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Plasma Science, IEEE Transactions on

Issue 7 • Date July 2013

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Displaying Results 1 - 25 of 26
  • Table of contents

    Page(s): C1 - 1689
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  • IEEE Transactions on Plasma Science publication information

    Page(s): C2
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  • Impact of the Electric Field Distribution on the Generation Characteristics of Vacuum-Arc Discharge Plasmas

    Page(s): 1690 - 1695
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    To investigate the impact of the electric field distribution on the generation characteristics of vacuum-arc discharge plasmas, three types of coaxial electrodes, namely, a tubular electrode, a trumpet electrode, and a bowknot electrode, are designed and employed as anodes. A tubular Teflon insulator is mounted covering the cathode and in close contact with the cathode and anode in a coaxial geometry. The electric field distributions for different electrodes are simulated by the MAXWELL 3-D simulation software. The parameters for metal plasmas, such as the electron density, electron temperature, and space potential, are measured using a Langmuir probe. Furthermore, a poly(vinylidene fluoride) sensor is used to evaluate the plasma thrust characteristics. In addition, a series of contrast experiments are performed using the trumpet electrode to determine the impact of other factors that affect the electric field distribution. The experimental and simulation results indicate that plasmas generated using electrodes with greater cathode-tip electric field strength exhibit lower breakdown voltage, larger discharge current, higher density, and greater thrust. Suitable positioning of the insulator and the electrodes can increase the electric field strength of the cathode tip, revealing that the density and thrust of the plasma would be effectively increased. View full abstract»

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  • Contrasting the Effect of Electric Current Between Vertical and Horizontal High-Pressure Mercury Discharge Lamps

    Page(s): 1696 - 1702
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    This paper discusses the thermal behavior of a high-pressure mercury lamp in a horizontal position compared to that of a vertical lamp when the supply current varies. The model adopted is 3-D, steady, and dc powered. After the validation of the model, pressure of the lamp is kept at 6 × 105 Pa and the supply current varied from 1 to 10 A. Then, by comparing the case of the lamp in a horizontal position with that in a vertical one, the temperature fields, the flow of heat conduction, the flow of convective heat, and the accumulation of mercury behind the electrodes are analyzed. View full abstract»

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  • Effects of Atmospheric DBCD Plasma on Three Kinds of Typical Microorganisms

    Page(s): 1703 - 1708
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    Dielectric barrier corona discharge (DBCD) is a robust plasma reactor with high efficiency and large scalable area. Nonthermal plasma is generated by DBCD in open condition under atmospheric pressure. Products of plasma are analyzed by using spectroscopy technology. The DBCD plasma is used to treat three kinds of typical microorganisms such as Escherichia coli, Staphylococcus aureus, and Candida albicans. Then, the inactivation effects of the plasma are discussed and compared with our formerly published results of parallel-plate dielectric barrier discharge (DBD) plasma. The results show that the DBCD plasma damages microbe cells by reactive species (RS) and lower pH values, while the parallel-plate DBD plasma works mainly through microdischarge channel and RS. In addition, different cell wall configurations result in different treatment effects. View full abstract»

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  • New Arc Control Design for Vacuum Interrupters

    Page(s): 1709 - 1715
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    In this paper, we introduce a new design of an arc control exhibiting a behavior that is different from those observed with axial magnetic field (AMF) and Transverse/Radial Magnetic Field (TMF/RMF) arc controls. With this new arc control, the arc forming when the contacts are parted is a rotating diffuse columnar arc with a main arc column which can occupy up to half of the contact tip surface. We present the assessment of the arc behavior and its characteristics by means of high-speed video recordings of the arc, arc voltage measurements, and synthetic and direct testing, which show that the new arc control has the potential to offer better breaking performance than the existing AMF cup type arc control of the same size. In addition, because of the shape and behavior of the arc, the electric life of the new arc control is expected to be longer than the one of the TMF arc controls. View full abstract»

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  • Degradation of High Concentration Methanol in Aqueous Solution by Dielectric Barrier Discharge

