Experiments and simulation research of vacuum arc with TMF-AMF contact

Abstract

A series of triggering experiments were carried out to investigate into the characteristics of vacuum arc controlled by TMF-AMF contacts. During the whole experiments, current ranged from 5kA to 20kA (rms) and both arc appearance and the behavior of cathode spots were captured by high-speed camera with corresponding arc current and arc voltage. A 3D steady MHD model was built to simulate and analyze the vacuum arc behavior under TMF-AMF contacts, and arc plasma parameters were calculated based on the above model. The experimental results showed that arc deflection was visible under both low and high current. Under high current, arc core formed, which meant arc contracted itself significantly. In addition, anode became much more active under high current. The behavior of cathode spots showed that they split themselves into other new cathode spots. Under high current, the bulk of spots rotated along clockwise direction on TMF plate, which arose much noise and oscillation in arc voltage. The simulation results show that ions are likely to gather on the branches of TMF plate on anode plane, as a result of the effects between electro-magnetic force and pressure gradient of arc plasma. Current contracts itself in the center of TMF plate on cathode due to the thin connecting rod there. The anode contraction of current is caused by the Hall Effect. Ions move along clockwise direction on TMF plate, which is driven by Ampere force. The current contraction resulted in significant melting in the center of cathode surface while other region is suffered from uniform melting. The anode contraction arises more severe melting than cathode.