In Granular Charging, Does Size Really Matter?

Spontaneous charging in systems of particles, causing particle separation and electrical discharges, is commonly observed in pharmaceutical powder beds, sandstorms and natural dust plumes. Previous studies have attributed size difference or external factors such as wind or an outside electric field as the primary driving force behind such large scale charging. In this talk we discuss experimental results showing that systems of uniformly sized particles with no external field still exhibit net polarization and charging buildup. We also present computational results modeled from a variation of Dyson's Ising model, which validates this behavior and predicts new types of phenomena.