High-speed schlieren studies of electrical breakdown in liquid hydrocarbons

Abstract

High-speed schlieren studies have been carried out on the electrical breakdown of liquid hydrocarbons using a pulsed ruby laser. The development and propagation of charge carrier trajectories were recorded photographically on prebreakdown, breakdown, and postbreakdown events occurring in very pure, oxygen-free samples of hexane, benzene, toluene, and isooctane using a parallel plate electrode geometry. The initiation of breakdown was characterized by the growth of narrow streamers the creation of which was attributed to field injected electrons at local asperities of the cathode surface. Once the streamers reached the anode, large currents were found to flow through the gap leading to formation of a plasma column. Subsequent emissions occurring at the anode were attributed to field reversal. Details of the schlieren pictures have been interpreted in terms of classical electromagnetic theory.