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

• Designing and testing a prototype of a 4He sub-Kelvin sorption cooler for use in an adiabatic demagnetization refrigerator. • Achieving a minimum temperature of 773 mK and providing a cooling capacity of 100 μW at 803 mK. • Investigating the correlation between the quantity of the working medium and the overall refrigeration performance. • Discussing prospects for optimization and identifying challenges, with a focus on lowering cooling temperatures and extending hold time. 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. [ABSTRACT FROM AUTHOR]