This issue has the following articles: (1) Optimizing Electron-Positron Pair Production on kJ-Class High-Intensity Lasers for the Purpose of Pair-Plasma Creation; (2) Neutron Yield Study of Direct-Drive, Low-Adiabat Cryogenic D2 Implosions on OMEGA; (3) Al 1s-2p Absorption Spectroscopy of Shock-Wave Heating and Compression in Laser-Driven Planar Foil; (4) A Measurable Lawson Criterion and Hydro-Equivalent Curves for Inertial Confinement Fusion; (5) Pulsed-THz Characterization of Hg-Based, High-Temperature Superconductors; (6) LLE's Summer High School Research Program; (7) FY08 Laser Facility Report; and (8) National Laser Users Facility and External Users Programs.

This issue has the following articles: (1) Shock-Ignition Experiments on OMEGA at NIF-Relevant Intensities; (2) Laser-Driven Magnetic-Flux Compression in High-Energy-Density Plasmas; (3) Lorentz Mapping of Magnetic Fields in Hot, Dense Plasmas; (4) Characterization and Optimization of Yb-Doped Photonic-Crystal Fiber Rod Amplifiers Using Spatially Resolved Spectral Interferometry; (5) Optical Differentiation and Multimillijoule {approx}150-ps Pulse Generation in a Regenerative Amplifier with a Temperature-Tuned Intracavity Volume Bragg Grating; (6) Slow Crack Growth During Radiatiave Cooling of LHG8 and BK7 Plates; and (7) Finite Element Simulation of Metal-Semiconductor-Metal Photoconductor.

This issue has the following articles: (1) Applied Plasma Spectroscopy: Laser-Fusion Experiments; (2) Relativistic Electron-Beam Transport Studies Using High-Resolution, Coherent Transition Radiation Imaging; (3) Pressure-Driven, Resistive Magnetohydrodynamic Interchange Instabilities in Laser-Produced, High-Energy-Density Plasmas; (4) Extended Model for Polymer Cholesteric Liquid Crystal Flake Reorientation and Relaxation; (5) Modeling the Effects of Microencapsulation on the Electro-Optic Behavior of Polymer Cholesteric Liquid Crystal Flakes; (6) Capillarity and Dielectrophoresis of Liquid Deuterium; and (7) A Stable Mid-IR, GaSb-Based Diode Laser Source for Cryogenic Target Layering at the OMEGA Laser Facility.

This volume of the LLE Review, covering October-December 2008, features 'Demonstration of the Shock-Timing Technique for Ignition Targets at the National Ignition Facility' by T. R. Boehly, V. N. Goncharov, S. X. Hu, J. A. Marozas, T. C. Sangster, D. D. Meyerhofer (LLE), D. Munro, P. M. Celliers, D. G. Hicks, G. W. Collins, H. F. Robey, O. L. Landen (LLNL), and R. E. Olson (SNL). In this article (p. 1) the authors report on a technique to measure the velocity and timing of shock waves in a capsule contained within hohlraum targets. This technique is critical for optimizing the drive profiles for high-performance inertial-confinement-fusion capsules, which are compressed by multiple precisely timed shock waves. The shock-timing technique was demonstrated on OMEGA using surrogate hohlraum targets heated to 180 eV and fitted with a re-entrant cone and quartz window to facilitate velocity measurements using velocity interferometry. Cryogenic experiments using targets filled with liquid deuterium further demonstrated the entire timing technique in a hohlraum environment. Direct-drive cryogenic targets with multiple spherical shocks were also used to validate this technique, including convergence effects at relevant pressures (velocities) and sizes. These results provide confidence that shock velocity and timing can be measured in …

