Developing x-ray Fresnel Diffractive-Refractive Radiography for Measuring Mutual Diffusion in Warm Dense Matter

The experimental measurement of evolving density gradients at the interface of two warm dense matter (WDM) species can inform us about dynamic transport properties and the equation of state. We have developed x-ray Fresnel diffractive-refractive radiography (FDR), which combines an ultra-small source size with an isochorically-heated buried wire sample, to create a high spatial resolution (~1µm) radiography platform for large laser facilities such as Omega and the NIF. The high spatial resolution allows for imaging of refractive and diffractive features at the interface^1,2,3, and therefore precise measurement of the evolving interface as the materials expand after heating. We will discuss results from our recent OMEGA experiments using plastic-coated 4µm W wire targets, where we saw significant expansion of the W into plastic, resulting in shock propagation and distinct changes in the refraction/diffraction features at the interface.

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