Spectroscopic diagnostics of an atmospheric microwave plasma for monitoring metals pollution

Woskov, P.; Hadidi, K.; Borras, M.C.; Thomas, Paul D.; Green, K.; Flores, Guadalupe

doi:10.1063/1.1149485

Cited by 19 publications

(10 citation statements)

References 7 publications

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“…1-11 Such an interest stems from their potential and actual use in various applications, including excitation sources for elemental analysis, [12][13][14][15][16][17][18][19] lighting [20][21][22] and, more recently, purification of noble gases obtained from air distillation 23 and remediation of gas effluents detrimental to the environment. 24 -26 A.…”

Section: Introductionmentioning

confidence: 99%

Radial contraction of microwave-sustained plasma columns at atmospheric pressure

Kabouzi

Calzada

Moisan

et al. 2002

Journal of Applied Physics

151

139

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Plasma columns sustained at high enough gas pressures undergo radial contraction as manifested by their glow not entirely filling the radial cross-section of the discharge tube. This phenomenon has been reported with direct current, radio frequency, and microwave discharges. However, its modeling is still incomplete, in particular for rf and microwave discharges, a situation attributed to a lack of experimental data. To fill this gap, we took advantage of the extreme flexibility in terms of field frequency, tube diameter and gas nature of surface-wave sustained discharges to achieve a parametric study of this phenomenon. Special attention was paid to filamentation, specific to rf and microwave discharges, which is the breaking of a single channel of plasma into two or more smaller filaments as a result of the skin effect. We used emission spectroscopy as the main diagnostic means. Electron density was obtained from Stark broadening of the Hβ line, while molecular-band spectra emitted by the OH radical and the N2+ molecule were employed to determine the discharge gas temperature, leading to its radial distribution upon performing Abel inversion. For a given tube radius, contraction is shown to increase with decreasing thermal conductivity of the discharge. As a result, He and N2 discharges are the least contracted, while contraction increases with increasing atomic mass of noble gases. Of all these discharges, the N2 discharge appears to be the closest to local thermodynamic equilibrium.

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Section: Introductionmentioning

confidence: 99%

Radial contraction of microwave-sustained plasma columns at atmospheric pressure

Kabouzi

Calzada

Moisan

et al. 2002

Journal of Applied Physics

151

139

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show abstract

“…The work described in this paper is limited to measurements of Fe I excitation temperatures and NH rotational temperatures (along with overlapping spectral features of the nitrogen second positive band) as a function of axial location inside the microwave torch under identical plasma conditions. It is worth mentioning the work of Woskov et al 14 , who conducted similar spectroscopic diagnostics on an atmospheric microwave plasma. In that study, they extracted T rot from the N 2 + (0,0) first negative system and T exc for Fe I in nitrogen and air plasmas, respectively.…”

Section: Introductionmentioning

confidence: 98%

Investigation of LTE Condition inside a Microwave Induced Nitrogen Plasma Torch

Zaidi

Denning

Urdahl

2014

52nd Aerospace Sciences Meeting

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Optical emission spectroscopy is employed to determine the Fe I excitation temperature (T exc ) and NH rotational temperature (T rot ) inside the microwave excitation region of an atmospheric-pressure, microwave-induced plasma (MIP) torch operating in nitrogen. The plasma is operated at 2.45 GHz at an input power of 900 W with 50 W reflected, and inner and annular auxiliary nitrogen flow rates of 1 slpm each, and annular outer gas nitrogen flow rates of 13 and 25 slpm. Iron is introduced to the inner flow at a concentration of 200 ppm in a 1% HNO 3 solution. Measured relative emission intensities of Fe I emission lines in the band between 370.56 and 376.72 nm are used to determine T exc using a fitting method assuming Boltzmann equilibrium. NH radical A( 3 Π)-X( 3 Σ -) spectra are also employed (in the band between approximately 335 and 343 nm) to determine T rot by comparing measured spectra with spectra calculated using the Specair software. The presence of overlapping spectral features from the N 2 (C-B) second positive band near 337 nm are accounted for by activating these transitions in Specair in addition to the NH transitions. Good agreement between the T exc of Fe and T rot of NH is observed, indicating a local thermodynamic equilibrium (LTE) condition. These temperatures range from approximately 5000 K near the inner gas flow injector to approximately 4000 K at a distance of 25 mm downstream of the injector. The temperatures do not change significantly as a function of the outer gas flow rate.

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“…In the case of MW plasma it has been shown that a resonant cavity is not necessary for sustaining the plasma [11,12]. Large volume microwave plasma was generated using a commercial microwave oven at 2.45 GHz [13].…”

Section: Introductionmentioning

confidence: 99%

Chemical reactor network modeling of a microwave plasma thermal decomposition of H2S into hydrogen and sulfur

Sassi¹,

Amira²

2012

International Journal of Hydrogen Energy

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Spectroscopic diagnostics of an atmospheric microwave plasma for monitoring metals pollution

Cited by 19 publications

References 7 publications

Radial contraction of microwave-sustained plasma columns at atmospheric pressure

Radial contraction of microwave-sustained plasma columns at atmospheric pressure

Investigation of LTE Condition inside a Microwave Induced Nitrogen Plasma Torch

Chemical reactor network modeling of a microwave plasma thermal decomposition of H2S into hydrogen and sulfur

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