Search NASA⌕ Search

SEARCH · Search NASA

Results for “electronic hybridization”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Real‐Time Optical Process Monitoring for Structure and Property Control of Aerosol Jet Printed Functional Materials

Abstract Aerosol jet printing is a popular digital additive manufacturing method for flexible and hybrid electronics, but it lacks sophisticated real‐time process control schemes that would enable more widespread adoption in manufacturing environments. Here, an optical measurement system is introduced to track the aerosol density upstream of the printhead. The measured optical extinction, combined with the aerosol flow rate, is directly related to deposition rate and accurately predicts functional materials properties such as the electrical resistance of printed graphene films. This real‐time system offers a compelling solution for process drift and batch‐to‐batch variability, rendering it a valuable tool for both real‐time control of aerosol jet printing and fundamental studies of the underlying process science.

Tafoya, Rebecca R.↗
DOE OSTI2020

Interpenetration and kinetic effects in converging, high-energy plasma jets

In this work, we report on numerical simulations of laser-driven convergent plasma fusion targets. These “inverted corona” fusion targets are useful for the study of counter-streaming and converging rarefied plasma flows, and previous experiments have demonstrated their potential as neutron sources. The scheme consists of a fuel layer lined along the interior surface of a hollow plastic shell that is laser-ablated and expands inward towards the target center. The plasma streams generated in these targets are initially nearly collisionless as they converge, leading to wide interaction length scales and long interaction time scales as the jets interpenetrate. Such kinetic effects impact mixing of constituent ions - a phenomenon not properly captured by single-fluid hydrodynamic simulations. Here we conduct numerical simulations using two different methods: (1) single-fluid simulations in HYDRA, and (2) kinetic-ion, fluid-electron hybrid particle-in-cell (PIC) simulations in the code Chicago. It is shown that the initially nearly collisionless plasma fronts interpenetrate deeply and lead to broader interaction regions in space and time resulting in significant beam-beam fusion. The two approaches make different, testable predictions for the effect of fuel-layer thickness on neutron yield.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

2D kinetic-ion simulations of inverted corona fusion targets

Laser-driven “inverted corona” fusion targets have attracted interest as a low-convergence neutron source and platform for studying kinetic physics. The scheme consists of a hollow or gas-filled spherical shell made of deuterated plastic. The shell has one or more laser entrance holes (LEH), resembling a spherical hohlraum. The laser passes through the LEH’s and illuminates the interior surface of the shell, ablating a plasma that travels inward towards the target center. Long ion mean free paths in the converging plasma can lead to significant interpenetration, atomic mix, and other kinetic effects. Here, in this work we report on numerical simulations of inverted corona targets using the kinetic-ion, fluid–electron hybrid particle-in-cell (PIC) approach in 2D RZ geometry. 2D simulations suggest that shape effects do not have a significant impact on plasma evolution and observed yield trends are primarily the result of 1D kinetic mix mechanisms. Simulations are also compared against available experimental data recorded at the OMEGA laser facility. In particular, synthetic x-ray emission images show good qualitative agreement with experimental results, albeit with an apparent timing discrepancy for the two-sided vacuum target. More generally, we demonstrate the potential of hybrid-PIC simulations for full-system modeling and experimental design, including collisional absorption of laser energy, plasma evolution, mix, and fusion burn.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Watching Polarons Move in the Energy and Frequency Domains Using Color Impedance Spectroscopy

