Dust-acoustic solitary waves in a magnetized dusty plasma with nonthermal electrons and trapped ions

摘要

The nonlinear propagation of electrostatic dust-acoustic (DA) waves in amagnetized dusty plasma consisting of negatively charged mobile dusts,nonthermal fast electrons and trapped ions with vortex-like distribution isstudied. Using the reductive perturbation technique, a Korteweg-de Vries(KdV)-like equation is derived which governs the dynamics of thesmall-amplitude solitary waves in a magnetized dusty nonthermal plasma. It isfound that due to the dust thermal pressure, there exists a critical value$(\beta_c)$ of the nothermal parameter $\beta~(>1)$, denoting the percentage ofenergetic electrons, below which the DA solitary waves cease to propagate. Thesoliton solution (travelling wave) of the KdV-like equation is obtained, and isshown to be only of the rarefactive type. The properties of the solitons areanalyzed numerically with the system parameters. It is also seen that theeffect of the static magnetic field (which only modifies the soliton width)becomes significant when the dust gyrofrequency is smaller than one-tenth ofthe dust plasma frequency. Furthermore, the amplitude of the soliton is foundto increase (decrease) when the ratio of the free to trapped ion temperatures$(\sigma)$ is positive (negative). The effects of the system parametersincluding the obliqueness of propagation $(l_z)$ and $\sigma$ on the dynamicsof the DA solitons are also discussed numerically, and it is found that thesoliton structures can withstand perturbations and turbulence during aconsiderable time. The results should be useful for understanding the nonlinearpropagation of DA solitary waves in laboratory and space plasmas (e.g., Earth'smagnetosphere, auroral region, heliospheric environments etc.).