Electron Diffusion in Finite Enclosures

Abstract

Starting from the two-term approximation to the Boltzmann equation, a study is made of the time dependence of the density of electrons released inside a finite enclosure containing a neutral gas. The dominant behaviour can be represented by a diffusion equation containing an effective diffusion constant which depends upon pressure and dimensions of the enclosure. In the limit of large pressure and large enclosure the usual expression of the diffusion constant is obtained. The approach to this limit dePends upon the electron-neutral interaction. The effect of various model and measured cross sections for some inert gases is discussed.