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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Kinetic Plasma Simulation in the MOOSE Framework: Verification of Electrostatic Particle In Cell Capabilities

In magnetic confinement nuclear fusion reactors, the interaction between the plasma edge and plasma facing components is extremely important. At the plasma edge, a kinetic representation such as particle-in-cell (rather than a fluid representation) is required to accurately capture the plasma behavior. General purpose particle-in-cell plasma simulation capabilities have been developed in the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework. This new capability is a part of the development of a new MOOSE-based framework for modeling plasma facing components, the Fusion ENergy Integrated multiphys-X (FENIX) framework. In this work, the verification of foundational particle-in-cell capabilities in FENIX is presented. This new plasma simulation capability has three main components: moving particles in discrete steps on the finite element mesh, mapping charge density from the particle's location to the finite element mesh, and solving for the electrostatic potential based on the charge density mapped from particles to the mesh. In this paper, simple verification problems demonstrating each of these new capabilities are presented, and future work includes electromagnetic capabilities and Monte Carlo collisions with neutral gas particles.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Substituent and Heteroatom Effects on π–π Interactions: Evidence That Parallel-Displaced π-Stacking is Not Driven by Quadrupolar Electrostatics

Stacking interactions are a recurring motif in supramolecular chemistry and biochemistry, where a persistent theme is a preference for parallel-displaced aromatic rings rather than face-to-face π-stacking. This is usually explained in terms of quadrupole–quadrupole interactions between the arene moieties but that interpretation is inconsistent with accurate calculations, which reveal that the quadrupolar picture is qualitatively wrong. At typical π-stacking distances, quadrupolar electrostatics may differ in sign from an exact calculation based on charge densities of the interacting arenes. We apply symmetry-adapted perturbation theory to dimers composed of substituted benzene and various aromatic heterocycles, which display a wide range of electrostatic interactions, and we investigate the interplay of Pauli repulsion, dispersion, and electrostatics as it pertains to parallel-displaced π-stacking. Profiles of energy components along cofacial slip-stacking coordinates support a prominent role for the “van der Waals model” (dispersion in competition with Pauli repulsion), even for polar monomers where electrostatic interactions are significant. While electrostatic interactions are necessary to explain the optimal face-to-face π-stacking distance and to account for the relative orientation of one polar arene with respect to another, we find no evidence to support continued invocation of quadrupolar electrostatics as a basis for π-stacking. Our results suggest that a driving force for offset-stacking exists even in the absence of electrostatic interactions. Consequently, tuning electrostatics via functionalization does not guarantee that slip-stacking can be avoided. This has implications for rational design of soft materials and other supramolecular architectures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Electrostatic forces in planetary rings

The average charge on a particle in a particle-plasma cloud, the plasma potential inside the cloud, and the Coulomb force acting on the particle are calculated. The net repulsive electrostatic force on a particle depends on the plasma density, temperature, density of particles, particle size, and the gradient of the particle density. In a uniformly dense ring the electrostatic repulsion is zero. It is also shown that the electrostatic force acts like a pressure force, that even a collisionless ring can be stable against gravitational collapse, and that a finite ring thickness does not necessarily imply a finite velocity dispersion. A simple criterion for the importance of electrostatic forces in planetary rings is derived which involves the calculation of the vertical ring thickness which would result if only electrostatic repulsion were responsible for the finite ring thickness. Electrostatic forces are entirely negligible in the main rings of Saturn and the E and G rings. They may also be negligible in the F ring. However, the Uranian rings and Jupiter's ring seem to be very much influenced by electrostatic repulsion. In fact, electrostatic forces could support a Jovian ring which is an order of magnitude more dense than observed.

Goertz, C. K.↗
NASA NTRS2015

A Triboelectric Sensor Array for Electrostatic Studies on the Lunar Surface

The moons electrostatic environment requires careful consideration in the development of future lunar landers. Electrostatically charged dust was well documented during the Apollo missions to cause thermal control, mechanical, and visibility issues. The fine dust particles that make up the surface are electrostatically charged as a result of numerous charging mechanisms. The relatively dry conditions on the moon creates a prime tribocharging environment during surface operations. The photoelectric effect is dominant for lunar day static charging, while plasma electrons are the main contributor for lunar night electrostatic effects. Electrostatic charging is also dependent on solar intensity, Earth-moon relative positions, and cosmic ray flux. This leads to a very complex and dynamic electrostatic environment that must be studied for the success of long term lunar missions.In order to better understand the electrostatic environment of planetary bodies, Kennedy Space Center, in previous collaboration with the Jet Propulsion Laboratory, has developed an electrostatic sensor suite. One of the instruments included in this package is the triboelectric sensor array. It is comprised of strategically selected materials that span the triboelectric series and that also have previous spaceflight history. In this presentation, we discuss detailed testing with the triboelectric sensor array performed at Kennedy Space Center. We will discuss potential benefits and use cases of this low mass, low cost sensor package, both for science and for mission success.

