The strength of shock-loaded single crystal tantalum [100] has been experimentally determined using in situ broadband x-ray Laue diffraction to measure the strain state of the compressed crystal, and elastic constants calculated from first principles. The inferred strength reaches 35 GPa at a shock pressure of 181 GPa and is in excellent agreement with a multiscale strength model [N. R. Barton et al., J. Appl. Phys. 109, 073501 (2011)], which employs a hierarchy of simulation methods over a range of length scales to calculate strength from first principles.

Mechanisms of nano-hole drilling due to nano-probe intense electron beam irradiation on a stainless steelWe have performed quasi-isentropic compression experiments on radiation-damaged stainless steel. The samples were dynamically loaded by Sandia National Laboratory's Z accelerator with a ramp compression wave. Sample/window interface velocities were recorded with VISAR. The velocity histories suggest a sudden volume reduction of the material above 40 kbar caused by the collapse of nanosized voids. This is predicted by a theoretical model of void collapse based on the emission of vacancy-type dislocations loops. We compare the results of these experiments to hydrodynamic calculations performed using a constitutive model which is derived from the atomistic void collapse mechanism.

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A new diagnostic for measuring Bragg diffraction from a laser-driven crystal using a 100ps 17.5 kV x-ray backlighter source is designed and tested successfully at the Omega EP laser facility on static Mo and Ta single crystal samples using a Mo Ka backlighter. The Bragg Diffraction Imager (BDI) consists of a heavily shielded enclosure and a precisely positioned beam block, attached to the main enclosure by an Aluminum arm. Image plate is used as the x-ray detector. The diffraction lines from Mo and Ta <222> planes are clearly detected with a high signal-to-noise using the 17.5 keV and 19.6 keV characteristic lines generated by a petawatt-driven Mo foil. This technique will be applied to shockand ramp-loaded single crystals on the Omega EP laser.