Two-temperature chemically non-equilibrium modelling of an<b><i>air</i></b>supersonic ICP

Morsli, Mbark El; Proulx, Pierre

doi:10.1088/0022-3727/40/16/010

Cited by 24 publications

(11 citation statements)

References 63 publications

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“…At the beginning of the 1980s, Chen et al [38] introduced a two-temperature model of dc arcs. Non-LTE also occurs when injecting a cold gas into a plasma jet [39], when quenching the plasma to promote the formation of chemical species that are produced by recombining radicals in a given temperature range [40], near electrodes and walls [41][42][43][44][45][46][47][48], in expanding plasma jets under soft vacuum [49][50][51][52][53] and in arc jets [54]. A further example is the new spray device of Sulzer-Metco, devoted to the deposition of columnar structures from the vapour phase in a chamber at a few tens of pascals [55].…”

Section: Non-lte and Chemical Equilibriummentioning

confidence: 99%

Treatment of non-equilibrium phenomena in thermal plasma flows

Rat¹,

Murphy²,

Aubreton³

et al. 2008

J. Phys. D: Appl. Phys.

131

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Thermal plasma flows provide a uniquely high specific enthalpy source that is well suited to transformation of matter, often via phase changes. As a consequence, numerous thermal-plasma-based processes have been developed to, for example, destroy pollutants, modify surfaces (e.g. cutting and welding), synthesize nanostructures and deposit functionalized nanostructured coatings. In many cases, departures from equilibrium (both thermal and chemical) occur in regions of such plasmas; for example, in electrode erosion phenomena or in the injection of a liquid into a plasma jet. This paper reviews the treatment of non-equilibrium phenomena in thermal plasma flows, in particular the methods of calculation of the composition and transport coefficients of non-equilibrium plasmas, which are required for modelling the above processes. The focus is on two-temperature plasmas, in which electrons and heavy species are at different temperatures. Methods of calculation of the composition of plasmas both in local chemical equilibrium (LCE) and out of LCE are presented. A comparison of the different methods shows large discrepancies, even assuming LCE. Two-temperature transport coefficients obtained from simplified expressions, from the modified Chapman–Enskog method and from the Stefan–Maxwell relations are presented, as well as examples focusing on the influence of plasma composition. Different methods of calculation of the collision integrals required in determining the transport coefficients are also reviewed. Particular attention is paid to diffusion, in particular to the combined diffusion coefficient method, which simplifies treatment of plasmas in LCE. The method of calculation of the reactive thermal conductivity and the influence of excited states on transport coefficients are also addressed in some detail.

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Section: Non-lte and Chemical Equilibriummentioning

confidence: 99%

Treatment of non-equilibrium phenomena in thermal plasma flows

Rat¹,

Murphy²,

Aubreton³

et al. 2008

J. Phys. D: Appl. Phys.

131

View full text Add to dashboard Cite

show abstract

“…This Re result suggests that the flow is in transition state with both turbulent and laminar transports [22]. On the other hand, Morsli [23] reported that the turbulence is present in the cooler regions (below 5000 K) of ICP torch jets. Also it is detailed that the laminar flow is promoted due to the lower densities and higher viscosities at the centre of the plasma stream (above 5000 K).…”

Section: Turbulence Characteristicsmentioning

confidence: 90%

Analysis of De-Laval nozzle designs employed for plasma figuring of surfaces

Jourdain

Gourma

et al. 2016

Int J Adv Manuf Technol

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Plasma figuring is a dwell time fabrication process that uses a locally delivered chemical reaction through means of an inductively coupled plasma (ICP) torch to correct surface figure errors. This paper presents two investigations for a high temperature jet (5000 K) that is used in the context of the plasma figuring process. Firstly, an investigation focuses on the aerodynamic properties of this jet that streamed through the plasma torch De-Laval nozzle and impinged optical surfaces. Secondly, the work highlights quantitatively the effects of changing the distance between the processed surface and nozzle outlet. In both investigations, results of numerical models and experiments were correlated. The authors' modelling approach is based on computational fluid dynamics (CFD). The model is specifically created for this harsh environment. Designated areas of interests in the model domain are the nozzle convergent-divergent and the impinged substrate regions. Strong correlations are highlighted between the gas flow velocity near the surface and material removal footprint profiles. In conclusion, the CFD model supports the optimization of an ICP torch design to fulfil the demand for the correction of ultra-precision surfaces.

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“…To study theoretically this kind of discharge, taking into account the possible occurrence of departures from thermal equilibrium, it is necessary to develop multi temperature MHD models. There are more and more publications in the literature dealing with multi-T fluid models such as the works of Mostaghimi et al [2], El Morsli and Proulx [3], Tanaka [4], Ye et al [5] and Al-Mamun et al [6] concerning respectively argon, air, Ar-N 2 , Ar-H 2 and Ar-CO 2 -H 2 radio-frequency inductively coupled plasma (ICP) torches, Ghorui et al [7] for the study of the oxygen flow inside the nozzle of a metal cutting device, Boselli et al [8] concerning a direct current (DC) welding arc in argon, Trelles et al [9], Bartosiewicz at al. [10] and Kaminska et al [11] for the study of a DC plasma torch in argon, Baeva and Uhrlandt [12] and Freton et al [13] concerning free-burning arcs in argon, Colombo et al [14] for a 3D transient model of a twin torch system, Park et al [15] for a DC transferred arc in argon and Benilov and Naidis [16] for the study of a wall-stabilized DC arc discharge.…”

Section: Introductionmentioning

confidence: 99%

Non-uniqueness of the multi-temperature law of mass action. Application to 2T plasma composition calculation by means of a collisional-radiative model

et al. 2017

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This work is devoted to the calculation of the composition for a monoatomic plasma (argon in the case presented) for which the assumption of thermal equilibrium is not realized. The plasma composition is obtained from a CR model, taking into account free electrons and a great number of electronic levels of Ar atoms and Ar + ions. This model is based on a large set of transition probabilities and reaction rate coefficients for radiative processes (spontaneous emission and radiative recombination) and on an extended database of direct and reverse reaction rate coefficients for collisional processes (excitation/de-excitation and ionization/recombination mechanisms). Assuming Maxwellian energy distribution functions for electrons and heavy chemical species, detailed balance equations are determined for all kind of reactions in the frame of the micro reversibility principle. From these balance equations, reverse rate coefficients are calculated as a function of direct reaction rates and of electrons and heavy particles translation temperatures (Te and T h respectively). Particular attention is paid to problematic chemical reactions with electrons involved on one side and only heavy species on the other side such as: Ar + Ar → Ar + Ar + + e. The detailed balance relations obtained for ionization/recombination processes demonstrate the non-uniqueness of the multi-temperature Saha-Eggert law (i.e. non-uniqueness of the multi-temperature law of mass action). Multi-temperature argon plasma compositions obtained in the present work exhibit abrupt density variations. These sharp variations are characteristic of the transition between the domination of heavy particle reactions (at low temperature) and the predominance of electron collisions (at high temperature).

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Two-temperature chemically non-equilibrium modelling of anairsupersonic ICP

Cited by 24 publications

References 63 publications

Treatment of non-equilibrium phenomena in thermal plasma flows

Treatment of non-equilibrium phenomena in thermal plasma flows

Analysis of De-Laval nozzle designs employed for plasma figuring of surfaces

Non-uniqueness of the multi-temperature law of mass action. Application to 2T plasma composition calculation by means of a collisional-radiative model

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