NSLS II Accelerator System Overview NSLS II Advisory

NSLS II: Accelerator System Overview NSLS II Advisory Committees October 18/19, 2006 Satoshi Ozaki 1 BROOKHAVEN SCIENCE

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 me. V energy resolution, and • single atom sensitivity (or sufficiently high brightness) • These and other requirements translate into the target parameters of the storage ring as; • ~3 Ge. V, 500 m. A, top-up injection • Brightness ~ 7 x 1021 photons/sec/0. 1%bw/mm 2/mrad 2 • 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 2 BROOKHAVEN SCIENCE

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

Rendering of the NSLS II Ring (Rear View) 4 BROOKHAVEN SCIENCE

Injector Linac • • S-band linac system providing 200 Me. V electron beams of 7 n. C 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 5 BROOKHAVEN SCIENCE

Booster Synchrotron • • • 200 Me. V to 3 Ge. V 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, <10 T/m, ~45 kg • 15 sextupoles: 0. 4 m long, <200 T/m 2, ~55 kg • 15 sextupoles: 0. 2 m long, <200 T/m 2, ~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 6 BROOKHAVEN SCIENCE

Booster Lattice and its Relationship with Storage Ring 7 BROOKHAVEN SCIENCE

Storage Ring Lattice Layout Linac RF Station 8 BROOKHAVEN SCIENCE

Storage Ring Storage ring configuration • DBA 30 lattice (780 m circumference) with 15 super-periods, each ~52 m long • Super-period: two identical cells separated by alternating 5 m and 8 m straights • Short straight: x = 2. 7 m, y = 0. 95 m, and dispersion = zero • Long straight: x = 18. 2 m, y = 3. 1 m, and dispersion = zero • This Hi-Lo is suited for variety of ID as well as top-off injection • Weak bends (0. 4 T) 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 k. W power level • Harmonic number (No. of buckets): 1300, of which ~ 80% will be filled • A 2 -cell harmonic cavities for bunch lengthening Basic performances: • 3 Ge. V, 500 m. A, Top-up with current stability of <1% • Bare Lattice: x ~2. 1 nm, y ~0. 008 nm (Diffraction limited at 12 ke. V) • Pulse Length (rms): 2. 9 mm/~10 psec 9 BROOKHAVEN SCIENCE

Lattice functions of half of an NSLS-II SR super-period (one cell). 10 BROOKHAVEN SCIENCE

Dispersion Section of a Cell Alignment tolerance of multipoles on a girder is 30 m, whereas girder-togirder 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 11 BROOKHAVEN SCIENCE

Dynamic Aperture of the Lattice For on momentum and off momentum cases by 3% 12 BROOKHAVEN SCIENCE

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 13 BROOKHAVEN SCIENCE

RF Power Up-grade Path RF Power Requirements for Dipole and Various Insertion Device Configurations. Covered in baseline proposal Installed RF Power (270 k. W/unit Power the 3 rd cavity with 300 k. W Transmitter Add 4 th RF station RF power # P(k. W) Dipoles - 144 Damping Wigglers (9. 23 k. W/m, 7 m each) 3 194 4 259 8 517 CPMU’s (4. 17 k. W/m, 3 m each) 3 38 6 76 10 127 EPU’s (4. 1 k. W/m, 4 m each) 2 33 4 66 5 83 ? 200 Additional Devices Total 409 545 803 1071 Available Power 540 810 1080 14 BROOKHAVEN SCIENCE

Ultimate Configuration and Performances Ultimate Configuration: • 8 damping wigglers (7 m long, 1. 8 T peak field) • 4 RF cavities with 1, 080 k. W of RF power Expected performances at 3 Ge. V: • Beam current: 500 m. A • Emittance: x ~ 0. 5 nm, y ~ 0. 008 nm • Flux ~ 1016 photons/sec/0. 1%bw • Brightness ~ 7 x 1021 photons/sec/0. 1%bw/mm 2/mrad 2 • 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 ke. V) • Up to 5 bending magnets for IR, far-IR, and THz beamlines 15 BROOKHAVEN SCIENCE

