Electrostatic charging of wind-blown dust and implications on dust transport

It is well known that electric fields occur in wind-blown dust, due to the triboelectric charging of particles as they collide. Triboelectric charging, or contact electrification, is a poorly understood and complex phenomenon. It is especially important in granular systems, as the high surface-to-volume ratio can lead to the build-up of large amounts of charge. A particularly surprising effect, which is important in dust systems, is that charge transfer occurs in systems of a single composition, such that there is a particle-size dependent polarity of the particles. Here, we use a combined experimental and theoretical approach to elucidate the electrostatic charging that occurs during dust storms, and the effects of this electrostatic charging on dust transport. We create laboratory-scale wind-blown dust systems, and study the electrostatic charging. We find that larger particles tend to charge positive and to stay at or near the sand bed, while smaller particles tend to charge negative and get lofted to higher elevations. This self-segregating of charged particles would lead to electric fields within a dust storm. Our results show that electric fields then increase the dust transport by more easily lofting charged particles.