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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Space Electronic Test Engineering

The Space Power and Propulsion Test Engineering Branch at NASA Glenn Research center has the important duty of controlling electronic test engineering services. These services include test planning and early assessment of Space projects, management and/or technical support required to safely and effectively prepare the article and facility for testing, operation of test facilities, and validation/delivery of data to customer. The Space Electronic Test Engineering Branch is assigned electronic test engineering responsibility for the GRC Space Simulation, Microgravity, Cryogenic, and Combustion Test Facilities. While working with the Space Power and Propulsion Test Engineering Branch I am working on several different assignments. My primary assignment deals with an electrical hardware unit known as Sunny Boy. Sunny Boy is a DC load Bank that is designed for solar arrays in which it is used to convert DC power form the solar arrays into AC power at 60 hertz to pump back into the electricity grid. However, there are some researchers who decided that they would like to use the Sunny Boy unit in a space simulation as a DC load bank for a space shuttle or even the International Space Station hardware. In order to do so I must create a communication link between a computer and the Sunny Boy unit so that I can preset a few of the limits (such power, set & constant voltage levels) that Sunny Boy will need to operate using the applied DC load. Apart from this assignment I am also working on a hi-tech circuit that I need to have built at a researcher s request. This is a high voltage analog to digital circuit that will be used to record data from space ion propulsion rocket booster tests. The problem that makes building this circuit so difficult is that it contains high voltage we must find a way to lower the voltage signal before the data is transferred into the computer to be read. The solution to this problem was to transport the signal using infrared light which will lower the voltage signal down low enough so that it is harmless to a computer. Along with my involvement in the Space Power and Propulsion Test Engineering Branch, I am obligated to assist all other members of the branch in their work. This will help me to strengthen and extend my knowledge of Electrical Engineering.

Chambers, Rodney D.↗
NASA NTRS1974

Charged particle measurements on a 30-CM diameter mercury ion engine thrust beam

Measurements of both thrust ions and charge exchange ions were made in the beam of a 30 centimeter diameter electron bombardment mercury ion thruster. A qualitative model is presented which describes magnitudes of charge exchange ion formation and motions of these ions in the weak electric field structure of the neutralized thrust beam plasma. Areas of agreement and discrepancy between observed and modeled charge exchange properties are discussed.

Sellen, J. M., Jr.↗
DOE OSTI2023

Plasma-assisted deposition and characterization of Al 2 O 3 dielectric layers on (001) β -Ga 2 O 3

In this work, we have investigated plasma-assisted deposition of Al 2 O 3 on HVPE (001) β-Ga 2 O 3 and evaluated the dielectric quality from electrical measurements on fabricated metal-oxide-semiconductor (MOS) capacitors. The interface structure and crystallinity of the films were investigated as a function of the growth temperature. The dielectric/semiconductor interfaces were found to have reverse breakdown electric fields up to 5.3 MV/cm in the β-Ga 2 O 3 , with relatively low hysteresis in capacitance–voltage and low leakage current. We determined a negative fixed interface charge density at the interface from analysis of thickness-dependent capacitance voltage data. In conclusion, this study shows the advantage of using plasma-assisted deposition to achieve high breakdown strength Al 2 O 3 /β-Ga 2 O 3 MOS structures for device application purposes.

42 ENGINEERING↗
DOE OSTI2021

Numerical Investigation of Enhanced Dehumidification Processes By Using Dielectrophoresis Principles in Moist Airflows

