AMS02 Thermal Control System TCS

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AMS-02 Thermal Control System (TCS)
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AMS-02 Thermal Overview

• AMS-02 delivered to ISS in orbiter payload bay
• Mounted on S3, inboard, zenith Payload Attach
  Site
• Payload nominally dissipates 2400 watts (2800
  watts peak)
• Will meet all ISS and STS safety requirements
• Thermal requirements are defined in SSP 57003
  (Attached Payload Interface Requirements
  Document)
• Thermal Design Goals
• Maintain all experiment components and
  sub-detectors within specified operating and
  survival limits (document in AMS-02 Thermal ICD)
• Maximize Super Fluid Helium (SFHe) endurance
• Optimize sub-detector temperatures to maximize
  science

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AMS-02 TCS Hardware

• Radiators
• Heaters
• Thermal Blankets
• Loop Heat Pipes (LHPs)
• Standard Axial Groove Heat Pipes
• 2-Phase CO2 pumped loop
• Surface Optical Coatings

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Radiators

• AMS-02 radiators include Main Radiators (Ram and
  Wake), Tracker Radiators (Ram and Wake), and
  Zenith Cryocooler Radiators.

Ram
Wake
Main Radiator Wake
Main Radiator Ram
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Main Radiators

• Main Radiators dissipate heat from electronics
  crates.
• Ram radiator dissipates up to 525 watts during
  normal operation, while the Wake Radiator
  dissipates up to 812 watts.

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Main Radiators Mounting

• Main Radiators are mounted to directly to the
  crates, which in turn are attached to the USS-02

Upper Brackets (4)
Mid Bracket (4)
Lower Brackets (4)
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Main Radiator Construction

• Radiators are a sandwich construction with Al
  face sheets and a ROHACELL core.
• Axial groove heat pipes (aluminum filled with
  ammonia) are imbedded between face sheets.
• Heat pipe flanges maximize thermal contact at
  crates mounting locations
• Chotherm 1671 is used as a thermal interface
  filler between crates and radiators.
• Radiators are painted with SG121FD white paint to
  optimize heat rejection.

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AMS-02 Main Radiator Cross-section (flange
removed)
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AMS-02 Main Radiator Heat Pipe Layout
Ram
Wake
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Tracker Radiators

• Ram and Wake Tracker Radiators are designed to
  reject the total heat generated inside the
  Tracker (144W).
• Heat is transported by the Tracker Thermal
  Control System (TTCS) which will be discussed
  latter.

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Tracker Radiators
Tracker Radiator (2 x 1.225 m2)
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Tracker Radiator Construction

• Tracker Radiators are a sandwich construction
  with Al face sheets and a ROHACELL core.
• Heat pipes (aluminum filled with ammonia) are
  imbedded between face sheets.
• TTCS Condensers bolt directly to heat pipe
  flanges (40mm wide at interface locations, but
  only 22mm elsewhere).
• Chotherm 1671 is used as a thermal interface
  filler between condensers and radiators.
• Outer surface is painted with SG121FD white paint
  to optimize heat rejection.

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Tracker Radiator Cross-Section (non-interface
section)
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TTCS Condenser Mounting Interface
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Tracker Radiator Heat Pipe Layout
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EMBEDDED HEAT PIPE RADIATOR PANEL
CARBON FIBER SUPPORT STRUTS
TTCS CO2 CONDENSERS (old design)
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Zenith Radiator

• The Zenith Radiator (4 separate panels) is design
  to reject the waste heat generated by the
  Cryocoolers (60-160W each).
• Heat is transported to each radiator panel via 2
  Loop Heat Pipes (LHPs) attached to a single
  cryocooler.
• The LHPs utilize propylene as a working fluid
  which flows directly through aluminum tubes
  embedded in the Radiator.
• Aluminum tubes in the radiator transition to
  stainless steel tubes running to the evaporator
  via a bi-metallic joint.

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Zenith Radiator Panels
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Zenith Radiator Construction

• Radiators are a sandwich construction with Al
  face sheets and a ROHACELL core.
• 3mm aluminum tubes are brazed to upper face
  sheet.
• Radiator panels are mounted to top of TRD Upper
  Honeycomb Panel via brackets and glass-fiber
  pins.
• Outer surface is coated with silver-Teflon.
• Multi-layer Insulation (MLI) is used between
  Radiator and TRD.

