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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Artificial meteor ablation studies

Artificial meteor ablation was performed on natural minerals, composed predominately of magnetite and hematite, using an arc heated plasma stream of air. Analysis of the ablated debris indicated most was composed of two or more minerals. The more volatile elements were depleted and the relative abundance of Fe increased as a result of both volatile depletion and a reduction in its oxidation state. Hematite was converted to magnetite in the ablation zone, and quartz and apatite minerals were converted to an Fe-rich glass consisting of varying amounts of Si, P, Cl, and Ca, depending upon the accessory minerals available at the time of melting. Artificially created ablation products from iron oxides exhibited unique properties depending on the composition of the original material and the environmental conditions of formation. In addition to the accepted elemental criteria, these properties were morphologic characteristics, textural parameters, and the existence of metastable minerals.

Blanchard, M. B.↗
NASA NTRS1974

Artificial meteor ablation studies - Olivine

Artificial meteor ablation has been performed on a Mg-rich olivine sample by means of an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine was 98% olivine (including traces of olivine alteration products) and 2% chromite. The forsterite content of the original olivine was Fo 89 and increased to Fo 94 in the recrystallized olivine after ablation. In addition, lamella-like intergrowths of magnetite were prevalent. Wherever magnetite occurred, Mg increased and Fe decreased in the recrystallized olivine. The Fe for the magnetite exsolved from the original olivine crystals. Individual particles (i.e., spherules) were also characterized by magnetite intergrowths. Fusion crusts on the Allende and Murchison meteorites were compared with the fusion crust on the olivine sample. The Allende fusion crust consisted of a recrystallized olivine, richer in Mg and deficient in Fe in comparison with the original meteorite's olivine, and abundant magnetite grains.

Blanchard, M. B.↗
NASA NTRS1975

The ERDA thermionic program

A rationale for increased Federal support of thermionic research is considered and the objectives and milestones of the thermionic program of the U.S. Energy Research and Development Administration (ERDA) are examined. The ERDA program is to provide very high specific power systems needed for planned future NASA nuclear electric propulsion missions. Another objective is the enhancement of the overall thermal conversion efficiency of the present utility power plants from approximately 35% to 50% or more. Attention is given to key problem areas, taking into account inadequate analytical tools, the reduction of the plasma arc-drop losses, aspects of hot shell materials development, and the coordination of the participating groups programmatic activities.

Newby, G. A.↗
NASA NTRS1977

Analysis of ablation debris from natural and artificial iron meteorites

Artificial ablation studies were performed on iron and nickel-iron samples using an arc-heated plasma of ionized air. Experiment conditions simulated a meteoroid traveling about 12 km/sec at an altitude of 70 km. The artificially produced fusion crusts and ablation debris show features very similar to natural fusion crusts of the iron meteorites Boguslavka, Norfork, and N'Kandhla and to magnetic spherules recovered from Mn nodules. X-ray diffraction, electron microprobe, optical, and scanning electron microscope analyses reveal that important mineralogical, elemental, and textural changes occur during ablation. Some metal is melted and ablated. The outer margin of the melted rind is oxidized and recrystallizes as a discontinuous crust of magnetite and wustite. Adjacent to the oxidized metallic ablation zone is an unoxidized metallic ablation zone in which structures such as Widmannstatten bands are obliterated as the metal is transformed to unequilibrated alpha 2 nickel-iron. Volatile elements are vaporized and less volatile elements undergo fractionation.

Blanchard, M. B.↗
NASA NTRS1976

A high-voltage-isolated automated data acquisition system

A data acquisition system for electric-arc heated, high-temperature wind tunnel facilities has been developed; the high voltage isolation of the system exceeds 50 kV. A closed loop, optically coupled data system acquires transducer signals from high-temperature, arc-generated plasmas used for reentry testing. The data acquisition system monitors on-line tests, stores data on magnetic tape, and prints out a paper tape. The system has 400 data channels: 200 low-voltage programmable channels and 200 high-voltage sequential channels.

Cox, J.↗
NASA NTRS1978

Analysis of ablation debris from natural and artificial iron meteorites

Iron and nickel-iron samples subjected to treatment by an arc-heated plasma of ionized air were used to model meteor ablation. The artificial ablation debris and fusion crusts were compared to the fusion crusts of three natural iron meteorities and to magnetic spherules from deep-sea manganese nodules. An outer discontinuous crust of magnetite and wuestite, followed by an unoxidized metallic zone, was observed in the artificially produced samples. Fractionation of less volatile elements was also noted.

