Coupling of acoustic and drift modes, harmonic modons in astrophysical dusty plasma and a new mode in the Comet Halley

TL;DR

This paper presents a theoretical study of acoustic and drift wave coupling in dusty plasmas, revealing new nonlinear vortex structures and a novel mode in comet Halley with potential space and laboratory applications.

Contribution

It introduces new nonlinear vortex solutions in dusty plasma waves and identifies a previously unreported mode in comet Halley plasma unaffected by dust presence.

Findings

Coupling of dust-modified ion acoustic and drift waves analyzed.

Formation of vortex-like structures in nonlinear regimes.

Discovery of a new mode in comet Halley plasma unaffected by dust.

Abstract

This manuscript, presents a theoretical study of the linear and nonlinear characteristics of acoustic and drift waves in a bounded inhomogenious dusty plasma which has potential applications in space and lab environments. In this analysis, flow of all plasma particles is assumed to be along the axial direction whereas gradients in velocity are considered to be along the radial direction. First we study coupling of dust modified ion acoustic (DMA) and drift (DMD) waves (linear analysis) at fast time when dynamics of dust remain inactive, later formation of nonlinear vortex like structures are examined. In the second case at slow time when dust participates in dynamics, coupling between ultra low frequency dust acoustic (UDA) and dust drift (ULD) waves is studied and modons like solutions are obtained in the nonlinear analysis. Existence of the vortex solution with azimuthal harmonics higher than the dipole vortex has been studied both analytically and numerically. Later we extend our analysis to consider applications of dust particle's presence in the comet Halley and tropical mesospheric dusty plasma where in earlier case we report that that unexpectedly comet Halley plasma admits a new mode where presence of dust in background does not have any affect, this mode is similar to the convective cell mode where electrostatic drift (ExB) cancels out, density gradients also vanish due to the presence of negative ions and only polarization drift contributes to the mode. For the linear analysis of this mode, there is no coupling observed but this the convective cell mode evolves whereas nonlinear dynamics of this mode are found to obey the vortex-like solution.