This volume of the LLE Review, covering January-March 2008, features 'Cryogenic Targets: Current Status and Future Development', by D. R. Harding, D. H. Edgell, M. D. Wittman, L. M. Elasky, S. J. Verbridge, A. J. Weaver, L. D. Lund, W. Seka, W. T. Shmayda, R. T. Janezic, M. J. Shoup III, M. Moore, R. Junquist, and A. V. Okishev. In this article (p. 57), the authors report on the status of layering cryogenic DT and D{sub 2} targets at LLE for inertial confinement fusion (ICF) targets. This critical effort achieves the important milestone of routinely providing cryogenic DT targets that meet the 1.0-{micro}m (rms) OMEGA ice-quality-surface specification. The best D{sub 2}-ice layers produced so far (rms roughness of 1.1 {micro}m) are approaching the quality typically achieved in DT targets. Efforts to improve the consistency of this process are reported along with investigations supporting the National Ignition Campaign studying issues relevant to indirect-drive and direct-drive cryogenic targets. Additional highlights of recent research presented in this issue include the following: (1) an improved laser speckle smoothing scheme that augments the current NIF 1-D SSD system by using multiple-FM modulators (MultiFM 1-D SSD) (p. 73). With a judicious choice of modulator frequencies, MultiFM …

This volume of the LLE Review, covering January-March 2004, features ''Performance of 1-THz-Bandwidth, 2-D Smoothing by Spectral Dispersion and Polarization Smoothing of High-Power, Solid-State Laser Beams'', by S. P. Regan, J. A. Marozas, R. S. Craxton, J. H. Kelly, W. R. Donaldson, P. A. Jaanimagi, D. Jacobs-Perkins, R. L. Keck, T. J. Kessler, D. D. Meyerhofer, T. C. Sangster, W. Seka, V.A. Smalyuk, S. Skupsky, and J. D. Zuegel (p. 49). Laser-beam smoothing achieved with 1-THz-bandwidth, two-dimensional smoothing by spectral dispersion and polarization smoothing on the 60-beam, 30-kJ, 351-nm OMEGA laser system is reported. These beam-smoothing techniques are directly applicable to direct-drive ignition target designs for the 192-beam, 1.8-MJ, 351-nm National Ignition Facility. Equivalent-target-plane images for constant-intensity laser pulses of varying duration were used to determine the smoothing. The properties of the phase plates, frequency modulators, and birefringent wedges were simulated and found to be in good agreement with the measurements.

This issue has the following articles: (1) The Omega Laser Facility Users Group Workshop; (2) The Effect of Condensates and Inner Coatings on the Performance of Vacuum Hohlraum Targets; (3) Zirconia-Coated-Carbonyl-Iron-Particle-Based Magnetorheological Fluid for Polishing Optical Glasses and Ceramics; (4) All-Fiber Optical Magnetic Field Sensor Based on Faraday Rotation in Highly Terbium Doped Fiber; (5) Femtosecond Optical Pump-Probe Characterization of High-Pressure-Grown Al{sub 0.86}Ga{sub 0.14}N Single Crystals; (6) LLE's Summer High School Research Program; (7) Laser Facility Report; and (8) National Laser Users Facility and External Users Programs.

This volume of the LLE Review, covering April-June 2000, features an article by F. J. Marshall, T. Ohki, D. McInnis, Z. Ninkov, and J. Carbone, who detail the conversion of the OMEGA time-integrated x-ray diagnostics to electronic readout using direct-detection x-ray cameras [charge-injection devices (CID's)]. Pinhole and x-ray microscope images are shown along with inferred calibration measurements of the CID cameras. Currently, the same cameras are being used to obtain x-ray spectra in a TIM-based spectrometer, extending their use to all time-integrated imaging and spectroscopic x-ray instruments used on OMEGA. Additional highlights of the research presented in this issue are: (1) V. A. Smalyuk, B. Yaakobi, F. J. Marshall, and D. D. Meyerhofer investigate the spatial structure of the temperature and density of target-shell plasmas at peak compression (stagnation). This is accomplished by examining the energy dependence of the x-ray emission using narrow-band x-ray filters and the known absorption properties of the shell dopant (Ti). (2) F. Sequin, C. K. Ll, D. G. Hicks, J. A. Frenje, K. M. Green, R. D. Petrasso, J. M. Soures, V. Yu. Glebov, C. Stoeckl, P. B. Radha, D. D. Meyerhofer, S. Roberts, C. Sorce, T. C. Sangster, M. D. Cable, S. Padalino, and …

