Gain saturation in gas flow and chemical lasers

The gain saturation properties of a flowing gas laser medium are investigated theoretically. The basic equations describing the interaction between the flowing gas gain medium and the laser radiation field are considered to be applicable to all possible numerical values of tau/tau sub c, where tau is the characteristic flow time, and tau sub c is the collision relaxation time. On the basis of the basic equations, the influence of convection and source flow in the inverted population on line broadening are analyzed. The effects of convection and source flow on gain saturation were also considered. It is shown that the theoretical calculations are consistent with the experimental results of Gross and Coffer (1982) which described anomalous saturation phenomena in a CW supersonic diffusion HF chemical laser, with tau/tau sub c less than 1. In the case of tau/tau sub c much greater than 1, the theoretical results conformed to standard theory for gas lasers in which the gas has no macroscopic motion.