Proceedings PaperSpecific power optimization for COIL
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A heuristic approach for predicting the available laser power per nozzle area will be presented and discussed as a function of reduced mass flow rate and oxygen pressure. The different loss mechanisms due to limited oxygen generator performance, gas transport, iodine dissociation, water deactivation, and laser threshold will be clearly identified. A comparison with available experimental data shows that the model describes subsonic and supersonic experiments, as well. However, a limited validity of the simple model is found for further pressure scaling. This relates in particular to the usual description of the water deactivation losses. The goal of this paper is to derive a new expression for those losses which are still valid at higher gas pressures. The new approach presented in this paper starts from the basic rate equations and takes into account the steady state situation between the excited iodine atom and the excited oxygen molecule. The newly derived expression is included in the general heuristic approach predicting the available laser power. Numerical results are discussed for various laser parameters. Special emphasis is given to the relative importance of gas transport vs. water quenching losses as a function of oxygen pressure and mass flow rate in the laser.