Supporting the Scientific Base for Competencies Essential to Sandia Missions
The DOE Office of Science (SC) is the single largest supporter of basic research in the physical sciences in the U.S., providing more than 40 percent of total funding in this area. Sandia has active research programs funded by:
Advances environmental and biomedical knowledge that promotes national security through improved energy production, development, and use; international scientific leadership that underpins the nation’s technological advances; and research that improves the quality of life for all Americans.
Supports world-class, high-performance computing and networking infrastructures as well as supporting fundamental research in mathematical and computational sciences to enable researchers in DOE scientific disciplines to analyze and predict complex phenomena for scientific discovery.
ARPA-E is an innovative and collaborative government agency that brings together America’s best and brightest scientists, engineers, and entrepreneurs.
The focus of Sandia’s ARPA-E program is to establish partnerships with universities, industry and other National Labs to create innovative energy solutions for the Nation through both maturation of industry capabilities and commercialization of our technologies.
Address Stationary and Transportation Energy pillars
Leverage differentiating facilities/capabilities and Research Foundations of Sandia Labs
As part of Sandia’s core geochemistry program funded by DOE Office of Basic Energy Sciences (BES), Sandia’s Randall Cygan (in Sandia’s Geoscience Research and Applications Dept.) and his collaborators, W. Crawford Elliott and his PhD student Laura Zaunbrecher from Georgia State University, have been examining the adsorption mechanisms of metal cations onto soils and sediments. This effort is especially important for the environmental treatment of chemical and radioactive contaminants, including the fission product cesium-137—which is a significant contaminant at the Savannah River Site in South Carolina and in the region near the disabled Fukushima reactors in Japan. The article describing their work, “Molecular models of cesium and rubidium adsorption on weathered micaceous minerals,” was chosen by the editors of Journal of Physical Chemistry A to be the cover feature of the June 4, 2015, issue.
Equilibrated molecular structure of interlayer Cs+ (yellow), Rb+ (purple), and K+ (blue) in mica-vermiculite hybrid structure (HIV-mica wedge model) as derived from molecular dynamics. Frayed edges are represented by wedge zone in periodic structure. Wedge, vermiculite, and mica zones are indicated for the lower left section of the simulation cell.
Mechanism-based adsorption models for the long-term interaction of chemical and radionuclide species with clay minerals are needed to improve the accuracy of groundwater reaction and flow models, and related simulations for performance assessment of waste sites and repositories. The nanoscale nature of clay minerals often limits their characterization by traditional analytical methods. Therefore, molecular simulation using geometry-optimization and molecular-dynamics methods have been used to investigate the adsorption behavior of Cs+ and Rb+ cations at frayed-edge wedges (a proxy for frayed-edge sites) and in the interlayer region formed as a result of the transformation of muscovite to interlayered vermiculite during weathering and soil formation/development. Our results indicate that Cs+ binds more strongly than Rb+ in the vermiculite interlayer, while Rb+ binds more strongly than Cs+ in the vermiculite-mica wedge region. This is the first study to explore the detailed structure and energetics of molecular binding mechanisms at important wedge sites associated with soils and sediments.
Ultimately, these models and results will guide further determination of adsorption capacities associated with complex natural materials, especially those that can impact the attenuation and sequestration of radioactive contaminants in the environment. This work is also critical to performance assessment research activities sponsored by US Nuclear Regulatory Commission in their evaluation of the suitability of nuclear materials storage and disposal.
Sandia and the Laboratory for Laser Energetics (LLE) at the University of Rochester will investigate the compression and heating of high energy-density, magnetized plasmas at fusion-relevant magneto-inertial [confinement] fusion (MIF) conditions, building on the recent Magnetized Liner Inertial Fusion (MagLIF) concept successes. The SNL-LLE team will conduct focused experiments based on the MagLIF approach at both SNL and LLE facilities, targeting key physics challenges in the intermediate plasma density regime. The team will also exploit and enhance a suite of simulation and numerical design tools validated by these experiments. Through this project, the team will provide critical information for improved compression and heating performance as well as insights on loss mechanisms and instabilities for hot, dense, magnetized plasmas. This information will help accelerate MagLIF concept development, and will also inform the continued development of intermediate-density approaches across the DOE’s Advanced Research Projects Agency–Energy (ARPA-E) ALPHA (Accelerating Low-cost Plasma Heating and Assembly) program portfolio.
