Structural Analysis of ITER Toroidal Field Coil In-Cryostat Feeders

The ITER superconducting magnet system consists of 18 toroidal field (TF) coils, 6 poloidal field coils, 6 central solenoid modules, and 18 correction coils. Each coil is connected with a magnet feeder to support and control the high-current operation at cryogenic temperature. This paper presents the structural designs and finite-element (FE) analyses of the special construction of the TF in-cryostat feeders (ICFs). A global finite element model (FEM) was built to assess the distribution of the mechanical loads affected by gravitational, thermomechanical, and electromagnetic forces, as well as the displacement by the coils. Design challenges have been taken into account, and critical issues have been identified by global analysis. Valuable changes have been made based on global analysis results to solve the issues. Displacements obtained from global analysis were applied to local models as boundary conditions. Detailed FE analyses were performed to identify the local stress level in welded connections and the interaction between insulated bus bars and their clamps. The results of global and local analyses verify that the ICF ring box and bus bar jacket of the improved TF ICF design can withstand the operational loads with sufficient safety margin.