Completion of the first ITER toroidal field coil in Japan

• Published in: Nuclear fusion 2021-11, Vol.61 (11), p.116044
• Main Authors: Nakamoto, M., Baba, T., Kasai, Y., Sakamoto, K., Shimane, H., Shimizu, T., Saito, K., Nakahira, M., Koizumi, N., Inoue, M., Fujiwara, E., Shichijo, T., Kuno, K., Yamane, M., Hasegawa, M., Luongo, C.
• Format: Article
• Language: English
• Subjects: current center line (CCL); ITER; tolerance; toroidal field coil
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/1741-4326/ac26ed

The first ITER toroidal field coil (TFC) has been successfully manufactured by the Japanese Domestic Agency in January 2020. The ITER TFCs are the largest Niobium Tin (Nb 3 Sn) superconducting magnets in the world; each is enclosed in an austenitic stainless-steel case with a height of 16.5 m and total weight is 310 tons (Knaster et al 2008 IEEE Trans. Appl. Supercond. 18 495–498). A set of 18 TFCs will be installed around vacuum vessel to function as a plasma confinement magnet system. The responsibility to procure 18 TFCs and 1 spare coil is shared between European Domestic Agency and Japanese Domestic Agency (Bellesia et al 2020 IEEE Trans. Appl. Supercond. 30 4202205; Sborchia et al 2008 IEEE Trans. Appl. Supercond. 18 463–466). To hold a common magnetic and geometrical properties among all the TFCs, tight tolerances of sub-millimeter order are defined on each TFC. The fabrication of those massive magnets with such tight tolerances involved some major technical challenges. These technical challenges were solved by pre-assessment and process qualification through some qualification trials. As a result, techniques established to solve those challenges were implemented to the TFC manufacturing, leading to the successful completion of the first TFC. The details are described in the paper.