| Plasma consists of ions, electrons, and other neutral particles. There are plenty of plasma in the nature, such as the air punctured by lightning. Moreover, plasma also exists in people’s life, like fluorescent lamp.Plasma is electric quasi-neutrality as a whole. However, locally, electromagnetic fields must be considered because they plays an important role on dynamic processes in plasma, which is different from air. Thus, the existence of electromagnetic fields makes the research on plasma dynamic processes much difficult.Generally, magnetic reconnection plays an important role in magnetized plasma. Many observation results have indicated that magnetic reconnection plays a crucial role on the energy transfer and transport in magnetized plasma, even can be regarded as the most important process. Through the process of magnetic reconnection, magnetic energy can be transferred to thermal energy and kinetic energy of plasma. It is also widely recognized that magnetic reconnection is a fundamental energy transport mechanism in collisionless plasma. Various types of waves can be generated in the process of magnetic reconnection, such as Alfven wave and magnetosonic wave. There have been some theoretical and experimental investigations about the generation of Alfven wave through magnetic reconnection in the solar environment. It is believed that the process of magnetic reconnection widely exists in the photosphere, chromosphere and solar corona. Besides coronal heating, Alfven wave is also very important to solar wind acceleration. Hence, the study of Alfven wave generation in magnetic reconnection is of great significance.In this thesis, we conduct 2D MHD simulations to investigate generation of Alfven wave energy during magnetic reconnection.First, we introduce a new method to determine the Alfven wave generated during magnetic reconnection which is triggered by a locally enhangced resistivity. The distributions of the x and z components of Alfven wave show a good agreement with the magnetic field and plasma flow stream line bending. During the growth phase of reconnection, the distribution undergoes a dramatic change. In the decay phase, it almost keeps its shape and position. Due to the resistive dissipation, magnetic energy mainly transforms to thermal energy. The maximum conversion rate from the magnetic energy to the Alfven wave energy is about 4.3%.Second, we investigate how reconnection speed influences the generation of Alfven wave. In this part, both the uniform resistivity and Hall effects are considered. Larger resistivity leads to larger reconnection rate. Thus, large resistivity can speed up the energy conversion procedure. However, larger resistivity does not give a larger conversion rate from magnetic energy to Alfven wave energy. With the uniform resistivity without Hall effect, the conversion rate is less than one percent that is much lower than that obtained in the above first part for the case with a locally enhangced resistivity. A strong Hall effect not only accelerates magnetic reconnection process and also gives a larger conversion rate between magnetic energy and Alfven wave energy. With inclusion of Hall effect, energy conversion can be as large as that for a locally enhanced resistivity case. Besides, stronger Hall effect causes higher conversion rate.Third, we investigate the effect of a guiding field. The guiding field will suppress magnetic reconnection. The in-plane magnetic energy decreases with time, while the equivalent thermal energy increases. The in-plane magnetic energy mainly transforms to equivalent thermal energy. Kinetic energy slightly reduces with the increase of the guiding magnetic field. Overall, the guiding magnetic field only slightly reduce the conversion rate to Alfven wave energy from magnetic energy and has little effect on the distribution of the x and z components of Alfven wave energy. |
