Parveen BalaManpreet Kaur2019-04-222019-04-222019http://krishikosh.egranth.ac.in/handle/1/5810100816Solitary waves are nonlinear and localized structures which arise when there is balance between nonlinearity and dispersion. In the present study, the effects of non-thermal and non-extensive distribution of electrons on the soliton propagation in plasma system containing Boltzmann positrons have been studied. The given distribution is applicable to this study to a limited range of values of q and α, 0.6< q≤ 1 and 0≤ α< 0.25. Using Reductive Perturbation method, Korteweg-de Vries (K-dV), modified K-dV (mK-dV) and Gardner equations are derived for electron-positron-ion (e-p-i) plasma system. The soliton solution of the Gardner equation is discussed in detail. Results have been interpreted in the form of graphs. It is found that for a given set of parameter values, there exists a critical value of q (i.e, qc) below which only rarefactive K-dV solitons exist and above it compressive K-dV solitons exist. However, at the critical value of q, both compressive and rarefactive mK-dV solitons co-exist. In this region, for q > qc, rarefactive Gardner solitons and for q < qc, compressive Gardner solitons are found. The present investigation may help us to understand the electrostatic perturbations in laboratory and space plasmas.ennullThesis