Search NASA⌕ Search

SEARCH · Search NASA

Results for “3D Simulation”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Investigation of the decolorization efficiency of two pin-to-plate corona discharge plasma system for industrial wastewater treatment

In this article, a dual pin-to-plate high-voltage corona discharge system is introduced to study experimentally the gap distance, the contact time, the effect of pin and plate materials, the thickness of ground plate and the conductivity on the amount of Acid Blue 25 dye color removal efficiency from polluted water. A study for the optimum air gap distance between dual pin and surface of Acid Blue 25 dye solution is carried out using 3D-EM simulator to find maximum electric field intensity at the tip of both pins. The outcomes display that the best gap for corona discharge is approximately 5 mm for 15-kV source. This separation is constant during the study of other factors. In addition, an investigation of the essential reactive species responsible for oxidation of the dye organic compounds (O{sub 3} in air discharge, O{sub 3} in water, and H{sub 2}O{sub 2}) during the experimental time is conducted. Three various materials such as: stainless steel, copper and aluminum are used for pins and plate. The maximum color removal efficiencies of Acid Blue 25 dyes are 99.03, 82.04, and 90.78% after treatment time 15 min for stainless steel, copper, and aluminum, respectively. Measurement results for the impact of thickness of an aluminum ground plate on color removal competence show color removal efficiencies of 86.3, 90.78, and 98.06% after treatment time 15 min for thicknesses of 2, 0.5, and 0.1 mm, respectively. The increasing of the solution conductivity leads to the reduction of decolorization efficiency. A kinetic model is used to define the performance of corona discharge system. The models of pseudo-zero-order, pseudo-first-order, and pseudo-second-order reaction kinetics are utilized to investigate the decolorization of Acid Blue 25 dye. The rate of degradation of Acid Blue 25 dye follows the pseudo-first-order kinetics in the dye concentration.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Synthesis of Electron-Optical Systems with Compression of Sheet Beam for Terahertz TWTs

Electron-optical systems are synthesized to form a converging sheet electron beam with a compression of 15 and 20, a cross section of 0.05 × 2 mm, and a current density of 100 A/cm{sup 2} in the presence of complete magnetic shielding of field-emission cathode. Deformation of low-perveance flux in the presence of magnetic field in the drift tunnel of slow-wave structure is analyzed with the aid of 3D computer simulation of the electron-optical system with the sheet electron beam.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Analysis and Optimization of the Characteristics of Superpower Virtode Generation

We report on the results of the 3D numerical simulation of perspective design of an oscillator based on an external-feedback virtual cathode (virtode), as well as optimization of characteristics of its generation. We have analyzed the effect of beam parameters on the virtode output characteristics. In particular, we have obtained the dependence of the efficiency on the feeding voltage and on the current being injected. We have studied the effect of beam velocity premodulation and electron velocity spread on virtode generation characteristics. It has been established that the introduction of premodulation sharply increases the generation efficiency up to 13% for optimal parameters. The possibility of stable generation in the virtode at relatively large spread in electron velocities has been demonstrated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

IRAD

IRAD (Ion Irradiation and Radiation Damage) is an open-source GUI for SRIM-like vacancy production and implanted ion profile calculations. Using updated databases, IRAD is accessible at https://code.ornl.gov/liny/irad for Windows systems. It performs energy-corrected Iradina calculations, automatically determining dpa and implanted ion concentration, considering total ion fluence. Additional results like ion trajectories, final positions, stopping power distribution, etc., are available. Advanced settings permit customization of parameters such as stopping power database, incident ion angle, and 3D target simulations.