This volume of the LLE Review, covering July-September 2000, begins with an article by T. R. Boehly, V. N. Goncharov, O. Gotchev, J. P. Knauer, D. D. Meyerhofer, D. Oron, S. P. Regan, Y. Srebro, W. Seka, D. Shvarts, S. Skupsky, and V.A. Smalyuk, who describe measurements of the effect of beam smoothing and pulse shape on imprinting. (Imprinting is defined as the imposition of pressure perturbations on the target by spatial variations in the laser intensity.) A principal result is the observation of reduced levels of imprint with the higher beam smoothing afforded by 1-THz smoothing by spectral dispersion (SSD). Additional highlights of research presented in this issue are: (1) P. W. McKenty, V. N. Goncharov, R. P. J. Town, S. Skupsky, R. Betti, and R. L. McCrory describe calculations of directly driven ignition capsule performance on the National Ignition Facility (NIF). The authors detail how the various contributors to implosion disruption (laser imprint, power imbalance, and target roughness) affect target performance and final gain. The conclusions are obtained by examining the simulated target evolution with the two-dimensional hydrodynamics computer code ORCHID. (2) D. D. Meyerhofer, J. A. Delettrez, R. Epstein, V. Yu. Glebov, V. N. Goncharov, R. L. …

This volume of the LLE Review, covering the period July-September 1999, features a theoretical analysis of a process that generates mass perturbations of an imploding target driven by modulated laser illumination. The process, referred to as laser imprint, impacts the integrity of the shell during direct-drive implosions, potentially quenching target performance. In this article V. N. Goncharov, J. A. Delettrez, S. Skupsky, and R. P. J. Town present a model of the generation of mass perturbations and analyze the mass perturbation growth due to nonuniform ablation pressure. Stabilizing mechanisms of thermal conduction smoothing and mass ablation are shown to suppress the acceleration perturbation, and mass ablation is also shown to impact velocity perturbations. The model predicts that a direct-drive cryogenic NIF target will remain intact during the implosion when l-Thz SSD beam smoothing is used.

This volume of the Laboratory for Laser Energetics (LLE) Review, covering the period April-June 1999, features a theoretical analysis of direct-drive target performance on National Ignition Facility (NIF). In this article R. P. J. Town, J. A. Delettrez, R. Epstein, V. N. Goncharov, R. L. McCrory, P. W. McKenty, R. W. Short, and S. Skupsky detail ignition target designs developed at LLE specifically to achieve successful direct-drive ignition on the NIF facility. A baseline ''all-DT'' target design is described along with a two shock compression analysis, which includes discussion of the parameters leading to variability in shock timing. The modeling and analysis presented flow down to specification requirements for the laser and target parameters to ignite this baseline target design with the NIF laser.

This volume of the LLE Review, covering the period October--December 1998, includes two articles addressing issues applicable to direct-drive ICF on the National Ignition Facility (NIF): laser-plasma interactions and laser-irradiation uniformity. Additional highlights of the research presented in this issue are: (1) P.B. Radha and S. Skupsky present a novel charged-particle diagnostic that performs simultaneous {rho}R measurements of the fuel, shell, and ablator regions of a compressed ICF target, consisting of an inner DT fuel region, a plastic (CH) shell, and an ablator (CD), by measuring the knock-on deuteron spectrum. (2) F. Dahmani, S. Burns, J. Lambropoulos, S. Papernov, and A. Schmid report results from stress-inhibited laser-driven crack propagation and stress-delayed damage-initiation experiments in fused silica at 351 nm. Research is underway presently to determine the ramifications of these findings for large-aperture systems, such as OMEGA. (3) V. Goncharov presents an analytic theory of the ablative Richtmyer-Meshkov instability, which shows that the main stabilizing mechanism of the ablation-front perturbations is the dynamic overpressure of the blowoff plasma with respect to the target material. The perturbation evolution during the shock transit time is studied to determine the initial conditions for the Rayleigh-Taylor phase of the instability and to analyze the level …

