Experimental results of a modified condensation-driven dilution refrigerator by adding a step heat exchanger

Abstract Condensation-driven dilution refrigerator uses a condenser to liquefy the 3 He vapor and achieve the circulation of the 3 He, which can meet the requirements of specific applications, such as the forthcoming generation of cosmic microwave background observatories. In 2023, we built a condensation-driven dilution refrigerator with a no-load temperature of 68 mK, and the cooling performance needs further improvement. In this paper, the condensation-driven dilution refrigerator is modified, and a step heat exchanger with sintered silver powder is added to the system. The step heat exchanger with a total surface area of 3 m 2 is designed to efficiently meet the heat transfer requirements. In the experiments, the no-load temperature of 55.3 mK and a cooling power of 7.4 μW @100 mK were achieved in the modified system.