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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Near Field Intensity Trends of Main Laser Alignment Images in the National Ignition Facility (NIF)

The National Ignition Facility (NIF) utilizes 192 high-energy laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to potentially initiate a fusion reaction. NIF has been operational for six years; during that time, thousands of successful laser firings or shots have been executed. Critical instrument measurements and camera images are carefully recorded for each shot. The result is a massive and complex database or ‘big data’ archive that can be used to investigate the state of the laser system at any point in its history or to locate and track trends in the laser operation over time. In this study, the optical light throughput for more than 1600 NIF shots for each of the 192 main laser beams and 48 quads was measured over a three year period from January 2009 to October 2012. The purpose was to verify that the variation in the transmission of light through the optics over time performed within design expectations during this time period. Differences between average or integrated intensity from images recorded by the input sensor package (ISP) and by the output sensor package (OSP) in the NIF beam-line were examined. A metric is described for quantifying changes in the integrated intensity measurements and was used to view potential trends. Results are presented for the NIF input and output sensor package trends and changes over the three year time-frame.

42 ENGINEERING↗
DOE OSTI2017

Simulation of the Prompt Dose Environment in the NIF during High Yield Shots

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is the world's largest and most energetic laser system for inertial confinement fusion. NIF is a 192-laser beam facility, capable of producing 1.8 MJ, 500 TW of ultraviolet light. The main laser systems are installed in two laser bays. Each laser bay delivers 96 beams into one of two switchyards. Sets of turning mirrors in each Switchyard (SY) redirect the beams into the Target Bay (TB). Additional sets of optics in the TB will align and focus the beams onto the target in the center of the Target Chamber (TC). The 192 beams enter the TC through 48 indirect-drive beam ports. Laser beams are then focused to enter a small metal can (hohlraum) held at the center of the TC creating thermal x-rays that heat the surface of the fusion capsule contained within. The Target Bay has a cylindrical design with an inner radius of 15.24 m, 1.83-m-thick concrete walls and 1.37-m-thick concrete roof. A total of 239 and 121 penetrations are present in the Target Bay and switchyard walls, respectively. Figure 1 shows the facility's layout. There are seven floor levels within the TB at elevations of -33'9'', -21'9'', -3'6'', 17'6'', 29'6'', 40'0'', and 50'6'' with respect to the ground level. The TC is positioned in the middle of the TB with its center at elevation of 23'0'' from the ground level. The NIF will routinely utilize deuterium-tritium (D-T) targets with up to 20 MJ yield per shot, and maximum annual yield of 1200 MJ. This summary focuses on analyzing the expected prompt dose environment during the NIF's high yield phase of operations. Previous publications evaluated the expected doses associated with lower yield phases of operation. During shots, the Target Bay, Switchyards, and Laser Bays are interlocked and unoccupied. On the other hand, Personnel can be present inside the Operations Support Building (OSB), the control room, and the visitor center during the shots. The radiation shielding has been optimized to meet the NIF radiological design goals and the Department of Energy (DOE) limits. The goal is to limit the maximum prompt dose in any potentially occupied area to less than 50 {mu}Sv per shot as well as limiting the annual dose to individuals in the occupied areas to less than 1 mSv.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2012

Inertial Confinement Fusion and the National Ignition Facility (NIF)

Inertial confinement fusion (ICF) seeks to provide sustainable fusion energy by compressing frozen deuterium and tritium fuel to extremely high densities. The advantages of fusion vs. fission are discussed, including total energy per reaction and energy per nucleon. The Lawson Criterion, defining the requirements for ignition, is derived and explained. Different confinement methods and their implications are discussed. The feasibility of creating a power plant using ICF is analyzed using realistic and feasible numbers. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is shown as a significant step forward toward making a fusion power plant based on ICF. NIF is the world’s largest laser, delivering 1.8 MJ of energy, with a peak power greater than 500 TW. NIF is actively striving toward the goal of fusion energy. Other uses for NIF are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Design and modeling of indirectly driven magnetized implosions on the NIF

