Equation of state measurements for beryllium in the ICF capsule regime

The dynamic response of beryllium on nanosecond time scales is important for controlling symmetry during the implosion of the fuel capsule in inertial confinement fusion. Particularly important is the behavior up to about 200 GPa, covering the foot of the implosion drive. We have performed experiments to measure the equation of state (EOS) and flow stress of beryllium, and to investigate solid-solid phase transitions and melting, using flyer impact and isentropic compression by pulsed electromagnetic fields at Z, and shocks induced by direct laser irradiation at TRIDENT. The principal diagnostic was VISAR velocimetry; transient x-ray diffraction was also used on some TRIDENT experiments. The Hugoniot and isentrope data were consistent with previously-reported EOS. The flow stress was inferred from elastic precursor waves to be about 6 GPa in the (0001) direction on these time scales, with significant sensitivity to orientation. Possible evidence was observed of the hex-bcc transition and of melting