Task Cryomodule. Paolo Pierini INFN Sezione di Milano - LASA

Transcription

1 Task Cryomodule Paolo Pierini INFN Sezione di Milano - LASA

2 Outline Schedule borrowed from Alex Karlsruhe presentation Aim of the task & work split Comment on existing cryomodule designs, trying to sort out the rationales behind them TTF SNS First educated guesses towards work PP 2

3 FI6W-CT : Integrated Project on European Transmutation (EUROTRANS) TASK GOAL: Design, construction and test of a full prototypical cryomodule of the high energy section of the proton linac. CO-ORDINATING CONTRACTOR: INFN (I) Paolo Pierini MILESTONES: M1.3.9: Preliminary cryomodule specifications (+9) M1.3.10: Cryomodule design finalized (+15) M1.3.11: Cryomodule is ready for test (+30) M1.3.12: Experimental results of performances (+39) M1.3.13: Final report: synthesis and design proposals (+42) DELIVERABLES: D1.3.7: Preliminary report: specifications for the cryomodule (INFN, +9) D1.3.8: Report on cryomodule design and schedule (CNRS, +15) D1.3.9: Final report: test results, synthesis and design proposals (INFN, +42)

4 Aim of the task (contractual 18 months) Q: 9? Q: 15? My understanding Specifications (D1.15 = D1.3.7) Make architectural choices to deal with ADS needs Review possible design with respect to the state of the art (SNS, TTF)» Get what we can, but no free meal Sketches (not drawings!) Back of the envelope calculations and estimations to support the choices Design and Schedule (D1.16 = D1.3.8) Milestone to see if it makes sense to go ahead (production) with the given funding and schedule, if we want to make a significative activity Proceed to confirm (or suggest alternatives) for choices above Somewhat detailed drawings of the vessel, shields and lines Checks with mechanical/thermal analysis the main choices Interfaces and logistics (RF, Cryo, ) PP 4

5 Split of the work for D1.3.7 (Specs) Architecture of the system Specifications: INFN with CNRS Dynamic load range Straightforward from design Alignment tolerances We did not start beam dynamics tolerances estimations in PDS-XADS, should be possibly a task for Less straightforward right now, assume SNS? Layout of the cold mass: INFN Interface to cryogenics: CNRS Interface to RF: CEA or CNRS? Couplers? Still weak point by now in terms of resources +9 form April means January 2006 Better start soon PP 5

6 Commentary on cryomodule designs TESLA [ borrowing transparencies from Carlo] SNS [ commenting published/unpublished material] APT TRASCO What are the rationales for each design? We cannot adopt any scheme if incompatible with ADS! PP 6

7 TESLA Cryomodule Design Rationales High Performance Cryomodule was central for the TESLA Mission More then one order of magnitude was to be gained in term of capital and operational cost Low static losses High filling factor: to maximize real estate gradient Long sub-units with many cavities (and quad): cryomodules (12-17 m) Sub-units connected in longer strings (2-3 km) Cooling and return pipes integrated into a unique cryomodule Low cost per meter: to be compatible with a long TeV Collider Cryomodule used also for feeding and return pipes Minimize the number of cold to warm connections for static losses Minimize the use of special components and materials Modular design using the simplest possible solution Easy to be aligned and stable: to fullfil beam requirements PP 7

8 Performing Cryomodules Three cryomodule generations to: improve simplicity and performances minimize costs Reliable Alignment Strategy Sliding 2 K Finger Welded Shields 2 thermal shields (4 K and K) Required plug power for static losses < 5 kw/(12 m module) PP 8

9 Cryomodules installed in TTF II ACC 5 ACC 3 ACC MeV 800 MeV ACC 4 & ACC 5 ACC 1 ACC MeV RF gun 4 MeV ACC 2 & ACC 3 PP 9

10 1 Prototype and 3 generations Mainly: Simplification of assembling & alignment strategy HeGRP is dominant in the cross-section Cry 1 Cry 2 Cry 3 Module 1 Module 2 & 3 Module 4 & 5 PP 10

11 From Prototype to Cry 3 Extensive FEA modeling (ANSYS ) of the entire cryomodule Transient thermal analysis during cooldown/warmup cycles, Coupled structural/thermal simulations Full nonlinear material properties Detailed sub-modeling of new components and Laboratory tests Finger-welding tests at ZANON Cryogenic tests of the sliding supports at INFN-LASA PP 11

