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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Electron Distribution Functions in the Diffusion Region of Asymmetric Magnetic Reconnection

We study electron distribution functions in a diffusion region of antiparallel asymmetric reconnection by means of particle-in-cell simulations and analytical theory. At the electron stagnation point, the electron distribution comprises a crescent-shaped population and a core component. The crescent-shaped distribution is due to electrons coming from the magnetosheath toward the stagnation point and accelerated mainly by electric field normal to the current sheet. Only a part of magnetosheath electrons can reach the stagnation point and form the crescent-shaped distribution that has a boundary of a parabolic curve. The penetration length of magnetosheath electrons into the magnetosphere is derived. We expect that satellite observations can detect crescent-shaped electron distributions during magnetopause reconnection.

Electron↗
NASA NTRS2011

High Voltage EEE Parts for EMA/EHA Applications on Manned Launch Vehicles

The objective of this paper is an assessment of high voltage electronic components required for high horsepower electric thrust vector control (TVC) systems for human spaceflight launch critical application. The scope consists of creating of a database of available Grade 1 electrical, electronic and electromechanical (EEE) parts suited to this application, a qualification path for potential non-Grade 1 EEE parts that could be used in these designs, and pathfinder testing to validate aspects of the proposed qualification plan. Advances in the state of the art in high power electric power systems enable high horsepower electric actuators, such as the electromechnical actuator (EMA) and the electro-hydrostatic actuator (EHA), to be used in launch vehicle TVC systems, dramaticly reducing weight, complexity and operating costs. Designs typically use high voltage insulated gate bipolar transistors (HV-IGBT). However, no Grade 1 HV-IGBT exists and it is unlikely that market factors alone will produce such high quality parts. Furthermore, the perception of risk, the lack of qualification methodoloy, the absence of manned space flight heritage and other barriers impede the adoption of commercial grade parts onto the critical path. The method of approach is to identify high voltage electronic component types and key parameters for parts currently used in high horsepower EMA/EHA applications, to search for higher quality substitutes and custom manufacturers, to create a database for these parts, and then to explore ways to qualify these parts for use in human spaceflight launch critical application, including grossly derating and possibly treating hybrid parts as modules. This effort is ongoing, but results thus far include identification of over 60 HV-IGBT from four manufacturers, including some with a high reliability process flow. Voltage ranges for HV-IGBT have been identified, as has screening tests used to characterize HV-IGBT. BSI BS ISO 21350 Space systems Off-the-shelf item utilization, developed from Marshall Work Instruction MWI8060.1 OFF-THE-SHELF HARDWARE UTILIZATION IN FLIGHT HARDWARE DEVELOPMENTwas found to provide guidance for including commercial off-the-shelf (COTS) hardware for use in critical applications.

Griffin, Trent↗
NASA NTRS1971

Failure-rate computations based on Mariner Mars 1969 spacecraft data

An analysis of in-flight spacecraft part hours and failure data from the Mariner Mars 1969 Project is given. It contains failure rates computed from this data for all electronic and electromagnetic parts on the Mariners 6 and 7 spacecraft. Also included are failure rates based on combining flight data from Mariners 4,5,6, and 7.

Chelson, P. O.↗
DOE OSTI2024

The Design of B1APF Dipole for the EIC

Brookhaven National Laboratory has been chosen to host the Electron-Ion Collider (EIC). Part of this is to install an additional electron ring to the existing RHIC tunnel. The electron hadron Interaction Region (IR) will host nine superconducting magnets on the forward side and six superconducting magnets on the rear side of the Interaction Point (IP). B1APF dipole is the last magnet of the near IR in the outgoing hadron direction. Further, the magnet has a physical aperture of 370 mm diameter and is 1.5 m long. This large aspect ratio makes this magnet particularly challenging. It is a collared magnet and uses a NbTi Rutherford cable with 15.1 mm X 1.9 mm. It is expected to operate at a maximum current of 13400 A at 2 K. The required integrated dipole field is 4.05 Tm. This paper discusses the current design status of the B1ApF dipole and presents the electromagnetic analysis and thermal quench propagation analysis.

43 PARTICLE ACCELERATORS↗
NASA NTRS1973

Energetic particles as a source of flare energy

The production of solar flares by the reservoir of energy generated by sunspot magnetic fields is discussed. Electrons play an important part in the flare process since high energy electrons are responsible for X-ray and radio emission. The energy required in the form of protons trapped in sunspot magnetic fields to produce large solar flares is analyzed. A trigger mechanism is described where the particles can be rapidly dumped into the chromosphere when fast electrons are produced by Coulomb collisions and through pion production by the highest energy protons.

