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AMS-02 Cryosystem. Phase III Flight Safety Review January 12, 2010 Phil Mott. AMS-02 Cryosystem. Vacuum Case Main Helium Tank Plumbing & Valves. Cryosystem Schematic. SUPER INSULATION & VAPOR COOLED SHIELDS. MAGNET RACETRACK COIL (DIPOLE COIL ROTATED 90 o ). SUPERFLUID HELIUM TANK.

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Ams 02 cryosystem

AMS-02 Cryosystem

Phase III Flight Safety Review

January 12, 2010

Phil Mott

Ams 02 cryosystem1
AMS-02 Cryosystem

  • Vacuum Case

  • Main Helium Tank

  • Plumbing & Valves

Cryosystem schematic
Cryosystem Schematic

Vacuum case






1 x 10-6 TORR


Vacuum Case


  • Vacuum jacket for the superconducting magnet

  • Inner Joint:

    • Welded U groove design

  • Outer Joint:

    • Bolted joint with double o-rings








Vacuum case certification
Vacuum Case Certification

  • Helium Leak Tests

    • Both o-rings at all locations and both closeout welds were leak tested to show a better than 1.0 x 10-7 std cc/sec permeation

  • Proof Pressure Test:

    • The VC was successfully pressure tested to 1.8 atm absolute (1.0 x MDP)

  • Closeout Weld

    • Process certified to MSFC-SPEC-504C

    • Inspections

      • Visual

      • Dye Penetrant

      • Ultrasonic

Main helium tank
Main Helium Tank

  • 2500 liter toroidal vessel which is constructed from Al 5083

    • All welded structure

  • Helium Leak Test

    • Both halves leak tested along with full assembly

  • Proof Pressure Test

    • Successfully tested to 3.3 bar (MDP is 3.0)

  • Superfluid Helium Leak Test

    • Tank was leak checked after it was assembled inside of the VC due to issues with the ground testing rig. No leaks were found.

Burst discs
Burst Discs

  • Both the Vacuum Case and the main helium tank are protected by burst disc. These will be covered in detail in a later presentation.

Warm cold valves
Warm & Cold Valves

  • The system uses two sets of gas-actuated valves in order to move the liquid helium around the cryosystem.

    • The cold valves are located on the main helium tank

    • The warm valves are located on the VC

  • Actuation gas comes from the Warm Helium Supply on the VC.

Pilot valve vacuum vessel pvvv
Pilot Valve Vacuum Vessel (PVVV)

  • The PVVV contains the pilot valves that control the cold valves inside of the magnet. This prevents heat leak into the actuation lines.

  • System was installed in place, so a proof pressure test to 1.5xMDP cannot be done without risking damage to other components. Equivalent verifications being developed with EP.

  • Vacuum leak checked.

Pvvv changes
PVVV Changes

  • Design changed from an all welded configuration to a bolted o-ring seal (for valve replacement if necessary). Does not affect safety.

  • Line added to vent pump from PVVV to pump out helium from valve exhaust for a reduced heat load from L-88 to launch.

Warm helium supply
Warm Helium Supply

  • Provides helium that actuate both the warm and cold valves.

  • Covered in detail in a later presentation

Superfluid cooling loop scl
Superfluid Cooling Loop (SCL)

  • The SCL is a closed system that is used to continually cool the magnet.

  • A serpentine tube is located inside of the main helium tank and the cooling loop is run along the top and bottom of the magnet coils.

  • The SCL is protected by a 20 bar burst disc that vents into the main helium tank.

  • Nominal operating pressure is 1 bar

Cool down circuit
Cool Down Circuit

  • Only used to initially cool down the magnet and after a quench to re-cool the magnet.

  • Tubes run along the top and bottom of the magnet coils and connected by thermal bus bars.

Current leads
Current Leads

  • The current leads are used to charge the magnet and are cooled by flowing helium through the middle of the lead.

  • The current leads functioned nominally after the fix was implemented (covered in a separate presentation).

Thermo mechanical pump
Thermo-mechanical Pump

  • The thermo-mechanical pump is used to pump helium from the main tank into the cryosystem during re-cooling of the magnet after a quench and during charging.

  • It has no moving parts and is actuated by a heater and primed by surface tension.

  • Both TMP’s function as designed.

Porous plug nominal venting
Porous Plug & Nominal Venting

  • As helium in the main tank boils off, it is vented through a porous plug that separates the gas from the superfluid helium.

  • The vapor passes through the Vapor Cooled Shields, and then out through a port on the VC which then splits into three lines.

    • The first line goes to the flight vent, which is used on-orbit

    • The second line goes to a port with a connection to the CGSE pumps, which is used on the ground.

    • The third line goes to the On-Board Pump, which is used during transportation and in the payload bay.

Vapor cooled shields vcs
Vapor Cooled Shields (VCS)

  • There are 4 VCS between the helium tank and the VC. As the helium boils off in the main helium tank, it flows through pipework attached to the 4 VCS’s that intercept incoming heat.

  • The VCS’s are constructed from strips of pure aluminum.

  • The VCS’s are separated by layers of superinsulation (aluminized Mylar and nylon netting)

Vcs supports
VCS Supports

  • VCS 2 & 4 are supported by a carbon fiber honeycomb structure on the top and bottom. They are connected to each other by a series of wires.


  • Four Stirling-cycle cryocoolers used to remove additional heat from VCS 4 and reduce the external heat leak.

  • The cryocoolers were developed by Sunpower and modified by GSFC for flight.

  • Qualification cooler has been run for twice the nominal mission lifetime without incident.

Fill port
Fill Port

  • The Fill Port is only used for ground operations during filling and topping off of the main helium tank.