First radiative shock experiments on the SG-II laser

TL;DR

This paper presents the first experimental observations of radiative shocks driven by the SG-II laser, using large gas-cell targets and advanced imaging techniques to analyze shock formation, propagation, and collision dynamics.

Contribution

It introduces the first radiative shock experiments on the SG-II laser, demonstrating shock imaging and collision analysis with novel gas-cell targets and diagnostics.

Findings

Shock velocities around 40 km/s observed

Shocks propagated up to 100 ns without wall interference

Collision and stagnation of counter-propagating shocks demonstrated

Abstract

We report on the design and first results from experiments looking at the formation of radiative shocks on the Shenguang-II (SG-II) laser at the Shanghai Institute of Optics and Fine Mechanics in China. Laser-heating of a two-layer CH/CH-Br foil drives a $\sim$40 km/s shock inside a gas-cell filled with argon at an initial pressure of 1 bar. The use of gas-cell targets with large (several mm) lateral and axial extent allows the shock to propagate freely without any wall interactions, and permits a large field of view to image single and colliding counter-propagating shocks with time resolved, point-projection X-ray backlighting ($\sim20$ $\mu$m source size, 4.3 keV photon energy). Single shocks were imaged up to 100 ns after the onset of the laser drive allowing to probe the growth of spatial non-uniformities in the shock apex. These results are compared with experiments looking at counter-propagating shocks, showing a symmetric drive which leads to a collision and stagnation from $\sim$40 ns onward. We present a preliminary comparison with numerical simulations with the radiation hydrodynamics code ARWEN, which provides expected plasma parameters for the design of future experiments in this facility.