Simulations of a Thermal Conductivity Cell Filled with Normal 4He and Dilute Mixtures of 3He in Superfluid 4He

Abstract

We have simulated the thermal response of a cylindrical thermal conductivity cell filled with liquid helium to AC and DC heat fluxes. The conductivity cell in these simulations is realistic in that it includes sidewalls and gaps, which cannot be treated analytically or in a one-dimensional simulation. Our simulations are to able to account quantitatively for the apparent departure of the effective thermal conductivity, κ eff , of dilute mixtures of 3 He in superfluid 4 He from theoretical predictions. We have recently demonstrated experimentally that this departure is due to the presence of gaps in previous thermal conductivity cells. These simulations also show that the additional phase lag in the response of normal 4 He to an AC heat flux, measured by Olafsen and Behringer, is due to gaps in the heated plate.