Cryogenic Cooling of Infrared Electronics

Infrared detection devices generally require approximately 1 W of cooling at 10 to 100 K. Among the cryocoolers currently available commercially, closed-cycle devices offer advantages over open-cycle types in terms of logistics of storage and maintenance, compactness, and light weight. Reciprocating devices, such as those operating on the Stirling, Vuilleumier, Solvay, and Ericsson cycles, appear generally suitable. Devices incorporating Joule-Thomson (J-T) expansion valves suffer from potential clogging of the active element, the valve. Thermoelectric (Peltier) devices are conceptually attractive, but material limitations have prevented their development for the cooling range of interest. Turbo cryocoolers are potentially attractive because they experience no pressure or force fluctuations, but are perhaps more suitable for larger cooling loads. Each cryocooler application has special needs that can best be met with a custom design that is specified early in the system program in cooperation with the cryocooler and electro-optic designers. A number of U.S. and foreign manufacturers produce closed-cycle cryocoolers suitable for IR detectors. Generally, these devices have a cooling capacity of about 0.25-2.0 W at about 80 K. Those currently available are predominantly Stirling cycles, including both split and integrated versions, although there are also several Joule-Thomson devices and a few Vuilleumier and Gifford-McMahon units. Many organizations are doing sponsored and proprietary research in cryocooler technology. Essentially, research and development can be classified in terms of cycle analysis, loss mechanisms, regenerator development, heat exchanger and contamination elimination. Operated by IIT Research Inst., Chicago, IL. Sponsored in part by DLA/DTIC.