Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “fusion experiments”

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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

The role of thermal conduction on the size scaling of laser direct-drive implosions

Ablation pressure is a key parameter controlling laser drive performance in direct-drive inertial confinement fusion implosions. In this work, we develop a theoretical framework to clarify the role of thermal conduction in determining how ablation pressure scales with laser intensity, wavelength, and target size. We focus on a steady-state, spherically expanding plasma produced when an over-dense pellet is irradiated by a high-intensity laser. Scaling laws for ablation pressure and the mass ablation rate are derived with respect to laser intensity, wavelength, and target size. As a result, the theoretical predictions are found to be in good agreement with one-dimensional hydrodynamics simulations in spherical geometry.

Ablation↗
DOE OSTI2023

Fast Algorithms for Scientific Data Compression

Many scientific simulations and experiments generate terabytes to petabytes of data daily, necessitating data compression techniques. Unlike video and image compression, scientists require methods that accurately preserve primary data (PD) and derived quantities of interest (QoIs). In our previous work, we demonstrated the effectiveness of hybrid compression techniques that combine machine learning with traditional approaches. This paper presents innovative computational techniques aimed at expediting the compression pipeline. Our experiments, conducted on two distinct platforms with a large-scale XGC-based fusion simulation, demonstrate that the overhead incurred by these new approaches is less than one percent of the computational resources needed for the simulation.

Banerjee, Tania↗
DOE OSTI2020

Data Evaluation of Actinide Cross Sections: 230 Th and 231 Th

A new evaluation of the ENDL cross section set for Thorium (Z=90) is developed using the TALYS statistical model cross section code. The primary goal of this effort is to produce an evaluation that attempts to match as closely as possible fission cross sections developed through surrogate reaction techniques on actinide targets 230 Th and 231 Th. This evaluation effort and the processing needed to render its results into data libraries is a necessary step in making the efforts of nuclear experimentalists useful to the broad community of researchers engaged in simulations of nuclear fusion for basic and applied science. Another aspect, verification and validation against various AGEX experiments, is also presented. The end-product is an updated library that includes the latest measurements of fission cross sections for comparison against those measured via traditional techniques. All the steps in the evaluation, processing, validation and verification, and library release are described in the following sections. For completeness, the appendix contains all the parameters used in the TALYS cross section evaluation for neutrons incident on 230 Th and 231 Th.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Post-irradiation Examination of Eurofer-97 Steel Irradiated to 20 dpa at 200–400°C in HFIR under the EUROfusion (ORNL-KIT) Collaboration Program

The Oak Ridge National Laboratory/Karlsruhe Institute of Technology (ORNL/KIT) collaboration focuses on research involving irradiation experiments and post-irradiation examinations (PIE) of isotopically modified Eurofer-97 steels for fusion reactor applications. This collaboration capitalizes on ORNL’s expertise in radiation effects on materials and its capabilities in irradiation and PIE. The research aims to qualify Fe-9Cr-based Eurofer-97 steel under simulated fusion conditions, which include high doses and high transmutation rates. A unique isotopic modification technique is utilized in the research, wherein high-transmutation isotopes such as Fe-54 and Ni-58 are alloyed into the Eurofer steel to align with the expected helium production rates in fusion reactor conditions. This report presents the results of post-irradiation mechanical testing activities for the EUROFER-97/2 specimens after irradiation to ~20 dpa at various irradiation temperatures. The irradiation doses and temperatures for the ES capsules ranged from 18.4–20.4 dpa and 202–256°C, respectively. The mechanical property datasets, obtained through baseline testing and PIE of the tensile and fracture specimens, include microhardness data from 93 irradiated and non-irradiated tensile specimens and 28 irradiated bend bar specimens, uniaxial tensile property data from 45 irradiated and non-irradiated tensile specimens, and fracture toughness data from the bend bar specimens. Further data analyses provide statistical information on the microhardness values and tensile properties, as well as the reference ductile-brittle transition temperature (T 0 ) data.

36 MATERIALS SCIENCE↗
NASA NTRS2007

Fusion of Synthetic and Enhanced Vision for All-Weather Commercial Aviation Operations

NASA is developing revolutionary crew-vehicle interface technologies that strive to proactively overcome aircraft safety barriers that would otherwise constrain the full realization of the next-generation air transportation system. A piloted simulation experiment was conducted to evaluate the complementary use of Synthetic and Enhanced Vision technologies. Specific focus was placed on new techniques for integration and/or fusion of Enhanced and Synthetic Vision and its impact within a two-crew flight deck during low visibility approach and landing operations. Overall, the experimental data showed that significant improvements in situation awareness, without concomitant increases in workload and display clutter, could be provided by the integration and/or fusion of synthetic and enhanced vision technologies for the pilot-flying and the pilot-not-flying. During non-normal operations, the ability of the crew to handle substantial navigational errors and runway incursions were not adversely impacted by the display concepts although the addition of Enhanced Vision did not, unto itself, provide an improvement in runway incursion detection.

