Classification of head-on collisions of ion-acoustic solitary waves in a plasma consisting of cold ions and Boltzmann electrons

The classification of head-on collisions of ion-acoustic solitary waves in a collisionless plasma consisting of cold ions and Boltzmann electrons is proposed. Based on the analysis of the results of numerical experiments performed using the particle-in-cell method, five possible collision scenarios are determined. The scenarios differ from each other in that each of the colliding solitary waves either preserves or does not preserve its identity after the collision, depending on the initial (before the collision) amplitudes of both of the solitary waves. The classification can be represented in the diagram of the initial amplitudes, in which each point corresponds to the collision of solitary waves with amplitudes determined by the coordinates of this point. In this diagram, for each scenario, it is possible to determine such a region that all points of this region correspond to collisions in this scenario. The classification distributes all possible head-on collisions of solitary waves in five scenarios, for each of which the corresponding region of initial amplitudes of the colliding solitary waves is established. The classification allows us to predict the scenario of a head-on collision of solitary waves by the known values of their amplitudes before the collision.