N. Akhtar

Ion acoustic shock waves in degenerate plasmas

Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

Non Planar Electrostatic Solitary Wave Structures in Negative Ion Degenerate Plasma

Theoretical and numerical studies are performed for quantum ion acoustic solitons in planar and non-planar geometries in an unmagnetized homogenous plasma consisting of warm positive and negative ions with nonthermal electrons. A deformed Korteweg de Vries (DKdV) equation is derived by using the reductive perturbation method. The numerical solution to the DKdV equation indicates that the quantum parameter, temperatures of positive ions, temperture of negative ions and electron density blatantly influence the propagation speed and the structure of quantum ion acoustic solitons. The geometrical effects on the structure of quantum ion acoustic wave are discussed. It is shown that the amplitude and propagation speed in spherical geometry is larger as compared to cylinderical and planar geometries for different values of the above-mentioned parameters.

Propagation of ion acoustic shock waves in negative ion plasmas with nonextensive electrons

Nonlinear ion acoustic shocks (monotonic as well as oscillatory) waves in negative ion plasmas are investigated. The inertialess electron species are assumed to be nonthermal and follow Tsallis distribution. The dissipation in the plasma is considered via kinematic viscosities of both positive and negative ion species. The Korteweg-de Vries Burgers (KdVB) equation is derived using small amplitude reductive perturbation technique and its analytical solution is presented. The effects of variation of density and temperature of negative ions and nonthermal parameter q of electrons on the strength of the shock structures are plotted for illustration. The numerical solutions of KdVB equation using Runge Kutta method are obtained, and transition from oscillatory to monotonic shock structures is also discussed in detail for negative ions nonthermal plasmas.

Acoustic double layer structures in dense magnetized electron-positron-ion plasmas

The acoustic double layer structures are studied using quantum hydrodynamic model in dense magnetized electron-positron-ion plasmas. The extended Korteweg-de Vries is derived using reductive perturbation method. It is found that increase in the ion concentration in dense magnetized electron-positron plasmas increases the amplitude as well as the steepness of the double layer structure. However, increase in the magnetic field strength and decrease in the obliqueness of the nonlinear acoustic wave enhances only the steepness of the double layer structures. The numerical results have also been shown by using the data of the outer layer regions of white dwarfs given in the literature.

Nonlinear quantum ion acoustic waves in a Fermi plasma

Ion acoustic waves in a homogeneous quantum plasma, comprising of positive, negative ions, and electrons, have been investigated via the Korteweg–de Vries equation. The positive and negative ions are taken inertial and electrons are taken as inertialess. It is determined that the dispersive property of quantum plasma is strongly related to the quantum diffraction parameter. The quantum diffraction parameter (He), ion mass ratio (m), and negative ion temperature ratio (β) blatantly influence the propagation and type (compressive/rarefactive) of nonlinear ion acoustic solitary wave. It is noticed that soliton amplitude follows a dual trend at higher and lower concentrations of negative ions. The theoretical calculations presented are applicable to analyze the propagation of ion acoustic waves in a quantum electron-ion plasma containing negative ions in addition.

Imploding and exploding shocks in negative ion degenerate plasmas

Imploding and exploding shocks are studied in nonplanar geometries for negative ion degenerate plasma. Deformed Korteweg de Vries Burgers (DKdVB) equation is derived by using reductive perturbation method. Two level finite difference scheme is used for numerical analysis of DKdVB. It is observed that compressive and rarefactive shocks are observed depending on the value of quantum parameter. The effects of temperature, kinematic viscosity, mass ratio of negative to positive ions and quantum parameter on diverging and converging shocks are presented.

Ion acoustic shocks in magneto rotating Lorentzian plasmas

Ion acoustic shock structures in magnetized homogeneous dissipative Lorentzian plasma under the effects of Coriolis force are investigated. The dissipation in the plasma system is introduced via dynamic viscosity of inertial ions. The electrons are following the kappa distribution function. Korteweg-de Vries Burger (KdVB) equation is derived by using reductive perturbation technique. It is shown that spectral index, magnetic field, kinematic viscosity of ions, rotational frequency, and effective frequency have significant impact on the propagation characteristic of ion acoustic shocks in such plasma system. The numerical solution of KdVB equation is also discussed and transition from oscillatory profile to monotonic shock for different plasma parameters is investigated.

Effects of adiabatic hot dust on arbitrary amplitude electrostatic solitary structures in magnetoplasmas

The effects of dust temperature on arbitrary amplitude dust acoustic solitary waves in a homogeneous magnetized plasma are studied. It is found that the dust temperature is destructive for the formation of solitons in magnetized plasmas. This behavior is similar to the case of unmagnetized hot dusty plasmas. However, the soliton amplitude increases with the increase in the obliqueness of the wave propagation. The numerical results are also shown for illustrative purposes.

Dust Charge Polarity Effect on Dust-Ion Acoustic Modulational Instability in a Nonthermal Dusty Plasma With Adiabatic Ions

The effects of dust charge polarity, ion temperature, and nonthermal electrons on dust-ion acoustic modulational instability and on the region (i.e., modulated wave number) for the formation of bright and dark envelope soliton structures are investigated. The dust particles are considered to be stationary and have positive and negative charges, while ions are taken dynamic and warm, and hot nonthermal electrons are assumed to be inertialess and kappa distributed in a dusty plasma. The Krylov-Bogoliubov-Mitropolsky method is used to derive the nonlinear Schrödinger equation (NLSE) for nonlinear amplitude modulation of dust-ion acoustic wave (DIAW) in plasmas. The dispersive and nonlinear coefficients of NLSE are obtained for DIAW, which depends on ion temperature, spectral indices of the nonthermal distributed electrons, dust density, and charge polarity of stationary dust particles. The modulationally stable and unstable regions of DIAW and its growth rate are investigated numerically. It is found that finite ion temperature, dust density, dust charge polarity, and spectral index of kappa for nonthermal electrons play a significant role to unstable the modulated DIAW modulated wave. The existence of positively and negatively charged dust particles and their observation in different regions of space plasma and in laboratory experiments is also pointed out.

Collisional effects in negative ion plasmas in the presence of degenerate electrons

Ion acoustic solitary wave structures in negative ion plasmas in the presence of degenerate electrons are investigated. The collisions of positive ions, negative ions, and electrons with neutrals are considered. The Damped Korteweg-de Vries (DKdV) equation is derived by using reductive perturbation method. The time dependent solution of DKdV is presented. Different combinations of the negative ion plasmas in the presence of degenerate electrons are considered for numerical analyses. The effects of variations of different plasmas parameters on the propagation characteristics of the damped solitary wave structure are discussed.