Characterization of point-plane corona pulses in SF6

Abstract

The properties of streamer or electron avalanche pulses have been investigated for point-plane, and positive and negative dc corona discharges in gaseous SF6 over the pressure range of 50-500 kPa. Measurements were made of the voltage and pressure dependence of electrically detected corona pulse-height distributions, pulse shapes, and repetition rates. Positive corona pulses appear at onset as low-level electron avalanches which, at higher voltages, develop into large streamers usually followed by a burst of many smaller pulses. The burst characteristics of positive corona show a definite dependence on pressure and voltage which is evident in the pulse-height distribution data. Negative corona displays characteristics which are sensitive to cathode surface conditions. For a point electrode that is either exposed to UV radiation or has been conditioned by prior discharges, the negative corona appears predominantly in a quasiglow mode consisting of relatively low-level pulses of high repetition rate.