Observation of Instability Growth in a Copper $Z$ -Pinch Target Using Two-Color Monochromatic X-Ray Backlighting

Existing monochromatic X-ray backlighting diagnostics at 1.865 and 6.151 keV have been combined to create a two-color monochromatic X-ray backlighting diagnostic. The use of different photon energies can allow a much broader range of areal densities to be observed in a single experiment. Here, we apply the two-color backlighter to the study of instability growth on the outside edge of an initially solid copper rod target driven by a 100-ns rise-time current pulse with a peak value of 20 MA. The different opacity of Cu at these two photon energies allows a dynamic range of ~ 1600x to be surveyed instead of ~ 60x (assuming a useful transmission range of 5%-95%).