Viscosity, ion mobility, and the λ transition

Abstract

A model is presented of the λ transition in superfluid helium in which fluctuations near the transition are approximated by distinct regions of normal fluid and superfluid. The macroscopic viscosity of such a medium is computed. The ion mobility is also computed, taking into account a region of normal fluid around the ion induced by electrostriction. The results are, for the viscosity, ηλ-η∼t^0.67 and for the mobility μ-μλ∼t^0.92 both in excellent agreement with recent experiments. The model suggests that the λ transition itself is the point at which superfluid regions become macroscopically connected.