Measurement of the vertical non-uniformity of the plasma sheath in a complex plasma

TL;DR

This study experimentally measures the vertical non-uniformity of plasma sheath in complex plasma by analyzing the anisotropic forces between dust particles, revealing the influence of ion wakefields on force distribution.

Contribution

It introduces an attenuated oscillation method to quantify the vertical non-uniformity of plasma sheath and demonstrates the force asymmetry caused by ion wakefields.

Findings

Upper particle experiences a stronger repulsive force than the lower.

Ion wakefields significantly influence force distribution in the sheath.

Experimental data supports the anisotropic interaction force measurement.

Abstract

Employing an attenuated oscillation method, the anisotropic interaction force between two vertically aligned dust particles located in the sheath of a complex plasma was measured experimentally based on a linear approximation to the interaction force. Experimental data shows that although both particles experience a repulsive interaction force, the upper particle experiences a stronger magnitude force than does the lower. This result can be explained by the ion wakefield since the lower particle resides within the ion wakefield generated by the streaming ions passing through the sheath and around the upper particle.