Optimizing Shock Timing for Improved Compression and Reduced Adiabat in High-Yield, Burning-Plasma Experiments on the National Ignition Facility

Laser-indirect­­—drive inertial confinement fusion (ICF) experiments at the National Ignition Facility (NIF) have demonstrated a burning plasma [1] and are approaching the ignition regime with demonstrated yields exceeding a MJ [2]. In these experiments, increasing the compression is thought to be one method of obtaining higher amounts of fusion energy production. Based on the current, best-performing implosion, N210808, with a total yield of 1.3 MJ, we have performed experiments with modified pulse shapes for optimized shock timing. The goal is to reduce the adiabat and increase compression by ~10% with respect to the baseline experiment, while also maintaining moderate levels of ablation-front instability growth and fuel-ablator Atwood number. We will report on simulations and a first series of experiments studying performance metrics with the updated pulse shape design, as well as the viability of this approach for a robust, high-yield ICF platform. This work was performed under the auspices of the U.S. Department of Energy by LLNS, LLC, under Contract No. DE-AC52- 07NA27344. LLNL-ABS-836763.



[1] Zylstra et al., Nature 601, 547 (2022), Kritcher et al., Nature Physics 18, 251 (2022)

[2] “Lawson criterion for ignition exceeded in an inertial fusion experiment,” in preparation