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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Excitation of XPS spectra from nanoscaled particles by local generation of x-rays

In preliminary work, the authors have shown that use of an aluminum substrate to support a distribution of copper particles enables their characteristic photoelectrons to be observed within the Auger electron spectrum generated by an incident electron beam. This observation raises the possibility of the use of chemical shifts and the corresponding Auger parameter to identify the chemical states present on the surface of individual submicrometer particles within a mixture. In this context, the technique has an advantage in that, unlike conventional Auger electron spectroscopy, the electron beam does not dwell on the particle but on the substrate adjacent to it. Given the importance, for both medical and toxicological reasons, of the surface composition of such particles, the authors have continued to explore the potential of this development. In this contribution, the authors show that proximal excitation of x-rays is equally successful with magnesium substrates. In some regions of the x-ray photoelectron spectrum, the much larger Auger peaks generated by the electron beam can cause inconvenient clustering of Auger and photoelectron peaks. As in conventional x-ray photoelectron spectroscopy, the ability to switch between Al and Mg sources is useful in such situations. In this context, the authors have extended the studies to iron particles where the authors show that use of Al or Mg substrates, as necessary, can make a contribution to clear identification of individual components in the Fe 2p peaks. For this development in electron spectroscopy to achieve its full potential, it is necessary to optimize the beam conditions used to generate the local x-ray to give good selectivity of a given particle. Measurements made in support of this will be given. Of greater concern is a possible problem of local heating associated with x-ray generation. The authors continue to explore this problem and report some progress in minimizing heating of the particle while maintaining the particle selectivity that is central to this exciting development.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

What more can be done with XPS? Highly informative but underused approaches to XPS data collection and analysis

Because of the importance of surfaces and interfaces in many scientific and technological areas, the use of x-ray photoelectron spectroscopy (XPS) has been growing exponentially. Although XPS is being used to obtain useful information about the surface composition of samples, much more information about materials and their properties can be extracted from XPS data than commonly obtained. This paper describes some of the areas where alternative analysis methods or experimental design can obtain information about the near-surface region of a sample, often information not available in other ways. Experienced XPS analysts are familiar with many of these methods, but they may not be known to new or casual XPS users, and sometimes, they have not been used because of an inappropriately assumed complexity. The information available includes optical, electronic, and electrical properties; nanostructure; expanded chemical information; and enhanced analysis of biological materials and solid/liquid interfaces. Many of these analyses can be conducted on standard laboratory XPS systems, with either no or relatively minor system alterations. Topics discussed include (1) considerations beyond the “traditional” uniform surface layer composition calculation, (2) using the Auger parameter to determine a sample property, (3) use of the D parameter to identify sp 2 and sp 3 carbon information, (4) information from the XPS valence band, (5) using cryocooling to expand range of samples that can be analyzed and minimize damage, and (6) using electrical potential effects on XPS signals to extract chemically resolved electrical measurements including band alignment and electrical property information.

Baer, Donald R. [Pacific Northwest National Labora↗
DOE OSTI2026

DP-TwoLevel: two-stage gradient subspace learning for differentially private federated learning

Federated learning (FL) enables collaborative model training across distributed data sources without sharing raw data, but faces fundamental challenges in communication efficiency and privacy. Differentially private (DP) training mitigates information leakage but introduces noise that degrades model performance, especially in high-dimensional settings. We propose DP-TwoLevel, a hierarchical gradient projection method that improves utility under fixed DP constraints by exploiting low-dimensional structure in model updates. Our approach learns a two-level PCA-based representation of gradients and applies DP noise in a reduced-dimensional subspace, thereby lowering the effective noise magnitude while preserving dominant signal components. We evaluate the method across three datasets (MNIST, Fashion-MNIST, CIFAR-10) and three privacy regimes (ϵ∈0.5, 1.0, 2.0). Across nine experimental settings, DP-TwoLevel consistently outperforms DP-FedAvg, achieving an average accuracy improvement of 9.44%, with larger gains observed in lower ϵ(higher-noise) regimes (up to +22.31%). We further analyze scalability across models ranging from 100K to 1.49M parameters and identify a variance-based success criterion: performance remains strong when the projection preserves more than 75% of gradient variance, degrades in a marginal regime (65–75%), and fails below this threshold. Our results demonstrate that structure-aware dimensionality reduction can significantly improve the privacy–utility tradeoff in FL without modifying formal privacy guarantees. We also provide empirical evidence of scaling limitations for global projections and motivate per-layer extensions for larger models.

