Transport phenomena in /sup 3/He-/sup 4/He mixtures near the tricritical point

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:6264040

Ruppeiner, G

We have made extensive measurements on transport phenomena in /sup 3/He-He/sup 4/ mixtures near the tricritical point and along the superfluid transition line at saturated vapor pressure. The /sup 3/He mole fraction X ranged from 0.51 to 0.72 and the temperature from 0.8 to 1.6 K. Our measurements were made under steady state conditions using a cell where we measured the vertical /sup 3/He concentration gradient del X induced by a temperature gradient produced by a vertical heat flux. The cell included two superposed capacitors and del X was determined by means of the dielectric constant method. In this thesis, a comprehensive report on our results for the thermal diffusion ratio kappa/sub T/ and the thermal conductivity kappa both in the normal fluid and in the superfluid is presented. In the tricritical region k/sub T/ was found to diverge strongly as the tricritical point was approached; no singularity in kappa was found. This behaviour is consistent with theoretical predictions. In the region near the kappa remains finite, as expected, but k/sub T/ appears to have a stronger singularity than predicted by theory. The analysis of our experiment in the normal fluid for mixtures with X > 0.51 was complicated by superfluid film flow along the walls of the sample cell. We describe this effect and analyse it with Khalatnikov's theory of superfluidity. However, for the mixture X = 0.51, where there is no such film flow, the behaviour of k/sub T/ is consistent with pedictions. We also give, for the first time, a comprehensive test of Khalatnikov's theory in all regions explored where it should be valid. In addition, the k/sub T/ data for the mixtures 0.6 < X < 0.7 could be cast into a tricritical scaling representation similar to that for the concentration susceptibility. A discussion is given. Finally, the relaxation times that characterize the establishment of steady state conditions are discussed.

• Research Organization: Duke Univ., Durham, NC (USA)
• OSTI ID: 6264040
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
640450 -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DATA
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FLUIDS
HELIUM 3
HELIUM 4
HELIUM II
HELIUM ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
PHYSICAL PROPERTIES
QUANTITY RATIO
QUANTUM FLUIDS
RELAXATION
STABLE ISOTOPES
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
THERMAL CONDUCTIVITY
THERMAL DIFFUSIVITY
THERMODYNAMIC PROPERTIES