The National Nuclear Security Administration (NNSA) and the DOE Office of Science (SC) have reported on the outcomes of the May 10-12 scientific workshop in Washington, DC, on the use of NIF for fundamental science research over the coming decade.The workshop reviewed NIF's capabilities and operational experience, plans for future diagnostics and targets, and the current state of science in key areas that NIF could potentially impact.
The NNSA/SC report, issued on November 8, identifies scientific challenges and research directions in laboratory astrophysics, nuclear physics, materials in extremes and planetary physics, and beam and plasma physics that NIF's unique capabilities can address. When taken together with considerations of user science processes and capability gaps, it defines a set of priority directions to meet these challenges on the time scale of a decade.
"The next decade holds bright promise for rapid progress in scientific discovery through the appropriate utilization and continued development of NIF," said Don Cook, NNSA's Deputy Administrator for Defense Programs. "The outcome of the workshop supports the fact that NIF enables fundamental science investigations using unique extreme laboratory environmental conditions in addition to NIF's primary role in preserving the safety, security and reliability of the nuclear stockpile without underground testing."
"We're proud of this cooperative effort with our colleagues in NNSA," said Dr. William F. Brinkman, director of the Office of Science. "This report, which draws on the insights of experts from a wide range of fields, represents an important first step toward identifying the unique scientific opportunities presented by NIF." Click here to read the report.
The workshop was co-chaired by John Sarrao of Los Alamos National Laboratory, Michael Wiescher of the University of Notre Dame, and Kim Budil of LLNL.
The National Nuclear Security Administration has agreed to provide support for students and postdocs not employed by LLNL who are interested in attending the NIF User Group meeting planned for February 12 to 15 at the Laboratory. Interested applicants can apply here; the application deadline is January 6, 2012.
The meeting will describe NIF's capabilities and will include presentations on NIF experiments and related research at other facilities. More information on the meeting is available here. The deadline for foreign nationals to register for the meeting is December 13; U.S. citizens must register by January 13, 2012.
The first infrared (1,053-nanometer) laser light was created in the NIF master oscillator room (MOR) on October 29, 2001. This marked the end of almost a decade of work bringing the fiber laser system design to maturity and months of producing laser light in an off-line facility in Bldg. 381.
Laser pulses for all of NIF's experiments begin in the MOR, where a fiber oscillator and an acousto-optic modulator generate a single-frequency infrared laser pulse. The pulse is then launched into an optical fiber system that amplifies and splits it into 48 separate fibers and carries it to low-voltage modulators where it is shaped for the desired experiment. From there, the fibers take it to a preamplifier module where the pulse is increased to about 10 joules, then on to the 192-beam main laser system.
In 10 years, the NIF MOR has been dramatically transformed from a single-color, single-output laser to a fully deployed fusion laser front-end that operates 24/7 and has generated more than 300 billion precision pulses to support ignition target experiments. Three separate oscillator systems that are tunable in wavelength drive the outer and inner 23-degree and 30-degree cones of beamlines that enter the top and bottom of the hohlraum at the center of the Target Chamber. This tunability provides improved power balance and allows the target drive symmetry to be optimized.
LLNL's Steve MacLaren has received the National Nuclear Security Administration (NNSA) Defense Programs Employee of the Quarter Award in recognition of his role as lead designer in the recently completed high-energy-density (HED) experiments on both NIF and the Z Machine at Sandia National Laboratories. "The leadership and achievements of the award recipients have contributed directly to the many successes that NNSA Defense Programs has recently enjoyed," said Don Cook.
MacLaren is a physicist in the Weapons and Complex Integration Directorate. The award recognizes the successful application of LLNL's massively parallel simulation capability to recent NIF experimental results to validate a physics-based model important to stockpile stewardship.
MacLaren received a B.S. in physics from the U. S. Naval Academy in 1990 and his Ph.D. in physics from UC Berkeley in 2000, joining LLNL the same year. In 2009 he led a team of scientists that received the NNSA Defense Programs Award of Excellence for the first successful stockpile stewardship-relevant experiments at NIF.
A 3D animated ride through the NIF beamlines and demonstrations of laser light on the Jumbotron scoreboard were featured attractions at the November 6 Science Discovery Days at AT&T Park in San Francisco.
The beamline ride was part of the LLNL exhibit on the park's infield that also included an interactive electronic climate simulation, science challenge games, and the Laboratory's popular "Fun with Science" show. The Jumbotron presentation, in which NIF Director Ed Moses demonstrated the difference between diffuse light and laser light, was shown hourly.
Discovery Days at AT&T Park, which drew more than 21,000 visitors, was the climax of the first annual Bay Area Science Festival, which brought together scientific and educational institutions from throughout the region to produce one of the largest science-based events ever held in the United States. The festival ran from October 29 to November 6 and featured more than 100 fun, interactive science and technology events.
The record ramp-compression equation-of-state (EOS) experiments conducted on NIF earlier this year and progress on the National Ignition Campaign were highlighted in invited presentations at the 53rd Annual Meeting of the APS Division of Plasma Physics (APS/DPP), held November 14-18.
LLNL physicist Ray Smith presented the results of the EOS experiments, in which diamond samples were gradually compressed to a record pressure of 50 megabars (50 million times Earth's atmospheric pressure). Smith said that by replicating the conditions believed to exist in the cores of several recently discovered "super-Earths," the experiments could provide clues to the formation and structure of these and other giant planets, as well as the exotic behavior of materials at ultrahigh densities.
The team of scientists from UC Berkeley, Princeton University, and LLNL used a carefully shaped 20-nanosecond, 750-kilojoule laser pulse from 176 NIF beams to ramp-compress multiple thicknesses of diamond to more than six times the pressure previously achieved in similar experiments by the same team at the University of Rochester's OMEGA laser. For more information, see the March 2011 Photons & Fusion Newsletter.
