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探测器的CCD相机的动态范围以及光谱仪内部光的衍射引起的图像展宽决定。在这项工作中，我们采用了一种读出噪声幅度更小、读出速度更快的CMOS摄像机。通过对CMOS摄像头采集的1500个信号进行平均处理，实现了光电检测的动态范围为106。此外，我们还采用了具有高刻划密度的大透射式光栅，抑制了由于衍射引起的图像展宽。通过这些方法，该谱仪的动态范围达到了106。我们将该谱仪应用于美国国家核聚变科学研究所产生的高温等离子体的观测。我们发展了一种从观测到的氢原子光谱来估计核心等离子体中氢原子密度分布的技术。

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.