Ultrafast In-situ Small Angle X-ray scattering in a Shocked Solid

When a shock wave reflects from a free surface a region of hydrostatic tension of sufficient magnitude may form causing voids to nucleate and grow which often leads to failure of the material (termed spall). We have conducted the first time resolved in-situ small angle x-ray scattering (SAXS) measurements of shock-loaded metal at the nanosecond timescale. The experiments utilized a Q-switched Nd:YAG laser to generate an ablatively driven shock wave while a custom x-ray detector in conjunction with a specialized synchrotron fill pattern was used to acquire the SAXS signal generated by a single photon bunch of less than 100 ps duration. A clear increase in scattering was observed over the timescale commensurate with the formation of a tensile loading wave as calculated from a one-dimensional hydrodynamic simulation of the experiment. This presentation will focus on the methodology and results of the first series of experiments, which were conducted on aluminum.