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Plasma Science, IEEE Transactions on

Issue 10 • Date Oct. 2012

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Displaying Results 1 - 25 of 26
  • Table of contents

    Publication Year: 2012 , Page(s): C1 - 2669
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  • IEEE Transactions on Plasma Science publication information

    Publication Year: 2012 , Page(s): C2
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  • Introducing the New Senior Editor for Pulsed Power Science and Technology

    Publication Year: 2012 , Page(s): 2670
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  • Electron Swarm Parameters in \hbox {c-C}_{4} \hbox {F}_{8} and \hbox {CO}_{2} Gas Mixtures From Boltzmann Equation Analysis

    Publication Year: 2012 , Page(s): 2671 - 2677
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    The electron swarm parameters in c-C4F8/CO2 gas mixtures, including the density-normalized effective ionization coefficient (α-η)/N and the drift velocity Ve, are calculated for the overall density-reduced electric-field strength E/N values from 150 to 600 Td (1 Td = 10-17 V · cm2). These calculations have been performed through solving the Boltzmann equation under the two-term approximation in the condition of steady-state Townsend experiment. The c-C4F8 content k in the gas mixtures can be varied over the range of 0%-100 %. From the variation curve of (α-η)/N with the c-C4F8 mixture ratio k, the limiting field strength (E/N)lim for each c-C4F8 concentration is determined for the analysis of the insulation characteristics of the c-C4F8/CO2 mixture. Additionally, the global-warming potential and the liquefaction temperature of c-C4 F8/CO2 gas mixtures are also taken into account to evaluate the possibility of applying in gas insulation of power equipment. View full abstract»

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  • The Electron Sheath Around an Emissive Wire in Vacuum

    Publication Year: 2012 , Page(s): 2678 - 2685
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    An orbit-motion-limited (OML) theory is developed for the electron sheath and the virtual cathode that forms around an emissive wire in vacuum. The electron cloud above the wire surface is assumed to be described by a 2-D Maxwellian distribution function. A comparison is made with a 1-D theory having only radial velocities for the electrons. The OML theory gives a greater electron density and a more negative virtual cathode because of differences between the 1-D and 2-D distribution functions. Expressions are derived for the current from the cathode to the anode. View full abstract»

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  • Three-Dimensional Particle-in-Cell Simulation of Fast Oscillation Startup and Efficiency Improvement in a Relativistic Magnetron With Electric Priming

    Publication Year: 2012 , Page(s): 2686 - 2692
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1648 KB) |  | HTML iconHTML  

    A 3-D particle-in-cell (PIC) code MAGIC 3-D has been used to examine the output performance of a relativistic magnetron operating under the effect of electric priming by protrusions and recessions on the inner surface of the anode vanes. Electric priming has been implemented and demonstrated using the PIC code for electron prebunching in A6 relativistic magnetron. When N-fold perturbation of the radial electric field is imposed in the azimuthal direction along anode-vane inner surfaces, the electron initially develops into the desired 2π-mode, resulting in fast oscillation startup. The startup time is reduced by 46%, the output power is increased by 30%, and the efficiency is increased by 30% for three protrusions alternating with three recessions along the anode-vane inner surfaces in comparison with the A6 basic model. Simulations have been also carried out for different combinations of protrusions and recessions. All the studies have been carried out for 2π -mode of operation. View full abstract»

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  • Computer Simulation and Analysis of 350-MHz High-Power Coaxial RF Window and T-bar Transition

    Publication Year: 2012 , Page(s): 2693 - 2698
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    This paper describes a simple method to optimize the design of a high-power T-bar coaxial-to-rectangular waveguide (WR2300) transition including coaxial RF window using CST Microwave Studio code. S-parameter analysis has been iteratively used to find matching solutions at 350 MHz. A narrow-band structure has been analyzed with an aim to establish a computer-based electromagnetic design methodology for practical high-power coaxial-to-rectangular waveguide transition. Low RF power measurement results of the cold test model of the coaxial RF window and T-bar transition assembly agree quite closely with the predicted value at designed frequency by simulation. View full abstract»

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  • Spectroscopic Diagnostic of Volume Discharge Arrangement of a DBD Source and Comparison With PIC Simulation Code

