Title: "Magnetic Reconnection in Plasmas" (Video)
Abstract: Magnetic reconnection is the process whereby a change in topology of magnetic field lines allows for a rapid conversion of magnetic energy into thermal and kinetic energy of the surrounding plasma. This physical process plays a key role in many astrophysical and laboratory contexts, ranging from magnetospheric substorms, solar eruptions, sawtooth crashes in fusion devices and potentially the super-flares in Crab Nebula. The recently launched Magnetospheric Multiscale (MMS) mission provides an unprecedented view of the three-dimensional fine-scale structure of magnetic reconnection. It offers the amazing opportunity to combine key insights from numerical models with high quality in-situ measurements that promise to greatly increase our understanding of this crucial physical process.
A fundamental and long-standing mystery has been why the reconnection energy conversion rate is remarkably efficient and near-universal across a wide spectrum of plasma regimes. In this talk, I demonstrate for the first time how the reconnection geometry determines the energy release, setting an upper limit for the energy conversion rate that is insensitive to the details of the system. This model is in excellent qualitative and quantitative agreement with the universal fast rate observed in disparate systems. I will also present new insights into the complex three-dimensional nature of magnetic reconnection revealed by means of petascale supercomputing, and will interpret my results in the context of MMS. Finally, I describe the next steps we need to take to answer some key open questions in magnetic reconnection.