LCLS-II Design and FEL R&D
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Transcript of LCLS-II Design and FEL R&D
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Tor O. Raubenheimerfor the LCLS and LCLS-II teams
LCLS-II Design
and FELR&D
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2High Brightness Electron Beams Workshop, 2013
LCLS Concept: Fourth Generation Workshop20 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 GroupClaudio Pellegrini Herman Winick
Engaged Bjorn Wiik andGerd Materlik duringsabbaticals at SLAC
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Slide 3
High Brightness Electron Beams Workshop, 2013
Linac Coherent Light Source FacilityInjector at 2-km point
Existing Linac (1 km)(with modifications)
First Light April 2009, CD-4 June 2010
New e- Transfer Line (340 m)
X-ray Transport Line (200 m)
UCLA
Undulator (130 m)
Near Experiment Hall
Far Experiment Hall
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High Brightness Electron Beams Workshop, 2013
SLAC linac tunnel research yard
Linac-0L =6 m
Linac-1L 9 mrf -25°
Linac-2L 330 mrf -41°
Linac-3L 550 mrf 0°
BC1L 6 m
R56 -39 mm
BC2L 22 m
R56 -25 mm DL2 L =275 m
DL1L 12 mR56 0
undulatorL =130 m
6 MeVz 0.83 mm 0.05 %
135 MeVz 0.83 mm 0.10 %
250 MeVz 0.19 mm 1.6 %
4.50 GeVz 0.022 mm 0.71 %
13.6 GeVz 0.022 mm 0.01 %
Linac-XL =0.6 mrf= -160
21-1b,c,d
...existinglinac
L0-a,b
rfgun
21-3b24-6dX 25-1a
30-8c
undulator
Commission Mar-Aug 2007 Commission Jan-Aug 2008
beam parked here
Generation of low emittance beam Preservation of 6D brightness in accelerator and compressors Undulators meeting tolerance and trajectory control
LCLS commissioning ended Oct. 2009
Nov 2008…
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5High Brightness Electron Beams Workshop, 2013
LCLS Operational Performance(480 eV – 10 keV) (280 eV – 10 keV)
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High Brightness Electron Beams Workshop, 2013
• Exceptional e- beam quality from RF gun (gex,y 0.4 mm)
• Pulse length easily adjustable for users (60 - 500 fs FWHM)
with <<10 fs pulses at low charge (20 pC)
• Wider photon energy range: 280 - 10000 eV (design was:
830 - 8300 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
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LCLS Achievements
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Slide 7
High Brightness Electron Beams Workshop, 2013
Linac Coherent Light Source IIInjector @1-km point
Sectors 10-20 ofLinac (1 km)(with modifications)
X-ray Transport Optics/Diagnostics
New Underground Experiment Hall
Bypass LCLS LinacIn PEP Line(extended)
New Beam TransportHall
SXR, HXR Undulators
2010: April- Critical Decision 0 approved2011: October- Critical Decision 1 approved2012: March- Critical Decision 3a approved2012: August- Critical Decision 22013: June- Critical Decision 3b ??2018: Sept. First FEL Light2019: Sept. Critical Decision 4
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LCLS-II Accelerator for 250 pC, 120 Hz
Injector, linac, and compression parameters are all very similar to LCLS-I, but not exactHigh Brightness Electron Beams Workshop, 2013 8
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LCLC-II Parameter Space Photon Energy vs Beam Energy
Calculation by H-D Nuhn
High Brightness Electron Beams Workshop, 2013 9
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10High Brightness Electron Beams Workshop, 2013
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
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High Brightness Electron Beams Workshop, 2013
LCLS-II Enhanced Capability
LCLS-II will provide expanded spectral range using two beamlines and variable gap undulators
- Up to 13 keV (above Selenium K-edge) @ 10.5-13.5 GeV- Down to 250 eV (Carbon K-edge) @ 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 program11
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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 12
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LCLS-I FEL R&D ProjectsLCLS-I R&D will clarify LCLS-II upgrades
TW
CTF (Cathode Test Facility)
High Brightness Electron Beams Workshop, 2013
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Hard X-ray Self-Seeding
High Brightness Electron Beams Workshop, 2013
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Hard X-Ray Self-SeedingNew Capability in LCLS Operation
Nature Photonics (2012)
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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
Improved SASE (iSASE)
J. Wu, A. Marinelli, Pellegrini, FEL2012
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iSASE experiment
SASE: (red) 1.21 mJ; average spectrum (FWHM 17 eV)iSASE: (blue) 0.21 mJ; average spectrum (FWHM 5 eV)
SASE iSASE
Single shot spectrum (13.8 GeV,150 pC)
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High Brightness Electron Beams Workshop, 2013 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 %)
simulation
experiment
J. Wu, et al
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19High Brightness Electron Beams Workshop, 2013
TW FEL: LCLS Divergence StudiesSpecifying LCLS-II Apertures
Measurements of LCLS Angular Divergence
Y. Feng, J. Krzywinski, J. Turner, J. Welch
• X-ray stay clear (mirrors, diagnostics, energy attenuator) all depend on x-ray beam sizes
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XTCAV: LCLS X-Band Transverse Cavity
Commissioning to start soon! P. KrejcikY. Ding
• A deflecting cavity has been installed after the undulator to measure the longitudinal phase space (t, DE/E) of the e- and g beams
High Brightness Electron Beams Workshop, 2013
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XTCAV: e- and g Longitudinal Phase Space
SoftX-Rays
HardX-Rays
Y. DingReconstructed e- profile Reconstructed g profile
FEL off FEL on
High Brightness Electron Beams Workshop, 2013
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HXR Beam Splitting at LCLSIt works!!
High Brightness Electron Beams Workshop, 2013
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Two-color FELSingle slotted foil to control pulse durationChicane to control delay
Magnetic Chicane1st undulator section
K1
e-
x-ray1st Color
2nd undulator section
x-ray2nd Color
Controlled Delay
K2
A. Lutman, R. Coffee, Y. Ding, et al.
Eb = 5800 MeV and Eg = 1.5 keVColor separation 19 eV
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DELTA Undulator for Polarization Control
Cornell 0.3-m Delta undulator (A. Temnykh)
• Polarization control• Flexible post-saturation taper• Second-harmonic afterburner• Simple upgrade to LCLS undulator
H.-D. Nuhn, E. KraftLCLS 1-m prototype
High Brightness Electron Beams Workshop, 2013
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High Brightness Electron Beams Workshop, 2013
Soft X-Ray Self Seeding
SLAC, LBNL, PSI collaboration
• Photon energy 500-1000 eV (expandable to 300-1200 eV)• Resolving power ~ 5000• Fit in one undulator section (U9), < 4m in length
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2011-12 2015-162013-14 2017-18 2019-20
LCLS-II injector LCLS-II completion
HXRSS
Injector R&DITF-FACET2: advanced beam generation,
high-energy compression and seeding
Temporal diagnostics & timing
Attosecond & mode-locking x-rays
X-ray seeding & brightness
E-beam brightness & manipulation
Technologydevelopment
Ultrafast techniques
ECHO-7
Soft X-Ray Self-SeedingECHO-75, laser phase error
error
THz & Polarization
THz
Polarization control
Multi bunches, detectors, novel undulators, high-rep. rate
ASTA (Cathode R&D)
X-ray spectrometer, beam sharing
TWFEL
HHG efficiency and control
Completed Ongoing Under development
iSASE
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SLAC X-ray FEL R&D roadmap
Zhirong Huang
THz Facility Options
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27High Brightness Electron Beams Workshop, 2013
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