Lin, Yan-Ru [Oak Ridge National Laboratory (ORNL),↗
DOE OSTI2018

A numerical study of surface-wave-based tunnel detection at the Black Diamond Mines Regional Preserve, California

Detecting underground voids, such as old mine workings, solution cavities in karst terrain, or unknown tunnels such as illicit cross-border tunnels, is a challenging problem for geophysics and an important concern for geotechnical design, public safety, and domestic security. Seismic surface-wave-based detection methods have become increasingly popular for detecting relatively shallow and small targets; however, the theoretical limitations of these methods have thus far remained unclear. We use a suite of 3D numerical simulations inspired by a tunnel detection experiment carried out at the Black Diamond Mines Regional Preserve (BDM) in northern California. The geophysical anomalies predicted by our numerical simulations at BDM agree with field observations, and our estimates for the location of the primary tunnel target agree with historical records in the area. Using our calibrated numerical model, we perform a parametric study to determine the effect of tunnel size, depth of burial, filling material, and source characteristics to determine the range over which surface-wave backscattering and attenuation-based methods are effective. Additionally, we perform a regression analysis to determine a relationship for the maximum depth at which a tunnel may be detected via these approaches, given the target diameter, wavelength of interest, and the signal-to-noise ratio.

58 GEOSCIENCES↗
DOE OSTI2013

Drive Asymmetry, Turbulence and Ignition Failure in High Convergence ICF Implosions [Slides]

We use 2D and 3D numerical simulations with the adaptive mesh refinement Eulerian radiation-hydrocode RAGE to investigate the connection between drive asymmetry and the generation of turbulence in the DT fuel in an example ICF implosion. Long wavelength deviations from spherical symmetry in the pressure drive lead to the generation of coherent vortical structures in the DT gas and it is the three dimensional instability of these structures that in turn lead to turbulence and mix.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Experiments at Scale with In-Situ Visualization Using ParaView/Catalyst in RAGE

In this paper I describe some numerical experiments performed using the ParaView/Catalyst in-situ visualization infrastructure deployed in the Los Alamos RAGE radiation-hydrodynamics code to produce images from a running large scale 3D ICF simulation on the Cielo supercomputer at Los Alamos. The detailed procedures for the creation of the visualizations using ParaView/Catalyst are discussed and several images sequences from the ICF simulation problem produced with the in-situ method are presented. My impressions and conclusions concerning the use of the in-situ visualization method in RAGE are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

In-Situ Visualization Experiments with ParaView Cinema in RAGE

A previous paper described some numerical experiments performed using the ParaView/Catalyst in-situ visualization infrastructure deployed in the Los Alamos RAGE radiation-hydrodynamics code to produce images from a running large scale 3D ICF simulation. One challenge of the in-situ approach apparent in these experiments was the difficulty of choosing parameters likes isosurface values for the visualizations to be produced from the running simulation without the benefit of prior knowledge of the simulation results and the resultant cost of recomputing in-situ generated images when parameters are chosen suboptimally. A proposed method of addressing this difficulty is to simply render multiple images at runtime with a range of possible parameter values to produce a large database of images and to provide the user with a tool for managing the resulting database of imagery. Recently, ParaView/Catalyst has been extended to include such a capability via the so-called Cinema framework. Here I describe some initial experiments with the first delivery of Cinema and make some recommendations for future extensions of Cinema’s capabilities.

