Dynamic plasticity of beryllium in the inertial fuel fusion capsule regime

TL;DR

This study investigates the dynamic plastic response of beryllium under laser-induced shock loading, combining experimental measurements with modeling to understand elastic and plastic wave behavior relevant to inertial confinement fusion.

Contribution

It provides new insights into beryllium's plasticity under shock conditions using combined velocimetry, x-ray diffraction, and dislocation-based modeling.

Findings

Elastic waves up to ~1 km/s observed

Plastic precursor modeled with dislocation dynamics

Lattice spacing changes confirm stress states

Abstract

The plastic response of beryllium was investigated during loading by laser-induced shock waves, using surface velocimetry and in-situ x-ray diffraction. Results from loading by thermal x-rays (hohlraum) were consistent with more extensive studies using laser ablation. Strong elastic waves were observed, up to ~1 km/s in free surface speed, with significant structure before the arrival of the plastic shock. The magnitude and shape of the precursor could be reproduced with a plasticity model based on dislocation dynamics. Changes in lattice spacing measured from the x-ray diffraction pattern gave a direct measurement of uniaxial compression in the elastic wave, triaxial flow from the decay of the precursor, and triaxial compression in the plastic shock; these were consistent with the velocity data. The dynamic strength behavior deduced from the laser experiments was used to help interpret surface velocity data around the onset of shock-induced melting. A model of heterogeneous mixtures is being extended to treat anisotropic components, and spall.