Search

In a polywell reactor, it is critical to have a stable and energetic virtual cathode that is necessary to accelerate ions and create fusion interactions. Increasing the confinement time of virtual cathode electrons is of critical importance in the performance of polywell reactors. In this paper, COMSOL Multiphysics software was used to perform a three-dimensional numerical simulation in order to investigate the impacts of effective variables of a polywell on the virtual cathode. The findings indicated that the confinement time depends on the distance between the coils, coil radius, coil current, and the kinetic energy of the injected electrons. In addition, by using the simulation results, the dependence of the mentioned parameters on the confinement time is obtained, and then a mathematical model was developed.

Abstract In this study, three-type paper supercapacitors based on the polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA)/phosphoric acid (H3PO4) gel electrolytes and graphite nanoparticles (GNPs) electrodes have been fabricated. The gel electrolytes and electrodes films have been coated on the paper using push coating and then characterized by scanning electron microscopy (SEM). In two types of the paper supercapacitors, on the PVDF gel electrolyte film, a layer of PVA/water and BaTiO3 as a gel separator film has been coated. The specific capacitance of the paper supercapacitors using cyclic voltammetry (CV) and galvanostatic (charge–discharge) methods at the scan rates 20 and 150 mV s−1 have been investigated. The paper supercapacitor based on the BaTiO3 separator film showed higher specific capacitance (312 F g−1) compared to other samples. Also, using electrochemical impedance spectroscopy (EIS), the Nyquist and Bode curves of paper supercapacitors have been measured. For the paper supercapacitors based on the PVDF gel electrolyte film and BaTiO3 separator film using the Nyquist curves, the equivalent series resistance (ESR) was 306 Ω and 125 Ω, respectively. The paper supercapacitor based on BaTiO3 gel separator structure represents a new type of flexible supercapacitor with high performance that can be applied to electronic devices.

Using a three-dimensional numerical simulation, the dependencies of the electron cloud (virtual cathode) on the distance between the coils in the Polywell fusion reactor were examined. In the Polywell, the role of a stable and energetic virtual cathode is crucial for fusion. It is shown that by increasing the spacing coils, the electron confinement time increases initially and then remains constant. Using the simulation results, an optimum range for the spacing of coils was suggested, which leads to a longer and more effective confinement. The results obtained can be used to design future devices in order to have a more effective virtual cathode.

The current research was carried out to reveal the possible impacts of cold plasma on growth and physiology of wheat, as a new approach in plant science. Short and long-term impacts of different types of plasma (nitrogen and helium) with surface power density of 0.4 W cm-2, exposure times (15, 30, 60, and 120 s), and repetitions (1, 2, and 4 times with 24 h intervals) were evaluated. Single-time applied helium or nitrogen derived plasma significantly promoted total root and shoot lengths, in contrast to four times application, and the root system was more sensitive than the shoot one. In addition, seedlings were more sensitive to nitrogen derived plasma, compared with helium. The physiological responses to plasma treatment were analyzed via protein assay and peroxidase or phenylalanine ammonia lyase (PAL) activities measurements. Plasma generated signaling molecules, especially ozone, nitric oxide, and/or UV radiation induced promotions in the peroxidase and PAL activities as well as increase in protein content in leaves, especially when times and/or repetitions increased. Plants were perished by the nitrogen derived plasma at the highest exposure time and number of repetitions. However, the seedlings with inhibited growth not only caught up control one month after, but even the growth rate and biomass accumulation in the shoot and leaves were accelerated. Increased leaf soluble phenol content was recorded in plasma treated seedlings, especially at longer times and more repetitions.

In the present paper our aim is to investigate the effect of the spray time of the aluminium coated layers on the microstructure and corrosion behaviour. For this purpose we use the self-generated atmospheric plasma spray system for coating of aluminium on the carbon steel substrate. The different thicknesses of coating are created. To evaluate this effect we use the several analyses such as X-ray diffraction, scanning electron microscope, Micro hardness analysis by Vickers method, Adhesion strength analysis and electrochemical polarization test. The results are very interesting and show that due to low porosity, thicker layers are more homogeneous. The nanoparticles are observed in the thicker layers. The micro hardness tests show that the thicker layers have the better micro hardness value. Next, the adhesion strength tests illustrate that the highest adhesion strength are for longer spray times. On the other hand, the corrosion resistance behaviour of the coating is investigated by electrochemical polarization test. It is shown that the corrosion resistance increases by increasing the thickness due to low percentage of porosity. Keywords: Plasma spray, Thickness, Aluminium, Micro hardness, Corrosion resistance

