arXiv subjects

David Steuer

Publications and source records attributed to David Steuer.

3 recordsLinked to original sources

arXiv2026

3D CO-TALIF distribution above a micro cavity discharge: A systematic approach for plasma catalysis

We investigate a micro cavity plasma array (MCPA) reactor operated at atmospheric pressure, offering excellent diagnostic accessibility and flexible opportunities for catalyst integration. Dissociation processes, such as $\mathrm{CO}$ production from $\mathrm{CO}_{2}$ diluted in helium, are studied. The diagnostic setup, combining TALIF with an ICCD camera, enables three-dimensional spatially resolved measurements of $\mathrm{CO}$ number densities above the $\mathrm{CO}$-generating discharges. The measured distributions are compared to a basic three-dimensional diffusion model, showing good agreement and revealing the dominant transport mechanisms. Flow variation studies indicate that the gas flow inside the reactor follows a laminar, Poiseuille-like profile, while the transport behavior is consistent with literature values for the diffusion coefficient of $\mathrm{CO}$, further validating the model. The high estimated local dissociation within the MCPA discharges (about $40\%$) results in saturation of $\mathrm{CO}$ production under increasing voltage. Combined with complementary diagnostics developed for this discharge, including measurements of surface charges, electric fields, and atomic oxygen, this approach provides a suitable platform for systematic studies of plasma catalyst interactions.

physics.plasm-ph↗

arXiv2025

Analyzing atomic oxygen product evolution in Micro Cavity Plasma Arrays by a combination of a Multi-PMT OES Setup and a 0-D Chemical Model

Dielectric barrier discharges (DBDs) are widely used in applications such as ozone generation and volatile organic compound treatment, where performance can be enhanced through catalyst integration. A fundamental understanding of reactive species generation is essential for advancing these technologies. However, temporally resolving reactive species production, especially during the initial discharges, remains a challenge, despite its importance for controlling production rates and energy efficiency. This study examines atomic oxygen production as a model system for reactive species production in a micro-cavity plasma array, a custom surface DBD confined to micrometer-sized cavities. Optical emission spectroscopy was employed to investigate plasma-chemical processes in helium with 0.1-0.25$\%$ molecular oxygen admixture at atmospheric pressure. The discharge, powered by a 15$\,$kHz, 600$\,$V amplitude triangular voltage, achieved near-complete oxygen dissociation (up to 100$\%$), as determined via helium state-enhanced actinometry (SEA). A novel multi-photomultiplier system enabled precise temporal tracking of atomic oxygen density and dissociation dynamics. To ensure measurement accuracy, a basic 0D chemical model was developed, reinforcing the reliability of the experimental results.

physics.plasm-ph↗

arXiv2021

Zero-dimensional and pseudo-one-dimensional models of atmospheric-pressure plasma jet in binary and ternary mixtures of oxygen and nitrogen with helium background

A zero-dimensional (volume-averaged) and a pseudo-one-dimensional (plug-flow) model are developed to investigate atmospheric-pressure plasma jet devices operated with He, He/O$_2$, He/N$_2$ and He/N$_2$/O$_2$ mixtures. The models are coupled with the Boltzmann equation under the two-term approximation to self-consistently calculate the electron energy distribution function (EEDF). The simulation results are verified against spatially resolved model calculations and validated against a wide variety of measurement data. The nitric oxide (NO) concentration is thoroughly characterized for a variation of the gas mixture ratio, helium flow rate and absorbed power. The concentration measurements at low power are better captured by the simulation with a larger hypothetical "effective" rate coefficient value for the reactive quenching N$_2$(A$^3Σ$,B$^3Π$) + O($^3$P) $\to$ NO + N($^2$D). This suggests that the NO production at low power is also covered by the species N$_2$(A$^3Σ$,B$^3Π$;v>0) and multiple higher N$_2$ electronically excited states instead of only N$_2$(A$^3Σ$,B$^3Π$;v=0) in this quenching. Furthermore, the O($^3$P) density measurements under the same operation conditions are also better predicted by the simulations with a consideration of the aforementioned hypothetical rate coefficient value. It is found that the contribution of the vibrationally excited nitrogen molecules N$_2$(v$\geqslant$13) to the net NO formation rate gains more significance at higher power. The vibrational distribution functions (VDFs) of O$_2$(v<41) and N$_2$(v<58) are investigated. The sensitivity of the zero-dimensional model with respect to a variation of the VDF resolutions, wall reaction probabilities and synthetic air impurity levels is presented. The simulated plasma properties are sensitive to the variation especially for a feeding gas mixture containing nitrogen.

physics.plasm-ph↗