Nusrat Jehan - Academia.edu (original) (raw)

Papers by Nusrat Jehan

Research paper thumbnail of A new equation in two dimensional fast magnetoacoustic shock waves in electron-positron-ion plasmas

Physics of Plasmas, Mar 1, 2010

Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-com... more Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-component plasma comprising of electrons, positrons, and ions. In this regard, Kadomtsev-Petviashvili-Burger (KPB) equation is derived using the small amplitude perturbation expansion method. Under the condition that the electron and positron inertia are ignored, Burger-Kadomtsev-Petviashvili (Burger-KP) for a fast magnetoacoustic wave is derived for the first time, to the best of author's knowledge. The solutions of both KPB and Burger-KP equations are obtained using the tangent hyperbolic method. The effects of positron concentration, kinematic viscosity, and plasma β are explored both for the KPB and the Burger-KP shock waves and the differences between the two are highlighted. The present investigation may have relevance in the study of nonlinear electromagnetic shock waves both in laboratory and astrophysical plasmas.

Research paper thumbnail of Planar and non-planar ion acoustic shock waves in electron–positron–ion plasmas

Physics Letters A, 2008

Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, ... more Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, positrons and adiabatically hot positive ions. This is done by deriving the Kortweg-deVries-Burger (KdVB) equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. It is observed that the positron concentration, ratio of ion to electron temperature, and the plasma kinematic viscosity significantly modifies the shock structure. Finally, it is found that the temporal evolution of the non-planar IASW's is quite different by comparison with the planar geometry. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

Research paper thumbnail of Modulation instability of low-frequency electrostatic ion waves in magnetized electron-positron-ion plasma

Physics of Plasmas, 2008

The nonlinear amplitude modulation of low-frequency electrostatic ion waves propagating in collis... more The nonlinear amplitude modulation of low-frequency electrostatic ion waves propagating in collisionless magnetized electron-positron-ion plasma are studied. The Krylov–Bogoliubov–Mitropolsky perturbation method is employed to derive the nonlinear Schrödinger equation. ...

Research paper thumbnail of Perpendicular propagating electromagnetic envelope solitons in electron-positron-ion plasma

Physics of Plasmas, 2010

The nonlinear amplitude modulation of electromagnetic waves propagating perpendicular to the dire... more The nonlinear amplitude modulation of electromagnetic waves propagating perpendicular to the direction of ambient magnetic field in a uniform collisionless magnetized electron-positron-ion plasma is studied. The Krylov-Bogoliubov-Mitropolsky perturbation method is employed to derive nonlinear Schrödinger equation, which describes the amplitude dynamics of perturbed magnetic field. The modulation instability criterion reveals that the low frequency mode is always stable, whereas the high frequency mode becomes modulationally unstable for certain ranges of wave number and positron-to-electron density ratio. Furthermore, the positron-to-electron density ratio as well as the strength of ambient magnetic field is found to have significant effect on the solitary wave solutions of the nonlinear Schrödinger equation, namely, dark and bright envelope solitons.

Research paper thumbnail of A new equation in two dimensional fast magnetoacoustic shock waves in electron-positron-ion plasmas

Physics of Plasmas, 2010

Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-com... more Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-component plasma comprising of electrons, positrons, and ions. In this regard, Kadomtsev-Petviashvili-Burger ͑KPB͒ equation is derived using the small amplitude perturbation expansion method. Under the condition that the electron and positron inertia are ignored, Burger-Kadomtsev-Petviashvili ͑Burger-KP͒ for a fast magnetoacoustic wave is derived for the first time, to the best of author's knowledge. The solutions of both KPB and Burger-KP equations are obtained using the tangent hyperbolic method. The effects of positron concentration, kinematic viscosity, and plasma ␤ are explored both for the KPB and the Burger-KP shock waves and the differences between the two are highlighted. The present investigation may have relevance in the study of nonlinear electromagnetic shock waves both in laboratory and astrophysical plasmas.

Research paper thumbnail of Oblique modulation of ion-acoustic waves and envelope solitons in electron-positron-ion plasma

Physics of Plasmas, 2009

The effect of oblique modulation on the amplitude dynamics of ion-acoustic wave propagating in a ... more The effect of oblique modulation on the amplitude dynamics of ion-acoustic wave propagating in a collisionless electron-positron-ion plasma is investigated. Using Krylov-Bogoliubov-Mitropolsky ͑KBM͒ perturbation method, a nonlinear Schrödinger ͑NLS͒ equation is derived which governs the evolution of obliquely modulated ion-acoustic envelope excitations. It is found that the presence of positron component significantly modifies the stability domains for small angles of propagation with the direction of modulation. The stationary solutions of NLS equation, i.e., bright and dark envelope solitons, become narrower as the concentration of positron component increases.

