Interest In Plasma Physics Research Articles

Redistribution of Stochastic Kinetic Energy in Ensembles of Non-Identical Charged Particles

The energy exchange processes are studied in the systems of non-identical interacting particles (with different sizes, masses, and charges) with the spatially inhomogeneous distribution of the stochastic kinetic energy sources. To analyze the energy balance in such systems, a theoretical model is considered. The analytical relations are presented that describe the redistribution of the stochastic kinetic energy between two charged particles. The relations proposed are verified by means of simulating numerically the problem for particles with the Coulomb interaction between them. The numerical analysis is performed of the process of the stochastic kinetic energy redistribution in the two-dimensional ensembles with the separated fractions of particles with different sizes and temperatures. The results of this work can be applied to the systems with any type of pair interaction. They can be also used for analyzing the energy exchange processes in inhomogeneous systems that are of interest in plasma physics and in physics of polymers and colloid systems.

Partition functions

Context. Hydrogen is the most abundant molecule in the Universe. Its thermodynamic quantities dominate the physical conditions in molecular clouds, protoplanetary disks, etc. It is also of high interest in plasma physics. Therefore thermodynamic data for molecular hydrogen have to be as accurate as possible in a wide temperature range.

Generalization of the perturbation theory by using a repeating equation: A case that reveals the plasma chaotic state

AbstractAmong the theoretical and experimental situations of interest in plasma physics are the waves that rise into the plasma and are strongly affected from the plasma parameters. Therefore, the development of strong relations between unperturbed and perturbed quantities is proved to exist both experimentally and theoretically. In the present paper, the mathematical solution ended in a relation between drift and perturbed velocities, which presupposes the perturbed velocity value to be very small in comparison with the drift velocity. However, the experiment has shown that the presupposition of the small value of the perturbations is not satisfied in many laboratory instances; as a result the use of the perturbation theory is limited. To surpass this difficulty, the big perturbed quantity was divided into small and equal parts, and by using the equation between unperturbed and perturbed velocities as a repeating relation, the perturbed theory may be extended and generalized beyond the small disturbances. In addition, calculations with a little change in the initial conditions were carried out, to determine when the plasma obtains chaotic behavior.

Stark spectroscopy of a probe lithium beam excited with two dye lasers as a technique to study a high-power ion-beam diode

A non-disturbing measurement of electric field distributions is a subject of special interest in plasma physics and high-voltage devices. In this paper we describe a diagnostic technique for remote sensing of electric fields via injection of a probe beam of lithium atoms and cascade excitation of resonance fluorescence with two broadband dye lasers. The fluorescence spectrum was recorded using a monochromator equipped with an optical multi-channel analyser. The magnitude of the local electric field was retrieved from the Stark-shifted components of the 3d-2p lithium spectral line. The technique was applied to measurements of the electric field in the applied-B-field high-voltage diode of the 1 TW KALIF ion-beam accelerator.

On a relativistic Fokker-Planck equation in kinetic theory

A relativistic kinetic Fokker-Planck equation that has been recently proposed in the physical literature is studied. It is shown that, in contrast to other existing relativistic models, the one considered in this paper is invariant under Lorentz transformations in the absence of friction. A similar property (invariance by Galilean transformations in the absence of friction) is verified in the non-relativistic case. In the first part of the paper some fundamental mathematical properties of the relativistic Fokker-Planck equation are established. In particular, it is proved that the model is compatible with the finite propagation speed of particles in relativity. In the second part of the paper, two non-linear relativistic mean-field models are introduced. One is obtained by coupling the relativistic Fokker-Planck equation to the Maxwell equations of electrodynamics, and is therefore of interest in plasma physics. The other mean-field model couples the Fokker-Planck dynamics to a relativistic scalar theory of gravity (the Nordström theory) and is therefore of interest in gravitational physics. In both cases the existence of steady states for all possible prescribed values of the mass is established. In the gravitational case this result is better than for the corresponding non-relativistic model, the Vlasov-Poisson-Fokker-Planck system, for which existence of steady states is known only for small mass.

