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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

SYNCA: A Synthetic Cyclotron Antenna for the Project 8 Collaboration

Cyclotron Radiation Emission Spectroscopy (CRES) is a technique for measuring the kinetic energy of charged particles through a precision measurement of the frequency of the cyclotron radiation generated by the particle's motion in a magnetic field. The Project 8 collaboration is developing a next-generation neutrino mass measurement experiment based on CRES. One approach is to use a phased antenna array, which surrounds a volume of tritium gas, to detect and measure the cyclotron radiation of the resulting β-decay electrons. To validate the feasibility of this method, Project 8 has designed a test stand to benchmark the performance of an antenna array at reconstructing signals that mimic those of genuine CRES events. To generate synthetic CRES events, a novel probe antenna has been developed, which emits radiation with characteristics similar to the cyclotron radiation produced by charged particles in magnetic fields. This paper outlines the design, construction, and characterization of this Synthetic Cyclotron Antenna (SYNCA). Furthermore, we perform a series of measurements that use the SYNCA to test the position reconstruction capabilities of the digital beamforming reconstruction technique. Finally, we find that the SYNCA produces radiation with characteristics closely matching those expected for cyclotron radiation and reproduces experimentally the phenomenology of digital beamforming simulations of true CRES signals.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

THz Radiation Generation to Enable Internal Magnetic Field Measurement of Burning Plasmas (Final Scientific Report)

A one-year experimental program was performed using the Multi-TeraWatt (MTW) laser at the Laboratory for Laser Energetics (LLE) to investigate the efficiency and physical process of laser-driven—wire THz generation. This process was evaluated as a potential high-repetition-rate source of powerful THz pulses for use in THz pulsed polarimetry of a moderate-density magnetic-confinement fusion concept developed by TAE. The goal was to develop a source for short pulses in the THz regime (150 μm wavelength) containing 10’s of mJ. The campaign tested the impact of Cu wire diameter (25, 75, 160 μm), length (250 – 750 μm), and laser irradiation orientation on THz production efficiency in comparison to 20-μm thick Cu foils. Of these targets, the 160 µm diameter, 750 µm long wires with sharpened tips and irradiated at the base were found to produce the highest energy and shortest wavelength THz pulses, exceeding 2.5 Joule/sr and meeting the requirements for the polarimetry diagnostic. The brightest THz signal was radiated in the direction of the sharpened wire tip. A combination of two models – a traveling wave antenna combined with coherent transition radiation – describes the emission pattern, pulse energy, and spectrum observed in the experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Enhanced Planar Antenna Efficiency Through Magnetic Thin-Films

This work proposes to use magnetic material as the substrate of planar antennas to overcome the platform effect caused by the conducting ground plane. The upper bound of the radiation efficiency of an electric-current-driven low-profile antenna is theoretically derived, which is inversely proportional to the Gilbert damping factor of the magnetic material. Meanwhile, the improvement of radiation due to the use of magnetic material is demonstrated by a three-dimensional (3D) multiphysics and multiscale time-domain model. The simulation results match the theoretical derivation, showing 25% radiation efficiency from a planar antenna backed by a FeGaB thin film with 2.56 m thickness. Furthermore, for conductive ferromagnetic materials, it is shown that the eddy current loss can be well suppressed by laminating the thin film into multiple layers. Here, the radiation efficiency of the modeled antenna with a conductive ferromagnetic substrate is improved from 2.2% to 11.8% by dividing the substrate into 10 layers, with a ferromagnetic material fill factor of 93%.

42 ENGINEERING↗
DOE OSTI2020

An Unbalanced Sinuous Antenna for Near-Surface Polarimetric Ground-Penetrating Radar

Sinuous antennas are capable of producing ultra-wideband radiation with polarization diversity. This capability makes the sinuous antenna an attractive candidate for UWB polarimetric radar applications. Additionally, the ability of the sinuous antenna to be implemented as a planar structure makes it a good fit for close-in sensing applications such as ground-penetrating radar (GPR). In this work, each arm of a four-port sinuous antenna is operated independently to achieve a quasi-monostatic antenna system capable of polarimetry while separating transmit and receive channels—which is often desirable in GPR systems. The quasi-monostatic configuration of the sinuous antenna reduces system size as well as prevents extreme bistatic angles, which may significantly reduce sensitivity when attempting to detect near-surface targets. A prototype four-port sinuous antenna is fabricated and integrated into a GPR testbed. The polarimetric data obtained with the antenna is then used to distinguish between buried target symmetries.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Information Carried by Electromagnetic Radiation Launched from Accelerated Polarization Currents

