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Plasma, Volume 5, Issue 1 (March 2022) – 13 articles

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8 pages, 791 KiB  
Article
Enhancement of Nuclear Fusion in Plasma Oscillation Systems
by Alfred YiuFai Wong and Chun-Ching Shih
Plasma 2022, 5(1), 176-183; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010013 - 17 Mar 2022
Cited by 2 | Viewed by 3023
Abstract
Concepts of dynamic oscillations of positive and negative ions to enhance fusion reactions are examined in this paper. Collective oscillations of positive and negative ions produce large oscillating electrostatic fields and could provide a significant reduction of the Coulomb potential barrier between the [...] Read more.
Concepts of dynamic oscillations of positive and negative ions to enhance fusion reactions are examined in this paper. Collective oscillations of positive and negative ions produce large oscillating electrostatic fields and could provide a significant reduction of the Coulomb potential barrier between the two interacting species (such as hydrogen anion H− and B+ in the hydrogen-boron fusion reaction). The negative hydrogen ions can be produced by populating low-temperature electrons around the neutral hydrogen atoms in a rotation chamber. The existence of H− ensures the stability of the plasma and the effectiveness of fusion interactions between H− and B+. In this paper, theoretical analyses of such oscillations systems will be presented and the conditions for fusion enhancement are discussed. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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22 pages, 544 KiB  
Article
Adaptive Algorithm for the Generation of Superconfigurations in Hot-Plasma Opacity Calculations
by Jean-Christophe Pain
Plasma 2022, 5(1), 154-175; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010012 - 04 Mar 2022
Cited by 4 | Viewed by 2309
Abstract
In hot plasmas, such as the ones encountered in astrophysics or laser-fusion studies, the number of ionic excited states may become huge, and the relevant electron configurations cannot always be handled individually. The Super Transition Array approach enables one to calculate the massic [...] Read more.
In hot plasmas, such as the ones encountered in astrophysics or laser-fusion studies, the number of ionic excited states may become huge, and the relevant electron configurations cannot always be handled individually. The Super Transition Array approach enables one to calculate the massic photo-absorption cross-section (or radiative opacity) in a statistical manner consisting of grouping configurations close in energy into superconfigurations. One of the main issues of the method, beyond its spectral resolution, is the determination of the most relevant configurations that contribute to opacity. In this work, we discuss different aspects of the generation of superconfigurations in a hot plasma and propose a new adaptive algorithm. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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8 pages, 1332 KiB  
Article
Bulk Polymerization of PEGDA in Spruce Wood Using a DBD Plasma-Initiated Process to Improve the Flexural Strength of the Wood–Polymer Composite
by Matthew Mieles, Callie Stitt and Hai-Feng Ji
Plasma 2022, 5(1), 146-153; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010011 - 28 Feb 2022
Cited by 1 | Viewed by 2442
Abstract
The chemical treatment of wood has been shown to increase its mechanical strength by forming composites with a variety of polymers. Polyethylene glycol diacrylate (PEGDA) has commonly been used as a polymer reinforcement to increase the strength and resistance of spruce wood for [...] Read more.
The chemical treatment of wood has been shown to increase its mechanical strength by forming composites with a variety of polymers. Polyethylene glycol diacrylate (PEGDA) has commonly been used as a polymer reinforcement to increase the strength and resistance of spruce wood for various applications, such as protection from weathering. In this study, PEGDA was impregnated into wood samples and polymerized by dielectric barrier discharge (DBD) plasma to form wood–polymer composites (WPCs). The kinetic rate order of PEGDA was explored using FT-IR quantitative analysis and the DBD plasma-initiated polymerization was determined to be second order. The strength of the wood samples was then determined by a three-point flexural test. The PEGDA-treated spruce wood samples showed improved flexural strength versus the untreated wood samples. The WPCs were also made using a UV treatment method and were then compared to the DBD plasma-treated samples. The results showed that the DBD plasma-treated samples yielded superior flexural strength relative to the UV-treated samples. We accredited this difference in strength to the plasma process and its ability to penetrate into the various layers of the wood and initiate polymerization, as opposed to UV light that can only penetrate superficially, initiating polymerization in only the first few layers of the wood surface. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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16 pages, 6043 KiB  
Article
Effect of Electrode Profile and Polarity on Performance of Pressurized Sparkgap Switch
by Vinod Kumar Gandi, Rishi Verma, Manoj Warrier and Archana Sharma
Plasma 2022, 5(1), 130-145; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010010 - 13 Feb 2022
Cited by 4 | Viewed by 3742
Abstract
Sparkgap are most widely used closing switches in various high-voltage pulsed power systems and its reliable operation at desired voltage level is very essential. Conventionally by adjusting the filling gas pressure inside sparkgap switch, breakdown voltage level is altered but switching characteristics such [...] Read more.
