
%0 Journal Article
%A Skullerud, HR 
%T On the Theory of Electron Diffusion in Electrostatic Fields in Gases
%J Australian Journal of Physics
%D 1974/04/01
%V 27
%N 2
%P 195-210
%K 
%R https://doi.org/10.1071/PH740195
%U https://www.publish.csiro.au/paper/PH740195 
%X The motion of electrons in a gas in the presence of large electron density gradients has been studied theoretically, starting from the two-term expansion of the Boltzmann equation. The effects of material boundaries have not been considered. An electron swarm released as a b-function in space and with an equilibrium energy distribution is found initially to develop as a spheroid with dimensions determined by the lateral diffusion coefficient. It subsequently passes through a stage involving a slowly decaying pear-shaped deformation, before ultimately becoming an ellipsoid with dimensions determined by the longitudinal and lateral components of the diffusion tensor. Numerical values cited in the literature for the long-term deviations from the mean square widths predicted by the diffusion equation have been found to be in error by factors of 10 or more. 