    Publication Year: 2012 , Page(s): 2699 - 2705
    Cited by:  Papers (1)
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    This paper reports the spectroscopic analysis in volume discharge arrangement of a dielectric barrier discharge source in parallel plate geometry of a width of 2 mm. Helium is used as a working gas. The investigations are carried out using sinusoidal supply for the generation of discharges where two current pulses have been observed with different polarities in one period. The electron plasma density and temperature during the discharge have been estimated using the line-ratio technique from the observed visible neutral helium lines. To validate the results, a commercial particle-in-cell simulation code, OOPIC-Pro, has been used, which confirms filamentary as well as diffused discharges observed in the experiment. This code analysis also validates the estimated electron plasma density and temperature measurements at two different working pressures and at a fixed operating frequency. View full abstract»

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  • Surface Cleaning Using an Atmospheric-Pressure Plasma Jet in \hbox {O}_{2}/\hbox {Ar} Mixtures

    Publication Year: 2012 , Page(s): 2706 - 2710
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    An atmospheric-pressure plasma jet generated in O2/Ar mixtures by specially designed equipment with two coaxial quartz tubes and double power electrodes has been investigated, and its effect on the cleaning of surface organic contaminations has been studied. The Q-V Lissajous figures are performed to evaluate the power consumed in the discharge and show no great modification in consumed power with the increase in the oxygen flow rate. From the results of the optical emission spectra, remarkably high oxygen radical concentration is obtained at a 1.5% addition of O2 to Ar and then decreases with the further increase in the O2/Ar mixing ratio. The effect of the surface cleaning by O2/Ar-based plasma is studied with respect to the changes in the contact angle. An addition of O2 to Ar decreases the contact angle, and the lowest contact angle is obtained at a 1.5% addition of O2 to Ar. However, further addition of oxygen does not show further improvement in the contact angle. From the results of quadrupole mass-spectrum analysis, we can identify the fragment molecules of CO and H2O in the emitted gases, which are produced by the decomposition of the surface organic contaminations during the cleaning process. View full abstract»

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  • Effect of Low-Temperature Plasma on Deactivation of Hepatitis B Virus

    Publication Year: 2012 , Page(s): 2711 - 2716
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    In recent years, low-temperature plasma (LTP) has been widely applied in biological and medical fields. This paper is aimed to investigate the deactivation effect of LTP on hepatitis B virus (HBV). Dielectric barrier discharge (DBD) is employed to generate the atmospheric-pressure LTP for treatment of HBV. HBV serum collected from hepatitis B patients with HBsAg, HBeAg, and anti-HBc positive is used as the treatment model. LTP treatment time intervals are set as 10, 20, 30, and 40 s, respectively. Concentrations of HBsAg and S/N value for each different treatment are calculated. The liver function and HBV deoxyribonucleic acid (DNA) copy number are also detected. It is found that, compared with the control group, the concentrations of HBsAg and HBV DNA copy number of different treatment groups have statistically significant differences. With time going of LTP treatment, both the concentration of HBsAg and the copy number of HBV DNA gradually decrease, and all the S/N values are less than 2.1, indicating that HBsAg becomes negative after LTP treatment. Comparing the liver functions (i.e., enzymatic, proteinic, and bilirubin indicators) before and after LTP treatment, all the data are in the range of normal reference values. It is concluded that LTP induced by DBD is effective for HBV deactivation, and the liver function is kept normal during the process of plasma killing HBV. View full abstract»

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  • Analysis of Current and Magnetic Field Distributions in Rail Launcher With Peaceman–Rachford Finite-Difference Method

    Publication Year: 2012 , Page(s): 2717 - 2722
    Cited by:  Papers (1)
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    The evaluation of current and magnetic field distributions in a railgun system during the launch is helpful to its structure design and efficiency improvement. In this paper, the finite-difference method (FDM) for the transient electromagnetic analysis of a railgun is presented. Using a 2-D analysis, the Peaceman-Rachford format is employed to the FDM to calculate current and flux density distributions. For the convenience of numerical experiment, a rectangle is used as the cross-sectional shape in railgun system at present. Also, as the prerequisite to calculate the current and the magnetic flux density distributions, the inductance gradient of rails is analyzed based on the phase method. The results of the simulation show how the distributions of both current density and magnetic field change during the discharge process. View full abstract»

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  • Thermodynamic and Radiative Properties of Plasma Excited in EDM Process Through \hbox {N}_{2} Taking Into Account Fe

    Publication Year: 2012 , Page(s): 2723 - 2735
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    After initial discharges in the electrical discharge machining (EDM) process, iron plasma appears due to steel workpiece vaporization. This study deals with the calculation of the thermodynamic properties and net emission coefficient of nitrogen-iron arc plasma. Assuming isothermal plasma in local thermodynamic equilibrium, the properties are presented according to the typical plasma parameter range of the EDM process, viz., for temperature up to 10 000 K, pressure range of 0.1-1 MPa, different amounts of iron, and several EDM plasma radii. The presence of iron vapor has considerable influence on the thermodynamic and radiative properties of EDM arc plasmas. View full abstract»

