Distribution of peak temperature and energy flux on the surface of the anode in a multi-cathode spot pulsed vacuum arc

S. Goldsmith, R. L. Boxman, E. Sapir, Y. Cohen, H. Yaloz, N. Brosh

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The distribution of the peak temperature and energy flux on the surface of a steel anode in a pulsed high-current vacuum arc was determined by studying the spatial location of the borderline separating the region of hardened steel, produced by the pulse of energy flux to the anode, and the region of the anode which did not undergo a phase transition. The arc was run between a 14-mm-diameter stainless steel cathode and a 25-mm 4340 steel anode, separated by a 4-mm gap, with peak currents up to 1000 A and 71 ms full-width half-amplitude (FWHA) duration. The phase transition of the steel occurs at 727 °C and the above-mentioned borderline is thus the geometrical location of all points which reached a peak temperature of 727°C. The peak anode surface temperature was calculated from the borderline position by approximate solution of the three-dimensional heat conduction equation. The effect of an axial magnetic field on the anode surface temperature and energy flux distribution was also studied showing that with no magnetic field the distribution had a pronounced maximum on the axis of the arc, while with the presence of a magnetic field the distribution became annular with a maximum at about mid-radius. In comparison, the shape of the distribution of the cathode mass deposited by the arc on the anode was uniform without a magnetic field. The peak of the anode temperature and the energy flux amplitude also depended on the magnetic field, first decreasing and then increasing almost linearly with it. The peak energy flux into the anode as calculated from the temperature distribution is found to compare reasonably well with the estimated energy flux calculated by using the anode region model of Boxman and Goldsmith, and is in the range of 70-80 MW/m2. The corresponding maximum surface temperature is about 980°C.

Original languageEnglish
Pages (from-to)510-514
Number of pages5
JournalIEEE Transactions on Plasma Science
Issue number5
StatePublished - Oct 1987


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