Energy Transport by Kelvin-Helmholtz Instability at the Magnetopause

By means of the formation of vortices in the nonlinear phase, the Kelvin Helmholtz instability is able to redistribute the flux of energy of the solar wind that flows parallel to the magnetopause. The energy transport associated with the Kelvin Helmholtz instability contributes significantly to the magnetosphere and magnetosheath dynamics, in particular at the flanks of the magnetopause where the presence of a magnetic field perpendicular to the velocity flow does not inhibit the instability development. By means of a 2D two-fluid simulation code, the behavior of the Kelvin Helmholtz instability is investigated in the presence of typical conditions observed at the magnetopause. In particular, the energy penetration in the magnetosphere is studied as a function of an important parameter such as the solar wind velocity. The influence of the density jump at the magnetopause is also discussed.

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Kelvin-Helmholtz vortices and secondary instabilities in super-magnetosonic regimes

Annales Geophysicae ◽

10.5194/angeo-29-1169-2011 ◽

2011 ◽

Vol 29 (6) ◽

pp. 1169-1178 ◽

Cited By ~ 10

Author(s):

F. Palermo ◽

M. Faganello ◽

F. Califano ◽

F. Pegoraro

Keyword(s):

Plasma Density ◽

Relative Motion ◽

Plasma Flow ◽

Fluid Simulation ◽

Nonlinear Behaviour ◽

Two Dimensional ◽

Helmholtz Instability ◽

Simulation Code ◽

Secondary Instabilities ◽

Two Fluid

Abstract. The nonlinear behaviour of the Kelvin-Helmholtz instability is investigated with a two-fluid simulation code in both sub-magnetosonic and super-magnetosonic regimes in a two-dimensional configuration chosen so as to represent typical conditions observed at the Earth's magnetopause flanks. It is shown that in super-magnetosonic regimes the plasma density inside the vortices produced by the development of the Kelvin-Helmholtz instability is approximately uniform, making the plasma inside the vortices effectively stable against the onset of secondary instabilities. However, the relative motion of the vortices relative to the plasma flow can cause the formation of shock structures. It is shown that in the region where the shocks are attached to the vortex boundaries the plasma conditions change rapidly and develop large gradients that allow for the onset of secondary instabilities not observed in sub-magnetosonic regimes.

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The Kelvin-Helmholtz Instability From the Perspective of Hybrid Simulations

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.801824 ◽

2021 ◽

Vol 8 ◽

Author(s):

P. A. Delamere ◽

N. P. Barnes ◽

X. Ma ◽

J. R. Johnson

Keyword(s):

Solar Wind ◽

Surface Waves ◽

Energy Transport ◽

Helmholtz Instability ◽

Flow Shear ◽

Planetary Magnetospheres ◽

Dayside Magnetopause ◽

Hybrid Simulations

The flow shear-driven Kelvin-Helmholtz (KH) instability is ubiquitous in planetary magnetospheres. At Earth these surface waves are important along the dawn and dusk flanks of the magnetopause boundary while at Jupiter and Saturn the entire dayside magnetopause boundary can exhibit KH activity due to corotational flows in the magnetosphere. Kelvin-Helmholtz waves can be a major ingredient in the so-called viscous-like interaction with the solar wind. In this paper, we review the KH instability from the perspective of hybrid (kinetic ions, fluid electrons) simulations. Many of the simulations are based on parameters typically found at Saturn’s magnetopause boundary, but the results can be generally applied to any KH-unstable situation. The focus of the discussion is on the ion kinetic scale and implications for mass, momentum, and energy transport at the magnetopause boundary.

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Kelvin-Helmholtz instability and induced magnetic reconnection at the Earth’s magnetopause: 3D simulation based on satellite data

Plasma Physics and Controlled Fusion ◽

10.1088/1361-6587/ac43f0 ◽

2021 ◽

Author(s):

Matteo Faganello ◽

Manuela Sisti ◽

Francesco Califano ◽

Benoit Lavraud

Keyword(s):

Magnetic Reconnection ◽

Northern Hemisphere ◽

Fluid Simulation ◽

Asymmetric Distribution ◽

Helmholtz Instability ◽

Plasma Parameters ◽

Nonlinear Phase ◽

Vortex Merging ◽

Dayside Magnetopause ◽

Secondary Instabilities

Abstract A 3D two-ﬂuid simulation, using plasma parameters as measured by MMS on September 8th 2015, shows the nonlinear development of the Kelvin-Helmholtz instability at the Earth’s magnetopause. It shows an extremely rich dynamics, including the development of a complex magnetic topology, vortex merging and secondary instabilities. Vortex induced and mid-latitude magnetic reconnection coexist and produce an asymmetric distribution of magnetic reconnection events. Oﬀ-equator reconnection exhibits a predominance of events in the southern hemisphere during the early nonlinear phase, as observed by satellites at the dayside magnetopause. The late nonlinear phase shows the development of vortex pairing for all latitudes while secondary Kelvin-Helmholtz instability develops only in the northern hemisphere leading to an enhancement of the occurrence of oﬀ-equator reconnection there. Since vortices move tailward while evolving, this suggests that reconnection events in the northern hemisphere should dominate at the nightside magnetopause.

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