SR Chambers & RF Bellows

1. SR Chambers & RF Bellows H. Hseuh, Vacuum Group ASAC Review of NSLS-II Mar 26-27, 2009

2. Acknowledgements BNL: A. Blednykh, P. Cameron, C. De la Parra, S. DiStefano, L. Doom, M. Ferreira, E. Hu, F. Lincoln, C. Longo, S. Krinsky, V. Ravindranath, P. Settepani, S. Sharma, O. Singh, J. Skaritika, J. Sullivan, K. Wilson, …. ANL: J. Gagliano, G. Goeppner, … ESRF: R. Kersevan Diamond: M. Cox KEK: Y. Suetsugu SLAC: N. Kurita, M. Sullivan, L. Wang, U. Wienands, … TPS: J.R. Chen, G-Y. Hsiung, … and many others.

3. Outline • SR Vacuum Chambers and FY08 Effort • Material, quantity, types, fabrication • Extrusions w/ two vendors • Weld development of multipole chambers at APS • Prototyping and Testing Effort in FY09 • Bending of dipole extrusions • Extrusion of new multipole cross section • Weld development at APS • Testing of NEG strips and cal rod heaters • Interface with Magnets, AP, Diag. etc • RF Shielded Bellows • Design options and prototyping • Recent Review Recommendations

4. Cell Vacuum Chamber Layout ID Beamline S2 S3 S1 BM Beamline S4 L.S. S5 S1 S6 S.S. Stainless chambers • 60 stainless steel chambers, 1-2 m long • 5 types (cross sections, length, flanges, etc) • Stainless sheets, rolled, welded and brazed w/ Cu absorbers • 191 aluminum chambers, 3 – 6 m long • Extruded, two cross sections (dipole and multipole) • > 12 types (length, magnet cutouts, flanges, etc.) • Precision machining & welding to meet beam requirement Dipole Multipole

5. Cell Aluminum Chamber Types E: even cell; O: odd cell; DW: canted by ± 1.8 mrad Multipole also for day-1 straight Dipole S2-DW S2E S3-DW S2O S5 S4 90mm S3 & S5 S6E S3 S6O

6. Multi-step Fabrication of Al Chambers Lewis Doom Extrusion ➾ Bending ➾ Machining ➾ Cleaning ➾ Welding ➾ Assembly… BNL, V # 3,4,5. V #1,2 BNL APS APS BNL End adaptors Machined end Pump port Extrusions End adaptor End assembly Bi-metal flanges Machined extrusion Robotic welding at APS

7. Prototyping in FY08 Test extrusions completed Fabrication process fully developed for ‘old’ multipole chambers APS/ANL • Micrographs of welds show • Full fusion, no micro cracks • No void and trapped gas • Step ≤ 0.5 mm Prototype multipole chamber for alignment, BPM mounting, NEG carriers and bakeout 4mm X50 X15

8. Bending of Dipole Extrusion at BNL Lewis Doom Phil Settepani • 50 ton press break with 18-inch throat • W/ garnet filler, w/o filler • Change punch heights and load distributions – curvature to within 1 mm • Little spring back w/ thermal cycling to 180C • Gap reduction by 1 – 2.5 mm Spread the load outboard from the center will give more bending toward the ends. BNL CS break Fine tweaking the punch & shimms to get the exact bend!

9. New Multipole Extrusion & Weld Development Welding development at APS dipole, new multipole & exit port CD-2 Design Increase wall from 12 to 16 mm for improved BPM dual buttons/flange Short dipole chambers and flanges Multipole extrusion w/ exit port cutout New BPM flange New Old A multi-yr contract w/ APS is in place Test extrusion orders placed To be completed by May

10. NEG Strips and Carriers Lewis Doom Phil Settepani Two NEG strips in each aluminum chamber as main distributed pumping – total ~ 1,200m Riveted mounting every 10 cm w/ ceramic insulators and carrier plates Fully tested in prototype chambers Modified carriers for BPM TE modes? NEG strips in antechamber Feedthru Activation at 4500C x 30 min with 70 A thru NEG strips NEG carriers and feedthru

11. In-situ Bake with External Heaters Marcelo Ferreira Baseline design: 135oC x 150 psi water (as in APS and Spring-8) A major ES&H concern FY08 - T < 150oC achieved with foil heaters and insulation attached to limited magnet-free space (not a neat solution) FY09 – One Cal rod heater (10 mm φ) inserted in unused cooling channel > 120 C and ΔT < 5 C simple & versatile – to be tested for easy of installation and reliability

12. Interface with Magnets, AP and Diagnostics Provide APvacuum component models for impedance simulation and approval Worked with Magnet Measurement and identified issues with invar chamber supports, and fast corrector response over RF bellows/Al chambers – separate and relocate SC & FC Worked closely with AP on lattice improvement - 3rd family sextupoles, locations of 3PW, moving of sextupoles, etc RF shielding to shift the resonance frequencies of multipole chambers to > 550 MHz Animesh Jain Om Singh Interference from invar stands Separate SC & FC

13. Resonant Frequencies in Multipole Chamber Alexei Blednykh Electric field H101 Mode in a Rigid Waveguide 400MHz 1400MHz • Resonant frequencies measured in a 3.4m multipole chamber. • Agreed well with calculated H101 modes in a rigid waveguide. • Can be shifted by altering the chamber cross sections To shift the frequencies to > 550 MHz : - increase the slot height to > 15 mm - No - chamber width to < 80mm - No - ante-chamber height to  20 mm - No

14. Suppression of Rogue Modes Use modified NEG carriers to create shields in the ante-chamber ~ 150 mm from beam center, installed through end flanges ~ 500 mm long and ~ 300 mm spacing to shift Fo to > 550 MHz exact lengths and locations to be decided for each chamber type Fo ~ 385 MHz due to S4 absorber in extraction channel? Shields to be outside of SR fan or d/s of absorbers To be designed, prototyped and fully tested with NEG activations Alexei Blednykh 150 mm S4

15. Choice of RF Shielded Bellows Lewis Doom Marcelo Ferreira Inside fingersOutside fingers (APS, LNLS) (PEP II, Soleil, DLS, …) Simple, reliableLower impedance $$ $$$ outside fingers inside fingers NSLS-II RF Bellows Requirements: Max mis-alignment: ± 2 mm Max comp/extension: -15/+10 mm Max angle deviation: ±15 mrad Low impedance and low loss inconel springs Be-Cu fingers Consulted with many experts in other light sources Solid sleeve NSLS-II approach - outside fingers, few & wider fingers

16. Prototype Bellows Design Lewis Doom Marcelo Ferreira Hydro formed bellows welded to flanges with cooling channels 4 stainless inner support (Rh plated) 6 GlipCop fingers (0.9 mm thick Ag plated ) 4 Inconel outer springs (Ag plated ) 2 stainless clamping plate w/ groove for contact springs

17. Simulation w/ and w/o offsets At nominal position Kloss ≈ 2.0 x10-2 V/pC Alexei Blednykh 5” bellows 6” bellows With ± 2 mm offset Kloss ≈ 10 x10-2 V/pC With ± 2 mm offset Kloss ≈ 3.7 x10-2 V/pC Simulations of narrow finger bellows: Inside fingers : Kloss ≈ 1.9 x10-2 V/pC ± 2 mm offset ≈ 21.4 x10-2 V/pC Outside fingers : Kloss ≈2.1 x10-2 V/pC ± 2 mm offset ≈ 8.7 x10-2 V/pC • Thermal analysis with possible heat loads • Detailed production drawings and prototyping • Test for ease of assembly, mechanical stability with thermal cycling, etc.

18. TE mode interference to BPM Extensive studies by AP and Diag groups using chamber extrusions Modify NEG carriers to shift the frequency to > 550 MHz Clearance between magnets and vacuum chambers Increased from 1.5 mm to 2 mm at sextupole poles No foil heaters and insulation – cal rod heater in cooling channel To be tested with magnets RF shielded bellows design and RF fingers Consulted with colleagues from other light sources Preliminary design completed, being detailed and prototyped EPU gap (~ 8 mm) and maximum K values EDM the top and bottom walls of extraction gap in the S3 dipole (& S2 multipole) chambers to accommodate vertical photon fans ASAC Recommendations – July 08

19. Insitu bakeout and temperature uniformity - improved (ΔT < 5oC) with cal rod heater Extrusion tolerance and stress relief – straightened by machining vendor, < 1 mm relaxation after thermal cycling of bended extrusion NEG supports and protection – will be fully tested and with ground fault protected PS Effect of the vacuum components to magnets – ion pumps ok, invar supports not ok Asymmetric load on chambers due to thermal and mechanical force – analysis continues BPM buttons by welding – long development effort, can’t meet our current schedule 10,000 l/s pumping required at canted DW absorbers – pressure decreases with conditioning, only 1-2 locations Fast valve, Be window & RGA at FE – FV and RGA in the budget, Be windows to be reviewed together with BL Vacuum, FE & Support Review Recommendations – Aug 08

20. BPM position stability after repeated bakeouts To be tested using the prototype chambers Possible electron cloud Use CLOUDLAND by Lanfa Wang (SLAC) and NSLS-II staff with worst case parameters Ex & Ey mainly by electrons from reflected photons No multipacting, no instability, no emittance blowup H tune shift < -0.001, V tune shift < 0.0006 Fast ion instability High pressure d/s of canted DW, small impact only be ≤ 2 locations Need to simulate with beam fill patterns for ion clearing Construction Readiness Review Recommendations – Sept 08 Lanfa Wang

21. Summary • Cell vacuum chamber detail drawings continue – minor adjustment possible • Test extrusion of ‘new’ multipole cross sections continues • Machining and weld development of prototype chambers are underway • NEG strip supports developed and tested • Chamber bakeouts with cal rod heaters being tested • RF shielded bellows concept done, to be detailed, prototyped and tested • Work with AP & Diag. on shifting resonance frequencies using NEG carriers • Production of dipole chambers starts this summer, multipole by Dec • Next - Design and prototyping of absorbers and stainless chambers