in-situ visualization↗
DOE OSTI2016

Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

Z-pinches are sources of hot dense plasma which generates powerful x-ray bursts and can been applied to various areas of high-energy-density physics (HEDP). The 26-MA Z machine is at the forefront of many of these applications, but important aspects of HEDP have been studied on generators at the 1 MA current level. Recent development of laser diagnostics and upgrade of the Leopard laser at Nevada Terawatt Facility (NTF) give new opportunities for the dense Z-pinch study. The goal of this project is the investigation of the internal structure of the stagnated Z pinch including sub-mm and micron-scale instabilities, plasma dynamics, magnetic fields, and hot spots formation and initiation. New plasma diagnostics will be developed for this project. A 3D structure and instabilities of the pinch will be compared with 3D MHD and spectroscopic modeling and theoretical analysis. The structure and dynamics of stagnated Z pinches has been studied with x-ray self-radiation diagnostics which derive a temperature map of the pinch with a spatial resolution of 70-150 µm. The regular laser diagnostics at 532 nm does not penetrate in the dense pinch due to strong absorption and refraction in trailing plasma. Recent experiments at NTF showed that shadowgraphy at the UV wavelength of 266 nm unfolds a fine structure of the stagnated Z-pinch with unprecedented detail. We propose to develop laser UV diagnostics for Z pinches with a spatial resolution <5 μm to study the small-scale plasma structures, implement two-frame shadowgraphy/interferometry, and develop methods for investigation of strong magnetic fields. New diagnostics will help to understand better basic physical processes in Z pinches. A 3D internal structure of the pinch and characteristic instabilities will be studied in wire arrays with different configurations and compared with 3D MHD simulations and analytical models. Mechanisms of “enhanced heating” of Z-pinch plasma will be studied. Fast dynamics of stagnated plasma will be studied to estimate its contribution to the Doppler broadening of x-ray lines. Development of “necks” and “hot spots” will be studied with high-resolution UV diagnostics, an x-ray streak camera, and x-ray spectroscopy. Laser initiation of hot spots in Z pinches will be tested. A Faraday rotation diagnostic at 266 nm will be applied to 1-10 MG magnetic fields. For magnetic fields B>20 MG, suggested in micropinches, Cotton-Mouton and cutoff diagnostics will be applied. A picosecond optical Kerr shutter will be tested to increase a sensitivity of UV methods for application at multi-MA Z pinches. The proposal is based on the experimental capability of NTF. The Zebra generator produces 1-1.7 MA Z-pinches with electron plasma density of 10 20 -10 21 cm -3 , electron temperature of 0.5-1 keV, and magnetic fields >10 MG. The Leopard laser was upgraded to energy of 90-J at 0.8 ns. This regime will be used for laser initiation of hot spots. A further upgrade to energy of 250-J is suggested for laser-Z-pinch interaction. A picosecond regime will be used for optical gating. A 10-TW Tomcat laser at NTF is available for the high energy UV laser probing of the Z-pinch. Two graduate students will develop new optical and x-ray diagnostics, carry out experiments, and process experimental data. Other students will be involved in the design and fabrication of loads, supporting regular optical and x-ray diagnostics, and data processing. The new plasma diagnostics may be applied to HEDP experiments at NTF and other multi-MA generators. The feasibility of the research plan is based on the experience of the scientific team in Z-pinch plasma physics, laser physics, development of new plasma diagnostics, and the experimental capability of NTF. The experimental group of Dr. V. V. Ivanov (UNR) collaborates with a group for Z pinch MHD modeling of Dr. J. P. Chittenden (Imperial College, London), and theoretical group of Dr. D. D. Ryutov (LLNL). The suggested research ideas are supported by preliminary experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Stochastic Particle Real Time Analyzer (SPARTA) Validation and Verification Suite

This report presents the test cases used to verify, validate and demonstrate the features and capabilities of the first release of the 3D Direct Simulation Monte Carlo (DSMC) code SPARTA (Stochastic Real Time Particle Analyzer). The test cases included in this report exercise the most critical capabilities of the code like the accurate representation of physical phenomena (molecular advection and collisions, energy conservation, etc.) and implementation of numerical methods (grid adaptation, load balancing, etc.). Several test cases of simple flow examples are shown to demonstrate that the code can reproduce phenomena predicted by analytical solutions and theory. A number of additional test cases are presented to illustrate the ability of SPARTA to model flow around complicated shapes. In these cases, the results are compared to other well-established codes or theoretical predictions. This compilation of test cases is not exhaustive, and it is anticipated that more cases will be added in the future.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Stochastic Particle Real Time Analyzer (SPARTA) Validation and Verification Suite

