Thermal transport properties of the helium near the superfluids transition II. Dilute /sup 3/He-He mixtures in the superfluid phase
Measurements of the average thermal conductivity k/sub exp/ is identical to hQ/BETAT and of the thermal relaxation time GAMMA to reach steady-state equilibrium conditions are reported in the superfluid phase for dilute mixtures of /sup 3/He in /sup 4/He. Here h is the cell height, Q is the heat flux, and BETAT is the temperature difference across the fluid layer. The measurements were made over the impurity range 2 x 10/sup -9/ < x (/sup 3/He) < 3 x 10/sup -2/ and with heat fluxes 0.3 < q < 160 ..mu.. w/cm/sup 2/. Assuming the boundary resistance R /sub b/, measured for x < 10/sup -5/, to be independent of x over the whole range of x, a calculation is given for k/sub exp/. for Q smaller than a well-defined critical heat flux Q /sub c/ (X) proportional to X/sup 0.9/, k/sub exp/. for Q of Q and can be identified with the local conductivity K/sub eff/, which is found to be independent of the reduced temperature epsilon = (T - T/sub lambda/)/ T/sub lambda/ for -epsilon less than or equal to 10/sup -2/ from the prediction extrapolated value at T/sub lambda/ is found to depart for X less than or equal to 10/sup -3/ from the prediction k/sub lambda/ proportional to X/sup -1/, tending instead to a weaker divergence k/sub lambda/ proportional to X/sup -a/ with aapprox. = 0.8. A finite conductivity as X tends to zero is not excluded by the data, however. For Q > Q/sub c/ (X) a nonlinear regime is entered. for X less than or equal to 10/sup -6/, the measurements with the availavle temperature resolution are limited to the nonlinear conditions, but can be extrapolated into the linear regime for X greater than or equal to 2 x 10/sup -7/. the results for K /sub exp/ (Q), Q/sub c/ (X), and k /sub eff/ (XX) are found to be internally consistent, as shown by comparison with a theory by Behringer based on Khalatnikov's transport equations.
- Research Organization:
- Dept. of Physics, Duke Univ., Durham, NC
- OSTI ID:
- 6732741
- Journal Information:
- J. Low Temp. Phys.; (United States), Vol. 65:3/4
- Country of Publication:
- United States
- Language:
- English
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The thermal transport properties of dilute sup 3 He- sup 4 He mixtures near the superfluid transition temperatures
Thermal transport properties in dilute sup 3 He- sup 4 He mixtures near the superfluid transition
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HELIUM 3
SUPERFLUIDITY
THERMAL CONDUCTIVITY
HELIUM 4
BINARY MIXTURES
DATA COVARIANCES
EXTRAPOLATION
HEAT FLUX
NONLINEAR PROBLEMS
RELAXATION TIME
RESOLUTION
STEADY-STATE CONDITIONS
TEMPERATURE MEASUREMENT
THERMAL BOUNDARY RESISTANCE
DISPERSIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MIXTURES
NUCLEI
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
640450* - Fluid Physics- Superfluidity