Lawrence Berkeley Research Articles

Data-driven approach for synchrotron X-ray Laue microdiffraction scan analysis.

A novel data-driven approach is proposed for analyzing synchrotron Laue X-ray microdiffraction scans based on machine learning algorithms. The basic architecture and major components of the method are formulated mathematically. It is demonstrated through typical examples including polycrystalline BaTiO3, multiphase transforming alloys and finely twinned martensite. The computational pipeline is implemented for beamline 12.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory. The conventional analytical pathway for X-ray diffraction scans is based on a slow pattern-by-pattern crystal indexing process. This work provides a new way for analyzing X-ray diffraction 2D patterns, independent of the indexing process, and motivates further studies of X-ray diffraction patterns from the machine learning perspective for the development of suitable feature extraction, clustering and labeling algorithms.

William Jagust: Arrow Through The Rings

William Jagust: Arrow Through The Rings

Inorganic crystal soaks up CO2

Jeffrey Long and his colleagues at the Lawrence Berkeley National Laboratory noticed something surprising during their study of a potential hydrogen-storing material. When they grew magnesium borohydride on reduced graphene oxide, it formed an unusually open and porous crystalline nanostructure. “Working with the playbook of the periodic table, most inorganic crystals are dense,” Long says. But the gamma form of crystalline magnesium borohydride (shown) is an exception. Contemplating the material’s large surface area and its plethora of exposed, reactive borohydrides, postdoc Sohee Jeong had “a chemical intuition that it would soak up CO2,” Long says. She was right. Detailed studies revealed that the material initially works slowly, as the borohydrides first reduce the gas to create formate groups. There is then a stepwise spike in carbon dioxide uptake, forming methoxide groups (Adv. Mater. 2019, DOI: 10.1002/adma.201904252). A version of the material pretreated to create the formate groups works as well

One-year Stay at Lawrence Berkeley National Laboratory

One-year Stay at Lawrence Berkeley National Laboratory

(Invited) The FC-PAD Consortium: Advancing Fuel Cell Performance and Durability

The Fuel Cell Performance and Durability (FC-PAD) consortium was formed to advance performance and durability of polymer-electrolyte fuel cells (PEFCs) at a pre-competitive level in order to further enable their commercialization. This consortium coordinates national laboratory activities related to fuel-cell performance and durability, provides technical expertise, and harmonizes activities with industrial developers. The consortium serves as a resource that amplifies DOE EERE’s impact by leveraging the core capabilities of several labs in conducting low technology-readiness-level research. Consortium members include Argonne National Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, the National Renewable Energy Laboratory, and Oak Ridge National Laboratory.This consortium incorporates national laboratory investigators with proven experience (developed in prior projects) related to durability, transport, and performance, and combines them into one highly coordinated effort. The consortium is divided into six thrusts: three thrust areas related to components ((1) Electrocatalysts and Supports, (2) Electrode Layers, (3) Ionomers, Gas Diffusion Layers, Bipolar Plates, Interfaces), and three cross-cutting thrust areas ((4) Modeling and Validation, (5) Operando Evaluation: Benchmarking, ASTs, and Contaminants and (6) Component Characterization and Diagnostics.) In addition, four external-lab FC-PAD projects are led by 3M Company, General Motors, United Technologies Research Center, and Vanderbilt University. The core national lab team supports those four projects utilizing national lab capabilities. The major challenge addressed by this consortium is to develop the knowledge base, design rules, and understanding of underlying phenomena in order to mitigate durability concerns and optimize performance through understanding the science of integration, while simultaneously reducing cost. Current research focuses on achieving high performance and durability in low Pt-loaded PEFCs. FC-PAD has conducted significant analysis of MEA electrode structures, analyzed the structures to understand the performance and durability losses, comprehensively defined the current commercial material baseline materials, and used this information to developed new electrode architectures that are designed to minimize existing electrode layer losses. In this talk, in addition to discussion of the consortium itself, recent results will be highlighted including analysis of electrode layers from inks to structure to conditioning to performance. AcknowledgmentsWe want to acknowledge all of the FC-PAD researchers, particularly the Research Thrust Coordinators: Deborah Myers (ANL), K.C. Neyerlin (NREL), Ahmet Kusoglu (LBNL), Rajesh Ahluwalia (ANL), Rangachary Mukundan (LANL), Karren More (ORNL). This work is funded through the DOE FC-PAD Consortium with thanks to DOE EERE FCTO.

