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(IFP/16(R)) Nonlinear Theory of Laser Imprint, Richtmyer-Meshkov and Rayleigh-Taylor Instabilities

K. Nishihara¹⁾, M. Murakami¹⁾, C. Matsuoka²⁾, N. Ohnishi¹⁾, T. Ikegawa¹⁾, Y. Fukuda¹⁾, A. Sunahara¹⁾, H. Nagatomo¹⁾, H. Takabe¹⁾, K. Mima^1)
 
1) Institute of Laser Engineering, Osaka University, Osaka, Japan
²⁾ Faculty of Science, Ehime University, Matsuyama, Japan

Abstract.  Implosion process in laser fusion can be divided into three phases: start-up, acceleration and stagnation phases and various hydrodynamic instabilities appear in each phase. Analytical models are developed to study nonlinear evolutions of the hydrodynamic instabilities in these phases, and compared with multi-dimensional simulations. We mainly discuss the formation of double spiral structures caused by the singularity of vorticity in the RM spikes, the effect of the ablative stabilization in nonlinear growth of the RT instability with a finite bandwidth and the effect of the radiation cooling on the stability in the stagnation phase. Various smoothing effect, such as radiation smoothing and hydrodynamic smoothing, are also studied in the start-up phase.

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