Small-signal gain in the oxygen-iodine laser

A simple model for predicting the small signal gain as a function of flow direction is presented. It basically couples simplified kinetics and fundamental gas dynamics and allows for the heat release produced by the water deactivation of excited oxygen and iodine. The numeric results lead to a temperature rise in the gas, which causes a substantial decay of the small signal gain in flow direction. An analytic solution is also derived and results of both approaches compare favourably with experimental data.