Elliot, H.↗
NASA NTRS1978

Electron temperatures in the F region of the ionosphere - Theory and observations

The theory and observations relating to electron temperatures in the F region of the ionosphere are reviewed. The review is divided into three basic parts. In the first part the theory concerning electron heating, cooling, and energy transport processes is reviewed, and all the relevant expressions are updated. In the second part the behavior of F region electron temperatures, as measured by satellites, rockets, and incoherent scatter radars, is discussed. This portion covers electron temperature variations with altitude, latitude, local time, season, geomagnetic activity, and solar cycle. The third part is primarily devoted to a discussion of the various attempts to compare measured and calculated F region electron temperatures.

Schunk, R. W.↗
DOE OSTI2020

Electron-induced massive dynamics of magnetic domain walls

We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire, focusing on inertial effects on the DW due to interaction with a conduction electron bath. In this work, we develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived microscopically, including the full response kernel which is nonlocal in time. The DW dynamics is described by two collective degrees of freedom: position and tilt angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). The DW response kernel due to electrons contains two parts: one related to dissipation via FDT and another reactive part. We prove that the latter term leads to a mass for both degrees of freedom, even though the intrinsic bare mass is zero. The electron-induced mass is present even in a clean system without pinning or specifically engineered potentials. The resulting equations of motion contain rich dynamical solutions and point toward a way to control domain wall motion in metals via the electronic system properties. We discuss two observable consequences of the mass, hysteresis in the DW dynamics, and resonant response to ac current.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Electronic spectra with paramagnon fractionalization in the single-band Hubbard model

We examine spectral properties of a recently proposed theory of the intermediate temperature pseudogap metal phase of the cuprates. We show that this theory can be obtained from the familiar paramagnon theory of nearly antiferromagnetic metals by fractionalizing the paramagnon into two “hidden” layers of S = 1 / 2 spins. The first hidden layer of spins hybridizes with the electrons as in a Kondo lattice heavy Fermi liquid, whereas the second hidden layer of spins forms a spin liquid with fractionalized spinon excitations. Here, we compute the imaginary part of the electronic self-energy induced by the spinon excitations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Heterobilayers of 2D materials as a platform for excitonic superfluidity

Excitonic condensate has been long-sought within bulk indirect-gap semiconductors, quantum wells, and 2D material layers, all tried as carrying media. Here, we propose intrinsically stable 2D semiconductor heterostructures with doubly-indirect overlapping bands as optimal platforms for excitonic condensation. After screening hundreds of 2D materials, we identify candidates where spontaneous excitonic condensation mediated by purely electronic interaction should occur, and hetero-pairs Sb 2 Te 2 Se/BiTeCl, Hf 2 N 2 I 2 /Zr 2 N 2 Cl 2 , and LiAlTe 2 /BiTeI emerge promising. Unlike monolayers, where excitonic condensation is hampered by Peierls instability, or other bilayers, where doping by applied voltage is required, rendering them essentially non-equilibrium systems, the chemically-specific heterostructures predicted here are lattice-matched, show no detrimental electronic instability, and display broken type-III gap, thus offering optimal carrier density without any gate voltages, in true-equilibrium. Predicted materials can be used to access different parts of electron-hole phase diagram, including BEC-BCS crossover, enabling tantalizing applications in superfluid transport, Josephson-like tunneling, and dissipationless charge counterflow.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Ka-Band Multibeam Aperture Phased Array Being Developed

Phased-array antenna systems offer many advantages to low-Earth-orbiting satellite systems. Their large scan angles and multibeam capabilities allow for vibration-free, rapid beam scanning and graceful degradation operation for high rate downlink of data to users on the ground. Technology advancements continue to reduce the power, weight, and cost of these systems to make phased arrays a competitive alternative in comparison to the gimbled reflector system commonly used in science missions. One effort to reduce the cost of phased arrays is the development of a Ka-band multibeam aperture (MBA) phased array by Boeing Corporation under a contract jointly by the NASA Glenn Research Center and the Office of Naval Research. The objective is to develop and demonstrate a space-qualifiable dual-beam Ka-band (26.5-GHz) phased-array antenna. The goals are to advance the state of the art in Ka-band active phased-array antennas and to develop and demonstrate multibeam transmission technology compatible with spacecraft in low Earth orbit to reduce the cost of future missions by retiring certain development risks. The frequency chosen is suitable for space-to-space and space-to-ground communication links. The phased-array antenna has a radiation pattern designed by combining a set of individual radiating elements, optimized with the type of radiating elements used, their positions in space, and the amplitude and phase of the currents feeding the elements. This arrangement produces a directional radiation pattern that is proportional to the number of individual radiating elements. The arrays of interest here can scan the main beam electronically with a computerized algorithm. The antenna is constructed using electronic components with no mechanical parts, and the steering is performed electronically, without any resulting vibration. The speed of the scanning is limited primarily by the control electronics. The radiation performance degrades gracefully if a portion of the elements fail. The arrays can be constructed to conform to a mounting surface, and multibeam capability is integral to the design. However, there are challenges for mission designers using monolithic-microwave-integrated-circuit- (MMIC-) based arrays because of reduced power efficiency, higher costs, and certain system effects that result in link degradations. The multibeam aperture phased-array antenna development is attempting to address some of these issues, particularly manufacturing, costs, and system performance.

