Ion acoustic solitons in finite ion temperature inhomogeneous plasmas having negative ions

Analytical investigations are carried out for ion acoustic soliton propagation in a spatially inhomogeneous plasma having finite temperature negative and positive ions. The soliton characteristics are described by a Korteweg--de Vries equation which has additional terms. Rarefactive solitons are possible in the negative ion containing plasma, and their existence is decided by the nonlinearity coefficient of this equation. The soliton amplitude decreases for higher-density gradients, but it increases with the increasing ratio of negative-to-positive ion density. Effect of temperature and drift velocity, of both the positive and negative ions on soliton propagation, has been analyzed