Centers

The Advanced Characterization of Metals under Extreme Environments (ACME2) seeks to fundamentally understand high-temperature and fast loading rate responses of metastable microstructures in metallic alloys through novel experimentation and computational tools and unique probes. We will study displacive phase transformations like TRIP, TWIP, and SME/SE in CoCrNi-variant MPEAs, metastable Ti alloys and RMPEAs, ultrafine-scale eutectoid transformation products in TiCu alloys produced by AM, unusual defect structures produced by AM and high pressure and shear processing, and atomic processes like spinodal decomposition and interstitial effects in Ti alloys and RMPEAs and mechanical behaviors under extreme environments. We will perform multiscale computational modeling and build a framework to understand the deformation mechanisms and underlying microstructural changes. And, we will identify important metastable microstructural and defect characteristics that dictate quasi-static to dynamic mechanical response by in-situ/ex-situ characterization and diagnostics. We will perform microstructure and mechanical characterization with distinct capabilities, including in 3D (TriBeam, high-energy diffraction microscopy (HEDM) at Cornell High Energy Synchrotron Source, CHESS), by high-throughput electron microscopy and nanomechanical testing, and with ultrafast optical, x-ray imaging (laboratory and synchrotron at Advanced Photon Source, APS) and diffraction, and/or velocimetry during Kolsky (Split Hopkinson Pressure Bar, SHPB), gas gun, and/or high explosive (HE)-driven testing, including with 800 MeV Proton Radiography (pRad) at LANL, and at temperature and pressure extremes. ACME2 integrates phase transformation theory, materials processing and manufacturing, multiscale materials behavior modeling, and novel characterization, imaging, and detection to provide new alloying-processing-microstructure-properties-performance knowledge and the design of metals and alloys with tuned microstructures, defects, and controlled deformation mechanisms under extremes. The proposed work supports the aims of Topic Research Area #1: Advanced Characterization of Materials Properties under Extreme Environments, where phase transformations and microstructure changes under high strain rates, temperatures, and pressures are paramount.

Thrust 1: The chemical reactivity, electronic structure, and spectroscopic features of plutonium hydride phases are a central concern across several areas of the NNSA. The formation of PuHx from Pu metal is a key component of technologies for the disassembly and conversion of excess plutonium from nuclear weapons. This chemistry is also highly relevant to nuclear forensics; the formation of PuHx can vary widely depending on the precise composition and history of the plutonium metal. Additionally, the phase relationships for PuHx are exceedingly complex with a broad range of stoichiometries (PuH1.9 to almost stoichiometric PuH3) that give rise to remarkable differences in electronic structure. Furthermore, hydride coated plutonium surfaces present significant long-term storage and handling challenges since they catalyze the reaction with oxygen and produce a significant exotherm, which can, in turn, lead to reactions with dinitrogen (if in air). Although the reaction thermochemistry of PuHx has been studied in detail, the spectroscopic and computational analyses of its electronic structure and reactivity are complicated by strong electron correlation which arises from the near degeneracies engendered in these systems. Additionally, diffraction analysis and detailed understanding of hydride positions in PuHx and related materials is complicated by the necessity to employ neutron diffraction – a technique that is particularly problematic for plutonium materials. This research program will address these challenges by breaking down extended solid actinide electronic structure and reactivity into theoretically and spectroscopically more-addressable molecular models. The advantage of this approach is that it provides discreet complexes with well-defined Pu–H composition and structure to develop complementary experimental and theoretical tools for accurate analysis of electronic structure and reactivity of plutonium hydrides under different conditions. In addition, this program will greatly expand the number of known plutonium hydride complexes and apply contemporary characterization techniques including single-crystal X-ray diffraction, multi-nuclear NMR spectroscopy, and ligand K-edge XANES. Thrust 2: In order to develop methodologies for the manufacture of pure targets of americium (especially the short-lived isotopes), a more refined knowledge of the redox chemistry of americium is a prerequisite. A wide range of feedstocks can be considered and improvement of separation methodologies for americium isotopes including 241Am (t1/2 = 432.7 years) from in-growth in aged 239Pu and 243Am (t1/2 = 7380 years) from thermal neutron irradiation of 242Pu can lead to significant technological improvements across the NNSA mission space. Other sources, including spent nuclear fuel, may also be considered and would have more complex feedstock chemistry. Improving these separations for target preparation will require refined knowledge of americium redox processes, the effects of the irradiated host material on the downstream chemistry, and monitoring of the in-growth of decay products during the separation processes. These unique challenges necessitate the direct collaboration of both chemists and engineers to define the fundamental chemical processes and develop novel monitoring techniques to give direct insight to the evolving actinide isotopic mixture (measured by in-line monitoring by multiparticle sensors (neutron/gamma) and its chemical speciation (measured by in-situ IR and Raman spectroscopy) in both batch and preparative scale processes. Thrust 3-Cross Cutting Theory: To better understand the observed structures, reactivity, metal oxidation state, and metal-ligand bonding interactions of the actinide target complexes proposed in the two research goals, electronic structure studies will be required to complement the experimental characterization. Theoretical calculations will also be critical to assign and interpret the spectroscopy and develop robust understanding of the redox behavior of these systems. The proposed chemistries will present several challenges to extant methodologies and these studies will be the basis of critical methodology development to understand the chemistry of the mid-actinides (Np, Pu, and Am). In silico prediction of ligand effects and their impact on the redox properties (nature of the redox events, structural reorganization, magnitude of the redox potentials) will be utilized to tune the properties and guide the experiment to improve the redox characteristics. Orbital composition analyses, electron density partitioning/electron localization algorithms, energy decomposition schemes will be utilized to quantitatively analyze the nature of metal-ligand interactions. Modeling of multicenter bonding interactions involving f-electrons is crucial to understand the role of electron delocalization, degree of covalency, and non-negligible multi-nodal back-bonding effects), a crucial piece of information in high-valence actinide complexes. Analyses of electron density matrices will be performed at both DFT and multireference methods through considering scalar relativistic complete active space self-consistent field (CASSCF) or Dirac-CASSCF wavefunctions. Spectroscopic signatures will be modeled with time-dependent DFT calculations and will be complemented with multi-reference (XMS)-PDFT method to model UV-vis spectra, identify and describe the nature of electronic excitations. DFT will also be employed to compute NMR spectra to address strong correlation and spin-orbit coupling, high-level wavefunction-based methods will be used to not only evaluate the electronic structure but also for geometry optimization and vibrational analysis.

