UNIFORM TEMPERATURE COOLING POWER OF THE SUPERFLUID STIRLING REFRIGERATOR

Uniform temperature cooling power measurements of a superfluid Stirlin g refrigator are presented for He-3-He-4 molar concentrations of 5.9%, 17% and 36% and for temperatures between 0.37 K and 1.4 K. The result s are compared to an ideal Fermi gas model and to a more general therm odynamic model. The Fermi model agrees well with the 5.9% concentratio n data; however, the more elaborate model is needed for higher concent ration mixtures.