Computational Analysis of Reactivity and Atomic Mixing by Plasma Transport

On-going work involves the development of models and computational analyses for accurate prediction of nuclear reactions in plasma species undergoing mixing and the generation of atomically mixed components. Mix at the atomic level is driven by kinetic transport which is represented here as diffusivity in a classical plasma fluid (Braginskii-like Transport) driven by multiple gradient quantities. The atomic mix components are expressed as volume fractions in computational cells containing mixed materials. This feeds into an algorithm, SINGE, which distinguishes isotopes in mixed and in unmixed materials to predict nuclear reactions in the ICF (Inertial Confinement Fusion) regime. Several test cases are examined in simple geometry involving the diffusive-like mixing of low Z and higher Z components across a common interface, such as D-T fuel mixing with H-C in a hydrocarbon shell. Differences are examined for spatial distribution and reactivity results when computing transport accurately on an individual isotopic basis and for results computing transport on a material basis with collision rates determined as a weighted average for the isotopes contained in each material. Modifications to collision rates account for high-speed species inter-streaming. The plasma transport provides a physical basis for the atomic mixing needed for accurate reaction rates during mixing and is an alternative to existing reactive mix options based on turbulence models which do not account for mixing at the atomic level.