26aC02
欠陥導入タングステン中の重水素滞留挙動に及ぼす炭素照射影響
Effect of carbon implantation on deuterium retention behavior for damaged tungsten
東奎介 1、湯山健太 2、植村有希 2、桜田翔大 2、藤田啓恵 2、胡翠 1、波多野雄治 3、吉田直亮 4、近田拓未 2、大矢恭久 2Keisuke Azuma1 , Kenta Yuyama2 , Yuki Uemura2 , Shodai Sakurada2 , Hiroe fujita2 , Cui Hu1 ,Yuji Hatano3, Naoaki Yoshida4, Takumi Chikada2 , Yasuhisa Oya2
1静大理、2 静大院理、3 富山大水素研、4 九大応力研
Faculty of Science, Shizuoka Univ, 2Graduate School of Science, Shizuoka Univ,3Hydrogen Isotope Research Center, Univ. of Toyama, 4Research Institute for Applied Mechanics, Kyushu Univ.
1Carbon (C+) implantation effects on deuterium (D) retention for Fe 2+ damaged tungsten (W) with the damage concentration of0.001, 0.01, 0.1 and 1.0 dpa were studied. It was found that the amount of D trapped by voids was increased as the damage
concentration was increased from 0.1 dpa. On the other hand, D desorption rate derived from vacancies did not change in spiteof increased damage concentration. These results suggested that C was trapped by vacancies, which suppressed D trapping byvacancies.
showed that D desorption rate at Peak 2 and Peak 3
increased as the damage concentration increased [6]. In thisexperiment, D desorption rate at Peak 3 increased as thedamage concentration increased. However, no remarkablechange of D desorption at Peak 2 was found by thesequential Fe2+ and C+ implanted W in spite of increased
damage concentration, indicating that the vacancies formed
by Fe2+ implantation would trap C, which refrained Dtrapping by vacancies. The voids can sufficiently trap D,
because the size of voids is larger than vacancies.

-1

2.5

Peak1

17

Peak2

Peak3
un-damaged
1.0 dpa
0.1 dpa
0.01 dpa
0.001 dpa

2.0-2

Desorption rate / 10 D2 m s

1. Introduction
Tungsten (W) is planned to be used as plasma facing
materials of fusion reactors like ITER due to its good
physical characteristics such as higher melting point andlower sputtering yield. During the plasma operation, W will
be exposed to energetic particles, including hydrogenisotopes, neutron and impurities like carbon (C). It is wellknown that hydrogen isotope is trapped in the defects
produced by energetic particle irradiation. In addition, aC-W mixed layer was formed by C+ implantation for W,
which suppressed the deuterium (D) diffusion [1–2].
Therefore, it is important to elucidate C+ implantation effecton D retention behavior for damaged W to comprehendhydrogen isotope dynamics in actual reactor conditions.
2. Experimental
The polycrystalline W (A.L.M.T. Corp., Japan) with thesize of 10 mm diameter and 0.5 mm thickness was used as asample. To remove impurities, these samples were preheatedat 1173 K for 30 minutes under ultrahigh vacuum (< 10 -6 Pa).
To simulate neutron implantation, 6 MeV Fe2+ wasimplanted at room temperature with the damage
concentration of 0.001, 0.01, 0.1, and 1.0 dpa (displacementper atom) by 3 MV tandem accelerator, TIARA (Takasaki
Ions Accelerators for Advanced Radiation Application).
Then, 10 keV C+ implantation for these samples wereperformed with the ion flux of 1.0 × 1017 C＋ m-2 s-1 up to
the ion fluence of 1.0 × 1021 C+ m-2 at room temperature.
Thereafter, 3 keV D2+ was implanted with the ion flux of 1.0
× 1018 D+ m-2 s-1 up to the ion fluence of 1.0 × 1022 D+ m-2 atroom temperature. Finally, thermal desorption spectroscopy(TDS) measurements were performed from room
temperature to 1173 K to evaluate the D desorption
behavior.
3. Results and discussion
D2 TDS spectra for the sequential Fe2+ and C+ implanted W
with various damage concentrations (0.001 – 1.0 dpa) are
shown in Fig 1. These spectra were consisted of threedesorption peaks located at 400, 600, and 790 K. It is known
that Peak 1 is desorption of D adsorbed on the surface and/or
trapped by dislocation loops [3,4]. Peak 2 and Peak 3 wereconsidered to be derived from desorption of D trapped byvacancies and voids, respectively [5]. Our previous
experiment on the sequential Fe2+ and D+ implantation

1.5

1.00.50.04006008001000
Temperature / K
Fig.1 D2 TDS spectra for the sequential Fe2+ and C+ implanted Wwith various damage concentration and only C+ implanted WReferences[1] T. Shimada et al., J. Nucl. Mater. 313 (2003) 204.
[2] V. Kh. Alimov et al., J. Nucl. Mater. 282 (2000) 125-130[3] O. V. Ogorodnikova et al., J. Nucl. Mater. 313-316(2003) 469.
[4] H. Eleveld and A. Van Veen, J. Nucl. Mater. 191 (1992)
433-438[5] G. N. Luo et al., Fusion Eng. Des. 81, 8-14 (2006) 975.
[6] Y. Oya et al., J. Nucl. Mater. 461 (2015) 336-340.