High-repetition-rate X-ray imaging of hydrodynamic shock waves using a laser wakefield accelerator*

Betatron X-ray sources from laser wakefield accelerators provide a promising alternative for generating bright and ultrafast radiation at a fraction of the size and cost of conventional synchrotron facilities. The oscillation of plasma electrons in the wake bubble results in the emission of X-ray bursts with sub-micron source size, low beam divergence, and femtosecond duration. These radiation characteristics, in combination with a phase-contrast imaging technique and a high-repetition-rate accelerator, allow for capturing the complete time evolution of sub-micron scale dynamic systems. In this work we present the rst demonstration of high-repetition-rate phase-contrast imaging of dynamic phenomena using betatron X-rays. For this purpose we captured the interaction of a long laser pulse (200 ps, 1J) with a 30m stream of water. By taking advantage of the high-repetition-rate and high-resolution properties of the BELLA HTW betatron source we captured the full evolution of the propagating hydrodynamic shock, as well as experimentally observed multi-wave generation within the water target. Moreover, unprecedented experimental measurements of sheet-generated electric elds in the vicinity of the water jet have been made using electron beam radiography. Preliminary hydrodynamic simulations using CRASH and particle-in-cell simulations in FBPIC are used to complement the experimental measurements. This work paves the way tobetter diagnostic systems in High-energy-density physics experiments, where higher resolution and lower signal-to-noise ratio X-ray sources are needed.