ITER diagnostic challenges

Walsh, Michael J.; Andrew, P.; Barnsley, R.; Bertalot, L.; Boivin, R. L.; Bora, D.; Bouhamou, R.; Ciattaglia, S.; Costley, A. E.; Counsell, G.; Direz, M.-F.; Drevon, J.-M.; Encheva, A.; Fang, T.; Hellermann, M. von; Johnson, D.; Kim, J.; Kusama, Y.; Lee, H. G.; Levesy, B.; Martín, A.; Maquet, P.; Okayama, K.; Reichle, R.; Patel, Kaushal; Pitcher, C.S.; Prakash, Arun J.; Simrock, S.; Taylor, Neill; Udintsev, V. S.; Utin, Y.; Vasu, P.; Vayakis, G.; Veshchev, E.; Schunke, B.; Walker, Chris; Watts, Christopher; Zvonkov, A. V.

doi:10.1109/sofe.2011.6052210

Cited by 18 publications

(11 citation statements)

References 15 publications

(12 reference statements)

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“…A Renishaw inVia Raman spectrometer using the 514.5 nm wavelength of an argon (Ar) laser was exploited to determine the chemical and structural properties of the samples. In addition, the specular reflectance (R spec ) of the Rh mirrors (before contamination, after contamination and after cleaning) was determined subtracting the diffuse reflectance (R diff ) from the total reflectance (R tot ), both measured by a UV-vis-NIR PerkinElmer Lambda 1050 spectrophotometer with a 150 mm Spectralon integrating sphere in the 250-1800 nm wavelength range, of interest for most ITER diagnostics [1].…”

Section: Experimental Set-up and Mirror Productionmentioning

confidence: 99%

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Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

et al. 2016

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This paper presents a laboratory-scale experimental investigation about the laser cleaning of diagnostic first mirrors from tokamak-like contaminants, made of oxidized tungsten compounds with different properties and morphology. The re-deposition of contaminants sputtered from a tokamak first wall onto first mirrors’ surfaces could dramatically decrease their reflectivity in an unacceptable way for the proper functioning of plasma diagnostic systems. The laser cleaning technique has been proposed as a solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as first mirrors and to deposit onto them contaminants designed to be realistic in reproducing materials expected to be re-deposited on first mirrors in a tokamak environment. The same laser system was also used to perform laser cleaning experiments, exploiting a sample handling procedure that allows one to clean some cm2 in a few minutes. Cleaning effectiveness was evaluated in terms of specular reflectance recovery and mirror surface integrity. The effect of different laser wavelengths ( λ = 1064 , 266 nm) on the cleaning process was also addressed, as well as the impact of multiple contamination/cleaning cycles on the process outcome. A satisfactory recovery of pristine mirror reflectance (⩾90%) was obtained in the vis–NIR spectral range, avoiding at the same time mirror damaging. The results here presented show the potential of the laser cleaning technique as an attractive solution for the cleaning of diagnostic first mirrors.

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Section: Experimental Set-up and Mirror Productionmentioning

confidence: 99%

“…Metallic first mirrors (FMs) will be crucial components of all optical systems for plasma diagnostics and imaging tools in ITER [1,2]. They must survive a harsh environment consisting of intense thermal loads, strong radiation fields and high particle fluxes.…”

Section: Introductionmentioning

confidence: 99%

Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

et al. 2016

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“…It is enough to compare values of recorded signals with well‐known reference values and based on this comparison conclude about technical state of the object. The situation becomes more complicated when more complex objects (e.g., mining machinery, turbines, engines, or some specialized technical objects as International Thermonuclear Experimental Reactor [Walsh et al, ], and so forth. ), for which there is the possibility to record a huge number (several thousands) of signals, are considered.…”

Section: Introductionmentioning

confidence: 99%

Requirements‐based approach for the diagnostic systems design process

Amarowicz

2018

Expert Systems

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The process of effective diagnosis of the technical state of an object is an essential task related to its utilization. For this purpose, appropriately developed diagnostic systems are used. However, the process of their elaboration is very difficult because it is necessary to consider very wide domain knowledge during this process—for example, information about the object's structure, possible faults, results of risk analysis, and available diagnostic methods. Generally, in the literature, there are no adequate methods for the purpose of designing diagnostic systems. In this article, a new design approach for this purpose is proposed. It is based on some elements of requirement engineering and the selected methods of artificial intelligence. The main assumptions of the proposed design approach rely on the use of sets of requirements to describe the expected functionalities of the diagnostic system. Each of the requirements is connected with proper faults that may occur during the operation of the considered object, is described by a set of attributes, and implies the partial solution of the diagnostic system. A gathered set of requirements is evaluated using the expert system, such as the inference process in Bayesian networks. The structure of these networks depends on the obtained notation of the requirements. As a result of an evaluation of the set of requirements, based on the data that describe the considered object and the assumed criteria that describe the limitations, a subset of requirements that describe the optimal solution of the diagnostic system is isolated.

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“…Therefore, metallic mirrors are foreseen to play a key role in guiding the plasma light towards the optical diagnostics. As these so-called first mirrors (FM) directly view the plasma, they will be subjected to a harsh environment of particle fluxes due to charge exchange neutrals and neutrons, as well as UV, x-ray and gamma radiation [1].…”

Section: Introduction *mentioning

confidence: 99%

Optical Coatings as Mirrors for Optical Diagnostics

Marot

Arnoux

Huber

et al. 2016

J. Coat. Sci. Technol.

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The aim of this work was to provide a comprehensive insight concerning coated films which might be used for first mirrors in ITER. The influence of the mirror crystallite size has been addressed as well as the coating techniques to provide nanocrystalline films. Tests of coated mirrors both in laboratories and in tokamaks are reviewed. For the tokamak tests a wide angle camera system has been installed in JET-ILW which is composed of a mirror box with 3 stainless steel mirrors coated with rhodium viewing the torus through a conically shaped aperture. The system delivered the required image quality for plasma monitoring and wall protection. No or insignificant degradation of the optical transmittance has been observed during the experimental campaign in 2014 with about 3000 plasma pulses in different magnetic field configurations.

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ITER diagnostic challenges

Cited by 18 publications

References 15 publications

Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

Requirements‐based approach for the diagnostic systems design process

Optical Coatings as Mirrors for Optical Diagnostics

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