The advanced radiographic capability (ARC) laser system, part of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, is a short-pulse laser capability integrated into the NIF. The ARC is designed to provide adjustable pulse lengths of ∼1-38ps in four independent beamlets, each with energies up to 1 kJ (depending on pulse duration). A detailed model of the ARC lasers has been developed that predicts the time- and space-resolved focal spots on target for each shot. Measurements made to characterize static and dynamic wavefront characteristics of the ARC are important inputs to the code. Modeling has been validated with measurements of the time-integrated focal spot at the target chamber center (TCC) at low power, and the space-integrated pulse duration at high power, using currently available diagnostics. These simulations indicate that each of the four ARC beamlets achieves a peak intensity on target of up to a few 1018W/cm2.

Picosecond-scale laser–matter interactions using compound parabolic concentrators have demonstrated strongly relativistic ponderomotive effects with ∼ 10 × increase in x-ray source brightness, positron production and multi-MeV proton acceleration versus flat targets, using a marginally relativistic intensity laser.

ARC is a kilojoule petawatt-class laser system which generates high energy x-ray and particle sources for radiography of experiments on the National Ignition Facility. We present recent progress on laser performance measurements and system modeling.

We report on the design, performance, and qualification of the injection laser system designed to deliver joule-level chirped pulse beamlets arranged in dual rectangular beam formats into two main laser amplifier beamlines of the National Ignition Facility. The system is designed to meet the requirements of the Advanced Radiographic Capability upgrade with features that deliver performance, adjustability, and long-term reliability.

This talk will provide an overview of high power laser research at Lawrence Livermore National Laboratory (LLNL). It will discuss the status of the National Ignition Facility (NIF) laser. In addition, the talk will describe other laser development activities such as the development of high average power lasers and novel fiber lasers. The National Ignition Facility (NIF) has been in service since 2007 and operating with > 1 MJ energies since 2009. During this time the facility has transitioned to become an international user facility and increased the shot rate from similar to 150 target shots per year to greater than 400 shots per year. Today, the NIF plays an essential role in the US Stockpile Stewardship Program, providing data under the extreme conditions needed to validate computer models and train the next generation of stockpile stewards. Recent upgrades include the Advanced Radiographic Capability (ARC), a high energy short pulse laser used to do high resolution radiography. In addition to the NIF, this talk will include an overview of progress on the high average power laser development, recent results from fiber laser development activities and improvements to laser design and computational capabilities.

Programmable spatial shapers using liquid-crystal-based spatial-light-modulators in the National Ignition Facility lasers enable spatial shaping of the beam profile so that power delivered to the target can be maximized while maintaining system longevity. Programmable spatial shapers achieve three objectives: Introduce obscurations shadowing isolated flaws on downstream optical elements that could otherwise be affected by high fluence laser illumination; Spatial shaping to reduce beam peak-to-mean fluence variations to allow the laser to operate at higher powers so that maximum power can be delivered to the target; And finally gradually exposing the optical regions that have never seen laser light because they have always had shadowing from a blocker that is no longer needed. In this paper, we describe the control and image processing algorithms that determine beam shaping and verification of the beam profile. Calibration and transmittance mapping essential elements of controlling the PSS are described along with spatially nonlinear response of the device such as scale and rotation.

A system of customized spatial light modulators has been installed onto the front end of the laser system at the National Ignition Facility (NIF). The devices are capable of shaping the beam profile at a low-fluence relay plane upstream of the amplifier chain. Their primary function is to introduce "blocker" obscurations at programmed locations within the beam profile. These obscurations are positioned to shadow small, isolated flaws on downstream optical components that might otherwise limit the system operating energy. The modulators were designed to enable a drop-in retrofit of each of the 48 existing Pre Amplifier Modules (PAMs) without compromising their original performance specifications. This was accomplished by use of transmissive Optically Addressable Light Valves (OALV) based on a Bismuth Silicon Oxide photoconductive layer in series with a twisted nematic liquid crystal (LC) layer. These Programmable Spatial Shaper packages in combination with a flaw inspection system and optic registration strategy have provided a robust approach for extending the operational lifetime of high fluence laser optics on NIF.

We have undertaken a measurement campaign to determine the repeatability of the prompt flashlamp-induced wavefront aberration on beamlines at the National Ignition Facility (NIF) and determine the extent to which shot-to-shot variations in this aberration may degrade the performance of a proposed adaptive optics system for the short-pulse Advanced Radiographic Capability beamline on NIF. In this paper we will describe the unique NIF configuration that was required to make this measurement, present the results of the experiment, and discuss the implications of these results for the adaptive optics system design.

