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Results for “ELECTROMAGNETIC RADIATION”

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

Electromagnetic Radiation Effects on MgO-Based Magnetic Tunnel Junctions: A Review

Magnetic tunnel junctions (MTJs) have been widely utilized in sensitive sensors, magnetic memory, and logic gates due to their tunneling magnetoresistance. Moreover, these MTJ devices have promising potential for renewable energy generation and storage. Compared with Si-based devices, MTJs are more tolerant to electromagnetic radiation. In this review, we summarize the functionalities of MgO-based MTJ devices under different electromagnetic irradiation environments, with a focus on gamma-ray radiation. We explore the effects of these radiation exposures on the MgO tunnel barriers, magnetic layers, and interfaces to understand the origin of their tolerance. This review enhances our knowledge of the radiation tolerance of MgO-based MTJs, improves the design of these MgO-based MTJ devices with better tolerances, and provides information to minimize the risks of irradiation under various irradiation environments. This review starts with an introduction to MTJs and irradiation backgrounds, followed by the fundamental properties of MTJ materials, such as the MgO barrier and magnetic layers. Then, we review and discuss the MTJ materials and devices’ radiation tolerances under different irradiation environments, including high-energy cosmic radiation, gamma-ray radiation, and lower-energy electromagnetic radiation (X-ray, UV–vis, infrared, microwave, and radiofrequency electromagnetic radiation). In conclusion, we summarize the radiation effects based on the published literature, which might benefit material design and protection.

42 ENGINEERING↗
DOE OSTI2018

Wide-Aperture Aspheric Optics for Formation of Subwavelength Caustics of a Terahertz Electromagnetic-Radiation Beam

A wide-aperture aspheric lens for focusing a terahertz electromagnetic-radiation beam in a circle of the subwavelength size is proposed. The calculation of the lens and the estimation of size of created caustic were carried out using computational methods of geometric optics and electrodynamics. The lens is made of high-density polyethylene with the help of a turning machine. For experimental estimation of the spatial resolution provided by the lens, a THz imaging system based on raster scanning of the object’s surface was created. The imaging system was used in combination with wide-aperture THz optics to record images of the streak plates with different spatial frequencies. Analysis of the experimental data showed that the aspheric lens allows the resolution of two objects spaced at a distance of 0.95λ, providing contrast of 15%. The proposed THz optics is superior to classical THz spherical lenses and off-axis parabolic mirrors, greatly expanding the capabilities of THz-spectroscopy methods and imaging.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1983

Apparatus for processing electromagnetic radiation and method

Measuring apparatus including a ruled member having alternate transparent and opaque zones. An optical coupler connecting the ruled member with electromagnetic radiation-conversion apparatus. The conversion apparatus may include a photomultiplier and a discriminator. Radiation impinging on the ruled member will, in part, be converted to electrical pulses which correspond to the intensity of the radiation. A method of processing electromagnetic radiation includes providing a member having alternating dark and light zones, establishing movement of the member through the beam of electromagnetic radiation with the dark zones interrupting passage of radiation through the rule, providing an optical coupler to connect a portion of the radiation with a conversion station where the radiation portion is converted into an electrical pulse which is related to the intensity of the radiation received at the conversion station. The electrical pulses may be counted and the digitized signals stored or permanently recorded to produce positional information.

Gatewood, George D.↗
NASA NTRS1983

Electromagnetic radiation from beam-plasma instabilities

A computer simulation is developed for the generation of electromagnetic radiation in an electron beam-plasma interaction. The plasma is treated as a two-dimensional finite system, and effects of a continuous nonrelativistic beam input are accounted for. Three momentum and three field components are included in the simulation, and an external magnetic field is excluded. EM radiation generation is possible through interaction among Langmuir oscillations, ion-acoustic waves, and the electromagnetic wave, producing radiation perpendicular to the beam. The radiation is located near the plasma frequency, and polarized with the E component parallel to the beam. The scattering of Langmuir waves caused by ion-acoustic fluctuations generates the radiation. Comparison with laboratory data for the three-wave interactions shows good agreement in terms of the radiation levels produced, which are small relative to the plasma thermal energy.

