Abstract
Magnetic reconnection and turbulence are two phenomena that are often invoked to address outstanding open questions as the energy dissipation problem and the heating and acceleration of the solar wind. These two phenomena are closely related to each other in a wide range of plasmas. Turbulent fluctuations can emerge in critical regions of reconnection events, and magnetic reconnection can occur as a product of the turbulent cascade. In this seminar I present some results exploring the interlink between turbulence and reconnection.
This talk is divided in two sections, the first one Exploring the Effect of Driving Turbulent-like Fluctuations on a Harris Current Sheet Configuration and the Formation of Plasmoids and the second one Characterising Sub-Grid-Scale Effects on the Ohms Law Terms in Hybrid Simulations of Turbulence at the Earth’s Magnetosheath. The connecting thread is the non-linear and multi-scale nature of turbulence and reconnection as well as the importance of the small-scale dynamics on the large-scale one.
In the first study, we perform 2D particle-in-cell simulations of a reconnecting Harris current sheet in the presence of turbulent fluctuations to explore the effect of turbulence on the reconnection process in collisionless non-relativistic pair-plasmas. We find that the presence of a turbulent field can affect the onset and evolution of magnetic reconnection. Moreover, we observe the existence of a scale dependent amplitude of magnetic field fluctuations above which these fluctuations can disrupt the growing of magnetic islands. These fluctuations provide thermal energy to the particles within the current sheet and preferential perpendicular thermal energy to the background population. In our second study we address the challenge that poses the modelling of large-scale systems while accounting for the small-scale phenomena by characterising the contribution of the small-scale dynamic terms on the generalized Ohms law in Vlasov-Hybrid simulations of turbulence in Earth’s magnetosheath. This with the aim of providing insight on Sub-Grid-Scale models that can be incorporated in Large Eddy Simulations. Our results are highly relevant to the future modelling of large-scale turbulent plasmas such as magnetospheres, the solar wind, the solar atmosphere, and other astrophysical systems.