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The Core-Plasma CXRS Diagnostic for ITER: An Introduction to the Current Design

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Abstract

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”.

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Acknowledgements

This work was partly supported by the German Federal Ministry of Education and Research (BMBF Grant No. 03FUS0007) and by the ITER Organization in the framework of service contract ITER/CT/12/4300000546. A few of the later results were obtained under F4E-FPA-408 (DG), a partnership with Fusion for Energy, the European domestic agency to ITER. The views expressed here are the sole opinion of the author. He is indebted to his colleagues W. Biel, O. Marchuk and N. Hawkes for their constructive and helpful remarks. The support and contributions of all members of the \({\textit{IC}}^3\) consortium (ITER Core Charge-exchange Consortium) are gratefully acknowledged—\({\textit{IC}}^3\) is the ad hoc consortium to design and build the core-plasma CXRS diagnostic in the Upper Port Plug No. 3 of ITER.

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Mertens, P. The Core-Plasma CXRS Diagnostic for ITER: An Introduction to the Current Design. J Fusion Energ 38, 264–282 (2019). https://doi.org/10.1007/s10894-018-0202-1

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