TY - JOUR
T1 - Evaluation of radiation damages on the first-wall surface in LHD exposed to charge-exchanged helium particles
AU - Tokitani, M.
AU - Yoshida, N.
AU - Miyamoto, M.
AU - Ohtawa, Y.
AU - Tokunaga, K.
AU - Fujiwara, T.
AU - Masuzaki, S.
AU - Ashikawa, N.
AU - Shoji, M.
AU - Kobayashi, M.
AU - Sagara, A.
AU - Noda, N.
AU - Yamada, H.
AU - Komori, A.
AU - Nagata, S.
AU - Tsuchiya, B.
N1 - Funding Information:
This work was performed with the support and under the auspices of the NIFS Collaborative Research Program and under the inter-university cooperative research program of the Institute for Materials Research, Tohoku University. This research was partly supported by the Japan Society for the Promotion of Science and Grant-in-Aid of Scientific Research from Japan Ministry of Education, Culture, Sports, Science and Technology.
PY - 2009/4/30
Y1 - 2009/4/30
N2 - In order to clarify the radiation damages caused by charge-exchanged helium particles, metal specimens were inserted into the first wall position by using material probe system in LHD, and then, exposed to the neutral beam heated helium plasmas (87 s in total). After the exposure, dense helium bubbles with size of 1-2 nm and dislocation loops were confirmed in all specimens from transmission electron microscope observation. It means that the energy of incidence helium particles is sufficiently higher than that of the minimum energy for creating the knock-on damage (Emin). Majority of such incidence helium particles are energetic neutrals created by charge-exchange collisions [R.J. Goldston, P.H. Rutherford, Introduction to Plasma Physics, 1996, p. 156]. It was tried to estimate the flux and energy of CX-helium to the first walls by comparing with systematic helium ion irradiation experiments [H. Iwakiri et al., J. Nucl. Mater. 283-287 (2000) 1134], [M. Tokitani et al., J. Nucl. Mater. 329-333 (2004) 761]. The estimated flux and energy from size and density of the defects is the order of ∼1019 He/m2 s, and about 1-2 keV, respectively.
AB - In order to clarify the radiation damages caused by charge-exchanged helium particles, metal specimens were inserted into the first wall position by using material probe system in LHD, and then, exposed to the neutral beam heated helium plasmas (87 s in total). After the exposure, dense helium bubbles with size of 1-2 nm and dislocation loops were confirmed in all specimens from transmission electron microscope observation. It means that the energy of incidence helium particles is sufficiently higher than that of the minimum energy for creating the knock-on damage (Emin). Majority of such incidence helium particles are energetic neutrals created by charge-exchange collisions [R.J. Goldston, P.H. Rutherford, Introduction to Plasma Physics, 1996, p. 156]. It was tried to estimate the flux and energy of CX-helium to the first walls by comparing with systematic helium ion irradiation experiments [H. Iwakiri et al., J. Nucl. Mater. 283-287 (2000) 1134], [M. Tokitani et al., J. Nucl. Mater. 329-333 (2004) 761]. The estimated flux and energy from size and density of the defects is the order of ∼1019 He/m2 s, and about 1-2 keV, respectively.
UR - https://www.scopus.com/pages/publications/64749102733
UR - https://www.scopus.com/pages/publications/64749102733#tab=citedBy
U2 - 10.1016/j.jnucmat.2008.12.086
DO - 10.1016/j.jnucmat.2008.12.086
M3 - Article
AN - SCOPUS:64749102733
SN - 0022-3115
VL - 386-388
SP - 173
EP - 176
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
IS - C
ER -