Optical discharge with absorption of repetitive CO₂ laser pulses in supersonic air flow: wave structure and condition of a quasi-steady state

We report a study of the wave structure formed by an optical discharge plasma upon the absorption of repetitively pulsed CO₂ laser radiation in a supersonic (M = 1.36) air flow. Experimental data are presented on the configuration of the head shock wave and the geometry and characteristic dimensions of breakdown regions behind a laser plasma pulsating in the flow at a frequency of up to 150 kHz. The data are compared to calculation in a point explosion model with allowance for counterpressure, which makes it possible to identify the relationship between laser radiation and supersonic flow parameters that ensures quasisteady- state energy delivery and is necessary for extending the possibilities of controlling the structure of supersonic flows. (interaction of laser radiation with matter)