Flashover between Closely Spaced Electrodes on an Insulating Surface

The dc breakdown field strength of copper electrodes separated by an epoxy-glass insulator in air shows a -0.04 (1/25) power dependence on the length of the electrode-insulator-gas triple junction in the range 10-2-102 cm. The breakdown field strength was found to have an electrode-gap spacing power dependence of -0.45 in the range ~ 10-3-~10-1 cm. This is a similar power factor to both that of the Paschen curve for air at atmospheric pressure and for dc-and microsecond-pulsed discharges over insulating surfaces in vacuum. These results may be applicable to various surface discharge switches and surface discharge plasma sources.