Results for “Electrical propertied and parameters” — Page 15

DOE OSTI2022

Understanding the surface wave characteristics using 2D particle-in-cell simulation and deep neural network

Here, the characteristics of the surface waves along the interface between a plasma and a dielectric material have been investigated using kinetic particle-in-cell simulations. A microwave source of GHz frequency has been used to trigger the surface wave in the system. The outcome indicates that the surface wave gets excited along the interface of plasma and the dielectric tube and appears as light and dark patterns in the electric field profiles. The dependency of radiation pressure on the dielectric permittivity and supplied input frequency has been investigated. Further, we assessed the capabilities of neural networks to predict the radiation pressure for a given system. The proposed deep neural network model is aimed at developing accurate and efficient data-driven plasma surface wave devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

Guiding Self-Assembly of Active Colloids by Temporal Modulation of Activity

Self-organization phenomena in ensembles of self-propelled particles open pathways to the synthesis of new dynamic states not accessible by traditional equilibrium processes. The challenge is to develop a set of principles that facilitate the control and manipulation of emergent active states. In this study, we report that dielectric rolling colloids energized by a pulsating electric field self-organize into alternating square lattices with a lattice constant controlled by the parameters of the field. We combine experiments and simulations to examine spatiotemporal properties of the emergent collective patterns and investigate the underlying dynamics of the self-organization.We reveal the resistance of the dynamic lattices to compression and expansion stresses leading to a hysteretic behavior of the lattice constant. The general mechanism of pattern synthesis and control in active ensembles via temporal modulation of activity can be applied to other active colloidal systems.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Functional Nanomaterials with Tunable Plasmonic and Emittive Properties (Final Project Report)

The goal of the project is on understanding the principles of non-covalent assembling of tunable functional materials with various nanocrystals in order to control light-matter interactions by changing localized interfacial refractive properties, coupling parameters, or the ionic environment of surrounding media. We explore novel soft functional matrices with controlled physical properties via the application of light, mechanical stresses, ionic environment, and electrical potential. These functional matrices is used in conjunction with novel anisotropic inorganic nanostructures such as noble metal/metal alloy anisotropic nanostructures with complex optical properties (multiple LSPR modes) and quantum dots with light-emissive or absorbing properties in a broad spectral range from the UV to the NIR for efficient solar energy absorption and light conversion.

36 MATERIALS SCIENCE↗

NASA NTRS1987

Study of Plasma Motor Generator (PMG) tether system for orbit reboost

Detailed designs were produced for a 2 kW plasma motor generator tether system based largely on existing hardware and hardware designs. Specifically, the hollow cathode design and electronics are derived from ion propulsion equipment. A prototype tether was constructed and will be tested for deployment, strength, resistance to breakage and abrasion and electrical properties. In addition, laboratory development models of the electronics will be used to operate two plasma motor generator hollow cathode assemblies with this tether to verify electrical performance parameters for the complete system. Results show that a low cost demonstration of a plasma motor generator tether system appears to be feasible by the middle of the 1990s.

Source record↗

NASA NTRS2004

Ceramic Interconnects with Low Sintering Temperature

Ceramic interconnects for use in solid oxide he1 cells are expected to operate between 900 to approximately 1000 C, sinter below 1400 C to allow co-firing and meet a number thermal mechanical requirements. The pervoskite type (ABO3) lanthanum chromite based materials have emerged as a leading candidate that will meet these criteria by varying the composition on the A and B sites. A need therefore exists to determine this material's temperature dependent electrical and mechanical properties with respect to these site substitutions. In this investigation oxide powders were prepared by the glycine-nitrate process. Ionic substitutions were carried out on A sites with Ca or Sr, and B sites with Co and Al, respectively. Only stoichiometric compositions were considered for the sake of stability. The powders and their ability to sinter were investigated by XRD, SEM, dilatometry and density measurements. The sintered materials were further examined by SEM, thermal expansion and electric conductivity measurements in order to elucidate the resulting microstructure, electrical and mechanical properties. In addition quantum mechanical calculations were performed to obtain insight into the effects of these dopants on the materials electronic band structure and lattice parameter.

Zhong, Zhi-Min↗

NASA NTRS2018

Electrical Properties of Unidirectional Carbon Fiber Reinforced Epoxy-Graphene Composites

This paper aims at establishing connections between electrical resistivity and stresses in carbon fiber reinforced epoxy-graphene composites. To avoid the interconnection of multiple parameters, we examined composite specimens consisting of a single strand or tow (12,000 carbon fiber filaments) embedded in an epoxy matrix containing up to 1.0 wt% of graphene (TG679) particles. The specimens show resistance increase with the tensile stress. The characteristic of the dependence varies with the content of graphene particles, tending to be linear as the percentage of graphene content increases. We did not observe any significant changes in the ultimate strength of the composite with an increase of the graphene particles concentration.

