Experiments and analysis of gold disk targets irradiated by smoothing beams of Xingguang II facilities with 350 nm wavelength

Gold disk targets were irradiated using focusing and beam smoothing methods on Xingguang (XG-II) laser facilities with 350 nm wavelength, 0.6 ns pulse width and 20–80 Joules energies. Laser absorption, light scattering and X-ray conversion were experimentally investigated. The experimental results showed that laser absorption and scattered light were about 90% and 10%, respectively, under focusing irradiation, but the laser absorption increased 5%–10% and the scattered light about 1% under the condition of beam smoothing. Compared with the case of focusing irradiation, the laser absorption was effectively improved and the scattered light remarkably dropped under uniform irradiation; then due to the decrease in laser intensity, X-ray conversion increased. This is highly advantageous to the inertial confinement fusion. However, X-ray conversion mechanism basically did not change and X-ray conversion efficiency under beam smoothing and focusing irradiation was basically the same.