LLE Review, Quarterly Report: Volume 98, January-March 2004 (open access)

LLE Review, Quarterly Report: Volume 98, January-March 2004

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.
Date: August 10, 2004
Creator: Goncharov, Valeri N.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 118, January-March 2009 (open access)

LLE Review, Quarterly Report: Volume 118, January-March 2009

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.
Date: August 3, 2009
Creator: Bittle, Wade A.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 114, January-March 2008 (open access)

LLE Review, Quarterly Report: Volume 114, January-March 2008

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 …
Date: July 30, 2008
Creator: Zuegel, Jonathan D.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 117, October-December 2008 (open access)

LLE Review, Quarterly Report: Volume 117, October-December 2008

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 …
Date: May 28, 2009
Creator: Bittle, Wade A.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 120, July-September 2009 (open access)

LLE Review, Quarterly Report: Volume 120, July-September 2009

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.
Date: February 19, 2001
Creator: Edgell, Dana H.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 119, April-June 2009 (open access)

LLE Review, Quarterly Report: Volume 119, April-June 2009

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.
Date: October 22, 2009
Creator: Edgell, Dana H.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 84, July-September 2000 (open access)

LLE Review, Quarterly Report: Volume 84, July-September 2000

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. …
Date: December 1, 2000
Creator: Marshall, Frederic J.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 83, April-June 2000 (open access)

LLE Review, Quarterly Report: Volume 83, April-June 2000

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 …
Date: December 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 80, July-September 1999 (open access)

LLE Review, Quarterly Report: Volume 80, July-September 1999

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.
Date: January 7, 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library