Amplification of Magnetic Twists in Solar Prominence Threads
Magnetic twists are commonly associated with solar prominences. Twists are believed to play an important role in supporting the dense plasma against gravity as well as in prominence eruptions and coronal mass ejections, which may have a severe impact on the Earth and its near environment. We have recently used a simple model to mimic the formation of a prominence thread by plasma condensation with the aim of investigating the evolution of small twists during this process. We found that small perturbations are exponentially amplified in time as they propagate along the condensing thread. The amplification is caused by the coupling between the flow and the twists. The linear study carried out by Taroyan and Soler (2019) suggests generation of large amplitude axisymmetric twists along a prominence thread when it is permeated by a converging flow, for example, during the evaporation and condensation of plasma along the thread (see Figure). We have recently found that the process of flow-twist coupling may also lead to the formation of steep gradients and small scales at the critical point. This new phenomenon does not require any influx of azimuthal energy.
We propose a PhD project to focus on the nonlinear evolution of the twists / Alfvenic perturbations using a multidimensional non-linear model with the aim of investigating the back reaction of the amplified twists on the flow, their possible role in the formation of large twists that may support the dense plasma against gravity, their role in the generation of vortices and in the eruption of prominences.