This report presents the test cases used to verify, validate and demonstrate the features and capabilities of the first release of the 3D Direct Simulation Monte Carlo (DSMC) code SPARTA (Stochastic Real Time Particle Analyzer). The test cases included in this report exercise the most critical capabilities of the code like the accurate representation of physical phenomena (molecular advection and collisions, energy conservation, etc.) and implementation of numerical methods (grid adaptation, load balancing, etc.). Several test cases of simple flow examples are shown to demonstrate that the code can reproduce phenomena predicted by analytical solutions and theory. A number of additional test cases are presented to illustrate the ability of SPARTA to model flow around complicated shapes. In these cases, the results are compared to other well-established codes or theoretical predictions. This compilation of test cases is not exhaustive, and it is anticipated that more cases will be added in the future.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

The Beam Dynamics and Beam Related Uncertainties in Fermilab Muon $g-2$ Experiment

The anomaly of the muon magnetic moment, $a_{\mu}\equiv (g-2)/2$, has played an important role in constraining physics beyond the Standard Model for many years. Currently, the Standard Model prediction for $a_{\mu}$ is accurate to 0.42 parts per million (ppm). The most recent muon $g-2$ experiment was done at Brookhaven National Laboratory (BNL) and determined $a_{\mu}$ to 0.54 ppm, with a central value that differs from the Standard Model prediction by 3.3-3.6 standard deviations and provides a strong hint of new physics. The Fermilab Muon $g-2$ Experiment has a goal to measure $a_{\mu}$ to unprecedented precision: 0.14 ppm, which could provide an unambiguous answer to the question whether there are new particles and forces that exist in nature. To achieve this goal, several items have been identified to lower the systematic uncertainties. In this work, we focus on the beam dynamics and beam associated uncertainties, which are important and must be better understood. We will discuss the electrostatic quadrupole system, particularly the hardware-related quad plate alignment and the quad extension and readout system. We will review the beam dynamics in the muon storage ring, present discussions on the beam related systematic errors, simulate the 3D electric fields of the electrostatic quadrupoles and examine the beam resonances. We will use a fast rotation analysis to study the muon radial momentum distribution, which provides the key input for evaluating the electric field correction to the measured $a_{\mu}$.

Wu, Wanwei↗
DOE OSTI2016

FY 2016 Fusion Energy Sciences (FES) Theory and Simulation Performance Target

Annual target: Predicting the magnitude and scaling of the divertor heat load width in magnetically confined burning plasmas is a high priority for the fusion program and ITER. One of the key unresolved physics issues is what sets the heat flux width at the entrance to the divertor region. Perform massively parallel simulations using 3D edge kinetic and fluid codes to determine the parameter dependence of the heat load width at the divertor entrance and compute the divertor plate heat flux applicable to moderate particle recycling conditions. Comparisons will be made with data from DIII-D, NSTX-U, and C-Mod.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Evaluation of Solver and Time Stepping Options and RIA Demonstration

This report summarizes Bison development and application in three areas: • Development of the layered 1D approach to permit its use with the reference residual convergence criterion that is widely used for 2D and 3D Bison simulations. For higher-dimensional simulations, this approach has resulted in significant improvements in robustness and solution efficiency, and it is expected to result in similar benefits for 1D simulations of light water reactor (LWR) rods. • A study on the effects of the chosen convergence tolerances on solution difficulty and accuracy was performed for a prototypical layered 1D simulation of an LWR fuel rod. The effect of convergence tolerance on iteration counts, run times, and several quantities of interest in the solution are compared for the various convergence tolerance. This study will be helpful for guiding the choice of convergence tolerances. • A demonstration of a reactivity insertion accident (RIA) simulation with Bison within the coupled VERA code was performed. The MPACT neutron transport code and the CTF thermal-hydraulic code provided inputs to Bison for a postulated control rod ejection scenario. This demonstrates the ability of the VERA environment to consider coupling effects not only for normal operation, but for accident conditions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

Auto-magnetizing (AutoMag) liners for MagLIF: Helically-wound composite liners.

