COMPARISON OF THEORETICAL ANALYTIC ION VELOCITY DISTRIBUTION FUNCTIONS WITH EXPERIMENTAL MEASUREMENTS.

Abstract

Analytic velocity distribution functions of ions drifting through a buffer gas under the influence of an electric field are compared with experimentally obtained measurements of velocity and energy distribution functions. Good matches are found for particular examples, but in general the analytic functions relative to the experimental functions are shifted to lower velocities when the ratio of the electric field to the neutral number density is low and to higher velocities when the ratio is high. The effect of using experimentally determined values of the drift velocity and diffusion coefficients in the analytic expressions is also investigated.