【作者】 柯锐；

【导师】 高喆； 许敏；

【作者基本信息】 清华大学 ， 核科学与技术， 2018， 博士

【摘要】 边缘等离子体湍流是制约托卡马克约束性能的关键。边缘区剪切流湍流的非线性相互作用是边缘区湍流的主要抑制机制之一。这种非线性相互作用将湍流的能量传递给了带状流。在以往实验中,使用零维模型下,湍流与带状流的相互作用仅包含了能量传递过程。但这一简单近似在实验中进行局域测量时并不适用。通过理论分析和实验验证可知,对于局域测量,湍流与带状流体系的非线性过程,除两者之间的能量交换外,还包括湍流通过雷诺胁强作用使得带状流在径向上发生再分布的过程,以及湍流不同成分间的相互作用导致的湍流在空间上的扩散过程。当考虑到这两个能量在空间上的再分布过程后,可以得到湍流与带状流体系的能量平衡。在HL-2A装置上,通过扫描ECRH的加热功率,发现带状流的分支测地声模与湍流的能量传递过程随着加热功率的升高而增强,同时其非线性增长率也不断上升。在研究边缘湍流的能量平衡时,无法使用静电探针对于高加热功率条下边缘湍流以及与芯部和刮削层区湍流相互作用的研究。为此,在HL-2A装置上发展了一套先进的束发射谱诊断系统。通过优化的光路设计,高灵敏度的探测器和低噪声水平的前置放大器设计,最终使得整套系统的空间分辨率达到了1 cm(径向),1.5 cm(极向),时间分辨率达到0.5μs,整体性能达到国际先进水平。目前已经安装完成了16道(2×8)系统,覆盖外中平面附近r=26~42 cm的范围,可以为湍流能量平衡的进一步研究提供诊断支持,也能够为磁流体不稳定性和高能粒子的研究提供数据。更多还原

【Abstract】 Edge turbulence is believed to be the key of tokamak confinement.The nonlinear interaction between turbulence and edge shear flows is one of the main mechanisms of turbulence suppression.This nonlinear process could transfer the energy from turbulence to shear flows.In early experimental research,by applying the zero-dimensional model,this process is nothing more than energy transfer.However this hypothesis is not applicable for localized measurement in experiments.By theoretical and experimental study of the interaction between turbulence and shear flows,besides the energy transfer,the nonlinear interaction includes the spacial redistribution of shear flows driven by Reynolds stress and turbulence spreading induced by nonlinear coupling between different modes for localized measurement as well.When considering the kinetic energy redistribution process of turbulence and shear flows,both energy budgets can be balanced.The ECRH power scanning experiments on the HL-2A tokamak shows that the energy transfer between one branch of the zonal flows,geodesic acoustic modes(GAMs)and turbulence,as well as the nonlinear growth rate of GAMs increases monotonically with ECRH power increasing.The Langmuir probe array is not suitable for experimental studies of turbulence energy balance in high-performance discharge with high auxiliary heating power.An advanced beam emission spectroscopy system is developed on HL-2A tokamak for turbulence measurement.By optimizing the optics design,using high-sensitive detectors and low-noise design of pre-amplifier,the BES system could achieve a high time resolution of 0.5 μs,high spatial resolution of 1 cm radially and 1.5 cm poloidally,providing an advanced performance in the world.At present,16-channel(2×8)BES system has been installed on HL-2A tokamak,covering a range of r = 26 ~ 42 cm near outer middle plane.Thus it is able to provide data for turbulence energy balance and other studies like MHD instability and energetic particles.更多还原