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Title Multimodal Interaction in the ALS Longitudinal Feedback Kicker RF Cavity
  • S. De Santis, K.M. Baptiste, J.M. Byrd, S. Kwiatkowski, T.H. Luo, E.R. Sanmateo, C. Steier, C.A. Swensonpresenter
    LBNL, Berkeley, California, USA
  • F. Marcellini
    PSI, Villigen PSI, Switzerland
Abstract RF cavities are essential components in particle accelerators not only for beam acceleration, but also for control purposes (bunch lengthening/shortening, deflecting and crabbing, transverse and longitudinal kickers) and for beam diagnostics (BPM). Normally, only a single resonating mode is actively used, although other modes can be excited by the circulating beam. Cavities used as feedback longitudinal kickers are designed with an axial mode which, appropriately excited, provides a kick to the circulating bunches for maintaining beam stability. To provide the necessary bandwidth this mode has to be strongly damped resulting in quality factors of just a few units. In the longitudinal feedback kicker cavity just installed on the ALS we have detected a second axial mode which, although a few hundreds of MHz below the 1.4 GHz design mode, is also strongly damped and has a shunt impedance high enough to be appreciably excited by the feedback amplifier coupling to the first mode. In this paper we show bench measurements on the cavity and with beam during its commissioning and discuss the interaction of the two modes resulting in a modulation of shunt impedance and phase response.
Funding The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
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Conference IPAC2016, Busan, Korea
Series International Particle Accelerator Conference (7th)
Proceedings Link to full IPAC2016 Proccedings
Session Poster Session
Date 11-May-16   16:00–18:00
Main Classification 06 Beam Instrumentation, Controls, Feedback and Operational Aspects
Sub Classification T05 Beam Feedback Systems
Keywords cavity, kicker, feedback, resonance, impedance
Publisher JACoW, Geneva, Switzerland
Editors Christine Petit-Jean-Genaz (CERN, Geneva, Switzerland); Dong Eon Kim (PAL, Pohang, Republic of Korea); Kyung Sook Kim (PAL, Pohang, Republic of Korea); In Soo Ko (POSTECH, Pohang, Republic of Korea); Volker RW Schaa (GSI, Darmstadt, Germany)
ISBN 978-3-95450-147-2
Published June 2016
Copyright © 2016 by JACoW, Geneva, Switzerland     CC-BY Creative Commons License
cc Creative Commons Attribution 3.0