ARPA-E’s ALPHA program funds developing the tools to build foundations for new pathways toward fusion power. ALPHA is focused on approaches that exploit magnetic fields to reduce energy losses in the intermediate-ion-density regime between lower-density magnetic-confinement fusion (MCF) and higher-density inertial-confinement fusion (ICF). This intermediate-density regime is not as well explored as the more mature MCF and ICF approaches, and it may offer new opportunities for more attractive fusion reactors with energy and power requirements that are compatible with low-cost technologies.
Illustration of the stages of the MagLIF concept on Z. The target is a metal cylinder ~1 cm tall containing fusion fuel. The target is axially magnetized using magnetic field coils (not shown). The Z machine applies a current along the axial direction, which creates an azimuthal magnetic field outside the liner and the resulting magnetic pressure compresses the liner. Early in the implosion, a multi-kJ laser pulse from the Z-Beamlet laser is coupled to the fuel through a thin plastic window on one end. This energy is homogenized over the several tens of nanoseconds it takes to compress the fuel.
As shown in the figure (right), MagLIF is an innovative MIF concept that exploits advances in pulsed-power technology. A MagLIF target is magnetized with an axial field of up to 30 tesla (~60,000 times greater than the Earth’s magnetic field) before the shot. The target is imploded using a 20 million ampere, 100 nanosecond current from the Z pulsed-power accelerator. The liner rapidly becomes plasma. Just as the liner’s inner surface begins to move, the multiple-kilojoule, 1 terawatt, 0.53 mm Z-Beamlet laser is used to heat the deuterium gas.
The axial magnetic field suppresses electron heat transport from the hot fuel to the cold liner wall—enabling electron-ion equilibration and allowing a quasi-adiabatic compression to fusion temperatures (>50 million Kelvin) and fuel pressures of approximately gigabars (~5 billion times atmospheric pressure). The embedded axial magnetic field is compressed to ~13 kilotesla. Target designs on the Z facility are predicted to reach fusion yields that approach and exceed the driver energy invested in the fuel if equimolar deuterium-tritium (DT) fuel is used. In these designs, the fuel is compressed radially by ~25–30 times before the fuel’s plasma pressure stops the implosion (the point of ‘stagnation’). At stagnation, the charged-particle products (alpha particles for DT reactions or 1 MeV tritons for deuterium-deuterium [DD] reactions) are magnetized, meaning that their gyro radii are less than the final fuel radius resulting in their confinement in the plasma.
MIF has long been discussed as a promising fusion approach using plasma densities between those of MCF (~1014 ions and electrons per cubic centimeter) and traditional ICF (>1025 ions and electrons per cubic centimeter), but there remains a paucity of experimental data quantitatively compared to state-of-the-art simulations validating MIF, particularly in fusing plasmas. In late 2013, experiments began on the Z pulsed-power facility studying MagLIF targets. These experiments showed that a 70 kilometers per second cylindrical liner implosion compressing laser-heated and axially magnetized deuterium gas could produce a final ion temperature of up to about 44 million Kelvin and up to 2 × 1012 thermonuclear DD neutrons. In addition, >1010 secondary DT neutrons were observed, which is only possible with significant fuel magnetization. By reducing electron thermal conduction losses and magnetizing the ions, MagLIF relaxes the constraints on traditional inertial fusion designs (final fuel pressure, areal density, convergence, driver power, and intensity).
OMEGA (left) stands 10 meters tall and is approximately 100 meters in length. This system delivers pulses of laser energy to targets in order to measure the resulting nuclear and fluid dynamic events. In this target chamber (center), OMEGA’s 60 laser beams focus up to 40,000 joules of energy onto a target (right) that measures less than 1 millimeter in diameter in approximately one billionth of a second.
It is predicted that yields two orders of magnitude larger are possible on Z using deuterium fuel within the next three years. If equimolar DT were to be used for the fusion fuel instead of pure deuterium, simulations suggest the fusion yields could exceed the total amount of energy delivered to the fuel (fuel gain > 1). Such an achievement—modeled and understood—would clearly demonstrate MIF’s credibility as an ICF/MCF alternative. A key challenge is the Z facility’s relatively low shot rate. Our research will greatly increase MagLIF rate of progress by conducting many more experiments per year on Sandia’s Z-Beamlet laser and the University of Rochester’s OMEGA (shown in the figure above) and OMEGA-EP lasers. Our experiments will target key physics challenges such as laser preheating and fuel magnetization. We will also conduct fully integrated, scaled-down experiments of the MagLIF concept on LLE’s OMEGA facility. Testing MagLIF on OMEGA and leveraging NNSA-funded research on Z will demonstrate key MIF tools on multiple facilities at significantly different energy, time, and spatial scales. Another key project goal is to use state-of-the-art simulations and numerical design tools, tested by these experiments, to validate and improve fusion-target design parameters for magnetized plasmas.
