Benchmarking between fluid and global models for low-pressure oxygen DC glow discharges

TL;DR

This study compares a zero-dimensional global model and a one-dimensional fluid model for oxygen DC glow discharges, finding good agreement at lower pressures but decreasing accuracy at higher pressures, guiding model choice based on pressure conditions.

Contribution

It provides a systematic benchmarking of 0D and 1D models for oxygen glow discharges, highlighting the limitations of volume-averaged models at higher pressures.

Findings

Good agreement (<5%) on main discharge parameters at all pressures.

Relative differences in species densities increase with pressure, up to 57%.

Volume-averaged models are recommended only up to 10 Torr.

Abstract

This work focuses on the benchmarking between a zero-dimensional (0D) global model (LoKI) and a one-dimensional (1D) radial fluid model for the positive column of oxygen DC glow discharges in a tube of 1 cm inner radius at pressures between 0.5 Torr and 10 Torr. The data used in the two models are the same, so that the difference between the models is reduced to dimensionality. A good agreement is found between the two models on the main discharge parameters, with relative differences below 5%. The agreement on species average number densities, charged and neutral, is slightly worse, with relative differences increasing with pressure from 11% at 0.5 Torr to 57% at 10 Torr. The success of the 0D global model in describing these plasmas through volume averaged quantities decreases with pressure, due to pressure-driven narrowing of radial profiles. Hence, in the studied conditions, we recommend the use of volume-averaged models only in the pressure range up to 10 Torr.