Magnetized Liner Inertial Fusion (MagLIF) is an inertial confinement fusion (ICF) concept that includes a strong magnetic field embedded in the fuel to mitigate thermal conduction loss during the implosion. MagLIF experiments on Sandia's 20 MA Z Machine uses an external Helmholtz-like coil pair for fuel premagnetization. By contrast, the novel AutoMag concept employs a composite liner (cylindrical tube) with helically oriented conduction paths separated by insulating material to provide axial premagnetization of the fuel. Initially, during a current prepulse that slowly rises to %7E1 MA, current flows helically through the AutoMag liner, and sources the fuel with an axial field. Next, a rapidly rising main current pulse breaks down the insulation and current in the liner becomes purely axial. The liner and premagnetized fuel are then compressed by the rapidly growing azimuthal field external to the liner. This integrated axial-field-production mechanism offers a few potential advantages when compared to the external premagnetization coils. AutoMag can increase drive current to MagLIF experiments by enabling a lower inductance transmission line, provide higher premagnetization field (>30 T), and greatly increase radial x-ray diagnostic access. 3D electromagnetic simulations using ANSYS Maxwell have been completed in order to explore the current distributions within the helical conduction paths, the inter - wire dielectric strength properties, and the thermal properties of the helical conduction paths during premagnetization (%7E1 MA in 100ns). Three liner designs, of varying peak field strength, and associated varying risk of dielectric breakdown, will soon be tested in experiments on the %7E 1 MA, 100ns Mykonos facility. Experiments will measure B z (t) inside of the line r and assess failure mechanisms.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Direct Measurement of Backstreaming Ions from the Axis 2 Septum Dump and RF Generation

The DARHT-II accelerator produces a 2-kA, 17-MeV beam in a 1600-ns pulse. After exiting the accelerator, the pulse is sliced into four short pulses by a kicker and quadrupole septum and then transported for several meters to a high Z material target for conversion to x-rays for radiography. The un-kicked beam is diverted to a graphite dump. The interaction of this beam with the dump produces ions that propagate back to the target beamline and affect the beam properties. Coupling of the electron beam and ions to the beam dump vacuum chamber can also produce significant amounts of radiofrequency fields (RF) that disrupt the beam transport to the target. This requires a change in the nominal tune in order to minimize the heating of the carbon beam dump and suppress desorption of ions. Initially, ions are generated through stimulated desorption and ionization of the monolayers of water vapor stuck to the beam dump surface. These ions propagate upstream at high speeds and act as an electrostatic focusing lens by reducing the beam space charge. As the beam size on the dump decreases, the dump is sufficiently heated so that a surface plasma is formed and much greater quantities of ions are generated through temperature limited thermionic emission. The interaction of these ions with the beam creates RF which causes significant disruption of the beam. The results of a 3D PIC simulation show that ions can propagate back to the target beam line in about 500 ns. A beam position monitor (BPM) located just upstream of the septum was modified to include four capacitive pickups in addition to four of the usual inductive pickups. The inductive and capacitive pickups provide a measure of the beam current. The capacitive pickups are very sensitive to low velocity ions. As ions from the beam dump pass through the BPM the inductive and capacitive pickup will record two different measures of the beam current. Initial results from this BPM will be discussed along with other measurements which indicate the presence of backstreaming ions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Theory of Plasma-Cascade Instability

In this paper we present the theory of a novel micro-bunching instability occurring in charged particle beams propagating along a straight trajectory: a Plasma-Cascade Instability (PCI). This instability was confirmed by 3D numerical simulations and observed experimentally. It can by driven by variation of beam’s density and/or particle’s mobility. The PCI can strongly amplify noise in the beam and drastically reduce its quality. Conversely, such instability can drive novel high-power sources of radiation or can be used as a broadband amplifier.

43 PARTICLE ACCELERATORS↗