A theoretical calculation of electron swarm properties in helium†

Electron swarm motion across uniform electric fields in gases has been calculated by employing a Monte Carlo—Boltzmann technique. The method examines the swarm properties from the initial generation of electrons at the cathode, through the non-equilibrium region, and finally through the equilibrium region to the anode, The discharge parameters which characterize the swarm motion have been calculated. These are energy distribution, electron drift velocity, electron ionization coefficients, radial and longitudinal diffusion coefficients and coefficients for the inelastic collisions. The effects of the discharge electrodes have also been examined, and the loss of electron current by ‘ back diffusion ’ has been calculated as a function of E/po, electron emission energy, and reflection coefficient. Numerical calculations have been made for swarm motion in helium gas for E/po = 10 to 50 v cm−1 torr−1 at 0°c. The discharge parameters for equilibrium conditions have been compared with the values calculated from Boltzmann's equation.