Investigation of fast electron-induced K$\alpha $ x-rays in laser-produced blow-off plasma

Interaction of a high-power, short-pulse laser exceeding the peak intensity of 10 18 W/cm$^2$ with solid targets is an efficient source of characteristic x-ray. We have quantitatively studied the K$\alpha $ x-ray production in laser-produced expanding plasma. Using two-beam TITAN laser at LLNL, a multilayered target was irradiated by the long pulse laser to create blow plasma and by the short pulse laser to generate fast electrons at the delay of 0, 1, 6 and 8 ns. The K$\alpha $ yields and monochromatic images were recorded with a Bragg crystal spectrometer and spherical crystal imager. The results show a decrease of the total K$\alpha $ yields by a factor of 8 from the refluxing to non-refluxing conditions. The size of the K$\alpha $ spot was unchanged at any delays. There is good agreement between the experimental data and modeling using hydrodynamic and hybrid-PIC codes in the K$\alpha $ yields. Results will be presented at the meeting. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and DE-FG-02-05ER54834 (ACE).