LCLS Injector/Linac Systems
Update
E. Bong
LCLS FAC
April 7, 2005
LCLS
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
LCLS Injector/Linac Systems Update
Plan Changes Since Last FAC
FY05 Schedule & LLP Activity
Shutdown Strategy
Design & Fabrication Status
Response to Last FAC Comments
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Nominal LCLS Linac Parameters for 1.5-Å FEL
Single bunch, 1-nC charge, 1.2-mm slice emittance, 120-Hz repetition rate…
6 MeV
z  0.83 mm
  0.05 %
250 MeV
z  0.19 mm
  1.6 %
Linac-X
L =0.6 m
rf= -160
14.1 GeV
z  0.022 mm
  0.01 %
135 MeV
z  0.83 mm
  0.10 %
rf
gun
Linac-1
L 9 m
rf  -25°
Linac-0
L =6 m
SLAC linac
21-1b
21-1d
DL-1
L 12 m
R56 0
E-Dump
Linac-2
L 330 m
rf  -41°
Linac-3
L 550 m
rf  -10°
21-3b
24-6d
25-1a
30-8c
X
BC-1
L 6 m
R56 -39 mm
SLAC linac tunnel
(RFLaser
phase: fnot
is at accelerating crest)
Drive
rf = 0shown
April 7, 2005
LCLS FAC Injector-Linac Update
4.54 GeV
z  0.022 mm
  0.71 %
BC-2
L 22 m
R56 -25 mm
undulator
L =130 m
LTU
L =275 m
R56  0
research yard
Thanks Paul Emma
Eric Bong
BONG@slac.stanford.edu
System Changes Since Last FAC
Continuing resolution delayed project funding
October electrical accident halted accelerator operations
Review of SLAC Safety Management Plan
Halt of program prompts revision of FY05 run and down
schedules
FY05 down moved to October ’06, shortened to one month
Injector and Linac System Management Combined
Injector and Linac Systems engineering and design staff
combined eliminating duplication of effort
Injector WBS converted from geographical to product
based. Manpower loaded schedule revised to condense
structure into products rather than individual components.
Schedule changed to better track cost performance.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Plan Changes Since Last FAC
Design, fabrication and installation schedule updated to
reflect change in Linac down dates.
RF Gun design and fabrication moved in-house to mitigate
schedule and technical risk.
Added LLNL and ANL collaborations on drive laser
temporal, spatial and THG studies.
Added UCLA collaboration to develop single shot bunch
length measurement device.
Formed agreement with Klystron department for RF
component design support including gun design.
Utilizing ILC personnel for dual-feed structure design.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
FY05 Schedule & LLP Activity
The change in ‘05 down time reduced the scope of
the planned installation in the Injector and changed
the design emphasis from the Linac to the Injector
side of the shielding wall.
LLP consists of fabrication activities in the Injector
which can be started in FY05, the X-Band system
components and BC1 & BC2 dipoles
$2M bulk vacuum purchase agreement – June 05
The portion of the Injector system in the Linac
Housing can not be fabricated in FY05.
The Linac L1 segment design is complete and
could be installed during the October 2005 down.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector-Linac Installation Strategy
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Laser System
Gun Region
Accel Region
Heater Region
Wall Region
Injection Region
Spect Region
June
2006
April
2006
March 2006
January 2006
October 2005
August 2006
August 2006
Waveguide through wall and up
penetration October 2005
Installation schedule sets design and fabrications deadlines
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector-Linac Installation Strategy
Linac 1 (L1)
Treaty Point LCLS
Injector/LCLS Linac
LCLS Injector
Two short accelerator
structures, refurbished
Quads+BPMs,X&YCOR
Bunch Compressor 1 (BC1)
X-Band
Structure
(NLC)
Quad + BPM,
YCOR,XCOR,
QE, Toroid
Bunch
Compressor &
Diagnostics
Emittance
Diagnostics.
LCLS Linac
Remove 5 S-Band Structures
Electrons
L1 Fabrication could be complete for October 2005 Installation
X-Band Fabrication started – Installation FY06 Down
BC1 Articulation ready for fabrication now
BC1 installation FY06 Down
Remainder of Linac installation FY07
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Drive Laser Progress
Proposals received from vendors, evaluation in process.
Pulse shaping and THG most difficult issues.
