On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. As recently reported, a burning plasma state, where the alpha-heating in the plasma is the primary source of heating, was achieved in laboratory experiments. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin ``burn propagation'' into surrounding cold fuel, enabling the possibility of high energy gain. While ``scientific breakeven'' (i.e. unity target gain) has not yet been achieved, this talk reports the first controlled fusion experiment on the National Ignition Facility to produce capsule gain greater than unity (here 5.8) and reach ignition by many different formulations of the Lawson criterion. In the talk, we will discuss some key basic physics inertial confinement fusion (ICF) principles behind the burning plasma and ignition results as well as discuss future challenges.

Complex and precise research targets are required for the inertial confinement fusion (ICF) experiments conducted at the National Ignition Facility. During the National Ignition Campaign (NIC) the target development team embarked on and completed a science and technology campaign to provide the capability to produce the required targets at the rate needed by the NIC. An engineering design for precision, manufacturing, and fielding was developed. This required new processes, new tooling, and equipment to metrologize and assemble components. In addition, development of new processing technology was also required.Since the NIC had to respond to new results from ICF experiments, the target development team had to respond as well. This required target designs that allowed for flexibility in accommodating changes in the targets for capsule dimensions and doping levels, hohlraztm dimensions and materials, and various new platforms to investigate new physics. A continuous improvement of processes was also required to meet stringent specifications and fielding requirements.

Capsules for inertial confinement fusion require precise measurement of isolated features and domes on the capsule's outer suiface. Features that are too large must be removed. A 4pi capsule mapping and characterization system has been developed to map, identify, and measure domes using a Leica confocal microscope. An ultraviolet wavelength laser was integrated to laser-ablate the offending domes that exceed the allowable mix mass. Current process methods to remove domes require three different stations in different locations. The 4pi system achieves automated capsule handling, metrology, and laser polishing/ablation of domes on one device without losing track of the capsule's orientation. The measurement technique and metrology accuracy are compared to patch atomic force microscopy scans and phase-shifting diffraction inteiferometer measurements with good correlation. The laser polishing method has demonstrated analogous results to the current process methods, but in an automated fashion. Additionally, the 4pi capsule-handling capability of the system has been used to laser-ablate purposeful engineered designs into specialty capsules.

A very large area (7.5 mm(2)) laser-driven x-ray backlighter, termed the Big Area BackLighter (BABL) has been developed for the National Ignition Facility (NIF) to support high energy density experiments. The BABL provides an alternative to Pinhole-Apertured point-projection Backlighting (PABL) for a large field of view. This bypasses the challenges for PABL in the equatorial plane of the NIF target chamber where space is limited because of the unconverted laser light that threatens the diagnostic aperture, the backlighter foil, and the pinhole substrate. A transmission experiment using 132 kJ of NIF laser energy at a maximum intensity of 8.52 × 10(14) W/cm(2) illuminating the BABL demonstrated good conversion efficiency of >3.5% into K-shell emission producing ~4.6 kJ of high energy x rays, while yielding high contrast images with a highly uniform background that agree well with 2D simulated spectra and spatial profiles.

Capsule ablators are precision hollow spheres used in inertial confinement fusion targets used in high-peak-power laser systems such as the National Ignition Facility. These capsules have high surface-quality requirements, and hence a full surface microscopic mapping system has been developed to characterize them. The capsule-fill-tube-assembly mapping system combines a confocal surface-profiling microscope with a nine-axis, high-precision stage system to provide quantitative three-dimensional data over the entire surface of each capsule prior to assembly into the final target. The system measures the individual volumes of features on the capsule surface that are 7.5 μm3 and larger with an accuracy of ±10%. The positional accuracy is better than 0.25 deg (1σ), or [approximately]5 μm linearly. The data acquisition and image processing are all highly automated in order to keep pace with throughput demands. The system consists of four primary subsystems: the positioning system, the confocal microscope, the automated acquisition code, and the image processing and data management software.