Vertical probe-induced asymmetric dust oscillation in complex plasma

TL;DR

This study investigates how a vertical probe perturbs a Coulomb crystal of dust particles in plasma, revealing asymmetric oscillations and cavity formation, with experimental results compared to a plasma sheath model.

Contribution

It introduces a novel experimental setup to perturb and analyze dust crystal oscillations using a vertical probe in plasma, and compares observations with a theoretical sheath model.

Findings

Cavity formation in the dust crystal occurs as the probe approaches.

Oscillations of the probe induce asymmetric dust particle motion.

Experimental levitation height changes align with the electric field model.

Abstract

Spherical, micrometer-sized particles within a Coulomb crystal levitated in the sheath above the powered lower electrode in a GEC reference cell are perturbed using a Zyvex S100 Nanomanipulator. Using the S100, a vertical probe is positioned within the cell at various locations with respect to the crystal formed within the sheath. As the probe is lowered toward the horizontal plane of the dust layer, a circular cavity opens in the center of the crystal and expands. To explore the minimally perturbative state, the probe is lifted to the position that closes this cavity, the probe potential is oscillated, and the motion of the particle directly beneath the probe is analyzed. Using a simple electric field model for the plasma sheath, the change predicted in the levitation height is compared with experiment.