Conceptual Design of Magnet System for JT-60 Super Advanced (JT-60SA)

At Japan Atomic Energy Agency (JAEA), the JT-60 is planned to be modified to a full-superconducting tokamak referred as JT-60 Super Advanced (JT-60SA) as one of the JA-EU broader approach projects. In JT-60SA, the magnet system with 1400 ton consists of 18 toroidal field (TF) coils, 4 stacks of central solenoid (CS) and 7 plasma equilibrium field (EF) coils. The TF coil with using the NbTi cable-in-conduit (CIC) conductor has the maximum magnetic field of 6.4 T in winding, the magnetomotive force of 8.2 Tm and the magnetic stored energy of 1.5 GJ which is 1.5 times larger than present superconducting fusion devices. The conductor for CS which is the Nb₃Sn CIC conductor with the maximum magnetic field of 10 T was newly designed to increase the flux swing capability for the ITER plasma simulation and to accommodate the diminution of available space because of the TF coil with NbTi conductor. For CS, the faster maximum varying field of 2.88 T/s is required because of fast plasma initiation scenario of JT-60SA.