Electrode erosion in high current, high energy transient arcs

Donaldson, A. L.; Kristiansen, M.; Watson, A.; Zinsmeyer, K.; Kristiansen, E.; Dethlefsen, R.

doi:10.1109/tmag.1986.1064638

Cited by 72 publications

(35 citation statements)

References 12 publications

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“…It is well documented in the literature on air-gap discharges (Ref 12,13) that greater erosion occurs in the cathodes under unipolar discharges while bipolar discharges lead to similar erosion losses in both electrodes. A detailed discussion of the effects of material removal from the anode during pulsed discharges in water can be found in Ref 17, and a number of factors may be at play.…”

Section: Electrode Materials Testsmentioning

confidence: 91%

Electrode Erosion Observed in Electrohydraulic Discharges Used in Pulsed Sheet Metal Forming

Bonnen

Golovashchenko

Dawson

et al. 2013

J. of Materi Eng and Perform

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In this paper, we present results of electrode durability testing and electrode design in a pulsed electrohydraulic discharge environment. Pulsed electrohydraulic forming (EHF) is an electrodynamic process based upon high-voltage discharge of capacitors between two electrodes positioned in a fluid-filled chamber. EHF enables a more uniform distribution of strains, widens the formability window, and reduces elastic springback in the final part when compared to traditional sheet metal stamping. This extended formability allows the fabrication of panels of alternative high strength alloys that are otherwise difficult to make conventionally. It was found that, of the materials tested, steel electrodes not only survived the stresses encountered in the EHF chamber but also had lower erosion rates compared to molybdenum. Erosion rates were found to be constant for low carbon steel at 3.7 mm 3 /discharge, and they were high enough that the initial tip geometry was rapidly worn away and a more geometrically and thus electrically stable tip geometry had to be selected. Entrained air in the system had little influence on erosion rates but numerical modeling suggests that the erosion process takes place during the very initial stages of the pulse. Lastly, it was determined that the electrodes discussed in this paper can survive 2000 pulses.

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Section: Electrode Materials Testsmentioning

confidence: 91%

Electrode Erosion Observed in Electrohydraulic Discharges Used in Pulsed Sheet Metal Forming

Bonnen

Golovashchenko

Dawson

et al. 2013

J. of Materi Eng and Perform

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“…Although the cathode surface was smooth, tiny graphite particles were attached on the periphery of the cathode surface. This phenomenon could be attributed to the graphite cannot melt but only be sublimated, during discharging in a gas switch, the graphite electrode surface was heated by the arc, the energy exchange on anode and cathode were different under high-current, high coulomb transfer operating conditions [14], and the energy input into the anode was larger than that into the cathode, leading to serious material removal on the anode and sputtering on the cathode during discharge. Although serious erosion was observed during discharge, stable self-breakdown voltage was obtained during the lifetime experiments, this indicated that the erosion was uniform and the tiny graphite particles had no effect on the performance of the gas switch.…”

Section: Erosion Characteristic Of the Graphite Electrodesmentioning

confidence: 99%

Design and Characteristics of a High Current Two-Electrode Graphite Gas Switch for the ICF Power System

et al. 2015

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In this paper, a two-electrode graphite gas switch was developed as the main discharge switch for the high-power laser system. A compact Marx generator designed to generate a 20 ns rise-time and -80 kV peak voltage to trigger the main discharge switch. A magnetic switch was designed to block the triggering pulse from the flashlamp load and permit the main discharge current to flow from the capacitor bank to the flashlamp load. The characteristics of the gas switch were measured under a 1.0-MJ capacitive pulsed power module for over 3300 discharge experiments with a total charge transfer 230 kC. The self-breakdown voltage and the surface characteristics of the electrodes indicated that the erosion of the gas switch was uniform. The lifetime was directly dependent on the electrode erosion rate. The gas switch can go on acting at a full current after the graphite electrodes were replaced.

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“…I n the intense arc mode, erosion of the cathode is quite high. This severe erosion has several causes: the increase in electrical power dissipated a t the cathode, the increased radiant energy from the anode, and the ablation of the cathode surface caused by the mechanical and thermal effects of an anode jet impinging upon the cathode [24]. I n the diffuse arc mode with no anode sputtering, erosion of the anode is zero.…”

Section: E L E C T R O D E E R O S I O Nmentioning

confidence: 99%

“…It is possible that the extra power compensates for increased losses by the arc column; or that, while the overall anode power density increases, the local peak power density decreases. However, recent work by DONALDSON et al [24] indicates that the most probable explanation is that the increased erosion a t the shorter gaps is not primarily an effect of direct electric power dissipation, but rather reflects the meclianical and thermal erosion produced by the impact of a powerful plnvnin jet (anode jet) on the surface of the electrode [25].…”

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confidence: 99%

A Review of Anode Phenomena in Vacuum Arcs

Miller

1989

Contrib. Plasma Phys.

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This paper discusses arc modes at the anode, experimental results pertinent t o anode phenomena, and theoretical explanations of anode phenomena.A vacuum arc can exhibit five anode discharge modes: (1) a low current mode in which the anode is basically passive, acting only as a collector of particles emitted from the cathode; (2) a second low current mode that can occur if the electrode material is readily sputtered (a flux of sputtered atoms will be emitted by the anode); (3) a footpoint mode, characterized by the appearance of one or more small luminous spota on the anode (footpoints are generally much cooler than the true anode spota present in the last two modes); (4) an anode spot mode in which one large or several small anode spots are present (such spots are very luminous, have a temperature near the atmospheric boiling point of the anode material, and are a copious source of vapor and ions); and ( 5 ) an intense arc mode where an anode spot is present, but accompanied by severe cathode erosion.The arc voltage is relatively low and quiet in the two low current. modes and the intense arc mode. It is usunlly high and noisy in the footpoint mode, and it can be either in the anode spot mode. Anode erosion is low, indeed negative, in the two low current modes, and it is low to moderate in thc footpoint mode. Severe anode erosion occurs in both the anode spot and intense arc modes.The dominant mechanism controlling the formation of an anode spot appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum i i rc being considered. I n specific experimental conditions, either magnetic constriction in the gap plasma, or gross anode melting, or local snode evaporation can trigger the transition. However, the most probable explanation of anode spot formation is a combination theory, which considers magnetic constriction in the plasma together with the fluxes of material from the anode and cathode as well as the thermal, electricnl, and geometric effects of the anode in analyzing the behavior of the anode and the nearby plasmn.

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Electrode erosion in high current, high energy transient arcs

Abstract: Introduction Experimental Setup Results Acknowledgements 05 References 06 D.

Cited by 72 publications

References 12 publications

Electrode Erosion Observed in Electrohydraulic Discharges Used in Pulsed Sheet Metal Forming

Electrode Erosion Observed in Electrohydraulic Discharges Used in Pulsed Sheet Metal Forming

Design and Characteristics of a High Current Two-Electrode Graphite Gas Switch for the ICF Power System

A Review of Anode Phenomena in Vacuum Arcs

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