(Invited) HydroGEN Supernode: Linking Low Temperature Electrolysis/Hybrid Materials Properties to Electrode Performance

The HydroGEN Energy Materials Network (EMN) supernode in low temperature electrolysis combines capabilities from the National Renewable Energy Laboratory (NREL), Lawrence Berkeley National Laboratory (LBNL), and Savannah River National Laboratory (SRNL) to perform relevant and ground-breaking research outside of EMN-funded projects. The low temperature electrolysis supernode focuses on: evaluating and bridging the gap between rotating disk electrode half-cell activity and membrane electrode assembly single-cell performance; and understanding how electrode composition and processing parameters affects device performance. Ex-situ testing has been used to screen a variety of catalysts and correlate oxygen evolution activity to in-situ performance. Gaps between half- and single-cells were attributed to differences in configuration and standardized test parameters. While non-kinetic loss in membrane electrode assemblies are primarily due to resistance (ohmic), significantly larger transport losses are found in rotating disk electrodes due to electrode orientation and agitation. Differences in kinetics between these methods is primarily due to temperature. Increasing half-cell temperature and using flow cells can be used to bridge the gap between ex- and in-situ performance. Various oxygen evolution catalyst types, including different surfaces (metal/oxide), supports, surface areas, and components, were evaluated to address test differences across these material sets. Additionally, electrode composition and processing parameters were evaluated for their affect in electrolysis performance. Although catalyst layer uniformity may not significantly affect device performance at high loading, coating methodology is critical at low loading. Various spray coating parameters, including ink composition (ionomer content, water/alcohol ratio), drying temperature, and deposition rate were evaluated and found to alter the resulting performance in membrane electrode assemblies. Ionomer content was further correlated to half-cell tests, where low content may adversely impact ink stability (catalyst layer uniformity) and the catalyst layer interface, while high content may lower performance through contaminant effects. Parameters from spray coating tests were applied to slot die and gravure coating methods to transfer this understanding to larger-scale processes. Efforts to tune coating parameters utilize rheology studies and ex-situ characterization to assess catalyst-ionomer-solvent interactions and ionomer thin films. Multiscale modelling was used to evaluate membrane electrode assembly performance and separate kinetic, transport, and ohmic losses. Composition and processing parameters were additionally applied to hybrid cycles.

(Invited) Progress in Metal-Supported Solid Oxide Cells with Infiltrated Electrodes

This talk will provide an overview of performance, durability, and applications of metal-supported solid oxide fuel cell and electrolysis cell technology developed at Lawrence Berkeley National Laboratory (LBNL). The unique LBNL symmetric cell architecture design, with thin zirconia ceramic backbones and electrolyte sandwiched between porous metal supports, offers a number of advantages over conventional all-ceramic cells, including low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. The metal-supported solid oxide cells achieve high performance at 700°C: >1.5 W/cm2 with 3% humidified hydrogen fuel >1.2 W/cm2 with internal reforming of ethanol fuel >2.6 A/cm2 electrolysis current density at 1.3V and 50%steam/50% hydrogen With infiltrated catalysts, there is a tradeoff between initial performance and long-term stability, as extremely high surface area promotes high electrochemical reaction rates, but also provides high surface energy leading to coarsening and facilitates Cr deposition. Recent approaches to mitigating catalyst coarsening and Cr deposition within the cathode include coatings to prevent Cr evaporation from the stainless steel components, and optimization of infiltrated catalyst processing to stabilize the microstructure during operation. The degradation rate has improved to 2.3% kh-1 in fuel cell mode, compatible with the requirements for electric vehicle range extenders. Electrolysis operation, however, results in higher degradation rate. Efforts to identify and mitigate the additional degradation mechanisms in electrolysis mode will be discussed. Scale-up from button cells to 50cm2 is ongoing, and highlights will be presented. In addition to our long-standing development of zirconia-based metal-supported cells, recent exploratory effort has focused on compatibility between stainless steel metal supports and proton-conducting ceramics. Co-sintering of 400-series stainless steel and BZCY-type proton conductors presents a number of challenges, including: Ba evaporation in reducing atmosphere, over-densification of steel at the high temperatures (>1400°C) required for BZCY processing, and migration of Cr and Si from the steel support into the BZCY layers. Feasibility of new approaches to overcome these challenges will be discussed.

