Hybrid (Vlasov-fluid) simulation of ion-acoustic solitonic chain formation in plasmas with super-thermal electrons

Abstract

Nonlinear decay of a localized perturbation into ion-acoustic solitons in the presence of both trapped and super-thermal electrons (Abbasi et al 2008 Plasma Phys. Control. Fusion 50 095007) is revisited. The motivation is to present a benchmark by introducing a more precise model, the hybrid (Vlasov-fluid) model. In this way, it is possible to address the restrictions that a simple modified Korteweg de–Vries (mKdV) model has. For instance, the lack of vital information in phase space associated with the evolution of electron velocity distribution, its perturbative nature which limits it to weak nonlinear case, and special spatio-temporal scaling based on which the mKdV is derived. From these points of view, the hybrid model is a more convenient model that can be extended to more complex situations. Remarkable differences between the results of the two models lead us to conclude that the mKdV model can only monitor the general aspects of the dynamics, and the precise picture, including the correct spatio-temporal scales and the properties of solitons, should be studied within the framework of hybrid model.