Speaker
Description
The accelerator at the FACET-II National User Facility at SLAC National Accelerator Laboratory can test several elements of the design of the FCC-ee injector. To support the design of the injector we propose three experiments: measurement of emittance growth as a function of compression at high charge, characterization of jitter amplification of high-charge beams in s-band linacs at 25 ns separation, and photoinjector performance when varying charge from 0 to 5 nC. Historically, high-charge beams have been challenging to operate [1,2] and experience at light sources has motivated a move to lower charge beams [3]; CSR effects at high charge are not well studied. For the first experiment, we propose a study of the operation of compression systems at high charge that looks at 2D coherent synchrotron radiation effects on beam parameters to benchmark models used to design the FCC-ee injector. The second experiment examines how jitter is amplified by optics and wakefields along linacs operating at high charge with 25 ns bunch separation. The study includes potential optics testing of a method to damp jitter growth along a linac. To meet the charge variation requirements for top-up injection, the injector performance when varying the charge from 0 charge to 5 nC should be characterized. We propose to study methods to generate charge and laser size variation at 100 Hz that will produce the beam parameters required for the FCC-ee injector.
[1] Phinney, Nan. "SLC final performance and lessons." arXiv preprint physics/0010008 (2000).
[2] Funakoshi, Y., et al. Journal of Instrumentation 19.02 (2024): T02003.
[3] P. Emma, SLAC-TN-05-042
