Modeling of a high current vacuum arc in a transverse magnetic field and influence of the electrode gap on the arc motion

The present modeling deals with the physical description of the high-current (>15 kA) constricted vacuum arc, driven by a transverse magnetic field (TMF), as found in vacuum circuit breakers applying TMF arc control. The MHD approach together with detailed heat transfer and evaporation equations for the electrodes are used to describe the arc behavior self-consistently, restricting to two dimensions (2D). This newly model leads to the characterization of the physical quantities of the arc plasma and describes the arc motion as step-wise due to the different velocities of the current attachment areas of cathode and anode. The model is applied to simulate the influence of the electrode gap distance on the arc motion: it is found that faster arc velocity can be achieved at larger gap.