Hard x-ray radiography with a 1D-imaging micro-flag backlighter driven by NIF-ARC

Plastic deformation of samples ramp compressed to Mbar pressures at high strain rates forms the basis of ongoing dynamic material strength experiments at the National Ignition Facility. Hard x-ray radiography (>40 keV) is the primary means of measuring the evolution of these samples and initial trials with a source driven by the ARC laser suggest that a significant gain in spatio-temporal resolution can be achieved over the existing NIF-driven source, in agreement with expectations from previous work.



We present updated results from a further ARC shot (~2 kJ, 10 ps pulse) onto a 5-μm-thick dysprosium ‘micro-flag’ target which radiographs 100-μm-thick diamond-turned Pb test objects at high resolution, supported by analysis using the 3D Monte Carlo code GEANT4. We observe gradients in brightness, x-ray spectrum and resolution across the field of view which result primarily from the source geometry. By modeling the full 10-layer image plate detector stack and diagnostic housing we assess techniques such as image stacking for noise suppression in the context of reducing uncertainties in future dynamic strength experiments at NIF.



This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contact No. DE-AC52-07NA27344.