Nonlinear acoustic waves in nonthermal dusty or pair plasmas

Abstract

Using a Sagdeev pseudopotential formalism where nonlinear structures are stationary in a comoving frame, large dust-acoustic solitary waves and double layers have been studied in plasmas with negative cold dust or heavier ions, in the presence of nonthermal electrons and protons/positrons. The existence domain of negative solitary waves is limited by infinite compression of the negative dust or heavy ion species, that of positive solitary waves by the occurrence of positive double layers. These double layers require a sufficient degree of nonthermality of the hot species. There are parameter ranges where both negative and positive solitary structures can occur; sometimes both of the solitary wave type or sometimes one solitary wave and the other a double layer. Great emphasis is placed on the determination of the existence domains in compositional parameter space, with the help of strong analytical results, before typical Sagdeev pseudopotentials and solitary wave profiles are presented. Subject to simple adjustments, these results apply equally to a conjugate plasma model of positive dust or heavy ions, together with nonthermal electrons and protons/positrons.