Research paper thumbnail of Electrostatic solitary ion waves in dense electron-positron-ion magnetoplasma

Physics of Plasmas, 2009

The nonlinear coupled ion-acoustic and ion-cyclotron waves propagating obliquely to the external ... more The nonlinear coupled ion-acoustic and ion-cyclotron waves propagating obliquely to the external magnetic field in dense collisionless electron-positron-ion magnetoplasma are investigated using Sagdeev potential method. A semiclassical approach is used. Electrons and positrons are treated as degenerate Fermi gases described by Thomas-Fermi density distribution and ions behave as classical gas. It is found that the presence of degenerate positrons in a dense Thomas-Fermi plasma significantly modifies the structure of solitary waves by restricting the electrostatic potential to a certain maximum value which depends upon the concentration of positrons in the system. It is also noted that only subsonic humplike solitary waves can exist and for a given angle of propagation, the presence of degenerate positrons diminishes the amplitude as well as width of the solitary wave.

Research paper thumbnail of Planar and cylindrical magnetosonic solitary and shock waves in dissipative, hot electron-positron-ion plasma

Physics of Plasmas, 2011

Planar and cylindrical magnetosonic solitary and shock structures are studied in a hot and dissip... more Planar and cylindrical magnetosonic solitary and shock structures are studied in a hot and dissipative plasma consisting of electrons, positrons, and ions. By employing the reductive perturbative method, a modified Korteweg-de Vries Burgers (mKdVB) equation is derived in the limit of low frequency and long wavelength by taking into account viscous dissipation of the three species. The effects of variation of various plasma parameters on the profiles of planar and cylindrical solitary and shock structures are discussed. In the limit, when certain terms of the mKdVB equation are small enough to be treated as perturbation, analytical solutions are obtained and compared with the corresponding numerical ones.

Research paper thumbnail of Cylindrical and spherical ion-acoustic solitons in adiabatically hot electron–positron–ion plasmas

Physica Scripta, 2007

... Plasmas 2 716 [15] Nejoh YN 1996 Phys. Plasmas 3 1447 [16] Salahuddin M, Saleem H and Saddiq ... more ... Plasmas 2 716 [15] Nejoh YN 1996 Phys. Plasmas 3 1447 [16] Salahuddin M, Saleem H and Saddiq M 2002 Phys. Rev. ... Scr. 68 295 [20] Mahmood S, Mushtaq A and Saleem H 2003 New J. Phys. 5 28 [21] Mahmood S and Saleem H 2003 Phys. ...

Research paper thumbnail of Planar and nonplanar dust acoustic solitary waves in electron–positron–ion–dust plasmas

Physica Scripta, 2009

... 1 Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad... more ... 1 Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan 2 Pakistan Atomic Energy Commission ... Plasmas 8 1791 [3] Shukla PK and Mamun AA 2002 Introduction to Dusty Plasma Physics (Bristol: Institute of Physics) [4 ...

Research paper thumbnail of Dissipative cylindrical fast magnetoacoustic waves in planetary magnetospheres

Astrophysics and Space Science, 2011

Nonlinear cylindrical fast magnetoacoustic waves are investigated in a dissipative magnetoplasma ... more Nonlinear cylindrical fast magnetoacoustic waves are investigated in a dissipative magnetoplasma comprising of electrons, positrons, and ions. In this regard, cylindrical Kadomtsev-Petviashvili-Burgers (CKPB) equation is derived using the small amplitude perturbation expansion method. Furthermore, cylindrical Burgers-Kadomtsev-Petviashvili (Cyl Burgers-KP) for a fast magnetoacoustic wave is derived, for the first time, for spatial scales larger than the electron/positron skin depths, c/ω p(e,p).

Research paper thumbnail of Modulational instability of ion-acoustic waves in a warm plasma

Research paper thumbnail of Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas

Physica Scripta, 2007

Page 1. Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas... more Page 1. Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2007 Phys. Scr. 75 755 (http://iopscience.iop.org/1402-4896/75/6/002) ...

