LLE Annual Report

2018

Annual Report 2018

The fiscal year ending September 2018 (FY18) concluded the (March 2013 to September 2018) Cooperative Agreement DE-NA0001944 with the U.S. Department of Energy (DOE). The Laboratory is currently supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-NA0003856, the New York tate Energy Research Development Authority, and other agencies. This annual report summarizes work carried out under the Cooperative Agreement at the Laboratory for Laser Energetics (LLE) during the past fiscal year (FY18) including work on the Inertial Confinement Fusion (ICF) and High-Energy-Density (HED) science 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), the Laboratory Basic Science (LBS) Program, and other external users; and programs focusing on the education of high school, undergraduate, and graduate students. Of particular note during this past year was the award of the 2018 Nobel Prize in Physics to Donna Strickland and Gérard Mourou for their invention of chirped-pulse amplification (CPA) while working at LLE in the 1980s. CPA revolutionized laser science enabling amplification of ultrashort pulses by more than five orders of magnitude. This breakthrough is the basis of all modern ultrahigh-power laser systems including OMEGA EP, Lawrence Livermore National Laboratory's (LLNL's) National Ignition Facility (NIF) Advanced Radiographic Capability (ARC) laser, the Extreme Light Infrastructure in Europe as well as thousands of small-scale pulse-compressed lasers in industrial and other applications. Donna Strickland was a graduate student at the University of Rochester's Institute of Optics at that time and Gérard Mourou had a joint appointment as Senior Scientist at LLE and a member of the faculty at The Institute of Optics. Strickland is only the third woman in history to receive the Noble Prize in Physics, joining Marie Curie (1903) and Maria Goeppert–Mayer (1963) and the only one educated in the United States. The Strickland and Mourou work of the 1980s was funded principally by the Cooperative Agreement with the DOE Office of Inertial Fusion active at that time.

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 NIF. This program uses the Omega and NIF Laser Facilities and the full experimental, theoretical, computational, and engineering resources of the Laboratory. During FY18, 2319 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 2319 target shots, 71.1% were designated for the ICF and HED Campaigns. LLE is the lead laboratory worldwide for the laser-direct-drive approach with research focused on cryogenic implosions on the 60-beam OMEGA laser and on laser–plasma interaction physics of importance to all laser-driven concepts at both the Omega and NIF facilities. 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 Laser Systems.

An important result published just as this report was going to print [V. Gopalaswamy et al., Nature 565, 581 (2019) describes work on a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium–tritium targets carried out on the 30-kJ OMEGA Laser System, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When hydrodynamically scaled to the laser energies of the NIF (1.9 MJ), these targets are predicted to produce a fusion energy output of +500 kJ. This approach exploits the large database of OMEGA, and "machine learning" will guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.

High-Energy-Density Science
During FY18, several HED science campaigns were conducted at the Omega Laser Facility. Most of these were carried out by LLNL, Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and LLE scientists working under the HED Campaign and summaries are reported in National Laser Users' Facility and the External Users' Programs (p. 211). Some of the fundamental science HED physics experiments are carried out under the NLUF and LBS programs and are reported in high-impact journals such as Nature and Science (see Publications, p. 289).

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 FY18, this work included collaborative work with LLNL on the development of fifth-harmonic generation of a pulsed Nd:YLF laser in a cascade of nonlinear crystals with a demonstrated record efficiency of 30% (p. 12), detailed investigations of the effects of grating compressor misalignment in a CPA laser system (p. 143), development of a new rate-doubled, 10-GHz fiducial comb generator for precision optical timing calibration applications (p. 154), and the identification of three different types of damage-site morphology that capture thermomechanical signatures of the energy-release mechanism of laser-heated material under different damage-initiation conditions (p. 160).

Omega Laser Facility Users Group
The Tenth Omega Laser Facility Users Group (OLUG) Workshop was held at LLE on 25-27 April 2018. It was attended by 130 researchers, including scientists, postdoctoral fellows (postdocs), and students (Fig. 156.38, p. 199). The attendees represented institutions from five countries, including the U.S., Canada, U.K., France, and Israel. As has been the case for previous workshops, postdocs and students received travel support to attend the workshop from DOE's National Nuclear Security Administration (NNSA). The Workshop included the presentations of invited talks highlighting four recent science experiments conducted at the Omega Laser Facility, a talk via web conferencing on the NNSA perspective by Acting ICF Program Director Dr. Njema Frazier, facility update and progress on OLUG Recommendations, facility tutorials on Optical Diagnostics at OMEGA, panel discussions on OLUG Findings and Recommendations, young researcher panel discussions, and three poster sessions comprising a total of 81 posters of which 63 were presented by graduate students, postdocs, and undergraduate students.

Education
As the largest funded 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 2018, 13 students from Rochester-area high schools participated in the LLE's Summer High School Research Program. This marks the 30th year of the program, which started in 1989. The goal of the program is to motivate 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 seventy-seven high school students have now participated in the program. Two of this year's program participants, Maia Raynor and Anirudh Sharma, were named Scholars in the prestigious Regeneron Science Talent Search for research projects they carried out at LLE. A total of 38 students from the LLE program have now become Scholars since the program's inception in 1989.

Approximately 40 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.

