NUMERICAL SIMULATIONS OF DC GLOW-DISCHARGE USING SELF-CONSISTENT BEAM MODEL

Calculations are presented of helium dc glow discharges using a beam model, in which beam electrons represent nonequilibrium electron transport; cold electrons and ions are treated with an equilibrium continuum model. Calculated current densities ranged from 4.7 muA/(cm2.Torr2) (near the normal glow conditions) to 290 muA/(cm2. Torr2) (abnormal regime). High-density plasmas appeared in the negative glow; the peak density occurred at the position where the electric field changed from negative to positive. Calculations were also made using a continuum model with the local field approximation for electron transport: high-plasma density and electric field reversal were not predicted by the model. Calculations using the beam model show good agreement with recent experiments except at high current densities, where experiments showed complex phenomena.