Top Loading vs. Butter Dish Design (Bottom up) for Quarter and Half-wave Cavity Cryostats

1. WG4 TopLoadingvs.ButterDishDesign (Bottom up)for Quarter and Half-wave Cavity Cryostats K. Saito on behalf of S. Miller SRF Development Manager

2. Cryomodule Design General and FRIB Design • Alignment tolerance requirement from beam dynamics • Tighter in Heavy ion LINAC due to the smaller bore radius:40mm • Assembly-kindly structure design • Higher reliability in cryomodule assembly • Efficient assembly rate: one module/month, cost reduction • Low static heat load • Design experience • FRIB design based ReA experience • Top loading cryomodule designs world widely for low-b structure, next slide • FRIB chose bottom-up assembly design • Small bore radius (40 mm) requires tight alignment tolerance K. Saito, WG4 , TTC meeting 201902 TRIUMF

3. Cryomodule DesignLow- cryomodules examples world wide • Top-loading CM design world widely for low-b structures TRIUMF ISAC2 (QWR, top down) operating –common vacuum ANL ATLAS (QWR, top down) operating IFMIF EVEDA under prototyping (HWR, top down) FNL PXIE proposal (SPOKE) ReA MSU (QWR, top down) =0.041 QWR CM operating INFN Legnaro (QWR, top down) operating–common vacuum K. Saito, WG4 , TTC meeting 201902 TRIUMF

4. FRIB Bottom up Assembly • Coldmass on the baseplate • Assemble every component on the coldmass: magnetic shields, cryogenic piping, thermal shield • Cover the vacuum chamber from top WG4 K. Saito, TTC meeting 201902 TRIUMF

5. Six Cryomodule Designs for FRIBAll same design:Bottom-upassembly • Cavity 2K operation, solenoid package 4K operation (needs vapor cooling for current leads). • All six modules using the same bottom-up design approach • All cryomodules share large portion of common components to simplify design and facilitate fabrication. • Collaborate with JLAB on cryomodule design (β=0.041 and β=0.29) • Collaborate with ANL on coupler and tuner design β=0.085 Matching β=0.085 β=0.041 β=0.29 β=0.53 β=0.53 Matching K. Saito, WG4, TTC meeting 201902 TRIUMF

6. FRIB Cryomodule Alignment Approach and Establishments • Rigid baseplate provides stable and reliable platform for the coldmass • Three divided baseplates minimizes thermal contraction (0.085 and 0.53 CMs) • Small longitudinal contraction distortion for outer conductor of the FPCs • Alignment of cold string is achieved by control stack tolerance of coldmass and baseplate. • Transverse/Vertical error: ~0.5 mm at RT, cooldown error < 0.33 mm • Rails are made of 316L and annealed before final machining to minimize distortion during fabrication, cool down, and magnetization • No post assemble alignment adjustment needed X-Y movable post Fixed post Cryomodule Alignment Survey Results at RT. * Cool down error is projected to be < 0.33 mm K. Saito, WG4, TTC meeting 201902 TRIUMF

7. FRIB Cryomodule AssemblyCryomodule assembly bays in East highbay Bay #4 Bay #3 Bay #5 Bay #2 Bay #1 Subassembly Fabrication • Four bays for cryomodule assembly • 2 overhead cranes • 2 loading bays for coldmass and completed cryomodule transport • Assembly space for subcomponents (solenoid leads, O-rings, G-10 posts) • Fifth assembly bay for header assembly • Cryomodule assembly rate: 1.2 CMs/month overall K. Saito, WG4, TTC meeting 201902 TRIUMF

8. Cryomodule Assembly Rate • Cryogenic pip-welding > 300 pieces • 5 assembly areas and workers 15 including 5 welders • Established effective assembly rate: 1.2 CMs/month Cryomodule assembly rate; 1.2 CMs/month overall K. Saito, WG4 , TTC meeting 201902 TRIUMF

9. Established Benefits in FRIB Bottom-up Assembly • Tight assembly alignment established • < 1 mm (RT assembly + cooldown error) • 100% Argon beam transfer within a few days in the beam commissioning (0.041 first 3 CMs) • Almost no beam kick by steering coils in the first cryomodule beam commissioning, more results in the next beam commissioning for LS1 • High efficient assembly rate • 1.2 CMs/month with 5 assembly areas and 15 workers K. Saito, WG4, TTC meeting 201902 TRIUMF

10. Static Heat Loads • Solenoid package 4.5K operation (needs vapor cooling for current leads) and cavity operation 2K • Coupler static heat loads occupies about 40% for 2K static heat load and 60% for 4K, next slide. • Meets FRIB specification within measurement error (10-15%), except 0.085QWR 2K statics, which is under investigating. • However, it is compensated by high Q performance K. Saito, WG4, TTC meeting 201902 TRIUMF

11. Static Load Calculation Example: 0.53HWR CM Main Components • HFP static heat loads occupies about 40% for 2K static heat load and 60% for 4K • Vapor cooling current leads of solenoid package is essential. To reduce 4K static heat load. ~ 0.1W/one lead with vapor cooling, ~ 0.5W without cooling, • 3W (=0.5 x 6) for one package! K. Saito, WG4, TTC meeting 201902 TRIUMF

12. Summary • The bottom up assemble has been confirmed the excellent aliment error in the FRIB cryomodule • The efficient assembly rate was confirmed. • Static heat load (4.5K and 2K) meets FRIB specification. K. Saito, WG4, TTC meeting 201902 TRIUMF