X-ray microscopy of inertial fusion targets using a laser-produced plasma as an x-ray source

Abstract

With the advent of an ablation layer coating technology for mechanically nonsupported inertial fusion targets, the conventional optical interferometric technique for the characterization of these targets is no longer feasible since the batch process of this bounce coating technique makes it difficult to account for individual targets. A soft x-ray contact microradiography method, which was developed for this purpose, is limited in resolution by the 0.5-μm grain size of the photographic medium used. Utilization of an x-ray sensitive photoresist extends the resolution to as low as 50 Å. The use of a laser-generated x-ray source for x-ray microscopy appears to require much less energy than published photoresist sensitivity data. A single-shot exposure of 100 J, 0.527-μm wavelength, and 1-ns laser shot suffices for image formation. The resulting x-ray micrographs show a higher spatial resolution than the images obtained by previous radiography techniques. The resolution of 0.2 μm in the present study is due to the finite size of the x-ray source.