Study of pre-breakdown current in air-solid interface

An experimental study of pre-breakdown current in air-solid interface subjected to a 50-Hz AC voltage at atmospheric pressure is presented. The results show that the pre-breakdown current is in the form of pulses. We characterize these currents by the shape the pulses, their magnitude and the associated charge. The pre-breakdown current is strongly influenced by the applied voltage and the thickness and permittivity of the solid insulation. The effect of an air layer between the high voltage electrode and the solid dielectric on the characteristics of the pre-breakdown current is reported. The morphology of the surface discharge presents a particular aspect which depends on the space charge.