A 1 K-Class Cryogenic System and its Coupling With SNSPD for Space Applications

The increasingly widespread application of superconducting nanowire single-photon detectors (SNSPDs) in space quantum communication, satellite laser ranging, and optical quantum computing has also generated a growing demand for compact, lightweight, and low-vibration cryogenic systems operating below 2 K. To meet the needs, a system consisting of a Stirling-type pulse tube cryocooler (SPTC) and a Joule-Thomson cryocooler (JT) has been developed, which has significant advantages in terms of low vibration, long lifetime and high reliability. This paper introduces and discusses the operating principle, system composition, and the process of optimizing cooling performance, with a particular focus providing detailed descriptions of the JT compressor unit, heat exchange system, coupling structure with the detector, and electrical control system. The integrated system is driven by a single multi-channel power supply, providing a total input power of 480 W to the overall system. Furthermore, cooling experiments and temperature stability tests of the cold head are conducted, and the cooling performances are compared when using either He-4 or He-3 as the working medium. The experimental results show that the no-load temperature is 1.85 K or 1.43 K with He-4 or He-3, respectively, while the temperature oscillation of the cold head remains within a range of less than ±5 mK.