Amplification of visible light by S2 molecules in a supersonically cooled mixture of gases containing sulfur

A calculation was made of the gain as a result of interaction of light with S₂ molecules formed by recombination of sulfur atoms during cooling of a mixture of gases containing sulfur, first heated in a forechamber, by supersonic expansion. The optimal parameters of the gas flow and nozzle (initial composition of the mixture, pressure, temperature, nozzle profile and coordinates) corresponding to the maximum possible values of the optical gain were found. Gas mixtures CS₂–Ar and S₂–Ar were considered. A calculation of steady-state flow of a gas in a nozzle was carried out allowing for chemical reactions in the one-dimensional approximation. A search for the gain maximum (for a given initial gas pressure in the forechamber) was made by the method of configurations. At gas pressures of 10–100 atm in the forechamber, calculations yielded maximum values of the gain in the range 10^–4–2 × 10^–3 cm^–1(corresponding to the initial relative concentrations 13–5% and 17–5% of the CS₂ and S₂ molecules, respectively).