1. Multiplexing of LCLS II SXR beamlines using a canted undulator concept
J. Krzywinski

2. Acknowledgment D. Cocco F.J. Decker A. Lutman G. Marcus A. Marinelli
H.D. Nuhn
J. Turner
I would like to thank J. Hasting, R. Schoenlein, T. Raubenheimer, A. Busse, L. Zhang, J. Welch, Z. Huang, W. Schlotter and Jo Stohr for helpful discussions and comments.

3. Layout
Background
Canted undulator concept aka ‘FJD multipole FELs’
LCLS II beam line multiplexing concept
Expected FEL performance
Reference to LCLS II plans
Summary

4. Our Challenge: How to optimize space use– especially in the Near Experiment Hall (NEH)
FEL Beam
FEL Beam
AMO
SXR
XPP
Curtesy D. Fritz 4

5. Pre-conceptual design: LCLS II FEE Configuration
SXU: Bendable Mirror
0.25 – 1.2 keV
NEH 2.1, NEH 2.2
SXU: Monochromator
0.25 – 1.2 keV
NEH 2.1, NEH 2.2
SXU: Bendable Mirror
0.25 – 1.2 keV
NEH 2.1
NEH 2.1
NEH 2.2
SXU: Flat Mirror
keV
NEH 1.2
NEH 1.1
NEH 1.2
SXU: Flat Mirror
0.4 – 2.5 keV
NEH 1.2
XPP
FEH
HXU: Flat Mirror
2.5 – 25 keV
XPP, XCS, MFX, CXI, MEC
HXU: Flat Mirror
1 – 6 keV
NEH 1.2
HXU: Flat Mirror
keV
NEH 1.2, XPP, XCS, MFX, CXI, MEC
Curtesy D. Fritz

6. Instrument Layout for LCLS-II
NEH 1.1
High Flux Soft X-ray
250 – 2000 eV
3 μm / 200 nm
Minimal Optics
NEH 1.2
Tender X-ray Instrument
400 – 6000 eV
1 μm
2x XFELs
NEH 2.1
RIXS
250 – 1200 eV
2 x 10 μm
Up to 30,000 resolving power
NEH 2.2
250 – 1200 eV
5 μm
1, ,000 resolving power
Curtesy D. Fritz

7. Can we increase the scientific capacity further?

8. Canted undulator concept aka FJD Multiple FELs*
Non-kicked beam
Kicked beam
F.-J. Decker, P. Emma, J. Frisch, K. Horovitz, Z. Huang, R. Iverson, J. Krzywinski, H. Loos, S. Moeller, H.-D. Nuhn, J. L. Turner, J. Welch, J. Wu, “Multiple FELs from the one LCLS undulator”
Proceedings of FEL2011, Shanghai, China

9. LCLS II beam line multiplexing concept
Fast kicker kicks every second bunch with 100 kHz rate
beams with different colors can be send
into two separate beamlines

10. LCLS-II SXR and HXR Component Layouts
Curtesy H.D. Nuhn

11. Expected performance of the canted undulator scheme at 300 pC derived from Gabe’s S2E simulations

12. Reality check

13. Separation of the beams must be large enough to avoid beam truncation (> 20 mm for the concept sketched above)
Separation of the beams must be large enough to accommodate optics ’ bulky mechanical and cooling system

14. Pointing the FEL
The segments of the FEL can be pointed by moving the quads
The maximum displacement for the baseline design is the sum of physical displacement + motion of the quad center with correctors
is ~ +/- 1.2mm
The length of the undulator is ~ 100 m:
The maximum separation angle is ~ 100 microradians
The distance of the first mirror from the center of the undulator is ~ 100 m
The separation of the beams at the first mirror is ~ 10 mm
Meeting, Date

15. Current conceptual design

16. Modified concept

17. Considered operational modes: NEH 1.1 - NEH 1.2
Baseline

18. Considered operational modes: NEH 1.1 - NEH 2.2

19. Considered operational modes: NEH 1.1 - NEH 2.1

20. Considered operational modes: NEH 1.2 - NEH 2.1

21. Considered operational modes: NEH 1.2 - NEH 2.2

22. Considered operational modes: NEH 2.1 - NEH 2.2

23. Practical issue - impact of the monochromator design
The high resolution monochromator
requires a very stable, large support system which will likely reduce the number of the operation modes
Option I
Option II

24. Comments to operational modes
This is at the concept development stage.
A future detailed study and a serious engineering effort is required to evaluate the available space for the optics.
Most likely, not all operational modes presented above will be realized in practice.
Probable operational modes depending on the monochromator design:
The most obvious impact has to do with the handling of two beams that are separated by about 10 mm in the XTES location. BCS and differential pumping systems need to accommodate larger stay clear requirements. In addition, there will be a change in the direction of the incoming photon beams with respect to the current design.
Option I
Option II
NEH NEH 2.1
questionable OK
NEH NEH 2.2
NEH NEH 2.1
 questionable
NEH NEH 2.2
NEH NEH 2.2
 OK
NEH NEH 1.2

25. Summary
We have proposed a canted undulator scheme which can enable multiplexing of SXR beams of different colors at LCLS II and increase the scientific capacity of LCLS II.
The scheme will preserve the operational modes that are in the current plans.
S2E simulations show that, depending on the photon energy and electron bunch charge, it is possible to produce two photon beams with pulse energies between 2 mJ and 10 mJ in the photon energy range 400 eV eV, the range which is most interesting from the scientific point of view.
Addition of 4 undulator modules can increase the pulse energy range to 100 mJ at eV.
The obvious impact on the current baseline design is on differential pumping and BCS.
This presents the concept for evaluation and for the study of feasibility and the impact on the LCLS II baseline.

26. Thank you for your attention!