Title: Asymmetric Reconnection: A breakthrough to more realistic reconnection events in space
Authors: Cazzola, Emanuele
Lapenta, Giovanni
Issue Date: 28-May-2014
Conference: Belgian Physical Society (BPS) Annual Meeting location:Leuven date:2014
Abstract: Magnetic reconnection is a process already known as early as the forties, when Giovannelli first suggested the possibility for the magnetic field to change topology and release energy.
This is of primary importance in driving many physical events in space, such as solar flares and geomagnetic substorms, and required further studies. Specifically, the GEM challenge turned out to be fundamental in explaining reconnective events in the magnetotail. This region is usually well described with the Harris conditions concerning the balance between magnetic and plasma pressures into a symmetric current sheet.

However, reality is often strongly asymmetric in either magnetic field or density or both. Only recently this asymmetric configuration has been studied using several different approaches, including MHD and kinetic simulations.

Particularly, asymmetric reconnection results in having new interesting hallmarks. For instance, due to the difference of the magnetic energy across the current sheet, a co-location between the X-line and the stagnation point no longer exists. This offset leads to a plasma flow through the null point. Moreover, the X-line may experience a further lateral diamagnetic drift governed by the electron diamagnetic velocity when a proper out-of-plane magnetic component is present (i.e. guide field).

Finally, this work aims at going deeper into the abundance of physics behind the process of asymmetric reconnection in collisionless plasmas using a powerful tool as the fully kinetic implicit code iPIC3D. This tool allows us to perform simulations with larger spatial and temporal scales thanks to the reduced computational costs of the implicit algorithm.

As first application of asymmetric conditions, we are going to analyze the dayside magnetosphere, where the shocked solar wind (magnetosheath) encounters the magnetosphere plasma and strong gradients in both magnetic field and density are measured. Great interest in this region has been lately remarked, mostly in light of the upcoming 4-satellites cluster NASA mission, named MMS (Magnetosphere Multiscale Mission), devoted to observe reconnection behaviors into these large spatial scale of the magnetosphere.
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Plasma-astrophysics Section

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