快磁声波是一种频率介于质子回旋频率与低混杂频率之间的电磁波（不同于磁流体力学意义上的快磁声波），由质子环分布激发，在辐射带高能电子的动力学演化过程起重要作用。但是其全球分布特征及演化规律还有待系统深入研究。美国发射的Van Allen和THEMIS系列卫星搭载了能够探测空间电磁场电磁波和带电粒子的多个探测仪器，为研究地球辐射带的快磁声波全球分布与演化提供了很好的机会。本项目主要利用Van Allen和THEMIS卫星的探测数据，统计分析不同地磁活动期间快磁声波与质子环分布的全球分布特性；构建适用于磁层空间等离子体中快磁声波的三维电磁波路径跟踪模型和不稳定性模型，深入研究快磁声波的传播特性和不稳定性过程；并初步建立基于实际卫星探测结果的快磁声波时空演化模型。

Fast magnetosonic waves are electromagnetic emissions occurred at frequencies between the proton gyrofrequency and the lower hybrid frequency (which are different from the fast magnetosonic waves in magnetic hydrodynamics meaning). They are excited by proton ring distributions and play an important role in the dynamics of radiation belt energetic electrons. However, the global distribution and evolution of fast magnetosonic waves still require systematical and deep research. Equipped with the electric field instrument, magnetic field instruments, and particle instruments, Van Allen probes and THEMIS spacecrafts offer an excellent opportunity to investigate the global distribution and evolution of fast magnetosonic waves in the radiation belt. In this proposal, we shall study the global distribution of fast magnetosonic waves and proton rings during different geomagnetic activities by using detection data from Van Allen probes and THEMIS spacecrafts. We shall develop a three-dimensional ray-tracing model and the instability model of electromagnetic waves in space plasmas, and analyze the propagation and the instability process of fast magnetosonic waves. We plan to develop a model of the spatiotemporal evolution of fast magnetosonic waves.