Optimization design and mechanical analysis of the CFETR CS model coil

The Central Solenoid (CS) model coil of China Fusion Engineering Test Reactor (CFETR) consists of an inner Nb₃Sn module and an outer NbTi module. In this paper, a Fortran code is written to do the optimization design, which is performed with aim of reducing the Nb₃Sn CICC conductor required to produce a peak field of 12 T, besides the length of NbTi CICC conductor and the height difference among the constituent coils are considered as the secondary optimization objective. The constraints for the optimization are: maximum field on the NbTi module is lower than 6 T, and the length of one Nb₃Sn CICC conductor is shorter than 1 km. On the basis of the optimization design, the engineering scheme is determined. To verify the feasibility of the engineering scheme, mechanical analysis under the Lorentz force load is performed using ANSYS, the analysis results indicate the present design is reasonable.