(Invited) Enabling Cost Effective Hydrogen at Low Temperatures

This presentation will focus on durable, high-performance materials and interfaces for advanced water splitting, enabling a clear pathway for achieving <$2/KgH2 (on scale) with efficiency of 43 KWh/Kg using anion exchange membrane interface. Advances via fundamental understanding of both hydrogen and oxygen evolution reactions (HER/OER) leading to novel materials will be in conjunction with critical improvements in membrane and ionomers and gas evolution electrodes with corresponding characterization and testing. Progress towards these goals under a three-year multifaceted and comprehensive effort will be described wherein Northeastern University (NEU) will present catalyst development and characterization (both in situ and ex situ). University of Delaware (UD) will showcase improvements in ionomer and membrane materials. In addition, close collaboration with National Laboratory partners with Lawrence Berkeley National Lab (LBNL) participating in multiscale modeling and computation in close concert with Sandia National Laboratory (SNL) providing MD simulations of the membrane catalyst interface and National Renewable Energy Laboratory (NREL) providing advanced ionomers, durability protocols and validation will be described. Anion exchange membrane electrolyzers (AEMELs) are ideally suited with a low-cost profile enabled by platinum group metal (PGM)-free catalysts, low fluorine content membranes, and a less corrosive environment for cell separators. This presentation will showcase state of the art stable, high-conductivity, and high-strength AEMs, stable and active PGM-free catalysts for hydrogen and oxygen evolution reaction (HER/OER), and high performance electrode architectures that together can unlock the cost advantages of AEMELs. If successful, the developed technology can meet FCTO efficiency targets, delivering carbon-neutral hydrogen at $2/kg while simultaneously enabling higher penetrations of wind and PV electricity on the grid. The overall goal is cell level performance of 1.62 V at 1 A/cm2, which meets the FCTO efficiency target of 43 kWh/kg. Component performance targets have been established using a porous electrode model to support the overall cell performance target. This is at the modeled scale of 50,000 kg/day and operating at 1 A/cm2 resulting in hydrogen cost at $2.15, $1.82, or $1.76/kg, respectively (2, 20, 200 plants). In the low-volume manufacturing case, it is still possible to meet the cost target by operating near 2 A/cm2, sacrificing some efficiency.

(Invited) Materials Discovery for Energy Applications

New materials are critical for meeting our future global energy needs and to create the needed disruptive technologies for energy conversion, delivery, storage, and use. Materials discovery is being accelerated by significant advances in theory and high-throughput materials synthesis and characterization to a point where theory and computation can directly guide experimental materials discovery and development. We will present an overview and highlights from the Next Generation for Materials Design (CNGMD) Energy Frontier Research Center (EFRC), a multi-institution center funded by DOE including results from partners at NREL, Lawrence-Berkeley National Laboratory, SLAC National Laboratory, Harvard University, Oregon State University, Colorado School of Mines, and CU-Boulder. Our EFRC team integrates theory and experiment, including high-throughput methods and in-situ characterization, to discover new functional semiconductor materials, particularly metal oxides and nitrides, relevant to energy applications. Our main goal is to develop a systematic methodology to incorporate and actively design for functional metastability. We focus not only on ground-state materials discovery but also on incorporating metastability (i.e. non-equilibrium structures and compositions) into materials design. We are establishing ranges for accessible metastable materials as a function of the chemistry, energetics, and structure by investigating three classes of metastable systems: defects, polymorphs, and solid solutions (alloys). Another aim is to guide the synthesis of new materials. By coupling theory with state-of-the-art in-situ characterization to probe materials growth pathways, we are developing a systematic theory-driven approach to guide the synthesis of new materials—including metastable systems. An overview of NREL’s extensive R&D program in photovoltaics will also be presented along with challenges to address the development of the needed terawatts of global solar energy.

