Optical breakdown in supersonic air jet

The characteristics of a free supersonic air jet with a diameter of 10 mm and Mach numbers within 1.7–3.7 have been studied in the presence of energy supply via pulsed optical discharge generated by a periodic-pulsed mechanically-Q-switched CO$_2$ laser. The coefficient of laser radiation absorption by optical discharge plasma in supersonic air jet has been studied and it is established that this parameter can reach 60%. It is demonstrated for the first time that a threshold density of air corresponding to sharp growth in the absorption efficiency amounts to 1.8–2 kg/m$^3$ and is independent of the Mach number in airflow. Distributions of the gasdynamic parameters (including dynamic pressure and temperature) in supersonic air jet with energy supply via optical discharge have been determined.