This volume of the LLE Review covers the period January--March 1998. The first of eight articles documents the in-house development, scale-up, and manufacture of 60 continuous distributed phase plates with high laser-damage resistance. D.J. Smith et al. describe how inert ion beams were used to etch a continuously varying pattern into the surface of fused silica to form these devices. Other highlights of research presented in this issue are: (1) a soft x-ray microscope with high spatial resolution has been characterized and used for initial experiments on the OMEGA laser system, F.J. Marshall et al. give details of the testing, calibration, and initial use of this microscope for studying the hydrodynamic stability of directly driven planar foils; (2) D.K. Bradley et al. report on a series of experiments designed to investigate hydrodynamic instability growth in direct-drive capsule implosions; (3) C.J. McKinstrie et al. report on the use of systematic perturbation methods to derive formulas for the Landau damping rates of electron-plasma and ion-acoustic waves; (4) high efficiency and good beam quality are potential advantages of the end-pumped solid-state lasers over the side-pumped ones, A. Babushkin et al. describe their successful use of a transport fiber to end-pump a Nd:YLF laser, …

This progress report contains discussion on the following topics: A high-bandwidth electrical-waveform generator based on aperture-coupled striplines for OMEGA pulse-shaping applications; sweep deflection circuit development using computer-aided circuit design for the OMEGA multichannel streak camera; D-{sup 3}He protons as a diagnostic for target {rho}R; growth rates of the ablative Rayleigh-Taylor instability in inertial confinement fusion; three-dimensional analysis of the power transfer between crossed laser beams; characterization of freestanding polymer films for application in 351-nm, high-peak-power laser systems; subsurface damage in microgrinding optical glasses; bound-abrasive polishers for optical glass; and color gamut of cholesteric liquid crystal films and flakes by standard colorimetry.

This volume of the LLE Review, covering the period July--September 1997, begins with a general introduction to LLE`s experimental physics program and a report on recent results. This article includes a useful summary of the system`s operational capabilities and system parameters. Other highlights of the wide variety of research presented in this issue are: a promising method to directly observe the cold compressed shell of an imploding target. The shell is normally observed by backlighting. The proposal described here is to use a high-Z dopant that fluoresces under radiation from the hot core in the K{alpha} line. A study of the instabilities associated with near-forward stimulated Brillouin scattering. It includes a calculation of the saturation times and steady-state gain exponents. A successful program of pulse shaping for the OMEGA laser system. Examples of a variety of pulse shapes that can be programmed are presented. A description of the angular-scattering characteristics of ferroelectric liquid crystal electro-optical devices operating in transient and extended scattering modes. The possibility of applying these devices as modulators in practical IR imaging systems is evaluated. A faster method of shaping and finishing IR materials by the use of magnetorheological fluids. Detailed specifications and test results are included. …

This volume of the LLE Review, covering the period April-June 1997, includes an article discussing the results from recent experiments performed on OMEGA. These experiments used a new beam-smoothing device-distributed polarization rotators-in concert with existing techniques to improve the on-target uniformity of each beam. The result of this improved radiation uniformity was a substantive reduction in imprinting-the nonuniformity caused by the laser. A novel way to study the time dependence of this imprinting is also presented in this article.

This volume of the LLE Review includes an article on the status of the optics on the OMEGA laser system after the first 18 months of operation. A vigorous program to monitor the performance of the optics has been followed since the inception of the OMEGA laser. The article presents results from these observations and defines the various types of possible damage. Many of the optics have not damaged, such as the frequency-conversion crystals, polarizers, calorimeters, and liquid crystal optics. The most significant damage has been sustained by the fused-silica spatial filter lenses. There has been no evidence of any propagation of damage downstream of damage optics. Other highlights of research presented here are: The development of a single-beam, ponderomotive optical trap for energetic free electrons. A description of the new diode-pumped Nd:YLF master oscillator for the OMEGA laser. Simulations of heat transfer from localized absorbing defects to the host coating material in HfO{sub 2}/SiO{sub 2} 351-nm high reflectors. An experimental study of target performance and mixing in titanium-doped target implosions on OMEGA. A theoretical calculation of the dephasing time of an electron accelerated by a laser pulse. Separate abstracts have been indexed into the energy database from articles in …

This volume of the LLE Review, covering the period October-December 1996, includes a review of 2-D SSD as implemented on the OMEGA laser system. A summary of the detailed mathematical formalism is shown, and the predicted level of uniformity achievable on OMEGA is given. The first experimental results on uniformity using narrow-band 2-D SSD are compared to theoretical calculations. Excellent agreement between experiment and theory is found, which gives confidence that broadband 2-D SSD with polarization wedges should achieve an rms nonuniformity in the 1%-2% level necessary for cryogenic implosion experiments.