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  • Current Sheet Axial Dynamics of 2.5-kJ KSU-DPF Under High-Pressure Regime

    Publication Year: 2012 , Page(s): 2736 - 2740
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    In dense plasma focus (DPF) machines, the high-pressure (HP) regime of operation can be used as alternative technique to short-circuit (SC) test as the current sheet motion is minimal. The SC test was performed to get the right values for the static parameters of the machine. HP shots of more than 30 mbar were performed on the 2.5-kJ Kansas State University DPF machine to determine the deviation of HP values from SC values in computed static inductance and resistance. The test was performed using various gases over a wide range of molecular/atomic mass, starting from hydrogen as the lightest gas up to argon. It was found that the deviation in static inductance and resistance computed from HP method is inversely proportional to gas molecular mass at a certain pressure. The heavy gases like neon and argon were found to give the most accurate results. At 60 mbar of argon, the inductance deviation was 6.5%, and the resistance deviation was 14%. It was found also that increasing gas pressure over 30 mbar using heavy gases like Ar or Ne gives no effective improvement on the computed static impedance. Snowplow model was used to predict the axial position and the axial speed of the current sheet during the HP regime. The model showed that the average axial speed in heavy gases like argon was 0.8 cm/ μs, whereas in hydrogen, it was 1.6 cm/μs. View full abstract»

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  • Preliminary Results of Kansas State University Dense Plasma Focus

    Publication Year: 2012 , Page(s): 2741 - 2744
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    Kansas State University (KSU) dense plasma focus (DPF) is a 2.5-kJ DPF machine newly commissioned at the Plasma Radiation Physics Laboratory at KSU. The machine was designed to be used as a multiradiation source for applications in nuclear science and engineering. Neutrons are emitted from deuterium-deuterium (D-D) fusion reactions during high-power electric discharges at 17 kV, 140 kA, and 5 mbar. The machine circuit parameters were calculated using the short-circuit test. The emitted neutrons were measured using several radiation detection techniques. The 2.45-MeV characteristic D-D neutron energy was confirmed using the time-of-flight technique using a BC-418 plastic scintillator. The maximum neutron yield was roughly measured to be 2.8 × 108 neutrons per shot using a set of BTI BD-PND bubble detectors. Moreover, the neutron yield variation with pressure was measured and compared with the computed neutron yield using Lee model. Finally, the measured current showed good agreement with Lee six-phase model. View full abstract»

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  • Dependence of String Electron Current on Array Plasma Aspect Angle and Temperature

    Publication Year: 2012 , Page(s): 2745 - 2750
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    In most cases, the incident aspect angle of a photovoltaic array to the local plasma continuously changes for a spacecraft in low Earth orbit. It is possible to simulate the combined effects of changing array ram aspect angle with respect to the plasma flow inside a vacuum chamber. On-orbit solar array collected current will significantly vary as a function of the angle between the spacecraft velocity vector and the solar array front surface normal vector. The purpose of this paper is to extract this angular dependence of electron current collection of UltraFlex solar array coupons, as well as to measure the dependence of string electron collection current on array temperature. It is found that collected current can be approximated by a cosine function with a 70% drop when the array coupon front surface normal vector is rotated to an angle from 15° to 90°. It was also determined in subsequent tests with two electron number densities of Ne = 0.5 · 106 cm-3 and 1.0 · 106 cm-3 that electron current collection does not depend on the sample temperature. View full abstract»

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  • Surface Catalytic Effect of Electrode Materials on Ozone Dissociation in a Cylindrical Dielectric Barrier Discharge Ozonizer

    Publication Year: 2012 , Page(s): 2751 - 2755
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    The effect of electrode materials on ozone dissociation is studied by using the electrodes made of stainless steel, copper, and carbon in a coaxial cylindrical-type dielectric barrier discharge ozonizer. The gas and electrode surface temperatures as well as the ozone concentration generated in the ozonizer are measured with varying the applied pulse voltage. The results show that the surface temperature for a stainless steel electrode decreases sharply by more than 10°C as the discharge begins to generate ozone. This is explained reasonably by the dissociation of ozone at the catalytic stainless steel electrode surface, which takes away a large amount of heat from the electrode surface. The decrease of temperature for the less catalytic copper electrode is only about 3°C , and the temperature remains almost unchanged for the noncatalytic carbon electrode. Moreover, the ozone concentrations with the copper and carbon electrodes are approximately twice as high as that with the stainless steel electrode at the same voltage. This is attributed to a decrease in catalytic dissociation of ozone at the copper and carbon electrode surfaces, thus affecting the ozone yield. View full abstract»

