On the atmospheric-pressure pulsed HF chemical laser

Experiments are described on a pulsed chemical laser operating on the reaction between hydrogen and fluorine at pressures above the second explosion limit. Using a stable resonator, pulse energies of more than 1 joule have been obtained, corresponding to an energy density of 10 joules/ liter, and a chemical efficiency of 1%. Short pulse flash lamps were used for triggering the reaction; the laser pulse extends considerably beyond the flash lamp duration, indicating the chain is proceeding. Detailed analysis of the spectral distribution of the output pulses indicates the possibility of a non-Boltzmann distribution among rotational states during the laser action. The laser energies obtained are compared with values calculated using a theoretical model of the reaction. The effect of rotational relaxation on the laser energy is discussed.