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Plasma
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Open Access journal
ISSN (Online) 2571-6182
Published by MDPI

[84 journals]

Plasma, Vol. 5, Pages 184-195: Features of Pinch Plasma, Electron, and Ion
Beams That Originated in the AECS PF-1 Plasma Focus Device
- Authors: Mohamad Akel, Sharif AL-Hawat, Muthanna Ahmad, Yamen Ballul, Soliman Shaaban
  First page: 184
  Abstract: The measured current traces of alow energy AECS PF-1 plasma focus device are used for studying of the formed plasma, and the produced ion and electron beams. Anadapted version of the Lee model (RADPFV5.15FIB&REB) is applied, taking into account the fitting procedures between the measured and computed current waveforms for each shot. The experiments on AECSPF-1 were performed with three different gases—helium, nitrogen, and argon—for studying the effect of the atomic number on the properties of the generated beams. For numerical experiments using the Lee model, 36 successful shots for each gas were selected. The peak values of the total discharge current Ipeak were 50–55 kA, the pinch currents Ipinchwere34–36 kA, and the final pinch radius reached a minimum value of 0.03 cm for argon. The ion mean energy ranged from 35 keV (for He) to 223 keV (for Ar). The beam energy also had an extreme value of 1.34 J (0.05%E0) for argon. The results presented the highest values of 2.4 × 1014Wm−2 for the power flow density, and adamage factor of around 3.1 × 1010 Wm−2s0.5 for argon. For electron beams, the results also showed that the fluence and flux increased with the higher atomic number and reached a peak of 9.7 × 1022 m−2 and 5.9 × 1030 m−2 s−1 for argon, respectively. The results presented the highest values of 2.2 × 1016Wm−2 for the power flow density (heat flux), and adamage factor of around 3 × 1012 Wm−2s0.5 for argon. The kinetic energy of the relativistic electrons was found to be within the range of 18–23 keV. The results show that the ion and electron beam properties (energy, flux, fluence, ion and electron numbers, current, power flow density, and damage factor) emitted from the plasma focus had wide ranges based on the operational plasma focus parameters. Thus, these results could be used for selection of the suitable plasma focus parameters for desired material processing applications.
  Citation: Plasma
  PubDate: 2022-03-25
  DOI: 10.3390/plasma5020014
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 196-205: Poly (O-Aminophenol) Produced by Plasma
Polymerization Has IR Spectrum Consistent with a Mixture of Quinoid &
Keto Structures
- Authors: Natalie M. Stuart, Karl Sohlberg
  First page: 196
  Abstract: A vibrational analysis of various poly(o-aminophenol) structures has been undertaken using first principles methods. It is shown that a mixture of quinoid and keto forms of poly(o-aminophenol) gives rise to a simulated spectrum that replicates the experimental infrared spectra of plasma-produced poly(o-aminophenol) better than either the quinoid or keto poly(o-aminophenol) spectra alone. An unassigned peak in the spectrum is attributed to hydrogen bonding to the silica substrate.
  Citation: Plasma
  PubDate: 2022-04-14
  DOI: 10.3390/plasma5020015
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 206-220: Diagnostics of Air Purification Plasma
Device by Spatially Resolved Emission Spectroscopy
- Authors: Wanxia Zhao, Zeyad T. Alwahabi
  First page: 206
  Abstract: A non-thermal plasma, air purification device (PlasmaShield®, MD250, Keswick, SA, Australia), was investigated using spatially resolved optical emission spectroscopy. The emission spectra were measured with two spatial dimensions to analyze and identify the transition lines of excited NO–γ (A2Σ–X2Π), N2 (C3Π–B3Π), and N2+ (B2Σ–X2Σ) systems. The N2 emission band at 337 and 316 nm were used to determine the spatially resolved vibrational temperature of N2 molecules, TvibN2. It was found that the average N2 vibrational temperatures in the x and y directions are almost the same. Two key operating parameters, supplied power and air flow, influence the N2 vibrational temperature. The results demonstrate that applying higher supplied power increases the vibrational temperature, while changes in air flow velocity do not affect the vibrational temperature values. The phenomenological plasma temperature (PPT) was also estimated from the N2 vibrational temperature. It was observed that PlasmaShield® generates excited N2 and NO only within a narrow region around the discharge electrode tip (with peak intensity below 100 µm from the tip). The study also shows no presence of excited OH*, O*, and other radicals.
  Citation: Plasma
  PubDate: 2022-04-26
  DOI: 10.3390/plasma5020016
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 221-232: ElectroCatalytic Activity of Nickel Foam
with Co, Mo, and Ni Phosphide Nanostructures
- Authors: Morteza Saghafi Yazdi, Mohammad Rezayat, Joan Josep Roa Rovira
  First page: 221
  Abstract: In this study, the electrocatalytic activity of nickel foam, which is activated by cobalt, molybdenum, and nickel phosphide nanostructures, is prepared by the plasma hydrothermal method for use in the release of hydrogen and oxygen. The morphology and crystallographic structure of the synthesized phosphide specimens were examined by means of scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. Moreover, the electrolysis activity for these sets of specimens was investigated using the Tafel polarization curve or linear sweep voltammetry, cyclic voltammetry, as well as by means of the electrochemical impedance spectroscopy technique. Preliminary results show that nickel phosphide presents the highest electrocatalytic activity than the other phosphides developed in this research. In this regard, it presents an electrocatalytic activity to release hydrogen and oxygen of around −1.7 and 0.82 mV, which is measured at a current density of 100 mA·cm−2, respectively.