ARPA-E funding is $3.8M over two years. At this point, negotiations are underway to reconcile the elements of Sandia and LLE ’s originally proposed research program to the scope of the ARPA-E funding award.
Pavel Bochev, a Sandia computational mathematician has won the Department of Energy’s Ernest Orlando Lawrence Award for his work. (Photo by Randy Montoya)
Pavel Bochev (in Sandia’s Computational Mathematics Dept.) has received an EO Lawrence Award for his pioneering theoretical and practical advances in numerical methods for partial differential equations. “This is the most prestigious mid-career honor that the DOE awards,” said Bruce Hendrickson, director of Sandia’s computing research center. Bochev’s work was cited for “invention, analysis, and applications of new algorithms, as well as the mathematical models to which they apply.” in the category Computer, Information, and Knowledge Sciences. Said Bochev, “I’m deeply honored to receive this award, which is a testament to the exceptional research opportunities Sandia and DOE provide.
Lawrence Award recipients in nine categories of science each will receive a medal and a $20,000 honorarium at a ceremony in Washington, D.C., later this year. The EO Lawrence Award was established to honor the memory of Ernest Orlando Lawrence, who invented the cyclotron—an accelerator of subatomic particles—and received a 1939 Nobel Prize in physics for that achievement. Lawrence later played a leading role in establishing the U.S. system of national laboratories.
Said Secretary Moniz, “I congratulate the winners, thank them for their work on behalf of the department and the nation, and look forward to their continued excellent achievement.”
Sandia was recently awarded DOE Advanced Scientific Computing Research (ASCR) funding to develop a framework for in situ data management, analysis, and visualization. Sandia’s approach provides a mechanism for specifying the structure and use of data, decouples code specification from optimization, and facilitates the expression of complex scientific workflows—thereby enabling scientists to develop high-performance, portable codes at extreme-scale.
Sandia Combustion Research Facility (CRF) scientist Christopher Kliewer (in Sandia’s Combustion Chemistry Dept.) won a DOE Office of Science (SC) Early Career Research Program award to develop new optical diagnostics to study interfacial combustion interactions that are major sources of pollution and vehicle inefficiency. The funding opportunity for researchers in universities and DOE national laboratories, now in its sixth year, supports outstanding scientists early in their careers in developing individual research programs and stimulates research careers in the disciplines supported by DOE-SC.
Kliewer’s winning research proposal
“Interactions between Surface Chemistry and Gas-Phase Combustion: New Optical Tools for Probing Flame-Wall Interactions and the Heterogeneous Chemistry of Soot Growth and Oxidation in Flames”
examines the complex surface chemistry involved when gas-phase combustion interacts with solid/liquid interfaces. “I’m interested in interfacial combustion phenomena, like when a flame interacts with a wall. These heterogeneous processes dominate some of the most stubborn and technologically critical problems in combustion, yet they are not well understood,” said Kliewer. “This is due in part to the lack of experimental approaches capable of probing locations very close to an interface, especially in the hostile environment of combustion.”
CRF optical diagnostics researcher Christopher Kliewer has won a Department of Energy Early Career Research award that will fund the development of new tools for studying interfacial combustion interactions. These interactions are major sources of pollution and vehicle inefficiency. (Photo by Dino Vournas)
In engine and power generator combustors, flames interact with metal walls during the combustion process. These interactions produce pollutants, such as unburned hydrocarbon and particulate emissions, and cause aging and failure in engines and generators. Kliewer’s project will develop a new nonlinear optical surface scattering technique to capture the dynamic chemistry of the flame-wall interactions.
This tool will be further developed to correct a deficit in existing experimental techniques for studying soot particles collected from flames. Nearly all of these techniques require ex situ analysis, meaning a sample must be removed from the flame to be studied. The act of removing the soot changes both the sample and the surrounding combustion, limiting the accuracy of results.
Kliewer is one of 44 winners of the Early Career Research Program award. Since joining Sandia in 2009, he has received two distinguished paper awards from the Combustion Institute for articles presented in optical diagnostics at the 2010 and 2014 International Symposium on Combustion. His paper on 2D-CARS, coauthored with Sandia researcher Alexis Bohlin (also in Sandia’s Combustion Chemistry Dept.), was the most read paper in the Journal of Chemical Physics for June 2013. He has a doctorate in physical chemistry from the University of California, Berkeley, and a bachelor’s degree in chemistry from George Fox University in Newberg, Oregon.