Nuclear and x-ray burn widths in recent high-yield implosions on the National Ignition Facility*

Cryogenic implosions on the National Ignition Facility (NIF) are primarily used to produce high neutron yields in the effort to achieve the goal of ignition. Two campaigns using high-density carbon ablator designs are leading this effort using low- and high-adiabat implosions that have achieved yields of more than 50 kJ, the highest to date on NIF. The time-history of the DT neutrons and x-rays emitted during the implosion with ~10-20 ps temporal resolution in the form of MeV photons (gammas) released from fusion events and 10s of keV x-ray photons from the hot dense core. These burn durations are typically longer than predicted by simulations and could be a signature of degradation mechanisms like preheat, fuel-ablator mix, or 3D effects. We also observe a second x-ray peak post-stagnation at lower photon energies, which we attribute to the outgoing shock propagating through the ablator. We discuss how this signature can provide insight into the conditions of the shell at late time.