Author: Maury Cuna, G.H.I.
Paper Title Page
TUPFI002 Electron Cloud and Scrubbing Studies for the LHC 1331
  • G. Iadarola
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  • G. Arduini, V. Baglin, H. Bartosik, C.O. Domínguez, J.F. Esteban Müller, G. Iadarola, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, F. Zimmermann
    CERN, Geneva, Switzerland
  • C.O. Domínguez
    EPFL, Lausanne, Switzerland
  • G.H.I. Maury Cuna
    CINVESTAV, Mexico City, Mexico
  Electron cloud build-up resulting from beam-induced multipacting is one of the major limitations for the operation of the LHC with beams with close bunch spacing. Electron clouds induce unwanted pressure rise, heat loads on the beam screens of the superconducting magnets and beam instabilities. Operation with bunch spacing of 50 ns in 2011 and 2012 has required decreasing the Secondary Electron Yield of the beam screens below the multipacting threshold for beams with this bunch spacing. This was achieved by continuous electron bombardment induced by operating the machine with high intensity beams with 50 and 25 ns spacing during dedicated periods at injection energy (450 GeV) and at top energy (3.5 and 4 TeV). The evolution of the Secondary Electron Yield during these periods, at different sections of the machine, can be estimated by pressure, heat load and by bunch-by-bunch RF stable phase measurements. The experimental information on the scrubbing process will be discussed and a possible “scrubbing strategy” to allow the operation with 50ns and 25ns beams after the Long Shutdown in 2013-2014 will be presented.  
TUPFI005 Synchrotron-Radiation Photon Distribution for Highest Energy Circular Colliders 1340
  • G.H.I. Maury Cuna
    CINVESTAV, Mérida, Mexico
  • G. Dugan, D. Sagan
    CLASSE, Ithaca, New York, USA
  • F. Zimmermann
    CERN, Geneva, Switzerland
  Funding: Acknowledgements to CINVESTAV, CERN and EPLANET project.
At high energies, beam-induced synchrotron radiation is an important source of heating, beam-related vacuum pressure increase, and primary photoelectrons, which can give rise to an electron cloud. The photon distribution along the beam pipe wall is a key input to codes such as ECLOUD and PyECLOUD, which model the electron cloud build-up. For future high-energy colliders, like TLEP or SHE-LHC, photon stops and antechambers are considered in order to facilitate cooling and vacuum pressure control. We use the Synrad3D code developed at Cornell to simulate the photon distribution for the LHC.