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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 OSTI2018

Systems and related methods for determining self-discharge currents and internal shorts in energy storage cells

Systems and methods for determining self-discharge currents in an energy storage cell and detecting internal shorts are disclosed. A system includes a DC voltage source configured to provide a constant test voltage selected to be less than an open-circuit voltage of an energy storage cell to the energy storage cell. The system also includes a current measuring device operably coupled between the DC voltage source and the energy storage cell, and control circuitry operably coupled to the current measuring device. A method includes applying the constant test voltage, and measuring the test current flowing between the DC voltage source and the energy storage cell until after the test current switches from a negative current to a positive current. The method also includes determining a self-discharge current of the energy storage cell by analyzing the measured test current with computational models that capture physical processes tied to the test methods.

25 ENERGY STORAGE↗
DOE OSTI2019

Modelling of Ablatant Deposition from Electromagnetically Driven Radiative Pellets for Disruption Mitigation Studies

The Electromagnetic Particle Injector (EPI) concept is advanced through the simulation of ablatant deposition into ITER H-mode discharges with calculations showing penetration past the H-mode pedestal for a range of injection velocities and granule sizes concurrent with the requirements of disruption mitigation. As discharge stored energy increases in future fusion devices such as ITER, control and handling of disruption events becomes a critical issue. An unmitigated disruption could lead to failure of the plasma facing components resulting in financially and politically costly repairs. Methods to facilitate the quench of an unstable high current discharge are required. With the onset warning time for some ITER disruption events estimated to be less than 10 ms, a disruption mitigation system needs to be considered which operates at injection speeds greater than gaseous sound speeds. Such an actuator could then serve as a means to augment presently planned pneumatic injection systems. The EPI uses a rail gun concept whereby a radiative payload is delivered into the discharge by means of the JxB forces generated by an external current pulse, allowing for injection velocities in excess of 1 km/s. The present status of the EPI project is outlined, including the addition of boost magnetic coils. These coils augment the self-generated rail gun magnetic field and thus provide a more efficient acceleration of the payload. The coils and the holder designed to constrain them have been modelled with the ANSYS code to ensure structural integrity through the range of operational coil cu

disruption↗
DOE OSTI2024

Autonomous control for Heat-Pipe microreactor using Data-Driven model predictive control

To enable a self-regulating capability for heat pipe (HP) microreactors, an anticipatory control strategy achieved via model predictive control (MPC) could proactively respond to potential disturbances and deviations in operating setpoints. This paper demonstrates data-driven methods for predicting the distribution and transient of temperatures and heat fluxes at selected components and regions in a 37-HP system, based on which the optimal control actions in response to changes in user-defined setpoints can be found. We present the development and validation of linear state-space model, feedfoward, and recurrent neural networks. Here, we compare the performance of MPCs with different modeling approaches in terms of following setpoints for temperatures and averaged output heat fluxes. The accuracies of the three data-driven models are similar, but the control actions initiated by neural-network-based MPC can better adapt to drastic changes in setpoints yet generate the smallest errors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Flexible all-organic nanocomposite films interlayered with in situ synthesized covalent organic frameworks for electrostatic energy storage

Poly(vinylidene fluoride)-based terpolymers, known for having the largest dielectric constant among the existing dielectric polymers, are attractive materials for electrostatic film capacitors used in lightweight electrification systems. However, the potential of these terpolymers in film capacitor applications remains constrained by their low electrical insulating and mechanical strengths. To address these limitations, we introduced rigid covalent organic framework (COF) nanospheres into the thin films of soft terpolymers via in situ synthesis and a facile layer-by-layer solution casting method, whereby multilayer films consisting of two polymer outer layers and a COF-containing middle layer were readily obtained. The resultant all-organic thin films exhibit simultaneously high dielectric constant, enhanced breakdown strength, superior energy density (~25 J cm –3 ) at efficiencies over 80%, along with greatly improved mechanical self-supporting capability and excellent mechanical flexibility. Here, this work demonstrates the unprecedented use of COF for electrostatic energy storage, uncovering its potential for flexible electronic applications operating under high electric fields.

