Numerical simulation on the motion of cathode spots in high-current vacuum arc

In this paper, the motion of high-current vacuum arc cathode spots is simulated numerically. The transverse magnetic field is computed by commercial software ANSYS with the current distribution in contact plate taken into account. The initial expansion process of cathode spots in triggered vacuum arc under self-generated azimuthal magnetic field without external AMF is simulated at first as a reference. Then three kinds of external AMF distributions are applied, i.e. uniform AMF, bell-shaped AMF and saddle-shaped AMF distribution. Simulation results show that cathode spots expand faster without external applied AMF than that under AMF. Further more, the distribution of AMF has significant influence on the motion pattern and the distribution of cathode spots on cathode surface, e.g., the concentration of cathode spots in the centre region under bell-shaped AMF is more serious than that under saddle-shaped AMF. The results also show that a ring-shaped distribution of cathode spots is not a stable configuration.