On December 5th, 2022, controlled fusion ignition was demonstrated for the first time at the National Ignition Facility (NIF), a major achievement in the field of Inertial Confinement Fusion (ICF) requiring a multi-decadal effort involving broad national and international collaborations. To drive the fusion ignition reaction with the compressed fuel capsule, that yielded 3.15 MJ of nuclear energy [1], the NIF laser delivered a high-precision pulse shape with 2.05 MJ of ultra-violet (UV) laser energy and a peak power of 440 TW. This laser energy was an increase of similar to 8 % compared to that delivered on the previous "threshold of ignition" record yield experiment (1.37 MJ of yield for 1.89 MJ of laser energy) on August 8th, 2021 [2]. We explain how the results of our extensive research in laser technology and UV optics damage mitigation led to major improvements in the NIF laser, enabling this energy increase along with additional accuracy, precision, and power balance enhancements. Furthermore, we will discuss on-going efforts that have enabled operations at 2.2 MJ of UV energy as well as potential new initiatives to push the laser performance -accuracy and delivered energy- to even higher levels in the future as previously demonstrated on a small subset of NIF beams [3].

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.

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory contains a192-beam 4.2 MJ neodymium glass laser (around 1053 nm or 1w) that is frequency converted to351nm light or 3w. It has been designed to support the study of Inertial Confinement Fusion (ICF)and High Energy Density Physics (HEDP). The NIF Precision Diagnostic System (PDS) was reactivated and newdiagnostic packages were designed and fielded that offer a more comprehensive suiteof high-resolution measurements. The current NIF laser performance will be presented as well as the preliminary results obtained with the various laser experimental campaigns using the new diagnostic tool suites.

There are 830 transport mirrors with a combined surface area of approximately 255 m2 of precision multilayer coatings deposited on 50 metric tons of BK7 glass in the high fluence transport section of the National Ignition Facility (NIF). With peak fluences over 20 J/cm2 at 1053 nm, less than five percent of these mirrors are exchanged annually due to laser damage since full system operations began in 2009. Multiple technologies have been implemented to achieve these low exchange rates. The coatings are complex dichroics designed to reflect the fundamental wavelength (1053 nm) and an alignment beam (374 nm) while suppressing target backscatter wavelengths (351 nm and 400-700 nm) from backward propagation up the beamlines. Each optic is off-line laser conditioned to nominally 50% over the average fluence and nominally 90% of the peak fluence allowing the final laser conditioning to occur on-line during NIF operations. Although the transport section of NIF is sealed in a clean argon environment, air knives were installed on upward facing transport mirrors to blow off particulates that could accumulate and initiate laser damage. Beam dumps were installed in between the final optics assembly and the final transport mirrors to capture ghost reflections from the anti-reflection coated surfaces on the transmissive optics used for polarization rotation, frequency conversion, and focusing the 192 laser beams on target. Spot blockers, normally used for the final optics, are sometimes used to project a shadow over transport mirror laser damage in an effort to arrest laser damage growth and extend transport mirror lifetime. Post analysis of laser-damaged mirrors indicates that the dominant causes of laser damage are from surface particulates and the 351-nm wavelength target backscatter.

The primary sources of damage on the National Ignition Facility (NIF) Grating Debris Shield (GDS) are attributed to two independent types of laser-induced particulates. The first comes from the eruptions of bulk damage in a disposable debris shield downstream of the GDS. The second particle source comes from stray light focusing on absorbing glass armor at higher than expected fluences. We show that the composition of the particles is secondary to the energetics of their delivery, such that particles from either source are essentially benign if they arrive at the GDS with low temperatures and velocities.

Lawrence Livermore National Laboratory Campus Capability Plan for 2018-2028. Lawrence Livermore National Laboratory (LLNL) is one of three national laboratories that are part of the National Nuclear Security Administration. LLNL provides critical expertise to strengthen U.S. security through development and application of world-class science and technology that: Ensures the safety, reliability, and performance of the U.S. nuclear weapons stockpile; Promotes international nuclear safety and nonproliferation; Reduces global danger from weapons of mass destruction; Supports U.S. leadership in science and technology. Essential to the execution and continued advancement of these mission areas are responsive infrastructure capabilities. This report showcases each LLNL capability area and describes the mission, science, and technology efforts enabled by LLNL infrastructure, as well as future infrastructure plans.

