Interaction of 0.53 μm laser pulse with millimeter-scale plasmas generated by gasbag target

Detailed research on the interaction of a 0.53 μm laser pulse with millimeter-scale plasmas produced by a gasbag target on the Shengguang-II facility is presented. The x-ray pinhole images confirm that millimeter-scale plasmas are generated and the x-ray framing images show a temporal window of 0.6–1.1 ns during which the millimeter-scale plasmas exist. The electron temperature is measured with a collective Thomson scattering system, providing 0.64 keV for C5H12 and 1.8 keV for Xe plasmas. The electron density is inferred from the stimulated Raman scattering spectra. The experimental spectra show large differences for C5H12- and Xe-filled gasbags. A one-dimensional code based upon steady-state, kinetic linear theory is applied to calculate the stimulated Raman scattering spectra. Excellent agreement between the calculated and experimental results shows that the plasma parameters, especially the electron density and the temperature, dominate the disruption behavior of stimulated Raman scattering. The results also indicate that stimulated Raman scattering is probably located within specific region of the gasbag. The time-integrated reflectivity of both the stimulated Raman and Brillouin scattering is at a low level, even in the conditions of high laser intensity (1.5×1015 W/cm2) and no beam-smoothing. The experimental results are promising for future ignition experiments with a 0.53 μm laser as the driver.