As a result of BNL/DUVFEL pulse shaping studies, further
collaboration set up with LLNL and ANL to study temporal,
spatial and THG. Require studies to mitigate technical risk.
Laser transport penetration tube design complete,
earthquake safety approved, ready for fabrication.
Integration and alignment of laser launch, RF gun and
solenoid being investigated.
3-D ellipsoidal distribution studies – C. LImborg
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector RF Design Progress
RF Gun
Solenoid design complete. Relative alignment details under study.
RF design altered due to review recommendations
Increased Mode separation
Z-Coupling from Theta-Coupling
RF design complete mechanical design started (in –house)
Monolithic dual feed
Unresolved issues:
Final design for bulk cooling system
Load lock deferred
L0 Accelerator structures
Dual feed RF design pieced-together for solenoid assembly
Both L0A and L0B dual feed on input
Mechanical design in process
Removed T-Cav from Li-11
Injector waveguide routing through wall in design
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Linac RF Design Progress
X-Band System
X-Band System layout reviewed.
Waveguide components maximizing use of available components
and designs.
ILC cold decision X-Band system components available from NLC
Two partially completed XL4 Klystrons – fabrication resumed
Available waveguide components selected and requested
X-Band structures selected
L1 Short accelerating structures
Structures available from spares, under evaluation for use.
L1 design complete, drawings available. Can be installed 10-05
Support agreement made with Klystron Department for
Injector and Linac RF work
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
1 nC
2.8 kA
0.2 nC
2.0 kA
no spikes
Low Charge Operations
Need 20% smaller emittance (0.8 mm), but with
1/5 charge & 1/3 gun current (30 A)
No more transverse wakes in linac
Almost no CSR in BC’s
2-times less peak-current jitter
No undulator wakes
3-times shorter X-ray pulse
1-nC still OK, but only ~twice the photons, and a
much more challenging machine
1.11012 photons
no resistive wake
W. Fawley, LBNL
Z. Huang
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
1
-Do gun tests as early as possible, at vendor maybe
Gun will be designed and built in-house to use strength of SLAC RF design and to
control technical risk. RF tests will proceed along with fabrication process including cold
tests during cold fit-up through to 120 Hz hot-tests of final assembly.
-Consider creation of a gun test facility
Over the past eight years the GTF has revealed several problems with the prototype gun
including correlated energy spread, tilt (transverse position to time correlation) on the
beam and asymmetric beam at the gun exit to name just a few. These issues have been
addressed in the LCLS design by increasing the 0 and pi mode separation, adding a dual
feed coupler with racetrack geometry to both the gun and linac sections and adding a
dipole and quadrupole corrector in the solenoid. In addition several diagnostic techniques
for determining the beam correlations have been developed over the years that will be
used in the LCLS injector to improve the overall beam quality.
A new gun test facility will be proposed. However, the facility is beyond the financial
scope of the LCLS project. It is suggested that future SLAC funds be allocated to a new
gun test facility which could have more benefit to SLAC than LCLS gun testing alone.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
2
-Order 2 guns
Parts for two guns will be machined. Tests performed on the first set of parts
will be used to dimensionally adjust the second set. The second set will be fully
assembled. Hot tests on the second set will be used to dimensionally adjust the
first set for final assembly.
-Recommend continued testing of laser pulse shaping at DUVFEL
Additional pulse shaping, third-harmonic-generation and launch optics testing
will be conducted in collaboration LLNL and ANL.
-Consider doing electron beam tests at DUVFEL
Electron beam bunch length measurement tests will be performed at SPPS in
collaboration with UCLA. Additional beamline component and controls tests are
also planned in SPPS.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
3
-Consider collaboration with LLNL on gun laser development
We are collaborating with LLNL on drive laser development.
-Recommend a hot spare laser
A hot spare laser is not in the project baseline. However, it is planned to use
contingency money, if available, will be used to purchase a second drive laser in FY08.
The second laser may be a new design.
-Recommend the formation of a laser group
An LCLS laser group will be formed. A requisition is in place for a laser group leader.
-Consider doing tests of "lock-in" detection of low gain at DUVFEL
-Consider x-band waveform modulation as the input modulation for lock-in detection
Lock-in low gain FEL signal detection using X-Band waveform modulation was not
investigated. The XTOD System investigated other low gain detection schemes.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
4
-Show analysis and simulations of collimator performance at the
next review, including shower computations
Collimator simulations will be presented at the FAC. The simulations
include dark current from the gun and various RF structures, linac and
LTU collimation, and undulator protection. Shower calculations will be
done soon, but may not be ready for the April 2005 FAC.
