Crab Cavities SPS cryogenics – progress and requirements

1. Crab Cavities SPS cryogenics – progress and requirements Fermilab visit at CERN 02 August 2013 Krzysztof Brodzinski (on behalf of CERN cryogenic team)

2. Contents • Cryogenics for Crab Cavities project – technical aspects and status • Circuits • Heat load • Capacity limitations with existing infrastructure + possible solutions • BA4 work progress • 2 K pumping units test • Available space – integration brief • Cryogenics for SPS cryostat design • Process and instrumentation • Safety devices • Pumping collector sizing • Superfluid helium layer • Conclusions K. Brodzinski - Fermilab visit_2013.08.02

3. Cryogenic circuits Regarding 2 K refrigeration Additional He source Draft version Buffer tank R Service module LN2 JT CC cryostat Screen Coupler intercept CTW CC x 2 CTW EH EH PT TT TT LT black –> existing 4.5 K red –> to be constructed 2 K Screen K. Brodzinski - Fermilab visit_2013.08.02

4. Heat loads and TCF20 capacity The below values are calculated/estimated – no exact calculation is available yet depending on design V. Parma and colleagues Total net value: 0.98-1.08 g/s Total with 1.5 safety factor: ~1.5 g/s K. Brodzinski - Fermilab visit_2013.08.02

5. TCF20 cold box capacity discussion Static heat load -> 0.98-1.08 *1.5 =~1.5 g/s CERN isentropic equiv.recalculated with measured refrigeration capacity (120 W) CERN isentropic equiv.recalculated with guaranteed refrigeration capacity (85 W) CERN isentropic equiv.recalculated (20 l/h) Liquefaction capacity line [g/s] 0.7 0.85 1.2 0.76 1.56 LEGNARO guaranteed liquefaction capacity (22 l/h) LEGNARO guaranteed liquefaction capacity with LN2 (45 l/h) • Conclusions: • Existing TCF20 without LN2 boost is not sufficient to cover requirements (even upgraded as liquefier) • Plan B: LN2 boost to be installed and liquefaction capacity tested • Plan C: install new TCF20 liquefier + install LN2 boost (difficult because of safety and a lot of work – transfer lines to be installed, possible problems with instabilities of LN2 flow – info from G. Passardi) • Plan D: on the surface: Install a 10000 L dewarwith link to 200 L buffer as an “emergency boost” • Target: The cold box should cover at least the static heat load, the buffer tank dynamic operation of the cavity. K. Brodzinski - Fermilab visit_2013.08.02

6. Work done in BA4 • Inventory list, GMAO new naming definition list and PID update done by ~15.09.2012 • All SVs re-qualified and installed – done by ~15.09.2012 • Electrical motor and compressor maintenance – done by ~30.09.2012 • Oil separation refurbished (coalescers cartridge replaced, ADS charcoal replaced) – done by ~30.09.2012 • Storage – He tank re-qualified as pressure recipient – done on 12.09.2012 • All other pressure recipients re-qualified – done by ~15.10.2012 • Purging system on compressor station refurbished • Cooling water and air ventilation installations for compressor station – refurbished • Cold box vacuum system revised and partially refurbished • Compressor station and cold box (partially) instrumentation revised • Compressor station new electrical supply system with documentation done and tested by ~15.11.2012 • Control system well advanced (partially ready) • He tightness test done on compressor station • First run of compressor station done by 30.11.2012 – milestone (OK operational, HP@6 bara) • First helium flow through the cold box done on 18.12.2012 – milestone (OK, no leak into the vac) K. Brodzinski - Fermilab visit_2013.08.02

7. Work done 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 Renovated compressor + elec. motor – run test done Revised, labeled and qualified pressure control system / oil removal system Cold box TCF20 New power supply panel for compressor station 2 K pumping groups recovered from AMS SPS LS1 time frames: Open Access : 25/03/13 Close Access : 27/06/14 TCF20 Cold box K. Brodzinski - Fermilab visit_2013.08.02

8. 2 K pumping units performance test Both pumps were run to check their capacity – probably 2 pumps will have to be integrated in the tunnel – analysis underway. K. Brodzinski - Fermilab visit_2013.08.02

9. Cryo integration in SPS Pump heater SM Buffer TCF20 Electrical equipment Very tight integration if going behind the beam line (more details in Th. Renaglia presentation). K. Brodzinski - Fermilab visit_2013.08.02

10. Tentative SPS CC cryogenic schedule • Work planned for 2013: • - 2 K pumping group to be transported and integrated in the SPS tunnel in Autumn 2013 – AMS groups will be used • - Low pressure He recovery heating system to be transported and integrated in the SPS tunnel in Autumn 2013 – probably AMS elements could be adapted • - Electrical and control systems for 2 K cryogenics to be done (cables pulling included) – underway • - Refurbishment of the cold box 4.5 K – vacuum system and turbine circuits – done • - Cold box control system to be completed – done • - Cold box instrumentation revision/update to be completed – underway • - Cold run of the cold box – in September May 2013 – milestone – almost ready, conditioning done, waiting for cooling water circuit ON • - Liquefaction test of 4.5 K cold box (potentially with boost at 80 K stage, if yes, this boosting system is to be developed and bought/constructed), some hardware modifications are required as preparation for this test – to be done by 15.10.2013 – milestone • - Refurbishment of the supply/recovery system between BA4 and North Area is to be done or procurement of additional buffer tank to fulfil requirements of helium availability for CC testing – to be analysed and confirmed – spring/autumn 2013 – milestone • LN2 system for cooling of screen circuits to be developed and bought – to be defined • Buffer tank to be designed and bought • - 2 K cryogenics: transfer line system to be designed and ordered (installation in 2014) • - 2 K cryogenics: Service module to be to be designed and ordered (installation in 2014)  Main task for 2013/2014 is the distribution system development and installation K. Brodzinski - Fermilab visit_2013.08.02

