Abstract
The quasi-stationary solitons for Langmuir waves in plasmas is obtained in this paper. This model is governed by the perturbed nonlinear Schrodinger's equation with cubic and power law nonlinearities. The perturbation terms are considered with full nonlinearity. A new generalized definition of the phase of the soliton is introduced. This leads to additional information at higher order level which soliton perturbation theory fails to capture.