Influence of Oscillating Frequency of External Transverse Magnetic Field on DC Vacuum Arc Evolution

The objective of this paper is to experimentally determinate the influence of the oscillating frequency of transverse magnetic field (TMF) on DC vacuum arc evolution. In this paper, the experimental DC voltage was about 340 V, with the DC current of 340 A. The frequency of oscillating TMF was set as 70 Hz, 230 Hz, 430 Hz and 720 Hz, respectively. A high-speed charge-coupled device (CCD) video camera was selected to record the vacuum arc evolution, with the recording speed of 180,000 frames/s. The experimental results showed that, the duration of total interrupting process decreased with the increasing of the frequency of oscillating TMF. When the oscillating frequency increased from 70 Hz to 230 Hz and 430 Hz, the duration of total interrupting process decreased from 1.60 ms to 1.00 ms and 0.60 ms, respectively. As the frequency of oscillating TMF increased, the velocity of cathode spots increased. When the oscillating frequency increased from 70 Hz to 230 Hz, 430 Hz and 720 Hz, the average velocity of cathode spots increased from 5.25 m/s to 7.30 m/s, 8.47 m/s and 16.71 m/s, respectively. Moreover, when the oscillating frequency was too high, cathode spots would reciprocate on the surface of contacts, resulting in the failure of interruption. This research can provide a novel method for the low-voltage DC breaking technology in vacuum.