Scott Waitukaitis, Leiden University

The delicate dance of charged grains in zero gravity

Collaborators:  Victor Lee, Marc Miskin & Heinrich Jaeger

Poster available

Abstract: Granular systems are typically dominated by steric repulsion and gravity, but in special settings like windblown dust storms, volcanic ash plumes, and protoplanetary disks, other interactions such as the electrostatic force take center stage.  This brings up a number of basic yet largely unaddressed questions:  What is the charge distribution of a system of grains?  How do systems of same-material grains charge up?  What are the subsequent grain dynamics?  Observing a dilute, freely-falling granular stream with a co-falling camera, we watch this delicate dance in situ.  Adding a uniform, external field allows us to measure the charge distribution and probe the origins of same-material tribocharging.  Sans field, we observe attractive and repulsive Kepler orbits, cluster growth and annihilation, and granular molecule formation.  These results highlight the particular importance of polarization forces and shed light on fundamental phenomena ranging from tribocharging, to lightning generation, to planet formation.