Completion of Central Solenoid for JT-60SA

The construction of a magnet system for the tokamak device of JT-60 super-advanced (JT-60SA) was completed inMarch 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 theTF 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

Manufacturing and Welding Assembly of the Vacuum Vessel on JT-60SA

幅広いアプローチ活動の一環として実施されるサテライト・トカマク計画として、JT-60SAのトカマク本体の組立を進めている。今回、これまでに進めてきたJT-60SA装置の真空容器の製作技術と現地組立を中心に報告する。真空容器は、高さ6.6m、大半径5m、重量150トンの二重壁トーラス構造で、10個のセクターに分割して製作し、これらを現地に搬入して一体化した。トーラス形状と寸法を調整するため、セクターを直接突き合わせて溶接接続する方法と、セクター間にスプライス板を用いて接続する方法を併用した。本報告では、真空容器の設計概念と共に、真空容器の製作と組立の結果について詳細を報告する。14th International Symposium on Fusion Nuclear Technolog

Development of the thermal insulation devices for the JT-60SA tokamak

This report focuses on the development of the thermal insulation devices including thermal shield (TS) and cryostat for the superconducting tokamak JT-60SA.1. Design, manufacturing and acceptance test were successfully completed by 2019 and installation will be done by March 2020.2. The technique and knowledge to realize high accuracy manufacturing and short time installation of these devices will contribute to the ITER construction and DEMO design.28th IAEAFusion Energy Conferenc

Achievement of Precise Assembly of the JT-60SA Superconducting Tokamak

The JT-60 Super Advanced (JT-60SA) tokamak construction has been achieved respecting the requirements of very tight tolerance for the assembly and by handling very heavy components in a very close space environment. The construction of this large superconducting tokamak represents a big step forward in the world nuclear fusion history, opening the road for ITER and DEMO. Precise assembly is required, not only to avoid mechanical interference, but also to obtain good plasma performance by less magnetic error field. To complete this work, unique and well-considered procedures were introduced. In this paper, the developed technologies and their results are reported, focusing on the assembly of the final sector of vacuum vessel, central solenoid and in-vessel components.28th IAEAFusion Energy Conferenc

Achievement of precise assembly of the JT-60SA superconducting tokamak

The JT-60 Super Advanced (JT-60SA) tokamak was constructed with very tight tolerances for assembly and handling of heavy components in an enclosed space. Millimetre-order precision was required for the tokamak assembly, not only to avoid mechanical interference, but also to obtain good plasma performance by keeping the magnetic error field low. This effort entailed the development of numerous unique procedures. This paper reports on these procedures, focusing on assembly and testing of the final sector of the vacuum vessel, the central solenoid, top parts of the tokamak, and the in-vessel components

Construction and commissioning of the JT-60SA tokamak system

The construction of the JT-60 Super Advanced (JT-60SA) tokamak has been completed after seven years. In parallel to the tokamak construction, peripheral devices such as vacuum pumping system, gas baking system, wall cleaning system, and so on, that are indispensable for tokamak operation, have been modified for reuse or newly developed. In the JT-60SA, an ultra-high vacuum up to ~10-6Pa is to be realized by eight turbomolecular pumps with a total pumping speed of 6m3/sec for a vacuum vessel. To achieve an ultra-high vacuum condition, a baking operation with 200 ℃ is planned for desorbing water by Nitrogen gas circulation into a double shell of the vacuum vessel. The gas circulation system has a high flow rate of ~18,000 Nm3/h for 200 ℃ baking with four blowers and a heater. Since a radiant heat from the vacuum vessel will be absorbed by an 80 K thermal shield, the system is also utilized to keep vacuum vessel temperature 50 ℃.Moreover, a glow discharge system has been developed for wall conditioning. The system contains three electrodes installed into the vacuum vessel and power supplies with ~3A/600V. The system makes Helium glow discharge where impurities such as Oxygen could be effectively spattered from graphite first wall. In this paper, the completion of JT-60SA construction and the peripheral devices will be reported, focusing on the results of commissioning before the initial operation.31st Symposium of Fusion Technology (SOFT2020