Research paper thumbnail of A new equation in two dimensional fast magnetoacoustic shock waves in electron-positron-ion plasmas

Physics of Plasmas, Mar 1, 2010

Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-com... more Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-component plasma comprising of electrons, positrons, and ions. In this regard, Kadomtsev-Petviashvili-Burger (KPB) equation is derived using the small amplitude perturbation expansion method. Under the condition that the electron and positron inertia are ignored, Burger-Kadomtsev-Petviashvili (Burger-KP) for a fast magnetoacoustic wave is derived for the first time, to the best of author's knowledge. The solutions of both KPB and Burger-KP equations are obtained using the tangent hyperbolic method. The effects of positron concentration, kinematic viscosity, and plasma β are explored both for the KPB and the Burger-KP shock waves and the differences between the two are highlighted. The present investigation may have relevance in the study of nonlinear electromagnetic shock waves both in laboratory and astrophysical plasmas.

Research paper thumbnail of Planar and non-planar ion acoustic shock waves in electron–positron–ion plasmas

Physics Letters A, 2008

Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, ... more Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, positrons and adiabatically hot positive ions. This is done by deriving the Kortweg-deVries-Burger (KdVB) equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. It is observed that the positron concentration, ratio of ion to electron temperature, and the plasma kinematic viscosity significantly modifies the shock structure. Finally, it is found that the temporal evolution of the non-planar IASW's is quite different by comparison with the planar geometry. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

Research paper thumbnail of Modulation instability of low-frequency electrostatic ion waves in magnetized electron-positron-ion plasma

Physics of Plasmas, 2008

The nonlinear amplitude modulation of low-frequency electrostatic ion waves propagating in collis... more The nonlinear amplitude modulation of low-frequency electrostatic ion waves propagating in collisionless magnetized electron-positron-ion plasma are studied. The Krylov–Bogoliubov–Mitropolsky perturbation method is employed to derive the nonlinear Schrödinger equation. ...

Research paper thumbnail of Perpendicular propagating electromagnetic envelope solitons in electron-positron-ion plasma

Physics of Plasmas, 2010

The nonlinear amplitude modulation of electromagnetic waves propagating perpendicular to the dire... more The nonlinear amplitude modulation of electromagnetic waves propagating perpendicular to the direction of ambient magnetic field in a uniform collisionless magnetized electron-positron-ion plasma is studied. The Krylov-Bogoliubov-Mitropolsky perturbation method is employed to derive nonlinear Schrödinger equation, which describes the amplitude dynamics of perturbed magnetic field. The modulation instability criterion reveals that the low frequency mode is always stable, whereas the high frequency mode becomes modulationally unstable for certain ranges of wave number and positron-to-electron density ratio. Furthermore, the positron-to-electron density ratio as well as the strength of ambient magnetic field is found to have significant effect on the solitary wave solutions of the nonlinear Schrödinger equation, namely, dark and bright envelope solitons.

Research paper thumbnail of A new equation in two dimensional fast magnetoacoustic shock waves in electron-positron-ion plasmas

Physics of Plasmas, 2010

Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-com... more Nonlinear properties of the two dimensional fast magnetoacoustic waves are studied in a three-component plasma comprising of electrons, positrons, and ions. In this regard, Kadomtsev-Petviashvili-Burger ͑KPB͒ equation is derived using the small amplitude perturbation expansion method. Under the condition that the electron and positron inertia are ignored, Burger-Kadomtsev-Petviashvili ͑Burger-KP͒ for a fast magnetoacoustic wave is derived for the first time, to the best of author's knowledge. The solutions of both KPB and Burger-KP equations are obtained using the tangent hyperbolic method. The effects of positron concentration, kinematic viscosity, and plasma ␤ are explored both for the KPB and the Burger-KP shock waves and the differences between the two are highlighted. The present investigation may have relevance in the study of nonlinear electromagnetic shock waves both in laboratory and astrophysical plasmas.

Research paper thumbnail of Oblique modulation of ion-acoustic waves and envelope solitons in electron-positron-ion plasma

Physics of Plasmas, 2009

The effect of oblique modulation on the amplitude dynamics of ion-acoustic wave propagating in a ... more The effect of oblique modulation on the amplitude dynamics of ion-acoustic wave propagating in a collisionless electron-positron-ion plasma is investigated. Using Krylov-Bogoliubov-Mitropolsky ͑KBM͒ perturbation method, a nonlinear Schrödinger ͑NLS͒ equation is derived which governs the evolution of obliquely modulated ion-acoustic envelope excitations. It is found that the presence of positron component significantly modifies the stability domains for small angles of propagation with the direction of modulation. The stationary solutions of NLS equation, i.e., bright and dark envelope solitons, become narrower as the concentration of positron component increases.

