Radio-Frequency Plasma Generation of Singlet Oxygen in O2 and O2:AR (HE) Mixtures

Рахимова, Т. В.; Kovalev, A. S.; Braginsky, O.V.; Klopovsky, K. S.; Lopaev, Dmitry; Mankelevich, Yu. A.; Proshina, O. V.; Rakhimov, A. T.; Vasilieva, A.N.

doi:10.2514/6.2003-4306

Cited by 20 publications

(46 citation statements)

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“…The experimental measurements were described in detail elsewhere 7,8,11 . The inner surface of the tube in discharge region and somewhat behind the electrodes was coated by HgO to remove atomic oxygen.…”

Section: Resultsmentioning

confidence: 99%

“…At the last years many efforts of the different scientific teams were directed on the experimental and theoretical study of rf discharges (in capacitive or inductive modes) to decide mentioned above problems 6-12 . It was shown in our previous studies that the O 2 (a 1 ∆ g ) concentration in rf discharge plasma is saturated with the increase of both pressure and specific energy input. The three-body mechanism of fast O 2 (a 1 ∆ g ) quenching by oxygen atoms (OA) has been revealed 7,11 and explained the saturation. Indeed, the increase of pressure and energy input results in the increase of oxygen atom concentration and thereby the increase of the rate of three-body deactivation process 7,8,12 . In the present paper the experimental and theoretical study of the rf frequency influence on the discharge structure and the O 2 (a 1 ∆ g ) yield was carried out in the discharge tubes with and without HgO coating.…”

Section: Introductionmentioning

confidence: 99%

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Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Рахимова

Kovalev

Lopaev

et al. 2006

XVI International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

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This work is devoted to the experimental and theoretical study of rf frequency influence on the discharge structure and the O 2 (a 1 ∆ g ) yield in a rf discharge in the tubes with HgO coating for removing atomic oxygen to avoid fast O 2 (a 1 ∆ g ) quenching. Two series of experiments were carried in two discharge sets up: 1 -tube of large diameter of 14 mm, electrode length of 30 cm; 2 -tube of small diameter of 7 mm, electrode length of 10 cm. In the first series, the increase of rf frequency from 13.56 MHz to 81 MHz resulted in the singlet oxygen (SO) yield Y >15% at such high oxygen pressure as 10 Torr. 2D self-consistent model was developed to simulate the rf discharges in gas flow in a wide rage of discharge parameters both with and without HgO coating. Results of the simulation agreed very well with the experimental data. It is shown that at the high rf frequency the discharge operates in a mode of the normal current density so that the energy absorbed by electrons from the rf field increases with the frequency. In the second series we scaled up the rf discharge on the pd parameter (p-pressure, d-tube diameter) to increase the oxygen pressure. The pd discharge scaling at the high rf frequency allowed to reach the O 2 (a 1 ∆ g ) yield Y > 15% at oxygen pressure up to ~17 Torr. The effect of NO admixture on the O 2 (a 1 ∆ g ) production has been studied in series 2 at rf frequency of 160 MHz. NO admixture (5÷20%) results in the noticeable increase in the O 2 (a 1 ∆ g ) yield in comparison with the discharge tube without HgO coating. It is shown that combination of O 2 + NO mixture with HgO coating of the discharge tube walls provides the most optimal O 2 (a 1 ∆ g ) production with the efficiency up to 7-10 % and allows to reach the threshold yield in 15 % at oxygen pressure even above ~20 Torr.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Рахимова

Kovalev

Lopaev

et al. 2006

XVI International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

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“…The long lifetime of O 2 ͑ 1 ⌬͒ ͑60 min͒ and robustness against quenching enables transport over long distances to the laser cavity. [10][11][12][13][14][15][16][17][18][19][20][21][22] Recently, positive gain was reported in atomic iodine resulting from electric discharge produced O 2 ͑ 1 ⌬͒, 23,24 followed by laser demonstrations. 8,9 Recent and ongoing investigations have shown that substantial yields of O 2 ͑ 1 ⌬͒ can be generated by an appropriately tailored electric discharge, typically in mixtures with rare gas diluents such as He.…”

