Observation of the Arc Discharge Generated between a Pair of Opposed-electrodes in the Normal Direction to a Supersonic Air Flow

Pulse arc discharge is successfully generated in a Mach 5 supersonic free-jet between a pair of electrodes perpendicular to the flow with the voltage at 300V and the current at 200A. Two different gap lengths, 2mm and 6mm, between the electrodes are tested. From the high-speed images of the discharge, it is found that the arc discharge runs across the jet with the short gap, 2mm, while the arc discharge runs around the shear layer of jet with the longer gap, 6mm.