 
Summary: Proceedings of the 1998 NASA/JPL Microgravity Fundamental Physics
Workshop, Oxnard, CA, June 2325, 1998
FiniteSize and Gravity Effects on the Thermal
Conductivity of 4
He near T
Guenter Ahlers
Department of Physics and Center for Nonlinear Science,
University of California, Santa Barbara, California 93106
Abstract
This paper reviews the opportunities for microgravity and groundbased measure
ments of the thermal conductivity (t, L) near the bulk superfluidtransition line
T(P) of 4He confined in cylindrical geometries with axial heat flow. It provides an
evaluation of existing data near T at saturated vapor pressure (SVP) in cylinders
of L = 1µm radius, and uses these to derive a scaling function for the resistivity
R(t, L) = 1/(t, L). The purpose of future measurements over a wide range of L
and of the pressure P will be to test the applicability of this function. In the present
paper the scaling function is used to predict the conductivity for other values of L
and P. These predictions are used to assess quantitatively the effect of gravity on
potential Earthbased measurements. It is found that the gravity effect for R is par
ticularly severe below T. The estimate of the gravity effect provides the foundation
