2017 Annual Report
The fiscal year ending September 2017 (FY17) concluded the first 54 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) and High-Energy-Density (HED) Campaigns; laser, optical materials, and advanced technology development; operation of the Omega Laser Facility for the ICF and HED Campaigns, the National Laser Users’ Facility (NLUF) and Laboratory Basic Science (LBS) programs, 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 at the National Ignition Facility (NIF). This program uses the Omega Laser and NIF facilities and the full experimental, theoretical, and engineering resources of the Laboratory. During FY17, 2138 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). Of the facility’s 2138 target shots, 72% were designated for ICF and HED campaigns.
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 direct-drive ignition. LLE has also developed, tested, and constructed a number of diagnostics currently being used at both the Omega Laser Facility and on 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 and advanced ignition concepts; and development of diagnostics for experiments on the NIF, OMEGA, and OMEGA EP lasers. A significant portion of the cryogenic capsule implosion campaign in FY17 was dedicated to the 1-D implosion campaign used to develop a predictive model for direct-drive cryogenic implosions. The model includes a statistical mapping of the experimental results onto a simulation database of high-adiabat implosions (α ~ 5) having convergence ratios of ~11 to 13. The nonlinear regression formula from the mapping is used to bridge the gap between experiments and simulations. Using this approach, neutron yields in this cryogenic capsule campaign have exceeded 1014 neutrons and areal densities have exceeded 100 mg/cm2. In addition to many other diagnostic development projects, during FY17, LLE installed and operated the single-line-of-sight time-resolved x-ray imager (TRXI) on OMEGA. TRXI was the result of a collaboration among General Atomics, Lawrence Livermore (LLNL), LLE, and Sandia National Laboratories (SNL). The instrument was used on cryogenic capsule experiments and provided high-resolution (~10-µm spatial, ~40-ps temporal) imaging of highly compressed DT implosion cores. This enhanced imaging system will deliver significantly higher resolution than previously available, advancing stockpile stewardship diagnostics for ICF facilities throughout the Nuclear Security Enterprise.
During FY17, several high-energy-density science campaigns were conducted at the Omega Laser Facility including: measurements of the sound velocity and Grüneisen parameter in CH shocked to 800 GPa, equation-of-state measurements of CO2 precompressed to 1.2 GPa and shock compressed to 980 GPa, the solid hP4 phase of Na was observed at ~320 GPa, Hugoniot measurements were conducted of Si shock compressed to 21 Mbar, a new high-pressure solid phase of dynamically compressed Al was observed, and, in collaboration with Harvard University, the optical reflectance of dense hydrogen was measured as a function of energy in the 1.4- to 1.7-Mbar region and up to 2500 K. The data are consistent with the metallic hydrogen being a free-electron partially ionized plasma.
Lasers, Optical Materials, and Advanced Technology
One of LLE’s important missions is the development of advanced high-power lasers and optical materials in support of its inertial fusion and HED research programs. In FY17, this work included the development, construction, installation, and activation of a 100-J UV laser and Target Area System for the Dynamic Compression Sector at the Advanced Photon Source located at Argonne National Laboratory near Chicago. This new research facility is operated by Washington State University (WSU) under sponsorship from the National Nuclear Security Administration (NNSA). LLE partnered with Logos Technologies to develop and build the high-energy laser, which is suitable for a broad range of applications.
FY17 Omega Laser Facility Operations
During FY17, the Omega Laser Facility conducted 1353 target shots on OMEGA and 785 target shots on OMEGA EP for a total of 2138 target shots (see Tables 152.IV and 152.V, p. 206). OMEGA averaged 10.7 target shots per operating day with Availability and Experimental Effectiveness averages for FY17 of 95.7% and 94.4%, respectively.
