| 11. |
- Sergienko, G., et al.
(författare)
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Quartz micro-balance results of pulse-resolved erosion/deposition in the JET-ILW divertor
- 2017
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Ingår i: Nuclear Materials and Energy. - : ELSEVIER. - 2352-1791. ; 12, s. 478-482
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Tidskriftsartikel (refereegranskat)abstract
- A set of quartz crystal microbalances (QMB) was used at JET with full carbon wall to monitor mass erosion/ deposition rates in the remote areas of the divertor. After introduction of the ITER-like wall (ILW) in JET with beryllium main wall and tungsten divertor, strong reduction of the material deposition and accompanied fuel retention was observed. Therefore the existing QMB electronics have been modified to improve the accuracy of frequency measurements by a factor of ten down to 0.1 Hz which corresponds to 1.4 ng cm(-2). The averaged deposition rates of 1.2-3 ng cm(-2) s(-1) and erosion rates of 5.6-8.1 ng cm(-2) s(-1) were observed in the inner divertor of JET-ILW with the inner strike point positions close to the bottom edge of vertical tile 3 and at the horizontal tile 4 respectively. The erosion with averaged rates of approximate to 2.1 ng cm(-2) s(-1) and approximate to 120 ng cm(-2) s(-1) were observed in the outer divertor for the outer strike point positions at tile 5 and tile 6 respectively. (C) 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
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| 12. |
- Strauss, H., et al.
(författare)
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Comparison of JETAVDE disruption data with M3D simulations and implications for ITER
- 2017
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 24:10
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear 3D MHD asymmetric vertical displacement disruption simulations have been performed using JET equilibrium reconstruction initial data. Several experimentally measured quantities are compared with the simulation. These include vertical displacement, halo current, toroidal current asymmetry, and toroidal rotation. The experimental data and the simulations are in reasonable agreement. Also compared was the correlation of the toroidal current asymmetry and the vertical displacement asymmetry. The Noll relation between asymmetric wall force and vertical current moment is verified in the simulations. Also verified is the toroidal flux asymmetry. Although in many ways, JET is a good predictor of ITER disruption behavior, JET and ITER can be in different parameter regimes, and extrapolating from JET data can overestimate the ITER wall force.
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| 13. |
- Tokitani, M., et al.
(författare)
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Micro-/nano-characterization of the surface structures on the divertor tiles from JET ITER-like wall
- 2017
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Ingår i: Fusion engineering and design. - : Elsevier. - 0920-3796 .- 1873-7196. ; 116, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- Micro-/nano-characterization of the surface structures on the divertor tiles used in the first campaign (2011–2012) of the JET tokamak with the ITER-like wall (JET ILW) were studied. The analyzed tiles were a single poloidal section of the tile numbers of 1, 3 and 4, i.e., upper, vertical and horizontal targets, respectively. A sample from the apron of Tile 1 was deposition-dominated. Stratified mixed-material layers composed of Be, W, Ni, O and C were deposited on the original W-coating. Their total thickness was ∼1.5 μm. By means of transmission electron microscopy, nano-size bubble-like structures with a size of more than 100 nm were identified in that layer. They could be related to deuterium retention in the layer dominated by Be. The surface microstructure of the sample from Tile 4 also showed deposition: a stratified mixed-material layer with the total thickness of 200–300 nm. The electron diffraction pattern obtained with transmission electron microscope indicated Be was included in the layer. No bubble-like structures have been identified. The surface of Tile 3, originally coated by Mo, was identified as the erosion zone. This is consistent with the fact that the strike point was often located on that tile during the plasma operation. The study revealed the micro- and nano-scale modification of the inner tile surface of the JET ILW. In particular, a complex mixed-material deposition layer could affect hydrogen isotope retention and dust formation.
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