Modelling of anomalous Doppler broadened lines, thermalization of electrons and the role of radicals in discharges at high E/N

Abstract

In this paper we show how Monte Carlo technique developed for swarm studies may be applied to model some real discharges or to provide data for realistic plasma models. In all cases discussed here the Monte Carlo technique without self consistent field is driven to a much greater level of complexity than usually found in swarm studies. We discuss three conceptually quite different situations that require exact modelling by Monte Carlo Simulations (MCS). The first is the case of transport in gases where degree of dissociation is large and thereby radicals formed by the discharge may affect the transport coefficients. Based on recent calculations for electron CFX radical cross sections we calculated how transport coefficients would be affected by the presence of radicals in pure CF4 and CF4/Ar mixtures covering range of abundances often found in plasma etching devices. The second case studied here is modelling of thermalization of high energy electrons in the atmospheric gases as an attempt to provide the basis for detection of very high energy cosmic particles. In that case pressure dependent emission efficiency is studied as a function of electron energy and the system is developed to an arbitrary degree of secondary electron production. Finally we give some recent advances and current status of modelling of high E/N discharges operating in Townsend's regime in hydrogen where anomalous broadening was observed and explained by fast neutral excitation in both directions along and against the acceleration due to electric field.