Numerical modeling of a slow axial flow CW CO2 laser with simultaneous striking of two discharge tubes

Abstract A five temperature model which consists of a system of differential equations is applied to describe the operation of locally made a slow axial flow CW CO 2 laser with simultaneous striking of two discharge tubes. The model is solved using Runge-Kutta method. The laser works on the mixture of CO 2 :N 2 : He with a ratio of 1:1:4, at a total pressure of 8–20 mbar and a discharge current of 120–140 mA. According to the experimental measurements of the laser characteristics at certain operational conditions, the “BOLTZOLD” software has been used to determine the electronic excitation rates of CO 2 and N 2 molecules and electron drift velocity in the discharge. Therefore, the numerical solution of the rate equations for laser levels and energy balance equation of the discharge has been carried out using a written FORTRAN program under these conditions. Consequently, the temporal behaviour of the output power, the photon density of the laser emission, and the laser output power versus the input power are defined under the taken pressures and currents. In addition, the effect of gas kinetic temperature on the output power is studied taking into account the variation of loss factor depending on the operating conditions of the laser. The calculated and measured results of the output power versus the pressure, the current and the input power are in a good agreement under certain values of loss coefficient. In resume, the developed model could be used to predict and evaluate the performance of slow axial flow CW CO 2 lasers.