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Abstract

This paper describes the design, development, testing, and performance of the Ball Aerospace SB235 and SB235E long-life, two-stage space cryocoolers. The SB235 and SB235E are two-stage coolers designed to provide simultaneous cooling at 35 K (typically for HgCdTe detectors) and 85 K (typically for optics). The SB235 qualification unit was delivered to Air Force Research Laboratory (AFRL) for life testing and has accrued more than 13,000 hours as of May 2006. The SB235E is a higher capacity derivative of the SB235 that has undergone initial performance testing. The SB235E is the precooler for the 35 K High Capacity Variable Load Cryocooler and 10 K High Capacity Cryocooler Programs under development at Ball Aerospace. Initial testing of the SB235E has shown performance of 2.64 W at 35 K and 10.4 W at 85 K for 255 W of power, which equates to Carnot efficiency about 50% higher than that of other published cryocooler data. Mass of the SB235E cooler is 14.4 kg for the compressor and displacer.