N. A. El-Bedwehy

Nonlinear ion-acoustic structures in dusty plasma with superthermal electrons and positrons

Nonlinear ion-acoustic structures are investigated in an unmagnetized, four-component plasma consisting of warm ions, superthermal electrons and positrons, as well as stationary charged dust impurities. The basic set of fluid equations is reduced to modified Korteweg-de Vries equation. The latter admits both solitary waves and double layers solutions. Numerical calculations indicate that these nonlinear structures cannot exist for all physical parameters. Therefore, the existence regions for both solitary and double layers excitations have been defined precisely. Furthermore, the effects of temperature ratios of ions-to-electrons and electrons-to-positrons, positrons and dust concentrations, as well as superthermal parameters on the profiles of the nonlinear structures are investigated. Also, the acceleration and deceleration of plasma species have been highlight. It is emphasized that the present investigation may be helpful in better understanding of nonlinear structures which propagate in astrophysical environments, such as in interstellar medium.

Three-dimensional stability of dust-ion acoustic solitary waves in a magnetized multicomponent dusty plasma with negative ions

Using the small-k expansion perturbation method, the three-dimensional stability of dust-ion acoustic solitary waves (DIASWs) in a magnetized multicomponent dusty plasma containing negative heavy ions and stationary variable-charge dust particles is analyzed. A nonlinear Zakharov–Kuznetsov equation adequate for describing these solitary structures is derived. Moreover, the basic features of the DIASWs are studied. The determination of the stability region leads to two different cases depending on the oblique propagation angle. In addition, the growth rate of the produced waves is estimated. The increase of either the negative ion number density or their temperatures or even the number density of the dust grains results in reducing the wave growth rate. Finally, the present results should elucidate the properties of DIASWs in a multicomponent plasma with negative ions, particularly in laboratory experiment and plasma process.

Ion-acoustic super rogue waves in ultracold neutral plasmas with nonthermal electrons

The ion-acoustic rogue waves in ultracold neutral plasmas consisting of ion fluid and nonthermal electrons are reported. A reductive perturbation method is used to obtain a nonlinear Schrodinger equation for describing the system and the modulation instability of the ion-acoustic wave is analyzed. The critical wave number kc, which indicates where the modulational instability sets in, has been determined. Moreover, the possible region for the ion-acoustic rogue waves to exist is defined precisely. The effects of the nonthermal parameter β and the ions effective temperature ratio σ∗ on the critical wave number kc are studied. It is found that there are two critical wave numbers in our plasma system. For low wave number, increasing β would lead to cringe kc until β approaches to its critical value βc, then further increase of β beyond βc would enhance the values of kc. For large wave numbers, the increase of β would lead to a decrease of kc. However, increasing σ∗ would lead to the reduction of kc for all v...

Effect of second ion temperature on modulation stability of dust-acoustic solitary waves with dust charge variation

The derivative expansion perturbation method is applied to a cold plasma system consisting of dust grains with varying dust charge, electrons, and two species of ions with different temperatures. The basic system of equations is reduced to a nonlinear Schrodinger-type equation. The effect of the temperature of low temperature ions on the system parameters, e.g., angular frequency, group velocity, dispersion coefficient, and nonlinear coefficient, is investigated. It is found that the presence of low-temperature ions enhances the stability of the system. The small wave number limits of the coefficients of the nonlinear Schrodinger-type equation are found to agree exactly with the coefficients of the nonlinear Schrodinger-type equation obtained from the oscillatory solution of the Korteweg-de Vries equation of the system.

Evolution of rogue waves in dusty plasmas

The evolution of rogue waves associated with the dynamics of positively charged dust grains that interact with streaming electrons and ions is investigated. Using a perturbation method, the basic set of fluid equations is reduced to a nonlinear Schrodinger equation (NLSE). The rational solution of the NLSE is presented, which proposed as an effective tool for studying the rogue waves in Jupiter. It is found that the existence region of rogue waves depends on the dust-acoustic speed and the streaming densities of the ions and electrons. Furthermore, the supersonic rogue waves are much taller than the subsonic rogue waves by ∼25 times.

Large amplitude solitary waves in a warm magnetoplasma with kappa distributed electrons

The large amplitude nonlinear ion acoustic solitary wave propagating obliquely to an external magnetic field in a magnetized plasma with kappa distributed electrons and warm ions is investigated through deriving energy-balance-like expression involving a Sagdeev potential. Analytical and numerical calculations of the values of Mach number reveal that both of subsonic and supersonic electrostatic solitary structures can exist in this system. The influence on the soliton characteristics of relevant physical parameters such as the Mach number, the superthermal parameter, the directional cosine, the ratio of ion-to-electron temperature, and the ion gyrofrequency has been investigated.

Nonlinear structures: Cnoidal, soliton, and periodical waves in quantum semiconductor plasma

Properties and emerging conditions of various nonlinear acoustic waves in a three dimensional quantum semiconductor plasma are explored. A plasma fluid model characterized by degenerate pressures, exchange correlation, and quantum recoil forces is established and solved. Our analysis approach is based on the reductive perturbation theory for deriving the Kadomtsev-Petviashvili equation from the fluid model and solving it by using Painleve analysis to come up with different nonlinear solutions that describe different pulse profiles such as cnoidal, soliton, and periodical pulses. The model is then employed to recognize the possible perturbations in GaN semiconductor.

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,...

Ion thermal double layers in a pair-ion warm magnetized plasma containing charged dust impurities

In this paper the formation and the dynamics of ion thermal double layers (ITDLs) in a magnetized plasma, composed of positive and negative ions as well as a fraction of stationary charged (positive or negative) dust impurities have been studied. Using plasma hydrodynamics and Poisson equations for the two ion species, a modified Zakharov–Kuznetsov equation has been derived. The effects of the external magnetic field, the concentration of charged dust impurities, and the negative to positive ion temperature ratio on the ITDLs structure are investigated.

Higher-order contribution to dust-ion acoustic dressed solitons in a warm dusty plasma

Propagations of ion-acoustic dressed solitons in an unmagnetized dusty plasma consisting of a mixture of hot nonisothermal electrons, warm ions, and high negatively charged warm dust particles have been investigated. The reductive perturbation theory has been employed. At the lowest order of the perturbation theory a modified Korteweg–de Vries equation is obtained. At the next order of the perturbation theory, a linear inhomogeneous equation is obtained. Using the renormalization procedure introduced by Kodama and Taniuti, a stationary solution of the coupled equations has been obtained.