[Show abstract][Hide abstract] ABSTRACT: The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Koeteweg-deVries (KdV)-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.
Full-text · Article · Aug 2015 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: The plasma density non-uniformity gives rise to the coupling of transverse magnetic electron drift vortex (MEDV) mode with the longitudinal perturbations in dissipative and non-dissipative electron plasmas. This coupling produces partially transverse and partially longitudinal low frequency instabilities in classical un-magnetized laser plasmas. The MEDV mode couples with the ion acoustic wave, when the ion dynamics is also included. Both the modes have frequencies of the same order of magnitude and couple to give rise to electromagnetic
instabilities in un-magnetized plasmas.
No preview · Article · Aug 2015 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: It is pointed out that the analysis of the shear flow and its different limiting cases presented in the paper, Phys. Plasmas
18, 102105 (2011), using kinetic approach is misleading.
Full-text · Article · Apr 2015 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: It is pointed out that in the slow time scale perturbations the displacement current is ignored but it does not imply that the electron density fluctuations vanish. The dispersion relation of the low-frequency electromagnetic wave described within the framework of electron magnetohydrodynamics (EMHD) is modified by taking into account the longitudinal effects. This wave can couple with plasma lower hybrid oscillations if ion dynamics is also considered. The low-frequency wave discussed here can have many applications in plasma transport and plasma opening switches.
No preview · Article · May 2014 · Journal of Plasma Physics
[Show abstract][Hide abstract] ABSTRACT: Small amplitude ion-acoustic double layers in an unmagnetized and collisionless plasma consisting of cold positive ions, q-nonextensive electrons, and a cold electron beam are investigated. Small amplitude double layer solution is obtained by expanding the Sagdeev potential truncated method. The effects of entropic index q, speed and density of cold electron beam on double layer structures are discussed.
No preview · Article · Feb 2014 · Physics Letters A
[Show abstract][Hide abstract] ABSTRACT: It is shown that the sheared flow of electrons and ions in the presence of heavy stationary dust gives rise to unstable Alfvén waves. The coupling of newly studied low frequency electrostatic current-driven mode with the electromagnetic Alfvén and drift waves is investigated. The instability conditions and the growth rates of both inertial and kinetic Alfvén waves are estimated. The theoretical model is applied to the night side boundary regions of Jupiter’s magnetosphere which contain positive dust. The growth rates increase with increase in sheared flow speed. In the nonlinear regime, both inertial and kinetic Alfvén waves form dipolar vortices whose speed and amplitude depend upon the magnitude of the zero-order current.
No preview · Article · Jan 2014 · Astrophysics and Space Science
[Show abstract][Hide abstract] ABSTRACT: The current-driven electrostatic solitons and shocks are investigated in flowing plasmas having stationary dust and non-Maxwellian electrons. The propagation of solar wind parallel to the external magnetic field in the boundary regions of dusty magnetospheres of planets can give rise to drift type unstable electrostatic waves and nonlinear structures even if density is homogeneous. These waves can be produced in laboratory plasma experiments as well. Here the theoretical model is applied to Saturn’s magnetosphere.
No preview · Article · Jan 2014 · Astrophysics and Space Science
[Show abstract][Hide abstract] ABSTRACT: The soliton formation by the current-driven drift-like wave is
investigated for heavier ion (such as barium) plasma experiments planned
to be performed in future. It is pointed out that the sheared flow of
electrons can give rise to short scale solitary structures in the
presence of stationary heavier ions. The nonlinearity appears due to
convective term in the parallel equation of motion and not because of
temperature gradient unlike the case of low frequency usual drift wave
soliton. This higher frequency drift-like wave requires sheared flow of
electrons and not the density gradient to exist.
No preview · Article · Dec 2013 · Physics Letters A
[Show abstract][Hide abstract] ABSTRACT: It is pointed out that the Okuda-Dawson mode can couple with the newly proposed current-driven wave. It is also shown that the Shukla-Varma mode can couple with these waves if the density inhomogeneity is taken into account in a plasma containing stationary dust particles. A comparison of several low-frequency electrostatic waves and instabilities driven by shear current and shear plasma flow in an electron-ion plasma with and without stationary dust is also presented.
No preview · Article · Nov 2013 · Journal of Plasma Physics
[Show abstract][Hide abstract] ABSTRACT: The linear and nonlinear dynamics of pair-ion (PI) and pair-ion-electron
plasmas (PIE) have been investigated in a cylindrical geometry with a
sheared plasma flow along the axial direction having radial dependence.
The coupled linear dispersion relation of low frequency electrostatic
waves has been presented taking into account the Guassian profile of
density and linear gradient of sheared flow. It is pointed out that the
quasi-neutral cold inhomogeneous pure pair ion plasma supports only the
obliquely propagating convective cell mode. The linear dispersion
relation of this mode has been solved using boundary conditions. The
nonlinear structures in the form of vortices formed by different waves
have been discussed in PI and PIE plasmas.
No preview · Article · Oct 2013 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: It is pointed out that interactions between the solar wind and the dusty
magnetospheres of planets and comets give rise to nonlinear
electrostatic drift waves. It is assumed that after transient processes
a local steady state is attained with the same sheared flow of electrons
and ions Vi0(x) = Ve0(x) =
V0(x) z^ along the initial constant
component of B0z of the total sheared magnetic field
B0=B0z z^+B0y (x ) y^. The nonlinear perturbation caused by the electron
temperature gradient forms solitary and shock structures, depending upon
the dominant role of either the wave dispersion or dissipation,
respectively. The theoretical model has been applied to the
magnetosphere of Jupiter that contains positively charged dust grains.
