Air breakdown induced by a high-power short-pulse microwave

Air breakdown induced by a high-power short-pulse microwave in the pressure range from 100 to 760 Torr has studied experimentally. The high-power microwaves with the peak power of 20 MW, frequency of 12 GHz and pulse duration of 14 ns is irradiated to a pair of needle and plane electrodes biased at the potential less than the breakdown voltage. The gap separation between the needle and plane electrodes is 1.5 cm. Microwave-induced breakdowns occur at the pressure range from 150 to 760 Torr for negative potential and from 150 to 350 Torr for positive polarity at the presence of corona discharges. At the pressure range less than 150 Torr, the microwave-induced breakdown occurs without corona discharge at both polarities.