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TY - CONF AU - Matsumoto, S. AU - Higo, T. AU - Kakihara, K. AU - Kamitani, T. AU - Tanaka, M. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Large-aperture Travelling-wave Accelerator Structure for Positron Capture of SuperKEKB Injector Linac J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - Comparing to the previous KEKB, the four-times higher charge of 4 nC per bunch is required for the injector linac of SuperKEKB. Not only a flux concentrator will be introduced but also the physical aperture of the downstream six 2m-long accelerator structures was increased as large as 30mm in diameter. We call these structures as LAS, “Large Aperture S-band” structure. The resultant higher RF group velocity of about 3% makes the acceleration gradient lower. In the nominal acceleration system, a 40MW klystron with SLED feeds four 2m-long accelerator structures producing 20MV/m acceleration field. The acceleration gradient higher than 14 MV/m is required for the very first two LAS structures to suppress the satellite bunches. This gradient is obtained by feeding only two LAS structures. Initially, ten LAS structures were installed and the RF processing has partly started. In the present paper, we firstly describe the acceleration system design and then present the processing characteristics through the RF processing without beam and with beam. PB - JACoW CP - Geneva, Switzerland SP - 3872 EP - 3874 KW - positron KW - operation KW - acceleration KW - linac KW - solenoid DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-THPRI047 UR - http://jacow.org/ipac2014/papers/thpri047.pdf ER -