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TY - CONF AU - Takai, R. AU - Honda, T. AU - Nogami, T. AU - Obina, T. AU - Tanimoto, Y. ED - Schaa, Volker RW ED - Jansson, Andreas ED - Shea, Thomas ED - Olander, Johan TI - Design and Properties of a New DCCT Chamber for the PF-Ring at KEK J2 - Proc. of IBIC2019, Malmö, Sweden, 08-12 September 2019 CY - Malmö, Sweden T2 - International Beam Instrumentation Conferenc T3 - 8 LA - english AB - A DC current transformer (DCCT) for the PF-ring was renewed during the 2018 summer shutdown. A vacuum chamber for the new DCCT was designed based on a circular duct with an inner diameter of 100 mm and has a structure housing a toroidal core inside of electromagnetic shields. The geometry of the ceramic break for interrupting the wall current flow was optimized using a three-dimensional electromagnetic field simulator, and the break was fabricated considering some technical limitations. Both ends of the ceramic break were short-circuited in a high-frequency manner by a sheet-like capacitive structure to suppress the radiation of unneeded higher-order modes (HOMs) into the core housing. The ceramic break is also equipped with water-cooling pipes on metal sleeves brazed to the both ends to efficiently remove the heat generated by HOMs. The new DCCT chamber has been used already in user operation without any problems. A temperature rise near the ceramic break is still approximately six degrees Celsius, even when a 50-mA isolated bunch is stored. PB - JACoW Publishing CP - Geneva, Switzerland SP - 91 EP - 95 KW - simulation KW - impedance KW - operation KW - HOM KW - cavity DA - 2019/11 PY - 2019 SN - 2673-5350 SN - 978-3-95450-204-2 DO - doi:10.18429/JACoW-IBIC2019-MOPP010 UR - http://jacow.org/ibic2019/papers/mopp010.pdf ER -