A new strategy for achieving multiple continuous cooling stages in an adiabatic demagnetization refrigerator

This paper presents a three-stage continuous adiabatic demagnetization refrigerator (CADR) simultaneously providing cooling platforms at two different temperatures. Unlike conventional CADR with two continuous stages, this system does not require an extra continuous stage. It is achieved with carefully designed heat switch operations and stage sequences. This new strategy significantly reduces system complexity and mass. The detailed implementation of the two cooling platforms is described, and factors limiting system performance are analyzed. This CADR system has achieved a cooling power of 20 μW@1 K and 4 μW@300 mK simultaneously, offering a new design strategy for the development of CADR with multiple continuous stages.