Analysis of Non-Equilibrium Excitation in Pulsed Electric Discharges

摘要

A numerical solution of the time-dependent Boltzmann equation has been tested with model calculations. Some comparisons were made with nitrogen cross-sections. The model calculation are relatively fast and much easier to analyze. The electrons lose memory of their initial conditions for times greater than the energy exchange time. This relaxation time can vary orders of magnitude depending on the gas composition and the ratio of the applied field to the total gas density (E/N). The limits on the applicability of the local field approximation have been explored. It is found that it is a valid parameter for coefficients in the electron continuity equation provided E/N does not change within a few energy exchange times. Several attempts have been made to find a parameterization of the time-dependent transport and rate coefficients, or to formulate a hydrodynamic-like model for time-dependent fields. Previous effort to describe, for example, the ionization rate in the nonuniform field region of a discharge, have been examined for application in the time-dependent case. H The electron continuity equation only requires information on the electron density growth (or decay) constants and electron flux. The moments which are most sensitive to thils component are not usually included in models of gas discharges.