Zero-dispersion limit of the short-wave–long-wave interaction equations

The purpose of this paper is to study the zero-dispersion limit of the water wave interaction equations which arise in modelling surface waves in the present of both gravity and capillary modes. This topic is also of interest in plasma physics. For the smooth solution, the limiting equation is given by the compressible Euler equation with a nonlocal pressure caused by the long wave. For weak solution, when the coupling coefficient λ is small order of ε, λ = o ( ε ) , the wave map equation is derived and the scattering sound wave is shown to satisfy a linear wave equation.

Idealized slab plasma approach for the study of warm dense matter

Recently, warm dense matter has emerged as an interdisciplinary field that draws increasing interest in plasma physics, condensed matter physics, high pressure science, astrophysics, inertial confinement fusion, as well as material science under extreme conditions. To allow the study of well-defined warm dense matter states, we introduced the concept of idealized slab plasma (ISP) that can be realized in the laboratory via (1) the isochoric heating of a solid and (2) the propagation of a shock wave in a solid. The application of this concept provides new means for probing AC conductivity, equation of state, ionization, and opacity. These approaches are presented here using results derived from numerical simulations.

Computer-aided closure of the lie algebra associated with a nonlinear partial differential equation

Algorithms have been developed in the MACSYMA language for closing the Lie algebra generated from a nonlinear partial differential equation using the method of Wahlquist and Estabrook. The method is applied to find closed form solution of a nonlinear equation of interest in plasma physics.

25. Cryopumped hydrogen cluster beam source

Summary Cluster beams are of growing interest in plasma physics for heating and fueling fusion devices. At the Institute of Nuclear Engineering of the Karlsruhe Nuclear Research Centre an injector is under construction, which aims at the production of high power beams of electrically accelerated cluster ions of hydrogen. A hydrogen cluster is a condensed aggregate of molecules held together by the van der Waals forces. A cluster beam is obtained by rapid expansion of gaseous hydrogen from a cooled nozzle into vacuum. The outstanding properties of cluster beams are their high particle flux densities, an almost uniform particle velocity, a very sharp spatial limitation and a broad distribution of the particle size. An essential part for cluster beam generation is, besides the expansion nozzle and proper stagnation conditions, an adequate pumping system for the extreme gas load which occurs in cluster beam formation. The portion of cluster beam amounts to about 10% of the entire nozzle mass flux; therefore, 10 times of the cluster beam mass flow have to be disposed of. A cluster beam of 100 A equivalent current (= 10 torr l/s−1) calls for a pumping capacity of 100 torr 1/s−1 at a pressure of about 10−4. A cryosystem using liquid helium is described which provides the necessary pumping speed by cryopumps. The same cryostat yields also a cryogenic capacity for nozzle cooling and, in the case of the cluster injector mentioned above, the pumping speed required for the ionization regime and the accelerating tube. The production of intense cluster beams, cryopumping under extremely high gas load and typical properties of the cluster beams source with integrated cryopumps are discussed.

Approximations for Collisional and Radiative Transition Rates in Atomic Hydrogen

view Abstract Citations (297) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Approximations for Collisional and Radiative Transition Rates in Atomic Hydrogen Johnson, L. C. Abstract A simple, accurate, and complete set of approximate formulae is presented for evaluating collisional and radiative transition rates for bound-bound and bound-free transitions in atomic hydrogen. The approximations are chosen in a form which facilitates computer programming and solution of nonequilibrium excitation problems of interest in plasma physics and astrophysics. Detailed comparisons are made with experimental, theoretical, and other semiempirical results. Publication: The Astrophysical Journal Pub Date: May 1972 DOI: 10.1086/151486 Bibcode: 1972ApJ...174..227J full text sources ADS |