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4.5m GTEM RS105 Test Capability Commissioning

Bowman, Tyler; Baker, Nicholas S.; Oliveira, Matthew P.H.; Nelson, Howard W.

This work details the reconfiguration of the 4.5 m Gigahertz Transverse Electromagnetic test facility at Sandia National Laboratories to operate in accordance with the RS105 (radiated susceptibility) test from MIL-STD-461 representing a high-altitude electromagnetic pulse. This reconfiguration involved removal of the existing continuous wave source and connecting both a high voltage feed and a coaxial feed housing the Marx bank pulser. Marx control settings were calibrated for several voltage levels across two pulsers, and position-dependent measurements of the peak electric field were taken throughout the test volume for each pulser. The results showed field uniformity and purity across the test volume comparable to continuous wave operations, and field peaks were measured from 1.63 kV/m to 54.8 kV/m, with maximum capabilities expected to exceed 100 kV/m. Some challenges in consistent pulser operations at lower Marx bank voltages and high frequency reflections in the system were identified for future capability improvements.

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TYPE SAND Report YEAR 2023
DOIOSTI

Verification and benchmarking relativistic electron beam transport through a background gas

Computer Physics Communications

Medina, Brandon M.; Grua, Pierre; Cartwright, Keith L.; Hebert, David; Szalek, Nicolas; Caizergues, Clement; Owens, Israel J.; Rhoades, Elaine L.; Gardelle, Jacques; Moore, Christopher H.

It is necessary to establish confidence in high-consequence codes containing an extensive suite of physics algorithms in the regimes of interest. Verification problems allow code developers to assess numerical accuracy and increase confidence that specific sets of model physics were implemented correctly in the code. The two main verification techniques are code verification and solution verification. In this work, we present verification problems that can be used in other codes to increase confidence in simulations of relativistic beam transport. Specifically, we use the general plasma code EMPIRE to model and compare with the analytical solution to the evolution of the outer radial envelope of a relativistic charged particle beam. We also outline a benchmark test of a relativistic beam propagating through a vacuum and pressurized gas cell, and present the results between EMPIRE and the hybrid code GAZEL. Further, we discuss the subtle errors that were caught with these problems and detail lessons learned.

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TYPE Journal Article YEAR 2023
DOIOSTIScopus

Integrated Tiger Series (ITS) Code Validation and Uncertainty Quantification for Electron Number Albedo in Various Materials

Depriest, Kendall R.; Kensek, Ronald P.; Olson, Aaron; Davis, Rowdy

In the 1970’s and 1980’s, researchers at Sandia National Laboratories produced electron albedo data for a range of materials. Since that time, the electron albedo data has been used for a wide variety of purposes including the validation of Monte Carlo electron transport codes. This report was compiled to examine the electron albedo experiment results in the context of Integrated Tiger Series (ITS) validation. The report presents tables and figures that could provide insight into the underlying model form uncertainty present in the ITS code. Additionally, the report provides data on potential means to reduce these model form errors by highlighting potential refinements in the cross-section generation process.

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TYPE SAND Report YEAR 2023
DOIOSTI

Grayscale Digital Light Processing Gradient Printing for Stress Concentration Reduction and Material Toughness Enhancement

Journal of Applied Mechanics, Transactions ASME

Forte, Connor T.; Montgomery, S.M.; Yue, Liang; Hamel, Craig; Qi, H.J.

Avoiding stress concentrations is essential to achieve robust parts since failure tends to originate at such concentrations. With recent advances in multimaterial additive manufacturing, it is possible to alter the stress (or strain) distribution by adjusting the material properties in selected locations. Here, we investigate the use of grayscale digital light processing (g-DLP) 3D printing to create modulus gradients around areas of high stress. These gradients prevent failure by redistributing high stresses (or strains) to the neighboring material. The improved material distributions are calculated using finite element analysis. The much-enhanced properties are demonstrated experimentally for thin plates with circular, triangular, and elliptical holes. This work suggests that multimaterial additive manufacturing techniques like g-DLP printing provide a unique opportunity to create tougher engineering materials and parts.

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TYPE Journal Article YEAR 2023
DOIOSTIScopus

Executive Summary of the Z Fundamental Science Program

Knudson, Marcus D.

The Z Fundamental Science (ZFS) Program is intended to provide access to the Z machine and its diagnostics for high energy density (HED) experiments in collaboration with a broad community of academic, industrial, and national laboratory research interests. ZFS experiments on the Z Facility focus on conducting fundamental research in HED science and help provide research experience necessary to maintain and grow the HED community, especially through involvement of researchers from academia. This report serves as an executive summary of the ZFS Program and provides a succinct synopsis of the history of the ZFS Program, metrics and impacts of the Program, as well as a brief list of the most impactful publications that have resulted from the various ZFS Projects relevant to laboratory astrophysics, plasma physics, and planetary physics.

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TYPE SAND Report YEAR 2023
DOIOSTI

Parallel simulation via SPPARKS of on-lattice kinetic and Metropolis Monte Carlo models for materials processing

Modelling and Simulation in Materials Science and Engineering

Mitchell, John A.; Abdeljawad, Fadi; Battaile, Corbett C.; Garcia-Cardona, Cristina; Holm, Elizabeth A.; Homer, Eric R.; Madison, Jonathan D.; Rodgers, Theron M.; Thompson, Aidan P.; Tikare, Veena; Webb, Ed; Plimpton, Steven J.

SPPARKS is an open-source parallel simulation code for developing and running various kinds of on-lattice Monte Carlo models at the atomic or meso scales. It can be used to study the properties of solid-state materials as well as model their dynamic evolution during processing. The modular nature of the code allows new models and diagnostic computations to be added without modification to its core functionality, including its parallel algorithms. A variety of models for microstructural evolution (grain growth), solid-state diffusion, thin film deposition, and additive manufacturing (AM) processes are included in the code. SPPARKS can also be used to implement grid-based algorithms such as phase field or cellular automata models, to run either in tandem with a Monte Carlo method or independently. For very large systems such as AM applications, the Stitch I/O library is included, which enables only a small portion of a huge system to be resident in memory. In this paper we describe SPPARKS and its parallel algorithms and performance, explain how new Monte Carlo models can be added, and highlight a variety of applications which have been developed within the code.

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TYPE Journal Article YEAR 2023
DOIOSTIDOIScopusOSTIScopus
Results 4001–4050 of 101,000
Results 4001–4050 of 101,000
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