# Capacitively-coupled rf discharge with a large amount of microparticles: spatiotemporal emission pattern and microparticle arrangement

## TL;DR

This study investigates how micron-sized particles influence the behavior and emission patterns of a low-pressure rf discharge, combining experiments and simulations to understand the effects of microparticle arrangements.

## Contribution

It introduces a combined experimental and numerical approach to analyze microparticle effects on plasma emission patterns, highlighting limitations of one-dimensional models.

## Key findings

- Microparticle arrangements significantly affect emission patterns.
- One-dimensional models cannot fully reproduce observed phenomena.
- Radial diffusion likely causes discrepancies in simulations.

## Abstract

The effect of micron-sized particles on a low-pressure capacitively-coupled rf discharge is studied both experimentally and using numerical simulations. In the laboratory experiments, microparticle clouds occupying a considerable fraction of the discharge volume are supported against gravity with the help of the thermophoretic force. The spatiotemporally resolved optical emission measurements are performed with different arrangements of microparticles. The numerical simulations are carried out on the basis of a one-dimensional hybrid (fluid-kinetic) discharge model describing the interaction between plasma and microparticles in a self-consistent way. The study is focused on the role of microparticle arrangement in interpreting the spatiotemporal emission measurements. We show that it is not possible to reproduce simultaneously the observed microparticle arrangement and emission pattern in the framework of the considered one-dimensional model. This disagreement is discussed and attributed to two-dimensional effects, e.g., radial diffusion of the plasma components.