25 ENERGY STORAGE↗
DOE OSTI2014

Monolithic integration of a quantum emitter with a compact on-chip beam-splitter

A fundamental component of an integrated quantum optical circuit is an on-chip beam-splitter operating at the single-photon level. Here, we demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 μm), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light. The device was tested by using single photons emitted by a QD embedded in one of the input arms of the device. We verified the single-photon nature of the QD signal by performing Hanbury Brown-Twiss measurements and demonstrated single-photon beam splitting by cross-correlating the signal from the separate output ports of the directional coupler.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Nonlinear regime of electrostatic waves propagation in presence of electron-electron collisions

The effects are presented of including electron-electron collisions in self-consistent Eulerian simulations of electrostatic wave propagation in nonlinear regime. The electron-electron collisions are approximately modeled through the full three-dimensional Dougherty collisional operator [J. P. Dougherty, Phys. Fluids 7, 1788 (1964)]; this allows the elimination of unphysical byproducts due to reduced dimensionality in velocity space. The effects of non-zero collisionality are discussed in the nonlinear regime of the symmetric bump-on-tail instability and in the propagation of the so-called kinetic electrostatic electron nonlinear (KEEN) waves [T. W. Johnston et al., Phys. Plasmas 16, 042105 (2009)]. For both cases, it is shown how collisions work to destroy the phase-space structures created by particle trapping effects and to damp the wave amplitude, as the system returns to the thermal equilibrium. In particular, for the case of the KEEN waves, once collisions have smoothed out the trapped particle population which sustains the KEEN fluctuations, additional oscillations at the Langmuir frequency are observed on the fundamental electric field spectral component, whose amplitude decays in time at the usual collisionless linear Landau damping rate.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

First light from beam neutrinos on an LAPPD in ANNIE

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is both a physics experiment and a technology testbed for next-generation light-based neutrino detection. In this paper, we report the first demonstration of a fully integrated Large Area Picosecond Photodetector (LAPPD) operating in a running neutrino beam experiment. Particular focus is given to the design, commissioning, and successful deployment of the Packaged ANNIE LAPPD (PAL), a waterproof, self-triggering module incorporating fast waveform digitization and precision timing synchronized to the ANNIE detector subsystems. We identify beam-correlated LAPPD data frames consistent with charged-current neutrino interactions observed in multiple detector subsystems, establishing the first detection of neutrino-induced Cherenkov light with an LAPPD. These results validate the system-level performance of LAPPDs under realistic experimental conditions — including long-term stability, timing synchronization, and event matching with conventional PMT and muon detector systems — marking a critical step toward their deployment in future large-scale neutrino and particle detectors.

Cherenkov detectors↗
DOE OSTI2018

Vertical-Cavity Surface-Emitting 1.55-μm Lasers Fabricated by Fusion

The results of studies on fabrication of vertical-cavity surface-emitting 1.55-μm lasers by fusing AlGaAs/GaAs distributed-Bragg-reflector wafers and an active region based on thin In{sub 0.74}Ga{sub 0.26} As quantum wells grown by molecular-beam epitaxy are presented. Lasers with a current aperture diameter of 8 μm exhibit continuous lasing with a threshold current below 1.5 mA, an output optical power of 6 mW, and an efficiency of approximately 22%. Single-mode lasing with a side-mode suppression ratio of 40–45 dB is observed in the entire operating current range. The effective modulation frequency of these lasers is as high as 9 GHz and is limited by the low parasitic cutoff frequency and self-heating.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

CICART Center For Integrated Computation And Analysis Of Reconnection And Turbulence

