Transcript 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
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Introduction
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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.
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Design Concept for the Baseline Configuration
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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
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Accelerator System Configuration
Booster
Booster
Storage Ring
Linac
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
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Storage Ring
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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
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Rendering of the NSLS II Ring (Rear View)
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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 stateof-the-art existing facilities.
• While the design presents challenges for the beam dynamics, beam
instrumentation, controls and hardware, the performance goals appear
achievable.
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Injector Linac
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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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Booster Synchrotron
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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
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Booster Lattice and its Relationship with Storage Ring
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Storage Ring Lattice Layout
Linac
RF Station
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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%
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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
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Lattice functions of half
of an NSLS-II SR
super-period (one cell).
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Dynamic Aperture of the Lattice
For on momentum and off momentum cases by 3%
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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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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
3rd cavity
with 300kW
Transmitter
Add 4th RF
station
RF power
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P(kW)
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P(kW)
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P(kW)
#
P(kW)
Dipoles
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144
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144
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144
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144
Damping Wigglers
(9.23 kW/m, 7m each)
3
194
4
259
8
517
8
517
CPMU’s (4.17kW/m,
3m each)
3
38
6
76
6
76
10
127
EPU’s (4.1kW/m, 4m
each)
2
33
4
66
4
66
5
83
?
200
Additional Devices
Total
409
545
803
1071
Available Power
540
540
810
1080
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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
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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
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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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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 SubProject
Mechanical Engineering Group*
Electrical Engineering Group*
Storage Ring System
Sub-Project
RF Group
Diagnostic & Controls Group
Insertion Devices Group
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Summary
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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
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Parametric Comparison of Lattice
Lattice
TBA24
DBA32
DBA30
DBA28
DBA26
DBA24
Circumference (m)
630
822
780
739
697
656
Straight Sections (n  [m])
247
16(8,5)
15(8,5)
14(8,5)
13(8,5)
12(8,5)
1.3/7.6
0.33/30
0.4/25
0.43/25
0.46/25
0.5/25
X [bare lattice] (nm)
~1
1.7
2.1
2.6
3.2
4.1
X [56m of damping wigglers] (nm)
NA
0.5
0.6
0.7
0.8
1.1
Number of Long Straights
24
16
15
14
13
12
Injection and RF
3
3
3
3
3
3
NA
8
8
8
8
8
5
5
5
5
5
5
4
3
2
1
16
15
14
13
12
26
24
22
20
18
Dipole Field (T)/Bending radius (m)
Straight Section Utilization
Reserved for Damping Wiggler
Fix Gap Wiggles Available to Users
Long Straight for User Devices
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Short Straight for User Devices
Total User Insertion Device Straight
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Injector Linac Parameters
Linac
Nominal/maximum linac energy (MeV)
Frequency (GHz)
Number of accelerating structures
Number of klystrons (no hot spare)
Pulse repetition rate (pps)
Beam pulse length (ns)
Pulse charge (nC) (overall charge in a macropulse)
Energy spread ( %)
Total number of traveling wave accelerating sections
24
200/270
2.998
5
3
<10
1 - 80 (up to 1µs)
>7
<0.5
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Booster Ring Parameters
Booster Ring
Injection energy (MeV)
Nominal top energy (GeV)
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 GeV (T)
Energy loss per turn at 3 GeV (keV)
Beam current (mA)
Natural emittance at 3 GeV (nm-rad)
Number of bunches
25
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
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Storage Ring Parameters
Storage Ring Assembly
Number of DBA Cells
Circumference (m)
Nominal energy (GeV)
Circulating current @ 3 GeV, multi-bunch (mA)
Circulating current @ 3 GeV, single bunch (mA)
Harmonic number
No. of filled bunches/harmonic number
Nominal bending field @ 3 GeV (T)
Dipole critical energy @ 3 GeV (KeV)
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
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30
780
3
500
0.5
1300
80%
0.4
2.4
15: [18.15/3.09]
15: [2.72/0.945]
60
360
390
240 + (4 X ID)
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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 (keV)
Initial radiation energy loss with 3 wigglers (keV)
Ultimate radiation energy loss with 8 wigglers (keV)
Bending magnet radiation energy loss (keV)
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 (kW)
Harmonic cavity (2 cells/cavity)
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499.46
2 +1 spare
540
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