Thermal conductivity of dilute 3He4He mixtures near the superfluid transition

We report new measurements of the effective thermal comhtetivity K,,t~ and rehtxation t#ne r in dilute mixtures of ~He in superjluid 4He, with mohu" concentrations X <~ 10 s. The temperature range extended fi'om T ~ 1.4 K to T;. Both ~",:t/ and r are found to agree with theoretical predictions, in contrast to previous experhnents where significant diJferences were observed. A new thermal comhtctivi O, cell design was used which ahnost comph, tely eliminates extraneous vohmws and surJ;tces, and the earlier results are e,\plahled h7 relation to these design changes.

Section: A Overviewmentioning

confidence: 99%

Heat transport in dilute mixtures of3He in superfluid4He

Murphy

Meyer

1997

Critical dynamics in the normal phase near the ?-transition in 3He-4He mixtures. I. Theoretical results

Moser¹,

Folk²

1992

We stud~, the asymmetric model of Siggia and Nelson for the critical dynamics of 3He-He mixtures above T~. The static effects resulting from the singular behavior of the susceptibilities are separated from genuine dynamic effects and treated in a consistent way. The calculated expressions for the thermal conductivity, thermal diffusion ratio and mass diffusion in the normal phase serve as a basis for a subsequent quantitative comparison with experiment. We use afield theoretical non-asymptotic renormalization procedure for our calculations. General relations resulting from the structure of the dynamical model for the mixtures are derived within this theoretical formulation.

Critical dynamics in the normal phase near the ?-transition in 3He-4He mixtures. II. Comparison with experiment

Moser¹,

Folk²

1992

We compare the experimental results for the temperature and concentration dependence of the thermal conductivity, the thermal diffuskm ratio and the mass diffusion near the ).-transition with the results of a nonsymptotic renormalization group calculation of these transport coefficients. Satisfactory agreement is obtained for the first two coefficients, but discrepancies remain for the mass diffusion.