Abstract
The plasma deposited layers at divertor surfaces in the
JET tokamak with carbon wall have been studied post
mortem, using micro ion beam analysis (µ-IBA) methods,
optical microscopy and scanning electron microscopy
(SEM). The layers were formed during plasma operations
over different periods through 1998-2009. They frequently
have a columnar structure. For µ-IBA a 3 MeV 3He beam was
used, focused to about 5-15 µm size. Nuclear reaction
analysis was used to measure D, Be and C. Elemental
mapping was carried out both at the original surface and
on polished layer cross sections. Trapped deuterium is
predominantly found in remote areas on the horizontal
bottom divertor tiles and in regions with locally
enhanced deuterium concentration on the vertical tiles.
Pockets with enhanced deuterium concentration are found
in the carbon fibre composite (CFC) substrate. Areas with
dimensions of about 100 µm with enhanced deuterium
concentration are also found inside the deposited layers.
The inhomogeneous fuel trapping is tentatively explained
with co-deposition in partly protected pits in the
substrate and by incorporation of dust particles in the
growing layers
Original language | English |
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Pages (from-to) | 266-270 |
Journal | Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms |
Volume | 332 |
Issue number | August |
DOIs | |
Publication status | Published - 2014 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Deposited layers
- deuterium retention
- fusion
- microbeam
- microstructure