LLE Annual Report
The fiscal year ending September 2014 (FY14) concluded the first 18 months of the fourth five-year renewal of Cooperative Agreement DE-NA0001944 with the U.S. Department of Energy (DOE). This annual report summarizes work carried out under the Cooperative Agreement at the Laboratory for Laser Energetics (LLE) during the past fiscal year including work on the Inertial Confinement Fusion (ICF) Campaign; laser, optical materials, and advanced technology development; operation of the Omega Laser Facility for the ICF and High-Energy-Density (HED) Campaigns, the National Laser Users' Facility (NLUF), the Laboratory Basic Science (LBS) Program, and other external users; and programs focusing on the education of high school, undergraduate, and graduate students during the year.
Inertial Confinement Fusion Research
One of LLE's principal missions is to conduct research in ICF with particular emphasis on supporting the goal of achieving ignition on the National Ignition Facility (NIF). This program uses the Omega Laser Facility and the full experimental, theoretical, and engineering resources of the laboratory. During FY14, a record total of 2104 target shots were taken at the Omega Laser Facility (comprised of the 60-beam OMEGA UV laser and the four-beam, high-energy petawatt OMEGA EP laser). More than 42% of the facility's target shots in FY14 were designated as ICF experiments or experiments in support of ICF. The OMEGA and OMEGA EP lasers attained average experimental effectiveness of 93.3% and 92.8%, respectively, in FY14.
LLE plays a lead role in validating the performance of cryogenic target implosions, essential to all forms of ICF ignition. LLE is responsible for a number of critical elements within the Integrated Experimental Teams that support the demonstration of indirect-drive ignition on the NIF and is the lead laboratory for the validation of the polar-direct-drive (PDD) approach to ignition on the NIF. LLE has also developed, tested, and constructed a number of diagnostics that are being used at both the Omega Laser Facility and the NIF. During this past year, progress in the Inertial Fusion Research Program continued in three principal areas: ICF experiments and experiments in support of ICF; theoretical analysis and design efforts aimed at improving direct-drive–ignition capsule designs (including polar-direct-drive–ignition designs) and advanced ignition concepts such as shock ignition and fast ignition; and development of diagnostics for experiments on the NIF, OMEGA, and OMEGA EP.
Lasers, Optical Materials and Advanced Technology
The Laboratory's efforts in the development of advanced high-power lasers and optical materials in support of its inertial fusion and HED research programs is also covered in this volume, including the demonstration that cascaded nonlinearities in a regenerative amplifier compensate for intracavity self-phase modulation—important for the generation of high-quality short optical pulses; the finding that absorption of near UV photons by HfO2 monolayer films is reduced by up to 70% following irradiation by continuous-wave near-UV laser light—important for high-power laser optical coatings; the demonstration of a new collimated ion-beam sputtering process for depositing a multilayer reflector over the surface relief of a sinusoidal diffraction grating—attractive for high-laser-damage-threshold applications; the installation of a programmable liquid crystal beam-shaping system in a chirped-pulsen–amplification system front end—used to improve beam uniformity in the subsequent amplifier.
FY14 Omega Facility Operations
During FY14, the Omega Laser Facility conducted 1405 target shots on OMEGA and 699 target shots on OMEGA EP for a total of 2104 target shots [see Tables 140.III and 140.IV (p. 250)].
OMEGA averaged 11.1 target shots per operating day with Availability and Experimental Effectiveness averages for FY14 of 95.8% and 93.3%, respectively.
OMEGA EP was operated extensively in FY14 for a variety of internal and external users. A total of 638 target shots were taken into the OMEGA EP target chamber and 61 joint target shots were taken into the OMEGA target chamber. OMEGA EP averaged 7.6 target shots per operating day with Availability and Experimental Effectiveness averages for FY14 of 95.7% and 92.8%, respectively.
Per the guidance provided by DOE/NNSA (National Nuclear Security Administration), the facility provided target shots for the ICF, HED, NLUF, and LBS programs. The facility also provided a small number of shots for Commissariat á l'Énergie Atomique et aux Energies Alternatives (CEA) and for the Defense Threat Reduction Agency (DTRA) (see Fig. 1). Nearly 69% of the target shots in FY14 were taken for the ICF and HED programs.
National Laser Users' Facility and External Users Programs
The fundamental science campaigns accounted for 26.9% of the shots taken in FY14. Nearly half of these were dedicated to university fundamental science under the NLUF Program, and the remaining shots were allotted to the LBS Program, comprising peer-reviewed fundamental science experiments conducted by the national laboratories and by LLE, including the Fusion Science Center (FSC).
The Omega Laser Facility is also used for several campaigns by teams from CEA of France and the Atomic Weapons Establishment (AWE) of the United Kingdom. These programs are conducted at the facility on the basis of special agreements put in place by DOE/NNSA and participating institutions.
