Electromagnetic load evaluation of K-DEMO divertor for MD and VDE plasma disruption scenarios

Abstract

Electromagnetic (EM) force caused by the instability of plasma operation is one of the most significant external loads in the DEMO, as well as the extremely high heat flux (more than 10 MW/m2). Abrupt disruption of plasma current of several MA causes thermal quench and current quench sequentially. This paper presents the EM force on the divertor calculated by considering the Poloidal field variation (PFV), halo current (HC), and toroidal field variation (TFV) generated during the quenching process for the K-DEMO. The K-DEMO with the fusion power of 2,200 MW has a major radius of 6.8 m and a plasma current of 12 MA in steady-state operation. The K-DEMO divertor basically employs a water-cooled tungsten monoblock concept with a reduced activation ferritic martensitic RAFM steel heat sink. EM force was calculated using ANSYS Mechanical/Emag solver. For the convenience of calculation, the existing inconvenient GUI environment based on MAPDL was changed to ANSYS Workbench and improved. To evaluate the EM forces generated in the K-DEMO divertor when various disruption scenarios occur, three scenarios were selected for major disruption (MD) and vertical displacement event (VDE), respectively. The variation of PFV, HC, and TFV in the disruption are significant input data for EM analysis. The major disruption data were converted from ITER disruption scenarios by using the in-house code since the plasma data for the disruption scenarios has not been developed for the K-DEMO. This study presents the preliminary evaluation of EM force for the K-DEMO and improved calculation platform although the disruption data derived from ITER are used. The EM forces generated by the selected six scenarios were calculated and compared. In the MD_DW_slow_fast and VDE_DW_slow_fast scenarios, the maximum EM force was 4.8 MN on the K-DEMO divertor module along the vertical direction, and the HC influence was dominant.