2 - 5 Micron Chemical Laser.

Abstract : The objective of this research program has been to optimize Hydrogen Fluoride/Deuterium Deuterium Fluoride (HF/DF) chemical laser technology for application in lighweight, airborne systems with cw power levels in the range of several hundred watts. Outcoupled power levels as high as 140 watts were observed in a device with a 6 cm gain length at an efficiency of 620 J/g free fluorine, and with a 15 cm nozzle 120 watts has been produced without diluent at an efficiency of 526 J/g F. The latter corresponds to a specific power of 333 kJ/Kg of total flow. Laser performance was evaluated with a variety of hardware configurations and with several combinations of combustor and cavity fuels and oxidizers. NF3 was shown to be a good fluorine source when producing F-atoms in a low-temperature, nonequilibrium combustor. On a mole for mole basis, the performance of the halogen fuels HBr and DBr is equal to that of H2 and D2, but the requirement to use large quantities of diluent with these high molecular weight fuels still limits their usefulness. Extensive spectroscopic data on laser cavity conditions is reported. Qualitative agreement of theses chemiluminescence spectra with observed laser performance is excellent, but quantitative comparisons of the HF and DF data yields anomolous results. The ability to lase efficiently with no added diluent is shown to have potential in airborne laser systems of minimum size and weight. (Author)