Investigation on Dynamic Pressure Characteristics of a 5–7 K Three-Stage Stirling-Type Pulse Tube Cryocooler

The temperature range of 5–7 K is important for advanced high sensitivity space detectors. The multi-stage Stirling-type pulse tube cryocooler and J-T cryocooler were finally used in James Webb Space Telescope to meet the demand of cooling the mid-infrared instrument at 6.2 K. To explore the dynamic cooling characteristics of 5 –7 K, a thermal coupled three-stage Stirling type pulse tube cryocooler has been developed in SITP. The effects of pressure on the impedance characteristics and losses in the regenerator were analyzed with calculation programs in this study. In experimental tests, a no-load temperature of 3.96 K was reached with He-4, and a maximal cooling capacity of 24 mW at 5 K was obtained. The cooling capacity at 6 K and 7 K with three groups of charge pressures in the third stage were compared. A maximal cooling capacity of about 80 mW at 6 K was obtained when the charge pressure is 2.0 MPa. The test results are consistent with the model calculation and prediction, and it is expected to further optimize the cooling performance by adjusting pressure finely.