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Full-Text Articles in Physics
Low Temperature Cathodoluminescence Of Space Observatory Materials, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Jr Dennison
Low Temperature Cathodoluminescence Of Space Observatory Materials, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Jr Dennison
Conference Proceedings
In recent charging studies, a discernable glow was detected emanating from sample surfaces undergoing electron beam bombardment that resulted from a luminescent effect termed cathodoluminescence. This suggests that some of the materials used as optical elements, structural components, and thermal control surfaces in the construction of space-based observatories might luminesce when exposed to sufficiently energetic charged particle fluxes from the space plasma environment. If these visible, infrared and ultraviolet emissions are intense enough, they can potentially produce optical contamination detrimental to the performance of the observatory optical elements and sensors, and act to limit their sensitivity and performance windows. As …
Charging Effects Of Multilayered Dielectric Spacecraft Materials: Surface Voltage, Discharge And Arcing, Gregory Wilson, Amberly Evans Jensen, Justin Dekany, Jr Dennison
Charging Effects Of Multilayered Dielectric Spacecraft Materials: Surface Voltage, Discharge And Arcing, Gregory Wilson, Amberly Evans Jensen, Justin Dekany, Jr Dennison
Conference Proceedings
Charging of thin-film, multilayer dielectric materials subject to electron bombardment was found to evolve with time. The charging behavior was also highly dependent on the incident energy of the monoenergetic electron beams; this is driven by energy dependant processes including the electron penetration depth, electron emission, and material conductivity. The electron penetration depth is the average range to which incident electrons at a given incident energy penetrate into the material, thus defining the mean depth of an embedded charge layer. The secondary electron yield is the ratio of electrons emitted from the surface to the number of incident electrons; this …
Evaluation Of The Temperature Dependence Of Endurance Models Of Electrostatic Breakdown, Charlie Sim, Jr Dennison
Evaluation Of The Temperature Dependence Of Endurance Models Of Electrostatic Breakdown, Charlie Sim, Jr Dennison
Senior Theses and Projects
The goal of this research was to investigate temperature and time dependent models for the electrostatic breakdown of polymeric spacecraft insulators. Temperature dependent breakdown was found by inducing an electrostatic breakdown in the prototypical polymer Low Density Polyethylene (LDPE) at various temperatures. Time dependent breakdown was found by applying a static voltage to LDPE and measuring the time to electrostatic breakdown. No significant temperature dependence of the electrostatic breakdown of LDPE was observed in a temperature range of 150 K to 300 K. The time dependent results show that the time to electrostatic breakdown is modeled by a negative logarithmic …
The Effects Of Surface Roughness On Diffuse Optical Reflection And Photoyields On Spacecraft Materials, Amberly Evans Jensen
The Effects Of Surface Roughness On Diffuse Optical Reflection And Photoyields On Spacecraft Materials, Amberly Evans Jensen
Senior Theses and Projects
The goal of this project was to measure the change in the absorbance of spacecraft materials due to changes in the surface of the material. The absorbance was obtained by measuring reflectance and transmittance. We found that modifying the surface of a material did affect the material’s specular reflectance. However, the change may not have been entirely due to an increase in absorbance, but may also imply an increase in the diffuse reflection. To understand the affect on absorbance, diffuse reflectance and transmission will need to be measured. This will lead to a prediction of how surface modification affects the …