We show experimentally that a continuous, linear, dielectric antenna in which a superluminal polarization-current distribution accelerates can be used to transmit a broadband signal that is reproduced in a comprehensible form at a chosen target distance and angle. The requirement for this exact correspondence between broadcast and received signals is that each moving point in the polarization-current distribution approaches the target at the speed of light at all times during its transit along the antenna. This results in a one-to-one correspondence between the time at which each point on the moving polarization current enters the antenna and the time at which all of the radiation emitted by this particular point during its transit through the antenna arrives simultaneously at the target. This has the effect of reproducing the desired time dependence of the original broadcast signal. For other observer-detector positions, the time dependence of the signal is scrambled, due to the nontrivial relationship between emission (retarded) time and reception time. This technique represents a contrast to conventional radio transmission methods; in most examples of the latter, signals are broadcast with little or no directivity, selectivity of reception being achieved through the use of narrow frequency bands. In place of this, the current paper uses a spread of frequencies to transmit information to a particular location; the signal is weaker and has a scrambled time dependence elsewhere. Here, we point out the possible relevance of this mechanism to 5G neighborhood networks and pulsar astronomy.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons

The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1 μ m - 3 , tens of orders of magnitude greater than the equilibrium density expected from theory. Nonequilibrium quasiparticles extract energy from the qubit mode and can induce dephasing. Here we show that a dominant mechanism for quasiparticle poisoning is direct absorption of high-energy photons at the qubit junction. We use a Josephson junction-based photon source to controllably dose qubit circuits with millimeter-wave radiation, and we use an interferometric quantum gate sequence to reconstruct the charge parity of the qubit. We find that the structure of the qubit itself acts as a resonant antenna for millimeter-wave radiation, providing an efficient path for photons to generate quasiparticles. A deep understanding of this physics will pave the way to realization of next-generation superconducting qubits that are robust against quasiparticle poisoning.

Liu, Chuan-Hong↗
DOE OSTI2025

Directional, joule per steradian THz pulses from multi-joule laser irradiation of wires

We report on THz pulses with energy flux exceeding 2.5 J/sr and high directionality, generated from picosecond, joule laser irradiation of microwires. The impact of wire diameter, length, and laser irradiation orientation is explored with the irradiation of 160 μm diameter, 750 μm, sharpened wires at the dull base found to produce the highest energy and shortest wavelength THz pulses among the targets tested. A traveling wave antenna combined with coherent transition radiation model is developed to explain the emission pattern, pulse energy, and spectrum seen.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

A High Gain Lens-Coupled On-Chip Antenna Module for Miniature-Sized Millimeter-Wave Wireless Transceivers

This paper presents high gain and compact Transmit/Receive (TX/RX) integrated antennas in a standard BiCMOS 130nm technology for millimeter-scale millimeter-wave (mm-wave) applications, including high data rate radios and high resolution radars. The proposed TX/RX antenna module utilizes an integrated dipole antenna for the receiver and a slot antenna for the transmitter, placed orthogonally. The achieved gain and radiation efficiency are 5.7dBi and 41.3% for the slot antenna, respectively, and 6dBi and 39% for the dipole antenna. The link budget is improved by 16dB by optimization on the geometry aswell as application of a high resistivity hemispheric silicon dielectric lens.

Engineering↗
DOE OSTI2021

Microfabricated ion trap chip with an integrated microwave antenna

An ion trap chip, which may be used for quantum information processing and the like, includes an integrated microwave antenna. The antenna is formed as a radiator connected by one of its ends to the center trace of a microwave transmission line and connected by its other end to a current return path through a ground trace of the microwave transmission line. The radiator includes several parallel, coplanar radiator traces connected in series. The radiator traces are connected such that they all carry electric current in the same direction, so that collectively, they simulate a single, unidirectionally flowing sheet of current. In embodiments, induced currents in underlying metallization planes are suppressed by parallel slots that extend in a direction perpendicular to the radiator traces.

