Modelling of COIL lasers

The modelling of chemical oxygen iodine lasers (COIL's) is discussed. A qualitative description of the system hardware elements and the major physical processes occurring in the laser is presented. Next, a steady one-dimensional model of the oxygen iodine laser system which includes the effects of area change, heat transfer, friction, mass injection and removal, changes in molecular weight and specific heat ratio and homogeneous and heterogeneous deactivation of species O2(1Delta) is described. The laser cavity physics is modelled by modifying a widely used laser analysis code, ALFA, to simulate iodine lasing. Theoretical calculations are presented for several typical operating conditions (cavity pressures of approximately 1-3 torr, mass flow rate, approximately 4 gr/s). Comparisons between experimental results and model predictions are presented for excited species, and selected flow variables.