Plasma

14 pages, 2726 KiB

Open AccessArticle

Streamer Discharge Modeling for Plasma-Assisted Combustion

by Stuart Reyes and Shirshak Kumar Dhali

Plasma 2025, 8(3), 28; https://doi.org/10.3390/plasma8030028 - 10 Jul 2025

Some of the popular and successful atmospheric pressure fuel/air plasma-assisted combustion methods use repetitive ns pulsed discharges and dielectric-barrier discharges. The transient phase in such discharges is dominated by transport under strong space charge from ionization fronts, which is best characterized by the streamer model. The role of the nonthermal plasma in such discharges is to produce radicals, which accelerates the chemical conversion reaction leading to temperature rise and ignition. Therefore, the characterization of the streamer and its energy partitioning is essential to develop a predictive model. We examine the important characteristics of streamers that influence combustion and develop some macroscopic parameters. Our results show that the radicals’ production efficiency at an applied field is nearly independent of time and the radical density generated depends only on the electrical energy density coupled to the plasma. We compare the results of the streamer model to the zero-dimensional uniform field Townsend-like discharge, and our results show a significant difference. The results concerning the influence of energy density and repetition rate on the ignition of a hydrogen/air fuel mixture are presented. Full article

(This article belongs to the Special Issue New Insights into Plasma Theory, Modeling and Predictive Simulations)

► Show Figures

Figure 1

28 pages, 8047 KiB

Open AccessArticle

Hybrid Dielectric Barrier Discharge Reactor: Production of Reactive Oxygen–Nitrogen Species in Humid Air

by Dariusz Korzec, Florian Freund, Christian Bäuml, Patrik Penzkofer, Oliver Beier, Andreas Pfuch, Klaus Vogelsang, Frank Froehlich and Stefan Nettesheim

Plasma 2025, 8(3), 27; https://doi.org/10.3390/plasma8030027 - 6 Jul 2025

Viewed by 336

Abstract

Reactive oxygen–nitrogen species (RONS) production in a Peltier-cooled hybrid dielectric barrier discharge (HDBD) reactor operated with humid air is characterized. Fourier-transform infrared spectroscopy (FTIR) is used to determine the RONS in the HDBD-produced gases. The presence of molecules

O_{3}

{NO}_{2}

[...] Read more.

O_{3}

{NO}_{2}

N_{2}

N_{2} O_{5}

, and

{HNO}_{3}

is evaluated. The influence of HDBD reactor operation parameters on the FTIR result is discussed. The strongest influence of Peltier cooling on RONS chemistry is reached at conditions related to a high specific energy input (SEI): high voltage and duty cycle of plasma width modulation (PWM), and low gas flow. Both PWM and Peltier cooling can achieve a change in the chemistry from oxygen-based to nitrogen-based.

N_{2} O_{5}

and

{HNO}_{3}

are detected at a low humidity of 7% in the reactor input air but not at humidity exceeding 90%. In addition to the FTIR analysis, the plasma-activated water (PAW) is investigated. PAW is produced by bubbling the HDBD plasma gas through 12.5 mL of distilled water in a closed-loop circulation at a high SEI. Despite the absence of

N_{2} O_{5}

and

{HNO}_{3}

in the gas phase, the acidity of the PAW is increased. The pH value decreases on average by 0.12 per minute. Full article

(This article belongs to the Special Issue Processes in Atmospheric-Pressure Plasmas—2nd Edition)

► Show Figures

Figure 1

18 pages, 995 KiB

Open AccessArticle

A Quasi-Spherical Fusion Reactor Burning Boron-11 Fuel

by Joel G. Rogers, Andrew A. Egly, Yoon S. Roh, Robert E. Terry and Frank J. Wessel

Plasma 2025, 8(3), 26; https://doi.org/10.3390/plasma8030026 - 30 Jun 2025

Viewed by 212

Abstract

In this study, particle-in-cell (PIC) simulation was used to validate a conceptual design for a quasi-spherical, net power, hydrogen-plus-boron-11-fueled fusion reactor incorporating high-temperature superconducting (HTS) magnets. By burning a fully thermalized plasma, our proposed MET6 reactor uses the principles of the 1980 magneto-electrostatic trap design of Yushmanov to improve the classic Polywell design. Because the input power consumed by the reactor will barely balance the waste bremsstrahlung radiation, future research must focus on reducing the bremsstrahlung losses to reach practical net power levels. The first step to reducing bremsstrahlung, explored in this paper, is to tune the reactor parameters to reduce the energies of trapped electrons. We assume the quality factor Q can be approximated as the ratio of fusion power output divided by bremsstrahlung power loss. Thus, assuming the particles’ power loss is negligible compared to bremsstrahlung power loss, the resulting quality factor is estimated to be Q ≈ 1.3. Full article

(This article belongs to the Special Issue Feature Papers in Plasma Sciences 2025)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Plasma, Volume 8, Issue 3 (September 2025) – 3 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI