Recent Advances in Hohlraum Physics: Resolving the Drive Deficit and Enhancing Predictive Capability

Significant progress has been achieved in understanding and modeling hohlraum physics, leading to the resolution of the longstanding "drive deficit" issue in indirect-drive inertial confinement fusion experiments. Through targeted experimental campaigns and advances in radiation-hydrodynamics modeling, we have developed a more predictive hohlraum model that accurately captures laser energy coupling and x-ray drive generation. This improved understanding enables precise prediction of capsule bang time to within 100 ps, representing a substantial step forward in predictive capability and experimental design. Despite these advances, challenges remain in accurately predicting the implosion shape, with current simulations failing to capture the implosion symmetry observed in experiments. Multiple coordinated campaigns are underway at the National Ignition Facility to test hypotheses related to cross-beam energy transfer and laser-plasma interactions as a potential source of this discrepancy. This presentation will summarize recent experimental data, validation against model improvements, and ongoing efforts to resolve remaining uncertainties in implosion shape prediction.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.