High-Tc thermal bridges for space-borne cryogenic infrared detectors
✍ Scribed by S.A. Wise; J.D. Buckley; I. Nolt; M.W. Hooker; G.H. Haertling; R. Selim; R. Caton; A.M. Buoncristiani
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 829 KB
- Volume
- 1
- Category
- Article
- ISSN
- 0964-1807
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✦ Synopsis
Several space-borne infrared detectors require cryogenic temperatures for successful operation. As a result, mission durations are substantially limited due to cryogen evaporation. The electrical leads connecting the detectors to the amplification electronics comprise a significant portion of the heat load on the dewar (i.e., 20% for some systems). Currently, manganin wires ate used for these connections, due to the alloy's low thermal conductive at cryogenic ~rn~~~s. However, replacement of these leads with high Tc materials would result in a substantial reduction in thermal loss, translating into approximately lo-15% enhancement in mission lifetime. The potential for using the high-Tc materials as thermal bridges to replace the manganin connections is currently under investigation at NASA-LaRC.
The National Aeronautics and Space Administration (NASA) is currently pursuing several experiments designed to evaluate both the present condition and future changes in Planet Earth by monitoring the concentration of chemical radicals present in the upper a~osphe~.lI Several infrared sensors used for detection in these systems require liquid helium cryogenic refrigeration for optimum signal-to-noise performance.21 As a result, the useful mission lifetime is limited by the rate of cryogen evaporation. All heat loads on the system are considered critical, and efforts am made to minimize all sources of thermal loss.
One nonparasitic heat load on the dewar system is the electrical instrumentation, specifically the electrical connections between the sensors and the data acquisition and storage