Parallel velocity shear instabilities in an inhomogeneous plasma with a sheared magnetic field

1973 ◽  
Vol 16 (10) ◽  
pp. 1719 ◽  
Author(s):  
Peter J. Catto
Keyword(s):  
Magnetic Field ◽  
Inhomogeneous Plasma ◽  
Velocity Shear ◽  
Shear Instabilities

Parallel velocity shear instabilities in an inhomogeneous plasma

1979 ◽  
Vol 62 (2) ◽  
pp. 353-366 ◽  
Author(s):  
K. M. Srivastava ◽  
D. N. Vyas
Keyword(s):  
Inhomogeneous Plasma ◽  
Velocity Shear ◽  
Shear Instabilities

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).

scholarly journals Compressional wave events in the dawn plasma sheet observed by Interball-1

1999 ◽  
Vol 17 (9) ◽  
pp. 1145-1154 ◽  
Author(s):  
O. Verkhoglyadova ◽  
A. Agapitov ◽  
A. Andrushchenko ◽  
V. Ivchenko ◽  
S. Romanov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Field Line ◽  
Plasma Sheet ◽  
Inhomogeneous Plasma ◽  
Partial Solution ◽  
Alfven Wave ◽  
Data Set ◽  
Background Magnetic Field ◽  
Phase Variations

Abstract. Compressional waves with periods greater than 2 min (about 10-30 min) at low geomagnetic latitudes, namely compressional Pc5 waves, are studied. The data set obtained with magnetometer MIF-M and plasma analyzer instrument CORALL on board the Interball-1 are analyzed. Measurements performed in October 1995 and October 1996 in the dawn plasma sheet at -30 RE ≤ XGSM and |ZGSM| ≤ 10 RE are considered. Anti-phase variations of magnetic field and ion plasma pressures are analyzed by searching for morphological similarities in the two time series. It is found that longitudinal and transverse magnetic field variations with respect to the background magnetic field are of the same order of magnitude. Plasma velocities are processed for each time period of the local dissimilarity in the pressure time series. Velocity disturbances occur mainly transversely to the local field line. The data reveal the rotation of the velocity vector. Because of the field line curvature, there is no fixed position of the rotational plane in the space. These vortices are localized in the regions of anti-phase variations of the magnetic field and plasma pressures, and the vortical flows are associated with the compressional Pc5 wave process. A theoretical model is proposed to explain the main features of the nonlinear wave processes. Our main goal is to study coupling of drift Alfven wave and magnetosonic wave in a warm inhomogeneous plasma. A vortex is the partial solution of the set of the equations when the compression is neglected. A compression effect gives rise to a nonlinear soliton-like solution.Key words. Magnetosphere physics (magnetotail) · Space plasma physics (kinetic and MHD theory; non-linear phenomena)

scholarly journals Interacting vorticity waves as an instability mechanism for magnetohydrodynamic shear instabilities

2015 ◽  
Vol 767 ◽  
pp. 199-225 ◽  
Author(s):  
E. Heifetz ◽  
J. Mak ◽  
J. Nycander ◽  
O. M. Umurhan
Keyword(s):  
Magnetic Field ◽  
Phase Locking ◽  
Unstable Flow ◽  
Background Magnetic Field ◽  
Non Local ◽  
Action At A Distance ◽  
Shear Instabilities ◽  
Basic States ◽  
The Waves ◽  
Stable Flow

AbstractThe interacting vorticity wave formalism for shear flow instabilities is extended here to the magnetohydrodynamic (MHD) setting, to provide a mechanistic description for stabilising and destabilising shear instabilities by the presence of a background magnetic field. The interpretation relies on local vorticity anomalies inducing a non-local velocity field, resulting in action at a distance. It is shown here that the waves supported by the system are able to propagate vorticity via the Lorentz force, and waves may interact. The existence of instability then rests upon whether the choice of basic state allows for phase locking and constructive interference of the vorticity waves via mutual interaction. To substantiate this claim, we solve the instability problem of two representative basic states, one where a background magnetic field stabilises an unstable flow and the other where the field destabilises a stable flow, and perform relevant analyses to show how this mechanism operates in MHD.

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