Research paper thumbnail of Electrostatic solitary ion waves in dense electron-positron-ion magnetoplasma

Physics of Plasmas, 2009

The nonlinear coupled ion-acoustic and ion-cyclotron waves propagating obliquely to the external ... more The nonlinear coupled ion-acoustic and ion-cyclotron waves propagating obliquely to the external magnetic field in dense collisionless electron-positron-ion magnetoplasma are investigated using Sagdeev potential method. A semiclassical approach is used. Electrons and positrons are treated as degenerate Fermi gases described by Thomas-Fermi density distribution and ions behave as classical gas. It is found that the presence of degenerate positrons in a dense Thomas-Fermi plasma significantly modifies the structure of solitary waves by restricting the electrostatic potential to a certain maximum value which depends upon the concentration of positrons in the system. It is also noted that only subsonic humplike solitary waves can exist and for a given angle of propagation, the presence of degenerate positrons diminishes the amplitude as well as width of the solitary wave.

Research paper thumbnail of Planar and cylindrical magnetosonic solitary and shock waves in dissipative, hot electron-positron-ion plasma

Physics of Plasmas, 2011

Planar and cylindrical magnetosonic solitary and shock structures are studied in a hot and dissip... more Planar and cylindrical magnetosonic solitary and shock structures are studied in a hot and dissipative plasma consisting of electrons, positrons, and ions. By employing the reductive perturbative method, a modified Korteweg-de Vries Burgers (mKdVB) equation is derived in the limit of low frequency and long wavelength by taking into account viscous dissipation of the three species. The effects of variation of various plasma parameters on the profiles of planar and cylindrical solitary and shock structures are discussed. In the limit, when certain terms of the mKdVB equation are small enough to be treated as perturbation, analytical solutions are obtained and compared with the corresponding numerical ones.

Research paper thumbnail of Cylindrical and spherical ion-acoustic solitons in adiabatically hot electron–positron–ion plasmas

Physica Scripta, 2007

... Plasmas 2 716 [15] Nejoh YN 1996 Phys. Plasmas 3 1447 [16] Salahuddin M, Saleem H and Saddiq ... more ... Plasmas 2 716 [15] Nejoh YN 1996 Phys. Plasmas 3 1447 [16] Salahuddin M, Saleem H and Saddiq M 2002 Phys. Rev. ... Scr. 68 295 [20] Mahmood S, Mushtaq A and Saleem H 2003 New J. Phys. 5 28 [21] Mahmood S and Saleem H 2003 Phys. ...

Research paper thumbnail of Planar and nonplanar dust acoustic solitary waves in electron–positron–ion–dust plasmas

Physica Scripta, 2009

... 1 Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad... more ... 1 Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan 2 Pakistan Atomic Energy Commission ... Plasmas 8 1791 [3] Shukla PK and Mamun AA 2002 Introduction to Dusty Plasma Physics (Bristol: Institute of Physics) [4 ...

Research paper thumbnail of Dissipative cylindrical fast magnetoacoustic waves in planetary magnetospheres

Astrophysics and Space Science, 2011

Nonlinear cylindrical fast magnetoacoustic waves are investigated in a dissipative magnetoplasma ... more Nonlinear cylindrical fast magnetoacoustic waves are investigated in a dissipative magnetoplasma comprising of electrons, positrons, and ions. In this regard, cylindrical Kadomtsev-Petviashvili-Burgers (CKPB) equation is derived using the small amplitude perturbation expansion method. Furthermore, cylindrical Burgers-Kadomtsev-Petviashvili (Cyl Burgers-KP) for a fast magnetoacoustic wave is derived, for the first time, for spatial scales larger than the electron/positron skin depths, c/ω p(e,p).

Research paper thumbnail of Modulational instability of ion-acoustic waves in a warm plasma

Research paper thumbnail of Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas

Physica Scripta, 2007

Page 1. Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas... more Page 1. Cylindrical and spherical dust acoustic solitary waves in adiabatically hot dusty plasmas This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2007 Phys. Scr. 75 755 (http://iopscience.iop.org/1402-4896/75/6/002) ...