Design and development of a ⁴He sub-Kelvin sorption cooler

The sub-Kelvin sorption cooler (SKSC) has emerged as a reliable and vibration-free solution for space cryogenics, establishing itself as a highly competitive choice. This paper focuses on the development of a ⁴He SKSC prototype designed for precooling an adiabatic demagnetization refrigerator (ADR). Based on the sorption refrigeration mechanism, the relationship between the amount of working medium and cooling performance is analyzed. Subsequently, each component of the SKSC is designed and constructed, resulting in the successful creation of a ⁴He SKSC prototype. Experimental testing demonstrates its capability to achieve a minimum temperature of 773 mK and provide a cooling capacity of 100 μW at 803 mK.