CICART is a partnership between the University of New Hampshire (UNH) and Dartmouth College. CICART addresses two important science needs of the DoE: the basic understanding of magnetic reconnection and turbulence that strongly impacts the performance of fusion plasmas, and the development of new mathematical and computational tools that enable the modeling and control of these phenomena. The principal participants of CICART constitute an interdisciplinary group, drawn from the communities of applied mathematics, astrophysics, computational physics, fluid dynamics, and fusion physics. It is a main premise of CICART that fundamental aspects of magnetic reconnection and turbulence in fusion devices, smaller-scale laboratory experiments, and space and astrophysical plasmas can be viewed from a common perspective, and that progress in understanding in any of these interconnected fields is likely to lead to progress in others. The establishment of CICART has strongly impacted the education and research mission of a new Program in Integrated Applied Mathematics in the College of Engineering and Applied Sciences at UNH by enabling the recruitment of a tenure-track faculty member, supported equally by UNH and CICART, and the establishment of an IBM-UNH Computing Alliance. The proposed areas of research in magnetic reconnection and turbulence in astrophysical, space, and laboratory plasmas include the following topics: (A) Reconnection and secondary instabilities in large high-Lundquist-number plasmas, (B) Particle acceleration in the presence of multiple magnetic islands, (C) Gyrokinetic reconnection: comparison with fluid and particle-in-cell models, (D) Imbalanced turbulence, (E) Ion heating, and (F) Turbulence in laboratory (including fusion-relevant) experiments. These theoretical studies make active use of three high-performance computer simulation codes: (1) The Magnetic Reconnection Code, based on extended two-fluid (or Hall MHD) equations, in an Adaptive Mesh Refinement (AMR) framework, (2) the Particle Simulation Code, a fully electromagnetic 3D Particle-In-Cell (PIC) code that includes a collision operator, and (3) GS2, an Eulerian, electromagnetic, kinetic code that is widely used in the fusion program, and simulates the nonlinear gyrokinetic equations, together with a self-consistent set of Maxwell’s equations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Longitudinal Beam Dynamics with a Higher-Harmonic Cavity for Bunch Lengthening

In Sect.1 we review the conditions of operation of an HHC system assuming its stability. We first discuss the longitudinal dynamics with an active HHC and the conditions that lead to a quartic potential in the limit of small oscillations, together with formulae giving the bunch lengthening factor and the synchrotron frequency dependence on the amplitude of the synchrotron oscillations. We discuss next passive HHC operations with uniform fillings, and distinguish the case of normal-conducting HHC, where optimal conditions of operation can be met, from the case of superconducting HHC, where optimal conditions of operation can be satisfied only approximately. In Sect.2 we address the stability of the passive superconducting 3HC system of the NSLS-II storage ring via self-consistent simulations with code SPACE. The case of nominal fractional filling of 80% is compared with the case of fractional filling of 90% and with the uniform filling case. It is shown that for values of the detuning frequency in the neighborhood of the good working point discussed in Sect.2, unstable regimes of oscillation are found, with detuning frequency threshold dependent on the gap in the filling. It is shown that the instability regime is characterized by dipole and quadrupole modes of oscillation exhibiting asymptotically nonlinear saturation. A discussion of the average bunch lengthening, together with the degree of uniformity across the bunch train, achievable under stable conditions as a function of the fractional filling concludes the paper.

36 MATERIALS SCIENCE↗
DOE OSTI2023

WIRE-21 Experiment Irradiation Conditions and In-Situ Data Collection

This report summarizes the in situ data collected during three cycles of irradiation (~75 days) of the Wireless Instrumented Removable Beryllium Experiment 2021 (WIRE-21) in the removable beryllium (RB) positions of the High Flux Isotope Reactor (HFIR). The experiment was designed primarily to evaluate the effects of high neutron flux and fluence on the performance of wireless temperature and pressure sensors being developed by Westinghouse Electric Company (WEC). WEC’s sensors could provide critical data regarding the evolution of centerline temperatures and pressurization due to fission gas release during fuel operation in light-water reactors (LWRs) or various advanced reactor applications. In addition to WEC’s wireless sensors, many other sensors were interrogated, including thermocouples, self-powered neutron detectors (SPNDs), distributed fiber optic temperature sensors, and passive neutron flux wires and silicon carbide thermometry.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Analysis of Grid-Forming Inverter Controls for Grid-Connected and Islanded Microgrid Integration

Autonomous grid-forming (GFM) inverter testbeds with scalable platforms have attracted interest recently. In this study, a self-synchronized universal droop controller (SUDC) was adopted, tested, and scaled in a small network and a test feeder using a real-time simulation tool to operate microgrids without synchronous generators. We presented a novel GFM inverter control adoption to better understand the dynamic behavior of the inverters and their scalability, which can impact the distribution system (DS). This paper provides a steady-state and transient analysis of the GFM power inverter controller via simulation to better understand voltage and frequency stabilization and ensure that the critical electric loads are not affected during a prolonged power outage. The controllers of the GFM inverter are simulated in HYPERSIM to examine voltage and frequency fluctuations. This analysis includes assessing the black start capability for photovoltaic microgrids, both grid-connected and islanded, during transient fault conditions. The high photovoltaic PV penetration levels open exciting opportunities and challenges for the DS. The GFM inverter control demonstrated appropriate response times for synchronization, connection, and disconnection to the grid. The DS has become more resilient and independent of fossil fuels by increasing the penetration of inverter-based distributed energy resources (DERs).

