data System (ADS)
Ivanov, V. V.; Klopovskii, K. S.; Lopaev, D. V.; Proshina, O. V.; Rakhimov, A. T.; Rakhimova, T. V.; Rulev, G. B.
2002-03-01
The kinetics of the production and loss of CF2 and CF radicals in a glow discharge in pure CF4 is investigated by the laser-induced fluorescence method. The effective rate constants for electron-impact dissociation of CF4 molecules along the pathways toward CF2 and CF radicals are determined within a wide range of the reduced electric field (80-250 Td). It is shown that, along with the direct electron-impact dissociation of CF4, the radicals are also produced via the dissociation of the CxFy polymer fluorocarbon particles that form in the plasma. A detailed analysis of the kinetics of the radical production and loss in a modulated discharge made it possible to evaluate the contribution of the electron-impact dissociation of CF4 to the production of radicals and, consequently, to determine the dissociation rate constants k_{CF_2 } and k CF. A comparison of the obtained k_{CF_2 } and k CF values with the results of calculations by the Monte Carlo method and the literature data on the cross sections for electron-impact dissociation of CF4 molecules enabled the normalization of these cross sections in the threshold region and the construction of the model cross sections for the electron-impact dissociation of CF4 into neutral products. The calculated cross sections allow a satisfactory description of the experimental results throughout the entire range of E/N under study. A significant scatter (up to 100%) in the experimental data on k_{CF_2 } and k CF at low values of E/N is related to the considerable contribution of the CxFy polymer molecules (and, probably, CxF{y/+} ions and fluorocarbon grains) to the production of CF2 and CF radicals both in the plasma volume and on the surface of a fluorocarbon film covering the discharge tube wall.
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.
Yeung, Man-Chung
to such a plasma as equilib- rium plasma. In this work, we focus on a reactor in which nonther- mal, nonequilibrium plasma is generated by high- voltage, short electric discharges. Such a reactor is commonly referred technologies and improve the existing plasma reactors. One of the major modeling challenges is to determine
NASA Technical Reports Server (NTRS)
Roth, J. R.
1977-01-01
The degree of toroidal symmetry of the plasma, the number of midplane electrode rings, the configuration of electrode rings, and the location of the diagnostic instruments with respect to the electrode rings used to generate the plasma are discussed. Impurities were deliberately introduced into the plasma, and the effects of the impurity fraction on ion kinetic temperature and electron number density were observed. It is concluded that, if necessary precautions are taken, the plasma communicates extremely well along the magnetic field lines and displays a high degree of symmetry from sector to sector for a wide range of electrode ring configurations and operating conditions. Finally, some characteristic data taken under nonoptimized conditions are presented, which include the highest electron number density and the longest particle containment time (1.9 msec) observed. Also, evidence from a paired comparison test is presented which shows that the electric field acting along the minor radius of the toroidal plasma improves the plasma density and the calculated containment time more than an order of magnitude if the electric field points inward, relative to the values observed when it points (and pushes ions) radially outward.
Bun, H; Monjanel-Mouterde, S; Noel, F; Durand, A; Cano, J P
1990-08-01
The authors monitored the plasma levels of clobazam (CLO) and its principal metabolite, N-desmethylclobazam (NCLO) during chronic treatment of more than 400 epileptic patients receiving different co-medications, such as phenytoin (PH), carbamazepine (CBZ), sodium valproate (VPA) and phenobarbital (PB). This study investigated the influence of age and antiepileptic drugs on plasma levels of CLO and NCLO. Plasma concentrations measured 3 hr after morning administration of CLO varied from 30 to 700 [formula; see text] for CLO, and from 160 to 7000 [formula; see text] for NCLO. Plasma levels of CLO were higher in patients aged 20-30 years. NCLO concentrations increased with age up to 20 years. Coadministered antiepileptic compounds significantly decreased maximal plasma levels of CLO. Moreover, PH and CBZ a significantly increased the plasma levels of NCLO. Results on the influence of CBZ on CLO kinetics were confirmed in a group of ten patients receiving PB and VPA and later PB, VPA and CBZ as CLO associated drugs. The influence of VPA on the pharmacokinetics parameters of CLO was also evaluated in a patient in the latter group. PMID:2255665
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.
Nonlinear kinetic modeling of stimulated Raman scattering in a non-uniform and non-stationary plasma
NASA Astrophysics Data System (ADS)
Benisti, Didier
2014-10-01
We provide a theoretical description of stimulated Raman scattering that allows for collisionless dissipation as described in (and, in particular, of the nonlinear reduction of the Landau damping rate), and that accounts for the nonlinear frequency shift of the plasma wave and for the growth of sidebands. Non-uniform and non-stationary effects are derived by making use of a variational principle. The central direction of propagation of the pump laser is calculated with the usual ray-tracing method. However, non-paraxial equations are used for the plasma and scattered waves in order to account for the self-focusing induced by the nonlinear frequency shift.
Iris Erlund; Esa Meririnne; Georg Alfthan; Antti Aro
The flavanones naringenin and hesperetin exhibit estrogenic, anticarcinogenic and antioxidative properties. Orange juice and grapefruit juice contain high amounts of these compounds, and therefore their intake from the diet can be relatively high. No data are available regarding plasma concentrations or plasma kinetics of flavanones. The objectives of this study were to develop methods allowing the analysis of naringenin and
California at Los Angles, University of
1999-01-01
-4075(99)97893-8 Time-dependent kinetics model for a helium discharge plasma J Abdallah Jr, N Palmer, W Gekelman, J a cathode discharge in helium have been recorded with a Langmuir probe in the UCLA large plasma device simplified models to study the role of metastable levels and excited states in the plasma kinetics
NASA Astrophysics Data System (ADS)
Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.
2010-12-01
Abstract 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 Galileo orbital mission and for planning flyby and orbital measurements for future missions. The simulations are based on recent models of the atmosphere of Europa [1,2,3]. 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 ions velocity distribution and the fluxes along the magnetic field [4]. Photoionization, electron-impact ionization and charge exchange are included in our model. The temperature of the background electrons and pickup electrons was also included into the generalized Ohm's law. The background plasma contains O++, S++ thermal ions and energetic ions [5]. The pickup ions were created from the atmosphere. The majority of O2 atmosphere is thermal with an extended non-thermal population [1]. The moon is modeled in this initial work as a weakly conducting body. The first results of 3D hybrid kinetic simulation of Europa's environment in absence and with the induced magnetic dipole moment were presented in [4]. In this report we discuss the results of the hybrid kinetic simulation of Europa's environment and plasma wake for various temperatures of the atmospheric atom and we provide a comparison with observation data (E4 pass, [5]) and MHD simulations.
NASA Astrophysics Data System (ADS)
Winkler, R. B.; Wilhelm, J.; Winkler, R.
In continuation of recent kinetic investigations of the main macroscopic quantities of the Ar-Hg plasma which include realistic electron kinetics at various Hg partial pressures, this paper deals with the study of the macroscopic plasma behaviour at varying discharge current and buffer gas pressure respectively in a wide range of practical interest. By simultaneously solving the particle balances for the various kinds of excited Hg atoms, the current balance as well as the electron Boltzmann equation for such a mixture plasma, the densities of the electrons and excited Hg atoms, the electron energy distribution function, the energy budget of the electrons and the ultraviolet resonance radiation outputs could be determined, analysed and in part compared with experimental data available in the literature. In particular, a good agreement between theoretical and experimental results for the densities of the excited Hg atoms as well as for both resonance radiation outputs was found for a wide range of both considered parameters.Translated AbstractKinetik des Ar-Hg-Plasmas von Leuchtstofflampen-Entladungen II. Ar-Partialdruck- und EntladungsstromvariationIn Weiterführung vorausgehender kinetischer Untersuchungen der wesentlichen makroskopischen Größen des Ar-Hg-Plasmas unter Berücksichtigung der realistischen Elektronenkinetik bei Variation des Hg-Partialdruckes behandelt die vorliegende Arbeit das makroskopische Plasmaverhalten bei Veränderung des Entladungsstromes bzw. des Puffergasdruckes in umfangreichen, praktisch interessierenden Bereichen. Mittels simultaner Lösung der Teilchenzahlbilanzen für die verschiedenen Arten von angeregten Hg-Atomen, der Strombilanz sowie der Elektronen-Boltzmann-Gleichung für ein solches Mischplasma konnten die Dichten der Elektronen und angeregten Hg-Atome, die Elektronenenergieverteilungsfunktion, der Energiehaushalt der Elektronen und die Ausbeuten an ultravioletter Strahlung bestimmt, analysiert und teilweise mit in der Literatur verfügbaren experimentellen Daten verglichen werden. Insbesondere wurde eine gute Übereinstimmung zwischen theoretischen und experimentellen Ergebnissen sowohl für die Dichten der angeregten Hg-Atome als auch für beide Resonanzstrahlungsausbeuten bei ausgedehnter Variation beider betrachteter Parameter gefunden.
NASA Astrophysics Data System (ADS)
Maneva, Y. G.; Araneda, J. A.; Poedts, S.
2014-12-01
We consider parametric instabilities of finite-amplitude large-scale Alfven waves in a low-beta collisionless multi-species plasma, consisting of fluid electrons, kinetic protons and a drifting population of minor ions. Complementary to many theoretical studies, relying on fluid or multi-fluid approach, in this work we present the solutions of the parametric instability dispersion relation, including kinetic effects in the parallel direction, along the ambient magnetic field. This provides us with the opportunity to predict the importance of some wave-particle interactions like Landau damping of the daughter ion-acoustic waves for the given pump wave and plasma conditions. We apply the dispersion relation to plasma parameters, typical for low-beta collisionless solar wind close to the Sun. We compare the analytical solutions to the linear stage of hybrid numerical simulations and discuss the application of the model to the problems of preferential heating and differential acceleration of minor ions in the solar corona and the fast solar wind. The results of this study provide tools for prediction and interpretation of the magnetic field and particles data as expected from the future Solar Orbiter and Solar Probe Plus missions.
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 ...
Plasma Parameters, Fluctuations and Kinetics in a Magnetic Field Line Reconnection Experiment
Norbert Craven Wild Jr.; N. C. Jr
1983-01-01
The processes associated with reconnecting magnetic field lines have been studied in a large experimental laboratory plasma. Detailed time- and space-resolved probe measurements of the plasma density, temperature, potential and electric and magnetic fields are discussed. Plasma currents are seen to modify the vacuum magnetic field topology. A flat neutral sheet develops along the separatrix where magnetic flux is transferred
Kinetic determination of plasma amine oxidase photometric test with aldehyde dehydrogenase
R. Vormbrock; R. Helger
1982-01-01
Of three different methods for the determination of plasma amine oxidase activity we found the method with coupled aldehyde dehydrogenase to show the least interferences and to give reliable results with unfractionated samples, e. g. human plasma. From our inhibitor studies we concluded that no flavine containing amine oxidase (MAO) could be detected in human plasma and that all detectable
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 ...
Mamedov, B. A. [Department of Physics, Faculty of Arts and Sciences, Gaziosmanpasa University, Tokat 60100 (Turkey)
2010-11-15
An efficient analytical calculation approach is presented for the Tsytovich-Angelis dust-dust collision functions consisting of the kinetic theory of dusty plasmas. This method is based on the use of binomial expansion theorem for the analytical representation of the dust-dust collision functions. The analytical calculation offers the advantage that leads to a mathematical expression, which allows the direct calculation of the dust-dust collision functions. The proposed algorithm is implemented numerically using a computer program, and its convergence properties are investigated.
On the magnetohydrodynamic description of a two-component plasma in the Kerr metric
Ramon Khanna
1998-01-01
The magnetohydrodynamic equations describing an inviscid, fully ionized plasma in the vicinity of a rotating black hole are derived from a two-component plasma theory within the framework of the 3+1 split of the Kerr metric. Of central interest is the generalized Ohm's law. In the limit of quasi-neutral plasma it contains no new terms as compared with special relativity. Gravitomagnetic
Kline, J L; Bertsche, W A; Kurnit, N A; Montgomery, D S; Johnson, R P; Niemann, C
2012-01-01
A nitrogen gas Raman cell system has been constructed to shift a 70 J 527 nm laser beam to 600 nm with 20 J of energy. The 600 nm probe and a 200J, 527 nm pump beam were optically mixed in a laser produced (gas jet) plasma. The beating of the two laser beams formed a ponderomotive force that can drive Kinetic Electrostatic Electron Nonlinear (KEEN) waves discovered in Vlasov-Poisson simulations by Afeyan et al [1,2]. KEEN waves were detected in these experiments where traditional plasma theory would declare there to be a spectral gap (ie no linear waves possible). The detection was done using Thomson scattering with probe wavelengths of both 351 nm and 263.5 nm.
Vranjes, J.; Poedts, S. [Centre for Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven (Belgium) and Leuven Mathematical Modeling and Computational Science Research Centre (LMCC), Celestijnenlaan 200B, 3001 Leuven (Belgium)
2010-08-15
A purely kinetic instability of the dust acoustic mode in inhomogeneous plasmas is discussed. In the presence of a magnetic field, electrons and ions may be magnetized while at the same time dust grains may remain unmagnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species. It is shown that this may be a powerful mechanism for the excitation of dust acoustic waves. The analysis presented in the work is also directly applicable to plasmas containing both positive and negative ions and electrons, provided that at least one of the two ion species is unmagnetized.
NASA Astrophysics Data System (ADS)
Vranjes, J.; Poedts, S.
2010-08-01
A purely kinetic instability of the dust acoustic mode in inhomogeneous plasmas is discussed. In the presence of a magnetic field, electrons and ions may be magnetized while at the same time dust grains may remain unmagnetized. Although the dynamics of the light species is strongly affected by the magnetic field, the dust acoustic mode may still propagate in practically any direction. The inhomogeneity implies a source of free energy for an instability that develops through the diamagnetic drift effects of the magnetized species. It is shown that this may be a powerful mechanism for the excitation of dust acoustic waves. The analysis presented in the work is also directly applicable to plasmas containing both positive and negative ions and electrons, provided that at least one of the two ion species is unmagnetized.
Adamovich, Igor V; Li, Ting; Lempert, Walter R
2015-08-13
This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N2 vibrational energy transfer, reactions of excited electronic species of N2, O2, N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N2 vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H2-air, CH4-air and C2H4-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C3H8-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C3H8-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H2-air, CH4-air and C2H4-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate 'conventional' chemistry mechanism. PMID:26170427
A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas
NASA Astrophysics Data System (ADS)
Li, J.; Huang, X. B.; Cai, H. C.; Yang, L. B.; Xie, W. P.; Duan, S. C.
2014-12-01
Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.
Plasma L-5-Oxoproline Carbon and Nitrogen Kinetics in Healthy Young Adults
Cornelia C. Metges; Yong-Ming Yu; Wei Cai; Xiao-Ming Lu; Sue Wong; Alfred M. Ajami; Vernon R. Young
L-5-oxoproline (OP), an intermediate of the g-glutamyl cycle of glutathione synthesis and degrada- tion, may serve as a probe for the state of glutathione kinetics. We explored the whole-body carbon and nitrogen kinetics of OP in five male healthy subjects (75.2 kg; 181 cm; 26 y) after a 5-d adaptation to an adequate L-amino acid-based diet (160 mg N z
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
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.
M. J. Sowa; M. E. Littau; V. Pohray; J. L. Cecchi
2000-01-01
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
Kinetics of layer growth during plasma nitriding of nickel based alloy Inconel 600
Y. Sun
2003-01-01
The response of nickel based superalloy, Inconel 600, to plasma nitriding has been investigated in the present work. Plasma nitriding experiments carried out at temperatures between 400 and 600°C for times between 1 h and 40 h revealed that the growth of the nitrided layer varied with temperature in a way significantly deviating from the conventional diffusion law. For similar
Positive and negative chlorine ion kinetics in inductively-coupled ClâBClâ plasmas
C. B. Fleddermann; G. A. Hebner
1997-01-01
Discharges in gas mixtures of Clâ, BClâ, Ar, and Nâ are used by the integrated circuit industry for metal etching, and are as yet not well understood, especially in inductively-coupled plasma (ICP) sources which are rapidly becoming the industry standard for etching tools. An essential parameter that must be measured in these plasmas is the density of ions, both positive
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.
Kinetics of Sodium Dodecyl Sulfate Solubilization of Mycoplasma laidlawii Plasma Membranes
Auborn, James J.; Eyring, Edward M.; Choules, G. Lew
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 activation energy remained the same in either case, about 10 kcal/mol. Static light-scattering studies at higher resolution showed that the solubilized membranes are in the form of small aggregates. PMID:5289357
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.
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 ...
Yu. G. Ignatyev; K. Alsmadi
2010-12-27
A complete model of baryon production in an expanding, primordially symmetric hot Universe is constructed in the framework of general-relativistic kinetic theory. In this model specific model for a baryon is calculated and graphs of the value dependence are constructed.
NASA Astrophysics Data System (ADS)
Ponomarjov, Maxim
2000-10-01
General methods are proposed for 3D time-dependent kinetic simulations of turbulent plasma flows under the effect of external magnetic field. The model Boltzmann equation solved taking into account the external magnetic fields and interactions with ambient particles. Using this solution in different specific cases the analytical and numerical results are obtained, which describe developing magnetic field aligned 3D stratifications and acceleration of mass and heat flows. For magnetic field aligned drifting velocity of the flows, formation of 3D flute structures along the edges of the flows is obtained. These new results developed significantly the previous research in this direction (Ponomarjov M.G. Physical Review E, 54, 5591-5598,1996; Planetary and Space Science, 43, 1409-1427, 1995)
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.
Devi, N.; Gogoi, R.; Das, G. C.; Roychoudhury, R. [Department of Mathematics, Cotton College, Guwahati-781001, Assam (India); Mathematical Sciences Division, Institute of Advanced Study in Science and Technology, Paschim Boragaon, Guwahati-781035, Assam (India); Physics and Applied Mathematical Unit, Indian Statistical Institute, Kolkata 700108 (India)
2007-01-15
A two fluid model has been employed to study the oblique propagation of solitary kinetic Alfven waves. Formation of solitary waves and double layers is observed. Amplitude, width (in the case of solitons), and thickness (in the case of double layers) of the nonlinear structures are studied in some detail. Wider solitary structures are found to exist for oblique propagation nearer to the magnetic field direction.
Kinetic processes in the plasma formed in combustion of hydrocarbon fuels
A. M. Starik; A. M. Savel’ev; N. S. Titova
2011-01-01
An analysis of the basic kinetic processes responsible for the formation of ions, electrons, charged and neutral carbon clusters\\u000a and particles of nanometer size in the combustion of hydrocarbon fuels has been made. It has been shown that the formation\\u000a of a polydisperse ensemble of positively and negatively charged particles is mainly caused by the ion adhesion to primary\\u000a particles
Problems and perspectives of state-to-state kinetics for high enthalpy plasma flows (Invited)
NASA Astrophysics Data System (ADS)
Colonna, Gianpiero
2014-12-01
The paper will present a brief overview of the applications of state-to-state kinetics in modeling fluid dynamics. The research activities ranges from hypersonic entry (boundary layer, shock wave) to ground test facilities, from MHD interaction to DBD flow control. The state-to-state model in fluid dynamics in the last years is rapidly diffusing, promising new interesting developments in the next future.