  Citation: Plasma
  PubDate: 2022-04-27
  DOI: 10.3390/plasma5020017
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 233-246: Oxidative Stress Pathways Linked to
Apoptosis Induction by Low-Temperature Plasma Jet Activated Media in
Bladder Cancer Cells: An In Vitro and In Vivo Study
- Authors: Hideo Fukuhara, Endre J. Szili, Jun-Seok Oh, Kawada Chiaki, Shinkuro Yamamoto, Atsushi Kurabayashi, Mutsuo Furihata, Masayuki Tsuda, Hiroshi Furuta, Howard D. Lindsay, Robert D. Short, Akimitsu Hatta, Keiji Inoue
  First page: 233
  Abstract: Current methods used to treat non-muscle invasive bladder cancer are inadequate due to a high recurrence rate after surgery and the occurrence of adverse events such as interstitial pneumonia following intravesical instillation therapy. Low-temperature plasma is a new form of physical therapy that provides a rich source of reactive oxygen species (ROS). Oxidative solutions, created by pre-treatment of aqueous media with plasma before application to target cells, lead to the destruction of cancer cells through oxidative stress pathways. This study focuses on the effects of plasma-activated media (PAM) in bladder cancer cells. PAM treatment increases oxidative stress that leads to cell cycle arrest and concomitantly depolarises the mitochondrial membrane leading to increased mitochondrial ROS production. Cell cycle arrest and increased mitochondrial ROS production led to an increase in caspase 3/cytochrome c activity, which might explain the induction of apoptosis in bladder cancer cells in vitro and in a bladder cancer tumour in vivo. These observations highlight the potential of plasma activated solutions as a new adjuvant therapy in the clinical treatment of bladder cancer.
  Citation: Plasma
  PubDate: 2022-04-27
  DOI: 10.3390/plasma5020018
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 247-257: Pulsed Spherical Tokamak—A New
Approach to Fusion Reactors
- Authors: Mikhail Gryaznevich, Valery A. Chuyanov, Yuichi Takase
  First page: 247
  Abstract: Traditionally, spherical tokamak (ST) reactors are considered to operate in a steady state. This paper analyses the advantages of a pulsed ST reactor. The methodology developed for conventional tokamak (CT) reactors is used and it is shown that advantages of a pulsed operation are even more pronounced in an ST reactor because of its ability to operate at a higher beta, therefore achieving a higher bootstrap current fraction, which, together with a lower inductance, reduces requirements for magnetic flux from the central solenoid for the plasma current ramp-up and sustainment.
  Citation: Plasma
  PubDate: 2022-05-18
  DOI: 10.3390/plasma5020019
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 258-264: Characteristics of a Source for Oxide
Coating Deposition by the Electron-Beam Evaporation of Dielectric
Materials
- Authors: Viktor Burdovitsin, Ilya Bakeev, Kirill Karpov, Lionel Ngon A. Kiki, Efim Oks, Alexey Vizir
  First page: 258
  Abstract: We describe our investigations of a plasma-cathode electron source designed for the deposition of oxide coatings by the electron-beam evaporation of dielectric materials. Tests carried out using oxygen as the working gas showed that the source is operable without a change in parameters for at least ten hours of continuous operation. The current–voltage characteristics of the hollow-cathode plasma source in oxygen displayed a monotonically increasing character, and the voltage dependence of the discharge current was exponential. At the same time, for argon, nitrogen, and helium, the discharge voltage remained unchanged over a current ranging from 0.1 A to 1 A. A possible reason for these differences is the formation of oxides on the electrode surfaces for operation in the oxygen, impeding the discharge operation and requiring higher voltages for the same current as the other gases. The dependencies of the electron beam current on the accelerating voltage were monotonically increasing curves for all the gases except for helium, for which the beam current remained unchanged with increasing voltage over a range from two to ten kilovolts.
  Citation: Plasma
  PubDate: 2022-05-25
  DOI: 10.3390/plasma5020020
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 265-279: Indigo Carmine Degradation in Water Induced
by a Pulsed Positive Corona Discharge in Air: Discharge and Postdischarge
Effects
- Authors: Matías G. Ferreyra, Brenda L. Fina, Natalio J. Milardovich, Juan C. Chamorro, Brenda Santamaría, Karina Balestrasse, Leandro Prevosto
  First page: 265
  Abstract: In recent years, one of the fastest growing technological applications in the field of nonthermal plasmas is the degradation of organic contaminants of water. In this work, the degradation of indigo carmine (IC) in water induced by a pulsed positive corona discharge operating in ambient air is reported. Degradation levels in different volumes of IC in solution with distilled water treated with different plasma exposure times immediately after discharge (0 h), and in the postdischarge up to 24 h were examined. To explain the IC discoloration in the postdischarge phase, a chemical model was developed. The stability of the reactive species in solution nitrate (NO3−), nitrite (NO2−) and hydrogen peroxide (H2O2), as well as the properties of the solution (electrical conductivity, pH) were also measured. The results suggest that the hydroxyl radical (OH˙) as well as ozone (O3) are the main oxidizing species during the discharge phase, being primarily formed in the gas phase through plasma-mediated reactions and then transferred to the liquid by diffusion, while the OH˙ production in the bulk liquid through the decomposition of peroxinitrous acid (O=NOOH) plays a major role in the IC degradation during the postdischarge. These results are associated with a noticeably increase in the energy-yield values observed at 24 h post-treatment.
