Nonequilibrium Phenomena in (Quasi-)thermal Plasma Flows

Trelles, Juan Pablo

doi:10.1007/s11090-019-10046-1

Cited by 21 publications

(12 citation statements)

References 94 publications

(109 reference statements)

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“…Complex physical phenomena with multi-space-scale features, such as deviation from thermal and chemical equilibria [9][10][11][12][13] and broken quasi-neutrality condition [14][15][16][17], occur along the distance from the electrode surface to the plasma column. The first layer of adjacent electrodes is the space-charge sheath, which is on the order of the Debye length (∼10 −8 m) [2].…”

Section: Introductionmentioning

confidence: 99%

Non-equilibrium modeling on the plasma–electrode interaction in an argon DC plasma torch

Sun¹,

Sun²,

Niu³

et al. 2021

J. Phys. D: Appl. Phys.

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A 2D two-temperature chemical non-equilibrium model considering both cathode and anode space-charge sheath is applied to investigate the plasma-electrode interaction in a laminar argon DC plasma torch working at atmospheric pressure. In order to validate the model, the predicted arc voltage is compared with experimental values under different working conditions, and a reasonable agreement is obtained. The distributions of arc characteristics in the plasma column and electrode regions of a DC arc plasma torch are analyzed in detail. Moreover, the effects of thoriated tungsten, pure tungsten and non-uniform thoriated tungsten cathodes on the plasma characteristics inside the DC plasma torch are investigated. It is found that a constricted arc attachment with the highest current density is obtained at the non-uniform cathode, leading to the largest velocity and electric potential drop in the plasma column. The pure tungsten cathode produces the highest temperatures and heat flux along the cathode surface, which is caused by the largest arc voltage and intense space-charge sheath heating. The temperature and heat flux density on the thoriated tungsten cathode are the lowest, leading to a diffuse distribution of current density. The results indicate that the different cathodes can exert an important influence upon the plasma behavior near the cathode. Furthermore, the torch exit parameters are also slightly different due to their different arc voltages and overall input power.

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Section: Introductionmentioning

confidence: 99%

Non-equilibrium modeling on the plasma–electrode interaction in an argon DC plasma torch

Sun¹,

Sun²,

Niu³

et al. 2021

J. Phys. D: Appl. Phys.

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“…Therefore, the simulation of the departure from LTE inside the torch is required to understand the processes inside the plasma torch. The detailed analysis of the nonequilibrium phenomena presented in Trelles (2020) suggests to refer to such plasma flows as a quasi-thermal plasma flow.…”

Section: Introductionmentioning

confidence: 99%

“…The present study is focused on implementing a 2T 3D time-dependent model combined with the solid electrodes; it also compares several thermal configurations of the model in the context of a DC plasma torch. Following the terminology proposed in Trelles (2020), the model is intended to cover the kinetic nonequilibrium caused by microscopic imbalance in thermal energy. Meanwhile, the dissipative nonequilibrium caused by macroscopic instabilities, e.g.…”

Section: Introductionmentioning

confidence: 99%

Model of a non-transferred arc cascaded-anode plasma torch: the two-temperature formulation

Zhukovskii

Chazelas

Rat

et al. 2021

J. Phys. D: Appl. Phys.

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This study presents an analysis of a three-dimensional unsteady two-temperature simulation of atmospheric pressure direct current electric arc inside a commercial cascaded-anode plasma spray torch; it coupled the arc model with the torch electrodes and used an open-source computational fluid dynamics software (code_saturne). The previously published models of plasma spray torch either deal with conventional plasma torches or assume local thermodynamic equilibrium in cascaded-anode plasma torches. The paper presents the computation of the two-temperature argon plasma properties, compares two enthalpy formulations that differ in association of the ionization part of enthalpy and finally demonstrates the influence of the radiation heat loss data by comparingthe results for two different literature sources. It is the first to compare different enthalpy formulations in the context of plasma torch and discuss the differences in terms of the enthalpy gains and losses. It also explains why an unphysical simulation artifact of electron temperature lower than the heavy species temperature can occur in simulated plasma flow. The solution, then, consists in associating the ionization part of enthalpy to electrons and selecting the appropriate source of the data of radiation heat loss. However, negligible thermal non-equilibrium persists even in the hot core of electric arc, which ensures that the heavy species are heated up by collisions with electrons. The flexibility of the open-source software allows all the necessary modifications and adjustments to achieve satisfactory simulation results. Thus, the paper could be considered as a manual for development of a plasma spray torch model.

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“…A LTE-diffusion method to near arc plasma was applied to predict characteristics of metal vapor flow [17]. Juan Pablo compared the kinetic nonequilibrium and dissipative nonequilibrium model for thermal plasma analysis in LTE [18]. In this study, LTE was assumed and an analysis was performed for ease of analysis.…”

Section: Introductionmentioning

confidence: 99%

Arc Plasma Flow Variation by Obstruction Structures between Anode and Cathode

Cho

Jeong

Kim

et al. 2021

Metals

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Arc plasma flow between electrodes has been investigated in several studies. However, in the industrial field, arc plasma flow between electrodes is hindered by interfering materials such as filler metal in arc welding, substrates in chemical vapor deposition, and powders in sintering. Therefore, in this study, high temperature arc plasma flow analysis via three obstruction structure shapes was performed to understand the inter-electrode interference phenomena. COMSOL Multiphysics was used for the analysis; COMSOL interface such as electric field, magnetic field, heat transfer, and fluid flow (laminar flow) was applied and Multiphysics such as plasma heat source and temperature coupling were considered. The temperature and velocity of the arc plasma were determined and the energy transfer between the electrodes was analyzed. We confirmed that the concave shape has a lower average heat flux than the other shapes, with the arc pressure evenly distributed in the anode. It is concluded that the concave shape can reduce the flow of the plasma from the anode and obtain even distribution of the arc plasma in the radial direction.

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Nonequilibrium Phenomena in (Quasi-)thermal Plasma Flows

Cited by 21 publications

References 94 publications

Non-equilibrium modeling on the plasma–electrode interaction in an argon DC plasma torch

Non-equilibrium modeling on the plasma–electrode interaction in an argon DC plasma torch

Model of a non-transferred arc cascaded-anode plasma torch: the two-temperature formulation

Arc Plasma Flow Variation by Obstruction Structures between Anode and Cathode

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