Passivation kinetics of two types of defects in polysilicon TFT by plasma hydrogenation
I-Wei Wu; Tiao-Yuan Huang; Warren B. Jackson; Alan G. Lewis; Anne Chiang
1991-01-01
The effects and kinetics of hydrogen passivation on polycrystalline-silicon thin-film transistors (poly-TFTs) are investigated. Based on the response of device parameters with the progress of hydrogenation, two types of defects can be distinguished from the difference in passivation rate. The threshold voltage and subthreshold slope, which are strongly influenced by the density of dangling bond midgap states, have a faster
Optimization of kinetic parameters for the degradation of plasmid DNA in rat plasma
NASA Astrophysics Data System (ADS)
Chaudhry, Q. A.
2014-12-01
Biotechnology is a rapidly growing area of research work in the field of pharmaceutical sciences. The study of pharmacokinetics of plasmid DNA (pDNA) is an important area of research work. It has been observed that the process of gene delivery faces many troubles on the transport of pDNA towards their target sites. The topoforms of pDNA has been termed as super coiled (S-C), open circular (O-C) and linear (L), the kinetic model of which will be presented in this paper. The kinetic model gives rise to system of ordinary differential equations (ODEs), the exact solution of which has been found. The kinetic parameters, which are responsible for the degradation of super coiled, and the formation of open circular and linear topoforms have a great significance not only in vitro but for modeling of further processes as well, therefore need to be addressed in great detail. For this purpose, global optimization techniques have been adopted, thus finding the optimal results for the said model. The results of the model, while using the optimal parameters, were compared against the measured data, which gives a nice agreement.
High-energy kinetic theory of a particle beam generated plasma
NASA Astrophysics Data System (ADS)
Peyraud, N.
1984-08-01
The equilibrium high-energy electron distribution in a particle-beam-generated plasma is calculated. The tail of the distribution, above the first excited state, is derived from a Boltzmann equation which contains inelastic collisional processes and a continuous source term. This equation is analytically solved by a Laplace-transformation method, and (in a numerical application for the case of an argon plasma created by a high-energy electron beam between 1 and 1000 keV), the branching ratios for energy deposition in ionization and excitation states are calculated. The results are compared with those of the laser group of Orsay (Bretagne et al., 1981).
A. Durov; M. Deminsky; M. Strelkova; B. V. Potapkin
2004-01-01
The description of dynamics of particles size distribution function (PDF) in processes of new phase formation is important task in various technologies. Moments method is one of modern approaches which meet demands of accuracy and moderate usage of computer resources. Modified moments method which permits one to describe correctly both particles growth (in results of nucleation, coagulation and surface reactions)
Kinetic theory of a spherical probe in a stationary collision-dominated isothermal plasma
A. D. Brailsford
1977-01-01
Constitutive equations for the charge carrier fluxes in a stationary collision-dominated isothermal plasma surrounding a spherical electrode are derived, from the Boltzmann equation, by a moment method using a two-stream Maxwellian distribution of the type introduced by Lees. In contrast to previous treatments, the constraint of uniform temperature is imposed and its importance emphasized. This condition, together with particle conservation,
Kinetics of electrons and molecules at plasma-beam discharge in molecular gases
V. I. Karas; V. V. Mukhin; A. M. Naboka; V. E. Novikov
1987-01-01
Effect of molecule distribution by oscillating levels on plasma-beam discharge characteristics in molecular gases has been considered. It is shown that under conditions of gas low temperature T<< T sub v and TE sub 1E << epsilon sub 0 the higher rate of a chemical reaction can be obtained under conditions of strong nonequilibricity, i.e., when the larger stage of
Kinetics and energetics of the dissociation of HâS mixed with COâ in thermal plasmas
B. V. Potapkin; M. I. Strelkova; A. A. Fridman
1992-01-01
The dissociation of hydrogen sulfide mixed with carbon dioxide in quasiequilibrium thermal plasmas is studied numerically. The major channels for the reaction HâS + COâ â products and the mechanisms that describe them are established. The rates of cooling of the dissociation products for which the major products (Hâ, CO) will be conserved are determined. The range of energy inputs
MULTICOMPARTMENT KINETIC MODEL FOR LEAD. PART 3. LEAD IN BLOOD PLASMA AND ERYTHROCYTES
Multicompartment models have been fitted to experimental data on plasma lead and blood lead concentrations of subjects studied by de Silva (1981, Brit. J. Industr. Med. 38, 209-217) and one subject studied by Manton and Malloy (1983, Brit. J. Industr. Med., 40, 51-57). Nonlinear ...
Products and bioenergy from the pyrolysis of rice straw via radio frequency plasma and its kinetics
Wen-Kai Tu; Je-Lung Shie; Ching-Yuan Chang; Chiung-Fen Chang; Cheng-Fang Lin; Sen-Yeu Yang; Jing T. Kuo; Dai-Gee Shaw; Yii-Der You; Duu-Jong Lee
2009-01-01
The radio frequency plasma pyrolysis technology, which can overcome the disadvantages of common pyrolysis methods such as less gas products while significant tar formation, was used for pyrolyzing the biomass waste of rice straw. The experiments were performed at various plateau temperatures of 740, 813, 843 and 880K with corresponding loading powers of 357, 482, 574 and 664W, respectively. The
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
The GHIBLI plasma wind tunnel: Description of the new CIRA-PWT facility
NASA Astrophysics Data System (ADS)
Purpura, Carlo; Filippis, Federico De; Graps, Egidio; Trifoni, Eduardo; Savino, Raffaele
2007-06-01
A new plasma wind tunnel is under construction at the Italian Aerospace Research Centre (CIRA) located at Capua. It is named GHIBLI and the plasma is generated by a segmented arc heater whose power is about 2 MW. Such a new facility will be able to perform test campaigns on models up to 80 mm in diameter, and may be used to develop researches in the aerospace field of the hypersonic plasma flows from the reentry technologies to the validation of CFD codes for the theoretical predictions of aerothermodynamic phenomena. Target of the present paper is the presentation of results obtained by means of CFD simulation by using the well-known FLUENT code, Such a code has been used to simulate the aerothermodynamic field inside the conical nozzle of the facility to obtain some analytical correlations (fits) between the main aerodynamic parameters at the nozzle exit, such as the Mach number, flow density, mass flow rate, etc. and the reservoir conditions inside the arc heater column, total pressure and total enthalpy. Such fits allow fast theoretical prediction of the facility operation parameters for given reservoir conditions.
Gyrocenter-gauge kinetic theory
H. Qin; W. M. Tang; W. W. Lee
2000-08-07
Gyrocenter-gauge kinetic theory is developed as an extension of the existing gyrokinetic theories. In essence, the formalism introduced here is a kinetic description of magnetized plasmas in the gyrocenter coordinates which is fully equivalent to the Vlasov-Maxwell system in the particle coordinates. In particular, provided the gyroradius is smaller than the scale-length of the magnetic field, it can treat high frequency range as well as the usual low frequency range normally associated with gyrokinetic approaches. A significant advantage of this formalism is that it enables the direct particle-in-cell simulations of compressional Alfven waves for MHD applications and of RF waves relevant to plasma heating in space and laboratory plasmas. The gyrocenter-gauge kinetic susceptibility for arbitrary wavelength and arbitrary frequency electromagnetic perturbations in a homogeneous magnetized plasma is shown to recover exactly the classical result obtained by integrating the Vlasov-Maxwell system in the particle coordinates. This demonstrates that all the waves supported by the Vlasov-Maxwell system can be studied using the gyrocenter-gauge kinetic model in the gyrocenter coordinates. This theoretical approach is so named to distinguish it from the existing gyrokinetic theory, which has been successfully developed and applied to many important low-frequency and long parallel wavelength problems, where the conventional meaning of gyrokinetic has been standardized. Besides the usual gyrokinetic distribution function, the gyrocenter-gauge kinetic theory emphasizes as well the gyrocenter-gauge distribution function, which sometimes contains all the physics of the problems being studied, and whose importance has not been realized previously. The gyrocenter-gauge distribution function enters Maxwell's equations through the pull-back transformation of the gyrocenter transformation, which depends on the perturbed fields. The efficacy of the gyrocenter-gauge kinetic approach is largely due to the fact that it directly decouples particle's gyromotion from its gyrocenter motion in the gyrocenter coordinates. As in the case of kinetic theories using guiding center coordinates, obtaining solutions for this kinetic system involves only following particles along their gyrocenter orbits. However, an added advantage here is that unlike the guiding center formalism, the gyrocenter coordinates used in this theory involves both the equilibrium and the perturbed components of the electromagnetic field. In terms of solving the kinetic system using particle simulation methods, the gyrocenter-gauge kinetic approach enables the reduction of computational complexity without the loss of important physical content.
Arbitrary amplitude double layers in warm dust kinetic Alfven wave plasmas
Gogoi, Runmoni; Devi, Nirupama [Department of Mathematics, Cotton College, Guwahati-781001, Assam (India)
2008-07-15
Large amplitude electrostatic structures associated with low-frequency dust kinetic Alfvenic waves are investigated under the pressure (temperature) gradient indicative of dust dynamics. The set of equations governing the dust dynamics, Boltzmann electrons, ions and Maxwell's equation have been reduced to a single equation known as the Sagdeev potential equation. Parameter ranges for the existence of arbitrary amplitude double layers are observed. Exact analytical expressions for the energy integral is obtained and computed numerically through which sub-Alfvenic arbitrary amplitude rarefactive double layers are found to exist.
Kinetic simulations of the self-focusing and dissipation of finite-width electron plasma waves.
Winjum, B J; Berger, R L; Chapman, T; Banks, J W; Brunner, S
2013-09-01
Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus ?m relative to the initial width ?0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability ?TPMI divided by the loss rate of field energy ?E to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing ?TPMI/?E?1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)]. PMID:25166675
A Variational Formulation of Macro-Particle Algorithms for Kinetic Plasma Simulations
NASA Astrophysics Data System (ADS)
Shadwick, B. A.
2013-10-01
Macro-particle based simulations methods are in widespread use in plasma physics; their computational efficiency and intuitive nature are largely responsible for their longevity. In the main, these algorithms are formulated by approximating the continuous equations of motion. For systems governed by a variational principle (such as collisionless plasmas), approximations of the equations of motion is known to introduce anomalous behavior, especially in system invariants. We present a variational formulation of particle algorithms for plasma simulation based on a reduction of the distribution function onto a finite collection of macro-particles. As in the usual Particle-In-Cell (PIC) formulation, these macro-particles have a definite momentum and are spatially extended. The primary advantage of this approach is the preservation of the link between symmetries and conservation laws. For example, nothing in the reduction introduces explicit time dependence to the system and, therefore, the continuous-time equations of motion exactly conserve energy; thus, these models are free of grid-heating. In addition, the variational formulation allows for constructing models of arbitrary spatial and temporal order. In contrast, the overall accuracy of the usual PIC algorithm is at most second due to the nature of the force interpolation between the gridded field quantities and the (continuous) particle position. Again in contrast to the usual PIC algorithm, here the macro-particle shape is arbitrary; the spatial extent is completely decoupled from both the grid-size and the ``smoothness'' of the shape; smoother particle shapes are not necessarily larger. For simplicity, we restrict our discussion to one-dimensional, non-relativistic, un-magnetized, electrostatic plasmas. We comment on the extension to the electromagnetic case. 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.
Kinetic Simulations of the Self-Focusing and Dissipation of Finite-Width Electron Plasma Waves
NASA Astrophysics Data System (ADS)
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)].
Blob Method for Kinetic Plasma Simulation with Variable-Size Particles
NASA Astrophysics Data System (ADS)
Coppa, G. G. M.; Lapenta, G.; Dellapiana, G.; Donato, F.; Riccardo, V.
1996-09-01
A new approach to particle in cell simulation is presented for collisionless plasmas. The new method is based on computational particles of variable size ( blobs). Each blob represents an element of phase space and its shape and size are evolved in time to represent better the correct evolution. The blob particles can be split to increase the accuracy in selected regions of stronger gradients. Blobs can also be coalesced to keep the total number of blobs constant. The performance of the blob method is analyzed in the case of the Landau damping and in the formation of a sheath in a bounded plasma. The results show the correctness and effectiveness of the new method. When compared to standard PIC methods, the blob technique reduces the noise for a given number of computational particles.
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.
The kinetic energy of carbon ions in vacuum arc plasmas: Acomparison of measuring techniques
Anders, Andre; Yushkov, George Yu.
2003-12-20
Ions in cathodic arc plasmas have high velocities attained by acceleration at cathode spots. Among other techniques, two time-of-flight setups had previously been used to determine ion velocities. These measurements showed significant discrepancies especially for some light cathode materials like carbon. To reconcile the differences, a thorough investigation was conducted using carbon as the cathode material. It is shown that systematic errors occur when the ion source time-of-flight system is not operated near perveance-matching conditions. The extracted ion beam is not parallel but divergent, and the Faraday cup detector measures only a fraction of the beam. In contrast, plasma source experiments without ion extraction are free of such distortions. In the absence of an external magnetic field, the average carbon ion energy has been determined to be in the range 18.5-20.5 eV for arc currents in the range 100-600 A, in agreement with previous plasma source measurements and other literature data.
NASA Technical Reports Server (NTRS)
Schindler, K.; Birn, J.; Hesse, M.
2012-01-01
Localized plasma structures, such as thin current sheets, generally are associated with localized magnetic and electric fields. In space plasmas localized electric fields not only play an important role for particle dynamics and acceleration but may also have significant consequences on larger scales, e.g., through magnetic reconnection. Also, it has been suggested that localized electric fields generated in the magnetosphere are directly connected with quasi-steady auroral arcs. In this context, we present a two-dimensional model based on Vlasov theory that provides the electric potential for a large class of given magnetic field profiles. The model uses an expansion for small deviation from gyrotropy and besides quasineutrality it assumes that electrons and ions have the same number of particles with their generalized gyrocenter on any given magnetic field line. Specializing to one dimension, a detailed discussion concentrates on the electric potential shapes (such as "U" or "S" shapes) associated with magnetic dips, bumps, and steps. Then, it is investigated how the model responds to quasi-steady evolution of the plasma. Finally, the model proves useful in the interpretation of the electric potentials taken from two existing particle simulations.
Microscopic Lagrangian description of warm plasmas. III - Nonlinear wave-particle interaction
NASA Technical Reports Server (NTRS)
Galloway, J. J.; Crawford, F. W.
1977-01-01
The averaged-Lagrangian method is applied to nonlinear wave-particle interactions in an infinite, homogeneous, magnetic-field-free plasma. The specific example of Langmuir waves is considered, and the combined effects of four-wave interactions and wave-particle interactions are treated. It is demonstrated how the latter lead to diffusion in velocity space, and the quasilinear diffusion equation is derived. The analysis is generalized to the random phase approximation. The paper concludes with a summary of the method as applied in Parts 1-3 of the paper.
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.
Description of the Fokker-Plank code used to model ECRH of the Constance 2 plasma
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 in this report. The ECRH is modeled by the bounce-averaged quasilinear theory derived by Mauel. 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 (ADI) technique as explained by Killeen and Marx. The program was written in LISP to be run in the MACSYMA environment of the MACSYMA Consortium's PDP-10 computer.
The Ulysses solar wind plasma investigation: Description and initial in-ecliptic results
Bame, S.J.; Phillips, J.L.; McComas, D.J.; Gosling, J.T. (Los Alamos National Lab., NM (United States)); Goldstein, B.E. (Jet Propulsion Lab., Pasadena, CA (United States))
1991-01-01
During the in-ecliptic flight of Ulysses from the Earth toward its encounter with Jupiter, the Los Alamos solar wind plasma experiment has performed well. Briefly described, the instrumentation contains two independent electrostatic analyzers, one for ions and one for electrons. Initial analysis of solar wind electron core temperatures obtained between 1.15 and 3.76 AU yields a gradient of T {proportional to} R{sup {minus}0.7} which is flatter than expected for adiabatic expansion of a single-temperature Maxwellian velocity distribution and steeper than that obtained from Mariner-Voyager.
Davidson, R.C. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.; Chen, C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Science and Fusion Center
1997-08-01
A kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field B{sup sol}({rvec x}) is developed. The analysis is carried out for a thin beam with characteristic beam radius r{sub b} {much_lt} S, and directed axial momentum {gamma}{sub b}m{beta}{sub b}c (in the z-direction) large compared with the transverse momentum and axial momentum spread of the beam particles. Making use of the nonlinear Vlasov-Maxwell equations for general distribution function f{sub b}({rvec x},{rvec p},t) and self-consistent electrostatic field consistent with the thin-beam approximation, the kinetic model is used to investigate detailed beam equilibrium properties for a variety of distribution functions. Examples are presented both for the case of a uniform solenoidal focusing field B{sub z}(z) = B{sub 0} = const. and for the case of a periodic solenoidal focusing field B{sub z}(z + S) = B{sub z}(z). The nonlinear Vlasov-Maxwell equations are simplified in the thin-beam approximation, and an alternative Hamiltonian formulation is developed that is particularly well-suited to intense beam propagation in periodic focusing systems. Based on the present analysis, the Vlasov-Maxwell description of intense nonneutral beam propagation through a periodic solenoidal focusing field {rvec B}{sup sol}({rvec x}) is found to be remarkably tractable and rich in physics content. The Vlasov-Maxwell formalism developed here can be extended in a straightforward manner to investigate detailed stability behavior for perturbations about specific choices of beam equilibria.
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.
Brief note about plasma catecholamines kinetics and submaximal exercise in untrained standardbreds.
Baragli, Paolo; Pacchini, Sara; Gatta, Domenico; Ducci, Michele; Sighieri, Claudio
2010-01-01
Four untrained standardbred horses performed a standardized exercise test on the treadmill and an automated blood collection system programmed to obtain blood samples every 15 s was used for blood collection in order to evaluate the kinetics of adrenaline and noradrenaline. The highest average values obtained for adrenaline and noradrenaline were 15.0 +/- 3.0 and 15.8 +/- 2.8 nmol/l respectively, with exponential accumulation of adrenaline (r = 0.977) and noradrenaline (r = 0.976) during the test. Analysis of the correlation between noradrenaline and adrenaline for each phase of the test shows that correlation coefficient decreases as the intensity of exercise increases (from r = 0.909 to r = 0.788). This suggests that during submaximal exercise, the process for release, distribution and clearance of adrenaline into blood circulation differs from that of noradrenaline. PMID:20348624
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.
Kinetic analysis of the energy transport of bursty bulk flows in the plasma sheet
NASA Astrophysics Data System (ADS)
Cao, Jinbin; Ma, Yuduan; Parks, George; Reme, Henri; Dandouras, Iannis; Zhang, Tielong
2013-01-01
The energy transport of bursty bulk flows (BBFs) is very important to the understanding of substorm energy transport. Previous studies all use the MHD bulk parameters to calculate the energy flux density of BBFs. In this paper, we use the kinetic approach, i.e., ion velocity distribution function, to study the energy transport of an earthward bursty bulk flow observed by Cluster C1 on 30 July 2002. The earthward energy flux density calculated using kinetic approach QKx is obviously larger than that calculated using MHD bulk parameters QMHDx. The mean ratio QKx/QMHDx in the flow velocity range 200-800 km/s is 2.7, implying that the previous energy transport of BBF estimated using MHD approach is much underestimated. The underestimation results from the deviation of ion velocity distribution from ideal Maxwellian distribution. The energy transport of BBF is mainly provided by ions above 10 keV although their number density Nf is much smaller than the total ion number density N. The ratio QKx/QMHDx is basically proportional to the ratio N/Nf. The flow velocity v(E) increases with increasing energy. The ratio Nf/N is perfectly proportional to flow velocity Vx. A double ion component model is proposed to explain the above results. The increase of energy transport capability of BBF is important to understanding substorm energy transport. It is inferred that for a typical substorm, the ratio of the energy transport of BBF to the substorm energy consumption may increase from the previously estimated 5% to 34% or more.
