Performance of a large, CW, preexcited CO supersonic laser

The performance of a CO laser having electrical excitation by a continuously operating, self-sustained glow discharge in a high-pressure gas mixture followed by a supersonic expansion to the cavity region has been studied. A threshold for lasing was found which corresponded to 0.035 eV of input energy per CO molecule. Beyond this, nearly 15 percent of the additional energy was extracted by the resonator. The total power reached 940 W with a maximum electrooptical efficiency of 13.7 percent and a specific power of 17 kJ/lb. The vibrational population distribution of the CO in the cavity, with and without lasing, was determined from the overtone emission spectrum. The data indicated a significant loss of vibrational energy during expansion.