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The fast diffraction set-up at P02.2 at PETRA-III: Time-resolved x-ray diffraction of tera-pascal per second compression

The fast diffraction set-up at the Extreme Conditions Beamline (P02.2) at PETRA-III offers the opportunity to performed time-resolved x-ray diffraction on samples which are dynamically-compressed using piezo-driven diamond anvil cells (dDACs). Using this platform, it is possible to track the structural behaviour of materials during a compression ramp and investigate the compression-rate dependence of material properties such as phase transition boundaries. Crucial to this set-up is the high time-resolution achieved through the use of two hybrid pixel photon-counting GaAs LAMBDA* detectors, each of which have a minimum exposure time of 0.5 ms and a collection rate of 2 kHz when run in a continuous read-out mode.

The maximum compression rate which has been achieved using this set-up is illustrated by the fast compression of Au, where the sample was compressed from 1 to 140 GPa in 2.5 ms. The timing of the two detectors was offset by 0.25 ms to give an effective repetition rate of 4 kHz, which enabled the collection of multiple x-ray diffraction patterns during the compression.  In the middle of the ramp, the compression rate reaches up to 160 TPa/s, the fastest compression which has been achieved using this set-up.

Contour plot of the integrated diffraction images collected from one of the LAMBDA detectors (left) and the time-dependent pressure profile and compression rate (right) during the fast compression of Au in the dDAC. The compression rate reaches a maximum of 160 TPa/s in the middle of the ramp.



Using this platform, it is possible to investigate the behaviour of materials at intermediate strain-rates that are not accessible using conventional static or shock compression techniques. The pressure profile of the sample can be carefully controlled to suit the needs of the experiment, which offers exciting opportunities for future research including the simulation of processes such as meteorite impacts on the surface of the Earth or the propagation of seismic waves.

Courtesy of P02.2 PETRA-III

https://aip.scitation.org/doi/10.1063/1.5098993

*LAMBDA detectors information could be found at www.x-spectrum.de & at the booth of X-Spectrum GmbH. New operating modes are allowing for even higher time resolution.




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