High-Resolution Kr Heeta Spectroscopy Maps NIF Hot Spot Density and Temperature Evolution

The experiment fielded HDC and W-doped HDC ablators with trace Kr dopant. Time-gated spectrometers recorded the evolving Heeta complex while a simultaneous time-integrated measurement provided absolute calibration. A collisional-radiative model matched the observed line shapes and satellite intensities, yielding plasma conditions at multiple bang-time slices. The W dopant reduced hot-spot mix and raised peak density by approximately 15 percent relative to pure HDC shots. These data directly constrain the hydrodynamic scaling that links capsule performance to ignition thresholds. Because the measurements are obtained on the same shots that achieve high yield, they close a critical loop between ablator design and stagnation conditions that integrated neutron diagnostics alone cannot resolve. The work remains a preprint and reports only seven shots; statistical power is therefore modest. A dedicated campaign of 30–50 shots with varied dopant levels and convergence ratios would strengthen the inference of systematic trends and allow direct comparison against radiation-hydrodynamics simulations.