Effect of Cairns–Gurevich polarization force on dust-acoustic solitons in collisionless dusty plasmas

Abstract

A first theoretical attempt is made to investigate the effects of the trapped nonthermal polarization force on dust-acoustic solitons in collisionless dusty plasmas. For this purpose, a three-dimensional Cairns–Gurevich distribution, that describes, simultaneously, the evolution of the energetic ions and those trapped in the plasma potential well, is revisited, and, consequently, both density and polarization force expressions are derived. The effects of the polarization force are sensibly modified due to the presence of the trapped nonthermal ions. In particular, we have found that, for both experimental and space dusty plasmas, the polarization force magnitude decreases as the relative fraction of the nonthermal ions increases. The changes arising in both linear and nonlinear dust-acoustic (DA) solitons propagation due to the presence of these trapped nonthermal density and polarization force are also analyzed. We have shown that due to the polarization force acting on the dust grains, the effect of the ion nonthermality is boosted. Besides, we have found that an increase in polarization force magnitude leads to an increase in the amplitude and width of DA solitons.