A surface microwave discharge at high pressures of air

An investigation is performed of a microwave discharge generated on the external surface of a quartz antenna at high pressures of air, where the electron-molecule collision frequency is much higher than the circular frequency of electromagnetic field. Under these conditions, a surface microwave discharge consists of a system of thin plasma channels with transverse dimensions of $0.1$–$0.2$ mm. The dynamics of development of surface microwave discharge are studied, and the dependences of longitudinal dimension of discharge and of longitudinal velocity of its propagation on microwave power input and on duration of stimulation are measured. It is demonstrated that, at the initial stage of forming of discharge, the longitudinal velocity of its propagation reaches a value of $2$–$30$ km/s and, at high pressures of air $p > 30$ torr, the main mechanism providing for the propagation of discharge is the breakdown wave.