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Diamond II: machine studies

Diamond II: machine studies. R. Bartolini Diamond Light Source and John Adams Institute, University of Oxford. LER16 workshop SOLEIL 26 October 2016. Strategy and constraints. Wishlist for the Diamond II upgrade emittance reduced to 270 pm at least ( a factor 10 better than now )

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Diamond II: machine studies

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  1. Diamond II: machine studies R. Bartolini Diamond Light Source and John Adams Institute, University of Oxford LER16 workshop SOLEIL 26 October 2016

  2. Strategy and constraints Wishlist for the Diamond II upgrade • emittance reduced to 270 pm at least (a factor 10 better than now) • minimal changes to the machine reuse tunnel and beamlines as they are (no offset or angle) leave the straight sections as they are reuse hardware if possible (magnets, RF, etc) • maintain I09-I13 optics • maintain short pulse capabilities (low-alpha) • avoid long interruptions find options that can be phased • minimise technology risks LER16 workshop SOLEIL 26 October 2016

  3. Outline • Lattice designs and relative merits of MBA (M = 4,5,6,7) x10 reduction in emittance + double #beamlines 4BA 270 pm (aka DDBA) first consultation with PBSs  more aggressive designs x20 reduction in emittance 6BA 120 pm (aka DTBA) modified ESRF cell + double #beamlines best of both DDBA and ESRF 7BA • Source properties ID Hard X-rays, ID Soft X-rays, wiggler bending • Onoging work and conclusions LER16 workshop SOLEIL 26 October 2016

  4. Modified 4BA – 270 pm It transpired that a 4BA cell can be modified to introduce an additional straight in the middle of an arc while keeping the emittance small. This lattice originated the modification of the existing cell2 to a DDBA cell It is been the baseline design for Diamond II until end 2015 LER16 workshop SOLEIL 26 October 2016

  5. One DDBA cell in the existing lattice One DDBA cell is going to be installed in the existing lattice in order to have one more beamline (no significant gain in emittance)

  6. Girder 1 installed (24/10/2016)

  7. Initial studies on modified 6BA design proved difficult (a simple scaling of TBA doubling the number of cells did not work) Collaboration with ESRF: Use the ESRF cell concept (7BA with longitudinal gradient dipoles) – removing the mid dipole to make it a 6BA with a straight at the centre modified 6BA lattice – 100/140 pm This design is promising! First analysis shows it is as good as the 4BA Longitudinal gradient dipoles + strong gradient dipole (up to 1.4 T 40 T/m) ~3 m mid-straight section ~2mm bunch length work in progress!

  8. Tailoring cell design to diamond specific features The present work is concentrating on providing the 6-fold symmetry of diamond short straigth sections ~5m long straight sections ~8 m Mid-straight section ~3 m Large beta x for injection under investigation I09-I13 double minibeta sections to be included Ditto for I21 stronger focussing sections Cell variants specific to Diamond design

  9. One superperiod Existing ring emittance [pm] 2700 pm natChrom H/V -54/-90 tune H/V 27.20/13.36 momCompaction 1.7e-04 bunchLength 3 mm Main Ring Parameters emittance [pm] 122 pm natChrom H/V -79/-123 tune H/V 57.20/20.30 momCompaction 1.1e-04 bunchLength 2.4 mm

  10. Cell optimisation Linear  Nonlinear optimisation Following the ESRF approach we make a thorough scan of the linear optics that provides the best DA and MA (for a fixed chromaticity) MOGA will follow (WIP)

  11. Momentum aperture providing 3.25 h with 300 mA 900 bunches 1% coupling Cell optimisation tLife: 3.25h; further optimisation underway HHC cavities for bunch lengthening will be necessary to increase the Touschek lifetime With a DA of 11 mm and a lifetime of 3.2h the DTBA is a promising candidate for Diamond II. Most of the design effort is concentrating on this lattice LER16 workshop SOLEIL 26 October 2016

  12. Varying betax at injection straight Injection cell optimisation LER16 workshop SOLEIL 26 October 2016

  13. Dealing with beamlines LER16 workshop SOLEIL 26 October 2016

  14. electron beam sizes and photon phase space at 1A The electron beam brightness is improved by nearly a factor of 25. Diamond Diamond-II