Charging↗
DOE OSTI2025

A Universal Augmentation Framework for Long-Range Electrostatics in Machine Learning Interatomic Potentials

Most current machine learning interatomic potentials (MLIPs) rely on short-range approximations, without explicit treatment of long-range electrostatics. To address this, we recently developed the Latent Ewald Summation (LES) method, which infers electrostatic interactions, polarization, and Born effective charges (BECs), just by learning from energy and force training data. Here, in this study, we present LES as a standalone library, compatible with any short-range MLIP, and demonstrate its integration with methods such as MACE, NequIP, Allegro, CACE, CHGNet, and UMA. We benchmark LES-enhanced models on distinct systems, including bulk water, polar dipeptides, and gold dimer adsorption on defective substrates, and show that LES not only captures correct electrostatics but also improves accuracy. Additionally, we scale LES to large and chemically diverse data by training MACELES-OFF on the SPICE set containing molecules and clusters, making a universal MLIP with electrostatics for organic systems, including biomolecules. MACELES-OFF is more accurate than its short-range counterpart (MACE-OFF) trained on the same data set, predicts dipoles and BECs reliably, and has better descriptions of bulk liquids. By enabling efficient long-range electrostatics without directly training on electrical properties, LES paves the way for electrostatic foundation MLIPs.

Kim, Dongjin [University of California, Berkeley, ↗
NASA NTRS1971

Conversion of electrostatic plasma waves into electromagnetic waves - Numerical calculation of the dispersion relation for all wavelengths.

The dispersion curves have been computed for a wide range of wavelengths from electromagnetic waves to electrostatic waves in a magnetoactive warm plasma with a Maxwellian velocity distribution function. The computation was carried out mainly for the perpendicular propagation mode. The upper hybrid resonance is the connection point of the electrostatic waves and the electromagnetic waves. The electrostatic waves not associated with the upper hybrid resonance are subjected to electron cyclotron damping when the wavelength becomes long. Oblique propagation is allowed for the electrostatic waves in a frequency range from the plasma frequency to the upper hybrid resonance frequency in the long-wavelength region where Landau damping can be neglected and where the electrostatic mode smoothly connects to the electromagnetic X-mode. In a slightly inhomogeneous plasma, the Bernstein-mode electrostatic wave can escape by being converted into the O-mode electromagnetic wave; two reflections take place during this escape process.

Oya, H.↗
NASA NTRS1986

Analysis and interpretation of the shocklike electrostatic noise observed during the AMPTE solar wind lithium releases

During the AMPTE (Active Magnetospheric Particle Tracer Explorers) solar wind lithium release on September 11, and again on September 20, 1984, an intense burst of electrostatic noise was observed near the upstream edge of the ion cloud. Comparisons with measurements by the IMP-6 and ISEE-1 spacecraft show that the spectrum and overall features of this noise are very similar to electrostatic noise observed at the Earth's bow shock. A stability analysis using realistic parameters shows that the electrostatic noise can be accounted for by an ion beam-plasma instability caused by the solar wind proton beam streaming through the nearly stationary lithium cloud. The growth rate of this instability is largest when the ion density and solar wind proton density are similar, which explains why the noise only occurs near the outer edge of the ion cloud. The similarity to the noise in the Earth's bow shock suggest that a shock may exist in the solar wind plasma flow upstream of the ion cloud. If the noise is associated with a shock, then it must be an electrostatic shock, since the ion cyclotron radii are too small for the existence of a MHD shock. Since the electrostatic instability occurs at phase velocities near the lithium thermal velocity, the electrostatic turbulence may play a role in heating the lithium ions and transferring momentum from the solar wind to the ion cloud.

