CSR Microbunching in the Zeuthen-Workshop Benchmark Chicane Paul Emma Stanford Linear Accelerator Center July 2, 2002

Chicane CSR Test-Case Use line-charge CSR    transient model described in LCLS-TN-01-12… (Stupakov/Emma, Dec. 2001) [same now used in Elegant] …based on TESLA-FEL-96-14 (Saldin et al., Nov. 1996) (T566 included, no ISR* added) * incoherent synchrotron radiation

Modulate current and energy profiles li = 75 mm sE/E0 = 210-6 gex0 = 0 mm ‘cold’ beam li = 20 mm sE/E0 = 210-6 gex0 = 0 mm ‘cold’ beam

Vary ‘slice’ emittance and energy spread li = 20 mm gex0=0 mm sd =210-6 gex0=1 mm sd =210-5 gex0=1 mm sd =210-6

Berlin-Benchmark 5-GeV Gain Curve “theory”: S. Heifets et al., SLAC-PUB-9165, March 2002 ‘cold’ beam Microbunching Gain gex=1 mm sd=210-5 (gex=0) gex=1 mm, sd=310-5 wavelength at chicane entrance

LCLS BC2 CSR Microbunching Gain vs. l gex=1 mm ‘cold’ beam Initial modulation wavelength prior to compressor gex=1 mm, sd=310-5 “theory”: S. Heifets et al., SLAC-PUB-9165, March 2002

Z. Huang: LCLS DL1/BC1/BC2/DL2 SC wiggler OFF SC wiggler ON