Head-on collision of ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma

The head-on collision between two ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma has been investigated. By using the extended Poincaré-Lighthill-Kuo perturbation method, we obtain the KdV equation and the analytical phase shift after the head-on collision of two solitary waves in this three-component plasma. The effects of the ratio of electron temperature to positron temperature, and the ratio of the number density of positrons to that of electrons on the phase shift are studied. It is found that these parameters can significantly influence the phase shifts of the solitons. Moreover, the compressive solitary wave can propagate in this system.     

Quantum ion-acoustic solitary waves in weak relativistic plasma

Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized two- species relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects significantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter H on the nature of solitary wave solutions is studied in some detail.     

Head-on collision of quantum ion-acoustic solitary waves in a dense electron-positron-ion plasma

The characteristics of the head-on collision between two-quantum ion-acoustic solitary waves (QIASWs) in a dense electron-positron-ion plasma are investigated. Using the extended Poincaré-Lighthill-Kuo (PLK) method, the Korteweg-de Vries (KdV) equations and the analytical phase shifts, after two QIASWs collision occurs, are derived. This study is a first attempt to illustrate the effects of both of the quantum diffraction corrections and the Fermi temperature ratio of positrons to electrons on the phase shifts. It is found that the electron-positron-ion plasma parameters modify significantly the phase shifts of the two colliding solitary waves.     

Nonlinear ion acoustic solitary waves in electron-positron-ion inhomogeneous plasma

A theoretical investigation has been made for studying the propagation of ion-acoustic waves (IAWs) in a weakly inhomogeneous, collisionless, unmagnetized, three-component plasmas, whose constituents are inertial ions, nonthermal electrons, and Boltzmannian positrons. Employing reductive perturbation method (RPM), the variable coefficients Korteweg-de Varies equation (KdV) is derived. At the critical ion density, the KdV equation is not suitable for describing the system. Thus, a new set of stretched coordinates is considered to derive the modified variable coefficients KdV equation. Above (below) this critical point the system supports compressive (rarefactive) solitons. The effect of plasma parameters on the soliton profile has been considered. It has been shown that the width and the amplitude of the soliton affected by wave propagation speed, ratio of positron-to-electron density, and nonthermal parameter.     

Planar and nonplanar ion-acoustic envelope solitary waves in a very dense electron-positron-ion plasma

Ion-acoustic envelope solitary waves in a very dense plasma comprised of the electrons, positrons and ions are investigated. For this purpose, the quantum hydrodynamic model and the Poisson equation are used. A modified nonlinear Schrödinger equation is derived by employing the reductive perturbation method. The effects of the quantum correction and of the positron density on the propagation and stability of the envelope solitary waves are examined. The nonplanar (cylindrical/spherical) geometry gives rise to an instability period. The latter cannot exist for planar case and it affected by the quantum parameters, as well as the positron density. The present investigation is relevant to white dwarfs.     

Effect of excavated trapped electron distributions on ion-acoustic solitary structures in an electron-positron-ion plasma

Fully nonlinear propagation of ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma is investigated. A more realistic situation is considered in which electrons interact with the wave potential during its evolution and, follow the vortex-like excavated trapped distribution. The basic properties of large amplitude solitary waves are studied by deriving an energy integral equation involving Sagdeev potential. It is shown that effects of such electron behavior and positron concentration change the maximum values of the Mach number and amplitude for which solitary waves can exist. The small amplitude limit is also investigated by expanding the Sagdeev potential to include third-order nonlinearity of electric potential. In this case, exact analytical solution is obtained which is related to the contribution of the resonant electron to the electron density. It is shown from both highly and weakly nonlinear analysis that the plasma system under consideration supports only compressive solitary waves.     

Fully nonlinear ion-acoustic solitary waves in a magnetized plasma

The propagation of fully nonlinear ion-acoustic solitary waves in a magnetized plasma with cold ions and warm electrons is studied analytically. Necessary conditions for the existence of solitary waves in such a plasma were obtained by Yuet al. In this paper necessary and sufficient conditions are found.     

