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Full-Text Articles in Physics
Intergranular Phases In Cyclically Annealed Yba2cu3o7-X And Their Implications For Critical Current Densities, Andrew Peter Clarke
Intergranular Phases In Cyclically Annealed Yba2cu3o7-X And Their Implications For Critical Current Densities, Andrew Peter Clarke
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
We report changes in the intergranular material and grain morphology of YBa2Cu3O7-x during cyclic anneals between 780 and 980 ºC in oxygen at atmospheric pressure. Two endothermic reactions were detected: (a) the eutectic reaction of YBa2Cu3O7-x with CuO and BaCuO2 at 900 ºC (enthalpy ∆Ha) and (b) the peritectic reaction of YBa2Cu3O7-x with CuO at 950 ºC (∆Hb). During the first anneal, only reaction (b) is detected, and although it should only occur if there is an excess of CuO, …
Deep Dielectric Charging Of Spacecraft Polymers By Energetic Protons, Nelson W. Green, Jr Dennison
Deep Dielectric Charging Of Spacecraft Polymers By Energetic Protons, Nelson W. Green, Jr Dennison
Journal Articles
The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments, this emphasis on electrons is appropriate since energetic electrons are the dominant species. However, for spacecraft in orbits within the inner radiation belts, or for interplanetary and lunar space probes, proton charging effects may also be of concern. To examine bulk spacecraft charging effects in these environments, several typical highly insulating spacecraft polymers were exposed to energetic protons with energies from 1 to 10 MeV to simulate protons …
Low-Fluence Electron Yields Of Highly Insulating Materials, Ryan Hoffmann, Jr Dennison, Clint D. Thomson, Jennifer Albretson
Low-Fluence Electron Yields Of Highly Insulating Materials, Ryan Hoffmann, Jr Dennison, Clint D. Thomson, Jennifer Albretson
Journal Articles
Electron-induced electron yields of high-resistivity, high-yield materials - ceramic polycrystalline aluminum oxide and the polymer polyimide (Kapton HN), - were made by using a low-fluence, pulsed incident electron beam and charge neutralization electron source to minimize charge accumulation. Large changes in energy-dependent total yield curves and yield decay curves were observed, even for incident electron fluences of <3 fC/mm2. The evolution of the electron yield as charge accumulates in the material is modeled in terms of electron re-capture based on an extended Chung-Everhart model of the electron emission spectrum. This model is used to explain anomalies measured in highly insulating, …