Experimental Measurement of Overlapped Sheaths

TL;DR

This paper introduces a novel method using micron-sized dust grains and a particle-freefall technique to measure plasma sheath profiles in overlapping regions, crucial for industrial plasma applications.

Contribution

It presents an innovative, non-perturbative approach to experimentally measure overlapping plasma sheaths using dust grains and a particle-freefall technique.

Findings

Successfully identified conditions for sheath overlap.

Quantified the magnitude of sheath overlap effects.

Demonstrated the effectiveness of the dust grain probing method.

Abstract

Due to the complicated environment of the plasma sheath, it is difficult to experimentally measure plasma characteristics in the narrow geometry where sheaths from opposite boundaries overlap. Since such geometries are often found in industrial plasma applications, accurate measurements of this type are of significant interests. In this paper, we employ micron-sized dust grains as non-perturbative probes of the plasma environment. A particle-freefall technique is then used to measure the sheath profiles produced by a rf plasma within a glass box. The results show that this technique can identify the plasma operating conditions for which the sheaths on opposite walls begin to overlap as well as the magnitude of the effect.