A Compact VesselStiffenerTuner for Double Quarter Wave Crab

A Compact Vessel/Stiffener/Tuner for Double Quarter Wave Crab Cavity Binping Xiao On behalf of the DQWCC team 12/13/2012 1 12/13/12

Outline �Double Quarter Wave Crab Cavity �Helium Vessel Design and Safety �Stiffener and Cavity Safety �Tuner Design, Sensitivity and Range �Magnetic Shielding �Next Steps �Summary �Reference 2 12/13/12

The Double Quarter Wave Cavity 390 296 362 3 12/13/12

Bare Cavity under Pressure Crab cavity max stress intensity vs Nb (bare cavity only) Max Stress Intensity [10 MPa] 100 90 80 Nb property: thickness • Modulus @ RT: 1. 03 e 11 Pa • Modulus @ Cryo: 1. 23 E 11 Pa • Poisson’s Ratio: 0. 38 70 Pressure: • 2 e 5 Pa (2 bar) outside • vacuum inside. 60 50 40 Fixed Support: 2 mm mesh size One side of beam port. 30 20 10 0 1 2 3 4 Thickness of Nb [mm] 4 5 6 Nb property for reference: • Density: 8. 58 e-3 g/mm^3; • Yield-RT: 4. 83 e 7 Pa (7 e 7 Pa for 300 RRR Nb) • Yield-Cryo: 12/13/12 5. 77 e 8 Pa.

Bare Cavity under Pressure (2) 5 12/13/12

Helium Vessel Design • Preliminary design of the helium vessel • The vessel will play a role in stiffening/tuning the cavity • Clearance for other beam lines in the vicinity. • Compact design which saves LHe • Stress relief connections to the coupling ports(not shown here) 6 12/13/12

Helium Vessel Safety 7 Ti property: • Modulus @ RT: 1. 02 e 11 • Poisson’s Ratio: 0. 338 • Yield-RT: >2. 76 e 8 Pa 12/13/12

Stiffener – Cavity Safety 8 12/13/12

Tuner - Design • Thermal leak from one drive shaft and piezoelectric wires. • Non backslash threaded rod (or differential screw) provides coarse tune. • Piezoelectric in series with threaded rod provides fine tune. • Step motor is attached to the cryomodule with a Conflat flange. 9 • Effectively use the space: give more space to couplers make the magnetic shielding 12/13/12 easier

Cavity Frequency [MHz] Tuner - Sensitivity Push/pull to tune 10 430 420 410 400 390 380 370 Tuning Sensitivity: 1. 93 MHz/mm 360 350 -10 -5 0 5 Change of distance between plates [mm] 12/13/12 10

Tuner – Elastic Push: 0. 42 mm Max Pull: 0. 38 mm Max 11 With 3000 N force Push: 2. 15 e 8 Pa Max 810 KHz 733 KHz Pull: 2. 03 e 8 Pa Max 12/13/12

Magnetic Shielding • Requirement: Less than 1 μT on cavity surface • Magnetic field 48 μT: Vertical 44 μT, Horizontal 20 μT (//pipe) • Material: 2 mm Cryoperm 10 with μr=150000 • Shield cavity, vessel, and loose fit to beam pipe 12 12/13/12

Magnetic Shielding (2) 13 12/13/12

Next Steps � The above analyses are based on 4 mm Nb wall thickness, solutions for 2. 8 mm are on going. � The cooling for HOM coupler/filters needs to be figured out. � Design/hardware for tuning system needs to be detailed. � Welding between cavity and vessel needs to be addressed. DQWCC project team @ BNL: Qiong Wu, Binping Xiao (Postdoc), John Skaritka, Vito De Monte, Sergey Belomestnykh, Ilan Ben-Zvi, Silvia Verdu Andres (Postdoc starting in Jan. 2013) Collaborators: Jerry Huang (BNL), Terry Grimm (Niowave), Luis Manuel Alberty Vieira, Rama Calaga (CERN) 14 12/13/12

Summary � An integrated vessel/stiffener/tuner solution is evaluated to keep the double quarter wave crab system compact, and to save liquid helium. � He vessel and cavity with stiffener meet the safety code. � Simple compact tuning mechanism clears the path for the other components. � Tuning system gives an “even” change on deflecting field. � Elastic tuning range: ± 0. 4 mm/ ± 770 KHz � Earth magnetic field shielding solutions for <1µT field on cavity surface are provided. 15 12/13/12

Reference � S. Belomestnykh, presentation, LHC Crab Cavity Engineering Meeting, Fermi Lab, Dec 13 -14, 2012 � Q. Wu, presentation, LHC Crab Cavity Engineering Meeting, Fermi Lab, Dec 13 -14, 2012 � Q. Wu, presentation, 2 nd Joint Hi. Lumi LHC-LARP Annual Meeting, INFN Frascati, Nov 14 -16, 2012 � R. Calaga, et. al. , A Quarter Wave Design for Crab Crossing in the LHC, Proceedings of IPAC 12, New Orleans, LA, May 20 -25, 2012 � Q. Wu, presentation, LARP CM 18/Hi. Lumi LHC Meeting, Fermi Lab, May 7 -9, 2012 � Q. Wu, S. Belomestnykh, I. Ben-Zvi, Novel deflecting cavity design for e. RHIC, Proceedings of SRF 11, Chicago, IL, July 25 -29, 2011 � R. Calaga, presentation, LHC-CC 11, CERN, Nov 14 -15, 2011 � I. Ben-Zvi, presentation, LHC-CC 10, CERN, Dec 15 -17, 2010 � P. Pierini et. al, Design of a magnetic shield internal to the helium vessel of RF cavities, Proceedings of EPAC 08, Genoa, Italy 16 12/13/12

Thank you. 17 12/13/12

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Tuner – Inelastic 30000 N force. Max deformation: 4. 05 mm. Max stress intensity: 2 19 12/13/12