The hybrid electronic–ionic transport property of π-conjugated polymers enables new (opto)electrochemical device constructs for energy conversion and storage and biosensing applications. One major challenge is separating the energy and frequency dependence of Faradaic events–those involving charge transfer and the redox processes of the conjugated backbone–from the non-Faradaic components, such as ionic motion. Herein, we combine optical spectroscopy with electrochemical impedance spectroscopy (EIS) to resolve the frequency response of ionic–electronic coupling as a function of electrochemical doping potential. First, using EIS, we identify two different frequency regimes resulting in potential-dependent capacitive elements on the order of ~10 μF/cm 2 in a high-frequency regime and ~50–150 μF/cm 2 in a low-frequency regime. Given the larger magnitude and greater potential dependence, we posit that polaronic motion is more likely to occur at low frequencies (<1 kHz) and overlaps with ionic motion. The use of color impedance spectroscopy (CIS) enables observation of polaronic motion with frequency modulation. We observe that higher doping potentials show a greater motion of polarons above the DC-bias baseline concentration for onset in electrochemical doping, but all potentials considered demonstrate a critical frequency at which the polaronic motion is “frozen” (~40 Hz). Furthermore, this critical information obtained from CIS in highly dielectric environments offers a unique figure of merit for future studies on electronic–ionic coupling by which to compare across polymer/electrolyte interfaces, including the role of a charge-supporting electrolyte, a solvent, and alternative Faradaic processes (e.g., electrocatalysis).

36 MATERIALS SCIENCE↗
DOE OSTI2024

A giant virus infecting the amoeboflagellate Naegleria

Giant viruses (Nucleocytoviricota) are significant lethality agents of various eukaryotic hosts. Although metagenomics indicates their ubiquitous distribution, available giant virus isolates are restricted to a very small number of protist and algal hosts. Here we report on the first viral isolate that replicates in the amoeboflagellate Naegleria. This genus comprises the notorious human pathogen Naegleria fowleri, the causative agent of the rare but fatal primary amoebic meningoencephalitis. We have elucidated the structure and infection cycle of this giant virus, Catovirus naegleriensis (a.k.a. Naegleriavirus, NiV), and show its unique adaptations to its Naegleria host using fluorescence in situ hybridization, electron microscopy, genomics, and proteomics. Naegleriavirus is only the fourth isolate of the highly diverse subfamily Klosneuvirinae, and like its relatives the NiV genome contains a large number of translation genes, but lacks transfer RNAs (tRNAs). NiV has acquired genes from its Naegleria host, which code for heat shock proteins and apoptosis inhibiting factors, presumably for host interactions. Notably, NiV infection was lethal to all Naegleria species tested, including the human pathogen N. fowleri. This study expands our experimental framework for investigating giant viruses and may help to better understand the basic biology of the human pathogen N. fowleri.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Connection between f -electron correlations and magnetic excitations in UTe 2

The detailed anisotropic dispersion of the low-temperature, low-energy magnetic excitations of the candidate spin-triplet superconductor UTe 2 is revealed using inelastic neutron scattering. The magnetic excitations emerge from the Brillouin zone boundary at the high symmetry Y and T points and disperse along the crystallographic $\hat{b}$ -axis. In applied magnetic fields to at least μ 0 H = 11 T along the $\hat{c}-{\rm{axis}}$ , the magnetism is found to be field-independent in the (hk0) plane. The scattering intensity is consistent with that expected from U 3+ /U 4+ f-electron spins with preferential orientation along the crystallographic $\hat{a}$ -axis, and a fluctuating magnetic moment of μ eff =1.7(5) μ B . We propose interband spin excitons arising from f-electron hybridization as a possible origin of the magnetic excitations in UTe 2 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Kinetic mix at gas-shell interface in inverted corona fusion targets

Gas-filled, laser-driven “inverted corona” fusion targets have attracted interest as a low-convergence neutron source and platform for studying kinetic physics. At the fill pressures under investigation, ejected particles from the shell can penetrate deeply into the gas before colliding, leading to significant mixing across the gas–shell interface. Here, we use kinetic-ion, fluid-electron hybrid particle-in-cell simulations to explore the nature of that mix. Simulations of the system demonstrate characteristics of a weakly collisional electrostatic shock, whereby a strong electric field accelerates shell ions into the rarefied gas and reflects upstream gas ions. This interpenetration is mediated by collisional processes: At higher initial gas pressure, fewer shell particles pass into the mix region and reach the hotspot. This effect is detectable through neutron yield scaling vs gas pressure. Predictions of neutron yield scaling show excellent agreement with experimental data recorded at the OMEGA laser facility, suggesting that 1D kinetic mechanisms are sufficient to capture the mix process.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Proximity-induced magnetism and the enhancement of damping in ferromagnetic/heavy metal systems

