| 1. |
- Koivuranta, S., et al.
(författare)
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Post-mortem measurements on fuel retention at JET in 2007-2009 experimental campaign
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438:Suppl., s. S735-S737
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Tidskriftsartikel (refereegranskat)abstract
- The deuterium inventory at Joint European Torus (JET) after the 2007-2009 experimental campaign has been evaluated using Nuclear Reaction Analysis (NRA) and Secondary Ion Mass Spectrometry (SIMS). A full poloidal set of divertor tiles were analysed providing estimation for the total deuterium retention of about 48 g. Deuterium is trapped mainly at the inner divertor floor tile and outer divertor floor tile. The total deuterium retention is similar to 2%.
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| 2. |
- Likonen, Jari, et al.
(författare)
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Local deposition of C-13 tracer in the JET MKII-HD divertor
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438:Suppl., s. S762-S765
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Tidskriftsartikel (refereegranskat)abstract
- Migration and deposition of C-13 have been investigated at JET by injecting C-13-labelled methane at the outer divertor base at the end of the 2009 campaign. The C-13 deposition profile was measured with enhanced proton scattering (EPS) and secondary ion mass spectrometry (SIMS) techniques. A strong toroidal deposition band for C-13 was observed experimentally on each of the analysed four outer divertor floor tiles. In addition, C-13 was also found on the vertical edge of load bearing tile (LBT) and at the bottom of the LBT tile facing the puffing hole. Local C-13 migration in the vicinity of the injection location was modelled by the ERO code. The ERO simulations also produced the strong toroidal C-13 deposition band but there is strong deposition also on the vertical edge of the LBT tile and elsewhere on the horizontal part of the outer divertor floor tile.
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| 3. |
- Matejicek, Jiri, et al.
(författare)
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Interaction of candidate plasma facing materials with tokamak plasma in COMPASS
- 2017
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Ingår i: Journal of Nuclear Materials. - : ELSEVIER SCIENCE BV. - 0022-3115 .- 1873-4820. ; 493, s. 102-119
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arc-discharge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of 'global' erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization.
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| 4. |
- Petersson, Per, et al.
(författare)
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Injection of nitrogen-15 tracer into ASDEX-Upgrade : New technique in material migration studies
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438:SUPPL., s. S616-S619
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Tidskriftsartikel (refereegranskat)abstract
- For the first time nitrogen-15 gas was used as a tracer for determining of global nitrogen retention in ASDEX-Upgrade. The injection done from the midplane gas inlet on the last day of the experimental campaign was followed by retrieval and ex situ analyses of many limiter and divertor tiles. The study was done by nuclear reaction analysis using the N-15(H-1,gamma He-4)C-12 process and detecting both gamma radiation and He-4. The highest and peaked concentrations of N-15, 8 x 10(16) cm(2), were found on limiters close to the injection point, while fairly homogeneous flat profiles were measured on most of the divertor plates. The measured concentrations are compared to an ASCOT simulation of the injection.
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