1. Mechanical Design of Main Linac Cryomodule (MLC) Yun He, Dan Sabol, Joe Conway On behalf of Matthias Liepe, Eric Smith, James Sears, Tim O’Connell, Ralf Eichhorn

2. 2 Outline  Design criteria  Beamline and its support Beamline components Helium gas return pipe Support posts and alignment components Vacuum vessel  Thermal and magnetic design Post 40K thermal shield Magnetic shields Multi-layer insulation  Cryogenic environment Layout of cooling pipes 2K cooling loop  Materials, sizes and weights of sub-assemblies Yun HE, MLC External Review10/3/2012

3. 3 Design criteria Cryomodule provides support, alignment, cryogenic environment, thermal shielding and magnetic shielding for the cavities RequirementsDesign SupportBeamline is supported by HGRP onto three posts mounted on vacuum vessel Cryogenic environmentCavities are immersed in 2 K liquid helium bath Cryogenic piping is inside module, providing 2K, 5K and 40-80 K cooling Thermal shieldingInsulation vacuum to eliminate convective heat transfer by gases 40K thermal shield with multi-layer insulation to reduce radiation heat inleak Support system with low thermal conductivity material G10 Magnetic shieldingTwo layers of magnetic shields, one wraps cavity and the other on 40K shield AlignmentPrecision machined support interfaces with alignment pins/keys provides precision alignment at room temperature and allows for differential thermal contractions at cold VibrationSufficient supports to cryogenic pipes to increase the natural frequencies Yun HE, MLC External Review10/3/2012

4. Yun HE, MLC External Review4 Cross-sectional view of module HGRP Vacuum vessel 38” dia. OD Input coupler HGRP support post + alignment 40K shield + Mu-metal shield Rails 2K-2 Phase Cryogenic valves 4” 9.5” Cavity in 2K Helium bath

5. Yun HE, MLC External Review5 1.Beamline and its support Beamline string components Helium gas return pipe Support posts and alignment components Vacuum vessel 10/3/2012

6. 6 Beamline sub-assembly Taper HOM load SC magnets/BPMs Manual gate valve Beamline interconnection Pneumatic gate valve 9.8 m Beam Yun HE, MLC External Review  9.8 m long  six packages of 7-cell cavity/Coupler/tuner  a SC magnets/BPMs package downstream  five regular HOM absorbers/two taper HOM absorbers  A gate valve at each end to keep beamline a UHV unit One manual, to be opened once two modules are connected One pneumatic Cavity package with coupler, tuner and HOM absorber 10/3/2012

7. Alignment pins provides horizontal alignment 7 Supports for cavity Flexible support allows 1mm differential thermal displacement of helium vessel relative to HGRP during cool-down/warm-up Yun HE, MLC External Review Material: Ti Grade 2 LHe vessel supports 10/3/2012

8. Yun HE, MLC External Review8 Supports for other beamline components Alignment keys allow for differential thermal displacement of beamline components relative to HGRP 10/3/2012

9. 9 QuadsDipole BPMs Port for pre-cool SC magnets/BPMs package Port to 2K/2 phase line High temperature superconducting current leads Yun HE, MLC External Review10/3/2012

10.  Beamline (~ 1 Ton) is suspended under HGRP via three support posts Center post fixed, side posts allow differential contractions during cool-down  Material : Grade 2 Ti, ID Φ280mm, wall thickness 9.5mm Similar thermal expansion rate with niobium Does not need transition for being welded to Nb Sliding post Fixed Point Sliding post 10 Beamline strongback - Helium gas return pipe High precision machined mounting surfaces with central pin holes Provide precision alignments of beamline components Yun HE, MLC External Review10/3/2012

11. Yun HE, MLC External Review11 Helium gas return pipe -- production steps  Final precision machining of top and bottom surfaces and pin holes with one set-up  Heat treatment to relieve internal stress? 10/3/2012