Kotevska, Olivera [ORNL] (ORCID:0000000316772243)↗
DOE OSTI2014

WE-G-BRD-05: Is “New Radiobiology” Needed to Account for the Anti-Tumor Efficacy of Hypofractionated Lung SBRT?

Purpose: The radiobiological understanding of SBRT is controversial. In this work, we modeled SBRT outcomes based on a previously published tumor control probability model, that incorporates hypoxia, proliferation and cell-cycle effects, in order to understand if non-traditional factors must be invoked to understand the efficacy of single and multiple fraction SBRT. Methods: We extracted cohorts from Mehta et al. (PRO (2012) 2:288) with easily identifiable fractionation parameters and commensurate outcome and prescription methods (n=2617). Each RT scheme was simulated in the model, and the surviving fraction (SF) of tumor cells was estimated. Another simulation was then carried out with conventional (2Gy/fx, 5fx/wk) fractionation until the same SF was achieved, resulting in model-derived equivalent dose in 2Gy/fx for α/β=10 (EQD2{sub 10}(model)). In the scatter plot of the outcome vs. EQD2{sub 10}(model), logistic regressions were performed for the total group or separate groups (conventional RT, SBRT with 3×10 fxs, and single fx SBRT), assuming the slope of the dose response curve (γ{sub 50}) of 1.5. Chi-squared tests were performed to test the validity of the fit. Results: With unfavorable hypoxic and cell-cycle effects, the effectiveness of typical SBRT regimes were predicted by the model to be significantly less effective than comparable standard fractionation regimes. The single-fraction TD{sub 50} was only 55% of the conventional fractionation TD{sub 50}, in units of EQD2{sub 10}(model). The dose response curves for the separate fractionation groups seems to represent the three different groups, with a high p-value for both SBRT groups. For the lower α/β of 3, the same patterns were observed with smaller differences among the groups. Conclusion: Based on classical radiobiology, the dose response relation of SBRT was evaluated and compared with conventional RT. Observed SBRT outcomes are inconsistent with classical radiobiology principles, suggesting the possible other effects, which increases as the fractional dose increases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-G-BRD-02: Automated Systematic Quality Assurance Program for Radiation Oncology Information System Upgrades

Purpose: To: (1) describe an independent, automated, systematic software-based protocol for verifying clinical data accuracy/integrity for mitigation of data corruption/loss risks following radiation oncology information system (ROIS) upgrades; and (2) report on application of this approach in an academic/community practice environment. Methods: We propose a robust approach to perform quality assurance on the ROIS after an upgrade, targeting four data sources: (1) ROIS relational database; (2) ROIS DICOM interface; (3) ROIS treatment machine data configuration; and (4) ROIS-generated clinical reports. We investigated the database schema for differences between pre-/post-upgrade states. Paired DICOM data streams for the same object (such as RT-Plan/Treatment Record) were compared between pre-/post-upgrade states for data corruption. We examined machine configuration and related commissioning data files for changes and corruption. ROIS-generated treatment appointment and treatment parameter reports were compared to ensure patient encounter and treatment plan accuracy. This protocol was supplemented by an end-to-end clinical workflow test to verify essential ROI functionality and integrity of components interfaced during patient care chain of activities. We describe the implementation of this protocol during a Varian ARIA system upgrade at our clinic. Results: We verified 1,638 data tables with 2.4 billion data records. For 222 under-treatment patients, 605 DICOM RT plans and 13,480 DICOM treatment records retrieved from the ROIS DICOM interface were compared, with no differences in fractions, doses delivered, or treatment parameters. We identified 82 new data tables and 78 amended/deleted tables consistent with the upgrade. Reports for 5,073 patient encounters over a 2-week horizon were compared and were identical to those before the upgrade. Content in 12,237 xml machine files was compared, with no differences identified. Conclusion: An independent QA/validation approach for ROIS upgrades was developed and implemented at our clinic. The success of this approach ensures a robust QA of ROIS upgrades without manual paper/electronic checks and associated intensive labor.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

State-variable model of porous electrode batteries 1-D electrochemical/thermal behavior

Compared to full-order numerical models, the state-variable model (SVM) achieves multiple orders of reduction in computation time for simulation of electrochemical/thermal transport and reaction processes occurring inside lithium-ion and similar batteries with porous electrode construction. The model efficiently describes Li diffusion dynamics in active material and electrolyte phases, charge transfer kinetics, charge balance, and electron transport processes. The model requires a separate pre-processing step to identify SVM parameters.

