Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD
In order to confirm the formation of a tungsten fiberform nanostructure (W-fuzz) by helium plasma exposure in the large-sized plasma confinement device, the bulk tungsten with the size of 80 × 20 × 1.5 mm3 was inserted into the divertor leg position in the Large Helical Device (LHD). Then, it was ex...
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| Format: | Article |
| Language: | English |
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Elsevier
2017-08-01
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| Series: | Nuclear Materials and Energy |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179116300278 |
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| author | M. Tokitani S. Masuzaki H. Kasahara Y. Yoshimura R. Sakamoto N. Yoshida Y. Ueda T. Mutoh S. Nagata |
| author_facet | M. Tokitani S. Masuzaki H. Kasahara Y. Yoshimura R. Sakamoto N. Yoshida Y. Ueda T. Mutoh S. Nagata |
| author_sort | M. Tokitani |
| collection | DOAJ |
| description | In order to confirm the formation of a tungsten fiberform nanostructure (W-fuzz) by helium plasma exposure in the large-sized plasma confinement device, the bulk tungsten with the size of 80 × 20 × 1.5 mm3 was inserted into the divertor leg position in the Large Helical Device (LHD). Then, it was exposed to the divertor plasma during the ultra-long pulse helium discharges with 10,190s in total. The width of the divertor plasma, incident ion energy and total fluence were expected to be ∼2cm, 100–200eV and ∼5 ×1025 He/m2 (strike position), respectively. The surface temperature of the tungsten specimen was monitored by IR camera. The typical surface temperature of the divertor strike point was estimated to be around 1900∼2300K. After the exposure, an initial growth phase of tungsten fiberform nanostructure (W-fuzz) was able to be identified on the tungsten surface. The finest initial growth phase of the W-fuzz structure was able to be identified on the central region of the divertor strike point, where retention amount of helium was estimated to be ∼8 ×1021 He/m2. This study is the first simultaneous evaluation of the W-fuzz growth and quantification of the helium retention in the large-sized plasma confinement device. Keywords: W-fuzz, TEM observation, Ion beam analysis, LHD |
| first_indexed | 2024-12-19T03:18:30Z |
| format | Article |
| id | doaj.art-e1e74dc1bb2e41f9b3eddc5ffbdeb7bd |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-19T03:18:30Z |
| publishDate | 2017-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-e1e74dc1bb2e41f9b3eddc5ffbdeb7bd2022-12-21T20:37:49ZengElsevierNuclear Materials and Energy2352-17912017-08-011213581362Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHDM. Tokitani0S. Masuzaki1H. Kasahara2Y. Yoshimura3R. Sakamoto4N. Yoshida5Y. Ueda6T. Mutoh7S. Nagata8National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan; Corresponding author.National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, JapanNational Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, JapanNational Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, JapanNational Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, JapanResearch Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580, JapanGraduate School of Engineering, Osaka University, Yamadaoka, Suita, Osaka 565-0871, JapanNational Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, JapanInstitute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, JapanIn order to confirm the formation of a tungsten fiberform nanostructure (W-fuzz) by helium plasma exposure in the large-sized plasma confinement device, the bulk tungsten with the size of 80 × 20 × 1.5 mm3 was inserted into the divertor leg position in the Large Helical Device (LHD). Then, it was exposed to the divertor plasma during the ultra-long pulse helium discharges with 10,190s in total. The width of the divertor plasma, incident ion energy and total fluence were expected to be ∼2cm, 100–200eV and ∼5 ×1025 He/m2 (strike position), respectively. The surface temperature of the tungsten specimen was monitored by IR camera. The typical surface temperature of the divertor strike point was estimated to be around 1900∼2300K. After the exposure, an initial growth phase of tungsten fiberform nanostructure (W-fuzz) was able to be identified on the tungsten surface. The finest initial growth phase of the W-fuzz structure was able to be identified on the central region of the divertor strike point, where retention amount of helium was estimated to be ∼8 ×1021 He/m2. This study is the first simultaneous evaluation of the W-fuzz growth and quantification of the helium retention in the large-sized plasma confinement device. Keywords: W-fuzz, TEM observation, Ion beam analysis, LHDhttp://www.sciencedirect.com/science/article/pii/S2352179116300278 |
| spellingShingle | M. Tokitani S. Masuzaki H. Kasahara Y. Yoshimura R. Sakamoto N. Yoshida Y. Ueda T. Mutoh S. Nagata Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD Nuclear Materials and Energy |
| title | Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD |
| title_full | Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD |
| title_fullStr | Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD |
| title_full_unstemmed | Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD |
| title_short | Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD |
| title_sort | initial growth phase of w fuzz formation in ultra long pulse helium discharge in lhd |
| url | http://www.sciencedirect.com/science/article/pii/S2352179116300278 |
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