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H.F. Robey, J. Kane, B.A. Remington, O. Hurricane, H. Louis, R.J. Wallace (Lawrence Livermore National Laboratory), R.P. Drake, P. Keiter (University of Michigan), D. Arnett (University of Arizona), J. Knauer (University of Rochester)
Extensive observational evidence from core-collapse supernovae such as SN 1987A indicates that some form of large-scale hydrodynamic mixing process is required to explain the resulting light curves, spectra, and velocity of the heavier elements produced by explosive nucleosynthesis. High-resolution 2D numerical simulations to date, however, have been unable to reproduce these observations. An experimental testbed has been designed to study in a controlled laboratory setting some of the hydrodynamic issues believed to be of importance in this problem. These experiments are being conducted on the Omega Laser at the Laboratory for Laser Energetics (LLE), University of Rochester. To date, four separate aspects of the supernova explosion problem have been studied. In all cases, radiation from the Omega laser is used to drive a strong shock (M>>1) into the target materials. In a first series of experiments, a three-layer target with approximate density ratios of 10:1:0.1 was used to simulate the decreasing radial density profile of a SN progenitor. This experiment addresses the possible coupling, via propagation of a perturbed shock, between instability growth and mixing at the simulated (C+O)/He and He/H interfaces. A second series of experiments focused on the effect of spherical divergence on the growth of an initially imposed perturbation. Additional experiments have been conducted to study the role of dimensionality (2D vs. 3D initial perturbation) and modal content (single wavelength vs. multi-mode perturbation) in the evolution of a hydrodynamically unstable interface. In each case, numerical simulations are found to provide reasonable agreement with the experiments. Future work will aim to combine the phenomena studied here in isolation, will move toward more fully turbulent interface mixing, and will explore possible non-symmetrical explosion scenarios.
Work performed for the US DOE by UC LLNL under contract W-7405-Eng-48.