Kim, Gi-Heon↗
DOE OSTI2019

Deep Direct-Use Feasibility Study Numerical Modeling and Uncertainty Analysis using iTOUGH2 for West Virginia University

To reduce the geothermal exploration risk, a feasibility study is performed for a deep direct-use system proposed at the West Virginia University (WVU) Morgantown campus. This study applies numerical simulations to investigate reservoir impedance and thermal production. Because of the great depth of the geothermal reservoir, few data are available to characterize reservoir features and properties. As a result, the study focuses on the following three aspects: 1. model choice for predicting reservoir impedance and thermal breakthrough: after investigating three potential models (one single permeability model and two dual permeability models) for flow through fractured rock, it is decided to use single permeability model for further analysis; 2. well placement (horizontal vs. vertical) options: horizontal well placement seems to be more robust to heterogeneity and the impedance is more acceptable; 3. Prediction uncertainty: the most influential parameters are identified using a First-Order-Second-Moment uncertainty propagation analysis, and the uncertain range of the model predictions is estimated by performing a Monte Carlo simulation. Heterogeneity has a large impact on the perdition, therefore, is considered in the predictive model and uncertainty analysis. The numerical model results and uncertainty analysis are used for economic analysis. The dataset submitted here support the described study. Manuscript is submitted to Geothermics, will be linked once paper is accepted.

15 GEOTHERMAL ENERGY↗
DOE OSTI2018

2018 Water Splitting Technologies Benchmarking and Protocols Workshop

The HydroGEN EMN (Energy Materials Network) benchmarking team held a workshop for the advanced water splitting technologies on October 24-25 at Arizona State University, in Tempe, AZ. Several breakout sessions were held for each technology area, to gather information for developing material protocols and identifying critical parameters.

08 HYDROGEN↗
DOE OSTI2012

Energy Reductions Using Next-Generation Remanufacturing Techniques

The goal of this project was to develop a radically new surface coating approach that greatly enhances the performance of thermal spray coatings. Rather than relying on a roughened grit blasted substrate surface for developing a mechanical bond between the coating and substrate, which is the normal practice with conventional thermal spraying, a hybrid approach of combining a focused laser beam to thermally treat the substrate surface in the vicinity of the rapidly approaching thermally-sprayed powder particles was developed. This new surface coating process is targeted primarily at enabling remanufacturing of components used in engines, drive trains and undercarriage systems; thereby providing a substantial global opportunity for increasing the magnitude and breadth of parts that are remanufactured through their life cycle, as opposed to simply being replaced by new components. The projected benefits of a new remanufacturing process that increases the quantity of components that are salvaged and reused compared to being fabricated from raw materials will clearly vary based on the specific industry and range of candidate components that are considered. At the outset of this project two different metal processing routes were considered, castings and forgings, and the prototypical components for each process were liners and crankshafts, respectively. The quantities of parts used in the analysis are based on our internal production of approximately 158,000 diesel engines in 2007. This leads to roughly 1,000,000 liners (assuming a mixture of 6- and 8-cylinder engines) and 158,000 crankshafts. Using energy intensity factors for casting and forgings, respectively, of 4450 and 5970 Btu-hr/lb along with the energy-induced CO 2 generation factor of 0.00038 lbs CO 2 /Btu, energy savings of over 17 trillion BTUs and CO 2 reductions of over 6.5 million lbs could potentially be realized by remanufacturing the above mentioned quantities of crankshafts and liners. This project supported the Industrial Technologies Program's initiative titled 'Industrial Energy Efficiency Grand Challenge.' To contribute to this Grand Challenge, we. pursued an innovative processing approach for the next generation of thermal spray coatings to capture substantial energy savings and green house gas emission reductions through the remanufacturing of steel and aluminum-based components. The primary goal was to develop a new thermal spray coating process that yields significantly enhanced bond strength. To reach the goal of higher coating bond strength, a laser was coupled with a traditional twin-wire arc (TWA) spray gun to treat the component surface (i.e., heat or partially melt) during deposition. Both ferrous and aluminum-based substrates and coating alloys were examined to determine what materials are more suitable for the laser-assisted twin-wire arc coating technique. Coating adhesion was measured by static tensile and dynamic fatigue techniques, and the results helped to guide the identification of appropriate remanufacturing opportunities that will now be viable due to the increased bond strength of the laser-assisted twin-wire arc coatings. The feasibility of the laser-assisted TWA (LATWA) process was successfully demonstrated in this current effort. Critical processing parameters were identified, and when these were properly controlled, a strong, diffusion bond was developed between the substrate and the deposited coating. Consequently, bond strengths were nearly doubled over those typically obtained using conventional grit-blast TWA coatings. Note, however, that successful LATWA processing was limited to ferrous substrates coated with steel coatings (e.g., 1020 and 1080 steel). With Al-based substrates, it was not possible to avoid melting a thin layer of the substrate during spraying, and this layer re-solidified to form a band of intermetallic phases at the substrate/coating interface, which significantly diminished the coating adhesion. The capability to significantly increase the bond strength with ferrous substrates and coatings may open new remanufacturing opportunities that were previously not considered due to concerns with the limits of the mechanical bonding of conventional TWA coatings. However, the limited results obtained within this one-year program are not sufficient to move the LATWA into a production environment. Additional work will be needed engineer the process to coat components with more complex geometries than the flat specimens studied in this work. In addition part-specific bench testing and relevant field tests will be required to fully establish the necessary confidence for introducing the LATWA process. These are typical constraints and requirements for most any new production process, and it is quite possible this new process will continue to be a viable approach for extending the usage of remanufacturing, and in turn capturing the resulting energy savings and green house gas emission reductions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

