TRANSPORT PROPERTY OF ELECTRONS IN GASES UNDER ELECTRIC-FIELD .1. LATERAL DIFFUSION-COEFFICIENT

The well known formula of isotropic diffusion coefficient D//v of electrons does not give exact values of lateral diffusion coefficient D//t under an electric field. D//v implies the ensemble average of the instantaneous probability of diffusion, while D//t is obtained as the time average of diffusion flux. The cause of the discrepancy between D//v and D//t is the change of the collision frequency within respective flights of electrons due to the electric field. Problems concerning D//v and D//t are made clear from relevant quantities calculated by the analytical method and by the Monte-Carlo simulation for various model cross sections.