AMS TIM July, 2008 – CERN 1
AMS 02 –Thermal Control
System Design
AMS-02 Thermal Control System (TCS)
AMS TIM July, 2008 – CERN 2
AMS 02 –Thermal Control
System Design
AMS-02 Thermal Overview
• Payload nominally dissipates 2400 watts (2800 watts peak) when fully operational
• 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
AMS TIM July, 2008 – CERN 3
AMS 02 –Thermal Control
System Design
AMS-02 TCS Hardware• Radiators• Heaters• Thermal Blankets• Loop Heat Pipes (LHP’s)
– Cryocoolers– CAB
• Standard Axial Groove Heat Pipes
• 2-Phase CO2 pumped loop
• Surface Optical Coatings
AMS TIM July, 2008 – CERN 4
AMS 02 –Thermal Control
System Design
Radiators
• AMS-02 radiators include – Main Radiators (Ram and Wake)
• Ram radiator dissipates heat from electronic crates (up to 525 watt)• Wake Radiator dissipates heat from electronic crates and the PDS
(up to 812 watt)
– Tracker Radiators (Ram and Wake)• Tracker radiators reject the 144 watt of the Tracker, transported by
the TTCS
– Zenith Cryocooler Radiators (4 panels)• Zenith panels radiate the power of 4 cryocoolers, 400W in total,
carried by 8 LHP
AMS TIM July, 2008 – CERN 5
AMS 02 –Thermal Control
System Design
Main Radiators Mounting• Main Radiators are mounted directly to the
crates, which in turn are attached to the USS-02
Lower Brackets (4)
Upper Brackets (4)
Mid Bracket (4)
AMS TIM July, 2008 – CERN 6
AMS 02 –Thermal Control
System Design
Main Radiator Construction• Radiators are a sandwich construction with Al
face sheets and a ROHACELL® core. • Axial grooved heat pipes (aluminum filled with
ammonia) are imbedded between face sheets.• Chotherm 1671 is used as a thermal interface
filler between crates and radiators.• Radiators are painted with SG121FD white paint
to optimize heat rejection.
AMS TIM July, 2008 – CERN 7
AMS 02 –Thermal Control
System Design
AMS TIM July, 2008 – CERN 8
AMS 02 –Thermal Control
System Design
AMS TIM July, 2008 – CERN 9
AMS 02 –Thermal Control
System Design
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 later.
AMS TIM July, 2008 – CERN 10
AMS 02 –Thermal Control
System Design
AMS TIM July, 2008 – CERN 11
AMS 02 –Thermal Control
System Design
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.
• 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.
AMS TIM July, 2008 – CERN 12
AMS 02 –Thermal Control
System Design
AMS TIM July, 2008 – CERN 13
AMS 02 –Thermal Control
System Design
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 (LHP’s) attached to a single cryocooler.
• The LHP’s 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.
AMS TIM July, 2008 – CERN 14
AMS 02 –Thermal Control
System Design
4 Zenith Radiator Panels
AMS TIM July, 2008 – CERN 15
AMS 02 –Thermal Control
System Design
Zenith Radiator Construction• Radiators are a sandwich construction with Al face
sheets and a ROHACELL® core. • 3mm aluminum tubes are glued to upper face
sheet, inside the sandwich• 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.
AMS TIM July, 2008 – CERN 16
AMS 02 –Thermal Control
System Design
Zenith Radiator Installation
AMS TIM July, 2008 – CERN 17
AMS 02 –Thermal Control
System Design
Multi-Layer Insulation (MLI) Blankets
AMS TIM July, 2008 – CERN 18
AMS 02 –Thermal Control
System Design
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)
• Typical construction will include multiple layers of aluminized Mylar separated by Dacron scrim. Betacloth will protect exposed surfaces.
AMS TIM July, 2008 – CERN 19
AMS 02 –Thermal Control
System Design
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.
– System recovery in case of extended power outages in cold environments.
– Manage TTCS operation
AMS TIM July, 2008 – CERN 20
AMS 02 –Thermal Control
System Design
Heaters (continued)
• Most heaters are both thermostatically and computer controlled. – Most heaters will not be operated on the
ground• Analyses have been performed to evaluate
effect of “run away” heaters. • All safety critical heaters are two-fault tolerant.
AMS TIM July, 2008 – CERN 21
AMS 02 –Thermal Control
System Design
Heat Pipes
• Standard axial groove heat pipes are used in several locations to help distribute heat
• All heat pipes are aluminum filled with high purity ammonia.
• Heat pipes are designed to survive freezing/thawing cycles
AMS TIM July, 2008 – CERN 22
AMS 02 –Thermal Control
System Design
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 (LHP’s), provided by IberEspacio/Madrid, are similar to those successfully demonstrated as part of COM2PLEX flown on STS-107.
AMS TIM July, 2008 – CERN 23
AMS 02 –Thermal Control
System Design
Loop Heat Pipe System
ZENITH RADIATOR
CRYOCOOLER
AMS TIM July, 2008 – CERN 24
AMS 02 –Thermal Control
System Design
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 (LHP’s) will transport heat from the CAB base plate to the outer skin of the Wake Radiator.
AMS TIM July, 2008 – CERN 25
AMS 02 –Thermal Control
System Design
CAB Thermal System
• LHP are similar to Cryocooler LHP’s, 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.
