Demonstration of an x-ray ring-aperture microscope for inertial-confinement fusion experiments

Abstract

We are investigating the use of annular (ring) apertures to image high-energy x-ray emission (≳4 keV) from inertial-confinement fusion targets. In our scheme, a coded image is formed on a detector (such as x-ray film) by x rays that pass through a narrow annulus cut in a sheet of high-Z material such as gold. Signal-to-noise ratio calculations show a factor of 10 advantage of ring-aperture imaging over conventional pinhole imaging. Simultaneous pinhole and ring-aperture images of small (≊20 μm diam), laser-driven, x-ray sources were obtained in recent experiments. We used a 10-μm-wide, 1-mm-diam annulus in a 6-μm thickness of gold; a 10-μm-diam pinhole was in the center of the annulus. Unfolds of the coded images have signal-to-noise ratios a factor of 20 larger than the pinhole images. The ring-aperture microscope is a promising new technique to image inertial-confinement fusion targets and other compact sources of high-energy x rays.