Graduate students are using the Omega Laser Facility as well as other LLE facilities for fusion and HED physics research and technology development activities (see Table I, p. viii-xiv). 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 FY18, a total of 72 graduate students were involved in research projects at LLE. LLE directly sponsored 39 students pursuing Ph.D. degrees via the NNSA-supported Frank Horton Fellowship Program (Table I, p. viii-xiv). LLE also directly funds research programs within the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center, the University of Michigan, the University of Nevada at Reno, and the State University of New York (SUNY) at Geneseo. These programs involve a total of approximately 10 graduate students, 29 undergraduate students, 2 postdoctoral students, and 8 faculty members. In addition, LLE supports one Oxford University graduate student. A total of 362 graduate students have now conducted their research work at LLE since the program began.

In addition, 182 graduate students and post-graduate fellows from other universities have conducted research at the Omega Laser Facility as part of the NLUF and LBS programs. Thirty-four graduate students (Table 156.VIII, p. 213) were involved in NLUF research programs in FY18.

FY18 Omega Laser Facility Operations
During FY18, the Omega Laser Facility conducted 1441 target shots on OMEGA and 878 target shots on OMEGA EP for a total of 2319 target shots (see Tables 156.V and 156.VI, p. 209). OMEGA averaged 12 target shots per operating day with 95.0% Experimental Availability (EA) and 96.5% Experimental Effectiveness (EE).

OMEGA EP was operated extensively in FY18 for a variety of user experiments. A total of 833 target shots were taken into the OMEGA EP target chamber and 45 joint target shots were taken into the OMEGA target chamber. OMEGA EP averaged 8.3 target shots per operating day with 95.8% EA and 96.3% EE.

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)/University of Bordeaux, Rutherford Appleton Laboratory/York University (RAL/York), and ARPA-E (Advanced Research Projects Agency-Energy) programs (see Figs. 6 and 7, p. xv). The ICF and HED programs received 71.15% of the facility shots in FY18.

National Laser Users' Facility and External Users Programs
The Fundamental Science Campaigns accounted for 24.3% of the Omega Laser Facility target shots taken in FY18. Nearly 60% of these shots were dedicated experiments led by U.S. academia and businesses 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 LLE.

The Omega Laser Facility was also used for several campaigns led by teams from CEA of France, the University of Bordeaux of France, and the joint RAL/York of the United Kingdom. These externally funded experiments are conducted at the facility on the basis of special agreements put in place by UR/LLE and participating institutions with the endorsement of DOE/NNSA.

The facility users during this year included 13 collaborative teams participating in the NLUF Program; 15 teams led by LLNL, LANL, and LLE scientists participating in the LBS Program; many collaborative teams from the national laboratories and LLE conducting ICF experiments; investigators from LLNL, LANL, and LLE conducting experiments for HED physics programs; and scientists and engineers from CEA, the University of Bordeaux, and RAL/York.

A total of 293 target shots were taken for NLUF projects during FY18. Summaries of the FY18 NLUF experiments are presented beginning on p. 211.

A critical part of the NLUF Program is the education and training of graduate students in HED and plasma physics. During the year, 34 graduate students from ten universities participated in experiments conducted under the NLUF Program at the Omega Laser Facility (Table 156.VIII, p. 213). Ten graduate students trained under the Omega Science Program (NLUF and LBS) successfully defended their Ph.D. theses in 2017/2018 (Table 156.IX, p. 214).

Fifteen LBS projects previously approved were allocated Omega Laser Facility shot time and conducted a total of 231 target shots in FY18 (see Table 156.X, p. 231). Summaries of the FY18 LBS experiments are presented beginning on p. 231.

In FY18, LLNL's HED Physics and Indirect-Drive ICF (ICF-ID) Programs conducted numerous campaigns on the OMEGA and OMEGA EP Laser Systems. This was the 20th year of national laboratory collaborative experiments at Omega since the Nova Laser at LLNL shut down in 1999, building upon prior collaborations. Overall, these LLNL programs led 465 target shots, with 283 shots using only the OMEGA laser, 172 shots using only the OMEGA EP laser, and 10 shots using both lasers jointly. Approximately 28% of the total number of shots (60 OMEGA shots and 71 OMEGA EP shots) supported the ICF-ID Campaign. The remaining 72% (223 OMEGA-only shots, 101 OMEGA EP-only shots, and 10 joint shots) were dedicated to experiments for HED physics. Highlights of the various HED and ICF-ID Campaigns are summarized beginning on p. 246. In addition to these experiments, LLNL Principal Investigators led a variety of LBS program experiments. In total, LLNL scientists led 603 target shots at the Omega facility in FY18. Summaries of the LLNL experiments begin on p. 246.

In FY18, Los Alamos National Laboratory carried out 21 shot days with a total of 239 target shots on the OMEGA and OMEGA EP Laser Systems in the areas of HED science and ICF. The focus areas were on radiation flow, hydrodynamic turbulent mix and burn, and coupled Kelvin-Helmholtz (KH)/Richtmyer-Meshkov (RM) instability growth including convergent geometry. Several shot days also focused on transport properties in the kinetic regime as neutron imaging and performed tests of a new imaging concept to be installed on the NIF. Experiments were executed in support of the double-shell campaign, and initial experiments were started using the new Revolver triple-shell design platform. Summaries of the LANL experiments begin on p. 275.

During FY18, the Naval Research Laboratory in collaboration with LLE executed two shot days on OMEGA EP. Using an x-ray prepulse, the OMEGA EP experiments determined the minimum high-Z coating thickness (300 Å Pd) as well as the minimum expansion time (6 ns) needed for laser imprint reduction (Fig. 156.167, p. 285).

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