The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility containing a
192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter-diameter target chamber and
room for 100 diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific
center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser
beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to
initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10 8 K and
10 11 bar; conditions that exist naturally only in the interior of stars and planets. NIF has completed the first phases of its
laser commissioning program. The first four beams of NIF have generated 106 kilojoules in 23-ns pulses of infrared light
and over 16 kJ in 3.5-ns pulses at the third harmonic (351 nm). NIF's target experimental systems are being commissioned
and experiments have begun. This paper discusses NIF's current and future experimental capability, plans for diagnostics,
cryogenic target systems, specialized optics for experiments, and potential enhancements to NIF such as multi-color laser
operation and high-energy short-pulse operation.
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF will be the world’s largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 108 K and 1011 bar, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF has completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kilojoules of infrared light and over 16 kJ at the third harmonic (351 nm). NIF's target experimental systems are being commissioned and experiments have begun. This presentation provides a detailed look the NIF laser systems, laser and optical performance and results from recent laser commissioning shots, and plans for commissioning diagnostics for experiments on NIF.
With the first four of its eventual 192 beams now executing shots, the National Ignition Facility (NIF) at the Lawrence
Livermore National Laboratory is already the world's largest and most energetic laser. The optical system performance
requirements that are in place for NIF are derived from the goals of the missions it is designed to serve. These missions
include inertial confinement fusion (ICF) research and the study of matter at extreme energy densities and pressures.
These mission requirements have led to a design strategy for achieving high quality focusable energy and power from
the laser and to specifications on optics that are important for an ICF laser. The design of NIF utilizes a multipass
architecture with a single large amplifier type that provides high gain, high extraction efficiency and high packing
density. We have taken a systems engineering approach to the practical implementation of this design that specifies the
wavefront parameters of individual optics in order to achieve the desired cumulative performance of the laser beamline.
This presentation provides a detailed look at the causes and effects of performance degradation in large laser systems
and how NIF has been designed to overcome these effects. We will also present results of spot size performance
measurements that have validated many of the early design decisions that have been incorporated in the NIF laser
The construction of the National Ignition Facility (NIF) building and laser beampaths at the Lawrence Livermore
National Laboratory has been completed. This 8-year design/construction effort has successfully erected a 450,000 sq ft
building and filled its interior with a complex of large-scale optical benches. These benches support all of the largeaperture
optic elements of the NIF and the environmentally controlled enclosures that protect each of the 192 laser
beamlines as they propagate from the injection laser system, through large aperture amplification stages, and into the
target chamber. Even though this facility is very large, nearly 200 m long, 100 m wide, and 30 m tall, stringent
mechanical performance requirements have been achieved throughout including temperature control <0.3°C, laserbeam
pointing stability on target <50 μrms, and level 100 surface cleanliness on internal components. This presentation
will provide an historical perspective explaining the basis of the design, technical details describing the techniques of
construction and a chronological progression of the construction activities from ground breaking to beampath
The National Ignition Facility at LLNL recently commissioned the first set of four beam lines into the target chamber. This effort, called NIF Early Light, demonstrated the entire laser system architecture from master oscillator through the laser amplifiers and final optics to target and initial X-ray diagnostics. This paper describes the major installation and commissioning steps for one of NIF's 48 beam quads. Using a dedicated single beam line Precision Diagnostic System, performance was explored over the entire power versus energy space up to 6.4 TW/beam for sub-nanosecond pulses and 25 kJ/beam for 23 ns pulses at 1w. NEL also demonstrated frequency converted Nd:Glass laser energies from a single beamline of 11.3 kJ at 2w and 10.4 kJ at 3w.
Optical propagation modeling of the National Ignition Facility has been utilized extensively from conceptual design several years ago through to early operations today. In practice we routinely (for every shot) model beam propagation starting from the waveform generator through to the target. This includes the regenerative amplifier, the 4-pass rod amplifier, and the large slab amplifiers. Such models have been improved over time to include details such as distances between components, gain profiles in the laser slabs and rods, transient optical distortions due to the flashlamp heating of laser slabs, measured transmitted and reflected wavefronts for all large optics, the adaptive optic feedback loop, and the frequency converter. These calculations allow nearfield and farfield predictions in good agreement with measurements.
The Laser Performance Operations Model (LPOM) has been developed to provide real-time predictive capabilities for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. LPOM uses diagnostic feedback from previous NIF shots to maintain accurate energetics models for each of the 192 NIF beamlines (utilizing one CPU per laser beamline). This model is used to determine the system set-points (initial power, waveplate attenuations, laser diagnostic settings) required for all requested NIF shots. In addition, LPOM employs optical damage models to minimize the probability that a proposed shot may damage the system. LPOM also provides post-shot diagnostic reporting to support NIF experimenters. LPOM was deployed prior to the first main laser shots in NIF in mid-2002 and has been used to set up the every laser shot in NIF's first quad of four laser beamlines. Real-time adjustments of the LPOM energetics parameters allows the LPOM team to predict total beam energies within 5%, and to provide energy balance among the four beamlines to within 2% for shots varying from 0.5 to 26 kJ (1w) per beamline. The LPOM has been a crucial tool in the commissioning of the first quad of NIF.
