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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Three-Dimensional Magnetic-Bubble Memory System

Proposed magnetic-bubble memory system includes stack of two-dimensional memory modules. Design enables overall storage density of system to be greater than prior magnetic-bubble memories. Provides nonvolatile storage, with readout access times in millisecond range. Has partly parallel input/output configuration supporting high-performance computing. Also relatively invulnerable to damage by ionizing radiation. Binary data, as represented by direction of magnetization of magnetic bubbles, reads out via Faraday effect.

Katti, Romney R.↗
NASA NTRS1991

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Depaula, Ramon P.↗
NASA NTRS1994

Fiber-Optic Ammeter

In addition to fiber-optic loop, apparatus includes stable source of coherent light and high-resolution optical receiver. Magnetic field generated by electric current measured via Faraday effect. Developed to measure electric currents and/or magnetic fields in outer space as part of effort to determine number densities and directions of movement of electrically charged particles; loop of low-loss optical fiber made large enough so number of charged particles encircled adaquate for measurement. Apparatus also used on Earth in noncontact measurements of electric currents.

Wyntjes, Geert↗
NASA NTRS1995

Actively Pumped Optical Filters at 532 nm

The operation of two narrow-band optical filters at 532.33 nm is presented. Both of these filters operate on the 4P(sub 1/2) to 8S(sub 1/2) excited-state transition in potassium vapor. One of the filters is based on excited-state Faraday effect, and requires the application of an external axial magnetic field. The peak transmission of this filter is approximately 3.5% with a linewidth of less than 10 GHz. The second filter does not require a magnetic field for its operation, but readily attains peak transmissions of 25-30%. The 4P(sub 1/2) state is excited by a 769.9 nm light pulse which is linearly polarized for the first scheme and circularly polarized for the second.

Billmers, Richard I.↗
NASA NTRS1994

Three-dimensional magnetic bubble memory system

A compact memory uses magnetic bubble technology for providing data storage. A three-dimensional arrangement, in the form of stacks of magnetic bubble layers, is used to achieve high volumetric storage density. Output tracks are used within each layer to allow data to be accessed uniquely and unambiguously. Storage can be achieved using either current access or field access magnetic bubble technology. Optical sensing via the Faraday effect is used to detect data. Optical sensing facilitates the accessing of data from within the three-dimensional package and lends itself to parallel operation for supporting high data rates and vector and parallel processing.

Stadler, Henry L.↗
DOE OSTI2022

Super resolution for magneto-optical microscopy

Sub-diffraction limited magneto-optical microscopy, such as Kerr or Faraday effect microscopy, provide many advantages to fields of science and technology for measuring, or imaging, the magnetization structures and magnetization domains of materials. Disclosed is a method and system for performing sub-diffraction limited magneto-optic microscopy. The method includes positioning a microlens or microlens layer relative to a surface of a sample to image the surface of the sample, forming a photonic nanojet to probe the surface of the sample, and receiving light reflected by the surface of the sample or transmitted through the sample at an imaging sensor. The methods and associated systems and devices enable sub-diffraction limited imaging of magnetic domains at resolutions 2 to 8 times the classical diffraction limit.

te Velthuis, Suzanne Gabriëlle Everdine↗
DOE OSTI2024

Polarimetry-Interferometry Diagnostic for Magnetic Field and Magnetic Fluctuation Measurements in High-Performance and Long-Pulse Tokamaks (Final Report)

In this grant, we executed a multi-year plan to develop an advanced Faraday-effect polarimeter-interferometer system to address both fluctuation and equilibrium diagnostic needs by providing a measurement of the plasma internal magnetic field fluctuations (including non-axisymmetric 3-D perturbations) and plasma vertical position. This diagnostic included both fast time response and low phase noise so that both the temporal dynamics of equilibrium quantities as well as high-frequency electromagnetic fluctuations could be measured simultaneously, adding new and unique measurement capabilities for the core of high-temperature plasmas. The combined polarimeter-interferometer diagnostic development was applied primarily to the tokamak magnetic configuration, focusing on high-performance regimes including H-mode, reversed shear advanced tokamak scenarios, and non-inductive current drive.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Kerr, Faraday, and magnetoelectric effects in MnBi 2 Te 4 thin films

The topological magnetoelectric effect (TME) is a characteristic property of topological insulators. In this paper, we use a simplified coupled-Dirac-cone electronic structure model to theoretically evaluate the THz and far infrared Kerr and Faraday responses of thin films of MnBi 2 ⁢Te 4 with up to N = 10 septuple layers with the goal of clarifying the relationship between these convenient magnetooptical observables and the TME. Here we find that for even N, the linear Kerr and Faraday responses to an electric field vanish in the low-frequency limit, even though the magnetoelectric response is large and approximately quantized.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Orbital Inverse Faraday and Cotton-Mouton Effects in Hall Fluids

