The dynamics of electrical breakdown in liquid hydrocarbons. II

The development of an electrical spark in purified hydrocarbons has been studied using a pulsed laser schlieren technique. A 15 ns laser pulse, coming from a Q switched ruby laser was split into two or three beams. Two of the beams are sent through the test cell in the same direction with one delayed by 60 ns with respect to the other. They are projected onto two different cameras. With the help of the schlieren optics the movement of the charge carriers is indicated in terms of density gradients. The pictures so obtained suggest that the electrical breakdown column moves between the parallel surfaces somewhat similar to a tornado. The significance of these findings is discussed in the light of earlier results and a qualitative mechanism for electrical breakdown is proposed.