A Theoretical Model for Nonlinear Waves Observed in Space Plasmas

The nonlinear waves exists everywhere in space plasmas, such as solar wind, planetary magnetosphere, ionosphere, and so on. The nonlinear structure could be complex particle density structure and electric field structure. In this study, the nonlinear waves observed in space plasmas are reviewed. A fully nonlinear theoretical model for the observed ion nonlinear structure in low $\beta$ plasma is introduced. The Model results show that the electrostatic linear ion-cyclotron wave and ion acoustic wave could be excited and developed to nonlinear structures, such as the density periodical nonlinear wave, hump soliton, dip soliton and shock, as well as the nonlinear E-field structures. The plasma condition to excite each type of the nonlinear structures are given, and the condition of the E-filed nonlinear waves are analyzed and given, too. With concrete parameters, the model results could be consistent with observation in the nonlinear waveform and size, both for nonlinear density waves and E-field waves.