Blanchard, M. B.↗
NASA NTRS1986

Improved piston ring materials for 650 deg C service

A program to develop piston ring material systems which will operate at 650C was performed. In this program, two candidate high temperature piston ring substrate materials, Carpenter 709-2 and 440B, were hot formed into the piston ring shape and subsequently evaluated. In a parallel development effort ceramic and metallic piston ring coating materials were applied to cast iron rings by various processing techniques and then subjected to thermal shock and wear evaluation. Finally, promising candidate coatings were applied to the most thermally stable hot formed substrate. The results of evaluation tests of the hot formed substrate show that Carpenter 709-2 has greater thermal stability than 440B. Of the candidate coatings, plasma transferred arc (PTA) applied tungsten carbide and molybdenum based systems exhibit the greatest resistance to thermal shock. For the ceramic based systems, thermal shock resistance was improved by bond coat grading. Wear testing was conducted to 650C (1202F). For ceramic systems, the alumina/titania/zirconia/yttria composition showed highest wear resistance. For the PTA applied systems, the tungsten carbide based system showed highest wear resistance.

Bjorndahl, W. D.↗
NASA NTRS1989

Shutter For VPPA-Welding Vision System

Conceptual electro-optical shutter subsystem regulates intensity of light entering video camera from variable-plasma-pulse-arc weld in process. Camera part of video system that enables welding technician to obtain better view of weld bead and puddle in light of arc. Electro-optical shutter opened during low-illumination viewing intervals near zero crossings of welding current, preventing overloading of video camera.

Lirette, Murray J.↗
NASA NTRS1994

Analysis of the Shuttle Orbiter reinforced carbon-carbon oxidation protection system

Reusable, oxidation-protected reinforced carbon-carbon (RCC) has been successfully flown on all Shuttle Orbiter flights. Thermal testing of the silicon carbide-coated RCC to determine its oxidation characteristics has been performed in convective (plasma Arc-Jet) heating facilities. Surface sealant mass loss was characterized as a function of temperature and pressure. High-temperature testing was performed to develop coating recession correlations for predicting performance at the over-temperature flight conditions associated with abort trajectories. Methods for using these test data to establish multi-mission re-use (i.e., mission life) and single mission limits are presented.

Williams, S. D.↗
NASA NTRS1999

MPTA Overview

Presentation discusses Micro Plasma Transfer Arc (MPTA) welding. It was introduced in 1960, and has been used for blade refurbishment for jet engines since 1980. It is compared with Gas Tungsten Arc Welding. MPTA welding reduces the heat input to perform the weld. It uses controlled filler material, and it is easy to use.

Weeks, Jack↗
NASA NTRS1994

Ultra-High Temperature Ceramics

Recent developments in ultra-high temperature ceramic composites, and their application to advanced vehicle thermal protection systems will be discussed. Research and testing of refractory ceramics has resulted in the identification of a new family of ceramic composites that promise temperature performance to 4000 F+, significantly beyond the current state-of-the-art of reusable systems which are limited to approximately 300 F. This new family of materials includes zirconium and hafnium diboride composites with various reinforcements, such as fibers and particulates. Preliminary material characterization and testing results, including plasma arc-jet testing of prototype vehicle components, will be described. Future directions for the research and material development activities will also be discussed.

Rasky, Dan↗
NASA NTRS1997

Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

Nonliner Plasma waves↗
NASA NTRSDate not supplied

Active Region Simulation with EBTEL

Active regions (ARs) are areas in the sun’s upper atmosphere that are bright in the extreme ultraviolet (EUV) and X-ray spectrum. Coronal loops are one key feature of an AR. They can be described as arcs of plasma resulting from loop-shaped magnetic fields on the sun. The average temperature of these loops is over one million kelvin, which is significantly hotter than the sun’s surface. The mechanism for the heat transfer of these high temperatures remains unknown and is referred to as the coronal heating problem. One leading hypothesis regarding this mystery is that small, impulsive heating events called nanoflares are a major contributor. Here, we explore the contribution of nanoflares in the heating of AR plasma. We utilize the Enthalpy-Based Thermal Evolution of Loops (EBTEL) program to simulate NOAA 12846, as observed on July 25, 2021. We then use that simulation to analyze how the frequency of nanoflare heating events affects the EUV and X-ray observations in existing instruments, including SDO’s AIA and Hinode’s XRT. We also predict how this AR would appear in recently developed X-ray instruments, such as NASA’s MaGIXS.

