等离子体层嘶声对槽区电子的弹跳共振散射效应  

Bounce resonance scattering of slot region electrons by plasmaspheric hiss

作　　者：曹兴[1] 陆鹏 朱琪 马新 倪彬彬[1] CAO Xing;LU Peng;ZHU Qi;MA Xin;NI BinBin(Department of Space Physics,School of Electronic Information,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学电子信息学院空间物理系,武汉430072

出　　处：《地球物理学报》2023年第5期1796-1806,共11页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2022YFF0503900,2022YFF0503700);国家自然科学基金(41904144,42025404,42188101,42241143);中国科学院先导B计划(XDB41000000);中央高校基本科研业务费专项资金(2042022kf1012,2042021kf1045,2042021kf1056)资助。

摘　　要：等离子体波动与带电粒子的共振相互作用一直是磁层物理学的研究热点.作为一种常见的宽频、右旋极化等离子体波动,等离子体层嘶声在地球磁层电子的损失过程中起到了重要作用.其中,嘶声波对电子的回旋共振散射被认为是辐射带槽区形成的主要机制,而人们对嘶声波与电子的弹跳共振机制的理解却相对匮乏.本文旨在细致研究嘶声波与槽区电子的弹跳共振相互作用,明确其对槽区电子动态演化过程的影响.研究发现,嘶声波与电子的弹跳共振可以造成槽区电子在高投掷角(80°~90°)处明显的投掷角扩散.相比于低能(<~100 keV)电子,嘶声波引起的高能(>~100 keV)电子的弹跳共振效应明显更强.槽区电子的弹跳共振投掷角扩散系数对于L-shell、地磁活动条件和共振阶数都有着很强的依赖性.随着L-shell的增大和地磁活动的增强,嘶声波对电子的弹跳共振散射效应显著增强.对于低能电子,共振阶数对总散射系数的贡献随阶数的升高而增大;而对于低L-shell处的高能电子,共振阶数对总散射系数的贡献随阶数的升高而呈现先增大后减小的趋势.嘶声波与槽区电子的弹跳共振相互作用可以有效地将高投掷角电子散射到较低的投掷角上,进而在回旋共振机制的协助下将它们散射到损失锥中.因此,未来在地球槽区电子动力学建模过程中有必要考虑等离子体层嘶声对电子的弹跳共振散射效应.Resonant interactions between plasma waves and charged particles have always been a research hotspot in magnetospheric physics.As a kind of frequently observed broadband and right-handed polarized plasma waves,plasmaspheric hiss plays an important role in the loss of magnetospheric electrons.The cyclotron resonance scattering of electrons by hiss is considered to be the main mechanism responsible for the formation of the slot region in the radiation belts,while the understanding of the bounce resonance mechanism is relatively poor.This paper is aimed at investigating the bounce-resonant interactions between hiss and energetic electrons in the slot region in detail,and clarifying their influence on the dynamic evolution of slot region electrons.It is found that the bounce resonance between hiss and electrons can cause efficient pitch angle diffusion of electrons at high pitch angles(80°~90°)in the slot region.Compared to low-energy electrons(<~100 keV),the bounce resonance scattering effects of high-energy(>~100 keV)electrons caused by hiss are significantly stronger.The bounce resonance pitch angle diffusion coefficients of slot region electrons have a strong dependence on L-shell,geomagnetic activity conditions and bounce resonance order.The bounce resonance scattering effects of slot region electrons are enhanced with an increase of L-shell and the level of geomagnetic activity.The contribution of each bounce resonance order to the net scattering rates increases with increasing resonance order for low-energy electrons.Nevertheless,for high-energy electrons at low L-shells,the contribution of the resonance order tends to increase first and then decrease as the resonance order increases.The bounce resonance interactions between hiss and slot region electrons can effectively scatter high pitch angle electrons to lower pitch angles,where the cyclotron resonance mechanism can take over and subsequently scatter them into the loss cone.It is thus necessary to incorporate the bounce resonance scattering by plasmasphe

关 键 词：地球槽区 等离子体层嘶声 波粒相互作用 弹跳共振 

分 类 号：P352[天文地球—空间物理学]