Bright and dark envelope solitons in negative-ion plasmas in the presence of Maxwellian electrons population

Using the Krylov–Bogoliubov–Mitropolsky (KBM) perturbation method, a nonlinear Schrödinger (NLS) equation describing the slow modulation of the wave amplitude of the ion-acoustic wave is derived for the system. We have considered a collisionless plasma consisting of two cold-ion species with different masses, concentrations, and charge states and hot-isothermal electrons. The steady state solution of the nonlinear Schrödinger (NLS) equation is...