The effects of surface roughness on the surface flashover voltage of lucite, lexan, and celcon

The materials, Lucite, Lexan, and Celcon, were tested in order to determine the dependence of flashover voltage upon surface roughness. Ten different roughness groups were tested. Marx banks delivering 1.2 / 50/spl mu/s double exponential (standard lightning) impulses of negative polarity were used and the experiments were conducted in a vacuum chamber at 1 X 10/sup -6/ torr. The flashover voltages varied significantly for different roughnesses, and these variations differed for the different materials. Further investigation into Lexan was performed by placing two different roughnesses on each sample tested. The purpose of this was to investigate how the samples behaved under flashover conditions while the roughness dividing line was near the anode or the cathode. A hypothesis is presented that describes the relationship between the surface roughness and the susceptibility to and effects felt by surface contamination from the cathode.