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Green, David

Publications and source records attributed to Green, David.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Validation Studies using ELK and the Open-Source MOOSE Framework Application Zapdos for Electromagnetic Coupled Plasma Simulation

An open source simulation platform that captures electromagnetics, plasma chemistry, and fluid treatment of the plasma domain would be a powerful tool for studying low temperature plasma (LTP) phenomena. Within the Multiphysics Object-Oriented Simulation Environment (MOOSE) open source framework, ELK, CRANE, and Zapdos are combined to provide open source simulation capability for the LTP community. This talk presents continued validation of the general electromagnetic (EM) simulation tool ELK (Electromagnetic Library for Kinetics & fluids). Previous validation efforts focused on simulating standard waveguide and antenna benchmarks in vacuum and linear dielectrics, but ELK has since been coupled with the MOOSE-based plasma fluid application Zapdos [Lindsay et al 2016 J. Phys. D: Appl. Phys. 49 235204] to perform radio-frequency (rf) capacitively coupled plasma (CCP) system simulation. Plasma validation efforts initially focused on electrostatic benchmarks to demonstrate ELK-Zapdos code coupling and then moved to electromagnetic benchmarks based on interesting geometries and conditions (VHF effects in a CCP reactor, microwave heating, etc.). Results and progress in these efforts will be summarized and discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Elk: A New MOOSE Framework Application for Radio-frequency Electromagnetics

A new tool in-development for general electromagnetic (EM) simulation for modeling radio-frequency (rf) systems is presented. The primary motivation for development of this tool is to leverage the flexibility and high-performance-computing capability of the Multiphysics Object-Oriented Simulation Environment (MOOSE) Framework developed by Idaho National Laboratory (INL) for complex EM problems. A MOOSE application (or MOOSE App) enables the end user to create a fully-functional simulation scenario without needing explicit knowledge of the underlying finite-element weak form implementation. MOOSE combines the libMesh library and the PetSc suite as the finite element and solver libraries, giving a robust platform for solving highly non-linear, coupled sets of PDEs such as those found in EM and plasma physics problems. Initial validation efforts have included standard waveguide and antenna benchmarks with the current focus being field validation against the well-known capacitively-coupled GEC Reference Cell (GEC-CCP). The results of this effort will be outlined and discussed. Future work plans including cold-plasma rf wave propagation studies and coupling to the plasma fluid MOOSE App, Zapdos [Lindsay et al 2016 J. Phys. D: Appl. Phys. 49 235204], will also be discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

An electron Bernstein wave heating scheme for the Proto-MPEX linear device

Linear plasma devices, such as the Prototype Material Plasma Exposure eXperiment (Proto-MPEX), are an economic method to study plasma-material interactions under high heat and particle fluxes. The Proto-MPEX device at Oak Ridge National Laboratory is a high-density helicon plasma generator with additional resonant electron heating to study plasma-material interactions in ITER-like conditions. Here, we present modeling results of an electron Bernstein wave (EBW) heating scheme for this device using a microwave-based system. A 28 GHz injection system is available to provide power levels up to 100 kW injected into low electron temperature and high electron density plasmas. A modified version of the GENRAY ray-tracing code, GENRAY-C, has been used to determine the EBW and electron cyclotron heating wave accessibility for these overdense plasmas. Modeling has shown that greater than 80% of mode conversion from the ordinary mode to the EBW is possible for 28 GHz injection in Proto-MPEX. Calculations show that by utilizing the effects of Doppler-shifted resonance absorption, power deposition near the core is possible. Finally, significant collisional damping, leading to edge absorption, is expected to occur for neutral pressures >1.0 mTorr; however, experiments can be designed to minimize these effects.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Kinetic-j : A computational kernel for solving the linearized Vlasov equation applied to calculations of the kinetic, configuration space plasma current for time harmonic wave electric fields

We present the Kinetic-j code, a computational kernel for evaluating the linearized Vlasov equation withapplication to calculating the kinetic plasma response (current) to an applied time harmonic wave electricfield. This code addresses the need for a configuration space evaluation of the plasma current to enablekinetic full-wave solvers for waves in hot plasmas to move beyond the limitations of the traditional Fourierspectral methods. We benchmark the kernel via comparison with the standard k-space forms of the hotplasma conductivity tensor.

Green, David L.↗
DOE OSTI2018

Einstein@Home discovers a radio-quiet gamma-ray millisecond pulsar

Millisecond pulsars (MSPs) are old neutron stars that spin hundreds of times per second and appear to pulsate as their emission beams cross our line of sight. To date, radio pulsations have been detected from all rotation-powered MSPs. Here, in an attempt to discover radio-quiet gamma-ray MSPs, we used the aggregated power from the computers of tens of thousands of volunteers participating in the Einstein@Home distributed computing project to search for pulsations from unidentified gamma-ray sources in Fermi Large Area Telescope data. This survey discovered two isolated MSPs, one of which is the only known rotation-powered MSP to remain undetected in radio observations. These gamma-ray MSPs were discovered in completely blind searches without prior constraints from other observations, raising hopes for detecting MSPs from a predicted Galactic bulge population.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2018

Transboundary Water: Improving Methodologies and Developing Integrated Tools to Support Water Security

River basins for which transboundary coordination and governance is a factor are of concern to US national security, yet there is often a lack of sufficient data-driven information available at the needed time horizons to inform transboundary water decision-making for the intelligence, defense, and foreign policy communities. To address this need, a two-day workshop entitled Transboundary Water: Improving Methodologies and Developing Integrated Tools to Support Global Water Security was held in August 2017 in Maryland. The committee that organized and convened the workshop (the Organizing Committee) included representatives from the National Aeronautics and Space Administration (NASA), the US Army Corps of Engineers Engineer Research and Development Center (ERDC), and the US Air Force. The primary goal of the workshop was to advance knowledge on the current US Government and partners' technical information needs and gaps to support national security interests in relation to transboundary water. The workshop also aimed to identify avenues for greater communication and collaboration among the scientific, intelligence, defense, and foreign policy communities. The discussion around transboundary water was considered in the context of the greater global water challenges facing US national security.

