Publications (130)216.17 Total impact
 [Show abstract] [Hide abstract]
ABSTRACT: There is no abstract available for this article.  [Show abstract] [Hide abstract]
ABSTRACT: The nonlinear dynamics of ionacoustic waves is investigated in a plasma having fieldaligned shear flow. A KoetewegdeVries (KdV)type nonlinear equation for a modified ionacoustic 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.  [Show abstract] [Hide abstract]
ABSTRACT: The plasma density nonuniformity gives rise to the coupling of transverse magnetic electron drift vortex (MEDV) mode with the longitudinal perturbations in dissipative and nondissipative electron plasmas. This coupling produces partially transverse and partially longitudinal low frequency instabilities in classical unmagnetized 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 unmagnetized 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.  [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 lowfrequency 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 lowfrequency wave discussed here can have many applications in plasma transport and plasma opening switches. 
Article: Small amplitude ionacoustic double layers with cold electron beam and qnonextensive electrons
[Show abstract] [Hide abstract]
ABSTRACT: Small amplitude ionacoustic double layers in an unmagnetized and collisionless plasma consisting of cold positive ions, qnonextensive 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.  [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 currentdriven 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 zeroorder current.  [Show abstract] [Hide abstract]
ABSTRACT: The currentdriven electrostatic solitons and shocks are investigated in flowing plasmas having stationary dust and nonMaxwellian 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.  [Show abstract] [Hide abstract]
ABSTRACT: The soliton formation by the currentdriven driftlike 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 driftlike wave requires sheared flow of electrons and not the density gradient to exist. 
Article: Coupling of the OkudaDawson model with a shear currentdriven wave and the associated instability
[Show abstract] [Hide abstract]
ABSTRACT: It is pointed out that the OkudaDawson mode can couple with the newly proposed currentdriven wave. It is also shown that the ShuklaVarma 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 lowfrequency electrostatic waves and instabilities driven by shear current and shear plasma flow in an electronion plasma with and without stationary dust is also presented.  [Show abstract] [Hide abstract]
ABSTRACT: The linear and nonlinear dynamics of pairion (PI) and pairionelectron 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 quasineutral 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.  [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.  [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 zeroorder 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]  [Show abstract] [Hide abstract]
ABSTRACT: We present nonlinear properties of the lowfrequency nonlinear electrostatic waves in a nonuniform bounded magnetoplasma 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 fieldaligned ion flow with a radial ion velocity gradient in laboratory magnetoplasmas that are bounded and nonuniform.  [Show abstract] [Hide abstract]
ABSTRACT: A mechanism for selfheating 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 flowdriven instability and/or by a sheared flowdriven drift wave. These processes can occur throughout the corona and, hence, this selfheating 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 twoion coronal plasma. In the solar corona, very low frequency (of the order of 1 Hz) drift dissipative waves can also occur due to electronion collisions.  [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 electronion 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 nonuniform zeroorder current in plasmas having stationary dust. One of the modes is flutelike 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. 
Article: Subtlety in the Use of Maxwell's Equation and a New Electromagnetic Wave in Electron Plasmas
[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 nonuniform 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 twodimensional plasma evolution with Beltramilike flow and field due to baroclinic effect has been presented. Particular solution of the nonlinear twofluid 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 Bfield in laserinduced plasmas and the result is in good agreement with experimental values. (C) 2004 American Institute of Physics.  [Show abstract] [Hide abstract]
ABSTRACT: A criterion to define a pure pairion (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 nonlinear differential equations has been obtained for PI plasma dynamics. In moving frame, it can be reduced to a form similar to HasegawaMima equation but it does not contain drift wave.
Publication Stats
1k  Citations  
216.17  Total Impact Points  
Top Journals
 Physics of Plasmas (42)
 Physica Scripta (15)
 Physics Letters A (13)
 Physics of Plasmas (6)
 Astrophysics and Space Science (4)
Institutions

2015

Institute of Space Technology
Islāmābād, Islāmābād, Pakistan


20132014

National Centre for Physics
Islāmābād, Islāmābād, Pakistan


19852014

QuaidiAzam University
 Department of Physics
Islāmābād, Islāmābād, Pakistan


20032013

COMSATS Institute of Information Technology
 Department of Physics
Islāmābād, Islāmābād, Pakistan


19902012

RuhrUniversität Bochum
 • Faculty of Physics and Astronomy
 • Institut für Theoretische Physik I
Bochum, North RhineWestphalia, Germany


20062008

Pakistani Institute of Nuclear Science and Technology
Islāmābād, Islāmābād, Pakistan


20062007

Abdus Salam International Centre for Theoretical Physics
Trst, Friuli Venezia Giulia, Italy


2002

The University of Tokyo
 Graduate School of Frontier Sciences
Tokyo, Tokyoto, Japan