The use of magnetic fields to improve the performance of hohlraum-driven implosions on the National Ignition Facility (NIF) is discussed. The focus is on magnetically insulated inertial confinement fusion, where the primary field effect is to reduce electron-thermal and alpha-particle loss from the compressed hotspot (magnetic pressure is of secondary importance). We summarize the requirements to achieve this state. The design of recent NIF magnetized hohlraum experiments is presented. These are close to earlier shots in the three-shock, high-adiabat (BigFoot) campaign, subject to the constraints that magnetized NIF targets must be fielded at room-temperature, and use ≲1 MJ of laser energy to avoid the risk of optics damage from stimulated Brillouin scattering. We present results from the original magnetized hohlraum platform, as well as a later variant that gives a higher hotspot temperature. In both platforms, imposed fields (at the capsule center) of up to 28 T increase the fusion yield and hotspot temperature. Integrated radiation-magneto-hydrodynamic modeling with the Lasnex code of these shots is shown, where laser power multipliers and a saturation clamp on cross-beam energy transfer are developed to match the time of peak capsule emission and the P2 Legendre moment of the hotspot x-ray image. The resulting fusion yield and ion temperature agree decently with the measured relative effects of the field, although the absolute simulated yields are higher than the data by 2.0−2.7×. The tuned parameters and yield discrepancy are comparable for experiments with and without an imposed field, indicating the model adequately captures the field effects. Self-generated and imposed fields are added sequentially to simulations of one BigFoot NIF shot to understand how they alter target dynamics.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

The significance of the latest NIF results

If you were hoping for the thermonuclear fusion breakthrough that would provide cheap electricity to every home this is not the one. However, the recent results from the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory are a very important and notable step forward in fusion research. With regard to the scope of the NIF experiments, it is important to understand that NIF's mission is not to perfect fusion energy, but rather to establish the science related to the safety and reliability of the US stockpile of nuclear weapons. Fusion research is one element of that program. Since igniting thermonuclear fuel in the laboratory has been an elusive goal of the worldwide quest for fusion energy, the NIF ignition experiments have aroused interest within the fusion-energy community. On 28 September 2013, a millimeter-sized plastic shell containing 0.17 mg of fusion fuel (deuterium and tritium, DT) was imploded inside a small gold can called the hohlraum by 1.8 megajoules of laser light incident on the hohlraum's inner walls. The laser energy is converted into x rays by the hohlraum plasma that then irradiates and implodes the capsule. At the start of the experiment, the fusion fuel was in the form of a solid DT ice layer frozen onto the inner shell wall. The fuel layer was imploded at a velocity of around 370 km/s and its total (kinetic) energy was around 10 kilojoules. Note that less than 1% of the laser energy found its way to the fusion fuel. When the fuel was squashed into a tiny plasma ball 100 μm in size with 100 billion atmospheres of pressure, about 5000 trillion fusion reactions occurred. The total energy produced by those fusion reactions was about 14 kJ

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Application of the Solute-Solvent EMF Cell to Measure Activity of NiF 2 in Molten FLiNaK

Electromotive force (emf) measurements made using a combination of solute- and solvent-based electrodes were used to determine the activity of NiF 2 in molten FLiNaK eutectic at 823 K across a concentration range of x NiF2 = 5.2 × 10 –4 –1.0 × 10 –2 . The solute emf values were measured using electrodes consisting of Ni wires immersed in FLiNaK with dissolved NiF 2 contained in graphite crucibles. The measured emf values were then converted to the FLiNaK Eutectic Potassium Electrode (FEKE) potential and used to quantify the activity of dissolved NiF 2 . This quantification was based upon comparative measurements of a reference solvent electrode consisting of a K-Bi alloy immersed in pure FLiNaK contained in a boron nitride crucible and a solute electrode. Short cell lives were characteristic of the measurements due to the corrosive nature of the fluoride salts. Quantifying the activity of NiF 2 will improve the utility of Ni 2+ /Ni reference electrodes in molten fluoride salts, which are notoriously difficult electrolytes to work with because of their reactivity. In conclusion, this work demonstrates the general nature of the solute-solvent approach as a repeatable, easily employed method for measuring the activity values of electroactive species in a variety of molten salts to improve understanding of the electroactive species behavior in these systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Cleanliness for the NIF 1ω Laser Amplifiers

During the years before the National Ignition Facility (NIF) laser system, a set of generally accepted cleaning procedures had been developed for the large 1ω amplifiers of an inertial confinement fusion laser, and up until 1999 similar procedures were planned for NIF. Several parallel sets of test results were obtained from 1992 to 1999 for large amplifiers using these accepted cleaning procedures in the Beamlet physics test bed and in the Amplifier Module Prototype Laboratory (AMPLAB), a four-slab-high prototype large amplifier structure. Both of these showed damage to their slab surfaces that, if projected to operating conditions for NIF, would lead to higher than acceptable slab-refurbishment rates. Finally, this study tracks the search for the smoking gun origin of this damage and describes the solution employed in NIF for avoiding flashlamp-induced aerosol damage to its 1ω amplifier slabs.

