The ITER superconducting magnet system consists of 18 Toroidal Field (TF) coils, six Central Solenoid (CS) modules, six Poloidal Field (PF) coils and 18 Correction Coils. The Japan Atomic Energy Agency (JAEA), serving as the Japanese Domestic Agency (JADA) in the ITER project, is responsible for the procurement of nine TF coil winding packs (WP), structures for 19 TF coils (including one spare), and assembly of the WP and the coil structures for nine TF coils. JAEA signed the procurement arrangements for the TF conductor in November 2007 and the ones for the nine TF coils and their TF coil structures in November 2008. The manufacture of the TF conductor has already started and its progress is reported in this special issue. In addition, sub- and full-scale trials were performed to achieve compliance for the manufacturing procedure of the TF coil and its structure. These results are also reported in detail in this special issue. Based on these successful results, JAEA is planning to start manufacturing the first TF coil from 2012 to meet the required schedule and complete the 18th TF coil at the end of 2017 in cooperation with the European Domestic Agency (F4E).
Superconducting conductors are applied in the toroidal field (TF) coils, poloidal field coils, and central solenoid (CS) in the ITER. The Japan Atomic Energy Agency plans to procure 25% of the TF conductors and 100% of the CS conductors. Mass-produced Nb 3Sn superconducting strands for TF conductors have been supplied by two manufacturers since 2008. The total length of the strands is approximately 23,000 km; thus, quality control is extremely important. A statistical process control has been adopted in order to reduce the dispersion of strand performance, and stable performance of the mass-produced strands was achieved. Both manufacturers improved the fabrication yield through mass production. Approximately 72% of the Japanese share in TF strands has been produced as of October 2011.