NASA Astrophysics Data System (ADS)
Tang, William
2013-04-01
Advanced computing is generally recognized to be an increasingly vital tool for accelerating progress in scientific research in the 21st Century. The imperative is to translate the combination of the rapid advances in super-computing power together with the emergence of effective new algorithms and computational methodologies to help enable corresponding increases in the physics fidelity and the performance of the scientific codes used to model complex physical systems. If properly validated against experimental measurements and verified with mathematical tests and computational benchmarks, these codes can provide more reliable predictive capability for the behavior of complex systems, including fusion energy relevant high temperature plasmas. The magnetic fusion energy research community has made excellent progress in developing advanced codes for which computer run-time and problem size scale very well with the number of processors on massively parallel supercomputers. A good example is the effective usage of the full power of modern leadership class computational platforms from the terascale to the petascale and beyond to produce nonlinear particle-in-cell simulations which have accelerated progress in understanding the nature of plasma turbulence in magnetically-confined high temperature plasmas. Illustrative results provide great encouragement for being able to include increasingly realistic dynamics in extreme-scale computing campaigns to enable predictive simulations with unprecedented physics fidelity. Some illustrative examples will be presented of the algorithmic progress from the magnetic fusion energy sciences area in dealing with low memory per core extreme scale computing challenges for the current top 3 supercomputers worldwide. These include advanced CPU systems (such as the IBM-Blue-Gene-Q system and the Fujitsu K Machine) as well as the GPU-CPU hybrid system (Titan).
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.
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.
Quantitative description of ion transport via plasma membrane of yeast and small cells
Volkov, Vadim
2012-01-01
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.
Kinetic Simulations of the Self-Focusing and Dissipation of Finite-Width Electron Plasma Waves
Winjum, B. J. [Univ. of California, Los Angeles, CA (United States); Berger, R. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chapman, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Banks, J. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brunner, S. [Federal Inst. of Technology, Lausanne (Switzerland)
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)].
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
Roy E S Bullingham; Henry J McQuay; Andrew Moore; Martin R D Bennett
1980-01-01
Buprenorphine kinetics was determined in surgical patients using radioimmunoassay. Buprenorphine was measured in the plasma of 24 patients who had received 0.3 mg buprenorphine intraoperatively. After 3 hr 10 of these patients then received a further 0.3 mg buprenorphine intravenously for postoperative pain relief, and 11 patients were given 0.3 mg intramuscularly: again, plasma levels were measured for 3 hr.
NASA Astrophysics Data System (ADS)
Runge, Keith; Deymier, Pierre
2013-03-01
Recent progress in orbital-free Density Functional Theory (OF-DFT), particularly with regard to temperature dependent functionals, has promise for the simulation of warm dense matter (WDM) systems. WDM includes systems with densities of an order of magnitude beyond ambient or more and temperatures measured in kilokelvin. A challenge for the development of temperature dependent OF-DFT functionals is the lack of benchmark information with temperature and pressure dependence on simple models under WDM conditions. We present an approach to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Electrons are described as harmonic necklaces within the discrete path integral representation while quantum exchange takes the form of cross linking between electron necklaces. A molecular dynamics algorithm is used to sample phase space and the fermion sign problem is addressed by restricting the density matrix to positive values. The temperature dependence of kinetic energies for the strongly coupled electron plasma is presented for a number of Wigner-Seitz radii in terms of a fourth order Sommerfeld expansion. Recent progress in orbital-free Density Functional Theory (OF-DFT), particularly with regard to temperature dependent functionals, has promise for the simulation of warm dense matter (WDM) systems. WDM includes systems with densities of an order of magnitude beyond ambient or more and temperatures measured in kilokelvin. A challenge for the development of temperature dependent OF-DFT functionals is the lack of benchmark information with temperature and pressure dependence on simple models under WDM conditions. We present an approach to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Electrons are described as harmonic necklaces within the discrete path integral representation while quantum exchange takes the form of cross linking between electron necklaces. A molecular dynamics algorithm is used to sample phase space and the fermion sign problem is addressed by restricting the density matrix to positive values. The temperature dependence of kinetic energies for the strongly coupled electron plasma is presented for a number of Wigner-Seitz radii in terms of a fourth order Sommerfeld expansion. Supported by US DoE Grant DE-SC0002139
NASA Astrophysics Data System (ADS)
Shuaibov, A. K.; Chygin, V. I.; Shimon, L. L.; Shevera, I. V.; Gorun, P. P.; Obukhovskii, R. O.
2010-05-01
The results of studying the radiation due to argon, krypton, and xenon monochloride bands, as well as to the bands of chlorine molecules, from the plasma of a transverse Ar-Kr-Xe-Cl2 volume discharge are reported. The working mixture of a pulse radiation source is optimized with regard to its pressure and elemental composition and parameters of an excitation system. By numerically solving the Boltzmann kinetic equation for the electron energy distribution function, the transport characteristics of plasma electrons and discharge power specific losses are found for different values of the reduced electric field strength. The plasma parameters are simulated for the quaternary mixture, which is most appropriate for a multiwave UV-VUV source. Qualitative analysis is conducted for the most important electron processes in the multicomponent plasma that govern the joint formation of argon, krypton, and xenon monochlorides in the transverse discharge.
Kinetic analysis of the ion temperature gradient modes in toroidally rotating plasmas
Zheng, L.; Tessarotto, M. [Department of Mathematical Sciences, University of Trieste, 34127 Trieste (Italy)] [Department of Mathematical Sciences, University of Trieste, 34127 Trieste (Italy)
1996-12-01
With the two time scale feature revealed, an analytical method is developed to solve the combined eigenvalue and initial value problem describing the ion temperature gradient (ITG) modes in the toroidally rotating plasmas. With full gyrokinetics and toroidal geometry effects being taken into account in an ordering consistent manner, dispersion relations are obtained for ITG modes both of toroidal and slab-like branches. The results show that the sonic rotation can be harmful for the stability, while subsonic rotation with flow shear can be expected to be stabilizing. The existence of the flow shear leads the time evolution of the fluctuation signals to display two different time scales{emdash}a fast oscillating (either fast or slow growing) signal with its amplitude modulated by a slowly varying envelope, resembling fishbone-like fluctuations. {copyright} {ital 1996 American Institute of Physics.}
NASA Astrophysics Data System (ADS)
Rekaa, Vegard L.; Chapman, Sandra C.; Dendy, Richard O.
2014-05-01
Supernova remnant and heliopause termination shock plasmas may contain significant populations of minority heavy ions such as alpha-particles, with relative number densities n?/ni up to 50%. Fully self-consistent kinetic simulations of quasi-perpendicular, supercritical shocks can show non-steady, reforming solutions with consequences for ion acceleration local to the shock. We present the first set of particle-in-cell simulations that span the entire range of values of n?/ni from zero to one, where the two ion species and electrons are all treated fully self-consistently. These '1.5D' simulations evolve the full three dimensional particle trajectories and electromagnetic vector fields as a function of one space co-ordinate and time. The simulated supercritical (Mach number ~ 8) shocks have perpendicular geometry, plasma ? = 0.15, upstream magnetic field B1 = 10-7T and particle density n ? 107m-3. Crucial to the time evolving phenomenology of the shocks and particles at different n?/ni are the interplay between the differing characteristic gyroscales of the two ion species. Ions can gain energy both directly by acceleration in the electromagnetic foot-ramp region of the shock, and in the strongly fluctuating fields downstream. The downstream field fluctuations are driven by the free energy that both ion species gain in their initial interaction with the shock. The details of all these processes, and their efficiency for energization, are found to depend on n?/ni. Disclaimer: This work was partly funded by the UK Engineering and Physics Sciences Research Council under grant EP/G003955 and by The European Communities under the contract of association between Euratom and CCFE. The views and opinions expressed herein do not necessarily represent those of the European Communities.
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.
Radu Balescu and the search for an stochastic description of turbulent transport in plasmas
Sanchez, Raul [ORNL; Carreras, Benjamin A [ORNL; van Milligen, B. Ph. [Asociacion EURATOM-CIEMAT
2007-01-01
An idea that the late Prof. Radu Balescu often pondered during his long and distinguished scientific career was the possibility of constructing simple stochastic or probabilistic models able to capture the basic features of the complex dynamics of turbulent transport in magnetically confined plasmas. In particular, the application of the continuous-time random walk (CTRW) concept to this task was one of his favorites. In the last few years prior to his death, we also became interested in applying (variations of the standard) CTRW to these problems. In our case, it was the natural way to move beyond the simple paradigms based on sandpile constructs that we had been previously studying. This common interest fueled an intense electronic correspondence between Prof. Balescu and us that started in 2004 and was only interrupted by his unexpected death in June 2006. In this paper, we pay tribute to his memory by reviewing some of these exciting concepts that interested him so much and by sketching the problems and ideas that we discussed so frequently during these two years. Regretfully, he will no longer be here to help us solve them.
NASA Astrophysics Data System (ADS)
Hosseini Jenab, S. M.; Kourakis, I.
2014-04-01
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 (?trap) and their amplitude, on the electron-to-ion temperature ratio and on the dust concentration. In electron-ion plasma, an exponential relation between ?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 ?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.
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.
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.
NASA Astrophysics Data System (ADS)
Ahmed, M. K.; Sah, O. P.
2014-09-01
Taking into account of ion temperature effect, existence conditions of arbitrary amplitude solitary Kinetic Alfvén Waves (KAWs) in a plasma with q-nonextensive electrons are investigated by the conventional Sagdeev pseudo potential method. It is found that only solitons with density hump can exist, the amplitude of which depends sensitively on the parameter q, ion temperature () and plasma ?. There is an upper limit of solitary wave amplitude which decreases with increase of q, ? and ?. The amplitude of solitary KAWs is found to increase with increase in ion temperature. The results obtained in the framework of Maxwellian distribution are reproduced when q?1.
J. R. Wygant; A. Keiling; C. A. Cattell; R. L. Lysak; M. Temerin; F. S. Mozer; C. A. Kletzing; J. D. Scudder; V. Streltsov; W. Lotko
2002-01-01
We present evidence based on measurements from the Polar spacecraft for the existence of small-scale, large-amplitude kinetic Alfvén waves\\/spikes at the plasma sheet boundary layer (PSBL) at altitudes of 4-6 RE. These structures coincide with larger-scale Alfvénic waves that carry a large net Poynting flux along magnetic field lines toward the Earth. Both structures are typically observed in the PSBL
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
Al Ayoubi, S.; Amouroux, J. [ENSCP, Paris (France). Laboratoire de Genie des Procedes Plasmas; Renou-Gonnord, M.F. [Ecole Polytechnique, Palaiseau (France). Laboratoire des Mecanismes Reactionnels
1995-12-31
The design of a plasma process for removing organic and hazardous substances has to account for pollutant emission by effluent gases. In order to evaluate the feasibility of using a plasma spouted-bed reactor for waste destruction, an efficient analytical procedure has been developed. CF{sub 4} has been chosen as a model molecule in both experimental work and in kinetic calculations.
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.
The relativistic kinetic Weibel instability: General arguments and specific illustrations
Schaefer-Rolffs, U.; Lerche, I.; Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr Universitaet Bochum, D-44780 Bochum (Germany)
2006-01-15
A general description is developed of the kinetic Weibel [Phys. Rev. Lett. 2, 83 (1959)] instability in relativistic plasmas for arbitrary plasma distribution functions. Then general conditions for the existence of the relativistic instability are given as well as the influence of limits on the wave-number range and so on the instability rate. A comparison with previous works on bi-Gaussian distributions is also provided. Furthermore, ultrarelativistic and also weakly anisotropic relativistic distributions are investigated in general. Finally, isolated Weibel modes (in which both the frequency and wave number are fixed) are derived for asymmetric relativistic plasma distributions and constraints on these isolated modes are presented.
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.
Steven J. Christopher; R. Yuancai Ye; Kenneth Marcus
1997-01-01
Studies are performed to evaluate the effect of discharge power, pressure, and sampling position on the kinetic energy of ions sampled from a radio frequency glow discharge (rf-GD) source. The average kinetic energy of ions decreases with increases in discharge power (20–40 W) and pressure (130–300 mTorr), with typical values lying in the range of 10–14 eV. Average ion kinetic
Yin Yunpeng; Sawin, Herbert H. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2007-07-15
The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ion scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.
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.
Quark-gluon transport theory II. Color response and color correlations in a quark-gluon plasma
Ulrich Heinz
1986-01-01
Starting from a classical kinetic description of the quark-gluon plasma, we derive in the linear response approximation the color response function near thermodynamic equilibrium. From its poles the dispersion relations for the collective color modes (one longitudinal and one transverse) are obtained. The absence of Landau damping in the quark-gluon plasma is shown, and other damping mechanisms are discussed. A
A. Hadjadj; G. Djellouli; O. Jbara
2010-01-01
We performed H2 plasma treatment of hydrogenated amorphous silicon (a-Si:H) thin films and followed by in situ spectroscopic ellipsometry measurements the kinetics of hydrogen-induced film modifications at temperatures varying from 100 to 250 °C. The time-dependence of the H-modified layer thickness dH(t) follows an exponential relation of the form dH0[1-exp(-t\\/tau)]. The temperature-dependence of dH0 and tau shows a discontinuity at
Brans, Y.W.; Schwartz, C.A.; Hood, R.J.; Ksebati, M.B.; Konduri, G.G. (Wayne State Univ., Detroit, MI (USA))
1990-10-01
We demonstrate the feasibility of quantifying the abundance of {sup 2}H in plasma by nuclear magnetic resonance (NMR) spectroscopy. After adding internal standard (tert-butyl-d9 alcohol) to deproteinized plasma samples containing {sup 2}H{sub 2}O, we determined the ratio of NMR peak areas for {sup 2}H{sub 2}O and tert-butyl-d9 alcohol. This peak-area ratio was directly proportional to the exogenous {sup 2}H enrichment of plasma (difference between measured and naturally occurring {sup 2}H) between 0 and 0.272 atom % (r = 0.999). The coefficient of variation was 1.34% at an exogenous enrichment of 0.136 atom %. We applied this method to a study of the dilution kinetics of {sup 2}H{sub 2}O to determine the optimal time and method of blood sampling for estimation of total body water content. The {sup 2}H enrichment of plasma stabilized by 4 h after intravenous injection of {sup 2}H{sub 2}O, 1 g/kg of body weight, and fluctuated within 2-4% of the 4- to 8-h mean thereafter.
Coupled electron and ion nonlinear oscillations in a collisionless plasma
Karimov, A. R. [Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, Moscow 127412, Russia and Department of Electrophysical Facilities, National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow 115409 (Russian Federation)] [Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, Moscow 127412, Russia and Department of Electrophysical Facilities, National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow 115409 (Russian Federation)
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.
Coupled electron and ion nonlinear oscillations in a collisionless plasma
NASA Astrophysics Data System (ADS)
Karimov, A. R.
2013-05-01
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.
Klaus Kappen; Uwe H. Bauder
2001-01-01
The energy transport by radiation is one of the most important effects in an electrothermal-chemical (ETC) accelerator. At the beginning of the ETC round, after the initiation of the plasma e.g. by an exploding wire, the plasma radiation is responsible for the ignition of the propellant and the observed enhancement of mass production. This could be validated by different closed
Blaschke, D. B. [Institute for Theoretical Physics, University of Wroclaw, 50-204 Wroclaw (Poland); Bogoliubov Laboratory for Theoretical Physics, Joint Institute for Nuclear Research, RU - 141980 Dubna (Russian Federation); Dmitriev, V. V.; Smolyansky, S. A. [Department of Physics, Saratov State University, RU - 410026 Saratov (Russian Federation); Roepke, G. [Institut fuer Physik, University of Rostock, D - 18051 Rostock (Germany)
2011-10-15
In the present work a closed system of kinetic equations is obtained from the truncation of the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy for the description of the vacuum creation of an electron-positron plasma and secondary photons due to a strong laser field. This truncation is performed in the Markovian approximation for the one-photon annihilation channel which is accessible due to the presence of the strong external field. Estimates of the photon production rate are obtained for different domains of laser field parameters (frequency {nu} and field strength E). A huge quantity of optical photons of the quasiclassical laser field is necessary to satisfy the conservation laws of the energy and momentum of the constituents (e{sup -}, e{sup +} and {gamma}) in this channel. Since the number of these optical photons corresponds to the order of perturbation theory, a vanishingly small photon production rate results for the optical region and strongly subcritical fields E<
Dandy, David
1 Treatment of methyl t-butyl ether contaminated water using a dense medium plasma reactor-7369 Email: david.dandy@colostate.edu Abstract Plasma treatment of contaminated water appears reactor configurations and two pin array spin rates. The oxidation products from the treatment of MTBE
On Hamiltonian and Action Principle Formulations of Plasma Dynamics
Morrison, P. J. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712 (United States)
2009-11-10
A general discussion of Hamiltonian and action principle formulations for fluid and plasma models is given. A procedure, based on Hamilton's principle of mechanics but adapted for continua, for the construction of action principles for fluid and kinetic models is given. The transformation from action principles in terms of the Lagrangian variable description to the Eulerian variable description in terms of noncanonical Poisson brackets is described. Two examples are developed: ideal MHD and Braginskii's fluid model with gyroviscosity.
Studies of plasma reactions in a moderate power microwave-induced plasma
Viscomi, A.S.
1989-01-01
Although plasmas have been used as analytical tools for almost 20 years, there has not been a definitive description of the reactions and their mechanisms that make plasmas useful excitation, ionization and emission sources for atomic spectrometry. Previous investigators have used the assumption of Local Thermodynamic Equilibrium (LTE) to describe plasma behavior. It has been shown that LTE criteria are generally not met in analytical plasmas. Recent discussions of plasma reactions attempt to take into account all the plasma reactions and the kinetics of these reactions. Not all of these rates are directly measurable. The author has used the reaction of probe analytes with the plasma in an attempt to determine the reaction mechanism in a moderate power helium microwave induced plasma (He-MIP). This dissertation reports the investigation of these modes of reaction, provides a critical review of current plasma reaction models, and gives a possible kinetic explanation of the observed behavior. Included in this study are plasma diagnostic measurements, analyte concentration effects, comparison studies of various analyte species, and theoretical calculations. Analytical figures of merit are presented, including detection limits and linear ranges. Finally, proposals for future mechanism research are outlined, with the goal of furthering research into high-energy plasma reactions.
NASA Astrophysics Data System (ADS)
Yin, L.; Albright, B. J.; Bowers, K. J.; Daughton, W.; Rose, H. A.
