Compression of3He by refluxing4He: A model for computing HEVAC effects in3He-4He mixtures

Abstract

This article comprises the first part of a study concerning the effect that a flow of gaseous4He has on the concentration distribution of3He atoms in the presence of a super fluid film. We present a simple model in which hydrodynamic effects in the gas phase (diffusion and viscosity), and local thermodynamic equilibrium with a superfluid film are considered. Results are derived and discussed for the simple case in which a heat flow is sustained along a cylindrical tube lined with a helium film. This heat flux drives a superfluid flow in the film, and a corresponding counterflow of4He in the vapour. The pressure, temperature,3He concentration, and film thickness profiles along the tube are computed. Over a wide range of conditions, a dramatic reduction of the3He concentration, a large temperature increase, and a spectacular film thinning towards hotter regions are predicted to result from a heat flow. The results of a series of experiments supporting this model will be presented in a forthcoming article.