Progress on An 8 K gas-coupled three-stage Stirling pulse tube cryocooler

Stirling pulse tube cryocoolers hold significant potential for cooling in miniaturized devices. This paper investigates the numerical design and optimization of a gas-coupled three-stage Stirling pulse tube cryocoolers, which has been validated by subsequent experiments. Following the optimization of the length of inertance tube and the configuration of double-inlet at the third stage, the prototype has achieved a minimum no-load temperature of 8.6 K and a cooling capacity of 25 mW at 9.5 K with an input electrical power of 500 W. To the best of our knowledge, the lowest temperature of Stirling pulse tube cryocoolers reaches below 10 K, which can be used as one of the research routes for small pulse tube cryocoolers in the liquid helium temperature.