Thermal Switches
Function
Autonomous thermal switches allow multiple cryogenic cooling systems such as cryocoolers to redundantly control sensitive IR sensors. The thermal switches are autonomous, requiring no electronics to control the switching mechanism and they are actuated by a temperature difference across the switch. As the cold side of the switch is cooled sufficiently, the switch closes allowing heat to be transferred to the cold heat sink (cryocooler). If a cooler fails or is switched off, the cold side of the switch will warm up, causing the switch to open, thus thermally isolating the failed cooler from the operating system. Additionally, the simplified thermal switch movement design decreases tolerance requirements and improves reliability.
TMT was selected to design, fabricate, and test thermal switches for NASA's JWST program.
Thermal Performance
- Thermal impedance (when actuated): 3 K/W
- Thermal impedance (when off): 2500 K/W
- Actuation temperature: 210 Kelvin
Applications
Thermal Switches are among the other TMT technologies in the TMT commercialization pipeline. High volume applications for thermal switches include transient cooling of electronics in missile deployment.
- Spacecraft
- Missile avionics
- Wherever the heat path must be modified during system operation
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