Plasma

15 pages, 3448 KB

Open AccessArticle

Deposition Behavior in Atmospheric-Pressure Plasma CVD Evaluated by a Quartz Crystal Microbalance

by Kenichi Yamazaki, Hiroyuki Yasui, Tsuyoshi Noguchi, Yuuma Suenaga and Akitoshi Okino

Plasma 2026, 9(1), 8; https://doi.org/10.3390/plasma9010008 - 17 Mar 2026

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Atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) enables low-temperature coating in open air, yet the interplay between precursor activation and ambient-derived species remains unclear. Here, thin films from an amine precursor are deposited using a helium plasma and characterized by gas chromatography–mass spectrometry (GC-MS), [...] Read more.

Atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) enables low-temperature coating in open air, yet the interplay between precursor activation and ambient-derived species remains unclear. Here, thin films from an amine precursor are deposited using a helium plasma and characterized by gas chromatography–mass spectrometry (GC-MS), a quartz crystal microbalance (QCM), and X-ray photoelectron spectroscopy (XPS). GC-MS indicates partial precursor conversion and formation of oxygen- and nitrogen-containing products, consistent with participation of ambient air and moisture. QCM identifies a limited precursor-concentration window in which mass increases monotonically during plasma exposure and remains constant after shutdown; outside this window, post-discharge mass loss occurs, indicating desorption of weakly bound species. XPS confirms carbon-rich films incorporating oxygen- and nitrogen-containing functionalities and complete substrate coverage at higher precursor concentrations. Full article

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

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15 pages, 4301 KB

Open AccessArticle

Underwater Electrical Explosions of Different Metal Wires on the Microsecond Timescale

by Ron Grikshtas, Sergey Efimov, Nikita Asmedianov and Yakov E. Krasik

Plasma 2026, 9(1), 7; https://doi.org/10.3390/plasma9010007 - 11 Feb 2026

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Abstract

Underwater electrical explosions of single metallic wires driven by microsecond current pulses are investigated and compared with previously reported sub-microsecond experiments. Current and voltage waveforms, streak camera shadow imaging, and one-dimensional hydrodynamic simulations are employed to characterize how the energy density, energy density [...] Read more.

Underwater electrical explosions of single metallic wires driven by microsecond current pulses are investigated and compared with previously reported sub-microsecond experiments. Current and voltage waveforms, streak camera shadow imaging, and one-dimensional hydrodynamic simulations are employed to characterize how the energy density, energy density deposition rate, and the generated shock waves in water depend on the wire parameters. It was found that, similar to the sub-microsecond timescale, the solid–liquid phase transition occurs later than thermodynamic calculations predicted, while the liquid–vapor phase transition happens sooner than expected, leading to a two-phase coexistence. Additionally, most materials show a notable resistance peak (Ti, Fe, Ni, Zn, Ag, Sn, Ta, Au) compared to a quasi-plateau for Cu and Mo or a continuous increase for Al and Pt. Moreover, the specific action integral values are significantly smaller than those observed in wire explosion experiments in vacuum. Finally, the plasma formed at peak resistive voltage is non-ideal but exhibits lower electron density, ionization degree, and temperature compared to the sub-microsecond case. Full article

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9 pages, 1392 KB

Open AccessArticle

An Atmospheric Plasma Jet Generator Driven by a Current Source

by Ovidiu S. Stoican

Plasma 2026, 9(1), 6; https://doi.org/10.3390/plasma9010006 - 10 Feb 2026

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Abstract

A novel system aiming to electrically supply various cold plasma generators is proposed. It operates as a programmable linear current source which is able to maintain a dc constant discharge current at various discharge voltages required to sustain the plasma jet. Its design [...] Read more.

A novel system aiming to electrically supply various cold plasma generators is proposed. It operates as a programmable linear current source which is able to maintain a dc constant discharge current at various discharge voltages required to sustain the plasma jet. Its design is based on a specific electronic device called a switchable current regulator, which considerably simplifies the circuit topology. Experimental results carried out in real operating conditions confirm the practical purpose of the proposed solution. Full article

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

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14 pages, 3655 KB

Open AccessArticle

Pin-Plane Electrical Discharge Driven by a MOSFET DC Current Source

by Myles Perry, Sidmar Holoman, Daniel Wozniak and Shirshak Kumar Dhali

Plasma 2026, 9(1), 5; https://doi.org/10.3390/plasma9010005 - 3 Feb 2026

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Abstract

The generation of atmospheric pressure nonequilibrium plasma using electrical discharges is an active area of research due to its significance in a wide spectrum of applications including medicine, combustion, and manufacturing. In our attempt to create a helium plasma jet in a pin-plane [...] Read more.