Modeling Electrolyte Composition Effects on Anion-Exchange-Membrane Water Electrolyzer Performance

Anion-exchange membrane (AEM) electrolyzers are an attractive alternative for hydrogen production due to the potential stability and activity of non-precious metal catalysts in alkaline environments. Recently, AEM electrolyzers have been demonstrated using various membranes, ionomers, porous-transport layers, and catalysts (1). The influence of these materials and their properties on AEM electrolyzer performance, however, is underdeveloped. Furthermore, recent studies have shown (2) and hydrogen-evolution reaction kinetics (3), offering additional routes to decreasing cost and reducing operating voltage. In this work, we use a coupled, nonisothermal, multiphase model of an AEM electrolyzer to understand the role of material properties, transport phenomena, and reaction kinetics in improving device pformance. We use the model to identify performance bottlenecks through applied voltage breakdowns (AVBs) and provide guidance for next-generation electrolyzer materials and designs by evaluating sensitivity to membrane and catalyst-layer properties. Finally, we explore the effects of various electrolyte solution feeds and operating paradigms on cell performance, with a particular interest in the influence of ion transport on reaction kinetics. Acknowledgements This work was funded under the HydroGEN Consortium, by the Office of Energy Efficiency and Renewable Energy (EERE), of the U.S. Department of Energy under contract number DE-AC02-05CH11231. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program. This work was also supported in part by Workforce Development & Education at Berkeley Lab. We thank Sanjeev Mukerjee, Ian Kendrick, Yu Seung Kim, and Dongguo Li for helpful discussions. References I. Vincent and D. Bessarabov, Renewable and Sustainable Energy Reviews, 81, 1690 (2018).H. Ito, N. Kawaguchi, S. Someya, T. Munakata, N. Miyazaki, M. Ishida and A. Nakano, International Journal of Hydrogen Energy, 43, 17030 (2018).Q. Jia, E. Liu, L. Jiao, J. Li and S. Mukerjee, Current Opinion in Electrochemistry, 12, 209 (2018).

Macro-Energy Systems: Toward a New Discipline

Patricia J. Levi is a doctoral candidate in the Management Science and Engineering department at Stanford University. Her research uses tools from economics and operations research to improve regulations and policy that reduce environmental impacts in the electricity sector. She earned a SM in Technology & Policy (2016) at the Massachusetts Institute of Technology, where she was also a researcher at the MIT Energy Initiative. Simon Davidsson Kurland is a postdoctoral researcher at Chalmers University of Technology, where he explores the potential for decarbonizing energy and transport systems and their associated energy and material flows. He was previously a postdoctoral scholar at Stanford University, focusing on net energy analysis of photovoltaics and battery systems. He has an MSc in Energy Systems Engineering and a PhD in Natural Resources and Sustainable Development from Uppsala University, Sweden. Michael Carbajales-Dale heads the Energy-Economy-Environment (E3) Systems Analysis group. He joined Clemson University in August 2014 as an Assistant Professor in the Environmental Engineering & Earth Sciences department. Before joining Clemson, Mik was an Energy Systems Analyst with Stanford’s Environmental Assessment & Optimization Lab and with the Global Climate & Energy Project (GCEP). His research focuses on the long-term, large-scale evolution and dynamics of the energy-economy system, especially how development of energy resources affects social development and the effects of a future transition from fossil fuels to renewable energy technologies. John P. Weyant is Professor of Management Science and Engineering, Director of the Energy Modeling Forum (EMF), a Senior Fellow at the Precourt Institute for Energy, and an affiliated faculty member in the School of Earth Sciences at Stanford University. His current research focuses on developing improved methods for diagnostics and uncertainty characterization in energy and environmental modeling, energy technology assessment, and strategic planning methods. He serves on many scientific advisory boards and has been awarded lifetime achievement awards by the US Institute for Energy Economics, the International Association for Energy Economics, and the Integrated Assessment Modeling Consortium. Dr. Adam R. Brandt is an Associate Professor in the Department of Energy Resources Engineering at Stanford University. His research focuses on reducing the greenhouse gas impacts of energy production and consumption. Primary research interests include life cycle assessment of petroleum production and natural gas extraction, with a particular interest in unconventional fossil fuel resources such as oil sands, oil shale, and hydraulically fractured oil and gas resources. He also researches computational optimization of low-emissions technologies, such as carbon dioxide capture, solar thermal, and solar photovoltaic output prediction. Dr. Brandt received his PhD from the Energy and Resources Group, UC Berkeley. Sally M. Benson is a professor of energy resources engineering in the School of Earth, Energy & Environmental Sciences, co-director of the Precourt Institute for Energy, and Director of the Global Climate and Energy Project at Stanford University. Formerly, Benson was at Lawrence Berkeley National Laboratory, where she held a variety of key positions, including Deputy Director, Associate Director for Energy Sciences, and Director of the Earth Sciences Division. Benson is regarded as an authority on carbon capture and storage. She also uses energy systems analysis to help guide decisions about the most promising pathways for clean energy development.

