Investigation of Carbon $X$-Pinches as a Source for Point-Projection Radiography

We report on the first investigations of the use of carbon fibers in an
X
-pinch load using a 250-kA linear transformer driver (LTD). Multiframe laser shadowgraphy is used to examine the evolution of the pinch and shows that carbon loads demonstrate wire expansion and cross-point pinch and gap formation as observed in
X
-pinches constructed from high Z materials. Radiographs taken using the carbon
X
-pinch as the source demonstrate both that sufficient flux is emitted to provide a good contrast image at source-to-image distances of > 10 cm and that the cross point produces a relatively small hot spot. Radiographs of a series of fine wires (5-30 mum) using X-rays > 500 eV demonstrated that 25-mum wires can be resolved in this energy range. Time-resolved X-ray emission measurements showed that, while emission in the hnu > 500 eV range shows long (> 100 ns) timescales, emission in the hnu > 1 keV range shows a multiple-peaked structure with durations as short as 20 ns.