42 ENGINEERING↗
DOE OSTI2011

Target Diagnostics Supports NIF's Path to Ignition

The physics requirements derived from the National Ignition Facility (NIF) experimental campaigns are leading to a wide variety of target diagnostics. Software development for the control and analysis of these diagnostics is included in the NIF Integrated Computer Control System, Diagnostic Control System and Data Visualization. These projects implement the configuration, controls, data analysis and visual representation of most of these diagnostics. To date, over 40 target diagnostics have been developed to support NIF experiments. In 2011 diagnostics were developed or enhanced to measure Ignition performance in a high neutron yield environment. Performance is optimized around four key variables: Adiabat (a) which is the strength and timing of four shocks delivered to the target, Velocity (V) of the imploding target, Mix (M) is the uniformity of the burn, and the Shape (S) of the imploding Deuterium Tritium (DT) hot spot. The diagnostics used to measure each of these parameters is shown in figure 1. Adiabat is measured using the Velocity Interferometer System for Any Reflector (VISAR) diagnostic consisting of three streak cameras. To provide for more accurate adiabat measurements the VISAR streak cameras were enhanced in FY11 with a ten comb fiducial signal controller to allow for post shot correction of the streak camera sweep non-linearity. Mix is measured by the Neutron Time of Flight (NTOF) and Radiochemical Analysis of Gaseous Samples (RAGS) diagnostics. To accommodate high neutron yield shots, NTOF diagnostic controls are being modified to use Mach Zehnder interferometer signals to allow the digitizers to be moved from near the target chamber to the neutron shielded diagnostic mezzanine. In December 2011 the first phase of RAGS diagnostic commissioning will be completed. This diagnostic will analyze the tracers that are added to NIF target capsules that undergo nuclear reactions during the shot. These gases are collected and purified for nuclear counting by the RAGS system. Three new instrument controllers were developed and commissioned to support this diagnostic. A residual-gas analyzer (RGA) instrument measures the gas content at various points in the system. The Digital Gamma Spectrometer instrument measures the radiological spectrum of the decaying gas isotopes. A final instrument controller was developed to interface to a PLC based Gas collection system. In order to support the implosion velocity measurements an additional Gated X-ray Detector (GXD) diagnostic was tested and commissioned. This third GXD views the target through a slit contained in its snout and allows the other GXD diagnostics to be used for measuring the shape on the same shot. In order to measure the implosion shape in a high neutron environment, Actide Readout In A Neutron Environment (ARIANE) and Neutron Imaging (NI) diagnostics were commissioned. The controls for ARIANE, a fixed port gated x-ray imager, contain a neutron shielded camera and micro channel plate pulser with its neutron sensitive electronics located in the diagnostic mezzanine. The NI diagnostic is composed of two Spectral Instruments SI-1000 cameras located 20M from the target and provides neutron images of the DT hot spot for high yield shots. The development and commissioning of these new or enhanced diagnostics in FY11 have provided meaningful insight that facilitates the optimization of the four key Ignition variables. In FY12 they will be adding three new diagnostics and enhancing four existing diagnostics in support of the continuing optimization series of campaigns.

42 ENGINEERING↗
DOE OSTI2015

NIF Experiment Editor Redesign. Setting up for the future

The Campaign Management project at the National Ignition Facility is embarking on a major redesign of the software used by experimentalists to setup experiments on the NIF. The current editor was architected over a decade ago and optimized for a different purpose than supporting production science campaigns. It has a steep learning curve and lacks many desirable features. Furthermore, its underlying technology stack and architecture do not support the kind of routine capability evolution that represents current and future growth needs of the Program. The principal stakeholders are the physicists who are users of the editing application, but the entire integrated suite of Campaign Management software has a broad customer base spanning experimentalists, NIF sub-system subject matter experts, planners, and shot operations staff. A recent DOE-mandated review of NIF activity, conducted with the goal of improving the shot rate at NIF, identified the experiment editor as a clear barrier to a more productive and efficient experiment lifecycle, exposing unnecessary levels of detail, lacking adequate automation, and lacking adequate integration with related activities and data sources in what should be a shared data environment.

