  Betatron radiation from laser wakefield accelerators is an ultrashort pulsed
source of hard, synchrotron-like x-ray radiation. It emanates from a centimetre
scale plasma accelerator producing GeV level electron beams. In recent years
betatron radiation has been developed as a unique source capable of producing
high resolution x-ray images in compact geometries. However, until now, the
short pulse nature of this radiation has not been exploited. This report
details the first experiment to utilise betatron radiation to image a rapidly
evolving phenomenon by using it to radiograph a laser driven shock wave in a
silicon target. The spatial resolution of the image is comparable to what has
been achieved in similar experiments at conventional synchrotron light sources.
The intrinsic temporal resolution of betatron radiation is below 100 fs,
indicating that significantly faster processes could be probed in future
without compromising spatial resolution. Quantitative measurements of the shock
velocity and material density were made from the radiographs recorded during
shock compression and were consistent with the established shock response of
silicon, as determined with traditional velocimetry approaches. This suggests
that future compact betatron imaging beamlines could be useful in the imaging
and diagnosis of high-energy-density physics experiments.