The circuit parameters are investigated in a Mather-type plasma focus device. The experiments are performed in the SABALAN-I plasma focus facility (2 kJ, 20 kV, 10 µF). A 12-turn Rogowski coil is built and used to measure the time derivative of discharge current (dI/dt). The high pressure test has been performed in this work, as alternative technique to short circuit test to determine the machine circuit parameters and calibration factor of the Rogowski coil. The operating parameters are calculated by two methods and the results show that the relative error of determined parameters by method I, are very low in comparison to method II. Thus the method I produces more accurate results than method II. The high pressure test is operated with this assumption that no plasma motion and the circuit parameters may be estimated using R-L-C theory given that C0 is known. However, for a plasma focus, even at highest permissible pressure it is found that there is significant motion, so that estimated circuit parameters not accurate. So the Lee Model code is used in short circuit mode to generate the computed current trace for fitting to the current waveform was integrated from current derivative signal taken with Rogowski coil. Hence, the dynamics of plasma is accounted for into the estimation and the static bank parameters are determined accurately. Keywords: Plasma focus, Short circuit, High pressure, Rogowski coil, Circuit parameters, Lee Model

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).This article has been retracted at the request of the Editors-in-Chief.After a thorough investigation, the Editors have concluded that the acceptance of this article was based upon the positive advice of at least one illegitimate reviewer report. The report was submitted from an email account which was provided to the journal as a suggested reviewer during the submission of the article. Although purportedly a real reviewer account, the Editors have concluded that this was not of an appropriate, independent reviewer.This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identities were assumed and to the readers of the journal that this deception was not detected during the submission process.Further, the corresponding author was not able to explain the reason for adding the author M. Ghoranneviss to the revised article.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).This article has been retracted at the request of the Editors-in-Chief.After a thorough investigation, the Editors have concluded that the acceptance of this article was based upon the positive advice of at least one illegitimate reviewer report. The report was submitted from an email account which was provided to the journal as a suggested reviewer during the submission of the article. Although purportedly a real reviewer account, the Editors have concluded that this was not of an appropriate, independent reviewer.This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identities were assumed and to the readers of the journal that this deception was not detected during the submission process.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Editors-in-Chief.The article duplicates significant parts of a paper that had already appeared in the Journal of Alloys and Compounds 648 (2015) 1104–1108 http://dx.doi.org/10.1016/j.jallcom.2015.07.063. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

In this study, the three structures of the symmetric paper supercapacitors based on the carbon nanotubes (CNTs), graphite nanoparticles (GNPs) and graphene electrodes have been fabricated. In the supercapacitors was used of polyvinyl alcohol (PVA)/phosphoric acid (H3PO4) as a gel electrolyte and the BaTiO3 film as a separator film. The carbon nanomaterials, gel electrolyte surface, and electrode films were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The specific capacitance of the symmetric paper supercapacitors using charge-discharge technique and C-V curves at the voltage scan rates 20 mV/s and 150 mV/s have been investigated. The symmetric paper supercapacitor based on the CNTs electrode showed higher specific capacitance 411 F g−1, compared to GNPs and graphene supercapacitors. Also by electrochemical impedance spectroscopy, the Nyquist curves of the symmetric paper supercapacitors have been plotted. For the symmetric paper supercapacitors based on the GNPs, graphene and CNTs electrodes the equivalent series resistance (ESR) resistance was 210 Ω, 96 Ω and 101 Ω respectively. The flexible symmetric paper supercapacitor based on BaTiO3/PVA/CNTs structure denotes a new type of the flexible supercapacitor that can be applied to the soft electronic.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).This article has been retracted at the request of the Editors-in-Chief.After a thorough investigation, the Editors have concluded that the acceptance of this article was based upon the positive advice of at least two illegitimate reviewer reports. The reports were submitted from email accounts which were provided to the journal as suggested reviewers during the submission of the article. Although purportedly real reviewer accounts, the Editors have concluded that these were not of appropriate, independent reviewers.This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identities were assumed and to the readers of the journal that this deception was not detected during the submission process.No reason has been provided for the addition of the author name A. Salar Elahi to the authorship of the revised article.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).This article has been retracted at the request of the Editors-in-Chief.After a thorough investigation, the Editors have concluded that the acceptance of this article was based upon the positive advice of at least one illegitimate reviewer report. The report was submitted from an email account which was provided to the journal as a suggested reviewer during the submission of the article. Although purportedly a real reviewer account, the Editors have concluded that this was not of an appropriate, independent reviewer.This manipulation of the peer-review process represents a clear violation of the fundamentals of peer review, our publishing policies, and publishing ethics standards. Apologies are offered to the reviewers whose identities were assumed and to the readers of the journal that this deception was not detected during the submission process.

