Calculation of surface current response to surface flashover of a large sample under grounded and floating conditions

Results for the electromagnetic response to the discharge of an 80 cm diameter dielectric sample mounted on a 120 cm diameter cylinder are presented. It is assumed that the dielectric is charged with a known potential profile dropping sharply near the edge, and the substrate initially grounded. During the early part of the discharge (approximately 10 ns) there is little difference between the grounded and floating cases. Beyond about 10 ns the grounded experiment is in approximate steady state, continuous to blow off charge until the dielectric is substantially discharged. The floating case, however, shows modestly decreasing emission and response. Eventually, a quasi-steady state is reached in which charge is transported from dielectric to substrate rather than blown off.