Nordquist, Christopher↗
DOE OSTI2020

Observation of a THz-sub-THz spontaneous coherent undulator radiation driven by a low energy electron beam from a thermionic RF electron gun

In this work, we report observations of an intense, multi-band, sub-THz and THz radiation extracted from a similar to 2-3 MeV electron beam with a flat transverse profile propagating in an oversized rectangular waveguide placed into a 3.25 mm gap of a planar undulator having 1.3 cm period and similar to 20 cm length. Radiation outcoupling is accomplished using a horn antenna and a miniature permanent in-vacuum magnet separating the mm-sub-mm-waves and electron beam. A table-top experiment utilizes a radio frequency thermionic electron gun delivering a thousand momentum-chirped microbunches per macropulse and an alpha-magnet producing microbunches of a sub-mm length. Total radiated energy of a sub-millijoule per a microsecond radio frequency macropulse is demonstrated with flux more than ten micro-Joules per centimeter squared. With 1 THz filter the energy measured is about 1 microjoule and flux of a few micro-Joules per centimeter squared.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

3D Printing Prototypes for a Reflector-Based Broadband Axion Search

This work sought to begin research and development on a horn antenna which can be used to transfer the energy of microwave photons produced by axions in a strong magnetic field to a coaxial cable for measurement. 3D prototypes of pyramidal horn antennas and a parabolic reflector were printed and then coated with conductive spray paint. The S 11 parameter was measured and simulated for both 3D printed horn antenna and the conical horn antenna both with and without the reflector present to determine how much of the radiated power was reflected back. Ultimately, for both the conical and pyramidal antennas, less than one percent of the energy emitted by the antennas was reflected back. When the pyramidal antenna was tilted by about 45 degrees, however, around 30-40 percent of the microwaves emitted by the antennas was reflected back.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Neutron radiation hardness of aluminum gallium nitride UV LEDs at various wavelengths

Radiation hard diagnostics are critical to the success of nuclear fusion at National Ignition Facility, Z, ITER, and prolonged space explorations. We have first demonstrated the exceptional proton radiation hardness of initial GaN devices and qualified their space flight and deployment for missions such as the Laser Interferometer Space Antenna and International Space Station. We have further conducted neutron radiation hardness experiments at Los Alamos Neutron Science Center by opening a new high fluence beam station. During 2014–2016, we irradiated multiple Aluminum Gallium Nitride (AlGaN) LEDs with a maximum fluence of 2.4 × 1013 neutrons/cm2 in 3 years and generated 54 161 current–voltage (I–V) scan traces. Our data processing program analyzes each and all I–V traces. In addition, we retrieved local temperature records to analyze and remove temperature effects in the outdoor environment. The I–V curve families of AlGaN UV LEDs with emitting wavelengths of 265, 275, and 310 nm were compared. The I–V curves of 265 nm AlGaN UV LEDs have the smallest deviations from the average value, while the I–V curves for 310 nm AlGaN LEDs showed the largest deviations from the average value. We have reached another important recommendation for the optimal use of multiple AlGaN optoelectronic devices or imaging arrays for inertially confined fusion diagnostics: Shorter wavelength devices at 265 nm exhibit more consistent radiation hardness performance than the 310 nm devices. Higher aluminum content LEDs or AlxGa1–xN devices with higher mole fraction x for generating shorter wavelengths have better radiation hardness for fusion diagnostics.

Sun, K. -X. (ORCID:0000000224659235)↗
DOE OSTI2023

The Princeton Field-Reversed Configuration for Compact Nuclear Fusion Power Plants

