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.

Indirect drive experiments have now been carried out with laser powers and energies up to 520 TW and 1.9 MJ. These experiments show that the energy coupling to the target is nearly constant at 84% ± 3% over a wide range of laser parameters from 350 to 520 TW and 1.2 to 1.9 MJ. Experiments at 520 TW with depleted uranium hohlraums achieve radiation temperatures of ∼330 ± 4 eV, enough to drive capsules 20 μm thicker than the ignition point design to velocities near the ignition goal of 370 km/s. A series of three symcap implosion experiments with nearly identical target, laser, and diagnostics configurations show the symmetry and drive are reproducible at the level of ±8.5% absolute and ±2% relative, respectively.

he National Ignition Facility (NIF) is the world's most energetic laser, having demonstrated in excess of 1.9MJ @351nm with Inertial Confinement Fusion pulse-shapes in July, 2012. First commissioned with 192 operational beamlines in March, 2009, NIF has since transitioned to routine operation for stockpile stewardship, inertial confinement fusion research, and basic high energy density science.The NIF design includes component placement and beam alignment tolerances to preclude laser beam clipping on components within the laser chain, indeed lengthy studies and analyses, including various statistical approaches, were done in the design phase as early as 1996. The margin between the available optical aperture and the beam was established to ensure, given beam centering variations and component placement errors, that we would achieve a confidence level such that even low-level clipping, which causes downstream modulation damage, would occur at an acceptably or even vanishingly low rate.With the completion of NIF and nearly 4 years of operational experience, it became apparent that we could increase the beam size to more optimally fill the available aperture, and gain an additional 5% to 10% or more energy and power delivered to targets. It was also shown that additional energy could be recovered by removing approximately 70% of our beam 'corner blockers' originally installed in May 2010 to prevent target-chamber 1 mu m counterpropagating light from leaking back through the extinction minimums at the corners of vacuum-loaded square optics. Subsequent analyses showed that only one and in some cases two of the corner blockers were really needed. Increasing the beam size was a challenging endeavor, however, as it fundamentally meant recommissioning the entire NIF laser chain to tailor all 192 beams to their specific available aperture, individual beam rotation (for the NIF square beam), beam centering offsets, change-out of the 48 front-end aperture (relay-plane "0"), and removal of 48 Laser Mirror #2 line replaceable units for corner-blocker removal. Some of this commissioning, such as tailoring beam sizes to their specific available aperture, had not been performed during the original commissioning. Furthermore, achieving this required precise diagnostics and rapid analysis of massive quantities of images and data in order to direct the changes and feed-back the achieved results. Completed on June 1, 2012, the beam area was increased by 7.5%, and was a significant contributing factor in NIF transitioning from a 1.6MJ laser to its present 1.9MJ capability

The laser system has predicted performance of 8100-J at 16-Hz with 18% wallplug efficiency. This laser also has broad industrial applications including materials processing, and Chirped-Pulse-Amplification pump/amplifier sources which in turn can produce secondary radiation sources.

This paper presents our conceptual design for laser drivers used in Laser Inertial Fusion Energy (LIFE) power plants. Although we have used only modest extensions of existing laser technology to ensure near-term feasibility, predicted performance meets or exceeds plant requirements: 2.2 MJ pulse energy produced by 384 beamlines at 16 Hz, with 18% wall-plug efficiency. High reliability and maintainability are achieved by mounting components in compact line-replaceable units that can be removed and replaced rapidly while other beamlines continue to operate, at up to similar to 13% above normal energy, to compensate for neighboring beamlines that have failed. Statistical modeling predicts that laser-system availability can be greater than 99% provided that components meet reasonable mean-time-between-failure specifications.

In preparation for the upcoming experiments on the Titan laser at the Jupiter Laser Facility, a new Thomson scattering system has been designed and implemented. This system allows electron temperature and density measurements in a high-density regime (n(e)>10(21) cm(-3)). A 263 nm probe has been demonstrated to produce a total energy of 15 J at 4ω(263 nm) in a 1 ns square pulse with a focal spot size of 100 μm. This probe has been used for imaging Thomson scattering of the ion feature. The goal of this study is to investigate the heating of a preformed plasma by a short-pulse heater beam.

We are converting a quad of NIF beamlines into eight, short-pulse (1–50 ps), petawatt-class beams for advanced radiography and fast ignition experiments. This paper describes progress toward completing this project.

The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer of laser energy to the compressed fuel via multi-MeV electrons. Preformed plasma due to the laser prepulse strongly influences ultraintense laser plasma interactions and hot electron generation in the hollow cone of an FI target. We induced a prepulse and consequent preplasma in copper cone targets and measured the energy deposition zone of the main pulse by imaging the emitted K_{alpha} radiation. Simulation of the radiation hydrodynamics of the preplasma and particle in cell modeling of the main pulse interaction agree well with the measured deposition zones and provide an insight into the energy deposition mechanism and electron distribution. It was demonstrated that a under these conditions a 100 mJ prepulse eliminates the forward going component of approximately 2-4 MeV electrons.

