The Rayleigh-Taylor (RT) growth of 3D broadband nonuniformities was measured using x-ray radiography in spherical plastic shells accelerated by laser light at an intensity of approximately 2 x 10(14) W/cm(2). The 20- and 24-microm-thick spherical shells were imploded with 54 beams on the OMEGA laser system. The shells contained diagnostic openings for backlighter x rays used to image shell modulations. The measured shell trajectories and modulation RT growth were in fair agreement with 2D hydro simulations during the acceleration phase of the implosions with convergence ratios of up to approximately 2.2. Since the ignition designs rely on these simulations, improvements in the numerical codes will be implemented to achieve better agreement with experiments.

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We present a fully atomistic simulation study of a filler-to-filler contact embedded in a polymer matrix. The system consists of two silica spheres embedded in polyisoprene. Tests are presented showing that our polymerization algorithm achieves the proper polymer density and characteristic ratio. In this study, the polymer chains are not chemically attached to the particle surfaces and neither are they chemically cross-linked. We apply an external force in the direction of the axis of the system to one of the silica particles and determine the attendant distance to the second particle. The force–distance curves confirm a previously suggested loss mechanism, allowing us to estimate the dissipated energy when a contact is opened and closed due to cyclic loading. We also study the atomic structure and mobility inside the polymer close to the particle surfaces. We do find structural ordering in terms of three appreciable density peaks. The atom mobility inside these density shells is characterized by a fast and a slow process. The latter shows an apparent dependence on the shell’s distance from the particle surface.