Coupling loss optimization of central solenoid cable-in-conduit conductor for next generation fusion reactor by experiments and modeling

Abstract The next generation tokamak aiming to carry out D–T experiments and to demonstrate power generation, is under development at the Institution of Plasma Physics, Chinese Academy of China (ASIPP). A hybrid magnet configuration is proposed for the central solenoid (CS) coil of this tokamak, a high-temperature superconducting coil is inserted into an outer Nb 3 Sn coil for increasing the flux. Minimization of the coupling losses is investigated in the Nb 3 Sn cable-in-conduit conductor (CICC) with rectangular cross-section for the outer CS coils using numerical modeling and experimental verification. The AC loss was measured on several candidate conductors with a superconducting AC Dipole at ASIPP and the numerical modeling was performed with the JackPot-AC/DC © model, which was developed by University of Twente (UT). The data from the experiments tested in UT were used for calibrating and validating the model computations. With the model, further optimization on cable parameters was then carried out. The results show that the twist pitch (TP) of the first stage and the TPs ratio have an important impact on the rectangular CICC coupling loss, and the influences of these two factors are related. In addition, the use of a rectangular cross-section CICC can have significant advantages when used in CS magnets.