Characteristics of a downstream-mixing CO_2 gasdynamic laser caused by behavior of two supersonic flows in a laser cavity

Abstract

A combustion-driven downstream-mixing CO(2) gasdynamic laser (GDL) is developed. When the total mass flow rate is ~ 2 kg/s and the combustion gas temperature is 1750 K, a small-signal gain coefficient of up to 0.6% cm(-1) and a laser output power as high as 11 kW are measured. To explain the experimental values, a mixing loss factor was previously introduced into an analytical model incorporating the three-temperature kinetics model. In the present study, a numerial analysis and further experiments are carried out to clarify the mixing behavior of two supersonic flows in the laser cavity. A measuring method for the average static temperature in the laser resonator is adapted, and it is made clear that, with the current state of supersonic nozzle manufacturing technology, two supersonic flows will not mix well.