The 3D behavior of a twisted flux tube expanding in the corona: reconnection, writhe and jets

TL;DR

This paper investigates the 3D behavior of twisted magnetic flux tubes in the solar corona, revealing how magnetic reconnection driven by flux emergence leads to helical jets and the conservation of magnetic helicity.

Contribution

It presents 3D MHD simulations showing how highly twisted flux emergence causes reconnection and jet formation, elucidating the role of magnetic helicity in solar plasma dynamics.

Findings

Twisted flux emergence creates null points and reconnection sites.

Reconnection releases trapped twist as helical jets.

Magnetic helicity conservation explains jet helicity structure.

Abstract

We discuss some aspects of magnetic reconnection which could help in understanding many aspects of magnetic plasma interactions. We will show that the helical structure often observed in polar jets is a natural consequence of magnetic helicity conservation in 3D reconnection driven by a collision of two parts of an emerging flux tube within the single emerged loop. We perform 3D simulations by solving the time-dependent, ideal MHD equations with a uniform initial twist. We deduce that the emergence of highly twisted magnetic flux introduces several null points, which in turn causes reconnection between opposite directions of magnetic field within a single loop at nearest part and the release of the trapped twist in the form of a helical jet-like emission.