模拟研究射频波鞘层边界对边界局域模及其湍流输运的影响

项目名称： 模拟研究射频波鞘层边界对边界局域模及其湍流输运的影响

项目编号： No.11505236

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 桂彬

作者单位： 中国科学院合肥物质科学研究院

项目金额： 23万元

中文摘要： 本项目在圆位形中，引入射频波鞘层边界，利用BOUT++框架下的六场物理模型，研究射频波鞘层边界对边界局域模及其湍流输运的影响，为在偏滤器位形中模拟射频波鞘层边界对边界等离子体的影响和ELMs在偏滤器靶板上的热流沉积打下基础。在模拟中，我们将射频波天线及其保护限制器放置在圆位形刮削层的最外中平面上，文中所说的限制器也特指保护天线的限制器。在托卡马克等离子体中，射频波是加热等离子体的主要手段之一。当磁场不能与天线完全耦合时，射频波会在刮削层中产生一个慢波分量，其平行电场会改变刮削层中电子离子向限制器表面的运动，形成射频波鞘层边界。射频波鞘层边界不仅改变了刮削层内的平衡电势分布，通过旋转动量的径向输运，也会改变分离面内侧附近的平衡电势。径向电场引起的剪切旋转，会影响到边界局域模的爆发及其湍流输运过程。同时刮削层中的鞘层边界也会影响局部的湍流输运，进而影响限制器表面的热流分布。

中文关键词： 数值模拟；流体模型；射频波鞘层边界；边界局域模；湍流输运

英文摘要： In this program, the RF sheath boundary condition is applied in the six-field two-fluid model and shift-circle geometry under BOUT++ framework. The effect of RF sheath boundary condition on the edge localized mode and the turbulent transport is studied. This program will be the foundation of the future work which will study the effect of RF sheath boundary on the edge plasma and the heat flux on the divertor target due to the ELM under divertor geometry. In the simulation, the RF wave antenna and the protecting limiter are placed at the outer middle plane in SOL, while the ‘limiter’ below refers in particular to the protecting limiter. RF wave is the primary heating method in Tokamak experiments, including EAST and ITER. Imperfect alignment of the equilibrium magnetic field with respect to the antenna and walls can generate unwanted slow waves. The parallel electric field will affect the thermal motion of electron and ion toward the limiter and result in the RF sheath boundary condition. The RF sheath boundary condition not only changes the electric potential in SOL, but also changes the electric potential inside the separatrix through the momentum transport. The shear flow due to this radial electric field will affect the ELM and its turbulent transport. On the other hand, the sheath boundary condition in SOL will also locally affect the turbulent transport and then affect the heat flux distribution on the limiter surface.

英文关键词： numerical simulation;fluid model;Radio-Frequency sheath boundary condition ;Edge localized modes;turbulent transport