27pB07
様々な温度にて炭素照射したタングステンにおける欠陥形成と重水素滞留挙動の相関関係に関する研究
Study of correlation between defect formation and retention behavior of deuteriumin carbon-implanted tungsten at various carbon implantation temperatures
川﨑淨貴 1、小林真 1、藤島徹生 1、戸田健介 1、芦川直子 2、相良明男 2、
吉田直亮 3、大矢恭久 1、奥野健二 1
静大理放射研1、核融合研2、九大応力研3
Kiyotaka Kawasaki1, Makoto Kobayashi1, Tetsuo Fujishima1, Kensuke Toda1, Naoko Ashikawa2, et al.
1
Shizuoka Univ., 2NIFS., 3Kyushu Univ.
The usage of tungsten has been considered as the plasma facingretention behavior. The TEM observations were also performed tomaterial (PFM) in D-T fusion reactors. The PFM is exposed toobserved the irradiation defects formed by the ion implantations.

energetic hydrogen isotopes and impurities like carbon during

Figure shows the D2 TDS spectra for the tungsten sample

plasma operation. It is considered that the irradiation defects will be

implanted with C+ as a function of C+ implantation temperature.

introduced by these energetic particles on the tungsten surface,

There were two deuterium desorption stages at around 400 K andresulting in the increase of hydrogen isotope retention in the PFM.

550 K, attributing to the desorption of deuterium trapped byTherefore, elucidation of a correlation between hydrogen isotope

dislocation loops and trapped by vacancies, respectively. The

retention behaviors and formation of irradiation defects is quite

retention of deuterium trapped by vacancies was increased as the C+

important to understand the fuel recycling in the PFM during theimplantation temperature increased. For TEM observation, however,operation. In addition, the first wall is exposed to high heat load in

the amount of dislocation loops was almost the same among thesethe D-T fusion reactors. Therefore, it was also necessary toC+ implanted samples even if the implantation temperature wasunderstand effects of carbon implantation temperature on thechanged, indicating that the amount of vacancies was almost theformation of irradiation defects and the hydrogen isotope retention.

same among these samples. On the other hand, the voids were++In this study, C pre-implantations into tungsten at various C

clearly formed for the C+ implanted sample at 673 K, indicating that

implantation temperatures were performed. Thereafter, D2+

the increase of the amount of deuterium desorbed at around 550 K

implantation was carried out at room temperature to clarify thewas caused by the deuterium trapped by the voids. It was consideredtemperature dependence on defect formation and deuteriumthat the aggregation of vacancy was induced by the enhancement ofretention for carbon implanted-tungsten. TDS (Thermal desorption

irradiation induced diffusion of vacancies due to the higher C+

spectroscopy) measurements were performed to investigate theimplantation temperature. Therefore, it was indicated that thedeuterium retention behavior in tungsten. TEM (Transmission

increase of C+ implantation temperature will enhance the hydrogenElectron Microscopy) observations were also performed to observeisotope retention in tungsten due to the formation of voids. However,

the irradiation defects formed by the ion implantations.

the desorption temperature of deuterium shifted toward lowerφt

A disk-type polycrystalline tungsten (10 mm ×0.5 mm ) purchased

temperature region compared to that in only D2+ implanted tungsten

from Allied Material Co. Ltd was used. The sample was preheated atin our previous study. This difference will be discussed in the-61173 K for 30 minutes under ultrahigh vacuum (>10 Pa) to remove

presentation.
Peak 1processes. The C+ pre-implantation was done with the energy of 10+

C imp. at R.T.
+C imp. at 473 K+C imp. at 673 K

4.0

17keV C+ and the ion fluence of 1.0 × 1021 C+ m-2 at room temperature,
473 K or 673 K. For the D2+ implantation, 3.0 keV D2+ implantation
was performed for C+ pre-implanted tungsten with the ion fluence of
1.0 × 1022 D+ m-2 at room temperature. After the ion implantation,
TDS measurements were performed from room temperature to 1173
K with a heating rate of 0.5 K s-1 to investigate the deuterium

Peak 2

5.0-2

Desorption rate / 10 D2 m s-1

the impurities and damages introduced during the polishing

Fig.

3.0
2.0
1.00.0300

500
700
Temperature / K+900

D2 TDS spectra for C -D2+ sequential implanted tungsten withvarious C+ implantation temperatures and only D2+ implanted
tungsten