托卡马克边缘局域模输运和能流沉积的动力学模拟研究

Edge localized modes (ELMs), an instability occurring in the edge of high-confinement mode (H-mode) plasma, are considered as one of the most important issues in the field of fusion research. ELMs produce a periodic expulsion of plasma particles and energy from the edge region of core plasma into the scrape-off layer (SOL) towards the divertor target and other plasma facing components (PFCs). High energy particles due to ELMs burst lead to the excessive heat load on the divertor plate, which results in material erosion and melting. In this project, the particle-in-cell (PIC) code is developed for the kinetic studies of ELMs in EAST tokamak device in the following two aspects: 1. ELMs transport in the SOL and resulting power loading on the divertor plate. The influence of ELMs transport on plasma sheath and the distributions of potential and electric field is investigated. Further, the detailed physical information of incident particles has been employed to calculate energy flux and erosion rate of target plate. In addition, the impact of recycling on the distribution of energy flux is investigated. 2. The studies of gas puffing for mitigating the erosion of divertor plate during ELMs. The PIC model coupled with DSMC (direct simulation Monte Carlo) method is used to study the impact of puffing location, puffing duration , injected gas velocity and species on alleviating the erosion of divertor plate during ELMs.

边缘局域模（ELMs）是高约束模状态下发生的一种边缘不稳定性，对于ELMs问题的研究是聚变研究领域的重要课题之一。ELMs会周期性地将粒子和能量从中心等离子体边缘区域排除到刮削层中，在刮削层中输运后载能粒子会沉积在偏滤器靶板或者其它面向等离子体部件上。这些高能粒子在偏滤器靶板产生过高的热负荷，导致靶板材料侵蚀和融化。本项目自主开发粒子模拟程序，针对EAST装置发生ELMs的情况下，开展了以下两方面的动力学模拟研究：1.ELMs在刮削层中输运和在偏滤器靶板上能流沉积。主要研究ELMs输运对等离子体鞘层，电势和电场分布的影响，根据粒子轰击靶板的物理信息计算靶板上的能流沉积和侵蚀速率，以及研究再循环对能流分布的影响。2.喷入气体来减缓ELMs对偏滤器靶板侵蚀的研究。使用PIC-DSMC方法研究在ELMs发生的过程中，喷气位置、喷气持续时间、喷入气体速度和种类对于减缓偏滤器靶板侵蚀的影响。

边缘局域模（ELMs）是在高约束模状态下发生的一种边缘不稳定性，对于ELMs问题的研究是聚变研究领域的重要课题之一。ELMs会周期性地将粒子和能量从中心等离子体边缘区域排除到刮削层中（SOL），在SOL中输运后载能粒子会沉积在偏滤器（DIV）靶板或者其它面向等离子体部件(PFCs)上。这些高能粒子在DIV靶板产生过高的热负荷，导致靶板材料侵蚀和融化。这对DIV寿命和聚变装置运行有严重的影响。本项目自主开发粒子模拟程序，针对EAST装置发生ELMs的情况下，主要研究ELMs输运对等离子体鞘层，电势和电场分布的影响，根据粒子轰击靶板的物理信息（能量、入射角度、流量等）计算靶板上的能流沉积和侵蚀速率。并且，首次研究了ELMs输运与鞘层演化的关系以及鞘层演化对离子轰击能量的影响。这些模拟结果的取得对于ELMs输运和侵蚀研究具有很好的物理指导意义。