A model of driven and decaying magnetic turbulence in a cylinder

TL;DR

This paper models the evolution of magnetic fields in a cylindrical system using mean-field theory, highlighting how magnetic helicity fluxes influence field reversal and potentially mitigate quenching effects in plasma confinement.

Contribution

It introduces a mean-field theoretical framework for magnetic turbulence in a cylinder with boundary conditions, emphasizing the role of magnetic helicity fluxes in field reversal.

Findings

Weak axial magnetic field reversal due to helicity fluxes

Magnetic helicity fluxes can reduce catastrophic quenching of the alpha-effect

Application insights for reversed field pinch devices

Abstract

Using mean-field theory, we compute the evolution of the magnetic field in a cylinder with outer perfectly conducting boundaries, an imposed axial magnetic and electric field. The thus injected magnetic helicity in the system can be redistributed by magnetic helicity fluxes down the gradient of the local current helicity of the small-scale magnetic field. A weak reversal of the axial magnetic field is found to be a consequence of the magnetic helicity flux in the system. Such fluxes are known to alleviate so-called catastrophic quenching of the {\alpha}-effect in astrophysical applications. Application to the reversed field pinch in plasma confinement devices is discussed.