The relationship between the estimated intensity of electrical current flowing in the electrolyte and the propagation of the local discharge on an electrolytic surface under AC voltage

The concept of the estimated intensity of the electrical current flowing in the electrolyte enables one to check the advancement of the leader of the discharge according to time. We observed the extension of a discharge on an electrolyte surface by using an original set-up permitting simultaneous measurements of optical and electrical parameters on the same flashover in different points of the discharge path. The resistance per unit length of the conductive film was varied in the range 2 kΩ/cm to 10 kΩ/cm. Experimental results suggest that on the first half of the course that the discharge nearly propagates with a constant instantaneous velocity. It then accelerates its progression on the second half with discontinuities capable to be assigned to progressions by jumps characterizing a change of mechanism of propagating discharge. Our results have been validated by comparison with those published in the literature, which they confirm and often refine. The results bring to the fore the presence, ahead of the principal discharge, of a photoionization zone in which the development can occur of the streamers serving as precursors to its extension.