A Trial Construction of 3He/4He Dilution Refrigerator

A simple 3He/4He dilution refrigerator for the magnetic resonance and magnetic susceptibility measurements has been constructed. In the construction, some simplifications in the refrigerator operation have been intended so that sufficient time may be left for magnetic measurements without care of the refrigerator. The piping system in the room temperature is capable of use not only for the dilution refrigerator but also for 3He cryostat. The detail of the dilution refrigerator are given in the text. The lowest temperature obtained in continuous operation was 70m°K with the refrigerator having three sintered copper heat exchangers. In this case, 3He circulation rate was -4×10-6mol/sec. This rate is so small comparing with those of other refrigerators reported elsewhere. Further ameliorations are now in progress.