EAST上离子回旋模转换波和低杂波协同电流驱动的研究

In order to achieve the important goal of the scientific apparatus：EAST Superconducting tokamak-long-pulse high-parameter H-mode operation, aiming at the problem of the rapid decline of lower hybrid current drive efficiency in high-density conditions in EAST experiments. In this project, a study on synergistic ICRF mode converted wave and lower hybrid wave current drive in EAST will be carried out. Quasilinear Fokker-Planck equation with the two waves (including two-wave quasi-linear diffusion terms) by combining the ray-tracing method and the full wave method will be solved numerically, the physical mechanism of the two-wave synergy will be theoretically analyzed. the role of the synergistic two waves current drive on improving current drive efficiency, filling “spectrum gap” of lower hybrid current drive and controlling current profile will be investigated, the key factors and parameters will be found, local heating by the mode converted wave will also be considered. Finally, the optimal methods and parameters of enhancing the current drive efficiency and controlling the current profile flexibly will be obtained. The project is of great significance to the EAST experiment with radio-frequency wave current drive.

为实现我国的大科学装置全超导托卡马克EAST上的重要目标-长脉冲高参数H模运行，针对目前实验中遇到高密度参数下低杂波电流驱动效率快速下降等问题，本项目拟开展针对EAST的离子回旋模转换波和低杂波协同电流驱动研究。通过联合射线追踪法、全波方法，数值求解两波作用下(包含两波准线性扩散项）的准线性Fokker-Planck方程，理论上分析两波协同效应的物理机制，数值模拟研究两波协同驱动对提高电流驱动效率、填补低杂波电流驱动谱间隙以及控制电流剖面的作用，找到影响协同电流驱动效果的因素和关键参数，考虑离子回旋模转换加热导致局部电子温度的提升，获得利用两波协同电流驱动提高电流驱动效率、灵活有效控制电流剖面的优化方案和参数空间。为EAST上实现更高效的电流驱动、更有效的主动电流剖面控制提供参考。

针对目前EAST实验中遇到的高密度参数下低杂波电流驱动效率快速下降等问题，本项目开展分别针对EAST低βe和高βe放电实验的离子回旋高谐快波和低杂波协同电流驱动理论模拟研究。通过对双波协同作用情况下（叠加两波准线性扩散项）描述电子分布函数演化 的准线性 Fokker-Planck 方程求解，发现两波联合电流驱动存在显著的协同效应，即联合驱动电流大于两支波单独驱动电流之和，协同效应导致电流驱动效率被提升到原来的2倍，电流分布被控制在期待的离轴区域（r/a=0.2-0.5），局部协同因子可达到到4.38。并明晰了协同效应产生的物理机制，获得了两波协同电流驱动的优化参数和方案。为实现我国的大科学装置全超导托卡马克EAST上改善射频波电流驱动昂效果和重要目标-长脉冲高参数H模运行有着重要积极的意义，发现这种新的协同效应也为国际上开展相关研究提供基础。