Methods of Generation and Detailed Characterization of Millimeter-Scale Plasmas Using a Gasbag Target

Abstract

Gasbag targets are useful for the research of laser-plasma interactions in inertial confinement fusion, especially in the laser overlapping regime. We report that on the Shengguang-II laser facility, millimeter-scale plasmas are successfully generated by four 0.35 μm laser beams using a gasbag target. Multiple diagnostics are applied to characterize the millimeter-scale plasmas in detail. The images from the x-ray pinhole cameras confirm that millimeter-scale plasmas are indeed created. An optical Thomson scattering system diagnoses the electron temperature of the CH filling plasmas by probing the thermal ion-acoustic fluctuations, which indicates that the electron temperature has a 600 eV flat roof in 0.7–1.3 ns. Another key parameter, i.e. the electron density of the millimeter-scale plasmas, is inferred by the spectrum of the back stimulated Raman scattering of an additional 0.53 μm laser beam. The inferred electron density keeps stable at 0.1nc in early time consistent with the controlled filling pressure and splits into a higher density in late time, which is attributed to the blast wave entering into the SRS interaction region.