Multimode low-pressure cw chemical laser performance including source flow effects

The performance of low pressure (inhomogeneously broadened) multiple longitudinal mode cw chemical lasers is investigated in the limit Deltanu(c) << Deltanu(h), Deltanu(h) << Deltanu(d), where Deltanu(c), Deltanu(h), and Deltanu(d) represent longitudinal mode separation, homogeneous width, and Doppler width, respectively. Effects of source flow (i.e., mean motion in optical path direction) are included. The present approach, in which power on spectral line shape is assumed a priori, yields physically realistic self-consistent solutions for laser flow regimes of practical interest. Numerical results, as well as analytic limit solutions, are provided. The decrement in net laser output power, caused by lack of saturation and by source flow, is evaluated. It is concluded that the latter can be estimated from numerical codes in which a single longitudinal mode is assumed at line center for each lasing transition, provided zero power line center gain is corrected for the source flow effect. It is also concluded that a limit solution deduced herein provides relatively accurate simple-closed-form analytic expressions for laser performance in the regime of interest.