Progress in Development of a Chemical CO Laser Driven by a Chemical Reaction between Carbon Vapor and Oxygen

摘要

A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v=14, at low temperatures, T=400-450 K, with population inversions at v=4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants. A supersonic flow CO laser excited by a transverse RF discharge in the plenum is used to determine the effect of adding air species to the laser mixture. Carbon monoxide infrared emission spectra are used to measure CO vibrational level populations and temperature in subsonic CO-He, CO-He-N_2, CO-He-O_2, and CO-He-air flows excited by the discharge. Laser power and spectra generated in the transverse resonator in the M=3 supersonic flow are measured for each mixture. Nitrogen addition to the baseline CO-He mixture increases energy stored in the CO vibrational mode, resulting in a significant increase in laser power. Addition of oxygen had the opposite effect, reducing both CO vibrational populations and laser power. Adding air resulted in a modest increase of CO vibrational distribution, as well as an increase in laser power, although not as significant as when nitrogen was added to the flow. The results demonstrate feasibility of operating a supersonic flow CO laser in mixtures with significant amounts of air.