11. Process & instrumentation 1/2 • The cryostat will house 2 crab cavities and will be operated at 2 K (saturated helium bath  ~30 mbar). The design should be done in the way to minimize the static heat load at 2 K(important!) • It will be equipped with two circuits 2 K and 80 K. The main interface should be provided from the top with 4 main lines (LHe IN, GHe pumping, LN2 80 K IN and 80 K OUT). • Proposed piping should cover nominal operation and transients (cool down and warm up), • Interface to the cryostat: internal pipes welded, external envelope bolted (allowing opening of the jacket by means of sliding it up or down). • Power couplers and Cold/Warm Transitions will be intercepted with LN2 at 80 K. cryostat interface thermal screen at ~80 K common pumping collector helium tank CWT crab cavity SKETCH CWT Power coupler intercept K. Brodzinski - Fermilab visit_2013.08.02

12. Process & instrumentation 2/2 • The cryostat should be equipped with the following instrumentation: • Helium level measurement – each helium tank should be equipped with a level gauge allowing for helium level measurement from the bottom through the phase separator (LT x 2, each gauge should allow for helium level regulation in the phase separator collector), • Pressure measurement on the saturated helium bath is to be provided (PT x 1), • Temperature measurement on each cavity helium tank is to be provided, installed on the bottom of each helium tank (suggested CERNOX type transducer, TT x 2), • Electrical heaters of 50 W are to be installed on each helium tank (EH x 2) • Temperature measurement on 80 K screen line is to be provided (TT x 2 on inlet and outlet) • JT valve and sub-cooling HX are foreseen to be installed out of the cryostat • (instrumentation for 80 K intercept circuits – definition underway) • All sub atmospheric instrumentation/safety devices with ambient air interface will have to be equipped with appropriated helium guard. cryostat interface thermal screen at ~80 K common pumping collector helium tank CWT crab cavity SKETCH TT TT CWT Power coupler intercept EH EH PT TT TT LT LT K. Brodzinski - Fermilab visit_2013.08.02

13. Safety devices • Assembly of cavity with helium tank have to be designed to withstand pressure of at least 2.6 bar (deltaP of 2.6 bar) without plastic deformation at ambient temperature. • Design pressure for the cryostat assembly should be based on installed safety devices according to design rules (cryostat equipped with a safety valve set at 1.8 bara* and a rupture disc set at 2.2 bara*, possibly one device could be installed … - analysis underway) • both safety devices will be installed in the way to avoid potential projection of helium towards the passages or transport areas (deflectors installation to be analyzed, preliminary position for the rupture disc and safety valve have been proposed on transfer line close to the cryostat interface), • Both safety devices should protect the cavity and the cryostat from pressure rise causing plastic deformations, • Both safety devices should be equipped with appropriate helium guards. • sizing of the devices -> to be done cryostat interface thermal screen at ~80 K common pumping collector helium tank CWT SV @ 1.8 bara SKETCH crab cavity Rupture disc @ 2.2 bara CWT Power coupler intercept * Value compatible with recommendations given by T. Peterson on December 2012 Fermilab meeting K. Brodzinski - Fermilab visit_2013.08.02

14. Pumping collector sizing • Requirements: gas speed lower than 5 m/s*, min 50 mm for level regulation, additional buffer for ~ 20 min of operation, compatibility with safety devices for pressure limit requirements. • Indications: Diameter of 100 mm (recommended) allows for: • return gas speed below 5 m/s up to ~90 mm of liquid level in the collector (operation regulation level to be set at ~50 mm of LHe in the collector), • buffer volume for transients/unexpected process perturbations (half filled collector allows for ~20-30 min of operation assuming collector length of ~1.6 m and 20 W of thermal load), • compatibility with safety valves sizing is still to be checked ! Liquid level * Value compatible with recommendations given by T. Peterson on December 2012 Fermilab meeting 100 mm ~90 mm maxi: 5 m/s 92 Regulation ~50 mm 0 mm * Calculation done assuming: collector diameter of 100 mm, He mass flow = 2 g/s, GHe temp = 2 K, GHe press = 20 mbar. K. Brodzinski - Fermilab visit_2013.08.02

15. Superfluid Helium layer Requirements: superfluid helium layer must cover whole surface of the cavity and provide correct operation of the cavity at required conditions (2 K). The heat transfer capability for superfluid helium layer have to be evaluated, typically between 0.95 - 1 W/cm2 Exercise – indication: assuming round cavity from below sketch; dimensions D=175 mm x L=700 mm and heat load of 20 W, the required minimum superfluid helium layer is ~ 2.5 mm. Applied production technology will require more …. It should not be enlarged without the limits in order to minimize reasonably the liquid helium volume (max. 40 L/cavity if possible). cryostat interface common pumping collector SKETCH – NO SCALING Units: [mm] helium tank crab cavity ~300 185 180 700 K. Brodzinski - Fermilab visit_2013.08.02 710

16. Conclusions • Work is progressing well, cold run of the cold box to be done in September with dedicated liquefaction test, • Boost of the cold box is mandatory (LN2 system to be built + additional 10000 L He dewar connection possibility to be take into consideration, • 2 K pumping units – capacity test done -> 2 units to be integrated in the tunnel, • Tight planning with still a lot of work on the infrastructure to fulfill requirements -> LN2 line to be installed, probably He line to be installed through the shaft to connect the buffer tank, • Close collaboration with regular working sessions is needed to merge between CERN requirements and the modules suppliers. Thank you! Questions? K. Brodzinski - Fermilab visit_2013.08.02