Ion acoustic solitary structures in a magnetized nonthermal dusty plasma

Abstract

The Sagdeev potential technique has been used to investigate the arbitrary amplitude ion acoustic solitary structures in a collisionless magnetized dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions and nonthermal electrons. The present system supports both positive and negative potential solitary waves, the coexistence of solitary waves of both polarities, and negative potential double layers. The system does not support any positive potential double layer. Although the system supports negative potential double layers, these double layer solutions cannot restrict the occurrence of all solitary structures of same polarity. In fact, there exists a parameter regime for which the negative potential double layer is unable to restrict the occurrence of negative potential solitary waves, and in this region of the parameter space, there exist negative potential solitary waves after the formation of a negative potential double layer. Consequently, negative potential supersolitons have been observed and the Mach number M corresponding to a negative potential supersoliton is restricted by the inequality MNPDL < M < Mcr, but this supersoliton structure reduces to a conventional solitary wave of same polarity if M ≥ Mcr, where MNPDL is the Mach number corresponding to a negative potential double layer and Mcr is a critical value of M. Thus, we have seen a transition process of negative potential solitary structures, viz., soliton → double layer → supersoliton → soliton. Different solitary structures have been investigated with the help of compositional parameter spaces and the phase portraits of the dynamical system describing the nonlinear behaviour of ion acoustic waves. The mechanism of transition of a negative potential supersoliton to a conventional soliton after the formation of a double layer of same polarity has been discussed with the help of phase portraits.