Understanding hydrodynamic material instabilities at extremes
The National Nuclear Security Administration science-based stockpile stewardship program funds research that will improve critical physics-based dynamic materials models. Los Alamos National Laboratory and Lawrence Livermore National Laboratory, as nuclear weapon design laboratories, are mandated to predict the reliability and durability of the nuclear weapons stockpile. This is done using state-of-the-art supercomputers and computer codes. It is also important to have state-of-the-art physics models in these codes. Los Alamos has theory experts in dynamic materials, thus creating powerful working groups when combined with experimental experts in Physics Division and elsewhere.
Key to the science-based stockpile stewardship program is making measurements of fundamental properties of materials relevant to the nuclear weapons program. Many of these properties involve the dynamic of how key materials respond to dynamic loading and subsequent unloading or research into hydrodynamic instabilities at extremes. Los Alamos performs research in many areas where fundamental properties are needed. Our dynamic materials program covers a broad range of applications including Department of Defense conventional weapons and armor; advanced nuclear reactor concepts, such as radiation-induced shock and damage; dynamic materials in industry, such as for aircraft wings and stress; as well as the stockpile stewardship work mentioned above.
Dynamic materials experiments over a wide range of stresses and strain rates are essential for studying constitutive relations (e.g., plasticity), damage (e.g., spall), equations of state, phase transitions and kinetics, and other properties. Physics Division scientists, in collaboration with others both inside and outside the Laboratory, conduct experiments on shocked materials at several facilities using high explosive and gun-flyer plate type drives, and laser drive. Observations of the material's response to these shock waves provide valuable insights into how they behave under dynamic loading.
Above: Richtmyer Meshkov Instability growth into vacuum (above) and into gas (below, 5 Atm Xenon). RMI Experiments address transport, particle breakup, and bubble saturation.