This PDF file contains the front matter associated with SPIE Proceedings Volume 7916, including the Title Page, Copyright information, Table of Contents and the Conference Committee listing.

We present new calculations on radiative power losses of carbon and gold. Both ions are involved in inertial confinement fusion. The first element could also be utilized in the walls of future TOKAMAK reactors such as ITER (International Thermonuclear Experimental Reactor) while the second is present in holraums and its X-ray emission contributes to the heating in ICF. Because argon impurities may be used in the fusion core, in order to diagnose the electron temperature, we have calculated the intensities of the He-β line and the Li-like Ar satellite lines. In fact, the intensity ratio depends on electron temperature. The effect of the plasma electric field on the line intensities is discussed. Our approach is based on a detailed line calculation in which the atomic database is provided by the MCDF code. Then a lineshape code allowing for NLTE ionic populations was adapted to the calculation of RPL profiles. Because the calculation time is sometimes prohibitive, a second approach, based on the first moments of the RPL, is investigated. This approach was used for extensive calculations on germanium.

State-of-the-art, high-energy, high-power laser facilities, such as the Omega Laser Facility at the University of Rochester's Laboratory for Laser Energetics (LLE), provide unique opportunities for conducting a broad range of inertial fusion and high-energy-density physics studies. As part of the LLE National Laser Users' Facility program, a significant portion of the shot time of the 60-beam UV 30-kJ, 30-TW OMEGA and the four-beam, petawatt-class OMEGA EP Laser Systems is provided for external user experiments. These experiments include studies of matter compressed to super-high densities and pressures, inertial fusion, laboratory astrophysics, relativistic plasma physics, warm-densematter physics, and the development of advanced high-energy-density plasma diagnostic systems. Some of the challenges, exciting results, and future opportunities for inertial fusion and high-energy-density physics research will be presented.

ICF power plants, such as the LIFE scheme at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. To reduce the uncertainties of cooling and beam/target propagation through such gas-filled chambers, we present a pulsed plasma source producing 2-5 eV plasma comprised of high-Z gases. We use a 5-kJ, 100-ns theta discharge for high peak plasma-heating-power, an electrode-less discharge for minimizing impurities, and unobstructed axial access for diagnostics and beam (and/or target) propagation studies. We will report on the plasma source requirements, design process, and the system design.

The LIFE minichamber experiment will investigate cooling of the strongly radiating Xe buffer gas protecting the LIFE chamber wall. A theta pinch will inductively heat a few cc of Xe at ion density 2e16/cc to several eV. Thomson scattering will be used to determine electron temperature and ionization state. Modeled is being done using the magnetohydrodynamic code HYDRA with an external circuit model and inductive feedback from the plasma to the external circuit. Coil stresses are being assessed using the 3D MHD code ALE3D. A major challenge to the design is the paucity of opacity and conductivity data for Xe in the buffer gas regime. Results of the modeling will be presented. *This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Laser Safety at high profile laser facilities tends to be more controlled than in the standard laser lab found at a research institution. The reason for this is the potential consequences for such facilities from incidents. This ranges from construction accidents, to equipment damage to personnel injuries. No laser user wants to sustain a laser eye injury. Unfortunately, many laser users, most commonly experienced researchers and inexperienced graduate students, do receive laser eye injuries during their careers. . More unforgiveable is the general acceptance of this scenario, as part of the research & development experience. How do senior researchers, safety personnel and management stop this trend? The answer lies in a cultural change that involves institutional training, user mentoring, hazard awareness by users and administrative controls. None of these would inhibit research activities. As a matter of fact, proper implementation of these controls would increase research productivity. This presentation will review and explain the steps needed to steer an institution, research division, group or individual lab towards a culture that should nearly eliminate laser accidents. As well as how high profile facilities try to avoid laser injuries. Using the definition of high profile facility as one who's funding in the million to billions of dollars or Euros and derives form government funding.