The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical
materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into
production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be
achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser
performance better than the design. A suite of custom metrology tools have been designed, built and installed at the
vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront
specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of
spatial scale-lengths from 10 μm to 0.5 m (full aperture). We have continued our multi-year research effort to improve
the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric
coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed
and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as
raster and full aperture defect mapping systems. Research on damage mechanisms continues to drive the development
of even better optical materials.
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized high-energy (1.8 megajoule) / high-peak power (500 terawatt) laser system, which will utilize over 3000 meter-size Nd-doped metaphosphate glasses as its gain media. The current production status, the selection criteria of individual slabs for specific beam line locations, and some recent technical advances are reviewed. The glass blanks are manufactured by a novel continuous glass melting process, and the finished slabs are then prepared by epoxy bonding a Cu-doped phosphate glass edge cladding and by advanced finishing techniques. To date, nearly 3400 slab equivalents have been melted, 2600 have been rough-cut to blanks, 1200 have been finished, and 144 have been installed in NIF. A set of selection rules, which are designed to optimize laser performance (e.g., maintain gain balance between beam lines and minimize beam walkoff) and to maximize glass lifetime with respect to Pt damage site growth, have been established for assigning individual slabs to specific beam line locations. Recent technical advances for amplifier slab production, which include: 1) minimizing surface pitting (hazing) after final finishing; 2) minimizing humidity-induced surface degradation (weathering) upon storage and use; and 3) preventing mounting-induced surface fractures upon installation, have contributed in improving the laser glass quality.
The large-aperture (up to 40 cm × 80 cm) mirrors required for the National Ignition Facility have very stringent specifications. The specifications include requirements for transmitted and reflected wavefront over a wide spectral frequency, surface quality, laser resistance, spectral characteristics, etc. In order to validate optic performance, metrology tools were fielded at optic fabrication vendors to assure production control. These tools include interferometers, large-area conditioning stations, and photometers. Of the 1800 large-aperture mirrors required for the NIF, approximately 35% have been completed. This presentation will review the types of large-aperture mirrors used on NIF along with the performance of NIF optics as measured and received from our vendors.
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. Each beam line requires three different large-aperture optics made from single crystal potassium dihydrogen phosphate (KDP). KDP is used in the plasma electrode pockels cell (PEPC) and frequency doubling crystals, while deuterated KDP (DKDP) crystals are used for frequency tripling. Methods for reproducible growth of single crystals of KDP that meet all material requirements have been developed that enable us to meet the optics demands of the NIF. Once material properties are met, fabrication of high aspect ratio single crystal optics (42 × 42 × 1 cm) to meet laser performance specifications is the next challenge. More than 20% of the required final crystal optics have been fabricated and meet the stringent requirements of the NIF system. This manuscript summarizes the challenges and successes in the production of these large single-crystal optics.
The National Ignition Facility (NIF) is designed with its high-value optical systems in cassettes called line-replaceable Units (LRUs). Virtually all of NIF's active components are assembled in one of approximately 4000 electrical and optical LRUs that serve between two and eight of NIF's 192 laser beamlines. Many of these LRUs are optomechanical assemblies that are roughly the size of a telephone booth. The primary design challenges for this hardware include meeting stringent mechanical precision, stability, and cleanliness requirements. Pre-production units of each LRU type have been fielded on the first bundle of NIF and have been used to demonstrate that NIF meets its performance objectives. This presentation provides an overview of NIF LRUs-and their design and production plans for building out the remaining NIF bundles.
The National Ignition Facility (NIF) is a high-power, 192-beam laser facility being built at the Lawrence Livermore National Laboratory. The 192 laser beams that will converge on the target at the output of the NIF laser system originate from a low power fiber laser in the Master Oscillator Room (MOR). The MOR is responsible for generating the single pulse that seeds the entire NIF laser system. This single pulse is phase-modulated to add bandwidth, and then amplified and split into 48 separate beam lines all in single-mode polarizing fiber. Before leaving the MOR, each of the 48 output pulses are temporally sculpted into high contrast shapes using Arbitrary Waveform Generators (AWG). Each output pulse is then carried by optical fiber to the Preamplifier Module (PAM) where it is amplified to the multi-joule level using a diode-pumped regenerative amplifier and a multi-pass, flashlamp-pumped rod amplifier. Inside the PAM, the beam is spatially shaped to pre-compensate for the spatial gain profile in the main laser amplifiers. The output from the PAM is sampled by a diagnostic package called the Input Sensor Package (ISP) and then split into four beams in the Preamplifier Beam Transport System (PABTS). Each of these four beams is injected into one of NIF's 192 beam lines. The combination of the MOR, PAM, ISP and PABTS constitute the Injection Laser System (ILS) for NIF. This system has proven its flexibility of providing a wide variety of pulse shapes and energies during the first experiments utilizing four beam lines of NIF.