Sparkgap are most widely used closing switches in various high-voltage pulsed power systems and its reliable operation at desired voltage level is very essential. Conventionally by adjusting the filling gas pressure inside sparkgap switch, breakdown voltage level is altered but switching characteristics such as stability in hold-off voltage at various pressures, breakdown delay, plasma channel formation, and erosion rate are mainly dictated by adopted electrode profile and its dimensions, inter-electrode gap length and polarity. In this paper, experimental results obtained on breakdown characteristics of four different electrode geometries—Plane Parallel, Hemi-spherical, Bruce, and Rogowski and also a generalized criterion for fixing major dimensions of electrode and inter-gap length to ensure uniform electric field in the inter-electrode region are reported. All electrodes are of brass material and have common radius and thickness of 25 mm and 18 mm, respectively (surface finish <1 µm). Experiments performed on various electrode profiles in gap lengths of 2 mm to 5 mm range with pure nitrogen (N2) gas pressurization up to 50 psi reveal that among all profiles, Rogowski performs most reliably having stable hold-off voltage in wide operating range. Hold-off voltage magnitude and breakdown delay was commonly obtained higher for negative polarity in all trials. A comprehensive overview of experimental investigation reported herein compares suitability of various electrode profiles and polarity for reliable switching. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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19 pages, 8889 KiB  
Article
Application of Nitrogen Piezoelectric Direct Discharge for Increase in Surface Free Energy of Polymers
by Dariusz Korzec, Florian Hoppenthaler, Thomas Andres, Sophia Guentner and Simona Lerach
Plasma 2022, 5(1), 111-129; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010009 - 09 Feb 2022
Cited by 4 | Viewed by 2651
Abstract
The subject of this study is the application of the piezoelectric direct discharge (PDD) operated with nitrogen to control the surface free energy (SFE) of polymers. The activation area, defined as the area of the zone reaching the SFE of 58 mN/m for [...] Read more.
The subject of this study is the application of the piezoelectric direct discharge (PDD) operated with nitrogen to control the surface free energy (SFE) of polymers. The activation area, defined as the area of the zone reaching the SFE of 58 mN/m for high-density polyethylene (HDPE) and poly (methyl methacrylate) (PMMA), is characterized. For HDPE, the activation area was characterized as a function of the distance from 1 to 16 mm, the nitrogen flow from 5 to 20 SLM, and the treatment time from 1 to 32 s. For larger distances, where SFE does not exceed 58 mN/m, the water contact angle is evaluated. The activation area for nitrogen PDD is typically a factor of 3 higher than for air with all other conditions the same. A maximum static activation area of 15 cm2 is reached. The plasma treatment of lens panels made of PMMA is presented as application example. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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14 pages, 4437 KiB  
Review
Improving Seed Germination by Cold Atmospheric Plasma
by Dayun Yan, Li Lin, Michelle Zvansky, Leat Kohanzadeh, Shannon Taban, Sabrina Chriqui and Michael Keidar
Plasma 2022, 5(1), 98-110; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010008 - 09 Feb 2022
Cited by 13 | Viewed by 5697
Abstract
Cold atmospheric plasma (CAP) is a tunable source of reactive species and other physical factors. It exerts luxuriant biochemical effects on diverse cells, including bacterial cells, mammalian cells, and plant cells. Over the past decade, CAP has shown promising application in modern agriculture. [...] Read more.
Cold atmospheric plasma (CAP) is a tunable source of reactive species and other physical factors. It exerts luxuriant biochemical effects on diverse cells, including bacterial cells, mammalian cells, and plant cells. Over the past decade, CAP has shown promising application in modern agriculture. Here, we focused on the state of the art of plasma agriculture, particularly the improvement of seed germination rates. Typical plasma sources, underlying physical principles, and the chemical and cellular mechanism of plasma’s effect on plants seeds have been discussed in depth. Full article
(This article belongs to the Special Issue Dielectric Barrier Discharges)
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23 pages, 46600 KiB  
Article
Experimental Study of a Nonthermal DBD-Driven Plasma Jet System Using Different Supply Methods
by Anton Ivankov, Tony Capela, Vanesa Rueda, Eric Bru, Hubert Piquet, Dmitry Schitz, David Florez and Rafael Diez
Plasma 2022, 5(1), 75-97; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010007 - 01 Feb 2022
Cited by 10 | Viewed by 5606
Abstract
This article presents an experimental study of a DBD-driven plasma jet system. The aim of the study is to design a whole system (the jet reactor, its electrical power supply, and a gas-feeding apparatus) suitable for biomedical applications. The article describes the test [...] Read more.
