Technology development and mass production of Nb
Sn conductors for ITER toroidal field coils in Japan
Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; Uno, Yasuhiro; Tsutsumi, Fumiaki; Yoshikawa, Masatoshi*; Nakajima, Hideo; Okuno, Kiyoshi; Devred, A.*; Mitchell, N.*
Japan Atomic Energy Agency is procuring the Nb
Sn superconductors for Toroidal Field (TF) Coils under the ITER project. Because manufacturing amount of Nb
Sn strands is quite large compared with the past experience and required superconducting performance is higher than that of the model coils which have been fabricated and tested in the ITER-EDA, quality control technique is very important for the manufacture of the strands. Sophisticated control technique is also required for the jacketing, in order to fabricate the conductors with the precise outer diameter and without leakage at welding part. This paper summarizes the technical developments leading to the first successful mass production of ITER TF conductors.