A time-resolved study of the physical processes governing void discharges

A time-dependent, hydrodynamic, model of partial discharges in voids in dielectrics is presented. The partial discharge is regarded as a space charge dominated electron avalanche, or streamer. The model incorporates the collisional and radiative processes in the void and at the boundary, and the field distortion due to space charge and surface charge. The coupling with the external circuit is taken into account. Simulations show that, when increasing the Laplacian field, the charge saturates above a threshold, due to field quenching. The threshold field depends on the geometry and is higher than usually quoted inception fields. The saturation charge may deviate by an order of magnitude from values obtained with simplified models. Accurate reproduction of measured waveforms requires a 2D hydrodynamic model