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Quadrupole Magnet Vibrations and RF Stability

Quadrupole Magnet Vibrations and RF Stability. Paul Emma LCLS-II Physics Meeting June 18, 2014. No CSR here. RF Stability Requirements and Consequences (1).

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Quadrupole Magnet Vibrations and RF Stability

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  1. Quadrupole Magnet Vibrations and RF Stability Paul Emma LCLS-II Physics Meeting June 18, 2014

  2. No CSR here

  3. RF Stability Requirements and Consequences (1) Longitudinal sensitivities where each entry in the DE/E0-column causes a 0.01% energy error, in the DI/I0-column causes a 4% peak current error, and in the Dtf -column causes a 20-fs bunch arrival time error. L0 RF phase sensitivity (LiTrack) ±4% ±0.048 degL L0 RF phase error of ±0.048 degL causes ±4% peak current change (and 44 more such linear fits fill out the table). Scale down such that quadrature sum of all errors just reaches beam stability limit for each column Beam-based feedback covers jitter slower than ~10 Hz LCLS-II FAC Review, July 1-3, 2014

  4. RF Stability Requirements and Consequences (2) Jitter Simulations in LiTrack Target final energy, peak current, and timing stability Hold to ~0.01-deg & ~0.01% tols** Assume uncorrelated RF jitter (cavity to cavity) Include bunch charge, laser, & chicane power supplies ENERGY ARRIVAL TIME PEAK CURRENT * The gun timing error is compressed by 3.85, from gun to 100 MeV, due to velocity compression. LCLS-II FAC Review, July 1-3, 2014 ** If correlated errors, would then achieve 0.01%, 4%, and 20 fs stability

  5. Quadrupole Magnet Vibration Tolerances (1) Introduce the normalized trajectory oscillation amplitude, Ax (or Ay), , Linac to split with Dx'ithe kick angle of the ith quadrupole due to its displacement. For N uncorrelated kicks along the accelerator… Budget is formed by grouping tolerances into a few discrete levels and setting Ax = 10%... HXR (SXR not shown) (includes undulators) where N1+N2+N3=N. Vibration sensitivity of each magnet: Dx's 285 quadrupole magnets LCLS-II FAC Review, July 1-3, 2014

  6. Quadrupole Magnet Vibration Tolerances (2) Divide tolerances into 3 bins (500, 120, & 50 nm rms)… rms vib. sensitivities: Linac to LTU-Split (x&y) Number of quads/bin (x&y) x & ytol.’s listed for each quad. rms vib. sensitivities: HXR (SXR not shown) 285 quadrupole magnets  LCLS-II FAC Review, July 1-3, 2014

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