This article presents an experimental study of a DBD-driven plasma jet system. The aim of the study is to design a whole system (the jet reactor, its electrical power supply, and a gas-feeding apparatus) suitable for biomedical applications. The article describes the test bench developed for this purpose and discusses the parameters it controls. The measurements show that the studied solutions can be used to control critical parameters such as the jet temperature and dimensions. The best results were obtained for a bipolar short-pulse voltage power supply in the 10–20 kHz frequency range and for a series resonant inverter current power supply operated in “burst mode”, allowing low-frequency modulation. Full article
(This article belongs to the Special Issue Plasma Biology)
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1 pages, 192 KiB  
Editorial
Acknowledgment to Reviewers of Plasma in 2021
by Plasma Editorial Office
Plasma 2022, 5(1), 74; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010006 - 29 Jan 2022
Viewed by 1784
Abstract
Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article
14 pages, 1132 KiB  
Article
3D-Modulational Stability of Envelope Soliton in a Quantum Electron–Ion Plasma—A Generalised Nonlinear Schrödinger Equation
by Shatadru Chaudhuri, Asesh Roy Chowdhury and Basudev Ghosh
Plasma 2022, 5(1), 60-73; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010005 - 17 Jan 2022
Cited by 1 | Viewed by 2166
Abstract
In physical reality, the phenomena of plasma physics is actually a three-dimensional one. On the other hand, a vast majority of theoretical studies only analyze a one-dimensional prototype of the situation. So, in this communication, we tried to treat the quantum electron–ion plasma [...] Read more.
In physical reality, the phenomena of plasma physics is actually a three-dimensional one. On the other hand, a vast majority of theoretical studies only analyze a one-dimensional prototype of the situation. So, in this communication, we tried to treat the quantum electron–ion plasma in a full 3D setup and the modulational stability of envelope soliton was studied in a quantum electron–ion plasma in three dimensions. The Krylov–Bogoliubov–Mitropolsky method was applied to the three-dimensional plasma governing equations. A generalized form of the nonlinear Schrödinger (NLS) equation was obtained, whose dispersive term had a tensorial character, which resulted in the anisotropic behavior of the wave propagation even in absence of a magnetic field. The stability condition was deduced ab initio and the stability zones were plotted as a function of plasma parameters. The modulational stability of such a three-dimensional NLS equation was then studied as a function of plasma parameters. It is interesting to note that the nonlinear excitation of soliton took place again here due to the balance of nonlinearity and dispersion. The zones of contour plots are given in detail. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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16 pages, 2998 KiB  
Article
Plasma Co-Polymerization of HMDSO and Limonene with an Atmospheric Pressure Plasma Jet
by Gerrit Wulf, Bernd Mayer and Uwe Lommatzsch
Plasma 2022, 5(1), 44-59; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010004 - 04 Jan 2022
Cited by 6 | Viewed by 3042
Abstract
Plasma co-polymers (co-p) were deposited with an atmospheric pressure plasma jet (APPJ) using a precursor mixture containing hexamethyldisiloxane (HMDSO) and limonene. A coating with fragments from both precursors and with siloxane, carbonyl and nitrogen functional groups was deposited. The flow rate of limonene [...] Read more.
Plasma co-polymers (co-p) were deposited with an atmospheric pressure plasma jet (APPJ) using a precursor mixture containing hexamethyldisiloxane (HMDSO) and limonene. A coating with fragments from both precursors and with siloxane, carbonyl and nitrogen functional groups was deposited. The flow rate of limonene was found to be an important parameter for plasma co-polymerization to tune the formation and structure of the functional groups. The FTIR and XPS analysis indicates that with increasing flow rate of limonene a higher proportion of carbon is bound to silicon. This is related to a stronger incorporation of fragments from limonene into the siloxane network and a weaker fragmentation of HMDSO. The formation mechanism of the nitroxide and carboxyl groups can be mainly differentiated into in-plasma and post-plasma reactions, respectively. Full article
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14 pages, 2015 KiB  
Article
The Effect of Excited Species on the Collisional Energy of Argon Inductively Coupled Plasmas: A Global Model Study
by Júlia Karnopp, Bernardo Magaldi, Julio Sagás and Rodrigo Pessoa
Plasma 2022, 5(1), 30-43; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010003 - 04 Jan 2022
Cited by 2 | Viewed by 3713
Abstract
Global modeling of inductively coupled plasma (ICP) reactors is a powerful tool to investigate plasma parameters. In this article, the argon ICP global model is revisited to explore the effect of excited species on collisional energy through the study of different approaches to [...] Read more.
