Development of a low-temperature 3He compressor for superfluid 3He–4He mixtures

The development, testing and modeling of a “compressor” that is capable of increasing the concentration of the 3He component of a liquid superfluid 3He–4He mixture is discussed. This compressor was developed to drive refrigeration cycles for cooling below 1 K. The compressor design and performance testing is described in detail. The compressor was operated at 1.2 K and 3He molar flow rates of 130 μmol/s were achieved. Compression ratios in excess of 6 were also demonstrated. The theoretical models presented are used to estimate the expected efficiencies of the compressor as well as the effect of the 4He component on the power required to drive the compressor.