The Princeton Field-Reversed Configuration (PFRC) nuclear fusion reactor concept is an innovative approach to fusion power generation prioritizing low neutron production and small size. Here, a combination of analytical modeling and numerical simulation shows that the novel heating approach generates an FRC with closed field lines. Simulation data from a single-particle Hamiltonian code predicts ms-scale plasma heating in reactor-scale conditions while PIC codes predict formation of warm FRC plasmas from initial mirror fields. The PFRC-1 and PFRC-2 experiments have heated electrons to energies well in excess of 100 eV and plasma durations to 300 ms, more than 10 4 times longer than the predicted tilt instability growth time. From these data, we have created a development plan and anticipated performance metrics for a fusion reactor based on the PFRC concept. The resulting 1–10 MW PFRC reactors would be suitable for diverse applications, from submarines to urban environments to space propulsion. PFRC is a steady-state, driven magnetic confinement device. Plasma, inside a cylindrical array of coils, is confined and heated by external RF antennae. PFRC would be ultra-low radiation due to both its fuel and small size. The choice of advanced fuels, deuterium and helium-3 (D– 3 He), may be enabled by the high-β FRC configuration. The small size of the reactor would enable rapid exhaust of the dangerous tritium ash. Low radiation would make the reactor safer to operate and, in combination with simple geometry and small size, dramatically lowers development and maintenance costs. This review paper gives an introduction to the physics of the PFRC and a summary of the PFRC-2 experiment results to date. It then discusses the future program plan and how PFRC reactors would be commercialized.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2026

Corrected Moments in Antenna Coordinates (CMAC) Technical Report

Various corrections are needed in order to extract the best value of the measurements from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) User Facility’s scanning precipitation radars. The Corrected Moments in Antenna Coordinates (CMAC) Value-Added Product provides an application chain for providing radar moments that are corrected for artifacts such as aliasing, attenuation, multi-trip echoes, and beam blockage. This technical report provides details on the entire process of correcting the ARM scanning precipitation radar data using CMAC. CMAC has been used at multiple ARM sites and ARM Mobile Facility deployments including the Tracking Aerosol Convection Interactions Experiment (TRACER), Cloud, Aerosol, and Complex Terrain Interactions (CACTI), and the Surface Atmosphere Integrated Laboratory (SAIL).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Plastic Laminate Antireflective Coatings for Millimeter-Wave Optics in BICEP Array

The BICEP/Keck series of experiments target the cosmic microwave background at degree-scale resolution from the South Pole. Over the next few years, the “Stage-3” BICEP Array (BA) telescope will improve the program’s frequency coverage and sensitivity to primordial B-mode polarization by an order of magnitude. The first receiver in the array, BA1, began observing at 30/40 GHz in early 2020. The next two receivers, BA2 and BA3, are currently being assembled and will map the southern sky at frequencies ranging from 95 to 150 GHz. Common to all BA receivers is a refractive, on-axis, cryogenic optical design that focuses microwave radiation onto a focal plane populated with antenna-coupled bolometers. High-performance antireflective coatings up to 760 mm in aperture are needed for each element in the optical chain, and must withstand repeated thermal cycles down to 4 K. Here, in this work, we present the design and fabrication of the 30/40 GHz anti-reflection coatings for the recently deployed BA1 receiver, with indices matched to its various polyethylene, nylon and alumina optical components. We describe an epoxy coating technique designed for alumina optics, which achieves better than 80% transmission at room temperature. For polyethylene optical elements, we present a new heat-compression approach that allows low-density polytetrafluoroethylene AR layers to reach sub-percent reflected power. We describe the planned use of these methods for the next BA cryostats, which may inform technological choices for future small-aperture telescopes of the CMB-S4 experiment.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Antenna system

An antenna system comprises a substrate, an antenna positioned on the substrate, and a circuit component positioned on the substrate. The antenna is positioned on a first surface of the substrate and operable to emit a radiation pattern. The circuit component is positioned on the substrate in a null region of the radiation pattern. The thickness of portions of the substrate are modified to achieve a desired performance characteristic of the antenna.

Byers, Kyle J.↗
DOE OSTI2022

Corrected Moments in Antenna Coordinates (CMAC) X-SAPR Technical Report

In 2010 the Atmospheric Radiation Measurement user facility procured 3- and 5-cm wavelength radars for documenting the macrophysical, microphysical, and dynamical structure of precipitating systems. In order to maximize the scientific impact, the program supported the development of an application chain to correct for various phenomena in order to retrieve the “point” values of moments of the radar spectrum and polarimetric measurements. This report details the motivation, science, and progress to date as well as charting a path forward.

54 ENVIRONMENTAL SCIENCES↗