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LCLS-IISC Parameters

LCLS-IISC Parameters. Tor Raubenheimer. Operating modes. Concurrent operation of 1-5 keV and 5-18 keV is not possible. 0.2-1.2 keV (100kHz). 4 GeV SC Linac. Cu Linac. 1.0 - 18 keV (120 Hz) 1.0 - 5 keV (100 kHz). Two sources: high rate SCRF linac and 120 Hz NCu LCLS-I linac

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LCLS-IISC Parameters

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  1. LCLS-IISC Parameters • Tor Raubenheimer

  2. Operating modes Concurrent operation of 1-5 keV and 5-18 keV is not possible 0.2-1.2 keV (100kHz) 4 GeV SC Linac Cu Linac 1.0 - 18 keV (120 Hz) 1.0 - 5 keV (100 kHz) • Two sources: high rate SCRF linac and 120 Hz NCu LCLS-I linac • North and south undulators always operate simultaneously in any mode LCLS-II Overview

  3. Preliminary Operating Parameters LCLS-II Overview

  4. High Level Schedule Insert Presentation Title in Slide Master

  5. More Immediate Schedule Insert Presentation Title in Slide Master Mid-October Workshop to review design, cost and schedule with collaborators Mid-December Director’s Review for CD1 Review Mid-January CD1 Lehman Review Also may need to have a FAC review prior to CD1 review  Mid-November ??

  6. Assumed Beam Parameters Insert Presentation Title in Slide Master The assumed emittance of 0.43 at 100 pC is roughly 25% larger than the LCLS-II baseline. It is more conservative than the NLS or the scaled NGLS values (the latter are consistent with the LCLS-II baseline) however a gun has not yet been demonstrated that achieves the desired emittances. Reduced emittances will decrease gain lengths. Peak current is consistent with higher energy beams and BC’s

  7. Example of Injector: APEX Insert Presentation Title in Slide Master

  8. SCRF Linac Insert Presentation Title in Slide Master Roughly 400 meters long including laser heater at ~100 MeV, BC1 at ~300 MeV and BC2 at 1000-2000 GeV. Long bypass line starting at Sector 9  BSY. LTU similar to LCLS-IISA discussed last month. Based on 1.3 GHz TESLA 9-cell cavity with minor mods for cw operation

  9. 1.3 GHz 8-cavity cryomodule (CM) • It is proposed to use an existing cryomodule design for the 4-GeV LCLS-II SRF linac. • CM is roughly 13 meters for 8 cavities plus a quadrupole package • The best-fit is the EU-XFEL cryomodule • Modifications are required for LCLS-II • (The CEBAF 12 GeV upgrade module must also be considered) • (The ILC CM is similar but has several important differences and is not as well suited for CW application) • 100 cryomodules of this design will be built and tested by the XFEL by 2016  Global industrial support for this task • One XFEL ~prototype CM was assembled and tested at Fermilab • (Fermilab assembled an ILC cryomodule and has parts for another)\

  10. Linac No warm breaks except BC: 1 cryo circuit per 3 kW load

  11. Linac View SLAC Linac (11 wide x 10 feet high) (3.35 x 3.05 m) x

  12. First 800 m of SLAC linac (1964): 350 m Injector Length Cryoplant placement and construction

  13. Assumed FEL Configuration Insert Presentation Title in Slide Master • High rep rate beam could be directed to either of two undulators HXR or SXR bunch-by-bunch • 120 Hz beam could be directed to the HXR at separate times • The SC linac would be located in Sectors 0-10 and would be transported to BSY in the 2km long Bypass Line. It would use a dual stage bunch compressor. • A dechirper might be used to further cancel energy spread for greater flexibility in beam parameters • The high rep rate beam energy would be 4 GeV and the HXR would fill the LCLS hall with ~144 m while the SXR would be <75 m so that it could be fit into ESA • Both undulators would need to support self-seeding as well as other seeding upgrades

  14. Undulator Requirements Insert Presentation Title in Slide Master Requirements: SXR self-seeding operation between 0.2 and 1.3 keV in ESA tunnel (<75 meters) with 2.5 to 4 GeV beam HXR self-seeding operation between 1.3 and 4 keV in LCLS tunnel (~144 meters) with 4 GeV beam HXR SASE operation up to 5 keV with 4 GeV beam Primary operation of SXR and TXR at constant beam energy  large K variation HXR operation comparable to present LCLS with 2 to 15 GeV beam