  15. Brightness improvement with Diamond-II (120pm): Hard X-rays undulator CPMU 300 mA 1%K 116 periods 2 m long with Kmax = 1.86 Soft X-rays undulators APPLE-II for I05, I06, I08, J09, I10 and I21 LER16 workshop SOLEIL 26 October 2016

  16. Coherent fraction improvement with Diamond-II (120pm): Transverse coherence fraction with respect to present operation The improvement in brightness/coherence is approximately a factor of x3 at 100 eV and x10 at 1 keV, the main benefit coming from the reduction in horizontal source size and divergence LER16 workshop SOLEIL 26 October 2016

  17. Flux through an aperture Flux through a 40 rad * 40 rad aperture for the Diamond CMPU in the existing ring (red) and in Diamond-II (black). LER16 workshop SOLEIL 26 October 2016

  18. Wigglers and bending magnets Bend magnet spectral flux for 0.8T (diamond II) and 1.4T (diamond) I12 4.2 T wiggler spectral flux (red diamond - black diamond II) LER16 workshop SOLEIL 26 October 2016

  19. I09-I13 vertical double minibeta and horizontal focussing optics difficult to maintain in 8 m straight section however these are “flagship beamlines” at Diamond I13 is ~200 m long to an external building Few other beamlines cannot be maintained as they are in the shorter straights I10 polarisation switching with 5 kickers – does not fit in 5.2 m I08 4.5 m ID is too long I06 2 * 2.1 m APPLE-II plus phase units is too long Bending magnet source very likely they will be all replaced in the additional straight sections B22 IR/THz radiation extraction from smaller pipe Strong interest in maintain some kind of time-resolved capability Open problems LER16 workshop SOLEIL 26 October 2016

  20. I13 is a flagship beamline: coherence and imaging LER16 workshop SOLEIL 26 October 2016

  21. Double minibeta optics Length Q-Q: 3.66 m but likely to be reduced due to strong quadrupoles >100 T/m work in progress LER16 workshop SOLEIL 26 October 2016

  22. BM Critical energy DLS-II 0.8 T  4 keV from 8.4 keV at DLS Broadband at least x3 critical energy DLS-II < 12 keV from ~25 keV at DLS Brightness/flux better aspect ratio DLS dipole (@ centre) 37 m H 25 m V DLSII dipole  sqrt(23) ~7.7 m H ~5.2 m V divergence dominated by 1/ = 170 urad flux decrease with critical energy penalizes strongly the hard X-rays bending beamlines Dipole beamlines in Diamond II MBA choice for bending PBSs: Most bending beamlines PBSs (7 bendings beamlines) expressed a clear preference for even-BA lattice option that will allow the flexibility of upgrading their source to an undulator or a wiggler or a 2PW or a 3PW if they wish

  23. Combining harmonic cavities at 1.5 GHz and 1.75 GHz to store simultaneously long and short pulses – SC RF Time resolved science via Variable pulse length SR - VSR From Bessy VSR CDR and A. Jankowiak private communications

  24. Initial consideration on layout, engineering integration, girders, beamline layout, etc. Design and Layout

  25. Diamond II design is striving to combine low emittanceanddoubling the straight sections The additional flexibility has so far paid off in winning the support of most bending beamlines and can be further used e.g. more beamlines proper additional RF (e.g. 100 MHz, HC or VSR HC) damping wigglers DTBA Lattice design promises to reach 120 pm emittance with conventional off axis injection. Need to asses the effect of reduced straight sections length Possible new directions: VSR-type of concepts Open for collaboration with interested AP-technology Groups (beyond DLS/JAI/ESRF) Conclusions

  26. R.P. Walker, P. Raimondi (ESRF) and A. Alekou (JAI/DLS), T. Pulampong (former JAI now DLS), S. Liuzzo (ESRF), N. Carmignani (ESRF) J. Zegenhagen, G. Evans, K. Sawnhey, G. Cinque, A. Day, N. Hammond, J. Kay Acknowledgments Thank you for your attention ! LER16 workshop SOLEIL 26 October 2016

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