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

2. OUTLINE Continue from the talk I gave on April 11, 2012 undulator by-pass line 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: R 56 = 46 mm, Energy 250 MeV, peak current 176 Amp L1S: – 20 degree L1X: – 160 degree; 19 MeV L2: – 31.4 degree BC2: R 56 = 29 mm, Energy 4.5 GeV, peak current 3 kA BC2 4.5 GeV By-pass 13.5 GeV TCAV3BC1 250 MeV L1S wirescanner L1X 4 wire-scanners L2-linac L3-linac DL1 135 MeV L0 gun LCLS-II Accel. Phys., J. Wu, SLAC UND

4. PROFILES BC1ENDUNDBEG 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 BC2ENDL3END 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 UNDULATOR WAKE Implement wakefield UNDENDUNDBEG LCLS-II Accel. Phys., J. Wu, SLAC

7. LAYOUT: HIGHER ENERGY BC1 @ 335 MeV Set points BC1: R 56 = 44.4 mm, Energy 335 MeV, peak current 207 Amp L1S: – 16 degree L1X: – 160 degree; 30 MeV L2: – 32 degree BC2: R 56 = 27 mm, Energy 4.5 GeV, peak current 3 kA LCLS-II Accel. Phys., J. Wu, SLAC BC2 4.5 GeV By-pass 13.5 GeV TCAV3BC1 355 MeV L1S wirescanner L1X 4 wire-scanners L2-linac L3-linac DL1 135 MeV L0 gun UND

8. PROFILES BC1ENDUNDBEG 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 BC2ENDL3END 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 UNDULATOR WAKE Implement wakefield UNDENDUNDBEG LCLS-II Accel. Phys., J. Wu, SLAC

11. REMATCH THE OPTICS Twiss-function through BC1 @ 335 MeV

12. EMITTANCE GROWTH Due to ISR E = 0.335 GeV;  = 6.43 o ; L B = 0.2035;  L = 2.44572; ; negligible  x = 5.5E-13  negligible last time CSR and Space Charge: reported last time with Impact- T simulation  small T.O. Raubenheimer 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 R 56 from 15 mm to 65 mm for the above mentioned energy range (200 – 350 MeV) With the same geometry as in CDR 1.31 kG m Then the maximum field integral of each dipole is 1.31 kG m (350 MeV and R 56 of 65 mm) Details are plotted in the next page LCLS-II Accel. Phys., J. Wu, SLAC

14. BC1 DIPOLE FIELD INTEGRAL BC1 energy set point: 200 -- 350 MeV redgreenblue BC1 chicane R 56 : 15 (red curve) – 46 (green curve) – 65 (blue curve) mm 1.31 kG m 1.10 kG m

15. SETPOINT Comparison between setting BC1 @ 250 and 335 MeV Next, look at the jitter and tolerance BC1 Setpoint (MeV) LocationR 56,1 (mm) L 1S Phase (S-deg) L 1X Phase (X-deg) L 1X Amplitud e (MV) L 2 Phase (S-deg) BC2 Setpoint (GeV) R 56,2 (mm) 25011-246-20-16019-31.44.529 33511-344.4-16-16030-324.527 LCLS-II Accel. Phys., J. Wu, SLAC

16. L1S PHASE JITTER: UNDBEG CENTROID ENERGY 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

17. L1S PHASE JITTER: UNDBEG RESIDUAL ENERGY CHIRP 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

18. L1S PHASE JITTER: UNDBEG PEAK CURRENT 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

19. L1X PHASE JITTER: UNDBEG CENTROID ENERGY 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

20. L1X PHASE JITTER: UNDBEG RESIDUAL ENERGY CHIRP 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

21. L1X PHASE JITTER: UNDBEG PEAK CURRENT 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

22. L1X AMPLITUDE JITTER: UNDBEG CENTROID ENERGY 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

23. L1X AMPLITUDE JITTER: UNDBEG RESIDUAL ENERGY CHIRP 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

24. L1X AMPLITUDE JITTER: UNDBEG PEAK CURRENT 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

25. INJECTOR TIMING JITTER: UNDBEG CENTROID ENERGY 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

26. INJECTOR TIMING JITTER: UNDBEG RESIDUAL ENERGY CHIRP 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

27. INJECTOR TIMING JITTER: UNDBEG PEAK CURRENT 335 MeV250 MeV LCLS-II Accel. Phys., J. Wu, SLAC

28. JITTER SENSITIVITIES AND TOLERANCE 250 MeV case from CDR

29. JITTER SENSITIVITIES AND TOLERANCE 335 MeV case on-going: L1S phase, L1X phase, timing Jitter sourceE BC1 (MeV)  E/E 0 (%) h 0 (1/m)  h (1/m)  I/I 0 (%) L 1S phase (rms 0.06 degree) 2500.0110.081.883.53 3350.01-7.181.591.30 L 1X phase (rms 0.50 degree) 2500.0110.145.442.63 3350.02-7.1811.535.91 L 1X amplitude (rms 0.05 MeV) 2500.0110.141.792.75 3350.01-7.180.141.22 Injector timing (rms 200 fs) 2500.0210.140.982.92 3350.01-7.193.540.28 LCLS-II Accel. Phys., J. Wu, SLAC

30. L1X PHASE JITTER BC1@ 335 MeV: UNDBEG L 1X : -160.5 o L 1X : -160 o L 1X : -159.5 o

31. Linear compression study with optimization for BC1 @ 300 -- 350 MeV up to undulator end Linear compression study with optimization for BC1 @ 300 -- 350 MeV up to undulator end Longitudinal profile 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 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 Looked into BC1 dipole magnet design for BC1 @ 335 MeV 1.31 kG m o The maximum field integral of each dipole is 1.31 kG m (350 MeV and R 56 of 65 mm)  Full machine lattice in Impact code is on going  Strong focusing on sec. 11-2  More tolerance study is needed. DISCUSSION LCLS-II Accel. Phys., J. Wu, SLAC