Investigations of electron interactions with matter. Part 1 - Bremsstrahlung production in aluminum and iron. Part 2 - Electron scattering in aluminum
Bremsstrahlung production in aluminum and iron - electron scattering in aluminum
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Bremsstrahlung production in aluminum and iron - electron scattering in aluminum
Electron microscopy and optical techniques for biological Mars studies
Electron beams from duoplasmatron using hollow cathode arc, noting current density distributions
Langmuir and current probe measurements of ion thrustor beam, and resulting transverse and longitudinal profiles of electron and ion densities
Ionosphere electron density determined by signal measurements from Elektron I and III SATELLITES
Return of high energy splash albedo electrons to earth investigated under limitations of Stormer theory
The NEPP Program focuses on the reliability aspects of electronic devices (integrated circuits such as a processor in a computer). There are three principal aspects of this reliability: 1) Lifetime, inherent failure and design issues related to the EEE parts technology and packaging; 2) Effects of space radiation and the space environment on these technologies, and; 3) Creation and maintenance of the assurance support infrastructure required for mission success. The NEPP mission is to provide guidance to NASA for the selection and application of microelectronics technologies, to improve understanding of the risks related to the use of these technologies in the space environment, and to ensure that appropriate EEE parts research is performed to meet NASA mission assurance needs. NEPPs FY15 goals are to represent the NASA voice to the greater aerospace EEE parts community including supporting anti-counterfeit and trust, provide relevant guidance to cost-effective missions, aid insertion of advanced (and commercial) technologies, resolve unexpected parts issues, ensure access to appropriate radiation test facilities, and collaborate as widely as possible with external entities. In accordance with the changing mission profiles throughout NASA, the NEPP Program has developed a balanced portfolio of efforts to provide agency-wide assurance for not only traditional spacecraft developments, but also those in-line with the new philosophies emerging worldwide. In this presentation, we shall present an overview of this program and considerations for EEE parts assurance as applied to cost conscious missions.
This presentation includes NASA Electronic Parts and Packaging (NEPP) Program FY18 overview, key efforts, concerns, and current status.
Understanding the evolution of dislocation structures during plastic deformation is critical for predicting the mechanical performance of metallic materials. In this work, we applied in situ scanning electron microscopy/electron backscatter diffraction tensile testing combined with multifractal (MF) analysis to assess deformation-induced dislocation structure evolution in solution-annealed 304 L stainless steel, both in its as-received and neutron-irradiated states (5.4 displacements per atom). The analysis of kernel average misorientation patterns revealed the formation of hierarchical dislocation arrangements that exhibit clear MF scaling behavior. Despite pronounced visual differences between nonirradiated and irradiated specimens—most notably, the appearance of dislocation channels after irradiation—the singularity spectra suggest that both conditions give rise to similar underlying hierarchical structures. MF analysis provides a quantitative measure of the spatial complexity and self-organization of dislocation patterns, highlighting the accelerated emergence and evolution of the dislocation structures in irradiated polycrystalline materials, as well as the limitation of their spatial extent. The findings indicate that irradiation not only modifies microstructure but also alters correlation-driven dislocation organization. More generally, they demonstrate that MF analysis is a powerful tool for probing mesoscale deformation mechanisms.
There is broad interest in layered, two-dimensional (2D) semiconductors owing to their high optical absorption and ability to heterogeneously integrate with various substrates. In such layered semiconductors, mesoscopic imperfections, such as surface step edges, may affect charge carrier kinetics and device performance, but studying their effects on carrier transport with sufficient spatial and temporal resolution is a challenge. Using scanning ultrafast electron microscopy, we image the near-surface charge carrier kinetics with μm/ps spatiotemporal resolution in single-crystal MoS 2 samples with surface steps tens of nanometers in height. We find an approximately 3-fold increase in surface trap density near such surface steps compared to the uniform, flat surface regions. Despite the difference in trap state density, filling of the traps occurs over the same time scale (∼100 ps), but carrier recovery is much slower near the step compared to the uniform regions of the material. Furthermore, these results provide an approach to measure ultrafast dynamics and determine the required uniformity of layered materials depending on the speed limit constraints for specific applications.
Here, the utility of the sterically bulky terphenylthiolate ligand, (SAr iPr6 ) 1− in expanding uranium reductive chemistry has been explored. Reduction of U(SAr iPr6 ) 2 I forms the U(II) complex, U(SAr iPr6 ) 2 , in which the metal is protected by the flanking arene rings of the ligand, but they move out of the way to accommodate the four electron reduction of PhN=NPh to form the U(VI) bis(imido) product U(SAr iPr6 ) 2 (=NPh) 2 (THF) 2 . Here, the KC 8 reduction of U(SAr iPr6 ) 2 generates a more reduced complex, KU(μ-SAr iPr6 ) 2 , initially identified by a −2.55 V vs. Fc + /Fc electrochemical reduction event in THF.
Cooling of protons at top energy (γ = 293) to counteract the IBS driven emittance growth can be beneficial to the EIC performance. The Ring Electron Cooler provides such capability.
Electric energy behavior for ground state of one-electron heteronuclear diatomic molecule near united atom
Gravitational effect on free falling electrons in vacuum, showing gravitational induction of electric field outside metal surface
Electron-bremsstrahlung cross sections for thin targets of Al, Au, Cu, and Sn between 0.2 and 2.5 MeV
Electron bremsstrahlung produced in thick targets of Al, Au, Be, Fe, and Sn at incident energies between 0.2 and 2.8 MeV
Survey of electron beam and laser techniques applicable to spacecraft joining
Channel electron multipliers for cathode luminescent collection of topographic details