Gurnett, D. A.↗
NASA NTRS2006

Electrostatic Screen for Transport of Martian and Lunar Regolith

The Martian and Lunar Regolith contain fine particulate including those in the size range from 0.5 to 200 micron [1-2]. Martian dust can be transported and deposited by Aeolian processes, including "Dust Devils". Due to the ultra high vacuum (10e-12 Torr), transport of dust on the Moon is solely a result of collision/ballistic motion. Dust obscuration of solar cells is one of the primary factors limiting the duration of Martian missions, including the Mars Exploration Rovers. Dust contamination in vacuum seals is one of the primarily factors that limited lunar excursions during the Apollo missions. Controlled transportation of dust on Mars and the Moon is important for many reasons, including both contamination mitigation and in situ resource utilization (ISRU). Since both the monopole and dipole electrostatic moments result in non-trivial forces on particles in an electrostatic field, dust particles, whether charged or not, can be transported by electrostatic fields. In the electrostatic screen, alternating waveforms of voltage applied to patterned grids of electrodes will transport dust. The authors will show that the canonical methods for transporting dust via electrostatic screen can be readily applied to transport of Martian and Lunar regolith. Experiments have been performed in ambient, low humidity, Martian, and Lunar conditions. Screen parameters have been examined for application to each regolith, such as grid spacing, trace width, grid voltage, pulse pattern, pulse frequency, and coating type. The authors have also developed an electrostatic screen based on optically transparent conductors that can be placed over solar arrays, windows, visors, lenses, etc.

Immer, C.↗
NASA NTRS2017

Active Electrostatic flight for airless bodies

The environment near the surface of asteroids, comets, and the Moon is electrically charged due to the Sun’s photoelectric bombardment and lofting dust, which follows the Sun illumination as the body spins. Charged dust is ever present, in the form of dusty plasma, even at high altitudes, following the solar illumination. If a body with high surface resistivity is exposed to the solar wind and solar radiation, sunexposed areas and shadowed areas become differentially charged. The E-Glider (Electrostatic Glider) is an enabling capability for operation at airless bodies, a solution applicable to many types of in-situ missions, which leverages the natural environment. This platform directly addresses the "All Access Mobility" Challenge, one of the NASA’s Space Technology Grand Challenges. Exploration of comets, asteroids, moons and planetary bodies is limited by mobility on those bodies. The lack of an atmosphere, the low gravity levels, and the unknown surface soil properties pose a very difficult challenge for all forms of know locomotion at airless bodies. This EGlider levitates by extending thin, charged, appendages, which are also articulated to direct the levitation force in the most convenient direction for propulsion and maneuvering. The charging is maintained through continuous charge emission. It lands, wherever it is most convenient, by retracting the appendages or by firing a cold-gas thruster, or by deploying an anchor. Preliminary calculations indicate that a 1 kg mass can be electrostatically levitated in a microgravity field with a 2 m diameter electrostatically inflated ribbon structure at 19kV, hence the need for a “balloon-like” system. The wings could be made of very thin Au-coated Mylar film, which are electrostatically inflated, and would provide the lift due to electrostatic repulsion with the naturally charged asteroid surface. Since the E-glider would follow the Sun’s illumination, the solar panels on the vehicle would constantly charge a battery. Further articulation at the root of the lateral strands or inflated membrane wings, would generate a component of lift depending on the articulation angle, hence a selective maneuvering capability which, to all effects, would lead to electrostatic (rather than aerodynamic) flight.

Schaub, Hanspeter↗
NASA NTRS2018

E-Glider: Active Electrostatic Flight for Airless Body Exploration

The environment near the surface of asteroids, comets, and the Moon is electrically charged due to the Sun's photoelectric bombardment and lofting dust, which follows the Sun illumination as the body spins. Chargeddust is ever present, in the form of dusty plasma, even at high altitudes, following the solar illumination. If abody with high surface resistivity is exposed to the solar wind and solar radiation, sun-exposed areas andshadowed areas become differentially charged. The E-Glider (Electrostatic Glider) is an enabling capability foroperation at airless bodies, a solution applicable to many types of in-situ mission concepts, which leverages thenatural environment. With the E-Glider, we transform a problem (spacecraft charging) into an enablingtechnology, i.e. a new form of mobility in microgravity environments using new mechanisms and maneuveringbased on the interaction of the vehicle with the environment. Consequently, the vision of the E-Glider is toenable global scale airless body exploration with a vehicle that uses, instead of avoids, the local electricallycharged environment. This platform directly addresses the "All Access Mobility" Challenge, one of the NASA'sSpace Technology Grand Challenges. Exploration of comets, asteroids, moons and planetary bodies is limitedby mobility on those bodies. The lack of an atmosphere, the low gravity levels, and the unknown surface soilproperties pose a very difficult challenge for all forms of know locomotion at airless bodies. This E-Gliderlevitates by extending thin, charged, appendages, which are also articulated to direct the levitation force in themost convenient direction for propulsion and maneuvering. The charging is maintained through continuouscharge emission. It lands, wherever it is most convenient, by retracting the appendages or by firing a cold-gasthruster, or by deploying an anchor. The wings could be made of very thin Au-coated Mylar film, which areelectrostatically inflated, and would provide the lift due to electrostatic repulsion with the naturally chargedasteroid surface. Since the E-glider would follow the Sun's illumination, the solar panels on the vehicle wouldconstantly charge a battery. Further articulation at the root of the lateral strands or inflated membrane wings,would generate a component of lift depending on the articulation angle, hence a selective maneuveringcapability which, to all effects, would lead to electrostatic (rather than aerodynamic) flight. Preliminarycalculations indicate that a 1 kg mass can be electrostatically levitated in a microgravity field with a 2 mdiameter electrostatically inflated ribbon structure at 19kV, hence the need for a "balloon-like" system. Due tothe high density and the photo-electron sheath and associate small Debye length, significant power is requiredto levitate even a few kilograms. The power required is in the kilo-Watt range to maintain a constant chargelevel.

