Experimental study of pulsed corona discharge in air

We report on the results of experimental investigation of a pulsed corona discharge in electric fields with different degrees of nonuniformity under the action of a standard thunderstorm pulse in a wide range of voltages from the origination threshold to the breakdown. A high-sensivity video camera makes it possible to record microdischarge and streameer procsses in air long before the spark breakdown. It is known that the size of the corona itdischarge sheath increases with the supplied voltage, and the shape of the corona sheath depends on the polarity of the active electrod [1, 2]. It was demonstrated for the first time by Peek [3] that the range of voltages from the initiation of a corona discharge to the spark breakdowne increases with the degree of nonuniformity of the electric field. We show that an analogous pattern is observed for a pulsed corona also. Our results show that the form of a pulsed corona discharge considerably depends on the pulse polarity, and a spark breakdown becomes possible when most branches in the streamer corona cover the electrode gap.