Hakimdavar, Raha↗
DOE OSTI2017

Fusion Energy Sciences Exascale Requirements Review. An Office of Science review sponsored jointly by Advanced Scientific Computing Research and Fusion Energy Sciences, January 27-29, 2016, Gaithersburg, Maryland

The additional computing power offered by the planned exascale facilities could be transformational across the spectrum of plasma and fusion research — provided that the new architectures can be efficiently applied to our problem space. The collaboration that will be required to succeed should be viewed as an opportunity to identify and exploit cross-disciplinary synergies. To assess the opportunities and requirements as part of the development of an overall strategy for computing in the exascale era, the Exascale Requirements Review meeting of the Fusion Energy Sciences (FES) community was convened January 27–29, 2016, with participation from a broad range of fusion and plasma scientists, specialists in applied mathematics and computer science, and representatives from the U.S. Department of Energy (DOE) and its major computing facilities. This report is a summary of that meeting and the preparatory activities for it and includes a wealth of detail to support the findings. Technical opportunities, requirements, and challenges are detailed in this report (and in the recent report on the Workshop on Integrated Simulation). Science applications are described, along with mathematical and computational enabling technologies. Also see http://exascaleage.org/fes/ for more information.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Verification of a Configuration Space Method for Evaluating the All-Orders Linear Kinetic Plasma Response to RF Power

Progress towards verification of a configuration space algorithm for evaluating the linear kinetic plasma current response to applied radio-frequency power is presented. This follows a previously published [1] verification of the parallel-only response, by verifying the perpendicular response required for much of the ion-and electron-cyclotron range of frequencies. In particular, we use the Colestock-Kashuba fast-wave to ion-Bernstein-wave benchmark [2] where we show that the Kinetic-J computational kernel is able to reproduce a known reference solution calculated via the AORSA full-wave code [3]. We also discuss the computational and scaling aspects of this novel approach, as well as the difficulties presented by the temporal scales in this multi-species problem.

Green, David↗
NASA NTRS2016

The NASA Applied Sciences Program: Volcanic Ash Observations and Applications

Since 2000, the NASA Applied Sciences Program has been actively transitioning observations and research to operations. Particular success has been achieved in developing applications for NASA Earth Observing Satellite (EOS) sensors, integrated observing systems, and operational models for volcanic ash detection, characterization, and transport. These include imager applications for sensors such as the MODerate resolution Imaging SpectroRadiometer (MODIS) on NASA Terra and Aqua satellites, and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NASA/NOAA Suomi NPP satellite; sounder applications for sensors such as the Atmospheric Infrared Sounder (AIRS) on Aqua, and the Cross-track Infrared Sounder (CrIS) on Suomi NPP; UV applications for the Ozone Mapping Instrument (OMI) on the NASA Aura Satellite and the Ozone Mapping Profiler Suite (OMPS) on Suomi NPP including Direct readout capabilities from OMI and OMPS in Alaska (GINA) and Finland (FMI):; and lidar applications from the Caliop instrument coupled with the imaging IR sensor on the NASA/CNES CALIPSO satellite. Many of these applications are in the process of being transferred to the Washington and Alaska Volcanic Ash Advisory Centers (VAAC) where they support operational monitoring and advisory services. Some have also been accepted, transitioned and adapted for direct, onboard, automated product production in future U.S. operational satellite systems including GOES-R, and in automated volcanic cloud detection, characterization and alerting tools at the VAACs. While other observations and applications remain to be developed for the current constellation of NASA EOS sensors and integrated with observing and forecast systems, future requirements and capabilities for volcanic ash observations and applications are also being developed. Many of these are based on technologies currently being tested on NASA aircraft, Unmanned Aerial Systems (UAS) and balloons. All of these efforts and the potential advances that will be realized by integrating them are shared in this presentation.

Murray, John J.↗
NASA NTRS1992

Determining the transferability of flight simulator data

This paper presented a method for collecting and graphically correlating subjective ratings and objective flight test data. The method enables flight-simulation engineers to enhance the simulator characterization of rotor craft flight in order to achieve maximum transferability of simulator experience.

Green, David↗
NASA NTRS1990

Software For Three-Dimensional Space-Shuttle Imagery

Flight Dynamics/Space Transportation System Three-Dimensional Monitor System (3-D Mon) is real-time graphical mission-monitoring software tool. Main objective to compute and display realistic three-dimensional solid model image of Space Shuttle, remote-manipulator system, payload, and surroundings from real-time Space Shuttle telemetry data. Ability to support spacecraft other than Space Shuttle also incorporated. Display shows almost any desired perspective. Written in C programming language.

Pittarelli, Ernest J.↗