Electrostatic Flight↗
DOE OSTI2024

Colloidal Dispersions of Sterically and Electrostatically Stabilized PbS Quantum Dots: Structure Factors, Second Virial Coefficients, and Film-Forming Properties

Electrostatically stabilized nanocrystals (NCs) and, in particular, quantum dots (QDs) hold promise for forming strongly coupled superlattices due to their compact and electronically conductive surface ligands. However, studies of the colloidal dispersion and interparticle interactions of electrostatically stabilized sub-10 nm NCs have been limited, hindering the optimization of their colloidal stability and self-assembly. In this study, we employed small-angle X-ray scattering (SAXS) experiments to investigate the interparticle interactions and arrangement of PbS QDs with thiostannate ligands (PbS-Sn2S64-) in polar solvents. The study reveals significant deviations from the ideal solution behavior in electrostatically stabilized QD dispersions. Our results demonstrate that PbS-Sn2S64- QDs exhibit long-range interactions within the solvent, in contrast to the short-range steric repulsion characteristic of PbS QDs with oleate ligands (PbS-OA). Introducing highly charged multivalent electrolytes screens electrostatic interactions between charged QDs, reducing the length scale of the repulsive interactions. Furthermore, we calculated the second virial (B2) coefficients from SAXS data, providing insights into how surface chemistry, solvent, and size influence pair potentials. Finally, we explore the influence of long-range interparticle interactions of PbS-Sn2S64- QDs on the morphology of films produced by drying or spin-coating colloidal solutions. The long-range repulsive term of PbS-Sn2S64- QDs promotes the formation of amorphous films, and screening the electrostatic repulsion by the addition of an electrolyte enables the formation of crystalline domains. These findings highlight the critical role of NC-NC interactions in tailoring the properties of functional materials made of colloidal NCs.

SAXS↗
NASA NTRS1979

Coherent anomalous resistivity in the region of electrostatic shocks

Anomalous resistivity in a phase-coherent electrostatic ion cyclotron wave in the region of the auroral electrostatic shocks observed by the S3-3 satellite is considered. It is shown that current-driven shocks and anomalous resistivity will be most important above 5,000 km, where the electron drift velocity is maximized and parallel electric fields are possible. A model for the parallel field based on the dissipation of an Alfven wave pulse by current-driven electrostatic ion cyclotron turbulence is presented. In the model, coherent electrostatic ion cyclotron waves lead to anomalous resistivity by electron trapping, producing parallel electric fields greater than 1 mV/m, and may set up the parallel populations necessary to support oblique electrostatic shocks.

Lysak, R. L.↗
NASA NTRS1981

Electrostatic disruption of a charged conducting spheroid

Electrostatic disruption of elongated parent grains following sudden charging to high electrostatic potentials is proposed as a specific mechanism for the appearance of striae or pseudosynchronic bands which have been observed in several comets. The polar and equatorial electrostatic tension for axis ratios between 0.01 and 1000 are calculated, and the polar pressure is found to be larger than the equatorial pressure for prolate spheroids. The electrostatic polar pressure profile along the polar axis for prolate spheroids is calculated, and the pressure is found to increase monotonically from a minimum at the center to a maxima at the ends. This indicates that as a prolate spheroid of uniform tensile strength is charged up, it will continue to chip off at the ends when the electrostatic pressure there exceeds the uniform tensile strength of the grain. The result can be a prolate grain or a grain which continues chipping until it explodes.