User defined elements in ANSYS for 2D multiphysics modeling of superconducting magnets

Dynamic simulation of superconducting magnets is critical for the design of quench protection systems to prevent potentially damaging temperatures and high voltage from developing after magnet quench. Modeling these scenarios is challenging due to the many multiscale phenomena which impact magnet behavior. These range from conductor scale effects of quench and interfilament coupling currents up to the behavior of the magnet in its powering and protection circuit. In addition, a strong coupling between electromagnetic and thermal domains is required to capture temperature and field dependent material properties and quench behavior. We present a finite element approach which integrates the various effects into the commercial software ANSYS by means of programming new element types. This is shown capable of simulating the strongly coupled transient electromagnetic, thermal, and circuit behavior of superconducting magnets required for quench protection studies. A benchmarking study is presented which shows close agreement between the new ANSYS elements and a COMSOL Multiphysics implementation developed at CERN for dump resistor and coupling loss induced quench based magnet protection of a Nb3Sn block dipole. Following this, the ANSYS implementation is shown reproducing strongly coupled quench back behavior observed during the test of a Nb3Sn superconducting undulator prototype at Lawrence Berkeley National Laboratory.

Relationship between mechanical strain and chemical composition in LiFePO4 via 4D-scanning transmission electron microscopy and scanning transmission X-ray microscopy

Journal Article Relationship between mechanical strain and chemical composition in LiFePO4 via 4D-scanning transmission electron microscopy and scanning transmission X-ray microscopy Get access LA Hughes, LA Hughes National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94708, USA Corresponding author, laurenhughes@lbl.gov Search for other works by this author on: Oxford Academic Google Scholar Benjamin H Savitzky, Benjamin H Savitzky National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94708, USA Search for other works by this author on: Oxford Academic Google Scholar Haitao D Deng, Haitao D Deng Depart. of Mat. Sci. & Eng., Stanford University, Stanford, CA 94305, USA Search for other works by this author on: Oxford Academic Google Scholar Norman L Jin, Norman L Jin Depart. of Mat. Sci. & Eng., Stanford University, Stanford, CA 94305, USA Search for other works by this author on: Oxford Academic Google Scholar Eder G Lomeli, Eder G Lomeli Depart. of Mat. Sci. & Eng., Stanford University, Stanford, CA 94305, USA Search for other works by this author on: Oxford Academic Google Scholar William C Chueh, William C Chueh Depart. of Mat. Sci. & Eng., Stanford University, Stanford, CA 94305, USA Search for other works by this author on: Oxford Academic Google Scholar Patrick Herring, Patrick Herring Toyota Research Institute, Los Altos, CA 94022, USA Search for other works by this author on: Oxford Academic Google Scholar Colin Ophus, Colin Ophus National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94708, USA Search for other works by this author on: Oxford Academic Google Scholar Andrew M Minor Andrew M Minor National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94708, USADepart. of Mat. Sci. & Eng., University of California, Berkeley, CA 94720, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 2068–2069, https://doi.org/10.1017/S1431927619011073 Published: 01 August 2019

