Dust ion acoustic solitary structures in presence of isothermal positrons

TL;DR

This paper investigates dust ion acoustic solitary waves and double layers in a dusty plasma with electrons and positrons, revealing conditions for various solitary structures including supersolitons and the effects of positron concentration.

Contribution

The study develops a computational scheme to map solution spaces, identifying conditions for the existence of different solitary structures and supersolitons in dusty plasma with positrons.

Findings

Negative potential double layers restrict negative solitary waves.

Positive potential double layers can coexist with supersolitons.

Very hot positrons have negligible effect at low concentrations.

Abstract

The Sagdeev potential technique has been employed to study the dust ion acoustic solitary waves and double layers in an unmagnetized collisionless dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions, and isothermally distributed electrons and positrons. A computational scheme has been developed to draw the qualitatively different compositional parameter spaces or solution spaces showing the nature of existence of different solitary structures with respect to any parameter of the present plasma system. The qualitatively distinct solution spaces give the overall scenario regarding the existence of different solitary structures. The present system supports both positive and negative potential double layers. The negative potential double layer always restricts the occurrence of negative potential solitary waves, i.e., any sequence of negative potential solitary waves having monotonically increasing amplitude converges to a negative potential double layer. However, there exists a parameter regime for which the positive potential double layer is unable to restrict the occurrence of positive potential solitary waves. As a result, in this region of the parameter space, there exist solitary waves after the formation of positive potential double layer, i.e., positive potential supersolitons have been observed. But the amplitudes of these supersolitons are bounded. A general theory for the existence of bounded supersolitons has been discussed analytically by imposing the restrictions on the Mach number. For any small value of positron concentration, there is no effect of very hot positrons on the dust ion acoustic solitary structures. The qualitatively different solution spaces are capable of producing new results for the formation of solitary structures.