Dispersed particle-laden flows are encountered in many building and industrial applications, such as flow in a fluidized bed, hydrocarbon transportation in pipelines, and the fouling of air-cooled heat exchangers (Kuruneru et al., 2016; Ray et al., 2019; Wang et al., 2019). Computational fluid dynamic (CFD) models have been developed in recent years to depict particle-fluid and particle-particle interactions in laminar or turbulent flows with increasing accuracy and stability. One particular particle-laden system of interest for moisture control is electrically-enhanced condensation in air and water droplet flows. Electrically-enhanced condensation consists of the use of highly charged water droplets injected in the moist air. The droplets become electric seeds that attract polar water vapor molecules to their surfaces and promote condensation. The nucleation and growth of the charged droplets deplete the vapor phase near a droplet, which is compensated for by the dielectrophoresis flow and diffusion. Dielectrophoresis flow involves surrounding vapor at a distance of about 10 to 100 nm for droplets charged by an electrospray compared to ~2 nm for a single electron charge in a droplet. As the vapor molecules collapse on the surface of the droplets, their initial electrical charge decreases with time due to the neutralization of the ions. While the physics of this phenomena is well known, engineering models for predicting the condensation rates are not available. This work computationally investigates dehumidification of moist airflow in a converging rectangular duct. The objective is to develop an engineering model that predicts water vapor condensation by employing dielectrophoresis principles. We construct a Computational Fluid Dynamics (CFD) model of the duct with electrically-enhanced condensation. The model is implemented in the open-source software OpenFOAM. We utilize the Multi-Phase Particle-In-Cell (MP-PIC) method coupled with a Population Balance Equation (PBE) approach to simulate the particle-laden system. This methodology is an Eulerian-Lagrangian approach used to simulate the droplets' behavior in the humid air. The MP-PIC approach (Andrews and O'Rourke, 1996) mitigates the computational cost by parceling several fundamental particles with similar properties (such as types, sizes, and temperature) into one computational particle. Thus, the billions of particles can be substituted by millions of computational particles without significant loss of information. The PBE was considered with the Lagrangian frame to combine the particle distribution function used in MP-PIC (Kim et al., 2020). This approach preserves mass and energy conservation between the phases in the Eulerian and Lagrangian structures. The PBE in this procedure was directly linked to the discrete parcels, making the simulation of the particle distribution computationally efficient and robust. The MP-PIC-PBE approach used in the present work was applied to the dehumidification of air. Water droplets were injected in the air stream and forced to grow according to experimentally derived correlation. The experiments were conducted on a converging duct with the same geometry and boundary conditions used to build the CFD model. This approach enabled us to approximate the effect of dielectrophoresis phenomena on the droplet and air interface. This presentation will discuss the details of the new CFD model built for the duct, the implementation of the model in OpenFOAM CFD programming language, and the experimental validation of the newly developed model. The results revealed a moderate yet measurable increase in droplet diameter due to water vapor condensation at the vapor-liquid interface of the electrically charged droplets' surface. The seed water droplet particles grew in size by capturing the water vapor in the surrounding air. The OpenFOAM model predicted reductions of humidity in the air from 5 to 10 percent.

Yel Mahi, Maliha↗
NASA NTRS1973

The hollow cathode in the quasi-steady MPD discharge

A large hollow cathode has been operated in a quasi-steady MPD discharge over a range of current from 7 to 30 kA and argon mass flow from 0.04 to 6.0 g/sec. The 1.3-cm-i.d. cathode cavity attains steady emission characteristics in some tens of microseconds without the assistance of auxiliary heating, low work function inserts, or external keeper electrodes. Measured current and potential distributions within the cavity reveal that the current attaches in a zone 1 to 2 cm long with a surface current density greater than 1000 A/sq cm and a local axial electric field less than 10 V/cm. Electron densities within the cavity, estimated from spectroscopic records, are above 10 to the 17th power per cu cm, at least one order of magnitude greater than has been reported for either ion engine hollow cathodes or conventional solid cathodes in similar arc discharges.

Von Jaskowsky, W. F.↗
NASA NTRS1976

Gait Analysis Laboratory

Complete motion analysis laboratory has evolved out of analyzing walking patterns of crippled children at Stanford Children's Hospital. Data is collected by placing tiny electrical sensors over muscle groups of child's legs and inserting step-sensing switches in soles of shoes. Miniature radio transmitters send signals to receiver for continuous recording of abnormal walking pattern. Engineers are working to apply space electronics miniaturization techniques to reduce size and weight of telemetry system further as well as striving to increase signal bandwidth so analysis can be performed faster and more accurately using a mini-computer.

