An FEM-BEM method for halo current problem and its application to HL-2M Tokamak

Halo current in Tokamak device during plasma vertical displacement events (VDEs) may damage the in-vessel components due to huge electromagnetic (EM) force. It is important to simulate the distribution of halo current in order to evaluate the EM force and the corresponding structural dynamic response. In this paper, an FEM-BEM method was proposed at first to simulate the current distribution in conductors excited by a sinusoidal conducting current injection. The response under a transient excitation was then realized by using the strategy of the frequency domain summation (FDS). A numerical simulation code was developed based on the proposed numerical scheme. The validity of the numerical method and corresponding code were proved by comparing numerical results of the developed code with those of the ANSYS software using step by step time domain integration. Finally, the proposed method was applied to the simulation of the halo current in a simplified vacuum vessel model of the HL-2M Tokamak. The simulation results provide good reference for the subsequent analysis of mechanical behaviors of in-vessel structures.