Section: Introductionmentioning

confidence: 99%

Production of O2(Δ1) in flowing plasmas using spiker-sustainer excitation

Babaeva

Arakoni

Kushner

2006

Journal of Applied Physics

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Articles you may be interested inLaser induced fluorescence of the ferroelectric plasma source assisted hollow anode dischargeIn chemical oxygen iodine lasers ͑COILs͒, oscillation at 1.315 m in atomic iodine ͑ 2 P 1/2 → 2 P 3/2 ͒ is produced by collisional excitation transfer of O 2 ͑ 1 ⌬͒ to I 2 and I. Plasma production of O 2 ͑ 1 ⌬͒ in electrical COILs ͑eCOILs͒ eliminates liquid phase generators. For the flowing plasmas used for eCOILs ͑He/ O 2 , a few to tens of torr͒, self-sustaining electron temperatures, T e , are 2 -3 eV whereas excitation of O 2 ͑ 1 ⌬͒ optimizes with T e = 1 -1.5 eV. One method to increase O 2 ͑ 1 ⌬͒ production is by lowering the average value of T e using spiker-sustainer ͑SS͒ excitation where a high power pulse ͑spiker͒ is followed by a lower power period ͑sustainer͒. Excess ionization produced by the spiker enables the sustainer to operate with a lower T e . Previous investigations suggested that SS techniques can significantly raise yields of O 2 ͑ 1 ⌬͒. In this paper, we report on the results from a two-dimensional computational investigation of radio frequency ͑rf͒ excited flowing He/ O 2 plasmas with emphasis on SS excitation. We found that the efficiency of SS methods generally increase with increasing frequency by producing a higher electron density, lower T e , and, as a consequence, a more efficient production of O 2 ͑ 1 ⌬͒.

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“…The filter has a 11-nm bandwidth (399-410 nm), which allows capture of (3,7), (5,8), (6,8), (8,9),(10,10), (11,10), (2,8), (5,8), (4,9). The camera was set up such that the optical axis was perpendicular to the grounded plate of discharge configuration #3, such that the O 2 * emission from 0.125" holes in the plate could be collected.…”

Section: Diagnostics Suite For Excited Oxygen and Oxygen Atom Measurmentioning

confidence: 99%

Improved production of O 2 (a¹Δ) in capacitively coupled radio-frequency discharges

et al. 2008

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Experimental investigations of radio-frequency discharges in O 2 /He/NO mixtures in the pressure range of 1-100 Torr and power range of 0.1-1.2 kW have indicated that O 2 (a 1 ∆) production is a strong function of geometry, excitation frequency, pressure and diluent ratio. The goal of these investigations was maximization of both the yield and flow rate (power flux) of O 2 (a 1 ∆) in order to produce favorable conditions for application to an electric oxygeniodine laser (EOIL). At lower pressures, improvements in yield are observed when excitation frequency is increased from 13.56 MHz. As pressure is increased, increasing excitation frequency in the baseline configuration becomes detrimental, and yield performance is improved by reducing the discharge gap and increasing the diluent ratio. Numerous measurements of O 2 (a 1 ∆), oxygen atoms, and discharge excited states are made in order to describe the discharge performance dependent on various parameters.

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Radio-Frequency Plasma Generation of Singlet Oxygen in O2 and O2:AR (HE) Mixtures

Cited by 20 publications

References 2 publications

Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Production of O2(Δ1) in flowing plasmas using spiker-sustainer excitation

Improved production of O 2 (a¹Δ) in capacitively coupled radio-frequency discharges

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Radio-Frequency Plasma Generation of Singlet Oxygen in O2 and O2:AR (HE) Mixtures

Cited by 20 publications

References 2 publications

Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Pressure scaling of an electro-discharge singlet oxygen generator (ED SOG)

Production of O2(Δ1) in flowing plasmas using spiker-sustainer excitation

Improved production of O 2 (a1Δ) in capacitively coupled radio-frequency discharges

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Product

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Improved production of O 2 (a¹Δ) in capacitively coupled radio-frequency discharges