Ram airbreathing laser

The performance characteristics of a ram airbreathing laser (RAL) were investigated for a wide range of Mach numbers (3 to 6) and altitudes (40 to 100 Kft). The supersonic inlet, based on pressure recovery data, provided pressures between 2 and 55 atm and temperatures between 600 and 1700K at the combustor inlet. Benzene was used as fuel to raise the gas temperature. The population inversion, the small signal gain and maximum available laser energy were determined as functions of axial position for the nonequilibrium flow through the special nozzle and laser cavity section for the unique RAL CO2-N2-H2O-O2 gas mixture for the current vibrational relaxation rates. The mole fraction of each constituent in the gas mixture was evaluated as a function of the combustor inlet conditions, fuel and fuel-air ratio. The laser performance characteristics were established for a wide variety of pressures, temperatures and nozzle characteristics. The pressure, temperature, nozzle area ratio and throat height for maximum laser performance were identified. The laser power increases with decreasing altitude and increasing Mach Number. The laser cavity and ram inlet geometries have been evaluated as functions of Mach number. (Modified author abstract)