Ion-Acoustic Solitary Waves in a Partially Degenerate Plasma

The propagation of arbitrary amplitude ion-acoustic (IA) solitary waves (SWs) is studied in unmagnetized, collisionless, homogeneous electron-positron-ion (e-p-i) plasmas with finite temperature degeneracy of both electrons and positrons. Starting from a set of fluid equations for classical ions and Fermi-Dirac distribution for degenerate electrons and positrons, a linear dispersion relation for IA waves is derived. It is seen that the wave dispersion is significantly modified due to the presence of positron species and the effects of finite temperature degeneracy of electrons and positrons. In the nonlinear regime, Sagdeev's pseudopotential approach is employed to study the existing domain and the evolution of nonlinear IA-SWs in terms of the parameters that are associated with the finite temperature degeneracy, the background number densities, and the thermal energies of electrons and positrons. It is found that in contrast to classical electron-ion plasmas, both the subsonic and supersonic IA-SWs can exist in a partially degenerate e-p-i plasma.

Automated summary

This study investigates the propagation of ion-acoustic solitary waves with arbitrary amplitude in unmagnetized, collisionless, homogeneous electron-positron-ion plasmas with finite temperature degeneracy. The results show that the wave dispersion is significantly modified by the presence of positron species and the effects of finite temperature degeneracy of electrons and positrons. In the nonlinear regime, Sagdeev's pseudopotential approach is utilized to analyze the nonlinear IA-SWs in terms of parameters related to the finite temperature degeneracy, background number densities, and thermal energies. It is found that both subsonic and supersonic IA-SWs can exist in partially degenerate e-p-i plasmas, which is different from classical electron-ion plasmas.