Mechanical Study of a Superconducting 28-GHz Ion Source Magnet for FRIB

The superconducting electron cyclotron resonance (ECR) source magnet for the facility for rare isotope beams at Michigan State University was designed and built by the Superconducting Magnet Group at Lawrence Berkeley National Laboratory (LBNL) in 2017. The 28 GHz NbTi ion source magnet features a sextupole-in-solenoids configuration which is comparable to the VENUS ECR magnet operated at LBNL. However, the mechanical design of this magnet utilizes a shell-based support structure which allows fine adjustments to the sextupole preload and reversibility of the magnet assembly process. The magnet has been assembled and tested to operational currents at LBNL. This paper describes the mechanical analyses performed to estimate the sextupole's and solenoids' preloads. We will report on the 3-D finite element analysis during room temperature assembly, cool-down, and magnet excitation, and then describe the magnet preload operations. Finally, we will describe the performance of the support structure during the quench training.

Test Results for a Superconducting 28-GHz Ion Source Magnet for FRIB

The superconducting ECR source magnet for the Facility for Rare Isotope Beams at Michigan State University was designed and built by the Superconducting Magnet Group at Lawrence Berkeley National Laboratory (LBNL). The 28-GHz NbTi ion source magnet features a sextupole-in-solenoids configuration, which is comparable to the VENUS ECR magnet operated at LBNL. A shell-based support structure using bladders and keys has been incorporated into the design to allow for adjustments of the preload and reversibility of the magnet assembly process. The magnet has been assembled and successfully tested to operational currents at LBNL. This paper describes the basic design of the magnet and the passive quench protection system. The test results are also presented, including the quench behavior of the magnet, the training performance, and the magnetic measurement results.

Diameter Quality Control of Nb3Sn Wires for MQXF Cables in the USA

The 0.850 ± 0.003 mm Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wires for the low-beta quadrupole magnets “MQXFA” procured for the U.S. LHC Accelerator R&D Program (LARP) and the U.S. High Luminosity LHC Accelerator Upgrade Project (US HL-LHC AUP, or simply AUP) are received at Lawrence Berkeley National Laboratory (LBNL). There, the wires are respooled and then fabricated into Rutherford cables for winding coils. As part of the quality control program, AUP obtains from the wire manufacturer values of the maximum, average, minimum, and standard deviation of the two orthogonal axes, which are assessed prior to shipment approval. At LBNL, a dual-axis optical micrometer is used to measure the wire diameter of each spool every ~30 cm prior to cabling. This helps decide whether wire pieces with abnormal diameters should be distributed across the cable cross section, in order to improve cable parameter quality and mechanical stability consistency. This paper presents: 1) diameter data of LARP cables and of the first AUP cables made using wires acquired under LARP; 2) our deviation acceptance/rejection justification; and 3) the impact of wire diameter statistics on cable fabrication.

Vertical Magnetic Measurements of the First Full-Length Prototype MQXFAP2 Quadrupole for the LHC Hi-Lumi Accelerator Upgrade Project

This paper reports the commissioning of the vertical magnetic measurement system and the room temperature (warm) and cryogenic (cold) magnetic field measurements of the first full-length (4.2 m) quadrupole built by the U.S. Accelerator Upgrade Project (AUP) (formerly the LARP collaboration) for the high luminosity upgrade of the Large Hadron Collider at CERN. The magnet, designated MQXFAP2, is a prototype preceding production for the AUP which will provide ten sets of 8.4-m superconducting insertion region quadrupoles for the Hi-Lumi Upgrade. The quadrupoles will be built by assembling two 4.2-m magnets in a single cryostat. Agreement between Brookhaven National Laboratory's (BNL's) and Lawrence Berkeley National Laboratory's (LBNL's) warm measurement data has indicated that the upgraded vertical magnetic measurement system at Brookhaven National Laboratory is ready for MQXFA magnet production testing. The cold magnetic measurement has been performed and preliminary data analysis has been conducted.