  15. Undulator Parameters Insert Presentation Title in Slide Master • To cover the range of 0.2 to 1.3 keV using SASE in less than 50 meters (to allow for seeding)  lw ~ 40 mm • A conventional hybrid undulator with 40 mm and a 7.2mm minimum gap would have Kmax ~ 6.0 which easily covers the desired wavelength range at 4 GeV • To achieve 5 keV using SASE with less than 144 m at 4 GeV  TXR lw <= 26 mm • A conventional hybrid undulator with 26mm and a 7.2mm minimum gap would have Kmax ~ 2.4 which covers desired wavelength range at 4 GeV • Provides reasonable performance with LCLS beam

  16. Baseline Tuning Range for 4 GeV Kmin = 0.55 SASE HXR: lu = 26 mm, L = 144 m SXR: lu= 41 mm, L = 75 m Self-Seeding Kmin = 0.91 Ephoton[keV] Kmin = 1.6 Self-Seeding Kmax = 2.44 Kmax = 6.0 Ebeam [GeV] Kmin is chosen to saturate within given length for SASE or Self-seeding Kmaxis set to the maximum value for a 7.2 mm gap variable gap undulator

  17. X-ray pulse energy at High Rate More than enough FEL power although results assume full beam and are ~2x optimistic Insert Presentation Title in Slide Master

  18. Comparison of HXR with LCLS performance at 120 Hz (1) 26 mm HXR covers 2 keV at ~4 GeV to 30+ keV at 14 GeV – beam energy might be reduced further if desired Insert Presentation Title in Slide Master

  19. Comparison of HXR with LCLS performance at 120 Hz (2) 26 mm HXR provides lower pulse energy than 30 mm LCLS but much shorter l Insert Presentation Title in Slide Master

  20. Options for HXR: SCU, IV, or 30 mm period (1) Insert Presentation Title in Slide Master To recover the LCLS performance, we need to increase K. Can (1) increase the period, (2) adopt an in-vacuum design, or (3) consider a planar or helical SCU. Example of a helical SCU below however have not included poorer SCU fill factor  results are optimistic

  21. Options for HXR: SCU, IV, or 30 mm period (2) Insert Presentation Title in Slide Master Example of a 30 mm period hybrid undulator below. Nearly recovers LCLS performance (reduction due to slightly larger gap with VG undulator) however the maximum photon energy at high rate, i.e., 4 GeV is now 4.3 keVnot5 keVas with 26 mm period

  22. SCU options Insert Presentation Title in Slide Master • An SCU has a number of benefits: • Would attain comparable performance as LCLS even while achieving 5 keV at 4 GeV at high rate by operating with high K • Would allow shorter SXR period to reduce SXR beam energy and gain length to ensure space in ESA while still covering full wavelength range at constant energy.

  23. GENESIS SIMULATION Electron parameters Good Bad Good Barely Good OK J. Wu (SLAC), jhwu@slac.stanford.edu, 08/05/2013 • Centroid energy 4 GeV; 100 pC compressed to 1 kA; normalized emittance: 0.45 mrad; slice energy spread: sE=300keV except for LCLS case with 15 GeV • 6 cases – details in following pages • Case 1: HXR Kmin = 0.91; lw= 26 mm; Lw= 144 m (study SS 4keV) • Case 2: SXR Kmin = 1.6; lw = 41 mm; Lw = 75 m (study 1.6 keV) • Case 3: SXR Kmax= 6.0; lw= 41 mm; Lw= 75 m (study 200 eV) • Case 4: SXR K = 1.9; lw = 41 mm; Lw = 75 m (study 1.3 keV) • Case 5: SXR K = 2.0; lw = 30 mm; Lw = 75 m (short gain len.) • Case 6: HXR in LCLS TW parameters but K too high for hybrid undulator

  24. Potential Areas of Collaboration with Partner Labs LCLS-II Overview

  25. Points of Contact Insert Presentation Title in Slide Master

  26. CDR Writing Insert Presentation Title in Slide Master • Must keep the document concise – it is a conceptual design • Executive Summary (Galayda) • Scientific Objectives (TBD) • Machine Performance and Parameters (Raubenheimer) • Project Overview (Galayda) • Electron Injector (Schmerge) • Superconducting Linac Technologies (Ross,Corlett) • Electron Bunch Compression and Transport (Raubenheimer, Emma) • FEL Systems (Nuhn) • Electron Beam Diagnostics (Frisch, Smith) • Start-to-End Tracking Simulations (Emma) • Photon Transport and Diagnostics (Rowen) • Experimental End-Stations (Schlotter) • Timing and Synchronization (Frisch) • Controls and Machine Protection (Shoaee, Welch) • Conventional Facilities (Law) • Environment, Safety and Health(Healy) • Radiological Issues (Rokni) • Future Upgrade Options (Galayda)

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