LCLS-II Particle Tracking: Gun to Undulator P. Emma Jan. 12, 2011

SLAC linac tunnelBTH & U-Hall Linac-0’ L  6 m Linac-1’ L  9 m  rf   20° Linac-2’ L  326 m  rf   32° Linac-3’ L  582 m  rf  0° BC1’ L  6.5 m R 56   46 mm BC2’ L  23 m R 56   29 mm DL1’ L  12 m R 56  6.3 mm undulators L  120 m 6 MeV  z  0.62 mm    0.05 % 135 MeV  z  0.62 mm    0.07 % 250 MeV  z  0.13 mm    1.1 % 4.2 GeV  z  7  m    0.43 % 13.5 GeV  z  7  m    0.01 % Linac-X’ L  0.6 m  rf   160  V 0   19 MV 11-3b14-4d 11-3b14-4d X X SXR 1-km bypass line 11-1 b,c,d 11-1 b,c,d...existing linac...existing linac 14-7b20-4d 14-7b20-4d LCLS-I keV 2-13 keV L0-a,b rf gun H XR keV LCLS-II Accelerator for 13.5 GeV, 120 Hz, 250 pC Jan. 12, 2011, 11:16 AM - PE

LCLS-II Layout (After Linac) LCLS-I LTUH LTUS LTU2 LTU1 LCLS-II  LINAC END muon plug wall

LCLS-II Layout (After Linac)

LCLS-II Optics in Elegant (250 pC, 13.5 GeV) BC1BC2 Bypass Line 2.4° bends HXR und. Thanks to Mark Woodley and Yuri Nosochkov

2E5 macro particles (250 pC) tracked through Parmela to 135 MeV. 1 st and 2 nd -order optics (dipoles, quads, soln’s) and sinusoidal RF. Longitudinal wakes of SLAC S-band RF structures. Resistive longitudinal wakes of 1240 meters of 2-inch diameter stainless steel beam pipe (sector 20-5 to exit of muon-plug wall). Resistive longitudinal wakes of 330 meters of inch diameter copper plated (?) LTU2 beam pipe. CSR in all bends (1D model in Elegant) - includes transients but ignores transverse beam size (typically not a big impact). ISR in all bends – small impact on slice E-spread and slice emittance. Laser heater adds 17 keV rms E-spread at 135 MeV. All components are error-free: perfect alignment & CSR-steering is removed. What’s Included in the Elegant Tracking?

LCLS-II Particle Distributions (in Longitudinal Phase Space) Output from Parmela at 135 MeV Output from Elegant at 14 GeV 35 A ~3 kA …with CSR 0.01% rms

CSR-Induced Emittance Growth Along BC2 (250 pC, 4.2 GeV) This calculation removes the linear correlations in x and x’ with energy in order to reveal only the irrecoverable CSR effect. The projected emittance after the BC2 without removing these linear correlation is 1.32  m  m 1.09  m 0.53  m  x  y Includes double-horn distribution of LCLS

CSR-Induced Slice Emittance Before and After BC2 (250 pC, 4.2 GeV) Slice Emittance Before BC2 Slice Emittance After BC2 Includes double-horn distribution of LCLS

CSR-Induced Emittance Growth Along LCLS-II Accelerator (13.5 GeV) BC1BC2 Bypass Dog-Leg LTU2 2.4-deg Bends might be fixed? Vertical Bends Includes double-horn distribution of LCLS

Emittance across LTU2 bend system (horizontal in black and vertical in blue), including the 2.4-deg bends and the LTUS SXR branch line optics (8 dipoles total). CSR-Induced Emittance Growth Along LTU2 & LTUS (13.5 GeV) 2.4° bendsLTUS DL-bends pulsed bend Includes double-horn distribution of LCLS

Resistive-Wall Longitudinal Wakefield of 1240-m of 2-inch SS Pipe (Existing Bypass Line) Bane, Sands

Resistive-Wall Longitudinal Wakefield of 1240-m of 2-inch SS Pipe (Existing Bypass Line) Before bypass linev After bypass line

Final Slice Emittances (x & y) - with CSR - Before Undulator (250 pC, 13.5 GeV)