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Proceedings Paper

Observation of low-mode implosion nonuniformity of plastic-shell targets in the acceleration phase
Author(s): Manabu Heya; Hiroyuki Shiraga; Masaharu Nishikino; Shinsuke Fujioka; Kazuhisa Fujita; Yoshihiro Ochi; Nobuhiko Izumi; Noriaki Miyanaga; Hiroaki Nishimura; Hiroshi Azechi; Hideaki Takabe; Kunioki Mima; Tatsuhiko Yamanaka
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Paper Abstract

IN order to directly observe low-mode implosion nonuniformities, especially of l equals 1, which prevents stable formation of a hot spark in the compressed core plasma at the final stage of the implosion, a series of direct-drive implosion experiments has been performed at the Gekko-XII glass laser facility by using gas-filled plastic- shell targets. Partially coherent light (PCL) was used as a drive laser to suppress middle- to higher-modes of the irradiation nonuniformity down to approximately 1 percent. A clear shift from the center of the chamber and a slight crosswise structure were seen in the time- and space- resolved shape of the shell in the accelerating phase with an x-ray framing camera and absorbed laser intensity were also estimated by using a rocket equation. In order to confirm the property of these results, separate experiments under similar laser conditions were performed by using Au- coated sapphire spheres as surrogate target. The x-ray intensity distribution on the circumference of the target in the XFCs image, which is strongly dependent on the drive nonuniformity in the accelerating shell resulted from the l equals 1 drive nonuniformity. In our experiments, the l equals 1 drive nonuniformity due to some reproducible factors was found to be of the order of approximately 10-20 percent.

Paper Details

Date Published: 11 January 2000
PDF: 8 pages
Proc. SPIE 3886, High-Power Lasers in Energy Engineering, (11 January 2000); doi: 10.1117/12.375139
Show Author Affiliations
Manabu Heya, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroyuki Shiraga, Institute of Laser Engineering/Osaka Univ. (Japan)
Masaharu Nishikino, Institute of Laser Engineering/Osaka Univ. (Japan)
Shinsuke Fujioka, Institute of Laser Engineering/Osaka Univ. (Japan)
Kazuhisa Fujita, Institute of Laser Engineering/Osaka Univ. (Japan)
Yoshihiro Ochi, Institute of Laser Engineering/Osaka Univ. (Japan)
Nobuhiko Izumi, Institute of Laser Engineering/Osaka Univ. (United States)
Noriaki Miyanaga, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroaki Nishimura, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroshi Azechi, Institute of Laser Engineering/Osaka Univ. (Japan)
Hideaki Takabe, Institute of Laser Engineering/Osaka Univ. (Japan)
Kunioki Mima, Institute of Laser Engineering/Osaka Univ. (Japan)
Tatsuhiko Yamanaka, Institute of Laser Engineering/Osaka Univ. (Japan)


Published in SPIE Proceedings Vol. 3886:
High-Power Lasers in Energy Engineering
Kunioki Mima; Gerald L. Kulcinski; William J. Hogan, Editor(s)

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