Experimental study of low-conductivity metallic coatings to mitigate instabilities in liner implosions on the Z Machine*

In MagLIF, instabilities on the exterior of a liner can grow to large amplitudes and feed through to the interior fusion fuel, reducing compression and confinement. We present results from the first experiments on the Z Machine using thin coatings of low electrical conductivity, electroless-nickel on the outer surface of beryllium liners to mitigate growth of the electrothermal instability and the subsequent magneto-Rayleigh Taylor instability. Shadowgraphy images show that the coatings reduce instability growth at observable densities <10²²/cc. Two-color radiography provides information on instability growth at higher densities. Compared to previously demonstrated dielectric coatings, these metallic coatings are more straightforward to model in MHD simulations of MagLIF and could therefore significantly enhance predictive capabilities for scaling targets to higher yields on future pulsed power facilities.