Fig. 4

In the 1960’s, GM refrigerators using Pb cryostats began to be used, and in the 1990’s, the heavy rare earth magnetic cryostat HoCu₂was developed and has been used for the next 30 years. The frustrated CFAO developed in this study enables the same level of cryogenic cooling without using of rare earth elements. The values of annual production were taken from the references^{9, 33,34,35}.