INFLUENCE OF THE OXIDIZER GAS-COMPOSITION ON THE OVERTONE GENERATION EFFICIENCY OF A SUPERSONIC CW CHEMICAL HF LASER

An experimental investigation was made of the influence of the chemica l composition of the oxidiser gas in an atomic-fluorine generator on t he efficiency of generation of radiation representing the first overto ne of the HF molecule in a self-contained supersonic cw chemical HF la ser with the active medium 70 cm long. The optimal chemical compositio n was different for the fundamental and overtone transitions. A specif ic output energy of 84 J g(-1) at a specific mass flow rate of 0.13 g s(-1) cm(-2) through the nozzle array was achieved by optimisation of a linear three-mirror optical cavity at the 1.33-1.35 mu m wavelengths . The overtone radiation power generated in the whole of the active me dium was 7.5 kW, corresponding to a 41% efficiency of energy conversio n to an overtone.