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plasma, Volume 1, Issue 1 (December 2018)

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Open AccessArticle Investigation of a Multiple-Timescale Turbulence-Transport Coupling Method in the Presence of Random Fluctuations
plasma 2018, 1(1), 126-143; https://doi.org/10.3390/plasma1010012 (registering DOI)
Received: 28 May 2018 / Revised: 5 July 2018 / Accepted: 10 July 2018 / Published: 12 July 2018
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Abstract
One route to improved predictive modeling of magnetically confined fusion reactors is to couple transport solvers with direct numerical simulations (DNS) of turbulence, rather than with surrogate models. An additional challenge presented by coupling directly with DNS is the inherent fluctuations in the
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One route to improved predictive modeling of magnetically confined fusion reactors is to couple transport solvers with direct numerical simulations (DNS) of turbulence, rather than with surrogate models. An additional challenge presented by coupling directly with DNS is the inherent fluctuations in the turbulence, which limit the convergence achievable in the transport solver. In this article, we investigate the performance of one numerical coupling method in the presence of turbulent fluctuations. To test a particular numerical coupling method for the transport solver, we use an autoregressive-moving-average model to generate stochastic fluctuations efficiently with statistical properties resembling those of a gyrokinetic simulation. These fluctuations are then added to a simple, solvable problem, and we examine the behavior of the coupling method. We find that monitoring the residual as a proxy for the error can be misleading. From a pragmatic point of view, this study aids us in the full problem of transport coupled to DNS by predicting the amount of averaging required to reduce the fluctuation error and obtain a specific level of accuracy. Full article
(This article belongs to the Special Issue Multiscale Methods in Plasma Physics)
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Open AccessArticle Possible Mechanism of Glucose Uptake Enhanced by Cold Atmospheric Plasma: Atomic Scale Simulations
plasma 2018, 1(1), 119-125; https://doi.org/10.3390/plasma1010011 (registering DOI)
Received: 9 May 2018 / Revised: 31 May 2018 / Accepted: 6 June 2018 / Published: 8 June 2018
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Abstract
Cold atmospheric plasma (CAP) has shown its potential in biomedical applications, such as wound healing, cancer treatment and bacterial disinfection. Recent experiments have provided evidence that CAP can also enhance the intracellular uptake of glucose molecules which is important in diabetes therapy. In
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Cold atmospheric plasma (CAP) has shown its potential in biomedical applications, such as wound healing, cancer treatment and bacterial disinfection. Recent experiments have provided evidence that CAP can also enhance the intracellular uptake of glucose molecules which is important in diabetes therapy. In this respect, it is essential to understand the underlying mechanisms of intracellular glucose uptake induced by CAP, which is still unclear. Hence, in this study we try to elucidate the possible mechanism of glucose uptake by cells by performing computer simulations. Specifically, we study the transport of glucose molecules through native and oxidized membranes. Our simulation results show that the free energy barrier for the permeation of glucose molecules across the membrane decreases upon increasing the degree of oxidized lipids in the membrane. This indicates that the glucose permeation rate into cells increases when the CAP oxidation level in the cell membrane is increased. Full article
(This article belongs to the Special Issue Plasma Medicine)
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Open AccessArticle Fully Kinetic Simulation of Ion-Temperature-Gradient Instabilities in Tokamaks
plasma 2018, 1(1), 105-118; https://doi.org/10.3390/plasma1010010 (registering DOI)
Received: 26 March 2018 / Revised: 20 May 2018 / Accepted: 29 May 2018 / Published: 31 May 2018
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Abstract
The feasibility of using full ion kinetics, instead of gyrokinetics, in simulating low-frequency Ion-Temperature-Gradient (ITG) instabilities in tokamaks has recently been demonstrated. The present work extends the full ion kinetics to the nonlinear regime and investigates the nonlinear saturation of a single-n
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The feasibility of using full ion kinetics, instead of gyrokinetics, in simulating low-frequency Ion-Temperature-Gradient (ITG) instabilities in tokamaks has recently been demonstrated. The present work extends the full ion kinetics to the nonlinear regime and investigates the nonlinear saturation of a single-n ITG instability due to the E × B trapping mechanism (n is the toroidal mode number). The saturation amplitude predicted by the E × B trapping theory is found to agree with the saturation level observed in the simulation. In extending to the nonlinear regime, we developed a toroidal Boris full orbit integrator, which proved to be accurate in capturing both the short-time scale cyclotron motion and long time scale drift motion, with good kinetic energy conservation and toroidal angular momentum conservation in tokamak equilibrium magnetic fields. This work also extends the previous work from analytic circular magnetic equilibria to general numerical magnetic equilibria, enabling simulation of realistic equilibria reconstructed from tokamak experiments. Full article
