托卡马克等离子体主动电荷交换复合光谱诊断的理论和实验研究

Recently years,Charge eXchange Eecombination Spectrum（CXRS） diagnostics from the Neutral beam injected (NBI) heating is a standard technique, especially in the ion temperature and plasma toroidal rotation velocity measurement. As long as the NBI occurred in the Tokamak, the electron is transferred from a neutral atom to an impurity ion called bare nucleus which are fully ionized. Because of the transfer process, these ions would be in some excited state, they emit some lines of lights. These emission lines have Doppler broadened and shift components as a result of ion thermal motion and toroidal rotation. These emission lines' shapes are used to extract values for the plasma parameters..This research is about the CXRS diagnostics built on the magnetic confinement HL-2A Tokamak,on which the profile measurement of impurity ion temperature and toroidal rotation velocity could be achieved. Considering the edge effect of the line of CVI 529.06nm (n= 8-7), which contains three lines: active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE), and also considering the instrument and Zeemann broadens effects, comparing with the Doppler broaden, which is predominant, It could arrive at the accurate impurity ion temperature and toroidal plasma rotation velocity profile under the condition of NBI heating is on..The new diagnostic system will have some optimize designs. First of all, absolute calibration of the spectrum system was carried on by using integrating sphere. Secondly, several methods had been introduced to the diagnostic system, such as optimizing design of light path using software called ZEMAX, decreasing the number of optical devices to the greatest extent, reducing the loss of optical signal by choosing low loss fiber, anti-reflection film on the high quality optical glassed. Meanwhile, in order to eliminate optical lenses sphere aberration and improve the quality of images of focal plane in the spatial discrimination (slit) and spectrum discrimination, two kinds of reflected mirrors (with different curvature radius) were used. Thirdly, it enable the diagnostic system maximum limit the background stray light coming from the wall by means of reasonable optical path arrangement, wall materials which could eliminate stray light. Fourthly, effective shielded metal wire mesh was used to deduce the interference to the system from plasma discharge. Fifthly, it devoted to complete the data analyzed software, more optimize the measurement system according to the experimental results. .All in all,this NSFC proposal research deals with the measurement which is used in the CXRS diagnostic system that built on HL-2A Tokamak.

电荷交换复合光谱诊断是一种先进的主动光谱诊断技术，具有电荷交换截面大、谱分辨率高等显著优点。此技术在国内外各聚变装置已有广泛的应用，但是在国内获取的相关物理参数还不是十分丰富。本项目基于HL-2A托卡马克装置建立的主动电荷交换光谱诊断系统，开展等离子体相关参量及时空分布的诊断；初步探索中性束注入对聚变等离子体旋转的驱动机制；研究等离子体光谱多道空间测量中的弱光探测技术；利用均匀光源系统研究绝对定标技术；研发相关数据分析软件以补充国内大型托卡马克装置的诊断分析软件库。同时针对电荷交换光谱诊断过程中遇到的难题：塞曼展宽和仪器展宽对计算多普勒展宽的影响；被动电荷交换光谱和电子碰撞激发光谱等寄生信号的干扰；优化硬件系统以提升弱光采集系统的效率等，提出切实有效的解决方案。该项目所得到的物理参数对研究聚变装置内部能量输运、杂质输运、加热机制以及从低约束模式到高约束模式转换等物理问题具有重要意义。

本项目所采用的诊断方式，电荷交换光谱诊断系统具有以下一些特征：1.电荷交换截面大，表现在两个方面：其一，相对其它辐射大10～100倍；其二，杂质原子序数越大发生电荷交换的截面越大。2. CXRS谱辐射谱线波段分布主要从可见光到紫外波段，而在实验诊断中主要利用可见波段区。可见波段的光谱具有光谱分辨率高、有利于光纤使用和具备相对较灵敏的探测器等硬件条件。CXRS诊断系统已经在HL-2A聚变装置上建立起来，所得到的结果也已经非常丰富，尤其是在高约束模（H模）运行下的诊断结果对稳态控制极为重要。研究主要集中在对已有的CXRS诊断结果进行分析，得到等离子体基本参量及时空分布进行高精度、高分辨率的测量。. 本项目基于HL-2A托卡马克装置建立的主动电荷交换光谱诊断系统，开展了等离子体相关参量及时空分布的诊断（得到了杂质离子温度和环向旋转速度随着大半径和时间变化的趋势）；研究了等离子体光谱多道空间测量中的弱光探测技术（得到了设计光路图，依据设计光路加工多道弱光探测系统）；同时针对电荷交换光谱诊断过程中遇到的难题：塞曼展宽和仪器展宽对计算多普勒展宽的影响（采用数值模拟的方法对结果进行了分析）；被动电荷交换光谱和电子碰撞激发光谱等寄生信号的干扰，得到了信噪比SNR随等离子体参数变化的趋势（采用SOS模拟程序对信噪比随着实验条件变化的趋势进行了预测）；优化硬件系统以提升弱光采集系统的效率（设计倾角改变的透镜组，高透光率光纤，大数值孔径光谱仪进行实验设计），提出切实有效的解决方案。该项目所得到的物理参数对研究聚变装置内部能量输运、杂质输运、加热机制以及从低约束模式到高约束模式转换等物理问题具有重要意义。