Investigation of the Surface Filamentary Discharge in Focus of Microwave Radiation

摘要

This report results from a contract tasking Federal State Unitary Firm 'MRTI' of RAS as follows: Experimental investigations of gaseous electrical discharges in quasi optical beams of electromagnetic (EM) radiation in microwave (MW) wavelength range showed that they are being realized in a streamer form at some definite range of gas parameters and radiation. Such discharge effectively absorbs radiation energy. It opens wide possibility for their applications. In frames of the Project No. 2820 we studied initiated MW discharge in EM beam focus in air both free localized electrodeless one and attached to initiator (EM vibrator). During these investigations we varied air pressure, amplitude of electric component of linearly polarized field exciting the discharge, radiation pulse duration, etc. Namely this wide set of experimental conditions has allowed to reveal typical discharge forms, realization areas of these discharge forms, spatial discharge structure formation velocity, maximum gas temperature T of discharge plasma in streamer channels, absorbing ability etc. In frames of the Project No. 2820 we have carried out also initial investigations of a MW discharge on surface of a dielectric plate located in linearly polarized quasi-optical beam. They have shown that undercritical MW discharge with developed streamer structure can be realized in this case. Experiments were undertaken in the case of transversal location of the dielectric plate (perpendicularly to wave vector of radiation) and in the case of longitudinal location (parallel to wave vector and electric field). Our experiments have shown that such discharge on the dielectric surface in both cases keeps its streamer type at a pressure higher than some definite value both in dead air and in its high-speed flow. This surface MW discharge feature opens wide possibility of its practical application even in coSurface MW discharge in quasi-optical beam fe.