Absolute Values of the Electron Drift Velocity in Nitrogen, Helium, Neon and Argon

Abstract

The electrical shutter method for measuring electron mobility has been employed for measurements of the electron drift velocity in nitrogen, helium, neon and argon. The values obtained experimentally as a function of $\frac{X}{p}$ are compared with those computed by theoretical equations and a discrepancy is shown to exist. In every case the deviation of the experimental from the calculated curves is explained by the hypothesis that the distribution of electron velocities is such that occasional inelastic collisions occur. Under such circumstances the energy losses are greater than those calculated, and the experimental values of the electron drift velocity are thus greater than predicted by theory. It is shown, in all cases studied, that electrons of sufficient energy are present to produce the postulated excitations. Assuming such inelastic collisions, a value for the probability of excitation of electronic levels in helium, neon, and argon is calculated. The probabilities so obtained agree in order of magnitude with those given by other experiments.