ION-ACOUSTICBIPOLAR ELECTRIC FIELD SOLITARY STRUCTURESWITH TRAPPED ELECTRONS

Bipolar electric field solitary (EFS) structures are essential components of space plasmas. Bipolar structures, which are associated with solitons, have been detected by numerous satellites across variousareas of near-Earth plasmas, including the solar wind, Earth's magnetosphere, auroral zone, and Martian magnetosheath. A fluid model is presented in this paper that incorporates inertial warm ions and adiabatically trapped electrons, deriving the Sagdeev potential from fully nonlinear fluid equations. Our findings indicate that bipolar EFS structures, which correspond to compressive solitons, can emerge in such plasmas. The results of our model provide valuable insights for interpreting solitary structures in space plasmas where trapped electrons are present.