NML Cryogenic System Arkadiy Klebaner Cryomodule One Commissioning June 3, 2011

Outline Overview CM1 cooldown System capabilities Technical issues Future plans Summary

NML Cryogenics Overview Two oil-flooded dual stage compound screw compressors Two standalone Tevatron heat exchangers operating in a mixed mode – refrigeration and liquefaction Refrigeration for 5 K thermal shields and distribution system heat leak Liquefaction for supplying cavities 80 K thermal shields are cooled by LN 2 from a dewar Warm vacuum pump is used to reduce helium vapor pressure for superfluid conversion Distribution system to serve Capture cavities and ILC type cryomodules Real time purification and contamination protection systems Inventory management systems State-of-the-art controls and instrumentation

CM1 Cooldown Cooldown to 4.5 K  Accelerator Division approval to operate CM1 was granted on November 17, Cooldown was started at 9:00 am Manual cooldown. Three shifts around the clock  Cooldown from 300 K to 4.5 K was achieved in 54 hours Pumpdown to 2 K  Pumpdown performed on Monday, November 22 nd  It took three hours to get to 12 torr ( ~ 1.8 K) Issues  Following completion of the CM1 cooldown on Friday, November 20 th developed a helium leak in the refrigerator room (3:30 pm)  CM1 helium to insulated vacuum and air to insulated vacuum leaks

System Capabilities Sufficient capacity for > ILC RF Unit* Rate limited cooldown ( req’d by ILC CM design) Stable cavity pressure Precision liquid level control Cryomodule over pressure protection system State-of-the-art controls Sub atmospherically hardened system * - based on the listed ILC cryomodule heat load Picture courtesy P. Perini, INFN

Capacity Feed cap, End cap and CM1 static heat load is estimated to be 18 W* Sustainable delivered capacity: ~ 110 Superfluid temperatures ( 1.6 K or higher) * - Estimate is within ~20% accuracy CM1 HeaterCM1 liquid levelRefrigerators heaters

Cooldown Rate Control Helium Gas Return Pipe (GRP), aka 300 mm strong back  Maximum Vertical Gradient <= 15 degrees  Longitudinal Gradient <= 50 degrees  Cooldown Rate is < 10 degrees/hour or better 5 K and 80 K Thermal Shields – similar constraints Driven by ILC cryomodule design 10 [K/hr] GRP vertical gradient

Pressure stability Cavity pressure fluctuation is 0.1 torr (10 Pa) or better, thus temperature stability is better than 2 mK

Liquid Level Control Dynamically adaptive PID control loop for liquid level control Q loaded Eacc He liquid level Cavity pressure

Over Pressure Protection System Cryomodule Relief System (Dual MAWP)  4 bar (43 psig) Main Relief (6” x 8” nominal size)  2.05 bar (15 psig Relief) (2” x 3” nominal size)  7 psig Operational Relief  Reliefs Utilize Conflat Flanges  12” Relief Header with Low Pressure Rupture Disk

Open Technical Issues Primary  Helium flow meter accuracy (explore alternative designs)  Improve insulating vacuum (install additional insulating vacuum pump cart, improve CM seals) Minor  North H/X return helium vaporizer (condensation in the building)  J-T heat exchanger thermometry (ground loops)  Replace South H/X bayonet with modern design ( leaking ball valve)

FCI Thermal Flowmeter Vendor calibrated primary thermal flowmeter and secondary variable area meter were tested by changing electrical heater power input to CM1

Insulating vacuum Helium to insulating vacuum leak intensifies at normal He to superfluid transition Insulated vacuumHe pressure

Future Plans Resolve open issues Increase system capacity  Modify and install CTI-4000  Supplement NML heat exchangers from CMTF Improve compressor system availability  Commission purifier compressor  Install a spare Mycom compressor Streamline cryomodule interconnects installation

Summary The NML cryogenic system has supported initial CM1 cooldown. It has been reliably operated for the past six months The system has achieved expected capacity and performance The cryogenic systems allows for continuous operation of ILC cryomodules NML has unique cryogenic capabilities specifically tailored for testing and operating of ILC cryomodules

Thanks to dedication and talent of many involved …

Supplemental material

NML Refrigerator Continued  Reciprocating expanders  Valve Box  Helium Dewar  Heat Exchanger  Bayonet Cans  Two Standalone Refrigerators  Capacity: K or 4 g/s LHe each  Located Southeast End of NML Satellite Refrigerators

Main Helium Compressors  Located at Lab B  Two oil-flooded screw compressors  Manufactured by Mycom  Capacity 60 g/s each  Pressure Discharge ~280 psig Suction ~ 1.2 psig  Oil Removal System  Power ~400 hp each

Helium Gas Storage and Liquid Nitrogen Supply  4 Helium Storage Tanks  Total Capacity = 42,900 gallons  MAWP = 250 psig  2 Tube Trailer Fill Stations  Liquid Nitrogen Dewar  6000 gallon capacity

Recovery Booster Compressor  Contamination Concerns due to Sub-atmospheric Operation  Frick Helium Screw Compressor (100 hp)  Vacuum Pump Discharge Flow  14 g/s of Helium at 1 psig Inlet Pressure  New Oil Removal System Installed  Compressor Flow can diverted to Helium Purifier  Two Full Flow Helium Purifiers Available

Helium Pumps (Superfluid Operations)  Ambient Temperature Pumping Cycle  Kinney Model KLRC 2100 Liquid Ring Pump  Kinney Model KMBD – 10,000 Roots Blower  Identical to Skid Used at MP7  Reworked for Helium Service  Helium Guarded Dynamic Seals  Sub-atmospheric Components  Several Stages of Interlocks for Protection  Connected to Cryogenic Load via Main Pumping Header  CC1, CC2 and Cryomodule String have individual low pressure control valve to independently regulate cavity pressure

Cryomodule Distribution System Feed Cap Cryomodule End Cap Feed Box Transfer line

Feed box Feedbox contains J-T heat exchanger, dewar/subcooler/phase separator, all the valves and instrumentation to distribute cryogens to all of the CM circuits

Feed cap WPM Beam Tube 5 K 80 K Support Plate ~30 ton Force

End cap Connects to 300 mm GRP Phase separator with liquid level probe and two heaters 80 K thermal shield 5 K thermal shield

Interconnects 27

AEM Meeting 28 Dec 20, 2010 Interconnects (cont’d)

29 Interconnects (cont’d)

30 Interconnects (cont’d)

31 Interconnects (cont’d)

32 Interconnects (cont’d)

33 Interconnects (cont’d)

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