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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.

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At least 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Noise Erasure in Quantum-Limited Current Amplifiers

Superconducting quantum interference devices (SQUIDs) are extraordinarily sensitive to magnetic flux and thus make excellent current amplifiers for cryogenic applications. One such application of high interest to Sandia is the set-up and state read-out of quantum dot based qubits, where a qubit state is read out from a short current pulse (microseconds to milliseconds long) of approximately 100 pA, a signal that is easily corrupted by noise in the environment. A Parametric SQUID Amplifier can be high bandwidth (in the GHz range), low power dissipation (less than 1pW), and can be easily incorporated into multi-qubit systems. In this SAIL LDRD, we will characterize the noise performance of the parametric amplifier front end -- the SQUID -- in an architecture specific to current readout for spin qubits. Noise is a key metric in amplification, and identifying noise sources will allow us to optimize the system to reduce its effects, resulting in higher fidelity readout. This effort represents a critical step in creating the building blocks of a high speed, low power, parametric SQUID current amplifier that will be needed in the near term as quantum systems with many qubits begin to come on line in the next few years.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

The application of macroscopic flakes for Fe-6.5%Si bulk magnetics with superior magnetic properties

Silicon steel is the most popular crystalline soft magnetic material for motor and transformer applications. The material must be in thin thickness to reduce the eddy current loss. Conventional thin steel sheet manufacturing process starts with cast slab, followed by a series of hot/cold roll process. For transformer, thin sheet is wrapped to form the core; for motor, the sheet is stamped, coated, heat treated, and stacked to form stator/rotor. This process requires the steel to possess sufficient ductility. For Si steel, increasing Si content will improve its electrical and magnetic properties, but it will also lead to embrittlement with 3.5% Si as the limit for the conventional manufacturing processes. Despite poor mechanical properties, high Si steel, especially the one with 6.5% Si, is gaining more attention due to its lower iron loss, higher permeability, and near zero magnetostriction. To address the brittleness problem of the 6.5% Si steel, we developed a novel process, using rapid solidification to prepare thin flakes with high ductility, then using hot press to consolidate the flakes into near net shape bulk sample. The obtained Fe-6.5%Si sample with 0.2 mm thickness exhibits an iron loss of 7.2 W/kg at 400Hz and magnetic flux density of 1 Tesla, and a maximum permeability of 28,400. In addition, various coating materials and processes were investigated as inter-flake insulators for their effect on reducing the eddy current losses for thicker configuration.

Fe-6.5%Si Steel↗
DOE OSTI2022

Diamagnetic Loop Testing on DARHT-I

Diamagnetic loops (DML) can be used as a noninvasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. The loop fundamentally measures the magnetic flux excluded by a diamagnetic object. A comprehensive theory relates the rms beam radius to the excluded flux measured by the DML. We have built, and calibrated a DML apparatus. Recently, this DML has been used to measure the size of the electron beam near the final focus of the DARHT-I flash-radiography accelerator. Results are in agreement with beam transport code predictions. In this article, we review and summarize the construction, calibration, and electron-beam testing of this DML.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

First Results from Diamagnetic Loop Measurements of the DARHT-I Electron Beam [Slides]

Diamagnetic-loop (DML) measurements can inform efforts to improve radiographic resolution. DML is non-invasive, so time-resolved data is available on every shot while tuning or executing a hydrotest. The time-resolved beam size can be deduced from the DML data. LIA beam-transport dynamics affecting beam size can be monitored while testing mitigation measures (e.g., beam halo suppression). Time-resolved beam size at final focus provides immediate information about spot size enlargement due to blur, and effectiveness of mitigation efforts. DML measures magnetic flux produced by a rotating beam, so it also enables monitoring of Larmor emittance that can enlarge the spot size. Beam rotation adds in quadrature with emittance, hence “Larmor emittance." Observing zero bias-field DML flux monitors beam rotation resulting from imperfect nulling of flux linking the cathode, and/or broken LIA transport symmetry (e.g., steering, quads, etc.).

