三维有结构太阳风背景条件下的太阳高能粒子（SEP）数值模拟研究

太阳高能粒子(SEP) 事件是重要的灾害性空间天气事件之一，SEP的传播和加速机制方面的研究一直是空间天气学研究的前沿课题。SEP在行星际空间中的传播及演化过程，均与背景太阳风密切相关，目前国内外SEP数值模拟方面的研究大多以恒定的太阳风速度和Parker螺旋磁场为基础，背景场的设置较为理想化。因此，获取更加接近物理真实的有结构太阳风背景场是提高 SEP 数值模式的关键因素之一。本研究基于三维的MHD数值模拟和观测约束，建立适用于不同太阳活动阶段的，从太阳表面附近直至10AU的三维稳态背景太阳风模型，并在该模型基础上研究太阳风压缩区以及共转相互作用区(CIR)激波对SEP传播和加速过程的影响，分析聚焦尺度(LB)在三维磁场中的变化特征及其与太阳风速度的相关性，期望更深层次理解 SEP 在日球层中的传播和加速机制。

Solar Energetic Particles (SEPs) as one kind of the disastrous space weather events could cause the destructive damages to spacecraft systems and constrain human activities in the space．To understand the transport and acceleration processes of SEPs is an important issue in alleviating these damage. The transport processes of SEPs in the inner heliosphere are modulated by ambient solar wind velocity and magnetic field. Previous simulation works often simplify the solar wind velocity as radial and constant, and treat the magnetic field as Parker spiral. In order to fully understand the effect of realistic underlying background conditions on the particles’ transport and acceleration process, a realistic background solar wind and magnetic field is required. In this investigation, the observation-constrained background solar wind from the coronal base to 10 AU　is　obtained　by the 3D high-resolution MHD model with a six-component grid. Then we combine the 3D background solar wind generated from the MHD model with the　SEP model to study the influence of the regions of solar wind compression and Corotating Interaction Region (CIR) shock on the transport and acceleration processes of SEPs. Furthermore, the particle distribution is affected by adiabatic focusing. We also investigate the variations of the magnetic focusing length LB in 3D solar wind velocity and magnetic field, and the relationship between LB and the solar wind speed. With comprehensive studies of SEP acceleration and propagation, we hope to enhance our understanding to the physics of SEP events.