SMALL SIGNAL GAIN COEFFICIENT AND POWER OUTPUT CALCULATIONS OF HIGH TEMPERATURE CO2 GASDYNAMIC LASER WITHOUT FLOW STAGNATIONS

Abstract

This paper deals with numerical analyses of the flows in a bow shock wave (B.S.W.)- nozzle system which is applied to the gasdynamic laser (G.D.L.). In the B.S.W.- nozzle system, the dissociation of CO2 or N2 molecules of the gas is suppressed even if the gas behind the B.S.W. is heated up to 2,000-5,000 K, since the gas is cooled rapidly, expanding through the nozzle. Numerical calculations for such flow fields lead us to the estimation of the capability and the optimum conditions of such G.D.Ls.. It is turned out in our system that the mole-fractions of CO2 can be elevated to 20%, and the small signal gain coefficients increase more than four or five times (3.8 m-1) than those of conventional G.D.Ls.. Numerical estimations of the laser power output are also examined for both cases of CW and Q-switch operations.