Electric and magnetic spectra from MHD to electron scales in the magnetosheath

Matteini, Lorenzo; Alexandrova, Olga; Chen, C. H. K.; Lacombe, Catherine

doi:10.1093/mnras/stw3163

Cited by 64 publications

(66 citation statements)

References 61 publications

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“…As seen in Figure 7(a), the magnetic field spectra are almost indistinguishable in the two simulations, meaning that the coupling is more effective in 3D than in 2D. At wavenumbers in the kinetic range (  kd 2 i ) the two simulations have a negligible difference and^R E B increases with the same (linear) scaling, as a direct consequence of Ohm's law, and consistently with observed frequency spectra in the solar wind frame (Bale et al 2005;Matteini et al 2017).…”

Section: Comparison With the 2d Casesupporting

confidence: 73%

Solar Wind Turbulent Cascade from MHD to Sub-ion Scales: Large-size 3D Hybrid Particle-in-cell Simulations

Franci

Landi

Verdini

et al. 2018

ApJ

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Properties of the turbulent cascade from fluid to kinetic scales in collisionless plasmas are investigated by means of large-size 3D hybrid (fluid electrons, kinetic protons) particle-in-cell simulations. Initially isotropic Alfvénic fluctuations rapidly develop a strongly anisotropic turbulent cascade, mainly in the direction perpendicular to the ambient magnetic field. The omnidirectional magnetic field spectrum shows a double power-law behavior over almost two decades in wavenumber, with a Kolmogorov-like index at large scales, a spectral break around ion scales, and a steepening at sub-ion scales. Power laws are also observed in the spectra of the ion bulk velocity, density, and electric field, at both magnetohydrodynamic (MHD) and kinetic scales. Despite the complex structure, the omnidirectional spectra of all fields at ion and sub-ion scales are in remarkable quantitative agreement with those of a 2D simulation with similar physical parameters. This provides a partial, a posteriori validation of the 2D approximation at kinetic scales. Conversely, at MHD scales, the spectra of the density and of the velocity (and, consequently, of the electric field) exhibit differences between the 2D and 3D cases. Although they can be partly ascribed to the lower spatial resolution, the main reason is likely the larger importance of compressible effects in the full 3D geometry. Our findings are also in remarkable quantitative agreement with solar wind observations.

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Section: Comparison With the 2d Casesupporting

confidence: 73%

Solar Wind Turbulent Cascade from MHD to Sub-ion Scales: Large-size 3D Hybrid Particle-in-cell Simulations

Franci

Landi

Verdini

et al. 2018

ApJ

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“…In the LH frequency range, the Hall dynamics yields (Matteini et al, )

δ E_{⊥}^{2} \propto k^{2} δ B^{2},

where δ B ∼ δ B ∥ ∼ δ B ⊥ according to the observations. The presence of significant δ B ⊥ can be attributed to finite k ∥ due to oblique wave propagation.…”

Section: Discussionmentioning

confidence: 87%

Rippled Electron‐Scale Structure of a Dipolarization Front

Pan

Khotyaintsev

Graham

et al. 2018

Geophysical Research Letters

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We use the Magnetospheric Multiscale mission to investigate electron‐scale structures at a dipolarization front. The four spacecraft are separated by electron scales and observe large differences in plasma and field parameters within the dipolarization front, indicating strong deviation from typically assumed plane or slightly curved front surface. We attribute this to ripples generated by the lower hybrid drift instability (LHDI) with wave number of kρe≃0.4 and maximum wave potential of ∼1 kV ∼kBTe. Power law‐like spectra of E⊥ with slope of −3 indicates the turbulent cascade of LHDI. LHDI is observed together with bursty high‐frequency parallel electric fields, suggesting coupling of LHDI to higher‐frequency electrostatic waves.

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“…In particular, a powerlaw spectrum with a slope between −2.8 and −3 is routinely observed (see, e.g., Alexandrova et al 2009;Chen & Boldyrev 2017). Concurrently, the electric to magnetic field power increases , together with compressive fluctuations (see, e.g., Chen et al 2012Chen et al , 2013aMatteini et al 2017), and the nature of the fluctuations seems to be compatible with strongly obliquely Alfvénic modes, the so-called kinetic Alfvén waves (see, e.g., Salem et al 2012;Chen et al 2013a).…”

Section: Introductionmentioning

confidence: 96%

Can Hall Magnetohydrodynamics Explain Plasma Turbulence at Sub-ion Scales?

Papini

Franci

Landi

et al. 2019

ApJ

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We investigate the properties of plasma turbulence by means of two-dimensional Hallmagnetohydrodynamic (HMHD) and hybrid particle-in-cell (HPIC) numerical simulations. We find that HMHD simulations exhibit spectral properties that are in most cases in agreement with the results of the HPIC simulations and with solar wind observations. The energy spectra of magnetic fluctuations exhibit a double power-law with spectral index −5/3 at MHD scales and −3 at kinetic scales, while for velocity fluctuations the spectral index is −3/2 at MHD scales. The break between the MHD and the kinetic scales occurs at the same scale in both simulations. In the MHD range the slopes of the total energy and residual energy spectra satisfy a fast Alfvén-dynamo balance. The development of a turbulent cascade is concurrently characterized by magnetic reconnection events taking place in thin current sheets that form between large eddies. A statistical analysis reveals that reconnection is qualitatively the same and fast in both the HMHD and HPIC models, characterized by inverse reconnection rates much smaller than the characteristic large-eddy nonlinear time. The agreement extends to other statistical properties, such us the kurtosis of the magnetic field. Moreover, the observation of a direct energy transfer from the large vortices to the small sub-ion scales triggered by magnetic reconnection, further supports the existence of a reconnection-mediated turbulent regime at kinetic scales. We conclude that the Hall-MHD fluid description captures to a large extent the transition of the turbulent cascade between the large MHD scales and the sub-ion scales.

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Electric and magnetic spectra from MHD to electron scales in the magnetosheath

Cited by 64 publications

References 61 publications

Solar Wind Turbulent Cascade from MHD to Sub-ion Scales: Large-size 3D Hybrid Particle-in-cell Simulations

Solar Wind Turbulent Cascade from MHD to Sub-ion Scales: Large-size 3D Hybrid Particle-in-cell Simulations

Rippled Electron‐Scale Structure of a Dipolarization Front

Can Hall Magnetohydrodynamics Explain Plasma Turbulence at Sub-ion Scales?

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