Integration of Adiabatic Demagnetization Refrigerators with Spaceflight Cryocoolers

Cryogenic cooling is an increasingly vital technology for ultra-high-resolution space-based instruments. The vast majority of detectors for X-ray, infrared, and sub-millimeter radiation now rely on operating at very low temperature to achieve the sensitivities and low signal background required for the upcoming and future missions. Operating temperatures in the 50–100 mK range have become common, and some new detector technologies can benefit from even lower colder operation. Among the refrigeration techniques that can achieve such temperatures, adiabatic demagnetization refrigerators (ADR) have many advantages for space missions, including high efficiency, lack of gravity dependence, and wide operating range. However, as an inherently single-shot type of cooler, and one that requires relatively high current to drive the magnetic cycle, there are challenges for their implementation in space instruments and coupling to the cryocoolers and cryogenic systems that support their operation. In this chapter, we discuss these challenges, how they affect ADR and system design and operation, and options for optimizing performance and expanding capabilities to meet the demands of future space instruments.