Storage Ring Vacuum Systems H. Hseuh, Vacuum Group ASAC Review of NSLS-II July 17-18, 2008 SR Vacuum Systems ASAC Review, 7/1718/2008 1 of 21 BROOKHAVEN SCIENCE ASSOCIATES 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 SR Vacuum Systems ASAC Review, 7/1718/2008 2 of 21 BROOKHAVEN SCIENCE ASSOCIATES Vacuum Requirements 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, ), (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 SR Vacuum Systems ASAC Review, 7/1718/2008 3 of 21 BROOKHAVEN SCIENCE ASSOCIATES Cell Vacuum Chamber Layout ID Beamline S1 L.S. S2 S3 Absorbers/pumps S4 BM Beamline S5 S6 Aluminum Cell Chambers S1 S.S.
Stainless chambers S2 3.6m Dipole chamber, 6o bend S3 - 3m Multipole chamber S4 3.3m S5 3m S6 3.7m SR Vacuum Systems ASAC Review, 7/1718/2008 4 of 21 BROOKHAVEN SCIENCE ASSOCIATES Cell Chamber Cross Sections and Analysis Multipole Chamber Dipole Chamber Extruded 3 mm wall Extruded cross section
Bended and machined At Quadrupole Maxi. = 0.3 mm x2 Max. S = 42 MPa Machined at pole locations Maxi. = 0.27 mm x2 Max. S = 64 MPa At Sextupole 3.1 mm wall Syield (A6063T5) = 145 MPa Sstress (A6063T5) = 186 MPa SR Vacuum Systems ASAC Review, 7/1718/2008 5 of 21 BROOKHAVEN SCIENCE ASSOCIATES Aluminum Cell Chamber Fabrication L. Doom Extrusion bending machining cleaning welding assembly . $$$ $
$ $ $$ $$ V #1,2 V #3 V #4, 5, 6 APS Machining APS BNL End plate Extrusions Machining End plate & bi-metal flanges Test extrusion with two vendors completed Fabricate two S4 chambers by Sept Machining by CS and by vendor started Weld development by APS started SR Vacuum Bending of dipole extrusions startsSystems soon ASAC Review, 7/1718/2008 6 of 21
End Assy Welding at APS BROOKHAVEN SCIENCE ASSOCIATES 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 T for absorbers, and P profile DW absorber Dampin Dampin Multipol Dipol g g e e WigglerWiggler 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 Mul tipo
e l Dip ol e Flange absorber Stick absorber canted by 0.12 mrad? DW fan Crotch absorber Mu e ltip ol IVU fan: 8 kW, 0.31 mrad Dipole fan: 2.4 kW, 105 mrad SR Vacuum Systems ASAC Review, 7/1718/2008 7 of 21 BROOKHAVEN SCIENCE ASSOCIATES DW and BM Photon Fans at S1-S4 S2Region S3 M. Ferreira S4 S2
DW ABS > 15 kW S3 S3 Larger bellows and RF fingers to accommodate canted DW fan Vertical fan hitting Top/bottom wall Source BM EPU IVU20 DW Location S3, S6 S1-S3 S1 S1 S2 S3 S4A P(W) ~5 < 35 160* 166 280 270 S4B Large SR power intercepted here
Limited space for pumping ports and multipoles *on magnet shields SR Vacuum Systems ASAC Review, 7/1718/2008 8 of 21 BROOKHAVEN SCIENCE ASSOCIATES Simulation of DW vertical power using SPECTRA8 M. Ferreira S1A S2 S1B DW 1 S3 DW 2 h = 10 - 25 mm h ~ 9 mm From + 1.8 DW1 mrad P = 166
W P = 274 W From - 1.8 mrad DW2 P=6W P < 0.5 W/cm2 DW fan profile h = 15 - 25 mm P = 230 W P = 40 W P < 0.3 W/cm2 Power and density are not excessive for S2 and S3 chambers Flange absorbers may be added at S1A-S1B, S1B-S2, and S2S3? to trim vertical fan effectively, still with reasonable SR Vacuum Systems impedance ASAC Review, 7/1718/2008 9 of 21 BROOKHAVEN SCIENCE ASSOCIATES Photon Absorbers (8-10 per cell) Crotch
< 12 W/mm2, Tmax ~ 200oC Stick Stick in multipole < 3 W/mm2, Tmax ~ 68oC Crotch in dipole Flange Damping Wiggler Absorber BM Absorber Positions and Power Absorber brazing development started SR Vacuum Systems ASAC Review, 7/1718/2008 10 of 21 P (kW) absorber 22 Pmax (W/mm2) 25 Smax (MPa) 303
