Field distortion in gaseous discharges between parallel-plate electrodes

Different methods are described for evaluating the field distortion due to a radially symmetrical distribution of charges in a spark discharge between plane parallel electrodes. Poisson´s equation is solved numerically using a relaxation procedure, and the results are compared with those obtained using less accurate methods, in particular the one-dimensional form of Poisson´s equation. The application to the calculation of ionisation currents in gases between parallel-plate electrodes is discussed.