The relationship between proximity-induced magnetism (PIM) at the heavy metal/ferromagnet interface and spin-transport across such interfaces has generated significant debate. To investigate the link between the two, element specific x-ray magnetic circular dichroism and ferromagnetic resonance measurements were made on the same CoFe/Au/Pt and NiFe/Au/Pt thin film samples with varying Au thickness, with complementary SIMS analysis, which shows evidence of Ni diffusion from NiFe into the Pt. An approximately linear relationship is observed between the magnitude of Pt PIM and magnitude of damping enhancement in both systems. The results demonstrate that electronic hybridization of the heavy metal and ferromagnet is required for a full understanding of damping enhancement and interfacial spintransport for spintronic devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Interacting fermions in narrow-gap semiconductors with band inversion

Abstract Highly unconventional behavior of the thermodynamic response functions has been experimentally observed in a narrow gap semiconductor samarium hexaboride. Motivated by these observations, we use renormalization group technique to investigate many-body instabilities in the f -orbital narrow gap semiconductors with band inversion in the limit of weak coupling. By projecting out the double occupancy of the f -states we formulate a low-energy theory describing the interacting particles in two hybridized electron- and hole-like bands. The interactions are assumed to be weak and short-ranged. We take into account the difference between the effective masses of the quasiparticles in each band. Upon carrying out the renormalization group analysis we find that there is only one stable fixed point corresponding to the excitonic instability with time-reversal symmetry breaking for small enough mismatch between the effective masses.

Physics↗
DOE OSTI2023

Effect of kinetic ions on the toroidal double-tearing modes

We investigate the effects of kinetic ions on double-tearing modes (DTMs) using the gyrokinetic particle-in-cell simulation code GEM with a gyrokinetic ion/fluid electron hybrid model. It is found that the ion kinetic effects can decrease the growth rate of the DTMs. This effect is more significant for stronger coupling of DTMs with smaller distance between the rational surfaces. Kinetic ions can also enhance the coupling effect between the two rational surfaces. Energy transfer analyses between particles and wave fields show that the stabilizing effect of kinetic ions comes mainly from the perpendicular magnetic drift of ions in the coupling region and around the outer rational surface.

Physics↗
DOE OSTI2020

Understanding and mitigating process drift in aerosol jet printing

Aerosol jet printing offers a versatile, high-resolution prototyping capability for flexible and hybrid electronics. Despite its rapid growth in recent years, persistent problems such as process drift hinder the adoption of this technology in production environments. Here we explore underlying causes of process drift during aerosol jet printing and introduce an engineered solution to improve deposition stability. In this work it is shown that the ink level within the cartridge is a critical factor in determining atomization efficiency, such that the reduction in ink volume resulting from printing itself can induce significant and systematic process drift. By integrating a custom 3D-printed cartridge with an ink recirculation system, ink composition and level within the cartridge are better maintained. This strategy allows extended duration printing with improved stability, as evidenced by 30 h of printing over 5 production runs. This provides an important tool for extending the duration and improving reliability for aerosol jet printing, a key factor for integration in practical manufacturing operations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Low-energy electrodynamics and a hidden Fermi liquid in the heavy-fermion compound CeCoIn 5

We present time-domain THz spectroscopy of thin films of the heavy-fermion superconductor CeCoIn 5 . Below the ≈40 K Kondo coherence temperature, a narrow Drude-like peak forms, as a result of the 𝑓-orbital–conduction-electron hybridization and the formation of the heavy-fermion state. The complex optical conductivity is analyzed through a Drude model and extended Drude model analysis. Via the extended Drude model analysis, we measure the frequency-dependent scattering rate (1/𝜏) and effective mass (𝑚*/𝑚 𝑏 ). This scattering rate shows a linear dependence on temperature, which matches the dependence of the resistivity as expected. Nevertheless, the width of the low-frequency Drude peak itself that is set by the renormalized quasiparticle scattering rate (1/𝜏*=𝑚 𝑏 /𝑚*⁢𝜏) shows a 𝑇 2 dependence. This is the scattering rate that characterizes the relaxation time of the renormalized quasiparticles. In conclusion, this gives evidence for a Fermi liquid state, which in conventional transport experiments is hidden by the strong temperature dependent mass.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Plasmonic Nonreciprocity Driven by Band Hybridization in Moiré Materials

