| Abstrakt: |
AbstractAn experimental study on the angular distribution and conversion of multi-keV X-ray sources produced from 2 ns-duration 527nm laser irradiated thick-foil targets on Shenguang II laser facility (SG-II) is reported. The angular distributions measured in front of the targets can be fitted with the function of f(?)?=??+?(1??)cos?? (? is the viewing angle relative to the target normal), where ??=?0.41???0.014, ??=?0.77???0.04 for Ti K-shell X-ray sources (~4.75 keV for Ti K-shell), and ??=?0.085???0.06, ??=?0.59???0.07 for Ag/Pd/Mo L-shell X-ray sources (2?2.8?keV for Mo L-shell, 2.8?3.5?keV for Pd L-shell, and 3?3.8?keV for Ag L-shell). The isotropy of the angular distribution of L-shell emission is worse than that of the K-shell emission at larger viewing angle (>70?), due to its larger optical depth (stronger self-absorption) in the cold plasma side lobe surrounding the central emission region, and in the central hot plasma region (emission region). There is no observable difference in the angular distributions of the L-shell X-ray emission among Ag, Pd, and Mo. The conversion efficiency of Ag/Pd/Mo L-shell X-ray sources is higher than that of the Ti K-shell X-ray sources, but the gain relative to the K-shell emission is not as high as that by using short pulse lasers. The conversion efficiency of the L-shell X-ray sources decreases with increasing atomic numbers (or X-ray photon energy), similar to the behavior of the K-shell X-ray source. [ABSTRACT FROM AUTHOR] |
