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LCLS-II HE Facility Overview Advanced Instrumentation for LCLS-II HE Science October 16-17, 2018
David Fritz
LCLS-II HE DOE Review, June 19-21, 2018
LCLS-II New Injector and New Superconducting Linac
Existing Bypass Line
New Transport Line
Two New Undulators And X-Ray Transport
Exploit Existing Experimental Stations
New Cryoplant
Remove SLAC Linac from Sectors 0-10
LCLS-II Key Performance Parameters
Early Finish in FY21
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LCLS-II variable gap hybrid undulators Development with LBNL and ANL
Frame
Variable gap undulators used in LCLS-II to provide greater wavelength tuning flexibility
• Vertical gap horizontally polarized undulator for soft x-ray branch
• Horizontal gap vertically polarized undulator for hard x-ray branch
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Linac Coherent Light Source II (LCLS-II)
Now HXU - Cu SXU – Cu HXU - SC SXU - SC
Photon Energy Range (keV) 0.25 -12.8 1 - 25 0.25 - 6 1 - 5 0.25 - 1.6
Repetition Rate (Hz) 120 120 120 929,000 929,000
Per Pulse Energy (mJ) ~ 4 ~ 4 ~ 8 ~ 0.2 ~ 1
Photons/Second ~ 1014 ~ 1014 ~ 1014 ~ 1016 ~ 1017
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LCLS-II-HE Overview - Accelerator Upgrades
1. Upgrading the LCLS-II superconducting linac to 8 GeV with nominal bunch frequency of 1 MHz to allow programmable FEL X-ray pulses up to 1 MHz repetition rate.
2. Installing a new cryogenic distribution box and transfer line between the cryoplant and the new L4 linac.
3. Addition of a pulsed low-energy extraction point in the superconducting linac at 3.8 GeV to allow quasi-independent operation of the soft-X-ray and hard-X-ray programs.
4. Use of an existing transport line to bypass the midsection of the SLAC linac and the LCLS linac along with installation of a new dump the at the end of the transport line.
5. Installation of a Hard X-ray Self Seeding capability in the hard X-ray undulator capable of operating at high repetition rate.
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Operation Modes
Spreader and new BSY2 kicker allow flexible patterns to HXR and SXR FELs (decouple undulator rate from linac)
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Start-2-End Simulation Results
Examples at 8 and 13 keV Fundamental Energy 8 keV 13 keV Units
Maximum Repetition Rate 929 (300) 929 (300) kHz
FW Pulse Duration 30 (105) 30 (102) fs
Total energy/pulse 235 (625) 108 (57) µJ
Source point relative to end of undulator 25 (19) 24 (21) m
First Harmonic
Photons per FEL pulse 0.18 (0.49) 0.05 (0.028) 1012
Relative FWHM Bandwidth 0.05 (0.09) 0.06(0.1) %
FWHM Source Size 36 (37) 26 (22) 𝜇m
FWHM Source Divergence 2.4 (2.0) 1.8 (1.8) 𝜇rad
Third Harmonic
Photons per FEL pulse 0.15 (0.29) 0 . 0 1 6 (0.005) 1010
Relative FWHM Bandwidth 0.05 (0.09) 0.06 (0.1) %
FWHM Source Size <36 (<37) <26 (<22) 𝜇m
FWHM Source Divergence <2.4 (<2.0) <1.8 (<1.8) 𝜇rad
20 pC, 13 keV
100 pC, 8 keV
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Photon Energy Upgrade Options
Reduced emittance, higher peak current, and/or higher energy can enable higher photon energies (>17 keV)
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The LCLS X-ray Instruments Today
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Notional Instrumentation Plan for LCLS-II-HE
Far Hall
DXS MFX CXI1 MEC
Near Hall
N1.1 N1.2 XPP
N2.2
CXI2
~ 50 m ~ 70 m
Blue – Upgraded for LCLS-II Black – Reuse (up to 2 kHz) Red – Upgraded for LCLS-II-HE Green – New for LCLS-II-HE
NXI
Build 1 new instrument • XCS à Dynamic X-ray Scattering (DXS) Endstation
Upgrade 2 instruments • XPP à Upgrade optics & diagnostics and Detector • CXI à Upgrade microfocus system
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New and upgraded instruments will address the science needs and take advantage of the transformative nature of LCLS-II-HE
• Key Performance Parameter - 3 upgraded endstations
• Objective KPP - 5 upgraded endstations
Instr. Upgrade Plan Science Opportunities
XPP New detector Upgraded diagnostics
• Understand coupled dynamics of molecular structure and charge & their role in energy flow
• Characterize materials heterogeneity, fluctuations & link to function
DXS Repetition rate enhancement IXS capability