The generation of atmospheric pressure nonequilibrium plasma using electrical discharges is an active area of research due to its significance in a wide spectrum of applications including medicine, combustion, and manufacturing. In our attempt to create a helium plasma jet in a pin-plane discharge with a constant current source, we observed self-pulsating behavior. We present the results of the electrical, optical, and spectroscopic measurements carried out to characterize the discharge. The duration of the discharge is a few tens of nanoseconds, and the repetition rate is in the few tens of kHz. The effect of the gap distance and gas flow is discussed. The effective capacitance formed by the space charge in the discharge region plays an important role in determining the pulsing frequency. The results of voltage swing, current pulse, and light emission are also discussed. Such self-pulsating discharges can be used to produce helium plasmas under ambient conditions in applications such as plasma medicine. Full article

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

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21 pages, 9238 KB

Open AccessArticle

Effect of Dielectric Thickness on Filamentary Mode Nanosecond-Pulse Dielectric Barrier Discharge at Low Pressure

by Anbang Sun, Yulin Guo, Yanru Li and Yifei Zhu

Plasma 2026, 9(1), 4; https://doi.org/10.3390/plasma9010004 - 27 Jan 2026

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Abstract

Filamentary mode, as a common phenomenon that appears in dielectric barrier discharge (DBD), is realized by rod-to-rod electrodes in N₂-O₂ mixtures at 80 mbar. The effects of the dielectric thickness on the characteristics of filamentary DBD are investigated through experiments [...] Read more.

Filamentary mode, as a common phenomenon that appears in dielectric barrier discharge (DBD), is realized by rod-to-rod electrodes in N₂-O₂ mixtures at 80 mbar. The effects of the dielectric thickness on the characteristics of filamentary DBD are investigated through experiments and simulations. The discharges are driven by a positive unipolar nanosecond pulse voltage with 15.8 kV amplitude, 9 ns rise time (T_r^10–90%), and 14 ns pulse width. The characteristics of filamentary DBD are recorded with an intensified charge-coupled device and a Pearson current probe in the experiment, and a 2D axisymmetric fluid mode is established to analyze the discharge. Surface discharges occur on the anode and cathode dielectric after the breakdown, and the discharge is gradually extinguished as the applied voltage decreases. A thinner total dielectric thickness (D_a + D_c) leads to larger currents, stronger discharges, and wider discharge channels. These characteristics are consistent when the total dielectric thickness is the same but anode dielectric thickness and cathode dielectric thickness are different (D_a ≠ D_c ≠ 0). If the anode is a metal electrode (D_a = 0), the current will be substantially large, and two discharge modes are observed: stable mono-filament discharge mode and random multi-filament discharge mode. It is found in simulations that the dielectric thickness changes the electric field configuration. The electric field is stronger with the decrease in dielectric thickness and leads to a more intense ionization which is responsible for most of the observed effects. Full article

(This article belongs to the Special Issue Recent Advances of Dielectric Barrier Discharges)

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9 pages, 1047 KB

Open AccessArticle

Plasma-Polymerized Polystyrene Coatings for Hydrophobic and Thermally Stable Cotton Textiles

by Lian Farhadian, Samira Amiri Khoshkar Vandani and Hai-Feng Ji

Plasma 2026, 9(1), 3; https://doi.org/10.3390/plasma9010003 - 31 Dec 2025

Viewed by 806

Abstract

Dielectric barrier discharge (DBD) plasma provides a solvent-free and energy-efficient approach for the in situ polymerization of styrene on cotton textiles. Traditional methods for polystyrene (PS) coating often require elevated temperatures, chemical initiators, or organic solvents, conditions that are incompatible with porous, heat-sensitive [...] Read more.

Dielectric barrier discharge (DBD) plasma provides a solvent-free and energy-efficient approach for the in situ polymerization of styrene on cotton textiles. Traditional methods for polystyrene (PS) coating often require elevated temperatures, chemical initiators, or organic solvents, conditions that are incompatible with porous, heat-sensitive substrates such as cotton. In this work, we demonstrate that DBD plasma can initiate and sustain styrene polymerization directly on cotton fibers under ambient conditions. FT-IR spectroscopy confirms the consumption of the vinyl C=C bond and the formation of atactic, amorphous polystyrene. Thermogravimetric analysis indicates that the cotton coated with DBD polymerized PS exhibits enhanced thermal stability compared to cotton coated with commercial PS. Additionally, UV aging tests confirm that the plasma-deposited coating maintains its hydrophobicity after exposure to light. Together, these findings highlight DBD plasma as a sustainable and effective approach for producing hydrophobic, thermally robust, and UV-stable textile coatings without the need for solvents, initiators, or harsh processing conditions. Full article

