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Proceedings Paper

Indirect/direct hybrid drive implosion experiments with x-ray pre-irradiation
Author(s): Masaharu Nishikino; Hiroyuki Shiraga; Noriaki Miyanaga; Hiroaki Nishimura; Keisuke Shigemori; Manabu Heya; Hiroshi Azechi; Mitsuo Nakai; Kunioki Mima; Hideaki Takabe; Sadao Nakai; Tatsuhiko Yamanaka
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Paper Abstract

Indirect/direct-hybrid drive scheme to suppress the initial imprint of the laser irradiation nonuniformities has been proposed and investigated as a new drive scheme for inertial fusion. In direct drive inertial confinement fusion, initial imprinting of laser irradiation nonuniformity is considered to cause seeding of the perturbation on target surface in the very beginning of the irradiation which may be amplified by Rayleigh-Taylor instability in the acceleration phase of the implosion and be deleterious to efficient heating of the hot spark at the center of the compressed fuel core plasma. In indirect/direct-hybrid drive scheme, the target is first irradiated very uniformly with low-intensity soft x-ray prepulse from external sources apart from the target. Indirect x-ray pre-irradiation of the surface causes a pre- expansion layer of the plasma before the irradiation of the direct drive laser beam. When the drive beam comes later, the target has a substantial stand-off distance between the ablation front and the beam absorption region. Thus the thermal smoothing effect is expected to occur in this transport layer, and the initial imprint can be significantly reduced. We have demonstrated planar target experiments on the indirect/direct hybrid scheme and observed reduction of the initial imprint. Implosion experiments the indirect/direct hybrid drive spherical capsules with external x-ray sources has been started. Overall implosion was performed successfully.

Paper Details

Date Published: 11 January 2000
PDF: 8 pages
Proc. SPIE 3886, High-Power Lasers in Energy Engineering, (11 January 2000); doi: 10.1117/12.375140
Show Author Affiliations
Masaharu Nishikino, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroyuki Shiraga, Institute of Laser Engineering/Osaka Univ. (Japan)
Noriaki Miyanaga, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroaki Nishimura, Institute of Laser Engineering/Osaka Univ. (Japan)
Keisuke Shigemori, Institute of Laser Engineering/Osaka Univ. (Japan)
Manabu Heya, Institute of Laser Engineering/Osaka Univ. (Japan)
Hiroshi Azechi, Institute of Laser Engineering/Osaka Univ. (Japan)
Mitsuo Nakai, Institute of Laser Engineering/Osaka Univ. (Japan)
Kunioki Mima, Institute of Laser Engineering/Osaka Univ. (Japan)
Hideaki Takabe, Institute of Laser Engineering/Osaka Univ. (Japan)
Sadao Nakai, Faculty of Engineering and 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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