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A numerical two-dimensional spatial model is used to describe experimental results from the literature on the concentrations of O2(a1Δg) and O2(b1 ) in a fast-flowing gas system free of plasma–chemical processes with the participation of electrons and ions. The concentration profiles of O2(a1Δg) and O2(b1 ) are found to depend on gas pressure, the fraction of oxygen atoms in O/N2 mixtures, and additions of O2 to the gas mixture. The model emphasizes the need to consider detailed vibrational kinetics of ozone and its formation on the surfaces of tube walls. A new interpretation is proposed for the three-body recombination of oxygen atoms on M = N2, O2, allowing for the reverse dissociation of the produced highly excited molecules. The resulting functional dependence of recombination rate coefficient krec(T) is obtained and agrees well with the available measured temperature dependences krec(T). Pathways for the subsequent relaxation of excited oxygen molecules and atoms are identified. [ABSTRACT FROM AUTHOR]

Plasmachemical and heterogeneous processes of generation and loss of ozone in the atmosphericpressure dielectric barrier discharge in oxygen are studied theoretically. Plasmachemical and electronic kinetics in the stage of development and decay of a single plasma filament (microdischarge) are calculated numerically with and without allowance for the effects of ozone vibrational excitation and high initial ozone concentration. The developed analytical approach is applied to determine the output ozone concentration taking into account ozone heterogeneous losses on the AlO dielectric surface. Using the results of quantummechanical calculations by the method of density functional theory, a multistage catalytic mechanism of heterogeneous ozone loss based on the initial passivation of a pure AlO surface by ozone and the subsequent interaction of O molecules with the passivated surface is proposed. It is shown that the conversion reaction 2O → 3O of a gas-phase ozone molecule with a physically adsorbed ozone molecule can result in the saturation of the maximum achievable ozone concentration at high specific energy depositions, the nonstationarity of the output ozone concentration, and its dependence on the prehistory of ozonizer operation. [ABSTRACT FROM AUTHOR]

Available data on the kinetic processes in H-O-O( aΔ) mixtures are analyzed theoretically, and the ranges in which the rate constants of these processes can vary are determined. The processes of energy transformation in an O( aΔ)-H-H-HO system in the approximations of the fast and slow (in comparison with the vibrational relaxation time of the HO radical) quenching of the electronically excited state are considered. The experiments on the quenching of singlet delta oxygen (SDO) molecules O( aΔ) excited in a microwave discharge at a temperature of 300 K and pressure of 6 Torr in a lean hydrogen-oxygen mixture are simulated (by a lean fuel mixture is meant a mixture in which the ratio of the fuel to the oxidizer mass fraction is less than the stoichiometric ratio, which is 2: 1 for a hydrogen-oxygen mixture). It is shown that, over the experimental observation times, the SDO quenching frequency depends on the concentration of molecular hydrogen, the residual odd oxygen fraction in the gas flow, and the ratio between the rate constants of kinetic processes involving HO and HO* radicals. Simulations of the microwave discharge and the transport of excited oxygen along the drift tube make it possible to determine the residual odd oxygen concentration in the gas flow. Recommendations on the choice of the rate constants for the O( aΔ) + HO) A″, v″ = 0) ↔ O + HO*( A′, v′ = 1), HO*( A′v′ ≤ 1) + O( aΔ) → HO*( A′,v′ ≥ 6) + O, and HO*( A′,v′ ≤ 1) + O( aΔ) → H + O + O processes are given. It is shown that, in the case of slow quenching in a H-O-O( aΔ) mixture at a low temperature, the intensity of hydrogen oxidation is enhanced due to the reaction + HO*( A′,v′ ≤ 1) + O(Δ) → H + O + O. [ABSTRACT FROM AUTHOR]

Results of experiments on the quenching of singlet delta oxygen (SDO) O( aΔ) in lean hydrogen-oxygen mixtures at temperatures of 500-1020 K and pressures of 26-90 Torr behind the shock front are analyzed theoretically. The processes affecting SDO quenching are simulated taking into account the temporal characteristics of the experiment and various mechanisms of energy transformation in an O( aΔ)-H-H-HO system. It is demonstrated that the approximations of both fast and slow (in comparison with the vibrational relaxation time of the HO radical) quenching of the electronically excited state of the radical are in good agreement with the experimental data on the effective rate constant of SDO deexcitation at temperatures of up to 700 K. It is shown that the available data on the kinetics of reactions involving SDO in H-O-O( aΔ) mixtures overestimate the SDO quenching rate in comparison with the experimental results obtained at temperatures above 850 K. The decrease in the rate constant of the reaction H + O( aΔ)→ products by one order of magnitude makes it possible to match the simulation results to the experimental data. The existence of the processes restoring SDO in the presence of atomic hydrogen that are not considered in the current models of the H-O-O( aΔ) kinetics is supposed. [ABSTRACT FROM AUTHOR]

The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D ( r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found. [ABSTRACT FROM AUTHOR]

A parametric analysis has been carried out to discover how the concentration of atomic oxygen in the O2: O2 (1Δg): O flow and the degree of predissociation and concentration of molecular iodine in the I2: He mixture affect the temperature regime and the formation of the inverse population at the atomic iodine laser transition at elevated pressures of P = 5–10 Torr in a simulated system with the axial injection of an I2: He mixture in the EDSOG-excited oxygen flow. [ABSTRACT FROM AUTHOR]