Electrostatic solitary structures in dusty plasmas with nonthermal and superthermal electrons

A theoretical model is presented to show the existence, formation, and possible realization of arbitrary amplitude solitary potentials in a dusty plasma with both nonthermal and superthermal electrons. A physically meaningful κ-like electron distribution function is outlined. It is shown that due to electron superthermality, the present dusty plasma model can support subsonic as well as supersonic electrostatic solitary waves involving cusped potential humps. Interestingly, one finds that the effect of increasing the spectral index κ is to reduce and restrict the domain of allowable dust Mach numbers. An increase of the nonthermal parameter α would lead to a shift of this domain and a drastic restriction of the spectral index regime in which compressive and rarefactive solitons can coexist. Our results may provide an explanation for the strong spiky waveforms observed in auroral electric fields measurements by Viking and Fast.