The Joint Accelerator Conferences Website (JACoW) is an international collaboration that publishes the proceedings of accelerator conferences held around the world.
TY - CONF AU - Kobayashi, T. AU - Akai, K. ED - Zhao, Ning ED - Poole, John ED - Schaa, Volker RW TI - LLRF Controls Including Gap Transients at KEKB and Plans for SuperKEKB J2 - Proc. of eeFACT2016, Daresbury, UK, October 24-27, 2016 C1 - Daresbury, UK T2 - ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e^+e^- Colliders T3 - 58 LA - english AB - Features of LLRF control systems in KEKB and SuperKEKB will be reviewed, and the evaluation of the bunch gap transient effect on beam phase will be presented for SuperKEKB. The RF systems of KEKB are being reinforced to handle triple as large beam power for upgrade to SuperKEKB. Furthermore, a new LLRF control system, which is based on a recent digital control technique, has been developed. For nine RF stations, among a total of thirty, the LLRF control system has been replaced with new ones. They were worked successfully in the Phase-1 commissioning. Bunch phase shift along the bunch train due to a bunch gap transient is a concern. In KEKB operation, a rapid phase change was observed at the leading part of the train, which was not predicted. Our new simulation study clarified that the rapid phase change is caused by a transient loading in the three-cavity system of ARES. And the new simulation shows that the phase change will be much large in SuperKEKB. The main issue is the difference in beam phase change between the two rings for the asymmetry colliding. The measures by means of mitigation of the relative beam phase difference between the two rings will be also suggested. PB - JACoW CP - Geneva, Switzerland SP - 177 EP - 184 KW - ion KW - cavity KW - controls KW - LLRF KW - simulation DA - 2017/07 PY - 2017 SN - 978-3-95450-187-8 DO - 10.18429/JACoW-eeFACT2016-WET2H7 UR - http://jacow.org/eefact2016/papers/wet2h7.pdf ER -