Prediction of arc distribution during transition and diffuse column modes of the vacuum arc

In this paper, arc distributions during the high-current diffuse column mode and transition mode are simulated based on recently developed generalized condition for cathode jet existence in the diffuse column arc mode. The following effects are considered by the model. The arc voltage imposed by the main column alters the plasma expansion and current flow in the single jet. Increasing the current in the main column causes the arc voltage and self-magnetic field to increase, in turn affecting the displaced single jet. Stable existence of the displaced single jet drives the transition into the high-current diffuse mode. The displaced single jets are confined along the magnetic field, which is combination of a self-magnetic field and an axial magnetic field. In this paper an additional effect is considered such as a possibility of the positive sheath near the anode. A model of the positive anode sheath is developed. It is shown that formation of a positive anode sheath strongly affects single cathodic jets and arc distribution during the transition mode.