高能粒子对托卡马克等离子体中测地声模的影响研究

Geodesic acoustic mode (GAM) is a unique electrostatic oscillation in a toroidal plasma. It is the high frequency branch of zonal flows and plays a significant role in the plasma transport and turbulence control. The present project is to investigate the effects of energetic particles (EPs) on the GAM in a torodially rotating anisotropic tokamak plasma by using gyro-kinetic equations and the hybrid kinetic-fluid model, and to analytically derive the dispersion relation of GAM, beta-induced Alfven eigenmode (BAE), and low frequency zonal flow (LFZF). It is expected to analyze the effects of EPs, toroidal rotation and anisotropy on those modes especially the GAM and be helpful in understanding the evolution of GAM and LFZF in the presence of EPs and toroidal rotation and anisotropy driven by auxiliary heating methods, seeking the physical mechanisms that can suppress instabilities, and fathoming how to control the radial plasma transport and turbulence. Hence, the present project is useful to understand the basic physical phenomenon in ITER and explore better means to control the fusion reactor.

测地声模是环形约束等离子体中特有的一支静电振荡，是带状流的高频分支，对等离子体输运和湍流控制有重要作用。本项目将立足回旋动理学方程和动理学-流体混合模型，研究高能粒子对环向转动各向异性托卡马克等离子体中测地声模、有限beta引起的阿尔芬本征模和低频带状流的作用，解析推导出各低频静电模式的色散关系，分析高能粒子、环向转动和各向异性对上述模式尤其是测地声模频率和稳定性的影响，从而帮助更好地理解测地声模和低频带状流在辅助加热驱动高能粒子、环向转动及各向异性的实验条件下的演化图像，寻求抑制磁流体力学不稳定性的物理机制，探索控制径向等离子体输运和抑制湍流的方法。因此，本项目对理解国际热核聚变实验堆装置中的基础物理现象、探索更好地控制聚变反应堆的方法等方面有重要的意义。

项目执行四年来，我们获得了高阶有限轨道宽度效应对环向旋转托卡马克等离子体中测地声模无碰撞阻尼率的作用；分析了高能粒子的空间分布、各向异性压强和抛射角对测地声模不稳定性判据的影响，着重考察了离子朗道阻尼对高能粒子驱动测地声模的关键作用，进一步获得了尾峰分布高能粒子作用下测地声模发生不稳定性的条件；我们从磁流体和回旋动理学的不同角度出发，获得了测地声模的电磁场信息；探索了测地声模对残余带状流的非线性激发问题；推导出了描述测地声模全局模式的二阶微分方程，详细分析了不同beta条件下测地声模的全局模式；数值考察了双撕裂模不稳定性的本征模特性。总共在国内外杂志上发表论文8篇。上述成果可以帮助寻求抑制磁流体力学不稳定性的物理机制，探索控制径向等离子体输运和抑制湍流的方法。