Nonlinear wavepackets in pair-ion and electron-positron-ion plasmas

The occurrence of amplitude-modulated electrostatic and electromagnetic<br/>wavepackets in pair plasmas is investigated. A static additional charged background species is considered, accounting for dust defects or for heavy ion<br/>presence in the background. Relying on a two-fluid description, a nonlinear<br/>Schrodinger type evolution equation is obtained and analyzed, in terms of the<br/>slow dynamics of the wave amplitude. Exact envelope excitations are obtained,<br/>modelling envelope pulses or holes, and their characteristics are discussed.