The electrical breakdown of viscous silicone fluids

The electrical breakdown of liquid dielectrics involves the generation and growth of a vapor cavity [1,2] and the dynamics of these pre-breakdown cavities in low-viscosity fluids have been widely studied photographically through the use of pulsed schlieren and shadowgraph techniques. Hakim and Higham, Farazmand, and Chadband and Wright [31, were the first to publish schlieren photographs that optically resolve the pre-breakdown events in liquids; these photographs show that a cavity forms in the vicinity of an electrode in a few microseconds before breakdown. Optical studies of this type were extended by Forster and co-workers, Devins et al., and others, so that a considerable amount of photographic information of this type is now available. The majority of workers have concentrated on low viscosity fluids ranging from n-hexane to transformer oil, but work has been reported on liquids of higher viscosity by Chadband and Calderwood [ 41 and Krasucki.