arbitrary amplitude ion acoustic wave in a pair ions and electron plasma with trapped electrons

Propagation of ion acoustic solitary waves (iasws) in electronegative plasma containing positive and negative ions, trapped and non-thermal electrons are investigated. using the sagdeev pseudopotential method and investigation of the energy integral, the existence of propagation regions for these waves is analyzed. it is shown that the mach number, positive and negative ions densities ratio and the trapping parameter can lead to change the pseudopotential amplitude and also it is shown that the lower limit of the mach number increases with the density and mass ratios of positive and negative ions, but the upper limit of the mach number does not depend on the densities ratio. the results show that for this kind plasma, there is only compressive iasw. this research will be helpful in understanding of physical phenomena concerned in plasmas in which the effects of trapped electrons control the dynamics of wave.