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Possible mitigations

Several mitigations are already in place, others may need to be improved and/or studied and developed.

Dipole perturbation

  • ADT is expected to suppress dipole excitation (f>3 kHz, within the limits of the its own noise and of the beam tune spread)
    • The low frequency cut off could be reduced, but this requires dedicated study and substantial hardware modification.
  • CO feedback will address only slow drift (f<0.2 Hz)
  • In the region 0.2 Hz < f < 3 kHz, where main triplets/BS/'10Hz’ modes lies,
    • optimized mechanical design of the new triplets
    • improved cleaning efficiency of halo (HEL)
  • At the moment, intra-bunch motion (CC amplitude noise and CC RF curvature, f>40 MHz, large efforts to reduce LLRF noise) has no safety-net. Encouraging simulation results of CC beam-based feedback (but not in the baseline)

Quadrupole perturbation (not critical effect expected)

  • no active way to address the tune modulation (tune feedback is too low in BW).
  • Increase the f_{clock} of the triplets switching-mode PC if possible.