NSLS II: Accelerator System Overview NSLS II Accelerator Systems Advisory Committee

1. NSLS II: Accelerator System Overview NSLS II Accelerator Systems Advisory Committee October 10, 2006 Satoshi Ozaki

2. Introduction • NSLS II: A highly optimized, third generation, medium energy storage ring for the x-ray synchrotron radiation: • The CD-0 approval articulated required capabilities as: • ~ 1 nm spatial resolution, • ~ 0.1 meV energy resolution, and • single atom sensitivity (or sufficiently high brightness). • These requirements translate into the target parameters of the storage ring as; • ~3 GeV, 500 mA, top-up injection • Brightness ~ 7x1021 photons/sec/0.1%bw/mm2/mrad2 • Flux ~ 1016 photons/sec/0.1%bw • Ultra-low emittance (x, y): 1 nm horizontal, ~0.01 nm vertical •  20 straight sections for insertion devices ( 5 m), • A high level of reliability and stability of operation.

3. Milestone Schedule

4. Steps in the Baseline Configuration Development • The original lattice for CD0 proposal was TBA24 with tight bend and 630 meter circumference. • Although the desired small emittance (x~1.5 nm) was thought to be within reach with the perfect lattice, it was found that any reasonable errors would have closed up the dynamic aperture. • Search of an alternative: • Enlarged TBA24 lattice • DBA lattice with more straights for damping wigglers for emittance control. • Weak bends to enhance damping by wigglers. • CD0 proposal also included a full energy linac injector. • A booster in the storage ring tunnel was chosen for this baseline configuration with due consideration of reliability, performance and cost.

5. Parametric Comparison of Lattice

6. The Preliminary Review of NSLS II Lattice and Accelerator Configuration: May 11-12, 2006 The Committee : • Dr. Carlo Bocchetta, Sincrotrone Trieste • Dr. Michael Boege, Swiss Light Source • Dr. Michael Borland, Argonne National Laboratory • Dr. Max Cornacchia, Stanford Linear Accelerator Center (retired), Chairman • Dr. Mikael Eriksson, MAXLAB • Dr. Thomas Roser, Brookhaven National Laboratory • Dr. Christoph Steier, Lawrence Berkeley National Laboratory The approach of NSLS II is to achieve the performance goal • with a lattice whose focussing strength is comparable to that of existing 3-rd generation sources, but that also includes a number of damping wigglers to further reduce the emittance without the deleterious effect on the dynamic aperture normally associated with strong focussing lattices. • Thus, the proposed design includes innovative ideas for a light source (damping wigglers and soft bends), informed by the experience of state-of-the-art existing facilities. • While the design presents challenges for the beam dynamics, beam instrumentation, controls and hardware, the performance goals appear achievable.

7. DBA 30 and Its Expected Performances • 3 GeV, 500 mA, top-up injection • Fifteen Superperiod consisting of two identical cells • Fifteen 8-m long straights and 15 5-m long straights • min,x /min,y @ 8-m straight = 18.2 m/3.1 m (Hi-) • min,x /min,y @ 5-m straight = 2.7 m/0.95 m (Lo-) • Bare Lattice: x ~2.1 nm, y ~0.008 nm (Diffraction limited at 12 keV) • Pulse Length (rms): 2.9 mm/~10 psec • Ultimate performance with full complement (56m 1.8T) of wigglers • Emittance (x, y): ~0.5, ~0.008 nm • Flux ~ 1016 photons/sec/0.1%bw • Brightness ~ 7x1021 photons/sec/0.1%bw/mm2/mrad2 • 19 user device (e.g., undulators) straights (15 x 5 m & 4 x 8 m) • 5 user compatible (fixed gap) damping wigglers • Beam Size (x/ y) at the center of short straights: ~38.5/~3.1 m • Beam Divergence (x’/y’) ~18.2/~1.8  rad • Pulse Length (rms) with damping wigglers: 4.5 mm/~15 psec • Ultimate total power loss by bending magnets and insertion devices: ~1 MW • Initial scope and performance is reduced to fit in the budget constraint, while maintaining the upgrade path.

