Investigations on the hohlraum radiation in the first shaped laser pulse implosion experiment at the SGIII laser facility

Abstract

The first 0.1 MJ scale shaped pulse implosion experiment was performed at the Shenguang-III laser facility in 2016. The hohlraum radiation of three representative shots with troughs of 1.0 ns, 1.5 ns, and 2.5 ns is analysed using the two-dimensional code LARED with the multi-group radiation transfer model. It is found that the simulated multi-angle radiation temperatures are generally in good agreement with the measurements within ∼3%. However, our simulations underestimate the peak radiation temperature at 64° by ∼6% for the shot with the 2.5 ns trough, due to the much smaller laser entrance hole in our calculations. In addition, we simulate the time-integrated M-band (2–4 keV) x-ray image at the view angle of 20° for the shot with the 1.0 ns trough. The simulated laser spot positions are consistent with the measurement. But the relative brightness between the inner beams and the outer beams is larger than the experimental result, which may be caused by the overestimation of the plasma density at the edge of the bubbles in our simulation. With the bubble contribution approximately removed, the simulated relative brightness between the inner beams and the outer beams approaches the experimental result.