Showing papers on "Heat current published in 1988"
TL;DR: A nonlocal theory of thermal conductivity for the case in which the heat is carried by phonons is derived and is used to explain some previous experiments in silicon.
Abstract: We have derived a nonlocal theory of thermal conductivity for the case in which the heat is carried by phonons. There is a nonlocal relation between the heat current J(r) and the temperature gradient \ensuremath{
abla}T(r'). The nonlocal theory is needed whenever the phonon mean free path is long compared to the distance scale of the variation in \ensuremath{
abla}T. The theory is used to explain some previous experiments in silicon.
103 citations
TL;DR: Experimental results for the depression of the superfluid transition temperature T/sub lambda/(Q) in /sup 4/He by a heat current Q are reported.
Abstract: We report experimental results for the depression of the superfluid transition temperature T/sub lambda/(Q) in /sup 4/He by a heat current Q. The data were obtained by use of thermometry with a resolution of 10 nK, and cover the range 0.4approx.
54 citations
01 May 1988
TL;DR: In this paper, the authors studied the general case of one-dimensional heat conduction in systems, whose conductivity is a function of both temperature and the coordinate in the heat flux direction.
Abstract: Starting from the results of Li, Prigogine and others about the one-dimensional heat conduction with constant temperature boundary conditions, the aim of this paper is to study, according to the methods and the purposes of the generalized thermodynamics, the more general case of one-dimensional heat conduction in systems, whose conductivity is function of both temperature and the coordinate in the heat flux direction and presents a finite number of discontinuities.
16 citations
7 citations
TL;DR: In this article, the thermal conductivity of 17 alkali halides has been calculated with a variational method, and it is shown that the relative contributions to the scattering integral from different combinations of branches are strongly correlated to the mass ratio of the two constituent ions.
Abstract: The thermal conductivity of 17 alkali halides has been calculated with a variational method. The calculations confirm previous results from relaxation-time calculations on NaCl and KCl that optic phonons are important in both the heat current and the scattering processes. It is found that the relative contributions to the scattering integral from different combinations of branches are strongly correlated to the mass ratio of the two constituent ions. On the other hand the amount of heat carried by optic phonons is more dependent on the ratio of the static and optic dielectric constants, epsilon 0/ epsilon infinity , than on the mass ratio. The theory of mirror pairs has been applied in an analysis of the thermal conductivity data. It is shown that experiments on Li and LiBr would be a critical test of the variational calculations.
3 citations