Bailey, Randall E.↗
DOE OSTI2021

FY20 LLNL Experimental Programs at Omega

In Fiscal Year 2020 (FY20), Lawrence Livermore National Laboratory’s (LLNL’s) High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted numerous campaigns on the OMEGA and OMEGA-EP (EP) laser systems. This was the 22ndyear of National Lab collaborative experiments at OMEGA since the Nova Laser at LLNL shut down in 1999, building upon prior collaborations. In FY20overall,these LLNL programs led 375target shots, with 166shots using just the OMEGA laser system and209 shots using just the EP laser system. Approximately 34% of the total number of shots (35OMEGA shots and 93EP shots) supported the Indirect Drive Inertial Confinement Fusion Campaign. The remaining 66% (131OMEGA-only shots and 116EP-only shots) were dedicated to experiments for High-Energy-Density Physics.Highlights of the various HED and ICF-ID campaigns are summarized in the following reports.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

The Materials Plasma Exposure eXperiment: Status of the Physics Basis Together With the Conceptual Design and Plans Forward

The Materials Plasma Exposure eXperiment (MPEX) is a linear plasma device that will address the plasma–material interaction (PMI) science for future fusion reactors and will enable testing of plasma-facing components (PFCs). It is designed as a steady-state device eventually delivering an ion fluence of up to 10 31 m -2 to the target. The device will be designed to handle neutron-activated materials. These capabilities should push the technical readiness level of PFCs up to six for some end-of-life aspects. In order to achieve the relevant plasma conditions, as they are expected in future fusion reactor divertors, MPEX will utilize a novel plasma source concept. This plasma source concept uses a high-power helicon (200 kW, 13.56 MHz), an electron cyclotron heating (ECH) system, which will heat electrons via electron Bernstein wave (EBW) heating (about 400 kW, 70 GHz), and an ion cyclotron heating (ICH) system (400 kW, 6–9 MHz). The physics basis for this plasma source concept including the heating physics and transport is based on experiments on Proto-MPEX. An overview of the experimental results and the physics basis will be given. The physics basis directly translates into functional requirements of MPEX and the conceptual design. The status of the conceptual design of MPEX will be shown.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Evolution of highly multimodal Rayleigh–Taylor instabilities

Rayleigh–Taylor (RT) instabilities are important fluid instabilities that arise in inertial confinement fusion (ICF) capsule implosions, and many other contexts. Multi-mode coupling is observed in experiments and plays a substantial role in material mix from RT instabilities. In this work, we study the evolution of highly multimodal perturbations (power law distribution) that approximate those found at manufactured material interfaces. We use simulations of over 2000 different perturbations in the LANL code xRAGE to identify distinct phases in the processes of bubble growth and bubble merger which can be visualized in a 2D phase portrait with clear regimes of mode growth and decay. Our results show that the dynamic evolution of the instability strongly depends on the mode of the perturbations and mode interactions. The merger process accelerates bubble growth. A non-Markovian region and a transition of the instability from: (1) initial exponential growth to (2) linear growth and to (3) quadratic growth and asymptotic behavior, are clearly captured in the phase space. We have developed a quantitative model of bubble growth that reproduces the dynamic behavior of ensembles of perturbations. Implications for ICF capsules designed for robustness against instabilities are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1989

Establishing laboratory standards for biological flight experiments

The general objective of this research was to assess the effects of exposure to simulated microgravity on ultrastructural aspects of the contractile system in chicken skeletal muscle cells. This general objective had two specific experimental components: (1) the progression of changes in cell morphology, fusion, and patterns of contractile filament organization in muscle cell cultures grown in hollow fibers in the Clinostat were evaluated, with appropriate controls; (2) to initiate experiments in which muscle cells were grown on the surface of microcarrier beads. The ultimate objective of this second portion of the work is to determine if these beads can be rotated in a bioreactor and thereby obtain a more accurate approximation of the effects of simulated microgravity on differentiated muscle cells.

