Full-scale simulation of high-current vacuum arc in vacuum interrupter under axial magnetic field

Most existing studies on vacuum arcs confine the arc to the space directly between the electrodes. Contacts are often slotted to facilitate magnetic field control of the arc, thereby artificially restricting the arc-burning zone and overlooking the influence of electrode slotting on vacuum arc behavior. During practical short-circuit current interruption within vacuum circuit breakers, arc plasma is emitted from cathode spots into the inter-electrode gap; however, a portion of it still propagates beyond this region. To address the limitations of current models in elucidating the complex arc-burning mechanisms in interrupter chambers, this study develops a three-dimensional magnetohydrodynamic model of vacuum arcs. The model accounts for both inter-electrode arc diffusion and the influence of realistic contact geometries on plasma transport. Using this model, the transport characteristics of arc plasma in full-scale vacuum interrupters under axial magnetic fields (AMFs) are simulated, and the effect of AMFs on these characteristics is examined. Simulation results reveal that a high-pressure, high-density zone forms at the inter-electrode center due to electromagnetic pinch effects, which constrain ion diffusion. Cathode slots exhibit marked ion density enhancement, whereas anode slots exhibit low-velocity ion accumulation. Localized ion temperature elevation on the anode side is attributed to kinetic energy conversion. The axial current density demonstrates a contraction trend toward the anode center, with contact slotting exerting a limited impact on overall transport properties. Moreover, a reduction in AMF intensity leads to increased outward ion diffusion and stronger arc constriction, accompanied by elevated electron temperature and energy flux density at the anode center.