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Storage Ring Vacuum Systems. H. Hseuh, Vacuum Group ASAC Review of NSLS-II July 17-18, 2008. Outline. Vacuum System Requirement and Layout Vacuum Chamber Design Prototype Chamber Fabrication Ray Tracing, Absorbers and Pressure Profiles - PowerPoint PPT Presentation
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BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20081 of 21
Storage Ring Vacuum Systems
H. Hseuh, Vacuum GroupASAC Review of NSLS-II
July 17-18, 2008
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20082 of 21
Outline
• Vacuum System Requirement and Layout
• Vacuum Chamber Design
• Prototype Chamber Fabrication
• Ray Tracing, Absorbers and Pressure Profiles
• Layout of Straight Sections for ID, Inj. and RF
• Development in Bellows, BPM Buttons, NEG Strip Support
• Development in In-situ Bake and Ozone Cleaning
• Summary
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20083 of 21
Vacuum Chambers - Adequate Apertures and Low Impedance• Beam aperture – 25 mm (V) x 76 mm (H)• Chamber straightness - < 1 mm / 5 m• Smooth cross section changes: inclination angle < 10o
• Minimum steps or cavities < 1 mm• Mechanical stability: 1 fixed & 2 flexible invar supports at BPMs
P(avg) < 1 nTorr (> 50% H2, < 50% CO, CO2, CH4, …),
• Շ (beam-gas) > 40 hr (inelastic scattering)• Local pressure bumps ➾ bremsstrahlung radiation• Intercept BM photons at discrete absorbers
– To protect un-cooled flanges and bellows– Large ion pump and TSP (or NEG cartridge) at absorbers
• Two NEG strips in antechamber to provide linear pumping
Vacuum Requirements
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20084 of 21
Cell Vacuum Chamber Layout
BM Beamline
ID Beamline
L.S.
S.S.
Absorbers/pumps
S2 - 3.6m
S3 - 3m
S4 – 3.3m
S5 – 3m
S6 – 3.7m
Aluminum Cell Chambers
S2 S3S4
S5
S6
Multipole chamber
Dipole chamber, 6o bend
Stainless chambers
S1
S1
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20085 of 21
Extruded cross section
Machined at pole locations
Bended and machined
Extruded
3 mm wall
3.1 mm wall
Multipole ChamberDipole Chamber
At Quadrupole
At Sextupole
Cell Chamber Cross Sections and Analysis
Maxi. δ = 0.3 mm x2Max. S = 42 MPa
Maxi. δ = 0.27 mm x2Max. S = 64 MPa
Syield (A6063T5) = 145 MPaSstress (A6063T5) = 186 MPa
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20086 of 21
End plate & bi-metal flanges
Aluminum Cell Chamber Fabrication
Extrusion ➾ bending ➾ machining ➾ cleaning ➾ welding ➾ assembly …. $ $$$$ $$$$$
V #1,2 V #3 V #4, 5, 6… APS APS BNL
Extrusions
Machining
Test extrusion with two vendors completed
Fabricate two S4 chambers by Sept
Machining by CS and by vendor started
Weld development by APS started
Bending of dipole extrusions starts soon
Machining End plate
End Assy
Welding at APS
L. Doom
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Ray Tracing of Photon Fans
To define photon fans and absorber locations
• ➾ To ensure adequate apertures for photon fans
• ➾ To protect un-cooled flanges and bellows
• ➾ To estimate power, density and ΔT for absorbers, and P profile
Damping Wiggler
Multipole
Dipole
Dipole
Multipole
Multipole
DW fan
DW absorber
Flange absorber
Stick absorber
Crotch absorber
DW fan: 32 kW x 2, ± 2.6 mrad
canted by ± 1.8 mrad
EPU fan: 6 kW x 2, ± 0.46/0.77 mrad
canted by ± 0.12 mrad?