    Page(s): 1716 - 1724
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    Degradation of high concentration methanol in aqueous solution is carried out in a dielectric barrier discharge (DBD) reactor. The degradation pathway of methanol is investigated by detecting the degradation products by gas chromatography and ion chromatography. The results demonstrate that formaldehyde as an intermediate product is accumulated easily at the early stage of the degradation process. An increase in the initial concentration (100 to 20000 mg · L-1) of methanol has a much greater effect on methanol mineralization than on methanol degradation. It is found that methanol degradation and mineralization could be enhanced by increasing either the acidity or basicity of the solution. The methanol degradation rate increases dramatically with the addition of Fe2+ (10-80 mg · L-1), whereas the influence of Cl- concentration (3000-24000 mg · L-1) on methanol degradation and mineralization is not as significant. The increase in liquid conductivity increase and decrease in pH value are mainly attributable to the NO3- formation due to the DBD treatment. Moreover, the methanol degradation mainly occurs in the liquid film on the liquid interface that is in direct contact with DBD, and the amount of methanol diffusing into the liquid film (main reaction zone) determines the degradation efficiency. View full abstract»

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  • Plasma Bullets Propagation Inside of Agarose Tissue Model

    Page(s): 1725 - 1730
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    This paper demonstrates plasma bullets generated by microsecond pulses in He flow propagation inside of conductive agarose gel tubes mimicking tissue. The objective of this paper is to understand the possibility of internal diseases' treatment (e.g., lung or intestinal cancer) using plasma jets. The propagation dynamics is studied using fast imaging technique, and production of reactive species is demonstrated both in gas phase (using optical emission spectroscopy) and inside of the agarose gel (using fluorescent dye). In addition, it is demonstrated that plasma bullets may propagate not only in a straight tubes, but also in L-shaped tubes, as well as be split in T-shaped tubes. All these facts offer an indication of possible successful application of plasma bullets for treatment of internal diseases, for example, lung cancers or intestinal diseases. View full abstract»

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  • A Reduced-Order Model for Thermionic Hollow Cathodes

    Page(s): 1731 - 1745
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    A reduced-order numerical model describing the plasma in an orificed hollow cathode is presented as a quick tool for the design of thermionic cathodes. A time-independent, volume-averaged model is developed to determine plasma properties, wall temperatures, and cathode lifetime without requiring experimental data as input. A system of particle and energy balance equations is numerically solved without invoking a Saha-type equilibrium under the hypothesis of a direct-impact ionization process. Further, a lumped-parameter thermal model is coupled with the plasma model to estimate the temperature profile along the cathode axis and the emitter lifetime. The obtained results capture most of the characteristic features of this class of hollow cathodes as compared with the available experimental data. In addition, the model gives insight into the most important power deposition processes affecting the emitter and orifice regions. The effect of the geometry on both plasma parameters and cathode performance is discussed to suggest design guidelines for the development of state-of-the-art hollow cathodes. View full abstract»

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  • On the Electrical Characteristic of Atmospheric Pressure Air/He/ {\rm O}_{2}/{\rm N}_{2} /Ar Plasma Needle

    Page(s): 1746 - 1750
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    The electrical characteristics of an air plasma needle are investigated. The discharge is driven by pulsed direct current voltages. A series of discharge pulses appear for one applied voltage pulse. The interval between nearby discharge current is tens of nanoseconds, which corresponds to a frequency of tens of MHz. This is much higher than that of the Trichel pulse (tens of kHz). The frequency of the discharge current pulses increases with the applied voltage but decreases with the gas gap distance. The series current pulses are found not only existing in electronegative gases (air, pure O2), but also in Ar and N2. On the other hand, when He is used, there always appears only one discharge current pulse; by adding small percentage of O2 to He, multiple discharges appear again. View full abstract»

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  • Comparison of Advanced Machine Learning Tools for Disruption Prediction and Disruption Studies

    Page(s): 1751 - 1759
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    Machine learning tools have been used since a long time ago to study disruptions and to predict their occurrence. On the other hand, the challenges posed by the quality and quantities of the data available remain substantial. In this paper, methods to optimize the training data set and the potential of kernels-based advanced machine learning tools are explored and assessed. Various alternatives, ranging from appropriate selection of the weights to the inclusion of artificial points, are investigated to improve the quality of the training data set. Support vector machines (SVM), relevance vector machines (RVMs), and one-class SVM are compared. The relative performances of the different approaches are initially assessed using synthetic data. Then they are applied to a relatively large database of JET disruptions. It is shown that in terms of final results, the optimization of the training databases proved to be very productive. Further, the RVM algorithm performs well when it is trained on a small set of discharges compared to the traditional methods. View full abstract»

