The Influence Of Hiss And Chorus Waves Normal Angles On Wave-particle Resonant Interaction

Radiation belt has attracted much attention since it was found in 1959, and is one of the important regions in the magnetosphere. During the main phase of geomagnetic storms, the flux of energetic electrons in the outer radiation belt drops rapidly, but increases gradually during the recovery phase. During substorms, plasmas injection into the inner magnetosphere occurs rapidly, producing the variation of the flux of energetic electrons. Since the increase in the energetic flux can hurt the satellite and the health of the astronauts, and even change the atmospheric chemical components, leading to the destruction of ozone. So it is very important to study and predict the evolution of the energetic electrons in the outer radiation belt.Hiss, chorus waves can resonate with energetic electrons, accelerating electrons. The acceleration of energetic electrons due to wave-particle interaction in the outer radiation belt depends on Fokker-Planck dynamic diffusion equation, and the solution of the diffusion equation is related to the diffusion coefficients. In this paper, using a Gaussian distribution of wave normal angle, and considering contributions of harmonic resonances n up to ±5, we simulate the evolution of the diffusion coefficients induced by gyroresonance between chorus, hiss waves and electrons with energies 1.0,2.0,3.0 and 4.0MeV at L=4.5. When Pitch Angle αe< 10 °, as the wave normal angle peak XM (XM=tanθM) increases,2MeV or above diffusion coefficients driven by the dayside chorus and 1MeV or above diffusion coefficients driven by hiss, the nightside chorus increase slightly; as the pitch angle increases, the effect of the peaks on the diffusion coefficients increases gradually; atαe> 20 °, when the peak increases 2.5 each time, the diffusion coefficients of hiss and chorus decrease rapidly, the reduction magnitude of hiss and chorus on the dayside become small gradually, the reduction magnitude of diffusion coefficients on the nightside firstly becomes large and then small; as energy increases, the diffusion coefficients decrease, and hiss wave normal angle effect on the diffusion coefficients decrease, too; for chorus, the peak effect on the diffusion coefficients increase with increasing energy. On this basis, we also have analyzed the effect of chorus and hiss normal angle on the diffusion coefficients at L=6. Results indicate that the peak effect on the diffusion coefficients of hiss and chorus at L=6 is analogous to the effect at L=4.5.