A high-capacity 1-K cryogenic system pre-cooled by pulse tube cryocooler

A 1-K cryogenic system can provide a stable and necessary low-temperature environment for some fields such as quantum computing, condensed matter physics research, and cryogenic scientific instruments. Specifically, in the field of basic research, 1 K is an ideal condition for studying quantum phenomena in low-temperature physics, such as quantum Hall effect and topological phase transition; in the field of technical applications, 1 K is a necessary condition for some quantum devices, such as superconducting quantum interferometers and single-photon detectors, to achieve high-sensitivity operation; in the field of ultra-low temperature technology, 1 K is the pre-cooling stage of refrigeration technologies, such as dilution refrigerators, and is also the basis for further achieving mK temperature ranges and lower temperatures. At present, in most of domestic 1-K systems, GM (Gifford-McMahon) cryocoolers are used for pre-cooling. These systems encounter some difficulties in achieving lower vibration control, lower electrical noise interference, lower pre-cooling temperature, and higher liquefaction efficiency. The 1-K systems based on pulse tube cryocoolers pre-cooling have inherent advantages in solving these problems. In this work, a 4-K GM-type pulse tube cryocooler is first developed by using a domestic helium compressor and a developed rotary valve, and the cold-end heat exchanger and the room-temperature phase shifters are redesigned in order to achieve a minimum cooling temperature of 2.14 K, and provide 1.5 W at 4.2 K and 45 W at 45 K cooling capacity simultaneously. With the home-made pulse tube cryocooler as the pre-cooling stage, a 1-K cryogenic system is further constructed. By designing key components such as JT flow resistance, combined thermal switch, and anti-superflow structure, a minimum cooling temperature of 1.1 K is achieved, with a cooling capacity of 100 mW at 1.6 K. This study lays an important foundation for subsequently developing dilution refrigerators with larger cooling capacity.