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  • Surface Modification of DLC Film Due to Oxygen-Plasma Exposure, Observed by IR Absorption Spectroscopy in Multiple-Internal-Reflection Geometry

    Publication Year: 2012 , Page(s): 2756 - 2761
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    We investigated the surface modification of diamond-like carbon film during its exposure to oxygen plasma, at different substrate temperatures. Observation of infrared spectral changes reveals that, during plasma exposure, OH groups are formed in the film. With increasing substrate temperature, OH formation suppresses, and hydrogen content decreases. Thus, we speculate that, with increasing temperature during the exposure, insertion of oxygen into C-H bonds decreases, and hydrogen abstraction from the film increases. View full abstract»

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  • A Long Pulse Relativistic Klystron Amplifier Driven by Low RF Power

    Publication Year: 2012 , Page(s): 2762 - 2766
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    Higher order modes self-excitation can seriously degrade klystron performance and cause pulse shortening in the high-gain relativistic klystron amplifier. In order to suppress higher order modes self-oscillation in the device, some special measures are taken to increase the threshold current of such modes. An output power of 1.02 GW with an efficiency of 24.3% and a gain of 53.7 dB is obtained in the simulation with an input power of 4.3 kW and a frequency of 2.88 GHz. The experiment is performed on the linear transformer driver. Under conditions of an RF power of 30 kW, the peak output power has achieved 1.2 GW, with an efficiency of 28.6% and a gain of 46 dB; the corresponding pulse length is 120 ns. View full abstract»

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  • Two-RF-Driver-Based Negative Ion Source for Fusion R&D

    Publication Year: 2012 , Page(s): 2767 - 2772
    Cited by:  Papers (2)
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    Inductively coupled radio-frequency (RF)-based multidriver negative ion sources form the basis of the ion sources for neutral beam injectors considered for present-day fusion devices. Information on the operational behavior of such multidriver RF sources is limited. Thus, an Indian program on the development and operation of such multidriver sources has been initiated to support and enhance the existing information and thus contribute to the successful development of the large-size multidriver ion sources. Experiments initiated under this program have the objective of understanding the physics and technology of plasma production and its control in the presence of the multidriver coupling. An experimental system consisting of a two-driver-based source powered by a single 1-MHz 180-kW RF generator has been configured for the purpose. It is foreseen that, in the proposed configuration of the source, a plasma of density on the order of 1018 m-3 in a volume about 0.5-m3 chamber shall be produced, and under cesiated conditions (Cs vapor injected into the source), a negative hydrogen ion current on the order of 10-12 A can be extracted at 50 kV. Adequate flexibility has been incorporated in the system design to test the source performance in air or under vacuum. The experiment is supported by extensive optical-, thermocouple-, and probe-based diagnostics to provide information related to the essential plasma parameters such as uniformity, temperature, density, and impurity level. View full abstract»

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  • Modeling Facility Effects on Secondary Electron Emission Experiment

    Publication Year: 2012 , Page(s): 2773 - 2780
    Cited by:  Papers (2)
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    Secondary electron emission is one of the most fundamental problems in spacecraft charging. An accurate prediction of secondary electron yield at low-energy electron impingement has long been a challenging problem due to both the complexity of the process and the difficulty in carrying out accurate measurements in a vacuum chamber. This paper discusses a correlated modeling and experimental study to investigate the facility effects on secondary electron emission yield measurement in a vacuum chamber. View full abstract»

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  • Special issue on vacuum discharge plasmas

    Publication Year: 2012 , Page(s): 2781
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  • Special Issue on Spacecraft Charging Technologies

    Publication Year: 2012 , Page(s): 2782
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  • Open Access [advertisement]

    Publication Year: 2012 , Page(s): 2783
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  • Proven powerful [advertisement]

    Publication Year: 2012 , Page(s): 2784
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  • IEEE Transactions on Plasma Science information for authors

    Publication Year: 2012 , Page(s): C3
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Aims & Scope

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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Meet Our Editors

Editor-in-Chief
Steven J. Gitomer, Ph.D.
Senior Scientist, US Civilian Research & Development Foundation
Guest Scientist, Los Alamos National Laboratory
1428 Miracerros Loop South
Santa Fe, NM  87505  87505  USA
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