Prebreakdown phenomena in hydrocarbon liquids

Prebreakdown current, photo current and conduction current are measured in n-hexane, cyclo-hexane, 1-hexene and benzene. Similar phenomena are observed in the saturated hydrocarbon liquids, n-hexane and cyclohexane, whereas great difference is observed in the unsaturated hydrocarbons, 1-hexene and benzene. In the case of bush-type light emission, the mean velocity is about 100 m/s, and the waveforms of the photo and the prebreakdown currents are pulsive. But in the cases of tree-type and radial-type light emission, the mean velocities of them both are a few km/s, and a continuous light emission with a sudden increase of prebreakdown current are observed just before breakdown.