Global modeling of inductively coupled plasma (ICP) reactors is a powerful tool to investigate plasma parameters. In this article, the argon ICP global model is revisited to explore the effect of excited species on collisional energy through the study of different approaches to particle and energy balance equations. The collisional energy loss is much more sensitive to modifications in the balance equations than the electron temperature. According to the simulations, the multistep ionization reduces the collisional energy loss in all investigated reaction sets and the inclusion of heavy species reactions has negligible influence. The plasma parameters obtained, such as total energy loss and electron temperature, were compared with experimental results from the literature. The simulated cases that have more excited species and reactions in the energy balance are in better agreement with the experimental measurements. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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18 pages, 3883 KiB  
Article
The Nanosecond Impulsive Breakdown Characteristics of Air, N2 and CO2 in a Sub-mm Gap
by Ting Liu, Igor Timoshkin, Mark P. Wilson, Martin J. Given and Scott J. MacGregor
Plasma 2022, 5(1), 12-29; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010002 - 30 Dec 2021
Cited by 5 | Viewed by 2537
Abstract
The present paper investigates the breakdown characteristics—breakdown voltage, with breakdown occurring on the rising edge of the applied HV impulses, and time to breakdown—for gases of significance that are present in the atmosphere: air, N2 and CO2. These breakdown characteristics [...] Read more.
The present paper investigates the breakdown characteristics—breakdown voltage, with breakdown occurring on the rising edge of the applied HV impulses, and time to breakdown—for gases of significance that are present in the atmosphere: air, N2 and CO2. These breakdown characteristics have been obtained in a 100 µm gap between an HV needle and plane ground electrode, when stressed with sub-µs impulses of both polarities, with a rise time up to ~50 ns. The scaling relationships between the reduced breakdown field Etip/N and the product of the gas number density and inter-electrode gap, Nd, were obtained for all tested gases over a wide range of Nd values, from ~1020 m−2 to ~1025 m−2. The breakdown field-time to breakdown characteristics obtained at different gas pressures are presented as scaling relationships of Etip/N, Nd, and Ntbr for each gas, and compared with data from the literature. Full article
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11 pages, 515 KiB  
Article
Modulational Instability of Ion-Acoustic Waves in Pair-Ion Plasma
by Sharmin Jahan, Rubaiya Khondoker Shikha, Abdul Mannan and A A Mamun
Plasma 2022, 5(1), 1-11; https://0-doi-org.brum.beds.ac.uk/10.3390/plasma5010001 - 29 Dec 2021
Cited by 2 | Viewed by 2185
Abstract
The modulational instability (MI) of ion-acoustic waves (IAWs) is examined theoretically in a four-component plasma system containing inertialess electrons featuring a non-thermal, non-extensive distribution, iso-thermal positrons, and positively as well as negatively charged inertial ions. In this connection, a non-linear Schrödinger equation (NLSE), [...] Read more.
The modulational instability (MI) of ion-acoustic waves (IAWs) is examined theoretically in a four-component plasma system containing inertialess electrons featuring a non-thermal, non-extensive distribution, iso-thermal positrons, and positively as well as negatively charged inertial ions. In this connection, a non-linear Schrödinger equation (NLSE), which dominates the conditions for MI associated with IAWs, is obtained by using the reductive perturbation method. The numerical analysis of the NLSE reveals that the increment in non-thermality leads to a more unstable state, whereas the enhancement in non-extensivity introduces a less unstable state. It also signifies the bright (dark) ion-acoustic (IA) envelope solitons mode in the unstable (stable) domain. The conditions for MI and its growth rate in the unstable regime of the IAWs are vigorously modified by the different plasma parameters (viz., non-thermal, non-extensive q-distributed electron, iso-thermal positron, the ion charge state, the mass of the ion and positron, non-thermal parameter α, the temperature of electron and positron, etc.). Our findings may supplement and add to prior research in non-thermal, non-extensive electrons and iso-thermal positrons that can co-exist with positive as well as negative inertial ions. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences)
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