The pitch angle diffusion by stochastic motion in the Earth’s radiation belt

Thursday, 18 December 2014
Cheongrim Choi1, Kyunghwan Dokgo1, Suk-bin Kang1, Eun Jin Choi1, K.-W. Min1, Junga Hwang2 and Young-deuk Park2, (1)KAIST Korea Advanced Institute of Science and Technology, Daejeon, South Korea, (2)KASI Korea Astronomy and Space Science Institute, Daejeon, South Korea
The motion of electron in the presence of the linearly polarized electromagnetic (EM) wave propagating along the uniform magnetic field (B0), which can be treated as electromagnetic ion cyclotron (EMIC) wave is investigated. There can be two resonances between the electron and the Doppler shifted EM wave which one is R mode resonance and the other is L mode. We show the stochastic motion of electrons with the Poincaré’s surface of section plot as the wave amplitude increases. Then we explain theoretically the electron precipitation by pitch angle diffusion. The pitch angle diffusion coefficient is calculated for Earth’s radiation belt from the dynamics of stochastic electrons. It is also compared with quasi-linear diffusion coefficient for EMIC wave. Furthermore it is found that the precipitation time of electron by pitch angle diffusion is about a few minutes for EMIC wave.