Author: Garcia Morales, H.
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WEPMW028 First Attempts at using Active Halo Control at the LHC 2486
  • J.F. Wagner
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
  • R. Bruce, H. Garcia Morales, W. Höfle, G. Kotzian, R. Kwee-Hinzmann, A. Langner, A. Mereghetti, E. Quaranta, S. Redaelli, A. Rossi, B. Salvachua, R. Tomás, G. Valentino, D. Valuch, J.F. Wagner
    CERN, Geneva, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
  Funding: Research supported by the High Luminosity LHC project.
The beam halo population is a non-negligible factor for the performance of the LHC collimation system and the machine protection. In particular this could become crucial for aiming at stored beam energies of 700 MJ in the High Luminosity (HL-LHC) project, in order to avoid beam dumps caused by orbit jitter and to ensure safety during a crab cavity failure. Therefore several techniques to safely deplete the halo, i.e. active halo control, are under development. In a first attempt a novel way for safe halo depletion was tested with particle narrow-band excitation employing the LHC Transverse Damper (ADT). At an energy of 450 GeV a bunch selective beam tail scraping without affecting the core distribution was attempted. This paper presents the first measurement results, as well as a simple simulation to model the underlying dynamics.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW028  
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WEPMW030 Cleaning Performance of the Collimation System of the High Luminosity Large Hadron Collider 2494
  • D. Mirarchi, A. Bertarelli, R. Bruce, F. Cerutti, P.D. Hermes, A. Lechner, A. Mereghetti, E. Quaranta, S. Redaelli
    CERN, Geneva, Switzerland
  • R.B. Appleby
    UMAN, Manchester, United Kingdom
  • H. Garcia Morales, R. Kwee-Hinzmann
    Royal Holloway, University of London, Surrey, United Kingdom
  Different upgrades of the LHC will be carried out in the framework of the High Luminosity project (HL-LHC), where the total stored energy in the machine will increase up to about 700 MJ. This unprecedented stored energy poses serious challenges for the collimation system, which was designed to handle safely up to about 360 MJ. In this paper the baseline collimation layout for HL-LHC is described, with main focus on upgrades related to the cleaning of halo and physics debris, and its expected performance is discussed. The main upgrade items include the presence of new collimators in the dispersion suppressor of the betatron cleaning insertion installed between two 11 T dipoles, and two additional collimators for an improved local protection of triplet magnets. Thus, optimized settings for the entire and upgraded collimation chain were conceived and are shown here together with the resulting cleaning performance. Moreover, the cleaning performance taking into account crab cavities it is also discussed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW030  
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