Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD
| Autor: | Masayuki Tokitani, Nobuaki Yoshida, Yoshio Ueda, Takashi Mutoh, Shinji Nagata, Hiroshi Kasahara, Suguru Masuzaki, Yasuo Yoshimura, Ryuichi Sakamoto |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Nuclear and High Energy Physics Ion beam analysis Materials science Nanostructure Materials Science (miscellaneous) Divertor chemistry.chemical_element Plasma Tungsten 01 natural sciences Fluence lcsh:TK9001-9401 010305 fluids & plasmas Large Helical Device Nuclear Energy and Engineering chemistry 0103 physical sciences lcsh:Nuclear engineering. Atomic power Atomic physics Helium |
| Zdroj: | Nuclear Materials and Energy, Vol 12, Iss, Pp 1358-1362 (2017) |
| ISSN: | 2352-1791 |
| Popis: | 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 |
| Databáze: | OpenAIRE |
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