12 Sliding Supports and Invar Rod Four C-Shaped stainless steel elements clamps a titanium pad welded to the helium tank. Rolling needles for longitudinal friction Cavities longitudinal position independent from the HeGRP contraction. x and y defined by reference screws Longitudinal position defined through an Invar Rod A model has been developed to measure real friction force and test extreme conditions Friction force: < 1 N PP 12

13 TESLA Cryomodule Concept Peculiarities Positive Very low static losses Very good filling factor: Best real estate gradient Low cost per meter in term both of fabrication and assembly Project Dependent Long cavity strings, few warm to cold transitions Large gas return pipe inside the cryomodule Cavities and Quads position settable at ± 300 µm (rms) Reliability and redundancy for longer MTTR (mean time to repair) Lateral access and cold window natural for the coupler Negative Longer MTTR in case of non scheduled repair Moderate (± 1 mm) coupler flexibility required PP 13

14 SNS Cryomodule Possibly more similar to ADS requirements Peculiarities!! PP 14

15 Design Rationales Fast module exchange and independent cryogenics (bayonet connections) 1 day 2K production in CM Warm quad doublet Moderate filling factor Designed for shipment 800 km from TJNAF to ORNL No need to achieve small static losses single thermal shield PP 15

16 Design for shipment (TJNAF to ORNL) 4 g 5 g g/2 Spaceframe concept PP 16

17 Around the cold mass Helium to cool the SRF linac is provided by the central helium liquefier He then piped to the 4.5K cold box and sent through cryogenic transfer lines to the cryomodules Joule Thomson valves on the cryomodules produce 2.1 K (0.041 bar) LHe for cavity cooling, and 4.5 K He for fundamental power coupler cooling Boil-off goes to four cold-compressors recompressing the stream to 1.05 bar and 30 K for counter-flow cooling in the 4.5K cold box Magnetic shields Vacuum chamber Tank 50 K thermal shield End Plate PP 17

18 4 BAR SNS He Flow HELIUM SUPPLY T.L. He Supply 4.5 K HELIUM RETURN T.L. He Return SUPPLY HP HELIUM COOLDOWN & POWER COUPLER RETURN GUARD VACUUM & RELIEF 20 BAR 20 BAR PHASE SEPARATOR LHe POWER COUPLER OUTER CONDUCTOR HEATER AT WINDOW Coupler and flange thermalization with 4.5 K flow END FLANGE HEAT STATION COUPLER HEAT STATIONS (2) 50K SHIELD COUPLER HEAT STATIONS (2) END FLANGE HEAT STATION 50 K Shield 20 BAR SURGE TANK 2K SUBCOOLER 2 K PP 18

19 SNS Cryomodule Assembly PP 19

20 Alignment strategy Indexing off of the beamline flanges at either end of each cavity Cavity string is supported by the spaceframe Nitronic support rods used to move the cavity into alignment Targets on rods on two sides of each flange. Each target sighted along a line between set monuments (2 ends and sides) The nitronic rods are adjusted until all the targets are within 0.5 mm of the line set by the monuments Cavity string in the vacuum vessel: the alignment is verified and transferred (fiducialized) to the shell of the vacuum vessel. PP 20

21 Modules during tests PP 21

22 And in ORNL (during PAC05) PP 22

23 The APT Coupler Dominated Case Huge power specs 100 ma cw! Everything built around coupler PP 23

24 The TRASCO Conceptual Design I-DEAS Student Edition : Design Short module, interchangeable, sliding supports, G10 frame Alignment transferred to rails in vessel Slide-in from side PP 24

25 First guesses for EUROTRANS Assuming two cavities, β=0.47 Coupler? Important component for boundaries on cryo design Preserve independence of modules (à la SNS) Easy connection/disconnection 2 K production at module Reliable interfaces (most troubles in SNS are leaks in iso vacuum) CNRS has much more cryogenics expertise than INFN CW machine, no need to design for low static losses Single thermal shielding at K is enough Choose an alignment strategy Fast and reliable Borrow, as much as possible, technologies from proven designs E.g. welding techniques for shields and sliding supports from TESLA PP 25