Magnetic reconnection: recent progress from Magnetospheric Multiscale satellite observations

Astronomy Unit Seminars
Jonathan Eastwood
David Burgess
March 2nd, 2018 at 14:30
GO Jones Room 610

Magnetic reconnection is a process of fundamental importance to plasma physics in both space and the laboratory. It is also increasingly cited as a process at work in astrophysical systems. This for two reasons: it controls plasma connectivity, and it can rapidly release and convert stored magnetic energy. Although the consequences of reconnection are large-scale – for example in the context of the Earth’s magnetosphere, collisionless reconnection controls the circulation of plasma and energy transport leading to geomagnetic substorms and storms – the physics that enables reconnection operates on small scales down to the electron scale. Thus, progress in understanding reconnection ultimately requires detailed electron-scale measurements of reconnection, and the magnetic reconnection diffusion region in particular. In 2015 NASA launched the four spacecraft Magnetospheric Multiscale (MMS) mission with the primary goal of studying magnetic reconnection in the Earth’s magnetosphere. Its state-of-the-art payload is capable of measuring the 3D electron plasma distribution on 30 ms timescales, 100 times faster than previous missions and finally able to resolve the electron scale physics that controls reconnection. In this seminar I will discuss why reconnection is important in space and astrophysical phenomena, the MMS mission and its instrumentation, and then review some of the exciting results that have already been discovered using MMS. These include measurements of the electron dissipation region, ion-scale flux ropes, and how the presence of a guide field in 3D reconnection modifies plasma heating.