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On the electron dynamics during island coalescence in asymmetric magnetic reconnection
KTH, School of Computer Science and Communication (CSC), High Performance Computing and Visualization (HPCViz). KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC.ORCID iD: 0000-0003-0639-0639
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2015 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 22, no 9, 092901Article in journal (Refereed) Published
Abstract [en]

We present an analysis of the electron dynamics during rapid island merging in asymmetric magnetic reconnection. We consider a doubly periodic system with two asymmetric transitions. The upper layer is an asymmetric Harris sheet of finite width perturbed initially to promote a single reconnection site. The lower layer is a tangential discontinuity that promotes the formation of many X-points, separated by rapidly merging islands. Across both layers, the magnetic field and the density have a strong jump, but the pressure is held constant. Our analysis focuses on the consequences of electron energization during island coalescence. We focus first on the parallel and perpendicular components of the electron temperature to establish the presence of possible anisotropies and non-gyrotropies. Thanks to the direct comparison between the two different layers simulated, we can distinguish three main types of behavior characteristic of three different regions of interest. The first type represents the regions where traditional asymmetric reconnections take place without involving island merging. The second type of regions instead shows reconnection events between two merging islands. Finally, the third regions identify the regions between two diverging island and where typical signature of reconnection is not observed. Electrons in these latter regions additionally show a flat-top distribution resulting from the saturation of a two-stream instability generated by the two interacting electron beams from the two nearest reconnection points. Finally, the analysis of agyrotropy shows the presence of a distinct double structure laying all over the lower side facing the higher magnetic field region. This structure becomes quadrupolar in the proximity of the regions of the third type. The distinguishing features found for the three types of regions investigated provide clear indicators to the recently launched Magnetospheric Multiscale NASA mission for investigating magnetopause reconnection involving multiple islands.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015. Vol. 22, no 9, 092901
Keyword [en]
Dynamics, Electrons, Magnetic fields, Magnetism, Magnetosphere, Merging, NASA, Behavior characteristic, Electron energization, Interacting electrons, Magnetic reconnections, Magnetospheric multi scale, Regions of interest, Tangential discontinuities, Two stream instability, Electron temperature
National Category
Fusion, Plasma and Space Physics
URN: urn:nbn:se:kth:diva-177771DOI: 10.1063/1.4929847ScopusID: 2-s2.0-84940872959OAI: diva2:874735

QC 20151127

Available from: 2015-11-27 Created: 2015-11-25 Last updated: 2015-11-27Bibliographically approved

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Markidis, Stefano
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High Performance Computing and Visualization (HPCViz)Centre for High Performance Computing, PDC
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