Author: Chu, J.Y.
Paper Title Page
WEYA02 Studies at CesrTA of Electron-Cloud-Induced Beam Dynamics for Future Damping Rings 2081
 
  • G. Dugan, M.G. Billing, K.R. Butler, J.A. Crittenden, M.J. Forster, D.L. Kreinick, R.E. Meller, M.A. Palmer, G. Ramirez, M.C. Rendina, N.T. Rider, K.G. Sonnad, H.A. Williams
    CLASSE, Ithaca, New York, USA
  • R.F. Campbell, R. Holtzapple, M. Randazzo
    CalPoly, San Luis Obispo, California, USA
  • J.Y. Chu
    CMU, Pittsburgh, Pennsylvania, USA
  • J.W. Flanagan, K. Ohmi
    KEK, Ibaraki, Japan
  • M.A. Furman, M. Venturini
    LBNL, Berkeley, California, USA
  • M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  Funding: US National Science Foundation PHY-0734867, PHY-1002467, and PHY-1068662; US Dept. of Energy DE-FC02-08ER41538; and the Japan/US Cooperation Program.
Electron clouds can adversely affect the performance of accelerators, and are of particular concern for the design of future low emittance damping rings. Studies of the impact of electron clouds on the dynamics of bunch trains in CESR have been a major focus of the CESR Test Accelerator program. In this paper, we report measurements of coherent tune shifts, emittance growth, and coherent instabilities carried out using a variety of bunch currents, train configurations, beam energies, and transverse emittances, similar to the design values for the ILC damping rings. We also compare the measurements with simulations which model the effects of electron clouds on beam dynamics, to extract simulation model parameters and to quantify the validity of the simulation codes.
 
slides icon Slides WEYA02 [2.033 MB]  
 
WEPPR087 Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA Due to Variations in Chromaticity, Bunch Current and Train Length 3135
 
  • M.G. Billing, G. Dugan, M.J. Forster, D.L. Kreinick, R.E. Meller, M.A. Palmer, G. Ramirez, M.C. Rendina, N.T. Rider, J.P. Sikora, K.G. Sonnad, H.A. Williams
    CLASSE, Ithaca, New York, USA
  • J.Y. Chu
    CMU, Pittsburgh, Pennsylvania, USA
  • J.W. Flanagan
    KEK, Ibaraki, Japan
  • R. Holtzapple, M. Randazzo
    CalPoly, San Luis Obispo, California, USA
 
  Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467.
Electron cloud-induced beam dynamics is being studied at CESRTA under various conditions. These measurements detect the the coherent self-excited spectrum for each bunch within a train and bunch-by-bunch beam size. In the position spectrum coherent betatron dipole and head-tail motion is detectable for each individual bunch within the train with a sensitivity for the motion of 1.1 (2) microns-rms in the vertical (horizontal) direction for a 1 mA bunch current. These techniques are utilized to study the electron cloud-related interactions, which cause the growth of coherent motion and beam size along the train. We report on the observations and results from studies of the instability growth vs. changes in chromaticity, the current per bunch and the length of the train.