42 ENGINEERING↗
DOE OSTI2020

Preshot Report for the NIF Discovery Science DDCyl Campaign: D_Hyd_DDCyl_DRT_DDD/EEE/FFF

The first Discovery Science shot day with the NIF DDCyl campaign demonstrated that Rayleigh-Taylor instability growth during the deceleration phase is scale-invariant for targets that varied in radial dimension and implosion time-scale by a factor of three. Smaller cylindrical implosions at the OMEGA laser facility were compared to the larger cylinders fielded in our first NIF outing. Both sets of targets had an initial m = 20 sinusoidal perturbation machined on the inner surface of an embedded aluminum marker layer, with the amplitude larger by the same factor of three for the NIF-scale targets. We observed growth factors of 14 at late time (t=λ = 7:7 ns, where λ = 1 for OMEGA and λ = 3 for NIF). These used a high density (300 mg/cm³) CH foam core, providing a very long period of deceleration before the rebounding shock hit the incoming spike tips, but the final convergence was only CR≈ 2:25. For our second shot day with this campaign, we are attempting to increase the convergence ratio to CR≥ 5 before reshock, while still measuring instability growth during the convergence/deceleration phase. As discussed in previous reports, the best way to increase convergence before reshock is to lower the density of the central foam. The preshot designs called for the use of a 30 mg/cm³ CH foam, though the as-built foams are closer to 40-42 mg/cm³, which is predicted to result in a final CR≈ 5:1 before reshock. Other than the lower foam density, the target design is identical to those used previously.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Preshot Report for the NIF DDCyl Campaign: H_Hyd_DDCyl_DRT_AAA/BBB/CCC

The first two cylinder shot days on the National Ignition Facility, allocated through the Discovery Science program, provided a successful demonstration of the cylinder platform on the NIF. Both of these shot days used cylinders that were nominally 3 times larger in radial dimension than cylinders fielded at the OMEGA laser facility, here referred to as scale-3 targets. In the first Discovery Science shot day, we demonstrated that Rayleigh-Taylor instability growth during the deceleration phase is scale-invariant between the scale-1 OMEGA experiments and similarly tailored scale-3 NIF experiments at the same convergence ratio of CR=initial radius/final radius=2.25. In the second Discovery Science shot day, we increased the convergence ratio by lowering the density of the central foam from 300 mg/cm 3 to roughly 40 mg/cm 3 with the same laser drive, resulting in a higher CR=5 at the time when the rebounding shock strikes the aluminum marker. We also greatly improved the imaging setup for the second shot day, resulting in much higher quality (greater signal-to-noise) radiographs of the implosion. This current shot day was awarded through the High Energy Density (HED) Council, following this demonstration of platform viability. It was originally scheduled for June 2020, but it was postponed several times due to the COVID-19 pandemic. It is currently scheduled for January 6, 2021. For this shot day, we will increase the radial dimension of the cylinder to four times the OMEGA-scale targets, and these will be referred to as scale-4 cylinders. Increasing the radial dimension of the target is advantageous as we push these targets to higher convergence ratio. By starting with an initially larger target, the target can push to a higher CR while maintaining the same final viewing area. Other than the larger radial dimension, the targets are very similar in design to the previous ones, consisting of an epoxy ablator, an embedded aluminum marker layer, and a low density central CH foam. These will also use a 40 mg/cm3 CH foam, reaching a CR~4.5 with the same laser energy (the added target mass reduces the final CR slightly). Note that this is NOT designed to be scale-invariant with the previous scale-1 OMEGA and scale-3 NIF shots. It was determined that the laser energy required to achieve a scale-invariant implosion was above the allowable optics damage limits (though achievable on the NIF) for these scale-4 targets.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

High-Energy Laser Direct Strike Assessment for NIF CryoXNBS Snout and Naiad SNM Container

An experimental IPT performed two NIF shots as an assessment of the effect of a direct laser beam strike impact on the NIF CryoXNBS snout and Naiad container. Four aligned NIF outer cone beams at best focus, 42 kJ total, struck a four millimeter thick stainless plate. In the first shot, the struck plate was followed by a 1.75 mm gap and a 2.0 millimeter stainless plate to create a surrogate geometry for the current CryoXNBS snout and Naiad container. There was minor plastic deformation of the rear plate rear surface with no evidence of bulk failure. The second shot tested a layered glass-filled polycarbonate and titanium shield placed in the gap. Nondestructive assay was sufficient to metrologize the beam strike area and the damage induced to the NIF target assemblies.

