Determination of gas temperature and thermometric species in inductively coupled plasmas by emission and diode laser absorption

Bol’shakov, Alexander A.; Cruden, Brett A.; Sharma, Surendra P.

doi:10.1088/0963-0252/13/4/019

Cited by 35 publications

(29 citation statements)

References 52 publications

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“…In the discussion given in reference [6] we attributed this violation of the T e -similarity law to the deviation of the electron energy distribution from the Maxwellian equilibrium form. This is in line with the studies [11,12,25].…”

Section: Resultssupporting

confidence: 92%

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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: Resultssupporting

confidence: 92%

“…Generally they can be divided as based on emission spectroscopy [12], laser absorption spectroscopy [12][13][14][15] and laser scattering [16]. In case of emission spectroscopy the T a can for instance be obtained from the rotational temperature of excited molecular species.…”

Section: Introductionmentioning

confidence: 99%

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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“…Plasma temperatures have also been shown to be highly dependent on plasma parameters, leading to an increased desire to understand the trends in energy partitioning as a function of key tunable parameters . Furthermore, ground and excited state species can have substantially different characteristic T R and T V under the same plasma conditions, distributions can strongly deviate from Boltzmann, and different radicals in the same ICP can exhibit distinct internal temperatures .…”

Section: Introductionmentioning

confidence: 99%

“…[10] Plasma temperatures have also been shown to be highly dependent on plasma parameters, leading to an increased desire to understand the trends in energy partitioning as a function of key tunable parameters. [11][12][13][14][15][16][17] Furthermore, ground and excited state species can have substantially different characteristic T R and T V under the same plasma conditions, distributions can strongly deviate from Boltzmann, and different radicals in the same ICP can exhibit distinct internal temperatures. [18,19] One additional consideration is that a single plasma species can be produced via different mechanisms (e.g., direct precursor decomposition vs. recombination), which may ultimately result in very different energy partitioning for that species.…”

Section: Introductionmentioning

confidence: 99%

Determination of internal temperatures within nitric oxide inductively coupled plasmas

Blechle

Hanna

Fisher

2017

Plasma Processes & Polymers

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Determination of molecular temperatures within inductively coupled plasmas is critical to understanding the reactions that drive the chemistry of these systems and the mechanisms involved in surface processing. To investigate such interactions, a dual, in situ broadband absorption and optical emission spectroscopy system was designed; providing insight into neutral and excited state species energetics, specifically rotational (T R ) and vibrational (T V ) temperatures across a broad spectral range (>800 nm). Nitric oxide plasmas have been investigated, where measured T V values were higher than T R values, indicating rotational degrees of freedom are more easily thermalized. Using the imaging of radicals interacting with surfaces technique, surface scatter coefficients were measured for NO radicals, which are discussed in relation to energy partitioning in these systems. K E Y W O R D Sbroadband absorption spectroscopy, energy partitioning, inductively coupled plasmas, nitrogen oxides, optical emission spectroscopy (OES)

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“…1 Many applications of the VCSELs in absorption spectroscopy, such as multi-species gas analysis, gas concentration measurements at high pressures, and gas temperature measurements, are based on their capabilities of being continuously tuned over broad spectral intervals. 2 A continuously tunable narrow-line emission produced by VCSELs is of great advantage for spectroscopic measurements including accurate frequency positioning of absorption lines against frequency markers and line profile studies of gas media in a wide range of gas pressures. Applications of tunable laser diodes in high-resolution spectroscopy and in gas sensing technology require an accurate knowledge of their properties.…”

Section: Introductionmentioning

confidence: 99%

Non-linear frequency tuning of long-wavelength VCSELs: phenomenological description

2006

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We have approximated with second-order polynomials the frequency tuning curves of long-wavelength single-mode VCSELs operating near 1654 and 1512 nm. Fitting coefficients were calculated using experimental data on injection currents and heat sink temperatures required to tune lasers to frequency markers generated by gas absorption lines. To measure temperature tuning rates, we tuned the lasers by temperature sequentially to pairs of absorption lines with known frequency separations. To determine fitting coefficients associated with linear and non-linear frequency tuning, we varied the laser injection currents and temperatures simultaneously in such a way that made a laser emit exactly the same frequency. Linear and non-linear tuning coefficients were then calculated from the data on effects of relatively small and large variation of laser operation parameters on laser frequency. Lasers were calibrated by tuning them on narrow absorption lines with frequencies accurately known from previous studies. The simulated tuning curves were demonstrated to fit frequency markers generated over spectral intervals up to 40 cm -1 with an accuracy of ± 0.10 cm -1 (1654-nm laser) and ± 0.15 cm -1 (1512-nm laser). A temperature dependence of injection current tuning rates of the 1654-nm laser was determined from the best fits of simulated tuning curves to a series of CO 2 absorption lines in the whole operation temperature range of the laser (0 -50 0 C). A simple and accurate method developed to describe tuning properties of long-wavelength VCSELs can be applied to quantitatively characterize any narrow-linewidth tunable laser.

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Determination of gas temperature and thermometric species in inductively coupled plasmas by emission and diode laser absorption

Cited by 35 publications

References 52 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

Determination of internal temperatures within nitric oxide inductively coupled plasmas

Non-linear frequency tuning of long-wavelength VCSELs: phenomenological description

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