03pC16
高エネルギーイオン照射により照射損傷を導入したタングステンにおける水素同位体透過挙動
Hydrogen isotope permeation behavior for tungsten damaged
by energetic ion irradiation湯山 健太１）、 内村 大道 2)、戸田 健介 2)、佐藤 美咲 2)、張 龍 2)、大矢 恭久 2)、奥野 健二 2)
Kenta YUYAMA１）, Hiromichi UCHIMURA１）, Kensuke TODA１）, Misaki SATO１）, Long ZHANG１）, et al.

1)静岡大理 2)静岡大院理1) Faculty of Science, Shizuoka Univ. 2) Graduate School of Science, Shizuoka Univ.
Usage of tungsten (W) is considered as a plasma permeability for the D2+ irradiated sample was similar
facing material (PFM) in fusion reactors. During to the unirradiated sample. However, the permeation
operation, irradiation damages will be introduced in the coefficient was significantly reduced at the lower
PFM by implantation of various energetic particles such temperature side for the 3 keV D2+-irradiated sample.
as hydrogen isotopes from plasma. It is expected that This suggests that the hydrogen permeation behavior
dissolution, diffusion, and permeation behaviors of was affected by the formation of the irradiation defects.
hydrogen isotopes for damaged tungsten should be The deuterium permeability for 3 keV D2+-irradiateddifferent from those for undamaged tungsten. sample was estimated to be P3keV＝(7.11 ± 2.16) × 10-5
Elucidation of hydrogen isotope permeation behavior exp(1.33 ± 0.03 eV / kT) [mol m-1 s-1 Pa-0.5]. It wasfor the damaged tungsten is important from a view reported that the activation energy for deuterium depoint of safety evaluation. In this study, deuterium gas- trapping from vacancies is 1.41 eV [1], indicating thatdriven permeation behaviors for tungsten damaged by rate determination step for 3 keV D2+ irradiated sample
energetic ions were studied at the temperature of. ....K. was deuterium detrapping from vacancies, which
The role of the irradiation damages on the hydrogen reduced the deuterium permeation rate.
permeation was discussed.
Tungsten foil (10 mm× 10 mm× 0.05 mmt) purchased [1] D.F. Johnson et al., J . Mater. Res., 25 (2010) 315.
from Nilaco Co. Ltd was used. The sample was [2] Takahiro Ikeda et al., J. Nucl. Mater. 417 (2011)preheated at 1173 K for 30 minutes under ultrahigh 568-571.
vacuum (<10-6 Pa) to remove the impurities. After [3] R.Fraunfelder., J. Vac. Sci. Technol. 6 (3) (1969)preheating, 1.0 keV or 3.0 keV D2+ implantation was 388.
performed to introduce the damage with fluence of 1.0 [4] A.P.Zakharov et al., Fiz.-Khim.Mekh. Mater. 9(2)× 1022 D+ m-2. The deuterium implantation side of (1973) 29.
sample was placed at the downstream side. Thesesamples were introduced into permeation chamber andsealed with silver coated gaskets. The deuterium
permeation experiments were performed at the pressureof 3.00 - 45.00 kPa and temperature of 423 - 1173 K.
Figure shows the deuterium permeabilities for theunirradiated and D2+ irradiated samples. The permeation
behavior for the unirradiated sample was changed at thetemperature of 773 K, indicating two different
permeation process existed. The permeation coefficient
was determined to be P = (1.52 ± 0.15) × 10-10 exp (0.24± 0.01 eV / kT) [mol m-1 s-1 Pa-0.5] at 423 K – 773 K and
P = (3.39 ± 0.48) × 10-7 exp (0.76 ± 0.04 eV / kT) [molm-1 s-1 Pa-0.5] at 773 K – 1173 K. It is known that theactivation energy of deuterium permeation for crystal
grain boundary in poly-crystalline W is 0.23 eV. On the Fig. The deuterium permeability for the unirradiated W, and1keV or 3 keV D2+ irradiated W with reference.
other hand, that for crystal lattice in poly-crystalline W
is 0.58 eV. These values were good agreement with thepresent results, suggesting two permeation processes
controlled the deuterium permeation and the deuterium
diffusion in crystal boundary controlled at lower
temperature and deuterium diffusion in the crystal
lattice, at higher temperatures. The obtained