High energy laser systems are ultimately limited by laser-induced damage to their critical components. This is especially true of damage to critical fused silica optics, which grows rapidly upon exposure to additional laser pulses. Much progress has been made in eliminating damage precursors in as-processed fused silica optics (the advanced mitigation process, AMP3), and very high damage resistance has been demonstrated in laboratory studies. However, the full potential of these improvements has not yet been realized in actual laser systems. In this work, we explore the importance of additional damage sources-in particular, particle contamination-for fused silica optics fielded in a high-performance laser environment, the National Ignition Facility (NIF) laser system. We demonstrate that the most dangerous sources of particle contamination in a system-level environment are laser-driven particle sources. In the specific case of the NIF laser, we have identified the two important particle sources which account for nearly all the damage observed on AMP3 optics during full laser operation and present mitigations for these particle sources. Finally, with the elimination of these laser-driven particle sources, we demonstrate essentially damage free operation of AMP3 fused silica for ten large optics (a total of 12,000 cm2 of beam area) for shots from 8.6 J/cm2 to 9.5 J/cm2 of 351 nm light (3 ns Gaussian pulse shapes). Potentially many other pulsed high energy laser systems have similar particle sources, and given the insight provided by this study, their identification and elimination should be possible. The mitigations demonstrated here are currently being employed for all large UV silica optics on the National Ignition Facility.

The possibility of imploding small capsules to produce mini-fusion explosions was explored soon after the first thermonuclear explosions in the early 1950s. Various technologies have been pursued to achieve the focused power and energy required for laboratory-scale fusion. Each technology has its own challenges. For example, electron and ion beams can deliver the large amounts of energy but must contend with Coulomb repulsion forces that make focusing these beams a daunting challenge. The demonstration of the first laser in 1960 provided a new option. Energy from laser beams can be focused and deposited within a small volume; the challenge became whether a practical laser system can be constructed that delivers the power and energy required while meeting all other demands for achieving a high-density, symmetric implosion. The National Ignition Facility (NIF) is the laser designed and built to meet the challenges for study of high-energy-density physics and inertial confinement fusion (ICF) implosions. This paper describes the architecture, systems, and subsystems of NIF. It describes how they partner with each other to meet these new, complex demands and describes how laser science and technology were woven together to bring NIF into reality.

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

We have achieved the NIF design goals for power and energy by delivering 1.86 MJ of ultra-violet energy in a wide dynamic range (> 300: 1), 22.5-ns shaped ignition pulse with a peak power of 520 TW.

Received 28 February 2011DOI:https://doi.org/10.1103/PhysRevLett.106.109903© 2011 American Physical Society

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

When the stadium-size National Ignition Facility (NIF) is fully operational at the Lawrence Livermore National Laboratory (LLNL), its 192 laser beams will deliver 1.8 megajoules (500 terawatts) of energy onto a target to create extremely high temperatures and pressures for inertial confinement fusion research as part of the Stockpile Stewardship Program. Due to the performance threshold and requirements of the NIF optical components, the optics and their surrounding beampath as well as the supporting utility systems must be fabricated, cleaned, assembled, and commissioned for precision cleanliness. This paper will provide an overview of the NIF cleanliness requirements, the Clean Construction Protocol (CCP) specifications for the beampath and clean utilities, and techniques for verifying the CCP specifications.The NIF cleanliness requirements define limits for molecular and particulate contamination. The goal of these limits is to prevent contamination of optical components. To prevent laser-induced damage and poor laser quality in the optical components, requirements for cleaning, assembly, installation, and commissioning in terms of particle and nonvolatile residue (NVR) levels are defined. The airborne cleanliness requirements in the interior of the beampath are Class 1 (ISO Class 3) particulate levels and a few parts-per-billion (ppb) airborne molecular contamination (AMC) (SEMI F21-95 MC-1,000).To achieve the cleanliness requirements for the beampath interior, a graded CCP approach is used as the NIF beampath and utilities are being constructed by a partnership between LLNL and the construction contractor, Jacobs Facilities Inc. (JFI) in a stadium-size Class 100,000 (ISO Class 8) building. Installation of the beampath components utilizes localized mini-environments of Class 100 (ISO Class 5) or better, with budgets of cleanliness exposure or "class-hours" for each clean connection. Garment, equipment, and operational considerations are evaluated with process verification.Verification of the beampath and utility cleanliness is performed with cleanliness exposure monitoring, evaluating particulates with "swipes" and the LLNL-developed Precision Cleanliness Verification System (PCVS), and measuring nonvolatile residues (NVRs) and AMCs with analytical chemistry techniques. Cleanliness verification results demonstrate that the CCP specifications are achieving the NIF cleanliness requirements for the beampath and clean utilities.