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Low Emittance Rings Workshop, Oxford, UK July 8, 2013

Low Emittance Rings Workshop, Oxford, UK July 8, 2013. ALS Brightness Upgrade & Future Plan H. Tarawneh , C. Steier , A. Madur , D. Robin Lawrence Berkeley National Laboratory.

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Low Emittance Rings Workshop, Oxford, UK July 8, 2013

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  1. Low Emittance Rings Workshop, Oxford, UK July 8, 2013 ALS Brightness Upgrade & Future Plan H. Tarawneh, C. Steier, A. Madur, D. Robin Lawrence Berkeley National Laboratory • B. Bailey, A. Biocca, A. Black, K. Berg, D. Colomb, N. Li, S Marks, H. Nishimura, E. Norum, C. Pappas, G. Portmann, S. Prestemon, A. Rawlins, D. Robin, S. Rossi, F. Sannibale, T. Scarvie, R. Schlueter, C. Sun, W. Wan, E. Williams.

  2. Outline • Introduction - ALS Upgrades • Brightness Upgrade • Lattice Choice • Magnet Design • Installation/Commissioning • Future directions (ALS-II) - Pre-conceptual: Lattice, Magnets, Injection. • Summary 2

  3. Brightness Upgrade • ALS for 20 years has been extremely successful in (soft) x-ray science and newer Facilities could provide potentially better performance and better tools • Brightness Upgrade Scope: • Replacement of the current 46 dipole corrector magnets with 48 combined function magnets (sextupole+HCM+VCM+skew), as well as associated power supplies, controls, interlocks, chamber modifications • Project Schedule: • - Magnet RFP 6/2010 • Magnet Installation 10/2012-3/2013 • Migration to low emittance 4/2013 SuperbendSourcepoints 68 microns (FWHM) 223 microns (FWHM) 3

  4. Why do we add sextupoles? • Reducing the equilibrium emittance is achieved changing settings of existing quadrupoles • Problem is nonlinear dynamics: • Sextupoles are too weak to correct chromaticity • Strengthening them would dramatically reduce dynamic aperture (lifetime, injection efficiency) • Need additional degrees of freedom • ‘Harmonic’ Sextupoles • ALS lattice already full – needed to replace existing corrector magnets with multi-magnets • Possibility for low alpha operation • THz, short bunches 4

  5. Lattices for ALS upgrade Current Lattice New Small bx Lattice New Large bx Lattice • There are several possible lattices with ~2 nm rad emittance • 3x smaller than the nominal ALS (~6.3 nmrad) • Large bx lattice optimizes brightness for the central bends • Small bx lattice would optimize brightness for the insertion devices further 5

  6. Baseline Lattice: Dynamic Aperture • Dynamic aperture is fairly large (larger than current lattice) • Dynamic Momentum Aperture larger • TouschekLifetime longer than present lattice • Despite higher density 6

  7. Project History Existing Correctors • Received funding (summer 09) • Comprehensive project review (12/09) • Awarded magnet contract (9/10) • Detailed magnet design review (3/11) • Prototypes of 3 magnet types complete (12/11) • First set of 13 production magnets shipped (4/12) • All magnets received (8/12) • Pre-Installed 13 of 48 sextupoles(1/13) • Remaining magnets and power supplies installed (3/13) • User operation in high brightness mode (2.0 nm emittance) – since (4/13) Sextupole / Corrector Multimagnets 7

  8. Accelerator Physics Work • Top-off calculations with new magnets • Re-analysis necessary, new field profiles • No hardware changes necessary • Wider ranges on topoff interlocks • New fs-slicing bump for new lattice • Using MOGA optimization techniques • Making use of new skew quadrupoles • Also evaluating to switch to horizontal slicing • Shorter pulses • Supporting analysis of magnet test results – Reducing Commissioning Risk • Hysteresis • Bandwidth • Multipolecontent • Continuing work to explore low bx lattices 8

