Determination of Anode Surface Temperature of Horseshoe-Type AMF Electrode after Current Zero

Abstract

The objective of this paper is to determine anode surface temperature after current zero of a horseshoe-type axial magnetic field (AMF) electrode. Both alternating current (AC) with a peak value of 15 kA and rectangular waveform current (RWC) with the maximum value of 10 kA were applied in the draw arc experiment. Near infrared (NIR) spectrometer working at a wavelength from 880 to 1700 nm was used to measure thermal radiance from the anode. Temporal resolution of the NIR spectrometer was 1.46 ms. A 2-D temperature distribution on the anode surface was obtained by means of a high-speed video camera with a metal interference filter transmitting at 890 nm. Based on the measurement results, the anode temperature was calculated using Planck curve fitting procedure. The anode temperature near current zero with AC was 1130 K. The anode temperature at 0.4 ms before current zero and 1.1 ms after current zero with RWC were 1290 K and 920 K, respectively. The temperature exponential decreased to about 690 K in 6.9 ms after current zero with both AC and RWC cases. In addition, two hot regions on anode surface were observed near current zero. In the RWC case, the maximum values of temperature in these two hot regions were 1170 K and 1080 K, respectively.