The effect of arc velocity on cold electrode erosion

Essiptchouk, A. M.; Marotta, A.; Sharakhovsky, L. I.

doi:10.1063/1.1647562

Cited by 17 publications

(11 citation statements)

References 11 publications

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“…For tubular plasma torches, the electrode lifetime spans from a few hundreds to a few thousands hours. Two common ways to reduce the erosion of electrodes are discussed in [1]: the introduction of vortex flow to enhance the heat convection near the electrodes and the application of an axial magnetic field B to rapidly displace the arc spot on the electrode surface, where the significant heat conduction to the electrodes can be decreased. Both approaches are employed in this paper to diminish the electrode erosion of a well-type plasma torch, where a circular swirler is installed to introduce the vortex flow and a solenoid is equipped to provide an axial magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

Chau

Hsu

Lin

et al. 2007

J. Phys. D: Appl. Phys.

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The cathode erosion rate, arc root velocity and output power of a well-type cathode (WTC), non-transferred plasma torch operating in air are studied experimentally in this paper. An external solenoid to generate a magnetically driven arc and a circular swirler to produce a vortex flow structure are equipped in the studied torch system, which is designed to reduce the erosion rate at the cathode. A least square technique is applied to correlate the system parameters, i.e. current, axial magnetic field and mass flow rate, with the cathode erosion rate, arc root velocity and system power output. In the studied WTC torch system, the cathode erosion has a major thermal erosion component and a minor component due to the ion-bombardment effect. The cathode erosion increases with the increase of current due to the enhancement in both Joule heating and ion bombardment. The axial magnetic field can significantly reduce the cathode erosion by reducing the thermal loading of cathode materials at the arc root and improving the heat transfer to gas near the cathode. But, the rise in the mass flow rate leads to the deterioration of erosion, since the ion-bombardment effect prevails over the convective cooling at the cathode. The most dominant system parameter to influence the arc root velocity is the axial magnetic field, which is mainly contributed to the magnetic force driving the arc. The growth in current has a negative impact on increasing the arc root velocity, because the friction force acting at the spot due to a severe molten condition becomes the dominant component counteracting the magnetic force. The mass flow rate also suppresses the arc root velocity, as a result of which the arc root moves in the direction against that of the swirled working gas. All system parameters such as current, magnetic field and gas flow rate increase with the increase in the torch output power. The experimental evidences suggest that the axial magnetic field is the most important parameter to operate the straight-polarity WTC plasma torch at high output power with a limited cathode erosion rate. This emphasizes the importance of an external magnetic field on a WTC torch system for reducing the erosion at the cathode.

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Section: Introductionmentioning

confidence: 99%

Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

Chau

Hsu

Lin

et al. 2007

J. Phys. D: Appl. Phys.

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“…The velocity of arc rotation was obtained from Fast Fourier Transform of the signal from thermocouples, now also operating as magnetic probes. Each time the arc passes in the neighbourhoods of the thermocouple position (Figure 2), an alternating voltage is induced in the thermocouple loop (for more details see [13]). By composition (averaging) and smoothing of two signals, obtained from two thermocouples installed on the opposite faces of the electrode, it was possible to obtain the mean electrode temperature T 0 (see Figure 3).…”

Section: Methodsmentioning

confidence: 99%

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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“…Essiptchouk et al made a magnetic probe consisting of single-loop chromel-alumel thermocouple wires which were placed side-on in the electrode to measure the arc velocity and the electrode temperature in an electric arc heater. The copper cathode erosion in a magnetically driven arc versus arc rotation velocity has been investigated [12]. B-dot probe has the advantages such as the following: It is easily made; the measurement accuracy is not influenced by the frequency of the target signal; and the probe signal can be directly sent to an oscilloscope without any transformation.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Arc Velocity in a Rotating-Arc Pulsed-Power Switch Based on B-Dot Probes

Guo

2010

IEEE Trans. Plasma Sci.

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A rotating-arc pulsed-power switch is designed in this paper. In order to realize the arc rotating characteristics, B-dot probes are installed in the switch to measure the arc velocity. Six B-dot probes are installed symmetrically in a circle under the gap to obtain the arc velocity variation with the current. The probe signal is calculated in a simplified model, and the method of velocity calculation is discussed. The theoretical errors of velocity calculation caused by the variation of arc direction are analyzed. The arc velocity is obtained from the experimental probe voltage signals using the probes in different distances, and then, the results are discussed. From the measurements, the arc rotates about 550 m/s at a current of 20 kA.Index Terms-Arc velocity, axial magnetic field, B-dot probe, rotating-arc switch.

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The effect of arc velocity on cold electrode erosion

Cited by 17 publications

References 11 publications

Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

Experimental study on copper cathode erosion rate and rotational velocity of magnetically driven arcs in a well-type cathode non-transferred plasma torch operating in air

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

Measurement of Arc Velocity in a Rotating-Arc Pulsed-Power Switch Based on B-Dot Probes

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