PREBREAKDOWN STREAMER PULSES IN LONG AIR GAPS UNDER POSITIVE DIRECT VOLTAGES

Results are presented of a systematic study of pre-breakdown streamer pulses in the DC corona discharge occurring in rod-plane gaps up to 1 m long. Pulse repetition rates, current amplitudes, and DC current com ponents have been measured as a function of atmospheric humidity. The relationship between these parameters and the voltages required for br eakdown are discussed, with particular reference to the abnormal behav iour of the latter in long gaps and at high humidities, where a change in the transition to the leader discharge is considered. Comparisons are made with earlier published work.