Young, Ronald B.↗
DOE OSTI2024

Validation of the ERO2.0 code using W7-X and JET experiments and predictions for ITER operation

Abstract The paper provides an overview of recent modelling of global material erosion and deposition in the fusion devices Wendelstein 7-X (W7-X), JET and ITER using the Monte-Carlo code ERO2.0. For validating the modelling tool in a three-dimensional environment, W7-X simulations are performed to describe carbon erosion from the graphite test divertor units, which were equipped in operational phase OP 1.2 and analysed post-mortem. Synthetic spectroscopy of carbon line emission is compared with experimental results from the divertor spectrometer measurement system, showing a good agreement in the e-folding lengths in the radial intensity profiles of carbon. In the case of metallic wall materials, earlier modelling of the Be/W environment in JET and ITER is revisited and extended with an updated set of sputtering and reflection data, as well as including the mixing model for describing the Be/W dynamics in the divertor. Motivated by recent H/D/T isotope experiments in JET, limited and diverted configuration pulses are modelled, showing the expected trend of both Be and W erosion increasing with isotope mass. For the JET diverted configuration pulses, it is shown that Be migrates predominantly to the upper part of the inner divertor where it initially leads to strong W erosion. With longer exposure time, the growth of a Be deposited layer leads to a reduction of W erosion in that region. A similar trend is observed in simulations of the ITER baseline Q = 10 scenario, however with a more symmetric Be migration pattern leading to deposition also on the outer divertor.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1991

Mars manned fusion spaceship

Fusion Propulsion has an enormous potential for space exploration in the near future. In the twenty-first century, a usable and efficient fusion rocket will be developed and in use. Because of the great distance between other planets and Earth, efficient use of time, fuel, and payload is essential. A nuclear spaceship would provide greater fuel efficiency, less travel time, and a larger payload. Extended missions would give more time for research, experiments, and data acquisition. With the extended mission time, a need for an artificial environment exists. The topics of magnetic fusion propulsion, living modules, artificial gravity, mass distribution, space connection, and orbital transfer to Mars are discussed. The propulsion system is a magnetic fusion reactor based on a tandem mirror design. This allows a faster, shorter trip time and a large thrust to weight ratio. The fuel proposed is a mixture of deuterium and helium-3. Helium-3 can be obtained from lunar mining. There will be minimal external radiation from the reactor resulting in a safe, efficient propulsion system.

Hedrick, James↗
DOE OSTI2023

Effect of Volumetric Energy Density on Microstructure and Properties of Grade 300 Maraging Steel Fabricated by Laser Powder Bed Fusion

Here this study investigated the effect of laser powder bed fusion process parameters on the microstructure and properties of maraging steel. The results show that the process parameters can be finetuned to achieve both a high build rate/low hardness and low build rate/high hardness during fabrication, enabling the co-design of components where property gradients are desirable such as an injection molding tool where surface hardness is desired to be higher than the bulk, which needs to have higher fracture toughness.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Recent and planned hydrodynamic instability experiments on indirect-drive implosions on the National Ignition Facility

At National Ignition Facility (NIF), yield amplification due to alpha particle heating approached ~3 in the highest performing inertial confinement fusion (ICF) implosions, while yield amplification of ~15-30 is needed for ignition. Hydrodynamic instabilities are a major factor in degradation of implosions while understanding and mitigation of the instabilities are critical to achieving ignition. This article describes recent and planned hydrodynamic instability experiments with several focused platforms that have been developed to directly measure these instabilities in all phases of ICF implosions. Measurements of ripple-shock generation at OMEGA laser have indicated initial seeds for the instabilities in three ablators - plastic (CH), beryllium, and high-density carbon (HDC). Hydrodynamic Growth Radiography (HGR) platform was used to measure instability growth at the ablation front in the acceleration phase of implosions. This platform used pre-imposed 2-D perturbations for growth factor measurements at different perturbation wavelengths and was also used to measure growth of “native roughness” modulations, fill tubes, and capsule support membranes or “tents”. Also, in the acceleration phase several new experimental platforms have been or are being developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, “self-emission” and “self-backlighting” platforms were developed to measure perturbations near peak compression. This article reviews recent progress and results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Rippled shock propagation in a laser-driven target at multimegabar pressures

