聚变装置中被约束快离子密度、温度分布测量及其数值模拟研究

Fast ions in the current and future fusion research are generated by fusion reactions, by injection of neutral beams, and by RF acceleration. These fast ions (non-Gaussian anisotropic suprathermal ion) not only have an important influence on the wall safety during the device operation , but also happen to be the main sources in the transport studies of plasma energy, current, momentun, and particle confinement. Evenmore plasma instabilities have some relation with the fast ions. All these jobs require accurate knowledge of the fast ion profile. In this application a fast-ion deuterium alpha(FIDA) diagnostic system, which is based on the heating neutral beam , will be set up in HL-2A tokamak. The unique contribution of the FIDA is that it allows measurement of the fast ions inside the plasma rather than the escaping fast ions in the fusion device.The ruslts will contribute a different view of the fast ion distribution to the fusion research.This is the reason why many fusion device (such as DIII-D, ASDEX-U, LHD)in the world carry out the diagnostic though the technology started to develop in 2004. The density and temperature of the confined fast ions will be obtained by this diagnostic. Acccording to the diagnostic system, the simulation code will be developed to analyze the related physics of the fast ions. The study about confined fast ions will improve and deepen our understanding of the fast ions in the fusion plasma. Southwestern Institute of Physics (SWIP) is the only one in China that has the capability to inject the high powerful neutral beam into plasma, and we have successfully developed the Charge eXchange Recombination Spectroscopy (CXRS) diagnostic based on this heating beam. The principle of new measurements is similar with the CXRS, so our experience will provide tremendous help to carry out this new work in our application.

在聚变研究中高能快离子不但是聚变产物,也是高功率中性束和波加热的产物。它们不仅对聚变装置的壁安全有重要影响，而且也是等离子体内部的动量、能量和离子输运的来源，甚至还可能产生某些不稳定性。本申请拟依托国内唯一成熟运行的高能加热中性束，通过对电荷交换复合谱（CXRS）系统进行改造，率先在HL-2A托卡马克装置上建立一套快离子Da测量系统。新系统的特色之处是：它专门测量等离子体中被约束的快离子，而非从等离子体中逃逸出来的快离子。通过该系统将得到HL-2A中被约束快离子的密度和温度的分布。同时还将发展一套约束高能粒子的模拟分析代码，来拓宽和加深研究者对被约束快离子的行为和相关物理的理解。本项目申请的测量方法和电荷交换复合谱（CXRS）的测量原理类似，也是最近几年国际上主要聚变装置大力发展的测量。申请者在CXRS项目中的成功经验将为该项目的开展奠定坚实基础。

本项目“聚变装置中被约束快离子密度、温度分布测量及其数值模拟研究”自项目启动以来，项目组根据研究内容和研究目标任务，在HL-2A托卡马克装置上研制了快离子分布诊断系统，发展了快离子数值模拟程序，在中性束加热期间开展了快离子分布测量、MHD及破裂等引起的快离子约束行为变化等相关的物理研究。（1）研制一套高时空分辨快离子Da（FIDA）诊断系统，实现对HL-2A托卡马克装置上快离子径向分布的高时空分辨测量，其中的时间分辨率10ms，空间分辨率5cm，具体包括研制一套适合微弱光探测且具有高通光效率的光谱测量系统，解决了强背景辐射中微弱信号探测及其分辨问题的方法，根据诊断窗口和选用的诊断仪器参数设计一套光学采集系统，解决光谱强度的绝对标定（特别是滤光片后的信号强度标定）；（2）开发数据分析处理软件包，完成一套数据分析软件, 能自动计算快离子分布测量系统的实验数据。（3）在HL-2A装置上中性束加热期间开展了快离子约束等相关的物理研究，研究了破裂导致的约束快离子输运损失，首次观察到高频MHD引起的快离子输运行为等现象。.项目实施三年来，共发表与本课题研究内容相关的文章17篇，参加会议10余人次，专利申请1项，在诊断和物理实验方面培养了2名技术骨干和2名硕士研究生。