The effects of dynamics on the triboelectrification of volcanic ash

Abstract

AbstractLightning is often observed during explosive volcanic eruptions, and the charging processes associated with these displays have been attributed to several mechanisms. In this work we delineate a set of experiments designed to quantify silicate‐based triboelectric charging in the volcanic context. Using natural samples from three different volcanoes, we show that the rate of triboelectrification in a fluidized bed depends on the energy input into the granular system. Experiments are conducted employing nonintrusive electrostatic sensors, ensuring that all charge exchange arises solely from particle‐particle collisions. At higher fluidization energies, particles undergo more frequent and energetic collisions, facilitating the transfer of charge. This finding implies that triboelectric charging could help promote charging in regions of the eruptive system that contain numerous particle‐particle collisions such as the conduit and gas thrust regions. Our experiments also suggest that surface charge density is capped, at least in part, by atmospheric conditions, specifically the breakdown characteristics of the gas.