Pritchett, P. L.↗
DOE OSTI2022

Bound states and electromagnetic radiation of relativistically rotating cylindrical wells

Here, we compute the effect of rigid rotation on the non-relativistic bound states. The energy levels of the bound states increase with the angular velocity of rotation until at certain value of the angular velocity they are completely pushed out into the continuum which corresponds to dissociation of the bound states. When the angular velocity exceeds the critical value at which the ground state disappears into the continuum, no bound state is possible. This effect should have important consequences for the phenomenology of the quark-gluon plasma. One of the ways to study it experimentally is to observe the electromagnetic radiation emitted by a rotating bound state. We compute the corresponding intensity of electromagnetic radiation and show that it strongly depends on the angular velocity of rotation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Causal fermion states in magnetic field in a relativistic rotating frame and electromagnetic radiation by a rapidly rotating charge

We consider the Dirac field uniformly rotating with angular velocity Ω and also subject to the constant magnetic field B directed along the rotation axis. The causal states are constrained to the interior of the light cylinder of radius c / Ω . When this radius is smaller than the system size, as in the quark-gluon plasma, the effect of the boundary on the fermion spectrum is critical. We derive the fermion spectrum and study its properties. We compute the intensity of the electromagnetic radiation emitted due to transitions between the fermion states. We study its dependence on energy and angular momentum for different values of the angular velocity and the magnetic field. Rotation has enormous impact on the electromagnetic radiation by the quark-gluon plasma with or without the magnetic field. Published by the American Physical Society 2024

Buzzegoli, Matteo (ORCID:0000000221145431)↗
NASA NTRS1972

Conical electromagnetic radiation flux concentrator

Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

Miller, E. R.↗
NASA NTRS1978

Localization of non-stationary sources of electromagnetic radiation with the aid of phasometry

The possibility of localizing sources of electromagnetic radiation by measurement of the time of passage of the radiation or the measurement of its phase at various points of cosmic space, at which are located satellite observatories is examined. Algorithms are proposed for localization using two, three, and four astronomical observatories. The precision of the localization and several partial results of practical significance are deduced.

Mersov, G. A.↗
NASA NTRS1996

Electromagnetic radiation generated by arcing in low density plasma

An unavoidable step in the process of space exploration is to use high-power, very large spacecraft launched into Earth orbit. Obviously, the spacecraft will need powerful energy sources. Previous experience has shown that electrical discharges occur on the surfaces of a high-voltage array, and these discharges (arcs) are undesirable in many respects. Moreover, any high voltage conductor will interact with the surrounding plasma, and that interaction may result in electrical discharges between the conductor and plasma (or between two conductors with different potentials, for example, during docking and extravehicular activity). One very important aspect is the generation of electromagnetic radiation by arcing. To prevent the negative influence of electromagnetic noise on the operation of spacecraft systems, it seems necessary to determine the spectra and absolute levels of the radiation, and to determine limitations on the solar array bias voltage that depend on the parameters of LEO plasma and the technical requirements of the spacecraft equipment. This report describes the results of an experimental study and computer simulation of the electromagnetic radiation generated by arcing on spacecraft surfaces. A large set of high quality data was obtained during the Solar Array Module Plasma Interaction Experiment (SAMPIE, flight STS-62) and ground test. These data include the amplitudes of current, pulse forms, duration of each arc, and spectra of plasma waves. A theoretical explanation of the observed features is presented in this report too. The elaborated model allows us to determine the parameters of the electromagnetic noise for different frequency ranges, distances from the arcing site, and distinct kinds of plasma waves.

Vayner, Boris V.↗
DOE OSTI2025

A curvature-based mechanism for the spontaneous emission of electromagnetic radiation at curved plasma–vacuum interfaces

In this work, we derive from first principles the dispersion relation for electromagnetic radiation that is spontaneously emitted at a 2D curved plasma–vacuum interface in the absence of both background and external electric and magnetic fields. This plasma geometry is motivated by plasmas generated through hypervelocity impact projectiles—an area that is of importance to satellite safety in the aerospace community, and may be of importance for the developing study of projectile impact-driven inertial confinement fusion. We find spontaneous radiation occurs when thermal surface waves propagate along the edge of a circular plasma, with a frequency lower than the plasma frequency and spatial decay proportional to 1/r. This is distinct from more well-known mechanisms of radiation, in which the radiation frequency is greater than or equal to the plasma frequency. This theory is validated against 2D, electromagnetic particle-in-cell simulations and shows reasonable agreement. Finally, we discuss the effects of plasma geometry and attribute the radiation generation mechanism to the acceleration of charged surface waves as they traverse azimuthally along a curved path.

Lau, Raymond (ORCID:0000000299318101)↗
NASA NTRS1984

Experimental observations of nonlinearly enhanced 2omega-UH electromagnetic radiation excited by steady-state colliding electron beams

Counterstreaming large-diameter electron beams in a steady-state laboratory experiment are observed to generate transverse radiation at twice the upper-hybrid frequency (2omega-UH) with a quadrupole radiation pattern. The electromagnetic wave power density is nonlinearly enhanced over the power density obtained from a single beam-plasma system. Electromagnetic power density scales exponentially with beam energy and increases with ion mass. Weak turbulence theory can predict similar (but weaker) beam energy scaling but not the high power density, or the predominance of the 2omega-UH radiation peak over the omega-UH peak. Significant noise near the upper-hybrid and ion plasma frequencies is also measured, with normalized electrostatic wave energy density W(ES)/n(e)T(e) approximately 0.01.

Intrator, T.↗