nsls-ii asac review, 4/23-24/07 h-c. hseuh,…, sr vacuum systems & fe sr vacuum systems and...
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NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
SR Vacuum Systems and Front Ends
Design Goals & Vacuum Cell Layout
Cell Chambers
Cross section updates
3-pole wigglers, IR chambers
Ray tracing and with canted damping wigglers
Absorbers, space allocation
Vacuum pumping and pressure profiles
Front Ends
Summary and Plan
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Design GoalsAdequate Apertures and Low Impedance• BSC aperture - 25mm (V) x 76 mm (H)• Chamber cross section and straightness/flatness to < 1 mm / 5m• Smooth cross section changes (10:1 ratio)• Surface finish to ~ μm• Clearance between chambers and magnet poles ~ 2mm
Low Pressure of < 1 nTorr (> 50% H2), (beam-gas) > 40 hrՇ
• Low outgassing and desorption after in-situ bake and beam conditioning• Intercept photons at discrete absorbers away from the source • High effective pumping speed (IP+TSP) at absorber locations
• 15 IP+TSP per superperiod– Distributed NEG strips in ante-chambers for active gases
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
30 vacuum cells of ~ 19m each
straights: 8.6m x15 + 6.6m x 15
Isolatable with 60 gate valves
Cell chamber material: extruded Al 6063-T5
Based on extensive experience at NSLS and APS
Developing fabrication procedures with help from APS
50 + 5 + 5 bending chambers - 6o, ~ 3m long (3+ types, 3 lengths)
90 multipole chambers of 3 lengths, 4m, 5m & 3.7m
~ 40 day-one straight section chambers of various lengths
extruded Al with similar cross sections as multipole chambers
Absorber locations
Vacuum Cell Layout
IP+TSP locations
3PW Front End
DW Front End
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Changes since last review•Thicker wall at gap and at NEG slots• Relocated cooling channels
After machining
Bending Chamber Cross Section
Extruded cross sectionsBSC: 25 x 76 mm2
3mm wall
Bending chamber, ~ 3m long
SM=45 MPa
DY=0.35mm x 2
SY = 145 MPa
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Multipole chamber extruded cross section
@ sextupole
@ quadrupole
BSC: 25 x 76 mm2
Multipole Chamber Cross Sections
DY = 0.33mm x 2
SM = 94 MPa
SY = 145 MPa
3-D FEA at the sextupole
2.9mm
3.1mm
w/ thicker wall
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Details on BPM machining, mounting and supports
Detailing chamber cross sections for prototype extrusion
Detail dimensions w/ tolerances
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
3-Pole Wiggler and IR Chambers at BM2
IR Vacuum chambers: 5 x 90mm in 90mm dipoles + 5 x 35mm in regular dipoles Impact to vacuum: outgassing, HOM heating, pumping, etc.
3 Pole Wigglers: 32/35mm gap x 20cm at u/s BM2 ~ 2.5 mm wall at center pole
Conceptual design of IR chamber in 90mm dipole gap
Ray tracing at absorber locations
BM2 fan
BM1 fan
Crotch absorber d/s of 3-pole wiggler
3PW fan±1 mrad
BM2
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Damping wiggler absorber and crotch absorber at BM1
Crotch AbsorberDW power 65 kW with ± 2.3 mrad fan, canted ± 1 mrad
Absorber: 4.5 kW @ 0.5 mrad x 2; 11 kw @ 1 mrad x 2
Need to clip 1 mrad x 2: to shadow the FE beam pipes
Wiggler Absorber
Canted Damping Wiggler Fans
BM1
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Flange absorber or stick absorber at center of straight to trim u/s BM2 fan and protect d/s bellows and gate valve
Crotch absorbers: 2 per cell for BM radiation
Stick absorbers (or flange absorber): 4 per cell for BM radiation
Wiggler absorbers: for damping wigglers
No ring absorbers needed for undulator (and 3 pole wiggler) fans
Ray Tracing and Absorbers
Stick absorber at 23mm to trim u/s BM1 fan and protect d/s flanges
FM to clip DW fan at FEDW fan after 1mrad x 2 by wiggler absorber
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
• The crotch absorber intercepts 814 W at a normal peak power density of 0.25kW/mm2. A maximum temperature of 105 ºC is calculated.
