The Kelvin-Helmholtz Instability in Compressible Plasmas with Magnetic Field Shear

2001 ◽  
Author(s):  
Alejandro G. González ◽  
Marisa González ◽  
Julio Gratton ◽  
Hernán Chuaqui ◽  
Mario Favre
Keyword(s):  
Magnetic Field ◽  
Helmholtz Instability

Effects of fluctuating magnetic field on the growth of the Kelvin-Helmholtz instability at the Earth's magnetopause

2019 ◽  
Author(s):  
Takuma Nakamura ◽  
Julia E. Stawarz ◽  
Hiroshi Hasegawa ◽  
Yasuhito Narita ◽  
Luca Franci ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Helmholtz Instability

scholarly journals Diffusion at the Earth magnetopause: enhancement by Kelvin-Helmholtz instability

2007 ◽  
Vol 25 (1) ◽  
pp. 271-282 ◽  
Author(s):  
R. Smets ◽  
G. Belmont ◽  
D. Delcourt ◽  
L. Rezeau
Keyword(s):  
Magnetic Field ◽  
Distribution Functions ◽  
Larmor Radius ◽  
Simple Analytical Model ◽  
Helmholtz Instability ◽  
Field Reversal ◽  
Finite Larmor Radius ◽  
The Earth ◽  
Specific Distribution ◽  
The Magnetic Field

Abstract. Using hybrid simulations, we examine how particles can diffuse across the Earth's magnetopause because of finite Larmor radius effects. We focus on tangential discontinuities and consider a reversal of the magnetic field that closely models the magnetopause under southward interplanetary magnetic field. When the Larmor radius is on the order of the field reversal thickness, we show that particles can cross the discontinuity. We also show that with a realistic initial shear flow, a Kelvin-Helmholtz instability develops that increases the efficiency of the crossing process. We investigate the distribution functions of the transmitted ions and demonstrate that they are structured according to a D-shape. It accordingly appears that magnetic reconnection at the magnetopause is not the only process that leads to such specific distribution functions. A simple analytical model that describes the built-up of these functions is proposed.

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).

The microinstabilities of a high-β plasma flow with a non-uniform velocity profile

1980 ◽  
Vol 24 (3) ◽  
pp. 385-407 ◽  
Author(s):  
A. B. Mikhailovskii ◽  
V. A. Klimenko
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Velocity Profile ◽  
Kinetic Analysis ◽  
Plasma Flow ◽  
Large Family ◽  
Larmor Radius ◽  
Helmholtz Instability ◽  
Uniform Velocity ◽  
Pressure Plasma

The microinstabilities of a high-pressure plasma moving along a magnetic field with a non-uniform velocity profile are investigated. A similar problem was studied earlier by Dobrowolny on the basis of hydromagnetic equations with an oblique viscosity tensor. The present paper, unlike Dobrowolny's work, gives a kinetic analysis. Perturbations with transverse wavelength both larger and smaller than the ion Larmor radius are considered. The analysis indicates that there is a large family of microinstabilities of the ‘drift’ type whose mechanism differs from the classical Kelvin–Helmholtz instability.

Hydromagnetic wavelike instabilities in a rapidly rotating stratified fluid

1973 ◽  
Vol 61 (3) ◽  
pp. 609-624 ◽  
Author(s):  
D. J. Acheson
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Growth Rates ◽  
Homogeneous Model ◽  
Stratified Fluid ◽  
Generation Mechanism ◽  
Helmholtz Instability ◽  
Coaxial Cylinders ◽  
The Magnetic Field ◽  
Rotating Stratified Fluid

We examine the hydromagnetic stability of a radially stratified fluid rotating between two coaxial cylinders, with particular emphasis on the case when the angular velocity greatly exceeds both buoyant and Alfvén frequencies. If the magnetic field is predominantly azimuthal instabilities then have an essentially non-axisymmetric and wavelike character. Various bounds on their phase speeds and growth rates are derived, including a ‘quadrant’ theorem analogous to Howard's semicircle theorem for Kelvin–Helmholtz instability. Their strong tendency to propagate against the basic rotation (i.e. ‘westward’), previously noted by the author in the study of a more simplified (homogeneous) model, seems relatively insensitive to the generation mechanism (e.g. unstable gradient of magnetic field, angular velocity or density), but a number of counterexamples show that this constraint need not apply if the magnetic field displays significant spatial variations of direction as well as magnitude and that eastward-propagating amplifying modes are then possible.

Evolution of Kelvin-Helmholtz instability at Venus in the presence of the parallel magnetic field

2015 ◽  
Vol 22 (6) ◽  
pp. 062902 ◽  
Author(s):  
H. Y. Lu ◽  
J. B. Cao ◽  
T. L. Zhang ◽  
H. S. Fu ◽  
Y. S. Ge
Keyword(s):  
Magnetic Field ◽  
Helmholtz Instability ◽  
Parallel Magnetic Field
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