Measurement of the time-evolution of averaged impedances in a small atmospheric pressure spark-gap

The results of measurement of the time-evolution of averaged values of the resistance and inductance of a small, self-breaking atmospheric pressure spark-gap are presented. The gap lengths were varied in the range 0.4-4 mm, and the driving circuit used for the measurements was based on a 37 nF capacitor. Both the resistance and the inductance were found to diminish with time, in qualitative agreement with a radially expanding model for the spark channel.