Preliminary test of the integrated sorption cooler for an adiabatic demagnetization refrigerator (ADR)

Abstract

The sorption cooler composed of the sorption pump and the thermosiphon is developed and tested. The developed cooler is planned to be integrated with the adiabatic demagnetization refrigerator (ADR) to provide cooling capacity at sub-kelvin temperature without vibration. The sorption cooler aims to cool the magnetic material of the ADR from 4.5 K to 2.5 K with the cooling capacity of 2.5 J. The working fluid of the cooler is helium-4. The sorption pump is filled with activated charcoal of 5.2 g and its temperature is regulated from 5 K to 30 K. To simulate the high heat capacity of the magnetic material, this study utilizes liquid helium as a thermal capacitor. In the experiment, the cooler refrigerates the thermal capacitor to 3 K from 4.5 K heat sink with the cooling capacity of 2.1 J. Cooling loss mostly occurs due to the radiative heat ingress which can be negligible when the sorption cooler is integrated with the ADR. Furthermore, the experiment identifies that the void volume of the thermosiphon affects on the evaporation speed of liquid helium. The detailed experimental results are presented and discussed in this paper.