# Wake-mediated propulsion of an upstream particle in two-dimensional plasma crystals

## TL;DR

This paper explains the wake-mediated propulsion of an extra particle in 2D plasma crystals through simulations and theory, revealing nonreciprocal interactions cause persistent self-propulsion, aligning well with experimental observations.

## Contribution

The study introduces a simple pointlike ion wake charge model to simulate and understand wake-mediated propulsion in plasma crystals, providing new insights into the underlying dynamics.

## Key findings

- Good agreement between simulated and experimental particle velocities.
- Nonreciprocal interactions due to wake charges cause persistent particle motion.
- The model successfully reproduces the wake-mediated propulsion effect.

## Abstract

The wake-mediated propulsion of an "extra" particle in a channel of two neighboring rows of a two-dimensional plasma crystal, observed experimentally by Du et al. [Phys. Rev. E 89, 021101(R) (2014)], is explained in simulations and theory. We use the simple model of a pointlike ion wake charge to reproduce this intriguing effect in simulations, allowing for a detailed investigation and a deeper understanding of the underlying dynamics. We show that the nonreciprocity of the particle interaction, owing to the wake charges, is responsible for a broken symmetry of the channel that enables a persistent self-propelled motion of the extra particle. We find good agreement of the terminal extra-particle velocity with our theoretical considerations and with experiments.