LONGITUDINAL DIFFUSION OF ELECTRONS IN ELECTROSTATIC FIELDS IN GASES

Expressions have been obtained for the longitudinal and lateral diffusion coefficients for electrons moving in electrostatic fields in gases, from the solution of the Boltzmann equation. Numerical results are quoted for the case of a collision frequency varying as the velocity raised to a power γ, on the assumption of no thermal motions of the gas molecules, and for the case of a constant collision cross section, with thermal motions included. The diffusion is found usually to be strongly anisotropic, in agreement with experimental measurements of Hurst and Parks in 1966 and Wagner, Davis and Hurst in 1967.