NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Storage Ring Vacuum Systems H-C. Hseuh, C. Foerster, J. Hu, G. Mahler, S. Pjerov, S. Sharma, J. Skaritka, C. Stelmach, … October 10, 2006

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Outline Design Principles Vacuum Cell Layout Cell Chambers and Material - Al Chamber Cross Sections and Analysis Vacuum Pumping and Pressure Profiles Front End Vacuum Summary

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Low Pressure of < 1 nTorr (» 50% H 2 ) Low outgassing and desorption after in-situ bake and pre-conditioning Intercept photons at discrete absorbers –Located absorbers far away from the source Lower power density and simpler cooling High effective pumping speed (IP + TSP) at absorber locations Low Impedance: Beam channel with smooth cross sections –Minimize no. of tapers, steps, gaps – low Z –Minimize no. of holes, slots for pumps and bellows – low Z/n Inner wall surface finish to ~ μm Design Principles Adequate Apertures for Beam and Exit Photons BSC - 25mm x 70mm Chamber cross section precision to ~1 mm Chamber temperature stability « 1 o C

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems 30 standard cells of ~ 19m each LSS: 15 x 5m and 15 x 8m Isolatable with 60 gate valves Vacuum Cell Layout 4m 3m 5m 4m Cell chamber material: extruded aluminum 6063-T5 NSLS and APS experience; fabrication cost thermal/electrical conductivity; ease of in-situ baking 60 bending chambers of 6 o each, 3m long 90 multipole chambers of 3 different lengths/types > 20 day-one LSS chambers of various types extruded Al with same cross sections as cell chambers Absorber locations FE

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems SpecificsAlSSTCu Initial PSD rateHighLowAverage Mechanical strengthAcceptableExcellentGood Thermal expansionLargeSmall Thermal conductivityExcellentPoorExcellent WeldabilityGoodExcellentGood Beam impedanceLowHighLow Bi-metal flangesYesNoYes Cooling channelsExtrusionBrazed Fabrication costLowAverageExpensive Ease of in-situ bakeGoodPoorGood Radiation shieldingPoorAverageExcellent AL-6063 (T5) Extrusion for the Cell Chamber Comparison of chamber materials

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Material ($): Aluminum 6063-T5 billets, ~ 350mm diameter Extrusion ($): only a few available (interested) vendors in the US ( due to the large cross sections and required dimensional precision) ➱ > 1 yr to develop the correct parameters for each type before production can start Stretching: to straighten and eliminate the waviness of inner surface Roll Bending ($): to obtain the correct curvature for bending chambers Machining ($$$): ports for beam lines, BPMs, absorbers, pumps, …. profiles at multipole, transitions, … Cleaning ($): to remove surface contaminants and reduce oxide layer Welding ($$): photon exit ports, SS-Al bi-metal flanges, etc. Assembly ($$$): BPMs, NEG strips, pumps, gauges, absorbers, …. Fabrication Steps for Cell Aluminum Chambers (G. Goeppner/E. Trakhtenberg, APS, ANL)

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Bending chamber, ~ 3m long 3-D Models of Cell Chambers Special Bending chamber for IR lines Bending magnet/girder #3 Multipole magnets/girder Multipole chamber #3, ~ 5m long

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems 3mm wall BSC: 25 x 70 mm 2 Dipole extruded cross sections Chamber cross sections

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Multipole chamber extruded cross quadrupole After Machining 3.9mm 3.2mm BSC: 25 x 70 mm 2 Chamber cross sections – cont’d

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems S M = 172 MPa (Localized) von Mises stress at sextupole location S Y = 144 MPa for Al 6063-T5 S M (D) = 54 MPa S M (Q) = 100 MPa Chien Pai, C-AD

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems D M = 0.6mm x 2 Deflection at sextupole location D M (Dipole) = 0.36mm x 2 D M (Quad) = 0.57mm x 2 Chien Pai, C-AD

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems UHV Pumping and Pressure Profiles P avg < 1 nTorr In-situ baking of entire cells at 120 C x 40 hrs To reduce thermal outgassing to < 1x Torr.l/s/cm 2 Total ring thermal gas load of < 1x10 -5 Torr.l/s Pressure will be dominated by photon stimulated desorption (PSD) # photons from BM ~ 1x /s ≈ 7x10 -5 Torr.l/s Assuming η (PSD) = 2x10 -6 mol/hv for Cu after ∫hv > /m # photons from each 7m DW ~ 6x /s with 15% intercepted by the ring absorber ➱ 7x10 -6 Torr.l/s 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 5 IP/TSP per cell + 2 for each ID location

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems PSD Yield versus Photon Dosage measured at NSLS U9A & X28 beam lines C. Foerster, et.al, J. Vac Sci. Technol. A14, 1273(1996). C. Foerster, et.al, J. Vac Sci. Technol. A19, 1652(2001). Cu Al ~ 100A.hr at NSLS

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Pressure Profiles (BM only) with Various Pumping Schemes By E. Hu & F. Makahleh Using Molflow and VacCal codes P avg ~ 1.5 nTorr P avg ~ 0.3± 0.1 nTorr Distributed NEG strips are critical to achieve low P avg ! Preliminary

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Pressure Profiles with and w/o Damping Wiggler Radiation By E. Hu & F. Makahleh P avg ~ 0.27 nTorr P avg ~ 0.3 nTorr Absorber IP/TSP Preliminary

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Beam Line Front End Vacuum Typical layout of Day 1 front end w/o beam line. Pressure of a few nTorr to protect the UHV SR vacuum from HV beam line with window or differential pumping Entire FE to be bakeable to 200 C (all metal, UHV material, etc) IP/TSP combination (same as SR) at high heat load components PS: photon shutter BS: Bremsstrahlung beam stop IP/TSP: ion pump/titanium sublimation pump GV: gate valve GVBS PS IP/TSP Front end design depends on type of radiation source (BM or ID) base on experience at NSLS and APS Details are being developed with the beam line determination Front End Vacuum Systems

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems IP/TSP GV BPM SS x 2 CO PM PS IP/TSP GV FV BDA PM: photon 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 pump and titanium sublimation pump IP/TSP

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Detail layout of cell and ID chambers, absorbers and pumps Detail design of cell chambers and absorbers Fabricate or acquire (from APS?) a few prototype cell chambers Learn and develop expertise in NSLS-2 chamber fabrication Establish formal collaboration with APS colleagues Work with potential extrusion vendors ASAP Refine the fabrication technique to meet the specifications Perform mechanical and vacuum evaluation on prototype chambers Dimensional precision, support, alignment NEG strip supports and installation Vacuum performance In-situ baking, NEG activation Major Goals for FY07 and FY08:

NSLS-II ASAC Review, 10/9-11/06 H-C. Hseuh,…, SR Vacuum Systems Summary Preliminary layout of cell chambers is progressing well Improvements are made together with the lattice Stress and deflection of chambers at multipole locations are acceptable Detail chamber design can be started Ray tracing of SR fan continues to optimize the absorber design Simulation of the pressure profiles has started. Including the PSD gas load from ID devices. To be refined with the final chamber/absorber design Pressure of < 1 nTorr is achievable with present pumping scheme Need to collaborate with APS colleagues on chamber fabrication Need to work with extrusion vendors soon