Figure 2: Comparison of experimental and simulated results.

A secondary target was used as an X-ray source for backlit pinhole radiography of the reverse shock region (see Fig. 1 and Methods). The plasma flow enters from the right of the figure and impacts onto the obstacle, originally at 3,000 μm, forming a reverse shock that can be seen around 2,750 μm. The top half of (a) shows the experimental radiograph, with the bottom half of (a) showing a synthetic radiograph from postprocessing a 2D simulation. The target tube had a slit cut into it from ∼2,200 to ∼3,100 μm. The same radiative hydrodynamic simulation was postprocessed to give simulated radiographs with and without the effect of the tube opacity, to account for the effect of the tube being absent at the slit position. A line-out of X-ray transmission along the central axis, for the experimental case and postprocessing of the simulated case with and without the opacity of the tube wall, is plotted in (b). The transmission is well matched for the experimental case and simulated radiograph without tube opacity from the position of the reverse shock, ∼2,750 μm, to the edge of the slit, ∼2,200 μm. After this point, the experiment transmission agrees better with the simulated radiograph including the tube opacity.