# Nonlinear Evolution of Axisymmetric Twisted Flux Tubes in the Solar Tachocline

## TL;DR

This study numerically investigates the nonlinear evolution of axisymmetric twisted flux tubes in the solar tachocline, revealing how twist influences stability and the destruction of magnetic fields.

## Contribution

It demonstrates the effects of twist on flux tube stability and shows that twisted tubes can suppress shredding instabilities or evolve differently due to their non-equilibrium nature.

## Key findings

- Untwisted flux tubes undergo radial-shredding instabilities.
- Twisted flux tubes can suppress these instabilities.
- Twisted tubes are generally not equilibrium solutions, leading to different evolution.

## Abstract

We numerically study the evolution of magnetic fields and fluid flows in a thin spherical shell. We take the initial field to be a latitudinally confined, predominantly toroidal flux tube. For purely toroidal, untwisted flux tubes, we recover previously known radial-shredding instabilities, and show further that in the nonlinear regime these instabilities can very effectively destroy the original field. For twisted flux tubes, including also a poloidal component, there are several possibilities, including the suppression of the radial-shredding instability, but also a more directly induced evolution, brought about because twisted flux tubes in general are not equilibrium solutions of the governing equations.