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

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.

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

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

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 0.4-2.5 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 1 - 25 keV NEH 1.2, XPP, XCS, MFX, CXI, MEC Curtesy D. Fritz

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 - 5,000 resolving power Curtesy D. Fritz

Can we increase the scientific capacity further?

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

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

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

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

Reality check

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

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

Current conceptual design

Modified concept

Considered operational modes: NEH 1.1 - NEH 1.2 Baseline

Considered operational modes: NEH 1.1 - NEH 2.2

Considered operational modes: NEH 1.1 - NEH 2.1

Considered operational modes: NEH 1.2 - NEH 2.1

Considered operational modes: NEH 1.2 - NEH 2.2

Considered operational modes: NEH 2.1 - NEH 2.2

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

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 1.1 - NEH 2.1 questionable OK NEH 1.1 - NEH 2.2 NEH 1.2 - NEH 2.1  questionable NEH 1.2 - NEH 2.2 NEH 2.1 - NEH 2.2  OK NEH 1.1 - NEH 1.2

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- 1000 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 1000 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.

Thank you for your attention!