Analysis method for magneto-mechanical coupled vibration of the in-vessel structures considering halo current effect and application to HL-2M tokamak

The tokamak in-vessel structures serve in strong magnetic fields. During plasma disruptions such as the vertical displacement events, the induced eddy current and the injected halo current in in-vessel structures cause the vibration of the plasma-facing components. The vibration is coupled to the magnetic field in the form of the motional eddy current. Such magneto-mechanical coupling effect may have a considerable influence on the dynamic mechanical behavior of the in-vessel structures. This paper presents a numerical approach to analyze this magneto-mechanical coupled problem based on the hybrid method of the finite element and boundary element formulation. The plasma current and the halo current are taken into account in a form of a series of movable current filaments and a pair of current source and sink. The proposed approach is applied to the numerical analysis of a simplified model of the vacuum vessel of HL-2 M tokamak under an L-mode plasma disruption. Simulation results show that the vibration is strongly damped and the maximum vertical displacement is reduced by around 30 % when considering the magneto-mechanical coupling.