Corona in atmospheric air between negative point and plane electrodes

The phenomena of corona between negative point and plane electrodes in atmospheric air have been found to consist of Trichel pulses above onset. Results of experimental investigations on negative point plane corona in air at atmospheric pressure for DC voltage applications are reported in this paper. The diameter of the hemispherical tip used in these investigations varied from 1.0 mm to 5.15 mm and the different materials used for the negative electrode were stainless steel, brass, copper and silver plated brass (25 /spl mu/m thickness). The gap distance range was 20 mm to 40 mm. In all these experiments, the time duration of Trichel pulses was found to consist of a range of values for corona currents even very close to onset. Further, the range of magnitude of Trichel pulse frequencies after corona inception for a silver plated brass electrode of dia 1.0 mm has been observed to be of much lower magnitude than observed for stainless steel and brass electrodes of tip diameter 1.2 mm and 1.0 mm, respectively.