ECH波与地球磁层电子的波粒共振相互作用

The Earth's magnetosphere is a fascinating natural plasma laboratory, within which the dynamics of energetic charged particles can be comprehensively explored. Recent five-probe THEMIS campaign has led to a resurgence of the researches on the global distribution and dynamical variability of magentospheric electrons. Specifically for this project, THEMIS multi-satellite observations have accumulated uniquely long-term FFF wave datasets featured by high resolution in both wave frequency and spatial-temporal domain, which enables a systematic and comprehensive analysis of electrostatic electron cyclotron harmonic (ECH) waves and its resonant interactions with magnetospheric electrons for the occurrence of diffuse auroral precipitation. The project will firstly adopt all the available THEMIS FFF wave data (2007 - 2013 and continously accumulating) to develop a well-defined global model of ECH emissions, which will be then used to compute the quasi-linear bounce-averaged diffusion coefficients of magnetospheric electrons due to resonant interactions with ECH waves. The dependence of ECH wave scattering rates on L-shell, MLT, electron energy, and equatorial pitch angle will be well evaluated to investigate the role of ECH waves in affecting the dynamic processes of magnetospheric electrons. Electron lifetime associated with ECH wave scattering can be estimated by inversing the bounce-averaged pitch angle scattering coefficient at the edge of loss cone. To largely increase computation efficiency, we will derive the parameterization of electron lifetime using a linear regression technique. Such parameterization efforts of plasma sheet electron lifetimes Our results to be obtained will be of signifcant importance to improved understandings of the global morphology of the diffuse aurora and multidimensional simulations of diffuse auroral precipitation and its effects on magnetosphere-ionosphere coupling in the auroral regions.

地球磁层是一个令人着迷的天然等离子体实验室，可以用来探索高能带电粒子的动力学过程。THEMIS项目的成功实施，把有关磁层电子的分布与动力学研究推向了一个新的高潮。随着THEMIS观测数据的不断积累，大量的、具有高质量的频率、空间和时间分辨率的FFF数据，使得对ECH波与磁层电子的波粒共振相互作用的系统研究成为可能，而这一物理过程与地球弥散极光的形成有重要联系。本项目首先利用THEMIS数据建立发展现有的ECH波的全球分布模型；进而基于准线性理论，通过计算、量化与L-shell、MLT、电子能量和赤道投掷角有关的弹跳平均散射系数，考察ECH波在磁层电子动力学过程中的作用。电子被等离子体波散射后的生存周期可通过其在损失锥角边沿的弹跳平均投掷角散射系数来估算。为缩短计算时间，线性回归方法将被用来参量化电子的生存周期。研究结果对弥散极光电子沉降的模拟以及极区磁层电离层耦合的研究有着非常重要的意义。

地球磁层是一个令人着迷的天然等离子体实验室，可以用来探索高能带电粒子的动力学过程。THEMIS项目的成功实施，把有关磁层电子的分布与动力学研究推向了一个新的高潮。随着THEMIS观测数据的不断积累，大量的、具有高质量的频率、空间和时间分辨率的FFF数据，使得对ECH波与磁层电子的波粒共振相互作用的系统研究成为可能，而这一物理过程与地球弥散极光的形成有重要联系。本项目首先利用THEMIS数据建立发展现有的ECH波的全球分布模型；进而基于准线性理论，通过计算、量化与L-shell、MLT、电子能量和赤道投掷角有关的弹跳平均散射系数，考察ECH波在磁层电子动力学过程中的作用。电子被等离子体波散射后的生存周期可通过其在损失锥角边沿的弹跳平均投掷角散射系数来估算。研究结果对弥散极光电子沉降的模拟以及极区磁层电离层耦合的研究有着非常重要的意义。