(This article belongs to the Special Issue Multiscale Methods in Plasma Physics)
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Open AccessArticle Improvement of the Multi-Hierarchy Simulation Model Based on the Real-Space Decomposition Method
plasma 2018, 1(1), 90-104; https://doi.org/10.3390/plasma1010009 (registering DOI)
Received: 1 March 2018 / Revised: 23 April 2018 / Accepted: 25 April 2018 / Published: 27 April 2018
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Abstract
Multi-hierarchy simulation models aimed at analysis of magnetic reconnection were developed. Based on the real-space decomposition method, the simulation domain consists of three parts: a magnetohydrodynamics (MHD) domain, a particle-in-cell (PIC) domain, and an interface domain to communicate MHD and PIC data. In
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Multi-hierarchy simulation models aimed at analysis of magnetic reconnection were developed. Based on the real-space decomposition method, the simulation domain consists of three parts: a magnetohydrodynamics (MHD) domain, a particle-in-cell (PIC) domain, and an interface domain to communicate MHD and PIC data. In this paper, the previous model (the 1D interlocking with the upstream condition) by the authors is improved to three types of new models, i.e., two types of the 1D interlocking with the downstream condition and one type of the 2D interlocking with the upstream condition. For their verification, simulations of plasma propagation across the multiple domains were performed in the multi-hierarchy models, and it was confirmed that the new interlocking methods are physically correct. Full article
(This article belongs to the Special Issue Multiscale Methods in Plasma Physics)
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Open AccessArticle An Inexpensive, Pulsed, and Multiple Wavelength Bench-Top Light Source for Biological Spectroscopy
plasma 2018, 1(1), 78-89; https://doi.org/10.3390/plasma1010008 (registering DOI)
Received: 6 April 2018 / Revised: 23 April 2018 / Accepted: 25 April 2018 / Published: 27 April 2018
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Abstract
Since signal/noise ratios are proportional to the square root of the intensity, high intensity light sources are advantageous for many forms of UV–Vis and IR spectroscopy particularly with very low or high absorbance samples. We report the construction of a low-cost (≈ £6500
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Since signal/noise ratios are proportional to the square root of the intensity, high intensity light sources are advantageous for many forms of UV–Vis and IR spectroscopy particularly with very low or high absorbance samples. We report the construction of a low-cost (≈ £6500 GBP, ca. 2016) bench-top spectrometer suitable for biological spectroscopy, which utilizes a hot plasma, generated with a pulsed Nd:YAG laser (λ = 1064 nm). The properties (reliability, intensity, and spectral profiles) of light generated with the plasma in different gaseous media (helium, neon, argon, and krypton) were investigated. Argon provided high intensity broadband light and was the most cost effective. The instrument was compared for spectral accuracy to a commercially available spectrometer (Thermo Scientific, GENESYS 10S) by measurement of the absorbance spectrum of the UV–Vis calibration standard holmium (III) oxide (4%, w/v) in perchloric acid (10%, w/v) and accurately replicated the results of the commercial spectrometer. This economical instrument can record consecutive absorbance spectra (between λ = 380 and 720 nm) for each laser pulse (6 Hz; ~160 ms/pulse), evinced by investigations into lysozyme aggregation in the presence of heparin. This instrument is suitable for use with lasers of a higher pulse power and repetition rates that would induce higher temperature plasmas. Higher temperature plasma sources offer increased signal to noise ratios due to the higher intensity emission generated. Full article
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Open AccessArticle The Role of Magnetic Islands in Collisionless Driven Reconnection: A Kinetic Approach to Multi-Scale Phenomena
plasma 2018, 1(1), 68-77; https://doi.org/10.3390/plasma1010007 (registering DOI)
Received: 13 February 2018 / Revised: 29 March 2018 / Accepted: 17 April 2018 / Published: 21 April 2018
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Abstract
The role of magnetic islands in collisionless driven reconnection has been investigated from the standpoint of a kinetic approach to multi-scale phenomena by means of two-dimensional particle-in-cell (PIC) simulation. There are two different types of the solutions in the evolution of the reconnection
