2004 Fiscal Year Final Research Report Summary
Study on reliability of CVD diamond RF window under fusion reactor environments
| Project/Area Number |
15560713
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Shizuoka University |
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Principal Investigator |
OKUNO Kenji Shizuoka University, Dept.of Science, Professor, 理学部, 教授 (80293596)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIOKA Hiroe Shizuoka University, Dept.of Science, Assistant Professor, 理学部, 助教授 (80021955)
IMAI Tsuyoshi Japan Atomic Energy Research Institute, Deputy Manager, 核融合工学部, 次長 (80354637)
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| Project Period (FY) |
2003 – 2004
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| Keywords | fusion reactor / RF window materials / CVD diamond / tritium / high energy chemistry / X-ray photoelectron spectroscopy |
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| Research Abstract |
An Electron Cyclotron Heating and Current Drive (ECH/ECCD) system is an effective tool for local plasma heating in fusion reactors. A vacuum window is one of the most important components fro development of the ECH/ECCD system. The window is used in a transmission line and a gyrotron as a wave output window. Diamond is the leading candidate for the RF window due to its low loss tangent in the frequency range of 100 GHz and extremely high thermal conductivity. Therefore, it should be exposed to energetic particles and radiation. The particles such as D and T have strong chemical affinity for carbon atoms. Therefore, it is an important safety issue in the ECH/ECCD system to elucidate the effects of particle exposure on structure change in the diamond. The influence of radiation such as γ-ray and neutron is also important from the same viewpoint.
In the present study, structure change and chemical bonding with implanted ions in the CVD diamonds were investigated by X-ray Photoelectron Spec
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troscopy (XPS) after energetic ion irradiation and the radiations. The effects of energetic D_2^+ and He^+ irradiation on the chemical structure of CVD diamond and the existing states of the irradiated D were investigated by means of the XPS technique. The variation of C1s XPS spectra indicated a change of diamond structure under both ion irradiations. The C1s chemical shift of D_2^+ irradiation was smaller than that of He^+ irradiation, and the chemical shift was -0.6 and -2.5 eV, respectively. The variation of the C1sFWHM of D_2^+ irradiation was also smaller than that of He^+ irradiation, and the FWBM was 0.1 and 0.7 eV, respectively. This difference in the chemical shift and FWHM could be explained by the formation of C-D bond between carbon atoms and the trapped deuterium atoms. In γ-ray irradiation for the diamond, it was shown that lower dose rate irradiation induced significantly disordered diamond structures, while no disordered diamond structures were observed under higher dose rate irradiation. This suggested that irradiation annealing of disordered structure would be carried out in the case of the higher dose rate irradiation. On the other hand, the neutron irradiation was no irradiation effects on the chemical structure of CVD diamond.
The experimental results accumulated in the present study give useful data bases to estimate the reliability of CVD diamond for the RF window in fusion reactors Less
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[Journal Article] Thermal Dsorption Behavior of Deuterium Implanted into Polycrystalline Diamond2005
Author(s)
H.Kimura, M.Sasaki, Y.Morimoto, T.Takeda, H.Kodama, A.Yoshikawa, M.Oyaidzu, K.Takahashi, K.Sakamoto, T.Imai, K.Okuno
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Journal Title
Journal of Nuclear Materials Vol.337-339
Pages: 614-618
Description
「研究成果報告書概要(欧文)」より
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