The supersonic air flow structure and parameters in optical breakdown zone for high frequency energy pulses
The shock-wave flow structure was determined by the results of the optical and pneumo-metric measurements; this structure forms at the optical breakdown realized by the focused pulse-periodical radiation of the СО<sub>2</sub>-laser as the air supersonic flow is injected perpendicularly toward it. The dynamics of the head shock wave formation in front of the energy-release area regarding the energy pulses repetition frequency is shown. The flow structure in the thermal wake behind the pulsing laser plasma is found, as well as the length of the thermal wake with low temperature nonuniformity. The size of the 3D configuration of the energy-release area was determined by the results of the optical and pneumo-metric measurements. Pioneering results show that the stagnation pressure and Mach number decrease in the thermal wake as the static pressure remains almost constant. Slight dependence of the averaged flow parameters on the energy pulses frequency within the range of 45 – 150 kHz is demonstrated.