12. Adjust post position Bellows 12 Support post -- alignment components  Three posts connected to HGRP to support cold mass ( ~3 Ton)  Posts are fastened to suspension brackets  Adjustable brackets allow alignment of cold mass position to vacuum vessel references Post Suspension bracket Yun HE, MLC External Review Vacuum vessel top flange HGRP 10/3/2012

13. Port for coupler Port for instrumentation and access to tuner Hanger for lifting & transportation Ports for GV & SC magnets Port for post Ports for cryogenic valves Rails for cold mass insertion ɸ 37-1/4” ID, 3/8 Thickness  Material: 38” OD x 3/8” wall carbon steel cylinder SS 316L for all flanges  Lining with Co-Netric mu-metal shielding Or a mu-metal shield on 40K shield? To be decided  Painted: interior with polyurethane and exterior with marine paints  A top port for spring-loaded gas relief disk (ID 4”) to prevent insulation vacuum from over pressurization in case of accidental spills of LHe 13 Vacuum vessel Yun HE, MLC External Review10/3/2012 Port for pressure relief

14. 14 Vacuum vessel – reinforcements and references Stiffening rings to top port Reference arm for survey target Cross-section of top port Reinforcement around the opening Yun HE, MLC External Review10/3/2012 SS flange with O-ring seal Brackets for waveguide supports

15. Yun HE, MLC External Review15 Vacuum vessel – production steps 10/3/2012 Weld supports/end flanges Align end flanges holes within 0.1° 0.002” flatness/coplanar/parallelism for bottom plates to vessel cylinder reference and each other Drill the holes Weld side flanges and brackets for waveguide supports Weld top flanges and survey arms Weld rail supports and align them within 0.02” Final machining on all flanges’ sealing surfaces, holes on bottom supports and waveguide brackets Precision machining of survey arms Install rails

16. Yun HE, MLC External Review16 2.Thermal design Support post 40K thermal shield Magnetic shields Multi-layer insulation 10/3/2012

17. 2 nd stage -- 5K intercept (Al) 5K braids clamped to 5K manifold 3 rd stage -- 40K intercept (Al) 2K HGRP 300K G-10 tube 17 Support post – thermal design  A major source of heat leak via conduction  Same design/size as those in TTF, supports up to 5 Ton weight Material: Fiber reinforced plastic (FRP) G10, low thermal conductivity, from ACPT  Four stages of shrink-fit metal discs/rings, with MLI on intercept discs Conduction 4 th stage -- 300K (SS 316L) 1 st stage -- 2K (SS 316L) 40K shield Yun HE, MLC External Review10/3/2012

18. 18  Plan to use the same company who built the posts for ILC cryomodule  Four stages of shrink-fit metal discs/rings, w/ interferences of 0.15-0.3 mm Support post – production steps G10 tube Al disk Tooling Cool down Al disk along with tooling to LN 2 Put on G10 tube Press top plate Let assembly #1 warm up to room temperature Al ring Warm up Al ring along with tooling to 200 o C Put on assembly #1 Let assembly #2 cool down to room temperature Step #1Step #2Step #3Step #4 Step #5 Step #6 Step #7 Step #8 Step #1 Step #2 10/3/2012Yun HE, MLC External Review Then repeat Step #2 & #3

19.  Three sections, each mounted on a post, fixed joint on middle post and flexible joints on side posts  Three sections are rigidly connected by intermediate covers as a whole  Material: Al 1100-H14, high thermal conductivity and light weight + Mu-metal (?, to be decided) + MLI (30 layers)  40-80 K helium gas cooling in extruded pipe which is welded to upper sheet  Shield sheets are connected by fasteners  Venting holes to prevent excessive pressure build-up in case of accidental spills of LHe Top sheets (1/4” thick) support 40-80 K manifolds and lower portion of the shield Intermediate cover connects two adjacent sections Lower sheet, 1/8” thick Extruded pipe to supply 40K helium gas cooling 19 40K thermal shield – general information Yun HE, MLC External Review Fixed Point Sliding post A cone shaped shield will be attached to the coupler penetration opening 10/3/2012