36 MATERIALS SCIENCE↗
DOE OSTI2025

The Concept and Role of Reference Architectures In NIF LRU Refurbishment Factories within LLNL

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) operates one of the most advanced laser systems in the world, relying on a vast number of optical components and Line Replaceable Units (LRUs) to maintain its functionality. Over time, these components degrade due to operational wear, necessitating refurbishment to sustain performance. However, many NIF LRU refurbishment factories have been “mothballed” or suffer from aging infrastructure, inconsistent work flows, and inefficiencies due to different approaches to production control and management. This paper explores the concept of reference architecture as a standardized framework to guide the redevelopment and restructuring of NIF LRU refurbishment factories. By establishing a common reference architecture, the refurbishment process can achieve reduced inefficiencies, produce quality products, and enhanced coordination across factories. This paper evaluates existing reference architectures, particularly those that integrate technical architecture, business architecture, customer context perspectives, and proposes tailored reference architecture for NIF LRU refurbishment factories.

42 ENGINEERING↗
DOE OSTI2025

Design and Development of the Handling Frame Assembly Table for the NIF Sustainment Project (Draft)

The Handling Frame Assembly Table is a custom designed piece of equipment developed to support the NIF Sustainment Project. The NIF Sustainment project's goal is to refurbish the National Ignition Facility (NIF), the world’s largest and most energetic laser, so it can continue advancing research in fusion energy, national security, and high energy density physics. A key aspect of this effort involves replacing all 1,728 blast shields on the NIF, which requires specialized equipment such as the Handling Frame Assembly Table to support the production of new blast shields. This project follows a systems engineering approach that guides the design sequence. This report documents the design process from initial concept through final design, including stakeholder analysis, requirements development, conceptual design, design analysis and validation, and final design. Future work will focus on building and commissioning the system.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Assessment of rare earth element fractionation in NIF implosions with radiochemically doped capsules

An ongoing experimental campaign at the National Ignition Facility (NIF) aims to measure neutron induced nuclear reaction cross–sections using radiochemically doped target capsules. Critical to this campaign is the ability to collect a representative sample of the reaction products using Solid Radiochemical Collectors (SRCs) fielded around the NIF chamber. The shot presented in this paper used a doped target capsule with a neopentane gas fill was to investigate the ratio of isotopes collected at three chamber angles. It was found that SRC samples of rare earth elements collected from NIF are representative of the ingoing dopant mix, thereby concluding that fractionation does not occur during a NIF implosion. This validates the doped capsule method for use in measuring neutron induced reaction cross-sections.

Capsule Doping↗
DOE OSTI2017

Fielding the LANL Gas Cherenkov Detector (GCD-3) at the National Ignition Facility: The engineering challenges of designing, analyzing, fabricating, testing, and commissioning the next-generation GCD detector and WellDIM3.9m insertion manipulator for use at NIF

We report that fielding the LANL third-generation Gas Cherenkov Detector (GCD-3) at the National Ignition Facility (NIF) revealed an array of complex engineering challenges. Fielding the GCD-3 Detector in a 3.9 meter re-entrant Well on the NIF Target Chamber required the development of a specialized detector deployment system named the WellDIM3.9m Diagnostic Manipulator (WellDIM). The most stringent design requirement entailed a no-load/no-contact condition with the Well, which dictated that all seismic loads be transferred to the Target Chamber port flange. The WellDIM transports the GCD-3 into the Well at a distance of 3.9m from Target Chamber Center. Finally, the GCD-3 Detector, outfitted with additional shielding to mitigate higher NIF backgrounds, will serve as a prototype for the future, heavily shielded “Super-GCD”.

42 ENGINEERING↗
DOE OSTI2017

Description of the NIF Laser

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 study describes the architecture, systems, and subsystems of NIF. Finally, 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.

42 ENGINEERING↗