Baseline Configuration & Performances Proposed baseline (CDR): • 3 damping wigglers (7 m long, 1. 8 T peak field) • 2 RF cavities with 540 k. W of RF power • 5 user beamlines (supported by trust funds) Expected performances at 3 Ge. V: • Beam current: step-by-step increase to 500 m. A • Emittance: x ~ 1 nm, y ~ 0. 008 nm • Flux ~ 1016 photons/sec/0. 1%bw ? • Brightness ~ 4 x 1021 photons/sec/0. 1%bw/mm 2/mrad 2 ? • 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 ke. V) • No. of IR beams from wide gap dipoles: 5 16 BROOKHAVEN SCIENCE

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 17 BROOKHAVEN SCIENCE

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 design of accelerator systems, in some case more detailed • Assembled accelerator parameter tables • We have a innovative design of a highly optimized synchrotron light source capable of meeting requirements articulated in the CD-0 document with ultra-high performances • There 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 18 BROOKHAVEN SCIENCE

Injector Linac Parameters Linac Nominal/maximum linac energy (Me. V) Frequency (GHz) Number of accelerating structures Number of klystrons (no hot spare) Pulse repetition rate (pps) Beam pulse length (ns) Pulse charge (n. C) (overall charge in a macropulse) Energy spread ( %) Total number of traveling wave accelerating sections 19 200/270 2. 998 5 3 <10 1 - 80 (up to 1µs) >7 <0. 5 5 BROOKHAVEN SCIENCE

Booster Ring Parameters Booster Ring Injection energy (Me. V) Nominal top energy (Ge. V) Circumference (m) Ramping repetition rate (Hz) Acceleration time (s) Harmonic number Radio frequency (MHz) Total number of cells Number of combined function bending magnets Number of quadrupole Dipole nominal aperture (mm) Dipole field at injection (T) Dipole field at extraction at 3 Ge. V (T) Energy loss per turn at 3 Ge. V (ke. V) Beam current (m. A) Natural emittance at 3 Ge. V (nm-rad) Number of bunches 20 200 3 780 1 ~0. 4 1300 499. 46 15 60 96 25 0. 0533 0. 7 500 2. 7 11. 5 from 1 to >100 BROOKHAVEN SCIENCE

Storage Ring Parameters Storage Ring Assembly Number of DBA cells Circumference (m) Nominal energy (Ge. V) Circulating current @ 3 Ge. V, multi-bunch (m. A) Circulating current @ 3 Ge. V, single bunch (m. A) Harmonic number No. of filled bunches/harmonic number Nominal bending field @ 3 Ge. V (T) Dipole critical energy @ 3 Ge. V (Ke. V) Number of 8 m straights: [βx/βy (m)] Number of 5 m straights: [βx/βy (m)] Number of dipoles Number of quadrupoles Number of sextupoles Number of correctors and scew 21 30 780 3 500 0. 5 1300 80% 0. 4 2. 4 15: [18. 15/3. 09] 15: [2. 72/0. 945] 60 390 240 + (4 X ID) BROOKHAVEN SCIENCE

Storage Ring Parameters (Continue) Damping Wigglers Initial number of 7 m damping wigglers 2 Fixed +1 Vari Final number of 7 m damping wigglers 5 Fixed +3 Vari Max. peak field (T) 1. 8 Radiation energy loss per wiggler (ke. V) Initial radiation energy loss with 3 wigglers (ke. V) Ultimate radiation energy loss with 8 wigglers (ke. V) Bending magnet radiation energy loss (ke. V) Emittance of bare lattice (nm) Emittance with 3 wigglers (nm) Emittance with 8 wigglers (nm) 129. 3 387. 9 1, 034. 4 286. 4 2. 1 1. 0 0. 6 Storage Ring RF System Radio frequency (MHz) Number of superconducting cavities Installed RF power for initial configuration (k. W) Harmonic cavity (2 cells/cavity) 22 499. 46 2 +1 spare 540 2 BROOKHAVEN SCIENCE