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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Polycaprolactone‐Based Zinc Ink for High Conductivity Transient Printed Electronics and Antennas

Abstract Distributed sensors and electronics can be used in agriculture to optimize crop management and improve environmental outcomes. Electronic devices in these outdoor spaces require medium to long range (>1m) wireless communication of data over several weeks or months, which in turn requires high conductivity (1 × 10 5 Sm −1 ) antennas. Printed bioinert or ecoresorbable conductors, comprising carbon, magnesium, or zinc fillers, typically exhibit conductivity on the order of 10–1000 Sm −1 and lifetimes from a few hours to a few days. A print‐based fabrication process for chemically treated zinc traces, which achieves conductivity of up to 6 × 10 5 Sm −1 is reported here. The ink formulation uses a non‐water‐soluble soil biodegradable polycaprolactone binder. The ink and printing processes reported here led to stable conductive traces that are used in ultra high frequency radio frequency identification (UHF‐RFID) folded dipole antennas operating at 915 MHz. The conductivity of the printed traces is maintained for over 70 days in ambient environments when traces are protected by a biodegradable beeswax encapsulation layer.

Baumbauer, Carol L.↗
DOE OSTI2023

Holographic Nano‐Imaging of Terahertz Dirac Plasmon Polaritons in Topological Insulator Antenna Resonators

Abstract Excitation of Dirac plasmon polaritons (DPPs) in bi‐dimensional materials have attracted considerable interest in recent years, both from perspectives of understanding their physics and exploring their transformative potential for nanophotonic devices, including ultra‐sensitive plasmonic sensors, ultrafast saturable absorbers, modulators, and switches. Topological insulators (TIs) represent an ideal technological platform in this respect because they can support plasmon polaritons formed by Dirac carriers in the topological surface states. Tracing propagation of DPPs is a very challenging task, particularly at terahertz (THz) frequencies, where the DPP wavelength becomes over one order of magnitude shorter than the free space photon wavelength. Furthermore, severe attenuation hinders the comprehensive analysis of their characteristics. Here, the properties of DPPs in real TI‐based devices are revealed. Bi 2 Se 3 rectangular antennas can efficiently confine the propagation of DPPs to a single dimension and, as a result, enhance the DPPs visibility despite the strong intrinsic attenuation. The plasmon dispersion and loss properties from plasmon profiles are experimentally determined, along the antennas, obtained using holographic near‐field nano‐imaging in a wide range of THz frequencies, from 2.05 to 4.3 THz. The detailed investigation of the unveiled DPP properties can guide the design of novel topological quantum devices exploiting their directional propagation.

Chemistry↗
DOE OSTI2025

Decoding Antenna Behavior in Metal—Organic Frameworks

Metal–organic frameworks (MOFs) define a solid-state platform for developing artificial photosystems. Efficient anisotropic exciton migrations in these frameworks entail “antenna behavior” that can power up the distal interior reaction centers (RC), driving charge separation between donor-acceptor pairs. Reminiscent of the natural light-harvesting complex, such processes can achieve high quantum yield by exploiting the vast interior surface of the porous crystallites. It is important to understand the optimum positioning of the RC site relative to the anisotropic exciton migration path within these frameworks. The efficiency of such antenna behavior is probed here through Stern–Volmer (SV) type analysis with a series of node-anchored redox quenchers, ferrocene-carboxylate, ferrocene acetate, and dinitrobenzoate. Decoding various intrinsic processes, this work constructs a revised SV formalism in solid assembly that hosts ultrafast anisotropic exciton migration to account for the intrinsic exciton hopping rate from the extrinsic electron transfer rate, and the dimension of effective quenching. In conclusion, this transformative understanding can be applied to other relevant solid-state assemblies.

