Pressure and Free Flight Time Effects on Glow Discharge Characteristics

Abstract

In this work, a model for a DC glow discharge at low pressure, used in many applications has been developed. This model allows the determination of plasma characteristics distributions in 2D geometry. The proposed theoretical model is applied to collisional argon plasma at low pressure in a reactor consisting of two plane parallel electrodes where the cathode is heated to a voltage of -250 V. The proposed code is based on solving the continuity equation coupled with Poisson's equation and electrons mean energy's equation. The particles trajectories simulation requires the knowledge of all collisional processes through their collision cross sections. The probability of collision during a free flight time can not be known without performing integrations of non-analytical cross sections. The proposed solution to this problem consists in the application of the "null collision" concept. The simulation results are shown in terms of spatial distribution of charged particles, potential, electric field, electrons energy and velocity. The study of the pressure (0.1-1Torr) and the free flight time (5.11x10 -9 to 1.46 x10 -7 s) effect, on the plasma characteristics, confirms the validity of this model