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In situ femtosecond x-ray diffraction measurements and ab initio molecular dynamics simulations were performed to study the liquid structure of tantalum shock released from several hundred gigapascals (GPa) on the nanosecond timescale. The results show that the internal negative pressure applied to the liquid tantalum reached $\ensuremath{-}5.6\text{ }(0.8)\text{ }\text{ }\mathrm{GPa}$, suggesting the existence of a liquid-gas mixing state due to cavitation. This is the first direct evidence to prove the classical nucleation theory which predicts that liquids with high surface tension can support GPa regime tensile stress.

The intricate spatial and energy distribution of magnetic fields, self-generated during high power laser irradiation (at $I{\ensuremath{\lambda}}^{2}\ensuremath{\sim}1{0}^{13}\ensuremath{-}1{0}^{14}\text{ }\text{ }\mathrm{W}.{\mathrm{cm}}^{\ensuremath{-}2}.\ensuremath{\mu}{\mathrm{m}}^{2}$) of a solid target, and of the heat-carrying electron currents, is studied in inertial confinement fusion (ICF) relevant conditions. This is done by comparing proton radiography measurements of the fields to an improved magnetohydrodynamic description that fully takes into account the nonlocality of the heat transport. We show that, in these conditions, magnetic fields are rapidly advected radially along the target surface and compressed over long time scales into the dense parts of the target. As a consequence, the electrons are weakly magnetized in most parts of the plasma flow, and we observe a reemergence of nonlocality which is a crucial effect for a correct description of the energetics of ICF experiments.

The first experimental evidence of the higher-order harmonic radiation generated by periodically modulated targets (gratings) irradiated by relativistic, ultrashort (