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

The world\´s largest high-field pulsed super conducting magnet, the CS model coil, was manufactured and tested by the international and participant teams for the verification of new design principles and fabrication concepts proposed for the ITER CS. State-of-the-art technologies were developed through the CS model coil program including high-performance Nb₃Sn strand, 46 kA cable-in-conduit conductor, and coil fabrication using "wind, react, insulate and transfer" method that enables Nb₃Sn to be applicable to a large magnet with mechanically rigid and high-voltage insulated windings. The CS model coil reached its design point of 13 T and 46 kA and demonstrated the pulsed operation of 0.6 T/s to 13 T, achieving all the development goals. The experiments of the CS model coil and three single-layer inserts have provided detailed knowledge on the performances of the coils and conductors including the hydraulic behavior, AC losses and critical currents. In particular, significant effects of large electromagnetic forces acting on the conductor were observed in these performances and the movement of cable inside the conductor was identified to be important. Results and experiences from the program are not only useful for the design optimization of the ITER magnets, but also applicable to other areas such as high energy physics.