@misc{oai:repo.qst.go.jp:00081678,
 author = {Hayashi, Takao and Takechi, Manabu and Matsunaga, Go and Isayama, Akihiko and Hayashi, Takao and Takechi, Manabu and Matsunaga, Go and Isayama, Akihiko},
 month = {Sep},
 note = {A lower divertor cassette of JT-60SA, which is the largest superconducting tokamak, has been designed, and the first divertor cassette covering a 10◦ sector in the toroidal direction has been manufactured. Modularized plasma facing components such as vertical targets, baffles, and domes will be assembled into the divertor cassette. All plasma facing components will be actively cooled. Carbon armor tiles bolted to water-cooled copper alloy heat sinks are used to remove heat loads of 0.3–2MW/m2 for 100 s and 10MW/m2 for less than 10 s. The divertor cassette integrated with coolant pipe connections will be used for remote handling / hands-on maintenance.  A remote pipe welding tool, which is accessed from the inside of the pipe, has been developed to assemble the inboard vertical target. The space around the cooling pipes is so limited that they are cut and welded remotely from the inside for maintenance. The laser welding method was used, and the focusing mirror inside the pipe was rotated to perform circumferential welding. As a countermeasure for welding groove misalignment, the aiming accuracy of the laser was improved by simultaneously controlling the rotation and lifting of the tool. Thereby, reliable welding has been achieved even with a groove that is misaligned by 0.5 degrees or more. The outer diameter of the cooling pipe is 59.8 mm, the wall thickness is 2.8 mm, and the material is SUS316L. After connecting the inboard vertical target, the other plasma facing components have been assembled into the first lower divertor cassette. When installing the divertor cassette towards the vacuum vessel, the laser welding tool described above is used to connect the cooling pipe between divertor cassette and vacuum vessel in JT-60SA, because the outer diameter and wall thickness of the cooling pipe are the same as the inboard vertical target., 31st Symposium on Fusion Technology (SOFT2020)},
 title = {Manufacturing of lower divertor cassette of JT-60SA},
 year = {2020}
}