Beryllium and carbon films in JET following D–T operation

Rubel, M.; Coad, J. P.; Bekris, N.; Erents, S.K.; Hole, D.E.; Matthews, G. F.; Penzhorn, R.-D.

doi:10.1016/s0022-3115(02)01350-8

Cited by 58 publications

(33 citation statements)

References 21 publications

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“…The major difference between the cassettes from the outer wall and the divertor was that in the latter case only very small quantities or no beryllium (especially inner divertor) have been detected. The result is in full agreement with measurements of deposition in previous campaigns in JET with a series of divertors: Mk-IIA [7,8] Mk-IIGB (Gas Box) [19] and Mk-IISRP (Septum Replacement Plate) [20]. It also agrees with the analysis of other erosion-deposition diagnostic tools used in TRS and exposed along with the mirrors in the presence of the Mk-IIHD (High Delta) divertor [21] and with general results of material migration studies in JET [22].…”

Section: Images Insupporting

confidence: 89%

“…The decision on testing two materials was taken in 2002 and the motivation regarding the material choice can be found in [2]: (a) both materials were on the list of candidates for first mirrors in ITER; (b) Mo is hard, easy-to-polish metal of high thermal conductivity and low sputter erosion; (c) steel, foreseen for actively cooled mirrors, is the same material as the support structure thus the mirror distortion would be minimized. In addition, relatively low price of both materials and easy machining were important because, based on very broad erosion-deposition studies in JET [7,8] it could be expected that the reflectivity degradation would be caused mainly by co-deposition. Once carbon film starts to grow, the underlying substrate plays secondary role, as it was proven by earlier studies of co-deposition on different metallic surfaces [9].…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

First Mirrors Test in JET for ITER: An overview of optical performance and surface morphology

Rubel¹,

Coad

Temmerman

et al. 2010

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tMetallic mirrors will be essential components of all optical systems for plasma diagnosis in ITER. A comprehensive First Mirror Test (FMT) has been carried out in the JET tokamak. The exposure was followed by a characterisation of mirrors and their carriers. The main results obtained by optical and surface analysis methods are: (i) reflectivity of all tested mirrors is degraded either by erosion with charge exchange neutrals or by the formation of thick deposits; (ii) deuterium and carbon are the main elements detected on all mirror surfaces and the presence of beryllium is also found in several cases; (iii) thick deposits show columnar structure; (iv) bubble-like structures are detected in deposits; their formation is a probable reason for deposits' disintegration and peeling-off; (v) the deposition in channels in the divertor cassettes is pronounced at the very entrance and then it sharply decreases with the distance from the plasma, l$5-7 mm.

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Section: Images Insupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

First Mirrors Test in JET for ITER: An overview of optical performance and surface morphology

Rubel¹,

Coad

Temmerman

et al. 2010

Nuclear Instruments and Methods in Physics Research Section A:

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“…Total reflectivity was measured in the range 350-1700 nm using a photo-spectrometer (GetSpec) system complying with work procedures on materials retrieved from JET [1,2], i.e. contaminated with beryllium and tritium [9][10][11]. The integrating sphere was located in the glove-box and connected by fiber optics with externally located photo-spectrometers.…”

Section: Experimental Details: Exposure and Analysesmentioning

confidence: 99%

“…Nuclear reaction analysis (NRA) with a 2. 11 B. Carbon and beryllium were also determined by enhanced proton scattering (EPS) with a 2.5 MeV H + beam, which allowed simultaneous studies of heavier elements using proton-induced x-ray emission (PIXE).…”

Section: Experimental Details: Exposure and Analysesmentioning

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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“…This issue becomes even more important if carbon plasma-facing components (PFCs) are used [2][3][4]. Two basic schemes for fuel removal are currently considered: (i) desorption of hydrogen-containing species and (ii) removal of the entire fuel-rich co-deposit.…”

Section: Introductionmentioning

confidence: 99%

Fuel re-absorption by thermally treated co-deposited carbon layers

Ivanova¹,

Rubel²,

Philipps³

et al. 2011

Phys. Scr.

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Systematic studies have been conducted to address the fuel re-absorption by carbon deposits under repeated exposure to plasma after cleaning procedures. The investigation was done with graphite tiles from ALT-II (Advanced Limiter Test II), i.e. the main limiter at the TEXTOR tokamak. Pure graphite plates were used as the reference material. The experimental programme comprised the following: pre-characterization of specimens; D desorption by baking the tile at 1273 K; surface analyses of the fuel-depleted layers; exposure to deuterium in a laboratory plasma device and in TEXTOR; and quantitative assessment of deuterium re-absorption. The main result is that fuel retention in the re-exposed deposits is 30-40 times lower than that in the original co-deposit, showing that fuel re-absorption does not lead to an immediate re-saturation of deposits. Annealing at high temperatures enhances layer brittleness, leading eventually to detachment of co-deposits.

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Beryllium and carbon films in JET following D–T operation

Cited by 58 publications

References 21 publications

First Mirrors Test in JET for ITER: An overview of optical performance and surface morphology

First Mirrors Test in JET for ITER: An overview of optical performance and surface morphology

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

Fuel re-absorption by thermally treated co-deposited carbon layers

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