Transport Coefficients and Energy Distributions of Electrons in Gases

The steady-state energy distribution of free electrons in a gas subjected to a constant electric field has been simulated stochastically. The effects of the thermal motion of the gas molecules, inelastic collisions, and the energy dependence of the collision cross sections have been included. Under appropriate limiting conditions, the stochastically generated results reduce to the analytical results of Maxwell, Davydov, and Druyvestian. Use of this technique, along with values of cross sections reported in the literature, has made possible the calculation of the drift velocities and diffusion coefficients of electrons in helium, hydrogen, and nitrogen as a function of the ratio $\frac{E}{P}$. The calculated results agree well with experimental values given in the literature over a range of $\frac{E}{P}$ from 0.002 to 0.20 V/cm mm Hg.