Please contact Rachel Wise at [email protected] for connection information

The behaviour of materials subject to intense bursts of relatively low energy X-rays is a complex issue that affects several fields, including how plasma ablates from hohlraum walls in ICF experiments, and how interstellar dust and debris are affected by supernovae. In the defence sector, there are concerns surrounding how such X-rays would affect the solar panels used in communication or reconnaissance satellites.

In order to start exploring this phenomenon, we have performed experiments observing the interaction of soft X-rays with planar silicon targets. The X-Ray bursts were produced by the implosion of wire array Z-Pinches on the MAGPIE pulsed power facility (1.4 MA peak-current, 240 ns rise-time). Intensities on target were 200-400J per sq cm over ~25ns timescales and have a spectra dominated by continua with temperature ~150eV. The X-rays produced dense outflows of plasma from the silicon that were diagnosed with a state-of-the-art suite of spatially and temporally resolved diagnostics including interferometry, optical Thomson scattering, Faraday probing and fast frame optical self-emission imaging. The outflows displayed a remarkably uniform structure, and had a characteristic velocity that appeared dependent on the X-ray intensity.

Results from the experiments are compared to predictions from the Gorgon MHD code, incorporating different spectral models. Plans for future experiments are described, including experiments at higher and lower intensities, over different timescales, with different spectral properties and onto different materials such as SiO2 and GaAs.