Author: Dowell, D.
Paper Title Page
MOP021 LCLS-II Injector Beamline Design and RF Coupler Correction 77
  • F. Zhou, D. Dowell, R.K. Li, T.O. Raubenheimer, J.F. Schmerge
    SLAC, Menlo Park, California, USA
  • C.E. Mitchell, C. F. Papadopoulos, F. Sannibale
    LBNL, Berkeley, California, USA
  • A. Vivoli
    Fermilab, Batavia, Illinois, USA
  Funding: U.S. DOE contract #DE-AC02-76SF00515.
LCLS-II CW injector beamline consists of a 186 MHz normal conducting (NC) RF gun for beam generation and acceleration to 750 keV, two solenoids for the beam focusing, two BPMs, 1.3 GHz NC RF buncher for bunch compression down to 3-4 ps rms, 1.3 GHz superconducting standard 8-cavity cryomodule to boost beam energy to about 98 MeV. The beamline is being optimized to accommodate all essential components and maximize beam quality. The beamline layouts and beam dynamics are presented and compared. The 3D RF field perturbation due to cavity couplers where the beam energy is very low (<1 MeV) causes significant emittance growth especially for a large-size beam. A theory of rotated fields predicted and simulations verified using a weak skew quadrupole located even a significant distance from the perturbation can completely eliminate the emittance growth. A layout for future upgrade is developed. The results are presented and analysed.
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