The Three-Dimensional Behavior of a Twisted Flux Tube Expanding in the Corona: Reconnection, Writhe, and Jets

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 3-D reconnection driven by a collision of two parts of an emerging flux tube within the single emerged loop. We perform 3-D 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 the nearest part and the release of the trapped twist in the form of a helical jetlike emission.