Collisionless magnetic reconnection in the presence of a sheared velocity field

Faganello, Matteo; Пегораро, Ф.; Califano, Francesco; Marradi, L.

doi:10.1063/1.3430640

Cited by 22 publications

(21 citation statements)

References 32 publications

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“…Finding #2 in Table 2 points out that the spectral breakpoint is associated with the thicknesses of current sheets in the solar wind. As noted in Table 2, physical processes that act on the thicknesses of current sheets are important, such as plasma expansion and compression (Schindler & Hesse, 2008, 2010, Bohm and gyro-Bohm diffusion (Borovsky, 2006;Borovsky & Gary, 2009;Pecseli & Mikkelsen, 1985;Perkins et al, 1993;Vahala & Montgomery, 1971), eddy diffusion (Borovsky, 2006;Chen & Montgomery, 1987;Yoshizawa & Yokoi, 1996), Alfvén wave steepening (Tsurutani & Ho, 1999;Vasquez & Hollweg, 2001), current sheet instabilities (Birn et al, 2004;Daughton, 2003;Roytershteyn & Daughton, 2008), and reconnection (Faganello et al, 2010;Gosling & Phan, 2013;Yin & Winske, 2002).…”

Section: 1029/2019ja027307mentioning

confidence: 99%

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

Borovsky

Burkholder

2020

JGR Space Physics

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The hypothesis is explored that the high‐frequency magnetic spectral power of the solar wind is associated with the spatial profiles of strong current sheets (directional discontinuities) in the solar wind plasma. This hypothesis is based on previous findings about current sheets and the solar wind's magnetic power spectra (1) that the amplitude distribution and waiting time distribution of strong current sheets determines the amplituic composition and the electron strade and spectral slope of the “inertial range” of frequencies and (2) that the thicknesses of strong current sheets in the solar wind determine the breakpoint frequency that ends the inertial range. Solar wind current sheets are collected from the WIND 0.09375‐s and MMS 7.8 × 10−3‐s magnetic data sets, and the current sheets are individually Fourier transformed. At frequencies above the solar wind breakpoint (1) the shape of the magnetic power spectra of the current sheets resembles the shape of the magnetic power spectra of the solar wind and (2) the current sheets occur frequently enough to account for the magnetic power of the solar wind above the breakpoint. This has implications for the physics underlying the high‐frequency magnetic power spectral density of the solar wind, supplementing the energy‐cascade description of the high‐frequency spectrum.

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Section: 1029/2019ja027307mentioning

confidence: 99%

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

Borovsky

Burkholder

2020

JGR Space Physics

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“…This diffusivity has been linked to faster reconnection rates although the existence of the instability is still controversial ). (d) Kelvin-Helmholtz instabilities in thin sheared current sheets may also lead to reconnection (Faganello et al 2010;. (e) An ion firehose instability driven in the ion-diffusion region by counterstreamingion-beams in the ion-diffusion region during anti-parallel reconnection .…”

Section: Measures Of Diffusion Regionsmentioning

confidence: 99%

What Can We Learn about Magnetotail Reconnection from 2D PIC Harris-Sheet Simulations?

2015

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The Magnetosphere Multiscale Mission (MMS) will provide the first opportunity to probe electron-scale physics during magnetic reconnection in Earth's magnetopause and magnetotail. This article will address only tail reconnection-as a non-steady-state process in which the first reconnected field lines advance away from the x-point in flux pile-up fronts directed Earthward and anti-Earthward. An up-to-date microscopic physical picture of electron and ion-scale collisionless tail reconnection processes is presented based on 2-D Particle-In-Cell (PIC) simulations initiated from a Harris current sheet and on Cluster and Themis measurements of tail reconnection. The successes and limitations of simulations when compared to measured reconnection are addressed in detail. The main focus is on particle and field diffusion region signatures in the tail reconnection geometry. The interpretation of these signatures is vital to enable spacecraft to identify physically significant reconnection events, to trigger meaningful data transfer from MMS to Earth and to construct a useful overall physical picture of tail reconnection. New simulation results and theoretical interpretations are presented for energy transport of particles and fields, for the size and shape of electron and ion diffusion regions, for processes occurring near the fronts and for the j × B (Hall) electric field.

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“…In these conditions, previous studies have demonstrated that the nonlinear evolution of KH vortices enables the occurrence of magnetic reconnection driven by large-scale vortex motions, of interest for space plasmas [7][8][9][10] , as well as for astrophysical plasmas jets 11,12 . The vortex formation process indeed drags the magnetic field component parallel to the solar wind direction into the flow.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

et al. 2013

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The nonlinear evolution of collisionless plasmas is typically a multi-scale process where the energy is injected at large, fluid scales and dissipated at small, kinetic scales. Accurately modelling the global evolution requires to take into account the main micro-scale physical processes of interest. This is why comparison of different plasma models is today an imperative task aiming at understanding cross-scale processes in plasmas. We report here the first comparative study of the evolution of a magnetized shear flow, through a variety of different plasma models by using magnetohydrodynamic, Hall-MHD, two-fluid, hybrid kinetic and full kinetic codes. Kinetic relaxation effects are discussed to emphasize the need for kinetic equilibriums to study the dynamics of collisionless plasmas in non trivial configurations. Discrepancies between models are studied both in the linear and in the nonlinear regime of the magnetized Kelvin-Helmholtz instability, to highlight the effects of small scale processes on the nonlinear evolution of collisionless plasmas. We illustrate how the evolution of a magnetized shear flow depends on the relative orientation of the fluid vorticity with respect to the magnetic field direction during the linear evolution when kinetic effects are taken into account. Even if we found that small scale processes differ between the different models, we show that the feedback from small, kinetic scales to large, fluid scales is negligable in the nonlinear regime. This study show that the kinetic modeling validates the use of a fluid approach at large scales, which encourages the development and use of fluid codes to study the nonlinear evolution of magnetized fluid flows, even in the colisionless regime.

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Collisionless magnetic reconnection in the presence of a sheared velocity field

Abstract: Physics of Fluids, 17, p. 062102 (2010)International audienc

Cited by 22 publications

References 32 publications

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

What Can We Learn about Magnetotail Reconnection from 2D PIC Harris-Sheet Simulations?

Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

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