Texas A&M University (TAMU) proposes continuing the research and workforce development of the Center for Excellence in Nuclear Training And University-based Research (CENTAUR). The Center is a partnership of seven academic institutions and collaboration with two DOE/NNSA (Lawrence Livermore, and Los Alamos) National Laboratories. Graduate students and postdocs funded by the Center will have access to the K500 superconducting cyclotron and K150 cyclotron located at TAMU and the 9 +8 MV Tandem-Linac located at the John D. Fox Accelerator Laboratory at Florida State University to conduct hands-on research. Additionally, the Center will provide an intellectually stimulating environment for young scientists in addition to exposure to personnel and research of the DOE/NNSA laboratories through internships and the annual stewardship and Center meetings to increase awareness about the breadth of rewarding careers that are available as part of the NNSA workforce. Texas A&M University (TAMU) will lead the CENTAUR partnership under the PI and Center Director Prof. Sherry Yennello, Regents Professor of Chemistry, and Director of the Cyclotron Institute (CI) and the Nuclear Solutions Institute. Dr. Lauren McIntosh will continue as Managing Director. Texas A&M has ongoing collaborations with Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The facilities of the CI will be available for research and training of Center participants (graduate students and postdocs), academic partners, and scientists from the DOE/NNSA laboratories who are collaborating with the proposed Center. Prof. Philip Adsley, Jeremy Holt, Dan Melconian, Ralf Rapp, Grisha Rogachev, and research scientist Dr. Alan McIntosh will each lead research projects and mentor students as part of CENTAUR. Florida State University (FSU) brings to the Center partnership use of the 9 +8 MV Tandem-Linac, including the triton beam developed with CENTAUR support. Efforts at FSU will be led by Prof. Ingo Wiedenhoever and include Sergio Alamaraz-Calderon, Paul Cottle, Mark-Christoph Spieker, and Vandana Tripathi. This partnership will allow greater use by non-FSU CENTAUR students and DOE/NNSA laboratory scientists and continue the successful pipeline to DOE/NNSA laboratories. Louisiana State University (LSU) will have co-PIs, Prof. Scott Marley and Kristina Launey, lead experimental and theoretical research, respectively, and mentor students as a part of CENTAUR. University of Massachusetts Lowell (UML) will bring the expertise of co-PI Prof. Marian Jandel with prior LANL experience and connection, as well as extensive experience with GEANT4 and MCNP. The University of Tennessee – Knoxville (UTK) will have co-PI Prof. Miguel Flores who has been instrumental in bringing development of triton beam capability at FSU. University of Washington (UW) is host to the Institute for Nuclear Theory and Prof. Aurel Bulgac, an expert in high-performance computing applications of Density Functional Theory with an emphasis on nuclear superfluid properties. Washington University (WU) in St. Louis MO, has CENTAUR co-PI, Prof. Lee Sobotka to lend expertise on nuclear reactions, fission, advanced electronic chips, and development of neutron detectors.

