AMS-02 Cryosystem Phase III Flight Safety Review January 12, 2010 Phil Mott

Page 2 AMS-02 Cryosystem Vacuum Case Main Helium Tank Plumbing & Valves

Page 3 Cryosystem Schematic

Page 4 Vacuum Case Vacuum jacket for the superconducting magnet Inner Joint: – Welded U groove design Outer Joint: – Bolted joint with double o-rings SUPERFLUID HELIUM TANK MAGNET RACETRACK COIL (DIPOLE COIL ROTATED 90 o ) VACUUM SPACE 1 x TORR SUPER INSULATION & VAPOR COOLED SHIELDS UPPER CONICAL FLANGE UPPER SUPPORT RING OUTER CYLINDER INNER CYLINDER OUTER JOINT INNER JOINT LOWER SUPPORT RING LOWER CONICAL FLANGE

Page 5 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

Page 6 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.

Page 7 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.

Page 8 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.

Page 9 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.

Page 10 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.

Page 11 Warm Helium Supply Provides helium that actuate both the warm and cold valves. Covered in detail in a later presentation

Page 12 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

Page 13 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.

Page 14 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).

Page 15 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.

Page 16 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.

Page 17 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)

Page 18 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.

Page 19 Cryocoolers 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.

Page 20 Fill Port The Fill Port is only used for ground operations during filling and topping off of the main helium tank.