LCLS Linac Update E. Bong Facility Advisory Committee Meeting October 12, 2004

LCLS Linac Update Brief Overview L1 & BC1 Progress LTU & E-Dump Status Continuing Resolution Impact

Nominal LCLS Linac Parameters for 1.5-Å FEL Single bunch, 1-nC charge, 1.2-mm slice emittance, 120-Hz repetition rate… 135 MeV z  0.83 mm   0.10 % 250 MeV z  0.19 mm   1.6 % 14.1 GeV z  0.022 mm   0.01 % 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° 21-1b 21-1d X 21-3b 24-6d 25-1a 30-8c undulator L =130 m 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 SLAC linac tunnel research yard (RF phase: frf = 0 is at accelerating crest)

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 (<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 Linac Physics Requirement Document PRD# 1.3-001

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

L1 & BC1 Subsystem System background 3-D complete Linac 1 (L1) Bunch Compressor 1 (BC1) Treaty Point LCLS Injector/LCLS Linac Two short accelerator structures, refurbished Quads+BPMs,X&YCOR X-Band Structure (NLC) Quad + BPM, YCOR,XCOR, QE, Toroid Bunch Compressor & Diagnostics Emittance Diagnostics. LCLS Injector LCLS Linac Remove 5 S-Band Structures Electrons System background 3-D complete X-Band structure and waveguide network design in progress BC1 chicane articulation design in progress Dimensional checks between mechanical layout and physics deck performed Work remaining: short accelerators, emittance diagnostics section

X-Band System Design 60cm structure from Fermi Integrated into beamline layout Translation to be designed XL4 Klystron NLC waveguide components designed for 8-Pack

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

LCLS Linac L2, BC2, L3 Except for BC2 in Linac Sector 24, Linac Sectors 22-30 largely unmodified System schematics complete 3-D models of area backgrounds near complete File management structure for 3-D models complete

LCLS Linac LTU Subsystem Schematic Energy and emittance diagnostics, energy collimation, bunch length diagnostics and undulator launch feedback 3-D solid automated layout generated from MAD done

Multiple Undulator Expansion Capability LTU Multiple beamlines NOT in LCLS baseline scope Baseline design not to exclude possibility of expansion

Main Dump and Safety Dump Main dump electromagnets allow energy and energy spread measurements 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

LCLS Linac Work Plan by Area Design, 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

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

LCLS Linac Challenges RF Stability Bunch Length Measurement & Feedback 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 Bunch length measurement in R&D at SPPS Feedback modeling and simulation by J. Wu Epics/SLAC Controls System Compatibility 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 Articulation required for R56 tuning for full range of beam charge Move for Accelerator centerline for un-damped beam operation BPM Module Design Measurement of full range of beam charge required Two beam e+ e- beam operations place additional challenge on module design

Work Plan Next 6 Months Matrix in Klystron Dept. engineering and design support for X-Band modulator and 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 Develop detailed installation plan Integrate Injector and Linac engineering groups

Linac System Progress Summary Linac baseline presented to EIR Linac area schematics complete Linac Li21-30 3D backgrounds in process L1, BC1 and X-Band modeling underway Conducted L1 & BC1 preliminary design review E-Dump & Safety Dump design under radiation safety review Jitter model developed and feedback simulations conducted, presented at XFEL conference J. Wu

Continuing Resolution Impact Procurement of long lead items delayed Ramp-up of engineering effort delayed In most cases delays decrease schedule float X-Band Klystron will not be ready for FY’06 downtime

End

BC 1 X-Band Compressor

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

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

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

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

LCLS Longitudinal Feedback Simulation feedback off feedback on (Integral gain:0.5) Juhao Wu (SLAC)