100 mK 以下二级绝热去磁制冷机的研究

High-performance low temperature detection technologies such as transition edge sensor (TES) and Kinetic Inductance Detectors (KIDS) are becoming more and more mature, which provides an opportunity for astronomers to solve key scientific problems such as “missing baryons” and primordial gravitational wave observation. These kinds of detectors need to work at very low temperatures (generally below 300 mK) to achieve its high sensitivity. As one of the important methods to obtain mK temperature, adiabatic demagnetization refrigerator (ADR) is a good candidate for cooling such high-performance low temperature detectors. In this paper, a two-stage adiabatic demagnetization refrigerator is described, and the refrigerant preparation of paramagnetic salt FAA is introduced. In the preliminary test, the ADR can obtain a temperature below 100 mK, which lays a foundation for subsequent research work.