近磁尾高速流与背景等离子体相互作用区电流体系研究

A magnetospheric substorm is an important energy transfer and coupling process in which energy from the solar wind-magnetosphere interaction is gradually stored and then quickly released in the near-Earth magnetotail and the ionosphere. Because of its central role in substorm onset and ionospheric dissipation of substorm energy, the field-aligned current system, which connects the magnetotail and the ionosphere resulting in substorm auroral brightening, has been one of the most important topics in substorm research for the past forty years. Recent multi-point observations from the ARTEMIS, THEMIS, GOES, and Van Allen spacecraft suggest that flow bursts emanating from near-Earth reconnection arrive at the inner magnetosphere where they play a critical role in generating the global substorm current wedge, supplying ions to the ring-current, generating the seed electron population for radiation belts, and creating ion cyclotron and whistler waves. These waves, in turn, affect the further evolution of the near-Earth space environment. Thus, the role of tail reconnection in substorms is more firmly established than ever before, and the potential importance of reconnection flows for storm-time evolution and electron acceleration is quite significant. Critical to our understanding of how reconnection outflows interact with the inner magnetosphere is the pressure distribution and flow evolution surrounding reconnected flux bundles that arrive in the inner magnetosphere. Using an unprecedented array of spacecraft from the near-Earth magnetosphere, I propose to evaluate ambient plasma conditions and reconnected flux bundle properties that enable penetration of reconnected flux bundles to the inner magnetosphere, where they become geoeffective.

磁层亚暴是太阳风-磁层-电离层体系能量传输与释放的主要过程。磁层中的场向电流则是磁层与电离层之间的能量与粒子传输的重要纽带。近磁尾场向电流系统由于其在亚暴爆发以及与极光点亮的电离层能量耗散过程中所起的重要作用，已经成为了近四十年来亚暴研究中最为重要的课题之一。近期，来自ARTEMIS、THEMIS、GOES以及Van Allen多个卫星计划的观测资料显示出近地重联所产生的等离子体高速流对亚暴电流楔的形成有重要贡献，并且可能提供环电流的离子、产生辐射带的种子电子以及激发离子回旋波和哨声波。而这些等离子体波又会进一步的影响近磁尾空间环境。随着磁尾重联在亚暴过程中的关系的系统建立，高速流作为能量、粒子和磁通量传输的载体显得尤为重要。本项目立足于近磁尾多卫星与地面磁场台站的联合观测研究，将建立高速流到达近磁尾所产生的场向电流系统变化模型。

磁层亚暴是日地能量传输和释放的主要过程之一，而亚暴的核心难题则是亚暴电流体系的行程机制。本项目聚焦与近磁尾高速流与背景等离子体相互作用的电流体系，以及对应的等离子体动力学特征。这一相互作用过程对于认识亚暴电流体系的行程机制有极为重要的科学意义。本项目立足于近磁尾多卫星与地面磁场台站联合观测，利用了MMS卫星，THEMIS卫星以及Cluster卫星研究了从磁流体力学的大尺度到粒子回旋尺度的微小尺度电子动力学以及电流题系，尤其是对场向电流的特征极其形成机制做了充分的研究。本项目所产生的科学成果极大地提升了我们对磁层电流体系以及电子微观动力学的理解。