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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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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.
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.
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.
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.
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.
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.
This study is an on-going research on depositing a Nb film on the internal wall of bulk Nb single cell SRF cavities, via a cathodic arc Nb plasma ions source, an coaxial energetic condensation (CED) facility at AASC company. The motivation is to firstly create a homoepitaxy-like Nb/Nb film in a scale of a ~1.5GHz RF single cell cavity. Next, through SRF measurement and materials analysis, it might reveal the baseline properties of the CED-type homoepitaxy Nb films. Literally, a top-surface layer of Nb films which sustains SRF function, always grows up in homo-epitaxy mode, on top of a Nb nucleation layer. Homo-epitaxy growth of Nb must be the final stage (a crystal thickening process) of any coatings of Nb film on alternative cavity structure materials. Such knowledge of Nb-Nb homo-epitaxy is useful to create future realistic SRF cavity film coatings, such as hetero-epitaxy Nb/Cu Films, or template-layer-mitigated Nb films. One large-grain, and three fine grain bulk Nb cavities were coated. They went through cryogenic RF measurement. Preliminary results show that the Q0 of a Nb film could be as same as the pre-coated bulk Nb surface (which received a chemically-buffered polishing plus a light electro-polishing); but quality factor of two tested cavities dropped quickly. We are investigating if the severe Q-slope is caused by hydrogen incorporation before deposition, or is determined by some structural defects during Nb film growth.
Abstract not provided.
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.
Recently, a filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In this study, numerical modeling of the filament arc-discharge source plasma has been done with kinetic modeling of electrons in the ion source plasmas by the multi-cusp arc-discharge code and zero dimensional rate equations for hydrogen molecules and negative ions. In this paper, main focus is placed on the effects of the arc-discharge power on the electron energy distribution function and the resultant H{sup −} production. The modelling results reasonably explains the dependence of the H{sup −} extraction current on the arc-discharge power in the experiments.
Optical emission spectroscopy has been for long proposed for monitoring and studying industrial steel making processes. Whereas the radiative decay of thermal excitations is always taking place in high temperatures needed in steel production, one of the most promising environment for such studies are electric arc furnaces, creating plasma in excited electronic states that relax with intense characteristic emission in the optical regime. Unfortunately, large industrial scale electric arc furnaces also present a challenging environment for optical emission studies and application of the method is not straightforward. To study the usability of optical emission spectroscopy in real electric arc furnaces, we have developed a laboratory scale DC electric arc furnace presented in this paper. With the setup, optical emission spectra of Fe, Cr, Cr{sub 2}O{sub 3}, Ni, SiO{sub 2}, Al{sub 2}O{sub 3}, CaO, and MgO were recorded in the wavelength range 250-600 nm and the results were analyzed with the help of reference data. The work demonstrates that using characteristic optical emission, obtaining in situ chemical information from oscillating plasma of electric arc furnaces is indeed possible. In spite of complications, the method could possibly be applied to industrial scale steel making process in order to improve its efficiency.
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.
Freezing point in an expanding plasma flow of an arc-jet engine
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.
Methods and apparatus for producing chemical nanostructures having multiple elements, such as boron and nitride, e.g. boron nitride nanotubes, are disclosed. The method comprises creating a plasma jet, or plume, such as by an arc discharge. The plasma plume is elongated and has a temperature gradient along its length. It extends along its length into a port connector area having ports for introduction of feed materials. The feed materials include the multiple elements, which are introduced separately as fluids or powders at multiple ports along the length of the plasma plume, said ports entering the plasma plume at different temperatures. The method further comprises modifying a temperature at a distal portion of or immediately downstream of said plasma plume; and collecting said chemical nanostructures after said modifying.
Methods and apparatus for producing chemical nanostructures having multiple elements, such as boron and nitride, e.g. boron nitride nanotubes, are disclosed. The method comprises creating a plasma jet, or plume, such as by an arc discharge. The plasma plume is elongated and has a temperature gradient along its length. It extends along its length into a port connector area having ports for introduction of feed materials. The feed materials include the multiple elements, which are introduced separately as fluids or powders at multiple ports along the length of the plasma plume, said ports entering the plasma plume at different temperatures. The method further comprises modifying a temperature at a distal portion of or immediately downstream of said plasma plume; and collecting said chemical nanostructures after said modifying.
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.
Observations of a transpolar arc and simultaneous measurements of associated plasmas in the magnetotail lobe on March 25, 1982, are presented. The auroral imager on board Dynamics Explorer 1 observes a theta aurora in the northern polar cap for more than two hours, between 0502 and 0720 UT. ISEE 1 is located in the southern lobe of the geomagnetic tail at a distance of 22.2 R(E) during this time. The plasma and particle detectors measure intermittent bursts of particle fluxes between 0530 and 0705 UT. The observations suggest that these particle fluxes represent the high-altitude signature of a theta aurora in the southern polar cap. The relatively dense and energetic plasmas are organized into several filamentary structures. Magnetic mapping between the two polar regions indicates that the theta aurora in the Southern Hemisphere is a mirror reflection about the noon-midnight meridional plane of the theta aurora in the Northern Hemisphere.