Removal of beryllium-containing films deposited in JET from mirror surfaces by laser cleaning

Widdowson, A.; Coad, J. P.; Temmerman, G. De; Farcage, D.; Hole, D.E.; Ivanova, Darya; Leontyev, A. V.; Rubel, M.; Semerok, A.; Schmidt, Axel; Thro, P.-Y.

doi:10.1016/j.jnucmat.2010.11.076

Cited by 30 publications

(22 citation statements)

References 6 publications

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“…The first attempt to clean a Be-containing film was undertaken by the authors of [77]. For cleaning SS and Mo mirrors exposed in JET during 2005-2007 a laser with λ=1064 nm, pulse length τ=120 ns and repetition rate 20 kHz was used.…”

Section: Removal Of Deposited Filmmentioning

confidence: 99%

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Voitsenya¹,

Bardamid²,

Donné³

2016

PHY

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In the experimental fusion reactor ITER, the plasma-facing component of each optical and/or laser diagnostic needs to be based on reflective optics with at least one mirror (first mirror) facing the thermonuclear plasma. The different kinds of radiation emanating from the burning plasma (neutrons, neutral atoms, electromagnetic radiation) create hostile operating conditions for the first mirrors. Therefore, a special program has been set up under the ITER framework aimed at solving the first mirror problem. This paper will review the main results in this field that have been obtained in the Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology” (in many cases in cooperation with groups of other countries, as indicated in corresponding parts of the manuscript) during long-term investigations directed to find a solution of this problem,i.e., to find a material and accompanying precautions in order to satisfy the requirements for first mirrors. The main efforts were devoted to finding solutions to overcome the impact of the most severe deteriorating factors resulting in degradation of the optical properties of mirrors: sputtering by charge exchange atoms and deposition of contaminants. The obtained results are focused on: the effects of long term sputtering on mirror specimens fabricated from different metals with different structures (polycrystals, single crystals, metal film on metal substrates, amorphous), the effects of contaminating film and the possible protection to avoid of its appearance, the role of chemical processes for some metal mirrors, and the choice of material of laser mirrors.

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Section: Removal Of Deposited Filmmentioning

confidence: 99%

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Voitsenya¹,

Bardamid²,

Donné³

2016

PHY

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“…Therefore, on the request of the ITER design team, the first mirror test (FMT) has been carried out at JET [1,2]. The entire research program comprises: (a) selection of material for the test mirror, (b) manufacture of mirrors and their carriers (cassettes of pan-pipe shape) for in-vessel installation, (c) optical pre-characterization of mirrors, (d) exposure in the plasma boundary of JET during a complete operational campaign, (e) a broad range of post-exposure analyses by means of optical and surface analysis methods, (f) analyses of deposition in the channels of the mirror carriers [3] and (g) photonic cleaning of the exposed mirrors [4], followed by analyses of cleaned surfaces and examination of products generated by the laser light impact. The FMT is embedded in tritium retention studies [5] aiming at a detailed description of erosion-deposition patterns in JET measured by several types of diagnostic tools.…”

Section: Introductionmentioning

confidence: 99%

Overview of the second stage in the comprehensive mirrors test in JET

et al. 2011

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The first mirror test for ITER in JET with carbon walls has been completed. Thirty polycrystalline Mo mirrors including four coated with a 1 µm rhodium (Rh) film were exposed to plasma in the divertor region and in the main chamber. The mirrors were installed in eight cassettes of pan-pipe shape. The reflectivity of all mirrors exposed in the divertor has been degraded by 80-90% because of the formation of thick (>20 µm) flaking co-deposits on surfaces. Only small reflectivity losses (5-10%) occurred on mirrors located at the channel mouth of the cassettes from the main chamber wall. This is due to the in situ removal of deposited species by charge exchange neutrals. Deuterium, 12 C and 9 Be are the main isotopes detected on surfaces, but other isotopes ( 13 C) are also found in some locations, thus indicating differences in the material migration. Rhodium coatings with an initial reflectivity that is 30% better than that of pure Mo survived the test without detachment, but their resultant reflectivity was the same as that of the exposed Mo surfaces.

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“…Another study was effective at reducing ~1-µm-thick beryllium depositions to approximately 10 nm after 40 laser pulses (Widdowson et al 2011). Laser heating or ablation may be effective at removing sodium depositions; however, more research is needed to determine the feasibility of this approach.…”

Section: Coolant and Impurity Condensation Mitigationmentioning

confidence: 99%

Summary of the Preliminary Optical ICHMI Design Study: A Preliminary Engineering Design Study for a Standpipe Viewport

Anheier

Qiao

Berglin

et al. 2013

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Removal of beryllium-containing films deposited in JET from mirror surfaces by laser cleaning

Cited by 30 publications

References 6 publications

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Overview of the second stage in the comprehensive mirrors test in JET

Summary of the Preliminary Optical ICHMI Design Study: A Preliminary Engineering Design Study for a Standpipe Viewport

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