Adiabatic Demagnetisation Refrigerators for Space Applications 941279
We show that the space prohibitive laboratory adiabatic demagnetization refrigerator properties of high magnetic field and a <2K environment (provided by a bath of liquid He4) can be alleviated, without a significant decrease in operational efficiency, through the use of a 2 or 3 salt pill refrigerator rather then the classical single salt pill design. The additional salt pills providing intermediate cooling stages, enabling operation from a 4K environment which can be provided by a single mechanical cooler.
For such ADRs the minimum magnetic field required is 2 and 1 Tesla for the 2 and 3 salt pill cases respectively. Such low magnetic fields allow the possible use of permanent and high temperature mechanically cooled superconducting magnets, avoiding the danger of quenching of the superconducting magnet.
We conclude that such ADRs offer a long orbital life time, high efficiency means of sub Kelvin cooling.