@article{oai:repo.qst.go.jp:00084562,
 author = {Akeshi Takahashi and Suto, Tetsuya and Tanaka, Toshiaki and Yamaguchi, Kohei and Hiroyuki Fujita and Hiranuma, Yuki and Satoshi Ichimura and Kazuhiro, Watanabe and Mieko, Kashiwagi and Tetsuya, Maejima and Hiroyuki, Tobari and Kazuhiro, Watanabe and Mieko, Kashiwagi and Tetsuya, Maejima and Hiroyuki, Tobari},
 issue = {5},
 journal = {IEEE Transactions on Industry Applications},
 month = {Sep},
 note = {This article presents the development results of a five-stage dc-1 MV rectifier for an international thermonuclear experimental reactor neutral beam injector system. Each rectifier outputs -200 kV, and the total five rectifiers are connected in a series. The feasibility of both gas insulation and gas cooling for semiconductor devices was validated to achieve dc-1 MV output and 1-h continuous operation. We devised a novel structure of cylindrical dense alignment of the heatsinks with stud-type diodes, which enables both the mitigation of electric-field concentration on the heatsinks and the improvement of heat dissipation from diodes. The difference in the temperature rise for three different directions of the heatsink in an SF 6 gas atmosphere was also clarified. The heat flow was analyzed to quantify the cooling effect of SF 6 gas, taking into account the gas circulation by the external cooling system. Rectification operation and temperature rise were tested with an actual-scale rectifier including a step-up transformer. Additionally, dc-1.2 MV withstand voltage was tested for a fifth-stage actual-scale rectifier. The test results demonstrated the validity of the proposed design.},
 pages = {4398--4408},
 title = {1 MV Rectifier With SF6-Gas Insulation and Cooling for ITER Neutral Beam Injector System},
 volume = {57},
 year = {2021}
}