Saha, Bapan [Southern Illinois University, Carbond↗
DOE OSTI2024

Gluon to $\textrm{q}\overline{\textrm{q}}$ antenna in anisotropic QCD matter: spin-polarized and azimuthal jet observables

We study the production of a quark-antiquark antenna in the presence of a dense and anisotropic QCD medium. We assume the antenna to originate from an unpolarized gluon state, and consider both massless and massive final states. The medium anisotropy is captured by allowing the jet quenching coefficient to take different magnitudes in orthogonal directions with respect to the jet axis. We find that the final particle distribution is sensitive to the medium anisotropy, and more importantly, that this effect couples directly to the helicity/spin of the final states. We propose to look into these effects by performing a Fourier decomposition of the particle distribution inside the jet. In our medium model, we find that the spin independent terms contribute to the even harmonics of the cosine series. The helicity/spin dependence enters only through the sine Fourier series. We further explore the spin dependence by examining the degree of polarization of the final states in different directions. Our results indicate that the anisotropies present in the QCD matter produced in heavy ion collisions can be probed by studying azimuthal and spin observables inside jets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Biochemical and spectroscopic characterizations of the oligomeric antenna of the coral symbiotic Symbiodiniaceae Fugacium kawagutii

Light-harvesting antennas in photosynthesis capture light energy and transfer it to the reaction centers (RCs) where photochemistry takes place. The sustainable growth of the reef-building corals relies on a constant supply of the photosynthates produced by the endosymbiotic dinoflagellate, belonging to the family of Symbiodiniaceae. The antenna system in this group consists of the water-soluble peridinin-chlorophyll $\textit{a}$-protein (PCP) and the intrinsic membrane chlorophyll $\textit{a}$-chlorophyll $c_2$-peridinin protein complex (acpPC). In this report, a nonameric acpPC is reported in a dinoflagellate, Fugasium kawagutii (formerly Symbiodinium kawagutii sp. CS-156). We found that extensive biochemical purification altered the oligomerization states of the initially isolated nonameric acpPC. The excitation energy transfer pathways in the acpPC nonamer and its variants were studied using time-resolved fluorescence and time-resolved absorption spectroscopic techniques at 77 K. Compared to the well-characterized trimeric acpPC, the nonameric acpPC contains an 11 nm red-shifted terminal energy emitter and substantially altered excited state lifetimes of Chl $\textit{a}$. The observed energetic overlap of the fluorescence terminal energy emitters with the absorption of RCs is hypothesized to enable efficient downhill excitation energy transfer. Additionally, the shortened Chl $\textit{a}$ fluorescence decay lifetime in the oligomeric acpPC indicate a protective self-relaxation strategy. We propose that the highly-oligomerized acpPC nonamer represents an intact functional unit in the Symbiodiniaceae thylakoid membrane. They perform efficient excitation energy transfer (to RCs), and are under manageable regulations in favor of photoprotection.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

“Antenna-like” Light-Harvesting in Partially Metalated Porphyrin Hydrogen-Bonded Organic Frameworks

Arrays of light harvesting molecules with long-range order hold promise as materials capable of efficient collection of photons as well as rapid transport of captured solar energy to chemical catalysts. Hydrogen-bonded organic frameworks (HOFs) could be promising artificial light-harvesting platforms, due to their crystalline nature and their comparative ease of synthesis. In this work, mixed-linkers of either zinc-metallated or free base tetrakis(4-carboxyphenyl)porphyrin HOFs were examined and found to demonstrate ‘antenna-like’ light harvesting behavior. Using time-resolved emission spectroscopy, Förster resonance energy transfer from zinc porphyrin to free-base porphyrin was assessed. Based on changes in the emission peak profile as the ratio of zinc porphyrin to free-base porphyrin is varied, we find that, in the limit of 100% zinc porphyrin, a photogenerated exciton can sample ~48 chromophores. These findings suggest that stacked linkers within HOFs can act as light harvesting ‘antennae’ and with encapsulation of suitable catalysts, may offer prospective application as photochemical energy conversion systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Terahertz quantum-cascade patch-antenna VECSEL with low power dissipation