OMEGA EP was operated extensively in FY17 for a variety of internal and external users. A total of 773 target shots were taken in the OMEGA EP target chamber and 12 joint target shots were taken in the OMEGA target chamber. OMEGA EP averaged 8.7 target shots per operating day with Availability and Experimental Effectiveness averages for FY17 of 95.8% and 96.6%, respectively. Per the guidance provided by DOE/NNSA, 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 (CEA), Centre Lasers Intenses et Applications (CELIA), and ARPA-E programs. Approximately 70% of the target shots in FY17 were taken for the ICF and HED programs.
National Laser Users’ Facility and External Users Programs
The Fundamental Science Campaigns accounted for nearly 24% of the Omega Laser Facility target shots taken in FY17. Nearly 62% of these shots were taken for experiments for 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.
The Omega Laser Facility was also used for several campaigns by teams from CEA of France. 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 13 collaborative teams participating in the NLUF Program; 14 teams led by Los Alamos National Laboratory (LANL), LLNL, and LLE scientists participating in the LBS Program; many collaborative teams from the national laboratories [LANL, LLNL, SNL, and Naval Research Laboratory (NRL)] and LLE conducting ICF experiments; investigators from LLNL, LANL, and LLE conducting experiments for high-energy-density–physics programs; and scientists and engineers from CEA and CELIA. Approximately 60% of the facility target shots were provided to external users of the facility.
Omega Laser Facility Users Group
The Ninth Omega Laser Facility Users Group (OLUG) Workshop was held at LLE on 26–28 April 2017. It was attended by 110 researchers, including scientists, postdoctoral fellows, and students. The attendees represented institutions from five nations, including the United States, United Kingdom, France, Spain, and Hungary. The workshop included the presentation of invited talks, a talk on the NNSA perspective by Dr. Njema Frazier of ICF/NNSA, facility tutorials, poster papers, presentations on research at the national laboratories, and panel discussions. A summary of the OLUG Workshop is presented in an article starting on p. 198.
As the only major university participant in the National ICF Program, education continues to be an important mission for LLE. The Laboratory’s education programs cover the range from high school (p. 204) to graduate education.
During the summer of 2017, 11 students from Rochester-area high schools participated in the Laboratory for Laser Energetics’ Summer High School Research Program. The goal of this program is to excite a group of high school students about careers in the areas of science and technology by exposing them to research in a state-of-the-art environment. Three hundred and sixty-four high school students have now participated in the program since it began in 1989. Two of this year’s program participants’, Nikhil Bose and Yujia Yang, were named Science Talent Search “Scholars” in the prestigious Regeneron Science Talent search for the research projects they carried out at LLE. Bose developed a simulation model to explore a novel method of improving the performance of LLE’s OMEGA EP laser and Yang carried out hydrodynamic simulations of a new fusion concept for the NIF. This year’s students were selected from approximately 60 applicants to the program.
Forty undergraduate students participated in work or research projects at LLE this past year. Student projects included 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 go on to pursue a higher degree in the area in which they gained experience at LLE.
Graduate students are using the Omega Laser Facility as well as other LLE facilities for fusion and HED physics research and technology development activities. These students are making significant contributions to LLE’s research program. Twenty-six faculty members from five University of Rochester academic departments collaborate with LLE scientists and engineers. In FY17, 72 graduate students were involved in research projects at LLE, and LLE directly sponsored 47 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. Two of the 2017 LLE Ph.D. graduates are pursuing careers in NNSA programs. Dr. Michelle Gregor is now a post-doctoral fellow at LLNL and Dr. Amanda Davis is an NNSA Graduate Fellow in the NNSA Defense Programs. LLE also 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. These programs involve a total of approximately 6 graduate students, 25 to 30 undergraduate students, and 10 faculty members. Over 340 graduate students have now conducted their graduate research work at LLE since its graduate research program began.
In addition, 170 graduate students and post-graduate fellows from other universities have conducted research at the Omega Laser Facility as part of the NLUF program. Thirty-three graduate students (Table 152.VII, p. 211) and approximately 30 undergraduate students were involved in NLUF research programs in FY17.