Development of Full-size Mockup bushing for 1 MeV ITER NB System

Full text: For verification of feasibility and a voltage holding capability of the high voltage bushing in the ITER NB system, manufacturing of a mockup and voltage holding test were performed at JAEA. A large bore ceramic ring (1.56 m in outer diameter) as an insulator of the high voltage bushing has been successfully brazed with 3 mm thick ring-shaped Kovar sleeves. After accomplishment of brazing of the ceramic, full-size mockup bushing was manufactured. Voltage holding of the mockup bushing at -200 kV for 3600 s has been demonstrated in the single-stage full-size mockup bushing. Vacuum insulation in a large insulator was discussed from the view point of electric field design toward 1 MeV ITER NB system. (author)