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Propagation of large amplitude dust-acoustic (DA) solitary waves is investigated in electronpositron-ion plasmas in the presence of dust grains using Sagdeev potential method. It is shown that acceptable values of Mach number for propagation of the large amplitude DA solitary waves depend strongly on plasma parameters. It is also observed that the amplitude of DA solitary waves increases as both the Mach number M and dust charge Z d are increased. Furthermore, it is found that a dusty plasma with inertial dust fluid and Boltzmann distributed electrons, positrons, and ions admits only negative solitary potentials associated with nonlinear dust-acoustic waves. In addition, it is remarked that the formation of double layers is not possible in this plasma system. V C 2012 American Institute of Physics. [http://dx.

The propagation of ion-acoustic (IA) solitons is studied in a plasma system, comprised of warm ions and superthermal (Kappa distributed) electrons in the presence of an electron-beam by using a hydrodynamic model. In the linear analysis, it is seen that increasing the superthermality lowers the phase speed of the IA waves. On the other hand, in a fully nonlinear investigation, the Mach number range and characteristics of IA solitons are analyzed, parametrically and numerically. It is found that the accessible region for the existence of IA solitons reduces with increasing the superthermality. However, IA solitons with both negative and positive polarities can coexist in the system. Additionally, solitary waves with both subsonic and supersonic speeds are predicted in the plasma, depending on the value of ion-temperature and the superthermality of electrons in the system. It is examined that there are upper critical values for beam parameters (i.e., density and velocity) after which, IA solitary waves could not propagate in the plasma. Furthermore, a typical interaction between IA waves and the electron-beam in the plasma is confirmed.

Abstract:The occurrence and propagation of large amplitude dust-acoustic solitary waves (DASWs) are studied in a three-component plasma consisting of negatively charged dust grains and electron-positron pairs by employing a pseudopotential technique. Here, we focus on a superthermal plasma modeled by a -like distribution and consider a finite temperature for dust particulates. It is shown that the solitary waves with negative polarity are allowed in the system and there is a critical value for dust charge Z d above/below which the subsonic/supersonic solitary structures can propagate. In the case of negative fullerene ions, Z d = 1, it is observed that subsonic DASWs can propagate in the plasma. In addition, it is revealed that the propagation of double layers is not possible in this plasma system.

The electrostatic (ES) oscillations, spatio-temporal Landau damping and growth in an electron-ion (EI) plasma is investigated by taking into account the effect of ion (electron) dynamics on the electron (ion) oscillations in the context of nonextensive particle distributions. The dispersion relation is exactly solved without employing approximations on the phase velocity, in contrast to the procedure developed by Landau where some approximations are applied on the phase velocity. This enables us to obtain some results which are not shown previously duo to approximate numerical and analytical studies. It is remarked that four kinds of ES modes; a high frequency mode (well-known Langmuir wave), two low and high intermediate frequency (LIF and HIF) modes and a very low frequency mode (well-known IA wave) may propagate in desired plasma system. In particular, these ES modes represent very different behavior when moving to left and right directions, from the point of view of spatio-temporal damping and growth. In addition, it is shown that exact solution of the dispersion relation gives rise to some interesting phenomena; such as the existence of non-acoustic electron and ion modes, the frequency and wavelength cutoffs and the existence of backward waves.