• The intercepted power by the wiggler absorber is 11 kW (at 1 mrad x 2) out of 65 kW. This results in a maximum temperature of 427 ºC . The actual temperature is 15 to 20% lower because of scattering. A fatigue life of > 10,000 cycles is expected.
SR Absorbers – Thermal Analyses
Stick Absorber Flange Absorber Crotch Absorber Wiggler Absorber
Chamber heating?
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Available space for ID at straight sections
Space for pumps at girder #3
= Lattice length – 1.5m
End box/transition, BPMs,
bellows, gate valve, etc.
GV End box
Bellows/ fast correctors
UBPM w/ isolated stand?
Girder stability?
DW / EPU
BPM
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
UHV Pumping and Pressure Profiles
Pavg < 1 nTorr
In-situ baking of entire cells at 120 C x 40 hrs
To reduce thermal outgassing to < 1x10-12 Torr.l/s/cm2
Whole ring thermal gas load of < 1x10-5 Torr.l/s
Pressure will be dominated by photon stimulated desorption (PSD)
# photons from 60 BM ~ 1x10+21/s ≈ 7x10-5 Torr.l/s (Assuming η (PSD) = 2x10-6 mol/hv for Cu after ∫hv > 1024/m )
# photons from one 7m DW ~ 6x10+20/s
with 15% intercepted by the ring absorber ➱ 7x10-6 Torr.l/s (each DW)
NEG strips ~ 1,400 m @ > 100 l/s/m for active gases
Reside in ante-chambers as in APS
Pump thru the photon slots ( C = ~ 200 l/s/m)
Ion pumps and TSP of ~ 500 l/s at absorbers
15 IP/TSP per supercell + 4 at four front ends on day one
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Pressure Profiles with and w/o Damping Wiggler Radiation
By E. Hu & F. Makahleh
Pavg ~ 0.27 nTorr
w/o DW
Pavg ~ 0.3 nTorr
w/ DW
AbsorberIP/TSP
To b
e updat
ed
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
SR Front Ends – Design Concept
FE with insertion devices: One fixed mask (FAPM); two safety shutters (SS) one photon shutter (PS); two X-ray BPMs
Day one FE: One photon shutter (PS) for BM radiation
Typical APS front end
Pressure of a few nTorr to protect the SR UHV
Bakeable to 200 C (all metal, UHV material, etc)
IP/TSP combination at high heat load components
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
IP/TSP
GV
BPM
BPM
SS x 2
COFM
PS
IP/TSP
GV
FVFM: fixed mask; CO: collimator; PS: photon shutter; BDA: beam defining aperture; SS: safety shutter
Typical layout of hard/soft x-ray beam line front end.
GV: gate valve; FV: fast valve;
IP/TSP: ion & titanium sublimation pumps
IP/TSP
APS fixed mask design
Collimator Photon shutterSafety shutters
Need thermal analysis of all high heat load components for each FE
X-BPM
NSLS-II ASAC Review, 4/23-24/07 H-C. Hseuh,…, SR Vacuum Systems & FE
Cell chamber layout with updated lattice – continuing effort
Good progress in chamber detail and cross sections with ray tracing
Ensure adequate locations and space for absorbers and pumps
Extrusion development
Detail cell chamber cross sections for prototype extrusion this year
Interface with two potential vendors (Taber, Tailien)
4 APS cell chambers and 3 bellows for R&D and evaluation
NEG support and assembly R&D, mechanical and fast corrector test
2007+ Plan
Continue detail design of chambers, absorbers and FE components
collaboration with APS on extrusion details
Hire ME, MD and VT, set up vacuum lab
MOUs with APS and TLS
with access to APS drawings, and TLS Al cleaning development
Prototype extrusion of both cross sections with two vendors
Summary and Work Plan for 2007