量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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The construction of a full-superconducting tokamak referred as JT-60 Super Advanced (JT-60SA) is in progress under the JA-EU broader approach projects. The magnet system of JT-60SA consists of 18 toroidal field (TF) coils, 4 modules of central solenoid (CS) and 6 equilibrium field (EF) coils. TF coils are procured by EU and CS, EF coils and current feeding system are procured by JA.
The current feeding system consists in-cryostat superconducting feeders and coil terminal boxes (CTBs). High Temperature Superconductor Current Leads (HTSCLs) are installed to the CTBs between room temperature busbars and superconducting current feeders to reduce the heat load for the cryoplant. There are five separated CTBs (CTB1-CTB5) to be installed to JT-60SA magnet system because of the small available space in torus building. Since the maximum allowable magnetic field of HTSCL is 33 mT, CTB main body is more than 12 m away from tokamak center.
Design of in-cryostat feeders are complicated because they are required to have flexibility and rigidity. In-cryostat feeders need to withstand large displacement of coils up to 38 mm in vertical direction, 20 mm in radial direction and 16 mm in toroidal direction due to shrinkage during cooling down and electromagnetic force during operation. Therefore some in-cryostat feeders have loop shape parts to increase the flexibility of in-cryostat feeders. On the other hand, in-cryostat feeders are required to withstand acceleration due to earthquake of 0.4 G (+1.0 G) in vertical direction and 0.6 G in horizontal direction. Therefore we added the supports at suitable position to increase the rigidity and keep the flexibility of in-cryostat feeders. The design of in-cryostat feeders for JT-60SA were fixed using FEM calculation.
Manufacturing of CTBs and in-cryostat current feeders started in 2014. First CTB (CTB1) was completed in February 2017 and CTB1 was used for the cold tests to validate the manufacturing design. CTB4 and CTB5 were completed in December 2017 and in-cryostat current feeders were also completed in May 2018. Manufacturing of remaining 2 CTBs (CTB2 and CTB3) will be finished in October 2018. CTBs and in-cryostat current feeders will be installed to the tokamak in 2019.
In this paper, the final design of CTBs and in-cryostat current feeders are described. And the results of cold test of CTB1 is reported.
Final design and manufacturing progress of the current feeders and coil terminal boxes for JT-60SA