The evolution of non-uniform shocks produced by modulated laser irradiation or surface perturbations is relevant to studies of inertial confinement fusion and material properties at high-energy-density conditions. We present results from an experiment conducted at the OMEGA EP laser facility, where a 300 GPa shock was driven into a fused silica sample with pre-fabricated single-mode surface modulations. Using time-resolved optical velocimetry, we captured the continuous evolution of rippled shock motion, enabling a comprehensive mapping of the spatial amplitude history from formation to phase reversal in a single experiment. Initially, the ablation-driven shock inherits a fraction of the surface modulation amplitude from the sample, which subsequently grows before decaying, ultimately leading to the flattening of the rippled shock and a phase reversal. We find that two-dimensional inviscid hydrodynamic simulation of the experiment is able to qualitatively capture many aspects of the rippled shock evolution but over-predicts the initial amplitude growth. This experimental platform, capable of accommodating varying ripple wavelengths, lays the groundwork for a potential viscometry method at extreme pressures, where viscous effects manifest as differences in shock flattening times between rippled shocks of two distinct wavelengths propagating through the sample.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Relevance of Tritium Breeder Irradiation Testing in a Fusion Prototypic Neutron Source

A fusion prototypic neutron source (FPNS) will play a fundamental role in testing and developing fusion materials that can withstand the harsh fusion environment. We conducted a thorough assessment to determine whether blanket materials would benefit from FPNS testing. Because of the cross sections for the various blanket materials, lithium-containing materials can generally be tested adequately using existing fission irradiation capabilities instead of waiting for or relying solely on future FPNS experiments. However, non-lithium blanket materials, such as beryllium multipliers and flow channel inserts, should be tested under a fusion neutron spectrum.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Fully Convolutional Spatio-Temporal Models for Representation Learning in Plasma Science

We have trained a fully convolutional spatio-temporal model for fast and accurate representation learning in the challenging exemplar application area of fusion energy plasma science. The onset of major disruptions is a critically important fusion energy science issue that must be resolved for advanced tokamak plasmas such as the $25B burning plasma international thermonuclear experimental reactor (ITER) experiment. While a variety of statistical methods have been used to address the problem of tokamak disruption prediction and control, recent approaches based on deep learning have proven particularly compelling. In the present paper, we introduce further improvements to the fusion recurrent neural network (FRNN) software suite, which delivered cross-machine disruption predictions with unprecedented accuracy using a large database of experimental signals from two major tokamaks. Up to now, FRNN was based on the long short-term memory (LSTM) variant of recurrent neural networks to leverage the temporal information in the data. Here, we implement and apply the "temporal convolutional neural network (TCN)" architecture to the time-dependent input signals. Furthermore, this allows highly optimized convolution operations to carry the majority of the computational load of training, thus enabling a reduction in training time, and the effective use of high-performance computing resources for hyperparameter tuning. At the same time, the TCN-based architecture achieves better predictive performance when compared with the LSTM architecture for various tasks for a representative fusion database.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

A deep learning framework for layer-wise porosity prediction in metal powder bed fusion using thermal signatures

Abstract Part quality manufactured by the laser powder bed fusion process is significantly affected by porosity. Existing works of process–property relationships for porosity prediction require many experiments or computationally expensive simulations without considering environmental variations. While efforts that adopt real-time monitoring sensors can only detect porosity after its occurrence rather than predicting it ahead of time. In this study, a novel porosity detection-prediction framework is proposed based on deep learning that predicts porosity in the next layer based on thermal signatures of the previous layers. The proposed framework is validated in terms of its ability to accurately predict lack of fusion porosity using computerized tomography (CT) scans, which achieves a F1-score of 0.75. The framework presented in this work can be effectively applied to quality control in additive manufacturing. As a function of the predicted porosity positions, laser process parameters in the next layer can be adjusted to avoid more part porosity in the future or the existing porosity could be filled. If the predicted part porosity is not acceptable regardless of laser parameters, the building process can be stopped to minimize the loss.

42 ENGINEERING↗
NASA NTRS2003

Two-Fluid Interface Instability Being Studied

The interface between two fluids of different density can experience instability when gravity acts normal to the surface. The relatively well known Rayleigh-Taylor (RT) instability results when the gravity is constant with a heavy fluid over a light fluid. An impulsive acceleration applied to the fluids results in the Richtmyer-Meshkov (RM) instability. The RM instability occurs regardless of the relative orientation of the heavy and light fluids. In many systems, the passing of a shock wave through the interface provides the impulsive acceleration. Both the RT and RM instabilities result in mixing at the interface. These instabilities arise in a diverse array of circumstances, including supernovas, oceans, supersonic combustion, and inertial confinement fusion (ICF). The area with the greatest current interest in RT and RM instabilities is ICF, which is an attempt to produce fusion energy for nuclear reactors from BB-sized pellets of deuterium and tritium. In the ICF experiments conducted so far, RM and RT instabilities have prevented the generation of net-positive energy. The $4 billion National Ignition Facility at Lawrence Livermore National Laboratory is being constructed to study these instabilities and to attempt to achieve net-positive yield in an ICF experiment.

Niederhaus, Charles E.↗