Negative Corona in a Multiple Interacting Point-to-Plane Gap in Air

Negative corona discharge from multiple interacting points has been investigated with emphasis on the role of negative streamers in causing spark breakdown. The interaction among the evenly spaced bright discharge spots existing along a negative corona wire was simulated with a multiple point electrode whose point-to-point spacing was adjustable. The points were arranged in a circular and linear pattern. Although the current-voltage characteristic curves for the multiple point electrode-to-plane geometry are different from that for a single point-to-plane, the sparkover voltages are the same for both geometries. Additionally, sparking was always observed between the central discharge point and the ground plate. The dependence of the corona current on the configuration of the cathode, the effects of streamer branching on the sparkover, and the breakdown voltage versus gap length relation will be discussed. The experimental results confirm that negative streamers are less dominant than positive streamers in affecting spark breakdown.