Magnetospheric Relativistic Electron Flux Enhancement Of Observational And Theoretical Studies Of The Event

During the time of high-speed solar wind with a southward component of the IMF, geomagnetic storms/substorms and flux enhancement events of the relativistic electrons ( E ≥1MeV) are frequently observed in the outer radiation belt ( 3 ≤L ≤7). Typically, fluxes of relativistic electrons decrease during the main phase of a magnetic storm and then increase to exceed the pre-storm level by a factor of 10 or higher during the recovery phase, this phenomenon is called restivistic electron flux enhancement events. Since relativistic electrons have enough energy to penetrate the outer skin of spacecraft and cause internal charging, they can cause spacecraft anomalies or destroy a spacecraft completely. Using combining observational results from the ACE ,GOES10 and LANL1997 satellites, we have studied the changes of the interplanetary field (IMF), solar wind, Dst index, AE index and fluxes of the relativistic electrons (E≥1MeV) in the Earth's magnetosphere during the interval between October and November, 2003. The combining observational results show that the flux of the relativistic electrons can increases and exceeds the prestorm level just during recovery phase of the storms including many prolonged substorm activities. Furthermore, the larger the flux of the electrons with energy being less than 300 keV is, the larger the flux of the relativistic electrons is, which shows the substorm-injection electrons with energy being less than 300 keV may be an important source of the relativistic electrons. Some else observation results show that the peak of the relativistic electron fluxes is at about L =4⁵ and enhanced whistler-mode waves in the frequency range 0. 1f_ce ≤f≤0.75f_ce or fast mode waves (i.e., compressional ULF waves in the frequency range of between the Pc4 and Pc5 pulsations) are observed during the storm that is associated with relativistic electron flux enhancement. Thus, the electrons can resonate with the waves when both the electrons and waves satisfy the relativistic resonant conditions, which shows that some nonadiabatic accelerations possibly cause the flux enhancements of the relativistic electrons. In the quasi-linear approximation, we study electron acceleration process generated by whistler-mode and compressional ULF (fast mode waves) turbulences near the Earth's synchronous orbit. The calculation results include three different cases as the following: Firstly, the whistler-mode waves can interact with some substorm injection electrons with several hundreds of keV via the cyclotron resonance when compressional ULF waves don't exist or they are very weak in some region in magnetosphere. Electrons accelerated by whistler-mode waves are mainly substorm injection electrons that are called "seed electron". This means that substorm injection electrons can be regarded as seed electrons that can be accelerated by whistler-mode...