Rapid precipitation of radiation belt electrons induced by EMIC rising tone emissions localized in longitude inside and outside the plasmapause
Rapid precipitation of radiation belt electrons induced by EMIC rising tone emissions localized in longitude inside and outside the plasmapause
复制标题
DOI：
10.1002/2016ja023267
复制
发表时间：
2017-01-01
影响因子：
2.8
通讯作者：
Omura, Yoshiharu
中科院分区：
文献类型：
--
作者：
Kubota, Yuko;Omura, Yoshiharu
通过对相对论电子被电磁离子回旋(EMIC)上升音发射散射的实验粒子模拟，我们发现了一种与非线性波捕获完全不同的非线性散射过程，称为SLPA(低音调角散射)。在远离损耗锥的大俯仰角时发生的非线性俘获，使一些共振电子散射到较低的俯仰角，一部分电子从俘获波中释放出来后被SLPA进一步传输到损耗锥中。SLPA和非线性俘获可以在有质子带或氦带的任何情况下工作，也可以在等离子体顶内外工作。我们阐明，联合散射过程会导致外辐射带的显著耗尽。在经向局域观测到的电子分布的时间演化中，我们发现了局域EMIC发射对电子耗尽的回声。监测在波生区丢失到大气中的电子的通量，我们还发现有效的相对论电子在几秒钟内沉淀。作为动能函数的沉淀电子通量的特性随波的频率范围和等离子体密度的不同而显著不同。
By performing test particle simulations of relativistic electrons scattered by electromagnetic ion cyclotron (EMIC) rising tone emissions, we find a nonlinear scattering process named SLPA (Scattering at Low Pitch Angle) totally different from the nonlinear wave trapping. The nonlinear wave trapping, occurring for high pitch angles away from the loss cone, scatters some of resonant electrons to lower pitch angles, and a fraction of the electrons is further transported into the loss cone by SLPA after being released from the wave trapping. SLPA as well as the nonlinear wave trapping can work in any cases with proton band or helium band and inside or outside the plasmapause. We clarify that the combined scattering process causes significant depletion of the outer radiation belt. In the time evolution of an electron distribution observed locally in longitude, we find echoes of the electron depletion by the localized EMIC emissions. Monitoring fluxes of electrons being lost into the atmosphere in the wave generation region, we also find that efficient relativistic electron precipitation in several seconds. The characteristics of the precipitating electron flux as a function of kinetic energy vary significantly depending on the wave frequency range and the plasma density.