在地球磁鞘中电磁离子回旋波（EMIC波）普遍存在。由于磁鞘EMIC波事件中等离子体垂直温度大于平行温度，所以在理论上认为离子温度各向异性回旋不稳定性激发了EMIC波。但是，已有磁鞘EMIC波理论研究都基于较为理想的等离子体参数，如仅考虑单一离子和电子组分。实际上，磁鞘中每种粒子都含有多种组分，每种组分具有不同的密度、温度和漂移速度。最新空间MMS卫星具有高时间分辨率的电磁场和等离子体测量，使其非常有助于开展磁鞘EMIC波理论和观测研究。因而，本项目基于MMS卫星开展磁鞘EMIC波研究工作，主要包括：（1）在观测上研究磁鞘EMIC波的空间分布及其与等离子体物理参数之间的关联；（2）基于观测的等离子体多组分粒子物理参数，在理论上研究磁鞘中EMIC波的激发和阻尼机制，揭示EMIC波和粒子之间的能量转化过程。这两方面工作有助于深入理解空间等离子体中波-粒相互作用的基本物理过程。

Electromagntic ion cyclotron (EMIC) waves are often detected in the Earth’s magnetosheath. It is widely believed that these EMIC waves are triggered by the ion temperature anisotropy cyclotron instability in the magnetosheath plasmas where the ion perpendicular thermal temperature is larger than the parallel temperature. However, previous theoretic studies for the EMIC wave consider relatively ideal plasma environment, e.g., only one ion/electron component. In fact, the particle (ion and electron) velocity distribution in the Earth’s magnetosheath is composed of several particle components which has different density, temperature, and drifting velocity. The MMS spacecraft contains high temporal resolution electromagnetic and plasma measurements, which is very helpful for proceeding to the theoretic and observational investigation of the EMIC wave in the Earth’s magnetosheath. Using the MMS spacecraft measurement, this project plans to investigate: (1) the spatial distribution of the EMIC wave in the Earth’s magnetosheath, and the relation of the wave distribution with local plasma parameters; and (2) the excitation and damping process of the observed EMIC wave on the basis of plasma fluid and kinetic theories and actual plasma parameters. The latter could explore the energy transfer between EMIC waves and ions. Therefore, this project will be helpful for understanding the interaction of plasma waves with charged particles in the space plasmas.