Large amplitude ion acoustic solitary waves in a plasma consisting of warm ions, twotemperature electrons and a cold electron beam

The traveling solitary wave approximation is employed for the derivation of the Sagdeev-type pseudopotential from a two-fluid model, describing a plasma which consists of warm ions, two-temperature electrons (both Maxwellian) and an electron beam. The conditions for the existence of large amplitude ion acoustic solitary waves are discussed. The effects of parameters like the ion temperature sigma_i, the beam density beta, the densities of the thermal electron populations (beta_c and beta_h) and hot-to-cold-electron temperature ratio mu_e on the existence of solitary waves are investigated. It is found that both positive and negative potential supersonic structures can propagate when the Mach number M satisfies M² ges 3sigma_i, whereas only subsonic negative potential structures can propagate for M² les 3sigma_i. It is shown that the amplitude of supersonic negative potential structures decreases as beta(M) increases for fixed M (fixed beta). On the other hand, it is seen that the amplitude of subsonic negative potential structures increases (remains nearly fixed) as M increases for fixed beta (as beta increases for fixed M).