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Reliable electron yield (EY) measurements of highly insulating granular particles have long been considered too difficult to collect due the many experimental complexities that arise from the nature of the granular materials. This has led to a critical knowledge gap for both engineering strategies and basic science issues essential for myriad important space applications. This talk will emphasize the preliminary EY measurements of highly insulting granular samples we have collected, including a range of samples with typical particle size ranging from ~1 μm to ~100 μm, samples with cubical, spherical and highly angular particle shapes, studies of highly angular Al2O3 polishing compound particles adhered to graphitic carbon conductive tape from 0% to ~100% coverage that demonstrates the effectiveness of the sample preparation methods used for dust samples. Acquisition of these accurate high-yield curves, which showed minimal charging effects, demonstrated our ability to make EY measurements for high-yield highly-insulating samples, unlike previous results for dust which showed highly suppressed yields due to severe charging effects. All this work has importance in applications surrounding lunar dust, which has been recognized as one of the most immediate and critical issues faced when expanding into deep space, mitigation of charged dust. The effects of surface roughness were demonstrated through comparison of EY for highly polished single crystal sapphire, rougher microcrystalline Al2O3, and very rough and porous layers of granular alumina; these were found to have the same shape of the yield curves and energy at maximum yield, while maximum yield decreased from 15 to ~2.5 as roughness increased. It was apparent that the maximum yield drastically decreased as the surface roughness of the materials increased from sample to sample.

Publication Date



Logan, UT


charging effects, dusty plasmas, electron yield, granular samples


Physical Sciences and Mathematics

Electron Yield Measurements of Highly Insulating Granular Samples Related to Charging of Dusty Plasmas