Demonstration of bright x-ray sources from solid and foam TiO2 targets at the Shenguang-III prototype laser facility

Enhancement of x-ray sources from laser-produced plasmas is significant in wide-ranging applications. Solid and foam TiO₂ targets were both used to generate bright x-ray sources at the Shenguang-III prototype laser facility, with a total laser power of 3.2 TW. The new foam targets were with an ultra-low initial density of 8.1 mg/cm³ and a high Ti fraction of 33 sat. %. By absolute measurements, the multi-keV x rays of the 4 keV-7 keV band and 1.6 keV-4.4 keV band and the total x rays above 0.1 keV of the foam target have simultaneously shown conversion enhancements of 1.4, 3.1, and 2.3 times, respectively, compared with the solid target. A much larger emission volume and an average electron temperature of 3.2 keV by moving the foci of laser beams inner were obtained for the foam target, providing a good condition for multi-keV x-ray production.