Electrically Excited, Supersonic Flow Carbon-Monoxide Laser with Air Species in Laser Mixture

Abstract

Performance parameters of an electric discharge excited, supersonic flow CO laser operated with significant amounts of air species in the laser mixture is studied experimentally and by kinetic modeling. The results demonstrate that adding nitrogen to the CO-He mixture increases the laser power significantly, by up to a factor of 3. Adding oxygen reduces CO vibrational excitation and results in a steep laser power reduction. Adding air to the laser mixture also produces higher output power, such that the positive effect of nitrogen outweighs the negative effect of oxygen. This result indicates that a chemical CO laser, not dependent on the electric discharge for excitation, may be capable of operating in a mixture of carbon vapor and air. Performance of a supersonic flow chemical laser excited by a reaction of carbon vapor and molecular oxygen is analyzed by kinetic modeling. Peak laser power is predicted at the C vapor mole fraction of 0.2%, when 15% of energy stored in CO vibrational energy mode (4.5% of the reaction enthalpy) is converted to laser power. At higher C vapor mole fractions, flow temperature rise caused by exothermic reactions and by CO vibrational relaxation results in rapid reduction of the predicted laser power.