Some statistical measurements on Trichel pulse periods

Trichel pulse periods were measured in air using a concentric-hemispheres point/cup electrode system, as the symmetry facilitates the modelling of discharge phenomena. Several hundred pulse periods were recorded for different voltage levels and 5 pressures from 0.2 to 1.0 bar. The scatter of the pulse periods about the mean decreases quickly above the onset voltage and appears to be due to the `statistical´ delay, after the ions from the previous pulse have drifted out of the gap, until an initiating electron appears. Analysis of the variation with pressure and voltage indicates that the initiating electrons originate from electron/ion pairs caused by background radiation