scholarly journals Kinetic effects on the Kelvin–Helmholtz instability in ion-to-magnetohydrodynamic scale transverse velocity shear layers: Particle simulations

2010 ◽  
Vol 17 (4) ◽  
pp. 042119 ◽  
Author(s):  
T. K. M. Nakamura ◽  
H. Hasegawa ◽  
I. Shinohara
Keyword(s):  
Transverse Velocity ◽  
Shear Layers ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Particle Simulations ◽  
Kinetic Effects

scholarly journals Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability

2013 ◽  
Vol 31 (9) ◽  
pp. 1535-1541 ◽  
Author(s):  
K.-I. Nishikawa ◽  
P. Hardee ◽  
B. Zhang ◽  
I. Duţan ◽  
M. Medvedev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Magnetic Fields ◽  
Electric Field ◽  
Flow Direction ◽  
Transverse Magnetic ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Magnetic Field Generation ◽  
Relativistic Jet

Abstract. We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic jet and an unmagnetized sheath plasma. We have examined the strong magnetic fields generated by kinetic shear (Kelvin–Helmholtz) instabilities. Compared to the previous studies using counter-streaming performed by Alves et al. (2012), the structure of the kinetic Kelvin–Helmholtz instability (KKHI) of our jet-sheath configuration is slightly different, even for the global evolution of the strong transverse magnetic field. In our simulations the major components of growing modes are the electric field Ez, perpendicular to the flow boundary, and the magnetic field By, transverse to the flow direction. After the By component is excited, an induced electric field Ex, parallel to the flow direction, becomes significant. However, other field components remain small. We find that the structure and growth rate of KKHI with mass ratios mi/me = 1836 and mi/me = 20 are similar. In our simulations saturation in the nonlinear stage is not as clear as in counter-streaming cases. The growth rate for a mildly-relativistic jet case (γj = 1.5) is larger than for a relativistic jet case (γj = 15).

Evolution of Turbulence in the Kelvin–Helmholtz Instability mediated by the Magnetopause and its Boundary Layer

2020 ◽  
Author(s):  
Francesca Di Mare ◽  
Luca Sorriso-Valvo ◽  
Alessandro Retino' ◽  
Francesco Malara ◽  
Hiroshi Hasegawa
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Large Scale ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Intermittent Turbulence ◽  
Large Scale Structures ◽  
Developed Turbulence ◽  
Spacecraft Data ◽  
Efficient Transfer

<p>The turbulence at the interface between the solar wind and the Earth’s magnetosphere, mediated by the magnetopause and its boundary layer are investigated by using Geotail and THEMIS spacecraft data during ongoing Kelvin-Helmholtz instability (KHI). The efficient transfer of energy across scales for which the turbulence is responsible, achieves the connection between the macroscopic flow and the microscopic dissipation of this energy. This boundary layer is thought to be the result of the observed plasma transfer, driven by the development of the KHI, originating from the velocity shear between the solar wind and the almost static near-Earth plasma. A collection of 20 events spatially located on the tail-flank magnetopause, selected from previously studied by Hasegawa et al. 2006 and Lin et al. 2014, have been tested against standard diagnostics for intermittent turbulence. In light of the results obtained, we have investigated the behaviour of several parameters as a function of the progressive departure along the Geocentric Solar Magnetosphere coordinates, which roughly represent the direction in which we expect the KHI vortices to evolve towards fully developed turbulence. It appears that a fluctuating behaviour of the parameters exist, visible as a decreasing, quasi-periodic modulation with an associated periodicity, estimated to correspond to approximately 6.4 Earth Radii. Such observed wavelength is consistent with the estimated vortices roll-up wavelength reported in the literature for these events. If the turbulence is pre-existent, it is possible that the KHI modulates its properties along the magnetosheath, as we observed. On the other hand, if we assume that the KHI has been initiated near the magnetospheric nose and develops along the flanks, then the different intervals we study may be sampling the plasma at different stages of evolution of the KH-generated turbulence, after the instability has injected energy in a cascading process as large-scale structures.</p>

Electron–ion hybrid mode due to transverse velocity shear

1988 ◽  
Vol 31 (10) ◽  
pp. 2753 ◽  
Author(s):  
G. Ganguli ◽  
Y. C. Lee ◽  
P. J. Palmadesso
Keyword(s):  
Transverse Velocity ◽  
Velocity Shear ◽  
Hybrid Mode

scholarly journals Physics of Magnetopause Reconnection: A Study of the Combined Effects of Density Asymmetry, Velocity Shear, and Guide Field

2010 ◽  
Vol 2010 ◽  
pp. 1-17 ◽  
Author(s):  
Kentaro G. Tanaka ◽  
Masaki Fujimoto ◽  
Iku Shinohara
Keyword(s):  
Shear Flow ◽  
Flow Direction ◽  
Electron Flow ◽  
Velocity Shear ◽  
Field Effects ◽  
Guide Field ◽  
Sliding Motion ◽  
Particle Simulations ◽  
Flow Effects ◽  
Magnetopause Reconnection

Magnetopause reconnection would be characterized by the density jump across the current sheet, the flow shear across the boundary, and nonzero guide field. While effects of each of these elements have been studied, the effects arising from the combination of these are still unexplored. Two-dimensional full-particle simulations show that the combination of shear flow and/or guide field with density asymmetry induces the sliding motion of theX-line along the magnetopause. The direction of theX-line motion is controlled either by the ion flow at theX-line when the shear flow effects dominate or by the electron flow at theX-line when the guide field effects dominate. The shear flow effects and the guide field effects may counteract each other in determining the direction of theX-line motion and, in the close proximity of the subsolar region where the flow is slow, theX-line motion can be opposite to the flow direction.

Ion cyclotron modes in a two-ion-component plasma with transverse-velocity shear

1997 ◽  
Vol 102 (A6) ◽  
pp. 11653-11663 ◽  
Author(s):  
Valeriy V. Gavrishchaka ◽  
Mark E. Koepke ◽  
Gurudas I. Ganguli
Keyword(s):  
Transverse Velocity ◽  
Velocity Shear ◽  
Ion Cyclotron ◽  
Component Plasma
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