Propagation of thermal excitations in a cluster of vortices in superfluid 3He-B

TL;DR

This paper reports the first experimental measurement of Andreev scattering of thermal excitations by a known vortex cluster in superfluid 3He-B, comparing results with numerical models of quasiparticle propagation.

Contribution

It introduces the first measurement of thermal excitation scattering in a controlled vortex configuration in superfluid 3He-B, combining experimental data with numerical simulations.

Findings

Measured heat flow affected by vortex cluster configuration.

Experimental results agree with ballistic quasiparticle propagation models.

Provides insights into vortex-thermal excitation interactions in superfluid 3He-B.

Abstract

We describe the first measurement on Andreev scattering of thermal excitations from a vortex configuration with known density, spatial extent, and orientations in 3He-B superfluid. The heat flow from a blackbody radiator in equilibrium rotation at constant angular velocity is measured with two quartz tuning fork oscillators. One oscillator creates a controllable density of excitations at 0.2Tc base temperature and the other records the thermal response. The results are compared to numerical calculations of ballistic propagation of thermal quasiparticles through a cluster of rectilinear vortices.