In this paper, we have studied the effect of working gas pressure on plasma pinch properties in a Mather type plasma focus (2 kJ, 20 kV, 10 μF), named SABALAN1. Argon at the various operating pressures ranging from 0.1-1.2 Torr has been used as working gas. The total current waveform has been measured for different pressures. Also, a numerical simulation was done using Lee model code to perform numerical experiments in SABALAN1. The numerical simulation was used to compute argon soft x-ray yield as a function of pressure, to anticipate the maximum soft x-ray efficiency at optimum operating gas pressure. The Lee model was configured for SABALAN1, by fitting a simulated discharge current waveform against a measured discharge current waveform was obtained by numerically integrating the output of a dI/dt calibrated Rogowski coil. The experimental and simulation curves for plasma pinch properties have been plotted. Some of the dynamic parameters of the plasma and the characteristics of the plasma pinch have been displayed at different argon pressures in two tables. In addition, the chart of the normalized parameters of the plasma pinch has been plotted in terms of pressure. The results of experimentally measured and numerical simulation show that better pinches with attention to their plasma pinch characteristics, generally were dependent on pressure and the best pinch is obtained at 0.6-0.7 Torr for argon at 14 kV in SABALAN1. Furthermore, in high pressures (higher than 0.7 Torr in our experiments), the discharge current can behave as short circuit discharge and resembles that of a simple L-C-R discharge which is a damped sinusoidal. Comparison of the experimental and numerical curves shows sensible agreement in some plasma pinch properties such as the time to pinch and depth of focus. The results from charts and tables have been discussed.

One of the best ways to get information about plasma and interactions within it, is the study on visible light emitted from plasma. Detection of the emission spectrum from plasma leads to identify the spectral lines of ions and impurities inside the plasma and measurement of all related parameters to ion flux such as velocity and temperature. The first measurement of impurities into the IR-T1 tokamak plasma is done by spectroscopic technique. The CCD-based spectrometer device with the wavelength range of 400-550 nm is used to detection the spectrum emitted from the plasma. The impurities into the plasma in the intended wavelength range are identified. Furthermore, the Doppler broadening of the most intense peaks of impurities and their temperatures are measured. The methods in this paper can be used on all fusion devices.

The first results of the movable multipurpose probe (MPP) experiments performed on the IR-T1 Tokamak are presented. For this purpose, a moveable MPP was designed, constructed, and installed on the IR-T1 Tokamak for the first time. MPP can measure radial variation of floating potential and ion saturation current, electrostatic fluctuation, magnetic fluctuation, and flow velocity simultaneously. The relation between gradient of Reynolds stress and poloidal particle flux can be investigated by MPP. It can measure the radial variation of radial electric field and poloidal electric field. The most advantage of MPP is to measure electric and magnetic plasma fluctuations simultaneously. MPP is composed of three sections: electrical part, magnetic part, and flow measurement section. This is a compact probe in which do not disturb plasma. The results are presented and discussed.

We have reviewed the deposition of titanium nitride (TiN) thin films on stainless steel substrates by a DC magnetron sputtering method and annealing at different annealing temperatures of 500, 600, and 700°C for 120 min in nitrogen/argon atmospheres. Effects of annealing temperatures on the structural and the optical properties of TiN films were investigated using X-ray diffraction (XRD), atomic force microscope (AFM), field emission scanning electron microscopy (FESEM), and UV-VIS spectrophotometer. Our experimental studies reveal that the annealing temperature appreciably affected the structures, crystallite sizes, and reflection of the films. By increasing the annealing temperature to 700°C crystallinity and reflection of the film increase. These results suggest that annealed TiN films can be good candidate for tokamak first wall due to their structural and optical properties.

Discovery of the laser in 1960 hopes were based on using its very high energy concentration within very short pulses of time and very small volumes for energy generation from nuclear fusion as “Inertial Fusion Energy” (IFE), parallel to the efforts to produce energy from “Magnetic Confinement Fusion” (MCF), by burning deuterium-tritium (DT) in high temperature plasmas to helium. Over the years the fusion gain was increased by a number of magnitudes and has reached nearly break-even after numerous difficulties in physics and technology had been solved. After briefly summarizing laser driven IFE, we report how the recently developed lasers with pulses of petawatt power and picosecond duration may open new alternatives for IFE with the goal to possibly ignite solid or low compressed DT fuel thereby creating a simplified reactor scheme. Ultrahigh acceleration of plasma blocks after irradiation of picosecond (PS) laser pulses of around terawatt (TW) power in the range of 1020 cm/s2 was discovered by Sauerbrey (1996) as measured by Doppler effect where the laser intensity was up to about 1018 W/cm2. This is several orders of magnitude higher than acceleration by irradiation based on thermal interaction of lasers has produced.

Nanocrystalline Pb1−3x/2GdxTiO3 (where x=0.01) abbreviated as PGT has been synthesised by high energy ball milling at room temperature. Milling was continuous and X-ray analysis shows that single phase tetragonal structure of nanocrystalline PGT was formed after 15 h milling. The average crystallite size was found to be 17 nm. The frequency dependent ac conductivity of the PGT ceramic was studied in the range 100–525°C. Complex impedance analysis suggested the dielectric relaxation to be of non-Debye type. The activation energy was found to be 1.04 ev. The mechanism of charge transport in nanocrystalline PGT was successfully explained by correlated hopping model.