The formation and main properties of a solitary wave with trapped ions, which arises during the collision of two compressive solitary waves in a plasma with negative ions, are investigated. The trapping of ions can develop according to three scenarios, each of which is determined by the corresponding range of initial amplitudes of the colliding waves. The dependence of the number of trapped ions on the initial wave amplitudes is presented. It is shown that a solitary wave with trapped ions can propagate and transport a sufficiently large number of ions over a fairly long period of time, while maintaining its amplitude, propagation velocity, and shape.
Yu. V. Medvedev (Sun,) studied this question.