AMS TIM July, 2008 – CERN 26
AMS 02 –Thermal Control
System Design
AMS TIM July, 2008 – CERN 27
AMS 02 –Thermal Control
System Design
Conclusion (1/2)
• 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 washers– thermal optical coatings– heaters and thermostats.
AMS TIM July, 2008 – CERN 28
AMS 02 –Thermal Control
System Design
Conclusion (2/2)
• Safety controls include:– Restricted access to AMS-02 when it is
charged, thus limiting risk of personnel contact with radiators.
– Design of TCS precludes hot spots.– Most payload heaters will not be operated on
the ground.– All safety critical heaters are two-fault tolerant.
AMS TIM July, 2008 – CERN 29
AMS 02 –Thermal Control
System Design
Backup slides
AMS TIM July, 2008 – CERN 30
AMS 02 –Thermal Control
System Design
TYPICAL RADIATOR INSERTS
AMS TIM July, 2008 – CERN 31
AMS 02 –Thermal Control
System Design
TTCS Condenser Mounting Interface
AMS TIM July, 2008 – CERN 32
AMS 02 –Thermal Control
System Design
Zenith Radiator Cross-Section
Radiator Mounting
Radiator Cross-section
AMS TIM July, 2008 – CERN 33
AMS 02 –Thermal Control
System Design
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 (<) 5,000 Ohms
– Resistance from ground to spacecraft structure shall be less than (<) 1 Ohm
AMS TIM July, 2008 – CERN 34
AMS 02 –Thermal Control
System Design
Heater summary:
Item Quantity
RAM radiator 19
WAKE radiator 13
J-crate 2
JT-crate 2
JPD crate 2
Both Tracker radiators 26
TOTAL 64
AMS TIM July, 2008 – CERN 35
AMS 02 –Thermal Control
System Design
Thermostats
• Heater circuits are thermostatically controlled:– For a progressive heating of the radiator panel at the
activation (close-on-rise)– For avoid overheating of the radiator and the
electronics– For safety (i.e. to avoid excessive overheating of the
heat pipes, containing pressurized ammonia)– For power saving
• Once the temperature is reached there is no need to continue supplying power
AMS TIM July, 2008 – CERN 36
AMS 02 –Thermal Control
System Design
Safety thermostats assessment: RAM radiator results
• Max Design temperature is 114 °C
• Max reached temperature is
82°C.
AMS TIM July, 2008 – CERN 37
AMS 02 –Thermal Control
System Design
Safety thermostats assessment: WAKE radiator results
• Max Design temperature is 114 °C
• Max reached temperature is
103°C.
AMS TIM July, 2008 – CERN 38
AMS 02 –Thermal Control
System Design
Thermostats• 166 thermostats, including spares.
• These thermostats are located on – RAM radiator– WAKE radiator– Tracker radiators– inside the PDS and – on the JPD main wall feet.
AMS TIM July, 2008 – CERN 39
AMS 02 –Thermal Control
System Design
Thermostats quantities (including spares):
Item Quantity
RAM radiator 49
WAKE radiator and PDS 63
PDS interlock 10
JPD 10
Tracker radiator 34
TOTAL 166
AMS TIM July, 2008 – CERN 40
AMS 02 –Thermal Control
System Design
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).
AMS TIM July, 2008 – CERN 41
AMS 02 –Thermal Control
System Design
Crycooler to LHP Interface
Cryocooler
• LHP Evaporators bolt to either side of the Cryocooler heat reject collar.
• Indium foil is used as a thermal interface.
Evaporator
AMS TIM July, 2008 – CERN 42
AMS 02 –Thermal Control
System Design
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.
AMS TIM July, 2008 – CERN 43
AMS 02 –Thermal Control
System Design
LHP Bypass Valve Schematic
(Argon)
AMS TIM July, 2008 – CERN 44
AMS 02 –Thermal Control
System Design
TRD GAS BOX TCS
AMS TIM July, 2008 – CERN 45
AMS 02 –Thermal Control
System Design
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.
AMS TIM July, 2008 – CERN 46
AMS 02 –Thermal Control
System Design
TRD Gas Thermal Design
Xe Tank
CO2 Tank
Circulation Box (Box C)
Valve blocks
AMS TIM July, 2008 – CERN 47
AMS 02 –Thermal Control
System Design
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
AMS TIM July, 2008 – CERN 48
AMS 02 –Thermal Control
System Design
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.
AMS TIM July, 2008 – CERN 49
AMS 02 –Thermal Control
System Design
TRD Gas Tank Heaters
heaters
thermostats
AMS TIM July, 2008 – CERN 50
AMS 02 –Thermal Control
System Design
WAKE RADIATOR
AMS TIM July, 2008 – CERN 51
AMS 02 –Thermal Control
System Design
Tracker RadiatorsTracker Radiator (2 x 1.225 m2)
AMS TIM July, 2008 – CERN 52
AMS 02 –Thermal Control
System Design
Safety thermostats assessment
• Analysis shows that the contemporary presence of all the heaters does not bring radiators skin temperature to the maximum design temperature for the Heat Pipes (114°C).
• Safety thermostats have been removed
AMS TIM July, 2008 – CERN 53
AMS 02 –Thermal Control
System Design