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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Characterization of the arc in crossflow using a two-temperature nonequilibrium plasma flow model

Diverse industrial applications such as circuit breakers and wire arc spraying involve the interaction between an electric arc and a stream of gas impinging perpendicular to it, a configuration commonly referred to as the arc in crossflow. The arc in crossflow is simulated using a three-dimensional time-dependent two-temperature (heavy-species and electrons) plasma flow model to better capture plasma-gas interactions and deviations from Local Thermodynamic Equilibrium (LTE). The coupled fluid-electromagnetic flow model is solved in a monolithic manner using Variational Multiscale Finite Element Method. Simulation findings are validated with experimental findings and contrasted against results obtained with a LTE model. Results from the two-temperature model corroborate experimental observations while providing quantification of the deviation between heavy-species and electron temperatures. The model is used to characterize the arc in crossflow as a function of the Reynolds and Enthalpy dimensionless numbers, which encapsulate the inter-dependence among the main parameters total current, inflow velocity, and inter-electrode spacing. Furthermore, the characterization revealed the behavior of arc shape, voltage drop, arc power, the degree of nonequilibrium, as well as the characteristic plasma front thickness, with varying controlling parameters.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

A Vacuum-Free Method for Producing Cubic Titanium Carbide in the Plasma of Low-Voltage Direct-Current Arc Discharge

The results of a study on the production of cubic titanium carbide in direct-current arc discharge plasma initiated in open air are presented. A feature of the method is its implementation without the use of gas or liquid protective media preventing the oxidation of products and initial reagents with air oxygen. According to the X-ray diffraction data, graphite gC, hexagonal titanium α-Ti, and cubic titanium carbide TiC are identified in the composition of the powder product. The TiC particles are represented by objects with a regular characteristic cut and sizes from units to tens of micrometers.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Informing ARC divertor design and plasma facing material selection through integrated modeling

This INFUSE 2023 project between UCLA and Commonwealth Fusion Systems used computer modeling to test whether tungsten materials can survive in CFS's ARC fusion reactor divertor. The team simulated plasma conditions and material responses, finding that tungsten-rhenium alloys resist grain growth better than pure tungsten, and that hydrogen buildup depends more on particle flux than temperature. The work helps CFS design durable plasma-facing components for their fusion power plant.

36 MATERIALS SCIENCE↗
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.↗
NASA NTRS2003

Magnetic Dipole Inflation with Cascaded ARC and Applications to Mini-Magnetospheric Plasma Propulsion

Mini-Magnetospheric Plasma Propulsion (M2P2) seeks to create a plasma-inflated magnetic bubble capable of intercepting significant thrust from the solar wind for the purposes of high speed, high efficiency spacecraft propulsion. Previous laboratory experiments into the M2P2 concept have primarily used helicon plasma sources to inflate the dipole magnetic field. The work presented here uses an alternative plasma source, the cascaded arc, in a geometry similar to that used in previous helicon experiments. Time resolved measurements of the equatorial plasma density have been conducted and the results are discussed. The equatorial plasma density transitions from an initially asymmetric configuration early in the shot to a quasisymmetric configuration during plasma production, and then returns to an asymmetric configuration when the source is shut off. The exact reasons for these changes in configuration are unknown, but convection of the loaded flux tube is suspected. The diffusion time was found to be an order of magnitude longer than the Bohm diffusion time for the period of time after the plasma source was shut off. The data collected indicate the plasma has an electron temperature of approximately 11 eV, an order of magnitude hotter than plasmas generated by cascaded arcs operating under different conditions. In addition, indirect evidence suggests that the plasma has a beta of order unity in the source region.

Giersch, L.↗
NASA NTRS1996

Spectroscopic Diagnostics and an Arc Jet Heated Air Plasma

Spectral radiation measurements were made in the range of 200 to 900 nm across a section of the plenum of an arc jet wind tunnel using a series of optical fibers. The spectra contained line radiation from Oxygen and Nitrogen atoms and molecular radiation from N2(+), N2, and NO. Abel inversion technique is used to obtain radial distribution of the spectra. The analysis yielded radial profiles of the electronic excitation, vibrational and rotational temperatures of the flow field. Spectral fitting yielded branching ratios for different vibrational and rotational bands. Relatively mild flow conditions, i.e. enthalpy and mass flow rate, were used for prolonged measurements of up to and over two hours to establish the best experimental methods of temperature determinations. Signal to noise was improved by at least an order of magnitude enabling the molecular vibrational band heads of N2(+) (first negative system), N2 (second positive system), and NO (beta, gamma, delta, and epsilon systems) to be resolved in the lower ultraviolet wavelength regions. The increased signal to noise ratio also enabled partial resolution of the rotational lines of N2(+) and N2 in certain regions of minimal overlap. Comparison of the spectra with theoretical models such as the NEQAIR2 code are presented and show potential for fitting the spectra when reliable calibration is performed for the complete wavelength range.

Mack, Larry Howard, Jr.↗
NASA NTRS1981

Cold plasma boundaries and auroral arcs

Auroral arcs often extend for more than a thousand kilometers with little deviation of their relative position within the auroral oval. At high altitudes, the outer limits of the plasmasphere are usually marked by sharp decreases in the cold plasma densities. It is suggested that some auroral arcs follow the ionospheric trace of these boundary shells.

