Low Frequency Electromagnetic Waves Observation During Magnetotail Reconnection Event

Abstract

Magnetic reconnection is a very important physical process in astrophysical and laboratory plasmas, which enables reconfiguration of the magnetic field topology and converts the magnetic field energy to plasma kinetic and thermal energy. The diffusion region is a crucial region of reconnection where magnetic field and plasma decouple from each other and strong wave activity and complex wave particle interactions occur. In general, the regions where the energy conversion takes place, e.g. substorm, ionosphere, shocks, produce wave emissions or wave turbulence covering a wide frequency range. Reconnection sites are not an exception. Understanding the role of waves and wave turbulence in the energy conversion, energy transport, and structure formation of the reconnection sites is an important and challenging task. When the reconnection takes place at ion inertial length, the wave-particle interaction plays an important role in reconnection process. Both the whistler dynamics and kinetic Alfven waves can strongly influence the structure of the dissipation region during magnetic reconnection. Hall term in the generalized Ohm’s law brings the dynamics of whistler waves into the fluid equations [1]. The only place where a reconnection site can be studied in great detail is laboratory and the Earth magnetosphere (or other environments in our solar system that have been visited by spacecraft, e.g. solar wind, other planets, comets). The spacecraft observations give much more detailed picture of the plasma dynamics at the smallest electron scales than the laboratory experiments, mainly due to the possibility to resolve particle distribution functions and fields at small scales. As the reconnection involves many processes at different spatial and temporal scales, numerical simulations serve as a superior tool for understanding the environment and physical processes near reconnection sites. The subsolar magnetopause and magnetotail are the two main regions in the Earth magnetosphere where the reconnection process has been observed by spacecrafts. The magnetotail reconnection is generally symmetric. In a sense plasmas on both sides of the current sheet have very similar properties. The opposite situation is observed at the magnetopause where the reconnection is mainly asymmetric. Another important difference between the magnetopause and mangetotail is that the typical spatial scales, e.g. ion inertial length, are usually a factor of ten smaller at the magnetopause. This is important for in situ studies where the instrument resolution becomes a limiting