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The construction of magnet system for the tokamak device of JT-60 super advanced (JT-60SA) was completed in March 2020. The manufacturing of CS had been finished in March 2019. The circularity of 4.0 mm is requirement for CS manufacturing from the point of view of plasma control. The high accurate manufacturing method and jigs had been developed and the circularity of CS achieves 1.44 mm, which meets the requirement of 4.0 mm. The clearance between the CS and the TF coils is very small, only 14 mm in design. The CS touches the TF coils and is subjected to load, the CS can be broken. Thus the surface dimension of the CS and the TF coils was measured before the installation of CS to confirm the clearance sufficient large to avoid the CS crashing in-to the TF coils. The CS was successfully installed to the tokamak center without any damages in December 2019 as the final step of magnet assembly of JT-60SA. In this paper, the manufacturing results and the installation of the CS are described

超電導コイルのコミッショニングでは、冷却前試験としてクエンチ検出用の高圧計測線の導通確認や、冷媒の温度計、圧力計、差圧計の動作確認およびコイル・給電機器の耐電圧試験を実施し異常のないことを確認した。冷却開始後は、コイルに20Aの電流を通電し、コイルの抵抗値変化および超伝導遷移温度の測定を実施する。4Kへの冷却が完了した後は、通電試験を実施し、問題なくプラズマ運転が行えることを確認する。発表では、コミッショングの状況・結果について報告した。, 第100回 低温工学・超電導学会研究発表会

The construction of a magnet system for the tokamak device of JT-60 super-advanced (JT-60SA) was completed in March 2020. The manufacturing of central solenoid (CS) had beenfinished in March 2019. The circularity of 4.0 mm is a requirement for CS manufacturing from the point of view of plasma control. The high accurate manufacturing method and jigs had been developed, and the circularity of CS achieves 1.44 mm, which meets the requirement of 4.0 mm. The clearance between the CS and the TF coils is very small, only 14 mm in design. In case the CS touches the TF coils and is subjected to load during operation, the CS can be damaged. Thus the surface dimensions of the CS and the TF coils have been measured before the installation of CS to confirm if the clearance is sufficient large to avoid the CS crashing into the TF coils. The CS was successfully installed to the tokamak center without any damages in December 2019 as the final step of the magnet assembly of JT-60SA. In this paper, the manufacturing results and the installation of the CS are described., Applied Superconductivity Conference 2020 (ASC2020)

Quantum and radiological science and technology performed a toroidal field (TF) insert coil (TFIC) test in 2016-2017, which was newly developed in 2014 with the ITER TF conductor, in the central solenoid model coil test facility. According to the test program, the TFIC underwent more than 1000 cycles of energization to 68 kA under a 10.8 T background field, which represents the lifetime electromagnetic loads of ITER TF coils. Then, five cycles of warm-up to 290 K and cool-down to a temperature lower than 5 K were also performed. Through the test campaign, the transition of the current sharing temperature (Tcs) was measured under the above energization condition. In parallel, two SULTAN test samples fabricated from the same TF conductor as the TFIC were tested by the similar test sequence to that of the TFIC, and the Tcsmeasurement results of the TFIC and the SULTAN samples were compared. In this paper, the test results mentioned above are reported.

The Central Solenoid (CS) insert coil consists of a 42-m-long CS conductor, of which the specifications are the same as that of the ITER CS. In order to investigate normal zone propagation and hot spot temperature, a quench test was carried out on the CS insert under End-of-Burn condition at 12.5 T and 45.1 kA of after 16,000 cycles. External heat was applied at nearly the center of the CS insert using an inductive heater, and quench was induced. A current of 45.1 kA was dumped 9.5 s (7 s) after voltage generation (Quench detection, QD). The Normal zone propagation length reached 23.4 m, and the maxim propagation velocity was 3.1 m/s just before dumping. Considering the distribution of temperature, which is calculated by GANDALF, hot spot temperature was expected to reach 227 K. As the result, it was found that the hot spot temperature exceeded the criteria of 150 K which is designed on ITER. However, heating the CS insert to 227 K did not influence conductor performance, because the current sharing temperature was maintained after the quench test. Therefore, the quench detection has a margin of approximately 9.5 s (7 s) after voltage generation (QD) in view of the conductor performance under the conditions applied in this quench test. If the hot spot temperature is kept to less than 150 K, the current should be dumped 7.5 s (5 s) before voltage generation (QD). These results are very useful for designing quench protection of the ITER CS.

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., Applied Superconductivity Conference 2018 (ASC2018)

JT-60SA is a tokamak device using superconducting coils to be built in Japan, as a joint international research and development project involving Japan and Europe. One design object of JT-60SA is maximization of the plasma volume and the instrumentation port availability in the condition that several buildings, heating instruments, and diagnostics of JT-60U are reused. The cryogenic pipe system of JT-60SA, which transfers cold helium from the helium refrigerator to cold components such as superconducting coils, thermal shield and divertor cryopumps, has two unique features due to the limited space mentioned above. One of them is a complicated path. Relatively small 11 valve boxes and 5 coil terminal boxes are separately installed around the tokamak cryostat asymmetrically, instead of a simple large distribution box and a current feeder box. The other is that several inlets to superconducting coils are placed on upper side of coils, which makes difficult requests for structural analyses because of the higher part of coils, the larger displacement due to the gravity load, the seismic load, vacuuming the cryostat, cooling down the cold components, and the electro-magnetic force by the plasma operation. For example, the cryogenic pipe interface of JT-60SA Toroidal Field Coil is displaced about 8 mm, 11mm and 38 mm toward radius, toroidal, and vertical direction. In order to determine the design, structural analyses are conducted using ANSYS® software, which is a finite element analysis tool. The analysis result must satisfy that the stress for all pipes and their support structures are lower than the allowable stress of the material and there is no physical interference with any other components as a result of displacement. In this work, the strategy of analysis and the design for JT-60SA cryogenic pipe system are reported., 30th Symposium on Fusion Technology (SOFT 2018)