We report two light-induced orbital magnetization effects in quantum Hall (QH) fluids, stemming from their transverse response. The first is a purely transverse contribution to the inverse Faraday effect (IFE), where circularly polarized light induces a dc magnetization by stirring the charged fluid. This contribution dominates the IFE in the QH regime. The second is the orbital inverse Cotton-Mouton effect (ICME), in which linearly polarized light generates a dc magnetization. Since the applied field in the ICME does not break time-reversal symmetry, the induced magnetization directly probes the chiral orbital response of the fluid at the driving frequency. We estimate that the resulting magnetization lies in the range of 0.5–10 Bohr magnetons per charge carrier in materials such as graphene and transition-metal dichalcogenides (TMDs) in the QH regime. Finally, we show that the induced magnetization is accompanied by a local correction to the static particle density, enabling optical quantum printing of density profiles into the QH fluid.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1993

Faraday anomalous dispersion optical filters

The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.

Shay, T. M.↗
NASA NTRS2003

The Effect of Rotating a Faraday Disc Perpendicular to an Applied Magnetic Field Theory and Experiment

A magnetohydrodynamic model that examines the effect of rotating an electrically conducting cylinder with a uniform external magnetic field applied orthogonal to its axis is presented. Noting a simple geometry, it can be classified as a fundamental dynamo problem. For the case of an infinitely long cylinder, an analytical solution is obtained and analyzed in detail. A semi-analytical model was developed that considers a finite cylinder. Experimental data from a spinning brass wheel in the presence of Earth's magnetic field were compared to the proposed theory and found to fit well.

Mazuruk, Konstantin↗
NASA NTRS1984

The Faraday rotation experiment

The magnetized plasma of the solar corona was remotely sounded using the Faraday rotation effect. The solar magnetic field together with the electrons of the coronal plasma cause a measurable Faraday rotation effect, since the radio waves of Helios are linearly polarized. The measurement is performed at the ground stations. Alfven waves traveling from the Sun's surface through the corona into interplanetary space are observed. Helios 2 signals penetrating through a region where coronal mass is ejected show wavelike structures.

Volland, H.↗
DOE OSTI2013

CONSTRAINING PRIMORDIAL MAGNETIC FIELDS THROUGH LARGE-SCALE STRUCTURE

We study primordial magnetic field effects on the matter perturbations in the universe. We assume magnetic field generation prior to the big bang nucleosynthesis (BBN), i.e., during the radiation-dominated epoch of the universe expansion, but do not limit analysis by considering a particular magnetogenesis scenario. Contrary to previous studies, we limit the total magnetic field energy density and not the smoothed amplitude of the magnetic field at large (of the order of 1 Mpc) scales. We review several cosmological signatures, such as halo abundance, thermal Sunyaev-Zel'dovich effect, and Ly{alpha} data. For a cross-check, we compare our limits with that obtained through the cosmic microwave background faraday rotation effect and BBN. The limits range between 1.5 nG and 4.5 nG for n{sub B} in (- 3; -1.5).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Synchrotron Intensity Gradients as Tracers of Interstellar Magnetic Fields

On the basis of the modern understanding of MHD turbulence, we propose a new way of using synchrotron radiation: using synchrotron intensity gradients (SIGs) for tracing astrophysical magnetic fields. We successfully test the new technique using synthetic data obtained with 3D MHD simulations and provide the demonstration of the practical utility of the technique by comparing the directions of magnetic fields that are obtained with PLANCK synchrotron intensity data to the directions obtained with PLANCK synchrotron polarization data. We demonstrate that the SIGs can reliably trace magnetic fields in the presence of noise and can provide detailed maps of magnetic field directions. We also show that the SIGs are relatively robust for tracing magnetic fields while the low spatial frequencies of the synchrotron image are removed. This makes the SIGs applicable to the tracing of magnetic fields using interferometric data with single-dish measurement absent. We discuss the synergy of using the SIGs together with synchrotron polarization in order to find the actual direction of the magnetic fields and quantify the effects of Faraday rotation as well as with other ways of studying astrophysical magnetic fields. We test our method in the presence of noise and the resolution effects. We stress the complementary nature of the studies using the SIG technique and those employing the recently introduced velocity gradient techniques that trace magnetic fields using spectroscopic data.

79 ASTRONOMY AND ASTROPHYSICS↗