Approximate analytic solution for the dissociation of molecular iodine in the presence of singlet oxygen

Perram, Glen P.

doi:10.1002/kin.550270808

Cited by 58 publications

(21 citation statements)

References 28 publications

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“…An effective binary diffusion model is used to describe concentration and pressure contributions to mass diffusion, an important process in the low density COIL flowfield. The COIL chemistry is described either using a 10 species, 22 reaction or a 13 species, 52 reaction finiterate mechanism [1] that models the gas phase chemical kinetic processes generating the population inversion in atomic iodine necessary for laser oscillation. References providing additional details regarding the application of GASP to this problem may be found in Madden, et al [2,3] …”

Section: Problem and Methodologymentioning

confidence: 99%

Chemical Oxygen-Iodine Layer Device Simulation Using the 3D, unsteady Navier-Stokes Equations

Madden

2007

2007 DoD High Performance Computing Modernization Program Users Group Conference

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The time-dependent, chemically reacting, viscous fluid dynamics within the chemical oxygen-iodine laser (COIL) flowfield are simulated using the unsteady, laminar, multi-component Navier-Stokes equations. The solutions of these equations are generated within simulations of COIL hardware at standard operating conditions; conditions predicted in previous simulations to be unsteady. These current simulations ascertain the effect of the flow unsteadiness upon the laser gain through Doppler broadening of the spectral lineshape induced by the bulk movement of the gas. The results from the simulations demonstrate that the presence of bulk flow rotation associated with the unsteady vortex generation influences the temperature determined from the resulting lineshapes; this result has direct implications for experiments where spectroscopically measured lineshapes are utilized to determine flow temperatures. Additional simulations are used to test varying fidelity within the COIL finite-rate chemistry mechanism in the presence of the flow unsteadiness and H 2 O vapor condensation. The same unsteady, laminar, multi-component Navier-Stokes simulation methodology is applied to new COIL mixing nozzle concepts with the goal of utilizing the unsteadiness flow to improve device performance. Experimental planar laser induced iodine fluorescence data for these nozzle concepts are directly compared to simulation data in a newly developed methodology for COIL model validation.

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Section: Problem and Methodologymentioning

confidence: 99%

Chemical Oxygen-Iodine Layer Device Simulation Using the 3D, unsteady Navier-Stokes Equations

Madden

2007

2007 DoD High Performance Computing Modernization Program Users Group Conference

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“…Following the generally accepted COIL kinetics, 16 the excited iodine atoms are mainly deactivated in the following reactions:…”

Section: B Coil Active Medium Characteristicsmentioning

confidence: 99%

Properties of O2(Δ1)–I(P21/2) laser medium with a dc glow discharge iodine atom generator

Mikheyev

Azyazov

2008

Journal of Applied Physics

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Experiments were carried out in a flow cell apparatus under conditions corresponding to those of a typical oxygen-iodine laser. The cell was equipped with a chemical jet type singlet oxygen generator and an electric discharge for the production of iodine atoms. The properties of the discharge generator and the active medium were studied using laser-induced fluorescence and emission spectroscopy. I2 or CH3I entrained in a carrier flow of Ar were used as atomic iodine precursors. About 50% of the iodine contained in CH3I molecules was extracted in the generator. 2.6% of the electric power loaded into the discharge was used in CH3I dissociation. Right after the discharge 80%–90% of the iodine flow consisted of atoms. However, due to recombination during transport, only 20%–50% of atoms remained at the point of injection into the oxygen flow. A straightforward comparison of two methods of oxygen-iodine medium production—conventional, by means of I2 dissociation in the singlet oxygen flow and with iodine atoms produced externally in the electric discharge—was performed. It was found that the lifetime for the energy stored in singlet oxygen was about 30% longer, when atomic iodine was produced from CH3I in the discharge, as compared to the conventional chemical dissociation of I2 in the singlet oxygen flow.

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“…This set of reactions was adopted in the standard kinetics package 20,21 which is used for most computational simulations of COIL devices. Heidner's mechanism assumes that vibrationally excited I 2 (X) is the immediate precursor to atomic iodine in COIL systems and hence that the dissociation is a two step process requiring at least two 0 2 ( 1 A) molecules to dissociate one 12. Recent kinetic measurements and modeling studies carried out by Heaven et al 17 indicate that these assumptions are invalid, and that electronically excited 1 2 (A') is the I atom precursor.…”

Section: Chemical Reaction Schemesmentioning

confidence: 99%

Modeling of the gain, temperature, and iodine dissociation fraction in a supersonic chemical oxygen-iodine laser

Barmashenko

Bruins

Furman

et al. 2002

Gas and Chemical Lasers and Intense Beam Applications III

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We report on a simple one-dimensional model developed for the fluid dynamics and chemical kinetics in the chemical oxygen iodine laser (COIL). Two different 12 dissociation mechanisms are tested against the performance of a COIL device in our laboratory. The two dissociation mechanisms chosen are the celebrated mechanism of Heidner and the newly suggested mechanism of Heaven. The gain calculated using Heaven's dissociation mechanism is much lower than the measured one. Employing Heidner's mechanism, a surprisingly good agreement is obtained between the measured and calculated gain and temperature over a wide range of the flow parameters. Other predictions of the model (larger mixing efficiency and higher temperature with a leak opened downstream of the resonator and gain decrease along the flow) are also in agreement with the experimental observations.

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Approximate analytic solution for the dissociation of molecular iodine in the presence of singlet oxygen

Cited by 58 publications

References 28 publications

Chemical Oxygen-Iodine Layer Device Simulation Using the 3D, unsteady Navier-Stokes Equations

Chemical Oxygen-Iodine Layer Device Simulation Using the 3D, unsteady Navier-Stokes Equations

Properties of O2(Δ1)–I(P21/2) laser medium with a dc glow discharge iodine atom generator

Modeling of the gain, temperature, and iodine dissociation fraction in a supersonic chemical oxygen-iodine laser

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