EXPERIMENTAL CONFIRMATION OF POSITIVE-STREAMER-LIKE MECHANISM FOR NEGATIVE CORONA CURRENT PULSE RISE

Current growth waveforms corresponding to initial phases of negative c orona current pulses were measured in nitrogenous gas mixtures at pres sures of 6.67-40 kPa. The measurements showed that the steep pulse ris e is not dependent on cathode secondary emission processes for pressur es above 30 kPa. This, together with a discontinuous transition in the current waveforms observed with increasing gap voltage in N2 at press ures of 20-26.6 kPa, implies that the feedback-to-cathode Townsend ion ization mechanism was supplanted by a faster streamer-like mechanism. At pressures below 20 kPa a positive-streamer-like wave results in com plex Trichel pulse shapes with a step on the pulse leading edge and a hump on the pulse trailing part.