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NSLS II: Accelerator System Overview Project Advisory Committee October 27, 2006 Satoshi Ozaki

NSLS II: Accelerator System Overview Project Advisory Committee October 27, 2006 Satoshi Ozaki. 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:

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NSLS II: Accelerator System Overview Project Advisory Committee October 27, 2006 Satoshi Ozaki

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  1. NSLS II: Accelerator System Overview Project Advisory Committee October 27, 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. Design Concept for the Baseline Configuration • Wherever possible use conventional technology with well established experience at existing light sources or other storage rings • Use standard S-band linac, commercially available, as the pre-injector • Use booster as the injector in order to ensure the reliability • Use top-up injection mode for stable stored beam current • Place booster in the storage ring tunnel to save the cost of a separate accelerator enclosure and service building • For storage ring lattice, use DBA with 30 straight sections, 8 of them for damping wigglers for emittance reduction, 3 for accelerator services, leaving 19 for user insertion devices. • Use weak bend (0.4 T) to enhance the emittance reduction factor of damping wigglers. • Bending magnets with 2.4 keV critical energy will be used for soft X-ray and infra-red light source • Choice of insertion devices will be base on the user requirement and fund for them and their front-ends are set aside as trust funds • The boundary between the accelerator system and beam line is at the exit from ratchet wall

  4. Booster Storage Ring Linac Accelerator System Configuration Booster • NSLS II Accelerator System: • 200 MeV S-band Linac • 3 GeV 1 Hz Booster • Top-up injection once per minute • 3 GeV storage ring: 30 DBA configuration • 15 long (8 m) straight with high -function • 15 short (5 m) straight with low -function Storage Ring

  5. 3-D Model of the SR Tunnel • There are no booster magnets over the SR straight section. • The tunnel will not be too crowded due to: • Low and narrow profile of SR girders • Compact designs of the front end components • Small sizes of the booster magnets

  6. Renderingof the NSLS II Ring (Rear View)

  7. 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.

  8. 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 • Five accelerating structures with three klystrons operating at 1.3 GHz • The system commercially available in turn-key procurement: • ACCEL • THALES

  9. 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 • The lattice arranged to have no booster components above storage ring straight sections, except for one 8-m straight for RF cavity • 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. • Purchase components from industry based on our reference design, and build and commission in-house • Turn-key procurement of a compact booster in separate tunnel: an option

  10. Booster Lattice and its Relationship with Storage Ring

  11. Storage Ring Lattice Layout Linac RF Station

  12. Storage Ring Storage ring configuration • DBA30 lattice (780m circumference) with 15 super-periods, each ~52m long • Super-period: two identical cells separated by alternating 5m and 8m straights • 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 • Weak bends (0.4T) with damping wigglers to achieve ultra-small emittance • Lattice magnet: (designed with 20% head room) • Dipoles: 60 (50 with 35 mm gap and 10 with 60 mm gap for IR beams) • Quadrupoles: 360 • Sextupoles : 390 • Correctors and skew quadrupoles: 240 + (4 X ID) • 500 MHz superconducting RF cavities each operating with 270 kW power level • Harmonic number (No. of buckets): 1300, of which ~ 80% will be filled • A 2-cell harmonic cavities for bunch lengthening Bare lattice performances: • 3 GeV, 500 mA, Top-up with current stability of <1% • Bare Lattice: x ~2.1 nm, y ~0.008 nm (Diffraction limited at 12 keV) • Pulse Length without harmonic cavities (rms): 2.9 mm/~10 psec • Robust dynamic and momentum aperture: ≥25 mm H, ≥15 V, ~±3%

  13. 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

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

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

  16. 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

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

  18. Ultimate Configuration and Performances Ultimate Configuration: • 8 damping wigglers (7 m long, 1.8T peak field) • 4 RF cavities with 1,080 kW of RF power Expected performances at 3 GeV: • Beam current: 500 mA • Emittance: x ~ 0.5 nm, y ~ 0.008 nm • Flux ~ 1016 photons/sec/0.1%bw • Brightness ~ 1021 photons/sec/0.1%bw/mm2/mrad2 • 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 • 19 user device (e.g., undulators) straights (15 x 5 m & 4 x 8 m) • 4 long straights for large gap user insertion devices • 15 short straight for user undulators, some with canting • 8 user compatible (fixed gap) damping wigglers • Many bending magnets for soft X-ray beam lines (critical energy ~2.4 keV) • Up to 5 bending magnets for IR, far-IR, and THz beamlines

  19. Baseline Configuration & Performances Proposed baseline (CDR): • 3 damping wigglers (7 m long, 1.8T peak field) • 2 RF cavities with 540 kW of RF power • 5 user beamlines (supported by trust funds) Expected performances at 3 GeV: • Beam current: step-by-step increase to 500 mA • Emittance: x ~ 1 nm, y ~ 0.008 nm • Flux ~ 1016 photons/sec/0.1%bw ? • Brightness ~ 7x1020 photons/sec/0.1%bw/mm2/mrad2 ? • Beam Size (x/ y) at the center of short straights: ~54.5/~3.1 m ? • Beam Divergence (x’/y’) ~25.7/~1.8  rad ? • Pulse Length (rms) with damping wigglers: 4.5 mm/~15 psec ? • No. of DW that can be used for light source: 3 • Max number of ID beam lines: ~10 (e.g., 6 CPMU [3 m] and 4 EPU [4 m]) • A number of bending magnets for soft X-ray beam lines (EC ~2.4 keV) • No. of IR beams from wide gap dipoles:  5

  20. Issues for Further Studies • Development of precision alignment (~30 µm) technology • Development of the optimum orbit correction and feedback scheme for high level 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

  21. 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 *: also support beamline efforts Accelerator Physics Group Injector System Sub-Project Mechanical Engineering Group* Electrical Engineering Group* Storage Ring System Sub-Project RF Group Diagnostic & Controls Group Insertion Devices Group

  22. 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

  23. Parametric Comparison of Lattice

  24. Injector Linac Parameters

  25. Booster Ring Parameters

  26. Storage Ring Parameters

  27. Storage Ring Parameters (Continue)

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