Development of compact multi-channel ultra soft X-ray spectrometer for high-accuracy particle transport measurement

通过使用示踪剂封装固体颗粒（TESPEL）和电荷交换复合光谱（CXS）的组合，可以高精度地评估杂质输运系数。本研究项目的目标是开发一种紧凑的多通道超软x射线（USXR）光谱仪，这是使用高能中性束进行CXS诊断所必需的。我们采用了由网格准直器和多层反射镜组成的光学系统，以达到紧凑和高吞吐量的目的。我们利用上述光学系统制作了一台单通道USXR光谱仪样机。在大型螺旋装置（Large Helical Device， LHD）上进行实验时，LHD等离子体工作气体意外流入USXR光谱仪样机，导致MCP探测器在高压下损坏。为了解决这个问题，我们修改了光谱仪的设计，并安装了带低温泵的差动泵系统。不幸的是，由于对抗工作比预期的时间要长，我们无法从改进的光谱仪上获得实验数据。然而，我们在利用现有光谱仪研究由TESPEL注入引入的示踪杂质离子的USXR发射方面取得了进展。已经开发了几个计算代码，这些代码对于使用杂质输运代码计算杂质输运系数是次要必要的。虽然多通道USXR光谱仪的开发还有待完成，但由于光学系统的紧凑性，这里采用的光学系统可以很容易地对准成扇形。

Impurity transport coefficients can be evaluated with a high degree of accuracy by using a combination of a tracer-encapsulated solid pellet (TESPEL) and a charge exchange recombination spectroscopy (CXS). The goal of this research project is the development of a compact multi-channel ultra soft X-ray (USXR) spectrometer, which is necessary for the CXS diagnostic with a high-energy neutral beam. We adopted the optical system that consists of a grid collimator and a multilayer mirror, for achieving the compactness together with the high throughput. We produced a prototype one-channel USXR spectrometer with the above optical system. During the experiment on the Large Helical Device (LHD), a working gas for LHD plasmas flowed accidentally into the prototype USXR spectrometer, and then MCP detectors with being applied a high voltage was damaged. To fix this problem, the design Of the spectrometer is modified and we proceed with the installation of differential pumping system with a cryopump. Unfortunately, since the countermeasure work takes a longer time than anticipated, we cannot obtain the experimental data from the modified spectrometer. However, we made progress in the research using existing spectrometers for studying USXR emissions from the tracer impurity ions introduced by the TESPEL injection. Several calculation codes, which are necessary secondarily for the calculation of the impurity transport coefficients using an impurity transport code, have been developed. Although the development of the multi-channel USXR spectrometer remains to be done, it can be easily done by aligning the optical system adopted here in a fan shape, owing to the compactness of that.