This investigation predicts the formation of short scale electrostatic
solitons having width of the order of 1 m and shocks having widths of
the order of 2 m.
No preview · Article · Aug 2012 · Journal of Geophysical Research Atmospheres
[Show abstract][Hide abstract] ABSTRACT: Nonlinear equations for an electrostatic perturbation in hybrid frequency range are derived in a magnetized heavier ion plasma assuming that the electrons are flowing with a sheared velocity along the initial external constant magnetic field B 0z ^ z. As a result of this current, the total zero-order magnetic field becomes sheared as B 0 ¼ B 0z ^ z þ B 0y ðxÞ^ y. Such a system can give rise to unstable electrostatic waves under certain conditions. The solutions of the nonlinear equations are obtained in the form of dipolar vortices, which can play an important role in plasma transport across field lines. This work can be useful for the future experiments on sheared electron flows. V C 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3700177]
No preview · Article · Apr 2012 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: We present nonlinear properties of the low-frequency nonlinear electrostatic waves in a nonuniform bounded magneto-plasma with the equilibrium density and parallel ion velocity gradients along the radial direction. The existence of electrostatic global vortices in a cylindrical magnetoplasma is established. The present results should help to understand the properties of coherent vortical structures in the presence of a magnetic field-aligned ion flow with a radial ion velocity gradient in laboratory magnetoplasmas that are bounded and nonuniform.
No preview · Article · Jan 2012 · Physics Letters A
[Show abstract][Hide abstract] ABSTRACT: A mechanism for self-heating of the solar corona is discussed. It is shown that the free energy available in the form of sheared flows gives rise to unstable electrostatic perturbations which accelerate and heat particles. The electrostatic perturbations can occur through two processes, viz., by a purely growing sheared flow-driven instability and/or by a sheared flow-driven drift wave. These processes can occur throughout the corona and, hence, this self-heating mechanism could be very important for coronal heating. These instabilities can give rise to local perturbed electrostatic potentials 1 of up to 100 volts within 3 × 10–2 to a few seconds time, if the (dimensionless) initial perturbation is assumed to be about 1%, that is, e1/Te 10–2. The wavelengths in the direction perpendicular to the external magnetic field B
0 vary from about 10 m to 1 m in our model. The purely growing instability creates electrostatic fields by sheared flows even if there is no density gradient, whereas a density gradient is crucial for the occurrence of the drift wave instability. The purely growing instability develops a small real frequency as well in the two-ion coronal plasma. In the solar corona, very low frequency (of the order of 1 Hz) drift dissipative waves can also occur due to electron-ion collisions.
Full-text · Article · Jan 2012 · The Astrophysical Journal
[Show abstract][Hide abstract] ABSTRACT: Solitary inertial Alfvén wave in the presence of positively and
negatively charged dust particles is studied. It is found that electron
density dips are formed in the super Alfvénic region and wave
amplitude is increased for the case of negatively charged dust particles
in comparison with positively charged dust particles in electron-ion
[Show abstract][Hide abstract] ABSTRACT: The flow of electrons and ions with the same sheared velocity introduces new type of electrostatic drift waves and instabilities due to non-uniform zero-order current in plasmas having stationary dust. One of the modes is flute-like and the other also includes ions motion parallel to the background magnetic field. This investigation has applications in the phenomena of solar wind interaction with the dusty plasmas of planets and comets.
No preview · Article · Oct 2011 · Physics Letters A
[Show abstract][Hide abstract] ABSTRACT: The ambiguity involved in the use of Maxwell's equation particularly in
electron plasmas is discussed. It is pointed out that in the slow time scale
perturbations the displacement current is ignored but it does not imply that
the electron density fluctuations vanish. The contradictions in the assumptions
and approximations used in the literature on this subject are discussed. A new
low frequency electromagnetic wave is described which is a normal mode of
non-uniform magnetized electron plasmas. This wave can couple with plasma
hybrid oscillations if ion dynamics is taken into account. It is stressed that
the electron magnetohydrodynamics (EMHD) model seems to be simple but in fact
its use is subtle and its scope is very limited.
[Show abstract][Hide abstract] ABSTRACT: A theory of two-dimensional plasma evolution with Beltrami-like flow and field due to baroclinic effect has been presented. Particular solution of the nonlinear two-fluid equations is obtained. This simple model can explain the generation of magnetic field without assuming the presence of a seed in the system. Coupled field and flow naturally grow together. The theory has been applied to estimate B-field in laser-induced plasmas and the result is in good agreement with experimental values. (C) 2004 American Institute of Physics.
Full-text · Article · Jun 2011 · Physics of Plasmas
[Show abstract][Hide abstract] ABSTRACT: A criterion to define a pure pair-ion (PI) plasma is presented. It is
suggested that the lighter elements (like H and He) are more suitable to
produce PI plasmas. The observation of ion acoustic wave (IAW) in recent
experiments with fullerene plasmas clearly indicates the presence of electrons
in the system. A set of two coupled non-linear differential equations has been
obtained for PI plasma dynamics. In moving frame, it can be reduced to a form
similar to Hasegawa-Mima equation but it does not contain drift wave.