Effect of mixture properties on size-dependent charging of same-material dielectric grains

Abstract

Experiments on same-material granular tribocharging in bidisperse mixtures have demonstrated a clear size dependence in the polarity of charge on each species. These experiments typically involve charging via fluidization or shaking in air or similar environments, and frequently measure only overall polarity rather than individual grain charge. These experiments require discrete size species in each mixture, and may include additional environmental influences on the charging process that remain poorly understood. Using our methodology for charging in high vacuum and measuring individual grain charge, we have examined mixtures of zirconia-silica grains with two primary size species combined in varying quantities. We have explored the accuracy of a variety of charging models compared to the charge distributions observed in our experiments. Our experimental results will inform future theoretical models for the charge transfer mechanism in dielectric grains.