A5089160707- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Plasma Diagnostics and Applications
- Electromagnetic Simulation and Numerical Methods
- Microwave Engineering and Waveguides
- Magnetic confinement fusion research
- Computational Fluid Dynamics and Aerodynamics
- Electromagnetic Scattering and Analysis
- Photocathodes and Microchannel Plates
- Electromagnetic Launch and Propulsion Technology
- Laser-Plasma Interactions and Diagnostics
- Gas Dynamics and Kinetic Theory
- Advanced Data Storage Technologies
- Ionosphere and magnetosphere dynamics
- Electron and X-Ray Spectroscopy Techniques
- Advanced Numerical Methods in Computational Mathematics
- Pulsed Power Technology Applications
- Lightning and Electromagnetic Phenomena
- Fluid Dynamics Simulations and Interactions
- Microwave-Assisted Synthesis and Applications
- Parallel Computing and Optimization Techniques
- Laser-induced spectroscopy and plasma
- Education and Critical Thinking Development
- Distributed and Parallel Computing Systems
Leidos (United States)
2016-2024
Los Alamos National Laboratory
2010-2023
Computational Physics (United States)
2023
WellStar Health System
2021
University of Central Missouri
2012-2019
Missouri State University
2019
Advanced Applications (United States)
2012
Indiana University of Pennsylvania
2012
Interface (United States)
2009
Los Alamos National Security (United States)
1999-2007
The development of a new three-dimensional electron gun and collector design tool is reported. This simulation code has been designed to address the shortcomings current beam optics modeling tools used for vacuum devices, ion sources, charged-particle transport. specifically targets problem classes including gridded-guns, sheet-beam guns, multibeam anisotropic collectors, with focus on improved physics models. includes both structured unstructured grid systems meshing flexibility. A method...
Recent developments to the MICHELLE electron gun and collector design tool are reported in this paper. The code is a new finite-element (FE) two-dimensional three-dimensional electrostatic particle-in-cell that has been designed address recent beam optics modeling simulation requirements for vacuum devices, ion sources, charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multibeam guns, sheet-beam thrusters. focus of development...
Knudsen layer losses of tail fuel ions can significantly reduce the fusion reactivity multi-keV DT in capsules with small $\ensuremath{\rho}r$; sizable yield reduction result for inertial confinement (ICF) capsules. This effect is most pronounced when distance from a burning gas region to nonreacting or cold wall comparable mean free path reacting ions. A simplified asymptotic theory depletion presented and nonlocal reduced model obtained. Application simulations ICF capsule implosion...
The thickness of the entrainment zone at top atmospheric mixed layer is analyzed using measurements made with a ground-based lidar during BLX83 and CIRCE field programs. When entrainment-zone depth normalized by mixed-layer plotted as function rate convective velocity scale, time parameter, hysteresis curve results. Although portions can be approximated diagnostic relationships, complete behavior better described prognostic relationship. A simple thermodynamic model that maps surface-layer...
Abstract Electromagnetic pulse (EMP) events produce low‐energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how interact air in order accurately predict EMP evolution and propagation. An swarm model can be used monitor the time of an environment characterized by electric field pressure. Here a developed that based on coupled ordinary differential equations (ODEs) described Higgins et al. (1973), hereinafter HLO. The ODEs...
The status of first principles modeling and simulation tools for vacuum electronics (VEs) is presented. These tools, when combined with parametric beam-wave interaction comprise the suite that enable design optimization VE devices, such as RF amplifiers. Although many basic algorithms discussed in article have been around decades, advances electromagnetic electrostatic particle-in-cell meshless beam codes revolutionized device development process where first-pass has become standard. include...
Abstract Atmospheric electromagnetic pulse (EMP) events are important physical phenomena that occur through both man‐made and natural processes. Radiation‐induced currents voltages in EMP can couple with electrical systems, such as those found satellites, cause significant damage. Due to the disruptive nature of EMP, it is accurately predict evolution propagation computational models. CHAP‐LA ( C ompton H igh A ltitude P ulse‐ L os lamos) a state‐of‐the‐art code solves Maxwell s equations...
New educators may feel overwhelmed by the options available for engaging students through classroom participation. However, it be helpful to recognize that participatory pedagogical systems often have constructivist roots. Adopting a perspective, our paper considers three meta-practices encourage student participation: designing activities, leading others, and assessing peers. We explored consequences of these important outcomes, including content knowledge, engagement, self-efficacy, sense...
Abstract In the last decade, hydrocarbon production from shale plays has increased dramatically, which greatly impacted petroleum industry. While this benefited industry, at same time these unconventional resources have presented many challenges to oil and gas reserves evaluators. One of is predicting long-term performance life, especially in a timely reliable manner. When Arps derived hyperbolic model 1944, b-factor was assumed as constant limited values less than or equal 1.0. However,...
Abstract Becoming a sustainable and restorative company can mean rethinking the basic components of your products. This leading carpet manufacturer's innovations, including those developed in collaboration with key suppliers, have changed industry moved closer to its sustainability goals. The author explains company's seven areas focus, role innovation plays reducing negative impact on environment. He then describes Interface's approach for building supplier commitment participation these...
Beam currents computed with a general-purpose gun code can exhibit puzzling behavior as the mesh is refined. To understand such behavior, we analyze convergence, respect to element size, of basic space-charge-limited (SCL) emission algorithm in one-dimensional (1-D) finite-element electrostatic model. With current density fixed at Child's law value, find that relative error potential first vertex adjacent cathode does not converge zero, but rather increases Convergence SCL algorithm, which...
We describe a novel current accumulation algorithm for the three-dimensional self magnetic field calculation in charged-particle beam optics code. The source is represented by collection of numerically-integrated current-carrying rays. compute vector potential using edge basis functions and curl-curl formulation finite-element method. takes advantage particle tracker that happens to be ideal this application. show our compatible with singular matrix, even modest numerical integration errors....
Electron gun and multistage depressed collector design remain significant tasks in new vacuum electron device development. The ability to accurately predict performance continues improve. Recent work has been done on improving the for modeling simulation environments aid designer finding optimum configurations. As tools have improved enable first- pass success some cases, potential benefits of optimization techniques become even more significant. This paper discusses various procedures guns...
Progress on a new three-dimensional electron gun and collector design tool is reported. This simulation code designed to address the shortcomings of current beam optics modeling tools used for vacuum devices, ion sources, charged-particle transport. The specifically targets problem classes including gridded-guns, sheet-beam guns, multi-beam anisotropic collectors, with focus improved physics models. basic model in based equilibrium steady state application electrostatic PIC approximation...
Next generation vacuum electron devices under development for millimeter and sub-millimeter wavelengths are often characterized by very small features that must be precisely designed manufactured proper tube function longevity. In this regime the need automated physics-based optimization to aid designer in meeting device performance specifications is much more critical than larger, lower frequency where prototyping experimentation readily performed. Recent work has been done on improving...
As the importance of Advance Care Planning (ACP) has become well-known and accepted, health systems have begun placing more emphasis on ACP. However, many still not standardized this process, most approach ACP in a reactive-rather than proactive-manner. This paper discusses one system's innovative to that standardizes inpatient outpatient settings, while focusing proactive rather reactive orientation
The MICHELLE code is a new Finite-Element (FE) two-dimensional (2D) and three-dimensional (3D) electrostatic particle-in-cell (PIC) that has been designed to address the recent beam optics modeling simulation requirements for vacuum electron devices, ion sources, charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multi-beam guns sheet-beam guns. focus of development program combine modern finite-element techniques with improved...