One of the primary challenges of the Laser Inertial Fusion Engine (LIFE) project is the cost and availability of the laser diode arrays needed to pump the solid-state laser gain media in the system. Current projections indicate that the arrays need to be available for approximately one cent per Watt of output power, which is one to two orders of magnitude cheaper than currently available. This work focuses on potential manufacturing approaches to meet the projected specifications of the LIFE project. Special attention will be paid to requirements related to power density (25 kW/cm²), bar pitch (150 - 400 microns), output wavelength (87x), and fast-axis divergence (+/- 4 degrees). A summary of the supply limitations and cost ramifications of each requirement is presented. Also discussed are potential supply chain limitations that are anticipated as a result of the immense size of the LIFE project.

This year fusion ignition and gain are expected on the National Ignition Facility at LLNL. The pathway to inertial fusion energy begins by addressing high average power operation of the diode pumped solid state laser system, target chamber, target injection and tracking, target mass production, blanket, and the balance of plant. To meet efficiency requirements, the power conditioning for the laser diodes must be compact and efficient. A diode pulser has been designed to meet these specifications, operate efficiently, and provide a means to minimizing cost and size for the estimated 4.4 million pulsers needed for a power plant.

Project Orion will provide a facility for performing high energy density plasma physics experiments at AWE. The laser consists of ten, nanosecond beam lines delivering a total of 5kJ with 0.1-5ns temporally shaped pulses and two short pulse beam lines, each producing 500J in 0.5ps with intensity > 10^21 W/cm^2. The performance of the Orion laser is reported as the first phase of commissioning (one short and one long pulse beam) concludes. Target shots with all beam lines will begin in 2012.

HiPER (High Power laser Energy Research) is the first European plan for international cooperation in developing inertial fusion energy. ICF activities are ongoing in a number of nations and the first ignition experiments are underway at the National Ignition Facility (NIF) in the USA. Although HiPER is still in the preparatory phase, it is appropriate for Europe to commence planning for future inertial fusion activities that leverage the demonstration of ignition. In this paper we shall detail some of the key points of the laser design and the way this design is connected to the capsule requirements.

OMEGA EP is a petawatt-class, Nd-doped phosphate glass laser system that can be operated in both 1053-nm, short-pulse (<1- to 100-ps) and 351-nm, long-pulse (1- to 10-ns) regimes. It was completed in FY08 and began user shots in FY09 during which 350 target shots were conducted for 30 principal investigators. As of the start of FY11, over 1000 target shots have been performed. The beamline architecture consists of 40-cm, single-segment disk amplifiers in a multipass configuration to provide the necessary gain and resulting IR energy. For long-pulse operation, type-I/type-II frequency-conversion crystals are used to convert the 1053-nm fundamental wavelength to its third harmonic. An important operational goal of the Omega EP Laser Facility is to provide principal investigators with maximum UV energy on target, while maintaining UV peak fluences within an acceptable margin for safe operation. To optimize the long-pulse, on-target energy of OMEGA EP, we have pursued a threefold effort: (1) Improve the laser-induced damage threshold of beam-transport optics; (2) improve the near-field beam profile; and (3) develop simulation tools to use during shot operations that provide rapid prediction of laser-system performance. These simulation tools predict the UV near-field beam-fluence distribution and on-target energy based on measurements of the inputs to the main amplifiers and are regularly used during shot operations. They have streamlined daily system qualification, making it possible for UV energy to be maximized within current system constraints.

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.

LMJ is typical of lasers used for inertial confinement fusion and requires a laser of programmable parameters for injection into the main amplifier. For several years, the CEA has developed front end fiber sources, based on telecommunications fiber optics technologies. These sources meet the needs but as the technology evolves we can expect improved efficiency and reductions in size and cost. We give an up-to-date description of some present development issues, particularly in the field of temporal shaping with the use of digital system. The synchronization of such electronics has been challenging however we now obtain system jitter of less then 7ps rms. Secondly, we will present recent advance in the use of fiber based pre-comp system to avoid parasitic amplitude modulation from phase modulation used for spectral broadening.

