Magnetospheric multiscale observation of kinetic signatures in the Alfvén vortex
Author(s)
Type
Journal Article
Abstract
Alfv ́en vortex is a multi-scale nonlinear structure which contributes to intermittency of turbulence.Despite previous explorations mostly on the spatial properties of the Alfv ́en vortex (i.e., scale,orientation, and motion), the plasma characteristics within the Alfv ́en vortex are unknown. Moreover,the connection between the plasma energization and the Alfv ́en vortex still remains unclear. Based onhigh resolution in-situ measurement from the Magnetospheric Multiscale (MMS) mission, we reportfor the first time, distinctive plasma features within an Alfv ́en vortex. This Alfv ́en vortex is identifiedto be two-dimensional (k⊥≫k∥) quasi-monopole with a radius of 10 proton gyroscales. Its magneticfluctuations B⊥are anti correlated with velocity fluctuations V⊥, thus the parallel current densityj∥and flow vorticity!∥are anti-aligned. In different part of the vortex (i.e., edge, middle, center),the ion and electron temperatures are found to be quite different and they behave in the reversetrend: the ion temperature variations are correlated withj∥, while the electron temperature variationsare correlated with!∥. Furthermore, the temperature anisotropies, together with the non-Maxwelliankinetic effects, exhibit strong enhancement at peaks of|!∥|(|j∥|) within the vortex. Comparison betweenobservations and numerical/theoretical results are made. In addition, the energy-conversion channelsand the compressibility associated with the Alfv ́en vortex are discussed. These results may help tounderstand the link between coherent vortex structures and the kinetic processes, which determineshow turbulence energy dissipate in the weakly-collisional space plasmas.
Date Issued
2019-02-01
Date Acceptance
2019-01-08
Citation
Astrophysical Journal Letters, 2019, 871 (2)
ISSN
2041-8205
Publisher
American Astronomical Society
Journal / Book Title
Astrophysical Journal Letters
Volume
871
Issue
2
Copyright Statement
© 2019. The American Astronomical Society. All rights reserved. This is an author-created, un-copyedited version of an article accepted for publication in Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at https://iopscience.iop.org/article/10.3847/2041-8213
Sponsor
Science and Technology Facilities Council (STFC)
Grant Number
ST/N000692/1
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
plasmas
turbulence
SOLAR-WIND
TURBULENCE
PLASMA
WAVES
VORTICITY
0201 Astronomical And Space Sciences
Publication Status
Published
Date Publish Online
2019-01-25