Wednesday

Magnetic reconnection is a fundamental plasma physics process which governs energy and mass transfer from the solar wind into the Earth’s magnetosphere. During reconnection we observe flux ropes: twisted magnetic field structures important for energy transfer processes. Whilst previous missions have observed and characterised flux ropes, the temporal resolution of the data was typically not great enough to study structures in detail, particularly on electron scales. Here we investigate magnetopause flux ropes using data from NASA’s four spacecraft Magnetospheric Multiscale mission (MMS). MMS measures the thermal electron and ion 3D distribution at 30 msec and 150 msec time resolution respectively at spacecraft separations down to a few kilometers. We focus on electron pitch angle distributions and demonstrate how they can be used to deduce the connectivity and topology of the magnetic field inside flux ropes. Transfer of flux into the magnetotail ultimately requires one end of the twisted field line to be connected to the magnetosphere and the other to the solar wind. Initial results surveying the MMS data suggest that this may not be true of all flux ropes, or throughout the complete duration of a single flux rope, and that the topology is much more variable and dynamic than was previously anticipated. We discuss some possible implications for the role of flux ropes in flux transfer events and flux transport in the magnetosphere.