Ward, Laura (ORCID:0000000345501581)↗
NASA NTRS1973

Self-imposed timeouts under increasing response requirements.

Three male White Carneaux pigeons were used in the investigation. None of the results obtained contradicts the interpretation of self-imposed timeouts as an escape response reinforced by the removal of unfavorable reinforcement conditions, although some details of the performances reflect either a weak control and/or operation of other controlling variables. Timeout key responding can be considered as one of several classes of behavior having a low probability of occurrence, all of which compete with the behavior maintained by positive reinforcement schedule.

Dardano, J. F.↗
NASA NTRS1983

The LSLE echocardiograph - Commercial hardware aboard Spacelab

The Life Sciences Laboratory Equipment Echocardiograph, a commercial 77020AC Ultrasound Imaging System modified to meet NASA's spacecraft standards, is described. The assembly consists of four models: display and control, scanner, scan converter, and physioamplifiers. Four separate processors communicate over an IEE-488 bus, and the system has more than 6000 individual components on 35 printed circuit cards. Three levels of self test are provided: a short test during power up, a basic test initiated by a front panel switch, and interactive tests for specific routines. Default mode operation further enhances reliability. Modifications of the original system include the replacement of ac power supplies with dc to dc converters, a slide-out keyboard (to prevent accidental operation), Teflon insulated wire, and additional shielding for the ultrasound transducer cable.

Schwarz, R.↗
NASA NTRS1986

Clay energetics in chemical evolution

Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

Coyne, L. M.↗
NASA NTRS1988

Microwave and millimeter-wave resonant-tunneling devices

Resonant-tunneling devices in microelectronic component form, whose structure is the electron analog of a Fabry-Perot resonator, encompass oscillators, self-oscillating mixers, and harmonic multipliers. The negative differential resistance characteristic of these devices has been obtained at room temperature, and resonant-tunneling transistors capable of operation in the THz-frequency range appear to be feasible. Three-terminal resonant-tunneling device development is in its infancy, as is that of devices for digital applications.

Sollner, T. C. L. Gerhard↗
NASA NTRS1993

X Ray, Far, and Extreme Ultraviolet Coatings for Space Applications

The idea of utilizing imaging mirrors as narrow band filters constitutes the basis of the design of extreme ultraviolet imagers operating at 58.4 nm and 83.4 nm. The net throughput of both imaging-filtering systems is better than 20 percent. The superiority of the EUV self-filtering camera/telescope becomes apparent when compared to previously theoretically designed 83.4-nm filtering-imaging systems, which yielded transmissions of less than a few percent and therefore less than 0.1 percent throughput when combined with at least two imaging mirrors. Utilizing the self-filtering approach, instruments with similar performances are possible for imaging at other EUV wavelengths, such as 30.4 nm. The self-filtering concept is extended to the X-ray region where its application can result in the new generation of X-ray telescopes, which could replace current designs based on large and heavy collimators.

Zukic, M.↗
NASA NTRS1993

A European mobile satellite system concept exploiting CDMA and OBP

This paper describes a novel Land Mobile Satellite System (LMSS) concept applicable to networks allowing access to a large number of gateway stations ('Hubs'), utilizing low-cost Very Small Aperture Terminals (VSAT's). Efficient operation of the Forward-Link (FL) repeater can be achieved by adopting a synchronous Code Division Multiple Access (CDMA) technique, whereby inter-code interference (self-noise) is virtually eliminated by synchronizing orthogonal codes. However, with a transparent FL repeater, the requirements imposed by the highly decentralized ground segment can lead to significant efficiency losses. The adoption of a FL On-Board Processing (OBP) repeater is proposed as a means of largely recovering this efficiency impairment. The paper describes the network architecture, the system design and performance, the OBP functions and impact on implementation. The proposed concept, applicable to a future generation of the European LMSS, was developed in the context of a European Space Agency (ESA) study contract.

Vernucci, A.↗