Performance of an HF chain-reaction laser with high initiation efficiency

Output-pulse observations are presented for a tranverse electrically initiated, helium-diluted HF laser pumped by the H2+ F2chain reaction. Performance of this laser is studied over a wide range of the gas composition and for initial pressures between 0.1 and 0.5 atm. The gas mixture was stabilized by premixing O2, F2, and He and flowing this mixture into a cold trap (84 K) before mixing with H2. Optimum conversion of electrical-initiation energy into laser energy was found for a 240-torr mixture with a mole ratio 1 F2:0.23 H2:0.08 O2:12 He which, when initiated with a 25-kV, 333-pF discharge, gave a pulse energy of 0.150 J. This corresponds to a ratio of laser output energy to electrical input energy of 144 percent. After unnecessary losses are taken into account, this ratio becomes 160 percent.