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Measured laser fusion gains reproduced by self-similar volume compression and volume ignition for NIF conditions

Published online by Cambridge University Press:  01 November 1998

HEINRICH HORA
Affiliation:
Department of Theoretical Physics, University of New South Wales, Sydney 2052, Australia
H. AZECHI
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
Y. KITAGAWA
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
K. MIMA
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
M. MURAKAMI
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
S. NAKAI
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
K. NISHIHARA
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
H. TAKABE
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
C. YAMANAKA
Affiliation:
Institute of Laser Technology, Osaka University, Souita Osaka 565, Japan
M. YAMANAKA
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan
T. YAMANAKA
Affiliation:
Institute of Laser Engineering, Osaka University, Souita Osaka 565, Japan

Abstract

The recent high core gains of 29% in laser fusion experiments at the LLE Rochester are evaluated and compared with related earlier measurements where surprisingly the self-similarity model for volume compression provides a common description. This is a proof that the isentropic conditions of stagnation-free compression were mostly fulfilled at the optimized experimental gains, in contrast to highly entropy-producing shock and central spark conditions. Some projections are given of how these results may be generalized to volume ignition for the parameters of the NIF (National Ignition Facility). The proof of stagnation-free volume compression for the best laser fusion gains indicates the advantages of volume ignition, which not only is ‘robust’ and simply follows the natural adiabatic compression, but also is much less sensitive to instabilities and mixing. However, its essential advantage is that it is free from symmetry problems – in contrast to spark ignition, with its spherical detonation front.

Type
Research Article
Copyright
1998 Cambridge University Press

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