# The origin of large amplitude oscillations of dust particles in a plasma sheath

## TL;DR

This paper investigates the spontaneous, large-amplitude oscillations of micron-sized dust particles in plasma sheaths, revealing their regularity, underlying electrostatic forces, and charging dynamics through combined experimental and numerical methods.

## Contribution

It introduces a comprehensive experimental and numerical analysis of dust particle oscillations, elucidating the electrostatic and charging mechanisms behind large amplitude motions.

## Key findings

- Particles oscillate with amplitudes over 1 cm, larger than previously observed.
- The motion reveals electrostatic force and charge variation in the plasma sheath.
- A delayed-charging model accurately captures the nonlinear dynamics.

## Abstract

Micron-size charged particles can be easily levitated in low-density plasma environments. At low pressures, suspended particles have been observed to spontaneously oscillate around an equilibrium position. In systems of many particles, these oscillations can catalyze a variety of nonequilibrium, collective behaviors. Here, we report spontaneous oscillations of single particles that remain stable for minutes with striking regularity in amplitude and frequency. The oscillation amplitude can also exceed 1 cm, nearly an order of magnitude larger than previously observed. Using an integrated experimental and numerical approach, we show how the motion of an individual particle can be used to extract the electrostatic force and equilibrium charge variation in the plasma sheath. Additionally, using a delayed-charging model, we are able to accurately capture the nonlinear dynamics of the particle motion, and estimate the particle's equilibrium charging time in the plasma environment.