Sunpower's CPT60 Pulse Tube Cryocooler

Sunpower, Inc. in collaboration with Gedeon Associates has developed a new model of single stage, coaxial pulse tube cryocooler, the CPT60, through funding from Smach (SMArt teCHnologies) Co., Ltd. of Osaka, Japan. The CPT60 achieves 2 W of cooling power at 60 K with 100 We of input power and 37° C reject temperature (8.3% of Carnot) using forced air cooling with the cold head positioned cold-end-up. A dual-opposed piston configuration minimizes vibration and the coaxial cold head configuration results in a compact package and the appearance of a "Stirling-style" cold finger. The CPT60 makes use of Sunpower's half-wave inertance technology for acoustic tuning that eliminates the need for a buffer volume at the end of the inertance tube resulting in a smaller overall package. An overriding goal in the development program was to make use of Sunpower's successful Stirling cryocooler technology in two ways: 1) to use components directly available from the CryoTel Stirling cryocooler manufacturing line, and 2) to make customer interfaces and the overall cryocooler appearance as similar as possible to the CryoTel. After successfully testing a water-cooled prototype, the CPT60 was redesigned for hermetic sealing and air cooling. Three hermetic units were produced, tested and delivered to Smach.