Electrical Breakdown Assisted by Shock Wave in Benzene

Observation using high-speed photography shows that the propagation velocity of a positive streamer in benzene is independent of the applied field over a certain range of applied voltage and that this field-independent propagation process is always accompanied by a shock wave. The streamer propagation velocity is also obtained from the linear relationship between formative time lag and gap spacing. The streamer velocity of 1.3 km·s-1 is equal to the sonic one in benzene. The results presented support a model of a positive breakdown mechanism based on a field ionization process involving thermal excitation and polarization.