Hohlraum-driven simultaneous VISAR and radiography experiments to study the effect of artificially implanted helium bubbles on material strength

We developed an experimental platform to investigate the plastic deformation dynamics of materials under extreme conditions. The platform utilizes the hohlraum-driven Rayleigh-Taylor (RT) strength setup with a reservoir-gap configuration to achieve ramp compression [1]. Key features include simultaneous VISAR measurements to analyze the drive conditions and x-ray radiography to infer high pressure plastic flow and material strength based on sample ripple growth. This platform was applied to study the strength differences between pure and helium-implanted lead samples loaded identically. Helium bubbles commonly form in materials as they age through radioactive alpha decay, significantly influencing their mechanical properties. This paper presents the performance evaluation of the experimental platform. The experimentally measured strength differences are compared with predictions from a porosity-mechanics-based model designed for materials containing helium bubbles. We find that the difference in strength between pure and helium-implanted materials is less than 5% under conditions of 350 GPa peak pressure and a strain rate of ~10⁷ s⁻¹.



[1] S. T. Prisbrey, H. -S. Park et al., Phys. Plasmas, 19, 056311 (2012)