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Title: Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge

Abstract

The method of multifrequency laser probing is developed which can be used for diagnostics of the temperature and population of vibrational levels in gas mixtures containing CO molecules in excited vibrational states. The method is tested by studying the dynamics of the gas temperature and population of vibrational levels of the CO molecule in gas mixtures excited by a pulsed discharge. It is shown that the method provides the reduction of the gas temperature measurement error down to 3%. It is found that the population of lower vibrational levels in the CO-O{sub 2} mixture can exceed the population of levels in CO-He and CO-N{sub 2} laser mixtures by several times. (active media)

Authors:
; ; ; ; ; ;  [1]
  1. P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
21466635
Resource Type:
Journal Article
Resource Relation:
Journal Name: Quantum Electronics (Woodbury, N.Y.); Journal Volume: 37; Journal Issue: 3; Other Information: DOI: 10.1070/QE2007v037n03ABEH013157
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARBON MONOXIDE; ELECTRIC DISCHARGES; LASERS; MIXTURES; MOLECULES; POPULATION INVERSION; PULSES; TEMPERATURE MEASUREMENT; VIBRATIONAL STATES; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; DISPERSIONS; ENERGY LEVELS; EXCITED STATES; OXIDES; OXYGEN COMPOUNDS

Citation Formats

Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Rulev, O A, Seleznev, L V, and Sinitsyn, D V. Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge. United States: N. p., 2007. Web. doi:10.1070/QE2007V037N03ABEH013157.
Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Rulev, O A, Seleznev, L V, & Sinitsyn, D V. Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge. United States. doi:10.1070/QE2007V037N03ABEH013157.
Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Rulev, O A, Seleznev, L V, and Sinitsyn, D V. Sat . "Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge". United States. doi:10.1070/QE2007V037N03ABEH013157.
@article{osti_21466635,
title = {Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge},
author = {Ionin, Andrei A and Klimachev, Yu M and Kozlov, A Yu and Kotkov, A A and Rulev, O A and Seleznev, L V and Sinitsyn, D V},
abstractNote = {The method of multifrequency laser probing is developed which can be used for diagnostics of the temperature and population of vibrational levels in gas mixtures containing CO molecules in excited vibrational states. The method is tested by studying the dynamics of the gas temperature and population of vibrational levels of the CO molecule in gas mixtures excited by a pulsed discharge. It is shown that the method provides the reduction of the gas temperature measurement error down to 3%. It is found that the population of lower vibrational levels in the CO-O{sub 2} mixture can exceed the population of levels in CO-He and CO-N{sub 2} laser mixtures by several times. (active media)},
doi = {10.1070/QE2007V037N03ABEH013157},
journal = {Quantum Electronics (Woodbury, N.Y.)},
number = 3,
volume = 37,
place = {United States},
year = {Sat Mar 31 00:00:00 EDT 2007},
month = {Sat Mar 31 00:00:00 EDT 2007}
}
  • It is shown that the addition of molecular oxygen to the working mixture of a pulsed electron-beam sustained-discharge (EBSD) laser CO amplifier leads to the increase in the small-signal gain (SSG) at the fundamental vibrational v+1{yields}v transitions in a CO molecule for v=6-13, which is explained by the increase in the population of vibrational levels. In this case, the temporal parameters of the dynamics decrease at all probed transitions. Variations observed in the SSG dynamics are explained by analysing the kinetic processes of vibrational-vibrational exchange between molecules. The study of lasing parameters of a pulsed CO laser showed that themore » threshold energy input decreased with increasing the oxygen content in the working mixture. It is found that the CO laser efficiency at fundamental transitions increases with the addition of oxygen, the maximum efficiency being achieved at lower energy inputs. It is shown that the pulsed EBSD CO laser can operate on the air working mixture both at the fundamental transitions and the first vibrational overtone transitions v+2{yields}v. (lasers. amplifiers)« less
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  • A self-sustained volume discharge in SF{sub 6} mixtures with C{sub 2}H{sub 6}, He, and Ne preliminarily irradiated by CO{sub 2} laser pulses was investigated. The radiation energy density absorbed by SF{sub 6} in the discharge ignition region amounted to 6.5 J atm{sup -1} cm{sup -3}. The discharge structure and the current distribution in the discharge gap were found to change radically with increasing the time delay between the laser and discharge pulses. In particular, brightly glowing narrow channels are formed at the boundary of the irradiation region. The observed effect is shown to arise from the development of a shock-wavemore » process due to a temperature jump at the boundary between the irradiated and unirradiated gas. The velocities of shock wave propagation and the main thermodynamic gas parameters in the perturbation region were calculated. A comparison was made between the calculated and measured velocities of the shock waves. (special issue devoted to the 90th anniversary of a.m. prokhorov)« less
  • The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume ({approx}18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts ({approx}1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving {approx}6.5more » kJ L{sup -1} atm{sup -1} per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O{sub 2} : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O{sub 2}(a{sup 1{Delta}}{sub g}) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value {approx}3% for W {approx} 1.0 kJ L{sup -1} atm{sup -1} is in agreement with the theoretical estimate. Theoretical calculations performed for W {approx} 6.5 kJ L{sup -1} atm{sup -1} at a fixed temperature show that the singlet-oxygen yield may be {approx}20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)« less
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