³He/⁴He希釈冷却器のための1K熱交換器

抄録

For the condensation of ³He into ³He/⁴He dilution refrigerator, two types of 1K heat exchanger operated by ⁴He evaporation were designed. One is a disk type and the other is a coaxial counter-flow type heat exchanger. Each exchanger consists of a flow limiting impedance, a sintered copper heat exchanger, and a buffer volume for pumped liquid ⁴He. No moving part is included in the system. The exchanger is continuously supplied with liquid ⁴He through the impedance. Sufficient thermal exchange areas for ³He and ⁴He were obtained in a space of a few cubic centimeters by the use of sintered copper sponges. The small buffer volume for pumped liquid ⁴He, which forms the ⁴He-outlet of the exchanger, is useful to stabilize the temperature of the exchanger for an abrupt injection of heat load.
The exchanger can absorb approximately 10mW for molar flow rate of 2×10^-4 moles/sec of ⁴He. Therefore it is suitable as a 1K heat exchanger for a dilution refrigerator which has a maximum ³He circulation rate of 10^-4 moles/sec. As the exchanger requires a small spacing in the vacuum jacket of the dilution refrigerator, it will be useful for shortening the vertical length of the refrigerator.