The Parameter Study Of Radiation Belt Electron Dynamics Driven By Whistler Waves

The magnetopause forms when magnetosphere interacts with solar wind whichhas a large number of energetic particles. Radiation belt is one of the importantregions of Earth’s magnetosphere. Solar activity causes the dynamic changes in theEarth’s magnetosphere when geomagnetic storms occur. Enhanced energetic particleflux in the radiation belt poses a serious hazard to synchronous orbit spacecraft,astronauts and ground power systems. Previous study has suggested that thecyclotron resonant interaction with waves is an important acceleration mechanism inthe radiation belt. The timescale of radiation belt energetic electrons accelerationdriven by whistler mode chorus waves is consistent with observations. Therefore, itis of a great significance to investigate the effect of acceleration driven by whistlermode chorus waves in the radiation belt. We can obtain the Fokker-Planck equationwhich describes the evolution of electron phase space density from the basicequations of kinetics. The general diffusion coefficient expression of every wave isdifferent. We use different spectral parameters of parallel whistler mode choruswaves to calculate acceleration of energetic election in the radiation belt, andcompare with the observation. The simulation results show that the neglect of crossdiffusion can cause the overestimate of energetic election PSDs, and the crossdiffusion plays a more significant role at larger L-shells. The change of spectralparameters would have an obvious impact in diffusion coefficient and the electronPSDs, especially for the small pitch angles. In order to improve the accuracy of thecalculation, the determination of spectral parameters is very important in thenumerical simulation study, and more accurate spectral parameters are required forthe different numerical models. Through the analysis of the examples we have foundthat the magnitude of the energetic electron flux produced by whistler mode choruswaves. Moreover, we provide the first simulation of the effect of Z-mode waves onthe outer radiation belt electron dynamics. The numerical results demonstrate thatmomentum diffusion dominates the dynamic evolution of energetic elections,whereas the contribution of pitch angle or cross diffusion rates is negligible usingthe specified Z-mode wave model.