Approaches to analyze structural issues of the European DEMO Toroidal Field Coil System at an early design stage

Because of its ambitious goals, the DEMO project faces many technical challenges. The mechanical performance of the superconducting toroidal field coil (TFC) system is mostly determined by the high electromagnetic forces. A structural evaluation of the TFC of the EU DEMO 2014/2015 baseline configurations is presented. The emphasis is focused on the parametric study with the use of simplified numerical modeling. Physical interpretation of the numerical results makes the system mechanical behavior transparent and directly leads to the design recommendations. An express approach is proposed to reconstruct the detailed conductor stress state from the homogenized winding. This allows for sorting out the WP designs with respect to their robustness against acceptance criteria while giving a way for their improvement. An analysis workflow for the TFC system stress analysis is proposed. The main features of a semianalytical procedure allowing for the coil predimensioning prior to the 3-D numerical simulations are highlighted. It features the structural optimization of the layered winding, thus defining the minimum space required for the coil winding.