Reinhart, Richard C.↗
NASA NTRS2000

Smallest Nanoelectronic with Atomic Devices with Precise Structures

Since its invention in 1948, the transistor has revolutionized our everyday life - transistor radios and TV's appeared in the early 1960s, personal computers came into widespread use in the mid-1980s, and cellular phones, laptops, and palm-sized organizers dominated the 1990s. The electronics revolution is based upon transistor miniaturization; smaller transistors are faster, and denser circuitry has more functionality. Transistors in current generation chips are 0.25 micron or 250 nanometers in size, and the electronics industry has completed development of 0.18 micron transistors which will enter production within the next few years. Industry researchers are now working to reduce transistor size down to 0.13 micron - a thousandth of the width of a human hair. However, studies indicate that the miniaturization of silicon transistors will soon reach its limit. For further progress in microelectronics, scientists have turned to nanotechnology to advance the science. Rather than continuing to miniaturize transistors to a point where they become unreliable, nanotechnology offers the new approach of building devices on the atomic scale [see sidebar]. One vision for the next generation of miniature electronics is atomic chain electronics, where devices are composed of atoms aligned on top of a substrate surface in a regular pattern. The Atomic Chain Electronics Project (ACEP) - part of the Semiconductor Device Modeling and Nanotechnology group, Integrated Product Team at the NAS Facility has been developing the theory of understanding atomic chain devices, and the author's patent for atomic chain electronics is now pending.

Yamada, Toshishige↗
NASA NTRS2021

Spatially Separated Electron and Proton Beams in a Simulated Solar Coronal Jet

Magnetic reconnection is widely accepted to be a major contributor to non-thermal particle acceleration in the solar atmosphere. In this paper we investigate particle acceleration during the impulsive phase of a coronal jet, which involves bursty reconnection at a magnetic null point. A test-particle approach is employed, using electromagnetic fields from a magnetohydrodynamic simulation of such a jet. Protons and electrons are found to be accelerated non-thermally both downwards toward the domain’s lower boundary and the solar photosphere, and outwards along the axis of the coronal jet and into the heliosphere. A key finding is that a circular ribbon of particle deposition on the photosphere is predicted, with the protons and electrons concentrated in different parts of the ribbon. Furthermore, the outgoing protons and electrons form two spatially separated beams parallel to the axis of the jet, signatures that may be observable inin-situobservations of the heliosphere.

Ross Pallister↗
NASA NTRS1984

Hot Forming With Electron-Beam Welder

Hot forming to restore size and shape of thin metal parts done with electron-beam welder. Work-piece heated in scanning defocused electron beam rather than conventional heat-treating furnace. Technique proved successful in straightening some thin flanges of nickel alloy and titanium.

Dobson, R. K.↗
DOE OSTI2024

Barrier coatings

A secondary electron emissive layer resistant to infiltration and fouling. A barrier layer is formed by atomic layer deposition. The barrier layer may be an emissive layer and/or an interlayer. The barrier layer may form an interlayer that is a part of an electron amplifier positioned between an emissive layer and a resistive layer. The barrier layer is resistive to fluorine migration from either the emissive layer or the resistive layer.

Source record↗
NASA NTRS2015

A NASA First in Nano-Technology: Nano-Electronic Devices in Space

The first active nano-electronic device flown in space was launched on a flight demonstration of a nano-chemical sensor aboard a US Navy satellite in 2007. The same sensor was flown again to the International Space Station (ISS) in 2009 as part of JPL electronic nose for crew cabin air quality monitoring.

Nano-technology↗
NASA NTRS1976

Electron-beam welder alinement

Parts are easily and quickly positioned in welding vacuum chamber with use of inexpensive thin metal-foil plate.

Whiffen, E. L.↗