Research On The Enhancements Of Energetic Outer Radiation Belt Electron Fluxes Driven By Chorus Waves During Magnetic Storm

Radiation belt is one of the most important regions in earth's magnetosphere. The enhancement of energetic particles fluxes in radiation belt poses a serious threat to spacecraft, astronauts and ground transmission system during magnetic storm. Therefore, it is of a great significance to investigate the energetic particles fluxes evolution in outer radiation belt.Latest research work has shown that wave-particle interaction is the primary mechanism responsible for the energetic electrons acceleration, yielding the flux enhancement. The timescale of ULF-driven acceleration lies in the range of tens of minutes to a few hours. While the timescale of acceleration associated with whistler-mode chorus are from half a day to several days, consistent with the observation that flux enhancement in energetic electrons can last for several days during the recovery phases of most stroms.The evolution of energetic outer zone electron fluxes during the strong magnetic storm on September 28 2002 is investigated based on the observations of SAMPEX, GOES-10 and NOAA-14 satellites. The observations of both satellites showed that energetic electron fluxes increased significantly during the storm recovery phase, and reached the maximum on October 6. The 1.5-14MeV and 2.5-14MeV electron fluxes observed by SAMPEX peaked around L=3.5 with values of 6×102 cm-2s-1sr-1keV-1 and 5×103 cm-2s-1sr-1keV-1, about 10 and 8 times higher than the pre-storm values. At the geostationary orbit, the >0.6MeV and >2MeV electron fluxes observed by GOES showed enhancements up to 50 and 30 times. The observation of NOAA showed that >100kev and >300keV electrons (seed-electrons) fluxes enhanced significantly after the storm began. The plasma parameters and whistler-mode chorus waves in the outer radiation belt are also analyzed based on the data from Cluster C3 satellite. Cluster C3 satellite passed through the outer radiation twice from 1 October to 4 October, and observed whistler-mode chorus waves with high intensity (10-5-10-4 nT2/Hz). Numerical calculations indicate that the observed chorus waves stay in gyro-resonance with the radiation belt electrons. The current observations and calculations provide a new evidence for that the gyro-resonance with chorus waves contribute significantly to the buildup of energetic outer zone electron fluxes during storms.