High-Power electron-beam pre-ionised CO2 cw laser modelling III : kinetic and fluid-dynamic model

In this paper, which is the third part of a work devoted to modelling high-power CO2 lasers, the kinetic and fluid- dynamic model of the investigated device is presented. The kinetic model takes into ac¬count intermode vibrational exchange and vibrational-energy transfer among different molecular species (C02, N2 and CO). The fluid-dynamic equations have been reduced to a single equation coupled to kinetic and discharge equations via gas flow velocity in the discharge chamber. Effects of temperature, density and velocity variations in the flowing mixture on laser small signal gain have been investigated by using a numerical code based on the above theoretical model. Profiles of sustainer current, small signal gain and fluid-dynamic parameters in the discharge chamber have been obtained. The output power has been calculated by using a simplified model for the optical cavity. Finally, numerical and experimental results are compared.