Numerical simulatin of supernova-relevant laser-driven hydro experiments on OMEGA

In ongoing experiments performed on the OMEGA laser [J. M. Soures et al., Phys. Plasmas 5, 2108 (1996)] at the University of Rochester Laboratory for Laser Energetics (LLE), nanosecond laser pulses are used to drive strong blast waves into two-layer targets. Perturbations on the interface between the two materials are unstable to the Richtmyer-Meshkov instability as a result of shock transit and the Rayleigh-Taylor instability during the deceleration-phase behind the shock front. These experiments are designed to produce a strongly shocked interface whose evolution is a scaled version of the unstable hydrogen-helium interface in core-collapse supernovae such as SN 1987A. The ultimate goal of this research is to develop an understanding of the effect of hydrodynamic instabilities and the resulting transition to turbulence on supernovae observables that remain as yet unexplained. The authors are, at present, particularly interested in the development of the Rayleigh-Taylor instability through the late nonlinear stage, the transition to turbulence, and the subsequent transport of material within the turbulent region. In this paper, the results of numerical simulations of 2D single and multimode experiments are presented. These simulations are run using the 2D Arbitrary Lagrangian Eulerian (ALE) radiation hydrodynamics code CALE [R. T. Barton, Numerical Astrophysicsmore » (Jones and Bartlett, Boston, 1985)]. The simulation results are shown to compare well with experimental radiography. A buoyancy-drag model captures the behavior of the single-mode interface, but gives only partial agreement in the multi-mode cases. The Richtmyer-Meshkov and target decompression contributions to the perturbation growth are both estimated and shown to be significant. Significant dependence of the simulation results on the material equation of state (EOS) is demonstrated, and the prospect of continuing the experiments to conclusively demonstrate the transition to turbulence is discussed.« less

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