Kobayashi S, Kado S, Oishi T, Kagawa T, Ohshima S, Mizuuchi T, Nagasaki K, Yamamoto S, Okada H, Minami T, Murakami S, Lee H Y, Minami T, Nakamura Y, Hanatani K, Konoshima S, Takeuchi M, Toushi K, Sano F
Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
Rev Sci Instrum. 2010 Oct;81(10):10D726. doi: 10.1063/1.3495787.
This paper describes the application of the beam emission spectroscopy (BES) to Heliotron J, having the nonsymmetrical helical-magnetic-axis configuration. The spectral and spatial profile of the beam emission has been estimated by the numerical calculation taking the collisional excitation processes between plasmas (electrons/ions) and beam atoms. Two sets of the sightlines with good spatial resolution are presented. One is the optimized viewing chords which have 20 sightlines and observe the whole plasma region with the spatial resolution Δρ less than ±0.055 using the newly designed viewing port. The other is 15 sightlines from the present viewing port of Heliotron J for the preliminary measurement to discuss the feasibility of the density fluctuation measurement by BES. The beam emission has been measured by a monochromator with a CCD camera. A good consistency has been obtained between the spectral profiles of the beam emission measured by the monochromator and the beam emission spectrum deduced by the model calculation. An avalanche photodiode with an interference filter system was also used to evaluate the signal-to-noise (S/N) ratio of the beam emission in the present experimental setup. The modification of the optical system is being planned to improve the S/N ratio, which will enable us to estimate the density fluctuation in Heliotron J.
本文描述了束发射光谱（BES）在具有非对称螺旋磁轴配置的Heliotron J装置上的应用。通过考虑等离子体（电子/离子）与束流原子之间的碰撞激发过程的数值计算，估算了束发射的光谱和空间分布。给出了两组具有良好空间分辨率的视线。一组是优化后的观测弦，有20条视线，通过新设计的观测窗口，以小于±0.055的空间分辨率Δρ观测整个等离子体区域。另一组是从Heliotron J现有的观测窗口选取的15条视线，用于初步测量，以探讨利用BES进行密度涨落测量的可行性。束发射由带有电荷耦合器件（CCD）相机的单色仪进行测量。单色仪测量的束发射光谱与模型计算推导的束发射光谱之间取得了良好的一致性。在当前实验装置中，还使用了带有干涉滤光片系统的雪崩光电二极管来评估束发射的信噪比。目前正在计划对光学系统进行改进，以提高信噪比，这将使我们能够估算Heliotron J中的密度涨落。