  Citation: Plasma
  PubDate: 2022-05-30
  DOI: 10.3390/plasma5020021
  Issue No: Vol. 5, No. 2 (2022)
Plasma, Vol. 5, Pages 30-43: The Effect of Excited Species on the
Collisional Energy of Argon Inductively Coupled Plasmas: A Global Model
Study
- Authors: Júlia Karnopp, Bernardo Magaldi, Julio Sagás, Rodrigo Pessoa
  First page: 30
  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 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.
  Citation: Plasma
  PubDate: 2022-01-04
  DOI: 10.3390/plasma5010003
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 44-59: Plasma Co-Polymerization of HMDSO and
Limonene with an Atmospheric Pressure Plasma Jet
- Authors: Gerrit Wulf, Bernd Mayer, Uwe Lommatzsch
  First page: 44
  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 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.
  Citation: Plasma
  PubDate: 2022-01-04
  DOI: 10.3390/plasma5010004
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 60-73: 3D-Modulational Stability of Envelope Soliton
in a Quantum Electron–Ion Plasma—A Generalised Nonlinear
Schrödinger Equation
- Authors: Shatadru Chaudhuri, Asesh Roy Chowdhury, Basudev Ghosh
  First page: 60
  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 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.
  Citation: Plasma
  PubDate: 2022-01-17
  DOI: 10.3390/plasma5010005
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 74: Acknowledgment to Reviewers of Plasma in 2021
- Authors: Plasma Editorial Office Plasma Editorial Office
  First page: 74
  Abstract: Rigorous peer-reviews are the basis of high-quality academic publishing [...]
  Citation: Plasma
  PubDate: 2022-01-29
  DOI: 10.3390/plasma5010006
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 75-97: Experimental Study of a Nonthermal DBD-Driven
Plasma Jet System Using Different Supply Methods
- Authors: Anton Ivankov, Tony Capela, Vanesa Rueda, Eric Bru, Hubert Piquet, Dmitry Schitz, David Florez, Rafael Diez
  First page: 75
  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 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.
  Citation: Plasma
  PubDate: 2022-02-01
  DOI: 10.3390/plasma5010007
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 98-110: Improving Seed Germination by Cold
Atmospheric Plasma
- Authors: Dayun Yan, Li Lin, Michelle Zvansky, Leat Kohanzadeh, Shannon Taban, Sabrina Chriqui, Michael Keidar
  First page: 98
  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. 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.
  Citation: Plasma
  PubDate: 2022-02-09
  DOI: 10.3390/plasma5010008
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 111-129: Application of Nitrogen Piezoelectric
Direct Discharge for Increase in Surface Free Energy of Polymers
- Authors: Dariusz Korzec, Florian Hoppenthaler, Thomas Andres, Sophia Guentner, Simona Lerach
  First page: 111
  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 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.
  Citation: Plasma
  PubDate: 2022-02-09
  DOI: 10.3390/plasma5010009
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 130-145: Effect of Electrode Profile and Polarity on
Performance of Pressurized Sparkgap Switch
- Authors: Vinod Kumar Gandi, Rishi Verma, Manoj Warrier, Archana Sharma
  First page: 130
  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 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.
  Citation: Plasma
  PubDate: 2022-02-13
  DOI: 10.3390/plasma5010010
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 146-153: Bulk Polymerization of PEGDA in Spruce Wood
Using a DBD Plasma-Initiated Process to Improve the Flexural Strength of
the Wood–Polymer Composite
- Authors: Matthew Mieles, Callie Stitt, Hai-Feng Ji
  First page: 146
  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 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.
  Citation: Plasma
  PubDate: 2022-02-28
  DOI: 10.3390/plasma5010011
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 154-175: Adaptive Algorithm for the Generation of
Superconfigurations in Hot-Plasma Opacity Calculations
- Authors: Jean-Christophe Pain
  First page: 154
  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 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.
  Citation: Plasma
  PubDate: 2022-03-04
  DOI: 10.3390/plasma5010012
  Issue No: Vol. 5, No. 1 (2022)
Plasma, Vol. 5, Pages 176-183: Enhancement of Nuclear Fusion in Plasma
Oscillation Systems
- Authors: Alfred YiuFai Wong, Chun-Ching Shih
  First page: 176
  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 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.
  Citation: Plasma
  PubDate: 2022-03-17
  DOI: 10.3390/plasma5010013
  Issue No: Vol. 5, No. 1 (2022)