[U04-P02] Ultrafast time-resolved XFEL diffraction study on shock-compressed corundum
Keywords:ultrafast measurement, XFEL, shock compression, corundum
In an XFEL facility SACLA, constructed at next to SPring-8, laser-driven shock-compression experiments are available with a high-power long-pulse laser system installed by Dr. N. Ozaki’s group and the Photon Pioneers Center in Osaka university. Using the high-power laser system (Nd:YAG, 532 nm, Hamamatsu Photonics K.K.) with the maximum energy of 50 J and pulse width of <10 ns (10-8 s), now we are able to reproduce ultrahigh-pressure and ultrahigh-temperature conditions to 1000 GPa (1 TPa) and >10,000 K regime. Here we show a result of in situ observation of shock-compressed polycrystalline corundum utilizing the high-power ns-pulsed pump laser with fs-pulsed intense probe X-ray based on pump-probe techniques.
The pump-probe measurements were carried out varying delay times of XFEL-probe exposure after flashing pump laser to generate shock wave on the surface of targets, which were composed of polypropylene ablator and corundum sample. After series of the pump-probe measurements, pseudo time-resolved profiles were obtained as a function of elapsed time after shock wave arrival to the sample through the ablator. As a result of the pump-probe laser-shock experiments, elastic/plastic compression, uniaxial/quasi-hydrostatic compression, and dynamic recrystallization were observed during shock-wave propagation in the corundum sample with the passing time in the maximum time-resolution of 0.2 ns. In the presentation, we will show the experimental setups and features of XRD profiles of the shock-compressed material in detail.