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  • Trigger Method Based on Secondary Induced Overvoltage for Linear Transformer Drivers

    Page(s): 1760 - 1766
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    In this paper, a triggering method based on secondary induced overvoltage for a linear transformer driver (LTD) is proposed and investigated by simulation. A detailed circuit model established for the LTD is chosen to study the effect of some factors on the feasibility of this triggering method. The considered factors include the permeability, equivalent resistance of energy loss, saturation of magnetic cores, and the delay of gas switches in LTD cavities. Simulation results indicate that high equivalent resistance and high permeability of magnetic cores are helpful in realizing this trigger method. However, the resistance plays a leading role. An equivalent resistance of more than 1.5 Ω favors the realization of this trigger. However, a relative permeability of even 25 has not produced a fatal menace to this triggering method. The feasibility of this triggering necessitates the available volt-second product of the present magnetic cores to be expanded twice. As for gas switches, the interval given by secondary induced overvoltage would likely be long enough to complete their breakdown. From simulation results, it is shown that LTD switches could be rapidly closed under the action of such an overvoltage pulse with a rise time of less than 10 ns. View full abstract»

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  • Compact Electric Power System for Fusion Reactor

    Page(s): 1767 - 1772
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    The issue of the Tokamak fusion reactor is its large area occupied by its power supply, which is about half of the total building area for the International Thermonuclear Experimental Reactor (ITER), together with the compatibility between the site grid and Tokamak loads during the plasma operation period. ITER is now implemented with Tokamak, which requires about 1 GVar reactive power to compensate its power system for superconducting magnets where about 0.2 GVar is transferred from France Electrical Power Network, the other 0.75 GVar is generated by the system of reactive power compensation and harmonic filtering, the standard VSC configuration. ITER can experimentally generate 500-MW fusion thermal power in 400 s long pulse mode. It could only generate about 500 MW/3 = 167 MWe active electric power if it is to be configured with pressured water reactor due to the fact that it is only about 1/3 conversion efficiency from thermal energy to electric energy. For such fusion machine, the requirement for reactive power is much larger than the active power it generates. Based on this requirement, one efficiency and compact pulsed synchronous generator is suggested for this purpose. It can generate not only the fundamental reactive power to compensate and stabilize the power network with low internal impedance but also the active power for outputting power to the network with exciting controller of the generator. Due to its two purposes in one device configuration, it becomes compact and reliable by being implemented in the design of future fusion power plant for demonstration. Some consideration has been done to the special low impedance synchronous generator, which is intended for the concept design of Chinese Fusion Engineering Testing Reactor, targeting the compact electric power system for superconducting Tokamak fusion reactor. View full abstract»

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  • Attachment Processes and Influencing Factors in Competition Tests Under Switching Impulse Voltages

    Page(s): 1773 - 1780
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    Research on the attachment processes in competition tests can provide insights into the influencing factors involved in the selection process that determines the lightning strike point. In this paper, a series of competition tests with a rod-rod gap configuration are designed and carried out. The test results indicate that the strike mechanism is decided by two discharge processes, namely the free development of the downward-propagating discharge and the interception process of the upward and downward discharges. If the first process prevails, the strike probabilities for different grounded rods will tend to be equal. For the second process, the strike probabilities reflect the different performances of the grounded rods for intercepting downward discharges. As the scale of the discharge gap increases, the development of the downward leader becomes more and more dominant in selecting the strike point. In natural lightning strikes, the scale of the downward leader is normally more than 90% of the discharge gap, hence the protective effect of lightning rods with different tips will not be significant for low rod heights and small lightning currents. To reflect the effect of the downward leader development on the choice of the strike point, a minimum discharge air gap of 10 m is suggested. View full abstract»

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  • Design and Testing of a Novel Inductive Pulsed Power Supply Consisting of HTS Pulse Power Transformer and ZnO-Based Nonlinear Resistor

