Hydrodynamic instabilities are a dominant feature of most High-Energy-Density (HED) systems. The growth of these instabilities depends on the material phase and intrinsic fields that perturb the hydrodynamics away from an ideal fluid flow. For example, many materials can retain significant resistance to shear deformation up to Mbar pressures in the solid-state. This strength is known to decrease Rayleigh-Taylor (RT) growth rates relative to those predicted and observed under ideal hydrodynamic conditions. Little is known, however, about the effects of material strength on the growth of the Richtmyer-Meshkov (RM) instability in general and, in particular, as phase boundaries (solid-solid, solid-liquid, etc.) are approached. Specifically, the behavior of shock and release waves undergo sharp changes near these boundaries, suggesting that significant changes to the growth rate of instabilities at material boundaries, i.e., RM, may occur at perturbed solid-state interfaces. The goal of the proposed research is to study these transitional properties and their effect on RM growth by measuring perturbation amplitudes in solid targets shocked into different material phases. Experiments will study the behavior of two materials with large density differences separated by a single mode (sinusoid) interfacial perturbation. An incident shock will be driven into a material that undergoes a solid-solid phase transition at pressures achievable by available long-pulse driver facilities (e.g., tin), and a transmitted shock will propagate into a phase stable material with negligible strength (e.g., PMMA). Laser-launched flyer plate experiments performed at the Trident laser facility (Los Alamos National Laboratory) will create a rippled shock and a growing interfacial perturbation as the incident planar shock passes over the rippled interface. A Transient Imaging Displacement Interferometer (TIDI) will measure perturbation amplitude at the bimaterial interface. A fast framing camera will capture surface displacement maps from the TIDI at ~10 ns intervals with sub-ns temporal resolution and 10 nm out-of-plane displacement sensitivity. The incident shock pressure will be adjusted so that it corresponds to just below or just above the phase transition. Experiments will then measure the growth rate of the perturbation by adjusting the TIDI timing for each pressure condition. The simultaneous development of phase-aware material strength models will allow studying strength and phase change effects on the RM instability in solids. These flexible models will be the first of their kind and will be validated by the novel experimental approach described above. This collaborative work will take advantage of unique and complementary capabilities available in each institution. On one hand, the world-class dynamic testing and in-situ diagnostic capabilities at LANL are indispensable to perform the required measurements. On the other hand, state of the art processing and characterization techniques at ASU, as well as the existing modeling capabilities will make it possible to fabricate the samples needed, and perform the analysis of experimental data to formulate, calibrate and validate the proposed models.
|Effective start/end date||8/15/12 → 8/14/16|
- US Department of Energy (DOE): $432,000.00