Investigation of the interaction between a hypersonic air stream and a carbon dioxide aerosol

A detailed investigation is made of the interaction between a hypersonic vibrationally excited donor gas and a carbon dioxide aerosol stream with a view to improving the energy characteristics of a gasdynamic СО$_2$ laser. The analysis shows that rapid (within times shorter than the relaxation time of the upper active level) mixing of the evaporating aerosol and the vibrationally excited gas is possible as a result of this interaction. For a planar flow geometry with symmetrical aerosol injection, the transverse dimension of the active medium may be $\gtrsim$ 20 cm for a hypersonic nozzle with a throat cross section $\sim$ 1 mm high. The conditions under which there were no gas-dynamic perturbations in the mixing zone and the active medium was optically homogeneous were determined. A СО$_2$ aerosol generator was developed with a solid particle size distribution function close to the optimal. An experimental investigation was made of the interaction between the streams using a system with a conical hypersonic nozzle for the air and perpendicular injection of the aerosol. The experimental results broadly agreed with the theoretical predictions. A СО$_2$ laser radiation gain close to the calculated value was obtained in the excited air-carbon dioxide aerosol mixing zone.