Abstract: In space physics, the study of substorms and magnetic storms has a great importance in transferring the energy from solar wind to the magnetosphere-ionosphere coupling system and atmosphere, where this energy take an important role in different processes such as, generating plasma instabilities, ion acceleration, plasma heating and so on. Plasma waves play a significant role in the transfer of mass, momentum and energy in tenuous, collisionless space plasmas and experience substantial attenuation during their propagation. This collisionless damping is caused by resonant wave-particle interaction as proposed by Landau; therefore, the study of Landau damping has significant importance in understanding the propagation characteristics of waves in space plasmas and provides insight into the basic plasma wave modes. When wave amplitude gets larger, nonlinear effects have to be considered. The nonlinear waves including the bipolar electric field solitary (EFS) structures are of great interest, as they are partially responsible for the acceleration of local plasma to produce magnetic-field-aligned electron and ion beams that produce discrete auroras and populate the magnetosphere with plasma of ionospheric origin.Therefore, in this dissertation, first we reviewed all the possible sources of energy entering the magnetosphere from solar wind and the energy release in the Magnetosphere-Ionosphere-coupling (MI Coupling) system during substorms and magnetic storms. As damping is an important characteristic of the wave which determines whether the wave will grow or damp out as it propagates in space, we will then studied the Landau damping of small amplitude electron plasma and ion-acoustic waves. At the last, we studied the characteristics of bipolar EFS structures which are a special type of nonlinear waves. For the energy budget studies, we concluded that the Akasofu’sε-parameter in its original form remains the most widely used parameter in the energy budget studies and gives a reasonable estimate of the total energy transferred into the magnetosphere from the solar wind. Although, some authors have found thatε-parameter underestimated the energy entered the magnetosphere. Furthermore, for the energy sinks in the MIC system, still there are three most important energy dissipation rates; the ring current injection rate UR, the Joule heat production rate in the ionosphere UJ, and the auroral particles precipitation rate UA, however, there are other minor energy sinks too.In this dissertation, Landau damping of small amplitude electron plasma (Langmuir) and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is investigated. As the space plasmas posses non-Maxwellian distributions, therefore, for the first time we have used a non-Maxwellian distribution function, such as the generalized distribution function in this investigation. Our numerical results showed that the damping rate is strongly dependent on the spectral indices r and q; and increases if the value of either q or r decreases or the percentage of the high energy particles increases. Although, as compared to the Langmuir ( r,q) waves, the dependence of damping rate on the spectral indices r and q for the ion-acoustic waves is weak. The Landau damping for such waves is strongly dependent on the ion temperature and experience only moderate Landau damping as long as T_i <

Key words: discontinuous shallow water flow; Qiantang River; tidal bore; Godunov scheme; KFVS scheme; “well-balanced” scheme; sediment mathematical model; moving boundary

# Theoretical Study on the Nonlinear Waves in Space Plasmas

This entry was posted in Doctoral Dissertation. Bookmark the permalink.