Surface Discharge in a Microwave Beam

A review of new experimental results on the characteristics of pulsed microwave (MW) surface plasmas on a dielectric plate is presented. The plate is located in a quasi-optical linearly polarized electromagnetic (EM) wave beam with an electric field lower than the critical breakdown field. Experiments were realized with two wavelengths of radiation. The plate was located both in a plane perpendicular to the pointing vector of this radiation and in a plane containing the pointing vector and a vector of the electric component of radiation. Preliminary experimental researches have shown that the corresponding transversally and longitudinally initiated surface MW discharges were realized in a surface-developed streamer type for a certain range of air pressure. The growth rate of streamer channels forming the discharge exceeds the sound speed in air. Separate areas of these channels, which have lengths comparable with the half wavelength of the field, interact energetically with the EM field producing the discharge in an efficient manner. The opportunity offered by the realization of these discharges attracts attention to questions on their practical application and further directions for experimental research.