8. Renderingof the NSLS II Ring (Rear View)

9. Booster Storage Ring Linac Accelerator System Configuration Booster Booster injection was chosen for a high level of reliability Since we operate with top-up mode, having the booster in the same tunnel will have little impact on the operational reliability

10. Injector Linac • S-band linac system providing 200 MeV electron beams of 7 nC to the Booster in one pulse • Electron source: thermionic DC gun modulated to match 500 MHz RF of booster and storage ring • The system commercially available in turn-key procurement: • ACCEL • THALES • Issue: control of energy droop causes by beam loading

11. Injector Linac Parameters

12. Booster Synchrotron • 200 MeV to 3 GeV booster • Hung below the ceiling of the storage ring tunnel and has the same circumference of 780 m • Relatively light weight small magnets; low power and air cooled: • 60 combined function dipoles: 1.5 m long, 25 mm gap, 0.7 T, ~580 kg • 96 quadrupoles: 0.3 m long, <10T/m, ~45 kg • 15 sextupoles: 0.4 m long, <200T/m2, ~55 kg • 15 sextupoles: 0.2 m long, <200T/m2,~30 kg • 60 orbit correctors • Up to 100 bunches per cycle for initial fill • Up to 20 bunches per cycle with the hunt and fill bunch pattern • One PETRA-type (commercially available) RF cavity • Very low emittance at the storage injection energy helps smooth low loss top-up injection. • Procure components, build, and commission in-house • Options: turn-key procurement of this booster or a compact booster in separate tunnel • Detailed discussion on Injection system by Timur Shaftan on the second day.

13. Booster Ring Parameters

14. Booster Lattice and its Relationship with Storage Ring

15. Storage Ring Lattice Layout Linac RF Station

16. Storage Ring • DBA30 lattice with 15 super-periods, each ~52m long, and 780m circumference • Super-period: two identical cell separated by alternating ~5m and ~8m straights • Weak bends (0.4T) with damping wigglers to achieve ultra-small emittance (~0.5 nm with 56 m of 1.8T wigglers) • Short straight: x = 2.7m, y = 0.95m, and dispersion = zero • Long straight: x = 18.2m, y = 3.1m, and dispersion = zero • This Hi-Lo  is suited for variety of ID as well as top-off injection • Utilization of straights and bending magnets • 1 long straight for injection with 4 kicker magnets • 2 long straights for fundamental and harmonic RF cavities • Up to 8 long straights for damping wigglers in the ultimate configuration • Five of them with fixed gap, being suitable for user beamlines • 4 long straights for user insertion devices. • 15 Short straight for user undulators, some with canting • A number of bending magnet for soft X-ray beam lines (critical energy ~2.4 keV) • Several bending magnets for IR, far-IR, and THz beamlines • Variable gap wigglers to compensate the change of undulator setting by users

17. Lattice functions of half of an NSLS-II SR super-period (one cell).

18. Dispersion Section of a Cell Alignment tolerance of multipoles on a girder is 30 m, whereas girder-to-girder tolerance is ~100 m In order to reduce the transmission of ground vibrations beam height is set at 1 m from the SR tunnel floor, instead of standard 1.4 m. Girder Resonant Frequency > 50 Hz

19. Dynamic Aperture of the Lattice For on momentum and off momentum cases by 3%

20. Horizontal Emittance vs. Energy Radiated by DW Dots represent the cases with 0, 1, 2, 3, 5, 8 damping wigglers, each 7-m long with 1.8 T field

21. RF Power Up-grade Path RF Power Requirements for Dipole and Various Insertion Device Configurations.

22. Storage Ring Parameters

23. Storage Ring Parameters (Continue)

24. Features of the Storage Ring Design • A large circumference DBA for small bare lattice emittance (~2.1 nm) • The design of the facility mostly depends on the well established technology at other storage ring light sources • Alternate Hi-Lo  straights accommodate various requirement for injection, RF, and long damping wigglers for machine, and insertion devices for users • The weak bend combined with damping wiggler reduces the horizontal emittance to sub nm level horizontal • Robust dynamic aperture (~20 mm) and wide momentum acceptance (3%) • 24 straights for the hard x-ray beam from insertion devices • A number of dipoles can be used for soft x-ray and IR beams • The level of RF power can be adjust according to the development of the facility with additional insertion devices and damping wigglers • Booster injection for better reliability • 1 meter beam height and good temperature control for better stability • Extensive array of diagnostic devices for better control of the beam

