Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 35, 1051-1067, 2017
https://doi.org/10.5194/angeo-35-1051-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
05 Sep 2017
Catalog of fine-structured electron velocity distribution functions – Part 1: Antiparallel magnetic-field reconnection (Geospace Environmental Modeling case)
Philippe-A. Bourdin Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
Abstract. To understand the essential physics needed to reproduce magnetic reconnection events in 2.5-D particle-in-cell (PIC) simulations, we revisit the Geospace Environmental Modeling (GEM) setup. We set up a 2-D Harris current sheet (that also specifies the initial conditions) to evolve the reconnection of antiparallel magnetic fields. In contrast to the GEM setup, we use a much smaller initial perturbation to trigger the reconnection and evolve it more self-consistently. From PIC simulation data with high-quality particle statistics, we study a symmetric reconnection site, including separatrix layers, as well as the inflow and the outflow regions. The velocity distribution functions (VDFs) of electrons have a fine structure and vary strongly depending on their location within the reconnection setup. The goal is to start cataloging multidimensional fine-structured electron velocity distributions showing different reconnection processes in the Earth's magnetotail under various conditions. This will enable a direct comparison with observations from, e.g., the NASA Magnetospheric MultiScale (MMS) mission, to identify reconnection-related events. We find regions with strong non-gyrotropy also near the separatrix layer and provide a refined criterion to identify an electron diffusion region in the magnetotail. The good statistical significance of this work for relatively small analysis areas reveals the gradual changes within the fine structure of electron VDFs depending on their sampling site.

Citation: Bourdin, P.-A.: Catalog of fine-structured electron velocity distribution functions – Part 1: Antiparallel magnetic-field reconnection (Geospace Environmental Modeling case), Ann. Geophys., 35, 1051-1067, https://doi.org/10.5194/angeo-35-1051-2017, 2017.
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Short summary
From computer simulations we study how free electrons behave in a region where opposite magnetic fields interact. The particles get disturbed and change their velocity and energy, similar to what happens in the tail of the magnetic field on the nightside of the Earth or during magnetic outburst events on the Sun. We provide a catalog of those particle velocities that are specific to their location within the magnetic field. Scientists may use the data for comparison with satellite observations.
From computer simulations we study how free electrons behave in a region where opposite magnetic...
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