Hill, J. R.↗
NASA NTRS1987

The electrostatic effect for the collisionless tearing mode

Electron dynamics has not been self-consistently considered in collisionless tearing mode theories to date because of the mathematical complexity of the Vlasov-Maxwell equations. It has been found, using computer simulations, that electrostatic fields play an important role in the tearing mode. Vlasov theory, including the electrostatic field, is investigated for topologies with both antiparallel and nonantiparallel magnetic field lines. The electrostatic field influences the resonant current in the neutral sheet which is a non-MHD effect, and modifies the linear growth rate. At the magnetopause, where the field lines are not antiparallel, the electrostatic effect acts to raise the linear growth rate of the tearing mode. On the other hand, in the magnetotail, where magnetic field lines are antiparallel, the electrostatic effect reduces the tearing mode growth rate.

Hoshino, Masahiro↗
NASA NTRS1991

Electrostatic fields in a dusty Martian environment

While there have been several studies suggesting the possibility of electrical activity on Mars, to date there have been no measurements to search for evidence of such activity. In the absence of widespread water clouds and convective storm systems similar to those on the Earth and Jupiter, the most likely candidate for the creation of electrostatic charges and fields is triboelectric charging of dust, i.e., the friction between blown dust and the ground, and of dust particles with each other. Terrestrial experience demonstrates that electric fields 5 to 15 kV-m(exp -1) are not uncommon in dust storms and dust devils in desert regions, where the polarity varies according to the chemical composition and grain size. Simple laboratory experiments have demonstrated that modest electrostatic fields of roughly 5,000 V-m(exp -1) may be produced, along with electrical spark discharges and glow discharges, in a simulation of a dusty, turbulent Martian surface environment. While the Viking landers operated for several years with no apparent deleterious effects from electrostatic charging, this may have been at least partly due to good engineering design utilizing pre-1976 electronic circuitry to minimize the possibility of differential charging among the various system components. However, free roaming rovers, astronauts, and airborne probes may conceivably encounter an environment where electrostatic charging is a frequent occurrence, either by way of induction from a static electric field or friction with the dusty surface and atmosphere. This raises the possibility of spark discharges or current surges when subsequent contact is made with other pieces of electrical equipment, and the possibility of damage to modern microelectronic circuitry. Measurements of electrostatic fields on the surface of Mars could therefore be valuable for assessing this danger. Electric field measurements could also be useful for detecting natural discharges that originate in dust storms. This detection could be performed at distances ranging from 10s of km in the case of J-charge-like discharge signatures, to planetary distances if there exists a global electrical circuit or Schumann resonance spectrum.

Sentman, D. D.↗
NASA NTRS1996

Numerical Investigation of Two-Phase Flows With Charged Droplets in Electrostatic Field

A numerical method to solve two-phase turbulent flows with charged droplets in an electrostatic field is presented. The ensemble-averaged Navier-Stokes equations and the electrostatic potential equation are solved using a finite volume method. The transitional turbulence field is described using multiple-time-scale turbulence equations. The equations of motion of droplets are solved using a Lagrangian particle tracking scheme, and the inter-phase momentum exchange is described by the Particle-In-Cell scheme. The electrostatic force caused by an applied electrical potential is calculated using the electrostatic field obtained by solving a Laplacian equation and the force exerted by charged droplets is calculated using the Coulombic force equation. The method is applied to solve electro-hydrodynamic sprays. The calculated droplet velocity distributions for droplet dispersions occurring in a stagnant surrounding are in good agreement with the measured data. For droplet dispersions occurring in a two-phase flow, the droplet trajectories are influenced by aerodynamic forces, the Coulombic force, and the applied electrostatic potential field.

Kim, Sang-Wook↗
DOE OSTI2024

Charging, aggregation, and electrostatic dispersion of radioactive and nonradioactive particles in the atmosphere

Electrostatic dispersion can significantly impact the microphysical behavior of charged particles and ions until reaching zero space charge. However, although radioactive particles can be strongly charged in air, the influence of electrostatic dispersion has been neglected in understanding their behavior. This study is aimed at investigating the time evolution of the charge and size distributions of radioactive and nonradioactive particles in air and developing simple approaches for applications. With processes involving charging, aggregation, and electrostatic dispersion, a comprehensive population balance model (PBM) has been developed to examine particle charge/size distribution dynamics. It is shown that compared to nonradioactive particles, the charge and size distributions of radioactive particles may evolve differently with time because radioactivity and electrostatic dispersion can significantly affect the charging and aggregation kinetics of the particles. It is found that, after the Fukushima accident, background aerosols in the pathway of radioactive plumes might be highly charged due to ionizing radiation, suggesting that radiation fields may strongly influence in situ measurements of charged atmospheric particles. The comprehensive PBM is simplified, and then the verification and application of the simplified PBMs are discussed. This study provides useful insight into how radioactivity can affect the dynamic behavior of particles in atmospheric systems including radiation sources.

54 ENVIRONMENTAL SCIENCES↗