Active region↗
NASA NTRS1985

Plasma irregularities associated with a morning discrete auroral arc - Radar interferometer observations and theory

A description is given of E region auroral plasma irregularities associated with an intense auroral morning arc observed over Fort Churchill by radar. The observations are compared with data from an all-sky camera (ASC) operated at Fort Churchill by the National Research Council of Canada. The particular event described was chosen because of the rapid variation in structure and motion of the arc as it traveled through the radar beam. The horizontal vector electron drift velocity and electric field along the poleward boundary of the morning discrete auroral arc was successfully measured with a radar interferometer. This instrument provided information concerning the temporal and spatial structure of the electrostatic plasma turbulence in the arc. The observations are described.

Providakes, J.↗
NASA NTRS2018

Evidence for Arcing on the International Space Station Solar Arrays

The International Space Station (ISS) is powered by a set of 160 V photovoltaic arrays (PVA) in the US sector. Arcing thresholds for the ISS PVAs measured in the laboratory are shown to vary from -210 V to -457 V depending on the ambient plasma density, where low arcing threshold occurs at high plasma densities. Arcing of ISS PVAs on-orbit is unlikely under normal operating conditions. The net potential of a solar cell relative to space depends on the position of the cell within a string, the (vxB)•L contribution to the potential at the location of the cell, and the frame potential of ISS due to solar array charging. Net potentials on a cell will reach the arcing threshold only on rare occasions. However, the situation changes when damaged PVA strings are considered. Open circuit strings can exhibit voltages exceeding -300 V when the strings are shunted. Under these conditions the local potential on the damaged string can easily exceed arcing thresholds at the low end of the -210 V to -457 V range for ISS PVAs. Because arcing to space on the array will remove some fraction of the net negative charge on the ISS, transient variations in the frame potential are expected during the electrostatic discharge events. We report a new class of transient ISS frame potential variations consistent with arcing on open strings using data from the ISS Floating Potential Measurement Unit’s Floating Potential Probe instrument.

Minow, Joseph I.↗
NASA NTRS1980

Comparative rocket observations of ionospheric electric fields in the auroral oval

The ion drift technique of measuring ionospheric electric fields is compared to two other simultaneous measurements. Rocket measurements in the evening auroral oval are checked against a dual probe, also in situ, and the ground based STARE auroral radar. The technique is explained thoroughly as well as tested for its dependence on mass. Two evening auroral oval conditions were observed from Andoya, Norway in January and February 1977. The first flight, 18:1005, measured electric fields over a quiet pre-midnight discrete arc. An interesting plasma convection reversal was observed poleward of the arc. The subsequent 18:1004, samples a breakup phase aurora nearer local midnight.

Zanetti, L. J., Jr.↗
DOE OSTI2026

Elucidating key reducing species beyond ions in hydrogen plasma smelting reduction of iron ore

Hydrogen plasma smelting reduction (HPSR) of iron ore has attracted significant attention over the past decade due to its high-temperature operation, rapid plasma mediated reduction kinetics, and simpler density-based separation of molten iron product, compared to H2-based solid-state reduction. All of these attributes enable processing of low-grade ores for downstream use in electric-arc furnaces, as virgin iron with low gangue content is required for high quality steel and improved furnace operation. While positive ions exist within the plasma arc, this work demonstrates that near the anodic ore surface, hydrogen radicals and vibrationally excited hydrogen species dominate and their densities correlate well with observed reduction rates. Species concentrations in the transferred plasma arc and at the plasma-ore interface are evaluated using coupled thermal plasma and near-wall non-equilibrium plasma models. The thermal plasma model is validated against experimental voltage data and spectroscopic measurements of plasma temperature and density for varying current inputs. Modeling of the near surface thermochemical non-equilibrium and micrometer scale anode sheath layer reveals, in addition to the expected H + , significant concentrations of ArH + and H$^+_3$ ions, typically not observed in thermal plasmas under thermodynamic equilibrium. Our results show that the inverted sheath structure at the anodic ore surface strongly suppresses reactive positive ion fluxes, while non-equilibrium electron-impact processes generate abundant hydrogen radicals and vibrationally excited species. These findings highlight the critical role of non-equilibrium effects in hydrogen arc-driven iron ore reduction and advance understanding beyond prevailing hypotheses centered on hydrogen ion-driven mechanisms.

08 HYDROGEN↗