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The role of magnetic islands in collisionless driven reconnection has been investigated from the standpoint of a kinetic approach to multi-scale phenomena by means of two-dimensional particle-in-cell (PIC) simulation. There are two different types of the solutions in the evolution of the reconnection system. One is a steady solution in which the system relaxes into a steady state, and no island is generated (the no-island case). The other is an intermittent solution in which the system does not reach a steady state, and magnetic islands are frequently generated in the current sheet (the multi-island case). It is found that the electromagnetic energy is more effectively transferred to the particle energy in the multi-island case compared with the no-island case. The transferred energy is stored inside the magnetic island in the form of the thermal energy through compressional heating, and is carried away together with the magnetic island from the reconnection region. These results suggest that the formation of a magnetic island chain may have a potential to bridge the energy gap between macroscopic and microscopic physics by widening the dissipation region and strengthening the energy dissipation rate. Full article
(This article belongs to the Special Issue Multiscale Methods in Plasma Physics)
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Open AccessArticle Microscopic Effect on Filamentary Coherent Structure Dynamics in Boundary Layer Plasmas
plasma 2018, 1(1), 61-67; https://doi.org/10.3390/plasma1010006 (registering DOI)
Received: 5 March 2018 / Revised: 19 March 2018 / Accepted: 19 March 2018 / Published: 22 March 2018
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Abstract
This study has demonstrated kinetic behaviors on the plasma filament propagation with the three-dimensional (3D) Particle-in-Cell (PIC) simulation. When the ion-to-electron temperature ratio Ti/Te is higher, the poloidal symmetry breaking in the filament propagation occurs. The poloidal symmetry breaking
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This study has demonstrated kinetic behaviors on the plasma filament propagation with the three-dimensional (3D) Particle-in-Cell (PIC) simulation. When the ion-to-electron temperature ratio T i / T e is higher, the poloidal symmetry breaking in the filament propagation occurs. The poloidal symmetry breaking is thought to be induced by the unbalanced potential structure that arises from the effect of the gyro motion of plasma particles. Full article
(This article belongs to the Special Issue Multiscale Methods in Plasma Physics)
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Open AccessReview Plasma Medicine: A Brief Introduction
plasma 2018, 1(1), 47-60; https://doi.org/10.3390/plasma1010005 (registering DOI)
Received: 28 January 2018 / Revised: 14 February 2018 / Accepted: 17 February 2018 / Published: 19 February 2018
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Abstract
This mini review is to introduce the readers of Plasma to the field of plasma medicine. This is a multidisciplinary field of research at the intersection of physics, engineering, biology and medicine. Plasma medicine is only about two decades old, but the research
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This mini review is to introduce the readers of Plasma to the field of plasma medicine. This is a multidisciplinary field of research at the intersection of physics, engineering, biology and medicine. Plasma medicine is only about two decades old, but the research community active in this emerging field has grown tremendously in the last few years. Today, research is being conducted on a number of applications including wound healing and cancer treatment. Although a lot of knowledge has been created and our understanding of the fundamental mechanisms that play important roles in the interaction between low temperature plasma and biological cells and tissues has greatly expanded, much remains to be done to get a thorough and detailed picture of all the physical and biochemical processes that enter into play. Full article
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Open AccessEditorial Plasma: An International Open Access Journal for All of Plasma Science
plasma 2018, 1(1), 45-46; https://doi.org/10.3390/plasma1010004 (registering DOI)
Received: 3 January 2018 / Revised: 8 January 2018 / Accepted: 8 January 2018 / Published: 12 January 2018
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Abstract
Plasma is an open access, cross-disciplinary scholarly journal of scientific studies related to all aspects of plasma science, such as plasma physics, plasma chemistry and space plasma[...] Full article
Open AccessArticle Electrical, Thermal and Optical Parametric Study of Guided Ionization Waves Produced with a Compact μs-Pulsed DBD-Based Reactor
plasma 2018, 1(1), 23-44; https://doi.org/10.3390/plasma1010003 (registering DOI)
Received: 22 November 2017 / Revised: 12 December 2017 / Accepted: 20 December 2017 / Published: 25 December 2017
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Abstract
Atmospheric pressure guided ionization waves (GIWs) that are driven by ns/μs-pulsed high voltages, are promising tools in the biomedical field allowing for the effective production of reactive species and metastables without thermal damages of the specimens that are exposed. In most cases, plasma