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Zenith Radiator Cross-Section
Radiator Mounting
Radiator Cross-section
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Multi-Layer Insulation (MLI) Blankets
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Multi-Layer Insulation (MLI) Blankets

• Numerous components of AMS-02 will be covered
  with MLI blankets
• All blankets will meet NASA standards for
  grounding and venting, and will be constructed
  according to MLI for AMS Guidelines
  (CTSD-SH-1782)
• All blankets will be positively secured.
• Typical construction will include multiple layers
  of aluminized Mylar separated by Dacron scrim.
  Betacloth will protect exposed surfaces.

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MLI for AMS Guidelines

• Written by Crew and Thermal Systems Division
  (CTSD-SH-1782, September 30, 2005)
• Based on requirements from ISS, STS and MSFC
• Electrical Bonding and Grounding
• All blankets with surface area greater than
  100cm2 will have at least two (2) grounding
  assemblies.
• Resistance from aluminized surface to ground
  shall be less than (lt)  5,000 Ohms
• Resistance from ground to spacecraft structure
  shall be less than (lt) 1 Ohm

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Heaters

• Heaters on AMS-02 are primarily used to
• Warm up components to switch on temperature
  after power outages (including initial turn-on).
• Maintain components above minimum operating
  limits during operation.
• Thaw CO2 (TTCS system) and NH3 (heat pipes) in
  case of extended power outages in cold
  environments.
• Manage TTCS operation

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Heaters (continued)

• Most heaters are both thermostatically and
  computer controlled.
• Analyses have been performed to evaluate effect
  of run away heaters.
• All safety critical heaters are two-fault
  tolerant.
• No heaters are required to control any hazards.

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Heat Pipes

• Standard axial groove heat pipes are used in
  several location to help distribute heat
• Main and Tracker radiators have embedded heat
  pipes mounted directly to heat sources.
• Heat pipes are mounted to one of the USS-02
  joints to help dissipate heat from the CAB during
  magnet charging.
• Heat pipes are used on the CAB base plates to
  minimize gradients.
• All heat pipes are aluminum filled with high
  purity ammonia.
• Heat pipes are designed to survive
  freezing/thawing cycles without excessive
  pressure or rupture.

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Thermal Optical Coatings

• Passive thermal design of AMS-02 include the use
  of thermal optical coatings.
• MLI blankets or plain Betacloth covers are used
  to improve optics of some surfaces.
• Main and Tracker radiators are painted with
  SG121FD white paint to improve heat rejection.
• The Zenith Radiator, along with parts of the
  Vacuum Case, USS-02, High Voltage Bricks, and CAB
  are covered with silver-Teflon film to reduce
  peak temperatures.

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Cryocooler Cooling

• Each of the 4 Cryocoolers dissipate up to 160W of
  heat in order to remove 4 10W of heat from the
  Cryomagnet system.
• Loop Heat Pipes (2 per Cryocooler) are used to
  transport this heat to the Zenith Radiator where
  it is rejected via radiation.
• The Loop Heat Pipes (LHPs), provided by
  IberEspacio/Madrid, are similar to those
  successfully demonstrated as part of COM2PLEX
  flown on STS-107.
• Propylene is used as a working fluid to avoid any
  freezing. Freezing point of propylene is -185C.

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Loop Heat Pipe System for 1 Cryocooler
Radiator panel
Fluid Lines
Redundant Evaporators
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LHP Configuration

• Each LHP has a vapor line running to the Zenith
  Radiator and a liquid line returning.
• Lines in and out of the evaporator are stainless
  steel tube. These tubes transition to aluminum
  tubes at the edge of the Zenith Radiator via a
  bi-metallic joint.
• Pumping pressure is achieved via capillary
  action in the LHP wick (nickel).

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LHP Schematic
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Crycooler to LHP Interface

• LHP Evaporators bolt to either side of the
  Cryocooler heat reject collar.
• Indium foil is used as a thermal interface.

Cryocooler
Evaporator
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LHP Heaters

• Heaters are mounted to the evaporators for LHP
  startup and to keep Cryocoolers above their
  minimum storage limits.

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LHP Bypass Valve

• A bypass valve is used to keep Cryocoolers from
  getting too cold in power outage situations.
• A bellows system filled with Argon is used to set
  the temperature set point of the valve.

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LHP Bypass Valve Schematic
(Argon)
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CAB Thermal System

• The Cryomagnet Avionics Box (CAB) is used to
  monitor and control the Cryomagnet.
• Heat dissipation can vary from 35W to 800W.
• Two Loop Heat Pipes (LHPs) will transport heat
  from the CAB base plate to the outer skin of the
  Wake Radiator.
• Final design details are under review.