Source record↗
DOE OSTI2023

Directly monitoring the shift in corrosion mechanisms of a model FeCrNi alloy driven by electric potential

Abstract Stainless steels are used in a myriad of engineering applications, including construction, automobiles, and nuclear reactors. Developing accurate, predictive mechanistic models for corrosion and electrochemical corrosion kinetics of stainless steels has been a topic of research studies over many decades. Herein, we quantified the aqueous corrosion kinetics of a model austenitic Fe–18Cr–14Ni (wt%) alloy in the presence and absence of applied potential using systematic in situ electrochemical atomic force microscopy (EC-AFM) and transmission electron microscopy (TEM). Without an applied bias, vertical dissolution of corrosion pits is controlled by the surface kinetics/diffusion hybrid mechanism, whereas lateral dissolution is diffusion controlled. When an electric bias is applied, the increase in corrosion rate is dominated by the nucleation of new pits. These insights gained by the in situ EC-AFM will allow applications of this method for a quantitative understanding of corrosion of a wider class of materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Engineering Electrical Conductivity in Stable Zirconium-Based PCN-222 MOFs with Permanent Mesoporosity

Electrically conductive metal–organic frameworks (MOFs) featuring zirconium-based nodes are of great interest for electrochemical and optoelectronic applications due to their exceptional thermal and chemical stability, although the number of such MOFs remains limited. Here in this paper, we demonstrate that electron deficient molecules such as transition metal(IV) bis(dicarbollide) (TM IV (C 2 B 9 H 11 ) 2 ; TM IV CB for short, where TM = Ni, Pd, and Pt) or C 60 , spatially infiltrated in the microporous channels of the zirconium-based porphyrinic MOFs PCN-222 and PCN-222-Zn, generate highly stable and electrically conductive frameworks in which the mesopores remain accessible to other guests. Solid-state density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations indicate incorporation of Ni IV CB and C 60 in the MOF micropores is energetically and structurally feasible. Interestingly, in contrast to the free species, strong donor–acceptor interactions between the MOF and Ni IV CB restrain it to a single conformation. Calculated electronic structures and charge-hopping conduction probabilities illustrate that efficient charge-transfer (CT) from photoexcited linkers to the guest molecules facilitates charge hopping in the framework, making the MOFs electrically conductive. The donor–acceptor conjugates also enhance exciton dissociation at their heterojunctions, fostering the formation of long-lived electron-trapped states with potential utility for photo- and electrochemical devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Intercell moiré exciton complexes in electron lattices

Excitons, Coulomb-bound electron–hole pairs, play a crucial role in both optical excitation and correlated phenomena in solids. When excitons interact with other quasiparticles, few- and many-body excited states can appear. Here, in this work, we report an interaction between exciton and charges enabled by unusual quantum confinement in two-dimensional moiré superlattices, which results in many-body ground states composed of moiré excitons and correlated electron lattices. In an H-stacked (60 o -twisted) WS 2 /WSe 2 heterobilayer, we found an interlayer moiré exciton whose hole is surrounded by its partner electron’s wavefunction distributed among three adjacent moiré traps. This three-dimensional excitonic structure enables large in-plane electrical quadrupole moments in addition to the vertical dipole. Upon doping, the quadrupole facilitates the binding of interlayer moiré excitons to the charges in neighbouring moiré cells, forming intercell charged exciton complexes. Our work provides a framework for understanding and engineering emergent exciton many-body states in correlated moiré charge orders.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Highlights of the Test of the QUiet Electric Engine (QUEEN V1) in the NASA GRC Acoustical Testing Laboratory (ATL)

This presentation for the NASA Acoustics Technical Working Group meeting highlights preliminary acoustic and thermal test results from the Quiet Electric Engine (QUEEN V1) experiment recently performed in the NASA Glenn Research Center Acoustical Testing Laboratory. The QUEEN V1 features a single Commercial-Off-the-Shelf fan with an Outlet Guide Vane. Four inlet duct acoustic liners were tested. Electronic Speed Controller (ESC) temperatures were recorded for two different cooling methods: air cooling and a cold plate.

