Investigation of the performance of mid-Z Hohlraum wall liners for producing x-ray drive

Abstract

M-band transitions (n = 4 → 3) in Gold are responsible for a population of X-rays with energy > 1.8 keV in indirect drive inertial fusion. These X-rays can preheat the fuel, cause the ablatorfuel interface to become unstable to Rayleigh-Taylor instabilities, and introduce radiation nonuniformity to the X-ray drive. This work investigates the performance of mid-Z lined hohlraums for producing an efficient drive spectrum absent of M-band X-rays using the two-dimensional lagrangian radiation hydrodynamics code h2d. The removal of the M-band transitions is observed in the Culined hohlraum reducing the total X-ray energy above 1.8 keV to 58% that of the un-lined hohlraum. Total radiation energy in the Cu-lined hohlraum is 93% that of the energy in the pure Au hohlraum for a 1 ns pulse. However, the soft X-ray drive energy (below 1.8 keV) for the lined hohlraum is 98% that of the pure Au hohlraum.