Gain and generation of laser radiation in a N2O-N2/CO/-He mixture in a supersonic flow

Results are presented for an experimental study of the dependence of gain at 10.9 microns in a N2O-N2-He mixture on partial composition, stagnation temperature, and distance from the nozzle slit. Measurements were performed in a shock-heated mixture flowing through a wedge-shaped nozzle with an angular aperture of 30 deg and an area ratio of 15. Maximum amplification was obtained in a 0.1:0.2:0.7 N2O-N2-He mixture 15 mm from the nozzle slit. Characteristics of the supersonic discharge are investigated which can be used to determine the gain per unit length. The effect on gain caused by substituting CO for N2 and by adding CO to the optimum mixture is evaluated, and the laser output is measured for the optimum mixture. In the CO-containing mixtures, the gain is measured at 10.9 microns as well as at 10.6 microns (for chemically produced CO2).