Fabrication of Bi-2212 Canted-Cosine-Theta Dipole Prototypes

Author(s): Fajardo, LG; Brouwer, L; Caspi, S; Hafalia, A; Hernikl, C; Prestemon, S; Shen, T; Bosque, E; English, C | Abstract: The U.S. Magnet Development Program (MDP) is exploring the possibility of combining low-and higherature superconductor technologies, using cosine-theta and canted-cosine-theta (CCT) Nb3Sn dipole magnets together with Bi-2212 CCT inserts, with the ultimate goal of constructing a 20-T dipole. The MDP short-term goal is a Bi-2212 CCT insert capable of reaching 5 T in the bore when operating as a stand-alone and 3 T when operating under a background field of 15 T. This paper reports on the fabrication of our BIN4 dipole magnet and our BIN5a and BIN5b coils, designed and built at the Lawrence Berkeley National Laboratory to address potential fabrication issues of Bi-2212 coils and verify the design of our 18-20-T dipole magnet. BIN4 is a two-layer 50-cm-long CCT magnet that uses a nine-strand Rutherford cable made with 0.8-mm-diameter Bi-2212 strands. Its goal is to investigate critical current, insulation integrity, manufacturing challenges, and quench protection issues after heat treating both layers together under oxygen at standard atmosphere (1 bar). BIN5a and BIN5b are two identical coils, similar to the outer layer of BIN4, with the difference that the length is 39 cm, and they will undergo 50-bar overpressure processing heat treatment. BIN5 coils are made from the state-of-the-art strand with an engineering critical current density of 1150 A/mm2 at 4.2 K and 5 T.

Absolute single photoionization cross-sections of Br3+: experiment and theory

Absolute single photoionization cross section measurements for Br3+ ions are reported in the photon energy range 44.79–59.54 eV at a photon energy resolution of 21 ± 3 meV. Measurements were performed at the Advanced Light Source at Lawrence Berkeley National Laboratory using the merged-beams technique. Numerous resonance features in the experimental spectrum are assigned and their energies and quantum defect values are tabulated. The cross-section measurements are also compared with Breit–Pauli R-matrix calculations with suitable agreement over the photon energy range investigated. Analysis of the measured spectrum including Rydberg resonance series identifications produced a new emperical determination of the ionizational potential of Br3+ of 46.977 ± 0.050 eV, which is 805 meV lower than the most recently published value of 47.782 eV. This disparity between our determination and the earlier published value is similar to an 843 meV shift in the accepted ionization potential published for iso-electronic Se2+ as part of this same research program.

Measuring Conversion Efficiency of Solar Vapor Generation

Xiuqiang Li obtained his PhD at College of Engineering and Applied Sciences, Nanjing University. Currently, he is a postdoc at Duke University. His research focuses on solar energy conversion and nanoscale heat transfer. George Ni is a research scientist at Lincoln Laboratory, Massachusetts Institute of Technology. He obtained his PhD in mechanical engineering at Massachusetts Institute of Technology. His research focuses on solar energy conversion. Thomas Cooper is an assistant professor at York University. He received his PhD and MSc from ETH Zurich in 2014 and 2010, respectively, and his BASc from the University of Toronto in 2008, all in mechanical engineering. His research focuses on solar energy and converting it into useful forms. Ning Xu, Jinlei Li, and Pengcheng Yao are PhD students at College of Engineering and Applied Sciences, Nanjing University. Their research focuses on solar energy conversion. Xiaozhen Hu and Bin Zhu are research scientists at College of Engineering and Applied Sciences, Nanjing University. Lin Zhou is an associate Professor at College of Engineering and Applied Sciences, Nanjing University. Their research focuses on solar energy conversion. Jia Zhu is a Professor at College of Engineering and Applied Sciences, Nanjing University. He obtained his bachelor’s degree in physics at Nanjing University and received his MS and PhD in electrical engineering from Stanford University. He worked as a postdoctoral fellow at University of California, Berkeley and Lawrence Berkeley National Lab. His scientific research interest is in the area of nanomaterials, nanophotonics and nanoscale heat transfer.