FT/P1-6 · Development of advanced superconducting coil technologies for the National Centralized Tokamak
K. Kizu1), Y.M. Miura1), K. Tsuchiya1), T. Ando2), N. Koizumi1), K. Matsui1), A. Sakasai1), H. Tamai1), M. Matsukawa1), S. Ishida1), K. Okuno1)
1) Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Japan
2) Nippon Advanced Technology, Tokai-mura, Naka-gun, Japan
Abstract: Advanced technologies of fabricating superconducting coils for the National Centralized Tokamak (NCT) which is based on a modification of JT-60 have been developed. One of the developed technologies is the application of the react-and-wind (R&W) method to the fabrication of a Nb3Al D-shaped coil. In order to form the D-shape that simulates the actual toroidal field (TF) coil curvatures, the winding technique of the conductor including “over bending” was developed. The energizing tests of the D-shaped coil were successfully carried out in 2003. We found that the bending strain due to the R&W method did not affect the critical current (Ic) characteristics of the conductor. This finding indicates the possibilities that manufacturing cost of large size coils can be reduced further by downsizing the heat treatment furnace and complex shape coils such as a helical type can be manufactured by using the Nb3 Al conductor. Another technology is an advanced winding technique, in which bending strains are loaded on the conductor, for the reduction of the AC losses of a Nb3 Sn coil, which is generally made by the wind-and-react (W&R) method. Effectiveness of this technique was experimentally demonstrated. Other technology, such as a high copper/non-copper (Cu/non-Cu) ratio NbTi strand with fine filaments, is also developed.
Keywords: cable-in-conduit conductor, Nb3Sn superconductor, NbTi superconductor, superconductor,