24P083-P
Experiment of deuterium absorption and permeation due to plasma irradiationin the compact PWI simulator APSEDASPWI模擬実験装置APSEDASにおけるタングステン試料の重水素透過実験
Koichiro Honda1, Aleksandr Rusinov1, Mizuki Sakamoto2, Akihide Fujisawa3, Naoko Ashikawa4,
Tatsuo Shoji5, Masayuki Tokitani4, Mitsutaka Miyamoto6, Naoaki Yoshida3 and Tetsuo Tanabe1
本多耕一郎1, Aleksandr Rusinov1, 坂本瑞樹2, 藤澤彰英3, 芦川直子4,
庄司多津男5, 時谷政行4, 宮本光貴6, 吉田直亮3, 田辺哲朗1
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,Kasuga, Fukuoka 816-8580, Japan1
Plasma Research Center, University of Tsukuba,
1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan3-1-1-4F2
Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580, Japan3
National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan4
Department of Engineering, Nagoya University, Nagoya, Aichi, 464-8601, Japan5
Department of Material Science, Shimane University, Matsue, Shimane 690-8504, Japan6
九州大学総合理工学府 〒816-8580 福岡県春日市春日公園6-11
筑波大学プラズマ研究センター 〒305-8577 茨城県つくば市天王台1-1-12
九州大学応用力学研究所 〒816-8580 福岡県春日市春日公園6-13
核融合科学研究所 〒509-5292 岐阜県土岐市下石町322-64
名古屋大学工学部 〒464-8601 愛知県名古屋市不老町5
島根大学総合理工学部 〒690-8504 島根県松江市西川津町10606
Plasma driven permeation (PDP) of deuterium through a tungsten sample under the condition of low
energy and high flux plasma exposure was carried out in the compact PWI simulator APSEDAS. As thesample temperature increased, the permeation flux increased as well. At 630K and 670K, the permeation
flux is constant in steady state, whereas, at 700K, 740K, and 780K, we can observe decreasing of thepermeation flux in a steady state regime.

1. Introduction
Hydrogen isotope implanted into a plasma
facing component is either reemitted into theplasma, or retained in or permeated through aplasma facing component to the backside. In theview point of safety of the fusion reactor, it isimportant to understand hydrogen isotope
permeation behavior through a plasma facingcomponent. Various experiments of plasma
driven permeation (PDP) and ion driven
permeation (IDP) have been performed [forexample: 1-4].
In this study, PDP flux through a tungsten thindisk, which was exposed to the low energy andhigh flux deuterium plasma, was investigated inthe compact PWI simulator APSEDAS. The fluxof gas permeated through the tungsten sample
was measured by a quadrupole mass spectrometer(QMS).
2. Experimental
A schematic diagram of the experimental
apparatus is shown in Fig. 1. A plasma column isFig. 1. Schematic diagram of the PWI simulator
APSEDASFig. 2. Schematic diagram of the sample holder

sustained by 13.56 MHz RF field and its diameter isabout 50mm. The sample was pinched by stainlesssteel flange and Cu normal gasket as shown in Fig.
2. The irradiated area was φ16mm. The sample
temperature was measured by a thermocouple
contacted with the backside of the sample. The
plasma parameters were measured by a Langmuirprobe. The permeation flux was measured by QMS,
which was installed at the upper of the pump.
Several masses including HD and D2 weremonitored. QMS signals were calibrated by using astandard helium leak bottle. HD calibration factor
was assumed to be the same as that of D2. The
pressure of deuterium gas in the upstream chamber
during exposure was maintained at about 2.0×10-2
Torr and the base pressure of the downstream(permeation) side was kept at about 1.5×10-7 Torr.
The tungsten disk sample (φ20mm×1mm) usedin this study was produced by A.L.M.T. Corp. The
sample was polished both sides mechanically andultrasonically cleaned in acetone and ethanol, andannealed in vacuum at 1173K for 1 hour before
experiments.
3. Results and discussion
The tungsten sample was exposed to the low
energy plasma (6~9.7eV) of which flux was about
2.1~4.0×1021D/m2s.
The time evolutions of permeation fluxes of HD,
D2 and the sample temperature are shown in Fig.
3(a), where the sample temperature was changed by
RF power step by step. The time evolutions ofpermeation fluxes of HD, D2 and the sample
temperature until 2 hours from the start of theplasma exposure are also shown in Fig. 3(b). The
permeation flux was observed just after the start ofthe plasma exposure. The permeation flux
decreased as soon as the plasma exposure wasstopped. It took long time to reach steady state at
first. As the sample temperature increased, thepermeation flux increased as well. The increase in
the permeation flux is attributed to the increase in
the diffusion coefficient due to the sample
temperature increase. At 630K and 670K, thepermeation flux is constant in the steady state,
whereas, at 700K, 740K, and 780K, we can observe
decreasing of the permeation flux in the steady state
regime. When the sample temperature decreased to~630K again, the permeation flux was reduced to alittle higher level as the first steady state at 630K.
4. Summary
To investigate behavior of deuterium permeation,
Plasma driven permeation of deuterium through thetungsten sample was carried out in the compact
PWI simulator APSEDAS. The permeation flux
began to increase as soon as the plasma exposure
started, and began to decrease when the exposure
was stopped. As the sample temperature increased,
the permeation flux also increased because of adiffusion coefficient rising. However, thepermeation flux gradually decreased in the steadystate regime at high temperature.
To investigate the behavior of permeation in moredetail, we will simulate using the simulation code
TMAP 7 and compare to experimental results.

Fig. 3(a). The time evolutions of permeation fluxes ofHD, D2 and the sample temperature

Fig. 3(b). The time evolutions of permeation fluxes ofHD, D2 and the sample temperature (~2h)

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