Tmax (oC) 256 BROOKHAVEN SCIENCE ASSOCIATES Absorber Positioning vs. Aperture Requirement W. Guo -- 3% aperture ABS +X position SR Vacuum Systems ASAC Review, 7/1718/2008 11 of 21 BROOKHAVEN SCIENCE ASSOCIATES Pressure Profile with and without DW Molflow Code (R. Kersevan/ESRF) E. Hu Local P w/ 15% DW fan bremsstrahlung radiation To be updated Pavg = 0.25 nT
SS LS Pavg = 0.13 nT 3 GeV, 0.5A, = 1x105 SR Vacuum Systems ASAC Review, 7/1718/2008 12 of 21 BROOKHAVEN SCIENCE ASSOCIATES 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 h = 8 x 57 mm, 1mm wall h = 7.5 mm, 1.25 mm APS IDwall chamber 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 Limited space for stand-alone ID BPMs SR Vacuum Systems ASAC Review, 7/1718/2008 13 of 21 BROOKHAVEN SCIENCE ASSOCIATES
Layouts for Injection and RF Straights Bellows + transition Injection Straight RF Straight Working closely with AP, Diag, Magnet and other systems on the layout of special components SR Vacuum Systems ASAC Review, 7/1718/2008 14 of 21 BROOKHAVEN SCIENCE ASSOCIATES Choice of RF Shielded Bellows M. Ferreira RF Bellows Requirements: Max mis-alignment: 2 mm; Max comp/extension: 12 mm; Max angle deviation: 15 mrad inside fingers Inside fingers (APS, LNLS) Simple, reliable $$ Outside fingers (Soleil, Diamond, etc)
Lower impedance $$$ 0.04 0.03 loss = 10 mV/pC 0.02 outside fingers W, V 0.01 0 -0.01 -0.02 -0.03 -0.04 -20 inconel springs 3D model for impedance simulation Inside or outside fingers? -10 0 10 20 30
s, mm 40 50 60 70 Outside fingers Wider fingers Fewer fingers Be-Cu fingers Solid sleeve SR Vacuum Systems ASAC Review, 7/1718/2008 15 of 21 BROOKHAVEN SCIENCE ASSOCIATES Impedance of Other Vacuum Components Work closely with AP on vacuum components impedance simulation and approval Component S4A chamber with absorber and shielded pumping ports S4A absorber and pump port A. Blednykh # loss, V
60 TBD Flange absorber ~ 50 0.2? GV RF shields Multipole chamber with stick absorber and pumping ports Flange absorber SR Vacuum Systems ASAC Review, 7/1718/2008 16 of 21 Dipole chamber with crotch absorber and pumping ports BROOKHAVEN SCIENCE ASSOCIATES Mounting of BPM Buttons/Flanges Optimum design: 7 mm buttons, 16 mm apart? P. Cameron (O. Singhs talk) 50
16 CD-2 Design 10mm button /34 mm flange /Helicoflex seal 25 2 12 mm wall may be too thin Rectangular flange? for bolts/inserts & sealing 15 mm wall? Sealing reliability? 7mm 12 mm apart w/ 44 mm flange SR Vacuum Systems ASAC Review, 7/1718/2008 17 of 21 BROOKHAVEN SCIENCE ASSOCIATES NEG strip supports L. Doom, K. Wilson Riveted mounting every 10cm, with alumina insulators on carrier plates Prototype to be tested on APS chambers for reliability and flexibility NEG strips in Antechamber NEG support development using APS chambers SR Vacuum Systems ASAC Review, 7/1718/2008
18 of 21 BROOKHAVEN SCIENCE ASSOCIATES In-situ Bake with External Heaters 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 APS chambers for bakeout development SR Vacuum Systems ASAC Review, 7/1718/2008 19 of 21 BROOKHAVEN SCIENCE ASSOCIATES Ozone Cleaning Development K. Wilson Flush chamber with < 500 ppm O3 in O2 to break and remove contaminants 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 Ozone system flow diagram SR Vacuum Systems ASAC Review, 7/1718/2008 20 of 21 BROOKHAVEN SCIENCE ASSOCIATES 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 and is ready for evaluation Ozone cleaning systemSRdeveloped Vacuum Systems ASAC Review, 7/1718/2008 21 of 21 BROOKHAVEN SCIENCE ASSOCIATES
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