Current pulse shapes of discharges in air gaps limited by series dielectrics

When gas voids in solid dielectrics break down under the application of an electric field, the current flow (as observed in the external circuit) is discontinuous, usually consisting of very short (ca. 10−7 sec) pulses. This general behavior is not unexpected, since the charge produced by breakdown of the gas cannot flow through the solid insulation, and therefore reduces the potential across the void, causing extinction of the discharge. If circuit time constants can be reduced below the times taken for charge movements in the gap, the current flow as a function of time should provide information on the nature of the charge carriers and on the breakdown mechanisms operative.