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Correcting Diamagnetic-Loop Measurements for Beam Corkscrew Motion

Diamagnetic loops (DML) are used as a non-invasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. The loop fundamentally measures the magnetic flux excluded by a diamagnetic object. One of the sources of background in these measurements is the flux produced by a straight filamentary current that is offset from the axis and tilted in the plane orthogonal to the offset. This was only a small effect in our experiments, because the beam was steered to be centered on average at the DML. However, we devoted some time to understanding and quantifying the effect, and we recount that effort in this report.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Fundamental R&D for high-Q0 650 MHz SRF cavities for hadron linacs

Upcoming projects requiring high-Q0 ~650 MHz elliptical cavities, such as MSU’s Facility for Rare Isotope Beams’ energy upgrade and Fermilab’s PIP-II, drive a need to better understand RF losses due to magnetic flux. With sample sets from two different Niobium vendors, we explore the efficacy of the fast-cooldown method, and high- temperature annealing in promoting flux expulsion. Additionally, we report the results of vertical tests comparing the effect of electropolishing and furnace baking treatments on the cavity flux sensitivity. We also directly measure the flux pinning force in niobium samples, and correlate it with different heat treatments, and flux expulsion performance.

K.McGee, K.McGee↗
DOE OSTI2025

Detonation Waves in High Explosives

A material at high temperature can react or decompose. For an energetic material, the reaction is exothermic and releases chemical energy that would further increase the temperature. Under some circumstances, when a reaction is triggered, such a reaction can propagate and the material rapidly releases a large amount of energy giving rise to an explosion. Examples of such materials are aerosols, suspensions of solid particles or liquid droplets in a gas; such as coal dust, grain dust and fuel-air explosions. Frequently, explosions are due to accidents. A spectacularly destructive example is the recent explosion of a large quantity of ammonium nitrate (thousands of tons) in Beirut, Lebanon (August 2020); see for example Beirut explosion. Ammonium nitrate is used as a fertilizer. It and the aerosols are not considered to be explosives due to the limited conditions for which an explosion can occur. An aerosol gets the oxidizer from the surrounding air. Burning requires diffusion of the oxidizer to the particle surface where the reaction occurs. A large density of small particles is required for a fast enough reaction to support an explosion. In contrast, an explosive is an energetic material with both fuel and oxidizer mixed on a molecular scale (either premixed gases or within molecules of a solid). This allows fast enough reactions over a wide range of conditions to support a self-propagating reactive wave known as a detonation wave. A detonation wave can be controlled and an explosive used for useful purposes such as in mining, construction, demolition, explosive welding, argon flash lamp, pulsed power using a magnetic flux generator [see also Goforth et al., 2015], jet cutter with shaped charge, explosive art, and generating conditions to study the response of materials at high strain rates and high pressures [see for example, Marsh, 1980]. Explosives are also used in conventional munitions and nuclear weapons. The focus of this book is on the theory and phenomenology of solid high explosives (HEs); in particular, plastic-bonded explosives (PBXs). Some aspects of detonation wave theory are needed to interpret explosive data. Hence, the theory is presented before the detonation wave phenomenology. A familiarity with fluid flow, specifically the notion of shock waves and the shock loci are assumed. In the remainder of this chapter we give a brief overview on the basic properties of detonation waves and PBXs.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Dynamic Capacitive Wireless Power Transfer System for Electric Vehicles (CRADA Final Report)

Road transportation accounts for 23% of our nation's total energy consumption, 59% of our petroleum consumption and 22% of our total emissions. Electric vehicles (EVs) have much higher well-to-wheel efficiency compared to gasoline vehicles and can reduce our dependence on oil, minimize emissions, improve local air quality and provide a platform for technological innovation and economic growth. While major progress has been made in the development of electric vehicles, their penetration remains under 1 The main hurdles in their widespread adoption are high cost, limited range and long charging times, due to limitations in battery technology. An approach to overcome these hurdles is to substantially reduce the on-board energy storage and instead deliver power wirelessly to the vehicle while it is in motion dynamic wireless power transfer (WPT). For EV charging applications, researchers have traditionally focused on inductive WPT. An issue with inductive WPT systems is that for magnetic flux guidance and shielding, they require ferrite cores, making them expensive, bulky and difficult to embed in the roadway. Under an ARPA-E IDEAS grant, the CU Boulder team has recently developed an alternative approach to WPT based on capacitive coupling that is much smaller, lighter, less expensive, and easier to embed in the roadway than inductive WPT; and have demonstrated a 1.2-kW 6.78-MHz version of this capacitive WPT system on a stationary platform. Under this seed grant program, preliminary work will be carried out on a dynamic capacitive WPT system to prepare a strong proposal for the ARPA-E OPEN 2018 FOA.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2019

