Dipole-Quadrupole dynamics during magnetic field reversals

TL;DR

This paper investigates the dynamics of magnetic field reversals in a turbulent dynamo experiment, focusing on the interplay between dipolar and quadrupolar magnetic components and their evolution during reversals.

Contribution

It provides experimental evidence supporting a recent model of magnetic reversals, highlighting the energy transfer between dipole and quadrupole components during the process.

Findings

Reversals involve energy transfer from dipole to quadrupole.

Reversals start with a slow dipole decay and are followed by a rapid recovery.

Random reversals occur near the transition between stationary and oscillatory dynamos.

Abstract

The shape and the dynamics of reversals of the magnetic field in a turbulent dynamo experiment are investigated. We report the evolution of the dipolar and the quadrupolar parts of the magnetic field in the VKS experiment, and show that the experimental results are in good agreement with the predictions of a recent model of reversals: when the dipole reverses, part of the magnetic energy is transferred to the quadrupole, reversals begin with a slow decay of the dipole and are followed by a fast recovery, together with an overshoot of the dipole. Random reversals are observed at the borderline between stationary and oscillatory dynamos.