Effect of electron inertia on the speed and shape of ion-acoustic solitary waves in relativistic plasma

Ion-acoustic solitary waves are investigated in a cold collisionless relativistic plasma. Electron inertia is also considered. The Sagdeevs pseudopotential is determined in terms of u, the ion speed and depends on v, the velocity of the wave. It is found that there exists a critical value of u ₁ ( 0), the value of u at which (u)² = 0, beyond which the solitary waves cease to exist. The critical value also depends on the relativistic parameter u ₀/c when u ₀ is the drift velocity of the ion and c is the speed of light.     

Ion acoustic solitary waves in weakly relativistic plasma with nonthermal electron, positron and warm ion

The Korteweg-de Vries equation for a weakly relativistic ion acoustic wave propagating in oollisionless plasma containing nonthermal electron, positron and warm ion is derived. The effects of the ion temperature, nonthermal parameter and relativistic effect on the amplitude, width and energy of soliton are studied.     

Particle-in-cell simulation of ion-acoustic solitary waves in a bounded plasma

We study some nonlinear waves in a viscous plasma which is confined in a finite cylinder.By averaging the physical quantities on the radial direction in some cases,we reduce this system to a simple one-dimensional model.It seems that the effects of the bounded geometry(the radius of the cylinder in this case)can be included in the damping coefficient.We notice that the amplitudes of both Korteweg–de Vries(KdV)solitary waves and dark envelope solitary waves decrease exponentially as time increases from the particle-in-cell(PIC)simulation.The dependence of damping coefficient on the cylinder radius and the viscosity coefficient is also obtained numerically and analytically.Both are in good agreement.By using a definition,we give a condition whether a solitary wave exists in a bounded plasma.Moreover,some of potential applications in laboratory experiments are suggested.     

Dynamics of ion-acoustic rogue waves in electron-positron-ion magneto-plasmas

A more general and realistic four-component magnetized plasma medium consisting of opposite polarity ions and nonthermal distributed positrons and electrons is considered to investigate the stable/unstable frequency regimes of modulated ion-acoustic waves (IAWs) in the D-F regions of Earth's ionosphere. A (3 + 1) -dimensional nonlinear Schrödinger equation, which leads to the modulation instability (MI) of IAWs, is derived. The parametric regimes for the existence of the MI, first- and second-order rogue waves, and also their basic features (viz., amplitude, width, and speed) are found to be significantly modified by the effect of physical plasma parameters and external magnetic field. It is found that the nonlinearity of the different types of electronegative plasma system depends on the positive to negative ion mass ratio. It is also shown that the presence of nonthermal distributed electrons and positrons modifies the nature of the MI of the modulated IAWs. The implication of our results for the laboratory plasma [e.g., (Ar⁺, F⁻ ) electronegative plasma] and space plasma [e.g., (H⁺, H⁻ ), () electronegative plasma in D-F regions of Earth's ionosphere] are briefly discussed.     

Nonlinear adiabatic models of ion-acoustic waves in dust plasma

Nonlinear adiabatic models of ion-acoustic waves in a dust plasma are developed. The problem of the structure of subsonic periodic and supersonic solitary ion-acoustic waves is exactly solved analytically under the assumption of a constant charge of dust particles; the critical Mach numbers for the solitary wave are determined. The problem of the wave structure is solved numerically for the case when the charge of dust particles was assumed to be variable.     

Nonlinear theory of ion-sound waves in a dusty electron-positron-ion plasma

A theory of ion-sound waves in a dusty electron-positron-ion plasma is developed. It is shown in the linear approximation that periodic waves exist in a bounded range of parameters. The expression for the sound velocity is derived and the dependence of the velocity on the space charge of dust particles is analyzed. In the nonlinear theory, the general exact solution is obtained, which is then analyzed using the Bernoulli pseudopotential method. Particular solutions are obtained in the form of nonlinear periodic waves, large-amplitude periodic waves (superlinear waves), and solitary compression and rarefaction waves (solitons).     

Dust ion-acoustic solitary waves in a hot adiabatic magnetized dusty plasma

The basic features of obliquely propagating dust ion-acoustic (DIA) solitary waves in a hot adiabatic magnetized dusty plasma (containing adiabatic inertia-less electrons, adiabatic inertial ions, and negatively charged static dust) have been investigated. The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV) equation which admits a small amplitude solitary wave solution. The combined effects of plasma particle (electron and ion) adiabaticity, ion-dust collision, and external magnetic field (obliqueness), which are found to significantly modify the basic features of the small but finite-amplitude DIA solitary waves are explicitly examined. The implications of our results in space and laboratory dusty plasmas are briefly discussed.     

