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TY - CONF AU - Shibata, T. AU - Fan, K. AU - Ishii, K. AU - Matsumoto, H. AU - Sugimoto, T. ED - Koscielniak, Shane ED - Satogata, Todd ED - Schaa, Volker RW ED - Thomson, Jana TI - The Development of a New Low Field Septum Magnet System for Fast Extraction in Main Ring of J-PARC J2 - Proc. of IPAC2018, Vancouver, BC, Canada, April 29-May 4, 2018 C1 - Vancouver, BC, Canada T2 - International Particle Accelerator Conference T3 - 9 LA - english AB - The J-PARC Main Ring (MR) is being upgraded to improve its beam power to the design goal of 750 kW. One important way is to reduce the repetition period from 2.48 s to 1.3 s so that the beam power can be nearly doubled. We need to improve the septum magnets for fast extraction. We are improving the magnets and their power supplies. The present magnets which are conventional type have problem in durability of septum coil by its vibration, and large leakage field at the flange of the beam duct. The new magnets are eddy current type. The eddy current type does not have septum coil, but has a thin plate. We expect that there is no problem in durability, we can construct the thin septum plate, the leakage field can be reduced. The output of the present power supply are pattern current which of flat top is 10 ms width, the new one is short pulse which of one is 10 us. The short pulse consists of 1st and 3rd higher harmonic. We can expect that the flatness and reproducibility of flat top current can be improved. The calorific power can be also reduced. This paper will report the performance of the power supply and its magnetic field with the eddy septum magnet systems. PB - JACoW Publishing CP - Geneva, Switzerland SP - 981 EP - 983 KW - septum KW - power-supply KW - operation KW - controls KW - feedback DA - 2018/06 PY - 2018 SN - 978-3-95450-184-7 DO - 10.18429/JACoW-IPAC2018-TUPAK010 UR - http://jacow.org/ipac2018/papers/tupak010.pdf ER -