• Map collective excitations & understand their relation to emergent phenomena in complex materials
• Characterize materials heterogeneity, fluctuations & link to function
CXI New optics & detector, Enhanced DAQ
• Reveal the role of structural dynamics in biological function • Catalysis: Reveal the correlation between chemical reactivity & structural
dynamics
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High Average Power X-ray Optics
§ Dynamically bendable mirrors ̶ Water cooled ̶ Eutectic GaIn interface o Good thermal contact o Weak mechanical coupling
§ Transfocators ̶ Water cooled
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High average power femtosecond pump laser
NIR OPCPA
Spatial profile
Power stability
Pulse duration Spectrum
88.5 ± 1.47W
• Tunable broadband spectrum centered at ~790nm
• Pulse durations down to 17fs
• Output power of 88.5 W at 100kHz, with efficiency of ~12% from pump
LCLS-II detector developments
High Speed Imaging ≥ 5-10 kHz
Spectroscopic ~ 0.5 eV @ 1 keV, 10 kHz
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Summary and Caveats
• LCLS-II-HE will: • Double the electron energy of the accelerator (4 to 8 GeV) and extends X-
ray energy limit from 5 keV to 12.8 keV • Install a second bypass line to deliver simultaneous soft X-ray and hard X-
ray beams at high rep-rate • A credible instrumentation plan was an essential requirement for CD-1
(and CD-0), and we created a draft plan based on the science case and community input from previous workshops – but this is not cast in stone.
• Ideas that emerge from this workshop will be essential for re-shaping and refining the instrumentation plan for LCLS-II-HE
• Inevitably, the initial scope of LCLS-II-HE instruments will be limited and likely implemented in phases. Ideas that emerge from this workshop will help to determine the priorities.
• Ideas that emerge from the workshop will also help motivate plans (and establish a case) for instrumentation that goes beyond the initial scope of LCLS-II-HE instruments.
Questions?
LCLS-II HE DOE Review, June 19-21, 2018 16
LCLS-II-HE Mission Need and Hard X-ray Capabilities
• Expanding the photon energy reach of the high repetition rate LCLS-II to beyond the current limit of 5 keV to access structure and dynamics at the atomic scale (i.e., in the 1Å region).
• Providing a ~1,000-fold increase in average spectral brightness (spatially and temporally coherent x-ray power) over any existing hard x-ray source, exploiting self-seeding developed at LCLS.
• Delivering spatial coherence to achieve ~1,000-fold increase in average coherent x-ray power (coherent ph/s/0.1% BW) beyond any existing hard x-ray source or proposed diffraction-limited storage ring (DLSR).
• Delivering temporal coherence to achieve >300-fold increase in average spectral flux (ph/s/meV) via self-seeding beyond any existing hard x-ray source or proposed DLSR.
• Generating ultrafast hard x-ray pulses in a uniform (or programmable) time structure at a repetition rate of up to 1 MHz.
LCLS-II-HE Mission Need Statement,
Approved Dec 2016
https://slacspace.slac.stanford.edu/sites/reviews/lclsiihe/cdr/LCLS-II-HE CD-0 MNS.pdf. 17
LCLS-II HE Project KPPs
KPPs proposed in the LCLS-II HE Conceptual Design Report
Performance Measure Threshold Objective
Superconducting linac electron energy 7 GeV 8 GeV
Electron bunch repetition rate in linac 93 kHz 929 kHz
Charge per bunch in SC- linac 0.02 nC 0.1 nC
Photon energy range 200 – 8,000 eV 200 to ≥ 12,800 eV
High rep-rate-capable HXR end stations ≥ 3 ≥ 5
FEL photon quantity (10-3 BW) 5×108 (50× spont. @ 8 keV)> 1011 @ 8 keV (200 µJ)
or > 1010 @ 12.8 keV (20 µJ)
Proposed Changes to the KPP listed in the Federal Project Data Sheet • ≥ 12,800 ev: Project goal is to achieve “greater than or equal to” 12.8 keV • >1010 photons @ 12.8 keV: Pulse energy at this photon energy is limited by
emittance and FEL performance
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HXR Self-Seeding
• LCLS operates with Hard X-ray Self-seeding over the range of 4 ~ 10 keV at 120 Hz
• LCLS-II will modify the system to operate over 4 ~ 12 keV at 120 Hz from the CuRF linac
• LCLS-II-HE will implement high rate self seeding between 4 and >9 keV
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