2008-01-01
Backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser are examined in the kinetic regime using particle-in-cell simulations. The SRS reflectivity measured as a function of the laser intensity in a single hot spot from two-dimensional (2D) simulations shows a sharp onset at a threshold laser intensity and a saturated level at higher intensities, as obtained previously in Trident experiments [D. S. Montgomery et al., Phys. Plasmas 9, 2311 (2002)]. In these simulations, wavefront bowing of electron plasma waves (ion acoustic waves) due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) [H. A. Rose, Phys. Plasmas 12, 12318 (2005)] is shown to occur in both two- and three-dimensional SRS simulations. The key physics underlying nonlinear saturation of SRS is identified as a combination of wavefront bowing, TPMI, and self-focusing of electron plasma waves. The wavefront bowing marks the beginning of SRS saturation and self-focusing alone is sufficient to terminate the SRS reflectivity, both effects resulting from cancellation of the source term for SRS and from greatly increased dissipation rate of the electron plasm waves. Ion acoustic wave bowing also contributes to the SBS saturation. Velocity diffusion by transverse modes and rapid loss of hot electrons in regions of small transverse extent formed from self-focusing lead to dissipation of the wave energy and an increase in the Landau damping rate in spite of strong electron trapping that reduces Landau damping initially. The ranges of wavelength and growth rate associated with transverse breakup of the electron-plasma wave are also examined in 2D speckle simulations as well as in 2D periodic systems from Bernstein-Greene-Kruskal equilibrium and are compared with theory predictions.
Yin, L.; Albright, B. J.; Bowers, K. J.; Daughton, W.; Rose, H. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2008-01-15
Backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser are examined in the kinetic regime using particle-in-cell simulations. The SRS reflectivity measured as a function of the laser intensity in a single hot spot from two-dimensional (2D) simulations shows a sharp onset at a threshold laser intensity and a saturated level at higher intensities, as obtained previously in Trident experiments [D. S. Montgomery et al., Phys. Plasmas 9, 2311 (2002)]. In these simulations, wavefront bowing of electron plasma waves (ion acoustic waves) due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) [H. A. Rose, Phys. Plasmas 12, 12318 (2005)] is shown to occur in both two- and three-dimensional SRS simulations. The key physics underlying nonlinear saturation of SRS is identified as a combination of wavefront bowing, TPMI, and self-focusing of electron plasma waves. The wavefront bowing marks the beginning of SRS saturation and self-focusing alone is sufficient to terminate the SRS reflectivity, both effects resulting from cancellation of the source term for SRS and from greatly increased dissipation rate of the electron plasm waves. Ion acoustic wave bowing also contributes to the SBS saturation. Velocity diffusion by transverse modes and rapid loss of hot electrons in regions of small transverse extent formed from self-focusing lead to dissipation of the wave energy and an increase in the Landau damping rate in spite of strong electron trapping that reduces Landau damping initially. The ranges of wavelength and growth rate associated with transverse breakup of the electron-plasma wave are also examined in 2D speckle simulations as well as in 2D periodic systems from Bernstein-Greene-Kruskal equilibrium and are compared with theory predictions.
S. N. Gordienko; L. D. Landau
1999-01-01
It is shown that because of the non-Markovian character of momentum transfer the scattering of a test particle in plasma cannot\\u000a always be described by a diffusion process. The braking of a particle by plasma occurs in three different stages: short and\\u000a long times, when scattering is nondiffusive, and intermediate times, when scattering can be described by a diffusion process.
Kosareva, I.N.; Aleksandrova, N.L.; Kindyshevaa, S.V.; Starikovskaia, S.M.; Starikovskii, A.Yu. [Moscow Institute of Physics and Technology, Institutskii Lane 9, Dolgoprudny, Moscow Region, 141700 (Russian Federation)
2009-01-15
The kinetics of ignition in C{sub n}H{sub 2n+2}:O{sub 2}:Ar mixtures for n=2 to 5 has been studied experimentally and numerically after a high-voltage nanosecond discharge. The ignition delay time behind a reflected shock wave was measured with and without the discharge. It was shown that the initiation of the discharge with a specific deposited energy of 10-30 mJ/cm{sup 3} leads to an order of magnitude decrease in the ignition delay time. Discharge processes and following chain chemical reactions with energy release were simulated. The generation of atoms, radicals and excited and charged particles was numerically simulated using the measured time-resolved discharge current and electric field in the discharge phase. The calculated densities of the active particles were used as input data to simulate plasma-assisted ignition. The sensitivity of the results to variation in electron cross sections, reaction rates and radical composition was investigated. Good agreement was obtained between the calculated ignition delay times and the experimental data. The analysis of the simulation results showed that the effect of nonequilibrium plasma on the ignition delay is associated with faster development of chain reactions, due to atoms and radicals produced by the electron impact dissociation of molecules in the discharge phase. Finally, we studied the role of various hydrocarbon radicals in the plasma-assisted ignition of the mixtures under consideration. (author)
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)].
A Kinetic Theory of Coupled Oscillators
Eric J. Hildebrand; Michael A. Buice; Carson C. Chow
2006-12-12
We present an approach for the description of fluctuations that are due to finite system size induced correlations in the Kuramoto model of coupled oscillators. We construct a hierarchy for the moments of the density of oscillators that is analogous to the BBGKY hierarchy in the kinetic theory of plasmas and gases. To calculate the lowest order system size effect, we truncate this hierarchy at second order and solve the resulting closed equations for the two-oscillator correlation function around the incoherent state. We use this correlation function to compute the fluctuations of the order parameter, including the effect of transients, and compare this computation with numerical simulations.
Claudio Cremaschini; Massimo Tessarotto
2012-01-09
A notorious difficulty in the covariant dynamics of classical charged particles subject to non-local electromagnetic (EM) interactions arising in the EM radiation-reaction (RR) phenomena is due to the definition of the related non-local Lagrangian and Hamiltonian systems. The lack of a standard Lagrangian/Hamiltonian formulation in the customary asymptotic approximation for the RR equation may inhibit the construction of consistent kinetic and fluid theories. In this paper the issue is investigated in the framework of Special Relativity. It is shown that, for finite-size spherically-symmetric classical charged particles, non-perturbative Lagrangian and Hamiltonian formulations in standard form can be obtained, which describe particle dynamics in the presence of the exact EM RR self-force. As a remarkable consequence, based on axiomatic formulation of classical statistical mechanics, the covariant kinetic theory for systems of charged particles subject to the EM RR self-force is formulated in Hamiltonian form. A fundamental feature is that the non-local effects enter the kinetic equation only through the retarded particle 4-position, which permits the construction of the related non-local fluid equations. In particular, the moment equations obtained in this way do not contain higher-order moments, allowing as a consequence the adoption of standard closure conditions. A remarkable aspect of the theory concerns the short delay-time asymptotic expansions. Here it is shown that two possible expansions are permitted. Both can be implemented for the single-particle dynamics as well as for the corresponding kinetic and fluid treatments. In the last case, they are performed a posteriori on the relevant moment equations obtained after integration of the kinetic equation over the velocity space. Comparisons with literature are pointed out.
NASA Technical Reports Server (NTRS)
Shawhan, S. D.
1982-01-01
The objectives, equipment, and techniques for the plasma diagnostics package (PDP) carried by the OSS-1 instrument payload of the STS-4 and scheduled for the Spacelab-2 mission are described. The goals of the first flight were to examine the Orbiter-magnetoplasma interactions by measuring the electric and magnetic field strengths, the ionized particle wakes, and the generated waves. The RMS was employed to lift the unit out of the bay in order to allow characterization of the fields, EM interference, and plasma contamination within 15 m of the Orbiter. The PDP will also be used to examine plasma depletion, chemical reaction rates, waves, and energized plasma produced by firing of the Orbiter thrusters. Operation of the PDP was carried out in the NASA Space Environment Simulation Laboratory test chamber, where the PDP was used to assay the fields, fluxes, wave amplitudes, and particle energy spectra. The PDP instrumentation is also capable of detecting thermal ions, thermal electrons suprathermal particles, VHF/UHF EMI levels, and the S-band field strength.
Shuaibov, A. K.; Grabovaya, I. A.; Minya, A. I.; Homoki, Z. T. [Uzhgorod National University (Ukraine); Kalyuzhnaya, A. G.; Shchedrin, A. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)
2011-03-15
A kinetic model of the processes occurring in the plasma of a high-power low-pressure gas-discharge lamp is presented, and the output characteristics of the lamp are described. The lamp is excited by a longitudinal glow discharge and emits the I{sub 2}(D Prime -A Prime ) 342-nm and XeI(B-X) 253-nm bands and the 206.2-nm spectral line of atomic iodine. When the emitter operates in a sealed-off mode on the p(He): p(Xe): p(I{sub 2}) = 400: 120: (100-200) Pa mixture, the fractions of the UV radiation power of iodine atoms, exciplex molecules of xenon iodide, and iodine molecules comprise 55, 10, and 35%, respectively. At the optimal partial pressure, the maximum total radiation power of the lamp reaches 37 W, the energy efficiency being about 15%.
NASA Astrophysics Data System (ADS)
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.
Ruobing Zhang; Chi Zhang; XingXin Cheng; Liming Wang; Yan Wu; Zhicheng Guan
2007-01-01
Removal of amaranth, a commercial synthetic azo dye widely used in the dye and food industry, was examined as a possible remediation technology for treating dye-contaminated water. Effects of various parameters such as gas flow rate, solution conductivity, pulse repetition frequency, etc., on decolorization kinetics were investigated. Experimental results show that an aqueous solution of 24mg\\/l dye is 81.24% decolorized
V. A. Sorokin; Yu. P. Tarasenko; S. V. Patrikeev; L. A. Orlovskii
1994-01-01
Aluminum powder and AlâOâ-Al, AlâOâ-SiOâ-Al, Ni-Al composites are studied within the range 20-1000Â°C by means of derivatography. Temperature ranges are determined for the reaction of components, interaction with each other and with the reaction medium, as well the dehydration of AlâOâ and NiO. The kinetics of these processes are explained and their thermal effect is described. X-ray methods show that
Carey, I; Bruce, M; Horner, M; Zen, Y; D'Antiga, L; Bansal, S; Vergani, D; Mieli-Vergani, G
2015-04-01
We aimed to investigate the ability of HBsAg plasma level kinetics to predict therapy response by studying 23 children with infancy-acquired chronic hepatitis B (CHB) during combination sequential therapy with lead-in lamivudine (LAM) and add-on interferon-? (IFN-?) [5 responders (R = anti-HBs seroconversion) and 18 nonresponders (NR)] and to assess their relationship with pretreatment intrahepatic HBV-DNA and cccDNA and HBsAg and HBcAg liver expression. Plasma HBsAg levels were measured in samples before (treatment week 0 = TW0), during (TW9, TW28, TW52) and after (follow-up week = FUW24) therapy by Abbott ARCHITECT(®) assay [log10 IU/mL]. Baseline liver HBV-DNA and cccDNA were quantified by real-time TaqMan PCR [log10 copies/ng genomic DNA]. HBsAg and HBcAg liver expression was evaluated by immunostaining of formalin-fixed, paraffin-embedded specimens [number of positive cells/1000 hepatocytes]. All results are presented as medians. Plasma: at baseline, on-treatment and during follow-up, HBsAg levels were lower in R than NR (TW0: 4.36 vs 4.75;TW28: 2.44 vs 4.35;TW52: 0 vs 4.08 and FUW24: 0.17 vs 4.35, all P < 0.05). Liver: baseline HBV-DNA (3.82 vs 4.71, P = 0.16) and cccDNA (1.98 vs 2.26, P = 0.18) tended to be lower in R than NR, HBsAg expression was lower in R than NR (0.5 vs 4.7, P = 0.03), and HBcAg expression was similar between R and NR. There were positive correlations between plasma HBsAg levels and liver HBV-DNA (r = 0.44, P = 0.04), cccDNA (r = 0.41, P = 0.04) and HBsAg liver expression (r = 0.38, P = 0.05). Lower baseline HBsAg plasma levels, lower HBsAg expression in liver and on-treatment decline of plasma HBsAg levels heralds HBsAg clearance and response to treatment in tolerant children with CHB. PMID:25278170
NASA Astrophysics Data System (ADS)
Sun, Yu; Kulkarni, Kaustubh; Sachdev, Anil K.; Lavernia, Enrique J.
2014-06-01
The current study shows the dramatic effect of an electric field (EF) and use of nanosized cryomilled grains on accelerating sintering kinetics during spark plasma sintering of blended elemental powder compacts of Ti53Al47 targeted to produce ?-TiAl intermetallic compounds. The EF had the dominating effect since it reduced the activation barrier for diffusion through Al3Ti leading to faster growth of Al3Ti; the precursor to ?-TiAl. The Avrami exponent ( n) determined for the micrograin compact lies between 1.0 and 1.5, which indicates that reaction sintering is controlled by bulk diffusion in these compacts, while for cryomilled compacts this is between 0.7 and 1.0 suggesting the important role of dislocations and grain boundaries on the transformation during reaction sintering. The activation energies were found to be in increasing order as: cryomilled compacts with EF (182 kJ/mol); micrograin compacts with EF (290 kJ/mol); cryomilled compacts without EF (331 kJ/mol); and micrograin compacts without EF (379 kJ/mol). The cryomilled microstructure also enhanced the sintering kinetics because of the availability of faster diffusing paths in Al and Ti including larger grain boundary area and dislocation density.
Yamada, N; Shames, D M; Havel, R J
1987-01-01
The kinetics of apolipoprotein (apo) B-100 in particles containing apo E (B,E particles) or lacking apo E (B particles) were studied in Watanabe heritable hyperlipidemic (WHHL) rabbits deficient in low density lipoprotein (LDL) receptors, and compared with those of normal rabbits after injection of radioiodinated very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), and LDL. In both groups results of kinetic modeling were consistent with the hypothesis that all apo B enters the plasma in VLDL, mainly as B,E particles, followed by delipidation and partial conversion to IDL and LDL, with concomitant conversion of some B,E particles to B particles. In WHHL rabbits, production of VLDL apo B was reduced by 40%, but LDL production was increased threefold. Defective removal of B,E and B particles in all three lipoprotein classes, coupled with preserved processes of delipidation, can account for the observed increases in the concentration of apo B (threefold in VLDL, fivefold in IDL, and twenty-twofold in LDL) in WHHL rabbits. PMID:3611356
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...
NASA Astrophysics Data System (ADS)
Zhang, H. Y.; Jin, C. G.; Yang, Y.; Ye, C.; Zhuge, L. J.; Wu, X. M.
2014-12-01
As-deposited HfO2 films were modified by CHF3, C4F8, and mixed C4F8/O2 plasmas in a dual-frequency capacitively coupled plasma chamber driven by radio frequency generators of 60 MHz as the high frequency (HF) source and 2 MHz as the low frequency source (60/2 MHz). The influences of various surface plasma treatments under CHF3, C4F8, and C4F8/O2 were investigated in order to understand the chemical and structural changes in thin-film systems, as well as their influence on the electrical properties. Fluorine atoms were incorporated into the HfO2 films by either CHF3 or C4F8 plasma treatment; meanwhile, the C/F films were formed on the surface of the HfO2 films. The formation of C/F layers decreased the k value of the gate stacks because of its low dielectric constant. However, the addition of O2 gas in the discharge gases suppressed the formation of C/F layers. After thermal annealing, tetragonal HfO2 phase was investigated in both samples treated with CHF3 and C4F8 plasmas. However, the samples treated with O-rich plasmas showed monoclinic phase, which indicated that the addition of O plasmas could influence the Hf/O ratio of the HfO2 films. The mechanism of the t-HfO2 formation was attributed to oxygen insufficiency generated by the incorporation of F atoms. The capacitors treated with C4F8/O2 plasmas displayed the highest k value, which ascribed that the C/F layers were suppressed and the tetragonal phase of HfO2 was formed. Good electrical properties, especially on the hysteresis voltage and frequency dispersion, were obtained because the bulk traps were passivated by the incorporation of F atoms. However, the H-related traps were generated during the CHF3 plasma treatments, which caused the performance degradation. All the treated samples showed lower leakage current density than the as-deposited HfO2 films at negative bias due to the reduced trap-assisted tunneling by the incorporation of F to block the electrons transferring from metal electrode to the trap level.
R. Álvarez; M. C. Quintero; A. Rodero
2005-01-01
In this paper, the radial distributions of emissivity of the species present in the helium-nitrogen, helium-oxygen and helium-argon plasmas sustained by the axial injection torch at atmospheric pressure are studied by optical emission spectroscopy using the Abel inversion procedure. The spectrum was scanned for atomic and ionic lines together with rotational bands of neutral and ionic molecules of such species.
Kinetic Theory of Coupled Oscillators
Hildebrand, Eric J.; Buice, Michael A.; Chow, Carson C.
2008-01-01
We present an approach for the description of fluctuations that are due to finite system size induced correlations in the Kuramoto model of coupled oscillators. We construct a hierarchy for the moments of the density of oscillators that is analogous to the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy in the kinetic theory of plasmas and gases. To calculate the lowest order system size effect, we truncate this hierarchy at second order and solve the resulting closed equations for the two-oscillator correlation function around the incoherent state. We use this correlation function to compute the fluctuations of the order parameter, including the effect of transients, and compare this computation with numerical simulations. PMID:17358861
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.
V. A. Sorokin; Yu. P. Tarasenko; S. V. Patrikeev; L. A. Orlovskii
1995-01-01
Aluminum powder and Al2O3-Al, Al2O3-SiO2-Al, Ni-Al composites are studied within the range 20–1000°C by means of derivatography. Temperature ranges are determined for the reaction of components, interaction with each other and with the reaction medium, as well the dehydration of Al2O3 and NiO. The kinetics of these processes are explained and their thermal effect is described. X-ray methods show that
Raul C. Maranhão; Ivete A. Roland; Odaly Toffoletto; José Antonio Ramires; Romélia P. Gonçalves; Carlos H. Mesquita; Fulvio Pileggi
1997-01-01
It was previously reported that a protein-free microemulsion (LDE) with structure roughly resembling that of the lipid portion\\u000a of low density lipoprotein (LDL) was presumably taken up by LDL receptors when injected into the bloodstream. In contact with\\u000a plasma, LDE acquires apolipoproteins (apo) including apo E that would be the ligand for receptor binding. Currently, apo were\\u000a associated to LDE
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.
Electron kinetics of collision dominated R. F. bulk plasma in CO: the role of second-kind collisions
Capitelli, M.; Celiberto, R.; Gorse, C.; Winkler, R.; Wilhelm, J.
1988-06-01
Electron energy distribution functions (EEDF) and related properties in the bulk region of the rf CO plasma at the reduced rf field frequency omega/p/sub 0/ = ..pi.. x 10/sup 7/ sec/sup -1/ torr/sup -1/ have been calculated by solving the time-dependent spatially homogeneous Boltzmann equation in the presence of second-kind collisions and have been interpreted on a microphysical basis. The results show that second-kind collisions (vibrational and electronic) strongly affect the temporal evolution of EEDF, of the mean energy, and of the mean collision frequencies for vibrational and electronic excitation processes, as well as for ionization. In particular, second-kind collisions in the CO rf bulk plasma strongly decrease the modulation of the mean ionization frequency during its periodical alteration in the rf field. Furthermore, the effect of second-kind collisions on an approximate determination of the time-averaged EEDF in the rf bulk plasma using the so-called effective-field approximation has been estimated.
A kinetic-MHD model for low frequency phenomena
Cheng, C.Z.
