Mechanical heat switch for cryogenic magnetic refrigerator

This work study the operating parameters of a cryogenic mechanical thermal switch, a detachable contact pair made of a alloy GdNi2 disk and a copper cylinder. The mechanical thermal switch operates in a vacuum in the temperature range of 8-325 K with a pressure of 250-350 kPa. The time of thermal equilibrium is studied at different contact areas with and without an indium thermal interface at an initial temperature difference of 0.8-10 K in the contact pair in the temperature range from 8 to 122 K. The temperature relaxation value is 33.7...39.9 seconds at a temperature difference of 3±0.14 K in the range of 50...122 K. Reducing the nominal contact area from 177 mm2 to 2.5 mm2 increases the temperature relaxation time at a temperature of 73.3 K from 36.6 to 63.5 seconds. This temperature range corresponds to the maximum magnetocaloric effect near the Curie temperature of the GdNi2 alloy. The values of the heat that must be removed to maintain the required temperature of the cooling object in a cryogenic magnetic refrigerator have been obtained.