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Study on the BC1 Energy Set Point

Study on the BC1 Energy Set Point . J. Wu working with T.O. Raubenheimer LCLS-II Accelerator Physics meeting May 09, 2012. outline. Continue from the talk I gave on April 11, 2012

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Study on the BC1 Energy Set Point

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  1. Study on the BC1 Energy Set Point J. Wu working with T.O. Raubenheimer LCLS-II Accelerator Physics meetingMay 09, 2012 LCLS-II Accel. Phys. , J. Wu, SLAC

  2. outline • Continue from the talk I gave on April 11, 2012 • Updated to LCLS-II design distance and also modeled the undulator resistive-wall wakefield effect and by-pass line wakefield effect • Pros of setting BC1 @ 300 ~ 350 MeV for LCLS-II • More accelerator tubes before BC1: lower the amplitude, avoid any breakdown related problem; more stable simply due to 1/sqrt(2) statistics; … • One concern about the chicane strength (looked into) • More knowledge about the stability and tolerance (on-going) LCLS-II Accel. Phys. , J. Wu, SLAC

  3. Layout: according to LCLS-II mad deck • BC1 @ 250 MeV • Set points • BC1: R56 = 46 mm, Energy 250 MeV, peak current 176 Amp • L1S: – 20 degree • L1X: – 160 degree; 19 MeV • L2: – 31.4 degree • BC2: R56 = 29 mm, Energy 4.5 GeV, peak current 3 kA wire scanner 4 wire-scanners L0 L1X L1S gun DL1 135 MeV BC1 250 MeV BC2 4.5 GeV TCAV3 L3-linac By-pass 13.5 GeV L2-linac UND LCLS-II Accel. Phys. , J. Wu, SLAC

  4. Profiles BC1END UNDBEG CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008] LCLS-II Accel. Phys. , J. Wu, SLAC

  5. Bc2 CSR and L3 RF + wake BC2END L3END CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008] LCLS-II Accel. Phys. , J. Wu, SLAC

  6. By-pass line and Undulatorwake Implement wakefield UNDBEG UNDEND LCLS-II Accel. Phys. , J. Wu, SLAC

  7. Layout: higher energy • BC1 @ 335 MeV • Set points • BC1: R56 = 44.4 mm, Energy 335 MeV, peak current 207 Amp • L1S: – 16 degree • L1X: – 160 degree; 30 MeV • L2: – 32 degree • BC2: R56 = 27 mm, Energy 4.5 GeV, peak current 3 kA wire scanner 4 wire-scanners L0 L1X L1S gun DL1 135 MeV BC1 355 MeV BC2 4.5 GeV TCAV3 L3-linac By-pass 13.5 GeV L2-linac UND LCLS-II Accel. Phys. , J. Wu, SLAC

  8. Profiles BC1END UNDBEG CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008] LCLS-II Accel. Phys. , J. Wu, SLAC

  9. Bc2 CSR and L3 RF + wake BC2END L3END CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008] LCLS-II Accel. Phys. , J. Wu, SLAC

  10. By-pass line and Undulatorwake Implement wakefield UNDBEG UNDEND LCLS-II Accel. Phys. , J. Wu, SLAC

  11. Rematch the optics LCLS-II Accel. Phys. , J. Wu, SLAC • Twiss-function through BC1 @ 335 MeV

  12. EmittANCE GROWTH T.O. Raubenheimer • Due to ISR • E = 0.335 GeV; q = 6.43o; LB = 0.2035;DL = 2.44572; ; • Dgex = 5.5E-13  negligible • CSR and Space Charge: reported last time with Impact-T simulation  small LCLS-II Accel. Phys. , J. Wu, SLAC

  13. BC1 dipole field integral • BC1 energy set point to be as high as 350 MeV • Assuming the set point range is from 200 MeV to 350 MeV • Assuming the BC1 chicane can provide R56 from 15 mm to 65 mm for the above mentioned energy range (200 – 350 MeV) • With the same geometry as in CDR • Then the maximum field integral of each dipole is 1.31 kG m (350 MeV and R56 of 65 mm) • Details are plotted in the next page LCLS-II Accel. Phys. , J. Wu, SLAC

  14. BC1 dipole field integral 1.31 kG m 1.10 kG m LCLS-II Accel. Phys. , J. Wu, SLAC • BC1 energy set point: 200 -- 350 MeV • BC1 chicane R56: 15 (red curve) – 46 (green curve) – 65 (blue curve) mm

  15. Setpoint Comparison between setting BC1 @ 250 and 335 MeV Next, look at the jitter and tolerance LCLS-II Accel. Phys. , J. Wu, SLAC

  16. L1S phase jitter: UNDbegcentroid energy 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  17. L1S phase jitter: UNDbeg residual energy chirp 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  18. L1S phase jitter: UNDbeg peak current 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  19. L1X phase jitter: UNDbegcentroid energy 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  20. L1x phase jitter: UNDbeg residual energy chirp 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  21. L1x phase jitter: UNDbeg peak current 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  22. L1X amplitude jitter: UNDbegcentroid energy 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  23. L1x amplitude jitter: UNDbeg residual energy chirp 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  24. L1x amplitude jitter: UNDbeg peak current 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  25. Injector timing jitter: UNDbegcentroid energy 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  26. Injector timing jitter: UNDbeg residual energy chirp 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  27. Injector timing jitter: UNDbeg peak current 250 MeV 335 MeV LCLS-II Accel. Phys. , J. Wu, SLAC

  28. Jitter sensitivities and tolerance 250 MeV case from CDR LCLS-II Accel. Phys. , J. Wu, SLAC

  29. Jitter sensitivities and tolerance 335 MeV case on-going: L1S phase, L1X phase, timing LCLS-II Accel. Phys. , J. Wu, SLAC

  30. L1X phase jitter BC1@ 335 MeV: UNDBEG L1X: -160.5o L1X: -160o L1X: -159.5o LCLS-II Accel. Phys. , J. Wu, SLAC

  31. discussion • Linear compression study with optimization for BC1 @ 300 -- 350 MeV up to undulator end • Longitudinal profile up to undulator end • Tolerance study: centroid energy, residual energy chirp, peak current on timing and LINAC phase jitter up to undulator entrance • Looked into BC1 dipole magnet design for BC1 @ 335 MeV • The maximum field integral of each dipole is 1.31 kG m (350 MeV and R56 of 65 mm) • Full machine lattice in Impact code is on going • Strong focusing on sec. 11-2 • More tolerance study is needed. LCLS-II Accel. Phys. , J. Wu, SLAC

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