Progress in the superconducting magnet technology through the ITER CS model coil programme

Okuno, Kiyoshi

Fusion magnets have major features of a large size, high magnetic field and operation under huge electromagnetic forces together with nuclear radiation. From this point of view, new design principles and fabrication concepts were proposed to build the ITER CS, and a model coil programme was performed for verification. The model coil reached its design point of 13 T and 46 kA, achieving all the goals of the development programme, including the following areas: (1) high-performance NbSn strand and mass production of about 26.5 t, (2) high-strength jacket materials (Incoloy 908, titanium, stainless steel) that can undergo NbSn heat treatment, (3) 46 kA cable-in-conduit conductors in a total length of 5 km, (4) insulation materials that can withstand up to 10 MGy radiation dose, (5) fabrication using wind-react-and-transfer method that enables Nb3Sn application to a large magnet with mechanically rigid and high-voltage insulated windings. Results and experiences from the programme are being fed back into the design and QA requirements of the ITER magnets.