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Manufacturing and Leak Check of Shell Targets for the FIREX-I Project

Takeshi FUJIMURA, Mitsuo NAKAI, Akifumi IWAMOTO¹⁾, Keiji NAGAI, Hirofumi HOMMA, Ken-ichi TANABE and Takayoshi NORIMATSU

Institute of Laser Engineering (ILE), Osaka University, 2-6 Yamada-oka, Osaka 565-0871 Japan

1)

National Institute for Fusion Science (NIFS), 322-6 Oroshi-cho, Toki, Gifu 509-0292, Japan

(Received 3 March 2009 / Accepted 3 June 2009 / Published 9 September 2009)

Abstract

This article reports the latest progress in the manufacture of shell targets used for the first stage of the Fast Ignition Realization Experiment (FIREX-I). In the project, the targets are cooled to cryogenic temperature and filled with hydrogen isotope fuel through a gas feed tube. If the target has a leak or the gas feeder is blocked, the experiments cannot be carried out successfully and waste much time. The authors have developed a system to check integrity of the targets. SF₆ is used instead of H₂ or D₂ because of its high refractive index and low diffusivity. When SF₆ is loaded into the target, the optical path length that passes through a target is longer than that of an evacuated target. The difference can be measured with an interferometer. Analyzing the interference images, it is possible to know whether the gas feeder is blocked and a leak is present. The validity of the system was experimentally confirmed.

Copyright (c) 2009 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

target fabrication, leak check, cryogenic target, fast ignition, laser fusion, interferometer

DOI: 10.1585/pfr.4.S1010

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References

• [1] H. Azechi and the FIREX Project, Plasma Phys. Control. Fusion 48, B267 (2006).
• [2] T. Norimatsu et al., Fusion Sci. Technol. 43, 339 (2003).
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• [4] S.M. Lambert et al., J. Appl. Poly. Sci. 65, 2111 (1997).
• [5] http://www.agc.co.jp/products/chemical/sf6_3.html (in Japanese)
• [6] S. Yoshikawa, Sinnkuu handobukku (in Japanese) (ULVAC, Japan, 1989) p.36.

This paper should be cited as follows:

Takeshi FUJIMURA, Mitsuo NAKAI, Akifumi IWAMOTO, Keiji NAGAI, Hirofumi HOMMA, Ken-ichi TANABE and Takayoshi NORIMATSU, Plasma Fusion Res. 4, S1010 (2009).