20. welded Array of 1”x2” fingers with 0.08” gap bolted welded Fingers increase the elasticity, reduce thermal stress due to temperature gradient during cool-down 40K thermal shield – finger welding 40-80 K cooling pipes 20Yun HE, MLC External Review10/3/2012

21. 21 40K thermal shield – materials  Al 1100-H14 for shield high thermal conductivity and high strength It is used on Injector cryomodule/HTC thermal shields – good workability  Al 6063-T52 (or T6), for extruded pipe TemperatureTensile strengthYield strength Al 1100-H1477 K205 MPa140 MPa 300 K125 MPa115 MPa Al 6063-T524 K385 MPa250 MPa 300 K220 MPa195 MPa Data from AMS handbook Data from Cryogenic materials data handbook Yun HE, MLC External Review10/3/2012

22. 22 Magnetic shields and multi-layer insulation  Two layers of magnetic shielding  A sheet of Mu-metal 4K (0.04” thick A4K) shield on the cavity LHe vessel Hydrogen annealed after welding for optimal performance at 2K Mounted in half shells; Perm nuts for joining the overlap seams  A sheet of Mu-metal (0.02” thick A4K) shield on 40K shield or lining on vacuum vessel?  Multi-layer insulation (MLI) blankets 30 layers on the 40K thermal shield 5 layers on He vessel, HGRP, all cryogen pipes  Venting holes to prevent excessive pressure build-up in case of accidental spills of LHe Yun HE, MLC External Review10/3/2012

23. Yun HE, MLC External Review23 3.Cryogenic environment Layout of cooling pipes 2K cooling loop 10/3/2012

24. 24 Cryogenic manifolds HGRP 1.8K gas 6K return Gas @3 bar 80K return Gas @18 bar 2K-2 Phase 1/3 full level 4.5K supply Fluid @3 bar 40K delivery Gas @20 bar 40K supply Gas @20 bar 2K supply subcooled liquid @1.2 bar 2K Yun HE, MLC External Review10/3/2012  Six lines of ɸ 50 mm pipes @ 2K, 4.5-6K, 40-80K running half-linac length  Each cryomodule has local manifolds with the flow adjusted by four valves

25. Material of 2K-2 phase, HGRP pipes and LHe vessel Grade 2 Ti Similar thermal expansion rate with niobium Does not need transition for being welded to Nb 25 2K cooling loop Yun HE, MLC External Review 2K-2 phase 1/3 full, monitored by a level sensor ɸ 87 mm, adequate area for superfluid counterflow Chimney w/ large cross-section for gas flow to HGRP HGRP Φ280mm 9.5mm wall Cavity immersed in 2K helium bath Large diameter provides low impedance for large mass flow 10/3/2012 A JT valve controls liquid helium to 2K-2 phase line 2K-2 phase pipe feeds helium to helium vessels of cavities and SC magnets Vapor returns back to cryogenic feed box via HGRP through single connection in the middle

26. 26 2K-2 phase pipe  A bellows section in chimney allows differential thermal contractions of beamline vs. HGRP during cool down  A welding lip allows cut-off/re-weld a mal-functional cavity A few supports attached to HGRP to increase pipe’s natural frequency Yun HE, MLC External Review Kapton thermofoil heater, to keep the refrigeration load constant when RF power is off 10/3/2012

27. 27 Material and size of sub-assemblies MaterialSize Beamline6 sets of cavity/coupler/HOM/tuner 1 set of magnets/BPMs 9.8 m Vacuum vesselCarbon steel9.15 m x Ф 0.96 m Helium gas return pipe 2K-2phase pipe Ti, grade 29.65 m x Ф 0.28 m 9.65 m x Ф 0.10 m Support postG10 (FRP) w/ Al & SS rings/disks 40 K thermal radiation shieldAl 1100-H14 Al 6063-T52 9.65 m Upper: 6.35 mm thick Lower: 3.175 mm thick Cryogenic pipingSS 316L Five Φ50mm pipes + local distribution pipes Interconnection moduleCarbon steel Cryo-feed entry moduleCarbon steel2.2 m Yun HE, MLC External Review10/3/2012