1. 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

2. H-C. Hseuh,…, SR Vacuum Systems & FE
Design Goals
Adequate 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), Շ (beam-gas) > 40 hr
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

3. H-C. Hseuh,…, SR Vacuum Systems & FE
Vacuum Cell Layout
Absorber locations
30 vacuum cells of ~ 19m each straights: 8.6m x m x 15 Isolatable with 60 gate valves
IP+TSP locations
DW Front End
3PW Front End
Cell chamber material: extruded Al 6063-T5
Based on extensive experience at NSLS and APS
Developing fabrication procedures with help from APS
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
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

4. Bending Chamber Cross Section
Changes since last review
Thicker wall at gap and at NEG slots
Relocated cooling channels
Bending chamber, ~ 3m long
BSC: 25 x 76 mm2
Extruded cross sections
SM=45 MPa
3mm wall
SY = 145 MPa
DY=0.35mm x 2
After machining
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

5. H-C. Hseuh,…, SR Vacuum Systems & FE
Multipole Chamber Cross Sections
w/ thicker wall
BSC: 25 x 76 mm2
Multipole chamber extruded cross section
3.1mm
3-D FEA at the sextupole
SM = 94 MPa
@ quadrupole
SY = 145 MPa
2.9mm
DY = 0.33mm x 2
@ sextupole
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

6. Detailing chamber cross sections for prototype extrusion
Detail dimensions w/ tolerances
Details on BPM machining, mounting and supports
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

7. H-C. Hseuh,…, SR Vacuum Systems & FE
3-Pole Wiggler and IR Chambers at BM2
3 Pole Wigglers:
32/35mm gap x 20cm at u/s BM2
~ 2.5 mm wall at center pole
Ray tracing at absorber locations
BM1 fan
3PW fan
±1 mrad
BM2
BM2 fan
Crotch absorber d/s of 3-pole wiggler
IR Vacuum chambers:
5 x 90mm in 90mm dipoles + 5 x 35mm in regular dipoles
Impact to vacuum: outgassing, HOM heating, pumping, etc.
Conceptual design of IR chamber in 90mm dipole gap
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

8. H-C. Hseuh,…, SR Vacuum Systems & FE
Damping wiggler absorber and crotch absorber at BM1
BM1
Wiggler Absorber
DW power 65 kW with ± 2.3 mrad fan, canted ± 1 mrad
Absorber: mrad x 2; 11 1 mrad x 2
Need to clip 1 mrad x 2: to shadow the FE beam pipes
Crotch Absorber
Canted Damping Wiggler Fans
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

9. H-C. Hseuh,…, SR Vacuum Systems & FE
Ray Tracing and Absorbers
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
FM to clip DW fan at FE
DW fan after 1mrad x 2 by wiggler absorber
Stick absorber at 23mm to trim u/s BM1 fan and protect d/s flanges
Flange absorber or stick absorber at center of straight to trim u/s BM2 fan and protect d/s bellows and gate valve
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

10. H-C. Hseuh,…, SR Vacuum Systems & FE
SR Absorbers – Thermal Analyses
Stick Absorber
Flange Absorber
Crotch Absorber
Wiggler Absorber
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.
Chamber heating?
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

11. Available space for ID at straight sections
= Lattice length – 1.5m
Girder stability?
End box/transition, BPMs,
bellows, gate valve, etc.
Space for pumps at girder #3
BPM
End box GV
DW / EPU
UBPM w/ isolated stand?
Bellows/ fast correctors
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

12. 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 > 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

13. H-C. Hseuh,…, SR Vacuum Systems & FE
Pressure Profiles with and w/o Damping Wiggler Radiation
By E. Hu & F. Makahleh
To be updated
Pavg ~ 0.3 nTorr
w/ DW
Pavg ~ 0.27 nTorr
w/o DW
Absorber
IP/TSP
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

14. SR Front Ends – Design Concept
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
Day one FE: One photon shutter (PS) for BM radiation
FE with insertion devices:
One fixed mask (FAPM); two safety shutters (SS)
one photon shutter (PS); two X-ray BPMs
Typical APS front end
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

15. H-C. Hseuh,…, SR Vacuum Systems & FE
Typical layout of hard/soft x-ray beam line front end.
Need thermal analysis of all high heat load components for each FE
SS x 2
FM: fixed mask; CO: collimator; PS: photon shutter; BDA: beam defining aperture; SS: safety shutter FV GV
BPM PS GV
BPM CO FM
IP/TSP
IP/TSP
IP/TSP
GV: gate valve; FV: fast valve;
IP/TSP: ion & titanium sublimation pumps
Collimator
Photon shutter
Safety shutters
APS fixed mask design
X-BPM
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE

16. H-C. Hseuh,…, SR Vacuum Systems & FE
Summary and Work Plan for 2007
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
NSLS-II ASAC Review, 4/23-24/07
H-C. Hseuh,…, SR Vacuum Systems & FE