Theoretical and experimental study of electrically initiated HF chemical lasers

Two classes of electrically initiated HF lasers (electron beam lasers and pin discharge lasers) are studied using separate models for discharge characteristics, chemical kinetics, and radiation dynamics. The amount of dissociated fluorine atoms produced initially is calculated by means of a model in which initiation energy is partitioned between ionization and dissociation (via excitation of low lying repulsive electronic states in various fluorides). Predicted dissociated F atom density is then inserted into an analytical chemical laser model and predicted laser outputs are compared with published experimental results. In this model, excited state densities are computed by means of a matrix procedure which is rigorous to the extent that radiation transients are those induced only by cavity and chemical kinetics--not those related to peculiarly quantum optical phenomena (such as rotation of polarization). Careful comparison of the output of an E-beam initiated amplifier with results from a comprehensive quantum optics computer code shows that the amplifier output faithfully reproduces the computed small signal gain profile, including the initial spike. After the turn-on spike the amplifier output peaks at a time given by p sec atm. Correlation of this result with theory shows that collisional deactivation of HF by H atoms must be considered and is at least as fast as deactivation by F atoms.