The thermal performance model of a 105 [email protected] K 4He Joule-Thomson cryocooler designed for space applications

• The thermal performance model of the space 4 He Joule Thomson cryocooler (JTC) precooled by atwo-stage thermally coupled PTC is presented. • The 4 He JTC can provide a cooling power of 105 mW at 4.41 K with a total input electric power of 548 W. • A large, flat surface for installing loads is provided by an evaporator with spiral flow channels in this 4 He JTC. The 4 He Joule-Thomson cryocooler (JTC) ensures the operation of space detectors working within the 4 K temperature range, such as the Block Impurity Band Infrared Detector (BIBID). In addition, the 4 He JTC is one of the essential components of the 300 K to 50 mK space cryochain. It can precool sub-Kelvin refrigerators, such as the adiabatic demagnetization refrigerator (ADR) and the dilution refrigerator (DR). With the development of space science, the need for cooling power at the 4 K temperature range is growing. Thus, a thermal performance model of the 4 He JTC precooled by a two-stage thermally coupled pulse tube cryocooler (PTC) is designed, manufactured, and tested with an eye toward space applications. A four-stage compression system with a high operating frequency and large pistons is designed and used to drive the JT cycle. This 4 He JTC has a total mass of 55 kg and can provide a cooling capacity of 105 mW at 4.41 K with a total input electric power of 548 W.