The role of electrostatic and hydrodynamic forces in the negative-point breakdown of liquid dielectrics

By combining simple electrostatic and hydrodynamic concepts one can derive equations for cavity growth, the instability growth rate, and streamer velocity, with results in reasonable agreement with experiments at voltages near breakdown, in short gaps. In high-viscosity fluids other hydrodynamic growth processes are observed. Thus in 100 and 1000 cSt DC-200 silicone fluids a vortex of hot liquid forms near the point cathode and this vortex develops into a vortex ring which grows and decays; at high fields the vortex undergoes an unstable growth process, leading to multiple vortices