Corrosion Sensors for Structural Health Monitoring of Oil and Natural Gas Infrastructure: A Review

Corrosion has been a great concern in the oil and natural gas industry costing billions of dollars annually in the U.S. The ability to monitor corrosion online before structural integrity is compromised can have a significant impact on preventing catastrophic events resulting from corrosion. This article critically reviews conventional corrosion sensors and emerging sensor technologies in terms of sensing principles, sensor designs, advantages, and limitations. Conventional corrosion sensors encompass corrosion coupons, electrical resistance probes, electrochemical sensors, ultrasonic testing sensors, magnetic flux leakage sensors, electromagnetic sensors, and in-line inspection tools. Emerging sensor technologies highlight optical fiber sensors (point, quasi-distributed, distributed) and passive wireless sensors such as passive radio-frequency identification sensors and surface acoustic wave sensors. Emerging sensors show great potential in continuous real-time in-situ monitoring of oil and natural gas infrastructure. Distributed chemical sensing is emphasized based on recent studies as a promising method to detect early corrosion onset and monitor corrosive environments for corrosion mitigation management. Additionally, challenges are discussed including durability and stability in extreme and harsh conditions such as high temperature high pressure in subsurface wellbores.

passive RFID sensors↗
DOE OSTI2022

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

High voltage converter modulators (HVCM) provide power to the accelerating cavities of the spallation neutron source (SNS) facility. HVCM experience catastrophic failures, which increase the downtime of the SNS and reduce beam time. The faults may occur due to different reasons including failures of the resonant capacitor, core saturation due to the magnetic flux, insulated-gate bipolar transistor (IGBT) failures, and others. We recently have setup a HVCM test stand to develop and test machine learning models for anomaly detection and fault prognostics. In this work, we propose binary classifiers and autoencoder architectures based on convolutional (CNN) and feedforward neural networks (FNN) to facilitate distinguishing normal from faulty waveforms coming from the HVCM during operation. The results indicate that the CNN binary classifier is the best model among the four showing very stable performance in the training and testing sets with impressive metrics of precision and recall reaching up to 99\% with a very small uncertainty. The FNN classifier shows the least performance with a large uncertainty in its metrics. The performances of the two autoencoders based on CNN and FNN were in between, showing very good performance nonetheless.

Radaideh, Majdi↗
DOE OSTI2017

Disk–Jet Connection in Active Supermassive Black Holes in the Standard Accretion Disk Regime

We study the disk–jet connection in supermassive black holes by investigating the properties of their optical and radio emissions utilizing the SDSS DR7 and the NVSS catalogs. Our sample contains 7017 radio-loud quasars with detection both at 1.4 GHz and SDSS optical spectra. Using this radio-loud quasar sample, we investigate the correlation among the jet power (${P}_{\mathrm{jet}}$), the bolometric disk luminosity (${L}_{\mathrm{disk}}$), and the black hole mass (${M}_{\mathrm{BH}}$) in the standard accretion disk regime. We find that the jet powers correlate with the bolometric disk luminosities as $\mathrm{log}{P}_{\mathrm{jet}}=(0.96\pm 0.012)\mathrm{log}{L}_{\mathrm{disk}}+(0.79\pm 0.55)$. This suggests the jet production efficiency of ${\eta }_{\mathrm{jet}}\simeq {1.1}_{-0.76}^{+2.6}\,\times {10}^{-2}$ assuming the disk radiative efficiency of 0.1, implying low black hole spin parameters and/or low magnetic flux for radio-loud quasars. But it can be also due to the dependence of this efficiency on the geometrical thickness of the accretion flow, which is expected to be small for quasars accreting at the disk Eddington ratios $0.01\lesssim \lambda \lesssim 0.3$. This low jet production efficiency does not significantly increase even if we set the disk radiative efficiency to be 0.3. We also investigate the fundamental plane in our samples among ${P}_{\mathrm{jet}}$, ${L}_{\mathrm{disk}}$, and ${M}_{\mathrm{BH}}$. In conclusion, we could not find a statistically significant fundamental plane for radio-loud quasars in the standard accretion regime.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Magnetically Induced Current Piston for Generating Extreme-ultraviolet Fronts in the Solar Corona

