Advances on a SPTC/JTC/ADR system for sub-Kelvin cooling

Sub-Kelvin cooling technologies are a critical technology for advanced deep space astrophysical observations. The configuration with adiabatic demagnetization refrigerator (ADR) precooled by Stirling-type pulse-tube cryocooler (SPTC) /Joule-Thomson cryocooler (JTC) is most attractive one for such space applications. In order to meet the demands of future national space science missions, the Technical Institute of Physics and Chemistry (TIPC, CAS) and the Shanghai Institute of Technology Physics (SITP, CAS) have carried out collaborative research. After separately optimizing SPTC, JTC, ADR, and efficient coupling of the three, a sub-Kelvin SPTC/JTC/ADR hybrid refrigeration system is proposed, built, and tested. The hybrid refrigeration system can achieve a no-load minimum temperature of 661 mK and maintain a temperature of 0.9 K without load for 3.78 h, setting the basis for the development of future space-application-targeted sub-Kelvin refrigerator.