Tools Used at CEA for Designing the DEMO Toroidal Field Coils Winding Pack

While the ITER machine is still under construction, design and R&D activities regarding the next-step experimental reactor DEMO are underway in Europe. Although general design tools already exist for dimensioning superconducting magnets in integrated tokamak system codes, there is a need to develop more refined models and codes for magnets owing to the high operating constraints encountered in these huge magnetic systems, particularly the toroidal field (TF) one. This paper focuses on two key issues related to this dimensioning: first, the capability to build, using realistic high-current (~100 kA) conductors and insulation, the winding pack in the TF steel casing (elsewhere dimensioned); and, second, the accurate computation of the magnetic field on the superconductor, which determines its transport current capability. The exercise was carried out within the CEA studies for the Eurofusion DEMO project in its 2014 and 2015 versions. The design of the superconducting cable is based on ITER-like conductors to take advantage of the already existing experience gained on this type of conductors through the ITER R&D and qualification programs, whereas the design criteria that are recalled have been agreed within the European fusion community. This paper depicts the method and the results of the dimensioning of a proposal TF winding pack.