1991-07-01
A hybrid kinetic-MHD model for describing low-frequency phenomena in high beta anisotropic plasmas that consist of two components: a low energy core component and an energetic component with low density. The kinetic-MHD model treats the low energy core component by magnetohydrodynamic (MHD) description, the energetic component by kinetic approach such as the gyrokinetic equation, and the coupling between the dynamics of these two components through plasma pressure in the momentum equation. The kinetic-MHD model optimizes both the physics contents and the theoretical efforts in studying low frequency MHD waves and transport phenomena in general magnetic field geometries, and can be easily modified to include the core plasma kinetic effects if necessary. It is applicable to any magnetized collisionless plasma system where the parallel electric field effects are negligibly small. In the linearized limit two coupled eigenmode equations for describing the coupling between the transverse Alfven type and the compressional Alfven type waves are derived. The eigenmode equations are identical to those derived from the full gyrokinetic equation in the low frequency limit and were previously analyzed both analytically nd numerically to obtain the eigenmode structure of the drift mirror instability which explains successfully the multi-satellite observation of antisymmetric field-aligned structure of the compressional magnetic field of Pc 5 waves in the magnetospheric ring current plasma. Finally, a quadratic form is derived to demonstrate the stability of the low-frequency transverse and compressional Alfven type instabilities in terms of the pressure anisotropy parameter {tau} and the magnetic field curvature-pressure gradient parameter. A procedure for determining the stability of a marginally stable MHD wave due to wave-particle resonances is also presented.
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
Magnetized Inhomogeneous Dusty Plasma Unstable Modes
Cereceda, Carlo; Puerta, Julio; Castro, Enrique [Departamento de Fisica, Universidad Simon Bolivar, Apdo. 89000, Caracas (Venezuela)
2006-12-04
The propagation of waves in unmagnetized dusty plasmas has been extensively studied in last years, describing DAW and DIAW modes. For magnetized, inhomogeneous dusty plasmas exists a series of works describing the theory of wave propagation, mainly fluid like description. However, there is a lack of detailed calculation and description of modes, being limited the recent works to magnetized electrons and neglecting the magnetization of ions and dust particles. In this work, we perform a detailed description of the whole magnetized system from full kinetic treatment and show detailed calculation of the unstable modes associated to ion and dust grains. High precision four pole approximations for the Z dispersion function are used. Comparison with previous results in the limiting cases are provided.
NASA Astrophysics Data System (ADS)
Ricconi, B. J.; Park, S.-J.; Sung, S. H.; Tchertchian, P. A.; Eden, J. G.
2007-05-01
Emission in the ultraviolet from the A?+2 electronic excited states of OH, NeD, and ArD, and the formation kinetics of these excited heteronuclear diatomics, have been investigated in microcavity plasmas generated in rare gas/H2O or D2 gas mixtures. Excitation transfer from the a?u +3(1u,0u-) Rydberg state of Ar2 appears to be the dominant pathway to OH(A?+2) formation in Ar /H2O vapor mixtures with total pressures of 400-800Torr and H2O partial pressures of 100mTorr-3Torr. Maximum emission on the (v',v?)=(0,0) vibrational band of the OH(A ?X) transition is observed in a 25?m, 45nl microcavity for 600-800Torr Ar/0.5Torr H2O mixtures. Comparisons of experimental and simulated fluorescence spectra show the OH[A?+2(v'=0)] state rotational temperature to be 425K for 600Torr Ar/100mTorr H2O mixtures but to rise linearly with the H2O partial pressure and exhibit a slope of 170K/Torr H2O for 100mTorr?pH2O?3Torr. Excitation of Ne or Ar /D2 gas mixtures in 50×50 arrays of Si microplasma devices generates broadband spectra, peaking in the mid-ultraviolet (?˜280-320nm), which are attributed to the A ?X transition of the ArD or NeD excimers. The optimal D2 concentration is observed to be ˜0.5% and the primary kinetic formation mechanism for the deuterides involves D atom transfer in collisions between Ar(4sP3) and D2.
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.
Fundamentals of Plasma Sails Propulsion Concept
NASA Technical Reports Server (NTRS)
Khazanov, G. V.; Kabin, K.; Delamere, P. A.
2002-01-01
The Mini-Magnetospheric Plasma Propulsion (M2P2), originally proposed by Winglee et al. [2000], is based on the two-fluid plasma model and requires a 15-km frontal standoff distance (or 20-km cross-sectional diameter) in order for the magnetic bubble to absorb sufficient momentum from the SW to accelerate a spacecraft to the unprecedented speeds of 50-80 km/s after an acceleration period of about three months. Winglee et al. [2000] derived the above size requirement based on an extrapolation of their simulated results in which a system much smaller than a M2P2 was used (p. 21,074 of their study). We submit, however, that a fluid model has no validity for such a small scale size-even in the region near the plasma source! It is assumed in the MHD fluid model, normally applied to the magnetosphere, that the characteristic scale-size is much greater than the Larmor radius and ion skin depth of the SW. In the case of the M2P2, however, the size of the magnetic bubble is actually less than or, at best, comparable to, the scale of these characteristic parameters and, therefore, a kinetic approach, which addresses the smallscale physical mechanisms involved, must be used. A fully three-dimensional version of the hybrid code is used in our M2P2 (Plasma Sails) studies was originally developed by Delamere et al. [1999]. The M2P2 plasma sail is an excellent application for this hybrid code. The primary advantage of this code is the seamless interface between fluid and kinetic descriptions of the ion populations. A kinetic description is not necessary for the dense inner regions of the magnetic bubble and tremendous computational savings can be realized by treating this dense, magnetized ion population with the fluid description. It is essential, however, that the outer bubble regions be treated kinetically as well as the SW protons. Comparison of full size M2P2 simulation based on 3D MHD and kinetic models show that kinetic treatment introduces much more asymmetry to the considering problem and the possibility of kinetic instabilities development.
Transport of Aluminum impurities in Helium Plasma
NASA Astrophysics Data System (ADS)
Hajjar, Rima; Hollmann, Eric; Krasheninnikov, Sergei; Doerner, Russell
2013-10-01
Impurity radiation losses at the edge of fusion devices are crucial for establishing detached divertor regimes in ITER and future tokamak reactors, despite the problem they cause in reducing plasma efficiency. Complex parallel and cross-field impurity transport suggest a rather fluid description when treating edge dynamics, leading somehow to marginal simulation results of the impurity transport problem. A kinetic description accounting for impurity/plasma collisions should be used instead, generating more details on the collision dynamics, while the relatively high mass difference between colliding particles leads to major simplifications in the physics of the problem. Modeling of Aluminum injection and entrainment into steady-state Helium plasma is presented. Multiple ionization and radial losses are included and numerical results are then compared to experimental data obtained from PISCES machine. Impurity radiation losses at the edge of fusion devices are crucial for establishing detached divertor regimes in ITER and future tokamak reactors, despite the problem they cause in reducing plasma efficiency. Complex parallel and cross-field impurity transport suggest a rather fluid description when treating edge dynamics, leading somehow to marginal simulation results of the impurity transport problem. A kinetic description accounting for impurity/plasma collisions should be used instead, generating more details on the collision dynamics, while the relatively high mass difference between colliding particles leads to major simplifications in the physics of the problem. Modeling of Aluminum injection and entrainment into steady-state Helium plasma is presented. Multiple ionization and radial losses are included and numerical results are then compared to experimental data obtained from PISCES machine. Work was supported in part by the DOE Grant DE-FG02-04ER54739 at UCSD.
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.
Possible negative collisional damping and instability of a drifting two-dimensional quantum plasma
C. Zhang; G. Gumbs
1993-01-01
The high-frequency conductivity\\/resistivity of a two-dimensional quantum plasma embedded in a random distribution of impurities is calculated with the use of a semiclassical kinetic description. The plasma is drifting at speed vD relative to the impurities and the system is under the influence of an electromagnetic radiation of wave number q and frequency ?. It is shown that the collisional
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
Abraham, Sinoj; Bahniuk, Markian S; Unsworth, Larry D
2012-12-01
Protein-surface interactions are crucial to the overall biocompatability of biomaterials, and are thought to be the impetus towards the adverse host responses such as blood coagulation and complement activation. Only a few studies hint at the ultra-low fouling potential of zwitterionic poly(carboxybetaine methacrylate) (PCBMA) grafted surfaces and, of those, very few systematically investigate their non-fouling behavior. In this work, single protein adsorption studies as well as protein adsorption from complex solutions (i.e. human plasma) were used to evaluate the non-fouling potential of PCBMA grafted silica wafers prepared by nitroxide-mediated free radical polymerization. PCBMAs used for surface grafting varied in charge separating spacer groups that influence the overall surface charges, and chain end-groups that influence the overall hydrophilicity, thereby, allows a better understanding of these effects towards the protein adsorption for these materials. In situ ellipsometry was used to quantify the adsorbed layer thickness and adsorption kinetics for the adsorption of four proteins from single protein buffer solutions, viz, lysozyme, ?-lactalbumin, human serum albumin and fibrinogen. Total amount of protein adsorbed on surfaces differed as a function of surface properties and protein characteristics. Finally, immunoblots results showed that human plasma protein adsorption to these surfaces resulted, primarily, in the adsorption of human serum albumin, with total protein adsorbed amounts being the lowest for PCBMA-3 (TEMPO). It was apparent that surface charge and chain hydrophilicity directly influenced protein adsorption behavior of PCBMA systems and are promising materials for biomedical applications. PMID:22665019
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
NASA Astrophysics Data System (ADS)
Hadjadj, A.; Djellouli, G.; Jbara, O.
2010-11-01
We performed H2 plasma treatment of hydrogenated amorphous silicon (a-Si:H) thin films and followed by in situ spectroscopic ellipsometry measurements the kinetics of hydrogen-induced film modifications at temperatures varying from 100 to 250 °C. The time-dependence of the H-modified layer thickness dH(t) follows an exponential relation of the form dH0[1-exp(-t/?)]. The temperature-dependence of dH0 and ? shows a discontinuity at T =200 °C. While the activation energy of dH0 changes from 0.19 eV at T <200 °C to 0.05 eV at higher temperatures, the activation energy of ? suddenly changes from 0.15 eV to a negative value (-0.26 eV). Such a discontinuity should be linked to the thermal equilibrium temperature of undoped a-Si:H. Moreover, we found that the rate of formation of the H-modified layer rH=dH0/? varies in inverse proportion to the etching rate, indicating a balance between hydrogen insertion and film etching at the steady state.
NASA Astrophysics Data System (ADS)
Medvedev, N. A.; Rymzhanov, R. A.; Volkov, A. E.
2013-11-01
Complex dielectric function formalism is applied to obtain the cross-sections, mean free path of electrons, and energy losses of swift heavy ions (SHI) in solid LiF and Y2O3 out of the experimentally known loss function. The calculated electron inelastic mean free paths in these materials agree very well with the NIST database; the inelastic energy losses of swift Pb and Au ions agree well with those calculated with the widely used SRIM and CasP codes. The obtained cross-sections are used in Monte Carlo simulations of the electronic kinetics after SHI impacts. The radial distributions of the electron and valence hole densities as well as their energy densities were calculated.
Self-consistent Equilibrium Model of Low-aspect-ratio Toroidal Plasma with Energetic Beam Ions
E.V. Belova; N.N. Gorelenkov; C.Z. Cheng
2003-04-09
A theoretical model is developed which allows the self-consistent inclusion of the effects of energetic beam ions in equilibrium calculations of low-aspect-ratio toroidal devices. A two-component plasma is considered, where the energetic ions are treated using a kinetic Vlasov description, while a one-fluid magnetohydrodynamic description is used to represent the thermal plasma. The model allows for an anisotropic distribution function and a large Larmor radius of the beam ions. Numerical results are obtained for neutral-beam-heated plasmas in the National Spherical Torus Experiment (NSTX). Self-consistent equilibria with an anisotropic fast-ion distribution have been calculated for NSTX. It is shown for typical experimental parameters that the contribution of the energetic neutral-beam ions to the total current can be comparable to that of the background plasma, and that the kinetic modifications of the equilibrium can be significant. The range of validity of the finite-Larmor-radius expansion and of the reduced kinetic descriptions for the beam ions in NSTX is discussed. The calculated kinetic equilibria can be used for self-consistent numerical studies of beam-ion-driven instabilities in NSTX.
Salmon, E.; Brooks, D.J.; Leenders, K.L.; Turton, D.R.; Hume, S.P.; Cremer, J.E.; Jones, T.; Frackowiak, R.S. (Hammersmith Hospital, London (England))
1990-05-01
S-(11C)Nomifensine (S-(11C)NMF) is a positron-emitting tracer suitable for positron emission tomography, which binds to both dopaminergic and noradrenergic reuptake sites in the striatum and the thalamus. Modelling of the cerebral distribution of this drug has been hampered by the rapid appearance of glucuronide metabolites in the plasma, which do not cross the blood--brain barrier. To date, (11C)NMF uptake has simply been expressed as regional versus nonspecific cerebellar activity ratios. We have calculated a free NMF input curve from red cell activity curves, using the fact that the free drug rapidly equilibrates between red cells and plasma, while glucuronides do not enter red cells. With this free (11C)NMF input function, all regional cerebral uptake curves could be fitted to a conventional two-compartment model, defining tracer distribution in terms of (11C)NMF regional volume of distribution. Assuming that the cerebellar volume of distribution of (11C)NMF represents the nonspecific volume of distribution of the tracer in striatum and thalamus, we have calculated an equilibrium partition coefficient for (11C)NMF between freely exchanging specific and nonspecific compartments in these regions, representing its binding potential to dopaminergic or noradrenergic uptake sites (or complexes). This partition coefficient was lower in the striatum when the racemate rather than the active S-enantiomer of (11C)NMF was administered. In the striatum of patients suffering from Parkinson's disease and multiple-system atrophy, the specific compartmentation of S-(11C)NMF was significantly decreased compared with that of age-matched volunteers.
An Open-Source Spacecraft Plasma Interaction Simulation Code PicUp3D: Tests and Validations
Julien Forest; Alain Hilgers; Benoît Thiébault; Lars Eliasson; Jean-Jacques Berthelier; Hervé de Feraudy
2006-01-01
The PicUp3D code is a prototype of simulation software dedicated to quantitative and accurate modeling of spacecraft plasma interactions developed in the context of a European scientific and industrial network Spacecraft Plasma Interaction Network in Europe. It is based on a full three-dimensional kinetic particle-in-cell description of the electrons and the ion dynamics. The use of unstructured schemes in the
Plasma Detachment Study in VASIMR
A. V. Ilin; F. R. Chang Díaz; J. P. Squire; B. N. Breizman; S. V. Novakovski; R. Z. Sagdeev
2000-01-01
We present kinetic and MHD simulations of plasma detachment in the exhaust of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). The detachment is associated with a transition from subalfvenic to superalfvenic plasma flow in the magnetic nozzle. As a result, the kinetic energy of the outgoing plasma flow is greater than the magnetic field energy in the exhaust area, so
PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis. Domier and N.C. Luhmann, Jr. UC at Davis at Workshop on Long Time Simulations of Kinetic Plasmas April 21, 2006 Hyatt Regency, Dallas, TX #12;PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA
Constraints on fluid modeling of magnetized collisionless plasmas
NASA Astrophysics Data System (ADS)
Sulem, Pierre-Louis; Passot, Thierry; Laveder, Dimitri; Hunana, Peter; Henri, Pierre
2013-04-01
It is well known that a complete description of the solar wind requires a kinetic description and that, particularly at sub-proton scales, kinetic effects cannot be ignored. It is nevertheless usually assumed that, at scales significantly larger than the proton gyroscale, MHD or bifluid models with isotropic pressures provide a satisfactory description. We demonstrate that in order to accurately capture, even at large scales, the low-frequency dynamics of a collisionless plasma, a fluid model should actually include kinetic effects such as Landau damping and finite Larmor radius corrections. Indeed, the usual polytropic bi-fluid models strongly overestimate the magnetic compressibility of oblique Alfvén waves. Retaining pressure anisotropy and Landau damping partially corrects this deficiency, but an accurate description of the Alfvén wave polarization and of the mirror instability growth rate actually requires to take into account the finite-Larmor corrections to all the retained moments. These remarks lead us to use the so-called FLR Landau fluid model (Phys. Plasmas, 19, 082113, 2012), for which a three-dimensional parallel code has been developed. Preliminary simulations in the turbulent regime will be presented, showing the reduction of the fluid compressibility and the inhibition of the parallel energy transfer. We will also report on the development of temperature anisotropy, associated with non-resonant perpendicular ion heating and constrained by the onset of the mirror instability.
Kiefer, Thomas [Friedrich-Schiller-Universitaet Jena, Jena (Germany); Schlegel, Theodor [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Helmholtz Institute Jena, Jena (Germany)
2012-10-15
It is shown that the hydrodynamic model of a one-dimensional collisionless plasma expansion is contained in the kinetic description as a special case. This belongs to a specific choice for the electron distribution function. Moreover, the consequences of the use of the hydrodynamic approach regarding the temporal evolution of the electron phase space density are investigated. It turns out that only the case of a hydrodynamic description with the adiabatic constant {kappa}=3 is physically self-consistent. Numerical simulations confirm this argumentation. The analysis for the case {kappa}=3 is extended to the kinetics of a relativistic electron gas.
Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.
1996-05-01
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.
Nonlinear kinetic model for lower-hybrid solitary structures
Jovanovic, D.; Shukla, P. K.; Morfill, G. [Institute of Physics, P. O. Box 57, 11001 Belgrade (Serbia); Institut fuer Theoretische Physik IV, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany) and School of Physics, University of KwaZulu-Natal, 4000 Durban (South Africa); Max-Planck-Institut fuer Extraterrestrische Physik, D-85740 Garching (Germany)
2007-08-15
Nonlinear drift-kinetic theory is proposed for lower-hybrid solitary structures in near-Earth plasmas, based on a two time scale kinetic description of nonlinear interactions between the lower-hybrid and dispersive Alfven waves. The detailed derivation of the nonlinear coupling terms in an arbitrary geometry is presented, that include the ponderomotive potential, non-curl-free component of the perpendicular electron velocity, and the electron diffusion in velocity space. It is shown that the resonant particles are trapped by the combined effects of the slow and ponderomotive potentials, and that their density is further modified by their diffusion in velocity space, yielding a new type of coherent structure, which is identified as an electron hole, coupled with a nonlinear Schroedinger-type soliton. A numerical solution is found in the form of train of soliton-like lower-hybrid spikes, trapped inside a weakly two-dimensional slab electron hole.
NASA Astrophysics Data System (ADS)
The following topics were dealt with: equilibrium properties and equations of state of dense plasmas, plasma kinetics, plasma transport processes, optics of plasmas, laser and heavy ion beam produced plasma, statistical theory and computer simulation, dense astrophysical plasma.
Michigan Institute for Plasma Sci-
Shyy, Wei
polarization in the skin layer and second harmonic current circu- lating around the main discharge current kinetics and plasma elec- trodynamics, plasma diagnostics, light source science and technology, plasma devices for material processing and plasma system design. Dr. Godyak is a Fellow of the APS
D G Swanson
2003-01-01
To a beginner in plasma physics the subject of waves can be bewildering, with a seeming myriad of different wave modes and ways of approaching them though cold plasma equations, warm plasma equations or kinetic equations. Add to this the intricacies of Landau and cyclotron damping and the fact that real plasmas are rarely uniform and infinite in extent, even
Kushner, M.J.
