Negative point-plane corona in oxygen

Experimental results are presented for current pulses in a negative point-plane corona in oxygen as a function of applied voltage gas pressure and point radius. The pressure range studied was 3.34 to 16.67 kPa and point diameters of 0.14, 1, 2, 5 and 10 mm were used. Under conditions which result in a steady train of current pulses the current waveform with larger diameter points exhibits a step on the leading edge which is not seen with the smallest diameter point. Long statistical time-lags have allowed a detailed study of the 'first' pulse in the train. The first pulse is significantly different from succeeding pulses and in particular the leading-edge step is present for all points studied.