POWER AND EFFICIENCY OF A CONTINUOUS HF CHEMICAL LASER

Experimental measurements of laser power output and chemical efficiency are reported for a continuous HF chemical laser. In this device, arc-heated N2 is mixed in a plenum with SF6 to provide F atoms. The mixture is expanded to form a supersonic jet into which H2 is diffused. Population inversion and lasing are due to H2 + F to HF(v) + H, v < or = 3, Delta H = -31.7 kcal/mole. Power levels up to 1 kw have been obtained. The efficiency of conversion of chemical energy to laser power is 16% at low SF6 flow rates and approximately 10% at peak power. For a fixed arc power, addition of 02 into the plenum raises peak power by about 25% under present operating conditions and reduced sulphur deposition on mirror surfaces. The presence of HF and DF in the plenums of DF and HF lasers, respectively, did not appear to degrade laser performance. However, the presence of HF and DF in the plenums of HF and DF lasers, respectively, did degrade laser output. For given flow conditions, peak net laser power was obtained when the optical cavity axis was about 2 cm downstream of the H2 injection station. The net output power was reduced to zero when the cavity axis location was increased to 5 cm. (Author)