    Page(s): 1781 - 1786
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    Higher energy density makes inductive energy storage more promising than capacitive storage for pulsed power supplies in industrial and military fields. To realize high amplitude of pulsed current and relieve stress of opening switch, this paper proposes a novel inductive pulsed power supply consisting of high-temperature superconducting pulse power transformer and ZnO-based nonlinear resistor. First, working processes and laboratory setup are described in detail. Then, simulation using the software SIMPLORER is built to show major pulse characteristics and comparisons of two different nonlinear resistors. For verifying the feasibility of this mode, high-current testing is carried out and the results show that large amplitude of pulsed current 3 kA with energy transfer efficiency 60% is achieved, and the ZnO-based nonlinear resistor can help to limit the voltage of the opening switch to a small constant below its clamping value as current is interrupted. View full abstract»

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  • Erosion and Lifetime of Tungsten, Gold, and Nichrome Wire Anodes in an Ultracorona in Air

    Page(s): 1787 - 1793
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    Anode erosion rates and lifetime-limiting parameters for different wire materials are investigated in a positive corona in atmospheric pressure air. The electrode wear is determined by measuring electrical resistance of the corona wire. Among the test materials are W, Ni-Cr alloys, and Au-coated stainless steels. The erosion rate of the Au-coated stainless steel and Ni-Cr alloy anode wires increases approximately exponentially with the total amount of transferred charge. A unified linear relationship between the ozone generation rate and wire diameter is suggested for typically used materials. View full abstract»

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  • High-Power Test of Chemical Vapor Deposited Diamond Window for an ECRH System in SST-1

    Page(s): 1794 - 1798
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    High-power tests on chemical vapor deposited (CVD) diamond window are carried out using 82.6-GHz Gyrotron. To test CVD diamond window with calorimetric dummy load, a matching optic unit is designed and fabricated with special profiled mirrors. The mirrors are fabricated by Gycom Russia and a mirror box assembly is fabricated at Institute for Plasma Research. The mirrors and mirror box are cooled with water. The mirror box consists of four arc detectors for the protection of window. The CVD diamond window is connected to a dummy load with this mirror box. The alignment of mirror is done during the testing of CVD window in pulsed condition. After achieving the desired Gaussian pattern at the exit of mirror box, system is connected to a dummy load for continuous wave test. The CVD window is tested maximum power up to 60 kW in pulse duration of 600 s. View full abstract»

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  • Development of In-Vessel Vertical Coil Power Supply in KSTAR

    Page(s): 1799 - 1804
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    The Korea Superconducting Tokamak Advanced Research (KSTAR) device is an advanced superconducting tokamak to establish scientific and technological bases for an attractive fusion reactor [1]. In-vessel vertical coil (IVC) power supply (PS) is developed for vertical stability and shape control of KSTAR plasma. IVC PS in KSTAR is based on a single-phase full-bridge inverter. The output voltage and current are dc ±1 kV and ±10 kA, respectively. Insulated gate bipolar transistor is used as switching power device in IVC PS and maximal 5 kHz of switching frequency is adopted to meet the requirement of fast control by plasma control system. This paper describes the configuration and engineering of the IVC PS system and analyzes both the IVC coil commissioning and the major performances that D-shape plasma achieved in experiments. View full abstract»

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  • Evolution of Dust-Acoustic Solitary Waves in a Dusty Plasma: Effects of Vortex-Like Ion and Nonthermal Electron Distributions

    Page(s): 1805 - 1810
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    In this paper, a reductive perturbation theory was used to derive a modified korteweg-de-vries equation for dusty plasmas consisting of vortex-like ions and nonisothermal electrons both for the first- and second-order perturbed potential. It was found that the presence of vortex-like ions and nonisothermal electrons modifies the nature of dust-acoustic solitary structures. The results show that the plasma model under consideration permits rarefactive solitons only and the higher-order approximation enhances the amplitude of dust acoustic waves. View full abstract»

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  • Proposal for: Special Issue on Pulsed Power Science and Technology - IEEE Transactions on Plasma Science (October 2014)

    Page(s): 1811
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  • Symposium on Fusion Engineering (SOFE) Publications

    Page(s): 1812
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  • Special Issue of IEEE Transaction on Plasma Science: Plasma Propulsion (Scheduled for December 2014)

    Page(s): 1813
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  • My IEEE

    Page(s): 1814
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  • 2013 IEEE membership application

    Page(s): 1815 - 1816
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  • IEEE Transactions on Plasma Science information for authors

    Page(s): C3
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IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

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