Daniel Wentzel↗

NASA NTRSDate not supplied

Analysis of Glint During the Artemis I Mission

Glint occurs when light reflects off a specular (mirror-like) surface. In the context of spacecraft, glinted light can land in places that may cause unintended, negative effects. During the Artemis I mission in November and December of 2022, glint was forced to occur in order to study its effect on the Orion electrical power system (EPS). With the vehicle in a nose-to-sun attitude, light was reflected off the crew module’s reflective skin and onto forward pointed solar array wings (SAWs), producing more current than would result from direct solar flux alone. The goal of this in-flight test was to anchor the models previously used to study this phenomenon and to understand what parameters have the most significant impact on glinted current generation. In this presentation, the two models used for estimating optical properties for glint analysis will be discussed, as well as a worst-case study that was performed before the Artemis I mission. In-flight telemetry data will be compared to values of SAW section current produced by the models. Each of the optical properties and parameters studied will be outlined and their significance on the impact of glint will be discussed.

Glint↗

DOE OSTI2021

Metal-insulator transition in transition metal dichalcogenide heterobilayer moiré superlattices

Moiré superlattices formed in two-dimensional semiconductor heterobilayers provide a new realization of Hubbard model physics in which the number of electrons per effective atom can be tuned at will. Here we report on an exact diagonalization study of the electronic properties of half-filled narrow moiré bands in which correlation strengths are varied by changing twist angles or interaction strengths. We construct a phase diagram for the bilayer, identifying where the metal-insulator phase transition occurs, estimating the sizes of the charge gaps in the insulating phase, and commenting on the nature of the transition and the importance of subdominant interaction parameters.

2-dimensional systems↗

DOE OSTI2020

Sonochemical synthesis of carbon dots, mechanism, effect of parameters, and catalytic, energy, biomedical and tissue engineering applications

Carbon-based nanomaterials are gaining more and more interest because of their wide range of applications. In this study, carbon dots (CDs) have shown exclusive interest due to unique and novel physicochemical, optical, electrical, and biological properties. Since their discovery, CDs became a promising material for wide range of research applications from energy to biomedical and tissue engineering applications. At same time several new methods have been developed for the synthesis of CDs. Compared to many of these methods, the sonochemical preparation is a green method with advantages such as facile, mild experimental conditions, green energy sources, and feasibility to formulate CDs and doped CDs with controlled physicochemical properties and lower toxicity. In the last five years, the sonochemically synthesized CDs were extensively studied in a wide range of applications. In this review, we discussed the sonochemical assisted synthesis of CDs, doped CDs and their nanocomposites. In addition to the synthetic route, we will discuss the effect of various experimental parameters on the physicochemical properties of CDs; and their applications in different research areas such as bioimaging, drug delivery, catalysis, antibacterial, polymerization, neural tissue engineering, dye absorption, ointments, electronic devices, lithium ion batteries, and supercapacitors. This review concludes with further research directions to be explored for the applications of sonochemical synthesized CDs.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Transition from retrograde to prograde drift instabilities in a magnetron microdischarge

Rotating plasma structures, or “spokes,” in magnetized discharges characterized by perpendicular electric and magnetic fields have been seen in a growing number of studies and are believed to be the result of gradient-driven drift instabilities. Under certain conditions, we have shown the spoke’s rotation to be opposite to the E B direction, i.e., retrograde in its expected direction. Recently, we have linked such counter-intuitive rotation to a local inversion of the electric field. Here, we give further experimental evidence for this inversion and attempt to provide an explanation for a relatively distinct transition seen between retrograde and positive (prograde) drift. In the experiments, a partially magnetized plasma forms inside a magnetron device of mm radius operated with argon. Discharge current–voltage measurements are acquired for a range of argon fill pressure and inter-electrode spacing. We find two branches of operation—a low current branch of negative resistance, coinciding with the retrograde spoke rotation, and a higher current branch of positive resistance, coincident with prograde spoke rotation. We postulate that at low discharge currents, high magnetic field confinement leads to a large density gradient, causing more electron transport to the anode than that demanded by the external circuit. At higher currents, anomalous axial electron transport (across the magnetic field lines) becomes dominant, eliminating the conditions for field inversion. Here, the current thresholds for the field inversion are found to be sensitive to the argon pressure and inter-electrode spacing.

