Theory of the density dependence of electron drift velocity in gases

We present a quantum-mechanical theory of the electron drift speed $W$ in a gas in a field at low $\frac{E}{N}$ and relatively high pressures. It is able to give a quantitative interpretation of the experimental results, as regards the dependence of $W$ on both the gas number density and the gas temperature. As an application, we make a comparison between theory and experiment in He, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, and Ar.