Modeling and simulation of high-current vacuum arc subjected to transverse magnetic field

Abstract

Vacuum arc is usually driven to rotate and deflect by transverse magnetic field (TMF). This paper presents the 2D simulation results of vacuum arc controlled by external transverse magnetic field based on the magneto-hydro-dynamic (MHD) model. It is assumed that anode and cathode spots only occupy a small part of contact area for arc maintains a constricted status under TMF. In the simulation, external TMF is set as 0.5T, 0.7T and 1.0T. According to the simulation results, when uniform TMF is added, arc deflects under Ampere force. As a result, ion and electron temperature also deflects with arc deflection. Current density also deflects and current density contracts itself near anode and cathode. When TMF increases, arc deflects more significantly with other parameters. More ions move to the deflection direction under stronger external TMF. The increase of the velocity component of the right direction determines arc deflection. Thus, ion velocity becomes larger from arc center to left and right edge of electrodes under the gradient of plasma pressure in case of weak TMF. Under strong TMF, ions reach highest velocity when ions from cathode and anode meet each other. Most of them move to the deflection direction and form a zone with highest plasma pressure. It is concluded that arc parameters deflect to the same direction as with Ampere force direction under TMF.