Nonlinear dust-acoustic waves in a non-Maxwellian multi-component plasma with streaming ions

Abstract

Abstract Nonlinear dust-acoustic waves (DAWs) is investigated in a six-component plasma consisting of negative dust grains, inertialess suprathermal ions and electrons, interacting with streaming protons and both Maxwellian and non-Maxwellian electrons. Using the reductive perturbation method, the governing equations are reduced to a Korteweg–de Vries (KdV) equation. It is found that, at the critical ion density ratio, the KdV equation is not appropriate for describing the plasma system. Therefore, we use a new stretched coordinate to derive the modified KdV (mKdV) equation. It is found that the presence of the solar wind proton density ratio not only significantly alters the basic features of the nonlinear structure, but also changes the polarity of the pulse. In the vicinity of the critical ion density ratio, neither the KdV nor the mKdV equation is sufficient for describing the DAWs. Therefore, we derived the further modified KdV (fmKdV) equation to obtain a sufficient description for the DAWs. Solitary and double-layer (DL) solutions are obtained for the evolution equations. The results are applied to interpret dust-acoustic fluctuations in Saturn’s magnetosphere, which arise due to interactions between the magnetospheric dust grains and the solar wind particles. It is observed that solitary waves exhibit electric field amplitudes in the range of approximately (0.4–1.5) mV/m, with durations of about (4–8) s and frequency (8 − 10) Hz. Whereas, the DL structure shows stronger fields (1−6.3) mV/m, with durations of approximately (3−6) s, and frequency (8 − 15) Hz. Furthermore, an increase in the superthermal ion parameter κi enhances the amplitudes of the solitary and DL pulses. Increasing the electron temperature ratio σe reduces both the solitary and DL amplitudes. Variations in the solar wind streaming velocity Vs0 and temperature ratios on soliton amplitudes have negligible effects ..........