Breakdown process of long air gaps with positive switching impulses

This study reports on measurements with multiple techniques delineating the complete sequence of events from the corona streamer to the arc phase in the spark transition for large rod-to-plane air gaps applied by positive switching impulses. Observations with a image converter camera, photomultipliers, a Boys camera, and still cameras as well as measurements of voltages and currents have revealed that starting with the corona streamer the breakdown proceeds through the development of the leader and the intermittent appearance of the light flash to the final spark formation. The detailed analyses were made to the corona streamer, intermittent flashes, and the final transition to the arc phase with extremely high time-resolution techniques.