Double origin of stochastic granular tribocharging

TL;DR

This study explores the stochastic nature of triboelectric charging in granular particles, revealing asymmetric charge distributions with a linear correlation between their mean and width, and proposing a combined stochastic model.

Contribution

It introduces a new model that explains the stochastic charge distributions and correlations observed in granular tribocharging experiments.

Findings

Charge distributions are wider than normal with exponential decay.

Distributions are asymmetric and include charges of both signs.

A linear correlation exists between the mean and width of charge distributions.

Abstract

The mechanisms underlying triboelectric charging have a stochastic nature. We investigate how this randomness affects the distributions of charges generated on granular particles during either a single or many collisions. The charge distributions we find in our experiments are wider than normal distributions with an exponential decay of the probability, they are asymmetric, and exhibit charges of both signs. Moreover, we find a linear correlation between the width and mean of these distributions. We rationalize these findings with a model for triboelectric charging which combines stochastic charge separation during contact and stochastic charge recombination after separation of the surfaces. Our results further imply that subsequent charging events are not statistically independent.