Peter Amendt | 17-ERD-119
Increasing the absorbed x-ray energy by capsule targets during inertial confinement fusion (ICF) experiments translates into a greater amount of shell kinetic energy at the instant of peak implosion speed and better prospects for igniting the thermonuclear fuel. Thus, our project aimed to increase the absorbed capsule energy by 2 to 3 times by pursuing advanced hohlraum concepts aimed at offering enhanced capabilities when compared with cylinder-shaped hohlraums. The advanced hohlraums we developed offered changes in shape to accommodate larger capsules without sacrificing symmetry control and peak shell implosion speed. The two hohlraum shapes we studied were the Frustraum and rugby. The central hot-spot ignition mode was the main focus of the Frustraum hohlraum, while the high-volume and -adiabat capsule (HVAC) ignition concept leveraged the rugby-shaped hohlraum. Both hohlraum types were exhaustively studied with numerical simulations for sensitivity, optimization, and use during experiments.
Our research culminated in three important advances: (1) developing the Frustraum hohlraum concept for accessing nearly 3-times-larger capsule-absorbed energy compared with cylinder-based designs for hot-spot ignition; (2) formulating the HVAC approach to ignition using rugby-shaped hohlraums; and (3) scoping out the facility limits of a gas-filled high-density-carbon ablator ignition design using a rugby hohlraum. Both the Frustraum and HVAC designs have now been adopted by the Lawrence Livermore National Laboratory's ICF program and are undergoing active testing at Livermore's National Ignition Facility (NIF).
This proposal is well-aligned with the Laboratory's nuclear weapons science mission research challenge, as well as the Laboratory's core competencies in high-energy-density (HED) science and advanced materials and manufacturing. In addition, the research supports NNSA missions in science-based stockpile stewardship and energy security through an enhanced understanding of HED physics and improved prospects for demonstrating thermonuclear ignition on NIF.
Publications, Presentations, and Patents
Amendt, P., et al. 2018. "Design Studies of Ultra-High Hohlraum-Capsule Coupling Efficiency Experiments for the NIF." EPS, Prague, Czech Republic, July 2018. LLNL-PRES-754878
——— 2019. "Ultra-high (>30%) coupling efficiency designs for demonstrating central hot-spot ignition on the National Ignition Facility using a Frustraum." Physics of Plasmas 26, 082707. doi:10.1063/1.5099934. LLNL-JRNL-769219
——— 2020. "High-Volume and -Adiabat Capsule ("HVAC") Ignition: Lowered Fuel Compression Requirements Using Advanced Hohlraums." Phys. Plasmas 27, 122708. doi:10.1063/5.0032380. LLNL-JRNL-815298