Single-pulse, globally propagating coronal fronts, called Extreme-ultraviolet (EUV) waves, were first confirmed in 1995 by the Extreme-ultraviolet Imaging Telescope and every observed EUV wave since has been associated with a coronal mass ejection (CME). The physical mechanism underlying these waves has been debated for two decades with wave or pseudo-wave theories being advocated. We introduce a hybrid model where EUV waves are compressional fronts driven by a reverse electric current layer induced by the time-dependent CME core current. The reverse current layer flows in a direction opposite to the CME core current and is an eddy current layer necessary to maintain magnetic flux conservation above the layer. Repelled by the core current, the reverse current layer accelerates upward so it acts as a piston that drives a compressional perturbation in the coronal regions above. Given a sufficiently fast piston speed, the compressional perturbation becomes a shock that separates from the piston when the piston slows down. Since the model relates the motion of the EUV front to CME properties, the model provides a bound for the core current of an erupting CME. The model is supported and motivated by detailed results from both laboratory experiments and ideal 3D magnetohydrodynamic simulations. Overlaps and differences with other models and spacecraft observations are reported on.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Turbulent Model of Crab Nebula Radiation

We construct a turbulent model of the Crab Nebula's nonthermal emission. The present model resolves a number of long-standing problems of the Kennel–Coroniti model: (i) the sigma problem, (ii) the hard spectrum of radio electrons, (iii) the high peak energy of gamma-ray flares, (iv) and the spatial evolution of the infrared (IR) emission. The Nebula contains two populations of injected particles: Component-I, accelerated at the wind termination shock via the Fermi-I mechanism; and Component-II, accelerated in reconnecting turbulence in highly magnetized (σ >> 1) plasma in the central part of the Crab Nebula. The reconnecting turbulence in Component-II extends from radio to gamma-rays: it accelerates radio electrons with a hard spectrum, destroys the large-scale magnetic flux (and thus resolves the sigma problem), and occasionally produces gamma-ray flares (from the largest-scale reconnection events). The model reproduces the broadband spectrum of the Crab Nebula, from low-frequency synchrotron emission in radio to inverse-Compton emission at TeV energies, as well as the spatially resolved evolution of the spectral indices in the IR and optical bands.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Accretion onto a Supermassive Black Hole Binary before Merger

While supermassive binary black holes (SMBBHs) inspiral toward merger they may also accrete matter from a surrounding disk. To study the dynamics of this system requires simultaneously describing the evolving spacetime and the magnetized plasma. We present the first relativistic calculation simulating two equal-mass, nonspinning black holes as they inspiral from a 20 M (G = c = 1) initial separation almost to merger. Our results imply important observational consequences: for instance, the accretion rate $\dot{M}$ onto the black holes first decreases and then plateaus, dropping by only a factor of ~3 despite the rapid inspiral. An estimated bolometric light curve follows the same profile, suggesting some merging SMBBHs may be significantly luminous past the predicted circumbinary disk decoupling. The minidisks are nonstandard: Reynolds, not Maxwell, stresses dominate, and they oscillate between two states. In one part of the cycle, "sloshing" streams transfer mass between minidisks, carrying kinetic energy at a rate sometimes as high as the peak minidisk bolometric luminosity. We also discover that episodic accretion drives time-varying minidisk tilts. These complex dynamics all contribute to unique cyclical behavior in the light curves of late-time inspiraling SMBBHs. The poloidal magnetic flux on the black holes is roughly constant at a dimensionless level $\phi$ ~ 2–3, but doubles just before merger; for significant black hole spin, this flux predicts powerful jets with variability driven by binary dynamics, another potentially unique electromagnetic signature. This simulation is the first to employ our multipatch infrastructure PATCHWORK MHD, decreasing the computational expense to ~3% of conventional single-grid methods' cost.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Radiation GRMHD Models of Accretion onto Stellar-mass Black Holes. II. Super-Eddington Accretion

We present a comprehensive analysis of super-Eddington black hole accretion simulations that solve the GRMHD equations coupled with angle-discretized radiation transport. The simulations span a range of accretion rates, two black hole spins, and two magnetic field topologies, and include resolution studies as well as comparisons with nonradiative models. Super-Eddington accretion flows consistently develop geometrically thick disks supported by radiation pressure, regardless of magnetic field configuration. Radiation generated in the inner disk drives substantial outflows, forming conical funnel regions that limit photon escape and result in very low radiation efficiency. The accretion flows are highly turbulent, with thermal energy transport dominated by radiation advection rather than diffusion. Angular momentum is primarily carried outward by Maxwell stress, with turbulent Reynolds stress playing a subdominant role. Both strong and weak jets are produced. Strong jets arise from sufficient net vertical magnetic flux and rapid black hole spin, and they can effectively evacuate the funnel, enabling radiation to escape through strong geometric beaming. In contrast, weak jets fail to clear the funnel, which becomes obscured by radiation-driven outflows and leads to distinct observational signatures. Spiral structures are observed in the plunging region, behaving like density waves. These super-Eddington models are applicable to a variety of astronomical systems, including ultraluminous X-ray sources, little red dots, and black hole transients.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

