Concept design of ultrafast charge exchange recombination spectroscopy on EAST tokamak

An ultrafast charge exchange recombination spectroscopy (CXRS) has been constructing for the measurement of the plasma ion temperature and rotation velocity fluctuations on EAST tokamak. The system shares the collection optics with the existing BES. The designed spectrometer operates at the spectral range of 527.5 ± 5 nm, then the emission lines from C VI at 529.059 nm and Ne X at 524.897 nm can be observed simultaneously. The collimating and focusing lenses are specially designed to realize the maximized transmission (˜95% for each lenses) and the optimized image quality. One customized transmission grating sandwiched by two identical BK7 prisms from Wasatch Photonics is used. The clear size of the grating is ˜205 × 100 mm and the grating has very high diffraction efficiency of > 80% for unpolarized light. The Simulation of Spectra code is used to guide the design and evaluate the diagnostic performance. In this paper, an overview of the status and performance of the ultrafast CXRS system will be presented.

本研究为EAST托卡马克装置上的等离子体离子温度与旋转速度涨落测量需求，搭建了一套超快电荷交换复合光谱诊断（CXRS）系统。该系统与现有束发射光谱（Beam Emission Spectroscopy, BES）共享收集光学系统。所设计的光谱仪工作光谱范围为527.5±5 nm，可同时观测到碳六价离子（C VI）在529.059 nm处与氖十价离子（Ne X）在524.897 nm处的发射谱线。准直与聚焦透镜均经过特殊优化设计，以实现最大化的光传输效率（单透镜传输效率约95%）并获得最优成像质量。系统采用沃萨奇光子学（Wasatch Photonics）定制的透射光栅，该光栅由两块相同的BK7玻璃棱镜夹持，光栅有效通光尺寸约为205×100 mm，对非偏振光的衍射效率高于80%。本研究使用光谱模拟（Simulation of Spectra）代码指导系统设计并评估诊断性能。本文将对这套超快CXRS系统的研制现状与整体性能进行综述介绍。