PV Power Output Smoothing using Energy Storage

This paper describes a simple algorithm designed to reduce the variability of photovoltaic (PV) power output by using an energy storage device. A full-scale implementation was deployed in an actual PV Energy demonstration project, in partnership with a utility and a battery manufacturer. The paper describes simulation tests as well as field results. In addition to demonstrating implementation of smoothing controls, this work also served to verify the models, identify best parameter sets for utility operations, and study the operation of an advanced energy storage system under partial state of charge and rapid, irregular charge/discharge cycling.

Ellis, Abraham↗
DOE OSTI2013

DARHT Axis II Cathode 12 (S/N 15) History as Recorded in the Historian and Shot Data Databases (DARHT Technical Note No. 501)

Long DARHT II injector cathode operating lifetimes are desirable for flash radiography of hydrodynamic tests at the dual-axis radiographic hydrotest facility (DARHT). The specification for cathode operating lifetime given to Spectra-Mat in the purchase orders for the 311X-M cathodes is ≥ 1000 hours at full operating temperature (~1120 °C). Of the five most-recent cathodes operated on DARHT II, only two have met this specification. It is desirable to have cathodes lifetimes considerably longer than the specified 1000 hours. In this report we present the thermal and vacuum history of cathode 12 (serial no. [S/N] 15), a 311X-M cathode, as recorded in the historian database and the shot data database. The hope is that by examining this history we can identify the parameter (or parameters) that are limiting the DARHT II 311X-M cathode lifetimes. This is the first in a series of 5 DARHT Tech Notes in which recent cathode thermal and vacuum histories are examined. The other tech notes in this series are DARHT Tech Notes Nos. 502 (cathode 13, S/N 19), 503 (cathode 14, S/N 20), 504 (cathode 15, S/N 21), and 505 (cathode 16, S/N 22). In DARHT Tech Note No. 506 we will compare the recorded thermal and vacuum histories of cathodes 12-16 and attempt to understand the cathode lifetime limitations based on the stored cathode data presented in DARHT Tech Notes 501-505 and other relevant information.

42 ENGINEERING↗
DOE OSTI2014

DARHT Axis II Cathode 16 (S/N 22) History as Recorded in the Historian and Shot Data Databases

Long DARHT II injector cathode operating lifetimes are desirable for flash radiography of hydrodynamic tests at the dual-axis radiographic hydrotest facility (DARHT). The specification for cathode operating lifetime given to Spectra-Mat in the purchase orders for the 311X-M cathodes is ≥ 1000 hours at full operating temperature (~1120 oC). Of the five most-recent cathodes operated on DARHT II, only two have met this specification. It is desirable to have cathodes lifetimes considerably longer than the specified 1000 hours. In this report we present the thermal and vacuum history of cathode 16 (serial no. [S/N] 22), a 311X-M cathode, as recorded in the historian database and the shot data database. The hope is that by examining this history we can identify the parameter (or parameters) that are limiting the DARHT II 311X-M cathode lifetimes. This is the fifth in a series of 5 DARHT Tech Notes in which recent cathode thermal and vacuum histories are examined. The other tech notes in this series are DARHT Tech Notes Nos. 501 (cathode 12, S/N 15), 502 (cathode 13, S/N 19), 503 (cathode 14, S/N 20), and 504 (cathode 15, S/N 21). In DARHT Tech Note No. 506 we will compare the recorded thermal and vacuum histories of cathodes 12-16 and attempt to understand the cathode lifetime limitations based on the stored cathode data presented in DARHT Tech Notes 501-505 and other relevant information.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2016 First Quarterly Report

