ION-ACOUSTIC COMPRESSIVE AND RAREFACTIVE SOLITONS IN A WARM MULTICOMPONENT PLASMA WITH NEGATIVE-IONS

Propagation of ion-acoustic solitons in a plasma consisting of warm po sitive and negative ion species with different masses, concentrations, and charge states, along with hot electrons, is studied. It is found that the finite temperatures of two ion species give rise to two types of modes, i.e., a slow ion-acoustic mode and a fast ion-acoustic mode . For all values of negative ion concentration, the slow wave mode sup ports compressive (rarefactive) solitons, when the negative ion specie s has a higher (lower) temperature than the positive ion species. The fast wave mode supports compressive solitons for low concentration of negative ions. At the critical concentration of negative ions both com pressive and rarefactive modified Korteweg-de Vries solitons coexist. Above this critical concentration the system supports rarefactive soli tons. The dependence of the critical concentration on the temperatures of two ion species is also discussed. (C) 1996 American Institute of Physics.