The ITER magnet system-present status of design and R&D programme

The superconducting coil systems for the International Thermonuclear Experimental Reactor (ITER) will consist of 24 toroidal field (TF) coils of 488 tonnes each, a central solenoid (CS) at 964 tonnes, and an external poloidal field (PF) coil set or 6 coils, the largest of which has a diameter of 30 m. The ITER magnets represent a large step from existing superconducting magnet technology in terms of their size, field level and reliability requirements. The superconducting coils for the system will require about 1600 tonnes of Nb₃Sn strand and will use a cable-in-conduit conductor operating at the 50 kA level and a maximum field at the windings of 13 T. The TF coils and the CS are layer wound. The design features of each of these systems are described. An extensive R&D program has been initiated for component development and design verification. The focus is on the manufacture and testing of model coils that will demonstrate manufacturing feasibility and operation in conditions relevant to those of the full scale magnets