Microwave Low-Pressure Gas Discharge Sustained by a Standing Surface Wave in the Dipolar Mode

The maintenance of a microwave gas discharge of a standing surface electromagnetic wave (SEW) in the dipolar mode is studied. The standing wave was formed between two flat mirrors that create an open resonator type structure on the surface wave. The measured Q factor of the open resonator is several tens. The electric field structures of a free discharge and a discharge supported by a standing surface wave field are determined. It is shown that resonance on a purely surface wave is excited in this system. With an increase in the field energy between the mirrors by 8–10 dB, the concentration of electrons increases by about 50%. The ratios of the surface wave field energies in the plasma and in the space surrounding the discharge both in the case of a free discharge and during resonance are estimated. The results of experiments and numerical simulations show that the structure of the discharge depends on the excited mode of steady-state SEWs.