42 ENGINEERING↗

DOE OSTI2022

A Novel Sustainable Process for Multilayer Graphene Synthesis Using CO 2 from Ambient Air

Graphene produced by different methods can present varying physicochemical properties and quality, resulting in a wide range of applications. The implementation of a novel method to synthesize graphene requires characterizations to determine the relevant physicochemical and functional properties for its tailored application. We present a novel method for multilayer graphene synthesis using atmospheric carbon dioxide with characterization. Synthesis begins with carbon dioxide sequestered from air by monoethanolamine dissolution and released into an enclosed vessel. Magnesium is ignited in the presence of the concentrated carbon dioxide, resulting in the formation of graphene flakes. These flakes are separated and enhanced by washing with hydrochloric acid and exfoliation by ammonium sulfate, which is then cycled through a tumble blender and filtrated. Raman spectroscopic characterization, FTIR spectroscopic characterization, XPS spectroscopic characterization, SEM imaging, and TEM imaging indicated that the graphene has fifteen layers with some remnant oxygen-possessing and nitrogen-possessing functional groups. The multilayer graphene flake possessed particle sizes ranging from 2 µm to 80 µm in diameter. BET analysis measured the surface area of the multilayer graphene particles as 330 m 2 /g, and the pore size distribution indicated about 51% of the pores as having diameters from 0.8 nm to 5 nm. This study demonstrates a novel and scalable method to synthesize multilayer graphene using CO 2 from ambient air at 1 g/kWh electricity, potentially allowing for multilayer graphene production by the ton. The approach creates opportunities to synthesize multilayer graphene particles with defined properties through a careful control of the synthesis parameters for tailored applications.

36 MATERIALS SCIENCE↗

NASA NTRS1994

Langmuir turbulence in the auroral ionosphere 2: Nonlinear theory and simulations

A theoretical interpretation of sounding rocket measurements of intense Langmuir wave fields (less than or equal to 500 mV/m) driven by a stream of 20 eV to 4 keV electrons in the lower auroral zone is developed. This interpretation is based on the ability of the 10 microseconds sampling rate of the wave detector to temporally resolve the structure of the Langmuir wave field envelope. A modified form of the Zakharov equations is used to numerically study beam-driven Langmuir turbulence in the presence of a moderate magnetic field (OMEGA (sub e) approximately equals Omega (sub pe). Strong Landau damping on observed nonthermal scattered electrons, which is treated in a companion paper (Newman et al., this issue), plays an important role by inhibiting backscatter cascade and the development of strong turbulence. A parameterized model of the linear electron stream-driven wave instability is introduced, which incorporates limited quasilinear plateau formation. A reasonable set of parameters is found that yields semiquantitative agreement between observed properties of the Langmuir fields and the results of Zakharov equation simulations, including the amplitude and characteristic frequency of the electric field envelope modulations.

Newman, D. L.↗

NASA NTRS1994

Tunnel effect measuring systems and particle detectors

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Kaiser, William J.↗

NASA NTRS1994

Tunnel effect measuring systems and particle detectors

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Kaiser, William J.↗

NASA NTRS1995

Tunnel effect wave energy detection

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Kaiser, William J.↗

NASA NTRS1993

Tunnel effect measuring systems and particle detectors

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Kaiser, William J.↗

DOE OSTI2023

Change of Electrical and Transport Properties of Nickel Oxide by Carrier Concentration and Temperature through First-Principle Calculations

Abstract Nickel is typically used as one of the main components in electrical contact devices or connectors. Nickel oxide (NiO) is usually formed on the surfaces of electrodes and can negatively impact system performance by introducing electrical contact resistance. The thermal, electrical, and transport properties of NiO, as a Mott insulator or a p-type semiconductor, can be altered by operating and environmental conditions such as temperature and stress/strain by contact. In this study, we investigate the fundamental material properties of NiO through the first-principle calculations. First, we obtain and compare the lattice parameter, magnetic moment, and electronic structure for NiO via the WIEN2K simulations with four different potentials (i.e., GGA, GGA + U, LSDA, and LSDA + U). Then, using the WIEN2K simulation results with LSDA + U potential that produces a highly accurate bandgap for NiO, we calculate the electrical conductivity and electrical part of the thermal conductivity of nickel and NiO as a function of temperature and carrier concentration through the BoltzTraP simulations. Systematic simulation results revealed that the electrical conductivity relative to the relaxation time for NiO increases with the carrier concentration, while it shows a slightly decreasing trend with temperature under a fixed carrier concentration. By contrast, the electrical part of the thermal conductivity shows an increasing trend considering carrier concentration and temperature.

Shah, Nayem Md. Reza↗

DOE OSTI2022

Electrical Conductivity of Clayey Rocks and Soils: A Non-Linear Model

It is well-accepted that Archie's law is only applicable to “clean” rocks and soils but fails in “dirty” ones where clay minerals possess an additional component of surface conductivity. Although several models, for example, Waxman-Smits model, were presented to account for this phenomenon, surface conductivity is always inappropriately treated as constant, which actually only holds at high salinities. The essential non-linear characteristic differing over fluid salinities has not been physically or mathematically explained well in those models. Here, we scrutinize the conduction mechanism of clayey rocks and soils and ascribe this non-linear feature to (a) variation of the electrical double layer and (b) the intrinsic clay-and-water conduction pattern. With effective medium theory, we develop an easy-to-use non-linear model that both reflects electrochemical theories and explains the measurement data well. Our model can be used to produce more accurate results for laboratory- and field-scale petrophysical parameter evaluations than the previous models.

58 GEOSCIENCES↗