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    FCC-ee special machine protection #2

    → Europe/Zurich
    CERN

    CERN
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    Participants: 

    A. Abramov, Y. Dutheil, M. Hofer, C. Wiesner, S. Yue

     

    Collider on-axis injection failure modes (S. Yue)

    • Due to the limitation of longitudinal phase space, it is needed to reduce the energy offset to 1% for the lower energy modes (see latest table from KO here)
    • Yann asked if it would be possible to reduce damping time by increasing the SR with wigglers
      • Michael points out that every mode is limited to 50MW RF power, and increasing SR requires to reduce the intensity
    • Magnetic septum is pulsed, but slow enough (few to 100ms) 
      • we consider the failure can be detected and injection prevented in case of failure
      • Christoph points out the maximum deflection error should still be calculated and its effect on the beamlet accounted for 
    • S.Yue will merge the injection lattice to FCCee repository, but it’s vertical beta function is too large, around 7000 m. 

    Collimation and collider injection failure (A. Abramov) 

    • The relation between injection kick and fraction impacting on primary collimators at the first turn depend on phase advance
    • Showing numbers for the injected beamlet
    • Other cases include the failure of the ring orbit fast bumpers
      • presently a PI bump of ~10sigma is considered, which would cause a 10sigma offset at the collimators -> beyond the damage limit
      • The ring bumpers could be split in 2 so that one failure would only cause up to 5 sigma betatron oscilation of the circulating beam
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