3-D Hybrid Simulation of Low-current Vacuum Plasma Jets under Axial Magnetic Fields

The basic behaviors of vacuum arcs are directly affected by the plasma jets ejected from cathode spots. It is of great interest to investigate the features of the plasma jets, especially under magnetic fields. However, for a single jet, the traditional methods, magnetohydrodynamics (MHD) or Particle-in-Cell (PIC), are limited by either accuracy or efficiency. In this paper, we have developed a 3-D parallel hybrid plasma simulation code, which treats ions as particles and electrons as massless fluids, studying the movement of particles and propagation of electromagnetic fields in a self-consistent way. By this approach, the behaviors of a vacuum plasma jet from a single cathode spot under axial magnetic field (AMF) are simulated. It is shown that the spreading angle of the plasma jet decreases gradually when the strength of AMF becomes larger. Moreover, the ion density of the axis near the anode increases. The simulation results are in reasonable agreement with the experimental results.