Experimentally Constraining the High-Pressure Behavior of Beryllium

Beryllium is a commonly used material in high-pressure diffraction targets, but its high-pressure behavior has not been experimentally characterized. Its equation of state calculations have long predicted an on-Hugoniot HCP to BCC transition, but current experimental results have shown no evidence of this transition from the HCP phase. Laser-driven shock and shock-ramp compression experiments on a nanosecond time scale were performed on Beryllium samples using the Omega-EP Laser System at the University of Rochester. These experiments have allowed us to characterize the behavior of Beryllium at higher pressures and temperatures than have previously been explored, both on and off the Hugoniot. The results of the experiments, including VISAR and X-ray diffraction measurements will be presented, along with radiation hydrodynamics simulations, which were used to design the experiments and validate the results. The pulse shapes, which were designed using the ideal shape of ramp compression waves to avoid shock formation [DOI:10.1103/PhysRevE.78.066115], are also presented. Simulations which were performed using a recently developed dislocation-based strength model for high energy density conditions [arXiv:2110.06345] are presented as well.