Pressure Dependence of Electron Drift Velocity in Hydrogen at 77.8°K

Our measurements show at $\frac{E}{P}<0.03\mathrm{}$ V/Torr cm a decrease of the drift velocity in hydrogen with increasing pressure (up to 50 000 Torr), which cannot be explained by an electron trapping mechanism. It is shown that this effect is in agreement with Legler's theory which takes into account multiple scattering. For $\frac{E}{P}>0.03\mathrm{}$ V/Torr cm, the observed decrease of the drift velocity can be explained by an electron trapping mechanism.