Abstract:
In this thesis we discuss non-linear effects in multi-component plasmas. Different types of
solitary waves and soliton, are the main focus in this work. First of all we consider magneto sonic soliton propagating in external magnetic field in Electron-Positron-Ion plasma, using the
effective one fluid MHD model. Two modes for the waves are discussed in the linear
approximation by using the reductive perturbation scheme for these modes in the nonlinear
regime. It is observed that for both the modes the angle, positron concentration, ion temperature,
affect the propagation properties of solitary waves and are from those of the simple Electron-Ion
plasmas. IAW is a low frequency electrostatic wave, which is supported by the ion inertia in
plasma physics. Due to the compressions and rarefaction of ion number density these low
frequency waves propagate in plasma. In the third chapter we investigate the linear and nonlinear
properties of the IAW. The Zakharov-Kuznetsov equation is derived by employing again the
reductive perturbation technique for this wave in the small amplitude nonlinear regime. This
equation admits solitary wave solution. The amplitude and width of this solitary wave have been
discussed with effects of obliqueness, relativity, ion temperature, positron concentration,
magnetic field and rotation of the plasma. The distribution function decreases generally as a
power law of the velocity instead of an exponential decrease associated with a Maxwellian
distribution. A useful distribution to model plasma containing super thermal and super thermal
particles is the generalized Lorentzian, or kappa, distribution function. The effect of particle
trapping on the linear and nonlinear evolution of an ion acoustic wave in electron-ion plasmas
has been discussed. The generalized KdV equations with associated solitary wave solutions for
different ranges of parameter are derived by employing a perturbation technique. Dust acoustic
wave on a very slow time scale of dust dynamics emerges as a result of the balance between dust
grain inertia and plasma pressure. In chapter 4,The reductive perturbation method is used to drive
Zakharov-Kuznetsov equation in relativistic, rotating, and magnetized electron-positron-ion non linear plasma. ZK equation acknowledge the solution of solitary wave.