  9. Commissioning Results • Installation completed on time (Mar/Apr 2013) • Quick Commissioning Progress • Benefit of pre-installation and commissioning: orbit feedbacks, detuned upgrade lattice • Managed to deliver low emittance beam during BLC shifts – and continue into user operations • 3 months ahead of schedule • Beamlines able to resolve brightness increase • Reliable operation (no faults due to new lattice or hardware so far) Measured horizontal photon beam profiles showing the reduction in size and increase in brightness. Above: BL 12.3.2, Below: BL 6.3.1 9

  10. Beamsize and Beam Dynamics Measurements Beamsize Reduction BL 6.3.1 BL 6.3.1 Confirmed larger dynamic and momentum aperture than high emittance lattice 10

  11. Brightness Comparison • Comparison to existing and future light sources (and upgrades) • Below 1 keV (soft x-ray) ALS is competitive now • Future: NSLS-II and Max-4 will outperform ALS above 100 eV Triple Bend Achromat provides very bright bend and Superbend source points from center bend magnets – ALS (2 nm) above NSLS-II 3PW 11

  12. Looking beyond completed Brightness Upgrade: Assuring world class capabilities for the future Diffraction Limit upgrade on a 200m circumference ring enables nanoscale microscopes with chemical, magnetic, and electronic resolution new magnets old magnets Chemical Maps Potential upgrade of ALS ring to diffraction limit From 20 nm to 2 nm; from 2D to 3D Resolve nano-interfaces in a cathode Observe the flux in a catalytic network Electronic Maps nanoARPES of complex phases at 25 nm resolution angle Magnetic Maps Thermally-driven domain fluctuations imprinted in speckle at nm resolution 100x increase in brightness 13

  13. Diffraction Limited Light Sources • Recent realization: Still large potential for storage ring sources • Smaller vacuum+magnet aperture – Multi bend achromat lattices with low emittance. • Actively pursued: MAX-IV, SIRIUS, ESRF-2, Spring8-2, BAPS, … • Transverse diffraction limited to 2 keV for ALS size is possible – ALS-II • Using the ALS tunnel to achieve moderate low emittance with moderate cost.

  14. Ongoing Conceptual Machine Design Work Active Areas of Conceptual Machine Design: • Lattice Optimization • Injection • Collective Effects • Engineering Considerations (Magnets-DC/pulsed, RF, Vacuum) • Cost/Schedule

  15. ALS-II Magnet System • Third generation light sources = generous physical apertures (except for IDs which define much smaller admittance) – smaller apertures (factor 3) = much stronger magnets • Nowadays field quality with smaller magnet apertures achievable • MBA lattices provide smaller natural emittances • NEG coating - distributed pumping in small chambers (cheaper) 0.78 T & 50 T/m Pole Tip Flux: 1.0 T 80 T/m Pole Tip Flux: 0.9 T 3000 T/m2 Pole Tip Flux 0.45T

  16. ALS-II Injection Scheme • On-axis injection into SR due to small DA Accumulator Ring (AC). • Accumulator ring shares the SR tunnel. • AC Lattice Req. (a) DA of ±10 mm. (b) Lifetime ≥2 h. (c) Minimum 4 Straight sections. • Partial Swap-out injection is foreseen • Relax requirements on AC ring & pulsed magnets, I=100 mA Bunch Trains Storage Ring Injected train Stored train Stored train Accumulator Ring Brightness evolution injecting 0.1*Ibeam

  17. Summary • Biggest challenge (as well as opportunity) for ALS – Continuous Renewal • Well balanced plan between machine/facilities upgrades and beamline/endstation renewal • Major Machine Renewal example: Brightness upgrade reduced horizontal emittance from 6.3 to 2.0 nm • Beamlines can resolve brightness increase and realize (full) benefit • Dramatic performance improvements beyond ALS are possible (at moderate cost) and are now being actively studied. 18

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