A Short-Timescale Channel of Dissipation of the Strong Solar Wind Turbulence

Markovskii, S. A.; Vasquez, Bernard J.

doi:10.1088/0004-637x/739/1/22

Cited by 56 publications

(43 citation statements)

References 36 publications

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“…4, namely at scales 0.2 < kd i < 2. This near-equipartition of energy however is broken at the ion skin depth (Alexandrova et al 2008), typical of both kinetic and dispersive fluctuations (Bale et al 2005;Valentini et al 2008;Alexandrova et al 2009;Sahraoui et al 2009;Markovskii and Vasquez 2011b;Servidio et al 2012). Similarly to solar wind observations (Bale et al 2005), we remark that the electric field activity at larger wavenumbers is higher than the magnetic activity, possibly due to the Hall effect .…”

Section: Statistical Properties Of Kinetic Turbulencesupporting

confidence: 74%

A kinetic model of plasma turbulence

et al. 2014

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A Hybrid Vlasov–Maxwell (HVM) model is presented and recent results about the link between kinetic effects and turbulence are reviewed. Using five-dimensional (2D in space and 3D in the velocity space) simulations of plasma turbulence, it is found that kinetic effects (or non-fluid effects) manifest through the deformation of the proton velocity distribution function (DF), with patterns of non-Maxwellian features being concentrated near regions of strong magnetic gradients. The direction of the proper temperature anisotropy, calculated in the main reference frame of the distribution itself, has a finite probability of being along or across the ambient magnetic field, in general agreement with the classical definition of anisotropy T⊥/T∥ (where subscripts refer to the magnetic field direction). Adopting the latter conventional definition, by varying the global plasma beta (β) and fluctuation level, simulations explore distinct regions of the space given by T⊥/T∥ and β∥, recovering solar wind observations. Moreover, as in the solar wind, HVM simulations suggest that proton anisotropy is not only associated with magnetic intermittent events, but also with gradient-type structures in the flow and in the density. The role of alpha particles is reviewed using multi-ion kinetic simulations, revealing a similarity between proton and helium non-Maxwellian effects. The techniques presented here are applied to 1D spacecraft-like analysis, establishing a link between non-fluid phenomena and solar wind magnetic discontinuities. Finally, the dimensionality of turbulence is investigated, for the first time, via 6D HVM simulations (3D in both spaces). These preliminary results provide support for several previously reported studies based on 2.5D simulations, confirming several basic conclusions. This connection between kinetic features and turbulence open a new path on the study of processes such as heating, particle acceleration, and temperature-anisotropy, commonly observed in space plasmas

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Section: Statistical Properties Of Kinetic Turbulencesupporting

confidence: 74%

A kinetic model of plasma turbulence

et al. 2014

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“…A clear correlation between velocity and magnetic field is observed at scales larger than the ion skin depth (i.e., at wave numbers smaller than kd i ' 1), typical feature of the MHD cascade. At about kd i $ 1, the nature of the cascade changes due to dispersive and kinetic effects, 13,16,[19][20][21] and finally, at scales kd i ' 7, the spectrum steepens down because of the presence of numerical resistivity. We would like to point out that such resistivity is required in fluid and hybrid simulations (fluid electrons) in order to guarantee the accuracy of the numerical results.…”

Section: Numerical Simulations Of the Hybrid Vlasov-maxwell Modelmentioning

confidence: 99%

Analysis of cancellation exponents in two-dimensional Vlasov turbulence

et al. 2014

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Statistical properties of plasma turbulence are investigated by means of two-dimensional Vlasov simulations. In particular, a classical technique called signed measure is used to characterize the scaling behavior and the topology of sign-oscillating structures in simulations of the hybrid Vlasov-Maxwell model. Exploring different turbulence regimes, varying both the plasma β and the level of fluctuations, it is observed that Vlasov turbulence manifests two ranges with different exponents, the transition being observed near the ion skin depth. These results, which may have applications to both laboratory and astrophysical systems, further confirm the singular nature of small scale fluctuations in a plasma, mainly classified as intermittent, narrow, and intense current sheets.

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“…We concentrated on heating processes due to KAWs, whose efficiency is related to the proximity of the wavelengths to the ion Larmor radius. Other heating processes, in addition to Landau and cyclotron resonances (Marsch and Bourouaine, 2011), are based on the effect of rapidly evolving small-scale structures such as currents sheets (Markovskii and Vasquez, 2011;Servidio et al, 2012). Forthcoming developments will concern the extension of the present simulations to the fully three-dimensional FLRLandau fluid model, which permits the development of turbulent cascades and thus provides a suitable tool to address the heating problem in a fully turbulent regime.…”

Section: Discussionmentioning

confidence: 98%

Fluid simulations of non-resonant anisotropic ion heating

2013

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The finite Larmor radius (FLR)-Landau fluid model, which extends the usual anisotropic magnetohydrodynamics to magnetized collisionless plasmas by retaining linear Landau damping and finite Larmor radius corrections down to the sub-ionic scales in the quasi-transverse directions, is used to study the non-resonant heating of the plasma by randomly driven Alfvén waves. One-dimensional numerical simulations, free from any artificial dissipation, are used to analyze the influence on the thermal dynamics, of the beta parameter and of the separation between the driving and the ion scales. While the gyrotropic heat fluxes play a dominant role when the plasma is driven at large scales, leading to a parallel heating of the ions by Landau damping, a different regime develops when the driving acts at scales comparable to the ion Larmor radius. Perpendicular heating and parallel cooling of the ions are then observed, an effect that is mostly due to the work of the non-gyrotropic pressure force and that can be viewed as the fluid signature of the so-called stochastic heating. A partial characterization of the plasma by global quantities (such as the magnetic compressibility and the density-magnetic field correlations that provide information on the dominant type of waves) is also presented. The enhancement of the parallel electron heating by a higher level of fast magnetosonic waves is in particular pointed out

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A Short-Timescale Channel of Dissipation of the Strong Solar Wind Turbulence

Cited by 56 publications

References 36 publications

A kinetic model of plasma turbulence

A kinetic model of plasma turbulence

Analysis of cancellation exponents in two-dimensional Vlasov turbulence

Fluid simulations of non-resonant anisotropic ion heating

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