1982-04-01
A kinetic model of the plasma-etching process has been developed to describe the etching of Si and SiO/sub 2/ in C/sub n/F/sub m//O/sub 2/ and C/sub n/F/sub m//H/sub 2/ plasmas (C/sub n/F/sub m/ equivalentCF/sub 4/, C/sub 2/F/sub 6/). The model has obtained good agreement with experiment for demonstrating the selective etching of SiO/sub 2/ in C/sub n/F/sub m//H/sub 2/ plasmas, and the enhancement of the etch rate of Si in C/sub n/F/sub m//O/sub 2/ plasmas. Good agreement is also obtained with mass spectroscopic measurements of neutral species from a CF/sub 4//H/sub 2/ plasma. Results from the model indicate that the adsorption of atomic hydrogen on silicon surfaces from C/sub n/F/sub m//H/sub 2/ plasmas, which then reacts with adsorbed fluorine, can significantly effect the selectivity of etching SiO/sub 2/ with respect to Si. Similarly, the adsorption of atomic oxygen, which then reacts with adsorbed carbon thereby cleansing the surface, may be responsible for the large etch rates of Si seen in C/sub n/F/sub m//O/sub 2/ plasmas. The selectivity of etching SiO/sub 2/ in C/sub n/F/sub m//H/sub 2/ plasmas has been found to be a sensitive function of the C/F ratio of the carbon-bearing molecules which desorb from the surface, and a C/F ratio of 0.5 shows best agreement with experiment. Results from the model favor ion drift as a dominant mechanism by which radicals are transported to the surface.
Kinetic activation-relaxation technique
Laurent Karim Béland; Peter Brommer; Fedwa El-Mellouhi; Jean-François Joly; Normand Mousseau
2011-01-01
We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic
Matalas, N.C.
1991-01-01
What constitutes a comprehensive description of drought, a description forming a basis for answering why a drought occurred is outlined. The description entails two aspects that are "naturally" coupled, named physical and economic, and treats the set of hydrologic measures of droughts in terms of their multivariate distribution, rather than in terms of a collection of the marginal distributions. ?? 1991 Springer-Verlag.
Ion distribution in the hot spot of an inertial confinement fusion plasma
NASA Astrophysics Data System (ADS)
Tang, Xianzhu; Guo, Zehua; Berk, Herb
2012-10-01
Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform Fokker-Planck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by Fokker-Planck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated.
Hong, Juhee
We compute the nonequilibrium stress tensor induced by a heavy quark moving through weakly coupled QCD plasma at the speed of light and compare the result to N=4 super-Yang-Mills theory at strong coupling. The QCD Boltzmann ...
Chris C. Dobson; Ivana Hrbud
2004-01-01
Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa
Greifswald, Ernst-Moritz-Arndt-Universität
2005-01-01
, CF2, CF3, are important species for formation of compounds with higher molecular weight (oligomers in Molecular Gases M. Geigl, S. Peters , O. Gabriel, B. Krames, and J. Meichsner Ernst Moritz Arndt UniversityA, Weinheim 1 Introduction Knowledge of concentration and kinetics of transient reactive species in molecular
Nguyen, Minh Tho
in our laboratory,8 in the present work a kinetic study of the reaction between copper atoms and methyl carried out in a fast-flow reactor. The gas phase copper atoms were generated using the microwave of the reaction is lowered to 24.8 kJ mol-1 . The measured values of k1 as a function of temperature can best
TOPICAL REVIEW: Striations in rare gas plasmas
Vladimir I. Kolobov
2006-01-01
This paper describes the recent progress in understanding the nature of striations in rare gas plasmas. Striations are ionization waves with unique properties determined by transport phenomena, ionization processes and electron kinetics in current-carrying plasmas. Recent progress in understanding the physics of striations is mainly associated with the advances of non-local electron kinetics in spatially inhomogeneous plasmas and the development
A macroscopic plasma Lagrangian and its application to wave interactions and resonances
NASA Technical Reports Server (NTRS)
Peng, Y. K. M.
1974-01-01
The derivation of a macroscopic plasma Lagrangian is considered, along with its application to the description of nonlinear three-wave interaction in a homogeneous plasma and linear resonance oscillations in a inhomogeneous plasma. One approach to obtain the Lagrangian is via the inverse problem of the calculus of variations for arbitrary first and second order quasilinear partial differential systems. Necessary and sufficient conditions for the given equations to be Euler-Lagrange equations of a Lagrangian are obtained. These conditions are then used to determine the transformations that convert some classes of non-Euler-Lagrange equations to Euler-Lagrange equation form. The Lagrangians for a linear resistive transmission line and a linear warm collisional plasma are derived as examples. Using energy considerations, the correct macroscopic plasma Lagrangian is shown to differ from the velocity-integrated low Lagrangian by a macroscopic potential energy that equals twice the particle thermal kinetic energy plus the energy lost by heat conduction.
Physics issues associated with low-beta plasma generators
NASA Technical Reports Server (NTRS)
Borovsky, Joseph E.
1992-01-01
Kinetic aspects of MHD generators are explored by examining the propagation of dense, low-beta streams of plasma. Three situations are considered: the basic principles of plasma-stream propagation, the propagation of plasma streams into vacuum, and the propagation of plasma streams into ambient plasmas. These three situations are analogous to plasma generators, plasma generators with vacuum loads, and plasma generators with plasma loads. Kinetic (microphysics) aspects include oscillations of the generator plasma, the effects of diocotron instabilities, the acceleration of particles, the starvation of current systems, and plasma-wave production.
MHD versus kinetic effects in the solar coronal heating: a two stage mechanism
David Tsiklauri
2006-06-27
Using Particle-In-Cell simulations i.e. in the kinetic plasma description the discovery of a new mechanism of parallel electric field generation was recently reported. Here we show that the electric field generation parallel to the uniform unperturbed magnetic field can be obtained in a much simpler framework using the ideal magnetohydrodynamics (MHD) description. In ideal MHD the electric field parallel to the uniform unperturbed magnetic field appears due to fast magnetosonic waves which are generated by the interaction of weakly non-linear Alfv\\'en waves with the transverse density inhomogeneity. In the context of the coronal heating problem a new {\\it two stage mechanism} of plasma heating is presented by putting emphasis, first, on the generation of parallel electric fields within an {\\it ideal MHD} description directly, rather than focusing on the enhanced dissipation mechanisms of the Alfv\\'en waves and, second, dissipation of these parallel electric fields via {\\it kinetic} effects. It is shown that for a single Alfv\\'en wave harmonic with frequency $\
NASA Technical Reports Server (NTRS)
Dobson, Chris C.; Hrbud, Ivana
2004-01-01
Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the 1-D Poisson equation for EC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with non-fusing hydrogen-1. The deuterium rates are consistent with predictions from the model.
NASA Technical Reports Server (NTRS)
Dobson, Chris C.; Hrbud, Ivana
2004-01-01
Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7 x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the one-dimensional Poisson equation for IEC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with nonfusing hydrogen- 1. The deuterium rates are consistent with predictions from the model.
Nonlinear instability saturation due to quasi-particle trapping in a turbulent plasma
Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Benkadda, S. [IIFS-PIIM, CNRS-Aix-Marseille Universite, Centre de Saint Jerome, 13397 Marseille Cedex 20 (France)
2012-08-15
We consider the problem of a single wave mode stability, dispersion, and nonlinear saturation in a turbulent plasma background. We adopt a wave kinetic description for the quasi-particle turbulence and assume a low frequency perturbation of both the plasma and the turbulent spectrum. We describe an improved theoretical approach, which goes beyond the geometric optics approximation and retains the recoil effects associated with the emission and absorption of low frequency waves by nearly resonant quasi-particles. We illustrate the present approach by considering the case of zonal flow excited by drift wave turbulence.
Applications of Hamiltonian and Action Principle Formulations of Plasma Physics
NASA Astrophysics Data System (ADS)
Morrison, P. J.
2004-11-01
Equations of plasma physics ultimately derive their Hamiltonian and action principle forms from those of Maxwell's equations self-consistently coupled to charged particle dynamics. The forms vary depending on the model (e.g. kinetic or fluid) and the variables (e.g. Eulerian, Lagrangian, or Clebsch) used for plasma description, and this has been a source of confusion and rediscovery (see e.g. [1,2] for review). In the past 25 years there has been extensive research on the Hamiltonian and action principle formulations of plasma equations. The various formulations will be reviewed and their interconnections explored. Recent advances in the use of these formulations for describing a variety of plasma phenomena will be discussed. Topics may include: a) Reduced Fluid Models, their derivation and classification for tokamak models with gyroviscosity, ITG, ETG, etc; b) Hamiltonian Closure Theory, obtaining exact and inexact fluid models from kinetic theory; c) Fluctuation Spectra, their derivation by statistical mechanics principles for fluid and Vlasov turbulence; d) Hamiltonian Simulated Annealing, the use of Poisson brackets in a numerical relaxation method for calculating coherent structures; and e) Single and Multi-wave Models, their derivation and application to beam-plasma interaction. [1] P. J. Morrison, Rev. Mod. Phys., vol. 70 , 467 (1998) [2] H. Ye and P. J. Morrison, Phys. Fluids B, vol. 4, 771 (1992).
Atmospheric pressure plasmas: A review
Claire Tendero; Christelle Tixier; Pascal Tristant; Jean Desmaison; Philippe Leprince
2006-01-01
This article attempts to give an overview of atmospheric plasma sources and their applications. The aim is to introduce, in a first part, the main scientific background concerning plasmas as well as the different atmospheric plasma sources (description, working principle). The second part focuses on the various applications of the atmospheric plasma technologies, mainly in the field of surface treatments.Thus
Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.
Capolupo, A; Giampaolo, S M; Illuminati, F
2013-10-01
Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments. PMID:24229140
Modulational interactions in quantum plasmas
Sayed, F.; Tyshetskiy, Yu. [School of Physics, University of Sydney, New South Wales 2006 (Australia)] [School of Physics, University of Sydney, New South Wales 2006 (Australia); Vladimirov, S. V. [School of Physics, University of Sydney, New South Wales 2006 (Australia) [School of Physics, University of Sydney, New South Wales 2006 (Australia); Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)] [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
2013-07-15
A formalism for treating modulational interactions of electrostatic fields in collisionless quantum plasmas is developed, based on the kinetic Wigner-Poisson model of quantum plasma. This formalism can be used in a range of problems of nonlinear interaction between electrostatic fields in a quantum plasma, such as development of turbulence, self-organization, as well as transition from the weak turbulent state to strong turbulence. In particular, using this formalism, we obtain the kinetic quantum Zakharov equations that describe nonlinear coupling of high frequency Langmuir waves to low frequency plasma density variations, for cases of non-degenerate and degenerate plasma electrons.
The deformation and fracture kinetics of stress corrosion cracking
A. S. Krausz
1978-01-01
The concepts of deformation and fracture kinetics theory are extended for the analysis of stress corrosion cracking. A single, coherent system is developed that provides the full kinetics description of the typical SCC behavior. The kinetics approach shows that Regions I and II are associated with two consecutive energy barriers, parallel with the single barrier associated with Regon III. The
Nonexponential Kinetics of DNA Escape from ?-Hemolysin Nanopores
Matthew Wiggin; Carolina Tropini; Vincent Tabard-Cossa; Nahid N. Jetha; Andre Marziali
2008-01-01
Throughput and resolution of DNA sequence detection technologies employing nanometer scale pores hinge on accurate kinetic descriptions of DNA motion in nanopores. We present the first detailed experimental study of DNA escape kinetics from ?-hemolysin nanopores and show that anomalously long escape times for some events result in nonexponential kinetics. From the distribution of first-passage times, we determine that the
A. K. Shuaibov; V. I. Chygin; L. L. Shimon; I. V. Shevera; P. P. Gorun; R. O. Obukhovskii
2010-01-01
The results of studying the radiation due to argon, krypton, and xenon monochloride bands, as well as to the bands of chlorine\\u000a molecules, from the plasma of a transverse Ar-Kr-Xe-Cl2 volume discharge are reported. The working mixture of a pulse radiation source is optimized with regard to its pressure and\\u000a elemental composition and parameters of an excitation system. By numerically
Plasma stability in a dipole magnetic field
Simakov, Andrei N., 1974-
2001-01-01
The MHD and kinetic stability of an axially symmetric plasma, confined by a poloidal magnetic field with closed lines, is considered. In such a system the stabilizing effects of plasma compression and magnetic field ...
Weakly Turbulent MHD Waves in Compressible Low-Beta Plasmas
Benjamin D. G. Chandran
2008-10-30
In this Letter, weak turbulence theory is used to investigate interactions among Alfven waves and fast and slow magnetosonic waves in collisionless low-beta plasmas. The wave kinetic equations are derived from the equations of magnetohydrodynamics, and extra terms are then added to model collisionless damping. These equations are used to provide a quantitative description of a variety of nonlinear processes, including "parallel" and "perpendicular" energy cascade, energy transfer between wave types, "phase mixing," and the generation of back-scattered Alfven waves.
Transport properties of dense deuterium-tritium plasmas
Wang, Cong; He, Xian-Tu; Zhang, Ping
2012-01-01
Consistent descriptions of the equation of states, and information about transport coefficients of deuterium-tritium mixture are demonstrated through quantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm$^{3}$ and a temperature of $10^{4}$ eV). Diffusion coefficients and viscosity are compared with one component plasma model in different regimes from the strong coupled to the kinetic one. Electronic and radiative transport coefficients, which are compared with models currently used in hydrodynamic simulations of inertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is also discussed from the highly degenerate to the intermediate region.
NASA Astrophysics Data System (ADS)
Rajan, Karthikeyan; Shanmugasundaram, Thangaraju; Subramanya Sarma, Vadlamani; Murty, B. S.
2013-09-01
Nanocrystalline mechanically alloyed powders of 9Cr-1Mo ferritic steels with and without yttria dispersoids were densified using spark plasma sintering (SPS) to near-theoretical density at a temperature of 1073 K (800 °C). Studies on densification behaviour revealed that steels with dispersoids densified faster when compared to Fe-9Cr-1Mo steel. The evaluation of densification mechanisms during SPS reveals that grain boundary and lattice diffusion to be predominant at relative densities ranging from >0.7 to 0.9 in both the alloys.
NASA Astrophysics Data System (ADS)
Williams, J. D.; Thomas, E., Jr.; Couëdel, L.; Ivlev, A. V.; Zhdanov, S. K.; Nosenko, V.; Thomas, H. M.; Morfill, G. E.
2012-10-01
Melting of a two-dimensional plasma crystal occurring due to a mode-coupling instability is studied using particle tracking and particle image velocimetry techniques. By combining these techniques, it is possible to identify the location of a propagating melting front and find a characteristic scale length for the temperature gradient across the front. It is found that the measurements of heat transport are consistent with a simple two-dimensional model allowing us to estimate the thermal diffusivity. The measured values for the thermal diffusivity are consistent with previously measured values.
Review of Atomic Physics of Dense Plasmas
Richard M. More
2003-01-01
Atomic physics of dense plasmas is a fascinating, complex and often difficult topic in plasma physics that draws from many scientific disciplines and is an integral part of the description of high energy-density plasmas, magnetic fusion plasmas, laser-plasma interactions and the science of warm condensed matter. In this talk, characteristic \\
Laser-seeded modulation instability in a proton driver plasma wakefield accelerator
Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States); Pukhov, Alexander [Institut für Theoretische Physik I, Universität Düsseldorf, Düsseldorf 40225 (Germany)] [Institut für Theoretische Physik I, Universität Düsseldorf, Düsseldorf 40225 (Germany)
2013-10-15
A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (?100–1000 m)
Sixteen-moment approximation for a collisionless space plasma: Waves and instabilities
Kuznetsov, V. D. [Russian Academy of Sciences, Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Russian Federation); Dzhalilov, N. S. [Academy of Sciences of Azerbaijan, Shemakha Astrophysical Observatory (Azerbaijan)
2009-11-15
A study is carried out of waves and instabilities in an anisotropic collisionless plasma. In a strongly magnetized plasma, the velocity distributions along and across the magnetic field lines are different, which results in anisotropy of the total pressure and gives rise to an anisotropic heat flux. The fluid description of the plasma is based on the 16-moment integral transport equations, which are integral equations obtained from the Boltzmann-Vlasov kinetic equation. For small incompressible perturbations in a homogeneous plasma, the general dispersion relation implies that there are not only firehose modes, but also three additional modes, and that all four wave modes interact with each other if a heat flux is present. Heat fluxes do not change the properties of conventional firehose modes. The conditions for the onset of instabilities are investigated as functions of the parameters of the problems. Qualitative estimates for conditions typical of the solar corona are presented.
Strong laser field interaction with a sharp nonuniform overdense plasma
Zakorko, Z.S.; Inovenkov, I.N.; Kim, A.V. [Inst. of Applied Physics, Novgorod (Russian Federation)
1995-12-31
The interaction of ultrashort ({le}1 psec) high-intensity laser pulses with matter has attracted considerable attention in recent years because of its potential as a source of picosecond x-ray pulses. Hard x rays associated with very energetic electrons have been measured in experiments. Ultrashort pulse lasers have also opened a regime representing an entirely new situation for description of laser-plasma interaction. Since the plasma has little time to expand during the laser pulse, it has density gradient length much shorter than the laser wavelength and allow the possibility of generating high-temperature near-solid density plasmas. Initially, experimental results for plasmas interacting with high-intensity contrast laser pulses at intensities in the range of 10{sup 15}W/cm{sup 2} suggested that inverse bremsstrahlung is the dominant absorption mechanism. However, at higher intensities, the electrons acquire high energies for which his collisional absorption mechanism becomes ineffective. Evidence based on x-ray emission as well as theory has suggested that at intensities of laser radiation exceeding 10{sup 17}Wcm{sup -2} resonance absorption due to p-polarized component of the incoming laser field which describes the energy transfer from an electromagnetic wave to an electron plasma wave could play an important role even for plasmas with a scale length considerably shorter than the laser wavelength. It was found that the characteristics of the interaction were determined by the intensity of the p-polarized component rather than the total intensity and a significant fraction of the laser energy was absorbed in the suprathermal electrons. In the high-intensity regime, absorption involves nonlinear kinetic effects and the isothermal approximation, which was successfully applied for the description of plasma dynamics in nanosecond pulse laser-plasma interactions, becomes invalid.
Theory of the unmagnetized plasma.
NASA Technical Reports Server (NTRS)
Montgomery, D. C.
1971-01-01
The Vlasov mathematical model of a plasma, which has come to be thought more useful than any other in describing the dynamical behavior of the majority of plasmas of interest, is first examined. Macroscopic variables and moment equations; linear electrostatics solutions; plasma oscillations, ion acoustic waves, and linear instabilities are treated, as well as external fields, 'test' charges, and nonlinear Vlasov phenomena. Plasmas are statistically described, and attention is given to the kinetic theory of the stable, uniform plasma and the Balescu-Lenard equation; two-time ensemble averages and fluctuation spectra in stable plasmas; the kinetic theory of the unstable plasma; and ensembles of Vlasov plasmas. Some illustrative experiments are described. Four appendixes deal with the electrostatic approximation and transverse waves; solution of the linearized Vlasov equation in a magnetic field; estimates of correlation functions from thermal equilibrium; and equivalence of spatially uniform BBGKY and Klimontovich correlations.
L. O. Silva; R. A. Fonseca; J. W. Tonge; J. M. Dawson; W. B. Mori; M. V. Medvedev
2003-01-01
We present the first three-dimensional fully kinetic electromagnetic\\u000arelativistic particle-in-cell simulations of the collision of two\\u000ainterpenetrating plasma shells. The highly accurate plasma-kinetic\\u000a\\
ERIC Educational Resources Information Center
Weed, Harrison D., Jr.
