[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.
Physics of Plasmas 08/2015; 22(8):084509. DOI:10.1063/1.4928916 · 2.14 Impact Factor
[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.
[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.
Physics Letters A 02/2014; 378(10). DOI:10.1016/j.physleta.2014.01.015 · 1.68 Impact Factor
[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.
Astrophysics and Space Science 01/2014; 349(1). DOI:10.1007/s10509-013-1611-2 · 2.26 Impact Factor
[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.
Astrophysics and Space Science 01/2014; 349(1). DOI:10.1007/s10509-013-1658-0 · 2.26 Impact Factor
[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.
Physics Letters A 12/2013; 377(43):3128-3130. DOI:10.1016/j.physleta.2013.07.061 · 1.68 Impact Factor
[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.
[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.
Physics of Plasmas 10/2013; 20(10):2304-. DOI:10.1063/1.4824002 · 2.14 Impact Factor
[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.
Journal of Geophysical Research Atmospheres 08/2012; 117(A8):8220-. DOI:10.1029/2011JA017306 · 3.43 Impact Factor
[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]
Physics of Plasmas 04/2012; 19(4):042107. DOI:10.1063/1.3700177 · 2.14 Impact Factor
[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.
Physics Letters A 01/2012; 376(4):497–499. DOI:10.1016/j.physleta.2011.10.065 · 1.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A mechanism of self-heating of solar corona is pointed out. It is shown that
the free energy available in the form of sheared flows gives rise to unstable
electrostatic waves which accelerate the particles and heat them. The
electrostatic perturbations take place through two processes (a) by purely
growing sheared flow-driven instability and (b) by sheared flow-driven drift
waves. These processes occur throughout the corona and hence the self-heating
is very important in this plasma. These instabilities can give rise to local
electrostatic potentials $\varphi$ of the order of about 100 volts or less
within $3\times10^{-2}$ to a few seconds time if the initial perturbation is
assumed to be about one percent that is $\frac{e\varphi}{T_{e}}\simeq10^{-2}$.
The components of wave lengths in the direction perpendicular to external
magnetic field $\textbf{B}_{0}$ vary from about 10m to 1m. The purely growing
instability creates electrostatic fields by sheared flows even if the density
gradient does not exist whereas the density gradient is crucial for the
concurrence of drift wave instability. Subject headings: Sun: self-heating of
corona, sheared flow-driven instability, drift waves.
The Astrophysical Journal 01/2012; 748(2). DOI:10.1088/0004-637X/748/2/90 · 5.99 Impact Factor
[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
plasmas.
[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.
Physics Letters A 10/2011; 375(44):3877-3879. DOI:10.1016/j.physleta.2011.07.060 · 1.68 Impact Factor
[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.
Physics of Plasmas 06/2011; 11(10). DOI:10.1063/1.1793173 · 2.14 Impact Factor
[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.
[Show abstract][Hide abstract] ABSTRACT: The shear flow-driven electrostatic instabilities are investigated in ideal low density, low temperature pair-ion-electron and pure pair-ion plasmas in several different cases, including homogeneous and inhomogeneous density effects. In uniform pair-ion-electron plasma, when the shear flow is of the order of the acoustic speed, the purely growing D’Angelo mode can give rise to electrostatic fields. In the case of an inhomogeneous plasma, the drift wave becomes unstable. The presence of negative ions, however, reduces the growth rate. If the positive and negative ions are not in thermal equilibrium with each other, then the shear flow also gives rise to an electrostatic instability in pure pair-ion plasma.
Physics of Plasmas 05/2011; 18(5). DOI:10.1063/1.3589474 · 2.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It is found that the zero-order current associated with electron shear flow produces a drift wave in magnetized plasmas, which can become unstable under certain conditions. This wave will be particularly important in low density and low temperature plasmas of heavy ions. As an example, numerical estimates are presented for a barium plasma with parameters compatible with experiments.
Physics of Plasmas 05/2011; 18(5):052103-052103-4. DOI:10.1063/1.3571630 · 2.14 Impact Factor