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Atmospheric pressure guided ionization waves (GIWs) that are driven by ns/μs-pulsed high voltages, are promising tools in the biomedical field allowing for the effective production of reactive species and metastables without thermal damages of the specimens that are exposed. In most cases, plasma is produced in noble gases using dielectric barrier discharge (DBD) devices of more-or-less sophisticated geometries. In this study, a compact low-cost DBD reactor of very simple geometry is presented. It is fed with pure helium and driven by positive μs-pulsed high voltage (amplitude: 4.5–8 kV, pulse width: 1–10 μs) of audio frequencies (5–20 kHz), while it operates consistently for long time periods in a wide range of conditions. The produced plasma exhibits propagation lengths up to 4 cm and rich chemical reactivity is established outside the reactor, depending on the device’s experimental parameters. Besides, the dielectric tube’s temperature during plasma operation is an important factor, which is linked to the plasma characteristics. This temperature and its variations are thoroughly investigated herein, along with GIWs electrical features versus the electrical parameters of the pulsed power supply. Accordingly, it is demonstrated that not all of the operational windows are adequate for thermal-free operation and suitable operating conditions of this system are proposed for diverse applications, such as biomedical (low gas temperature is a prerequisite) and surface treatments of solid materials (low temperatures are not required). Full article
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Open AccessArticle Endothelialization of Polyethylene Terephthalate Treated in SO2 Plasma Determined by the Degree of Material Cytotoxicity
plasma 2018, 1(1), 12-22; https://doi.org/10.3390/plasma1010002 (registering DOI)
Received: 18 October 2017 / Revised: 4 December 2017 / Accepted: 8 December 2017 / Published: 9 December 2017
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Abstract
Improving the biocompatibility of polyethylene terephthalate (PET) vascular grafts is an important task for avoiding thrombus formation. Therefore, SO2 plasma at various treatment periods were used to modify PET surface properties by forming sulfate functional groups. These groups were shown to act
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Improving the biocompatibility of polyethylene terephthalate (PET) vascular grafts is an important task for avoiding thrombus formation. Therefore, SO2 plasma at various treatment periods were used to modify PET surface properties by forming sulfate functional groups. These groups were shown to act antithrombogenically, ensuring good hemocompatibility of the materials, although the biocompatibility of such materials still remains a mystery. For this reason, the adhesion and viability of HUVEC cells on SO2 plasma-modified PET surfaces were studied, and the possible toxicity of the tested material was determined using two different assays, MTT (metabolic activity assay) and SRB (in-vitro toxicology assay). Changes in chemical composition, morphology and wettability were determined as well. Improved endothelialization was observed for all plasma-treated samples, with the most optimal being the sample treated for 80 s, which can be explained by it having the best combination of surface functionalization, roughness and morphology. Furthermore, toxicity was observed to some extent on the sample treated for 160 s, indicating the lowest cell density among the plasma-treated samples. X-ray photoelectron spectroscopy showed increased oxygen and sulfur content on the surface, which was independent on treatment time. Surface roughness of the plasma-treated samples increased, reaching its maximum after 80 s of treatment, and decreased thereafter. Full article
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Open AccessArticle Mechanism of Ampicillin Degradation by Non-Thermal Plasma Treatment with FE-DBD
plasma 2018, 1(1), 1-11; https://doi.org/10.3390/plasma1010001 (registering DOI)
Received: 8 August 2017 / Revised: 19 September 2017 / Accepted: 10 October 2017 / Published: 27 October 2017
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Abstract
This research focused on determining the effectiveness of non-thermal atmospheric pressure plasma as an alternative to advanced oxidation processes (AOP) for antibiotic removal in solution. For this study, 20 mM (6.988 g/L) solutions of ampicillin were treated with a floating electrode dielectric barrier
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This research focused on determining the effectiveness of non-thermal atmospheric pressure plasma as an alternative to advanced oxidation processes (AOP) for antibiotic removal in solution. For this study, 20 mM (6.988 g/L) solutions of ampicillin were treated with a floating electrode dielectric barrier discharge (FE-DBD) plasma for varying treatment times. The treated solutions were analyzed primarily using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). The preliminary product formed was Ampicillin Sulfoxide, however, many more species are formed as plasma treatment time is increased. Ampicillin was completely eliminated after five minutes of air-plasma treatment. The primary mechanism of ampicillin degradation by plasma treatment is investigated in this study. Full article
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