JR Dennison

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This study focuses on obtaining reliable electron yield measurements of highly insulating granular particles of various shape, size, and composition. Measurements of this kind have long been considered too difficult to collect on granular samples due to experimental complexities leading to a critical knowledge gap in the fundamental electrostatic behaviors of dust. A significant portion of this study was spent on preparing and characterizing granular samples before any type of measurement took place. Particles of varying sizes ranging from ~1 μm to ~100 μm, shapes including cubical, spherical, and angular, and composition including NaCl, MgO, Al2O3 and LHS1, were used to create a multilayered sample with a wide range of particulate coverage on an adhesive substrate that can withstand vacuum conditions. After preparation these particulate samples were characterized via scanning electron microscopy and subsequent electron emission measurements were then compared to measurements of the bulk particulate and substrate materials. Results demonstrated the ability to perform these difficult measurements and how the varying sample properties like roughness and coverage affected yields.

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