Experimental Study of Air Breakdown Induced by Subcritical Streamer Microwave Discharge

Air breakdown in sub- and supersonic flows induced by the subcritical streamer discharge and the effect of the initiator shape on breakdown conditions are studied. Experiments with varying the electric field strength and air pressure show that the ability of electromagnetic vibrators to initiate air breakdown has a resonant character. Placing a small electromagnetic vibrator in a microwave beam allows one to initiate air breakdown with a field strength in the microwave beam which is significantly smaller than the critical breakdown strength. The dependencies of the critical intensity of the electric field on the pressure and location of the initiator are reported. The dependence of the field amplification coefficient at the vibrator edge on the screen dimensions is presented at different lengths and widths of the screen.