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 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.
Construction and commissioning of the JT-60SA tokamak system
