High-energy Kα radiography using high-intensity, short-pulse lasers

The characteristics of 22-40 keV K alpha x-ray sources are measured. These high-energy sources are produced by 100 TW and petawatt high-intensity lasers and will be used to develop and implement workable radiography solutions to probe high-Z and dense materials for the high-energy density experiments. The measurements show that the K alpha source size from a simple foil target is larger than 60 mu m, too large for most radiography applications. The total K alpha yield is independent of target thicknesses, verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K alpha radiation. One-dimensional radiography experiments using small-edge-on foils resolved 10 mu m features with high contrast. Experiments were performed to test a variety of small volume two-dimensional point sources such as cones, wires, and embedded wires, measured photon yields, and compared the measurements with predictions from hybrid-particle-in-cell simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the high-energy range. An initial look at some of these detector issues is also presented. (c) 2006 American Institute of Physics.