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WP3_TDR #1: Kickoff meeting

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Andy Butterworth (CERN)
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Present: A. Butterworth, I. Karpov, O. Brunner, W. Hofle, K. Canderan, L. Valle, F. Peauger, J. Heron

Discussion

Cryogenic safety and access to RF zones

  • Sectorization of the RF zones is not a hard separation, rather a way of calculating air flow.

  • Proposal that the smoke extraction system be used for helium

    • A problem is the sensor to extraction delay which is about 30 seconds.

  • Will need to empty all cryomodules in the walking path to module which needs to be accessed.

  • Trying to design around the worst case scenario:

    • New experiments and studies needed, as the worst case scenario is realistically an overestimate. Accident/consequences to be refined.

  • Can avoid cavity quench loss of He in FCC as they do at ESS. Unlike LHC, where the release valves open on overpressure. To be checked in LHC.

  • Circumventing access problems with remote manipulation:

    • Robots for inspection but also for interventions.
    • Specific RF robot, or the same one as in the arcs
    • Different robots for collider and booster, as the CMs are either on the ceiling or the floor.
    • We should try to sketch interventions which are possible for robots. Space constraints are different in different places.
    • Fault categorization: classify into remote repairable, repairable from klystron gallery, common mode faults, child faults, electrical glitches etc. Can then decide if a robot is worth it, looking at the likelihood of faults.
Transverse damper
  • TFB is combined with depolarizer. Makes it more complicated for degraded mode.
  • IPAC paper in 2024 was a snapshot at the time, number of kickers  (24) more or less defined, 25ns spacing and bunch pattern defined.
  • Potential physics bunch spacing of 5ns for e-cloud, would need change of bandwidth.
  • Optics choice.
  • There is enough redundancy with 24 kickers for TFB operation but maybe not for depolarization.
  • System distributed over 4 locations per ring, gives redundancy against electrical loss etc.
  • Loss of synchronization with frev could be a common mode failure. If distributed over White Rabbit what is the redundancy?
  • Instability damping is only needed at the Z working point. For W it is still needed for HOM instability. We can remove it for reliability considerations at the H and ttbar working points.
  • TFB in the booster: what is needed for polarized bunches? More complex than in the collider.
  • Possibly required to do active depolarization of physics bunches in the collider.
  • E-POL group meeting: https://indico.cern.ch/event/1610901/
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