Vibrational relaxation of carbon monoxide in supersonic streams

The results are given of a numerical analysis of the vibrational relaxation of CO-Ar mixtures in expanding supersonic streams. An investigation is made of the influence of the geometry, temperature, and pressure in the nozzle throat on the gain of the expanding medium. It is shown that at a distance of 4 cm from the throat the gain may exceed 5×10^–2 cm^–1 for one-quantum vibrational-rotational (VR) transitions in carbon monoxide when the degree of expansion in the nozzle is 100. A study is made of the influence of vibrational-translational (VT) and vibrational-vibrational (W) relaxation processes on the distribution over the vibrational states in the carbon monoxide molecule. The conditions are found under which complete inversion can be achieved in some VR transitions. It is shown that a gasdynamic laser may be based on two-quantum transitions in the CO molecule resulting in emission of wavelengths from 2.3 to 2.7 μ. An investigation is also made of the influence of the carbon monoxide content in CO–Ar mixtures on the gain and the results are compared with the experimental data.