-Continue work on ESASE
ESASE work continues. LBNL is taking the lead on this study.
-Recommend x-y scanners for wire monitor, rather than diagonal
Performing modal analysis on existing design to determine if there is
any real benefit to tripling the number of wire scanners in the project
budget.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
5
-Consider the design of a feedback loop that adjusts the laser based on
electron beam measurements
Signal sources for laser feedback have been defined including bunch charge
and bunch timing signals.
-Consider options for the ULTIMATE LCLS Master Oscillator
A reliable oscillator of proven technology will be installed for LCLS.
Development work for the ULTIMATE master oscillator may be done in the
future as an upgrade.
-Continue tests of THz measurement techniques at SPPS
THz bunch length measurements in SPPS will continue once the SLAC Linac
resumes operations.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
6
-Consider schemes to modulate X-band phase for optimal set-up
-Place appropriate emphasis on challenging phase/amplitude
control of X-band system
Absolute phase and amplitude control of the X-Band system is not as
demanding as was understood. The shot-to-shot (fast) jitter tolerances are
fairly tight (0.5 deg-X and 0.25% amplitude, rms). This does not mean that
the absolute X-band phase and amplitude need to be held at their design
values to this level. The bunch length and energy feedback, described by
Juhao Wu, will also compensate for X-band phase and amplitude changes of
up to 10 degrees and 5%, as long as these variations occur slowly compared
with 120 Hz. The compensation is implemented by Linac-1 S-band phase
and amplitude corrections, but the net effect is to maintain a constant postBC1 bunch length and beam energy. A “dither” feedback, suggested by the
FAC, is therefore not as effective since it takes many pulses to dither the
system, and variations on this time scale will already be compensated by the
bunch length and energy feedback system. Perhaps a dither feedback can
be implemented for very slow time scales of more than one minute, but the
absolute regulation demands will then be quite loose (e.g., 2 degrees and
2%).
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
7
-Consider schemes to modulate X-band phase for optimal set-up
-Place appropriate emphasis on challenging phase/amplitude
control of X-band system
Absolute phase and amplitude control of the X-Band system is not as
demanding as was understood. The shot-to-shot (fast) jitter tolerances are
fairly tight (0.5 deg-X and 0.25% amplitude, rms). This does not mean that
the absolute X-band phase and amplitude need to be held at their design
values to this level. The bunch length and energy feedback, described by
Juhao Wu, will also compensate for X-band phase and amplitude changes of
up to 10 degrees and 5%, as long as these variations occur slowly compared
with 120 Hz. The compensation is implemented by Linac-1 S-band phase
and amplitude corrections, but the net effect is to maintain a constant postBC1 bunch length and beam energy. A “dither” feedback, suggested by the
FAC, is therefore not as effective since it takes many pulses to dither the
system, and variations on this time scale will already be compensated by the
bunch length and energy feedback system. Perhaps a dither feedback can
be implemented for very slow time scales of more than one minute, but the
absolute regulation demands will then be quite loose (e.g., 2 degrees and
2%).
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Response to October 2004 FAC
8
-By 1/2005, force a decision on undulator design
changes for AC wake fieldResistive wall wakefield studies were performed
(SLAC/ANL.) A low charge machine configuration now
looks like a very attractive operating point where resistivewall wakefields are not a problem. In addition, a semielliptical undulator vacuum chamber with aluminum
coating reduces the wakes to an acceptable level even at
the 1-nC charge level. No other large changes to the
undulator design have been necessary to further mitigate
the wakes.