During the first quarter of FY 2016, the following technical progress has been made toward project milestones: 1) Virginia Tech completed fiber orientation (FO) measurements for the samples taken at Locations A, B, C and D (Figure 1) from the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed and non-ribbed complex parts using Virginia Tech’s established procedure. Virginia Tech delivered to PNNL all the measured fiber orientation data for validating ASMI fiber orientation predictions. 2)Virginia Tech performed fiber length distribution (FLD) measurements for the samples taken at Locations A, B, C and D from these complex parts using Virginia Tech’s established procedure. Virginia also re-assessed previous data and measured fiber length distributions in the corresponding nozzle purging materials and delivered to PNNL all the measured length data for validating ASMI fiber length predictions. 3)Based on measured fiber orientation data, Autodesk identified the parameters of the anisotropic rotary diffusion reduced strain closure (ARD-RSC) model [1] and provided PNNL with the values of these parameters that were used in ASMI analyses of the complex parts. 4) Magna provided Virginia Tech with additional samples cut out from the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed parts (Figure 1) for fiber length and orientation measurements. 5) In discussion with Autodesk, PNNL performed 3D ASMI analyses of the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed and non-ribbed complex parts to predict fiber orientations and length distributions in these parts. The issues observed through the analyses regarding fiber orientation distributions profiles and abnormal length distributions were reported to Autodesk. Autodesk is working to resolve these issues. 6) PNNL completed 3D ASMI analyses of the complex parts and compared predicted fiber orientation results at Locations A, B, and C on the non-ribbed parts, and at Locations A, B, C and D on the ribbed parts with the corresponding measured data. PNNL also evaluated the within-15%-agreement criterion using the principal tensile and flexural moduli computed based on predicted vs. measured fiber orientation results. 7) PNNL developed and discussed with Toyota, Magna and PlastiComp a method to perform weight and cost reduction for making the 30wt% LCF/PA66 ribbed part through comparative three-point bending simulations of this part and of similar parts in steel.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Final Scientific/Technical Report

To increase our understanding of coal biogasification and move this technology closer toward field scale demonstration, we have thoroughly investigated coal bioconversion both ex situ and in situ. Specifically, we have screened a total of 12 parameters and identified those that exert statistically positive influence on coal biogasification. Based on these evaluations, a recipe for a nutrient solution was developed. With the addition of this nutrient solution, methane yield from Illinois coal was enhanced dramatically. In addition, we have demonstrated that coal bioconversion can be sustained over a long period of time as long as suitable conditions were maintained. Furthermore, biogasification of coal was tested under pressure simulating in situ conditions. Surprisingly, pressure was found to have no negative effects on microbial activities. Thus, the same recipe developed for ex situ may be used in situ as well.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Model Test Bed for Evaluating Wave Models and Best Practices for Resource Assessment and Characterization

A wave model test bed is established to benchmark, test and evaluate spectral wave models and modeling methodologies (i.e., best practices) for predicting the wave energy resource parameters recommended by the International Electrotechnical Commission, IEC TS 62600-101Ed. 1.0 ©2015. Among other benefits, the model test bed can be used to investigate the suitability of different models, specifically what source terms should be included in spectral wave models under different wave climate conditions and for different classes of resource assessment. The overarching goal is to use these investigations to provide industry guidance for model selection and modeling best practices depending on the wave site conditions and desired class of resource assessment. Modeling best practices are reviewed, and limitations and knowledge gaps in predicting wave energy resource parameters are identified.