This brief text was written to provide more extensive treatment of descriptive statistics than is ordinarily available in modern statistics textbooks. It is intended for use in conjunction with any college level text. The booklet consists of an introduction, three content oriented chapters, and four appendices devoted to computer programming…
ERIC Educational Resources Information Center
Beller, Charley
2013-01-01
The study of definite descriptions has been a central part of research in linguistics and philosophy of language since Russell's seminal work "On Denoting" (Russell 1905). In that work Russell quickly dispatches analyses of denoting expressions with forms like "no man," "some man," "a man," and "every…
Effects of Perfluorooctane Sulfonate on Carassius aurats and Kinetics Models
Zhao-Xiang Han; Chun-Xia Lv; Zeng-ren Zheng
2009-01-01
This study investigated the effects of perfluorooctane sulfonate (PFOS) exposure for varying durations and at multiple concentrations to Carassius aurats on tissues and organs (plasma, liver, kidney, muscle, and brain) and reproductive hormone (plasma testosterone, 11-ketotestoterone, 17?-estradiol) and cell performance (membrane fluidity and potential), as well as kinetics models. The results showed that plasma PFOS concentrations were higher than those
NSDL National Science Digital Library
This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. One third of modern semiconductor process steps and a variety of other applications employ plasma technology. RF energy is commonly used to generate and maintain a plasma which accelerates chemical processes or provides other desired outcomes such as light emission. This module is the first in a series that builds a knowledge foundation for understanding plasma technology and RF energy. Concepts and principles covered include particle behavior under plasma conditions, changes in electromagnetic wave forms, and related variables that affect RF/plasma applications.
Excitation equilibria in plasmas; a classification
J. A. M. van der Mullen
1990-01-01
This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi
Zhehui Wang; Vladimir I. Pariev; Cris W. Barnes; Daniel C. Barnes
2002-03-07
A new kind of dynamo utilizing flowing laboratory plasmas has been identified. Conversion of plasma kinetic energy to magnetic energy is verified numerically by kinematic dynamo simulations for magnetic Reynolds numbers above 210. As opposed to intrinsically-turbulent liquid-sodium dynamos, the proposed plasma dynamos correspond to laminar flow topology. Modest plasma parameters, 1-20 eV temperatures, 10^{19}-10^{20} m^{-3} densities in 0.3-1.0 m scale-lengths driven by velocities on the order of the Alfven Critical Ionization Velocity (CIV), self-consistently satisfy the conditions needed for the magnetic field amplication. Growth rates for the plasma dynamos are obtained numerically with different geometry and magnetic Reynolds numbers. Magnetic-field-free coaxial plasma guns can be used to sustain the plasma flow and the dynamo.
Wang, Z; Barnes, C W; Barnes, D C; Wang, Zhehui; Pariev, Vladimir I.; Barnes, Cris W.; Barnes, Daniel C.
2002-01-01
A new kind of dynamo utilizing flowing laboratory plasmas has been identified. Conversion of plasma kinetic energy to magnetic energy is verified numerically by kinematic dynamo simulations for magnetic Reynolds numbers above 210. As opposed to intrinsically-turbulent liquid-sodium dynamos, the proposed plasma dynamos correspond to laminar flow topology. Modest plasma parameters, 1-20 eV temperatures, 10^{19}-10^{20} m^{-3} densities in 0.3-1.0 m scale-lengths driven by velocities on the order of the Alfven Critical Ionization Velocity (CIV), self-consistently satisfy the conditions needed for the magnetic field amplication. Growth rates for the plasma dynamos are obtained numerically with different geometry and magnetic Reynolds numbers. Magnetic-field-free coaxial plasma guns can be used to sustain the plasma flow and the dynamo.
NASA Astrophysics Data System (ADS)
Bénisti, Didier; Yampolsky, Nikolai A.; Fisch, Nathaniel J.
2012-01-01
In this paper, we compare two recent models [N. A. Yampolsky and N. J. Fisch, Phys. Plasmas 16, 072104 (2009); D. Bénisti, D. J. Strozzi, L. Gremillet, and O. Morice, Phys. Rev. Lett. 103, 155002 (2009)] introduced to predict the nonlinear growth of stimulated Raman scattering in the kinetic regime, and providing moreover a nonlinear description of the collisionless, Landau-like, damping rate of the driven electron plasma wave. We first recall the general theoretical framework common to these two models, based on the derivation of the imaginary part of the electron susceptibility, ?i, and then discuss in detail why the two approaches differ. By comparing the theoretical predictions for ?i to those derived from test particle or Vlasov simulations, we moreover discuss the range of validity of the two models.
Numerical study of a dust-contaminated electron plasma
NASA Astrophysics Data System (ADS)
Maero, Giancarlo; Romé, Massimiliano; Lepreti, Fabio; Cavenago, Marco
2014-10-01
The collective behaviour of dusty plasmas is heavily affected by the presence of a small fraction of micrometric or sub-micrometric dust particles which collect a large surface charge. While dusty plasmas under study are usually quasi-neutral, we propose here an investigation on a magnetized nonneutral plasma (a situation found for example in Penning traps) where a conventional plasma with a single sign of charge (e.g. electrons) is contaminated by a dust population. We simulate the two-dimensional dynamics of such a plasma in the plane orthogonal to a homogeneous magnetic field with a tailored Particle-In-Cell code implementing a mass-less fluid (drift-Poisson) approximation for electrons and a kinetic description for the dust component, including gravity effects. Simulations with a range of initial conditions are performed to observe the influence of dust on the diocotron instability developing in the electron plasma. The early stage of the growth of diocotron modes is analyzed by Fourier decomposition. The fully non-linear evolution is studied by means of a statistical analysis of probability density functions and flatness of spatial vorticity increments in order to characterize the intermittency properties of the turbulence. Contribution to the Topical Issue "Theory and Applications of the Vlasov Equation", edited by Francesco Pegoraro, Francesco Califano, Giovanni Manfredi and Philip J. Morrison.
Turbulence in the solar wind: Kinetic effects
NASA Technical Reports Server (NTRS)
Goldstein, M. L.
1995-01-01
Although a casual look at the fluctuating magnetic and velocity fields in the solar wind may be reminiscent of a chaotic and disordered flow, there is, nonetheless. considerable organization and structure in the temporal and spatial evolution of those fluctuations. Much of that evolution is controlled by processes operating on rather large scales for example, in the inner heliosphere, the fluctuations in magnetic and velocity are highly correlated in the sense of outward propagating Alfven waves. This correlation can be destroyed both in time and distance by the velocity gradients present between fast and slow streams and by other nonlinear processes which stir the medium, producing a turbulent cascade of energy from large to small scales. Many aspects of this turbulent evolution can be described using fluid models; however, at some scale the fluid approximation breaks down and a more detailed paradigm is necessary. The breakdown is evident in the power spectrum of magnetic fluctuations at scales approaching the wavelength of ion cyclotron waves. At those scales, as evident in Mariner 10 and other magnetometer data, the spectrum bends over and the fluctuations damp, possibly heating the ambient plasma. Some evidence for heating of the solar wind is present in the Voyager data. Fluid models can be modified to some extent to incorporate aspects of a kinetic treatment. This is done by modifying the dissipation terms in the fluid equations and by including extra terms, such as the Hall term. As the scale lengths of phenomena shrink further and approach the spatial and temporal scales characteristic of electron phenomena, the fluid description must be abandoned altogether and a fully kinetic treatment is required. One example is the generation of Langmuir solitons produced by the electron beams that generate type 3 solar radio bursts.
Kinetic Theory and Fluid Dynamics
Yoshio Sone
2002-01-01
This monograph gives a comprehensive description of the relationship and connections between kinetic theory and fluid dynamics, mainly for a time-independent problem in a general domain. Ambiguities in this relationship are clarified, and the incompleteness of classical fluid dynamics in describing the behavior of a gas in the continuum limit---recently reported as the ghost effect---is also discussed. The approach used
Neutrino plasma coupling in dense astrophysical plasmas
NASA Astrophysics Data System (ADS)
Bingham, R.; Silva, L. O.; Mendonça, J. T.; Shukla, P. K.; Mori, W. B.; Serbeto, A.
2004-12-01
There is considerable interest in the propagation dynamics of intense neutrino beams in a background dispersive medium such as dense plasmas, particularly in the search for a mechanism to explain the dynamics of type II supernovae. Neutrino interactions with matter are usually considered as single particle interactions. All the single particle mechanisms describing the dynamical properties of neutrinos in matter are analogous with the processes involving single electron interactions with a medium such as Compton scattering, Cerenkov radiation, etc. However, it is well known that beams of electrons moving through a plasma give rise to a new class of processes known as collective interactions, such as two stream instabilities, which result in either the absorption or generation of plasma waves. Employing the relativistic kinetic equations for neutrinos interacting with dense plasmas via the weak force, we explore collective plasma streaming instabilities driven by neutrino beams. We examine the anomalous transfer between neutrinos and dense plasma via excitation of electron plasma waves. The nonlinear coupling between an intense neutrino beam and a plasma reveals the presence of two regimes, a hydrodynamic regime and a kinetic regime. The latter is responsible for Landau damping or growth of electron plasma waves. In dense fusion stellar plasmas neutrino Landau damping can play a significant role as an additional stellar plasma cooling process. Another interesting result is an asymmetry in the momentum balance imported by the neutrinos to the core of the exploding star due to symmetry breaking by the collapsed star's magnetic fields. This results in a directed velocity of the resulting neutron star or pulsar, explaining the so called 'birth' velocity.
Investigation of Cr etch kinetics
Banqiu Wu
2003-01-01
Studies on Cr etch and its kinetics were carried out using a 50KeV photomask e-beam writing system, an ICP plasma etcher, chemically amplified resist (CAR), and a scanning electron microscope (SEM) metrology tool. A Cr etch rate equation was developed, showing good agreement with experimental data. Both the theoretical rate equation and experimental results showed that the main Cr etch
Elmogy, Mohamed; Bassal, Taha T M; Yousef, Hesham A; Dorrah, Moataza A; Mohamed, Amr A; Duvic, Bernard
2015-01-01
A protein, designated as Sgl, showing a muramidase lytic activity to the cell wall of the Gram-positive bacterium Micrococcus lysodeikticus was isolated for the first time from plasma of Escherichia coli-immunized fifth instar Schistocerca gregaria. The isolated Sgl was detected as a single protein band, on both native- and SDS-PAGE, has a molecular weight of ?15.7?kDa and an isoelectric point (pI) of ca 9.3 and its antiserum has specifically recognized its isolated form. Fifty-nine percentage of Sgl lytic activity was recovered in the isolated fractions and yielded ca 126-fold increase in specific activity than that of the crude. The partial N-terminal amino acid sequence of the Sgl has 55 and 40% maximum identity with Bombyx mori and Gallus gallus c-type lysozymes, respectively. The antibacterial activity against the Gram-positive and the Gram-negative bacteria were comparatively stronger than that of the hen egg white lysozyme (HEWL). The detected Sgl poration to the inner membrane that reach a maximum ability after 3?h was suggested to operate as a nonenzymatic mechanism for Gram-negative bacterial cell lysis, as tested in a permease-deficient E. coli, ML-35 strain. Sgl showed a maximal muramidase activity at pH 6.2, 30-50°C, and 0.05?M Ca(2+) or Mg(2+); and has a Km of 0.5??g/ml and a Vmax of 0.518 with M. lysodeikticus as a substrate. The Sgl displayed a chitinase activity against chitin with a Km of 0.93?mg/ml and a Vmax of 1.63. PMID:25972507
Resistive ballooning modes in an axisymmetric toroidal plasma with long mean-free path
Connor, J.W.; Chen, L.
1984-08-01
Tokamak devices normally operate at such high temperatures that the resistive fluid description is inappropriate. In particular, the collision frequency may be low enough for trapped particles to exist. However, on account of the high conductivity of such plasmas, one can identify two separate scale lengths when discussing resistive ballooning modes. By describing plasma motion on one of these, the connection length, in terms of kinetic theory the dynamics of trapped particles can be incorporated. On the resistive scale length, this leads to a description in terms of modified fluid equations in which trapped particle effects appear. The resulting equations are analyzed and the presence of trapped particles is found to modify the stability properties qualitatively.
NASA Astrophysics Data System (ADS)
Shay, M. A.
2013-12-01
Asymmetric magnetic reconnection has become the focus of intense study in recent years due to its applicability to the dayside magnetosphere, the solar wind and corona, turbulent systems in general, and laboratory plasmas. The study of this asymmetric reconnection is particularly timely owing to the launch of the Magnetospheric Multiscale Mission (MMS) next year, which will focus on dayside reconnection in the first phase of its mission. To put these observations in context, it is important to understand how asymmetric magnetic reconnection will warp diffusion region properties at both the ion and electron kinetic scales. Multiple case studies using both simulations and observations have shown that the Hall diffusion region structures are substantially modified during asymmetric reconnection, with the quadrupolar Hall magnetic field becoming bipolar, and the bipolar Hall electric field becoming unipolar. After reviewing the basic properties of the diffusion region during asymmetric reconnection, we will present results from a systematic kinetic-PIC simulation study of a wide range of asymmetric inflow conditions. The separation of the stagnation point and the x-line appears to play a primary role in the warping of kinetic signatures of the diffusion region and also gives rise to purely kinetic structures not present in a fluid description of reconnection. Signatures which may aid the observational search for the electron and ion diffusion regions will be discussed.
How is the Monoclonal Antibodies Kinetic Affected by Changes of Their Physical Parameters?
Delgado-Correal, Camilo; Lizarazo-Pérez, Heidy Alexandra
2010-01-01
The study of monoclonal antibodies (MAb) is a field of great interest to science medicine, for example, anti-TNF agents (infliximab and adalimumab) represent an important tool for the management of autoimmune and inflammatory disorders. In this work we focus on the physical description of the transport kinetics of MAb in a fluid with laminar flow and parabolic profile. To simulate the kinetics of the MAb, standard equations were solved numerically (using The Verlet algorithm) to calculate the motion of a particle with a spherically symmetric inside of parabolic laminar flow, in order to find the time evolution of the antibody velocity in blood plasma in function of the increase of the radius, mass and density of the MAb, and the fluid pressure in blood vessels. In the case of we fixed the value of the antibody density, their kinetics increased when the pressure in the vessels increased. When we fixed the pressure in the vessels we found: if we reduce the antibody radius their kinetics increased, and when we i...
NSDL National Science Digital Library
Wolfgang Christian
This page contains two Physlets that are able to share data using their common superclass, SApplet. The Molecular Physlet is able to tag a particle as a data source. In particular, any tagged particle can deliver x, y, vx, and vy values to a data listener. This script tags two particles and assigns these data sources to two different series in the DataGraph Physlet. The connection can show any analytic function of the position and velocity components including the particle speed or kinetic energy.
NASA Astrophysics Data System (ADS)
Marmolino, Ciro
2011-10-01
The paper describes the occurrence of stochastic heating of dust particles in dusty plasmas as an energy instability due to the correlations between dust grain charge and electric field fluctuations. The possibility that the mean energy ("temperature") of dust particles can grow in time has been found both from the self-consistent kinetic description of dusty plasmas taking into account charge fluctuations [U. de Angelis, A. V. Ivlev, V. N. Tsytovich, and G. E. Morfill, Phys. Plasmas 12(5), 052301 (2005)] and from a Fokker-Planck approach to systems with variable charge [A. V. Ivlev, S. K. Zhdanov, B. A. Klumov, and G. E. Morfill, Phys. Plasmas 12(9), 092104 (2005)]. Here, a different derivation is given by using the mathematical techniques of the so called multiplicative stochastic differential equations. Both cases of "fast" and "slow" fluctuations are discussed.
Kinetics of methylprednisolone and its hemisuccinate ester.
Derendorf, H; Möllmann, H; Rohdewald, P; Rehder, J; Schmidt, E W
1985-05-01
Methylprednisolone in the form of its hemisuccinate ester was injected intravenously in doses of 10 mg/kg and 63.1 mg. Plasma levels of methylprednisolone and of the ester were measured and their kinetics were calculated. Results indicate dose dependency in the kinetics of both. About 10% of the dose was excreted unchanged as hemisuccinate in the urine, indicating incomplete conversion of the prodrug. When methylprednisolone (80 mg) was also taken by mouth, the relative bioavailability of the tablets was 99%. Saliva levels of methylprednisolone were low but paralleled plasma levels in the postdistribution phase. No methylprednisolone hemisuccinate was found in saliva. PMID:3886255
Complex plasmas: I. complex plasmas as unusual state of matter
V. N. Tsytovich; G. E. Morfill; H. Thomas
2002-01-01
This paper opens a series of review papers devoted to the physics of the so-called complex plasmas. The review contains a\\u000a description of new physical phenomena met in dusty plasmas and complex plasmas. The term complex plasma is used for a state\\u000a where some components (dust) are in crystal or liquid state, while the others (electron, ions, and neutral atoms)
BOOK REVIEW: Introduction to Dusty Plasma Physics
P. K. Shukla; A. A. Mamun
2002-01-01
The book Introduction to Plasma Physics by Shukla and Mamun deals with various aspects of collective processes in dusty plasmas. The first introductory chapters review dust charging and the forces on dust grains in the plasma. The next two chapters give an elaborate description of the various waves and instabilities present in plasmas. In our opinion this makes the book
NASA Astrophysics Data System (ADS)
Kelly, A. J.; Jahn, R. G.; Choueiri, E. Y.
1990-07-01
The dominant unstable electrostatic wave modes of an electromagnetically accelerated plasma are investigated. The study is the first part of a three-phase program aimed at characterizing the current-driven turbulent dissipation degrading the efficiency of Lorentz force plasma accelerators such as the MPD thruster. The analysis uses a kinetic theory that includes magnetic and thermal effects as well as those of an electron current transverse to the magnetic field and collisions, thus combining all the features of previous models. Analytical and numerical solutions allow a detailed description of threshold criteria, finite growth behavior, destabilization mechanisms and maximized-growth characteristics of the dominant unstable modes. The lower hybrid current-driven instability is implicated as dominant and was found to preserve its character in the collisional plasma regime.
NASA Technical Reports Server (NTRS)
Kelly, A. J.; Jahn, R. G.; Choueiri, E. Y.
1990-01-01
The dominant unstable electrostatic wave modes of an electromagnetically accelerated plasma are investigated. The study is the first part of a three-phase program aimed at characterizing the current-driven turbulent dissipation degrading the efficiency of Lorentz force plasma accelerators such as the MPD thruster. The analysis uses a kinetic theory that includes magnetic and thermal effects as well as those of an electron current transverse to the magnetic field and collisions, thus combining all the features of previous models. Analytical and numerical solutions allow a detailed description of threshold criteria, finite growth behavior, destabilization mechanisms and maximized-growth characteristics of the dominant unstable modes. The lower hybrid current-driven instability is implicated as dominant and was found to preserve its character in the collisional plasma regime.
