TY - JOUR
T1 - Coherent Structures at Ion Scales in Fast Solar Wind
T2 - Cluster Observations
AU - Perrone, D.
AU - Alexandrova, O.
AU - Roberts, O. W.
AU - Lion, S.
AU - Lacombe, C.
AU - Walsh, A.
AU - Maksimovic, M.
AU - Zouganelis, I.
N1 - Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - We investigate the nature of magnetic turbulent fluctuations, around ion characteristic scales, in a fast solar wind stream, by using Cluster data. Contrarily to slow solar wind, where both Alfvénic and compressive coherent structures are observed, the turbulent cascade of fast solar wind is dominated by Alfvénic structures, namely, Alfvén vortices, with a small and/or finite compressive part, with the presence also of several current sheets aligned with the local magnetic field. Several examples of vortex chains are also recognized. Although an increase of magnetic compressibility around ion scales is observed also for fast solar wind, no strongly compressive structures are found, meaning that the nature of the slow and fast winds is intrinsically different. Multispacecraft analysis applied to this interval of fast wind indicates that the coherent structures are almost convected by the flow and aligned with the local magnetic field, i.e., their normal is perpendicular to, which is consistent with a two-dimensional turbulence picture. Understanding intermittency and the related generation of coherent structures could provide a key insight into the nonlinear energy transfer and dissipation processes in magnetized and collisionless plasmas.
AB - We investigate the nature of magnetic turbulent fluctuations, around ion characteristic scales, in a fast solar wind stream, by using Cluster data. Contrarily to slow solar wind, where both Alfvénic and compressive coherent structures are observed, the turbulent cascade of fast solar wind is dominated by Alfvénic structures, namely, Alfvén vortices, with a small and/or finite compressive part, with the presence also of several current sheets aligned with the local magnetic field. Several examples of vortex chains are also recognized. Although an increase of magnetic compressibility around ion scales is observed also for fast solar wind, no strongly compressive structures are found, meaning that the nature of the slow and fast winds is intrinsically different. Multispacecraft analysis applied to this interval of fast wind indicates that the coherent structures are almost convected by the flow and aligned with the local magnetic field, i.e., their normal is perpendicular to, which is consistent with a two-dimensional turbulence picture. Understanding intermittency and the related generation of coherent structures could provide a key insight into the nonlinear energy transfer and dissipation processes in magnetized and collisionless plasmas.
KW - plasmas
KW - solar wind
KW - turbulence
UR - http://www.scopus.com/inward/record.url?scp=85037699073&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aa9022
DO - 10.3847/1538-4357/aa9022
M3 - Article
AN - SCOPUS:85037699073
SN - 0004-637X
VL - 849
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 49
ER -