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@ARTICLE{Oelmann:890591,
author = {Oelmann, Jannis and Wüst, Erik and Brezinsek, Sebastijan
and Li, Cong and Zhao, Dongye and Rasinski, Marcin and
Dhard, Chandra Prakash and Mayer, Matej and Naujoks, Dirk
and Gao, Yu},
title = {{H}ydrogen content in divertor baffle tiles in
{W}endelstein 7-{X}},
journal = {Nuclear materials and energy},
volume = {26},
issn = {2352-1791},
address = {Amsterdam [u.a.]},
publisher = {Elsevier},
reportid = {FZJ-2021-01057},
pages = {100943 -},
year = {2021},
abstract = {Plasma–wall interactions play a crucial role for the
performance of fusion devices and the lifetime of
plasma-facing components. In this work the results of some
plasma–wall interaction processes, namely the
erosion/deposition pattern and the fuel content of divertor
baffle tiles exposed in Wendelstein 7-X in the initial phase
of island divertor, are presented. Net-deposition of carbon
with co-deposited oxygen and hydrogen is determined on the
graphite tiles after about 1 hour of plasma operation in
hydrogen and helium in operation phase OP 1.2a. C is
predominately a result of net-erosion of the graphite target
plates and oxygen is the strongest intrinsic impurity in
Wendelstein 7-X in OP 1.2a. The hydrogen content
distribution on a set of tiles exposed in equivalent
positions in three of the five modules of the stellarator
was quantified for the first time. Ex-situ performed
laser-induced breakdown spectroscopy measurements show the
depth-resolved fuel content in deposited layers as well as
implantation and diffusion in the base material.
Complementary, gas analysis after laser-induced ablation
offers quantitative hydrogen content determination in the
deposited layers up to 1018 hydrogen atoms/cm that is
non-uniformly distributed over the 95 mm 125 mm sized tiles.
The results show a toroidal asymmetry with $60\%$ more
hydrogen in the stellarator module 2 with respect to module
1 as well as a slight top-down asymmetry for the baffle
tiles in upper and lower half modules. A clear dependence of
the hydrogen content on the surface temperature during
plasma exposition in stellarator discharges in standard
magnetic divertor configuration with edge transformation 5/5
was not observed.},
cin = {IEK-4},
ddc = {624},
cid = {I:(DE-Juel1)IEK-4-20101013},
pnm = {134 - Plasma-Wand-Wechselwirkung (POF4-134)},
pid = {G:(DE-HGF)POF4-134},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000628782500060},
doi = {10.1016/j.nme.2021.100943},
url = {https://juser.fz-juelich.de/record/890591},
}