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TY - CONF AU - Wang, H. AU - Dai, J.P. AU - Qin, Q. AU - Rimmer, R.A. AU - Teytelman, D. AU - Wang, S. AU - Xing, J. AU - Yue, J.H. AU - Zhang, Y. ED - Koscielniak, Shane ED - Satogata, Todd ED - Schaa, Volker RW ED - Thomson, Jana TI - Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS 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 - Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference. PB - JACoW Publishing CP - Geneva, Switzerland SP - 390 EP - 393 KW - cavity KW - experiment KW - feedback KW - beam-loading KW - luminosity DA - 2018/06 PY - 2018 SN - 978-3-95450-184-7 DO - 10.18429/JACoW-IPAC2018-MOPMK017 UR - http://jacow.org/ipac2018/papers/mopmk017.pdf ER -