Effect of Magnetic Field on the Behavior and Sustaining Characteristics of Low-Current DC Vacuum Arc

摘要

Effects of magnetic field on duration and dynamics of low-current DC vacuum arcs, less than 20 A, were examined. Without a magnetic field, the cathode spot moves at random on the cathode surface and the arc voltage is constant for increasing gap length up to 30 mm. In the axial magnetic field, the arc plasma was constricted and the arc voltage rose with increasing gap length. When a magnet was arranged behind the cathode, the cathode spot rotated in the opposite direction of the Lorentz force (j × B) on the edge of the cathode. On the other hand, when a magnet was arranged behind the anode, the arc column was constricted on the electrode axis and the lifetime of the arcs was extremely extended.