Monte Carlo simulation of electron swarm motion in SF6

Abstract

The nonequilibrium behaviour of electrons in a drift tube in SF₆ is investigated using a Monte Carlo simulation. It is shown that, in the case of a steady-state experiment, the mean properties of the electrons (drift velocity, number density, mean energy) present some strong spatial oscillations and that attachment occurs in some very localised regions of the gap. The question of the validity of the hydrodynamic description in that case is considered. In spite of these spatial oscillations of the macroscopic parameters, the first transport coefficients (deduced from the simulation of a time-of-flight experiment) seem to quickly reach their equilibrium values. Results from steady-state, pulsed Townsend and time-of-flight experiments are discussed.