Development of a Flight-Worthy 10 to 4 K Continuous Adiabatic Demagnetization Refrigerator

The cryogenics and fluids branch at NASA's Goddard Space Flight Center is currently developing a high-efficiency, vibration-free, flight-worthy Continuous Adiabatic Demagnetization Refrigerator (CADR) that consist of two modular units: one that lifts ~6 microW at 50 mK while rejecting its heat to a 4 K thermal sink, and another unit that provides a constant 4 K cooling stage while rejecting its heat to a thermal sink at 10 K. The two units are linked together via a 4 K common platform. This paper discusses the status report on the thermodynamic performance of the 4 -10 K ADR. This ADR utilizes an Nb3Sn superconducting magnet and Gadolinium Gallium Garnet (GGG) as its refrigerant. Results show that an idealized cycle, one where its hold time at 4 K is equal to the recycle time, can lift 13 mW at 4 K with a hold time of 132 seconds.