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Articles 1 - 5 of 5
Full-Text Articles in Structures and Materials
Secondary Electron Yield Measurements Of Carbon Nanotube Forests: Dependence On Morphology And Substrate, Brian Wood, Jordan Lee, Gregory Wilson, T. -C. Shen, Jr Dennison
Secondary Electron Yield Measurements Of Carbon Nanotube Forests: Dependence On Morphology And Substrate, Brian Wood, Jordan Lee, Gregory Wilson, T. -C. Shen, Jr Dennison
Journal Articles
Total, secondary, and backscatter electron yield data were taken with beam energies between 15 eV and 30 keV, in conjunction with energy emission data, to determine the extent of suppression of yield caused by carbon nanotube (CNT) forest coatings on substrates. CNT forests can potentially lower substrate yield due to both its inherently low-yield, low-atomic number (Z) carbon composition, and its bundled, high-aspect ratio structure. Rough surfaces, and in particular, surfaces with deep high-aspect-ratio voids, can suppress yields, as the electrons emitted from lower lying surfaces are recaptured by surface protrusions rather than escaping the near-surface region. Yields of multilayered …
Wireless Antenna Detection Of Electrostatic Discharge Events, Allen Andersen, Jr Dennison
Wireless Antenna Detection Of Electrostatic Discharge Events, Allen Andersen, Jr Dennison
Journal Articles
Wireless intraspacecraft communication technology is being developed for signal transfer on space missions to save weight and simplify the design. One consideration for this new technology is its interaction with space environmentinduced electrostatic discharges (ESDs). The short time scales of spacecraft ESD events result in broad frequency band signals that can interact with high-frequency wireless antennas. These interactions present a source of signal noise. However, they also present a possibility of in-flight wireless ESD monitoring. We present laboratory measurements of arcing on common spacecraft insulators using commercially available single-band 2.4-GHz and dual-band 2.4-/5.8-GHz Wi-Fi antennas. These wireless detections are shown …
Design Survey Of Laminated Composite I-Beam, Mrinmoy Saha
Design Survey Of Laminated Composite I-Beam, Mrinmoy Saha
All Graduate Plan B and other Reports, Spring 1920 to Spring 2023
Composite I-beams are popular for high-strength low-weight applications. Learning the macro-mechanics and designing the composite I-beam properly are necessary. In this report, a design overview of the composite I-beam is discussed which is based on classical lamination theory where it includes the homogenization approach, the plane stress assumption and the Kirchhoff hypothesis. Using these assumptions, a method was developed to come up with the effective material properties of a beam. Formulas to calculate maximum deflection and maximum bending stress and shear stress and the stress concentration at the connection of web-flange are discussed which describe ways for designing and manufacturing …
Electron Yield Measurements Of High-Yield, Low-Conductivity Dielectric Materials, Justin Christensen
Electron Yield Measurements Of High-Yield, Low-Conductivity Dielectric Materials, Justin Christensen
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this …
An Enhanced Operational Definition Of Dielectric Breakdown For Dc Voltage Step-Up Tests, Allen Andersen, Jr Dennison
An Enhanced Operational Definition Of Dielectric Breakdown For Dc Voltage Step-Up Tests, Allen Andersen, Jr Dennison
Journal Articles
The imprecise definition of breakdown in the ASTM D3755-14 standard can misidentify breakdown. If the recommended test circuit current sensing element threshold is set too high, breakdown may occur undetected. Conversely, false positives may result from designating a low current threshold. An operational definition of breakdown much less sensitive to these pitfalls is outlined herein. This enhanced definition of breakdown is based on the average rate of change of the leakage current with increasing voltage, rather than a simple current threshold, avoiding ambiguous association with anomalies in current traces. For tests that continuously monitor leakage current, breakdown can be detected …