Extreme AM processing conditions exhibit significant temperature gradients and rapid cooling rates resulting in materials with unique far-from-equilibrium micro/nanostructures that produce superior mechanical properties to their conventionally manufactured counterparts. However, much is still unknown about how these unusual microstructures from AM CCSs behave under non-classical conditions relevant to NNSA applications. To address key knowledge gaps, CAMCSE unites and leverages the expertise of 16 world-class researchers spanning 5 distinct disciplines from 5 core academic partners: University of Massachusetts Amherst (Additive Manufacturing and Micro-ballistic Impact); UAB (Static High-Pressure High-Temperature and Computational Physics/Machine Learning); Stanford University, SLAC (Advanced Time-resolved Characterization, and Dynamic Compression); University of California, Irvine (Machine Learning-based Prediction Modeling), and Tuskegee University (3-D Printing via Direct Ink Writing); and four user facilities. Four lab partners — LANL, LLNL, SNL, and NNSS — advance our research and training mission. CAMCSE uses three metal AM techniques, i.e., laser powder-bed-fusion (L-PBF), laser-engineered net shaping (LENS), and Direct Ink Writing (DIW), to fabricate CCSs with tailored microstructures and properties for our multiscale experimental characterizations. Static high-pressure high-temperature studies are conducted in a large volume-cell as well as in laser-heated a diamond anvil cell to 100 GPa and 2300 K. Phase transformation and thermal equation of data is subsequently compared for both equilibrium and non-equilibrium microstructures of AM CCSs. We then conduct laser-induced shock compression studies on AM CCSs using X-ray Free Election Lasers (XFEL) sources to obtain the equation of state, crystal structures and microstructural dynamics under strain rate of 107-109. Novel laser-induced projectile impact testing (LIPIT) is employed for the study of micro-ballistic impact hardness of AM CCSs under a high strain rate (104 – 107 s-1) and results are compared with compressive shear strength data on AM CCSs in a diamond anvil cell. Led by Yogesh Vohra (UAB), the team makes strategic use of DOE and other user facilities to pursue Center-wide goals. CAMCSE is supported by collaborative arrangements with Linac Coherent Light Source at SLAC National Accelerator Lab, HPCAT, Advanced Photon Source, Argonne National Laboratory, Jupiter Laser Facility at LLNL, and SPring-8 Angstrom Compact X-ray free electron Laser in Japan.

The Center for Matter Under Extreme Conditions (CMEC) is a partnership between four University of California campuses (UC San Diego, UC Davis, UC Berkeley, and UC Los Angeles), University of Rochester, and General Atomics, in close collaboration with LLNL, LANL, SNL, and SLAC. CMEC’s research focuses on connecting HED materials to plasmas through two Thrust Areas: (1) energy transport in HED plasmas; and (2) material properties across the HED regime. Our educational programs will train students and postdoctoral scholars across the key areas of HED physics that support research in fusion science. CMEC will address many of the key challenges for HEDS highlighted in the Decadal Report, including: • How are hydrodynamic shocks and instabilities affected by radiation? • What nonlinear process occur when plasmas collide? • What are material properties at the pressures and densities present in the interiors of planets, or white dwarfs? To achieve its mission and objectives, CMEC integrates a highly productive, multi-disciplinary team of leading HED scientists spanning key disciplinary areas from planetary science to astrophysical and laboratory HED plasmas NA with a robust training program and access to state-of-the-art tools. The team’s combination of expertise in experiments, modeling, theory, and diagnostics is critical to addressing the complex science challenges of understanding changes in materials’ properties under extreme conditions and the strategic goals of the SSP. The impact of the CMEC is threefold: i) advancement of understanding of matter under extreme temperature and pressure, resulting in high-quality publications; ii) outstanding training, mentorship, and career opportunities for a diverse, early-career workforce; and iii) educational tools to serve the entire research community.

