Experimental study of the motion of a shock wave in the plasma of a pulsed volume discharge in air

The motion of quasi-plane shock waves with Mach numbers = 2.20–3.50 in the plasma of a nanosecond combined volume discharge in air at an initial pressure of 10–100 Torr has been experimentally studied on the basis of high-speed shadow registration of the flow field. The dynamics of shock–wave configurations after the discharge at various stages of an unsteady supersonic flow, which is formed after the diffraction of a plane shock wave by a rectangular obstacle, is studied. An increase in the velocity of the shock wave front over a time interval of up to 15 𝜇s in a plasma region of 9–40 mm long and its dependence on the plasma parameters is found. An analysis of relaxation processes in plasma showed that the acceleration of the shock wave front can be caused by air heating due to the quenching of electronically excited nitrogen molecules, in which the internal energy is converted into thermal energy at times up to 30 𝜇s.