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The nonlinear characteristics of dust acoustic (DA) waves in an unmagnetized collisionless complex plasma containing adiabatic electrons and ions and negatively charged dust grains (including the effects of modified polarization force) are investigated. Employing the reductive perturbation technique, a Korteweg–de Vries–Burgers (KdVB) equation is derived. The analytical solution for the KdVB equation is discussed. Also, the bifurcation and phase portrait analyses are presented to recognize different types of possible solutions. The dependence of the properties of nonlinear DA waves on the system parameters is investigated. It has been shown that an increase in the value of the modified polarization parameter leads to a fast decay and diminishes the oscillation amplitude of the DA damped cnoidal wave. The relevance of our findings and their possible applications to laboratory and space plasma situations is discussed.

The linear and nonlinear properties of gravitoelectrostatic mode, in a plasma system consisting of inertial opposite polarity charged dust grains as well as inertialess nonextensively q-distributed ions and electrons (including the effect of polarization force on the massively charged dust grains), have been investigated. A general dispersion relation has been derived yielding only one eigen wave mode. It is found that the polarization force and the nonextensively distributed ions effects play directly a destabilizing role in Jeans instability. Moreover, a new pair of gravitoelectrostatically coupled energy integral equation has been obtained by applying the Sagdeev pseudopotential technique. Also, a small-amplitude approximation is considered for the self-gravitational potential. It is reported that the fluctuations dynamics of the dust grains evolve self-gravitational rarefactive soliton pulses and electrostatic compressive soliton-like patterns. Applying the phase plane analysis, the phase portraits of the dynamical system have been presented and also the corresponding wave solutions. Our results could be applicable for different space and astrophysical plasma systems, particularly for dust molecular clouds of H-II region.

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