GRB 170817A Associated with GW170817: Multi-frequency Observations and Modeling of Prompt Gamma-Ray Emission

We introduce our observations of electromagnetic transients associated with GW170817/GRB 170817A using optical telescopes of Chilescope observatory and Big Scanning Antenna (BSA) of Pushchino Radio Astronomy Observatory at 110 MHz. The Chilescope observatory detected an optical transient of ~19 m on the third day in the outskirts of the galaxy NGC 4993; we continued observations following its rapid decrease. We put an upper limit of 1.5 × 10 4 Jy on any radio source with a duration of 10–60 s, which may be associated with GW170817/GRB 170817A. The prompt gamma-ray emission consists of two distinctive components—a hard short pulse delayed by ~2 s with respect to the LIGO signal and softer thermal pulse with T ~ 10 keV lasting for another ~2 s. The appearance of a thermal component at the end of the burst is unusual for short GRBs. Both the hard and the soft components do not satisfy the Amati relation, making GRB 170817A distinctively different from other short GRBs. Based on gamma-ray and optical observations, we determine a model for the prompt high-energy emission associated with GRB 170817A. The merger of two neutron stars creates an accretion torus of ~10 –2 M ⊙ , which supplies the black hole with magnetic flux and confines the Blandford–Znajek-powered jet. We associate the hard prompt spike with the quasispherical breakout of the jet from the disk wind. As the jet plows through the wind with subrelativistic velocity, it creates a radiation-dominated shock that heats the wind material to tens of kiloelectron volts, producing the soft thermal component.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Current Sheet Alignment in Oblique Black Hole Magnetospheres: A Black Hole Pulsar?

Abstract We study the magnetospheric evolution of a nonaccreting spinning black hole (BH) with an initially inclined split monopole magnetic field by means of 3D general relativistic magnetohydrodynamic simulations. This serves as a model for a neutron star (NS) collapse or a BH–NS merger remnant after the inherited magnetosphere has settled into a split monopole field creating a striped wind. We show that the initially inclined split monopolar current sheet aligns over time with the BH equatorial plane. The inclination angle evolves exponentially toward alignment, with an alignment timescale that is inversely proportional to the square of the BH angular velocity, where higher spin results in faster alignment. Furthermore, magnetic reconnection in the current sheet leads to exponential decay of event-horizon-penetrating magnetic flux with nearly the same timescale for all considered BH spins. In addition, we present relations for the BH mass and spin in terms of the period and alignment timescale of the striped wind. The explored scenario of a rotating, aligning, and reconnecting current sheet can potentially lead to multimessenger electromagnetic counterparts to a gravitational-wave event due to the acceleration of particles powering high-energy radiation, plasmoid mergers resulting in coherent radio signals, and pulsating emission due to the initial misalignment of the BH magnetosphere.

Astronomy & Astrophysics↗
DOE OSTI2024

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

The Korean heliospheric community, led by the Korea Astronomy and Space Science Institute (KASI), is currently assessing the viability of deploying a spacecraft at the Sun-Earth Lagrange Point L4 in collaboration with National Aeronautics and Space Administration (NASA). The aim of this mission is to utilize a combination of remote sensing and in situ instruments for comprehensive observations, complementing the capabilities of the L1 and L5 observatories. The paper outlines long-term scientific objectives, underscoring the significance of multi-point in-situ observations to better understand critical heliospheric phenomena. These include coronal mass ejections, magnetic flux ropes, heliospheric current sheets, kinetic waves and instabilities, suprathermal electrons and solar energetic particle events, as well as remote detection of solar radiation phenomena. Furthermore, the mission’s significance in advancing space weather prediction and space radiation exposure assessment models through the integration of L4 observations is discussed. This article is concluded with an emphasis on the potential of L4 observations to propel advancements in heliospheric science.

79 ASTRONOMY AND ASTROPHYSICS↗