Parametric study of a Schamel equation for low-frequency dust acoustic waves in dusty electronegative plasmas.

In this paper, our attention is first concentrated on obliquely propagating properties of low-frequency (ω ≪ ω_cd) "fast" and "slow" dust acoustic waves, in the linear regime, in dusty electronegative plasmas with Maxwellian electrons, kappa distributed positive ions, negative ions (following the combination of kappa-Schamel distribution), and negatively charged dust particles. So, an explicit expression for dispersion relation is derived by linearizing a set of dust-fluid equations. The results show that wave frequency ω in long and short-wavelengths limit is conspicuously affected by physical parameters, namely, positive to negative temperature ion ratio (β_p), trapping parameter of negative ions (μ), magnitude of the magnetic field B₀ (via ω_cd), superthermal index (κ_n,κ_p), and positive ion to dust density ratio (δ_p). The signature of the penultimate parameter (i.e., κ_n) on wave frequency reveals that the frequency gap between the modes reduces (escalates) for k<k_cr (k>k_cr), where kcr is critical wave number. Alternatively, for weakly nonlinear analysis, reductive perturbation theory has been used to construct 1D and 3D Schamel Korteweg-de Vries (S-KdV) equations, whose nonlinearity coefficient prescribes only compressive soliton for all parameter values of interest. The survey manifests that deviation of ions from Maxwellian behavior leads intrinsic properties of solitary waves to be evolved in opposite trend. Additionally, at lower proportion of trapped negative ions, solitary wave amplitude mitigates, whilst the trapping parameter has no effect on both spatial width and the linear wave. The results are discussed in the context of the Earth's mesosphere of dusty electronegative plasma. [ABSTRACT FROM AUTHOR]