Experimental demonstration of unity gain at 1.9 MJ of laser drive on the National Ignition Facility through optimized shock timing*

Laser-indirect­­—drive inertial confinement fusion (ICF) experiments at the National Ignition Facility (NIF) have demonstrated ignition and integrated yields in excess of three MJ [1]. Following this achievement, there is a significant effort underway to further improve the current, best performing design with respect to ignition margin, robustness and performance. Particularly, increasing the compression of the fuel is thought to be one method of obtaining higher amounts of fusion energy production, e.g., by lowering the fuel adiabat using a modified shock-timing with small changes to the drive-laser pulse shape. We will be reporting on a series of experiments testing an updated pulse shape, which demonstrated increased compression by ~15% and increased yield of ~40% with respect to the baseline performance [2], as well as being the first platform to achieve, within experimental uncertainties, a gain of unity with a laser drive of 1.9 MJ. We will further discuss simulation results, the impact of the updated pulse shape on implosion metrics, and the viability of this design choice for a robust, high-yield ICF platform. LLNL-ABS-851371

 

[1] to be submitted to Phys. Rev. Letters

[2] H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Letters 129, 075001 (2022); A. L. Kritcher et al., Phys. Rev. E 106, 025201 (2022); A. B. Zylstra et al., Phys. Rev. E 106, 025202 (2022).