Current-density distribution on a plane cathode in DC glow and streamer corona regimes in air

The variation of current densities on a plane cathode in air has been investigated in a positive point-plane gap configurations. This work is concerned with the effects of gap spacing, point diameter and humidity variations on the current density profiles, according to the type of corona regime produced at the point anode during predischarge development. Cases are considered where the point electrode is energized by a positive DC voltage producing either a pure glow or streamers, according to given particular experimental conditions such as point-plane gap spacing, point diameter and ambient absolute humidity. The results obtained show that the current density variation for positive corona in air does not always follow Warburg´s law but depends upon the type of corona regime generated at the HV point anode. Comparisons are made with negative point-plane gaps