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Diamond upgrade

This workshop discusses the motivation and vision for the Diamond upgrade, including low emittance options, optics challenges, and future improvements in stability, current, and straight sections.

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Diamond upgrade

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  1. Diamond upgrade R. Bartolini Diamond Light Source and John Adams Institute for Accelerator Science University of Oxford Advanced Optics Workshop CERN, 5 February 2015

  2. Outline • Motivation and 10-years vision • low emittance options • MBA • DDBA • Optics challenges • Conclusions Advanced Optics Workshop CERN, 5 February 2015

  3. Diamond operates since 2007 with nominal parameters • 2.7 nm H emittance (top of the league in 2007) • 300 mA • 8pm V emittance (since 2010) However: • 2010 Petra-III was commissioned  1 nm H emittance • 2011-12 SLS and ASP ~1 pm V emittance (best achieved) • 2012 ESRF et al. operate with 8pm V emittance or less • 2013 ALS upgraded to a 2 nm H emittance lattice • 2014 NSLS-II started operation  0.5 nm H emittance • 2014 Petra III has tested a 160 pm lattice at 3GeV • 2016 MAX IV 300 pm H emittance lattice • 2019 ESRF II 140 pm H emittance lattice Motivations Advanced Optics Workshop CERN, 5 February 2015

  4. 10 years vision @ Diamond • Stability improvements over 1-1kHz • IDs development (CPMU, Superconducting undulators) • Higher current and collective effects • Short pulses • Tailored straight sections – broken symmetry • Lower emittance for diffraction limited rings Advanced Optics Workshop CERN, 5 February 2015

  5. Survey of low emittance lattices Advanced Optics Workshop CERN, 5 February 2015

  6. Lattice design at Diamond Original DBA 7BA DA achieved (WIP) 7BA DA 1 mm 5BA DA 3.5 mm 4BA DA 5 mm 7BA lattice 45 pm 5BA lattice 140 pm 4BA lattice 270 pm Nonlinear dynamics Fourth order and detuning terms very harder to compensate Not enough freedom to set the cell phase advance as needed 7BA 45 pm  90 pm @ 300 mA relative increase 100% 5BA 140 pm  180 pm @ 300 mA relative increase 30% 4BA 270 pm  280 pm @ 300 mA relative increase 5% IBS emittance

  7. IBS emittance increase IBS emittance blow-up as a function of stored current coupling 10% 900 bunches – computed with elegant 4BA H emittance 5BA H emittance 7BA H emittance 300 mA 300 mA 300 mA 4BA lattice 265 pm  280 pm @ 300 mA relative increase 5% 5BA lattice 140 pm  180 pm @ 300 mA relative increase 30% 7BA lattice 45 pm  90 pm @ 300 mA relative increase 100% Advanced Optics Workshop CERN, 5 February 2015

  8. A 5BA lattice for Diamond-II upgrade A 140pm lattice for a ~20-fold decrease in emittance DA 3.5 mm preliminary studies – not bad for the amount of work done on 5BA Advanced Optics Workshop CERN, 5 February 2015

  9. A modified 4BA (DDBA) lattice for Diamond-II This lattice combines low emittance with doubling the capacity of the ring DLS will produce a Conceptual Design report for Diamond II ~2016 The modified 4BA is a strong candidate Advanced Optics Workshop CERN, 5 February 2015

  10. One superperiod for Diamond-II Advanced Optics Workshop CERN, 5 February 2015

  11. Issues with cell design Original DBA H phase advance is ~2*0.8 3m 4BA_1 3.35m 3.35m 4BA_2 3 m 3.35m 3.35m 4BA_3 3.2m 3.4m 3.35m 3.35m • Longer mid-cell straight section from 3m to 3.4 m for IDs – longer is unfeasible • Hard to control phase advance between the chromatic sextupoles • Increases dispersion at chromatic sextupoles • removed sextupoles in the new straight • Optimized magnets positions and length avoiding coil/support clashes

  12. Maintain customised optics (I09 – I13) (WIP) • introduced quadrupole doublet + additional quads in long straight sections • reduced vertical beta functions to allow two independent lines with in-vac IDs • additional horizontal focussing allows photon focus down the beamline • no other machine implemented two such customised optics Advanced Optics Workshop CERN, 5 February 2015

