FT-IR Study for Hydrogen-Irradiated Carbon Materials
H. Nakazatoa , M. Yoshidab and T. Tanabec
Interdiscip. Graduate School of Eng. Sciences, Kyushu University, Kasuga-Koen 6-1, 816-8580 Kasuga-Fukuoka,
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Hakozaki 6-10-1, Higashi-ku,
812-8581 Fukuoka, Japan
Interdisciplinary Graduate School of Engineering Science, Kyushu University, Department of Advanced Energy
Engineering Science, 6-10-1 Hakozaki, Higashi-ku, 812-8581 Fukuoka, Japan
Hydrogen retention in carbon materials and its removal are critical safety issues for ITER and have been extensively
studied. Hydrogen retention in carbon tiles used in tokamaks has been determined by post mortem analysis but no in
situ measurement of hydrogen retention has been done. Hydrogen release characteristics and/or properties of hydrogen
retaining carbon materials are quite dependent on hydrogen concentration. For example, those having high H/C, referred
as soft amorphous hydrogenated carbon, desorb hydrogen at lower temperatures, while those with low H/C, hard carbon,
need higher temperature to desorb hydrogen. Hence it is very important to know how much hydrogen with what kind
of chemical form are retained in plasma facing carbon materials and deposited carbon ﬁlms at plasma shadowed area.
Fourier-transform infrared (FT-IR) analysis, which is a most power-full technique to observe C-H bonding, could be an
in-situ analysis technique for hydrogen-retaining carbon materials in tokamaks with the aid of infra-red light illumina-
tion and ﬁver optics. Here we have applied FT-IR for hydrogen irradiated carbon materials to understand how FT-IR
spectra are varied with hydrogen concentration. FT-IR spectra were taken with a reﬂection absorption (RAS) method
for future application in tokamaks.
Since carbon materials used here, nuclear graphite and highly oriented pyroritic carbon, absorb infrared photons with
little reﬂection, it is quite diﬃcult to detect resonance absorption spectra owing to C-H bonds. Nevertheless, it was
found that wide area absorbance decreased with increasing hydrogen implanted ﬂuence. Moreover a small absorption
peak corresponding C-H stretching appeared at 2930 cm−1 for high H/C.
This well corresponds that hydrogen implantation ﬁrst modiﬁes graphite structure to decrease absorbance and implanted
hydrogen then binds to a carbon atom making the C-H bond. Unfortunately, however, S/N of the FT-IR spectra is still
very low and should be increased modifying geometry to measure the reﬂection absorption more eﬀectively.
Number of words in abstract: 303
Technical area: 51. Materials for plasma-facing components Armor materials
Special session: Not speciﬁed
Presentation: No preference
Special equipement: No special equipment