Effect of Electron's Drift Velocity in Nonlinear Ion-Acoustic Solitons in a Negative Ion Beam Plasma

In the present paper, the authors have explored the existence of KdV and mKdV solitons in a collisionless and unmagnetized plasma model involving positive ion and negative ion beams together with thermal electrons. For various selections of Q'(= m(b)/m(i), negative ion beam to positive ion mass ratio) larger and less than one, low amplitude rarefactive and compressive KdV solitons are created in the plasma under the effect of the electron's drift velocity v'(e). In two intervals of drift velocity v'(e) for 0 <= v'(e) <= 26 and 26.5 <= v'(e) <= 28.5 when Q' is less than one, the existence of the mKdV solitons is demonstrated.