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 also discussed, which support bright and dark envelope solitons. The conditions for the existence of two types of localized envelope (Bright/dark) structures are investigated in terms of relevant parameters. We have discussed the characteristic of bright and dark envelope solitons in three plasmas compositions with (H+, O2−), (H+, H−), and (Ar+, F−). The dispersive and nonlinearity coefficients are obtained in terms of various plasma parameters. The range of parameters is investigated numerically in which system supports bright/-dark envelope solitons, and it is shown that envelope solitons exist in negative-ion plasma. The finding of the present study may be useful to understand some aspects of bright/dark envelope solitary waves in astrophysical negative-ion plasmas.