Field emission property of nanostructured tungsten formed by helium plasma irradiation |
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Authors: | Shin Kajita Noriyasu Ohno Yuki Hirahata Mineo Hiramatsu |
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Affiliation: | 1. EcoTopia Science Institute, Nagoya University, Nagoya 464-8603, Japan;2. Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan;3. Faculty of Science and Technology, Meijo University, Nagoya 468-8502, Japan |
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Abstract: | Field emission property of nanostructured tungsten formed by the exposure to a helium plasma is measured to investigate the initiation process of arcing in nuclear fusion devices. Field emission current from the nanostructured tungsten and tungsten with helium bubbles was significantly higher than that from the polished tungsten specimen. However, field enhancement factor was on the order of 100, which was almost comparable to that of bulk tungsten; the increase in the field emission current is attributed to primarily an increase in the effective emission surface area. From the calculation of thermo-field emission current from a heated tungsten, it is thought that a significant current emission can be still initiated even when the field enhancement factor is not so high when tungsten is exposed to high density plasmas such as the one accompanied with ELMs. |
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Keywords: | Helium irradiation Field emission Arcing |
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