IVU fan: 8 kW, ± 0.31 mrad
Dipole fan: 2.4 kW, 105 mrad
Damping Wiggler
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/20088 of 21
DW and BM Photon Fans at S1-S4 Region
Larger bellows and RF fingers to accommodate canted DW fan
S2 S3
S2S3
DW ABS > 15 kW
Vertical fan hitting Top/bottom wall
BM S3, S6 ~5EPU S1-S3 < 35IVU20 S1 160*DW S1 166 S2 280
S3 270
S4
Source Location P(W)
Large SR power intercepted here
Limited space for
pumping ports and multipoles
S3
S4BS4A
*on magnet shields
M. Ferreira
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SR Vacuum SystemsASAC Review, 7/17-
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P = 166 W
P = 274 W
P = 230 W
S1B
Simulation of DW vertical power using SPECTRA8
S2 S3
DW 1
P = 40 W
From DW1
From DW2
DW 2
ΔP < 0.3 W/cm2
h ~ 9 mmh = 10 - 25 mm
h = 15 - 25 mm
P = 6 W
DW fan profile
M. Ferreira
Power and density are not excessive for S2 and S3 chambersFlange absorbers may be added at S1A-S1B, S1B-S2, and S2-S3? to trim vertical fan effectively, still with reasonable impedance
+ 1.8 mrad
- 1.8 mrad
ΔP < 0.5 W/cm2
S1A
BROOKHAVEN SCIENCE ASSOCIATES
SR Vacuum SystemsASAC Review, 7/17-
18/200810 of 21
Photon Absorbers (8-10 per cell)
Stick
< 12 W/mm2, Tmax ~ 200oC
< 3 W/mm2, Tmax ~ 68oC
P (kW) absorber 22
Pmax (W/mm2) 25
Smax (MPa) 303
Tmax (oC) 256
Damping Wiggler Absorber
BM Absorber Positions and Power
Crotch in dipoleCrotch Stick in multipole Flange
Absorber brazing development started
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Absorber Positioning vs. Aperture Requirement
-- ± 3% aperture
Δ ABS +X position
W. Guo
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18/200812 of 21
Pressure Profile with and without DW
3 GeV, 0.5A, η = 1x10-
5
Pavg = 0.13 nT
Pavg = 0.25 nT
LS SS
Local ΔP w/ 15% DW fan ➾ bremsstrahlung radiation
Molflow Code(R. Kersevan/ESRF)
To be updated
E. Hu
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SR Vacuum SystemsASAC Review, 7/17-
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Layouts for Insertion Device Straights
ID Chamber Design:Chamber inner height ≈ magnet gap - 3 mm Extruded Al with NEG strips in antechamber Or extruded Al w/NEG coated
APS ID chamber
Limited space for stand-alone ID BPMs
h = 8 x 57 mm, 1mm wall
h = 7.5 mm, 1.25 mm wall
ESRF NEG coated chamber
9.3 m straight for 2 x 3.5 m DW
6.6 m straight for 2 x 2 m EPU
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Injection Straight
RF Straight
Bellows + transition
Layouts for Injection and RF Straights
Working closely with AP, Diag, Magnet and other systems on the layout of special
components
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inside fingers
M. Ferreira
outside fingers
Choice of RF Shielded Bellows
inconel springs
Be-Cu fingers
Inside fingers Outside fingers
(APS, LNLS) (Soleil, Diamond, etc)
Simple, reliable Lower impedance
$$ $$$
Outside fingers
Wider fingers
Fewer fingers
RF Bellows Requirements:Max mis-alignment: 2 mm; Max comp/extension: ± 12 mm;
Max angle deviation: 15 mrad
3D model for impedance simulation
Inside or outside fingers?
-20 -10 0 10 20 30 40 50 60 70-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
s, mm
W,
V
loss = 10 mV/pC
Solid sleeve
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Impedance of Other Vacuum Components
Component # loss, V loss, V
RF Bellows 200 1e-2? 2
S4A pump port 30 1e-3 0.03
Stick absorber 120 2e-3 0.24
Gate valve 60 2e-3 0.12
Crotch absorber 60 TBD
Flange absorber ~ 50 0.2?
Multipole chamber with stick absorber and pumping
ports
S4A chamber with absorber and shielded pumping ports
A. Blednykh
GV RF shields
Work closely with AP on vacuum components impedance simulation and
approval
Flange absorber
S4A absorber and pump port
Dipole chamber with crotch absorber and pumping
ports
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SR Vacuum SystemsASAC Review, 7/17-
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Mounting of BPM Buttons/Flanges
7mm Ø 12 mm apart
w/ 44 mm Ø flange
Optimum design:
7 mm Ø buttons, 16 mm apart?
(O. Singh’s talk)
P. Cameron
Rectangular flange?Sealing reliability?
CD-2 Design
10mm Ø button /34 mm Ø flange /Helicoflex seal
50
16
25
2 12 mm wall may be too thin for bolts/inserts & sealing
15 mm wall?
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NEG strip supports
Riveted mounting every 10cm, with alumina insulators on carrier plates
Prototype to be tested on APS chambers for reliability and flexibility
L. Doom, K. Wilson
NEG support development using APS chambers
NEG strips in Antechamber
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M. Ferreira, F. Lincoln
T ~120oC achievable with foil heaters mounted at drift space (< 1 kW/m)
Need to optimize power, heater temp, non-magnetic, insulation, etc
Eliminate the needs of high P, hot water system, a major ES&H concern
In-situ Bake with External Heaters
APS chambers for bakeout development
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Process developed by T. Momose, KEK
Final cleaning prior to installation (after alignment…)
Extensive O3 monitoring to meet ES&H requirements
System being assembled for testing
K. WilsonOzone Cleaning Development
Flush chamber with < 500 ppm O3 in O2 to break and remove contaminants
Ozone system flow diagram
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Summary
• Cell vacuum chamber design is well advanced
• Test extrusion of both cross sections completed with two vendors
• Machining and weld development of prototype chambers are underway
• Ray tracing and absorber development continues
• Straight section layouts for ID, RF and Inj has started
• RF shielded bellows design has started
• Work with AP on vacuum component impedanace
• Work with Diag. on finalizing BPM button/feedthru design.
• NEG strip supports developed and is being tested
• Chamber bakeout with foil heaters is successful
• Ozone cleaning system developed and is ready for evaluation