Non-planar ion acoustic Gardner solitons in electron-positron-ion plasma with superthermal electrons and positrons

The properties of non-planar (cylindrical and spherical) ion acoustic solitary waves (IASWs) in an unmagnetized collisionless electron-positron-ion (e-p-i) plasma, whose constituents are inertial ions and superthermal/non-Maxwellian electrons and positrons (represented by the kappa (κ) distribution), are investigated by deriving the modified Gardner (MG) equation. The well-known reductive perturbation method is employed to derive the MG equation. The basic features of non-planar IA Gardner solitons (GSs) are discussed. It is seen that the properties of non-planar IAGSs (positive and negative) differ significantly as the value of spectral index kappa changes.