1. Cryogenic system in P4: Possible options S. Claudet & U. Wagner LHC Workshop, “Chamonix XlV” January 2005 (Mostly for RF & beam scrubbing)

2. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Content  Brief recall of present situation  Concerns –Cooling capacity –Pressure stability –Coupling with items operated at higher pressure –Periodic cavity conditioning and developments  Possible alternative cooling schemes  Summary

3. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Getting familiar with the subject  LHC Design report, p 134 for description of ACS cryogenics and requirements  Schematic views: –Single cavity module:LHCACSGA0006 –QRL sector 3-4:LHCLSQR_0041 –QRL sector 4-5:LHCLSQR_0042  Minutes of meetings between RF & Cryo  Minutes of LHC Hardware Commissioning Global overview ?!? Interface to be further studied & finalised !!!

4. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Layout UX45, top view ACS QRL QUI QURC

5. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Layout UX45, side view ACS QUI QRL WRL

6. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Cooling capacity (1/3) InjectionNominal Maximum operation Absolute Maximum MV/m 2.755.58.2511.0 Static W 150 Margin W 25 Dynamic W 25100225 Total W 200275400950 “LHC Design report”, recently completed by AB/RF

7. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Cooling capacity (2/3) Chamonix 2004, p 252 Equivalent capacity [kW] Some margin left at Nominal mode Nominal mode: no need for capacity upgrade

8. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Cooling capacity (3/3) Chamonix 2004, p 252 Equivalent capacity [kW] Lack of capacity of the 4.5 K Refrigerators Ultimate mode: obvious need for capacity upgrade

9. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Capacity for beam scrubbing Chamonix 2004, p 253 Equivalent capacity [kW] Turbine upgrade decided in 2004, (contract F529) Cooling capacity in line with hydraulic capacity of beam screens

10. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Pressure stability (1/2) Pressure [mbar] LHe level [mm] SM18

11. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Pressure stability (2/2) Request: 1.350 bar ± 15 mbar Nota: LHe level control at low possible value will increase GHe volume for intrinsic pressure stability Pressure [mbar] SM18 Try with Line D (60m3) as buffer and return valve in QUI for Pressure control If not OK, then use return control valve of module for Pressure control

12. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Coupling via return line D (1/3)  During some operating modes, QRL - Line D will be operated at pressures above Cavities Maximum Allowed Working Pressure Cool-down: 3.5 B to 1.3 B Sector quench: 6 to 15 B Warm-up: 1.3 to 3.5 B 2.0 BSafety device 1.550 BBeam Dump 1.500 BHigh Voltage off 1.450 BRF off 1.350 BNominal value

13. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Coupling via return line D (2/3) Normal cooldown of a LHC sector 300-4.5 K Start of ACS and DFBs cooldown Initial ramp: dTmax* < 75 K * max temp. difference across magnet Chamonix 2004, p 206 LHC Project Workshop, Session 6 - Chamonix January, 21 2004 G. Riddone, AT Department + 2 d to 1.9K Cool-down of ACS to be started when QRL- line D pressure is low enough Compatible with overall schedule

14. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Coupling via return line D (3/3) Industrial cryogenic check-valve installed in refrigerators, DFB’s

15. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Conditioning & tests requirements  Commissioning or conditioning: –After installation before beam:6 months –After yearly warm-up to 300 K:1 week –After a short stop (T ≤ 50 K):1-2 hours Not critical, even if frequent quenches at the beginning Could be a good idea, but not yet the baseline !!!  Repeated request: –“Need to have the possibility of doing RF work if machine is down for some time (magnet replacement, …)”

16. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Simplified cooling scheme C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Warm recovery line (≤300 K; ≤1.1 bar) 4.5 K Refrigerator QUI QRL SC Cavities Safety System Fall-back for “low intensity” HP MP LP Warm Compressor Station Cold Box Safety System Back flow limitation Open points: Interface valves located in QRL Service Module Safety system (control valve, safety valve, bursting disc) Back flow limitation

17. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Alternative cooling schemes, why?  To provide the possibility to discharge helium gas at a lower pressure than nominal 1.350 bar, increasing availability of sc cavities operation  To keep availability at least as it is now  While reviewing possible options, why not giving the possibility to operate the sc cavities independently from the sectors

18. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options 4.5 K Refrigerator QUI QRL SC Cavities Coupler cooling HP MP LP Warm Compressor Station Cold Box ? C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Warm recovery line (≤300 K; ≤1.1 bar) Safety System Option 1: Warm return Advantage: (Cool-down) / Warm-up even if line D > 1.4 bar Recovery of ACS static losses after sector quench Allows short period of operation if line D > 1.4 bar Rather easily implemented

19. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Layout UX45, side view ACS QRL WRL Detailed integration study needed to confirm the concept Warm Recovery Line (WRL) always along QRL

20. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Option 2: Cold return Advantage: Cool-down / Warm-up even if line D > 1.4 bar Recovery of ACS static losses after sector quench Allows quick re-connection after quench Allows short period of operation if line D > 1.4 bar Allows operation independently from QRL / Magnets 4.5 K Refrigerator QUI QRL SC Cavities Coupler cooling HP MP LP Warm Compressor Station Cold Box ? C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Warm recovery line (≤300 K; ≤1.1 bar) Safety System Kept as back-up ? Disadvantage: New valve box & lines Intervention on 2 lines Not easily implemented supply &

21. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Layout UX45, top view ACS QRL QUI QPLB - QULA: Lines between refrigerators & QUI  Additional lines as by-pass of QUI, via a valve box  Feasibility to be confirmed  Detailed integration study needed to confirm the concept

22. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Option 3: “Process wish” Advantage: Cool-down / Warm-up : no limitation No limitation due to quench Allows operation independent from QRL / Magnets 4.5 K Refrigerator QUI QRL SC Cavities Coupler cooling HP MP LP Warm Compressor Station Cold Box To be defined C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Warm recovery line (≤300 K; ≤1.1 bar) Safety System Kept as back-up ? Disadvantage: Not likely to be possible

23. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Option 4: Dedicated compressor Advantage: Cool-down / Warm-up : no limitation No limitation due to quench Operation independent from sector 4.5 K Refrigerator QUI QRL SC Cavities Coupler cooling HP MP LP Warm Compressor Station Cold Box Dedicated compressor Capacity boost to be defined C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Safety System Kept as back-up ? Disadvantage: Coupling with 4.5K Ref. not certain if possible

24. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Option 5: Dedicated Ref. (at last!) Advantage: Cool-down / Warm-up : no limitation No limitation due to quench Operation independent from sector Dedicated Compressor Dedicated Cold Box 4.5 K Refrigerator QUI QRL SC Cavities Coupler cooling HP MP LP Warm Compressor Station Cold Box Kept as back-up ? C (4.5 K; 3.0 bar) D (20 K; 1.3 bar) Safety System Disadvantage: Where and how to install this now ?

25. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Layout UX45, top view (5)  ACS  QRL  Cooling capacity critical for ultimate beams, something will have to be done !  Integration study needed surface-shaft-cavern

26. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Summary options Warm Return Cold sup/ret “process wish” Dedicated Compressor Dedicated Refrigerator Now12345 Pro/cons Pressure in QRL-D Minimum decoupling RF more indenp. t Feasibility ?!? Capacity RF indep. t Budget (approx.) 100 - 150 kCHF 1 - 2 MCHF 3 - 5 MCHF Time to install 6 - 10 months 1 - 2 years 2 - 3 years Data provided as indications, to be further studied if necessary

27. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Summary  The reference solution needs to be implemented, with simple adaptations (control & check valves) to prevent perturbation due to back pressure from line D  A back-up return via the warm recovery line would prevent from major pressure excursions above 1.5 bar Option 1 Option 2,3,4, 5 Option 5  Any alternative cooling scheme will need a modification of the corresponding cryogenic distribution line (after concerned service module)  Additional capacity will be triggered by needs for ultimate beams or (bad!) operational experience

28. LHC Workshop CERN, January 2005 Session 3 Cryo/RF Options Acknowledgements The authors would like to thank all colleagues who contributed to this work: E. Ciapala, R. Losito, P. Maesen, O. Brunner Y. Muttoni L. Serio, G. Riddone, L. Tavian