An Adiabatic Demagnetisation Refrigerator Stage: Salt-Pill Entropy Budget, Hold Time and Magnet Requirements

This paper presents a computed design for a adiabatic demagnetisation stage intended for magnetic refrigeration at low temperature, with its performance, resource budgets and margins derived from stated assumptions rather than asserted. The headline results are: usable entropy change of the pill between magnetised and demagnetised states of 9.34 J per K; cooling capacity at the 100 mK operating point of 934 mJ; hold time under the stated total load of 21.6 hours; mass of the salt pill of 0.404 kg; duty cycle allowing forty-five minutes to recycle of 0.966 dimensionless. Each figure was produced by the deposited computation from the inputs listed in the Methods, and the sensitivity of the conclusions to those inputs is examined in the Discussion. The design is a paper study: it is labelled, on its face and in this abstract, SIMULATED, NOT MEASURED, and no quantity reported here is a measurement of built hardware.