Understanding the deficiency in inertial confinement fusion hohlraum x-ray flux predictions using experiments at the National Ignition Facility
Hui Chen, D. T. Woods, W. A. Farmer, N. Aybar, D. A. Liedahl, S. A. MacLaren, M. B. Schneider, H. A. Scott, D. E. Hinkel, O. L. Landen, J. D. Moody, M. D. Rosen, J. S. Ross, S. Rogers, N. Roskopf, G. F. Swadling, S. Vonhof
Abstract
The predicted implosion performance of deuterium-tritium fuel capsules in indirect-drive inertial confinement fusion experiments relies on precise calculations of the x-ray drive in laser-heated cavities (hohlraums). This requires accurate, spectrally dependent simulations of laser to x-ray conversion efficiencies and x-ray absorption losses to the hohlraum wall. A set of National Ignition Facility experiments have identified a cause for the long-standing hohlraum "drive deficit" as the overprediction of gold emission at ∼2.5 keV in nonlocal thermodynamic equilibrium coronal plasma regions within the hohlraum. Reducing the emission and absorption opacity in this spectral region by ∼20% brings simulations into agreement with measured x-ray fluxes and spectra.