Acoustics↗
NASA NTRS1991

Isothermal Dendritic Growth Experiment - Science, engineering, and hardware development for USMP space flights

The Isothermal Dendritic Growth Experiment (IDGE) has been designed to provide microgravity data on dendritic growth for a critical test of theory. This paper updates progress on constructing a crystal growth chamber suitable for space flight. The IDGE chamber is constructed from glass and stainless steel and is hermetically sealed by electron beam welds and glass-metal seals. Initial tests of the chambers sample's melting point plateau show that the new chamber design is capable of preserving the 99.9995 percent purity of succinonitrile. Dendrite growth can be initiated in the center of the IDGE chamber by means of thermo-electric coolers and a capillary injector tube (stinger). The new IDGE chamber is ready for fully integrated tests with the prototype IDGE engineering hardware at NASA's Lewis Research Center.

Glicksman, M. E.↗
DOE OSTI2025

Harnessing ferro-valleytricity in pentalayer rhombohedral graphene for memory and compute

Two-dimensional materials with multiple degrees of freedom, including spin, valleys, and orbitals, open up an exciting avenue for engineering multifunctional devices. Beyond spintronics, these degrees of freedom can lead to novel quantum effects such as valley-dependent Hall effects and orbital magnetism, which could revolutionize next-generation electronics. However, achieving independent control over valley polarization and orbital magnetism has been a challenge due to the need for large electric fields. A recent breakthrough involving pentalayer rhombohedral graphene has demonstrated the ability to individually manipulate anomalous Hall signals and orbital magnetic hysteresis, forming what is known as a valley-magnetic quartet. Here, we leverage the electrically tunable ferro-valleytricity of pentalayer rhombohedral graphene to develop nonvolatile memory and in-memory computation applications. We propose an architecture for a dense, scalable, and selector-less nonvolatile memory array that harnesses the electrically tunable ferro-valleytricity. In our designed array architecture, nondestructive read and write operations are conducted by sensing the valley state through two different pairs of terminals, allowing for independent optimization of read/write peripheral circuits. The power consumption of our PRG-based array is remarkably low, with only ∼6 nW required per write operation and ∼2.3 nW per read operation per cell. This consumption is orders of magnitude lower than that of the majority of state-of-the-art cryogenic memories. Additionally, we engineer in-memory computation by implementing majority logic operations within our proposed nonvolatile memory array without modifying the peripheral circuitry. In conclusion, our framework presents a promising pathway toward achieving ultra-dense cryogenic memory and in-memory computation capabilities.

2D materials↗
DOE OSTI2022

Morphological-informed Thermal Property Prediction in the Engineering Domain

Using first-principle, atomic scale methods to predict thermal carrier (electron and phonon) behavior at nanoscale yields highly resolved thermal properties. Density functional theory simulations can model myriad effects on the transport of phonons and electrons (e.g., phonon and electron coupling, electron correlation, defect presence, carrier scattering), and yield thermal properties for small geometric domains such as thermal and electrical conductivity, or heat capacity. While these thermal properties are accurate in atomistic and nanoscopic systems, they must be scaled up to the microstructural domain to be a useful predictor for experimental basis, as the microscale is where myriad changes and physical phenomenon occur within a material (e.g., grain boundaries, precipitate aggregations, interfaces, defect clusters). My talk will discuss the necessity of thermal property predictions for nuclear fuels applications and more. Additionally I will discuss the necessity in developing multi-physics, multi-scale methods for future applications in predictions for not only nuclear fuels, but other materials applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Light-induced ferromagnetism in moiré superlattices

Many-body interactions between carriers lie at the heart of correlated physics. The ability to tune such interactions would allow the possibility to access and control complex electronic phase diagrams. Recently, two-dimensional moiré superlattices have emerged as a promising platform for quantum engineering such phenomena. The power of the moiré system lies in the high tunability of its physical parameters by adjusting the layer twist angle, electrical field, moiré carrier filling and interlayer coupling. In this work, we report that optical excitation can highly tune the spin–spin interactions between moiré-trapped carriers, resulting in ferromagnetic order in WS 2 /WSe 2 moiré superlattices. Near the filling factor of v = 1/3 (that is, one hole per three moiré unit cells), as the excitation power at the exciton resonance increases, a well-developed hysteresis loop emerges in the reflective magnetic circular dichroism signal as a function of magnetic field, a hallmark of ferromagnetism. The hysteresis loop persists down to charge neutrality, and its shape evolves as the moiré superlattice is gradually filled, indicating changes of magnetic ground state properties. The observed phenomenon points to a mechanism in which itinerant photoexcited excitons mediate exchange coupling between moiré-trapped holes. This exciton-mediated interaction can be of longer range than direct coupling between moiré-trapped holes, and thus magnetic order arises even in the dilute hole regime. This discovery adds a dynamic tuning knob to the rich many-body Hamiltonian of moiré quantum matter.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Elimination of the bias-stress effect in ligand-free quantum dot field-effect transistors

