Mobility and Diffusion. I. Boltzmann Equation Treatment for Charged Particles in a Neutral Gas

Abstract

The conditions that usually prevail in drift tube experiments for the measurement of mobility and diffusion of electron and ion swarms are appropriate for the application of a linearized Boltzmann equation. Starting from such an equation, formulae for mobility and (anisotropic) diffusion coefficients are derived for the case where only elastic collisions are important. No restriction is placed on the masses of particles or on the nature of interaction potential. Results of earlier theories are shown to be special cases of the formulae obtained here. The intended application of the equations is mainly to the case of alkali metal ions in neutral rare gases, where numerical evaluation of the formulae is necessary. The m!lin features of some of the numerical procedures are discussed.