The status of rotational nonequilibrium in HF chemical lasers

It is pointed out that the successful scale-up of large HF and DF chemical lasers has depended on the predictions of several computer model/codes developed. In connection with the computational complexities involved, all codes have drastically simplified at least one and sometimes two or even all three of the involved factors. An obvious way to simplify the details of state-to-state chemistry was to ignore the possible effects of rotational nonequilibrium by assuming at the outset that the molecules in the lasing medium never deviated significantly from a Boltzmann distribution over rotational levels. The present investigation is concerned with evidence for rotational nonequilibrium in HF chemical lasers, processes which can lead to rotational nonequilibrium in HF lasers, rotational relaxation of HF, and modeling studies of rotational nonequilibrium effects in HF chemical lasers.