The Target Alignment Sensor (TAS) alignment station has been moved to a new alignment lab in the Operations Support Building (OSB), the former Diagnostics Building, in Bldg. 581. The alignment station simulates Target Chamber alignment beams, target and TAS positioning mechanisms, and the Target Chamber's alignment coordinate system.
The TAS is used to align NIF's laser beams to targets. To perform this function, four different optical systems on the TAS are aligned within a few microns to the same point in space. The task is complicated by the requirement that alignment beams must not strike the target directly.
To prevent that and still be able to align beams to the target, TAS uses mirrors to reflect alignment beams and create a "virtual image" of alignment beams incident on the target. The new alignment station provides ready access for TAS optics, while executing all the essential elements of NIF beam alignment to a target. To date, the station has been used to build and align two TAS units used in NIF, with two more under way.
The station's move into the combined TAS/FODI (Final Optics Damage Inspection system) alignment lab, now in its final stages, was made to allow for alignment of both the TAS and FODI units after they have been contaminated during high-neutron-yield experiments.
Laser-target interaction experiments relevant to directed-energy (DE) weapons design and applications require the use of high-power, complex and costly lasers that are typically unique devices, operated in dedicated facilities that don't easily permit controlled laboratory experiments on realistic targets—for example, those containing energetic materials.
Photon Science and Applications (PS&A) researchers, however, have recently shown that high-power diode laser arrays can deliver the necessary irradiance levels at the short ranges required for laboratory experiments to characterize laser-material interactions. Such arrays are capable of delivering irradiance characteristic of DE weapon requirements, are self-contained, compact, lightweight, relatively inexpensive and easily transportable to special facilities such as explosive contained-firing, wind tunnel or space environment simulation.
At the 14th Annual Directed Energy Symposium, held November 14 to18, PS&A researcher Alexander Rubenchik presented a paper on laser-material interaction experiments conducted under a Laboratory Directed Research and Development project that used a kilowatt-class diode-laser array to simulate a DE weapon-class laser. The laser system, built by Vernon Kanz, combines and homogenizes radiation from multiple bars of a diode array using a holographic optic and solid waveguide to deliver 10 percent uniform irradiation to the target. The simulator was used to characterize the thermal response of aluminum, titanium and steel.
Contributing to the presentation were Ray Beach, Vernon Kanz, Howard Lowdermilk, Mark Rotter, Craig Siders, and Sheldon Wu.
The NIF & Photon Science Directorate honored George Miller and his 40 years of dedicated service to the Directorate, LLNL and the nation with an ice cream social on November 30. Miller stepped down as the Laboratory’s 10th director on December 1.
NIF Director Ed Moses said Miller will be remembered as one of the greatest leaders of LLNL—an "MVP of Directors"—and Chief Scientist John Lindl and Chief Technologist Mary Spaeth praised Miller's contributions to the development of the Laboratory's laser program and the success of NIF. Miller in turn commended the ability of LLNL and NIF&PS staff to "take on challenges that most of the world say are impossible—and more often than not, you succeed. My hope is that you continue to do what nobody else in the world can do. When you get ignition I won't be far away, and I will be celebrating with you."
NIF&PS Chief Technology Officer Chris Barty presented an invited talk describing the use of mono-energetic gamma-ray (MEGa-ray) sources in nuclear photonics on November 17 at the International Light at Extreme Intensities (ILEI) 2011 conference. The talk was part of a full-day session devoted to nuclear photonics.
In a separate talk, Barty discussed the development of the Advanced Radiographic Capability (ARC) petawatt (PW) laser on NIF and the evolution of high-average-power laser activities at LLNL that can be leveraged to create new pump lasers for future high-repetition-rate PW lasers. An example, he said, is the E23 laser, which when constructed will fire ten shots per second and be capable of diffraction-limited beam quality by continuously correcting for beam distortions in the amplification chain using high-resolution adaptive optics.
Barty said the Laboratory has begun development of plans for E23 and formulated a path forward to completion pending funding. With a diffraction limited PW output, he said, "it is possible reach focused intensities of more than 1023 watts per square centimeter (W/cm2). Present PW lasers have not exceeded focal intensities of 1021 W/cm2. This is because they are single shot lasers and adaptive beam correction is not practical."
Twenty-one participants attended a Missile Defense Agency (MDA) Federally Funded Research and Development Center (FFDRC) / University Affiliated Research Center (UARC) "Home Visit" to NIF on November 9. The visitors represented MDA, Sandia National Laboratories, MITRE Corporation, Georgia Technical Research Institute, MIT Lincoln Laboratory, The Aerospace Corporation, and LLNL.
The Home Visit is an annual one-day overview of LLNL capabilities that support the MDA mission space. This year's visit focused on third-generation munitions, high performance computing, directed-energy weapon technologies, advanced simulations of missile intercepts, predictive lethality modeling, and x-ray survivability experiments on NIF.
Photon Science and Applications Program Director Gina Bonanno was the technical point of contact for the visit. Gina also serves as the LLNL FFRDC Captain, providing an interface for cooperative capability opportunities with the MDA and other FFRDCs.
The NIF Beampath Team has received a Jacobs Engineering Group, Inc., 2011 President's "BeyondZero" safety excellence award. Craig Martin, the company's president and chief executive officer, said the award winners "demonstrated a real commitment toward BeyondZero (the company's safety program) and the safekeeping of our co-workers by incorporating all aspects of BeyondZero into their projects and daily activities. These projects and offices achieved world class leadership and performance and exemplify the very best of Jacobs' safety culture. They deserve our thanks and congratulations."