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector/Linac Summary
Progress Made On
Laser Purchase, Laser Study Collaborations
RF Gun & Structure Design
X-Band System Design & Klystron Fabrication
Collimator Studies
Mechanical Design – Area Integration, Components
Magnet and Vacuum Procurement
Injector and Linac Design Staff Integrated
BCR to Modify Injector Manpower Loaded
Schedule Incorporating Linac Down Schedule
Changes, Better Cost-Performance Tracking
Added staff for magnet procurement and
diagnostics design
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
End
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
LCLS Injector/Linac Organizational Chart
Injector/Linac Systems
Eric Bong: Manager
Carl Rago: Deputy
Bob Dalesio
LCLS Controls
Richard M. Boyce
LCLS Installation
Manager
Dave Schultz
RF Systems
Injector/Linac Systems
Physicists
Paul Emma: Linac
C. Limborg: Injector
Sasha Gilevich
Injector Laser
Richard F. Boyce
Injector
Integration
LCLS Physics Support
Dave Dowell
John Schmerge
Paul Bolton
Zhirong Huang
Juhao Wu
Leif Eriksson
L1, L2, L3 BC1,
BC2 Integration,
Vacuum
Tim Montagne
LTU & E-Dump
Integration,
Diagnostics
Carl Rago
Mech. Data, RF
Distribution
Magnets
LCLS Injector/Linac Mechanical Engineering
RF Gun
Alan Hill
Injector RF
Peter McIntosh
Linac RF
Alan Miahnahri
Mike Palrang
Joe Stieber
Paul Stephans
Joe Franklin
Nick Braughton
Bill Brooks
Jim Stanfield
Ng Wing
SLAC Mechanical Design
Klystron
Department
Engineers
Designers
Fabrication
Klystron Department
Recent additions:
J Langton, Roger Carr
Stanford
ME Grad. RA
Ashish Mitra
Venkat Srinivasan
RF engineering, design and fabrication matrixed from Klystron Department
ILC engineering & design matrixed for dual feed structure design
Mechanical Design matrixed from SLAC Mechanical Design Department
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector Launch Feedback Model
Ron Akre, D. Kotturi
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector L0 Feedback Model
Ron Akre, D. Kotturi
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
LCLS Longitudinal Feedback Simulation
Details in Breakout J. Wu
feedback off
feedback on (Integral gain:0.5)
E / E  -0.0007 %;
E / E std  0.09 %
I / I  0.10 %;
I / I std  8.5 %
t  0.003 ps;
t std  0.15 ps
Juhao Wu (SLAC)
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector Wall Region Design
Beamline segment piercing Injector
vault shielding wall.
Includes valves, quadrupoles, OTRs,
wire scanners, BPMs, pumps, gages,
support stands, vacuum chambers.
Beamline layout assembled into wall
assembly model.
Design effort broken into diagnostics,
magnets, vacuum and integration.
Quadrupole order April 1, 2005
OTR body ready for vendor bid.
Wire scanner in design evaluation.
Installation scheduled October 2005
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector Heater Region Design
Beamline segment Between
Accelerators and Shielding
Wall
Includes laser heater,
transverse structure,
dipoles, quads, correctors
otrs.
Installation scheduled
January 2006
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Injector Waveguide Design
Waveguide network feeds gun,
Structures L0a & L0b, and T-Cav
Gun and structures fed from Li-20-6, 7 &
8 klystrons, T-Cav fed from Li-20-5d
structure exhaust.
3-D Layout integrated into Injector
system assembly
Design effort broken into penetrationwall runs, Gallery and Vault runs.
Installation penetration-wall October ’05
Installation Vault & Gallery Spring ’06
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
L1 Region Design
Beamline segment in Sector
21 Between Injector insertion
and X-Band structure.
Includes two shortened
accelerator structures, quads,
correctors and Bethe hole
couplers.
3-D Layout integrated into
Linac Girder model.
Design complete. Drawings
complete except couplers.
Fabrication could begin April
2005
Installation-early October ‘05
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
BC1 Region Design
Beamline segment in Sector 21 From XBand system, through compressor to
emittance diagnostics section.
Includes articulated compressor, interbend diagnostics, emittance wire
scanners, OTRs, quadrupoles and
vacuum components.
3-D Layout integrated into Linac Girder
model.
Design effort broken into chicane
articulation, diagnostics, magnets,
vacuum and integration.
Fabrication and testing of articulation
could begin April 2005
Installation – August 2006
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
X-Band System Design
60cm structure from
Fermi
X-Band Layout
Integrated into
beamline layout
XL4 Klystron in fab
Selected NLC
waveguide components
designed for 8-Pack
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
Linac L2, BC2, L3 Mechanical Design
System schematics complete
3-D models of area backgrounds complete
File management structure for 3-D models
complete
L2 and L3 modification ready to begin
BC2 design scheduled for FY06
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu
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
April 7, 2005
LCLS FAC Injector-Linac Update
Eric Bong
BONG@slac.stanford.edu