³He Refrigerator Based on Closed Cycle Cryocooler Cooling

In the Laboratory of Neutron Physics of the Joint Institute for Nuclear Research, work is underway to create gaseous neutron detectors. To prepare a working mixture of gases, it is necessary to use pure ³He, which is obtained by freezing impurities. The ³He refrigerator was created for this purpose. The refrigerator can also be used to obtain low temperatures in a physics experiment. In this work, the operating modes of the refrigerator are studied. In the continuous mode of ³He circulation, a temperature of 0.78 K was obtained. When ³He vapor is pumped out by an external pump in a single cooling mode, a temperature of 0.52 K is reached. We also study relaxation modes in which, with pre-condensed ³He, the volume of the container plays the role of a pump. A regime is presented in which the temperature of the evaporator relaxes from 1 to 1.5 K within 11 days.