333 / 2019-02-26 17:44:27

Experimental Study of Highly Compressed Warm Dense Aluminum and Silicon by using X-ray Absorption Spectra

Warm Dense Matter; X-ray absorption Spectrum; Shock Compression

全体主题 > Fundamental Physics at Extremes

Understanding the properties of highly compressed Warm Dense Matter is important in the research field of planetary interiors and inertial confinement fusion. X-ray absorption can provide direct information about the density, temperature, electronic, and ionic structures of dense matter. Thus, creating in a laboratory highly compressed matter and obtaining detailed measurements of x-ray absorption spectra is very appealing.
At ShenGuang Laser Facility, using a short laser interaction with a high-Z target as a backlighter and a crystal spectrometer, the time-resolved K-edge absorption measurements of the Aluminum and Silicon at the states created by x-ray radiation-driven shock colliding compression were carried out. Extreme states of the Aluminum and Silicon (from solid density to about 10g/cc) were reached. The shifts and broadenings of the K-shell edge for the compressed sample are obvious. The experimental temperatures by slope fitting of the K-edge are consistent with the hydrodynamic simulation. The experimental K-edge shifts are in general agreement with the theoretical calculations along shock conditions. Moreover, using a long laser (2ns) for backlighter and an x-ray streak crystal spectrometer, continuous variations of XANES (X-ray Absorption near Edge Structure) during the shock compression were obtained in one shot. The K-shell edge and the modulations of the XANES varied with the matter conditions.
This work shows the progress of the experimental study of WDM at ShenGuang Laser Facility, and the K-shell absorption can provide a unique capability to probe matter at extreme conditions.