Chicago/DOE Alliance Center – A Center of Excellence for Materials at Extremes (CDAC) is dedicated to basic research, training, and technique development in the study of materials in extreme conditions. The Center has enabled numerous advances in high P-T science, technology, and training since its inception in 2003 as the Carnegie/DOE Alliance Center. These advances include student and postdoc-led scientific discoveries and a successful track record in training early career scientists for work in the NNSA complex. The Research and Training plan is organized into three Thrusts driven by NNSA-derived Grand Challenges for materials in extreme environments, specifically: 1. Thermomechanical Extremes, with the goal to enhance understanding of materials in extreme conditions by advancing the evolving synergy between static, quasi-static, and dynamic compression techniques over a broad range of strain and strain rates in close synergy with theory, modeling, and simulation; 2. Chemical Extremes, with the goal to advance our understanding of extreme chemistry, including the development of rules for predicting chemical behavior at extreme conditions and extreme reactivity under all conditions, length scales, and dimensionality; and 3. Multiple Extremes, with the goal to advance our knowledge of the behavior of materials exposed to combined extreme conditions, including intense particle and electromagnetic fields, to enhance material performance, and to create new materials. The Center is linked by four Cross-cutting Themes involving all three Thrusts: (a) determining Material Properties in extreme environments, (b) investigating carefully chosen Targeted Materials, (c) fostering close synergy between Experiment and Theory, and (d) utilizing Advanced Radiation Facilities at DOE/SC and DOE/NNSA labs and other facilities. CDAC will conduct static, quasi-static, and dynamic compression experiments covering a broad range of strain rates, together with theory, modeling, and simulation in CDAC university labs as well as DOE/SC and DOE/NNSA facilities. The work will be enabled by continued access to CDAC’s partner synchrotron radiation facilities, High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source, Argonne National Laboratory (ANL) and the Frontier Infrared Spectroscopy (FIS) beamline at the National Synchrotron Light Source II, Brookhaven National Laboratory (BNL), as well as other facilities. The overarching scientific outcome is advancing the fundamental understanding of materials behavior in extreme conditions, which in turn will lead to improved understanding of materials aging, performance of newly manufactured materials, materials in multiple extreme environments, and the creation of new materials of relevance to the NNSA.

The primary mission of the Center for Magnetic Acceleration, Compression, and Heating (MACH) is to support the needs of the Stockpile Stewardship Program (SSP) in the area of pulsed-power-driven HEDP. This includes improving the understanding of fundamental HED science; exploiting the understanding to develop new and exciting concepts and applications; developing and stewarding next-generation pulsed power technology and drivers; leading, growing, and diversifying the pulsed power HEDP community (including participation in the Z Fundamental Science Program (ZFSP) and the nascent ZNetUS consortium); training the next generation of HED scientists and engineers; and partnering with NNSA/defense laboratories to ensure healthy staffing pipelines and strong science-based mission alignment. To accomplish these goals, students and researchers in the MACH Center will design and execute experiments, supported by theory and computation, that are relevant to key NNSA mission areas. These areas include ICF/MagLIF; neutron and x-ray source development for radiation effects testing; novel experimental platforms and diagnostic techniques to enable new measurements of HED material properties (e.g., electrical conductivity and magnetized transport); neutron source development relevant to Neutron Diagnosed Subcritical Experiments (NDSE); and fundamental science (e.g., lab astrophysics). The MACH Center will focus on key physics issues pertaining to: (1) magnetically driven implosions, including neutron and x-ray producing gas-puff z-pinches for radiation source development, and initially solid-metal liner implosions relevant to MagLIF; (2) electromagnetic power flow & current delivery in the presence of background electrode plasmas, with particular emphasis placed on experiments that can help inform the design of a Next Generation Pulsed Power facility as well as the design of a dense plasma focus for NDSE; and (3) novel experimental configurations (e.g., magnetically exploded systems) to enable greater diagnostic access for HED measurements and for exploring new applications (e.g., novel fuel preheating schemes for MagLIF).

