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The interaction of finite‐width reconnection exhaust jets with a dipolar magnetic field configuration
Author(s) -
Pritchett P. L.,
Runov A.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023784
Subject(s) - physics , dipole , electron , current sheet , magnetic field , plasma , jet (fluid) , magnetic reconnection , anisotropy , condensed matter physics , atomic physics , computational physics , magnetohydrodynamics , mechanics , quantum mechanics
The structure and properties of earthward propagating exhaust jets produced by a magnetic reconnection source region localized in the out‐of‐plane direction are investigated with 3‐D particle‐in‐cell simulations that incorporate a realistic plasma sheet configuration in which a dipole magnetic field region is connected to an asymptotic tail equilibrium with finite B z . The jet is found to separate initially into two segments of width ∼10–15 d i each ( d i is the ion inertia length). The dawnward segment moves ahead of the duskward one and continues to intensify, while the latter is buffeted by the return flows generated by the former and stagnates. The leading front develops the characteristic structure of a sharp B z increase and density drop on a 1–2 d i scale. The current associated with this B z increase is carried mainly by the electrons, and the jet front is the site of a Region 1 sense field‐aligned current system. The ions develop a moderate temperature anisotropy with T i || > T i ⊥ ahead of the front, while the electron temperature remains isotropic. The ion heating behind the front is quasi‐adiabatic, while the nonthermal electron tail is enhanced out to the limit of the simulation spectrum (∼15 E th ). The ion velocity distribution function behind the front exhibits a strong parallel phase space enhancement at speeds ∼0.5 V A associated with the earthward flow, while closer to the dipole region there is a drop out in parallel phase space at speeds of ∼1.5–2.5 V A . The electron distribution is isotropic with an enhanced central plateau extending out to ∼4 V A .