The National Ignition Facility (NIF) is currently the largest and most energetic laser system in the world. The main amplifiers are driven by the Injection Laser System comprised of the master oscillators, optical preamplifiers, temporal pulse shaping and spatial beam formatting elements and injection diagnostics. Starting with two fiber oscillators separated by up to a few angstroms, the pulse is phase modulated to suppress SBS and enhance spatial smoothing, amplified, split into 48 individual fibers, and then temporally shaped by an arbitrary waveform generator. Residual amplitude modulation induced in the preamplifiers from the phase modulation is also pre-compensated in the fiber portion of the system before it is injected into the 48 pre-amplifier modules (PAMs). Each of the PAMs amplifies the light from the 1 nJ fiber injection up to the multi-joule level in two stages. Between the two stages the pre-pulse is suppressed by 60 dB and the beam is spatially formatted to a square aperture with pre-compensation for the nonuniform gain profile of the main laser. The input sensor package is used to align the output of each PAM to the main laser and acquire energy, power, and spatial profiles for all shots. The beam transport sections split the beam from each PAM into four main laser beams (with optical isolation) forming the 192 beams of the NIF. Optical, electrical, and mechanical design considerations for long term reliability and availability will be discussed. Work performed under the auspices of the U. S. Department of Energy under contract W-7405-Eng-48.

There are a number of ongoing programs, teaming LLNL and industry, directed toward commercial applications of diode-pumped solid-state lasers (DPSSLs). Several programs, including direct optical lithography in the near UV, extreme-ultraviolet lithography (EUVL), and materials processing, share similar goals: demonstrating key solid-state laser technologies required for advanced manufacturing tools. These all share similar laser requirements. Specifically, the laser source must be capable of simultaneously producing high average power (300 to 500 W) at high repetition rates (700 Hz to 1.3 kHz) with high beam quality (less than several times the diffraction limit), good pointing stability, and pulse widths varying from (~10 ns to 1 μs).

A diode-pumped, solid-state laser has recently been activated in the Extreme Ultraviolet Lithography (EUVL) facility at Lawrence Livermore National Laboratory. The purpose of this report is to document the design, operation, current laser operating points, and future upgrades of the EUVL laser system.

The design of a diode pumped solid state laser for use as an x-ray driver is described. The laser will deliver 400 mJ per pulse in a 5ns to 8ns pulselength at a 1000 Hz pulse repetition rate. The laser architecture is a master oscillator/power amplifier. A microchannel cooling technique developed at LLNL is used to allow the diodes to operate at the high repetition rate. The oscillator amplifier concept has been demonstrated in a Nd:glass system. Progress to date and experimental results will be presented. The laser will deliver 400 mJ per pulse in a 5ns to 8ns pulselength at a 1000 Hz pulse repetition rate. The laser architecture is a master oscillator/power amplifier. A microchannel cooling technique developed at LLNL is used to allow the diodes to operate at the high repetition rate. The oscillator amplifier concept has been demonstrated in a Nd:glass system. Progress to date and experimental results will be presented.

A method for producing high-power broad-band coherent light via rotational Raman Stokes and anti-Stokes frequency generation in H2 is presented. A variety of potential applications include atmospheric imaging, ranging, and remote sensing. Another important potential application is producing a high-energy broad-band laser source to reduce plasma instabilities in inertial confinement fusion. The process presented here is divided into three steps. The polarization of the fields is tuned at each stage to control and optimize rotational Raman conversion. The system consists of a focused Stokes seed oscillator, collimated Stokes amplifier and a parametric mixer. A small Stokes seed is generated in a focused oscillator. A circularly polarized pump field is used here to supress parametric four-wave coupling, which insures good spatial beam quality and efficient energy conversion to first Stokes1. The circularly polarized Stokes seed is then combined with an opposite circularly polarized pump field in a collimated Raman amplifier. Again circular polarization suppresses competing parametric conversion to higher order Stokes or anti-Stokes fields. In the third stage a linearly polarized pump is combined with the amplified Stokes field, which is linearly polarized parallel to the pump and has comparable energy, in a collimated parametric mixer. Parallel linear polarization is used to maximize the parametric conversion in this final stage. Since collimated Raman cells are employed in the last two stages, this system in principle is scalable to large laser systems. This is a distinct advantage over conventional focused Raman systems 2,3, which by nature are limited in operation to small energy regimes by gas breakdown.

In the approach to quantum mechanical reactive scattering that we have been pursuing in an earlier paper, the reactive coupling has been described by a non-local exchange interaction in a coupled-channel Schrödinger equation. The results of systematic studies undertaken to identify the most efficient way to include the exchange interaction to infinite order, i.e. exactly, are reported. We find that the grid method used previously by Dardi et al. can be made much more efficient by using gaussian quadrature grids, but that still more efficient is an expansion of the exchange operator in a set of smooth basis functions via the “inner projection” approach of Adams and Miller. Test problems studied are the collinear H + D 2 , D + H 2 , and F + H 2 reactions.