E. F. El-Shamy

Head-on-collision of modulated dust acoustic waves in strongly coupled dusty plasma

The derivative expansion perturbation method is applied to a strongly coupled dusty plasma system consisting of negatively charged dust grains, electrons, and ions. The basic equations are reduced to a nonlinear Schrodinger type equation appropriate for describing the modulated dust acoustic (DA) waves. We have examined the modulation (in) stability and the dependence of the system physical parameters (angular frequency and group velocity) on the polarization force variation. Finally, the extended Poincare-Lighthill-Kuo technique is employed to investigate the head-on collision (HoC) between two DA dark solitons. The analytical phase shifts and the trajectories of these dark solitons after the collision are derived. The numerical illustrations show that the polarization effect has strong influence on the nature of the phase shifts and the trajectories of the two DA dark solitons after collision.

The interaction between two planar and nonplanar quantum electron acoustic solitary waves in dense electron-ion plasmas

The interaction between two planar and nonplanar (cylindrical and spherical) quantum electron acoustic solitary waves (QEASWs) in quantum dense electron-ion plasmas has been studied. The extended Poincare-Lighthill-Kuo method is used to obtain planar and nonplanar phase shifts after the interaction of the two QEASWs. The change of phase shifts and trajectories for QEASWs due to the effect of the different geometries, the quantum corrections of diffraction, and the cold electron-to-hot electron number density ratio are discussed. It is shown that the interaction of the QEASWs in planar geometry, cylindrical geometry, and spherical geometry are different. The present investigation may be beneficial to understand the interaction between two planar and nonplanar QEASWs that may occur in the quantum plasmas found in laser-produced plasmas as well as in astrophysical plasmas.

Nonplanar dust acoustic solitary waves in a strongly coupled dusty plasma with superthermal ions

The nonplanar amplitude modulation of dust acoustic (DA) envelope solitary waves in a strongly coupled dusty plasma (SCDP) has been investigated. By using a reductive perturbation technique, a modified nonlinear Schrodinger equation (NLSE) including the effects of geometry, polarization, and ion superthermality is derived. The modulational instability (MI) of the nonlinear DA wave envelopes is investigated in both planar and nonplanar geometries. There are two stable regions for the DA wave propagation strongly affected by polarization and ion superthermality. Moreover, it is found that the nonlinear DA waves in spherical geometry are the more structurally stable. The larger growth rate of the nonlinear DA MI is observed in the cylindrical geometry. The salient characteristics of the MI in the nonplanar geometries cannot be found in the planar one. The DA wave propagation and the NLSE solutions are investigated both analytically and numerically.

Modeling of nonlinear envelope solitons in strongly coupled dusty plasmas: Instability and collision

Modeling of instability and collision of nonlinear dust-acoustic (NDA) envelope solitons in strongly coupled dusty plasmas (SCDPs) is theoretically investigated. The SCDPs consists of strongly correlated negatively variable-charged dust grains and weakly correlated Boltzmann electrons and ions. Using the derivative expansion perturbation technique, a nonlinear Schr?dinger-type (NLST) equation for describing the propagation of NDA envelope solitons is derived. Moreover, the extended Poincar??Lighthill?Kuo (EPLK) method is employed to deduce the analytical phase shifts and the trajectories after the collision of NDA envelope solitons. In detail, the results show that both modulation instability and phase shift after collision of NDA envelope solitons will modify with the increase in the effects of the viscosity, the relaxation time, and the dust charge fluctuation. Crucially, the modeling of dust-acoustic envelope solitons collision, as reported here, is helpful for understanding the propagation of NDA envelope solitons in strongly coupled dusty plasmas.

Nonlinear propagation of electrostatic travelling waves in degenerate dense magnetoplasmas

The electrostatic travelling wave structures have been investigated in degenerate dense magnetoplasmas consisting of relativistic degenerate inertialess electrons and positrons, as well as nondegenerate inertial cold ions. The well known reductive perturbation method has been applied in obtaining the nonlinear Zakharov-Kuznetsov equation. The formation of the electrostatic solitary waves and periodic travelling waves is carried out by the bifurcation theory of planar dynamical systems. The results demonstrate that the nonlinear electrostatic travelling waves strongly depend on the concentration of positrons, the ion cyclotron frequency, and the direction cosines of the wave vector. The obtained results here may be useful for better understanding of the structure of nonlinear electrostatic travelling wave in dense plasmas, such as the interior of massive white dwarfs.

Nonlinear ion acoustic ring solitons in a multicomponent plasma with superthermal electrons: Propagation and collision

In this paper, the propagation and the collision of ion acoustic ring solitons (IARSs) in a multicomponent plasma with superthermal electrons are theoretically investigated by employing an extended Poincare–Lighthill–Kuo method. For the generic case, the dynamics and collisions of IARSs are studied via cylindrical Korteweg-de Vries (cKdV) equations and phase shift equations. It is found physically that both positive and negative polarity IARSs can propagate and collide, which usually leads to a time delay in propagation occurring during the collision, as compared to a single ion acoustic soliton (IARS) without collisions in the same physical model. Moreover, at a critical value of the negative ion-to-positive ion concentration, modified cylindrical Korteweg-de Vries (mcKdV) equations and their corresponding phase shifts have been derived. In general, it is observed that the trajectories of IARSs after collisions are significantly modified due to the influence of negative ion-to-positive ion density ratio,...

Nonlinear dust-ion acoustic periodic travelling waves in a magnetized plasma with two temperature superthermal electrons and stationary charged dust grains

In this research, the nonlinear propagation of dust-ion acoustic (DIA) periodic travelling waves in a dusty plasma consisting of cold ions, stationary charged dust grains, and two temperature superthermal electrons is theoretically studied. A nonlinear Zakharov-Kuznetsov equation, which describes nonlinear dust-ion acoustic waves, is derived using a reductive perturbation method. Furthermore, the bifurcation theory has been employed to study the nonlinear propagation of DIA periodic travelling wave solutions. In the proposed model, the co-existence of both compressive and rarefactive DIA periodic travelling waves are found. The numerical investigations illustrate that the characteristics of nonlinear DIA periodic travelling waves strongly depend on the temperature ratio, both the concentration and the superthermality of cold electrons, the ion cyclotron frequency, the direction cosines of wave vector k along z axis, and the concentration of dusty grains. The present investigation can help in better unders...

The effects of geometrical configurations on the head collision on nonlinear solitary pulses in a quantum semiconductor plasma: A case study on GaAs semiconductor

An investigation is presented to examine nonlinear electrostatic waves in a quantum semiconductor plasma. A quantum semiconductor plasma model consisting of electrons and holes is going to be used, which includes exchange–correlation potentials, the quantum recoil effect, and degenerate pressures of electrons and holes. Actually, a nonlinear solitary pulse can be used to represent the intrinsic coherent electrostatic wave in a quantum semiconductor plasma. The propagation and the collision of nonlinear solitary pulses are examined by the extended Poincare-Lighthill-Kuo method. Typical values for the GaAs semiconductors are employed to investigate the basic characteristics of solitary pulses. The numerical studies show that the energies and then the trajectories of nonlinear solitary pulses after the collision are significantly changed due to the effects of the exchange and correlation potentials and the variety in the studied systems geometry. The results obtained here may be useful for gaining a better ...