Strict calculation of electron energy distribution functions in inhomogeneous plasmas

Abstract

The paper reports on strict calculations of the velocity distribution function and of related macroscopic quantities of the electrons in inhomogeneous plasmas. The kinetic studies are based on the numerical solution of the inhomogeneous, time-independent Boltzmann equation of the electrons including the action of a nonuniform electric field and of elastic and inelastic collisions of the electrons with the gas atoms in weakly ionized plasmas. In particular, the relaxation of plasma electrons in uniform electric fields, the response of the electrons to spatial disturbances of the electric field, the electron kinetic behaviour in the case of space charge field confinement by enclosing walls and the reaction of the electrons to strong fields as occurring in the region of moderate cathode falls are analysed. Especially, unexpectedly large spatial relaxation lengths and distinctly nonlocal properties of the electrons are found to be typical of the weakly ionized plasmas in the range of medium electric fields.