Field-effect transistors (FETs) made from colloidal quantum dot (QD) solids commonly suffer from current–voltage hysteresis caused by the bias-stress effect (BSE), which complicates fundamental studies of charge transport in QD solids and the use of QD FETs in electronics. Here, we show that the BSE can be eliminated in n-channel PbSe QD FETs by first removing the QD ligands with a dose of H 2 S gas and then infilling the QD films with alumina by atomic layer deposition (ALD). The H 2 S-treated, alumina-infilled FETs have stable, hysteresis-free device characteristics (total short-term stability), indefinite air stability (total long-term stability), and a high electron mobility of up to 14 cm 2 V −1 s −1 , making them attractive for QD circuitry and optoelectronic devices. The BSE-free devices are utilized to conclusively establish the dependence of the electron mobility on temperature and QD diameter. We demonstrate that the BSE in these devices is caused by both electron trapping at the QD surface and proton drift within the film. The H 2 S/alumina chemistry produces ligand-free PbSe/PbS/Al 2 O 3 interfaces that lack the traps that cause the electronic part of the BSE, while full alumina infilling stops the proton motion responsible for the ionic part of the BSE. In conclusion, our matrix engineering approach should aid efforts to eliminate the BSE, boost carrier mobilities, and improve charge transport in other types of nanocrystal solids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Tailoring Interlayer Coupling in Few-Layer MoS 2 with Stacking Configuration

Here we manipulated the stacking configuration of a few-layer MoS 2 to investigate the impact of interlayer coupling on electrical band engineering. By simultaneously synthesizing two distinct stacking types of MoS2 islands, wedding cake (W) and spiral (S), on the same substrate, we explored layer-dependent electrical properties under identical experimental conditions. We used multiple scanning probe microscopy techniques to map local electronic properties with respect to the number of layers, stacking configurations, and local heterogeneities. First-principles calculations verified the role of distinct interlayer coupling in terms of the interlayer distance. Our findings highlight the critical role of interlayer coupling in applications of transition metal dichalcogenides.

36 MATERIALS SCIENCE↗
NASA NTRS2009

Insulating Foams Save Money, Increase Safety

Scientists at Langley Research Center created polyimide foam insulation for reusable cryogenic propellant tanks on the space shuttle. Meanwhile, a small Hialeah, Florida-based business, PolyuMAC Inc., was looking for advanced foams to use in the customized manufacturing of acoustical and thermal insulation. The company contacted NASA, licensed the material, and then the original inventors worked with the company's engineers to make a new material that was better for both parties. The new version, a high performance, flame retardant, flexible polyimide foam, is used for insulating NASA cryogenic propellant tanks and shows promise for use on watercraft, aircraft, spacecraft, electronics and electrical products, automobiles and automotive products, recreation equipment, and building and construction materials.

Source record↗
DOE OSTI2021

Universal phase dynamics in VO 2 switches revealed by ultrafast operando diffraction

Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is crucial for uncovering the fundamental limits of device operation. Using stroboscopic electron diffraction, we perform synchronized time-resolved measurements of atomic motions and electronic transport in operating vanadium dioxide (VO 2 ) switches. We discover an electrically triggered, isostructural state that forms transiently on microsecond time scales, which is shown by phase-field simulations to be stabilized by local heterogeneities and interfacial interactions between the equilibrium phases. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway. Our results establish electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials, opening avenues for engineering dynamical behavior in nanoelectronics.

36 MATERIALS SCIENCE↗