s Phenix Cryogenics BNL Review Cryogenics System Group

s. Phenix Cryogenics BNL Review Cryogenics System Group Collider Accelerator Department Presenter: Paul Orfin

SUMMARY § Low Power testing in building 912/902 § Baseline configuration and cost • RHIC cryogenics as cooling source • Thermo-siphon cooling mode § Cooling Source Options to explore • RHIC Cryogenics • Independent cryo plant 200 W@4. 5 K § Technical Options to review Forced cooling mode Thermo-siphon cooling mode

SLAC CONFIGURATION VALVEBOX/THERMO-SIPHON RESERVOIR 3

Solenoid Parameters § COIL COOLING • Conductively cooled by helium through aluminum tubes welded on aluminum outer support cylinder. • Designed as thermo-siphon loop • Parallel tubes on aluminum support cylinder • Top and Bottom Headers § COOLING LOOP § Design: Thermo-siphon loop § Operation at SLAC: § Thermo-siphon loop, but temperature unstable § Forced Flow from cryogenic plant

SOLENOID PARAMETERS 5

Cryogenic Summary of Solenoid § Coil Energy Stored energy: 27 MJ [@4596 A, 2. 57 H] • Tc =8. 27 K @ 2. 5 T • Coil temperature after quench 37 K • § Heat Shield • • • Duty: < 100 W [Design 350 W] 45 K <0. 5 g/s § Lead Flow • Main Coil • Buckling coil - 5000 A 0. 25 g/s each lead § Cool down • • SLAC flow: 70 G/S DTmax = < 40 K Max Cooling duty: 14 k. W Typical duration: 7 days § Steady State 4. 5 K load: ~ 25 W [Design 70 W] • Siphon Separator vessel and solenoid • § Operation modes • • Thermo-siphon loop Forced flow cooling from plant 200 A (may not be needed) 6

4. 5 K Low Power Test in Bldg 912 § Use ERL Cryogenic Plant § Operate in thermo-siphon mode § Add Tie-in on VTF side of ERL distribution lines • Isolation valves and Bayonets § Re-use Co-axial cryogenic transfer line from SLAC • Modifications to shorten and get matching bayonets on ERL interface end of this cryogenic transfer line. § Independent (from ERL) pre-cool using Small LN 2 precooling system for controlled cool down of solenoid using some helium flow from ERL compressor • 240 Liter LN 2 Dewar with subcooler coil exchanger • Control valves for mixing 300 K and 85 K helium gas

4. 5 K Low Power Test in Bldg 912 8

4. 5 K Low Power Test in Bldg 912 Important cryogenic benefits from testing § Determine if there any issues resulting from • Shipping • Decommissioning § Verify Static Heat leak • Compare against previous data • Make system adjustments or repairs if necessary § Examine thermo-siphon cooling method • Verify if temperature instabilities exist

Cryogenic System at IP 8 Requirements 1. Steady state operations, 4. 5 K 1. Thermo-siphon Cooling 2. Forced Flow Cooling 2. Cool down gradient <40 K. Preferred 20 K 3. 500 L storage for >5 hrs of operation without helium cryogenic system to ramp down solenoid. 4. Keep below 100 K without Helium cryogenic system. E. g. during summer shutdown, LN 2 system 5. Able to test solenoid during summer shutdown: 1. Additional space and transfer jumper for 500 L portable LHe 2. LN 2 Precool if starting from 300 K

Cooling Methods § Forced circulation • Subcooled - M header, 4 bar flow gets subcooled in a subcooler heat exchanger that is submerged in LHe bath and sent to solenoid. Return to S header. • 2 -phase flow - Push 2 phase flow through solenoid cooling tubes. - Essentially equivalent of strong Thermo-siphon loop § Thermo-siphon Design • SLAC operation shows loop is not stable. • Instability probably resulted from too much subcooling. • As a result, nucleate boiling does not initiate until tube surface temperature has risen appropriately, then once siphon starts, the helium begins to cool and fluctuation cycle restarts.

Cooling Method Comparison § Forced circulation § Cons Supply stops and so does magnet cooling - Reservoir needs to be pressurized, low pressure return needed to keep loop going (dump to atmosphere or return to low pressure header) - • Subcooled Requires subcooler exchanger-coil in phase separator bath - Operating pressure > 2. 3 bar - • 2 -phase flow Operate at subcritical in pressure - Cryo system has to be able to handle 2 -phase return - § Pro • Operationally more stable § Thermo-siphon § Cons • Not as stable - Need to review with SLAC § Pros • Low pressure operation • Easy to transfer liquid inventory from local reservoir in the event of loss of RHIC supply

Cooling Source Comparison § RHIC CRYO SYSTEM § Pros • Lower cost • Possibly less equipment to maintain § Cons • RHIC is High pressure • LHe Dewars needed for summer testing • Additional LN 2 cooled system to keep magnet cool § INDEPENDENT SYSTEM § Pros • Operation during summer shutdown • Can satisfy both cooling methods § Cons • Higher cost • More equipment maintenance • Space requirements • May still require 80 K cooler for backup

PFD: RHIC Source, Siphon mode SPHENIX – SC SOLENOID CRYO 14

RHIC Source, Subcooled Forced mode

Independent Source, Forced or Siphon Sheet 1 of 2

Independent Source, Forced or Siphon Sheet 2 of 2

Future Endeavors § Investigate thermo-siphon issues § Select a forced cooling method § Evaluate an independent cryogenic system at IP 8 as the cooling source § Preparations for low power test § Designs will be review and approved by BNL pressure safety committee

Plan View – IP 8 Drawing overlay Solenoid South 19

Elevation view – IP 8 Drawing overlay Solenoid South 20

EQUIPMENT – RHIC Source Siphon § RHIC Interface Valvebox • • 2 X 2” Cryogenic Control valves 4 x 1/2” Cryogenic Control valves 2 x ½” Control Valves Flowmeter, Press Trans, Temperatures • • • 120 ft long (4 x 30 ft) 1 x 2” or 1 x 1” Supply 1 x 2” Return 1 x ½” Shield return Shielded transfer line 4 mid joints + 2 end joints § § Transfer Line System § § § SLAC Valve. Box/Siphon reservoir reuse • • • Actuator upgrade for valves New Reliefs Other Lead Flow Control • New Controllers § § Summer Keep Cool System • #1 LN 2 cooled • #2 Cryomech G-M coldhead with circulator - Small compressor 1 g/s He LN 2 Transfer Line 3000 Gal LN 2 Storage Dewar / tap into existing 5000 Gal LN 2 dewar LHe Reservoir for Rampdown • • • 500 L Pressure Building Heater Coaxial Transfer Jumper Relief header: TBD • • • Most likely run small line to outside for transient relief Catastrophic failure or large quench vent inside? Depends on ODH Cold. Box at Solenoid Valvebox • • Heat exchanger for cooldown control Heat exchanger LN 2/He 3 Cryo Control valves 4 sets U-tube Jumpers: Bayoneted 21