Measurements of Rayleigh–Taylor instability growth of laser-shocked iron–silicon alloy

The Rayleigh-Taylor (RT) instability of liquid iron alloys is important for understanding the core formation mechanism in the Earth. Here we first report the measurement of RT instability growth for a liquid iron-silicon (Fe-Si) alloy, which is one of the major candidate for the material of the Earth's core, using a high power laser. We optimized the measurement setup and analytical technique to observe the growth of perturbation on an Fe-Si sample surface. The growth of perturbation amplitude on the Fe-Si alloy under high pressure and temperature was successfully observed using in situ X-ray radiography. The growth rate of the RT instability for the Fe-Si alloy on about 1000 GPa was estimated to be 0.3 ns(-1).