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Linac Overview E. Bong LCLS FAC Meeting April 29, 2004

Linac Overview E. Bong LCLS FAC Meeting April 29, 2004. LCLS. COST Report – WBS3 x Fund. COST Report – WBS3 x Fund. LCLS Linac Milestones. Data from LCLS Project Manpower Loaded Schedule. Nominal System Design. 1.5-Å SASE FEL Linac: Requirements Acceleration to 14.3 GeV (4.5 GeV min.)

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Linac Overview E. Bong LCLS FAC Meeting April 29, 2004

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  1. Linac OverviewE. BongLCLS FAC Meeting April 29, 2004 LCLS LCLS FAC Meeting - April 29, 2004

  2. COST Report – WBS3 x Fund LCLS FAC Meeting - April 29, 2004

  3. COST Report – WBS3 x Fund LCLS FAC Meeting - April 29, 2004

  4. LCLS Linac Milestones Data from LCLS Project Manpower Loaded Schedule LCLS FAC Meeting - April 29, 2004

  5. Nominal System Design 1.5-Å SASE FEL Linac: • Requirements • Acceleration to 14.3 GeV (4.5 GeV min.) • Bunch compression to 3.4 kA (gex,y 1.2 mm) • Emittance preservation (<20% ‘slice’, <100% ‘projected’) • Final energy spread (<0.02% ‘slice’, <0.1% ‘projected’) • Minimal sensitivity to system ‘jitter’ • Diagnostics integrated into design • Flexible operations (1.5 to 15 Å, low-charge, chirp, etc.) • Compatibility with other SLAC programs use 2 compressors, 3 linacs LCLS FAC Meeting - April 29, 2004

  6. Nominal LCLS Linac Parameters for 1.5-Å FEL Single bunch, 1-nC charge, 1.2-mm slice emittance, 120-Hz repetition rate… 250 MeV z  0.19 mm   1.6 % 14.1 GeV z  0.022 mm   0.01 % 135 MeV z  0.83 mm   0.10 % Linac-X L =0.6 m rf= -160 4.54 GeV z  0.022 mm   0.71 % LCLS INJ Linac-1 L 9 m rf  -25° Linac-2 L 330 m rf  -41° Linac-3 L 550 m rf  -10° undulator L =130 m 21-1b 21-1d 21-3b 24-6d 25-1a 30-8c X SLAC linac BC-1 L 6 m R56 -39 mm BC-2 L 22 m R56 -25 mm DL-1 L 12 m R56 0 LTU L =275 m R56  0 research yard SLAC linac tunnel LCLS FAC Meeting - April 29, 2004 (RF phase: frf= 0 is at accelerating crest)

  7. LCLS Linac L1 Subsystem • Linac Sector 21-1 • Accelerates a single 1-nC, 10-ps long electron bunch, at a repetition rate of 120 Hz, from 135 MeV to 250 MeV. Introduces energy chirp to allow bunch compression in BC1. X-Band linearizes energy spread. LCLS FAC Meeting - April 29, 2004

  8. Linac Sector 21-2a to 21-3a Compresses a single 1-nC, 830-mm long (rms) electron bunch, at a repetition rate of 120 Hz, at 250 MeV to an rms length of 190 mm. LCLS Linac BC1 Subsystem LCLS FAC Meeting - April 29, 2004

  9. Linac Sector 21-3b to 24-6d. Largely unmodified SLAC Linac. Accelerates a single 1-nC, 0.2-mm long electron bunch, at a repetition rate of 120 Hz, from 250 MeV to 4.5 GeV . Energy chirps the bunch to allow compression in BC2. LCLS Linac L2 Subsystem LCLS FAC Meeting - April 29, 2004

  10. Linac Sector 24-7a to 24-8d. compress a single 1-nC, 195-mm long (rms) electron bunch, at a repetition rate of 120 Hz, at 4.54 GeV to an rms length of 22 mm LCLS Linac BC2 Subsystem LCLS FAC Meeting - April 29, 2004

  11. Linac Sector 25 to 30. Largely unmodified SLAC Linac. LCLS Linac L3 Subsystem LCLS FAC Meeting - April 29, 2004

  12. Linac Sector 25 to 30. Largely unmodified SLAC Linac. Accelerates a single 1-nC, 0.02-mm long electron bunch, at a repetition rate of 120 Hz, from 4.5 GeV to 14.3 GeV . LCLS Linac L3 Subsystem LCLS FAC Meeting - April 29, 2004

  13. LCLS Linac LTU Subsystem Schematic LCLS FAC Meeting - April 29, 2004

  14. New Beamline extending from FFTB muon plug wall in SLAC BSY, across research yard in new housing to FEL undulator. Transports a 1-nC, 20-mm long (rms) electron bunch, at a repetition rate of 120 Hz, at 14 GeV to the LCLS FEL undulator. Includes energy and emittance diagnostics, energy collimation, bunch length diagnostics and undulator launch feedback. LCLS Linac LTU Subsystem LCLS FAC Meeting - April 29, 2004

  15. New Beamline located between exit of Undulator and Near Experimental Hall in new underground housing. Separates electron beam from X-Ray FEL beam directs beam to dump. Includes energy and energy spread measurement capability to 10-4 LCLS Linac E-Dump Subsystem LCLS FAC Meeting - April 29, 2004

  16. LCLS Linac X-Band Subsystem • X-Band located in L1 just up-stream of BC1 bunch compressor. • Linearizes energy gradient prior to bunch compression to minimize CSR instability. • 1 x XL-4 klystron feeding 1 NLC-type accelerating structure. LCLS FAC Meeting - April 29, 2004

  17. LCLS Linac Challenges • RF Stability (See R. Akre talk) • Existing system phase and amplitude stable to requirements over several seconds. • Require bunch length and energy feedback to meet requirements over longer time scales. • Bunch Length Measurement & Feedback (See P. Krejcik talk) • Bunch length measurement in R&D at SPPS. • Epics/SLAC Controls System Compatibility (See Controls breakout talks) • Require Epics system to access SLC control system in order to operate existing equipment required for LCLS. • SLC control system needs to access EPICS system to operate LCLS upgraded equipment required in high power beam operations. • Articulated Bunch Compressors (See P. Emma talk) • Articulation required for R56 tuning for full range of beam charge. • Simplification of LUTL bend chamber design to reduce design challenge. • BPM Module Design (See P. Krejcik talk) • Measurement of full range of beam charge required. • Two beam e+ e- beam operations place additional challenge on module design. LCLS FAC Meeting - April 29, 2004

  18. LCLS/SLAC Program Compatibility • Program Changeover Time • 15 minutes from LCLS to damped SLAC beam. • 24 hours from LCLS to undamped ESA beam. • Moving Chicanes • Articulates collinear with linac axis for straight-ahead. • X-Band Structure Aperture • 7mm, smaller than linac scrapers (16.5mm) • Smaller than undamped beam. • Moves off-axis, temporary pipe installed. • BPM Module Design • Charge Range. LCLS 0.2nC to 1nC. ESA ??? • Two Beam e- e+ Running. LCLS FAC Meeting - April 29, 2004

  19. Multiple Undulator Expansion LCLS FAC Meeting - April 29, 2004

  20. LCLS Linac System Summary • Layout and initial design of system underway. • Expertise on site for design and execution of modifications to existing SLAC Linac and construction of new beamlines. • Simplification of LEUTL chicane and experience with SPPS chicane to be applied to LCLS Chicane. • BPM module design challenging. • RF stability looks achievable. • Bunch length measurement required for RF feedback in R&D phase. LCLS FAC Meeting - April 29, 2004

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