Observations suggest that at altitudes of 1000 − 2000 km the interaction between the solar wind and Venus’ ionospheric plasma leads to ion-acoustic waves (IAWs) formation. For studying this hypothesis, a suitable hydrodynamic model relying on the observational data from Pioneer Venus Orbiter (PVO) and Venus Express (VEX) is developed. It consists of two ionospheric fluids of positive ions, hydrogen (H+) and oxygen (O+), and isothermal ionospheric electrons interacting with streaming solar wind protons and isothermal solar wind electrons. The favourable conditions and propagation characteristics of the fully nonlinear IAWs along with their dependence on solar wind parameters are examined and compared with the available space observations. It is found that the pulse amplitude is decreased by increasing the temperature of either the solar wind protons or electrons. In contrast, a higher relative density or velocity of the solar wind protons amplifies the amplitude of the solitary structures. Moreover, only velocity variations within a certain range called the plasma velocity scale can affect the basic features of the solitary pulses. Beyond this scale, solitary waves are not affected by the solar wind protons’ velocity anymore. This theoretical model predicts the propagation of electrostatic solitary waves with a maximum electric field of 7.5 mV/m and a pulse time duration of 3 ms. The output of the fast Fourier transformation (FFT) power spectra of the electric field pulse is a broadband electrostatic noise in a frequency range of ∼0.1 − 4 kHz. These FFT calculations are in good agreement with PVO’s observations.

A three-dimensional (3D) modulational instability (MI) of dust acoustic waves (DAWs) in a three-component magnetized dusty plasma system consisting of a negatively charged fluid, inertialess generalized (r, q) distributed electrons and Boltzmann distributed ions, is investigated. The basic system of the nonlinear hydrodynamic equations is reduced to a 3D nonlinear Schrödinger equation (NLS) which is valid for small but finite amplitude DAWs using a reductive perturbation technique. The domain of the stability and instability regions is investigated that is strongly affected by the spectral parameters of the generalized (r, q) distribution and the electron-to-ion temperature ratio (T e /T i ). The existence domains for observing the first-and second-order solutions of the dust acoustic rogue waves (DARWs) are determined and the basic features (viz the width and amplitude) for the first-order solution are found to be significantly dependent on the system physical parameters changes such as T e /T i , number density ratio [n e0/(n d0 z d0)] and the dust cyclotron frequency (ω cd ) as well as the spectral indexes r and q. A comparison between the first-and second-order DARW amplitudes is presented. Moreover, another comparison between the first-order DARW amplitudes obtained by generalized (r, q) distributed electrons and those corresponds to Maxwellian is provided. Finally, implication of our consequences in specific plasma situations are briefly discussed.

In this article we investigated the modulation of nonlinear ion acoustic waves in a weakly relativistic, warm, unmagnetized and adiabatic plasma whose constitutes are ion fluid and superthermally distributed electrons using the multiple scales approach. The basic system of equations is reduced to a finite wave number nonlinear Schrödinger-type equation at the second order of the perturbation theory and for small wave number limit the nonlinear Schrödinger-type equation is derived. Moreover the reductive perturbation technique is applied to this system and Korteweg-de Vries equation is obtained. For small wavenumber limit, it is found that the dispersion coefficient and nonlinear coefficient of the nonlinear Schrödingertype equation are reduced to the coefficients of nonlinear Schrödinger-type equation obtained from Korteweg-de Vries (K-dV) equation. The dependence of the phase velocity and the group as well as the domain of the stability and the instability on the temperature ratio, the relativistic factor and the superthermal parameter is investigated.

A reductive perturbation technique (multiple scales) is applied to a weakly relativistic warm unmagnetized adiabatic plasma system consisting of inertial ions fluid and nonextensively distributed electrons. A nonlinear Schrödinger-type (NST) equation for finite wavenumber at the second order is derived. Using the reductive perturbation technique we derived the corresponding Korteweg-de Vries (K-dV) equation. For small wavenumber limit the K-dV equation is transformed into NST equation. It is found that the coefficient of the NST equation obtained from the K-dV equation agree with the corresponding coefficients of NST equation obtained by the multiple scales. Moreover we investigated the effect of the physical parameters of the system namely temperature ratio of the ion temperature T i to electron temperature T e , the relativistic factor u 0 /C as well as the nonextensive parameter (q) of the distribution on the stability/instability of the system. It is found that these parameters affect strongly on the stability/instability regions. Finally, the validity of our results in astrophysical plasma is briefly discussed.

The modulational instability of ion-acoustic waves (IAWs) in a four-component magneto-plasma system consisting of positive–negative ions fluids and non-Maxwellian (r,q) distributed electrons and positrons, is investigated. The basic system of fluid equations is reduced to a three-dimensional (3D) nonlinear Schrödinger Equation (NLS). The domains of the IAWs stability are determined and are found to be strongly affected by electrons and positrons spectral parameters r and q and temperature ratio Tp/Te (Tp and Te are positrons and electrons temperatures, respectively). The existence domains, where we can observe the ion-acoustic rogue waves (IARWs) are determined. The basic features of IARWs are analyzed numerically against the distribution parameters and the other system physical parameters as Tp/Te and the external magnetic field strength. Moreover, a comparison between the first- and second-order rogue waves solution is presented. Our results show that the nonlinearity of the system increases by increasing the values of the non-Maxwellian parameters and the physical parameters of the system. This means that the system gains more energy by increasing r, q, Tp, and the external magnetic field through the cyclotron frequency ωci. Finally, our theoretical model displays the effect of the non-Maxwellian particles on the MI of the IAWs and RWs and its importance in D–F regions of Earth’s ionosphere through (H+,O2−) and (H+,H−) electronegative plasmas.