The one-particle approximation in the reflecting discharge simulation

Abstract

The method of some reflecting discharge (Penning discharge) characteristics computation, based on the one-particle approximation is proposed. This discharge is widely used in ion sources aimed at surface modification. However, only the steady state of this discharge is sufficiently described, whereas pulsed modes are preferable in many cases. In fact, the proposed method is similar to the approach used in the early times of first glow discharge investigations and crossed fields ion sources. It may be applied for the early discharge stages (the Townsend regime) description. It is somehow simpler than the diffusion-drift approximation used as a rule for the stationary state description, because plasma does not exist yet. On the other hand, one need not use most of usual diffusion-drift simplifications e.g. 1 or 2D models, uniform magnetic field etc. So the process of discharge formation may be described exactly for different kinds of Penning cells geometries and fields configurations. The discharge ignition condition for the Penning cell, analogous to the Townsend law is evaluated. It allows one to appreciate the discharge formation time as a function of cell geometric parameters, field configurations, anode voltage and Townsend’s coefficients α and γ. This time, or exactly the trajectory length during this time, plays the role of the Townsend parameter d – the distance between electrodes. The calculated values of such times show good agreement with experimental data.