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Crab cavities – cryogenic circuit and heat loads

Crab cavities – cryogenic circuit and heat loads. LHC crab cavity engineering meeting – Fermilab , USA 13-14 December 2012 K. Brodzinski on behalf of cryogenic team at CERN. Contents. Cryogenics in SPS BA4 (regarding 2 K refrigeration)

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Crab cavities – cryogenic circuit and heat loads

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  1. Crab cavities – cryogenic circuit and heat loads LHC crab cavity engineering meeting – Fermilab, USA 13-14 December 2012 K. Brodzinski on behalf of cryogenic team at CERN

  2. Contents • Cryogenics in SPS BA4 (regarding 2 K refrigeration) • Capacity limitations with existing infrastructure • Cryogenic circuits • Available space – integration • Helium availability • Cryostat design – analytical approach • Cryostat circuits • Instrumentation • Heat loads • Pressures, protection and safety, operation aspects • Helium volume and other practical aspects • Budget • Planning time line (for SPS and P4 testing) • Concept of LHC P1 and P5 cryogenics • Conclusions K. Brodzinski - CC_Fermilab 2012

  3. Cryogenic infrastructure in SPS BA4 Crab cavity cooling at 2 K  TCF20 cryoplant used in pure liquefaction TCF20 means 20 l/h = 0.7 g/s of LHe TCF20 T-S Diagram CC x 2 Guaranteed capacity: 87.5 W @ 4.5 K (i.e. isentropic equivalent to ~0.85 g/s of liquefaction) black –> existing 4.5 K red –> to be constructed 2 K K. Brodzinski - CC_Fermilab 2012

  4. Capacity limitations of TCF20 120 W @ 4.5 K available in refrigeration mode ! (+ 35 %) Giorgio Passardi Liquefaction capacity line [g/s] 0.7 0.85 1.2 Conclusions: Liquefaction capacity measurement mandatory to confirm cooling possibility @ 2 K K. Brodzinski - CC_Fermilab 2012

  5. Sulzer-Linde TCF20 in BA4 At SPS BA4 there is a 4.5 K cryogenic infrastructure used last time about 8 years ago for COLDEX experiment. It is foreseen to test its capacity and upgrade it for 2 K refrigeration – refurbishment is underway Revised, labeled and qualified pressure control system / oil removal system Renovated compressor + elec. motor – run test done Cold box TCF20 New power supply panel for compressor station 2 K pumping groups recovered from AMS K. Brodzinski - CC_Fermilab 2012 TCF20 Cold box

  6. Cryogenic circuits Regarding 2 K refrigeration R Service module JT CC cryostat Screen Coupler intercept End cone intercept CC x 2 End cone intercept EH EH EH EH EH EH TT PT TT TT TT TT TT LT black –> existing 4.5 K red –> to be constructed 2 K Screen K. Brodzinski - CC_Fermilab 2012

  7. Cryo integration in SPS heater SM TCF20 Very tight integration if going behind the beam line (preferable because of distances to the client and free space in access gallery). K. Brodzinski - CC_Fermilab 2012

  8. Helium availability BA4: one 8 m3 GHe tank – operation pressure is assumed at ~ 10 bara ~13 kg of helium For operation is assumed that ~9 kg of helium would be liquefied  60 dm3 of LHe volume TCF20 phase separator volume – estimated up to ~ 20 dm3 Conclusion: The CC x 2 cryostat should not be bigger than 40 dm3 (if reasonably possible) Remark:The above approach is the first estimate taking into account the reliable operation. If more flexibility required for the cryostat, appropriate solutions may be applied (e.g. renovation of special inter-sites supply and recovery lines, second tank …). Supply 200 bar from north zone 8 m3 Compressor Recovery line to north zone Buffer line Connection with battery K. Brodzinski - CC_Fermilab 2012

