Influence of axial magnetic field on cathode plasma jets in high-current vacuum arc

In this paper, the experiments of cup-shaped axial magnetic field (AMF) contacts were conducted in which a Helmholtz coil was introduced to generate different external imposed AMF. It was found that the appearance of arc plasma was changed by variation of the external imposed AMF. If the composite AMF in arc column increased gradually, the obvious individual cathode plasma jets were detected, the arc constriction decreased and the arc stability increased. Meanwhile, the inclination of cathode jets was observed and the inclination direction of cathode plasma jets changed by variation of the external imposed AMF and its direction. It was also found that, if the composite AMF in interelectrode gap points to different directions at a certain moment, it may lead to the transfer of arc column from the center to edge of interelectrode region and the arc instability until when the composite AMF in interelectrode gap points to the same direction. It can be concluded that the appearance of individual cathode plasma jets can be manipulated by the variation of AMF, which is helpful to study the interaction between arc plasma and electrodes, especially the anode, and improve the interruption performance at higher current.