Magnetic induction in a turbulent flow of liquid sodium: mean behaviour and slow fluctuations

TL;DR

This study investigates magnetic induction in a turbulent liquid sodium flow, revealing that at higher magnetic Reynolds numbers, induced magnetic fields surpass the applied field and exhibit complex fluctuations linked to large-scale flow dynamics.

Contribution

It provides new insights into magnetic induction behavior at higher Rm in turbulent sodium flows, highlighting non-Gaussian fluctuations and slow flow-induced magnetic dynamics.

Findings

Induced magnetic fields exceed applied fields at Rm > 25.

Non-Gaussian fluctuations and bimodal dynamics observed.

Slow flow fluctuations influence magnetic induction.

Abstract

We study the flow response to an externally imposed homogeneous magnetic field in a turbulent swirling flow of liquid sodium -- the VKS2 experiment in which magnetic Reynolds numbers Rm up to 50 are reached. Induction effects are larger than in the former VKS1 experiment. At Rm larger than about 25, the local amplitude of induced field components supersedes that of the applied field, and exhibits non-Gaussian fluctuations. Slow dynamical instationarities and low-frequency bimodal dynamics are observed in the induction, presumably tracing back to large scale fluctuations in the hydrodynamic flow.