25. Issues for Further Studies • Development of precision alignment (~30 µm) technology • Development of the optimum orbit correction and feedback scheme for high level of orbit stability: • A factor of ~3 improvement over the submicron stability recently reported with some recent light sources. • Impact and remediation of 5 mm gap undulator with short pitch to the dynamic aperture and the beam life-time • Because of the vertical focusing effect of undulators with short pitch, they cannot occupy the part of the ID straight where the vertical -function is large, i.e., areas away from the center of the straight. • This limits the 5 mm gap undulator length to ~3 m. • Impact of EPU on dynamics of the beam • Use of canted insertion device • Overall value engineering efforts

26. Current Baseline Scope/Specifications • Linac: • 200 MeV S-band linac • Turn key procurement • Linac to booster transfer line with spectrometer arm • Booster: • Air cooled magnet ring, 780 m circumference • Full complement of magnets, powered in series, designed with 20% head-room • Power supply rated for 1 Hz operation • PETRA-type 500 MHz room temperature 5 cell RF cavity • In house design, procurement, construction, and commissioning • Booster to storage ring transport line

27. Current Baseline Scope/Specifications (Continue) • Storage Ring: • Water cooled storage ring, 780 m circumference • All dipole magnets with 60 mm (instead of 35 mm) for IR beam extraction • Dipoles powered in series by one power supply and multipoles and correctors by individual power supplies. • Full complement of magnets designed to allow 20% head room • Extruded aluminum vacuum chambers a la APS • Front end for damping wiggler that will accommodate high power density radiation • Scope of user insertion devices not defined, subject to the user community’s proposal. Funds for devices and beamline front end set aside as trust funds • Initial complement of damping wigglers are to be 2  7 m fixed gap and 1  7 m variable gap. However, only one of each type with 1/3 of length are budgeted. • Two 500 MHz superconducting RF cavities, CESR-B or KEK B type, with power source and a passive 2-cell harmonic cavity will be installed. One spare cavity without power source will be purchased • One refrigerator with ~700W at 4.5K will be procured (turn-key) for the RF system • Procurement of full complement of diagnostic instrumentation is included in the scope • For control system, EPICS architecture has been adopted for now, subject to change

28. High Level Project Schedule

29. Accelerator System Division Organization Began working on development of baseline configuration in January 2006 ~42 people from NSLS, C-AD, SMD: many of them on part-time base. Effective FTE for this period: ~16.5 Many people from other laboratories (APS, ALS, MIT Bates) provided help The organization anticipated for the construction effort: Accelerator Systems Division Director Deputy Director Accelerator Physics Group Injector System Sub-Project Mechanical Engineering Group* *: also support beamline efforts Storage Ring System Sub-Project Electrical Engineering Group* RF Group Insertion Devices Group Diagnostic & Controls Group

30. Synopsis of Accelerator Systems Presentations • X-ray Storage Ring V. Litvinenko • NonlinearDynamics, Tolerances, & Dynamic and Momentum Aperture J. Bengtsson • Beam Based Alignment, Beam Stability, Orbit Corrections, and Fast Feed-back S. Kramer • Collective Effects S. Krinsky • Mechanical Sub-Systems S. Sharma • Magnet Power Supplies G. Ganetis • Storage Ring Vacuum System H-C Hseuh • Storage Ring RF System J. Rose • Insertion Devices T. Tanabe • Injection System: Top-up Injection Scheme, Linac, Booster, and Beam Transfer Lines T. Shaftan Not covered: • Beam Line Front-End: Follow experience at APS. As of now, details are not defined, waiting for the determination of the suit of beamlines. • Control System: EPICS was chosen as the backbone for now, but other systems are being studied • Diagnostics: Combination of standard instrumentation is planned.

31. Summary • Made good progress in last nine months in developing CDR for NSLS II • Optimized and define the configuration of the accelerator systems • Undertook conceptual, in some case more detailed, design of accelerator systems • Assembled accelerator parameter tables • We have a innovative design of highly optimized synchrotron light source capable of meeting requirement articulated in CD-0 document with ultra-high performances • There are a number of issues requiring further study:. • Insertion devices and their impact on the dynamic aperture and beam life-time • Diagnostics and feed-back for the required highly stable beam operation • General value engineering exercise to control costs