Simulation of electrical discharges in gases. Nonuniform electric fields

Non-equilibrium behavior of electrons and ions in gases in an electric field occurs in many situations such as in the cathode fall region of a glow discharge, asymmetrical electrodes between which the Laplacian electric field is nonuniform, in coronas and spark breakdown. This paper reviews various methods used to describe the non-equilibrium behavior of electrons and the degree of success obtained with these methods. Non-equilibrium effects in the cathode fall region of a discharge is treated separately. Mainly there are microscopic methods such as Monte Carlo simulation and Boltzmann equation analysis. Alternatively macroscopic methods such as the momentum transfer theory (or beam model) and memory factor model are available. Also, a hybrid fluid/Monte Carlo method is introduced as a new treatment of non-equilibrium behavior in high pressure and rf discharges. Future possible development in these areas are commented upon