Positive and Negative Point-to-Plane Corona in Air.

摘要

The present work has involved a careful comparison of positive and negative corona and observations at reduced pressures in the range 756 to 210 mm Hg. Oscillographic observation of corona pulses with a time resolution of the order of 1O(exp-7) second, visual and photographic observation of the corona, and current voltage measurements have thrown new light on fundamental corona processes. Some of the significant results obtained were as follows: For a polished platinum point of 0.38-mm diameter of curvature, the duration of positive pre-onset streamers and negative Trichel pulses near onset was about 0.4 microsecond; for positive breakdown streamers, 0.8 microsecond. A comparison of positive and negative current voltage characteristics showed that the intermittent Onsets were approximately equal but showed a small pressure dependent difference. Both curves showed linear 0hm's law regions, and the negative current was always the larger; these effects are due to space charge. The negative corona revealed the fluctuations and dependence on surface conditions noted by previous workers.