High-Resolution X-Ray Imaging of Blast-Wave–Driven Instabilities *

Two-dimensional x-ray radiography was used to measure hydrodynamic-instability growth at a modulated, blast-wave–driven interface between a laser-driven plastic pusher and a low-density foam. The ablatively driven system was generated on the OMEGA Laser System with up to few-nanosecond-duration laser pulses at focused intensities above 10¹⁴ W/cm². Radiographs were obtained using a 4.75-keV Ti He-like resonance line area backlighting source coupled to a Fresnel phase zone plate imager and an SI-800 x-ray charge-coupled device. Resolution grid tests confirm the achievement of micron-level static spatial resolution. With few-micron dynamic resolution, the data show clear bubble and spike growth and the effects of vorticity and asymmetric shear on the spike-tip morphology. Of note is the clarity in the imaged material response to the counter-rotating vortex pairs that form at the spike tips during roll-up. The data are compared with synthetic x-ray radiographs generated from numerical simulations using the computer codes DRACO and SPECT3D.