1. LCLS-II Design and FEL R&D
Summary of project scope
key milestones
funding profile
commissioning by LCLS operations
path to CD-2
priority of longer tunnel
urgency of getting CF bids
mention FAC
Tor O. Raubenheimer
for the LCLS and LCLS-II teams

2. LCLS Concept: Fourth Generation Workshop 20 Years Ago
C. Pellegrini, A 4 to 0.1 nm FEL Based on the SLAC Linac, Workshop on Fourth Generation Light Sources, February, 1992
Herman Winick’s Study Group
Claudio Pellegrini
Herman Winick
Engaged Bjorn Wiik and Gerd Materlik during sabbaticals at SLAC
High Brightness Electron Beams Workshop, 2013

3. Linac Coherent Light Source Facility
First Light April 2009, CD-4 June 2010
Injector at 2-km point
Existing Linac (1 km)
(with modifications)
UCLA
New e- Transfer Line (340 m)
Undulator (130 m)
Near Experiment Hall
X-ray Transport Line (200 m)
High Brightness Electron Beams Workshop, 2013
Far Experiment Hall

4. LCLS commissioning ended Oct. 2009
6 MeV
z  0.83 mm
  0.05 %
135 MeV
z  0.83 mm
  0.10 %
250 MeV
z  0.19 mm
  1.6 %
4.50 GeV
z  mm
  0.71 %
13.6 GeV
z  mm
  0.01 %
beam parked here
Linac-X
L =0.6 m
rf= -160
Linac-0
L =6 m rf
gun
L0-a,b
Linac-1
L 9 m
rf  -25°
Linac-2
L 330 m
rf  -41°
Linac-3
L 550 m
rf  0°
25-1a
30-8c
...existing
linac
21-3b
24-6d
21-1
b,c,d
undulator
L =130 m X
BC1
L 6 m
R56 -39 mm
BC2
L 22 m
R56 -25 mm
undulator
DL1
L 12 m
R56 0
DL2
L =275 m
Commission Mar-Aug 2007
Commission Jan-Aug 2008
Nov 2008…
SLAC linac tunnel
research yard
Generation of low emittance beam
Preservation of 6D brightness in accelerator and compressors
Undulators meeting tolerance and trajectory control
High Brightness Electron Beams Workshop, 2013

5. LCLS Operational Performance (480 eV – 10 keV)  (280 eV – 10 keV)
High Brightness Electron Beams Workshop, 2013

6. LCLS Achievements
Exceptional e- beam quality from RF gun (gex,y  0.4 mm)
Pulse length easily adjustable for users ( fs FWHM) with <<10 fs pulses at low charge (20 pC)
Wider photon energy range: eV (design was: eV)
Peak FEL power >70 GW (10 GW in CDR)
Pulse energy up to 6 mJ (2 mJ in CDR)
96.7% accelerator availability, 94.8% photon availability
Total of 133 publications, 35 in high impact journals
High Brightness Electron Beams Workshop, 2013

7. Linac Coherent Light Source II
1-km point
Sectors of
Linac (1 km)
(with modifications)
2010: April Critical Decision 0 approved
2011: October- Critical Decision 1 approved
2012: March Critical Decision 3a approved
2012: August- Critical Decision 2
2013: June Critical Decision 3b ??
2018: Sept First FEL Light
2019: Sept Critical Decision 4
Bypass LCLS Linac
In PEP Line
(extended)
New Beam Transport
Hall
SXR, HXR Undulators
X-ray Transport Optics/Diagnostics
High Brightness Electron Beams Workshop, 2013
New Underground Experiment Hall

8. LCLS-II Accelerator for 250 pC, 120 Hz
Injector, linac, and compression parameters are all very similar to LCLS-I, but not exact
High Brightness Electron Beams Workshop, 2013

9. LCLC-II Parameter Space Photon Energy vs Beam Energy
Calculation by H-D Nuhn
High Brightness Electron Beams Workshop, 2013

10. LCLS-II Greater Capacity
Dedicated new injector at Sector 10
Two new SASE undulator x-ray sources, both variable gap
High Field Physics Soft X-Ray Experiment Station
Immediately:
4X increase in operations hours for soft x-rays
Generally, soft x-ray experiments run one-at-a-time
Immediate 20% increase in operations hours for hard x-rays
Since hard x-ray instruments will someday run simultaneously, perhaps 2 or even 3 at a time, this can mean nearly 20% more time per station
Future: Room in new experiment hall for at least 3 more new instruments with new scientific capabilities
Future: 4th undulator in existing tunnel, 2 more instruments
High Brightness Electron Beams Workshop, 2013

11. LCLS-II Enhanced Capability
LCLS-II will provide expanded spectral range using two beamlines and variable gap undulators
Up to 13 keV (above Selenium GeV
Down to 250 eV (Carbon 7-10 GeV
300 meter undulator tunnel
Adequate space to accommodate future enhancements:
Options for BW control: SS, iSASE, pSASE, …
Two-color generation
Polarization control
TW peak power
Details will be determined by ongoing LCLS R&D program
High Brightness Electron Beams Workshop, 2013

