Ballistic propagation of thermal excitations near a vortex in superfluid He3-B

TL;DR

This paper models the trajectories of thermal excitations near vortices in superfluid He3-B, using Hamilton's equations to understand Andreev scattering and its implications for vortex dynamics and turbulence.

Contribution

It introduces a Hamiltonian framework for quasiparticle trajectories near vortices and extends the analysis to vortex gases, linking theory with experimental conditions.

Findings

Derived conditions for Andreev reflection of quasiparticles.

Estimated intervortex spacing consistent with experimental data.

Provided a theoretical basis for studying turbulence in superfluid He3-B.

Abstract

Andreev scattering of thermal excitations is a powerful tool for studying quantized vortices and turbulence in superfluid He3-B at very low temperatures. We write Hamilton's equations for a quasiparticle in the presence of a vortex line, determine its trajectory, and find under wich conditions it is Andreev reflected. To make contact with experiments, we generalize our results to the Onsager vortex gas, and find values of the intervortex spacing in agreement with less rigorous estimates.