Quantified reduction of wall material influx during Hohlraum experiments

Abstract

Heating the gold walls of a Hohlraum with intense laser beams produces a rapidly expanding gold plasma. Eventually, the wall material will converge on the axis of the Hohlraum with a density sufficient to be opaque to any standard radiography source. The gold expansion makes radiography of the back wall through the laser entrance hole of a Hohlraum driven from one side difficult. This experiment demonstrates a reduction of Au influx when the Hohlraum walls are coated with 0.44 μm of parylene-N. The reduction is quantified, using an x-ray framing camera, in a cylindrical Hohlraum driven by 6.8 kJ of laser light.