Here, we propose a new current-driven mechanism for achieving significant plasmon dispersion nonreciprocity in systems with narrow, strongly hybridized electron bands. The magnitude of the effect is controlled by the strength of electron-electron interactions α , which leads to its particular prominence in moiré materials, characterized by $α \gg$ 1. Moreover, this phenomenon is most evident in the regime where Landau damping is quenched and plasmon lifetime is increased. The synergy of these two effects holds great promise for novel optoelectronic applications of moiré materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Experimental Progress in Superconducting Nickelates

The superconducting nickelates were first proposed as potential analogs to the cuprate unconventional superconductors in 1999, but it took twenty years before superconductivity was successfully stabilized in epitaxial thin films. Since then, a flurry of both experimental and theoretical efforts have sought to understand the similarities and differences between the two systems and how they manifest in the macroscopic superconducting and normal state properties. Although the nickelates and cuprates indeed share many commonalities within their respective phase diagrams, several notable differences have also emerged, especially regarding their parent compounds, electronic hybridization, and fermiology. Here, we provide a survey of the rapidly developing landscape of layered nickelate superconductors, including recent experimental progress to probe not just the superconducting but also normal state and other ordered phases stabilized in these compounds.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1981

Air Force research in optical processing

Optical and optical electronic hybrid processing especially in the application area of image processing are emphasized. Real time pattern recognition processors for such airborne missions as target recognition, tracking, and terminal guidance are studied.

Neff, J.↗
NASA NTRS1985

Primary cosmic ray spectra in the range 20-60 GeV/n

Energy spectra for primary cosmic rays C-Fe above 20 GeV/n were measured on a balloon flight from Greenville S.C. in June 1982 with a hybrid electronic counter-emulsion chamber experiment. Fluxes above the atmosphere appear in general agreement with previously published values. The heavy events included in this data will be used along with the JACEE passive chamber data to provide a heavy composition direct measurement from 10 to the 12th power to approximately 10 to the 15th power eV total energy.

Burnett, T. H.↗
NASA NTRS1985

The response of a scintillation counter below an emulsion chamber to heavy nucleus interactions in the chamber

In 1982 a hybrid electronic counter-emulsion chamber experiment was flown on a balloon to study heavy nucleus interactions in the 20 to approximately 100 GeV/AMU energy range. A gas Cerenkov counter, two solid Cerenkov counters, and a proportional counter hodoscope gave the primary energy, the primary charge and the trajectory of the particles, respectively. Using the trajectory information cosmic ray nuclei of Z 10 were found reliably and efficiently, and interaction characteristics of the Fe group nuclei were measured in the chamber. A plastic scintillator below the emulsion chamber responded to showers resulting from interactions in the chamber and to noninteracting nuclei. Data on the response of the counter have been compared with simulations of hadronic-electromagnetic cascades to derive the average neutral energy fraction released by the heavy interactions, and to predict the performance of this kind of counter at higher energies. For the interacting events of highest produced particles multiplicity comparison between various simulations and the shower counter signal have been made.

Burnett, T. H.↗
NASA NTRS1988

A mechanism for strong shock electron heating in supernova remnants

It is shown that collisionless shock waves propagating away from a supernova may be directly responsible for the 10 keV X-ray emission seen in supernova remnants. A sequence of plasma instabilities (Buneman and ion acoustic) between the reflected and/or transmitted ions and the background electrons at the foot of the shock front can give rise to rapid anomalous heating of electrons. Hybrid simulations of a perpendicular collisionless shock are presented to demonstrate that this heating can arise within a self-consistently computed shock structure.

Cargill, P. J.↗