【作者】 王平；

【导师】 高喆；

【作者基本信息】 清华大学 ， 核科学与技术， 2009， 硕士

【摘要】 湍流输运一直是磁约束聚变等离子体物理中的核心问题之一。最近的研究发现,湍流的自组织带状流可以有效地减弱湍流输运,提高等离子体约束水平。测地声模(GAM)作为带状流的高频分支,对其进行研究就显得非常必要。本文利用环动理理论,采用局域平衡模型,研究了等离子体截面形状和有限环径比对测地声模的影响。首先,通过小量渐近展开,论文得到了GAM频率随拉长比和环径比变化的解析结果。结果显示,随着拉长比增加,GAM频率明显减小;而随着逆环径比的增加,GAM频率也会略有减小。因此,随着等离子体形变的增强,测地声模的频率会明显减小,相应地,阻尼率会显著增强。论文还开发了一套适用于研究有限环径比、非圆截面等离子体中测地声模的程序代码。利用此程序代码,可以通过数值方法对所有等离子体形状参数(包含有限环径比、沙夫拉诺夫位移、拉长比、三角形变)对测地声模的频率和阻尼率的影响进行研究。更多还原

【Abstract】 Turbulence transport is one of key topics in magnetically confined fusion plasma physics. Recent researches show that zonal flows can effectively moderate the turbulence transport, and thus, improve the confinement of plasma. Therefore, the geodesic acoustic mode(GAM), the high frequency branch of zonal flows, has received increasing attention. In the thesis, with the gyrokinetic theory and the local magnetohydrodynamic equilibrium model, effects of plasma shape and finite aspect ratio on the GAM are studied. Firstly, using the asymptotically expanding method, we find the dependence of the GAM frequency on the elongation and inverse aspect ratio analytically. It is shown that, when the elongation increases, the frequency dramatically decreases, while when inverse aspect ratio increases, the frequency slightly decreases as well. It means, in strongly shaped plasmas, the GAM frequency is quite low and then the damping becomes strong. In the last part of the thesis, a numerical code is developed based on our gyrokinetic model of the GAM. With this code, effects of all plasma shaping parameter, such as finite aspect ratio, Shafranov shift, elongation and triangularity, can be studied numerically.更多还原