The spectrum characteristic of cryogenic has been investigated and the cryogenic Yb:YAG amplification has been developing. As the temperature decreases, the stimulated emission cross section increasing rapidly with the center wavelength becoming short and the gain spectrum bandwidth narrowed. A diode-pumped cryogenic Yb:YAG regenerative amplifier at 10Hz repetition rate has been carrying out. Temperature of the Yb: YAG crystal has been controlled between 185K and 190K. A ~100 pJ optical pulse with 10 ns time duration and 10 Hz repetition rate at 1030 nm wavelength is inject into the regenerative amplifier. ~10.5 mJ output energy at 10 Hz from the regenerative amplifier with a square-pulse distortion of ~1.5 and an output-pulse-energy fluctuation of 7% was achieved.

This paper describes the alignment system developed on the Laser Mégajoule facility, allowing to focus the laser beams and to point the plasma diagnostics on the target. After an overview of the main laser components and alignment architecture, we detail some major equipments as the 6 tele-microscopes used to align the target, the continuous phase plate within the final optics assembly, the plasma diagnostic green pointer and the common reference which is the cornerstone of the chamber center alignment. Finally we present some results obtained on the telemicroscope prototype and a photometric prototype of the common reference. The expected performance of the alignment system will also be discussed.

The automatic alignment system for the National Ignition Facility (NIF) is a large-scale parallel system that directs all 192 laser beams along the 300-m optical path to a 50-micron focus at target chamber in less than 50 minutes. The system automatically commands 9,000 stepping motors to adjust mirrors and other optics based upon images acquired from high-resolution digital cameras viewing beams at various locations. Forty-five control loops per beamline request image processing services running on a LINUX cluster to analyze these images of the beams and references, and automatically steer the beams toward the target. This paper discusses the upgrades to the NIF automatic alignment system to handle new alignment needs and evolving requirements as related to various types of experiments performed. As NIF becomes a continuously-operated system and more experiments are performed, performance monitoring is increasingly important for maintenance and commissioning work. Data, collected during operations, is analyzed for tuning of the laser and targeting maintenance work. Handling evolving alignment and maintenance needs is expected for the planned 30-year operational life of NIF.

Some diagnostics at the National Ignition Facility (NIF), including the Gamma Reaction History (GRH) diagnostic, require multiple channels of data to achieve the required dynamic range. These channels need to be stitched together into a single time series, and they may have non-uniform and redundant time samples. We chose to apply the popular cubic smoothing spline technique to our stitching problem because we needed a general non-parametric method. We adapted one of the algorithms in the literature, by Hutchinson and deHoog, to our needs. The modified algorithm and the resulting code perform a cubic smoothing spline fit to multiple data channels with redundant time samples and missing data points. The data channels can have different, timevarying, zero-mean white noise characteristics. The method we employ automatically determines an optimal smoothing level by minimizing the Generalized Cross Validation (GCV) score. In order to automatically validate the smoothing level selection, the Weighted Sum-Squared Residual (WSSR) and zero-mean tests are performed on the residuals. Further, confidence intervals, both analytical and Monte Carlo, are also calculated. In this paper, we describe the derivation of our cubic smoothing spline algorithm. We outline the algorithm and test it with simulated and experimental data.

