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 CO 2 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 ( W 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 100cm 2 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 Qua ntit y RAM radiator19 WAKE radiator13 J-crate2 JT-crate2 JPD crate2 Both Tracker radiators 26 TOTAL64

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): ItemQuantity RAM radiator49 WAKE radiator and PDS63 PDS interlock10 JPD10 Tracker radiator34 TOTAL166

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 CO 2 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 CO 2 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 CO 2 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 CO 2 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 Radiators Tracker Radiator (2 x m 2 )

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