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The Solar Wind as a Turbulence Laboratory
Bruno, Roberto; Carbone, Vincenzo
In this review we will focus on a topic of fundamental importance for both astrophysics and plasma physics, namely the occurrence of large-amplitude low-frequency fluctuations of the fields that describe the plasma state. This subject will be treated within the context of the expanding solar wind and the most meaningful advances in this research f…
Solar Wind Turbulence and the Role of Ion Instabilities
Bale, S. D.; Alexandrova, O.; Horbury, T. S. +2 more
Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: (i) weakness of collisional dissipation and (ii) presence of several characteristic space and time scales. In this paper we discuss observational proper…
Energetic electron acceleration by unsteady magnetic reconnection
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +2 more
Magnetic reconnection in the Earth's magnetosphere accelerates electrons. And yet energetic electrons are not created during reconnection in the solar wind. Observations from the Cluster spacecraft now suggest that electron acceleration is caused by repeated bursts of plasma flow, which only occur in situations where the magnetic reconnection is u…
Statistics of whistler mode waves in the outer radiation belt: Cluster STAFF-SA measurements
Breuillard, Hugo; Khotyaintsev, Yuri V.; Balikhin, Michael +5 more
ELF/VLF waves play a crucial role in the dynamics of the radiation belts and are partly responsible for the main losses and the acceleration of energetic electrons. Modeling wave-particle interactions requires detailed information of wave amplitudes and wave normal distribution over L-shells and over magnetic latitudes for different geomagnetic ac…
Dipolarization fronts as a consequence of transient reconnection: In situ evidence
André, M.; Hamrin, M.; Sitnov, M. I. +10 more
Dipolarization fronts (DFs) are frequently detected in the Earth's magnetotail from XGSM = -30 RE to XGSM = -7 RE. How these DFs are formed is still poorly understood. Three possible mechanisms have been suggested in previous simulations: (1) jet braking, (2) transient reconnection, and (3) spontaneous f…
In-Situ Observations of Reconnection in Space
Phan, Tai; Paschmann, Götz; Øieroset, Marit
This paper gives an overview of the insights into the magnetic reconnection process obtained by in-situ measurements across current sheets found in planetary magnetospheres and the solar wind. Emphasis is placed on results that might be of interest to the study of reconnection in regions where no in-situ observations are available. These results i…
Scaling of the Electron Dissipation Range of Solar Wind Turbulence
Belmont, G.; Sahraoui, F.; Huang, S. Y. +4 more
Electron scale solar wind (SW) turbulence has attracted great interest in recent years. Considerable evidence exists that the turbulence is not fully dissipated near the proton scale, but continues cascading down to electron scales. However, the scaling of the magnetic energy spectra as well as the nature of the plasma modes involved at those smal…
Particle acceleration in dipolarization events
Nakamura, R.; Hesse, M.; Birn, J. +1 more
Using the electromagnetic fields of a recent MHD simulation of magnetotail reconnection, flow bursts and dipolarization, we investigate the acceleration of test particles (protons and electrons) to suprathermal energies, confirming and extending earlier results on acceleration mechanisms and sources. (Part of the new results have been reviewed rec…
A review of pressure anisotropy caused by electron trapping in collisionless plasma, and its implications for magnetic reconnection
Daughton, William; Egedal, Jan; Le, Ari
From spacecraft data, it is evident that electron pressure anisotropy develops in collisionless plasmas. This is in contrast to the results of theoretical investigations, which suggest this anisotropy should be limited. Common for such theoretical studies is that the effects of electron trapping are not included; simply speaking, electron trapping…
Enhanced Magnetic Compressibility and Isotropic Scale Invariance at Sub-ion Larmor Scales in Solar Wind Turbulence
Sahraoui, F.; Khotyaintsev, Yu. V.; Chapman, S. C. +3 more
The anisotropic nature of solar wind magnetic turbulence fluctuations is investigated scale by scale using high cadence in situ magnetic field measurements from the Cluster and ACE spacecraft missions. The data span five decades in scales from the inertial range to the electron Larmor radius. In contrast to the inertial range, there is a successiv…