Current status of ADR development at NASA Goddard Space Flight Center and future applications

Low temperature refrigeration is an increasingly vital technology for NASA's Space Science program. Ultra-sensitive detectors for x-ray, IR and sub-millimeter missions must be cooled below 0.1 K in order to reach their fundamental limits for energy and spatial resolution. Moreover, the ability to fabricate large arrays of these detectors means the cooler must have relatively large cooling power. Infrared missions also require telescope cooling into the 4 K range. Since the lifetime requirements for these missions go well beyond what is achievable with stored cryogen systems, the low temperature coolers for future missions must be able to use cryocoolers, operating at temperatures in the 4-10 K range, for pre-cooling. There is also a demand for laboratory coolers for developing the detectors and instruments for these missions. To meet these cooling requirements, we have developed several types of adiabatic demagnetization refrigerators (ADRs): a continuous ADR (CADR) that operates continuously at temperatures of 0.035 K and above for detector cooling in space; a CADR version for laboratory use; a quick turn around ADR system for detector development; and a multistage, higher cooling power CADR for cooling telescopes.