Abstract
An experimental study is presented for the thermal conductivity κ and the thermal relaxation for dilute mixtures of3He in4He with concentration 9×10−4⩽X(3He)⩽5×10−2 at saturated vapor pressure and in the normal phase near the superfluid transition. The conductivity results for κ are compared with predictions by Dohm and Folk from field-theoretic renormalization group(RG) theory. The conductivity κ s =[κ−1(T)−κ−1(Tλ)]−1, is compared with Ahlers' phenomenological arguments, and also with predictions by Dohm and Folk and by Onuki. The temperature difference transient ΔT(t) across the fluid, measured as a function of timet after switching on and off the heat current, is analyzed. The thermal diffusion ratiokT and the mass diffusion coefficientD are obtained by fitting the calculated transient to the experimental one. The results are compared with the predictions that follow from the RG approach by Dohm and Folk. Very good agreement is obtained forkT. The transient is not very sensitive toD, and hence the determination is not accurate. Yet within the uncertainty, the deducedD also agrees with predictions. Appendices give (1) the corrections to κ from finite heat effects, (2) the calculation of the concentration susceptibility (∂X/∂Δ) T,P , and (3) the calculation procedure for κ,kT, andD using the RG approach of Dohm and Folk.
Published Version
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