Electrode sheath voltages for helium arcs between non-thermionic electrodes of iron, copper and titanium

Yokomizu, Yasunobu; Matsumura, Toshiro; Sun, Wenbin; Lowke, J. J.

doi:10.1088/0022-3727/31/7/017

Cited by 20 publications

(17 citation statements)

References 10 publications

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“…Transfer of the arc current through the droplets after detachment from the wire requires emission of electrons from the droplet surface. As iron is a non-thermionic emitter, the emission of electrons from the droplet surface would require a sheath voltage of up to 15 V. 28 The natural minimum energy requirements would favor the conduction of the current through the plasma rather than through the detached welding droplets in the plasma. Following this argument, droplets in the plasma are heated only by conduction from neutral particles from the surrounding plasma.…”

Section: Discussionmentioning

confidence: 99%

An analysis of heat transfer and fume production in gas metal arc welding. III

Haidar

1999

Journal of Applied Physics

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Articles you may be interested inHeat and fluid flow in complex joints during gas metal arc welding-Part II: Application to fillet welding of mild steel J. Appl. Phys. 95, 5220 (2004); 10.1063/1.1699486 Heat and fluid flow in complex joints during gas metal arc welding-Part I: Numerical model of fillet welding J. Appl. Phys. 95, 5210 (2004); 10.1063/1.1699485 Modeling of temperature field and solidified surface profile during gas-metal arc fillet welding J. Appl. Phys. 94, 2667 (2003); 10.1063/1.1592012Modeling of heat transfer and fluid flow during gas tungsten arc spot welding of low carbon steel A theoretical model for gas metal arc welding and gas tungsten arc welding. I.A two-dimensional dynamic theory for predictions of arc and electrode properties in arc welding has been used to investigate heat transfer phenomena in the welding wire in gas metal arc welding ͑GMAW͒. The theory is a unified treatment of the welding wire, the plasma and the workpiece and includes a free surface treatment for the welding drops, accounting for the effects of inertia, gravity, surface tension, arc pressure, magnetic forces, and viscous drag by the gas flow around the drop. Also, the theory accounts for the variation of the surface tension coefficient with temperature and includes thermal and dynamic phenomena within the solid and liquid phases of the wire, together with a detailed treatment for the electrode sheath regions. Calculations are made for arcs in argon with wires of mild steel at currents between 150 and 325 A. Results of calculations for heat fluxes within the wire suggest that evaporation from the surface of the droplet during droplet growth has an important influence on the heat balance of the wire. The calculated evaporation rates from the droplet surface during droplet growth at the tip of the wire are found to be much higher than measured rates of fume formation in GMAW, suggesting an important recondensation process at the surface of the workpiece.

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Section: Discussionmentioning

confidence: 99%

An analysis of heat transfer and fume production in gas metal arc welding. III

Haidar

1999

Journal of Applied Physics

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“…In addition, averaging (at a width of 5 ms) was applied to the voltage waveforms in order to remove pulsations. The electrode voltage drop, estimated to be several volts [17,18], is ignored here because it is very small compared to the arc voltage (over 1000 V).…”

Section: Methodsmentioning

confidence: 99%

Internal voltage gradient and behavior of column on long‐gap DC free arc

Tanaka

Sunabe

Goda

2003

Electrical Engineering Japan

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SUMMARYThe internal voltage gradient and behavior of column on long-gap DC free arcs were analyzed quantitatively. In the analysis, an image processing technique developed by us was applied to the images shot from two orthogonal views by two high-speed video cameras to estimate the three-dimensional arc column paths. Objective free arcs were ignited between the rod electrodes with the current in the range of 100 to 2000A and the gap in the range of 1.6 to 3.2 m. In addition, some of the objective free arcs were placed in the external magnetic field brought about by a large coil. As a result, macroscopic changes with time in terms of the arc voltage gradient along the column path, the ratio of the arc column length to the gap length, and the distance from the center axis between the electrodes to the farthest point were derived. All average characteristics were shown as the experimental equations. In addition, the effect of the external magnetic field on the macroscopic velocity of the expansion was studied.

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“…On the other hand, a presence of a fine oxide layer, on the cathode surface, results in a considerable decrease of ∆U c , as it was reported in [7]. Furthermore, using different gases and electrode materials, it was shown experimentally that U fall is more related to the ionization potential of the filling gas, U i , than to the normal work function ϕ 0 of the electrode material [8]. Recently, some theoretical justification of these results has been presented [9,10].…”

Section: Introductionmentioning

confidence: 64%

Magnetic Field Effect on the Volt‐Equivalent of Arc Spot Heat Flux

Essiptchouk¹,

Marotta

Sharakhovsky

2005

Contrib. Plasma Phys.

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The results of an experimental study of the arc spot heat flux on the copper cathode of a coaxial Electric Arc Heaters (EAH), with magnetically driven arc, in air are presented. The three rings method was used for indirect separation of arc spot heat flux from total heat entering the electrode. As a result of joint generalizing new and previously published data, the linear dependence of the volt equivalent of arc spot heat flux on magnetic field was obtained for the range B = 0.01 − 1 Tesla and atmospheric pressure. A method, which allows to improve the measurement of the volt equivalent in highly unsteady arc spots, is proposed.

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Electrode sheath voltages for helium arcs between non-thermionic electrodes of iron, copper and titanium

Cited by 20 publications

References 10 publications

An analysis of heat transfer and fume production in gas metal arc welding. III

An analysis of heat transfer and fume production in gas metal arc welding. III

Internal voltage gradient and behavior of column on long‐gap DC free arc

Magnetic Field Effect on the Volt‐Equivalent of Arc Spot Heat Flux

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