Nickolay A. Khvatov

Sub- and supersonic COILs driven by a jet-type singlet oxygen generator

The experimental results of study of sub- and supersonic chemical oxygen-iodine lasers (COIL) based on the jet type singlet oxygen generator are presented. The progress in the high pressure jet type singlet oxygen generators allowed to develop the compact highly efficient COIL. The different types of the mixing schemes were tested in supersonic COIL based on the high pressure jet singlet oxygen generator. The preliminary cooling of the active medium by mixing of oxygen with the cold buffer nitrogen gas results in high efficiency operation of the small scale COIL with subsonic and supersonic gas flow in the laser cavity. In COIL with the fast axial gas flow the chemical efficiency more than 20% was achieved.

Dissociation of Molecular Iodine in a Flow Tube in the Presence of O2(1Σ) Molecules

Molecular iodine dissociates in the presence of O(2)((1)Δ) and O(2)((1)Σ) molecules, but the mechanism of this process is not completely understood. In this paper, using flow tube experiments, we studied the initiation stage of iodine dissociation. Absolute spectral irradiance measurements were employed for measurements of concentrations of electronically excited particles. It was found that under the present experimental conditions initiation of iodine dissociation is mainly caused by reaction O(2)((1)Σ) + I(2) → O(2)((3)Σ) + 2I with a rate constant of (9.3 ± 2.0) × 10(-11) cm(3) s(-1). An appreciable role of the O(2)((1)Δ) molecule as the dissociation initiator has not been observed. It was observed that the growth rate of iodine atoms sharply accelerated when the concentration of I((2)P(1/2)) atoms approached 2 × 10(-4) of O(2)((1)Δ) concentration or when production rates of O(2)((1)Σ) molecules in reactions O(2)((1)Δ) + I((2)P(1/2)) and O(2)((1)Δ) + O(2)((1)Δ) became equal.

Lasing performance of a chemical oxygen iodine laser (COIL) with advanced ejector nozzle banks

Experimental lasing results for the Chemical Oxygen Iodine Laser, (COIL), using four different ejector nozzle configurations are presented. These nozzle banks differed in the location of Iodine injection, the area of the oxygen nozzles, and the nozzle contour of the primary driver nitrogen. The aerodynamic choking of the oxygen jets caused by the under expanded primary driver nitrogen resulted in a reduction of the O2 (1(Delta) ) yield and chemical efficiency. Dilution of chlorine with helium in the ratio of 1:1 reduces the partial pressure of oxygen and increases the velocity resulting in a chemical efficiency of 25% at 250 mmoles/sec and 23% at 500mmoles/sec of driver nitrogen respectively. The corresponding Pitot pressures are 50 and 90 torr.

Results of experiments on iodine dissociation in active medium of oxygen-iodine laser

Results of experiments on dissociation of iodine molecules in the presence of singlet oxygen molecules are presented for wide range of oxygen-iodine media composition. Rate constants values have been obtained: 4.3⋅10-17cm3/s for the reaction O2(1Δ)+O2(1Δ)→O2(1Σ) +О2(3Σ) − (1), 2.8⋅10-13 cm3/s for the reactionO2(1Δ)+I(2P1/2)→O2(1Σ)+I(2P3/2) − (4) and 8.3⋅10-11 cm3/s for the reaction O2(1Σ) +I2→О2(3Σ)+2I − (2). Analysis of experiments shows that for the wide range of oxygen-iodine medium composition the dissociation occurs via the chain of reactions (1), (2), O2(1Δ)+I(2P3/2)→О2(3Σ)+I(2P1/2), (4) and via cascade process I2+I(2P1/2)→I2(v)+I(2P3/2), I2(v)+O2(1Δ)→2I+О2(3Σ). Contributions of each mechanism in the dissociation of the iodine are comparable for the typical composition of the active medium of the supersonic chemical oxygen-iodine laser. The experiments did not reveal the contribution of vibrationally excited oxygen molecules in the dissociation of iodine. Thus, the experiments and the following conclusions are fully confirmed iodine dissociation mechanism previously proposed by Heidner et al. (J. Phys. Chem., 87, 2348 (1983)).

Experimental study of iodine dissociation in active medium of oxygen-iodine laser

Results of experiments on dissociation of iodine molecules in oxygen-iodine laser medium are presented. Rates constant of key reactions have been reexamined. The experiments confirmed mechanism of iodine dissociation proposed in (J. Phys. Chem., 87, 2348 (1983)). The experiments did not reveal the contribution of vibrationally excited oxygen molecules or three body reactions in the dissociation of iodine.