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Van Winkle, D.

Paper Title Page
MPPP007 Operating Performance of the Low Group Delay Woofer Channel in PEP-II 1069
 
  • D. Teytelman, J.D. Fox, D. Van Winkle
    SLAC, Menlo Park, California
 
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

In PEP-II collider a dedicated low group-delay processing channel has been developed in order to provide high damping rates necessary to control the fast-growing longitudinal eigenmodes driven by the fundamental impedances of the RF cavities. A description of the digital processing channel operating at 9.81 MHz and capable of supporting finite impulse response (FIR) controllers with up to 32 taps will be presented. A prototype system has been successfully commissioned in the High-Energy Ring (HER) in May 2004. Operating experiences with the prototype and the newly determined limits on achievable longitudinal damping will be discussed and illustrated with experimental data.

 
WPAT041 Klystron Linearizer for Use with 1.2 MW 476 MHz Klystrons in PEP-II RF Systems 2660
 
  • J.D. Fox, T. Mastorides, D. Teytelman, D. Van Winkle, Y.-B. Zhou
    SLAC, Menlo Park, California
  • A. Gallo
    INFN/LNF, Frascati (Roma)
 
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The direct and comb loop feedback around the RF cavities in PEP-II is critical in reducing longitudinal instabilities driven by the cavity impedance, and the non-linear 1 MW klystron is in the signal path for these feedback loops. As a result, the effective small-signal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power amplifier. A klystron linearizer circuit has been developed which operates in series with the power amplifier and acts to equalize the small and large signal gains through the combination. The technique must implement a 1 MHz linear control bandwidth over roughly 15 dB of RF signal level variation. The dynamics of this system is operating point dependent, and the channel must have dynamic gain compensation to keep the linearity compensation loop stable over changes in operating point. The design of this non-linear signal processing channel (incorporating RF and DSP techniques) and measured results from full-power klystron testing are presented.

 
WPAT074 In Depth Diagnostics for RF System Operation in the PEP-II B Factory 3931
 
  • D. Van Winkle, J.D. Fox, D. Teytelman
    SLAC, Menlo Park, California
 
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The PEP-II RF systems incorporate numerous feedback loops in the low-level processing for impedance control and operating point regulation. The interaction of the multiple loops with the beam is complicated, and the systems incorporate online diagnostic tools to configure the feedback loops as well as to record fault files in the case of an RF abort. Rapid and consistent analysis of the RF-related beam aborts and other failures is critical to the reliable operation of the B-Factory, especially at the recently achieved high beam currents. Procedures and algorithms used to extract diagnostic information from time domain fault files are presented and illustrated via example interpretations of PEP-II fault file data. Example faults presented will highlight the subtle interpretation required to determine to root cause. Some such examples are: abort kicker firing asynchronously, klystron and cavity arcs, beam loss leading to longitudinal instability, tuner read back jumps and poorly configured low-level RF feedback loop.

 
TPPP035 Performance of the PEP-II B-Factory Collider at SLAC 2369
 
  • J. Seeman, J. Browne, Y. Cai, S. Colocho, F.-J. Decker, M.H. Donald, S. Ecklund, R.A. Erickson, A.S. Fisher, J.D. Fox, S.A. Heifets, R.H. Iverson, A. Kulikov, N. Li, A. Novokhatski, M.C. Ross, P. Schuh, T.J. Smith, K.G. Sonnad, M. Stanek, M.K. Sullivan, P. Tenenbaum, D. Teytelman, J.L. Turner, D. Van Winkle, M. Weaver, U. Wienands, M. Woodley, Y.T. Yan, G. Yocky
    SLAC, Menlo Park, California
  • M.E. Biagini
    INFN/LNF, Frascati (Roma)
  • W. Kozanecki
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • C. Steier, A. Wolski
    LBNL, Berkeley, California
  • G. Wormser
    IPN, Orsay
 
  Funding: Work supported by DOE contract DE-AC02-76SF00515.

For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has reached 9.2 x 1033/cm2/s. PEP-II has delivered an integrated luminosity of 710/pb in one day. It operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 2.55 A in 1588 bunches. The total integrated luminosity since turn on in 1999 has reached 256/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s. Upgrade details and plans are discussed.