Vol. 25, issue 03, article # 8

Abstract:

The paper presents the results of the study of the optical discharge and absorption of CO₂-laser radiation in the optical-discharge plasma in a supersonic air jet within Mach number range from 1.7 to 3.7. Qualitative experimental data about the dynamics of radiation absorption in the forming laser plasma within the wide range of gas-dynamic parameters of the supersonic air flow (velocity, static pressure, density, Mach number) have been obtained for the first time. It is demonstrated that the threshold density of air in the supersonic flow corresponds to the dramatic rise of the absorption efficiency and is equal to 1.8-2 kg/m³. The coefficient of laser radiation absorption in the optical-breakdown plasma has been measured for the supersonic air flow within the wide range of gas-dynamic parameters. The maximum value of the absorption coefficient reaches 60%. The distributions if the gas-dynamic parameters in the supersonic jet (dynamic pressure and temperature) with the energy supply from the optical breakdown plasma are given. The results of the work enable one to determine the supersonic flow parameters, which provide for a high level of the energy contribution into the flow and, hence, the ability to control the structure of such a flow.

Keywords:

high-power pulse-periodic CO₂-laser, mechanical Q-switching, the supersonic flow of air, the optical breakdown of air, the absorption coefficient of the plasma, dynamic pressure, the temperature of the thermal layer