Mcilwain, C. E.↗
NASA NTRS2018

The Laser Enhanced Arc-Jet Facility (LEAF-Lite): Simulating Convective and Radiative Heating with Arc-Jets and Multiple 50-KW CW Lasers

LEAF-Lite (Laser Enhanced Arc-Jet Facility) is a radiative laser heating facility that has been added to the 60 MW Interaction Heating Facility (IHF) convective plasma arc-jet located at NASA Ames Research Center. Together, these two systems can simulate both convective and radiative heating at heat fluxes reaching 551 W/cm2 by simultaneously combining a highest measured heat flux of 160 W/cm2 convective and 391 W/cm2 radiative heating on a 152-mm x 152-mm wedge model configuration. Adding radiant heating to an existing convective facility better simulates Earth atmospheric entry from hyperbolic lunarreturn speeds. The radiative heat is provided by multiple 50-kW CW IR lasers, which is nearly uniform across the illuminated surface with a total variation less than 6%, while the convective heat is provided by a high enthalpy plasma arc-jet. In a later phase, the facility will expand to test panel test articles of 432-mm x 432-mm and provide 100 W/cm2 of radiative heating in a plasma convective flow environment. The paper describes this new combined heating capability, its current testing conditions, and the unique application of the laser system with respect to the Orion test flight lunar orbits.

Cushman, Geoff↗
NASA NTRS1992

Current flow in a plasma caused by dielectric breakdown

Spacecraft with a thin dielectric coating on the outer surface of the structure which are biased (-200 V) negative relative to the atmospheric plasma are susceptible to dielectric breakdown. This paper will present experimental tests designed to measure the electron current flow from the structure through the plasma during the arc. The current path was examined in three parts: the electrons supplied through the structure and the arc to the outer structure, the expansion of the arc into the ambient plasma, and the return current through the ambient plasma. The measured electron current either flowing from the plasma or supplied to the plasma by the arc in each case was compared to the random thermal electron current which could be collected. The results of the tests show a spacecraft is capable of supporting arcs with peak currents greater than thermal electron currents, and these currents will be dependent upon the amount of stored charge in the structure (i.e., the structure's surface area and dielectric thickness). Also, the results of these tests show that it is possible for structures with a self capacitance of 10 microFarads to see peak currents of 90 A and structures with 1000 microFarads (i.e., capacitance of one Space Station Freedom module) to produce peak currents of 1000 A.

Vaughn, J. A.↗
NASA NTRS1975

Plasma clouds and auroral arcs

Correlation techniques for magnetospheric observations of various types by instrumented spacecraft in synchronous orbit are discussed. Emphasis is placed on ideas for possible use in studies with GEOS satellite during the International Magnetospheric Study, and comparison of auroral and magnetospheric plasma features are considered. Correlation between ATS-5 particle detector measurements with ground based measurement and other spacecraft such as Explorer 45 is described. Observations from ATS-6 instrument are briefly mentioned.

Deforest, S.↗
DOE OSTI2013

Carbides composite surface layers produced by (PTA)

The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Ionospheric flows associated with a transpolar arc

Data on plasma flows associated with a transpolar arc are obtained by combining observations (on January 21, 1982) from the auroral imaging instruments aboard the DE 1 spacecraft with simultaneous observations of ionospheric electron drift velocities obtained with a ground-based coherent radar system and with an ion-drift meter on the DE 2 spacecraft at about 800-km altitude. The combined observations demonstrate that the electron-drift velocities within the transpolar arc at the intersection with the auroral oval on the nightside are directed equatorward into the oval and that the transpolar arc connects to the oval near the Harang discontinuity. It is also shown that the sunward flow along the transpolar arc is present near local noon.

Nielsen, E.↗
DOE OSTI2015

Polarized {sup 3}He{sup −} ion source with hyperfine state selection

High beam polarization is essential to the scientific productivity of a collider. Polarized {sup 3}He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding that achieved today are a key requirement for the development of these next generation high-luminosity high-polarization colliders. The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for realization of a new type of a polarized {sup 3}He{sup −} ion source. This report discusses a polarized {sup 3}He{sup −} ion source based on the large difference of extra-electron auto-detachment lifetimes of the different {sup 3}He{sup −} ion hyperfine states. The highest momentum state of 5/2 has the largest lifetime of τ ∼ 350 µs while the lower momentum states have lifetimes of τ ~ 10 µs. By producing {sup 3}He{sup −} ion beam composed of only the |5/2, ±5/2> hyperfine states and then quenching one of the states by an RF resonant field, {sup 3}He{sup −} beam polarization of 90% can be achieved. Such a method of polarized {sup 3}He{sup −} production has been considered before; however, due to low intensities of the He{sup +} ion sources existing at that time, it was not possible to produce any interesting intensity of polarized {sup 3}He{sup −} ions. The high-brightness arc-discharge ion source developed at BINP can produce a high-brightness {sup 3}He{sup +} beam with an intensity of up to 2 A allowing for selection of up to ∼1-4 mA of {sup 3}He{sup −} ions with ∼90% polarization. The high gas efficiency of an arc-discharge source is important due to the high cost of {sup 3}He gas. Some features of such a PIS as well as prototype designs are considered. An integrated {sup 3}He{sup −} ion source design providing high beam polarization could be prepared using existing BNL equipment with incorporation of new designs of the 1) arc discharge plasma generator, 2) extraction system, 3) charge exchange jet, and 4) magnetic separation system.

43 PARTICLE ACCELERATORS↗