Powder diffraction from solids in the terapascal regime

A method of obtaining powder diffraction data on dynamically-compressed solids has been implemented at the Jupiter and OMEGA laser facilities. Thin powdered samples are sandwiched between diamond plates, and ramp compressed in the solid phase using a gradual increase in the drive-laser intensity. The pressure history in the sample is determined by back-propagation of the measured diamond free-surface velocity. A pulse of x-rays is produced at the time of peak pressure by laser illumination of a thin Cu or Fe foil, and collimated at the sample plane by a pinhole cut in a Ta substrate. The diffracted signal is recorded on x-ray sensitive material, with a typical d-spacing uncertainty of approximately 0.01 {\AA}. This diagnostic has been used up to 1.2 TPa (12 Mbar) to verify the solidity, measure the density, constrain the crystal structure, and evaluate the strain-induced texturing of a variety of compressed samples spanning atomic numbers from 6 (carbon) to 82 (lead).