A model of the cathode region of atmospheric pressure arcs

Benilov, M. S.; Marotta, A.

doi:10.1088/0022-3727/28/9/015

Cited by 240 publications

(381 citation statements)

References 28 publications

(20 reference statements)

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“…The total electric current density is expressed as the sum of the densities of the emission current, the ion current corresponding to the Bohm flux, and the electron back flux dependent on the electron density at the sheath edge and the voltage drop over the space-charge sheath. The latter is calculated from the balance of energy fluxes at the sheath edge, i. e. between the arc plasma (the non-equilibrium pre-sheath) and the space-charge sheath according to [13]. Then, the net heat flux density onto the cathode surface is calculated from the balance of all contributions from particle fluxes and the radiation of the cathode surface.…”

Section: Non-equilibrium Modelmentioning

confidence: 99%

Cathode fall voltage of TIG arcs from a non-equilibrium arc model

et al. 2014

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This work presents modelling results concerning a tungsten inert gas (TIG) welding arc. The model provides a consistent description of the free burning arc, the arc attachment and the electrodes. Thermal and chemical nonequilibrium is considered in the whole arc area, and a detailed model of the cathode space-charge sheath is included. The mechanisms in the cathode pre-sheath are treated in the framework of a non-equilibrium approach which is based on a twofluid description of electrons and heavy particles and a simplified plasma chemistry of argon. A consistent determination of the electrode fall voltages and temperature distributions is achieved. The model is applied to arcs in pure argon at currents up to 250 A, whereby welding of a workpiece made of mild steel with a fixed burner is considered. Arc voltages in the range from 12 to 17 V are obtained at 50 at 250 A, respectively. The space-charge sheath voltage is found to be about 7 V and almost independent of the current. The corresponding temperatures of the cathode tip are in the range from 3,000 K to about 3,800 K. The results obtained are in a good agreement with measurements.

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Section: Non-equilibrium Modelmentioning

confidence: 99%

Cathode fall voltage of TIG arcs from a non-equilibrium arc model

et al. 2014

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“…with noble gases or mercury. It is on one hand an outcome of intense theoretical studies and on the other hand of experimental investigations, mainly at a model lamp, within the last years [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]. The description of the dc operation of anodes in HID lamps is less advanced, but at least a qualitative understanding has been achieved for cold and to some extent also for hot HID anodes [16,17,18,19].…”

Section: Introductionmentioning

confidence: 99%

Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

Reinelt¹,

Westermeier²,

Ruhrmann³

et al. 2011

J. Phys. D: Appl. Phys.

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Abstract. Phase resolved temperature distributions are determined along a rod shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amps and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase resolved values of the electrode tip temperature T tip and of the power input P in are determined comparing the measured temperature distributions with the integral of the one dimensional heat balance with these parameters as integration constants. They are supplemented by phase resolved measurements of the sum of cathode and anode fall called electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. T tip and P in start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation but the same tendencies are observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.

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“…These authors consider a two temperature plasma [19,20], and introduce the metal vapor in the sheath model [20]. Their model is intended to address a broader range of applications than GTA, like the model by Benilov [21,22]. The approach of Benilov is based on the two-scale description of the cathode layer analyzed by Riemann [23] doing a rigorous kinetic theory of the plasma-sheath transition.…”

mentioning

confidence: 99%

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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A model of the cathode region of atmospheric pressure arcs

Cited by 240 publications

References 28 publications

Cathode fall voltage of TIG arcs from a non-equilibrium arc model

Cathode fall voltage of TIG arcs from a non-equilibrium arc model

Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

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

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