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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Graphite ionization vacuum gauge

Triode gauge with electron source, electron collector, and positive ion collector made from either graphite or carbon material extends low-pressure ranges of existing gauges by changing only materials used in construction. Advantages of graphite gauge stem from physical properties of graphite (or carbon).

Beitel, G. A.↗
NASA NTRS2017

Flowing Plasma Interaction with an Electric Sail Tether Element

Harnessing the power of the solar wind, an Electric Sail, or E-sail, is a relatively new concept that promises to deliver high speed propellant-less propulsion. The electric sail is an invention made in 2006 at the Kumpula Space Centre in Finland by Pekka Janhunen [Janhunen and Sandroos, 2007]. At its core, an electric sail utilizes multiple positively biased tethers which exchange momentum with solar wind protons via the repelling electric field established around each tether, in other words, by reflecting the solar wind protons. Recognizing the solar wind is a plasma, the effective repelling area of each tether is increased significantly by the formation a plasma sheath around each tether. Fig. 1 shows schematically a spacecraft employing an electric sail. The positive voltage bias (greater than10kV) applied to each tether naturally results in electron collection. Therefore, the electric sail concept necessarily includes an electron source (electron gun) to return collected electrons to space and maintain the positive bias of the tether system.

Schneider, Todd↗
NASA NTRS2010

Carbon nanotube electron gun

An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

Nguyen, Cattien V.↗
NASA NTRS2013

Carbon Nanotube Electron Gun

An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

Nguyen, Cattien V.↗
DOE OSTI2025

Demonstration of closed shell breeding of cesium ions with an electron beam ion source

An electron beam ion source serves as a charge breeder for the Californium Rare Isotope Breeder Upgrade (CARIBU) at the Argonne Tandem Linac Accelerator System (ATLAS). The source accepts radioactive beams of 1+ or 2+ ions and raises their charge state for post-acceleration by ATLAS. The efficiency of this process impacts the length of each experiment and, hence, the type and number of experiments that can be run in each program cycle. Recent efforts to improve the charge breeding efficiency for the 80 < A < 160 species typical of CARIBU have focused on utilizing the closed shell breeding technique. Here, with this technique, the electron beam energy is manipulated to take advantage of the large gap in ionization energies at shell closures and selectively populate a single charge state. Charge breeding studies with stable cesium ions have demonstrated an absolute efficiency of 72% for Cs 27+ and a total efficiency of 93%. The Cs 27+ efficiency result represents a factor of 3 improvement over the previous best charge breeding result of 23% for Cs 27+ .

Vondrasek, R. [Argonne National Laboratory (ANL), ↗
NASA NTRS1999

Prediction and Measurement of X-Ray Spectral and Intensity Distributions from Low Energy Electron Impact Sources

In-vacuum electron beam welding is a technology that NASA considered as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. The radiation exposure to astronauts performing the in-vacuum electron beam welding must be characterized and minimized to insure safe operating conditions. This investigation characterized the x-ray environment due to operation of an in-vacuum electron beam welding tool. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests consisted of Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) and exposed to x-ray radiation generated by operation of an in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 KeV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by electron impact with metal. These x-ray spectra were used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the in-vacuum electron beam welding tool. The calculated absorbed dose values were found to be in good agreement with the TLD values.

Edwards, David L.↗
NASA NTRS1969

Flexible high-voltage supply for experimental electron microscope

Scanning microscope uses a field-emission tip for the electron source, an electron gun that simultaneously accelerates and focuses electrons from the source, and one auxiliary lens to produce a final probe size at the specimen on the order of angstroms.

Chapman, G. L.↗
NASA NTRS2016

Carbon Nanotube Patterning on a Metal Substrate

A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

Nguyen, Cattien V.↗
NASA NTRS1995

Higher-Sensitivity Ionization Trace-Species Detector

Electron source and electron optics of reversal electron-attachment detector modified to increase sensitivity. Original version described in "High-Sensitivity Ionization Trace-Species Detector" (NPO-17596). Used to detect molecules of particular chemical species of interest (e.g., narcotics, explosives, or organic wastes) present in air at low concentrations, and known to attach extremely low-energy electrons. Apparatus does this by ionizing molecules from sampled atmosphere, then detecting ions of species of interest. Detector features indirectly heated spherical cathode and redesigned electron optics, together, deliver more electrons at low kinetic energy to reversal plane, R. Greater electron current generates more ions for detection.

Boumsellek, Said↗
DOE OSTI2024

Optically Stimulated Luminescence Data Storage (Abstract)

We will develop a tunable pulsed electron source capable of generating variable intensity highly-focused electron pulses at high repetition rates. Specifically, we need to demonstrate a high-speed variable electron gun capable of generating a variable intensity electron pulse containing between 102 and 105 electrons with an accelerating voltage of 1kV focused into a spot size <100nm in diameter at with a pulse rate >10MHz (with path to 300MHz). This combined performance cannot be achieved by commercially available electron sources. The primary technology path selected for this work will be to use a photocathode approach, where an easily modulated UV laser is used to stimulate electron emission. The approach utilizes the advances made in the development of the Dynamic TEM (DTEM), though this project will be simpler in that the pulse intensity is lower and there is no requirement for coherency. Alternate paths, including using a traditional electron beam modulated using a v-shaped slit and electrostatically deflecting the beam to adjust intensity; will also be considered for future capabilities. The electron source will then be used generate optically stimulated luminescence (OSL) in lithium fluoride (LiF) substrates to demonstrate the potential for OSL to serve as a basis technology for next generation data storage systems.

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