Skip to Main Content
Summary form only given. We have measured the production of 10 keV X-rays from low-density Ge-doped aerogel targets at the OMEGA laser. The targets were 1.2 mm long by 1.5 mm diameter beryllium cylinders filled with Ge-doped (20 atomic percent) SiO2 foam. The doped-foam density was 5 or 7 mg/cc. These targets are a major advance over previous doped aerogels: instead of suspending the dopant in the SiO2 matrix, the Ge atoms, with chemistry similar to Si, are incorporated directly in the matrix. Thus, the level of dopant is increased by more than a factor of six. Forty beams of the OMEGA laser (351 nm) illuminated the two cylindrical faces of the target with a total power that approached 20 TW. The laser interaction strongly ionizes the target (ne/ncrit = 0.15-0.20), and allows the laser-bleaching wave to supersonically ionize the high-Z emitter ions in the sample. The heating of the target was imaged with a gated (200 ps time resolution) X-ray framing camera, filtered to observe >8 keV. 2-D radiative-hydrodynamic calculations predict rapid and uniform heating over the whole target volume with minimal energy losses into hydrodynamic motion. Ge K-shell X-ray emission was spectrally resolved with a two-channel crystal spectrometer and recorded with temporal resolution with a set of calibrated photoconductive devices (PCDs). The calculations predict 150-200 J of X-ray energy output with 10 keV. The effect of shaping and delaying the laser pulse is studied. A full description of the experiment and the preliminary results of our analysis will be presented.