  9. Cryostat design – circuits 1/2 Option 1: cold box is able to cover all heat load requirements. 50 K OUT J-T for 2 K IN 4.5 K IN 2 K OUT Coupler intercept End cone intercept CC x 2 End cone intercept Screen 290 K OUT • Interfaces: • One flange for 4 cold process pipes • Three small tapping for helium gas recovery • One tapping for SV of 2 K helium tank (with helium guard) • One tapping for SV on the vacuum jacket • Instrumentation – as shown on the sketch above (PT, TT and LT on the helium bath) EH EH EH TT TT TT PT TT LT EH 9 K. Brodzinski - CC_Fermilab 2012

  10. Cryostat design – circuits 2/2 Option 2: cold box is NOT able to cover all heat load requirements (boost necessary – LN2 circuit added for intercepts, N2 solution is not recommended in the tunnel ). GN2 OUT J-T for 2 K IN LN2 80 K IN 2 K OUT Coupler intercept End cone intercept CC x 2 End cone intercept Screen • Interfaces: • One flange for 2 cold process pipes • Two tapping for N2 circuit – inlet and outlet • Three small tapping for N2 gas recovery • One tapping for SV of 2 K helium tank (with helium guard) • One tapping for SV on the vacuum jacket • Instrumentation – as shown on the sketch above (PT, TT and LT on the helium bath) EH EH EH TT TT PT TT LT TT EH Is it acceptable to have coupler and end cone intercepts at ~80 K? 10 K. Brodzinski - CC_Fermilab 2012

  11. Instrumentation Instrumentation proposal is presented below. Regulation – loop with GHe outlet valve 50 K OUT J-T for 2 K IN 4.5 K IN 2 K OUT Protection and safety devices Regulation – loop with LHe supply valve Coupler intercept End cone intercept CC x 2 End cone intercept Screen Cold gas warming and regulation at 290 K 290 K OUT Indication – probably can be used for regulation if PT fails Cold gas warming and regulation at 290 K For He evaporation/stabilization … EH EH EH TT TT TT PT TT LT EH The type of instrumentation (technology), range, power (for EH) are not defined yet and will be discussed with related instrumentation and control engineers. 11 K. Brodzinski - CC_Fermilab 2012

  12. Service module – circuits The Service Module is to be designed and ordered/produced by CERN. Subcoolingheat exchanger and JT valve are to be integrated in dedicated service module. GHe OUT LHe IN JT Screen (He or N2) Cryostat EH TT K. Brodzinski - CC_Fermilab 2012

  13. Heat loads 1/3 Main open questions: Will we have for SPS test a common cryostat for 2 cavities or 2 cavities in separated cryostats? Common cryostat: + lower total static heat load + simple distribution system - direct influence of one cavity on the other (quenches) - difficult replacement of one cavity (regarding third cavity testing in SPS) What will be approach for LHC final destination? SPS configuration should be as close as possible with decisions foreseen for LHC if possible. K. Brodzinski - CC_Fermilab 2012

  14. Heat loads 2/3 Assumptions received/presented by two suppliers: The values are for one module with 2 cavities (with request to comment on orange values). ? ? Very rough estimation at max. 2 W for SPS Incorrect values (capacity discussed on slide 3 and 4) From ShrikantPattalwar K. Brodzinski - CC_Fermilab 2012

  15. Heat loads 3/3 From Jean Delayen – Frascati 2012 K. Brodzinski - CC_Fermilab 2012

  16. Heat loads and TCF20 capacity Service module: 0.8 W@2 K, 2 W@4.5 K, 80 W at 80 K (e.g. taken out with latent heat of LN2) Module with 2 cavities (static + dynamic) without safety factors: 7.2 W @ 2 K, 4.5 W @ 4.5 K ?, 148.2 W @ 60 K ? Could be a difficult limit Putting all together: 8 W @ 2 K, 6.5 W @ 4.5 K ?, ~230 W @ 80 K Liquefaction capacity line [g/s] 0.7 0.85 1.2 8 W @ 2 K(~0.4 g/s) 6.5 W @ 4.5 K(~0.33 g/s) Transfer and screen …? Exercise for screen: Assumptions: available GHe@5K, heat load of 230 W on screen, outlet GHe temp at 80K -> 0.6 g/s of flow is needed It means that: 100 liter dewar would be empty in ~6 hours. • Preliminary conclusions (for thermal aspects we know today): • one cryostat for 2 cavities in the best case or only one cavity test to be done • using of LN2 seems to be an obligation K. Brodzinski - CC_Fermilab 2012

