Diagnostic mirrors with transparent protection layer for ITER

Razdobarin, A. G.; Mukhin, E. E.; Семенов, В. В.; Tolstyakov, S. Yu.; Kochergin, M. M.; Курскиев, Г. С.; Podushnikova, K.A.; Kirilenko, D. A.; Ситникова, А. А.; Konovalov, V. G.; Solodovchenko, S. I.; Nekhaieva, O.M.; Skorik, O.A.; Bondarenko, V. N.; Voitsenya, V. S.

doi:10.1016/j.fusengdes.2011.02.052

Cited by 7 publications

(7 citation statements)

References 7 publications

(9 reference statements)

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“…The films were deposited on the surface of ZrO 2 /Ag/ Al 2 O 3 /Si mirrors (figure 12). The mirrors of this type are to be used in the divertor Thomson Scattering diagnostics in ITER [8].…”

Section: Methodsmentioning

confidence: 99%

“…This is of particular importance for cleaning mirrors with a thin protective oxide coating. In this case the deuterium ion energy should be lower than the sputtering threshold of the oxide layer ~70 eV [8]. For hard-sputtered metal (Mo, W, Rh) mirrors the ion energy is also to be limited with the value of the sputtering threshold of the mirror materials.…”

Section: Implementation Of Cleaning Dischargementioning

confidence: 99%

“…The plasma treatment of chemical compounds may result in surface stoichiometry modification due to the depletion of easily sputtered components like oxygen. In addition, a blistering phenomenon may cause the fast degradation of the mirror surface [8,12]. Therefore, the implementation of the sputtering technique must involve an assessment of its impact on the optical components' performance.…”

Section: Removal Of Al Deposits In Rf CC Dischargementioning

confidence: 99%

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RF discharge forin situmirror surface recovery in ITER

et al. 2015

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Almost all optical diagnostic systems in ITER will require the implementation of mirror recovery and protection systems. Plasma cleaning is considered to be the most promising technique for the removal of metal deposits from optical surfaces. The engineering and physical aspects of RF discharge application for continuous or periodic plasma treatment are discussed with a focus on implementation under ITER conditions. The ion flux parameters obtained in capacitively coupled (CC) RF discharge were measured in the mock-up of a plasma cleaning system. The uniformity of sputtering in CC RF discharge with and without a magnetic field was studied experimentally for the cylindrical discharge reactor geometry and compared with numerical simulations. The sharp increase in the sputtering rate resulting from the non-uniform radial distribution of the ion flux was observed near the electrode edges. The longitudinal magnetic field improves sputtering uniformity. It was demonstrated that Al/Al 2 O 3 deposits can be removed in the Ne and D 2 plasma of CC RF discharge but longterm exposition results in the degradation of the polycrystalline molybdenum mirror surface. The efficiency of Al sputtering in the atmosphere containing O 2 and N 2 fractions was studied in the D 2 /O 2 and D 2 /N 2 plasma of glow discharge. The addition of 2% of oxygen or nitrogen increases the sputtering yield by 3-4 times as compared with that in a nominally pure D 2 discharge. The impact of metal deposits on the performance of diagnostic mirrors is discussed. It was shown that an ultrathin metallic film with a thickness as low as a few nm may cause a significant degradation of diagnostic mirrors with a transparent coating.

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“…The films were deposited on the surface of ZrO 2 /Ag/ Al 2 O 3 /Si mirrors (figure 12). The mirrors of this type are to be used in the divertor Thomson Scattering diagnostics in ITER [8].…”

Section: Methodsmentioning

confidence: 99%

Section: Implementation Of Cleaning Dischargementioning

confidence: 99%

Section: Removal Of Al Deposits In Rf CC Dischargementioning

confidence: 99%

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RF discharge forin situmirror surface recovery in ITER

et al. 2015

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“…In the case of metal film-coated mirrors, the film has to be thick enough to guarantee a reasonable lifetime. Although possible in principle to find ways of dealing with high levels of CXA erosion by selecting the mirror material, it is more difficult to deal with deposition [49]. In practice, therefore, every design for a long-life FM must incorporate a strategy for the reduction of the net deposition rate, the protection of the FM from unnecessary exposure to contaminant flux, mitigation of the effects of deposition on the measurement, and a maintenance strategy to restore performance, see [3] for an extended discussion of these problems.…”

Section: First Mirrors (Fm)mentioning

confidence: 99%

Functional materials for tokamak in-vessel systems—status and developments

2017

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The challenge to be faced in ITER and DEMO, as well as future fusion power plants (PPs), by the insulating (functional) materials for use not only in the magnetic coils and heating systems but for safety and control diagnostics is daunting. The available data on thermomechanical properties (strength, swelling, thermal conductivity) indicate that suitable materials are available for doses >1 dpa. However, for the important physical properties which degrade at far lower doses, data are generally only available for doses 1 dpa, corresponding at most to ITER expectations. To address this, the selection and development of potential radiation hard materials and components for diagnostic, H&CD, and other systems for DEMO and PPs is urgently needed, and will also assist in defining the materials test requirements for materials test reactors and IFMIF. This paper reviews the current data and basic knowledge for materials required for optical, DC electric, and AC/RF dielectric applications. A short discussion of the associated R&D needs/requirements deduced from missing or limited irradiation data is also presented.

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“…The preparation of such coated mirrors was reported by magnetron sputtering [3,14], evaporation [15] and pulsed laser deposition (PLD) [16][17][18] technique for Rh, Mo and W coatings. Silver and aluminum coatings with a thick protective dielectric layer with low rate of sputtering and chemical modification (Al2O3, ZrO2) were also investigated [19,20]. The ZrO2 films deposited at room temperature were found to have good homogeneity without microcrystalline inclusions.…”

Section: Realisation Of Coated Mirrorsmentioning

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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Diagnostic mirrors with transparent protection layer for ITER

Cited by 7 publications

References 7 publications

RF discharge forin situmirror surface recovery in ITER

RF discharge forin situmirror surface recovery in ITER

Functional materials for tokamak in-vessel systems—status and developments

Optical Coatings as Mirrors for Optical Diagnostics

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