392 / 2019-02-28 17:10:13

Laser-driven Reservoir Experiment of Rayleigh-Taylor Instability in the Solid-state Metal at Megabar Pressures

Laser-driven; Shockless compression; Rayleigh-Taylor instability; Material strength.

全体主题 > Interface Instabilities at Extremes

Generally, deformation of metal materials under compression can change material parameters, like yield strength and work hardening character. In order to avoid metal melting to study the properties of solid-state matter at extremely high pressure but relatively low temperature, laser-driven reservoir experiments which can create shockless compression are performed in SG-Prototype Laser facilities.

In the experiments, laser driven shocks are used to pressurize the CH-based reservoir, which are strong enough to turn the reservoir into a weakly ionized plasma. Sinusoidal perturbations are machined at the metal plate surface, with ~40 μm wave wavelength and 1~2 μm amplitude. After the plasma unloads and piles up against the Al plate, producing a slowly increasing load pressure as it converts the kinetic energy into thermal pressure, as shown in Fig 1. The whole process has the potential of reaching very high pressures ~1 Mbar, ultrhigh strain rates > 106 s-1,accessing new regimes of solid-state dynamics relevant to meteor impact and crater formation studies.

The growth factors are measured by face-on radiography and the properties of the driving source are measured by VISAR. Compared with liquid-state predictions using classical theories, the experiment data shows strong stabilization of the Rayleigh-Taylor instability growth, which can be explained due to solid-state material strength, expecially a phonon drag mechanism.