Characteristics of a Subthreshold Microwave Discharge in a Wave Beam in Air and the Efficiency of the Plasma-Chemical Reactor

An analysis of a set of experiments on studying subthreshold microwave self/non-self-sustained (SNSS) discharges made it possible to estimate the volume of the active zone of self-sustained thread-like discharges resulting from the development of the ionization–overheating instability. It is shown that this volume is 0.04–0.1 of the wave beam volume. It is shown that in the processes of the plasma-chemical action of the SNSS discharge, mixing of the substance reacted in the active regions with the gas outside the active regions increases the cost of the plasma-chemical process. A decrease in the energy cost of plasma-chemical processes requires an increase in the ratio of the microwave beam volume to the plasma-chemical reactor volume. A scheme of a flow-through reactor with a multimode waveguide is proposed and the possible performance of such a design in the destruction of harmful impurities in gas mixtures is estimated.