Joule heat generation in thermionic cathodes of high-pressure arc discharges

Benilov, M. S.; Cunha, M D

doi:10.1063/1.4790709

Cited by 12 publications

(22 citation statements)

References 30 publications

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“…Distributions of the energy ‡ux to the cathode surface (…gure 8(b)) are in a good agreement for I = 60 A, but deviate for 100 A and especially for 200 A. Note that one could think that this deviation is a consequence of Joule e¤ect inside the cathode, which was taken into account in the NLTE-sheath approach but not in the realization of the model of nonlinear surface heating being employed, however this has been disproved by additional simulations performed by means of the model of nonlinear heating with account of the Joule e¤ect as in [46].…”

Section: Other Possible Approachesmentioning

confidence: 99%

Account of near-cathode sheath in numerical models of high-pressure arc discharges

Benilov¹,

Almeida²,

Baeva³

et al. 2016

J. Phys. D: Appl. Phys.

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Three approaches to description of separation of charges in near-cathode regions of high-pressure arc discharges are compared. The …rst approach employs a single set of equations, including the Poisson equation, in the whole interelectrode gap. The second approach employs a fully non-equilibrium description of the quasi-neutral bulk plasma, complemented with a newly developed description of the space-charge sheaths. The third, and the simplest, approach exploits the fact that a signi…cant power is deposited by the arc power supply into the near-cathode plasma layer, which allows one to simulate the plasma-cathode interaction in the …rst approximation independently of processes in the bulk plasma. It is found that results given by the di¤erent models are in a generally good agreement, and in some cases the agreement is even surprisingly good. It follows that the predicted integral characteristics of the plasma-cathode interaction are not strongly a¤ected by details of the model provided that the basic physics is right.

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Section: Other Possible Approachesmentioning

confidence: 99%

Account of near-cathode sheath in numerical models of high-pressure arc discharges

Benilov¹,

Almeida²,

Baeva³

et al. 2016

J. Phys. D: Appl. Phys.

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“…These authors modeled cylindrical tungsten cathodes in argon plasma for various configurations, and current ranging from 1 to 500 A. From their results, it can be seen that the current threshold I depends on several parameters such as the electrode radius R (varied from 0.3 to 1.0 mm in [32]) and the tip geometry (hemispherical, or flat in [32]). For the set of configurations studied in [32] the current threshold I was observed to vary from 26 A (when R = 0.3 mm) to 274 A (when R = 1.0 mm).…”

Section: Cathode-modelling Assumptionsmentioning

confidence: 99%

“…From their results, it can be seen that the current threshold I depends on several parameters such as the electrode radius R (varied from 0.3 to 1.0 mm in [32]) and the tip geometry (hemispherical, or flat in [32]). For the set of configurations studied in [32] the current threshold I was observed to vary from 26 A (when R = 0.3 mm) to 274 A (when R = 1.0 mm). It should be noticed that parameters other than R (such as the argon pressure and the inter-electrode distance) were simultaneously varied in [32], and to our knowledge the exact dependence of I is not established yet.…”

Section: Cathode-modelling Assumptionsmentioning

confidence: 99%

“…For the set of configurations studied in [32] the current threshold I was observed to vary from 26 A (when R = 0.3 mm) to 274 A (when R = 1.0 mm). It should be noticed that parameters other than R (such as the argon pressure and the inter-electrode distance) were simultaneously varied in [32], and to our knowledge the exact dependence of I is not established yet. Thus, apart from few specific configurations and process parameters, the value of I is generally not know.…”

Section: Cathode-modelling Assumptionsmentioning

confidence: 99%

“…Above some current threshold I this heat source term is important to model since it has an effect on e.g. the cathode surface temperature, as shown by Benilov and Cunha [32]. These authors modeled cylindrical tungsten cathodes in argon plasma for various configurations, and current ranging from 1 to 500 A.…”

Section: Cathode-modelling Assumptionsmentioning

confidence: 99%

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Gas tungsten arc models including the physics of the cathode layer: remaining issues

Choquet

2017

Weld World

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A recent review pointed out that the existing models for gas tungsten arc coupling the electrode (a cathode) and the plasma are not yet complete enough. Their strength is to predict with good accuracy either the electric potential or the temperature field in the region delimited by the electrode and the workpiece. Their weakness is their poor ability to predict with good accuracy these two fields at once. However, both of these fields are important since they govern the heat flux to the workpiece through current density and temperature gradient. New developments have been made since then. They mainly concern the approaches addressing the electrode sheath (or space charge layer) that suffered from an underestimation of the arc temperature. These new developments are summarized and discussed, the modelling assumptions are examined, and important modelling issues that remain unexplored are underlined.

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Numerical analysis of the heat-pressure characteristics in ultrasonic vibration assisted plasma arc

Chen

2020

Journal of Applied Physics

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The ultrasonic vibration assisted plasma arc welding process was developed to enhance the welding efficiency while the underlying mechanism of ultrasonic interaction with plasma arc is not yet elucidated. In this study, a numerical model of ultrasonic vibration assisted plasma arc is proposed, which takes into account the influence of plasma flow velocity on the ultrasonic propagation as well as the macro- and micro-effects of ultrasound on the heat-pressure characteristics of the plasma arc. The calculation results show that the plasma flow velocity affects the ultrasonic field in the plasma arc, resulting in a significant increase in the sound pressure near the workpiece surface. Ultrasound can increase the thermal conductivity of plasma and reduce the electric conductivity of plasma. The acoustic radiation force is at the same order of electromagnetic force, while the acoustic energy is five orders of magnitude lower than Joule heat. Under the comprehensive action of ultrasonic vibration, the plasma arc pressure and current density on the anode surface are increased so that the keyholing/penetrating ability of the plasma arc is enhanced. The model is validated by comparison of predicted and measured arc pressure and current density on the anode surface.

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Joule heat generation in thermionic cathodes of high-pressure arc discharges

Cited by 12 publications

References 30 publications

Account of near-cathode sheath in numerical models of high-pressure arc discharges

Account of near-cathode sheath in numerical models of high-pressure arc discharges

Gas tungsten arc models including the physics of the cathode layer: remaining issues

Numerical analysis of the heat-pressure characteristics in ultrasonic vibration assisted plasma arc

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