Precision measurement of tribocharging in acoustically levitated sub-millimeter grains

Abstract

Contact electrification of dielectric grains forms the basis for a myriad of physical phenomena. However, even the basic aspects of collisional charging between grains are still unclear. Here we develop a new experimental method, based on acoustic levitation, which allows us to controllably and repeatedly collide two sub-millimeter grains and measure the evolution of their electric charges. This is therefore the first tribocharging experiment to provide complete electric isolation for the grain-grain system from its surroundings. We use this method to measure collisional charging rates between pairs of grains for three different material combinations: polyethylene-polyethylene, polystyrene-polystyrene, and polystyrene-sulfonated polystyrene. The ability to directly and noninvasively collide particles of different constituent materials, chemical functionality, size, and shape opens the door to detailed studies of collisional charging in granular materials. arXiv:1910.09669v1 [cond-mat.soft]

Ionizing protoplanetary discs in pebble collisions

“…(from Jungmann et al (2021) charging as motivation to estimate the effect for disks. The experiments by are similar in some sense to Kline et al (2020). We also study the charge on two grains before and after a collision.…”

“…This might be due to the fact that only little data exist on this. Kline et al (2020) were recently the first to publish results on high precision charge measurements in a collision experiment with charge being determined for two particles prior to and after a bouncing collision. The grains were stored in an acoustic trap before their collision and afterwards.…”

Quantifying Contact‐Electrification Induced Charge Transfer on a Liquid Droplet after Contacting with a Liquid or Solid

“…[7] It was reported that acoustic levitation technology can levitate liquid droplets, and further widely utilized to study areas include manipulation of subject, [8] chemical reaction, [9] material anal ysis, [10] etc. Except for liquid-liquid case, some studies using acoustic levitation to study CE between solids and solids, [11] solids and liquids [12] have been reported. We realized that the liquid droplet can be suspended in air to avoid contacting with solids and introducing extra charges [13] in the CE experiments.…”

Measuring Electric Dipole Moments of Trapped Sub-mm Particles

“…One method that allows particles to be trapped regardless of their charge is acoustic levitation. Kline et al (2020) analyzed the oscillations caused by net charge in an electric field for an acoustically trapped particle. Here, even large changes in net charge, e.g.…”

“…However, we are rather interested in the rotational motion. So while Kline et al (2020) study the linear oscillations of grains due to their net charge in the electric field of a capacitor, we study rotational motion, as the electric field induces oscillations with characteristic frequencies trying to align electric dipoles.…”