Study On Characteristic Of Some Acoustic Solitary Waves In Plasmas

The physics of plasma is a newly subject which develops rapidly. Plasma exists widely in the universe and the main areas of activity for the human being. The study of plasma is very important for the nonlinear physics. Solitary wave, which is a special coherent structure, describes a kind of stable nature wave phenomena. Nowadays, the study of solitary waves in plasma is one of the hot topics.In this paper, by using reductive perturbation technique, we studied the characteristic of some acoustic solitary waves in plasma. There are mainly four sections in this paper.In chapter one, the plasma, dusty plasma and the discovery and development of solitary wave had been introduced briefly.In chapter two, the (3+1) dimensional weakly nonlinear ion acoustic wave at higher order transverse perturbations in plasma was discussed and described by the Kadomtsev-Petviashvili (KP) equation. It shows that the solitary wave solutions exists in x direction of velocity, density and voltage of ion acoustic wave, even though dispersion presents along the vertical directions. However, the velocity components never presents solitary wave structures along the other vertical directions. Using the Hirota method, a single soliton solution and a double soliton solution for (3+1) dimensional KP equation were also obtained.In chapter three, we derived a KP equation for unmagnetized, hot, collisionless, and two-ion-temperature plasma with isothermal ions and adiabatic dusty fluid. It suggests that the nonlinear dust acoustic solitary waves in this dusty plasma are stable even at some higher order transverse perturbations. The temperature of dust grains, low temperature and high temperature ions and the number densities of the ions influence the property of dust acoustic waves.In chapter four, a dusty plasma with many different species of dust grains was studied and a nonlinear Schrodinger equation (NLSE) was derived which governed the modulation of dust acoustic waves. It shows that, for a power law distribution dusty plasma, the temperature, number densities of ions and electrons have important effect on the modulational instability for dust acoustic waves.