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Full-Text Articles in Physics
Atomic Oxygen Modification Of The Nanodielectric Surface Composition Of Carbon-Loaded Polyimide Composites, Kelby T. Peterson, Jr Dennison
Atomic Oxygen Modification Of The Nanodielectric Surface Composition Of Carbon-Loaded Polyimide Composites, Kelby T. Peterson, Jr Dennison
Posters
Black Kapton is a nanodielectric composite of carbon particles (100-500 nm) embedded in an insulating polyimide polymer matrix (100-5000 nm depth). Analysis of this nanodielectric composite has been done via optical imaging, scanning electron microscopy, and energy- dispersive x-ray analysis in order to gain insight into its nanodielectric properties. The insulating polyimide is known to be inert and impervious to strong bases and acids, but is affected by atomic oxygen exposure. We have observed changes in the surface structure and relative carbon- polymer concentrations in MISSE-6 samples that were exposed to the low earth orbit environment for 18 months outside …
Diverse Electron-Induced Optical Emissions From Space Observatory Materials At Low Temperatures, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Charles W. Bowers, Robert H. Meloy
Diverse Electron-Induced Optical Emissions From Space Observatory Materials At Low Temperatures, Jr Dennison, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Charles W. Bowers, Robert H. Meloy
Conference Proceedings
Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (<1 s) arcing, resulting from electrostatic discharge; and (iii) intermediate-duration (~100 s) glow—termed “flares”. We discuss how the electron currents and arcing—as well as light emission absolute intensity and frequency—depend on electron beam energy, power, and flux and the temperature and thickness of different bulk (polyimides, epoxy resins, and silica glasses) and composite dielectric materials (disordered SiO2 thin films, carbon- and fiberglass-epoxy composites, and macroscopically-conductive carbon-loaded polyimides). We conclude that electron-induced optical emissions resulting from interactions between observatory materials and the space environment electron flux can, in specific circumstances, make significant contributions to the stray light background that could possibly adversely affect the performance of space-based observatories.
Pulsed Electro-Acoustic (Pea) Measurements Of Embedded Charge Distributions, Jr Dennison, Lee H. Pearson
Pulsed Electro-Acoustic (Pea) Measurements Of Embedded Charge Distributions, Jr Dennison, Lee H. Pearson
Conference Proceedings
Knowledge of the spatial distribution and evolution of embedded charge in thin dielectric materials has important applications in semiconductor, high-power electronic device, high-voltage DC power cable insulation, high-energy and plasma physics apparatus, and spacecraft industries. Knowing how, where, and how much charge accumulates and how it redistributes and dissipates can predict destructive charging effects. Pulsed Electro-acoustic (PEA) measurements— and two closely related methods, Pressure Wave Propagation (PWP) and Laser Intensity Modulation (LIMM)— nondestructively probe such internal charge distributions. We review the instrumentation, methods, theory and signal processing of simple PEA experiments, as well as the related PPW and LIMM methods. …
Simulation Chamber For Space Environment Survivability Testing, Robert H. Johnson, Lisa D. Montierth
Simulation Chamber For Space Environment Survivability Testing, Robert H. Johnson, Lisa D. Montierth
Student Showcase
A vacuum chamber was designed and built that simulates the space environment making possible the testing of material modification due to exposure of solar radiation. Critical environmental components required include an ultra high vacuum (10-9 Torr), a UV/VIS/NIR solar spectrum source, an electron gun and charge plasma, temperature extremes, and long exposure duration. To simulate the solar spectrum, a solar simulator was attached to the chamber with a range of 200nm to 2000nm. The exposure time can be accelerated by scaling the solar intensity up to four suns. A Krypton lamp imitates the 120 nm ultraviolet hydrogen Lymann alpha emission …
Simulation Of Uv Radiation Degradation Of Polymers On Misse-6 In The Low Earth Orbit Environment, Kelby T. Peterson, Jr Dennison
Simulation Of Uv Radiation Degradation Of Polymers On Misse-6 In The Low Earth Orbit Environment, Kelby T. Peterson, Jr Dennison
Research on the Hill (Salt Lake City)
The Sate of Utah Space Environment & Contamination Study (SUSpECS) experiment flown on the Materials International Space Station Experiment 6 (MISSE-6) was an experiment designed to examine the consequences of the space environment on various materials used in space-component design. SUSpECS was comprised of approximately 180 samples that were suspended from the side of the International Space Station (ISS) for 18 months and returned to allow for pre- and post-flight comparisons. The sample with the most evident changes was a thin film of polyethylene terephthalate (PET) MylarTM coated with Vapor Deposited Aluminum (VDA). The post- flight analysis showed evidence of …
Properties Of Cathodoluminescence For Cryogenic Applications Of Sio2-Based Space Observatory Optics And Coatings, Amberly Evans Jensen, Jr Dennison, Gregory Wilson, Justin Dekany, Charles Bpwers, Robert Meloy, James B. Heaney
Properties Of Cathodoluminescence For Cryogenic Applications Of Sio2-Based Space Observatory Optics And Coatings, Amberly Evans Jensen, Jr Dennison, Gregory Wilson, Justin Dekany, Charles Bpwers, Robert Meloy, James B. Heaney
Conference Proceedings
Disordered thin film SiO2/SiOx coatings undergoing electron-beam bombardment exhibit cathodoluminescence, which can produce deleterious stray background light in cryogenic space-based astronomical observatories exposed to high- energy electron fluxes from space plasmas. As future observatory missions push the envelope into more extreme environments and more complex and sensitive detection, a fundamental understanding of the dependencies of this cathodoluminescence becomes critical to meet performance objectives of these advanced space-based observatories. Measurements of absolute radiance and emission spectra as functions of incident electron energy, flux, and power typical of space environments are presented for thin (~60-200 nm) SiO2/SiOx optical coatings on reflective metal …