EU-DEMO TF and CS Magnet Systems Design and Analyses Performed at CEA

While the ITER Tokamak is proceeding with major construction and assembly phases, design and R&D activities regarding the next step experimental reactor, the so-called DEMO machine, are underway in Europe. In particular, the magnet systems enter a refined design phase, under the general guidelines of Eurofusion, where winding packs (WP) are defined, conductor designs are proposed, and subscale analyses are performed in order to crosscheck the systems code (PROCESS) predimensioning. This paper summarizes the design iterations led at CEA on the toroidal field (TF) and central solenoid (CS) magnet systems. It presents, in particular, the optimization of the WP architecture with regard to the filling of the available space (TF) and flux maximization (CS). The paper gives the relevant electrical, thermal, and mechanical parameters for each system design, and tries to give insight on the tradeoffs and possible changes that could be implemented, given some margin on fixed systems code inputs. Finally, it also includes the refined magnetic field maps calculations performed to confirm the design operating field and explore other scenario time points that include poloidal field and plasma contributions.