Abstract

The dispersion relation of an ion-acoustic wave propagating through a collisionless, unmagnetised plasma, having warm isothermal electrons and cold positive and negative ions has been derived. It is seen that the ion-acoustic wave will be unstable in the presence of streaming of ions. Instability of the wave is graphically analysed for the plasma having (H⁺, O¯) ions, (H⁺, O₂¯) ions, (H⁺, SF₅¯) ions, (He⁺, Cl¯) ions and (Ar⁺, O¯) ions with different negative ion concentration and relativistic velocity.