非均匀行星际磁场中源自镜像力的新的高能带电粒子传播效应研究

Charged energetic particles in the interplanetary space, including solar energetic particles (SEP) and galactic cosmic rays (GCR), are harmful to the health of astronauts working in space and the electronic components on satellites, so they have become an important aspect in affecting solar-terrestrial space environment and space weather. It is very important to achieve a better understanding of the transport processes and effects of charged energetic particles in the interplanetary space. With combination of theoretical analyses, numerical simulations, and spacecraft observations, in this project we will systematically investigate the new transport effects of charged energetic particles from the mirror force in the large-scale inhomogeneous interplanetary magnetic fields. Firstly, based on the latitudinally dependent model of solar wind speed, we will determine the mirror force effects of the inhomogeneous interplanetary magnetic fields and the corresponding diffusion coefficients of energetic particles. Secondly, based on the sophisticated models of the heliospheric magnetic field, we will quantitatively describe the effects of mirror force on the diffusion and transport processes of energetic particles in the inhomogeneous magnetic fields. In addition, in the framework of the nonlinear diffusion theory, the mirror force effects of the inhomogeneous interplanetary magnetic fields will be quantitatively evaluated. We will also investigate the spectral index forms of the magnetic turbulence in the inhomogeneous interplanetary magnetic fields and their effects on the transport processes of energetic particles. The results presented in this project will provide new theoretical evidences to quantitatively explain the observational phenomena of the energetic particles, and will lay solid physical bases for establishing forecast model of radiation environment of energetic particles in the solar-terrestrial space.

行星际空间中的高能带电粒子包括太阳高能粒子 (SEP) 和银河宇宙射线 (GCR)，对在太空中作业的宇航员和卫星上的电子元器件均构成严重危害，成为影响日地空间环境和空间天气的重要因素。深入理解高能带电粒子在行星际空间中的传播过程及效应十分重要。本项目拟结合理论分析、数值模拟和飞船观测，系统研究大尺度非均匀行星际磁场中源自镜像力的新的高能带电粒子传播效应。首先，在纬度依赖性太阳风速度模型的基础上，确定非均匀行星际磁场的镜像力效应及相应的高能粒子扩散系数。其次，在精细日球磁场模型基础上，定量描述非均匀磁场中镜像力对高能粒子扩散与传播过程的影响。此外，在非线性扩散理论框架中定量评估非均匀行星际磁场的镜像力效应；明确非均匀行星际磁场的磁湍流谱指数形式及其对高能粒子传播过程的影响。本项目的研究结果将为定量解释高能粒子观测现象提供新的理论依据，为构建日地空间高能粒子辐射环境预报模式奠定坚实的物理基础。

行星际空间中的高能带电粒子包括太阳高能粒子 (SEP) 和银河宇宙射线 (GCR)，对在太空中作业的宇航员和卫星上的电子元器件均构成严重危害，成为影响日地空间环境和空间天气的重要因素。深入理解高能带电粒子在行星际空间中的传播过程及效应十分重要。本项目结合理论分析、数值模拟和飞船观测，系统研究了大尺度非均匀行星际磁场中源自镜像力的新的高能带电粒子传播效应，取得了重要进展和成果。研究结果主要包括：（1）在考虑磁场绝热聚焦作用情形下，研究了随纬度变化的太阳风速度对高能带电粒子扩散系数的影响；（2）通过数值模拟，发现了太阳高能粒子分布的东-西经度非对称性，并用垂直扩散机制予以解释；（3）用数值模拟重现了反向流动粒子束现象，并详细探讨了形成该现象的物理机制；（4）通过对1996-2011年间太阳高能粒子事件的统计分析，确认了太阳高能粒子事件的东-西经度非对称性分布现象；（5）发现了太阳高能粒子通量径向依赖性的“两阶段”现象，并指出该现象的“断点”位置取决于各飞船的磁连接状态。受本项目部分资助，已在本领域国际主流期刊上发表5篇论文。本项目研究成果对于深入理解太阳高能粒子扩散与传播过程具有重要意义。