HED science is the study of matter in the extreme, where pressures are above 1 million atmospheres (106 atm ≡ 1 Mbar ≡ 0.1 TPa) and temperatures range from about 10,000 to over 1,000,000 K (a few eV to keVs). Such systems are naturally found throughout the Universe, for example, in accretion disks, planetary interiors, magnetospheres, supernovae remnants, and astrophysical jets. Additionally, Inertial Confinement Fusion (ICF), key to the NNSA Stockpile Stewardship Program (SSP), falls in the HED regime. HED matter is complex, timescales are short (picoseconds to nanoseconds), and spatial scales are small (microns to millimeters). In any system, from an ICF experiment to an exploding star, when mass, momentum, or energy physically change, they do so via some transport process on a molecular, microscopic, or macroscopic level. In addition, the transport may be altered by the presence of strong magnetic or radiation fields and turbulent mixing. These transport processes in turn impact the structural evolution of their systems of origin. They may also impact densities, temperatures, ionization, flow speed, and other parameters. The University of Michigan aims to better understand these transport processes and their effects through a combination of experiment, simulation, and theory. The proposed Center for High Energy Density laboratory Astrophysics Research (CHEDAR) is inspired by specific astrophysical processes occurring in the Universe. Astrophysical observations certainly provide a wealth of knowledge and information, but distance and access to these complex systems will always limit our understanding. Simulation work is often computationally prohibitive due to the large range of spatial and temporal scales and the overall complexity of physical processes present. Common to unraveling all astrophysical systems and processes is the need to understand the mass, momentum, and energy transport that affects the evolution from the early Universe to present day. The University of Michigan is motivated to grapple with these elusive phenomena through a multivariate yet strategically focused approach. They aim to isolate specific, relevant processes and study them in a controlled setting. Such fundamental understanding of core building blocks is the focal point of the proposed laboratory astrophysics research program, which integrates experiments at multiple HED facilities, simulation codes with complementary models, and relevant theory. While challenges and opportunities arise with each of these separate methods, integrating them will strengthen our fundamental understanding. CHEDAR’s proposed discovery science just described is foundational to the SSP. Stockpile stewardship, and specifically ICF, integrates complex physics in extreme states of matter on short time and spatial scales. High temperatures and strong radiation are present in many stages of ICF experiments, both in the hohlraum and capsule. Understanding radiation transport in matter and radiation hydrodynamics in the HED regime is, thus, essential. ICF experiments also have multiple shocks that traverse material interfaces where complex instabilities and mixing can develop, injecting cold material into the central hot spot, which reduces the fusion yield. Therefore,fundamental mass transport and mixing due to hydrodynamics instabilities are crucial to ICF. Additionally, strong magnetic fields may be generated or are inherently present in ICF systems, which can lead to strongly driven magnetized plasmas, including magnetized shocks. Magnetized transport in the HED regime, lastly, must be well understood. Students will study these three fundamental discovery science areas with tools and methods key to the SSP. Specifically, they aim to better understand transport processes and their effects through a combination of experiment, simulation, and theory, with a commitment to identifying and employing the optimal tool or technique to investigate the HED science of interest and to understanding potential knowledge gaps in any specific method. Using an array of experimental facilities can offer access to a variety of HED conditions, diagnostics, and scales, in particular length (100 μm to 1 cm) and time (ps to 100s of ns). Students will start at small-scale facilities for exploratory experiments and transition to larger scale facilities as feasible. The breadth of experimental platforms (i.e. long and short-pulse laser and pulsed power) is a unique strength of the Center. Students will also use NNSA Laboratory codes (xRAGE, CASSIO, ARES, and HYDRA), again through NNSA Laboratory collaborations, so that they will gain experience with codes essential to the SSP, as well as codes that are publicly available, available via collaboration, or available with a license (LAMMPS, IMPACTA, PSC, CRASH, FLASH, and HELIOS).

The Wootton Center for Astrophysical Plasma Properties (WCAPP) focuses on atomic and radiation physics and material properties at a wide range of temperatures and densities. Our team will use facilities such as the Z machine at Sandia National Laboratories and the opacity platform at the National Ignition Facility. The WCAPP team will use spectra at wavelengths from x-ray to optical to diagnose plasmas and compare with observations of astrophysical objects and similar plasmas. This work will emphasize experiments, but incorporate a range of theorists and modelers for code validation. This will sharpen the scientific impact of the experiments and their contribution to NNSA. Our team will include university, National Laboratory, and NASA scientists, representing all career stages from the most junior to the most senior. The specific areas of investigation are: Ia. Stellar Opacity (Z) Ib. Stellar Opacity (NIF) II. Accretion-Power Sources (Z) III. Non-equilibrium X-ray Heating (Z) IV. White Dwarf Photospheres (Z) V. Planetary Material (Z) VI. Atomic Theory and Modeling