This volume contains articles detailing several nonlinear processes associated with lasers and their use, as well as an article describing the computer control systems necessary to maintain and operate a large laser system such as the 60-beam OMEGA laser. The specific topics discussed in this issue include stimulated scattering in laser plasmas, power exchange between interacting laser beams, charged particles interacting with a laser pulse, thermal equilibration of optically excited states, an overview of the laser control system software in OMEGA, and a technique for cancellation of the nonlinear phase accumulation in short-pulse lasers.

This volume of the LLE Review, covering the period of July-September 1996, includes a description of an important experiment carried out on OMEGA by researchers from LANL, LLNL, and LLE to demonstrate the feasibility of using OMEGA for indirect drive. Additional topics include tetrahedral hohlraums, the speckle properties of phase- converted laser beams, design criteria for SSD phase modulators, and the design of slab amplifiers. Highlights of the research presented in this issue are (1) Results from the proof-of-principle indirect- drive experiments in which up to 40 OMEGA beams were used to irradiate cylindrical hohlraums. Nova results were reproduced, and new capabilities not available on other lasers were demonstrated. (2) A discussion of tetrahedral hohlraums (spherical hohlraums with four laser entrance holes) as a means of achieving better capsule irradiation uniformity. Tetrahedral hohlraums also allow the use of all 60 OMEGA beams and may provide an alternate route to ignition on the NIF. (3) An analysis of the residual target irradiation nonuniformity due to the fine laser speckle remaining on the beam after being phase converted by the DPP`s. A model shows how a uniformly ablating plasma atmosphere reduces the speckle contribution to the effective time-averaged irradiation nonuniformity. (4) A …

This volume of the LLE Review, covering the period October-December 1995, contains a description of the generation and characterization of continuous, deep-surface-relief phase plates that are more efficient and versatile than previous designs. The LLE program plan has scheduled a number of enhancements to OMEGA`s performance and uniformity, the first of which is the implementation of these new distributed phase plates. Other articles in this volume include the discussion of an x-ray diagnostic method to measure shell-fuel mixing, the theoretical analysis of ablation-front stability, a description of a major subsystem in the OMEGA control system software, a study of the population inversions in intensely pumped Nd:YLF, and a description of a new ultrafast laser system and its uses.

This volume of the LLE Review, covering the period January-March 1996, contains three articles related to spherical implosions and their diagnosis, one article that provides an analysis of laser-plasma interactions, and three articles on advanced technologies developed at LLE.

This volume of the LLE Review, covering the period of April--June 1995, includes a description of the initial performance results of the upgraded OMEGA laser system. A series of acceptance tests were completed, demonstrating that all 60 beams can irradiate targets with more energy and better beam balance than was required by the Department of Energy`s acceptance criteria. Other articles in this volume include a description of a novel energy measurement system used to diagnose all 60 OMEGA beams; a theoretical calculation of the cutoff wave number of the ablative Rayleigh-Taylor instability, applicable to both direct and indirect drive; a description of a new algorithm used for designing distributed phase plates that will produce super-Gaussian focal-plane irradiance profiles: a study of the photoresponse of high-{Tc} YBCO thin films; and a description of magnetorheological finishing, a new process for optics polishing.

This volume of the LLE Review, covering the period July--September 1995, includes a description of the first target experiments performed on the upgraded OMEGA laser system. These experiments, carried out to active and test several diagnostics systems, have demonstrated successful functioning of the overall experimental system and have produced high neutron yields and high core temperatures. Other articles in this volume describe the diagnosis of core conditions using krypton line spectroscopy, a mix model for LILAC that can be applied to study the deceleration instability at the pusher-core interface, a simulated-annealing algorithm for improved phase-plate design, a simple method for characterizing the thickness and uniformity of transparent laser-fusion targets, and femtosecond pump-probe experiments on semiconducting YBCO.