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Physics of Electrostatic Projection Revealed by High-Speed Video Imaging
摘要： Processes based on electrostatic projection are used extensively in industry, e.g., for mineral separations, electrophotography, or manufacturing of coated abrasives, such as sandpaper. Despite decades of engineering practice, there are still unanswered questions. In this paper, we present a comprehensive experimental study of the projection process of more than 1500 individual spherical alumina particles with a nominal size of 500 μm, captured by high-speed video imaging and digital image analysis. Based on flight trajectories of approximately 1100 projected particles, we determine the acquired charge and dynamics as a function of the relative humidity (RH) and the electric field intensity and compare the results with classical theories. For RH levels of 50% and above, more than 85% of distributed particles are projected, even when the electric field intensity is at its minimum level. This suggests that, beyond a critical value of the electric field intensity, the RH plays a more critical role in the projection process. We also observe that the charging time is reduced dramatically for RH levels of 50% and above, possibly due to the buildup of thin water films around the distributed particles, which can facilitate charge transfer. In contrast, projected particles at the 30% RH level exhibit excessive amounts of electric charge, between 2 and 4 times than that of the saturation value, which might be attributed to triboelectric charging effects. Finally, the physics of electrostatic projection is compared and contrasted with those of induced-charge electrokinetic phenomena, which share similar field-square scaling, as the applied electric field acts on its own induced charge to cause particle motion.
关键词： electric field intensity,high-speed video imaging,alumina particles,charge transfer,electrostatic projection,triboelectric charging,relative humidity
更新于2025-09-19 17:13:59
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Dependence of Modulation Transfer Function on Electric Field Intensity of Photo conductor and Mobility-lifetime Product of Carriers in Polycrystalline Mercuric Iodide Based Flat Panel X-Ray Detectors: A Quantitative Approach and Error Analysis
摘要： In this Paper, a simplified mathematical model for Modulation Transfer Function (MTF) of Polycrystalline Mercuric Iodide based flat panel x-ray detector is applied on three different published prototypes of Polycrystalline Mercuric Iodide. Our aim was to fit the curves generated by simulation of MTF model with the curves acquired from experimental data. The mobility-lifetime product for the best curve fitting was examined for each prototype. Percentage of fitting error has been estimated for each prototype. Finally, average absolute error has been calculated for all the incorporated prototypes. This study can be further extended to develop a generic empirical model for the Modulation Transfer Function of polycrystalline mercuric iodide based flat panel x-ray detectors.
关键词： Modulation Transfer Function,Mobility-Lifetime Product,Average Absolute Error,Error Analysis,Empirical Model,Electric Field Intensity
更新于2025-09-04 15:30:14