Solitary ion acoustic waves in a plasma with regularized κ-distributed electrons

This work has been focused on the investigation of the existence conditions and the characteristics of ion acoustic soliton (IAS) in a plasma, which is composed of cold ions and regularized κ-distributed electrons. It is found that the propagation speed of the IAS should be larger than the actual ion acoustic velocity in the model. When the superthermal spectral index κ > 1.5, there exists IAS with only positive potential. In that case, the impact of the cutoff parameter α on the IAS is rather small. When κ < 1.5, however, the properties of IAS will exhibit a completely different behavior. The most significant change is that there will be IAS with negative potential if κ is small enough. The value of κ for the presence of the negative potential IAS decreases with the increase in α. The width of the IAS is determined by the Mach number, the superthermal index κ, and the cutoff parameter α. In addition, there is no singularity for the existence conditions of the IAS in the whole range κ > 0. It indicates that the regularized κ-distribution introduced by Scherer et al. (2017) can be relevant to the fluid description of the nonthermal plasma. The results obtained in the present study might be useful for the understanding of the nonlinear electrostatic phenomena in space plasmas.