Marian Smoluchowski
p 2 + m2. The 3D generalization of the Langevin description (3) is obvious, however in contrast to the Newtonian case it results with the set of three coupled equations with additive indepen- dent noises. The second remark concerns the specific re- quirements of the special relativity theory. Note that the Gibbs-Boltzmann equilibrium distribution is established in the distinguished resting
Waves and Instabilities in Magnetized Dusty Plasmas
Padma K. Shukla
1998-01-01
The status of waves and instabilities in magnetized dusty plasmas is summarized. The effects of an external magnetic field on low-frequency electrostatic and electromagnetic waves in dusty plasmas are discussed. The kinetic and hydrodynamic instabilities are shown to excite magnetized dusty plasma waves. The presence of the latter can give rise to an oscillatory wake-potential which can be responsible for
Waves and Instabilities in Magnetized Dusty Plasmas
Padma K. Shukla
1999-01-01
The status of waves and instabilities in magnetized dusty plasmas is summarized. The effects of an external magnetic field on low-frequency electrostatic and electromagnetic waves in dusty plasmas are discussed. The kinetic and hydrodynamic instabilities are shown to excite magnetized dusty plasma waves. The presence of the latter can give rise to an oscillatory wake-potential which can be responsible for
ON THE LANDAU APPROXIMATION IN PLASMA PHYSICS
Villani, CÃ©dric
ON THE LANDAU APPROXIMATION IN PLASMA PHYSICS R. ALEXANDRE AND C. VILLANI Abstract. This paper of his important works in plasma physics, established the kinetic equation which is now called after him interacting through binary collisions. Since then, this equation has been widely in use in plasma physics, see
Langdon, A.B.
1985-03-03
Implicit time integration methods have been used extensively in numerical modelling of slowly varying phenomena in systems that also support rapid variation. Examples include diffusion, hydrodynamics and reaction kinetics. This article discussed implementation of implicit time integration in plasma codes of the ''particle-in-cell'' family, and the benefits to be gained.
Model of the kinetic cooling of carbon dioxide gas
A. N. Vargin; V. V. Gogokhiia; V. K. Koniukhov; A. I. Lukovnikov
1978-01-01
Kinetic equations of vibrational relaxation in polyatomic gases are used in a quantitative description of kinetic (laser) cooling in carbon dioxide. At a temperature of 300 K, the vibrational relaxation of an antisymmetric mode is accompanied by the exchange of the vibrational energy of the antisymmetric mode into three quanta of a combined deformation and symmetric mode. Initial conditions corresponded
Kinetic Theory of Traffic Flows E. Ben-Naim1
Ben-Naim, Eli
Traffic flows are strongly interacting many-body systems. Therefore, theoret- ical techniques such as kinetic theory and hydrodynamics are useful in de- scribing the rich phenomenology of traffic flows which modeled within macroscopic descriptions such as hydrodynamics and kinetic theory [15] or microscopic
NASA Technical Reports Server (NTRS)
Gliese, U.; Avanov, L. A.; Barrie, A. C.; Kujawski, J. T.; Mariano, A. J.; Tucker, C. J.; Chornay, D. J.; Cao, N. T.; Gershman, D. J.; Dorelli, J. C.; Zeuch, M. A.; Pollock, C. J.; Jacques, A. D.
2015-01-01
The Fast Plasma Investigation (FPI) on NASAs Magnetospheric MultiScale (MMS) mission employs 16 Dual Electron Spectrometers (DESs) and 16 Dual Ion Spectrometers (DISs) with 4 of each type on each of 4 spacecraft to enable fast (30 ms for electrons; 150 ms for ions) and spatially differentiated measurements of the full 3D particle velocity distributions. This approach presents a new and challenging aspect to the calibration and operation of these instruments on ground and in flight. The response uniformity, the reliability of their calibration and the approach to handling any temporal evolution of these calibrated characteristics all assume enhanced importance in this application, where we attempt to understand the meaning of particle distributions within the ion and electron diffusion regions of magnetically reconnecting plasmas. Traditionally, the micro-channel plate (MCP) based detection systems for electrostatic particle spectrometers have been calibrated using the plateau curve technique. In this, a fixed detection threshold is set. The detection system count rate is then measured as a function of MCP voltage to determine the MCP voltage that ensures the count rate has reached a constant value independent of further variation in the MCP voltage. This is achieved when most of the MCP pulse height distribution (PHD) is located at higher values (larger pulses) than the detection system discrimination threshold. This method is adequate in single-channel detection systems and in multi-channel detection systems with very low crosstalk between channels. However, in dense multi-channel systems, it can be inadequate. Furthermore, it fails to fully describe the behavior of the detection system and individually characterize each of its fundamental parameters. To improve this situation, we have developed a detailed phenomenological description of the detection system, its behavior and its signal, crosstalk and noise sources. Based on this, we have devised a new detection system calibration method that enables accurate and repeatable measurement and calibration of MCP gain, MCP efficiency, signal loss due to variation in gain and efficiency, crosstalk from effects both above and below the MCP, noise margin, and stability margin in one single measurement. More precise calibration is highly desirable as the instruments will produce higher quality raw data that will require less post-acquisition data correction using results from in-flight pitch angle distribution measurements and ground calibration measurements. The detection system description and the fundamental concepts of this new calibration method, named threshold scan, will be presented. It will be shown how to derive all the individual detection system parameters and how to choose the optimum detection system operating point. This new method has been successfully applied to achieve a highly accurate calibration of the DESs and DISs of the MMS mission. The practical application of the method will be presented together with the achieved calibration results and their significance. Finally, it will be shown that, with further detailed modeling, this method can be extended for use in flight to achieve and maintain a highly accurate detection system calibration across a large number of instruments during the mission.
Simulation of Electron Kinetics in Gas Discharges
Kaganovich, Igor
discharges · Examples of simulations using CFD-ACE+ · Inductively Coupled Plasmas · Capacitively CoupledP-8244-1/1 Simulation of Electron Kinetics in Gas Discharges by Vladimir Kolobov and Robert of rare gases · Ionization Waves (Striations) in rare gases · Simulations using UFS collisionless effects
NASA Astrophysics Data System (ADS)
Chibisov, D. V.; Mikhailenko, V. S.; Stepanov, K. N.
2011-10-01
An extension of hydrodynamic D'Angelo mode of inhomogeneous sheared plasma flow along the magnetic field into the short wavelength range, where the hydrodynamic treatment is not valid, has been considered. We find that D'Angelo mode in this wavelength range is excited by inverse ion Landau damping and is a shear flow driven ion-kinetic mode.
Fluid Complex Plasmas - Studies at the Particle Level
Ivlev, A. V.; Morfill, G. E.; Nosenko, V.; Pompl, R.; Rubin-Zuzic, M.; Thomas, H. M. [Max Planck Institute for Extraterrestrial Physics, 85741 Garching (Germany)
2008-02-21
Complex plasmas are ideal laboratory systems to investigate kinetics of strongly coupled many-particle ensembles. In contrast to colloidal suspensions, the particle dynamics in complex plasmas is virtually undamped. This makes complex plasmas particularly suited to study kinetics of fluids, by observing fully resolved motion of individual particles. In this paper we focus on three major experimental highlights characterizing kinetics of fluid plasmas--laminar shear flows, onset and development of hydrodynamic instabilities, and heterogeneous nucleation in supercooled fluids. Analysis of elementary processes observed in these experiments provides important insights into fundamental generic processes governing fluid behavior, demonstrating significant interdisciplinary potential of the complex plasma research.
Investigation of Cr etch kinetics
NASA Astrophysics Data System (ADS)
Wu, Banqiu
2003-12-01
Studies on Cr etch and its kinetics were carried out using a 50KeV photomask e-beam writing system, an ICP plasma etcher, chemically amplified resist (CAR), and a scanning electron microscope (SEM) metrology tool. A Cr etch rate equation was developed, showing good agreement with experimental data. Both the theoretical rate equation and experimental results showed that the main Cr etch rate effect parameters were oxygen mass flow rate, oxygen partial pressure, and ICP power. It was found that pressure plays a very important role in critical dimension (CD) uniformity etch contribution, loading effects, isolated/dense (I/D) etch CD bias, and etch CD movement. Etch kinetic information was found to be very helpful for improving CD uniformity, reducing pattern (local loading) effects, and controlling CD movement at the etch step. Some obsolete-pattern photomasks were used in the kinetic study. The main advantages of using obsolete photomasks include reducing resist effects on Cr etch rate investigation, obtaining much more etch kinetics data, and significantly lowering process development costs normally incurred from lithography tool time and raw photomask material consumption.
Effect of plasma surface interactions on PLT plasma parameters
Meservey, E.B.; Arunasalam, V.; Barnes, C.
1980-07-01
This paper gives a brief description of the geometry and parameters of the PLT tokamak, reviews some of the last four years' results that are particularly relevant to plasma-boundary interactions, and then concentrates on two specific problems.
Kinetic activation-relaxation technique.
Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand
2011-10-01
We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon). PMID:22181304
Aniostropic kinetic dissipation in collisionless turbulent plasmas.
NASA Astrophysics Data System (ADS)
Parashar, T.; Shay, M.; Cassak, P.; Matthaeus, W.; Servidio, S.
2008-12-01
The nature of the collisionless dissipation at small scales in solar wind turbulence is a problem of critical importance. To gain some insight into the nature of the dissipation, we simulate the Orszag-Tang vortex using collisionless hybrid simulations. In magnetohydrodynamics this configuration leads rapidly to broadband turbulence. At small scales, differences from magnetohydrodynamics arise, as energy dissipates into heat almost exclusively through the magnetic field. A key result is that protons are heated preferentially in the plane perpendicular to the mean magnetic field, creating a proton temperature anisotropy as is observed in the corona and solar wind. In order to gain insight into the heating mechanism, the scaling properties of the dissipation are examined, as well as length and time spectra.
Kinetic Theory and Hydrodynamics for a Low Density Gas
James W. Dufty
2001-09-12
Many features of real granular fluids under rapid flow are exhibited as well by a system of smooth hard spheres with inelastic collisions. For such a system, it is tempting to apply standard methods of kinetic theory and hydrodynamics to calculate properties of interest. The domain of validity for such methods is a priori uncertain due to the inelasticity, but recent systematic studies continue to support the utility of kinetic theory and hydrodynamics as both qualitative and quantitative descriptions for many physical states. The basis for kinetic theory and hydrodynamic descriptions is discussed briefly for the special case of a low density gas.
NASA Astrophysics Data System (ADS)
May, P. W.; Harvey, J. N.; Allan, N. L.; Richley, J. C.; Mankelevich, Yu. A.
2010-12-01
A one-dimensional kinetic Monte Carlo (KMC) model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model considers adsorption, etching/desorption, lattice incorporation and surface migration but not defect formation or renucleation processes. Two methods have been devised for estimation of the gas phase concentrations of species at the growing diamond surface, and are used to determine adsorption rates for C1Hx hydrocarbons for the different conditions. The rate of migration of adsorbed carbon species is governed by the availability of neighboring radical sites, which, in turn, depend upon the rates of H abstraction and of surface-radical migration. The KMC model predicts growth rates and surface roughness for each of diamond types consistent with experiment. In the absence of defect formation and renucleation the average surface diffusion length, ?, is a key parameter controlling surface morphology. When ? <2, surface migration is limited by the lack of availability of surface radical sites, and the migrating surface species simply hop back and forth between two adjacent sites but do not travel far beyond their initial adsorption site. Thus, Eley-Rideal processes dominate the growth, leading to the rough surfaces seen in NCD and UNCD. The maximum or "intrinsic" surface roughness occurs for nominally zero-migration conditions (? =0) with an rms value of approximately five carbon atoms. Conversely, when migration occurs over greater distances (? >2), Langmuir-Hinshelwood processes dominate the growth producing the smoother surfaces of MCD and SCD. By extrapolation, we predict that atomically smooth surfaces over large areas should occur once migrating species can travel approximately five sites (? ˜5). ?-scission processes are found to be unimportant for MCD and SCD growth conditions, but can remove up to 5% of the adsorbing carbon for NCD and UNCD growth. C1Hx insertion reactions also contribute <1% to the growth for nearly all conditions, while C2Hx (x <2) insertion reactions are negligible due their very low concentrations at the surface. Finally, the predictions for growth rate and morphology for UNCD deposition in a microwave system were found to be anomalous compared to those for all the other growth conditions, suggesting that carbonaceous particulates created in these plasmas may significantly affect the gas chemistry.
Vlasov versus reduced kinetic theories for helically symmetric equilibria
Tasso, H. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, D-85748 Garching (Germany); Throumoulopoulos, G. N. [University of Ioannina, Association Euratom-Hellenic Republic, Section of Theoretical Physics, GR 451 10 Ioannina (Greece)
2013-04-15
A new constant of motion for helically symmetric equilibria in the vicinity of the magnetic axis is obtained in the framework of Vlasov theory. In view of this constant of motion the Vlasov theory is compared with drift kinetic and gyrokinetic theories near axis. It turns out that as in the case of axisymmetric equilibria [H. Tasso and G. N. Throumoulopoulos, Phys. Plasmas 18, 064507 (2011)] the Vlasov current density thereon can differ appreciably from the drift kinetic and gyrokinetic current densities. This indicates some limitation on the implications of reduced kinetic theories, in particular, as concerns the physics of energetic particles in the central region of magnetically confined plasmas.
NASA Astrophysics Data System (ADS)
Pancyk, T.; Rudzinski, W.
2003-11-01
All adsorption systems which have to deal with technology and environment are systems which are not in equilibrium. They are only on their way to achieving a certain adsorption equilibrium. Therefore, knowledge of the time evolution of adsorption systems should be of fundamental importance. However, the overwhelming majority of the published papers report on experimental and theoretical studies of adsorption equilibria. This is probably why the theories of adsorption equilibria are at present much more advanced than the theories of time evolution of non-equilibrium adsorption systems. The theories of the kinetics of gas adsorption/ desorption on/from flat solid surfaces provide a very impressive illustration. On both the experimental and theoretical side, one finds a level far behind that characterizing current studies of adsorption equilibria. One can still observe controversies concerning the fundamentals of adsorption/desorption kinetics. The present review reports on the most recent achievements in the theoretical description of both isothermal adsorption kinetics and kinetics of thermodesorption, achieved by applying the Statistical Rate Theory.
Bumetanide kinetics in renal failure
Pentikaeinen, P.J.P.; Pasternack, A.; Lampainen, E.; Neuvonen, P.J.; Penttilae, A.
1985-05-01
To study the effects of renal failure on bumetanide kinetics, the authors administered single intravenous doses of 1.0 mg/3.08 microCi /sup 14/C-bumetanide to six healthy subjects and 22 patients with variable degrees of renal failure. The kinetics of /sup 14/C-bumetanide and total /sup 14/C were adequately described by a two-compartment open model in the control subjects and in the patients. The volume of the central compartment and the distribution t1/2 were of the same order in both groups, whereas the mean (+/- SE) volume at steady state was larger (22.1 +/- 1.6 and 16.9 +/- 1.0 L) and the elimination t1/2 was longer (1.9 +/- 0.2 and 1.4 +/- 0.1 hours) in patients with renal failure than in healthy controls. Bumetanide renal clearance was lower (10 +/- 3 and 90 +/- 13 ml/min) in patients than in subjects and correlated with creatinine clearance (r = 0.784) and log serum creatinine level (r = -0.843), whereas nonrenal clearance was significantly higher in the patients (153 +/- /sup 14/ and 99 +/- 6 ml/min). Bumetanide total plasma clearance did not significantly change. The non-protein-bound, free fraction of bumetanide was higher in patients and correlated with plasma albumin levels (r = -0.777). The kinetics of total /sup 14/C showed similar but greater changes than those of 14C-bumetanide. Thus the most important changes in bumetanide kinetics in patients with renal failure are low renal clearance and a high free fraction, with a consequent increase in nonrenal clearance, volume of distribution, and elimination t1/2.
Kinetic Modeling of Microbiological Processes
Liu, Chongxuan; Fang, Yilin
2012-09-17
Kinetic description of microbiological processes is vital for the design and control of microbe-based biotechnologies such as waste water treatment, petroleum oil recovery, and contaminant attenuation and remediation. Various models have been proposed to describe microbiological processes. This editorial article discusses the advantages and limiation of these modeling approaches in cluding tranditional, Monod-type models and derivatives, and recently developed constraint-based approaches. The article also offers the future direction of modeling researches that best suit for petroleum and environmental biotechnologies.
Plasma confinement by magnetic field with convex-concave field lines
NASA Astrophysics Data System (ADS)
Tsventoukh, Mikhail M.; Krashevskaya, Galina V.; Prishvitsyn, Alexander S.
2015-06-01
It has been found that plasma confinement by the magnetic field of alternating-sign curvature with convex–concave field lines results in a strong stabilizing action against convective (flute-interchange) perturbations. For simple combinations of axisymmetric mirrors and cusps the calculations according to the kinetic stability criterion give strongly, centrally peaked stable plasma pressure profiles instead of shallow ones. For the experimental research of this effect, a compact magnetic confinement device has been modified by adding of the external current coil to fulfil the field-line curvature requirements. The critical convectively-stable plasma pressure profiles calculation in this experimental geometry and the probe measurements of the spatial plasma distribution in the new magnetic configuration of alternating-sign curvature have been performed. The experimental results give some support for a conclusion that there is an increase in the ion saturation current at the region near the minimum of the specific volume min ?dl/B. This region corresponds to the average minimum in the second adiabatic invariant, and the kinetic description predicts the stable pressure profile peaking here due to reduction of charge separation by particle drift in alternating-sign curvature.
Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions
Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; Rinderknecht, Hans G.; Rosenberg, Michael J.; Albright, B. J.; Simakov, Andrei N.; Sio, Hong; Zylstra, Alex B.; Johnson, Maria Gatu; et al
2015-05-01
“Reduced” (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method describedmore »here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple approach will motivate continued theoretical research into the development of first-principles-based, comprehensive, self-consistent, yet useable models of kinetic multispecies ion behavior in ICF plasmas.« less
Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions
Hoffman, Nelson M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)] (ORCID:000000030178767X); Zimmerman, George B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Molvig, Kim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rinderknecht, Hans G. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Rosenberg, Michael J. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Albright, B. J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Simakov, Andrei N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sio, Hong [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)] (ORCID:000000017274236X); Zylstra, Alex B. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Johnson, Maria Gatu [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Séguin, Fredrick H. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Frenje, Johan A. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)] (ORCID:0000000168460378); Li, C. K. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Petrasso, Richard D. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)] (ORCID:0000000258834054); Higdon, David M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Srinivasan, Gowri [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Glebov, Vladimir Yu. [Univ. of Rochester, NY (United States); Stoeckl, Christian [Univ. of Rochester, NY (United States); Seka, Wolf [Univ. of Rochester, NY (United States); Sangster, T. Craig [Univ. of Rochester, NY (United States)] (ORCID:0000000340402672)
2015-05-01
“Reduced” (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method described here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple approach will motivate continued theoretical research into the development of first-principles-based, comprehensive, self-consistent, yet useable models of kinetic multispecies ion behavior in ICF plasmas.
Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions
NASA Astrophysics Data System (ADS)
Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; Rinderknecht, Hans G.; Rosenberg, Michael J.; Albright, B. J.; Simakov, Andrei N.; Sio, Hong; Zylstra, Alex B.; Gatu Johnson, Maria; Séguin, Fredrick H.; Frenje, Johan A.; Li, C. K.; Petrasso, Richard D.; Higdon, David M.; Srinivasan, Gowri; Glebov, Vladimir Yu.; Stoeckl, Christian; Seka, Wolf; Sangster, T. Craig
2015-05-01
"Reduced" (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method described here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. The transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. We expect that the success of our simple approach will motivate continued theoretical research into the development of first-principles-based, comprehensive, self-consistent, yet useable models of kinetic multispecies ion behavior in ICF plasmas.