Mostafa Mehdipoor - Faculty of Science, Gonbad Kavous University, Gonbad Kavous, Iran

Ion-acoustic (IA) solitons in a collisionless pair-ion plasma consisting of positive and negative ions and superthermal electrons are studied by using the reductive perturbation method.The basic set of fluid equations is reduced to Korteweg-de Vries (K-dV) equation. It is found that both compressive and rarefactive solitons can propagate in this system. Also, the effectsof spectral index kappa, negative to positive ion density ratio and mass ratio of positive tonegative ions on IA solitons structure are also discussed. Our results may be useful in investigation ion acoustic solitary waves both in space and in laboratory experiments plasmas where two distinct groups of ions and superthermal electrons are present.

ion-acoustic waves; negative ion plasmas; superthermal electrons; k-dv equation