Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy
One of the key problems for the application of nuclear fusion energy is to select the suitable plasma facing materials (PFMs). Among the W-based materials, CVD-W exhibits some unique advantages. In order to estimate the performance of CVD-W under the fusion environment, the vacancy-type defects and...
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MDPI AG
2021-01-01
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| author | Xuefen Tian Xiang Liu Min Gong Weidi He Xinge Fu Aihong Deng |
| author_facet | Xuefen Tian Xiang Liu Min Gong Weidi He Xinge Fu Aihong Deng |
| author_sort | Xuefen Tian |
| collection | DOAJ |
| description | One of the key problems for the application of nuclear fusion energy is to select the suitable plasma facing materials (PFMs). Among the W-based materials, CVD-W exhibits some unique advantages. In order to estimate the performance of CVD-W under the fusion environment, the vacancy-type defects and their evolution are investigated by the Doppler-broadening slow positron beam analysis (DB-SPBA) combined with SEM (scanning electron microscope). There are two kinds of neutral beam irradiation, the pure H neutral beam and the H + 6 at.% He neutral beam irradiation, which are performed at the neutral beam facility GLADIS (IPP, Germany). The surface temperatures of CVD-W irradiated by H (H + 6 at.% He) are 850 and 1000 (700 and 800 °C). By comparing the samples under different conditions, the defect evolution of CVD-W is obtained. As for the pure H neutral beam irradiated samples, the DB-SPBA results demonstrate that the CVD-W sample at the surface temperature of 1000 °C, compared to the 850 °C sample, shows a decrease in <i>S</i> parameters, which is due to the reduction of vacancy-type defect concentration. The defect damage layer in 1000 °C sample is narrower than that of 850 °C sample and the defect type tends to be consistent in 1000 °C sample. The SEM results suggest that the surface damage of the 1000 °C sample was recovered to some extent. As for the H + 6 at.% He neutral beam irradiated samples, compared with the CVD-W sample at the surface temperature of 700 °C, the 800 °C sample shows an increased <i>S</i> parameters, which can be attributed to the volume increase of vacancy-type defect. The defect damage layer in the 800 °C sample is wider than that of the 700 °C sample. Both the H + 6 at.% He irradiated samples show complex defect types. The surface of the 800 °C sample exhibits more dense pinhole damage structures compared to that of the 700 °C sample. |
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| last_indexed | 2024-03-09T03:41:24Z |
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| spelling | doaj.art-5cc4d6327c43429c812e9de064470e692023-12-03T14:40:08ZengMDPI AGMetals2075-47012021-01-0111221110.3390/met11020211Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation SpectroscopyXuefen Tian0Xiang Liu1Min Gong2Weidi He3Xinge Fu4Aihong Deng5College of Physics, Sichuan University, Chengdu 610064, ChinaSouthwestern Institute of Physics, Chengdu 610041, ChinaCollege of Physics, Sichuan University, Chengdu 610064, ChinaCollege of Physics, Sichuan University, Chengdu 610064, ChinaCollege of Physics, Sichuan University, Chengdu 610064, ChinaCollege of Physics, Sichuan University, Chengdu 610064, ChinaOne of the key problems for the application of nuclear fusion energy is to select the suitable plasma facing materials (PFMs). Among the W-based materials, CVD-W exhibits some unique advantages. In order to estimate the performance of CVD-W under the fusion environment, the vacancy-type defects and their evolution are investigated by the Doppler-broadening slow positron beam analysis (DB-SPBA) combined with SEM (scanning electron microscope). There are two kinds of neutral beam irradiation, the pure H neutral beam and the H + 6 at.% He neutral beam irradiation, which are performed at the neutral beam facility GLADIS (IPP, Germany). The surface temperatures of CVD-W irradiated by H (H + 6 at.% He) are 850 and 1000 (700 and 800 °C). By comparing the samples under different conditions, the defect evolution of CVD-W is obtained. As for the pure H neutral beam irradiated samples, the DB-SPBA results demonstrate that the CVD-W sample at the surface temperature of 1000 °C, compared to the 850 °C sample, shows a decrease in <i>S</i> parameters, which is due to the reduction of vacancy-type defect concentration. The defect damage layer in 1000 °C sample is narrower than that of 850 °C sample and the defect type tends to be consistent in 1000 °C sample. The SEM results suggest that the surface damage of the 1000 °C sample was recovered to some extent. As for the H + 6 at.% He neutral beam irradiated samples, compared with the CVD-W sample at the surface temperature of 700 °C, the 800 °C sample shows an increased <i>S</i> parameters, which can be attributed to the volume increase of vacancy-type defect. The defect damage layer in the 800 °C sample is wider than that of the 700 °C sample. Both the H + 6 at.% He irradiated samples show complex defect types. The surface of the 800 °C sample exhibits more dense pinhole damage structures compared to that of the 700 °C sample.https://www.mdpi.com/2075-4701/11/2/211CVD-WH/HeDB-SPBA |
| spellingShingle | Xuefen Tian Xiang Liu Min Gong Weidi He Xinge Fu Aihong Deng Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy Metals CVD-W H/He DB-SPBA |
| title | Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy |
| title_full | Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy |
| title_fullStr | Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy |
| title_full_unstemmed | Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy |
| title_short | Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy |
| title_sort | evolution of defects in cvd w irradiated by h he neutral beam using positron annihilation spectroscopy |
| topic | CVD-W H/He DB-SPBA |
| url | https://www.mdpi.com/2075-4701/11/2/211 |
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