[Table of Contents]

Plasma and Fusion Research

Volume 5, 012 (2010)

Regular Articles


Microscopic Deformation of Tungsten Surfaces by High Energy and High Flux Helium/Hydrogen Particle Bombardment with Short Pulses
Masayuki TOKITANI, Naoaki YOSHIDA1), Kazutoshi TOKUNAGA1), Hajime SAKAKITA2), Satoru KIYAMA2), Haruhisa KOGUCHI2), Yoichi HIRANO2) and Suguru MASUZAKI
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
1)
Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
2)
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
(Received 24 August 2009 / Accepted 14 December 2009 / Published 7 April 2010)

Abstract

The neutral beam injection facility in the National Institute of Advanced Industrial Science and Technology was used to irradiate a polycrystalline tungsten specimen with high energy and high flux helium and hydrogen particles. The incidence energy and flux of the beam shot were 25 keV and 8.8 × 1022 particles/m2 s, respectively. The duration of each shot was approximately 30 ms, with 6 min intervals between each shot. Surface temperatures over 1800 K were attained. In the two cases of helium irradiation, total fluence of either 1.5 × 1022 He/m2 or 4.0 × 1022 He/m2 was selected. In the former case, large sized blisters with diameter of 500 nm were densely observed. While, the latter case, the blisters were disappeared and fine nanobranch structures appeared instead. Cross-sectional observations using a transmission electron microscope (TEM) with the focused ion beam (FIB) technique were performed. According to the TEM image, after irradiation with a beam shot of total fluence 4.0 × 1022 He/m2 , there were very dense fine helium bubbles in the tungsten of sizes 1-50 nm. As the helium bubbles grew the density of the tungsten matrix drastically decreased as a result of void swelling. These effects were not seen in hydrogen irradiation case.


Keywords

hydrogen, high energy, high fluence, tungsten, nanoscale structure, blister, bubble

DOI: 10.1585/pfr.5.012


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This paper may be cited as follows:

Masayuki TOKITANI, Naoaki YOSHIDA, Kazutoshi TOKUNAGA, Hajime SAKAKITA, Satoru KIYAMA, Haruhisa KOGUCHI, Yoichi HIRANO and Suguru MASUZAKI, Plasma Fusion Res. 5, 012 (2010).