  17. Cryostat operation – first approach • Pressures – safety : • The cavity should be designed to withstand external pressure of 2.6 bara (deltaP = 2.6 bar) at ambient temperature without plastic deformation, • Design pressure for the cryostat should be based on installed safety devices according to design rules (cryostat equipped with a rupture disc set at 2.2 bara and safety valve set at 1.8 bara) • both safety devices should be placed on the cryostat in the way to avoid potential projection of helium towards the passages or transport area (deflectors installation to be analyzed), • Both safety devices should protect cavity and cryostat from pressure rise causing plastic deformations • Operating pressure during the cool down can oscillate between 1.2 and 1.5 bara – estimation, • Normal operation pressure will be set at ~ 20 mbara (for 2 K cooling) • Cool down – stable operation – warm up: • Cool down will be done with direct filling of LHe to the cavity cryostat, very roughly estimated cool down time is ~ 1 day • Stable operation availability will be affected by impurities in the system (there is no purifier installed in the infrastructure). A few days continues availability should be guaranteed. • Warm up of the cavities will be done by natural evaporation of helium and temperature floating towards 300 K (additional heater on the helium bath can be used to speed up the process) 17 K. Brodzinski - CC_Fermilab 2012

  18. Helium volume Estimation of needed helium volume in the cryostat – for one cavity. • Assumptions: • Cavity in shape of a cylinder (D=175 mm, Lcav=700 mm) • Helium layer of L mm of thickness analyzed (see data below) • Head of additional Lc=50 mm layer of He taken above the cavity (see figure below) Lc Volume C L D Volume B Lcav L Volume A Volume A – layer of L mm of helium, Volume B – additional helium volume Volume C – additional head of helium for transients(for C=7dm3 -> ~30 min for head evaporation, loading at 20 W) “The CC x 2 cryostat should not be bigger than 40 dm3 (if reasonably possible)” Operation with one buffer tank of 8 m3 is limited … 18 K. Brodzinski - CC_Fermilab 2012

  19. GHe return collector Recommendations coming from LHC cryogenics operation. LHC RF GHe return line (too low for reliable level regulation) Volume of ~10 – 15 liters is to be respected (without collector) ~100 mm ~ 30 mm GHe return collector should be placed on side as presented in above sketch, with reasonable distance above LHe level (~ 100 mm)  for reliable level regulation (avoiding LHe presence in return line). The supply tapping is recommended to be placed in gas volume “far” from outlet pumping ports for efficient separation during the filling. 19 K. Brodzinski - CC_Fermilab 2012

  20. Crab-cavity test in SPSAdditional specific 2 K equipment Refurbishment of existing equipment (4.5 K) 150 kCHF Sub cooling heat exchanger 12 kCHF Warm pumping unit (WPU) 100 kCHF He guard for pressure relief valves 10 kCHF VLP heater 20 kCHF JT expansion valve 4 kCHF Service Module + piping 50 kCHF Total ~350 kCHFRemarks: 1. some additional cost for cryostat design can occurred e.g. beam screen circuit on second beam pipe2. if WPU cannot be installed underground, a new VLP line must beintegrated in the BA4 shaft (DN100 – 20 kCHF)3. No specific purifier foreseen for impurity management of the VLP circuit, i.e. availability affected in case of 2 K refrigeration. K. Brodzinski - CC_Fermilab 2012

