Toward developing a dynamic theory of electric breakdown in solids

Abstract

The relationship between breakdown modeling and the phenomenology of breakdown are elucidated. This phenomenology is based mostly on studies of electric breakdown in thick specimens (1 mm to 25 mm) of both polymeric and nonpolymeric materials, in a macroscopically uniform field geometry. Each specimen was subjected to a single impulse, with breakdown occurring typically on the rise. Risetimes to breakdown were 10 to 30 ns, depending on thickness and rate of rise. Diagnostics included waveforms (specimen voltage, current, and intensity of the self-luminosity), photographs of breakdown configurations from their self-luminosity, and post mortem microscopic studies of damage to the dielectrics and the electrodes. Breakdown initiation and tree propagation are treated. Some generalizations on breakdown modeling are presented. The need for a dynamical model that incorporates the macroscopic geometry, presence of the key microscopic field enhancement site, realistic parameters for high-field conduction processes, initial conditions on space charge distribution, the time history of the applied stresses, and three-dimensional time-dependent solutions is emphasized.<>