12. LCLS-I R&D Studies Improving LCLS-II Design
Many beam physics studies on LCLS and NLCTA that are helping clarify LCLS-II design
Injector studies to optimize and verify performance:
rf gun, laser heater, BC1, and BC2
CSR and bunch shaping studies for longitudinal phase space
Jitter studies to understand performance limits
Component studies – LCLS-II designs are similar in many cases
Gain length, angular divergence, operational stability measurements to help specify x-ray characteristics
Other R&D studies enhancing the LCLS-II design
Polarization control, self-seeding, & improved diagnostics
Improved-SASE (iSASE) and Purified SASE (pSASE)
Two-color generation, …
High Brightness Electron Beams Workshop, 2013

13. LCLS-I FEL R&D Projects LCLS-I R&D will clarify LCLS-II upgradesTW
CTF (Cathode Test Facility)
High Brightness Electron Beams Workshop, 2013

14. Hard X-ray Self-Seeding
High Brightness Electron Beams Workshop, 2013

15. Hard X-Ray Self-Seeding New Capability in LCLS Operation
Nature Photonics
(2012)

16. Improved SASE (iSASE)
Improve longitudinal coherence by increasing the longitudinal slippage
Narrow SASE bandwidth without fixing the central photon energy.
Pulse Intensity is less sensitive to energy jitters
LCLS proof-of-principle experiment:
Use detuned undulator as phase shifts
Detune every other undulator after U5
J. Wu, A. Marinelli, Pellegrini, FEL2012

17. SASE: (red) 1.21 mJ; average spectrum (FWHM 17 eV)
iSASE experiment
SASE: (red) 1.21 mJ; average spectrum (FWHM 17 eV)
iSASE: (blue) 0.21 mJ; average spectrum (FWHM 5 eV)
Single shot spectrum (13.8 GeV,150 pC)
SASE
iSASE

18. TW FEL: LCLS Strong Tapering Studies
Envelope of measured power similar to on-energy simulations
Large sensitivity to energy jitter as previously observed
1% taper demonstrated
blue (on-energy), black (+0.1 %), red ( -0.1 % ), magenta (-0.2 %)
experiment
simulation
J. Wu, et al
High Brightness Electron Beams Workshop, 2013

19. TW FEL: LCLS Divergence Studies Specifying LCLS-II Apertures
X-ray stay clear (mirrors, diagnostics, energy attenuator) all depend on x-ray beam sizes
Measurements of LCLS Angular Divergence
Y. Feng, J. Krzywinski, J. Turner, J. Welch
High Brightness Electron Beams Workshop, 2013

20. XTCAV: LCLS X-Band Transverse Cavity
A deflecting cavity has been installed after the undulator to measure the longitudinal phase space (t, DE/E) of the e- and g beams
P. Krejcik
Y. Ding
Commissioning to start soon!
High Brightness Electron Beams Workshop, 2013

21. XTCAV: e- and g Longitudinal Phase Space
FEL off
FEL on
Reconstructed e- profile
Reconstructed g profile
Soft
X-Rays
Hard
X-Rays
Y. Ding
High Brightness Electron Beams Workshop, 2013

22. HXR Beam Splitting at LCLS It works!!
High Brightness Electron Beams Workshop, 2013

23. Two-color FEL Single slotted foil to control pulse duration
Chicane to control delay
A. Lutman, R. Coffee, Y. Ding, et al.
Magnetic Chicane
1st undulator section K1 e-
x-ray
1st Color
2nd undulator section
2nd Color
Controlled Delay K2
Color separation 19 eV
Eb = MeV and Eg = 1.5 keV

24. DELTA Undulator for Polarization Control
Flexible post-saturation taper
Second-harmonic afterburner
Simple upgrade to LCLS undulator
Cornell 0.3-m Delta undulator
(A. Temnykh)
LCLS 1-m prototype
H.-D. Nuhn, E. Kraft
High Brightness Electron Beams Workshop, 2013

25. Soft X-Ray Self Seeding
Photon energy eV (expandable to eV)
Resolving power ~ 5000
Fit in one undulator section (U9), < 4m in length
SLAC, LBNL, PSI collaboration
High Brightness Electron Beams Workshop, 2013

26. SLAC X-ray FEL R&D roadmap
LCLS-II injector
LCLS-II completion
X-ray seeding & brightness
HXRSS
iSASE
TWFEL
Soft X-Ray Self-Seeding
ECHO-7
ECHO-75, laser phase error error
Zhirong Huang
HHG efficiency and control
E-beam brightness & manipulation
ASTA (Cathode R&D)
Injector R&D
ITF-FACET2: advanced beam generation, high-energy compression and seeding
Ultrafast techniques
Temporal diagnostics & timing
Attosecond & mode-locking x-rays
THz & Polarization
THz
THz Facility Options
Polarization control
Technology
development
X-ray spectrometer, beam sharing
Multi bunches, detectors, novel undulators, high-rep. rate
Completed
Ongoing
Under development

27. Summary LCLS has been a great success
Very flexible beam operations allows for wide range of photon science studies
R&D program is defining new capability
Short fs-scale bunches
Wide photon energy range; photon beam splitting
Self-seeding with >0.01% BW; iSASE
Two color operation
Polarized x-rays
Strongly tapered operation
LCLS-II will be the next addition to the SLAC photon science portfolio  expands LCLS capability and capacity greatly
High Brightness Electron Beams Workshop, 2013