Development of ultra-high dynamic rage spectroscopic method for evaluation of neutral hydrogen density distribution in fusion core plasmas

传统光谱仪的动态范围由用作光电检测器的CCD相机的动态范围以及由于光谱仪内部的光的衍射而导致的图像展宽来确定。在这项工作中，我们采用了CMOS相机，它具有较小的读出噪声幅度和更快的读出速率比CCD相机。通过对CMOS相机拍摄的1500个信号进行平均，我们实现了106的照片检测动态范围。此外，通过采用具有高刻线密度的大透射光栅，我们抑制了由于衍射引起的图像展宽。利用这些方法，使谱仪的动态范围达到106，并将其应用于核聚变研究所的高温等离子体观测。我们开发了一种技术，估计氢原子密度分布的核心等离子体从观察到的氢原子光谱。

The dynamic-range of a conventional spectrometer is determined by the dynamic range of a CCD camera used as a photo detector, as well as the image broadening due to the diffraction of light inside the spectrometer. In this work, we adopt a CMOS camera which has smaller readout noise amplitude and faster readout rate than those of CCD cameras. By averaging 1500 signals taken by the CMOS camera, we achieve the dynamic range of 106 in photo detection. Additionally, by adopting a large transmission grating with high ruling density, we suppress the image broadening due to the diffraction. The dynamic range of 106 of the spectrometer is achieved by these approaches.We apply this spectrometer to the observation of high temperature plasmas produced in National Institute for Fusion Science. We develop a technique to estimate the hydrogen atom density distribution in the core plasma from observed hydrogen atom spectra.