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CAB Thermal System

• LHP are similar to Cryocooler LHPs, except that
  ammonia, rather than propylene will be used as
  the working fluid.
• A bypass valve on the LHP will be used to bypass
  the radiator if CAB temperature approach lower
  limits.

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CAB Thermal System
CAB
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CAB Thermal System

• Additional axial groove heat pipes will be
  attached on the USS between the Upper Trunnion
  Bridge Beam and the Upper Vacuum Case Interface
  Joint.

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TRD Thermal Design

• The TRD must be isothermal to /-3ºC
• The TRD and Upper Time Of Flight (UTOF) are
  enclosed in a common thermal enclosure made of
  MLI blankets.
• The Zenith Radiator is mounted on top of the TRD
  using low conductivity pins.
• Primary TRD interfaces to USS-02 joints are
  insulated with titanium spacers.

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TRD Thermal Design
Zenith Radiator
TRD
UTOF
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TRD Thermal Design

• The MLI blanket enclosure is made of 7-layer MLI,
  except for the portion under the Zenith radiator
  which is 10-layer.
• Heaters are mounted on the TRD M-structure to
  help minimize gradients and to maintain the
  detector components (flipper valves) within
  operating limits.

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TRD MLI
M-structure
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TRD Gas Thermal Design

• The TRD Gas system consists of two parts the
  Supply (Box S) and the Circulation (Box C).
• Box S includes a high pressure Xenon tank, a high
  pressure CO2 tank, a mixing tank, pre-heater
  volumes, valves, pressure sensors, and associated
  tubing all mounted on an aluminum base plate.
• Box C includes two pumps, monitoring tubes and
  valves.
• Both Box S and Box C are enclosed in an MLI
  blanket.

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TRD Gas Thermal Design
Circulation Box (Box C)
Xe Tank
Valve blocks
CO2 Tank
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TRD Gas Tank Heaters

• Active heating is required to keep both the Xenon
  and CO2 tanks above their respective saturation
  temperatures.
• This is required in order to measure the amount
  of gas left in the tanks.
• Extremely long time constants preclude short term
  heating only.
• The Xenon tank should stay above 20ºC
• The CO2 tank should stay above 34ºC

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TRD Gas Tank Heaters

• Kapton foil heaters are glued to the surface of
  the composite over-wrapped stainless steel tanks.
• On each tank there are two strings of eight
  heater patches (one per power feed).
• Four thermostats in series are used for each
  string to protect against over heating the tanks.
• Each tank is wrapped with MLI.

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TRD Gas Tank Heaters
heaters
thermostats
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TRD Gas Pre-Heaters

• A Pre-heater is used to warm small volumes of
  Xenon and CO2 making transfer to the mixing tank
  more controlled.
• Heater is computer controlled using temperature
  sensors on heater plate.
• Heater will only be activated for brief periods
  (lt15 minutes per day)
• 4 thermostats in series protects against over
  heating.

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TRD Gas Valve Blocks

• The are 5 groups of valves in Box S mounted
  together with support brackets.
• Brackets are isolated from the base plate with
  G10 spacers.
• Each block of valves is individually wrapped with
  MLI.
• Resistive heaters are mounted on each valve
  support bracket to maintain valves above
  operating limits.
• A single thermostat is used to control each valve
  block heater (Except for the tower valve which
  has 4 in series)
• Two additional thermostats in series are mounted
  on the base plate to control power to all valve
  heaters.

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TRD Gas Box C

• Box C pumps the low pressure gas mixture from Box
  S to the TRD detector.
• The two pumps are enclosed in a pressurized
  canister.
• Kapton foil heaters are mounted on this canister
  to maintain the pumps above their operating
  limits.
• Resistive heaters are mounted on a block of
  valves to maintain valve temperature limits.

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TRD Gas Box C
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TRD Gas Box C

• Both the canister heater and the valve block
  heater are each controlled with a single
  thermostat.
• The two additional thermostats on the base plate
  cut heater power in hot environments.

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TRD Gas 28V Heater Schematic
UPDATE
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TRD Gas 120V Heater Schematic
UPDATE
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Thermal Design of other AMS-02 Subsystems

• Extensive work has also been performed on the
  thermal design of other AMS-02 Detectors and
  subsystems not described here
• Designs include MLI, thermal fillers, thermal
  optical coatings, etc.
• None of these designs affect any pressure systems
  or other safety critical components.