Experiments and modeling of supersonic COILs

Preliminary experiments and extensive modeling of supersonic chemical oxygen-iodine lasers (COILs) are reported. A 10-cm gain-length device is studied and both the gain and the power are measured as a function of flow rates and densities of the reactive species and of the output coupling. The mechanism of I₂ dissociation in supersonic COILs is studied applying a kinetic-fluid dynamics model, where pathways involving the excited species I₂(X¹Σ⁺_g,10≤v<25) , I₂(X¹Σ⁺_g,25≤v<47) , I₂(A′ ³Π_2u),I₂(A ³Π_1u),O₂(X ³Σ ^-_g,v),O₂(a¹Δ, _g,v),O₂(b ¹Σ⁺_g,v) I(²P_1/2) as intermediate reactants are included. The gist of the model is adding the first reactant and reducing the contribution of the second as compared to previous models. These changes, recently suggested by V. N. Azyazov et al., J. Chem. Phys. 130, 104306 (2009), significantly improve the agreement with the measurements of the gain in a low pressure supersonic COIL for all I₂ flow rates that have been tested in the experiments. In particular, the lack of agreement for high I₂ flow rates, which was encountered in previous models, has been eliminated in the present model. It is suggested that future modeling of the COIL operation should take into account the proposed contribution of the above mentioned reactants.