Indirect-direct hybrid target experiments with the GEKKO XII laser

H. Nishimura, H. Shiraga, H. Azechi, N. Miyanaga, M. Nakai, N. Izumi, M. Nishikino, M. Heya, K. Fujita, Y. Ochi, K. Shigemori, N. Ohnishi, M. Murakami, K. Nishihara, R. Ishizaki, H. Takabe, K. Nagai, T. Norimatsu, M. Nakatsuka, T. YamanakaS. Nakai, C. Yamanaka, K. Mima

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


A new fusion capsule drive scheme was investigated. The capsule is illuminated by a low intensity thermal X ray pulse prior to the main drive pulse. This leads to a noticeable suppression of initial imprinting by the drive beam because of thermal smoothing in the preformed plasma. Of the several types of indirect-direct hybrid target, the authors investigated the hybrid effect for two types. One is a foam hybrid, in which the fuel capsule has a low density foam layer attached directly on its surface and where pulsed radiation generated from a thin high Z layer on the foam propagates through the foam, creating a preformed plasma. The other is an external hybrid, in which the capsule is illuminated by external X ray radiation generated using different beams from the capsule drive beams. The hybrid effect was demonstrated for both types by imposing an initial imprint on a planar target with an intensity modulated beam, and subsequent non-uniformity growth due to Rayleigh-Taylor instability was observed by means of face-on backlighting. The observed suppression due to the presence of the preformed plasma is interpreted by a cloudy day model for both hybrids. Capsule implosion experiments have also been started. The overall implosion dynamics observed is replicated by 1-D hydrocode simulations. Preliminary results from the implosion experiments are presented.

Original languageEnglish
Pages (from-to)547-556
Number of pages10
JournalNuclear Fusion
Issue numberSPEC. ISS. 3
Publication statusPublished - 2000


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