2012 年 47 巻 3 号 p. 140-146
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.