LCLS Linac Overview E' Bong Lehman Review August 10, 2004

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LCLS Linac OverviewE. Bong Lehman Review
August 10, 2004
LCLS
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LCLS Linac Overview

• Technical Scope and Status
• Linac Functional Areas
• Long Lead Procurement Items
• Schedule and Organization
• Linac Challenges

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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
E-Dump
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
X
21-3b 24-6d
25-1a 30-8c
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
(RF phase frf 0 is at accelerating crest)
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Baseline 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 (lt20 slice, lt100
  projected)
• Final energy spread (lt0.02 slice, lt0.1
  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

• Linac Physics Requirement Document PRD 1.3-001

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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. Full ESA beam
• Two Beam e- e Running

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L1 BC1 Subsystem
Linac 1 (L1)
Bunch Compressor 1 (BC1)
Treaty Point LCLS Injector/LCLS Linac
Two short accelerator structures, refurbished
QuadsBPMs,XYCOR
X-Band Structure (NLC)
Quad BPM, YCOR,XCOR, QE, Toroid
Emittance Diagnostics.
Bunch Compressor Diagnostics
LCLS Injector
LCLS Linac
Remove 4 S-Band Structures
Electrons

• L1 Requirements PRD 1.3-002
• BC1 Requirements PRD 1.3-003
• Installation 06 shutdown

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X-Band System Design

• 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 X-Band accelerating
  structure obtained from NLC
• Long Lead Procurement Item
• Installation Summer 06 and 06 shutdown
• Requirements PRD 1.3-009

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BC1 System Design Status

• Articulated bunch compressor layout
• Dynamic solid modeling
• Bend Magnets LLP
• Install FY 06 shutdown

• BC1 inter-bend diagnostics package
• BPM, collimator, OTR

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LCLS Linac L2 Subsystem

• Linac Sector 21-3b to 24-6d. Largely unmodified
  SLAC Linac.
• Energy chirps the bunch to allow compression in
  BC2
• RF stability critical
• Four wire scanners added for emittance
  measurement
• Requirements PRD 1.3-004

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LCLS Linac BC2 Subsystem

• Linac Sector 24-7a to 24-8d, Remove eight S-Band
  structures
• 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
• BC2 Bends, Long Lead Procurement Item
• Requirements PRD 1.3-005

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LCLS Linac L3 Subsystem

• Linac Sector 25 to 30 largely unmodified.
• Two accelerator structures added, two structures
  moved, two wire scanners moved, transverse cavity
  moved, new OTR screen.
• Requirements PRD 1.3-006

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LCLS Linac LTU Subsystem

• 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
• Requirements PRD 1.3-007

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LCLS Linac LTU Subsystem Schematic
3-D solid automated layout generated from
MAD also done
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Multiple Undulator Expansion Capability
LTU

• Multiple beamlines NOT in LCLS baseline scope
• Baseline design not to exclude possibility of
  expansion

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LCLS Linac E-Dump Subsystem

• 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
• Requirements PRD 1.3-008

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Safety Dump Concept

• Safety dump permanent magnets deflect e-beam on
  BYD failure
• Ray traces show no beam transported through wall
  in any failure condition
• Working with SLAC Radiation Safety for approval
  of design
• Specification ESD 1.3-117

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LCLS Linac Challenges

• RF Stability (RF/Timing Design, R. Akre Linac
  Long-lead Procurement P. McIntosh)
• Existing system phase and amplitude stable to
  requirements over several seconds
• Stability achievable over longer time scales
  using bunch length and energy feedback
• Bunch Length Measurement Feedback (E-Beam
  Diagnostics , P. Krejcik)
• Bunch length measurement in RD at SPPS
• Epics/SLAC Controls System Compatibility
  (Controls System breakouts)
• 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 (Physics
  Requirements for Linac, P. Emma)
• Articulation required for R56 tuning for full
  range of beam charge
• Simplification of LEUTL design to reduce design
  challenge
• BPM Module Design (Controls System Breakouts)
• Measurement of full range of beam charge required
• Two beam e e- beam operations place additional
  challenge on module design

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LCLS Linac Work Plan by AreaDesign, Long Lead
Procurement, Construction, Installation, FEL
Commissioning
LLP X-Band
LLP BC1 BC2 Bends

• L1, BC1, L2, BC2 and L3 must be installed during
  SLAC Linac downtimes.

SLAC Linac Downtimes
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Budgeted Cost of Work Scheduled (BCWS)
FY04 to FY05 increase in funding - X-Band System
LLP FY05 to FY06 increase in funding
Construction
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LCLS Linac Organizational Chart

• Resources obtained through both direct hire and
  matrixed from SLAC departments
• Resources within groups distributed based on
  project demands
• Communication between systems managed through
  Interface Control Documents

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Linac System Progress Summary

• SC Wiggler removed from Linac baseline
• Conducted Linac Technical Design Review
• Linac status to Facility Advisory Committee
• Linac baseline presented to EIR
• Linac area schematics complete
• L1, BC1 and X-Band modeling underway
• Conducted L1 BC1 preliminary design review
• E-Dump Safety Dump design ready for Radiations
  Safety Committee review
• Jitter model developed and feedback simulations
  conducted, presented at XFEL conference J. Wu

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Work Plan Next 6 Months

• Matrix in Klystron Dept. engineering and design
  support for X-Band LLRF design
• Begin procurement of X-Band system
• Begin procurement of BC1 BC2 dipoles
• Complete L1 BC1 design details
• Complete BC1 diagnostics design details
• Begin L2 L3 system design
• Obtain Radiation Physics approval of safety dump
  design
• Continue jitter and feedback modeling
• Develop commissioning plans

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LCLS Linac System Conclusions

• L1 and BC1 design progress on schedule
• Linac system baseline established
• X-Band system BC Magnets ready for FY05 LLP
  funding
• RF stability achievable with feedback
• Bunch length measurement RD in progress

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End
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BC 1 X-Band Compressor