The development and design of the CXRS diagnostic for the core plasma of ITER is used as a pretext to elaborate on several of the main challenges of optical diagnostics on such a large fusion device. The idea was to confront the students of the 16th Ettore Majorana School on Diagnostics and Technology Developments with as many aspects of the design of optical diagnostics as possible. After an elementary review of the basics of charge-exchange, of typical spectra, of intended measurements and of the expected associated background, the DNB (diagnostic neutral beam) is briefly presented. The light collection and transport to the ex-vessel fibres and spectrometers constitutes the main part of this contribution: building on existing telescope and endoscope systems, the choice of a suitable optical layout for the core-plasma CXRS diagnostic at ITER is discussed. An account follows of the protective measures against the degradation of the first mirror, which will be exposed to high particle and heat fluxes: an appropriate duct, a shutter and, possibly, a cleaning discharge with “End-of-Cleaning Indicator”.

中文翻译：

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ITER 的核心等离子体 CXRS 诊断：当前设计简介

以 ITER 核心等离子体 CXRS 诊断的开发和设计为借口，详细阐述了对如此大型聚变装置进行光学诊断的几个主要挑战。这个想法是让第 16 届 Ettore Majorana 诊断和技术发展学院的学生尽可能多地了解光学诊断设计的各个方面。在对电荷交换的基础知识、典型光谱、预期测量和预期相关背景进行基本回顾之后，简要介绍了 DNB（诊断中性光束）。光收集和传输到船外光纤和光谱仪构成了这一贡献的主要部分：建立在现有的望远镜和内窥镜系统的基础上，讨论了为 ITER 的核心等离子体 CXRS 诊断选择合适的光学布局。下面介绍了防止第一面镜子退化的保护措施，第一面镜子将暴露在高粒子和热通量下：适当的管道、百叶窗，可能还有带有“清洁结束指示器”的清洁排放口。