Two-region computational model for DC glow discharge plasma

Abstract

A two-region model has been developed which simplifies the computations for a DC glow discharge plasma between two parallel plates. The glow discharge is divided into a cathode sheath and a bulk plasma. An anode sheath is ignored in the computations. The bulk plasma is assumed to be quasi-neutral and supports ambipolar diffusion. To link the sheath and bulk regions, the classical ambipolar analysis is modified to include a net total current in the plasma. In the sheath region the plasma variables are determined by numerical integration of an initial-value problem by Gear's routine. The integration starts from the cathode with the total current fixed and with the cathode electric field iterated until a complete solution is found. The sheath-bulk boundary occurs at the distance from the cathode where the electron and ion densities are nearly equal; matching conditions on the plasma variables are imposed here. Illustrative results are presented for some chosen conditions, and the effect of operating variables on the pertinent plasma properties is qualitatively discussed. >