Imaging the Cold, Compressed Shell in Laser Implosions Using the Kα Fluorescence of a Titanium Dopant

168 LLE Review, Volume 72 The cold, compressed shell in laser-driven implosions can normally be imaged only by backlighting because its x-ray emission is very weak. However, a high-Z–doped shell can be imaged using the Kα line radiation, which fluoresces due to excitation by the intense radiation from the hot core. We show results from titanium-doped target implosions where the onedimensional spatial profile of the Ti Kα radiation yields the dimensions of the cold shell around the time of peak compression. This result, coupled with the shell areal density determined by the K-edge absorption, yields an estimate of the shell density. Since Kα emission depends only on the cold shell density (not its temperature), its image directly reflects the shell uniformity. Additionally, the measured absorption above the K-edge and the energy in the Kα line, which are directly related, are shown to indeed be consistent.