Introduction: Plasma Parameters and Simplest Models

Plasma is ionized gas (partially or fully). Overwhelming majority of matter in the universe is in plasma state (stars, Sun, etc.). Basic parameters of plasma state are given briefly as well as classification of plasma types: classic-quantum, ideal-nonideal, etc. Differences between plasma and neutral gas are presented. Plasma properties are determined by long distance electrostatic forces. If spatial dimensions of a system of charged particles exceed the so-called Debye radius, the system may be considered as plasma, that is, a medium with qualitatively new properties. The expressions for Debye radius for classical and quantum plasma are carried out. Basic principles of plasma description are presented. It is shown that plasma is a subject to specific electrostatic (or Langmuir) oscillations and instabilities. Simplest plasma models are given briefly: the model of “test” particle and model of two (electron and ion) fluids. As an example, Buneman instability is presented along with qualitative analysis of its complicate dispersion relation. Such analysis is typical in plasma theory. It allows to easily obtain the growth rate.

Effects of Grain Size on the Bremsstrahlung Spectrum of Electron-Dust Grain Collisions in Dusty Plasmas

The grain size effects on the bremsstrahlung emission spectrum due to nonrelativisitc electrondust grain collisions are investigated in dusty plasmas. Using the Born approximation for the initial and final states of the projectile electron, the bremsstranhlung radiation cross section is obtained as a function of the grain size, dust charge, Debye radius, collision energy, and radiation photon energy. It is found that the effects of the grain size enhance the bremsstrahlung radiation cross section, especially for soft-photon radiations. The effect of the Debye radius on the bremsstrahlung cross section is found to be increased with an increase of the magnitude of the charge number of the dust grain. In addition, the grain size effect on the bremsstrahlung spectrum is found to be more significant for highly charged dusty grains

Some transport properties in plasmas containing argon and fluorine

In this paper some results of numerical evaluation of transport coefficients in plasmas in the mixtures of argon and fluorine are presented. These transport characteristics are given in the function of the temperature for low pressures ranging from 0,1 kPa to 1,0 kPa and for low temperatures between 500 K and 5 000 K in argon plasmas with 20% and 30% of the fluorine added. It is assumed that the system is kept under constant pressure and that a corresponding state of local thermodynamical equilibrium (LTE) is attained in it. The equilibrium plasma composition, necessary for the evaluations, was determined on the ground of the Saha equations for ionization processes and the law of mass action for the thermal dissociation of F2, combined with the charge conservation relation and the assumption that the pressure remained constant in the course of temperature variations. The ionization energy lowering, required in conjunction with the Saha equations, was obtained with the aid of a modified expression for the plasma Debye radius proposed previously. A previously derived expression for the modified Debye radius, offering the possibility to treat the plasmas considered as weakly non-ideal in the whole temperature range, is used. The cut-off at the Landau length rather than of the smallest of ionic radii is introduced. This alteration in the evaluation procedure brings different considerable changes in the final numerical results for the all relevant quantities.

Kinetic Theory of Subsonic and Supersonic Transport Processes for Screened Coulomb Interactions

A statistical theory of the intercomponent transport processes is given for nonisothermal plasmas consisting of electron and ion components, when the particles interact through Coulomb collisions screened electrostatically beyond the Debye-radius. The associated collision integrals are evaluated analytically for arbitrary drift velocities of the components, and under consideration of the velocity dependence of the Coulomb logarithm. The resultant analytical relations form consistent mathematical foundations for a transport theory of systems with collisional Coulomb interactions. It is shown that different properties of the transport processes and the effective Coulomb logarithms result for subsonic and supersonic drift velocities of the components

Zur Theorie der Ohm’schen Heizung vollionisierter Plasmen

Ausgehend von einer Lösung der BOLTZMANN-Gleichung durch eine für Plasmen erweiterte 13-Momenten-Approximation werden die Gleichungen für die OHMSCHE Heizung eines vollionisierten Plasmas aufgestellt. Der Einfluß eines Magnetfeldes wird vernachlässigt. Als weitere Näherungen werden die anisotropen Anteile des Drucktensors und der Wärmestromvektor in der Orthogonalreihenentwicklung für die Wahrscheinlichkeitsdichte vernachlässigt, so daß eine lokale MAXWELL–Verteilung resultiert. Die Vernachlässigungen werden im einzelnen begründet. Die Stoßintegrale, die in den so vereinfachten Gleichungen auftreten, werden für ein beim DEBYE-Radius abgeschnittenes COULOMB-Potential berechnet. Man erhält somit ein simultanes System von Differentialgleichungen, welches für eine praktische Berechnung der OHMschen Heizung bei beliebig starken elektrischen Feldern geeignet ist.