  13. Optimisation of beam dynamics Advanced Optics Workshop CERN, 5 February 2015

  14. Optimisation of beam dynamics Advanced Optics Workshop CERN, 5 February 2015

  15. MOGA optimisation for DA and lifetime (4BA) Nonlinear beam dynamics optimised mostly with MOGA and resonance driving terms compensation DA still under optimisation - ~5 mm (WIP) Touschek lifetime ~ 7h without harmonic cavities Advanced Optics Workshop CERN, 5 February 2015

  16. upgrade with Diamond-II (200pm): 300mA and 1%K Brilliance plot using U27 – 72 periods 2 m long with Kmax = 2.02 Tuning curves computed with Spectra 8.0 Advanced Optics Workshop CERN, 5 February 2015

  17. Lattice design at Diamond One (or more) modified 4BA cells in the present lattice (called DDBA) Advanced Optics Workshop CERN, 5 February 2015

  18. One DDBA cell in the existing lattice Replacing the existing cell2 with a DDBA cell • Introduces an additional straight section (beamline upgrade bending magnet to ID beamline) • Serves as a prototype for low emittance lattice upgrade • Lots of R&D required (magnet design challenging, vacuum with small apertures, engineering integration, etc) DDBA cell Additional straight Advanced Optics Workshop CERN, 5 February 2015

  19. One DDBA cell in the existing lattice One more beamline (no significant gain in emittance) existing DBA cell BM beamline modified DDBA cell Insertion Device ID beamline LER 2014 Workshop Frascati, 17 September 2014

  20. Ring optics with and without the DDBA cell in cell2 red = present lattice black = new lattice with modified cell2 Optics optimised with very modest perturbation to adjacent straight sections Advanced Optics Workshop CERN, 5 February 2015

  21. One DDBA: dynamic aperture and lifetime with MOGA Advanced Optics Workshop CERN, 5 February 2015

  22. DDBA DA with engineering apertures DA slightly reduced +8mm -12mm one DDBA cell +12mm – 15mm for the existing machine Injection efficiency ~93% with injection point at -6.8 mm Touschek lifetime (300 mA, 686 bunches, 1 % coupling), 16.5 h one DDBA cell 19.6 h for the existing machine

  23. Ring optics with three DDBA cells A bid for capital funds for more DDBA cells will be put forward. This will include a 3HC for bunch lengthening to be located in the third cell Advanced Optics Workshop CERN, 5 February 2015

  24. Main engineering issues • small bore quadrupoles (30 mm diameter to reach 70 T/m) • and a rather complex gradient dipole (0.8 T with 14 T/m) • All quads and all sextupoles with the same length and design • much reduced vacuum chamber in the arc • now elliptical 29 mm * 20 mm; it was octagonal 84 mm * 38 mm • initial investigation of NEG coating chamber was abandoned • too complex geometry for coating • no antechamber – systems of localised bumps to absorb radiation and cast downstream shadow • Engineering integration • standardisation of magnet lengths (one type of quads and sexts) • clashes between elements (space for coils overhang, flanges, …) • Orbit feedback based on a reduce number of fast correctors • sitting on SS vessel (avoid eddy current in copper vessel)

  25. Many light source operate with low emittance lattices. Vertical emittance in the 1-2 pm range are no longer uncommon. New projects aim at reaching diffraction limited rings in Horizontal plane as well. These are based on MBA lattices A modified 4BA for diamond is under investigation DA and Touschek lifetime studies are crucial. Magnets and apertures design will be at the cutting edge of present R&D. Collective effects (IBS) will limit the stored current to 100-200 mA. They might be mitigated by Harmonic Cavity for bunch lengthening. Round beams could help and more R&D is needed. Conclusion and open issues However the subject is now seriously tackled by a large community, some rings are already solved (e.g. PEP-X at 10 pm) and new solutions will likely appear for upcoming projects

  26. Low emittance ring community • ICFA Low Emittance Rings Workshops (LowERing) • XDL 2011 Workshops for ERLs and DLSRs, Cornell, June 2011 • Beijing USR Workshop, Huairou, October 2012 • DLSR Workshop, SPring-8, December 2012 • Low Emittance Ring Workshop, Oxford, July 2013 • SLAC DLSR Workshop, SLAC, December 2013 • Workshop on Low Emittance Rings Technology (ALERT 2014), Valencia, 2014 • Low Emittance Rings Workshop (LER2014), Frascati, September 2014 • DLSR Workshop, Argonne, November 2014 • EUCARD 2 – WP6 workshop on beam dynamics for low emittance ring • ALBA , Barcelona, 23-24 April Advanced Optics Workshop CERN, 5 February 2015

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