The National Ignition Facility (NIF) laser has been designed to support high energy density science (HEDS), including the demonstration of fusion ignition through Inertial Confinement. NIF operated a single "quad" of 4 beams from December 2002 through October 2004 in order to gain laser operations experience, support target experiments, and demonstrate laser performance consistent with NIF's design requirement. During this two-year period, over 400 Main Laser shots were delivered at 1 omega to calorimeters for diagnostic calibration purposes, at 3 omega to the Target Chamber, and at 1 omega, 2 omega, and 3 omega to the Precision Diagnostics System (PDS). The PDS includes its own independent single beam transport system, NIF design frequency conversion hardware and optics, and laser sampling optics that deliver light to a broad range of laser diagnostics. Highlights of NIF laser performance will be discussed including the results of high energy 2 omega and 3 omega experiments, the use of multiple focal spot beam conditioning techniques, the reproducibility of laser performance on multiple shots, the generation on a single beam of a 3 omega temporally shaped ignition pulse at full energy and power, and recent results on full bundle (8 beamline) performance. NIF's first quad laser performance meets or exceeds NIF's design requirements.

The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3omega) with a total intensity of 2 x 10(15) W cm(-2). The targets were filled with 1 atm Of CO2 producing up to 7 mm long homogeneously heated plasmas with densities of n(e) = 6 x 10(20) cm(-3) and temperatures of T-e = 2 keV. The high energy in an NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser-plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x-rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last similar to1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 3% for the smallest length (similar to2 mm), increasing to 10-12% for similar to7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modelling of the laser-plasma interactions at ignition-size scale lengths.

We describe the Optical Pulse Generation (OPG) testbed, which is the integration of the MOD and Preamplifier Development Laboratories. We use this OPG testbed to develop and demonstrates the overall capabilities of the NIF laser system front end. We will present the measured energy and power output, temporal and spatial pulse shaping capability, FM bandwidth and dispersion for beam smoothing, and measurements of the pulse-to-pulse power variation o the OPG system and compare these results with the required system performance specifications. We will discus the models that are used to predict the system performance and how the OPG output requirements flowdown to the subordinate subsystems within the OPG system.

A wavefront control system will be employed on NIF to correct beam aberrations that otherwise would limit the minimum target focal spot size. For most applications, NIF requires a focal spot that is a few times the diffraction limit. Sources of aberrations that must be corrected include prompt pump-induced distortions in the laser slabs, thermal distortions in the laser slabs from previous shots, manufacturing figure errors in the optics, beam off-axis effects, gas density variations, and gravity, mounting, and coating-induced optic distortions.

Summary form only given. The preamplifier module or PAM is a high gain, Nd:glass laser system that amplifies the temporally and frequency formatted pulse produced in the master oscillator room (MOR), up to a level that is sufficient for seeding the main amplifier chains of the NIF laser system. The PAM consists of two separate laser amplifiers, a diode-pumped, regenerative amplifier, and a 5 cm., flashlamp-pumped-rod, four-pass amplifier. The amplifiers boost the 1 nJ input pulse from the MOR up to 10-20 Joules in a pulse that ranges from 0.2 to 20 ns. In addition to amplification, the PAM spatially shapes the beam to precompensate for the spatial gain profiles of the main amplifiers, and angularly disperses the beam as part of the smoothing by spectral dispersion (SSD) feature of the laser system. In the past we have demonstrated the performance specifications of the preamplifier on a tabletop, development system. We assembled the first engineering prototype PAM and are conducting final measurements on a system that will become the first of 48 PAMs in the NIF laser system. We made improvements to various subsystems in the PAM that are now included in the engineering prototype. We now operate the regenerative amplifier in energy saturation to reduce the pulse-to-pulse variation in the PAM. We improved the efficiency of the spatial beam shaping masks by including the effects of diffraction from the chrome pixels in designing the masks. We eliminated temporal pulse overlap in the four-pass amplifier by lengthening the relay telescopes in the four-pass optical layout. In the presentation we discuss the latest results from performance measurements of PAM engineering prototype.

The National Ignition Facility (NIF) laser will use a 192- beam multi-pass architecture capable of delivering several MJ of UV energy in temporal phase formats varying from sub- ns square to 20 ns precisely-defined high-contrast shapes. Each beam wavefront will be subjected to effects of optics inhomogeneities, figuring errors, mounting distortions, prompt and slow thermal effects from flashlamps, driven and passive air-path turbulence, and gravity-driven deformations. A 39-actuator intra-cavity deformable mirror, controlled by data from a 77-lenslet Hartman sensor will be used to correct these wavefront aberrations and thus to assure that stringent farfield spot requirements are met. We have developed numerical models for the expected distortions, the operation of the adaptive optics systems, and the anticipated effects on beam propagation, component damage, frequency conversion, and target-plane energy distribution. These models have been extensively validated against data from LLNL's Beamlet, and Amplab lasers. We review the expected beam wavefront aberrations and their potential for adverse effects on the laser performance, describe our model of the corrective system operation, and display our predictions for corrected-beam operation of the NIF laser.

Summary form only given. The optical pulse generation system (OPG) produces the initial pulse that is shaped, spatially and temporally, frequency modulated, amplified to 22 X and injected into the 192 main amplifier chains of the National Ignition Facility (NIF) laser system.