Superconducting magnet system in a fusion reactor

Higher magnetic field of a Toroidal field (TF) coil in a tokamak fusion reactor can offer better performance of the reactor. Therefore, fusion magnet development always drives a new superconductor to be used in a large magnet on an industrial basis. Magnets for the International Thermonuclear Experimental Reactor (ITER) use Nb3Sn in order to generate a peak magnetic field of 13 T. Technologies for Nb3Sn superconductor has made a significant progress through the extensive development in ITER including the manufacture of model coils. A next generation superconductor, Nb3Al, has outstanding features of large critical current density at higher field and smaller degradation of the critical current due to a strain compared to Nb3Sn. High temperature superconductor (HTS) is another candidate, and if it becomes available, a magnetic filed above 20 T can be realized in a large magnet. These materials have the possibility of being used for high performance fusion reactors.