Plasma

21 pages, 7032 KB

Open AccessArticle

Non-Thermal Plasma Treatment of Dye-Contaminated Wastewater: A Sustainable Approach for Pollutant Degradation and Enhanced Plant Growth

by Subash Mohandoss, Harshini Mohan, Natarajan Balasubramaniyan and Sivachandiran Loganathan

Plasma 2025, 8(4), 40; https://doi.org/10.3390/plasma8040040 (registering DOI) - 11 Oct 2025

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Abstract

The win–win situation of dye degradation and nitrogen fixation in wastewater using non-thermal plasma (NTP) were investigated in this study. Specifically, the feasibility of utilizing plasma-treated dye-contaminated wastewater for seed germination and plant growth was explored. Crystal Violet (CV) and Rhodamine B (RhB) dyes were used as model pollutants, while Sorghum bicolor (great millet) seeds were used to assess germination rates and plant growth responses. In untreated wastewater containing CV and RhB, approximately 45% of seeds germinated after three days, but no significant stem or root growth was observed after 11 days. Plasma treatment significantly enhanced dye degradation, with efficiency improving as treatment time and input power increased. After 16 min of plasma treatment at 1.3 ± 0.2 W input power, about 99% degradation efficiency was achieved for both CV (0.0122 mM) and RhB (0.0104 mM). This degradation was primarily driven by reactive oxygen and nitrogen species (RONS) generated by plasma discharge. When sorghum seeds were germinated using plasma-treated wastewater, the germination rate increased to 65% after three days—20% higher than with untreated wastewater. Furthermore, after 11 days, the average stem length reached 9 cm, while the average root length extended to 7 cm. These findings highlight NTP as a promising and sustainable method for degrading textile industry pollutants while simultaneously enhancing crop productivity through the reuse of treated wastewater. Full article

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

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16 pages, 2928 KB

Open AccessArticle

PIC Modeling of Ionospheric Plasma Diagnostics by Hemispherical Probes: Study of the LAP-CSES at Magnetic Conjugates

by Nadia Imtiaz, Saeed Ur Rehman, Liu Chao, Rui Yan and Richard Marchand

Plasma 2025, 8(4), 39; https://doi.org/10.3390/plasma8040039 - 30 Sep 2025

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Abstract

We present three dimensional particle-in-cell simulations of current-voltage characteristics of the hemispherical Langmuir probe (LAP), onboard the China Seismo-Electromagnetic Satellite (CSES). Using realistic plasma parameters and background magnetic fields obtained from the International Reference Ionosphere (IRI) and International Geomagnetic Reference Field (IGRF) models, we simulate probe–plasma interactions at three locations: the equatorial region and two magnetically conjugate mid-latitude sites: Millstone Hill (Northern Hemisphere) and Rothera (Southern Hemisphere). The simulations, performed using the PTetra PIC code, incorporate realistic LAP geometry and spacecraft motion in the ionospheric plasma. Simulated current voltage characteristics or I–V curves are compared against in-situ LAP measurements from CSES Orbit-026610, with Pearson’s correlation coefficients used to assess agreement. Our findings indicate how plasma temperature, density, and magnetization affect sheath structure and probe floating potential. The study highlights the significance of kinetic modeling in enhancing diagnostic accuracy, particularly in variable sheath regimes where classic analytical models such as the Orbital-Motion-Limited (OML) theory may be inadequate. Full article

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12 pages, 3315 KB

Open AccessArticle

Polishing Inner Surface of Dies with a Beam of Fast Argon Atoms

by Alexander S. Metel, Marina A. Volosova, Enver S. Mustafaev, Yury A. Melnik and Sergey N. Grigoriev

Plasma 2025, 8(4), 38; https://doi.org/10.3390/plasma8040038 - 28 Sep 2025

Viewed by 167

Abstract

The removal of defective surface layers can substantially improve the quality of various products. It can be carried out using beams of accelerated ions or fast argon atoms. However, it is difficult to process the inner surface of narrow channels. In the present work, a narrow beam of fast argon atoms is used to sputter and polish the inner surface of drawing dies with 5.7 mm wide working channels. Due to the high angle of incidence to the channel walls, sputtering with fast argon atoms decreased their roughness to Ra ~ 0.004 µm. Full article

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

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Plasma, Volume 8, Issue 4 (December 2025) – 3 articles

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