AMS02 Cryosystem Phase III Flight Safety Review January

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

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

Cryosystem Schematic Page 3

Vacuum Case OUTER JOINT l Vacuum jacket for the UPPER SUPPORT RING superconducting magnet l Inner Joint: VA SUP PO ER R C INS OO UL LE ATI D S ON HIE & LD S – Welded U groove design l Outer Joint: – Bolted joint with double o-rings SUPERFLUID HELIUM TANK MAGNET RACETRACK COIL (DIPOLE COIL ROTATED 90 o) UPPER CONICAL FLANGE INNER JOINT INNER CYLINDER VACUUM SPACE 1 x 10 -6 TORR OUTER CYLINDER Page 4 N& S TIO IELD A H UL S INS LED ERCOO P SU OR P VA LOWER SUPPORT RING LOWER CONICAL FLANGE

Vacuum Case Certification l 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 l Proof Pressure Test: – The VC was successfully pressure tested to 1. 8 atm absolute (1. 0 x MDP) l Closeout Weld – Process certified to MSFC-SPEC-504 C – Inspections l Visual l Dye Penetrant l Ultrasonic Page 5

Main Helium Tank l 2500 liter toroidal vessel which is constructed from Al 5083 – All welded structure l Helium Leak Test – Both halves leak tested along with full assembly l Proof Pressure Test – Successfully tested to 3. 3 bar (MDP is 3. 0) l 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 6

Burst Discs l 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 7

Warm & Cold Valves l 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 l Actuation gas comes from the Warm Helium Supply on the VC. Page 8

Pilot Valve Vacuum Vessel (PVVV) l The PVVV contains the pilot valves that control the cold valves inside of the magnet. This prevents heat leak into the actuation lines. l System was installed in place, so a proof pressure test to 1. 5 x. MDP cannot be done without risking damage to other components. Equivalent verifications being developed with EP. l Vacuum leak checked. Page 9

PVVV Changes l Design changed from an all welded configuration to a bolted o-ring seal (for valve replacement if necessary). Does not affect safety. l 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 10

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

Superfluid Cooling Loop (SCL) l The SCL is a closed system that is used to continually cool the magnet. l 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. l The SCL is protected by a 20 bar burst disc that vents into the main helium tank. l Nominal operating pressure is 1 bar Page 12

Cool Down Circuit l Only used to initially cool down the magnet and after a quench to re-cool the magnet. l Tubes run along the top and bottom of the magnet coils and connected by thermal bus bars. Page 13

Current Leads l The current leads are used to charge the magnet and are cooled by flowing helium through the middle of the lead. l The current leads functioned nominally after the fix was implemented (covered in a separate presentation). Page 14

Thermo-mechanical Pump l 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. l It has no moving parts and is actuated by a heater and primed by surface tension. l Both TMP’s function as designed. Page 15

Porous Plug & Nominal Venting l As helium in the main tank boils off, it is vented through a porous plug that separates the gas from the superfluid helium. l 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 16

Vapor Cooled Shields (VCS) l 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. l The VCS’s are constructed from strips of pure aluminum. l The VCS’s are separated by layers of superinsulation (aluminized Mylar and nylon netting) Page 17

VCS Supports l 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 18

Cryocoolers l Four Stirling-cycle cryocoolers used to remove additional heat from VCS 4 and reduce the external heat leak. l The cryocoolers were developed by Sunpower and modified by GSFC for flight. l Qualification cooler has been run for twice the nominal mission lifetime without incident. Page 19

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