Characterization of National Ignitition Facility cryogenic beryllium capsules using x-ray phase contrast imaging

Beryllium capsules filled with cryogenic deuterium and tritium fuel layers may provide many advantages for obtaining ignition at the National Ignition Facility. However, characterizing the uniformity and thickness of the frozen fuel layer in such a target is challenging since traditional x-ray radiography techniques, which rely on absorption for image contrast, cannot provide sufficient contrast to image the fuel layer in these low-Z materials. We propose using x-ray phase contrast imaging, which relies on gradients in the refractive index and wave interference, to characterize fuel layer uniformity. We present numerical modeling results of x-ray phase contrast imaging demonstrating the feasibility of this method for target characterization, discuss the necessary x-ray source characteristics, and present concepts for using this technique in the context of dynamic high density plasma experiments. (C) 2004 American Institute of Physics.