13 HYDRO ENERGY↗
DOE OSTI2018

Process Development for Selective Laser Melting of Molybdenum

This report presents a process development effort aimed at both identifying operating parameters for producing high quality Molybdenum components via Selective Laser Melting (SLM) and developing a framework for understanding parameter interactions and enabling informed decision-making in parameter selection. At the core of this effort was mapping of SLM process inputs to build outcomes, for which there are application-based constraints, e.g. final part density, surface finish, and dimensional accuracy. Process mapping in additive manufacturing is currently the subject of intense research efforts at many institutions, both experimentally and through computational modeling; this was an experimentally driven research effort, which was carried out with an understanding of the importance of the underlying mechanisms that are inherent to the SLM process, such as the impact of laser power and scan speed on melt pool morphology, as well as solidification dynamics. Results revealed promising avenues for mapping of SLM process parameters for Molybdenum and quantitatively reinforced ideas derived from observations of part quality, i.e. density, mass, surface roughness.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Evaluation of Strangpresse Extruder on ORNL BAAM

Researchers at ORNL’s Manufacturing Demonstration Facility (MDF) worked with Strangpresse, LLC to demonstrate Strangpresse’s newly developed extrusion system. The project tested both a small and large Strangpresse extruder. The project also resulted in Strangpresse exclusively licensing ORNL’s some of previously developed extruder technology for high-volume additive manufacturing. The Strangpresse extruder is still under development and testing, however. The next phase of this project could include tasks such as identifying process parameters, making test articles, and quantifying material properties.

42 ENGINEERING↗
DOE OSTI2019

High-current density CORC® wires for use in accelerator magnets

Next generation accelerator magnets capable of generating magnetic fields in excess of 16 T require high-temperature superconductors (HTS) such as Conductor on Round Core (CORC®) cables and wires, wound from RE-Ba 2 Ca 3 O 7-δ (ReBCO, Re = rare earth) coated conductor tapes.1 The severe operating requirements of an engineering current density (J e ) of at least 400 Amm -2 at 4.2 K and 20 T, high operating currents of 5-20 kA, tolerance to Lorentz stresses in excess of 150 MPa, and in many cases cable bending diameters as small as 30 mm, make accelerator magnets one of the most challenging applications for any HTS material. Advanced Conductor Technologies (ACT) has been developing CORC® cables and wires wound from ReBCO tapes containing substrates of 30-50 µm thickness to meet these requirements. Although these requirements could each be met separately with current CORC® technology, meeting the requirements at the same time requires thinner, more powerful CORC® wires wound from tapes with even thinner substrates. The purpose of this Phase I SBIR program was to determine the feasibility to develop ReBCO tapes containing 25 µm thick substrates on an industrial scale and wind thinner CORC® wires from these tapes that could eventually meet the stringent performance specifications for accelerator magnets. The results of the Phase I program clearly demonstrated the feasibility of developing thinner, more powerful CORC® wires using ReBCO tapes with 25 µm substrate that would likely meet the stringent requirements for use in accelerator magnet by the end of the potential Phase II program. SuperPower Inc., as the subcontractor on the Phase I program, was successful in developing tapes with 25 µm substrate at minimum piece lengths of 30-40 m with a clear path towards industrial production. A total length exceeding 350 meters of 2 mm wide ReBCO tape with critical current (I c ) of between 45 and 65 A at 77 K was delivered to ACT during the Phase I program. The thinner tapes allowed us to reduce the CORC® core (former) from 2.5 mm to 2.0 mm, resulting in a higher current density conductor with enhanced flexibility. Several CORC® wires were manufactured to reach the Phase I goal of a Je of at least 300-400 Amm -2 at 20 T at a minimum bending diameter to less than 50 mm. Several CORC® wires were wound and analyzed after bending by identifying the location of peak stresses and causes of tape damage. Data was compared to 3D finite element models that included parametric studies to identify key parameters leading to the observed tape failure modes. The models suggest that flexibility is heavily dependent on the friction coefficient between tapes in a CORC® wire and the width of the tapes used. These studies provide a clear and straightforward path to improve conductor flexibility within the proposed Phase II program to reach our goal of minimum bending diameters below 30 mm with minimal I c reduction. We were successful in developing a flexible, 3.3 mm thick, high-J e CORC® wire containing 30 ReBCO tapes that carried > 80 % of its original I c after bending to diameters down to 44 mm. The CORC® wires showed no cyclic degradation due to in-field testing up to 57 stress cycles at 12 T. Another CORC® wire of 3.4 mm thickness had a J e as high as 451 Amm -2 when extrapolated to 20 T at a bending diameter of 63 mm, which is a new high-field performance record. We were also able to design a CORC® wire with increased tensile strength of 240 MPa at 76 K. The results of the Phase I program allow us to propose a very strong Phase II program with a high likelihood of reaching the ultimate goal of CORC® accelerator magnets wires with I c exceeding 8-10 kA and J e exceeding 600 Amm -2 at 20 T while bent to a 30 mm diameter.

43 PARTICLE ACCELERATORS↗