Author: Liu, X.
Paper Title Page
MOPS083 Update on Electron Cloud Mitigation Studies at Cesr-TA* 796
 
  • J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, J. Makita, R.E. Meller, M.A. Palmer, S. Santos, R.M. Schwartz, J.P. Sikora, C.R. Strohman
    CLASSE, Ithaca, New York, USA
  • S. Calatroni, G. Rumolo
    CERN, Geneva, Switzerland
  • K. Kanazawa, Y. Suetsugu
    KEK, Ibaraki, Japan
  • M.T.F. Pivi, L. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the US National Science Foundation (PHY-0734867) and Department of Energy (DE-FC02-08ER41538)
Over the course of the past three years, the Cornell Electron Storage Ring (CESR) has been reconfigured to serve as a test facility for next generation particle accelerators. A significant part of this program has been the installation of several diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. In particular, more than 30 Retarding Field Analyzers (RFAs) have been installed in CESR. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. This paper will provide an overview of RFA results obtained at CesrTA over the past year, including measurements taken as function of bunch spacing and wiggler magnetic field. Understanding these results provides a great deal of insight into the behavior of the electron cloud.
 
 
WEPC135 Recent Developments in Modeling Time-resolved Shielded-pickup Measurements of Electron Cloud Buildup at CESRTA 2313
 
  • J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, J.P. Sikora
    CLASSE, Ithaca, New York, USA
  • R.P. Badman
    Syracuse University, Syracuse, USA
  • S. Calatroni, G. Rumolo
    CERN, Geneva, Switzerland
  • S. Kato
    KEK, Ibaraki, Japan
 
  Funding: Work supported by the U.S. National Science Foundation PHY-0734867, PHY-1002467 and the U.S. Department of Energy DE-FC02-08ER41538
The Cornell Electron Storage Ring Test Accelerator program includes investigations into the mitigation of electron cloud buildup using a variety of techniques in custom vacuum chambers. The CESR ring accommodates two such chambers equipped with BPM-style pickup detectors shielded against the direct beam-induced signal. The signals provide time-resolved information on cloud development. Results for diamond-like carbon, amorphous carbon, and TiN coatings have been compared to those for an uncoated aluminum chamber. Here we report on extensions to the ECLOUD modeling code which refine its description of a variety of new types of in situ vacuum chamber comparisons. Our results highlight the sensitivity afforded by these measurements to the modeled photoelectron production and secondary yield parameters. We draw conclusions comparing the photoelectron and secondary yield properties of the various vacuum chamber coatings, including conditioning effects as a function of synchrotron radiation dose. We find substantial conditioning effects in both the quantum efficiency for producing photoelectrons and in the secondary yield.