Combined experimental and theoretical studies of i₂ dissociation in supersonic COILs

The present paper deals with the long standing problem of understanding the dissociation of I₂ molecules in chemical oxygen-iodine lasers (COILs). The dissociation was studied at the optical axis of a supersonic COIL via detailed measurements and three dimensional computational fluid dynamics calculations. Comparing the measurements and the calculations enabled critical examination of previously proposed dissociation mechanisms and suggestion of a mechanism consistent with the experimental and theoretical results obtained in a supersonic COIL for the gain, temperature and I₂ dissociation fraction at the optical axis. The suggested mechanism combines the recent scheme of Azyazov and Heaven (AIAA J. 44, 1593 (2006)), where I₂(A' ³∏_2u), I₂(A³∏ _1u) and O₂(a¹Δ_g, v) are significant dissociation intermediates, with the "standard" chain branching mechanism of Heidner et al. (J. Phys. Chem. 87, 2348 (1983)), involving I(²P_1/2) and I₂(X¹∑ _g⁺,v).