The mechanism of the formation of discharges limited by series dielectrics

Usually investigations of the nature of electrical discharges in gas voids in solid dielectrics are made using ac voltages or at least voltages changing continuously with time. Owing to statistical time lags this implies that each discharge will occur at a slightly different applied voltage always somewhat larger than the minimum Townsend threshold value. We have recently obtained evidence suggesting that the over-voltage is of considerable significance in determining the nature and magnitude of the discharges.