Ignition of electric gas discharge in the deeply subcritical field of quasi-optical microwave beam with an electromagnetic vibrator mounted over a metal screen

umerous experiments with the electric gas discharge ignited in the Fresnel region of a microwave beam[1] have indicated that the plasma formation of such discharges at high gas pressures p efficiently interacts with an electromagnetic wave exciting them. This stimulates searches of practical applications of this type microwave discharges, and conduct further basic physical investigations. Considered discharges may be realized at the amplitude of the electric component of the field E0 less than electric breakdown field Ecr (critical value) at given gas pressure p. To do this you need to create some method of initiation of electrical gas breakdown in the required area of EM beam. In work [2] the method of initiation breakdown by cylindrical EM vibrator placing in the microwave traveling wave is described. The field Epol induced in vicinity of pole surfaces of such a vibrator can significantly exceed its exciting field E. This enables ignite of these microwave discharges in gases at high pressures p and/or at low values of microwave beam power Pbeam including even the case of continuous burning. For example, when p>100 Torr subcritical discharges (E0>Ecr) can be realized only in a pulsed mode with a duration of microwave pulses pul ~ several tens of micro seconds or less[1].