Computer simulation of rapidly developing gaseous discharges

A method is described for tracing theoretically the growth in space and time of a rapidly developing gaseous discharge between parallel-plate electrodes where the electric field is distorted by the space charge of the electrons and ions. The results obtained for a discharge in nitrogen initiated by a pulse of electrons leaving the cathode have been used to simulate streak photographs of the light output from the discharge. There is excellent agreement between the present results and the experimental streak photographs of Wagner. It is concluded that the occurrence of the anode- and cathode-directed streamers can be satisfactorily explanined in terms of the basic Townsend ionisation processes, provided that space-charge distortion of the field is allowed for correctly.