Effect of electron-ion collision on the ion-acoustic solitary wave in a relativistic plasma

Summary We have considered the effect of electron-ion collision on the structure of the solitary wave in a relativistic unmagnetized plasma. In the present analysis we have considered ions to be cold, the electrons hot. The equation obtained for ion velocity is not the usual KdV type but a perturbed version of it, where the perturbing term is proportional to the electron-ion collision frequency. Lastly we have used the method of Bogoliubov-Mitropolsky to study the change in the solitary-wave profile due to this perturbation.     

Nonlinear propagation of ion-acoustic waves in a degenerate dense plasma

Nonlinear propagation of ion-acoustic (IA) waves in a degenerate dense plasma (with all the constituents being degenerate, for both the non-relativistic or ultrarelativistic cases) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg–de Vries (KdV) equation have been derived, and the numerical solutions of KdV equation have been analysed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly, in white dwarfs and neutron stars, have been briefly discussed.     

Head-on collision of ion acoustic solitary waves in electron-positron-ion plasma with superthermal electrons and positrons

The head-on collision of ion acoustic solitary waves are studied in an electron-positron-ion plasma composed of superthermal electrons, superthermal positrons, and cold ions using the extended Poincaré-Lighthill-Kuo (PLK) method. The effects of the ratio of electron to positron temperature, the spectral index of electron and positron, and the concentration of positron component on the phase shift are studied. It is found that the presence of superthermal electrons and superthermal positrons play a significant role on the collision of ion acoustic solitary waves. It is also been observed that the temperature ratio plays a significant role on the collision of ion acoustic solitary waves.     

二维热离子等离子体中离子声孤波的相互作用

通过使用推广的 Poincar-Lighthill-Kuo 摄动方法,研究了二维热离子等离子体中两个沿不同方向传播的离子声孤波的相互作用,得到了两个分别描述沿ξ和η方向传播的孤波的KdV方程以及两个孤波以任意夹角碰撞后的相移和轨道.同时还研究了离子温度比σ、热容比γ和碰撞夹角α对孤波相移的影响.研究表明,这些参量可以明显地改变孤波的相移,且在该系统中存在压缩型孤波. 关键词： 热离子等离子体 离子声孤波 Poincar-Lighthill-Kuo方法 相移     

Kinetic ion-acoustic solitary waves in collisional plasmas

In this study, a bipolar high-voltage pulse with 20 ns rising time is employed to generate diffuse dielectric barrier discharge plasma using wire-plate electrode configuration in nitrogen at atmospheric pressure. The gas temperature of the plasma is determined by comparing the experimental and the best fitted optical emission spectra of the second positive bands of N₂(C³Π_u → B³ Π_g, 0-2) and the first negative bands of N₂ ⁺ (B² Σ_u ⁺ → X² Σ_g ⁺, 0-0). The effects of the concentration of argon and oxygen on the emission intensities of N₂ (C³Π_u → B³Π_g, 0-0, 337.1 nm), OH?(A ²Σ → X²Π, 0-0) and N₂ ⁺ (B² Σ_u ⁺ → X² Σ_g ⁺, 0-0, 391.4 nm) are investigated. It is shown that the plasma gas temperature keeps almost constant with the pulse repetition rate and pulse peak voltage increasing. The emission intensities of N₂ (C³Π_u → B³Π_g, 0-0, 337.1 nm), OH(A²Σ → X²Π, 0-0) and N₂ ⁺ (B² Σ_u ⁺ → X² Σ_g ⁺, 0-0, 391.4 nm) rise with increasing the concentration of argon, but decrease with increasing the concentration of oxygen, and the influences of oxygen concentration on the emission intensities of N₂(C³Π_u → B³Π_g, 0-0, 337.1 nm) and OH (A²Σ → X²Π, 0-0) are more greater than that on the emission intensity of N₂ ⁺ (B² Σ_u ⁺ → X² Σ_g ⁺, 0-0, 391.4 nm).