Design of first experiment to achieve fusion target gain > 1

Abstract

A decades-long quest to achieve fusion energy target gain and ignition in a controlled laboratory experiment, dating back to 1962, has been realized at the National Ignition Facility (NIF) on December 5, 2022 [Abu-Shawareb et al., Phys. Rev. Lett. 132, 065102 (2024)] where an imploded pellet of deuterium and tritium (DT) fuel generated more fusion energy (3.15 MJ) than laser energy incident on the target (2.05 MJ). In these experiments, laser beams incident on the inside of a cylindrical can (Hohlraum) generate an intense ∼3 × 106 million degree x-ray radiation bath that is used to spherically implode ∼2 mm diameter pellets containing frozen deuterium and tritium. The maximum fusion energy produced in this configuration to date is 3.88 MJ using 2.05 MJ of incident laser energy and 5.2 MJ using 2.2 MJ of incident laser energy, producing a new record target gain of ∼2.4×. This paper describes the physics (target and laser) design of this platform and follow-on experiments that show increased performance. We show robust megajoule fusion energy output using this design as well as explore design modification using radiation hydrodynamic simulations benchmarked against experimental data, which can further improve the performance of this platform.