The heart of the National Ignition Facility is a megajoule-class laser system consisting of 192 beams used to drive inertial confinement fusion reactions. A recently installed system of programmable, liquid-crystal-based spatial light modulators adds the capability of arbitrarily shaping the spatial beam profiles in order to enhance operational flexibility. Its primary intended use is for introducing "blocker" obscurations shadowing isolated flaws on downstream optical elements that would otherwise be damaged by high fluence laser illumination. Because an improperly shaped blocker pattern can lead to equipment damage, both the position and shape of the obscurations must be carefully verified prior to high-fluence operations. An automatic alignment algorithm is used to perform detection and estimation of the imposed blocker centroid positions compared to their intended locations. Furthermore, in order to minimize the spatially-varying nonlinear response of the device, a calibration of the local magnification is performed at multiple sub-image locations. In this paper, we describe the control and associated image processing of this device that helps to enhance the safety and longevity of the overall system.

The goal of the European laser fusion project, is to build an engineering facility for repetitive laser operation (HiPER 4a) and later a fusion reactor (HiPER 4b). A key aspect for laser fusion energy is the final optics. At the moment, it is based on silica transmission lenses located 8 m away from the chamber center. Lens lifetime depends on the irradiation conditions. We have used a 48 MJ shock ignition target for calculations. We have studied the thermo-mechanical effects of ions and X-rays on the lenses. Ions lead to lens melting and must therefore be mitigated. On the other hand, X-rays (~1% of the energy) does not produce either a significant temperature rise or detrimental stresses. Finally, we calculated the neutron flux and gamma dose rate on the lenses. Next, based on a simple model we studied the formation of color centers in the sample, which lead to optical absorption. Calculations show that simultaneous neutron and gamma irradiation does not significantly increase the optical absorption during the expected lifetime of the HiPER 4a facility. Under severe conditions (HiPER 4b), operation above 800 K or lens refreshing by thermal annealing treatments seem to assure adequate behavior.

Thermally induced birefringence can degrade the beam quality in high-average-power laser systems with doped-glass substrates. In this work, we compare glass-laser slab amplifiers at either Brewster's angle or normal incidence and discuss trade-offs between both designs. Numerical simulations show the impact of thermally induced depolarization in both amplifier systems. A non-uniform temperature profile and the resultant mechanical stress leads to depolarization that worsens as the beam propagates through the slab-amplifier chain. Reflective losses for depolarized light at Brewster's angle cannot be compensated and degrade beam quality. This motivates the selection of normally incident slab amplifiers, which facilitates birefringence compensation. Tolerances for birefringence compensation of two matched normal-incidence glass-slab amplifiers balanced by a quartz rotator are also investigated. Imbalances in thermal load, relative amplifier position and beam magnification between amplifiers show the highest depolarization sensitivity and establish limits for manufacturing tolerances and amplifier design.

Plasma Pockels cell (PPC), which can use a thin crystal to perform the uniform electro-optical effect, is ideal component as average-power optical switch with large aperture. In this paper, by reformative design and employing a capacity to share the gas discharge voltage, the DKDP PPC driven by one pulse is realized. As gas breakdown delay time is stable, and discharge plasma is uniformly filled the full aperture, it meets the demand of plasma electrode for the repetition-rate PPC with DKDP crystal. A rep-rate plasma Pockels cell (PPC) with Φ30mm aperture has been fabricated. It is optimized with the limited space of repetition rate diode pumped laser. The specification of the PPC is: static transition of 97.2%, switching efficiency of 99.8%, the switch rising time of 8.6ns. In the LD pumped Yb:YAG plate laser system, the PPC can steadily work on 10Hz repetition rate performed as Q-switch. The key problems in PPC are analyzed for repetition-rate application, and thermo-optical effects are simulated by means of numerical modeling when average power laser is loaded on the electro-optical crystal. Furthermore, the principium design of rep-rate PPC with longitudinally conductive cooled structure is described in this paper. It will efficiently abate the thermo-optical effects under repetition rate application.

To meet the needs of some physical experiments for high energy short pulse laser, TGC (tiled gratings compressor) technology and beams-combination technology are required. Progress of TGC and beams-combination at CAEP is introduced. On TGC technology, interference pattern and far field distribution is used to initially eliminate the tiling error, and displacement sensor is used as feedback to maintain the posture of the sub-gratings. As for beams-combination a preliminary method of feedback control in subsections is proposed and will be expected to be used in an integrated test-bed.