(This article belongs to the Special Issue Recent Advances of Dielectric Barrier Discharges)

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17 pages, 488 KB

Open AccessArticle

Empirical Atomic Data for Plasma Simulations

by Stephan Fritzsche, Houke Huang and Aloka Kumar Sahoo

Plasma 2026, 9(1), 2; https://doi.org/10.3390/plasma9010002 - 29 Dec 2025

Viewed by 939

Abstract

Recent advances in non-local thermodynamic equilibrium (non-LTE) plasma simulations, for example in modeling kilonova ejecta, have emphasized the need for consistent and reliable atomic data. Unlike LTE modeling, non-LTE calculations must include a consistent treatment of various photon-induced and collisional processes in order [...] Read more.

Recent advances in non-local thermodynamic equilibrium (non-LTE) plasma simulations, for example in modeling kilonova ejecta, have emphasized the need for consistent and reliable atomic data. Unlike LTE modeling, non-LTE calculations must include a consistent treatment of various photon-induced and collisional processes in order to describe realistic electron and photon distributions in the plasma. However, the available atomic data are often incomplete, inconsistently formatted, or even fail to indicate the main dependencies on the level structure and plasma parameters, thus limiting their practical use. To address these issues, we have extended Jac, the Jena Atomic Calculator (version v0.3.0), to provide direct access to relevant cross sections, plasma rates, and rate coefficients. Emphasis is placed on photoexcitation and ionization processes as well as their time-reversed counterparts—photo-de-excitation and photorecombination. Whereas most of these data are still based on empirical expressions, their dependence on the ionic level structure and plasma temperature is made explicit here. Moreover, the electron and photon distributions can be readily controlled and adjusted by the user. This transparent representation of atomic data for photon-mediated processes, together with a straightforward use, facilitates their integration into existing plasma codes and improves the interpretation of high-energy astrophysical phenomena. It may support also more accurate and flexible non-LTE plasma simulations. Full article

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

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19 pages, 777 KB

Open AccessArticle

Enhanced Quantum Dot Emission in Fibonacci Photonic Crystal Cavities Optimized for PECVD-Compatible Porous Silicon: A Computational Study

by J. E. Mastache-Mastache, M. C. González, H. Martínez and B. Reyes-Ramírez

Plasma 2026, 9(1), 1; https://doi.org/10.3390/plasma9010001 - 26 Dec 2025

Viewed by 925

Abstract

This computational study investigates the optical properties of a sixth-order Fibonacci quasi-periodic photonic crystal cavity designed for the infiltration of near-infrared colloidal quantum dots (QDs, e.g., InAs/ZnSe or PbS) and fully compatible with plasma-enhanced chemical vapor deposition (PECVD) using porous silicon layers. Using [...] Read more.

This computational study investigates the optical properties of a sixth-order Fibonacci quasi-periodic photonic crystal cavity designed for the infiltration of near-infrared colloidal quantum dots (QDs, e.g., InAs/ZnSe or PbS) and fully compatible with plasma-enhanced chemical vapor deposition (PECVD) using porous silicon layers. Using the transfer matrix method (TMM), we simulate transmission (T), reflection, absorption, electric field distributions and Purcell factors (F) for both TE and TM polarizations, incorporating the wavelength-dependent absorption of porous silicon. A multi-objective figure-of-merit is defined to simultaneously maximize transmission (

T > 95 %

at 800 nm) and the one-dimensional Purcell factor. The optimized structure (

P_{H} = 0416

) yields a quality factor

Q \approx 4300

, a 1D Purcell factor

F_{1 D} \approx 3.6

and a realistic 3D Purcell enhancement estimated between 4 and 8 (under lateral confinement assumptions). This conservative estimate, derived via the effective index method to account for 3D effects, aligns with the detailed discussion within the article and is lower than the ideal upper bound of the 1D model. The integrated emission enhancement is approximately 3.0-fold. Monte Carlo simulations demonstrate remarkable robustness to fabrication tolerances (

\pm 10

nm thickness variations result in a <5% reduction in transmission), highlighting the structure’s scalability for PECVD-based processing. Comparison with periodic Bragg structures reveals superior angular stability and disorder tolerance in the Fibonacci design, positioning it as a promising platform for robust QD-based light sources and integrated refractive index sensors. Full article

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Plasma, Volume 9, Issue 1 (March 2026) – 8 articles

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