We report a terahertz quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL) based upon a metasurface consisting of an array of gain-loaded resonant patch antennas. Compared with the typical ridge-based metasurfaces previously used for QC-VECSELs, the patch antenna surface can be designed with a much sparser fill factor of gain material, which allows for reduced heat dissipation and improved thermal performance. Here, it also exhibits larger amplification thanks to enhanced interaction between the incident radiation and the QC-gain material. We demonstrate devices that produce several milliwatts of continuous-wave power in a single mode at ~4.6 THz and dissipate less than 1 W of pump power. Use of different output couplers demonstrates the ability to optimize device performance for either high power or high operating temperature. Maximum demonstrated power is 6.7 mW at 4 K (0.67% wall-plug efficiency, WPE) and 0.8 mW at 77 K (0.06% WPE). Directive output beams are measured throughout with divergence angles of ~5°.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Validation of high-fidelity ion cyclotron range of frequencies antenna coupling simulations in full 3D geometry against experiments in the ASDEX Upgrade tokamak

We address the validation of finite elements ion cyclotron range of frequencies (ICRF) antenna coupling simulation against experiments performed in the ASDEX Upgrade tokamak. Measurements of the loading resistance in ICRF-heated, magnetically-perturbed 3D plasma discharges are compared against numerical predictions of the RAPLICASOL code. To this end, the 3D induction field and the 3D density profile are modeled by concatenating the PARVMEC, BMW and EMC3-EIRENE codes. The 3D density is input to RAPLICASOL, where full-wave simulations are performed on a finite element mesh retaining full 3D geometry in the ICRF antenna model and the plasma description. The results are further compared with RAPLICASOL simulations using a 1D density profile as measured at the outboard midplane in the same experiments. We find that simulations using a 1D density profile overestimate the change in loading resistance by a factor of ~197 -248%, while simulations using the full 3D density profile are in agreement with experiments within a factor ~16%.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Experimental determination of axion signal power of dish antennas and dielectric haloscopes using the reciprocity approach

The reciprocity approach is a powerful method to determine the expected signal power of axion haloscopes in a model-independent way. Especially for open and broadband setups like the MADMAX dielectric haloscope the sensitivity to the axion field is difficult to calibrate since they do not allow discrete eigenmode analysis and are optically too large to fully simulate. The central idea of the reciprocity approach is to measure a reflection-induced test field in the setup instead of trying to simulate the axion-induced field. In this article, the reciprocity approach is used to determine the expected signal power of a dish antenna and a minimal dielectric haloscope directly from measurements. The results match expectations from simulation but also include important systematic effects that are too difficult to simulate. In particular, the effect of antenna standing waves and higher order mode perturbations can be quantified for the first time in a dielectric haloscope.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

First Results from a Broadband Search for Dark Photon Dark Matter in the 44 to 52 μ eV Range with a Coaxial Dish Antenna

We present first results from a dark photon dark matter search in the mass range from 44 to 52 μ eV (10.7–12.5 GHz) using a room-temperature dish antenna setup called GigaBREAD. Dark photon dark matter converts to ordinary photons on a cylindrical metallic emission surface with area 0.5 m 2 and is focused by a novel parabolic reflector onto a horn antenna. Signals are read out with a low-noise receiver system. A first data taking run with 24 days of data does not show evidence for dark photon dark matter in this mass range, excluding dark photon photon mixing parameters χ ≳ 10 − 12 in this range at 90% confidence level. This surpasses existing constraints by about 2 orders of magnitude and is the most stringent bound on dark photons in this range below 49 μ eV . Published by the American Physical Society 2024

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

On the Performance of Tree-Based Antennas for SLF-VLF Signal Reception

A full-wave electromagnetic simulation and experimental study is carried out to explore the effects of tree-induced dielectric loading on the receiving properties of an electrically small, earth-grounded wire monopole. It is demonstrated that by connecting the upper end of the wire to the tree trunk, the input impedance of the monopole can be significantly transformed, leading to an enhancement in the received signal strength that becomes more noticeable as the frequency is decreased; for example, at the lowest frequency considered, it is seen that the tree-loaded antenna can increase the received load voltage by as much as ~40 dB, when compared to the case without tree loading. An application of the tree-based antenna for low-frequency power line signal monitoring is presented. Overall, simulation results for the input impedance and received signal response are in good agreement with measurement data.