The facility users during this year included 11 collaborative teams participating in the NLUF Program; 16 teams led by Lawrence Livermore National Laboratory (LLNL) and LLE scientists participating in the LBS Program; many collaborative teams from the national laboratories conducting ICF experiments; investigators from LLNL and Los Alamos National Laboratory (LANL) conducting experiments for high-energy-density-physics programs; and scientists and engineers from CEA.
Omega Laser Facility Users Group (OLUG)
A capacity gathering of over 100 researchers from 25 universities and laboratories met at LLE for the Sixth Omega Laser Facility Users Group (OLUG) workshop to facilitate communications and exchanges among individual Omega users, and between users and the LLE management; to present ongoing and proposed research; to encourage research opportunities and collaborations that could be undertaken at the Omega Laser Facility and in a complementary fashion at other facilities [such as the NIF or the Laboratoire pour l'Utilisation des Lasers Intenses (LULI)]; to provide an opportunity for students, postdoctoral fellows, and young researchers to present their research in an informal setting; and to provide feedback from the users to LLE management about ways to improve and keep the facility and future experimental campaigns at the cutting edge.
As the only major university participant in the National ICF Program, education continues as an important mission for LLE. The Laboratory's education programs cover the range from high school to graduate education.
The high school program involved 16 students chosen from Rochester-area high schools. The projects were related to current research activities at LLE and covered a broad range of areas of interest including laser physics, computational modeling of implosion physics, radiation physics, experimental diagnostic development, cryogenic targets, theoretical and experimental chemistry, tritium capture, electronics, image display, and 3-D virtual modeling.
Thirty-two undergraduate students participated in work or research projects at LLE this past year. Student projects include operational maintenance of the Omega Laser Facility; work in laser development, materials, and optical thin-film coating laboratories; computer programming; image processing; and diagnostics development. This is a unique opportunity for students, many of whom will go on to pursue a higher degree in the area in which they gained experience at LLE.
Presently, 64 graduate students are involved in research projects at LLE, and LLE directly sponsors 37 students pursuing Ph.D. degrees via the NNSA-supported Frank Horton Fellowship Program in Laser Energetics. Their research includes theoretical and experimental plasma physics, HED physics, x-ray and atomic physics, nuclear fusion, ultrafast optoelectronics, high-power laser development and applications, nonlinear optics, optical materials and optical fabrication technology, and target fabrication. In addition, LLE directly funds research programs within the MIT Plasma Science and Fusion Center, the State University of New York (SUNY) at Geneseo, and the University of Wisconsin.
Table of Contents
- Theory of Hydro-Equivalent Ignition for Inertial Fusion and Its Applications to OMEGA and the National Ignition Facility
- Improving Hot-Spot Pressure and Demonstrating Ignition Hydrodynamic Equivalence in Cryogenic Deuterium–Tritium Implosions on OMEGA
- Measurements of Electron Density Profiles Using an Angular Filter Refractometer
- Multibeam Laser–Plasma Interactions in Inertial Confinement Fusion
- First-Principles Thermal Conductivity of Deuterium for Inertial Confinement Fusion Applications
- Self-Phase Modulation Compensation in a Regenerative Amplifier Using Cascaded Second-Order Nonlinearities
- Method to Measure Young's Modulus and Damping of Fibers at Cryogenic Temperatures
- Self-Generated Magnetic Fields in Direct-Drive–Implosion Experiments
- Absolute Calibration of the OMEGA Streaked Optical Pyrometer for Laser-Driven Shock Waves
- Multibeam Two-Plasmon Decay in Three Dimensions: Thresholds and Saturation
- Near-Ultraviolet Absorption Annealing in HfO2 Thin Films Subjected to Continuous-Wave Laser Irradiation
- Static and Optical Properties of Warm Dense Polystyrene Along the Principal Hugoniot
- Fabrication of a a Continuous-Enfolding Grating by Ion-Beam–Sputter Deposition
- Magnetic Reconnection Between Colliding Magnetized, Laser-Produced Plasma Plumes
- Implosion Dynamics in Direct-Drive Experiments
- X-Ray Continuum as a Measure of Pressure and Fuel–Shell Mix in Compressed Isobaric Hydrogen Implosion Cores
- Soft X-Ray Backlighting of Cryogenic Implosions Using a Narrowband Crystal Imaging System
- Time-Resolved Compression of a Spherical Shell with a Re-Entrant Cone to High Areal Density for Fast-Ignition Laser Fusion
- Precompensation of Gain Nonuniformity in a Nd:Glass Amplifier Using a Programmable Beam-Shaping System
- A New Neutron Time-of-Flight Detector for Fuel-Areal-Density Measurements on OMEGA
- Gigabar Spherical Shock Generation on the OMEGA Laser
- Direct-Drive–Ignition Designs with Mid-Z Ablators
- Channeling Multikilojoule High-Intensity Laser Beams in an Inhomogeneous Plasma
- Dependence of Tritium Release on Temperature and Water Vapor from Stainless Steel
- The Sixth Omega Laser Facility Users Group Workshop
- LLE's Summer High School Research Program
- FY14 Laser Facility Report
- National Laser Users' Facility and External Users' Programs
- Publications and Conference Presentations