Ionic thermal effects on ion-acoustic waves in plasmas with negative ions

Ion-acoustic waves in warm-ion plasma which includes some negative ions are studied using the properties of a modified Korteweg-de Vries equation. The equation, which describes the amplitude, width and velocity variation of the solitons is studied, taking into account the ion thermal effects. As in the case of a cold plasma, the warm negative ions also introduce a critical concentration at which the wave breaks up, which could play an important role in exploiting the ion-heating mechanism. The results obtained are compared with those for plasmas with cold ions.