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Mastorides, T.

Paper Title Page
WEOBM02 Lessons Learned from PEP-II LLRF and Longitudinal Feedback 1953
 
  • J. D. Fox, T. Mastorides, C. H. Rivetta, D. Van Winkle
    SLAC, Menlo Park, California
  • D. Teytelman
    Dimtel, San Jose
 
  The PEP-II B Factory is in the final phase of operation at 2X the design current and 4X the design luminosity. Since the original design the machine has added 8 1.2 MW Klystrons and 12 RF cavities, and the machine is operating with longitudinal instability growth rates roughly 5X in excess of the original estimates. Since commissioning there has been continual adaptation of the LLRF control strategies, configuration tools and new hardware in response to unanticipated technical challenges. This paper presents the LLRF and feedback system evolution from the original design estimates through to the 1.2·1034 final machine. We highlight issues of RF station stability, the interplay of LLRF configuration and low-mode (cavity fundamental driven) longitudinal instabilities, impacts of non-linearities and imperfections in the LLRF electronics, control of HOM driven beam instabilities and the development of configuration tools and measurement techniques to optimally configure the LLRF over the wide range of operating currents. We present valuable "lessons learned" which are of interest to designers of next generation impedance controlled LLRF systems.  
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THPC125 Modeling and Simulation of the Longitudinal Beam Dynamics-RF Station Interaction in the LHC Rings 3278
 
  • T. Mastorides, J. D. Fox, C. H. Rivetta, D. Van Winkle
    SLAC, Menlo Park, California
  • P. Baudrenghien, J. Tuckmantel
    CERN, Geneva
 
  A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to study the effect of RF station noise, impedance, and perturbations on the beam life and longitudinal emittance. It will be also used to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It allows the study of alternative LLRF implementations and control algorithms. The insight and experience gained from our PEP-II simulation is important for this work. In this paper we discuss properties of the simulation tool that will be helpful in analyzing the LHC RF system and its initial results. Partial verification of the model with data taken during the LHC RF station commissioning is presented.