This paper describes the synchronisation system under development on the Laser Mégajoule (LMJ) in order to synchronize the laser quads on the target to better than 40ps rms. Our architecture is based on a Timing System (TS) which delivers trigger signals with jitter down to 15ps rms coupled with an ultra precision timing system with 5ps rms jitter. In addition to TS, a sensor placed at the target chamber center measures the arrival times of the 3ω nano joule laser pulses generated by front end shots.

The Laser Integration Line (LIL) was first designed as a prototype to validate the concepts and the laser architecture of the Laser MegaJoule (LMJ). The LIL facility is a 4-beam laser representing a quad structure of the LMJ. A set of test campaigns were conducted to safely ramp up laser performance. The main goal was to measure quad-specific features such as beam synchronization and focal spot (size, smoothing contrast ratio or irradiation nonuniformity) versus the LMJ requirements. Following the laser commissioning, the LIL has become a major instrument dedicated to the achievement of plasma physics experiments for the French Simulation Program and was also opened to the academic scientific community. One of the attributes of the LIL facility is to be very flexible to accommodate the requests of plasma physicists during campaigns. The LIL is constantly evolving to best meet the needs of target physicists. Changes made or planned are either to improve the quality of laser beams, or to increase the LIL Energy-Power operating space. To optimize preparation and design of shot campaigns, the LIL performance status has been elaborated. It gives information about the characteristics of the laser in terms of near field and far field, defines the steps to maintain performance, explains how the facility responds to the request, details settings (smoothing, shaping of the focal spot, energy, temporal pulse shaping, beam pointing) and gives the limits in energy and power. In this paper, an overview of the LIL performance is presented.

By directly measuring the spherical wavefront near the focus, we demonstrated a approach to efficiently correct convergent spherical wavefront by installing a common small aperture deformable mirror (DM) in the middle of 0.89PW/29.0fs Ti:sapphire CPA laser chain. It is, to our knowledge, the first time attain the near perfect correction result in ultra-intensity laser system by correcting convergent spherical wavefront using a small aperture DM in adaptive optical loop. Finally the maximum peak intensity of 2.59×10^21 W/cm2 was obtained with an f/4 off-axis parabola at the output power of 0.89 PW.

National Ignition Facility (NIF) is a high-energy laser facility comprised of 192 laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to initiate a fusion reaction. The target container, or hohlraum, must be accurately aligned to an x-ray imaging system to allow careful monitoring of the frozen fuel layer in the target. To achieve alignment, x-ray images are acquired through starburst-shaped windows cut into opposite sides of the hohlraum. When the hohlraum is in alignment, the starburst pattern pairs match nearly exactly and allow a clear view of the ice layer formation on the edge of the target capsule. During the alignment process, x-ray image analysis is applied to determine the direction and magnitude of adjustment required. X-ray detector and source are moved in concert during the alignment process. The automated pointing alignment system described here is both accurate and efficient. In this paper, we describe the control and associated image processing that enables automation of the starburst pointing alignment.

The National Ignition Facility (NIF) is the largest and most energetic laser in the world contained in a complex the size of a football stadium. From the initial laser pulse, provided by telecommunication style infrared nanoJoule pulsed lasers, to the final 192 laser beams (1.8 Mega Joules total energy in the ultraviolet) converging on a target the size of a pencil eraser, laser safety is of paramount concern. In addition to this, there are numerous high-powered (Class 3B and 4) diagnostic lasers in use that can potentially send their laser radiation travelling throughout the facility. With individual beam paths of up to 1500 meters and a workforce of more than one thousand, the potential for exposure is significant. Simple laser safety practices utilized in typical laser labs just don't apply. To mitigate these hazards, NIF incorporates a multi layered approach to laser safety or "Defense in Depth."