Abstract
Ion-acoustic solitons in a collisionless plasma with adiabatic positive and negative ions with equal ion temperature and isothermal electrons are studied by using the reductive perturbation method. The basic set of fluid equations is reduced for the fast ion-acoustic wave to the Korteweg–de Vries and modified Korteweg–de Vries equation and for the slow ion-acoustic wave to the Korteweg–de Vries equation. Stationary solutions of these equations are obtained and the effect of ion temperature on fast and slow ion-acoustic solitons is investigated.