Modeling of chemical generation of atomic iodine for chemical oxygen-iodine laser

Abstract

The mathematical modeling of reaction systems for chemical generation of atomic iodine is presented. This process can be applied in the chemical oxygen-iodine laser (COIL), where it can save a substantial part of energy of singlet oxygen and so increase the laser output power. The parametric study of the production of atomic fluorine and subsequently atomic iodine in dependence on the pressure and dilution with inert gas was made. The calculation of the interaction between produced atomic iodine and singlet oxygen was made with four different mixing/reacting schemes. iodine 1 , and discharge dissociation of alkyliodides2 were tested to generate atomic iodine for COIL. We proposed a method of chemical generation of atomic iodine for COIL based on the reaction of hydrogen iodide with chemically generated atomic fluorine or chlorine. 3 ' 4 Atomic iodine produced in this way can then undergo the energy transfer from singlet oxygen contained in the gas flow. Because the reaction of hydrogen iodide with both atomic fluorine and chlorine is very fast, the chemical efficiency of atomic iodine production is determined by the efficiency of the preparation of atomic fluorine (in reaction F2 + NO) or chlorine (C10 2 + NO). To estimate the efficiency of these processes, a simplified one-dimensional (l-D) kinetic model was proposed and numerically solved for both reaction systems. 4 In this modeling, a constant gas velocity and constant total enthalpy were assumed, and the diffusion of species and heat transfer along the flow were neglected. The calculations were performed for the conditions that correspond with the subsonic channel, i.e., upstream the nozzle throat, in the supersonic COIL device operated in our laboratory: the total pressure of 4 kPa, temperature of 300 K, velocity of 200 m/s. The results following from this modeling showed that atomic fluorine is produced with a rate that is too slow to realize this process directly in the subsonic channel. More promising results were obtained by the modeling of the reactions with atomic chlorine, resulting in a sufficient production rate of atomic iodine. However, it is a disadvantage of this process, that the produced atoms are rapidly recombinated in the presence of NO 2. The results of 1-D modelling of this system 4 are only in some respect in quantitative accordance with the results from the experiments. 3 ' 5 The new results of modeling of the production of atomic iodine via atomic fluorine are presented in this paper, including the dependence on the initial pressure and dilution with the inert gas. The results of calculations of the interaction between produced atomic iodine and singlet oxygen are also included, considering four different mixing/reacting schemes.