الفهرس 
Introduction
What is plasmaOnly 14 pages are availabe for public view
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Abstract
In this thesis di.erent techniques have been applied to solve some nonlinear plasma problems using macroscopic plasma equations. The reductive perturbation theory has been applied to derive di.erent forms of KdeV and KdeVtype equation . Lisak technique leads the system of equations to a single nonlinear partial di.erential equation which contains the higherorder nonlinearity and dispersion. Lie point symmetry has been used to study the nonlinear partial differential equation produced by Lisak technique to reduce it to non linear di.erential equation. It has been shown that : The structure of Lie point symmetry of the KdeV equation only is more general than that of KdeV and KdeVtype equation since KdeVtype equation becomes a constraining equation for the KdeV equation. The traveling wave solution is the only one make the master equation invariant and gives soliton solution. The stability of plasma must be studied by phase portrait of the dynamical system corrosponding to each problem. the perturbed master equation gives soliton solutions up for higher order of perturbation theory. 154