Spatially resolved gas temperature measurements by Rayleigh scattering in a microwave discharge

Rousseau, Antoine; Teboul, Eric; Sande, MJ Marco van de; Mullen, J.J.A.M. van der

doi:10.1088/0963-0252/11/1/305

Cited by 24 publications

(39 citation statements)

References 25 publications

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“…The current study can be seen as an extension of the work reported in reference [19] on RyS measurements performed in our laboratory on a SWD delivered by a group from Orsay (Paris-Sud). There are three essential differences:…”

Section: Introductionmentioning

confidence: 74%

“…The results found in reference [19] based on the DECsimilarity law raised some questions. The shape of the axial dependence of the central values of the T a was found to be composed of two branches: a constant (plateau) value close to the launcher and a steep decay close to the plasma end.…”

Section: Introductionmentioning

confidence: 97%

“…However, since we use a 2D iCCD array instead of a 1D photo-diode array in the detection system as in reference [19], we get better insight into the role and strength of FS. (ii) Our RyS scattering experiments are done in conjunction with TS so that apart from the properties of {h} also n e and T e are obtained.…”

Section: Introductionmentioning

confidence: 99%

“…In this way we can trace the energy flow from {e} to {h}. In reference [19] the properties of the electron gas were not known. (iii) In the current work we observe different axial positions of a plasma operated at a constant power whereas in reference [19] the observed position is fixed (7 cm from the gap) while the power is changed.…”

Section: Introductionmentioning

confidence: 99%

“…In reference [19] the properties of the electron gas were not known. (iii) In the current work we observe different axial positions of a plasma operated at a constant power whereas in reference [19] the observed position is fixed (7 cm from the gap) while the power is changed. To get the gas temperature as a function of the axial position, the study in reference [19] relied upon a similarity law that states that the properties of plasmas of the same pressure, radius and composition only depend on the distance to the end of the column (DEC).…”

Section: Introductionmentioning

confidence: 99%

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Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

Hübner

Iordanova

Palomares

et al. 2012

Eur. Phys. J. Appl. Phys.

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Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. Abstract. The axial dependency of the central-axis value of the heavy particle density and temperature of surface-wave plasmas is studied using Rayleigh scattering (RyS). The plasma is generated at a frequency of 2.45 GHz in argon by a surfatron operating under the standard settings of a power of 45 W, a flow rate of 50 sccm and a pressure of 20 mbar. To investigate the effect of the pressure on the gas temperature, we also investigated 6 and 10 mbar plasmas. By using a two-dimensional intensified CCD array we could determine and eliminate the influence of false stray light, a major disturbing factor in the determination of the Rayleigh signal. In order to trace the energy fluxes that determine the gas temperature, we performed Thomson scattering so that the properties of the electron gas are known. It is found that the gas temperature, T a, depends on the wall temperature and the product of the gas pressure and the electron pressure. The latter implies that Ta follows the electron density axially, meaning that it is highest at the launcher and decreases monotonically in the wave propagation direction. The maximum gas temperature of around Ta = 800 K is found close to the launcher for the highest gas pressure of 20 mbar. For lower pressures we find lower Ta values. The extrapolation of Ta toward the end of the plasma column leads to a temperature of about 320 K. This study reveals that, for the argon plasmas under study, the central-axis values of the gas temperature are determined by the balance between the heating of the gas by means of elastic electron collisions and the cooling due to heat conduction from the center to the wall.

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Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

Hübner

Iordanova

Palomares

et al. 2012

Eur. Phys. J. Appl. Phys.

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Optical Diagnostics for Thin Film Processing

Herman

1996

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Mesure des champs de températures et de concentrations des gaz

Piégay¹,

Bailly²

2011

Photoniques

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La température d'un gaz est un phéno-mène statistique, mais c'est l'aspect macroscopique qui permet de comprendre les propriétés optiques des gaz dues aux transitions entre des niveaux éner-gétiques, c'est-à-dire la position des raies spectrales. Les chocs entre molécules et l'effet Doppler dû à la température entraînent l'élargissement des raies lorsque la température et la pression augmentent. Ces effets ont freiné l'apparition des méthodes optiques à cause de la difficulté à modéliser ces phénomènes. Dans le domaine industriel, les mesures relatives des températures, autrement dit les repères, ont souvent été considé-rées comme suffisantes. Des exigences nouvelles sont apparues qui nécessitent de connaître des températures absolues avec précision. Par exemple : les turbines à gaz ont un excellent rendement qui augmente avec la température des gaz. Mais au-delà de 1700 °C, la production de NOx augmente exponentiellement avec la température et il est alors néces-saire de déterminer les profils de tempé-rature à 10 °C près. Les méthodes décrites dans cet article [1] ont déjà été appliquées ou sont en déve-loppement préindustriel dans des laboratoires : seront ainsi présentées les méthodes actives les plus utilisées actuellement, puis des méthodes passives et enfin une nouvelle approche conjuguant ces deux types de méthodes. Méthodes actives Diffusion RayleighCe type de signal provient de la diffusion de la lumière lors des collisions élas-tiques entre les phonons et les molécules du gaz. L'intensité totale diffusée est proportionnelle au nombre de molécules diffusantes. Chaque molécule est caractéri-sée par une section efficace angulaire de diffusion σ R qui dépend des paramètres suivants : -indice de réfraction n i -longueur d'onde du rayonnement monochromatique incident λ -angle ϑ formé par le vecteur incident E et la direction d'observation de la diffusion Rayleigh. L'intensité totale de la lumière diffusée est la somme des différentes intensités de la lumière de chaque molécule pour « m » espèces différentes : en fait, on mesure le nombre de particules diffusantes dans un volume donné et par l'équation d'état, si la pression locale est connue, on remonte à la température [2]. La méthode donne de bons résultats, si l'espèce diffusante est unique, sinon dans le cas des réactions de combustion, le problème est indéterminé. Fluorescence (LIF)Elle Diffusion Raman spontanéeCette méthode utilise la diffusion iné-lastique sur les atomes ou sur les molé-cules. L'onde incidente est diffusée selon deux fréquences u 0 ± u Raman . Par exemple pour l'hydrogène, une excitation de la molécule à 532 nm conduit à l'apparition des raies de Stokes et anti-Stokes qui varient en fonction de la température. La diffusion ayant lieu dans toutes les directions, l'emploi d'une source de forte puissance est nécessaire. Diffusion Raman cohérente (DRASC)C'est la méthode la plus employée en diffusion. On utilise des processus optiques non linéaires à quatre ondes : deux ondes laser ω 1 et ω s sont mélangées dans un milieu possédant un mo...

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Spatially resolved gas temperature measurements by Rayleigh scattering in a microwave discharge

Cited by 24 publications

References 25 publications

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

Optical Diagnostics for Thin Film Processing

Mesure des champs de températures et de concentrations des gaz

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