1. Cooling Circuit Design Steve Virostek Lawrence Berkeley National Lab February 29, 2012 MICE Coupling Coil Cryostat Design Review Lawrence Berkeley National Lab

2. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 2 Cooling Circuit Overview All cooling is provided by three 2-stage pulsed tube cryocoolers The radiation shield is cooled by the first stage of the coolers The cold mass is maintained at 4K by a series of tubes welded to its exterior cover and containing liquid helium Heat loads on the cold mass vaporize helium in the tubes, and the vapor migrates to the cryocooler sleeve enclosures Helium vapor is returned to the system as liquid by means of a re-condenser connected to the second stage of the coolers Liquid helium collects in a reservoir at the top of the cold mass A thermal siphon circuit returns the condensed helium to the bottom of the cooling tubes

3. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 3 Coupling Coil Overview Cooler tower Cryocoolers

4. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 4 Helium System Vent Lines Primary vent line Secondary vent line

5. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 5 Cooling Circuit Status The Coupling Coil cooling circuit has undergone numerous design iterations The current scheme is intended to simplify the system as much as possible while lowering risk Elimination of one cooling tube not detrimental to performance Previous designs included: – LHe bath inside the cold mass (eliminated due to stress issues) – Lower LHe reservoir on the cold mass (not necessary in current design) – Liquid return from the reservoir in the same outer cooling tubes (removed one cooling tube and replaced with cool down and LHe return lines to eliminate risk of vapor lock)

6. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 6 Cooling Circuit Overview Cold mass with external tubes 1 st stage Cu plates LHe reservoir

7. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 7 Radiation Shield Overview Flexible links Shield thermal connection Series 1100 Al shield

8. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 8 Cooler Tower Details LHe condensers Primary vent line Secondary vent line

9. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 9 70K Cooling Circuit Details Cryocooler sleeve enclosures Cool down tubing

10. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 10 Cooling Circuit Tubes LHe cooling tubes Cool down line Liquid return line

11. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 11 Reservoir Interior Details Cooling tube connections to LHe reservoir Liquid return connection to LHe reservoir

12. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 12 Reservoir Tube Connections Cooling tubes Insulated liquid return line

13. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 13 Cooling Tube Bottom Details Liquid return line Cool down line Cross connect manifold

14. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 14 Cooling Tube Connecting Manifold

15. MICE Coupling Coil Cooling Circuit Design – S. Virostek – LBNL – February 29, 2012 Page 15 Summary The overall scheme for the Coupling Coil cooling circuit has been completed The circuit uses a relatively simple, low risk thermal siphon approach for cold mass cooling Analyses have shown that the 3 cryocooler system has adequate margin to maintain the cols mass and shield at the desired temperatures with no LHe boil off Final design details and fabrication drawings are still to be completed