1. Plasma kinetic effects on interfacial mix and burn rates in multispatial dimensions
- Author
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Kevin J. Bowers, Erik Vold, Lin Yin, W. D. Nystrom, Brian J. Albright, and Robert Bird
- Subjects
Physics ,Plasma ,Condensed Matter Physics ,Kinetic energy ,01 natural sciences ,Instability ,Molecular physics ,010305 fluids & plasmas ,Atwood number ,Physics::Plasma Physics ,0103 physical sciences ,Nuclear fusion ,Total pressure ,010306 general physics ,Inertial confinement fusion ,Scaling - Abstract
The physics of mixing in plasmas is of fundamental importance to inertial confinement fusion and high energy density laboratory experiments. Two- and three-dimensional (2D and 3D) particle-in-cell simulations with a binary collision model are used to explore kinetic effects arising during the mixing of plasma media. The applicability of the one-dimensional (1D) ambipolarity condition is evaluated in 2D and 3D simulations of a plasma interface with a sinusoidal perturbation. The 1D ambipolarity condition is found to remain valid in 2D and 3D, as electrons and ions flow together required for J = 0. Simulations of perturbed interfaces show that diffusion-induced total pressure imbalance and hydroflows flatten fine interface structures and drive rapid atomic mix. The atomic mix rate from a structured interface is faster than the ∼ t scaling obtained from 1D theory in the small-Knudsen-number limit. Plasma kinetic effects inhibit the growth of the Rayleigh-Taylor instability at small wavelengths and result in a nonmonotonic growth rate scaling with wavenumber k with a maximum at a low k value, much different from Agk (where A is the Atwood number and g is the gravitational constant) as expected in the absence of plasma kinetic effects. Simulations under plasma conditions relevant to MARBLE separated-reactant experiments on Omega and the NIF show kinetic modification of DT fusion reaction rates. With non-Maxwellian distributions and relative drifts between D and T ions, DT reactivity is higher than that inferred from rates using stationary Maxwellian distributions. Reactivity is also found to be reduced in the presence of finite-Knudsen-layer losses.
- Published
- 2019
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