  21. Tentative SPS CC cryogenic schedule • Surface equipment (GHe storage, compressor station and oil separation system) – refurbishment completed (run test done on 28.11.2012) – first results OK • Cold box refurbishment is underway – run test on the beginning of LS1 • Installation of liquefaction test instrumentation and test performance – by 15 June 2013 (cut of cooling water in SPS BA4 until ~ 15 September 2013). • Development, installation and commissioning of 2 K equipment by end of LS1 • Remark: • Integration of 2 K cryo equipment in the tunnel looks tight – if not possible  heavy complications – possibility of mentioned transfer line construction in the shaft to the surface = more logistics, more manpower and time required. K. Brodzinski - CC_Fermilab 2012

  22. Crab cavity test at Point 4 • Is this test essential and really necessary to be performed ? • If yes and if before availability of new cold box hard difficulties appears: • Existing cryo distribution to be modified and test performed at 4.5 K • Existing cryo distribution to be modified and 2 K pumping system to be added • TCF20 from SPS to be relocated … • The global scheme is no longer an option for the final HL-LHC, but a prototype cavity could be installed in Point 4 after the tests in SPS. • Installation of CC prototype could be: • Coupled to the RF cryogenic upgrade at P4 with 2 K equipment to be added • Scheduled during the LS2 (2018) for possible validation tests during 2019/20/21 (before the LS3 for P1/5 upgrade). K. Brodzinski - CC_Fermilab 2012

  23. Cooling of CC modules at P1 and 5 • Remarks: • It is probably preferable to link the CC with new refrigerators for ITs, if not we will recreate currently existing in s3-4 and 4-5 unbalance which has justified upgrade of cryo at P4 • Studied schemes of cryogenic upgrade for HL-LHC at P1 and 5 were presented in Frascati on Friday 16.11.2012 at 10h00 “Cryogenics for HL-LHC” by Laurent Tavian • https://indico.cern.ch/conferenceTimeTable.py?confId=183635#all.detailed Existing Cryo plants P5 Sector 5-6 LHC RFs Sector 4-5 Sector 3-4 New Cryo plant for RFs New Cryo plant for ITs and … CC • Two possibilities: • Via the 2 new cryoplants dedicated to the new inner triplets at IP1 and IP5 or • Via the 4 existing adjacent-sector cryoplants • The choice will depend strongly on: • the operating temperature of the new Inner Triplets (IT): 4.5 K vs 2 K • the total added heat loads K. Brodzinski - CC_Fermilab 2012

  24. P1 & P5 layout 1: Matching section cooled with sector cryoplants P1 or P5 S81 or S45 S12 or S56 Frascati 2012 by L. Tavian K. Brodzinski - CC_Fermilab 2012

  25. P1 & P5 layout 2: Matching section cooled with inner triplet cryoplants P1 or P5 S81 or S45 S12 or S56 Frascati 2012 by L. Tavian K. Brodzinski - CC_Fermilab 2012

  26. Conclusions • Prototype crab-cavity testing in SPS: • Test possible from end 2014. • Refrigeration at 2 K: • liquefaction capacity of the TCF20 must be measured and sufficient. • Additional resources (P + M) must be allocated. • Additional 2 K infrastructure to be built – could be in conflict with the LS1 activities – tight to be integrated. • Prototype crab-cavity testing at LHC P4: • If test necessary before availability of a new cold box -> difficulties for infrastructure • 2 K cooling (~1 MCHF + 2 FTE + a possible noise-insulated building tension/construction…?). • Series crab-cavities for the final HL-LHC local scheme: • Cryogenic implementation during the LHC LS3 (2022) • 2 K cooling via new ITs cryoplants preferable: • Option for Matching Section area to be cooled by the same new cryoplant • Cooling with existing sectors cryo plants not excluded but with load unbalance wrto the other LHC sectors K. Brodzinski - CC_Fermilab 2012

  27. Discussion Remind of main open points: • Is it acceptable to have coupler and end cone intercepts at ~80 K? • Heat loads clarification at 5 K and 60 K (for 4R cavity) • SPS test – common or separated cryostat? • Is the P4 test really necessary? (if yes -> When? At what temperature?) • … THANK YOU FOR YOUR ATTENTION ! K. Brodzinski - CC_Fermilab 2012

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