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

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2 BROOKHAVEN SCIENCE ASSOCIATES 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 and other requirements translate into the target parameters of the storage ring as; ~3 GeV, 500 mA, top-up injection Brightness ~ 7x10 21 photons/sec/0.1%bw/mm 2 /mrad 2 Flux ~ 10 16 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

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3 BROOKHAVEN SCIENCE ASSOCIATES Linac Booster Storage Ring Accelerator System Configuration 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 Booster Storage Ring

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

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5 BROOKHAVEN SCIENCE ASSOCIATES 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

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6 BROOKHAVEN SCIENCE ASSOCIATES 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/m 2, ~55 kg 15 sextupoles: 0.2 m long, <200T/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

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7 BROOKHAVEN SCIENCE ASSOCIATES Booster Lattice and its Relationship with Storage Ring

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8 BROOKHAVEN SCIENCE ASSOCIATES Storage Ring Lattice Layout Linac RF Station

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9 BROOKHAVEN SCIENCE ASSOCIATES 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 Basic 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 (rms): 2.9 mm/~10 psec

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

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11 BROOKHAVEN SCIENCE ASSOCIATES Dispersion Section of a Cell 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 Alignment tolerance of multipoles on a girder is 30 m, whereas girder-to- girder tolerance is ~100 m

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

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13 BROOKHAVEN SCIENCE ASSOCIATES 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

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14 BROOKHAVEN SCIENCE ASSOCIATES RF Power Up-grade Path RF Power Requirements for Dipole and Various Insertion Device Configurations. Covered in baseline proposal Installed RF Power (270kW/unit Power the 3 rd cavity with 300kW Transmitter Add 4 th RF station RF power#P(kW)# # # Dipoles-144- - - Damping Wigglers (9.23 kW/m, 7m each) 319442598517 8 CPMU’s (4.17kW/m, 3m each) 3 386 766 10 127 EPU’s (4.1kW/m, 4m each) 2 33 4 664 5 83 Additional Devices ? 200 Total Available Power 409 540 545 540 803 810 1071 1080

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15 BROOKHAVEN SCIENCE ASSOCIATES 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 ~ 10 16 photons/sec/0.1%bw Brightness ~ 7x10 21 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 keV) Up to 5 bending magnets for IR, far-IR, and THz beamlines

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16 BROOKHAVEN SCIENCE ASSOCIATES 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 ~ 10 16 photons/sec/0.1%bw ? Brightness ~ 4x10 21 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 (E C ~2.4 keV) No. of IR beams from wide gap dipoles: 5

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17 BROOKHAVEN SCIENCE ASSOCIATES 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

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18 BROOKHAVEN SCIENCE ASSOCIATES 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 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

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19 BROOKHAVEN SCIENCE ASSOCIATES Injector Linac Parameters Linac Nominal/maximum linac energy (MeV)200/270 Frequency (GHz)2.998 Number of accelerating structures5 Number of klystrons (no hot spare)3 Pulse repetition rate (pps)<10 Beam pulse length (ns)1 - 80 (up to 1µs) Pulse charge (nC) (overall charge in a macropulse)>7 Energy spread ( %)<0.5 Total number of traveling wave accelerating sections5

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20 BROOKHAVEN SCIENCE ASSOCIATES Booster Ring Parameters Booster Ring Injection energy (MeV)200 Nominal top energy (GeV)3 Circumference (m)780 Ramping repetition rate (Hz)1 Acceleration time (s)~0.4 Harmonic number1300 Radio frequency (MHz)499.46 Total number of cells15 Number of combined function bending magnets60 Number of quadrupole96 Dipole nominal aperture (mm)25 Dipole field at injection (T)0.0533 Dipole field at extraction at 3 GeV (T)0.7 Energy loss per turn at 3 GeV (keV)500 Beam current (mA)2.7 Natural emittance at 3 GeV (nm-rad)11.5 Number of bunchesfrom 1 to >100

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21 BROOKHAVEN SCIENCE ASSOCIATES Storage Ring Parameters Storage Ring Assembly Number of DBA cells30 Circumference (m)780 Nominal energy (GeV)3 Circulating current @ 3 GeV, multi-bunch (mA)500 Circulating current @ 3 GeV, single bunch (mA)0.5 Harmonic number1300 No. of filled bunches/harmonic number80% Nominal bending field @ 3 GeV (T)0.4 Dipole critical energy @ 3 GeV (KeV)2.4 Number of 8 m straights: [βx/βy (m)]15: [18.15/3.09] Number of 5 m straights: [βx/βy (m)]15: [2.72/0.945] Number of dipoles60 Number of quadrupoles360 Number of sextupoles390 Number of correctors and scew240 + (4 X ID)

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22 BROOKHAVEN SCIENCE ASSOCIATES Storage Ring Parameters (Continue) Damping Wigglers Initial number of 7 m damping wigglers2 Fixed +1 Vari Final number of 7 m damping wigglers5 Fixed +3 Vari Max. peak field (T)1.8 Radiation energy loss per wiggler (keV)129.3 Initial radiation energy loss with 3 wigglers (keV)387.9 Ultimate radiation energy loss with 8 wigglers (keV)1,034.4 Bending magnet radiation energy loss (keV)286.4 Emittance of bare lattice (nm)2.1 Emittance with 3 wigglers (nm)1.0 Emittance with 8 wigglers (nm)0.6 Storage Ring RF System Radio frequency (MHz)499.46 Number of superconducting cavities2 +1 spare Installed RF power for initial configuration (kW)540 Harmonic cavity (2 cells/cavity)2

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