Influence of an iodine donor on the output energy of a pulsed oxygen-iodine laser

Vagin, N. P.; Золотарев, В А; Kryukov, P. G.; Pazyuk, V S; Podmar’kov, Yu P; Фролов, М П; Yuryshev, Nikolai N

doi:10.1070/qe1991v021n01abeh003702

Cited by 11 publications

(3 citation statements)

References 3 publications

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“…Methyl iodide (CH 3 I) that dissociates efficiently in a discharge was used as an iodine precursor. There are examples of successful use of CH 3 I in somewhat similar experimental conditions [16,17]. Homogeneous and heterogeneous iodine atom recombination resulted in increase of I 2 content along the flow which is undesirable.…”

Section: Methodsmentioning

confidence: 99%

Study of iodine atom production in Ar/CH₃I dc glow discharges

Dem'yanov

Кочетов

Napartovich

et al. 2010

Plasma Sources Sci. Technol.

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A transverse flow dc glow discharge in Ar/CH 3 I mixtures was modeled using a plug-flow approximation and plasma evolution was computed within a frame of reference moving with the gas. Reduced electric field as a function of transportation length was determined using the condition of a constant power density in the discharge. Cathode fall (CF) was found by comparing modeled and experimental discharge voltages. It was shown that conditions in the plasma column are nearly optimal for iodine atoms production with the lowest required energy and larger energies observed in the experiment are due to energy loss in the CF. In the experiment, concentrations of iodine molecules were measured downstream of the discharge using laser-induced fluorescence. Iodine flow at the exit of the discharge generator consisted of 80-90% of iodine atoms and only of 10-20% of iodine molecules. A good agreement between modeled and measured concentrations was found.

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Section: Methodsmentioning

confidence: 99%

Study of iodine atom production in Ar/CH₃I dc glow discharges

Dem'yanov

Кочетов

Napartovich

et al. 2010

Plasma Sources Sci. Technol.

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“…Some arguments in favour of the appearance of excited atoms (the upper 1.315 µm laser level) are given a Authors of [23] have measured the backward reaction 13 rate at T = 150 K and concluded that the forward rate constant does not depend on temperature. b Experimental estimations in [13] provided the range for this constant value (3-5)×10 −11 cm 3 s −1 . The value taken in our model is a result of a fit procedure, which gives the best agreement with experiment.…”

Section: Cross Sections For Electron Scattering From Cf 3 I Moleculesmentioning

confidence: 99%

Mechanism of pulse discharge production of iodine atoms from CF₃I molecules for a chemical oxygen–iodine laser

Кочетов

Napartovich

Vagin

et al. 2009

J. Phys. D: Appl. Phys.

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The pulsed chemical oxygen–iodine laser (COIL) development is aimed at many new applications. Pulsed electric discharge is most effective in turning COIL operation into the pulse mode by instant production of iodine atoms. A numerical model is developed for simulations of the pulsed COIL initiated by an electric discharge. The model comprises a system of kinetic equations for neutral and charged species, electric circuit equation, gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are found by solving the electron Boltzmann equation, which is re-calculated in a course of computations when plasma parameters changed. The processes accounted for in the Boltzmann equation include excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron–ion recombination, electron–electron collisions, second-kind collisions and stepwise excitation of molecules. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. Results of numerical simulations are compared with experimental laser pulse waveforms. It is concluded that there is satisfactory agreement between theory and the experiment. The prevailing mechanism of iodine atom formation from the CF3I donor in a very complex kinetic system of the COIL medium under pulse discharge conditions, based on their detailed numerical modelling and by comparing these results both with experimental results of other authors and their own experiments, is established. The dominant iodine atom production mechanism for conditions under study is the electron-impact dissociation of CF3I molecules. It was proved that in the conditions of the experiment the secondary chemical reactions with O atoms play an insignificant role.

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“…A special attention must be paid however to potential reactions of molecular or atomic (in case of the discharge oxygen-iodine laser) oxygen with a residual, undecomposed CF 3 I, and also CF 3 radicals. For example, a CF 3 O 2 radical produced in this way is a serious quencher of both singlet oxygen (k = 2.3 x 10 -11 cm 3 s -1 ) and excited atomic iodine (2.5 x 10 -11 cm 3 s -1 ) [1316].…”

Section: Conclusion and Final Remarksmentioning

confidence: 99%

Production of iodine atoms by RF discharge decomposition of CF₃I

Jirásek¹,

Schmiedberger²,

Čenský³

et al. 2011

J. Phys. D: Appl. Phys.

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A generation of atomic iodine by dissociation of CF 3 I in RF discharge was studied experimentally in a configuration ready for direct use of the method in the oxygen-iodine laser. The discharge was ignited between the coaxial electrodes with a radial distance of 3.5 mm in a flowing mixture of 0.1-0.9 mmol.s -1 of CF 3 I and 0.5-6 mmol.s -1 of buffer gas (Ar, He) at a pressure of 2-3 kPa. The discharge stability was improved by different approaches so that the discharge could be operated up to a RF source limit of 500 W without sparking. The gas leaving the discharge was injected to the subsonic or supersonic flow of N 2 and concentration of generated atomic iodine and gas temperature were measured downstream of the injection. An inhomogeneous distribution of the produced iodine atoms among the injector exit holes was observed, which was attributed to a different gas residence time corresponding to each hole. The dissociation fraction was better with pure argon as a diluting gas than in the mixture of Ar-He, although the variation in the Ar flow rate had no significant effect on the CF 3 I dissociation. The dissociation fraction calculated from the atomic iodine concentration measured several centimeters downstream of the injection was in the range of 7 to 30% when the absorbed electric energy ranged from 200 to 4000 J per 1 mmol of CF 3 I. Corresponding values of the fraction of power spent on the dissociation decreased from 8 to 2%.% and the energy cost for one iodine atom increased from 30 to 130 eV. Due to a possible high rate of the atomic iodine loss by recombination after leaving the discharge, these values are considered as lower limits of those achieved in the discharge.

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Influence of an iodine donor on the output energy of a pulsed oxygen-iodine laser

Cited by 11 publications

References 3 publications

Study of iodine atom production in Ar/CH₃I dc glow discharges

Study of iodine atom production in Ar/CH₃I dc glow discharges

Mechanism of pulse discharge production of iodine atoms from CF₃I molecules for a chemical oxygen–iodine laser

Production of iodine atoms by RF discharge decomposition of CF₃I

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Influence of an iodine donor on the output energy of a pulsed oxygen-iodine laser

Cited by 11 publications

References 3 publications

Study of iodine atom production in Ar/CH3I dc glow discharges

Study of iodine atom production in Ar/CH3I dc glow discharges

Mechanism of pulse discharge production of iodine atoms from CF3I molecules for a chemical oxygen–iodine laser

Production of iodine atoms by RF discharge decomposition of CF3I

Contact Info

Product

Resources

About

Study of iodine atom production in Ar/CH₃I dc glow discharges

Study of iodine atom production in Ar/CH₃I dc glow discharges

Mechanism of pulse discharge production of iodine atoms from CF₃I molecules for a chemical oxygen–iodine laser

Production of iodine atoms by RF discharge decomposition of CF₃I