Mass production technology of ITER conductors; Investigation of twist pitch variation

Takahashi, Yoshikazu; Nabara, Yoshihiro; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Oshikiri, Masayuki; Tsutsumi, Fumiaki; Uno, Yasuhiro; Hamada, Kazuya; Shibutani, Kazuyuki*; Yano, Yoshitaka*; Ishibashi, Tatsuji*; Tsuzuku, Seiji*; Murakami, Yukinobu*; Teshima, Osamu*

In the ITER project, Japan Atomic Energy Agency (JAEA) is the first to start the mass production of the TF conductors in March 2010 among the 6 parties who are procuring TF conductors in the ITER project. The height and width of the TF coils are 14 m and 9 m, respectively. The conductor is cable-in-conduit conductor (CICC) with a central spiral. A circular multistage superconducting cable is inserted into a circular stainless steel jacket with a thickness of 2 mm. A total of 900 NbSn strands and 522 copper strands are cabled around the central spiral and the cable is inserted into a round-in-round stainless steel jacket. It was observed that the cabling pitch of the destructive sample is longer than the original pitch at cabling. The JAEA carried out the tensile tests of the cable and the measurement of the cable rotation during the insertion to investigate the cause of the elongation. The cause of elongation was clarified and the results will be described in this paper.