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TY - CONF AU - Tian, K. AU - Sebek, J.J. AU - Vargas, J.L. ED - Schaa, Volker RW TI - Investigation of Transverse Beam Instability Induced by an In-vacuum Undulator at SPEAR3 J2 - Proc. of IBIC2016, Barcelona, Spain, Sept. 13-18, 2016 C1 - Barcelona, Spain T2 - International Beam Instrumentation Conference T3 - 5 LA - english AB - Vertical beam instabilities have been observed at SPEAR3 when a newly installed in-vacuum undulator (IVUN) is operated at a set of narrow gap settings. The source of the instabilities is believed to be vertically deflecting trapped modes inside the IVUN tank that are excited by the beam. We have used beam-based measurements to characterize the frequencies and strengths of the excited modes using both our bunch-by-bunch feedback system and a spectrum analyzer. Using numerical simulations of our IVUN structure, we have found modes with high shunt impedance near the measured frequencies. Recently, we have successfully measured these IVUN modes during our current downtime. In this paper, we will report on the measurements, simulations, and plans to damp these modes. PB - JACoW CP - Geneva, Switzerland SP - 31 EP - 34 KW - simulation KW - coupling KW - operation KW - vacuum KW - insertion-device DA - 2017/02 PY - 2017 SN - 978-3-95450-177-9 DO - 10.18429/JACoW-IBIC2016-MOPG03 UR - http://jacow.org/ibic2016/papers/mopg03.pdf ER -