Book Description

Measurements of the product of viscosity and normal density have been made for pure He4 and for three He3-He4 mixtures (He3 mole fractions x3 of 0.005, 0.0475, and 0.1005) over temperature intervals which included their respective Lambda points. The measurements were made using a torsional crystal technique in which a piezoelectric, cylindrical quartz crystal was immersed in the sample fluid and driven at its resonant frequency in a fundamental torsional mode of vibration. The precision of the viscosity and normal density -against-T measurements for the mixture was greater than any previous measurements in the vicinity of experimental Lambda temperature. Doubly reduced plots of viscosity and normal density against T showed a slight but definite tendency for such curves to rotate clockwise about the (1,1) point with increasing x3 up to about 0.05. Values of viscosity were derived from the measurements by computing normal density as a function of reduced temperature. For each mixture, both viscosity and d viscosity/dT were continous across experimental Lambda temperature. No tendency was manifest for such curves to develop discontinuities as x3 decreased. It was, therefore, inferred that both viscosity and d viscosity/dT of pure He4 are continuous across experimental lambda temperature of pure He4. A further result obtained here is that up to mole fractions of 0. 1, the Lambda viscosity of the mixture viscosity (x3) bears a linear relation to the Lambda temperature (x3).--P. [i].