Large aperture Plasma Electrode Pockels Cells (PEPCs) are an enabling technology in the National Ignition Facility
(NIF) at the Lawrence Livermore National Laboratory. The Pockels cells allow the NIF laser to take advantage of multipass
main amplifier architecture, thus reducing costs and physical size of the facility. Each Pockels cell comprises four
40-cm x 40-cm apertures arranged in a 4x1 array. The combination of the Pockels cell and a thin-film polarizer, also
configured in a 4x1 array, forms an optical switch that is key to achieving the required multi-pass operation.
The operation of the PEPC is a follows: Before the arrival of the laser pulse, optically transparent, low-density helium
plasmas are initiated to serve as electrodes for the KDP crystals mounted in the Pockels cell. During beam propagation
through the main laser cavity a longitudinal electric field is impressed on the electro-optic crystals. The polarization of
the propagating beams is rotated by 90° on each of two passes, thereby allowing the beam to be trapped in the main laser
amplifier cavity for a total of four passes before being switched out into the cavity spatial filter.
The physics aspects of the PEPC are well documented. Consequently, this paper will emphasize the PEPC subsystem in
the context of its role and relevance within the broader NIF laser system, provide a view of the complexity of the
subsystem and give an overview of PEPC's interactions with other elements of NIF, including interfaces to the Beamline
Infrastructure, the NIF Timing Subsystem, and the Integrated Computer Control System (ICCS); along with dependence
on the Optics Production, Transport and Handling (T&H), and Assembly, Integration and Refurbishment (AIR) and
Operations organizations. Further, we will discuss implementation details related to the functional blocks and individual
components that comprise PEPC, with particular emphasis on the unique constraints placed on the elements and the
attendant engineering solutions. Finally, we describe performance, fabrication and assembly requirements unique to
PEPC and the various considerations necessary for successfully commissioning and operation of each PEPC unit. These
considerations include, but are not limited to, materials choices, materials preparation and processing (especially
cleanliness), inspection, pre- and post-assembly testing.
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system. High-energy-density and inertial confinement fusion physics experiments require the ability to precisely align and focus pulses with single beam energy up to 20KJ in a few nanoseconds onto mm-sized targets. NIF's alignment control system now regularly provides automatic alignment of the four commissioned beams prior to every NIF shot in approximately 45min., and speed improvements are being implemented. NIF utilizes adaptive optics for wavefront control, which significantly improves the ability to tightly focus each laser beam onto a target. Multiple sources of both static and dynamic aberration are corrected. This presentation provides an overview of the NIF Automatic Alignment and Wavefront Control Systems including the accuracy and target spot size performance achieved.
Installation and commissioning of the first of forty-eight Final Optics Assemblies on the National Ignition Facility was completed this past year. This activity culminated in the delivery of first light to a target. The final optics design is described and selected results from first-article commissioning and performance tests are presented.
Within the 192 National Ignition Facility (NIF) beamlines, there are over 7000 large (40 × 40 cm) optical components,
including laser glass, mirrors, lenses, and polarizers. These optics are held in large opto-mechanical assemblies called linereplaceable
units (LRUs). Each LRU has strict specifications with respect to cleanliness, alignment, and wavefront so that
once activated, each NIF beamline will meet its performance requirements. NIF LRUs are assembled, tested, and refurbished
in on-site cleanroom facilities. The assembled LRUs weigh up to 1800 kilograms, and are about the size of a
phone booth. They are transported in portable clean canisters and inserted into the NIF beampath using robotic transporters.
This plug and play design allows LRUs to be easily removed from the beampath for maintenance or upgrades.
Commissioning of the first NIF quad, an activity known as NIF Early Light (NEL), has validated LRU designs and architecture,
as well as demonstrated that LRUs can be assembled and installed as designed. Furthermore, it has served to
develop key processes and tools forming the foundation for NIF s long-term LRU production and maintenance strategy.
As we look forward to building out the rest of NIF, the challenge lies in scaling up the production rate while maintaining
quality, implementing process improvements, and fully leveraging the learning and experience gained from NEL. This
paper provides an overview of the facilities, equipment and processes used to assemble and install LRUs in NIF.