Electron collision frequencies in polar gases

Abstract

The collision frequencies of thermal electrons in polar gases are investigated. A quantitative discussion is given of the approximations contained in the conventional theory and it is argued that the ‘exact elastic scattering approximation’ of Mittleman and von Holdt is not a valid description. An error in the comparison of theory and experiment is corrected and it is suggested that the discrepancies can be largely attributed to omitted terms in the assumed interaction potentials. A modified formula is presented for the drift velocity of thermal electrons moving in molecular gases under the influence of a small electric field, which takes account of the internal structure of the molecules.