Equilibrium chemical composition of the gases in a sealed high-pressure pulsed CO2 laser

The dynamics of changes in the chemical composition of the gas mixture in a pulsed high-pressure gasdischarge CO₂ laser with photopreionization, a high current-pulse repetition rate, and transverse circulation of the gas around a closed loop was studied and the setting up of an equilibrium chemical composition was investigated. The use of a high repetition frequency for the current pulses facilitated the rapid establishment of an equilibrium chemical composition in the gas mixture (in about 10–15 min), in a relatively large volume (60 liters), without the mixture being strongly contaminated by desorbed gases. It was established that after this interval of time, following the initiation of a discharge in the gas, a dynamic equilibrium was set up between the dissociation of the CO₂ molecules and the recombination of the dissociation products. It was shown that a steady-state degree of dissociation of the CO₂ gas was a function of the electric-discharge parameters and of the initial composition of the gas mixture, and was independent of the pressure. Under typical laser discharge conditions, the steady-state degree of dissociation of the CO₂ molecules was 20–30%. It was found that hydrogen could be used as a catalyst for oxidizing carbon monoxide. On the basis of these investigations, the use of reduced pressures of the gas mixture is recommended for practically important operating regimes of pulsed CO₂ lasers which employ gas mixtures in chemical equilibrium.