Liao, DaHan↗
DOE OSTI2021

Design and characterization of microstrip patch antennas for high-T c superconducting terahertz emitters

We designed and characterized a microstrip pattern of planar patch antennas compatible with a cuprate high- T c superconducting terahertz emitter. Antenna parameters were optimized using an electromagnetic simulator. We observed repeatable sub-terahertz emissions from each mesa fabricated on identical Bi 2 Sr 2 CaCu 2 O 8+δ base crystals in a continuous frequency range of 0.35–0.85 THz. Although there was no significant output power enhancement, a plateau behavior at a fixed frequency was observed below 40 K, indicating moderate impedance matching attributable to the ambient microstrip pattern. A remarkably anisotropic polarization at an axial ratio of up to 16.9 indicates a mode-locking effect. Our results enable constructing compactly assembled, monolithic, and broadly tunable superconducting terahertz sources.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

All-dielectric multi-resonant bullseye antennas

Integrated devices that generate multiple optical resonances in the same volume can enhance on-chip nonlinear frequency generation, nonlinear spectroscopy, and quantum sensing. Here, we demonstrate circular Bragg antennas that exhibit multiple spatially overlapping, polarization-selective optical resonances. Using templated atomic layer deposition of TiO 2 , these devices can be fabricated on arbitrary substrates, making them compatible with a wide range of nonlinear materials and sensing targets, and couple efficiently to underlying films. In this work, we detail the design, simulation, and fabrication of all-dielectric multi-resonant bullseye antennas and characterize their performance using polarized broadband reflection spectroscopy.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Transportation Fatigue Testing of the pHB650 Power Coupler Antenna for the PIP-II Project at Fermilab

The PIP-II Project will see international shipment of cryomodules from Europe to the United States, and as such, the shocks which can occur during shipment pose a risk to the internal components. Of particular concern is the coupler ceramic window and surrounding brazes, which can see relatively high stress during an excitation event. Since the antenna design is new, and because of the setback failure would create, a cyclic stress test was devised for the antenna. This paper presents the experimental methods, setup, and results of the test.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Two-Channel Monopulse Antenna Null Steering

Traditional dual-channel phase-monopulse and amplitude-monopulse antenna systems might electrically steer their difference-channel nulls by suitably adjusting characteristics of their constituent beams or lobes. A phase-monopulse systems' null might be steered by applying suitable relative phase shifts. An amplitude-monopulse systems' null might be steered by applying a suitable relative beam amplitude scaling. The steering of the null might be employed by a continuously mechanically-scanning antenna to stabilize the null direction over a series of radar pulses.

42 ENGINEERING↗
DOE OSTI2023

Transportation Fatigue Testing of the pHB650 Power Coupler Antenna for PIP-II at FNAL

The PIP-II Project will see international shipment of cryomodules Proton Improvement Plan-II from Europe to the United States, and as such, the shocks which can occur during shipment pose a risk to the internal components. Of particular concern is the coupler ceramic window and surrounding brazes, which will see stresses during an excitation event. Since the antenna design is new, and because of the setback failure would create, a cyclic stress test was devised for the antenna. This paper presents the experimental methods, setup, and results of the test.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Notes on Amplitude versus Phase Comparison Monopulse Antennas for Radar

Monopulse is a technique for determining the Direction of Arrival (DOA) of a radar echo by comparing the simultaneous signal responses from two or more antenna beams or apertures. Two principal architectures are employed: 1) amplitude-comparison monopulse, and 2) phase-comparison monopulse. For a constrained-size fully and uniformly illuminated aperture, there is no meaningful difference between the DOA angle precision achievable by an amplitude monopulse architecture versus a phase monopulse architecture. DOA angle estimation precision is almost exclusively a function of antenna size, operating wavelength, and SNR, regardless of amplitude versus phase monopulse architectures.

47 OTHER INSTRUMENTATION↗